ISSN 1880-8468
Technical Report ofInternational Development Engineering࿖㓙㐿⊒Ꮏቇႎ๔TRIDE-2006- 01

February 20, 2006

Abstracts of Master Theses
Presented in February 2006

Department of International Development Engineering,
Graduate School of Science and Engineering,Tokyo Institute of Technology
http://www.ide.titech.ac.jp/TR

Technical Report of International Development Engineering
TRIDE-2006-01
Table of Contents
巻頭言 Preface (in Japanese)··················································································································· 太田秀樹 Hideki OHTA 1
A Study on the Decomposition of Nitrous Oxide over Titania Supported Metal Catalysts························································································································· Kiyoto YANAGIDA 3
Investigation of Natural Zeolite-based Catalyst Activity toward Soot Oxidation···················································································································· Winarto KURNIAWAN 7
A Study on the Selective Catalytic Reduction of NO by Metal Oxides Supported on Titania·····································································································································Cunfu TANG 11
A Study on New Approach to Prepare CoMo / Al2O3Catalyst for Deep Hydrodesulphurization·································································································································· Haibo ZHANG 15
Improvement of Rubberwood Process Using the Thermally Treated Products from Wood Residue·························································································································· Shunsuke KONISHI 19
Enzymatic Treatment of Phenol Waste Water with Thermo-Responsive Chitosan······················································································································ Shuichi KAWATOKO 23
Extraction of Coal Tar Absorption Oil by a Continuous Counter Current Spray Column········································································································································ Jun SAITO 27
Preparation and Structure Control of Plasma Polymerized Films by Utilizing Afterglow Region in
Atmospheric Non-thermal Plasma·································································································································· Takuo MIURA 31
Numerical Analysis for Solidification of Melt Plastic with a Spectral Finite Difference Scheme······································································································································Aya FUJITA 35
The Effect of Probe Shape and Wettability for Expanding Applicability of Micromanipulation Using
Capillary Force···························································································································· Kenichi J. OBATA 39
A Manipulation Method of a Dielectric Micro-Particle by Electrostatic Force·········································································································································· Min HAN 43
Beneficial 2-Way International Cooperation between Japan and Developing Countries in Asia:
Technology Transfer of Welding Technology Case Study·····················································································································Bruno Martins BRAGA 47
A Study on Plastic Deformation Mechanism without Dislocations in Metals by Transmission Electron
Microscopy································································································································· Hidetoshi FUJII 51
Study of Mahalanobis Metric··································································································································· Naoya INOUE 55
Study of Improvement of Kernel Sample Space Method································································································································ Chenghan PIAO 59

I

Support Vector Machine with Asymmetric Kernels··········································································································································· Shen LIU 63
Moving Picture Coding with Pixel Motion Compensation Prediction····················································································································· Takayuki SHINOZAKI 67
Propagation Paths Measurement System for Electronic Toll Collection Systems (ETC)·························································································································Yumihiko ANNAKA 71
Analysis of Radio Wave Propagation in Highway Electronic Toll Collection Gate······································································································································Junsheng LU 75
Location Estimation for Wild Animals····································································································································· Jun-ichi ABE 79
Investigation of the Wave Scattering Characteristics by Using Physical Optics Approximation··············································································································· Navarat LERTSIRISOPON 83
Sorption and Flushing Characteristic of Heavy Metal Ion Response to Sand································································································································Masatoshi AOKI 87
Possible Mechanism of Hydraulic Fracturing Initiation························································································································ Emiko TAKAHASHI 91
Proposed Design Method of Cathodic Protection for Reinforced Concrete Member under Chloride
Attack································································································································Keiyu KAWAAI 95
Influence of Chloride Ion And ITZ around Horizontal Steel Bars on the Corrosion of Steel Bars inConcrete······································································································································ Yang SONG 99
Seasonal and Diurnal Fluxes of Momentum, Energy, Water Vapor and CO2 over Tokyo Bay······································································································································ Ryoko ODA 103
Turbulent Flow Similarity in Open Air Scaled Models for Urban Micro Meteorology························································································································· Masahiko KANEGA 107
Observation Study on Water [nd Heat Transfer Processes in Urban Sewage System····························································································································· Yu NAKAYAMA 111
Airport Capacity Analysis Considering Terminal Air Traffic Flow Control and Airlines’ Aircraft
Sizing Behavior······························································································································ Naoki YAMADA 115

IITechnical Report of International Development Engineering

TRIDE-2006-01, February 20, 2006 (ISSN 1880-8648)

巻頭言 Preface
国際開発工学専攻長

太田秀樹

Hideki OHTA, Head, Department of International Development Engineering
東京工業大学の工学部に、開発システム工学科が発足して 10 年たった。大学院には国際開発工学専攻が設置されて、学部から大学院までの一貫した体制がつくられ、特定の既存分
野に偏ることなく、工学分野を広くカバーするため、いろいろな専門性をもった教員が集められた。学生も、日本人学生と外国人学生が半分ずつという構成である。「(1) アジア向け工学技術者の養成・(2) アジア人と日本人の混在教育・(3) 基幹４科目の専門教育とその連携・(4) 文化・歴史・ディベートなどの相互文化理解」という理念をかかげて、それを追求する体制である。
野心的な試みであったが、着実に教育・研究上の成果をあげてきた。教員ならびに学生が大変な努力をして、教育・研究上のあたらしい試みを実施し、実績を積み上げてきたのが国際開発工学専攻である。こういった 10 年間の蓄積をふまえて、新たな機運が教員のあいだで盛り上がってきた。10 年の節目を契機に、「国際開発工学」という学問分野そのものを創りあげよう、というわけである。学問上の新たな目標として、「国際開発工学」とは何であるかを追求したい。具体的な研究成果を公表することで、「国際開発工学」のあるべき実体をしめす努力をしようという機運が熟した。
ひとくちに「国際開発工学」といっても、その実体はあいまいである。取り扱う内容が多岐にわたるうえ、既存の工学分野との協働が不可欠であるから、試行錯誤の連続から出発することになるであろう。そういった努力を公表する場として、ここに「国際開発工学報
告 Technical Report of International Development Engineering (TRIDE)」を創刊する。
「国際開発工学」創出の学問的努力のなかから、従来の既存分野にはなかった全く新しい概念がつぎつぎと誕生することを期待したい。

1Technical Report of International Development Engineering

TRIDE-2006-01, February 20, 2006 (ISSN 1880-8648)

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Technical Report of International Development Engineering

TRIDE-2006-01, February 20, 2006 (ISSN 1880-8648)

A study on the decomposition of nitrous oxide over titania supported metal catalysts
Student Number：04M18185

Name：Kiyoto YANAGIDA Supervisor：Hirofumi HINODE

チタニア担持金属触媒による N2O 分解栁田 希与人
本研究では、チタニア担持金属触媒（銅、鉄、マンガン、ニオブ）の N2O 分解活性について検討した。チタニア担持銅触媒とチタニア担持鉄触媒は、反応温度 650℃において N2O をほぼ完全に分解した。また、チタニア担持銅触媒の N2O 分解における担体チタニアの影響について検討したところ、最適銅担持量はチタニアの比表面積に比例し、ルチル構造を有するチタニアが有効であることがわかった。
temperature for one day followed by 24hours drying up at 60℃. Then the catalysts
were calcined at 600℃ for 5 hours under air
flow. In order to reduce pressure drop, thecatalysts were pelletized, crushed and sieved
to between 0.71mm to 1.00mm. The
following nomenclatures for the catalyst
samples are used: Cu(xwt%)/TiO2 y where xmeans Cu loading levels, and y represent
reference
supportnumber(e.g.
Cu(1wt%)/TiO2 ① means JRC-TIO-1 withCu loading of 1wt%).
The sources of Fe, Mn and Nb were
(99.9%,Wako
Co.),
Fe(NO3)3⋅9H2O
MnCO3⋅nH2O (99.9%, Wako Co.) and(CBMM),
NH4[NbO(C2O4)2(H2O)2]⋅nH2O
respectively.

1. Introduction
Nitrous oxide (N2O) is one of the powerfulgreenhouse gases with a global warming
potential per molecule of about 300 times
that of carbon dioxide (CO2). N2O is also
identified as a contributor to the destructionof ozone layer in the stratosphere. Therefore,
it is important to study decomposition of
N2O from the environmental point of view.
Recently, a considerable number of studies
have been conducted on the catalytic
decomposition and the selective catalytic
reduction of N2O [1-8].
In our laboratory, selective catalytic
reduction of NO to N2 over TiO2 supported
metal catalysts in the presence ofhydrocarbon had been studied, and TiO2
supported metal catalysts had shown a good
activity [9]. In the reaction of NO to N2, N2O
is produced only at low temperature region
and not at high temperature region. From
this result, it can be interpreted that N2O
produced from NO reduction is completely
decomposed at high temperature region. It
was assumed that TiO2 supported metal
catalysts will also show a good activity forN2O decomposition. And another advantage
for using TiO2 as a support is the hightolerance to water vapor, which is an
importantcharacteristicfor
N2O
decomposition catalyst.
In this research, the decomposition of N2O
over TiO2 supported various metal catalysts
was investigated.

2.2 Catalytic activity experiment
The catalytic reaction was carried out in a
fixed-bed flow reactor under atmosphericpressure, and the reactant gas was preparedby mixing N2O, O2 and He as a balance gas.
Then the mixed gas of 1000ppm N2O, 10%
O2 and He was fed to the catalyst at flowrate of 5.0-6.0ml/s, which correspond to16000h-1 of space velocity. Water vapor was
introduced by using the bubbling system,and the concentration of water vapor wasapproximately 5vol%.
Gas chromatography (GC323w; GL
Science Co., with Porapak N, Porapak Q and
Molecular Sieve 13X column) was used toanalyze N2O, N2 and O2.
2.3 Catalyst characterization
Characterizationofcatalyst
was
performed by XRD (MultiFlex; Rigaku) andBET (SA3100; COULTER).

2. Experimental
2.1 Catalyst preparation
M/TiO2 (M=Cu, Fe, Mn, Nb) catalysts wereprepared by impregnation method. TiO2
(JRC-TIO-1, 2, 4, 5 and 6; reference catalyst,
Catalysis Society of Japan) were used as
supports.
In the case of preparation of Cu/TiO2, TiO2
was impregnated in an aqueous solution ofCu(NO3)2⋅3H2O (99.9%, Wako Co.). Each of
the solutions was stirred at room

3. Result and discussion
3.1 The activity for the decomposition of N2O
over M/TiO2④ (M = Cu, Fe, Mn, Nb)
Figure 1 shows the catalytic activity of
M/TiO2④ (M=Cu, Fe, Mn, Nb) catalysts for3

Technical Report of International Development Engineering

TRIDE-2006-01, February 20, 2006 (ISSN 1880-8648)

N2O decomposition. The loading level foreach sample here was selected from theloading level of the sample with the best
performance result.
The product of NO and NO2 were notdetected in all condition.

optimum Cu loading levels of Cu/TiO2
prepared from JRC-TIO-1, 2, 4 and 6 were
10wt%, 1wt%, 5wt% and 5wt%, respectively.
The difference of the optimum Cu loadinglevel was considered to be related with thedifference of the specific surface area of each
TiO2.

80

100

TiO2④
Cu(5wt%)/TiO2④
Fe(1wt%)/TiO2④
Mn(5wt%)/TiO2④
Nb(5wt%)/TiO2④

Cu(1wt%)/TiO2①
Cu(5wt%)/TiO2①
Cu(10wt%)/TiO2①

N2O conversion to N2 (%)

N2O conversion to N2 (%)

100

80

60

60

40

40

20

20

0
300

400

500

600

700

800

0

Temperature (℃)

300

400

500

600

700

800

Temperature (℃)

Fig.1 Comparison of the catalytic activity for thedecomposition of N2O over each catalyst

Fig.2 The catalytic activity for the decompositionof N2O over Cu/TiO2①

Parent JRC-TIO-4 calcined at 600 ℃
decomposed only 34% of N2O to N2 even at
700 ℃ , however when the copper was
supported on TiO2, the catalytic activity was
promoted. When Cu loading level was 5wt%,
the highest catalytic activity for thedecomposition of N2O was achieved.
Decomposition of N2O to N2 overCu(5wt%)/TiO2④ catalysts began at 400℃,
and the conversion of N2O to N2 reached100% at 650℃. Fe(1wt%)/TiO2④ completely
decomposed N2O at 650℃.
Mn(5wt%)/TiO2 ④ and Nb(5wt%)/TiO2 ④
decomposed only approximately 50% of N2Oeven at 700℃.
Copper showed better activity for N2O
decomposition than the other active metals,
Fe, Mn and Nb. Therefore, Cu/TiO2 was used
for the next investigations.

N2O conversion to N2 (%)

100

80

Cu(0.5wt%)/TiO2②
Cu(1wt%)/TiO2②
Cu(5wt%)/TiO2②
Cu(10wt%)/TiO2②

60

40

20

0
300

400

500

600

700

800

Temperature (℃)
Fig.3 The catalytic activity for the decompositionof N2O over Cu/TiO2②

N2O conversion to N2 (%)

100

3.2 The effect of TiO2 as support
In order to study the effect of TiO2 as
support on the catalytic activity of Cu/TiO2
for N2O decomposition, Cu/TiO2 catalysts
were prepared from JRC-TIO-1, 2, 4, 5 and 6.
The relationship between the optimum Culoading level of Cu/TiO2 and the specificsurface area of TiO2 support and also
between the catalytic activity and the
crystal structure of TiO2 were evaluated.
Figures 2 to 5 show the catalytic activityof Cu/TiO2 for N2O decomposition preparedfrom JRC-TIO-1, 2, 4 and 6, respectively.
From the results of Figures 2 to 5, the

80

TiO2④
Cu(1wt%)/TiO2④
Cu(5wt%)/TiO2④
Cu(10wt%)/TiO2④

60

40

20

0
300

400

500

600

Temperature (℃)

700

Fig.4 The catalytic activity for the decompositionof N2O over Cu/TiO2④4800

Technical Report of International Development Engineering

TRIDE-2006-01, February 20, 2006 (ISSN 1880-8648)

Table 1 shows the relationship between
the BET specific surface area of TiO2 and the
optimum Cu loading level of Cu/TiO2 fromthe catalytic activity experiments for N2O
decomposition and geometrical calculationfrom CuO and Cu(NO3)2 projected area.
The results from Table 1 indicate that the
optimum Cu loading level of Cu/TiO2
obtained from the catalytic activity
experiments was agreed well with on thecalculated value from the projected area of
CuO. Therefore, when the TiO2 surface wascovered with CuO molecule completely, thecatalytic activity for the decomposition of
N2O reached the highest value. If theamount of CuO loaded exceeded the
optimum loading, the catalytic activity
remained the same or declined because of
sintering of copper.
Figure 6 shows comparison of the catalytic
activities over Cu/TiO2 prepared from
JRC-TIO-1, 2, 4, 5 and 6. The Cu loadinglevel for each sample here was selected fromloading level of the sample with the best
performance result.

N2O conversion to N2 (%)

100

80

TiO2⑥
Cu(1wt%)/TiO2⑥Cu(5wt%)/TiO2⑥
Cu(10wt%)/TiO2⑥

60

40

20

0
300

400

500

600

700

800

Temperature (℃)
Fig.5 The catalytic activity for the decompositionof N2O over Cu/TiO2⑥

The BET specific surface areas of
JRC-TIO-1, 2, 4, 5 and 6 were 82.0m2/g,
15.9m2/g, 52.9m2/g, 1.24m2/g and 73.0m2/g,
respectively. The projected area of one
molecule of CuO on the surface of TiO2 was
calculated by using the radius of Cu2+ ion
and O2- ion and the bonding distance of Cu-O
molecule (Cu2+：0.69Å, O2-：1.40Å, Cu-O：
1.95Å). The projected area of one moleculeof CuO on the surface of TiO2 was calculated
to approximately 7.59 Å 2 by using thegeometrical equation in Eq.1.

−1.40

1.40 − x dx + ∫
2

2

2.64

1.355

0.69 − ( x − 1.95) dx
2

2

N2O conversion to N2 (%)

S=∫

1.355

100

(Eq.1)

However, during impregnation, it was
Cu(NO3)2 rather than CuO that wasdispersed and loaded on the surface of TiO2.
Therefore the projected area of Cu(NO3)2 on
TiO2 surface was also calculated. When thesurface of TiO2 was assumed to be uniform
and, covered with CuO or Cu(NO3)2
monolayer, the necessary amount of CuO or
Cu(NO3)2 molecule to make one full layer on
the TiO2 surface could be calculated.

80

Cu(10wt%)/TiO2①
Cu(1wt%)/TiO2②
Cu(5wt%)/TiO2④
Cu(0.5wt%)/TiO2⑤Cu(5wt%)/TiO2⑥

60

40

20

0
300

400

500

600

700

800

Temperature (℃)
Fig.6 The catalytic activity for the decompositionof N2O over Cu/TiO2 prepared from each TiO2

Table 1 Relationship between specific surface area of TiO2 and optimum Cu loadinglevel for the decomposition of N2O

Support
JRC-TIO-1
JRC-TIO-2
JRC-TIO-4
JRC-TIO-5
JRC-TIO-6

Optimum Cu loading level (wt%)

Specific surface
area (m2/g)

Experimental data

82.0
15.9
52.9
1.24
73.0

10
1
5
0.5
5
5

Geometrical

Geometricalcalculation of CuO

calculation of Cu(NO3)2

11.4
2.21
7.35
0.172
10.1

2.25
0.436
1.45
0.03402.00

Technical Report of International Development Engineering

TRIDE-2006-01, February 20, 2006 (ISSN 1880-8648)

The catalytic activity of Cu(1wt%)/TiO2②
⑤ for
the
and
Cu(0.5wt%)/TiO2
decomposition of N2O were the lower thanthe other catalysts in this experiment. The
small specific surface area and the low Cu
loading level were considered as the causesof the low activity of Cu(1wt%)/TiO2② andCu(0.5wt%)/TiO2⑤.
Cu(5wt%)/TiO2 ④ and Cu(5wt%)/TiO2 ⑥
hadhighercatalytic
activitythanCu(10wt%)/TiO2①.
Figure 7 shows the results of XRD
patterns of Cu/TiO2 catalyst with the
optimum loading level.

system of Cu/TiO2.

N2O conversion to N2 (%)

100
Cu(5wt%)/TiO2④
Cu(5wt%)/TiO2④ with H2O

80

60

40

20

0
300

400

500

600

700

800

Temperature (℃)

Cu(5wt%)/TiO2⑥

Fig.8 The influence of water vapor on the catalytic
activity of Cu(5wt%)/TiO2④ for N2O decomposition

4. Conclusion
Cu(5wt%)/TiO2 ④ and Fe(1wt%)/TiO2 ④
exhibited the catalytic activity for N2O
wasdecomposed
decomposition.
N2O
completely at 650℃.
If the BET specific surface area of TiO2
support was larger, the optimum Cu loadinglevel of Cu/TiO2 was higher. When TiO2
surface was covered with CuO completely,
the catalytic activity for the decomposition of
N2O reached the highest value.
The rutile structure was considered to be
more effective for the decomposition of N2O
than anatase structure.
The presence of water vapor did not
influence this catalytic system of Cu/TiO2 forN2O decomposition.

Intensity(a.u.)

Cu(0.5wt%)/TiO2⑤Cu(5wt%)/TiO2④

Cu(1wt%)/TiO2②

Cu(10wt%)/TiO2①

10

20

30
40
50
60
2θ(deg.)Fig.7 XRD patterns of Cu/TiO2 prepared from each
TiO2 (●：anatase、▲：rutile、■：CuO)

It can be seen from figure 6 and figure 7
andthat that both Cu(5wt%)/TiO2 ④
Cu(5wt%)/TiO2 ⑥ that constitute of rutile
structure exhibited higher activity for N2O
decomposition than Cu(10wt%)/TiO2① that
constitutes of anatase.
Therefore, the rutile structure wasconsidered to be more effective for thedecomposition of N2O than anatasestructure.

Reference[1] J.Haber, et al., Catal. Today, 90 (2004)
15.
[2] A. Dandekar and M.A. Vannice, Appl.
Catal. B, 22 (1999) 179.
[3] J. Lin, et al., Appl. Surf. Sci., 103 (1996)
307.
[4] Javier Perez-Ramirez and Freek
Kapteijn, Cat. Com., 4 (2003) 333.
[5] Shin-ichi Tanaka, et al., Catal. Today, 63(2000) 413.
[6] T. Chaki, et al., J.Catal., 218 (2003) 220.
[7] C. Pophal et al., Appl. Catal. B, 16(1998) 177.
[8] Liang Yan et al., Appl. Catal. B, 45(2003) 85.
[9] J. Mitadera and H. Hinode, Appl.Catal.
B, 39 (2002) 205

3.3 The influence of water vapor
Figure 8 shows the influence of water
vapor on the catalytic activity ofCu(5wt%)/TiO2 ④ for N2O decomposition.
The difference of the catalytic activity forN2O decomposition was not observed at all.
Even though many catalysts for thedecomposition of N2O were reported to show
lower activity in the presence of water vapor,this result indicates that the presence ofwater vapor did not influence this catalytic

6Technical Report of International Development Engineering

TRIDE-2006-01, February 20, 2006 (ISSN 1880-8648)

Investigation of Natural Zeolite-based Catalyst Activity toward Soot Oxidation
Winarto KURNIAWAN (04M18200)

Research Advisor: Prof. Hirofumi HINODE

天然ゼオライト系触媒の煤酸化活性に関する研究
Abstract
インドネシア産天然ゼオライト、ベントナイト及び両者を修飾した試料（塩基処理、ナトリウム担持、硝酸ナトリウム担持）の煤酸化に対する活性について熱重量分析による最高酸化温度低下量（∆T）によって検討した。触媒のキャラクタリゼーションはＩＣＰ、ＸＲＤ、ＳＥＭ−ＥＤＸで行った。天然ゼオライト
及びベントナイトは ∆T がそれぞれ約１０及び２０℃と活性は低かったが、修飾することにより活性が向上した。最も活性が高く安定性もある触媒は４M 及び６M の水酸化ナトリウムで処理したベントナイトであり、両者は１８５℃の ∆T を示した。触媒の中に含まれているアルカリ金属がその高い活性に貢献したと考えられる。

to investigate its activity toward soot oxidation. Based

1. Introduction
Soot from diesel engine exhaust can cause severeon the facts above, it is necessary to investigate thehealth problems. Soot can penetrate into lung andpotentiality of zeolite as catalyst for soot oxidation.

[1]

gives rise to carcinogenic effects . Due to its harmful

In this research, the catalytic activities toward

property, it is essential to develop improved pollution

soot oxidation of Indonesian natural zeolite (Zeolite

control equipment that can address soot emission

Lampung) and also natural bentonite (Bentonite

problem from diesel engines, for example by using

Bandung), which often be found together with zeolite,

catalyst to oxidize soot into carbon dioxide.

were investigated. Both were tested for their activity

Removal of soot by means of oxidation requires

before and after treatment. Treatment methods usedhigh temperature because typical soot oxidation starts

were alkali treatment, NaNO3 loading, and Na loadingfrom around 650°C. On the other hand, diesel engine

methods.

exhaust gas temperature is in the range of 150 to
400°C[2]. Therefore, an active catalyst to lower soot

2. Materials and Methods

oxidation temperature down to diesel engine exhaust

2.1 Materials
Catalyst materials were Zeolite Lampung (mainly

gas temperature range is required.
One of the promising materials that can be usedconsists of clinoptilolite) and Bentonite Bandung.

as catalyst is zeolite. Compared to other materials,

Alkaline solution for alkali treatment method was

zeolite possesses several advantages, i.e. it is resistant

NaOH (Wako Pure Chemical Industries Ltd.).

to thermal recursion and the spent catalyst presents

Precursor for NaNO3 loading and Na loading methods

less disposal problem. On the other hand, zeolite also

was NaNO3 (Wako Pure Chemical Industries Ltd.).

has disadvantage, which is its low hydrothermal

BP3700 (Cabot Chemical Company Ltd.) was used as[3][4][5]stability

model soot.

.

In Indonesia, natural zeolite exists in abundance

2.2 Catalyst Preparation

throughout wide area. Although the utilization of thisAlkali treatment method

natural zeolite in the area of catalysis has been

Materials were stirred into alkaline solution for

examined deeply, so far there is no research performed

24 hours at room temperature. Materials were then7Technical Report of International Development Engineering

TRIDE-2006-01, February 20, 2006 (ISSN 1880-8648)

washed, dried, and calcined at 600ºC for 3 hours in air.

temperature at which soot oxidation at the fastest. It

NaNO3 loading method

can be seen that raw natural zeolite and bentonite
showed a low activity toward soot oxidation, with ∆T

Materials were impregnated in NaNO3 solution
for 24 hours, and then dried at 80ºC for 24 hours.

of 10°C and 20°C, respectively. Treatment with

NaNO3 loading method

alkaline solution has proven to increase the activity ofMaterials were impregnated in NaNO3 solution

the catalysts. In the case of zeolite, the concentrationfor 24 hours. Materials were then dried at 80ºC for 24

of NaOH used did not influence activity of catalysts

hours and calcined at 600ºC or 750ºC for 5 hours insignificantly. Zeolites treated with 0.1 M, 1 M, and 2

air.

M of NaOH exhibited similar activity. In the case of

2.3 Activity Test

bentonite, an increase in NaOH concentration used

The activity tests were carried out insideresulted in the increase of activity of catalysts.

thermobalance (Thermoplus TG-8210, Rigaku Corp.).

However, as the concentration of NaOH reached 4 M,

The samples were prepared by mixing soot andincrease in concentration did not influence the activity.

catalyst in tight mode (soot and catalyst were grinded

It was thought that the activity of bentonite has

together in agate mortar to achieve close contact[6]),reached its maximum value after treatment with 4 M

with soot to catalyst ratio of 1:10. Platinum crucibleof NaOH.

was used for sample container. Samples were heated to

The catalysts that showed the highest activity

750°C with temperature increase rate of 10°C/min. To

while still exhibiting good stability at high temperaturegive an oxidizing atmosphere, air was flowed throughwere bentonite treated with 4 M and 6 M of NaOH.

the thermobalance at flow rate of 100 mL/min.

Both catalysts showed ∆T of 185°C.

Activities of developed catalysts were evaluatedNa-loaded zeolite with loading level of 20%

from thermogravimetry data in terms of the decrease

showed a ∆T of 205°C, higher than the former twoof soot oxidation temperature (∆T), which is thecatalysts. However, this catalyst was found to havedifference between the temperature of peak ofmelted concurrently with soot oxidation.
NaNO3-loaded zeolite and bentonite (for both

catalyzed soot oxidation and that of uncatalyzed one.

loading levels of 10% and 20%) showed ∆T of 240°C,

2.4 Catalyst Characterization
Catalyst characterization was performed using

the highest ∆T in this research. However, it was foundpowder X-ray diffraction (XRD, Multiflex X-ray

that the catalysts were also exhibited weight loss

Diffractor,

during catalytic process, which showed that these

RigakuCo.),

Inductively

PlasmaSpectroscopy (ICP, SPS7800, Seiko Instruments Inc.),

catalysts have low stability at high temperature.

and Energy Dispersive X-ray Spectroscopy (EDX,

3.2 Catalyst Characterization

SEM-EDS JSM-5310LV, JEOL Ltd.).

The XRD patterns of selected catalysts are shownin Fig. 3. It can be seen that bentonite treated with 4 M

3. Result and Discussion

and 6 M of NaOH exhibited weaker spectra compared

3.1 Activity Test

to bentonite treated with lower concentration NaOH.

The activity of developed catalysts is shown in

These weak spectra were thought to be caused by

Fig. 1 and 2. Horizontal axis indicates temperature,

destruction of some bentonite structure in the catalyst.

while

differential

Data from EDX analysis supports this hypothesis, in

termogravimetry (DTG, weight loss of sample per unit

which the weight fraction of Al and Si decreased intime). Peak of DTG curve corresponds to theboth materials. EDX analysis also shows higher Na

verticalaxis

corresponds

to8Technical Report of International Development Engineering

TRIDE-2006-01, February 20, 2006 (ISSN 1880-8648)

weight fraction on these materials, which was thought

Therefore, it can be concluded that NaNO3 exists on

to contribute to the increase of their catalytic activity.

the surface of these catalysts and that high activity and

NaNO3-loaded

zeoliteandbentonite

low thermal stability of these catalysts could beshow

attributed to the existence of this compound.

additional XRD spectra, which belong to NaNO3.

0.1
0
-0.1

DTG (wt.% of BP3700/s)

-0.2
-0.3

BP3700BP3700 - zeolite-0.4BP3700 - Na(1%)/zeolite-0.5BP3700 - Na(10%)/zeolite-0.6BP3700 - Na(20%)/zeolite
BP3700 - NaNO3(10%)/zeolite-0.7BP3700 - NaNO3(20%)/zeolite-0.8BP3700 - zeolite-NaOH(0.1 M)
BP3700 - zeolite-NaOH(1 M)-0.9

BP3700 - zeolite-NaOH(2 M)

-1.0
0

100

200

300

400

500

600

700

800

Temperature (ºC)

Fig. 1 Comparison of zeolite-based catalysts activity toward soot oxidation

0.1
0DTG (wt.% of BP3700/s)-0.1

BP3700-0.2BP3700 - bentonite-0.3

BP3700 - Na(1%)/bentonite
BP3700 - Na(10%)/bentonite-0.4

BP3700 - Na(20%)/bentonite-0.5

BP3700 - NaNO3(10%)/bentonite-0.6

BP3700 - NaNO3(20%)/bentonite
BP3700 - bentonite-NaOH(0.1 M)-0.7

BP3700 - bentonite-NaOH(1 M)-0.8

BP3700 - bentonite-NaOH(2 M)-0.9

BP3700 - bentonite-NaOH(4 M)
BP3700 - bentonite-NaOH(6 M)

-1.0
0

100

200

300

400

500

600

Temperature (ºC)

Fig. 2 Comparison of bentonite-based catalysts activity toward soot oxidation
9

700

800

Technical Report of International Development Engineering

TRIDE-2006-01, February 20, 2006 (ISSN 1880-8648)

NaNO3

Intensity (a.u.)

NaNO3/bentonite (10%)

NaNO3/zeolite (10%)
Bentonite NaOH-treated (6 M)
Bentonite NaOH-treated (4 M)
Bentonite NaOH-treated (2 M)
Natural bentonite preheated
Natural zeolite preheated
0

10

20

30

40

50

60

2θ (º)

Fig. 3 XRD spectra of selected catalysts
chlorides”, Catal. Comm., 4:591-596 (2003)

4. Conclusion
Indonesia natural zeolite and bentonite showed[2] Galdeano N.F, Carrascull A.L., Ponzi M.I., Lick

low activity toward soot oxidation. Treatment with

I.D., Ponzi E.N.; “Catalytic combustion ofalkali treatment, NaNO3 loading, and Na loading

particulate matter. Catalysts of alkaline nitrates

methods successfully increased the activity of natural

supported on hydrous zirconium”, Thermochim.

zeolite and bentonite. The catalysts with the highest

Acta, 421:117-121 (2004)[3] Wallin

activity that still possessed stability at soot oxidation

M.,

Karlsson

C.J.,

SkoglundhM.,

temperature were bentonite treated with 4 M and 6 M

Palmqvist A.; “Selective catalytic reduction ofof NaOH, with ∆T of 185ºC. Na-loaded zeolite

NOx with NH3 over zeolite H–ZSM-5: Influence(loading level of 20%) showed an even higher activityofwith ∆T of 205ºC. However, this catalyst was found to218:354–364 (2003)

transientammonia

supply”,

J.

Catal.,

melt simultaneously with soot oxidation. The highest[4] Stevenson S.A., Vartuli J.C., Sharma S.B.; “Theactivity was shown by NaNO3-loaded zeolite andeffects of steaming and sodium exchange on the

bentonite with ∆T of 235 ºC. However, these catalysts

selective catalytic reduction of NO and NO2 by

were found to decompose simultaneously with sootNH3 over HZSM-5”, J. Catal., 208:106–113 (2002)

oxidation, making the catalysts unsuitable for practical[5] Pieterse J.A.Z., van den Brink R.W., Booneveld S.,

applications. These high activities were attributed tode Bruijn F. A.; “Durability of ZSM5-supported

the presence of Na species on the surface of catalysts.

Co-Pd catalysts in the reduction of NOx withmethane”, Appl. Catal. B, 39:167-179 (2002)[6] Stanmore B.R., Brilhac J.F., Gilot P.; “The oxidation

References[1] Wang S., Haynes B.S.; “Catalytic combustion ofof soot: a review of experiments, mechanisms andsoot on metal oxides and their supported metalmodels”, Carbon, 39:2247-2268 (2001)10

Technical Report of International Development Engineering

TRIDE-2006-01, February 20, 2006 (ISSN 1880-8648)

A study on the selective catalytic reduction of NO
by metal oxides supported on titania
Student Number: 04M18239

Name: Cunfu TANGSupervisor: Hirofumi HINODE

チタニア担持金属触媒による NO 選択還元湯存福

本研究では、炭化水素を還元剤としたチタニア担持金属(Fe、Mn)触媒による NO 選択還元反応において、触媒の調製方法が触媒還元活性に与える影響を検討した。その中で、Fe2O3 と
Mn/TiO2 の機械的混合触媒の場合、Mn/TiO2 触媒単独のときと比べ、触媒活性が向上した。
Fe/TiO2 及び Mn/TiO2 の二層式触媒においては、触媒層の設置順序の違いが触媒活性に大きな影響を与え、Mn/TiO2 触媒を二層目にした場合、低温側で二種の触媒の相乗効果が得られた。

monoxide by ammonia in the presence of oxygen[4].
In this paper, we investigate the activities of the
M/TiO2 (M=Fe, Mn) catalyst for the HC-SCR of
NO with propene. And we also investigated theinfluences of the catalyst preparation method on
the catalytic reduction activity.

1. Introduction
Nitrogen oxides (NO, NO2) are major sources of
air pollution. Since they cause photochemicalsmog and acid rain. And almost all NOx comefrom automobiles (49%) and power plants (46%)[1]. To reduce the emission of nitrogen oxide thecatalytic technologies are quite attractive becauseof their low cost and high efficiency [1]. Amongthese technologies, the selective catalytic
reduction of NOx with hydrocarbons (HC-SCR)
has attracted much attention, because of it’spotential ability to eliminate NOx emission fromthe oxygen-rich exhaust.
It was suggested by many researchers that the
HC-SCR reaction is carried out by the reaction to
generate NO2 followed by the reaction of NO2
with hydrocarbons [2].
In the case of HC-SCR of NO, propene also
performed high reduction activity [3]. As for thegeneration of CO2, generally the following two
reactions are considered:
4NO+2C3H6+7O2 → 2N2+6CO2+6H2O
2C3H6+9O2 → 3CO2+6H2O

2. Experimental
M/TiO2 (M=Fe, Mn) were prepared byimpregnation method. TiO2 (JRC-TIO-4) andFe(NO3)3・9H2O (or MnCO3・nH2O) were mixed
in 300 ml of ion exchange water. The mixtures
were then stirred at room temperature for one day.
The solutions were dried up at 70℃ for 24 hrs.
Then they were calcined at 600℃ in air for 5 hrs.
Finally, the samples were crushed and sieved to
0.71-1.00 mm. TiO2 (JRC-TIO-4) was supplied
from the Catalysis Society of Japan. Fe(NO3)3・
9H2O and MnCO3・nH2O were purchased from
Wako Pure Chemicals Industries, Ltd.
For the catalyst preparation method, coimpregnation method, consecutive impregnation,mechanical mixing method, and two levels typecatalyst were mainly employed. The co-impregnation
indicated as (M1+M2)/TiO2 is a method toimpregnate two kinds of metals (Fe, Mn) to TiO2

(1)
(2)

Mn/TiO2 and Fe-Mn/TiO2 have been reported
that they were active for the reduction of nitrogen

11Technical Report of International Development Engineering

TRIDE-2006-01, February 20, 2006 (ISSN 1880-8648)

simultaneously. The consecutive impregnation isa method to impregnate two kinds of metals (Fe,Mn) to TiO2 one by one. This method is indicatedas M1-M2/TiO2 where metal M2 is supported
firstly. The mechanical mixing method whichindicated as M1+M2/TiO2 is a method to grind
M2 mecahanically after M1/TiO2 had been
prepared.Two-level type catalyst indicated as
M1/TiO2+M2/TiO2 is a method to pack two kindsof catalysts into quartz glass tube without mixing.
The SCR activity measurement was carried out
in a fixed-bed flow reactor which was equippedwith an electric furnace kept at desired
temperature under atmospheric pressure. 1.0 gramof the catalyst sample was packed into a 6 mm
inner diameter quartz glass tube. The reactant gas
composition was as follows: 1500 ppm NO, 1500
ppm C3H6, 10% O2, and He as a balance gas. The
total flow rate was about 4 ml/s, whichcorrespond to 13000 h-1 of space velocity. The
temperature range of reaction was from 150℃ to
600℃.
NO and NO2 concentrations were analyzed by
NOX analyzer (Shimadzu, NOA-305A). N2O wasanalyzed by gas chromatograph (Shimadzu,
GC-8A). CO2 and CO concentrations wereanalyzed by gas chromatograph (GL Science,
GC-390). Catalysts are characterized by TG-DTA,
SEM-EDS, XRD and, BET.

increased compared to that of single catalyst
Fe(0.5)/TiO2 or Mn(0.5)/TiO2, and when Mn(0.5)/TiO2

was used as the first level catalyst, the maximum
conversion reached 32%. And the maximum
conversion increased to 40% when Fe(0.5)/TiO2
was used as the first level catalyst. Therefore, it
can be concluded that the catalytic reduction
activity improved when a Mn/TiO2 catalyst usedas the second level catalyst.

50
NO
O2
C3H6

NO conversion to N2(%)

401500ppm
10%1500ppmFe(0.5)/TiO2
Mn(0.5)/TiO2
Mn(0.5)/TiO2+Fe(0.5)/TiO2
Fe(0.5)/TiO2+Mn(0.5)/TiO2

SV
13000h‑1
Sample 1.0ｇ

30

20

10

0
100

200

300

400
500
Temperature(℃)

600

700

Fig.1: Catalytic activity of two-level type catalyst(M1/TiO2+M2/TiO2 (M=Fe, Mn)) for the reductionof NO to N2 using C3H6 as a reducing agent

Table 1 and Table 2 show the conversion to N2
and CO2 respectively for two-level type catalyst,
and the total value of single catalysts of Mn/TiO2
and Fe/TiO2 is additionally shown.

3. Results and discussion
Table 1: The comparison of two-level type catalyst

3.1 Catalyst activity

activity for the reduction of NO to N2
Total

Mn/TiO2 at the

Fe/TiO2 at thevalue (%)

first level (%)

first level (%)

200

5.51

3.73

6.74

250

18.97

13.26

15.47

300

45.18

27.98

40.11

325

54.81

32.29

35.04

350

52.66

24.72

25.67

400

28.66

12.25

13.59

450

17.23

7.50

8.25

500

10.97

4.13

4.60

T(℃）

From the activity test result on the effect of metalloading to the catalytic activity, it was known thatthe highest conversion of NO to N2 was shown atmetal loading of 0.5wt.%. The highest
conversions of Fe(0.5)/TiO2 catalyst and Mn(0.5)/TiO2 were 28% and 26% respectively. Thus,
this optimal metal loadings of Fe(0.5)/TiO2
catalyst and Mn(0.5)/TiO2 catalyst were employed
for catalyst preparation mentioned below.
Figure 1 shows the effect of different packing
configuration of two-level type catalyst on
catalyst activity. The conversion of N2 slightly

In the low temperature regions, the two-level

12

Technical Report of International Development Engineering

TRIDE-2006-01, February 20, 2006 (ISSN 1880-8648)

type catalyst that uses Fe/TiO2 catalyst at the firstlevel, showed similar degree of conversion of N2
and CO2 as that of single catalysts of Mn/TiO2
and Fe/TiO2 added together at the same
temperature.It can be thought that reduction of
NO to N2 occurred in the two level of catalytic
beds together. Therefore, it can be concluded thatthe synergy effect of two catalysts was observedin the low temperature regions.

influence on the catalytic activity was
insignificant. In the case of a mechanical mixing
catalyst and a two-level type catalyst, the catalytic
activity significantly increased. Two-level typecatalyst showed the highest activity among thecatalysts developed in this research.
The conversions of NO2 and CO2 are shown in
Fig.3 and Fig.4.
60

Table 2: The comparison of two-level type catalyst
activity for the reduction of C3H6 to CO2
Mn/TiO2 at the

Fe/TiO2 at The

value (%)

first level (%)

first level (%)

200

2.57

4.65

4.85

250

11.90

8.64

10.48

300

53.18

31.17

49.78

325

97.05

57.98

75.19

350

(100.00)

74.55

84.67

400

(100.00)

93.41

98.40

450

(100.00)

99.02

100.00500(100.00)

100.00100.00NO conversion to NO 2(%)

Total

T(℃）

50

40

20

30

NO
O2
C3H6

10

300

400
500
Temperature(℃)

600

600

700

SV
13000h‑1
Sample 1.0ｇ
60

40

0
100

200

400
500
Temperature(℃)

1500ppm
10%1500ppmFe(0.5)/TiO2
Mn(0.5)/TiO2(Fe(0.1)+Mn(0.5))/TiO2
Fe(0.1)‑Mn(0.5)/TiO2
Fe(0.1)+Mn(0.5)/TiO2
Fe(0.5)/TiO2+Mn(0.5)/TiO2

20

20

0
100

300

100

C3H6 conversion to CO 2(%)

NO conversion to N2(%)

40

200

Fig.3: Catalytic activity of catalysts withdifferent preparation method for the reductionof NO to NO2 using C3H6 as a reducing agent

Fe(0.5)/TiO2
Mn(0.5)/TiO2(Fe(0.1)+Mn(0.5))/TiO2
Fe(0.1)‑Mn(0.5)/TiO2
Fe(0.1)+Mn(0.5)/TiO2
Fe(0.5)/TiO2+Mn(0.5)/TiO2

SV
13000h‑1
Sample 1.0ｇ

SV13000h‑1
Sample 1.0ｇ

0
100

60

50

Fe(0.5)/TiO2
Mn(0.5)/TiO2(Fe(0.1)+Mn(0.5))/TiO2
Fe(0.1)‑Mn(0.5)/TiO2
Fe(0.1)+Mn(0.5)/TiO2
Fe(0.5)/TiO2+Mn(0.5)/TiO230801500ppm
10%1500ppm

1500ppm
10%1500ppm

10

Figure 2 shows the conversion of N2 forvarious catalysts prepared by different preparation
method that used in this experiment.

NO
O2
C3H6

NO
O2
C3H6

200

300

400
500
Temperature(℃)

600

700

Fig.4: Conversion of C3H6 to CO2 overcatalysts with different preparation method
under oxidizing atmosphere

700

Fig.2: Catalytic activity of catalysts withdifferent preparation method for the reductionof NO to N2 using C3H6 as a reducing agent

The highest conversion to NO2 was achieved in
the case of co-impregnation catalyst. However,NO conversion was low in the low temperature
region because the combustion of HC, which is
the reducing agent, rapidly occurred according to
the reaction (2). Therefore, the conversion to N2

The catalytic activity slightly increased when
the co-impregnation method was used. In the caseof a consecutive impregnation catalyst, the13Technical Report of International Development Engineering

TRIDE-2006-01, February 20, 2006 (ISSN 1880-8648)

were calcined at the same temperature.

(b)Mn2O3

Intensity(a.u.)

did not increase. When the mechanical mixing
method catalyst or two-level type catalyst wasused, the conversion to NO2 slightly increased
compare to Mn/TiO2 catalyst only. In these cases,
the combustion of HC also occurred similar to thecase of Mn/TiO2 catalyst. Therefore, theconversion to N2 was thought to increase. In thecase of consecutive impregnation, the degree of
conversion to NO2 and CO2 were the same as thatof Mn/TiO2 catalyst. Thus it can also be supposedthat in this case there was no change inconversion to N2 either.

(a)Fe2O3

10

3.2 Characterization of Catalysts

20

30
40
2θ(deg.)50

60

Fig.5: XRD pattern of various metal oxides

The BET surface areas of iron catalysts andmanganese catalysts are summarized in Table 3.

4. Conclusions
Table 3: Specific surface area of various catalysts

Catalysts

Specific Surface
Area [m2/g]

TiO2 (JRC-TIO-4)

49.1

Fe2O3

5.3

Mn2O3

54.2

Fe(0.5)/TiO2

41.8

Mn(0.5)/TiO2

23.4(Fe(0.1)+Mn(0.5))/TiO2

43.6

Fe(0.1)-Mn(0.5)/TiO2

33.6

Mn(0.5) + Fe(0.1) /TiO2

33.2

Fe(0.1)+Mn(0.5)/TiO2

38.3

In the case of two-level type catalyst, the packing
order influenced on the catalytic activity. An
active synergy effect two catalysts was obtainedin the low temperature regions when Mn/TiO2
catalyst was used at the second level.
The rank of the activity of catalysts developedin this research is as follows:
Fe(0.5)/TiO2+Mn(0.5)/TiO2＞Fe(0.1)+Mn(0.5)/TiO2＞(Fe(0.1)+Mn(0.5))/TiO2＞Fe(0.1)-Mn(0.5)/TiO2.
The oxidation states of the catalysts used inthis study were Fe2O3 and Mn2O3. Iron was
found to enhance the dispersion ofmanganese on TiO2.

The surface area of the TiO2 support was 49.1
m2/g. After impregnation with iron or manganese,the surface area decreased. For the mixture
catalysts of Fe and Mn, it was found that additionof iron oxide increased the surface area of catalyst.
Therefore, it can be concluded that iron enhanced
the dispersion of manganese on TiO2.
Figure 5 shows the XRD patterns of the sample
which calcined at 600℃ in Fe(NO3)3・9H2O andMnCO3 ・nH2O. The samples were identified as
Fe2O3 and Mn2O3. Therefore, it can be estimatedthat the oxidation states of the catalysts used inthis study were Fe2O3 and Mn2O3, because they

References[1] H.Schneider, U.Scharf, A.Wokaun, A.Baiker,
J.Catal. 147, 545 (1994)[2] H. Hamada, Y. Kintaichi, M. Sasaki and T. Itoand M. Tabata, Appl. Catal., 70, L15 (1991)[3] R.Burch, T.C.Watling, Appl. Catal.B, 11, 207(1997)[4] Gongshin Qi,Ralph T.Yang, Appl. Catal., 217,
B44 (2003)

14

Technical Report of International Development Engineering

TRIDE-2006-01, February 20, 2006 (ISSN 1880-8648)

A Study on New Approach to Prepare CoMo / Al2O3Catalyst
for Deep Hydrodesulphurization
Student Number: 04M18245

Name: Haibo ZHANG

Supervisor: Hirofumi HINODE

深度水素化脱硫 CoMo/Al2O3 触媒の新たな調製方法の研究
張海波

石油精製における水素化脱硫触媒 CoMo/Al2O3 において活性種と考えられている CoMoS 相の新たな合成法を目指し、Mo の先駆物(NH4)2MoS4（ATTM）の導入および調製方法を検討した。チオフェン脱硫反応により水素化脱硫活性を評価した結果、調製試料が市販触媒より高い活性を示した。ATTM を真空焼成してから、Co を還元雰囲気で担持する方法で調製した試料は金属担持量の増加とともに活性が上昇の傾向を示し、Ｍｏ担持量 15wt%で 96.5％のチオフェン転化率を示した。生成物質分布の考察により調製試料の脱硫選択性が高いことが分かった。XRD、XAFX、TEM などの解析により、多層化した CoMoS 相の存在が確認された。調製試料表面の CoMoS 相の積層数が市販触媒より多いことが水素化脱硫活性および脱硫選択性が高い原因であると考えられる。

1

In the conventional preparation process, Al-O-Mo bond

INTRODUCTION

and CoMoO4 compound are produced during calcination

To meet the need of deep desulphurization ofand it had been found that these bond and compound do

transportation fuels, researches and developments of

not contribute to the production of active sites[3]. For thishydrodesulphurization(HDS) processes and catalysts

reason, the conventional method of catalyst preparation

have been carried out. It is considered to be difficult tois facing a limitation in the way of improving efficient

get super-low sulfur level liquid fuels (e.g. Japaneseutilization of active metals.

stand: less than 10 ppm) by exiting hydrotreating

New route for catalyst preparation process wastechnology alone, therefore, the present approaches suchproposed in this research in order to investigate the new

as increasing reactor size, operating in more severe

approach to prepare the catalyst for deep HDS. This new

conditions (e.g. high pressure and high temperature), androute is expected to efficiently improve utilization of

new designs in desulfurization process are considered toactive metals in catalyst in order to produce CoMoS

be good solutions[1].

phase.

CoMo/ Al2O3 catalyst is widely used in the HDS of2naphtha, paraffin oil, and light oil. Researches and

EXPERIMENTAL

developments of CoMo / Al2O3 HDS catalysts are being

2.1 Catalysts preparation

carried out in every aspect, such as supports and2.1.1 Materials used in preparation of catalysts

interactions between active metals. The known active site

Precursors of the catalysts were Co(NO3)2・6H2O (Wako

for this catalyst is a kind of CoMoS interacted by each

Pure Chemical Industries, Ltd., purity = 99.5%) andelement. The promotion of HDS activity is linked to Co(NH4)2MoS4 (Aldrich Chem. Co., purity = 99.97%).

[2]

JRC-ALO-2 (Al2O3, Reference Catalyst, The Catalysis

atoms present as CoMoS in the CoMo/Al2O3 catalyst .

15

Technical Report of International Development Engineering

TRIDE-2006-01, February 20, 2006 (ISSN 1880-8648)

Society of Japan) was used as support. As reference HDS

0.25mm×30m).

catalyst, commercial CoMo/Al2O3 catalyst was used after

2.3 Characterization

pre-sulfidation treatment.

The samples were characterized by powder X-ray
2.1.2 Preparation of catalysts

diffraction (XRD), X-ray absorption fine structure

Consecutive impregnation method was used in the(XAFS), transmission electron microscope (TEM), andpreparation of catalysts. The loading of Mo was varied inBrunauer-Emmett-Teller method (BET).

a range of 10~15wt% and the molar ratio of Co /Mo was

3

fixed at 0.27. There were three preparation routes

RESULTS AND DISCUSSION

investigated in this research. The prepared samples were

3.1 HDS activity and selectivity

named by prepared route and the loading of Mo, forFig.1 showed thiophene conversions of samples preparedexample, R1-10 means that the sample prepared byby three routes at 350℃.

Route1 and the loading of Mo is 10wt%.

100

Route 1 (R1) includes impregnation of Co(NO3)2・
calcination

under

H2

atmosphere,

Conversion(%)

6H2O,

90

and

impregnation of ATTM, vacuum calcination at 500℃
and 700℃.

70

R1
R2
R3

60

Route 2 (R2) includes impregnation of Co(NO3)2・
6H2O,

80

calcination

under

air

atmosphere,

50
9

and

impregnation of ATTM, vacuum calcination at 500℃.

11

13
15
Loading of Mo(wt%)

17

Figure 1: Thiophene conversions of prepared samples

Route 3 (R3) includes impregnation of ATTM,

In route 1, sample with a Mo loading of 10% showedvacuum calcination at 500 ℃ , and impregnation of

thiophene conversion of 83.6%, when the Mo loading

Co(NO3)2・6H2O, calcination under H2 atmosphere.

increased

Pre-sulfidation was carried out at 400℃ in a H2S/H2

to12.5%,

thesampleexhibitedaapproximately the same thiophene conversion as that of(10%) gas stream for all samples.

commercial catalyst (88.5%), while the thiophene
2.2

Activity measurement

conversion decreased to 77.5% when the Mo loading was

The reaction was carried out in a fixed-bed reactor underincreased to 15%. There was an optimum Mo loading in

atmospheric pressure. The catalyst was palletized,

this preparation route approximates to 12.5%. More thancrashed and sieved to 0.71~ 1.00mm. 0.2g of the sample

this value, the agglomeration caused by calcination at

was packed in the reactor and the total flow rate of the

700℃ was considered to be the reason of resulting in thefeed mixture gas was fixed at 20ml/min.. The

decreasing of catalytic activity.

concentration of thiophene in the feed stream was

In route 2, all prepared samples showed thiophenemaintained at 2.1mol%. The reaction temperature wasconversion more than 93%, and there was no apparent

selected at 300 to 350℃.

difference found among three samples. The active site

Thiophene and reaction products such as butane andbutenewerequantitatively

analyzedbyformation by MoS2 and Co is considered to be easier

GC-MS

formed through CoO than through Co[4], but the(Shimadzu Co. QP5050A) equipped with capillaryformation of CoMoS active site was limited to generatecolumn (Chrompack, CP-Porabond Q Fused Silica,

only on the surface of Al2O3 because Co impregnated16Technical Report of International Development Engineering

TRIDE-2006-01, February 20, 2006 (ISSN 1880-8648)

previous to ATTM could only access to the MoS2 located
Table 1: Comparison of product distribustions

on the Al2O3 surface, not to the part of MoS2 extending

Specific Area

from the surface. This is the reason that samples prepared

1-

Trans-2-(10 )butenebutenebutane butene

R3-15
Commercial

7.7
4.1

215.2
215.2

728.0
809.0

-6

by route 2 had high activity, however, there is alimitation on in increasing the catalytic activity byincreasing Mo loading.

n-Cis-2-

Thiophene

418.0
365.7

248.1
227.7

Reaction conditions:325℃, Thiophene concentrationin feed: 2.1mol%,GHSV 5800h-1
Thiophene conversion of R3-15:81.9%
Thiophene conversion of commercial catalyst: 82.5%

In route3, samples showed a tendency that thethiophene conversion increased together with theincreasing of Mo loading. Mo loading of 10% and 12.5%
showed thiophene conversion of 85.3% and 88.5%
respectively, and the sample with a 15% Mo showed the

3.2 Characterization

highest thiophene conversion of 96.5%(8% higher than

The XRD patterns of prepared samples (Fig.2) showedcommercial catalyst) in all samples. ATTM wascharacteristic peaks of MoS2 at 2θ=14.2º(002), 33.6º

introduced to Al2O3 before the impregnation of Co, and(100), 39.5º(103), 58.5º(110), and characteristic peaks ofthen decomposed to MoS2. After that, precursor of Co

Al2O3 at 2θ=46.3º(400), 66.9º(440). No characteristic

was absorbed on the surface of both Al2O3 and MoS2

peaks of Co or Co sulfide was detected. This means thatduring the impregnation. Co and MoS2 create CoMoS

during the Co addition, Co does not undergo aphase (interacted by each element[2]) in the active

reconstruction of MoS2 crystallite, although MoS2 acts astreatment and promoted catalytic activity of HDS.

a support to provide Co desirable location for theformation of CoMoS active site[7].

Table 1 showed comparison between sample R3-15
and commercial catalyst on the product distribustions at

002

325℃. 1-butene, trans-2-butene, n-butane, cis-2-butene
n-butane(defined as moles of n-butane in the products
per mole of thiophene in the feed) can represent thehydrogenation(HYD)

abilityofcatalyst

103

during

Al2O3
R3-10 110

Intensity(a.u.)were detected as reaction products. The conversion to

100

R2-10
R1-10

[5]

thiophene HDS reaction . During the process of deep
desulphurization, the HYD function of catalyst performs
saturation of olefins, and for example in the case of2θ(deg)gasoline desulphrization, this causes loss of octane

Figure 2: XRD patterns of prepared samples[6]

number in the final products , meanwhile low HYD

As shown in Fig.3, in TEM micrographs MoS2

ability directly contributes to low H2 consumption.

crystallite can be clearly seen in the form of groups of

Therefore, catalysts with high desulfurization ability andparallel dark lines with a space of about 6Å. The number

low hydrogenation ability are desirable.

of MoS2 layers in the prepared sample seems to range

The conversions to n-butane of the prepared samples

from 5 to 20 slabs more than that of commercial catalyst(43% for sample R3-15) were less than that ofwith 2 to 7 slabs. This can be considered to givecommercial catalyst (50%). The prepared samples havepromotions to the catalytic activities of HDS reaction[8]high HDS ability but lower HYD ability.

and to reduce steric hindrances for large molecular (such17Technical Report of International Development Engineering

TRIDE-2006-01, February 20, 2006 (ISSN 1880-8648)

as 4,6-dimethyldibenzothiophene) to approach active

promotions in the CoMoS structure contributed to thesite[3].

promotions of catalytic activity and selectivity.
(a)References[1] Song C. “An overview of new approaches to deep
desulfurization for ultra-clean gasoline, diesel fuel,and jet fuel”, Catal. Today. 86(2003)211-263.
[2] Topsøe H., “Clausen B.S., Active sites and support
effects in hydrodesulfurization catalysts”, Appl. Catal.
25(1986)273-293.
[3] Whitehurst D.D., Isoda T., Mochida T.I., “Present
state of the art and future challenges in the(b)hydrodesulfurizationofpolyaromatic

sulfurcompounds” Adv.Catal.42(1998)345-471.
[4]Li Jiapeng, “catalytic Hydrogenation Technology”,
FushunResearch

InstituteofPetroleumandPetrochemicals of SINOPEC, pp.254-266,Jan.1990(in Chinese)[5]Klimova T., Casados D.S., Ramirez J., “New selective
Mo

Figure 3: TEM images of (a) R3-15
and (b) commercial catalyst
XAFS

spectraprovided

and

NiMo

Al2O3-MgO(x)

HDS

mixed

catalysts
oxides”,

supported

Catalysis

on

Today

43(1998)135-146

electronic

structure[6]Yin C., Liu C., “Hydrodesulfurization of cracked

information of prepared sample that Co has anaphtha over zeolite-supported Ni-Mo-S catalysts”,

coordination number (CN) of 5.3 with S, and a CN=1.6

Appl. Catal. A:General 273(2004)177-184

with Mo. This result agreed well with the reported[7]Inamura K.,Prins R., “The Role of Co in Unsupported

electronic structure of CoMoS (Type 2) phase, which has[9]a CN=5.2 of Co-S, a CN=1.5 of Co-Mo .

Co-Mo

Sulfidesinthe

HydrosulfurizationofThiophene” J.Catal. 147(1994)515-524

CoMoS[8] Okamoto Y., Ishihara S., Kawano M., Satoh M. and(Type 2) phase is generally considered to be the active

Kubota T., “Preparation of Co-Mo/ Al2O3 modelsite for HDS reaction.

sulfide catalysts for hydrosulfurization and their

4

CONCLUSION

application to the study of the effects of catalyst
preparation” J. Catal. 217(2003)12-22

The introduction of ATTM as the precursor of Mo withappropriate preparation method showed great promotion[8]Bouwens S.M.A.M., van Zon F.B.M., van Dijk

to catalytic activity of CoMo/Al2O3 HDS catalyst. The

M.P.,van der Kraan A.M.,de Beer V.H.J.,van Veen

prepared samples showed high activity during thiophene

J.A.R.,and Koningsberger D.C., “On the Structural

HDS reaction (thiophene conversion of 96.5%, 8%

Differences between Alumina-Supported CoMoS
Type Ⅰand Alumina-,silica-,and Carbon-Supported

higher than commercial catalyst). The prepared samples

CoMoS Ⅱ

with higher HDS ability exhibited a relatively lower

phases Studied by XAFS,MES, and

XPS” J.Catal. 146 (1994)375-393

hydrogenation ability compare to commercial catalyst.
XRD, XAFS, TEM, and BET gave information that18

Technical Report of International Development Engineering

TRIDE-2006-01, February 20, 2006 (ISSN 1880-8648)

Improvement of Rubberwood Process Using the Thermally Treated Products from
Wood Residue
Student ID#:04M18110

Name:KONISHI, SHUNSUKESupervisor:EGASHIRA, RYUICHI

残材の熱処理生成物を用いたゴム木材プロセスの改良
小西俊介

ゴム木材の家具製造プロセスにおける有害防腐剤による排水汚染と大量の残材投棄が問題となっている。本研究では残材を熱処理することで木酢液、木炭、および可燃性気体に分離し、それぞれ低有害防腐剤、廃水処理用吸着剤、および熱源として再利用することでの問題の改善を考えた。ゴム木材おが屑を原料として温度や雰囲気等条件を変えて熱処理実験を行い、結果を用いてプロセス全体での物質収支および熱収支計算を行った。木酢液と木炭は十分な量得られ、出入り口でのエンタルピー差を熱処理の必要熱量としたとき、可燃性気体と吸着で余った木炭の発熱量により約半分の熱を回収できることが分かった
The char produced at 700K was used in the adsorption
experiment. The char was mixed with various concentrations ofaqueous phenol and the mixtures were put in the agitator at
303K for 120 hours enough for the adsorption equilibrium.
After the adsorption experiment, the aqueous phenols wereseparated from the char by the filtration. The initial andseparated phenol solutions were analyzed by GC. The
adsorption mass of phenol on the unit mass of the char was
estimated.

1. Introduction:
In Southeast Asia Countries, various forms of residues aredischarged from the process of rubberwood manufacturing. In
this process, a portion of wood residues are being thrown away
to isolated country site and are burned illegally. These disposal
methods do cause environmental problems, such as accidental
forest burning, release of hazardous gases, and soil
contamination by toxic preservatives. Besides, the issue ofwood preservative has also been paid attention because of the
toxicity of present wood preservative products. These problems
are considerably serious in these countries.
Wood can be thermally decomposed into useful materials
such as pyroligneous acid (PA), char and fuel off-gas. PA fromwood can be used as a substitute for the ordinary toxic woodpreservative[1,2,4]. The char was studied to have a highadsorption capacity to remove unfavorable components fromwaste water[3,5]. Off-gas contains some flammable gases suchas, H2, CO, CH4.
In this study, we are trying to improve the existing
rubberwood process. Thermal decomposition of rubberwood
was conducted to obtain the useful products. The yield andcharacteristic of the products were estimated. We proposed arubberwood process in which the products is utilized as apreservative, adsorbent and gas energy. The balance of heat
energy as well as material balance in the whole process wasestimated based on the experimental data.

2. Thermal treatment of rubberwood
characterization of the products:

Table 2.1

Experimental condition in the thermal treatment

Run NoA-700
A-900
A-1092
A-1292B-700
B-900
B-1092B-1292
C-1092C-1292

Experimental condition
700K, 0.03m3-steam/h, hold time 1hour
900K, 0.03m3-steam/h, hold time 1hour
1092K, 0.03m3-steam/h, hold time 1hour
1292K, 0.03m3-steam/h, hold time 1hour
700K, 0.03m3-steam/h, hold time0.5hour
900K, 0.03m3-steam/h, hold time 0.5hour
1092K, 0.03m3-steam/h, hold time 0.5hour
1292K, 0.03m3-steam/h, hold time0.5hour
1092K, 0.015m3-steam/h, hold time 1hour
1292K, 0.015m3-steam/h, hold time 1hour

and

2.1, Experimental
Thermal treatment
Rubberwood sawdust was treated thermally to obtain crude
pyroligneous acid (CPA), char, and off-gas in the various
conditions. Table 2.1 shows the experimental conditions,specified temperature, steam flow rate and holding time atspecified temperature. The CPA was distillated into PA and tar
at 413K. The apparatus of thermal treatment and distillation are
figured in Figure 2.1.

Figure 2.1 Schematic diagram of experimental apparatus

2.2, Results and Discussion
Thermal treatment
The yield of each product in the thermal treatment was
expressed as,Characterization of the productsYi =The CPA, PA and off-gas were analyzed by GC to know
the concentration of main components. Elementary analysis of
the char and rubberwood were also conducted. Preservative
efficiency of PA was estimated by comparing the compositionof phenolic compounds in PA with that in the previous
preservative. Phenols are known to have the preservative effect.
The calorific value of the gas, char and wood were calculated
from enthalpy difference between before and after burning.

Wi
Wsawdust(2-1)

The yield of each product is shown in Figure 2.2. It wasstudied that char is completely produced around 600K and the
produced char is gradually consumed by steam above 800K In
this study, the char yield decreased with increasing thetreatment temperature due to the high consumption of carbon bysteam. No char remained in the thermal treatments at 1292K.
The char was consumed more in the experiment A than theothers due to the more steam provided. As for CPA, the yield
was not influenced by the temperature. It is because the wood is

Adsorption

19

Technical Report of International Development Engineering

TRIDE-2006-01, February 20, 2006 (ISSN 1880-8648)

completely decomposed into CPA by 600K and in the higher
temperature range, the yield of CPA does not change any more.
The CPA is composed of the volatile components from thewood and the water from the feed steam. The yield of CPA isdetermined by not only feed wood but also feed steam mass.
The yield of CPA was higher in the Experiment A than theothers. It is because that more steam was provided in theapparatus and the unreacted steam was directly condensed to the
CPA. Contrary, the yield of the off-gas increased withincreasing temperature. In the range of higher temperature,
more char and steam were reacted and more off-gas wasproduced. The produced gas contained many inflammablecomponents such as, H2 and CO above 1092K. The reactions
are written below,(2-2)
H 2 O + C → H 2 + CO
(2-3)
H O + CO → H + CO
2

2

A

2

Yield of products, Yi [-]2

active reactions of carbon and steam. These reactions wereshown above at equation (2-2),(2-3). At higher temperature,these reactions were more active, and Hydrogen and Carbon
oxide were produced more. These high production of flammablegases resulted in the increase of the heating value of Off-gas. At
low temperature, 700 and 900K, the off-gas contained little
flammable gas and had low heating value as a heat recovery forthe thermal treatment. On the other hand, the off-gas produced
at 1092 and 1292K had high heating value and these were
useful for the heat recovery.

Distillation
The CPA produced at each thermal treatment condition was
distilled around same temperature, 413K. The yield of eachproduct in the distillation was expressed as,

Wi
(2-4)
WCPA
The yield of interested components in the PA was defined as,(2-5)
y i = xi ⋅ YPA
Yi =

B

C
◆ CPA
▲ Off-gas■ Char

1.5

1

0.5

0
0

500

1000 1500 0

Temperature, T[K]The yield of PA and tar is shown in Figure 2.3. It was very
difficult to control the distillation temperature which influences
strongly the yield of products. The higher distillation
temperature, the higher yield of PA and the lower yield of tar.
As a result, the yield varied in the distillation of each CPA due
to the unstable distillation conditions. However, the variation
range of PA yields was between 0.7~0.9 and these values wereenough for a wood preservative.
The concentration of phenols in PA is shown in Figure
2.4. All the PA contained larger phenols, preservative
components, than the previous PA which was confirmed to havepreservative effect. The result indicated that all the PA of thisstudy had high preservative effect and could be used as apreservative.

500

1000 1500 0

5001000 1500

Temperature, T[K]

Temperature, T[K]Figure 2.2 Yield of the products in the thermal treatment
1

Yield in the distillation, Yi [-]

A

B

C
■ PA
▲ Tar

0.5

Adsorption capacity of the char0

Figure 2.5 shows the adsorption isotherms of phenol by
the char. The char treated with steam atmosphere at 700K was
prepared in this study. The adsorption by the char of 1292K was
not conducted because the char was not obtained in the thermal
treatment as mentioned above. The adsorptions by the char of
900 and 1092K were conducted in the previous studies[1,3,5]. The
amount of adsorption of phenol increased with increasing
temperature of thermal treatment. It means that the char treatedat higher temperature has higher adsorption capacity. The
adsorption capacities of char with steam were somewhat smaller
than that of the chars with CO2. However, the char with steam
above 873K had enough adsorption capacity for an adsorbent ofwaste water. The Langmuir isotherm equation was used toquantify the adsorption capacity of each char. Product of theadsorption coefficient and the maximum adsorption amount ofchar, K⋅q ∞ , represents the relative adsorption capacity in adilute solution. Table 2.2 shows K⋅q∞ of each char and also therelative adsorption capacity on CO2-1073 basis.

500 1000 1500 0
T, [K]

0

Figure 2.3

500 1000 1500 0
T, [K]

500 1000 1500
T, [K]

Yield of PA and tar in the distillation●

PA in this study
Previous PA

Concentration of phenols, [-]×10 - 3

3

A

B

C

2

1

0
0

Heating value of Off-gas
Figure 2.6 shows the mass production of components in
the Off-gas at left axis, and the heating value at right side. The
off-gas mainly contained Hydrogen, Carbon oxide, Carbon
dioxide and Methane. The flammable gas, Hydrogen andCarbon oxide, increased with treatment temperature due to the

500 1000 1500 0
T [K]

500 1000
T [K]1500 0500 1000
T [K]Figure 2.4 Composition of phenols in PA

20

1500

Technical Report of International Development Engineering

TRIDE-2006-01, February 20, 2006 (ISSN 1880-8648)

0.25

CO2 at 1092K**
Amount of adsorption,
q [kg/kg-carbon]

0.2

steam at 1092K*

0.15

steam at 900K*

0.1

0.05

Figure 3.1

steam at 700K

3.2, Calculation condition and assumptions

0
0

0.1
0.2
0.3
0.4
0.5
Concentration of phenol in equilibrium,
Ce[kg/m3 ]0.6

Feed wood of 1000 ton/year is provided to Molding1. It
is molded into wood product, wood residue and waste wood.
The wood product of 200 ton/year is treated with preservative
by PA of constant rate, 33.4 ton/year. Flow rates of thermallydecomposed products are calculated using the results of yield in
the experimental section. The PA produced in Distillation are
directly used as a preservative. All the PA components are
assumed to be washed out into waste water during Drying. The
flow of char requirement for adsorbent is determined from theresults of adsorption experiment to meet the regulation of waste
water. The flow of PA requirement for preservation is
calculated from the reference data and it is constant, 33.4
ton/year. It is estimated the flow rate of required wood residue1
to obtain the requirement of PA and char. The flow of eachmaterial is defined as flow rate, ton/year.
The heat consumption in the thermal treatment wasestimated from the difference between the enthalpy of inlet andoutlet materials. The enthalpy of the inlet materials, sawdust
and water, were calculated at room temperature and that of theoutlet, Char, CPA and Gas, were calculated at the specified
temperature of apparatus. We assumed the composition of eachmaterial, that the char was pure carbon, and CPA was composedof only water, acetic acid, methanol and phenol, and off-gas
contained only H2, CO, CO2, CH4 and H2O. The same enthalpy
calculation was conducted in the distillation. The flow of eachheat is defined as heat flow, J/year.

Figure 2.5 Adsorption isotherms of phenol in the model
solution
Table 2-2 Adsorption capacity of each char produced

CO2-1092
steam-1092
steam-900
steam-700

q8 ×KL[m3/kg-carbon]
20.3252
8.26454.52900.5293

Adsorption capacity[-]
1
0.4066
0.22280.0260

×10 12

Production of components in
off-gas [mol/kg-sawdust]

A

B
H2
CO
CH4
CO2
H2O
Heat

20

500

C

1500 5001000
673 8731073 1273
T, [K]

1000

41500 500

673 873 1073 1273
T, [K]

1000

1500

Heating value on feed woodbasis, [J/kg-sawdust]

8

40

0

Proposed process flow03.3, Results and discussion

673 873 1073 1273
T, [K]

Figure 3.2 (a) shows the flow rates of the PA produced
and preservative requirement against flow rate of wood
residue1. The flow rate of the PA increased with wood residue1
and these were larger than that of requirement in all the cases.
Figure 3.2 (b) shows the flow rates of the char produced andadsorbent requirement. The char treated at 900K were satisfied
the requirement for the process at all the flow of wood residue1.
The char treated at the other temperatures were less than therequirement at low flow of wood residue1. As the flow of woodrsidue1 increased, these char products increased and reached therequirement at a flow rate of wood residue1. Figure 3.3 shows
the minimum flow rate of wood residue1 at which the either PAor char meets the requirement The flow rate for charrequirement was always larger than that for PA. We defined theresidue1 flow for char as a required residue1 flow rate to meetboth PA and char requirement.
Figure 3.4 shows the heat consumption in Thermal
treatment and Distillation, and also heat recovery from off-gas
and wood residue2 at the each defined residue1 flow. The heatconsumption increased with increasing the defined residue1.
When the residue was treated at 700K, the defined residue1 washigh and then the heat consumption was also high. We
estimated how much wood residue2 was burned for heatrecovery. Figure 3.5 shows the flow rate of the total required

Figure 2.6 Mass production of each component in Off-gas (left)
and heating value of Off-gas (right)

3. Balance of material and heat in the process:
3.1, Proposed rubberwood process
We proposed an improved rubberwood process utilizing
the thermal treated products, PA, char, and off-gas, from wood
residue as shown in Figure 3.1. Some waste wood are burned togenerate the heat for Drying. A portion of the remaining waste
wood, wood residue1, is decomposed into the useful products in
Thermal treatment. The other wood residue, wood residue2, isburned to recover the heat for the proposed process. After PA isput on the surface of wood product for preservation, it is washed
out into the wastewater. This wastewater is contacted with thechar adsorbing the phenols derived from PA. The Off-gas isalso burned with wood residue2 in Burning and produces theheat for Thermal treatment and Distillation.

21

Technical Report of International Development Engineering

TRIDE-2006-01, February 20, 2006 (ISSN 1880-8648)

wood residue, which is sum of the wood residue1 to obtain PA
and char, and the wood residue2 to recover the heat. At thepresent process, wood residue is discharged at various flow
rates. This flow rate depends on the situation. From thereference data, we estimated that the wood residue could bedischarged from 66 to 374 ton/year. This range is shown as a
red line in Figure 3.5. When the wood residue was treated at A900, B-900, B-1092 and C-1092, the flow rates of the totalrequired residue were below this range. The result means that inthese conditions, the PA and char were satisfied the requirement
and the heat is also recovered completely.

Heat consumption in Thermal treatment
in Distillation

Flow rate of heat consumption andrecovery [J/year]

4. Conclusion :We confirmed that the useful materials were produced bythermal treatment of wood. The PA had high preservative
effect. The char had high adsorption capacity. The off-gas hadhigh heating value and the heat recovery from off-gas was 1040% of the heat consumption in the proposed process. The
result of the process calculation showed that, when the wood
residue was treated at 900 or 1092K, the total requirement of theresidue was lowest. In these conditions, the useful products
were obtained enough for the preservative and adsorbent, andthe heat consumption for the proposed process was also
recovered.

600

1

0

PA for preservative, [ton/year]

8

0

6

0

4

0

2

0

300

50

0
200
0.2

400
0.4 00200
0.2

Flow rate of wood residue requiredfor PA or Char [ton/year]

C

B

900
T, [K]

1092

700

900
1092
T, [K]□ wood residue1 for PA and char■ wood residue2 for heat recovery
C
B

400

300

Wood residue flow,
66-374 ton/year

200

100

900 1092
T, [K]

700

900 1092
T, [K]

700

900 1092
T, [K]

Flow rate of the total required wood residue

Nomenclature

400
0.4

W
T
Yi
yi
xi
q
q∞
Ce
KL

Flow rates of PA(a) and Char(b) against flow rateof wood residue1

A

A

Figure 3.5

Wr1,M1 [-]Flow rate of wood residue1α[ton/year]

400

700

Flow rate of heat consumption and heat recovery at
the defined flow rate of wood residue1

700

α Wr1,M1 [-]Figure 3.2

900
1092
T, [K]

0

0

0

00

500

(b)

(a)

0.5

Figure 3.4

100

0

1

700

Char requirement
PA requirement at 700K
PA requirement at 900K
PA requirement at 1092K

C-1092C-1292

1.5

Flow rate of the total required wood
residue [ton/year]

B-700
B-900
B-1092B-1292C

B

A

0Char for adsorbent, [ton/year]

A-700
A-900
A-1092
A-1292Heat recovery from Off-gas
from wood residue2

×10 1 22

■ for char
□ for PA

Mass of material[g]Specified temperature in the thermal treatment[K]
Yield of product[-]
Yield of component[-]
Composition of component[-]
Amount of adsorption[m3/kg-carbon]
Saturated amount of adsorption[m3/kg-carbon]
Equilibrium concentration[kg/m3]
Langmuir adsorption coefficient[m3/kg]References[1] Sato, M., Bachelor thesis, Tokyo Institute of Technology, Japan,
March (2005)[2] Lim, K.G., Master thesis, Tokyo Institute of Technology, Japan,
March (2004)[3] Konishi, S., Bachelor thesis, Tokyo Institute of Technology, Japan,
March (2004)[4] Lim, K.G., et al.; RSCE 2004, ES-257 (2004 Bankok)[5] Sato, M., et al.; SCEJ 70th annual meeting S117 (2005 Nagoya)

200

0
700

Figure 3.3

900
T [K]

1092

700

900
T [K]

1092

700

900
T [K]

1092

Flow rate of wood residue1 required for PA and
char

22

Technical Report of International Development Engineering

TRIDE-2006-01, February 20, 2006 (ISSN 1880-8648)

Enzymatic treatment of phenol waste water with thermo-responsive chitosan
Student Number:04M18096

Name: Shuichi KAWATOKOSupervisor: Ryuichi EGASHIRA, Sachio HIROSE

熱応答性キトサンを用いたフェノール排水の酵素的処理
川床 修一
本研究では，熱応答性キトサン（ヒドロキシブチルキトサン，HBC）のゲル化特性を利用して、フェノー
ル排水処理に使用した酵素（ペルオキシダーゼ、HRP）をリサイクルする方法を提案する。
実験では、HBC 溶液のゲル化温度、ゲル収縮特性、HRP 活性、HBC 存在下でのフェノール重合反応の反応率を調べた。これらの結果より、反応操作条件を 30℃，pH 5.9, HBC 1.6 w/w%、HRP 5 mg/L と決定して，各操作において物質収支をとった。その結果、リサイクルを行わない場合と比べ 1.0-1.7 倍の効果が得られた。

1. Introduction

CH2OR

H

Phenol-polluted waters are widely produced as wastes
of several industrial and agricultural activities. Phenolic
compounds and their derivatives are considered primarypollutants because they are harmful toward livingorganisms, even at low concentrations [1]. If released into
the environment, they may accumulate in soil, groundwater, or surface water, thus representing an issue of great
environmental concern.
Removal of phenols from wastewater can be performedby conventional remediation methods (e.g., solvent
extraction, chemical oxidation and adsorption on activatedsupports) [2]. Some of these methods may present a
number of disadvantages, such as high costs,
time-consuming procedures and formation of toxic
residues although it is effective. Biological technologies
dealing with the use of oxidoreductive enzymes, forinstance, laccases, peroxidases, and tyrosinases, may
represent an efficient, alternative way to address theclean-up of phenol-polluted wastewater from low to highdensity. Phenol reaction formula by enzyme was shown inbelow.

O
H
OH

RO
H

NR2

H

n

H2 H
C C

H2
C CH3

OH
R:H or
Fig.1 HBC structure.

2. Experimental
2.1 Materials
HBC was provided from Dainichiseika Ltd., Japan.
HRP was purchased from Biozyme Laboratelies (South
Wales, UK). All other chemicals were the highest purity
available and purchased from Wako Pure Chemicals Co.,
Japan.
Two types of buffer solution were prepared, 0.1 M
phosphate buffer (pH 5.7-7.0) from sodium
dihydrogenhposphate and disodium hydrogenphosphate,
0.1 M acetate buffer (pH 5.4-5.6) from acetic acid andsodium acetate.

H2O2 + 2 AH2 → HAAH (polymerized product)
A: C6H4-OH
Enzyme figures as high reactivity, substrate specificity,
biodegradability, and can be operates at mild conditions oftemperature, pressure, and pH. However, there are anumber of practical problems in the use of enzymes. It
costs for isolation and purification of enzyme, theinstability of their structures.
In this study, we suggested the enzyme recycle methodby using thermo-responsive chitosan (hydroxybutyl
chitosan, HBC)(Fig.1). In this method after phenol
polymerization by horseradish peroxidase (HRP) andhydrogen peroxide, the solvent was gelated. From this step,
treated water drains from shrinking HBC gel. In the next
step, HBC gel returns solvent with cooling, polyphenol
was removed as precipitation.

2.2 Measurement of HBC gelation temperature
HBC solutions (pH 5.4-7.0, 1.0-2.0 w/w%) wereprepared, and measured their gelation temperature by
inverting test tube [3].
2.3 HPLC analysis
HPLC analysis was performed with a Shimazu
instrument equipment with a wavelength absorbance
detector set at 280nm. A wakoshi Ⅱ 4.6 mm×10 mmcolumn was used. Isocratic solution was performed at aflow rate of 1mL min-1 with mobile phase composed ofwater, acetic acid and acetnitrile (39.6: 0.8: 60.0 %; v/v)
2.4 Measurement of shrinking ratio
HBC solution(pH 5.9, 1.6 w/w%) was heated in231Technical Report of International Development Engineering

TRIDE-2006-01, February 20, 2006 (ISSN 1880-8648)

RE=CEa,no recycle/CEa, rrecycle

incubation bath at 33℃, moved another incubation bath(at 40, 45, 50℃) and measured their ratio of shrinking
after each times(10, 30, 60 min). Ratio of shrinking wasmeasured by weight of HBC gel after removal of waterand HBC solution before galation. And phenol and HRP
concentration after gel shrinking were determined by the
HPLC method of analysis for phenol concentration

CEa,no recycle[mg/L]: Additive enzyme concentration
on no recycle method
CEa,recycle[mg/L]: Additive enzyme concentrationon this recycle method
phenol waste water
HRP
H2O2

2.5 HRP Activity
HRP activity was assayed by measuring absorbance(450nm) intermediate product of phenol and 4aminoantipyrine (4-AAP) as the substrate.
To investigate effect of pH and temperature to HRP
activity, phenol (10.6 mM final concentration), 4-AAP(2.6mM final concentration), HRP (5.4×10-1 mg/L final
concentration) and H2O2 (0.22 mM final concentration) as
initiation reagent were prepared in 0.1 M phosphate buffer(pH 5.4-7.0), and the absorbance was measured after 5
min at 25-37℃ by microplateleader.
To investigate thermostability, HRP activity wasmeasured, after 10 mM HRP solution was incubated ineach incubation bath (33-60℃). Thermostability wasdefined the following equation as relative activity (RA).

R

HBC gel
HRP

S1

water

S2

polyphenol

R: phenol polymerization reaction
S1: separation by heating
S2: separation by coolingFig.2 Outline of enzyme recycle model.

3. Results and Discussion
3.1 HBC gelation temperature
Fig.3 shows the relationship between gelation
temperature and pH in various HBC concentrations. From
this graph, HBC solution had a tendency to be gel athigher pH, temperature and HBC concentration. Thesegelation behaviors can be attributed to the protonation ofamino groups in HBC and the property of hydroxybutyl
bond in HBC. The pKa of chitosan is approximately 6.5.
Hence chitosan is dissolved under pH 6.5 due toprotonated amino group of chitosan. Above pH 6.5,
chitosan is tendency to turn into gel because the aminogroups in chitosan were deionized. HBC turn to gel athigh temperature because of lower critical solution
temperature (LCST) derived from hydroxybutyl bond. In
addition, HBC with high concentration tune to gel because
the cross linkage points of molecule entanglement and thehydrophobic binding increase.

RA=At/A0
At [-]: HRP activity with t minutes heating
A0[-]: HRP activity with no heating
2.6 Phneol polymerization in the presence of HBC
To determine HRP concentration in the reactor, phenol
polymerization tests by HRP and H2O2 as initiation
reagent was carried out at with 1000 mg/L phenol in 0.1
M phosphate buffer (pH 5.9) with out HBC. Samples
were analyzed for phenol concentration by HPLC at eachtimes (10-120 min). And phenol polymerization tests by
HRP (5 mg/L final concentration) and H2O2 was carriedout at phenol concentrations ranging from 50-500 mg/L
with or without HBC on the same condition of previous
tests. Samples were analyzed for phenol concentration by
HPLC at each times (10-120 min).

7.0
2.0 w/w % HBC

6.8

pH[-]

2.7 Material balance
Using the values from experiments, material balance forthe method was calculated. As the modeling assumption,
the followings were assumed.ⅰ) The reaction related onmaterial balance would be phenol polymerization at R and
HRP deactivation at S1, ⅱ) Polyphenol was separated
completely at S1, ⅲ) HRP added to R had no deactivated
HRP, ⅳ) HBC and polyphenol were not included intreated water, and additive solvent to R.
Material balance calculations showed that all flows andconcentrations shown in Fig.2 were expressed by the
relation using the rate of reaction, RA, rate of shrinking,phenol ratio in HBC, HRP ratio in HRP, initial phenol
concentration, initial phenol feed, and reaction HRP
concentration. To evaluate the proposed model (Fig.2),
HRP recycle effect (RE) was defined as below;

1.8 w/w % HBC

6.6

1.6 w/w % HBC

6.4

1.4 w/w % HBC

6.2

1.2 w/w % HBC
1.0 w/w % HBC

6.0
5.8
5.6
5.4
5.2
5.0
25

30

35

40

45

50

55

Temperature [℃℃]
Fig.3 Relationship between gelation temperature and pH
in various concentrations of HBC.

24

2

Technical Report of International Development Engineering

TRIDE-2006-01, February 20, 2006 (ISSN 1880-8648)

3.2 shrinking ratio
Time causes of HBC shrinking ratio is shown in Fig.4.
The ratios of phenol and HRP in HBC gel after gel
shrinking were also shown in Fig.5 and Fig.6. In each case,
HBC gels were rapidly shrinking within 10 min. HRP andphenol ratios in HBC decreased with increasing time andthe concentrations of them increased due to HBC gelshrinking. Relationship between phenol ratio in HBC andphenol concentration is linear as shown in Fig.5, and thoseequations were summarized in Table 1.

Table1 Relationship between phenol ratio (ξ2 (Temperature[℃], Time [min])) in HBC and phenol concentration
ξ2(40, 10)=－1.5×10-4 ×CP2 + 0.63
ξ2(40, 30)=－2.4×10-4 ×CP2 + 0.59
ξ2(40, 60)=－3.3×10-4 ×CP2 + 0.55
-4
ξ2(45, 10)=－3.1×10 ×CP2 + 0.62
ξ2(45, 30)=－4.2×10-4 ×CP2 + 0.60
ξ2(45, 60)=－4.9×10-4 ×CP2 + 0.59
ξ2(50, 10)=－3.5×10-4 ×CP2 + 0.54
ξ2(50, 30)=－4.2×10 -4 ×CP2 + 0.53
ξ2(50, 60)=－5.9×10-4 ×CP2 + 0.59

1.0

45℃ without phenol and HRP
40℃ without phenol and HRP

0.8

1

50℃ with phenol and HRP
0.6

40℃

45℃ with phnol and HRP

HRP ratio in HBC [-]Ratio of shrinking [-]50℃ without phenol and HRP

40℃ with phenol and HRP
0.4

0.2

0.0

0

20

40

60

80

0.9

45℃

0.8

50℃

0.7
0.6
0.5
0.4

Time [min]

0

20

40

60

80

Time [min]Fig. 4 Time courses of HBC shrinking ratio in pH 5.9.
Fig. 6 Time courses of HRP ratio in HBC in pH 5.9 atdifferent temperatures.

0.7

1.6
0.5

1.4

0.4
40℃ 10min
40℃ 30min
40℃ 60min(40
線形℃ 10min)(40℃
10min)(40℃(40
30min)
線形℃ 30min)(40℃
60min)(40
線形℃ 60min)

0.3
0.2
0.1

Relative activity [-]Phenol ratio in HBC [-]

0.6

0
0

200

400

600

Phenol concentration [mg/L]

1.2
1.0
0.8
0.6
0.4
0.2

Fig.5 Relationship between phenol ratio in HBC andphenol concentration in pH 5.9 at 40℃.

0.0
0

50

100

150

200

Time [min]3.3 HRP activity
From HRP activity measurement, HRP activated at pH
6.5 in the range of pH 5.4-7.5 and at higher temperature in
the range from 25℃ to 37℃. HRP activity after 60 min
heating retained over 60% RA at up to 50℃(Fig.7).
In consideration of above results, phenol
polymerization condition was decided as described below:
pH 5.9, 30℃, 1.6 w/w% HBC.

Fig. 7 The relationship between time and relative activity
in various pHs and temperatures. (■:pH 5.7, 35℃,□:pH 5.9, 35℃, ◆:pH 5.7, 40℃, ◇:pH 5.9, 40℃,▲:pH 5.7, 45℃, △:pH 5.9, 45℃, ●:pH 5.7, 50℃,○:pH 5.9, 50℃, ×:pH 5.7, 60℃, －:pH 5.9, 60℃)

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Technical Report of International Development Engineering

TRIDE-2006-01, February 20, 2006 (ISSN 1880-8648)

3.4 Phenol polymerization in the presence of HBC
Fig.8 shows time course of phenol concentration invarious HRP concentrations. This graph indicates thatpolymerization reaction rate increase with increasing HRP
concentration. However, it’s more economic to use less
HRP. Therefore HRP concentration in polymerization
process was decided to 5 mg/L. Time courses of phenol
concentration in the condition with or without HBC areshown in Fig.9. This result indicates that phenol
polymerization could occur in the presence of HBC.

600

Phenol concentration [mg/L]

50mg/L without HBC

3.5 Material balance
RE was shown in Fig.10. From calculation results, theproposed recycle model turns out to be effective compared
to no recycle method. And it was also found that recycle
solution had approximately 3 times HRP concentration toinitial HRP concentration when HBC solution was shrankfor 30 min at 50℃.

100mg/L without HBC

500

500mg/L without HBC
50mg/L with HBC

400

100mg/L with HBC
300

500mg/L with HBC

200

100

0
0

50

100

150

Time [min]4. Conclusion
In this study, we suggested the HRP separation methodfrom aqueous solution by using HBC gelation process.
Gelation temperature of HBC in various conditions, gelshrinking ratio, phenol and HRP ratio in HBC gel, HRP
activity, thermostability of HRP, and phenol
polymerization reaction were investigated. And 10-500
mg/L phenol wastewater in HBC was treated. The result
showed possibility of decrease up to environmental
criteria of phenol concentration was implied.
Material balances in each process were calculated using
obtained data. In the results, the proposed HRP recycle
method showed 1.0-1.7 times effect defined as additive
HRP concentration compared to the condition of norecycle process.

Fig.9 Time courses of phenol concentration in theconditions with or without HBC.

Enzyme recycle effectivity [-]1.8

Phenol concentraion [mg/L]

1200

1000

1.6
1.4
1.2
1.0
40℃
45℃

0.8

50℃
0.6
0

20

40

60

80

Time [min]

800

600

Fig. 10 Enzyme recycle effect of various times andtemperatures.

0.1 mg/L
1 mg/L

400
200

5 mg/L

Acknowledgement

10 mg/LWe are grateful to T. Kajiuchi Prof. Emeritus at Tokyo
Institute of Technology for his helpful discussion. We wish
to thank Dainichiseika Ltd.,for providing HBC.

100 mg/L

0
0

50

100

References

150[1] L. Gianfreda et al, Water research, 37, 3205-3215(2003)[2] Miguel A Duarte-Vazquez et.al., Chem. Technol.
Biotecnol., 78, 42-47 (2002)[3] 長田義仁，梶原莞爾：普及版ゲルハンドブック，
エヌ・ティー・エス（1997）in JapaneseTime [min]Fig.8 Time course of phenol concentration in theconditions of various HRP concentrations.

26

4Technical Report of International Development Engineering

TRIDE-2006-01, February 20, 2006 (ISSN 1880-8648)

EXTRACTION OF COAL TAR ABSORPTION OIL
BY A CONTINUOUS COUNTER CURRENT SPRAY COLUMN
Student Number: 04M18127

Name: Saito Jun

Supervisor: Egashira Ryuichi

連続式向流接触スプレー塔によるコールタール吸収油の抽出分離
斎藤 潤
コールタール蒸留留分の一つである吸収油中の含窒素成分（キノリン，イソキノリン，インドール）とその他の成分（同
素環式化合物など）の抽出分離に対しスプレー塔型接触装置を適用した。溶媒の組成，両相の流量，などの条件を変化させて，原料吸収油（重液，分散相）と溶媒であるメタノール水溶液（軽液，連続相）を向流に接触させ定常状態に至らせた。良好な向流接触操作が可能であり，含窒素成分の収率および他の成分に対する分離の選択性は，それぞれ最大で 0.3
および 30 程度であった。また，物質移動抵抗は連続相側が支配的であった。

1. Introduction(AO) and solvent(MeOH aq.) were stocked in the tanks. The

Coal tar, one of the byproducts from coal carbonization,column top and bottom were continuously fed with AO as thecontains many useful compounds to chemical industry. First,

dispersed phase and MeOH aq. as the continuous phasecoal tar is separated into several fractions by distillation.

respectively and the two fluids were contacted countercurrently.

Absorption oil (abbreviated to AO) which is one of these

The inlet flow rates were kept constant by checking the flow

fractions (b.p.=470~550K) contains nitrogen heterocyclic

indicators and the level of the interface between the continuouscompounds (nitrogen compounds) such as quinoline (Q),phase and accumulated raffinate phase at the bottom was

isoquinoline (IQ), indole (IL), etc, and the other compounds

maintained by adjusting the drain valve of raffinate phase.

suchnaphthalene (N), 1-methylnaphthalene (1MN),

The inlet and outlet flow rates were determined by weighing

2-methylnophthalene (2MN), biphenyl (BP), dibenzofuran

outlet mass per unit time, respectively. The holdup of dispersedas(DBF) etc. Generally, the current method mainly used tophase in the column was obtained by measuring the ascent of

separate these compounds in AO is reactive extraction by acidinterface between continuous phase and accumulated raffinate

and/or base. However, this process is relatively costly because

phase at the bottom when the AO inlet and drain were closed at

the acid and base used as solvent are very difficult to be

the same time. AO, solvent, raffinate, and extract phase wererecovered and cause corrosion of the equipments. For the
separation problems, the solvent extraction with aqueous

⑥

⑨

Rt

Et

methanol (MeOH aq.) etc1-8) has been suggested. The process④

components and there are no studies concerning about practical

④

Z

④

proposed is based on the liquid-liquid equilibriums of the

⑨

⑤

⑧

④

Rb

⑤

④

⑤

contactors and mass transfer rates. Spray columns are the①simplest differential-contact devices in laboratory studies. Theiradvantages are that the throughput is large and the interfacial

②

⑦

⑨

Eb

③

①
②
③
④
⑤
⑥
⑦
⑧

AO tank
Solvent tank
Pump
Valve
Flow indicator
AO distributor
Solvent distributor
Pyrex glass column
D=0.037 m
Z=0.495 m
Level controller③

area is directly measurable. In this study, a countercurrent spraycolumn was applied to separation of AO as a continuous
apparatusinpractical

use

and

operability,

Fig.1 Schematic diagram of the experimental apparatus

separation

performances including mass transfer rates, and so forth were

2.7×10-2m
1.9×10-2m

examined.

2.0×10-2m

3.3×10-2m

2. Experimental
Schematic diagram of the apparatus used in continuous

6×10-4m

operation is shown in Fig. 1. The column is made of pyrex
glass and behavior in the column can be observed. Figure 2

1.4×10-2m

shows details of distributors. The distributor of dispersed phase

2.8×10-2m

has 8 needle nozzles. The distributor of continuous phase has

(a)

(b)

outlets on side of cylinder to pretend falling disperse drops

Fig. 2 Details of distributors;

entering in it. The experimental procedure is below. First, feed(a) for dispersed phase; (b) for continuous phase27

Technical Report of International Development Engineering

TRIDE-2006-01, February 20, 2006 (ISSN 1880-8648)

analyzed by GC6) and Karl Fischer’s titration was conducted toconcentration in continuous phase, Kc,i, was calculated by,give the water content. The densities of these phases wered(R·xi)/dz= - Kc,i·a·(yi*- yi)(5)measured with the pycnometers. The principal experimental

with the boundary conditions of top and bottom of the column.

conditions are summarized in Table 1. Water content in theyi* in this equation was estimated from xi with using thesolvent, yw,b, and inlet flow rates, Eb, and Rt, were changed.

equilibrium relationships. a and z were specific interfacial area

Table.1 Experimental conditions
feed:absorption oil
solvent:aqueous methanolRt[kg·hr- 1·m- 2]
yw,b [-]
Eb [kg·hr- 1·m- 2]
2
3
4×10 ~ 3×10
0.3
1×103
2
3
5×10 ~ 5×10
0.5
1×103
2
3
4×10 ~ 4×10
0.3
2×103
2
3
4×10 ~ 5×10
0.5
2×103

between continuous phase and disperse phase and distance

The liquid-liquid equilibrium relationships were measured fordiameters of dispersed phase drops were larger in the runs withestimating the mass transfer rates.

yw,b = 0.5 than in those with 0.3 because the differences of

No
EC1
EC2
EC3
EC4

from top of the column, respectively.
3.3. Behavior in the column
In all the runs, entrainment of the dispersed phase particles
into the continuous phase and flooding were not observed andthen countercurrent contact could be carried out favorably. The

densities between continuous and dispersed phase were smaller(see Table 2). The drop diameters decreased, as the flow rate of

3. Result and discussion
3.1. Basic results

dispersed phase, Rt, increased (see Fig. 3). The coalescence of

3.1.1. Liquid-liquid equilibrium

the dispersed phase and axial mixing were observed in therange of higher Rt. Holdup of dispersed phase in the column, H,

The liquid-liquid equilibrium relationships obtained in this6)

study were equal to those in the previous study .

shows in Fig. 4. Eb and yw,b had no effect on H. Therefore the3.1.2. Density

flow rates of both phases were under the loading point. Figure
5 shows the specific interfacial area, a, plotted against Rt.

The densities of materials are summarized in Table 2. The

3.4. Composition

density of dispersed phase was larger than that of extract phase.
The density changes did not effect seriously on continuous

The compositions of feed AO are shown in Table 3. Figure

operation. The density of continuous phase in the runs with yw,b

6 shows the extract compositions, yi,t, plotted against Rt. The= 0.5 was larger than that in those with 0.5.

substantial mass transfers of studied compounds could be
detected with this bench scale column of which effective

Table.2 Densities of the materials
Materials
absorption oil
methanolaqueous methanol (yw,b = 0.3)
aqueous methanol (yw,b = 0.5)
raffinate phaseextract phase (yw,b = 0.3)
extract phase (yw,b = 0.5)

contact height was 0.495 m. In all the runs, yi,t increased withincreasing Rt. The nitrogen compounds transferred from feed

Density [kg·m-3]
1.1×103
7.9×1028.7×1029.2×102
1.1×103
8.8 ~ 8.9×102
9.2 ~ 9.3×102

into extract phase preferentially to the other compounds and theseparation between these compounds could be achieved. In
the low range of Rt, yi,t were smaller in the runs with Eb=2000
than in those with 1000, but the differences became small withincreasing Rt. It was because two phases in the column almost
reached equilibrium in the high range Rt,

3.2. Numerical relationships

Table 3 Compositions of feed oil

The holdup of dispersed phase in the column, H, was definedComposition in mass fractionquinoline
xQ,tisoquinoline
xIQ,tindolexIL,tnaphthalenexN,t1-methylnaphthalene
x1MN,t2-methylnaphthalene
x2MN,tbiphenyl
xBP,tdibenzofuran
xDBF,twater
xw,tmethanolxMeOH,tby
H = Vd / V(1)

The Vd and V in the equation were the volume of disperse phasein the column and the column volume, respectively. One canwrite the material balance relationship in terms of the masschange rates of constituents i in respective phases with themass fractions, as follows:
Rt·xi,t- Rb·xi,b = Et·yi,t- Eb·yi,b(2)

The yield, Yi, and separation selectivity relative to 2MN of

[-]
[-]
[-]
[-]
[-]
[-]
[-]
[-]
[-]
[-]

0.05 ~ 0.09
0.02 ~ 0.03
0.04 ~ 0.06
0.02 ~ 0.03
0.09 ~ 0.1
0.2 ~ 0.3
0.06 ~ 0.09
0.06 ~ 0.1
0 ~ 0.004
0 ~ 0.04

3.5. Yield and selectivity

component i, ßi/2MN, were defined by,

Figure 7 shows the yields Yi against Rt. Yi were bigger in theYi = Et·yi,t/Rt·xi,t,(3)

runs with yi,w = 0.3 than in those with 0.5 for the equilibrium

ßi/2MN = (yi,t/y2MN,t)/(xi,b/x2MN,b)(4)

relationship. In the range of this work, Yi of the nitrogen

The overall coefficient of mass transfer based on thecompounds were about 0.4 at maximum with this column,
28

Technical Report of International Development Engineering

TRIDE-2006-01, February 20, 2006 (ISSN 1880-8648)b: at bottom of the column
BP : biphenyl
DBF : dibenzofuran
IL : indole
IQ : isoquinolinei: component i
MeOH: methanolN: naphthaleneQ: quinolinet: at top of the column
W : waterwhile those of the other components were below 0.1. Figure 8
shows the separation selectivity, βi/2MN against Rt. βi/2MN of thenitrogen compounds were larger in the run with yw,b = 0.5 thanin those with 0.3 and about 30 at maximum.
3.6. Overall mass transfer coefficient
Figure 9 shows the overall volumetric mass transfer
coefficients based on the concentration in continuous phase,
Kc,i·a, against Rt. Kc,i·a increased with Rt, mainly due to thedecrease of diameter of dispersed phase drops and then that ofKey

The effects of Rt on
dp, [m]the increase of specific interfacial area, a.

-3

3×10

the overall mass transfer coefficient based on the concentrationin the continuous phase, Kc,i, are shown in Fig. 10. The axial
mixing was observed in the high range of Rt. Kc,i decreased

No.
EC1
EC2
EC3

-3

2×10

EC4
-3

1×10

with increasing Rt because concentration differences became

2

3

10

4

10

10

Rt [kg⋅hr ⋅m ]-1

smaller compared with the case to assume the plug flow in the-2

Fig. 3 Diameters of the dispersed phases

column. Kc,i in the case of higher solvent flow rate, Et, waslarger than those at the lower Et. Therefore, the laminar film in

0.12

continuous phase controlled the mass transfers.
0.08
H[-]

4. Conclusion
The extraction separation of absorption oil with thecontinuous apparatus was carried out favorably under the

0.04

conditions in this study. The yields, Yi, and selectivity, ßi/2MN, ofthem were about 0.4 and 30 at maximum, respectively. The
0mass transfers were explained in term of mass transfer

102

coefficients. The overall mass transfer coefficient based on the

103

104

Rt [kg⋅hr ⋅m ]-1

concentration in the continuous phase, Kc,i, decreased with-2

Fig. 4 Holdup of the dispersed phase, H: (the keys are theincreasing Rt because axial mixing occurred in the column. The

same as Fig. 3)

mass transfer resistance existed mainly in continuous phase.

103

Consequently, the useful information for the process design-3a [m ⋅m ]was provided.
102

2

Acknowledgment
AO was provided by JFE Chemical Corporation.

101

Nomenclatures: specific interfacial area
[m2·m-3]: superficial mass flow rate of aqueous phase[kg·hr- 1·m- 2]
H: holdup of the dispersed phase[-]
Kc :overall mass transfer coefficient based on theconcentration in continuous phase[kg·hr- 1·m- 2]
R: superficial mass flow rate of oil phase [kg·hr- 1·m- 2]
V: volume in the column[m3]x: mass fraction in oil phase[- ]y: mass fraction in aqueous phase[–]Y: yield[–]z: distance from top of the column[m]Z: effective contact height of column[m]βi/2MN: separation selectivity of component i relative to
2-methylnaphthalene[–]<Subscripts>
1MN : 1-methylnaphthalene
2MN : 2-methylnaphthalene

a
E

100
102

103

104

Rt [kg⋅hr-1⋅m-2]

Fig. 5 specific interfacial area, a:(the keys are the same as Fig. 3)

29

Technical Report of International Development Engineering

TRIDE-2006-01, February 20, 2006 (ISSN 1880-8648)

5

10
EC1
EC2
EC3
EC4
EC1
EC2
EC3
EC4

10-1

i

Key Run
EC1
EC2

Q

EC3

i

Key Run
EC1
EC2

1MN

EC4
EC1
EC2
EC3
EC4

(a)

Key Run
EC1
EC2

IL

EC3

EC4
EC1
EC2
2MN
EC3
EC4

IQ

i

EC3

BP

EC4
EC1
EC2
DBF
EC3
EC4

N

(a)

i

Kc,i⋅a [kg⋅hr-1⋅m-3]

Key Run

(b)

104

3

10

(b)
102

102

-2

10

103

102

103

10

4

Rt [kg⋅hr ⋅m ]yi,t [ - ]-1-2

Fig. 9 Overall volumetric mass transfer coefficients basedon the concentration in continuous phase, Kc,i ⋅a:(a) in EC1-3

10

and 3; (b) in EC2 and 4(the keys are the same as Fig. 6)
3

10

10

3

2

3

10

10

10

(b)

(a)

4

Kc,i [kg⋅hr ⋅m ]10-4 2
10

2

10

-1

-2

Rt [kg⋅hr-1⋅m-2]

Fig. 6 Extract compositions, yi,t:(a) in EC1 and 3; (b) in EC2
and 4
0.5

0.2

(a)

1

10

(b)

0.4
0

Yi [ - ]

10
0.3

102

103

102

103

104

Rt [kg⋅hr ⋅m ]
-1

0.1

-2

Fig. 10 Overall mass transfer coefficients based on the

0.2

concentration in continuous phase, Kc,i:(a) in
0.1

EC1 and 3; (b) in EC2 and 4

0
102

3

10

103

(the keys are the same as Fig. 6)

0
102

103

104

Rt [kg⋅hr-1⋅m-2]

Reference
1) Ukegawa, K., Matsumura, A., Kodera, Y., Kondo, T.,
Nakayama, T., Tanabe, H., Yoshida, S., Mito, Y., Sekiyu
Gakkaishi (J. Jpn. Petrol. Inst.), 33, (4), 250 (1990).
2) Kodera, Y., Ukegawa, K., Mito, Y., Komoto, M., Ishikawa,E., Nagayama, T., Fuel, 70, (6), 765 (1991).
3) Matumura, A., Kodera, Y., Kondo, T., Ukegawa, K., Tanabe,
H., Yoshida, S., Mito, Y., Shigen to Kankyo (Journal. ofNIRE), 4, (2), 147 (1995)
4) Egashira, R., Nagai, M., Sekiyu Gakkaishi (J. Jpn. Petrol.
Inst.), 43, (5), 339 (2000)
5) Egashira, R., Salim, C., Sekiyu Gakkaishi (J. Jpn. Petrol.
Inst.), 44, (3), 178 (2001)
6) Salim, C., Saito, J., Egashira, R., Journal of the Japan
Petroleum Insititute, 48, (1), 60 (2005)
7) Watanabe, K., Egashira, R., 34th Japan Petroleum Insititutemeeting, (2004)
8) Salim, C. Dissertation for a doctoral degree of engineering,Tokyo Institute of Technology (2005)

Fig. 7 Yields, Yi:(a) in EC1 and 3; (b) in EC2 and 4 (the keys
are the same as Fig. 6)

βi/2MN [ - ]

102

(a)

(b)

101

100

10-1
102

103

102

103

104

Rt [kg⋅hr ⋅m ]-1

-2

Fig. 8 Separation selectivity, βi/2MN:(a) in EC1 and 3; (b) in
EC2 and 4 (the keys are the same as Fig. 6)30

Technical Report of International Development Engineering

TRIDE-2006-01, February 20, 2006 (ISSN 1880-8648)

Preparation and Structure Control of Plasma Polymerized Films by Utilizing
Afterglow Region in Atmospheric Non-thermal PlasmaStudent Number: 03M18236

Name: Takuo MIURA

Supervisor: Hidetoshi SEKIGUCHI

大気圧非平衡プラズマのアフターグロー領域を利用した重合膜の作製とその構造制御
三浦 拓生
本研究では，大気圧下の非平衡プラズマにおいて，アフターグロー領域を活用した技術に着目し，アセチレンから有機系の重合膜の作製するとともに，その構造制御を試みた．様々なパラメータを操作して生成した膜の赤外分光スペクトルを比較した結果より，アルゴンの活性種が気相中で sp2 結合の生成を促進し，基板温度によって水素の結合が進む重合モデルを提示した．

1. Introduction

cases ethylene is used as a monomer) is introduced
through the inside of the cupper tube while argon
gas flows between the cupper tube and the quartz
torch. Three types of power supply with different
frequency range at 13.56 MHz, 200 – 1999 kHz
and 0.1 – 10 kHz are employed to generate plasma.
Carbon related thin films are deposited on
mono-crystal silicon wafer substrates which areopen to the atmosphere. The voltage and thecurrent are measured with an oscilloscope and thepower is calculated by numerical integration. In
this torch, the monomer gases are led into theafterglow region of the plasma, so that the bulk
plasma can be generated with only argon gas at low
power [6]. In the case of pulsed plasma, pulsed
condition is achieved by connecting a function
generator to the power supply.

Plasma assisted chemical vapor deposition(PACVD) technology by using atmospheric
non-thermal plasma has a potential use in a film
deposition on a substrate which is easily affectedby heat, such as plastics. In our laboratory, we
have succeeded to prepare the carbon related thinfilms by using atmospheric glow discharge(APGD) [1]. The carbon related films preparedby the PACVD can form as amorphoushydrogenated carbon (a-C:H), diamond like carbon(DLC) and organic thin films [2]. The organic thinfilms have various applications in mechanics,
electronics and optics [3]. In particular, the organic
films prepared by plasma, so called plasma
polymer, have unique structure represented by theirregular three-dimensional crosslinked network[4].
However, the structure control of the plasma
polymer has not been achieved due to a variety ofactive species produced in the plasma region [5]. It
causes a difficulty to design the molecular structureof the polymer and its properties.
Therefore, this work will exhibit the significant
factors in the structure of the plasma polymer underatmospheric conditions. The afterglow region of
the APGD is utilized because it can reduce theimpact of highly active species in bulk region
which can dissociate monomer gas into a various
species. Besides, pulsed plasma which is known
as a technique to reduce input power is also used toinvestigate the effect of pulse parameters.

Power Supply
Monmer Gas Inlet
Aluminum Foil
(Ground)

Flow Meter
Quartz Tube

Substrate Holder
Silicon Wafer Substrate

Teflon Joint

Cupper Tube
(High Voltage)
Carrier Gas Inlet

Fig. 1. Experimetnal apparatus

Ar

C2H2
(C2H4)

Deposited films are analyzed by Fourier
Transfer Infrared Spectroscopy (FT-IR). In thiswork, the sp2/sp3 ratio and CH3/CH2 ratio of the
carbon bond is measured by peak fitting of the
FT-IR spectra. The peaks between 2800 cm-1 and
3100 cm-1 assign C-H bond. The details of theassignments are shown in Table I.
The integrated intensity is applied for the peakratio. R(sp2/sp3) is defined as the ratio between
sp2 bond and sp3 bond while R(CH3/CH2) indicatesthe ratio between terminal carbon and chainedcarbon.

2. Experimental
Experimental set-up is shown in Figure 1.
Cylindrical quartz torch (diameter: 6 mm,
thickness: 1 mm) has a cupper tube (diameter: 2
mm, thickness: 0.5 mm) as inside high voltage
electrode and aluminum foil (width: 15 mm) as
outside ground electrode. Acetylene gas (in some31Technical Report of International Development Engineering

TRIDE-2006-01, February 20, 2006 (ISSN 1880-8648)

higher voltage at low frequency can produce higher
energy electrons and different excited argon species
which can cause quartz tube sputtering and oxygen
dissociation. The hypothesis can be supported by
the optical emission spectra (OES) of argon plasma
at the different power supply shown in Figure 3.
Some peaks get strong or weak by changing thefrequency.

Table I. Assignments of C-H bonds between 2800 cm-1
to 3100 cm-1 in IR spectrum (possibly shift in a few
Kayser)-1

Wavenumber [cm ]Assginment
3

2840−CH2 sp sym

2870−CH3 sp sym

3

3

2890

−CH sp2920−CH2 sp asym

2960

−CH3 sp asym

3000

=CH sp2

3025=CH2 sp olef

3055

=CH sp arom

3080

=CH2 sp asym

3300

1

3
3

0.6

2

10 kHzAbsorbance [–]22≡CH sp（sym: symmetric，asym: asymmetric，olef: olefinic，arom:
aromatic）

800 kHz

0.2
13.56 MHz

Experimental conditions are shown in Table II.
Three different power supplies are used in order tochange the frequency range. Pulse parameters areavailable under pulsed plasma conditions.

0Fig. 2.

Table II. Experimental conditions
Frequency

0.4

4000

3000
2000
–1
Wavenumber [cm ]1000

FT-IR spectra with different frequency

13.56 MHz
1

600 – 800 kHz
6 – 10 kHz

0.8

1 – 3 kVPower

2 – 40 W

Argon flow rate

20 – 50 sccm

Acetylene flow rate2 – 10 sccm

Deposition time

10 minPeriod (pulse)

1 – 20 ms

Duty (pulse)

20 – 60 %Absorbance [–]Voltage

10 kHz0.6

800 kHz
0.4

0.2

3. Results and Discussion
0400

3.1. FT-IR spectra at the different frequency range

Fig. 3.

In this work, plasma polymerized films wereprepared mainly from acetylene monomer by using
three different frequency range; 13.56 MHz, 600 –800 kHz and 6 – 10 kHz. Figure 2 shows thosetypical FT-IR spectra at each frequency.
Firstly, a peak around 3400 cm-1 observed at 6 –10 kHz frequency is noticeable compared to theother spectra. The peak indicates hydroxyl bondhaving −OH functional groups. Although it is not
likely for oxygen to get involved in thepolymerization with argon and acetylene, there area few possibilities such as ion etching of quartz
tube and air contamination in the afterglow region.
The major difference between 6 – 10 kHz and theother two cases is the voltage which is much higher
at low frequency. Thus, it is suggested that the

500

600
700
–1
Wavenumber [cm ]800

OES spectra with different frequency

Secondly, comparing the two spectra at 13.56
MHz and 600 – 800 kHz, the peak intensity around3000 – 3080 cm-1 assigning =CH with 13.56 MHz
seems to be higher than that with 600 – 800 kHz.
In fact, R(sp2/sp3) is 0.3 – 0.7 with 13.56 MHz
while it is 0.1 – 0.3 with 600 – 800 kHz in various
conditions. This is considered to be due to thepower difference because 13.56 MHz power supply
consumes much larger power than 600 – 800 kHz.
Large power can cause the high argon radicals
concentration and raise the energy level of theargon radicals. It also increases the temperatureof the reaction field. The effect will be discussed
further in Section 3.3.

32

Technical Report of International Development Engineering

TRIDE-2006-01, February 20, 2006 (ISSN 1880-8648)

As to R(CH3/CH2), it declined with argon flowrate while being constant with acetylene flow rate
in Figure 6 and 8. In Figure 10, R(CH3/CH2)
increased with the input power. The different
tendency with argon flow rate from R(sp2/sp3)
proposes a different mechanism.
In this case, the temperature has an effect on
R(CH3/CH2) because the temperature decreased
with argon flow rate but did not change withacetylene flow rate. Similarly, it increased with
the input power. Thus, it is suggested that hightemperature promotes hydrogen addition on thefilm as CH3 is mainly produced by a reaction
between activated carbon and dissociatedhydrogen.

Acetylene and ethylene were employed asmonomer gases at 800 kHz. Figure 4 shows that
there are three distinctive differences between thefilms prepared by acetylene and ethylene asfollows:

3

0.7

1.3

0.6

1.2

0.5

1.1

0.4

1.0

2

These characteristic differences are identical to
the report with low pressure plasma.

R (sp / sp )(1) Carbon triple bond assignment at 3300 cm-1
can not be observed in the case of ethylene.
(2) The stronger peak around 3000 – 3080 cm-1 isobserved under acetylene use conditions.
(3) Ethylene monomer makes the 2960 cm-1 peakstronger than the peak at 2920 cm-1 while
acetylene makes the opposite.

R (CH3 / CH 2)

3.2. Correlation between the monomers and thefilm structure

0.6

0.3

0.9

0.2

0.8

0

0.4

0

C2H4

0.7

20 40 60 80 100 120
Argon Flow Rate [sccm]

Fig. 5. R(sp2/sp3) withdifferent argon flow rate

3000
2000
–1
Wavenumber [cm ]1000

Fig. 4. FT-IR spectra of the films with different
monomers; acetylene (C2H2) and ethylene (C2H4)

1.1

0.4

1.0

0.3

0.9

0.2

0.8

0.1
0

3.3. Effect of the argon and acetylene flow rates
and the input power

0

0.7

2
4
6
8 10 12
Acetylene Flow Rate [sccm]

0.7

3
2

2
4
6
8 10 12
Acetylene Flow Rate [sccm]

1.3

0.6

1.2

0.5

1.1

0.4

1.0

0.3

0.9

0.2

0.8

0.1
0

0

Fig. 8. R(CH3/CH2) withdifferent acetylene flow rate

Fig. 7.
R(sp2/sp3) withdifferent acetylene flow rate

R (sp / sp )R(sp2/sp3) and R(CH3/CH2) were measured withdifferent argon and acetylene flow rates and input
power by using 13.56 MHz power supply.
As shown in Figure 5 and 7, R(sp2/sp3) slightly
increases with argon flow rate, however it does notchange with acetylene flow rate. Figure 9 showsR(sp2/sp3) rises as the input power increases. The
increase of the argon flow rate causes intenseinterference between argon and the other species,
such as acetylene and its polymerized particles.
On the other hand, the acetylene flow rate cannot
affect R(sp2/sp3).
Therefore, the argon species including radicals
and ions are considered to have an increase effecton the sp2 bond. It is supported by the power
dependence because higher power can increase theeffect of the activated argon species in terms of theconcentration and the energy level.

1.2

R (CH3 / CH 2)

4000

1.3

0.6
0.5

20 40 60 80 100 120
Argon Flow Rate [sccm]

Fig. 6. R(CH3/CH2) withdifferent argon flow rate

0.7

2

0

0

R (CH3 / CH 2)

C2H2

3

0.2

R (sp / sp )Absorbance [–]

0.1

20

30
Power [W]40

Fig. 9.
R(sp2/sp3)
with different power

0.7

20

30
Power [W]40

Fig. 10. R(CH3/CH2)
with different power

3.4. Reaction mechanism with respect to R(sp2/sp3)
and R(CH3/CH2)
According to the discussion above, R(sp2/sp3) isaffected by argon radicals and ions. As for33

Technical Report of International Development Engineering

TRIDE-2006-01, February 20, 2006 (ISSN 1880-8648)

wave power supply (CW), low R(sp2/sp3) isobserved at long period and short duty, and highR(CH3/CH2) is observed at short period and large
duty.
1.2

0.5

1.1

0.4

1.0

0.3

CW

0.2

0.9

0

5

10
15
Period [ms]20

25

Fig 14. R(sp2/sp3) withdifferent period

0.7

0.6

1.2

1.2

0.5

0.2
0.1
Untreated Heated Ar exposure

Fig 11. Effect of heat
and argon plasma on
R(sp2/sp3)

0.8

0

0.7

Untreated Heated Ar exposure

CW

0.2
0.1

0.9

R(CH3/CH2)

20

25

CW

0.8

0

20

40
60
Duty [%]

80

100

Fig 16. R(sp2/sp3) withdifferent duty

Fig 12. Effect of heat
and argon plasma on

1015
Period [ms]

1.0

0.3

0.9

5

1.1

0.4

2

1.0

0.3

0

3

R (CH3 / CH 2)

0.4

R (CH3 / CH 2)

1.3

0.6
R (sp / sp )

0.7

1.1

0

Fig 15. R(CH3/CH2) withdifferent period

1.3

0.5

CW

0.8

0.1
0

R (CH3 / CH 2)

1.3

0.6

2

3

R (sp / sp )

0.7

0.7

2

3

R (sp / sp )R(CH3/CH2), temperature has a significant effecton the ratio. From a complementary experimentshown in Figure 11 and 12, it was found that thepost treatment of the prepared film by heat shows
significant decline of R(sp2/sp3) and R(CH3/CH2)
while argon plasma has little effect on them.
Considering the results of the plasma effects that
increase both ratios, the post treatments is not thesame with the plasma effects.
These results indicate the activated argon
species promote sp2 increase in the gas phase noton the substrate. Besides, hydrogen addition canbe occurred at high temperature in the presence ofhydrogen radicals.
The reaction model proposed above isvisualized in Figure 13.

0.7

0

20

40
60
Duty [%]

80

100

Fig 17. R(CH3/CH2) withdifferent duty

Even though no satisfactory mechanism can beproposed through these experiments, these results
show the potential of the pulsed plasma to control
the plasma polymer structure.

4. Conclusions
In this research, plasma polymerized films wereprepared using afterglow region and the film
structure was analyzed by FT-IR at different
conditions. From the behaviors of R(sp2/sp3) andR(CH3/CH2), the reaction mechanism was proposedin relation to argon and hydrogen radicals.
Besides, we found the potential of pulsed plasma tocontrol the plasma polymer structure.

5. References

Fig 13. Polymerization mechanism[1] Miura, T., Sekiguchi, H., Transactions of theMaterials Research Society of Japan, 29(2004) 3411
[2] Robertson, J., Phil.Mag., 76 (1997) 335[3] Frank F.S., Surf. Coat. Technol., 82 (1996) 1[4] Tibitt, J.M., Shen, M., Bell, A.T., J. Macromol.
Sci., Chem. A10 (1976) 1623
[5] Biederman, H., Osada, Y., Advances in Polym.
Sci., 95 (1990) 57[6] Leveille, V., Cooulombe, S., Plasma Sources
Sci. Technol., 14 (2005) 467

3.5. Pulsed plasma conditions
Under the pulsed plasma conditions at 800 kHz
frequency, R(sp2/sp3) and R(CH3/CH2) were
measured by changing period and duty.
From the results shown in Figure 14 and 15,
both of the R(sp2/sp3) and R(CH3/CH2) decreased
with period. On the other hand, both ratios
increased with duty as described in Figure 16 and17. Compared to the results with continuous

34

Technical Report of International Development Engineering

TRIDE-2006-01, February 20, 2006 (ISSN 1880-8648)

NUMERICAL ANALYSIS FOR SOLIDIFICATION OF MELT PLASTIC
WITH A SPECTRAL FINITE DIFFERENCE SCHEME
04M18179 Aya FUJITA Supervisor: Yoshihiro MOCHIMARU

スペクトル差分法を用いた溶融高分子の凝固解析
藤田

文

プラスチックは今日，工業において必要不可欠な材料で，使用分野は多岐に渡る．金型内で溶融高分子を冷却することによって成形されるプラスチックの流動過程は，溶融高分子が液体から固体に相変化するため，非常に複雑な現象であり，実験室的に実現することが難しく，数値計算によって解析を行うことが求められている．本研究では，計算精度の高いスペクトル差分法を用いて計算を行い，形状内の温度場と流れ場の特性を明らかにすることができた．

1. Introduction
Plastics contribute to improvement of human life,
for example as parts of electrical or medical appliances,elements of automobiles, casing of food, and housing
elements. Thus, demand for plastics has been
increasing year by year for refinement on production
process, and alternatives of the materials to reduce
product weight. Also, with expansion of industries inwhich plastics are used, higher molding technique thanever has been needed.
Phenomena in plastic molding are very complicated,since the flow in the process is non-isothermal andunsteady with phase change from liquid to solid.
Moreover, melt plastic is non-Newtonian withvisco-elasticity. These characters of the fluid and flow
make it difficult to predict the flow and thermal fields
analytically. Many researchers had studied the
behavior of non-Newtonian fluid and solidification
problem of water or other Newtonian fluid. However,the problem of solidification of non-Newtonian fluid
has not been investigated very much, so far. Therefore,
in this study, numerical analysis for solidification ofmelt plastic with phase change was performed to theshape which has right angle branch, where a spectral
finite difference method was used as a computational
scheme with higher accuracy.

∇ ⋅V = 0(2-1)

DV= −∇p + ∇ ⋅ τ + ρg
(2-2)
Dt
DT
ρC p
= k∇ 2T(2-3)
Dt
where t: time, τ: extra stress tensor, p: pressure, V:
velocity vector, ρ: density, Cp: specific heat, T:
temperature, k: thermal conductivity, g: acceleration
vector of gravity. It was assumed that the flow wasincompressible and laminar, and that the thermo physical properties were constant in each phase except
for viscosity. For the above governing equations, theeffect of natural convection was taken into account.
In case of formulating with the stream functionvorticity method, vorticity transport equation obtained
from the equation of motion and the equation ofrelationship between vorticity and a stream function ina Cartesian coordinate are given in a dimensionlessform as,ρ∂ζ ∂ψ ∂ζ ∂ψ ∂ζ+−∂t∂y ∂x ∂x ∂y⎛ ∂ 2τ xy ∂ 2τ xy ∂ 2τ xx ∂ 2τ yy ⎞⎟ + PrRa ∂θ−+−= Pr ⎜
2⎜ ∂x 2∂x∂x∂y∂x∂y ⎟⎠∂y⎝(2-4)⎛ ∂ 2ψ

∂ 2ψ ⎞⎟∂y 2 ⎟⎠

2. Numerical analysis
2-1. Governing equations

ζ = −⎜⎜

Governing equations are the equation of continuity,
the equation of motion and the equation of energy,
which can be expressed aswhere ζ: vorticity, ψ: stream function, Pr=ν /a: Prandtl
number, Ra = gβ∆TH3 / νa: Rayleigh number, ν =µ /ρ:kinematic viscosity, µ = µ0 exp( ∆Ĥ /R (1/ T- 1 / T0)):

⎝ ∂x

35

+
2

(2-5)

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TRIDE-2006-01, February 20, 2006 (ISSN 1880-8648)

viscosity, ∆Ĥ : activation energy, R: universal gas yy component:
constant, a: thermal diffusivity, H: characteristic length,⎧ ∂τ yy ∂ψ ∂τ yy ∂ψ ∂τ yy+−
β: coefficient of volume expansion. Buoyancy in the τ yy + We⎨
∂t
∂y ∂x
∂x ∂y
⎩
vorticity transport equation is expressed with adopting
2
2
⎛∂ ψ
⎞⎫⎪
∂ψ
∂ 2ψ
Boussinesq approximation.
+ 2⎜⎜ 2 τ xy +τ yy ⎟⎟⎬ = −2
∂x∂y
∂x∂y
⎝ ∂x
⎠⎪⎭

where τxx, τxy, τyy: components of extra stress, We:
Weissenberg number. In case of We = 0, the equations
just express a Newtonian fluid.

2-2 Modeling of solidification
If high temperature melt plastic is cooled, the phaseof plastic changes from liquid phase to transition phaseat melting temperature (Tm). Then, as plastic is cooled
more, the phase changes to solid at solidification
temperature (Ts). The gradient of heat capacity
between Tm and Ts is very large since latent heat isemitted between Tm and Ts. Therefore, duringsolidification, there exists three phases in the mold,which requires three types of energy equation. Specificheat was assumed to be of the form,⎧ ρ s c ps⎪
ρL⎪
ρC p ' = ⎨ ρ c p +T
m − Ts⎪⎪⎩ ρ l c pl

(2-9)

2-4 Coordination transform
For applying the spectral finite difference scheme toa right angle branch shape, the following conformal
mapping from Cartesian coordinate (x, y) to aboundary - fitted conformal coordinate (r, β) wasapplied.
(2-10)
r = exp α(T ≤ Ts)f = eα +iβ = (1 + iη ) (1 − iη )(2-11)( Ts < T < Tm )

η = −ciz1 2 + z1 + 1 z1

(2-12)

z1 = z 2 + b1

(Tm ≤ T)2(z 2 − 1) + b2 2 (z 2 + 1)⎛
2⎜
H 1 tan −1π ⎜⎜⎝≡ x + iywhere L: latent heat, Cp’: apparent specific heat. Thus,
the phase change problem is expressible in a single
energy equation, which is in the stream function –vorticity formulation in a Cartesian coordinate.

w=z2
aH − z222+ H 2 tanh −1(2-13)
H2
H1

⎞
⎟
2
2 ⎟
a H − z 2 ⎟⎠z2

，aH2 = 1 + H22 / H12(2-14)
Where c, H1, H2: constant and 0 ≤ r ≤ 1 , −π ≤ β ≤ π .
Figure 1 shows the coordinate system for analysis at c
= 1.0, H1 = H2 =1.0 and b1 = b2 = 1.0×10-3. In thiscoordinate, the space was divided into a suitable
number, M, in r direction and rM was defined at theboundary and r0 (r = 0) at the center of coordinate.

⎛ ∂θ ∂ψ ∂θ ∂ψ ∂θ ⎞ ⎛ ∂ 2θ ∂ 2θ ⎞⎟ (2-6)⎟=⎜+−+C p * ⎜⎜∂y ∂x ∂x ∂y ⎟⎠ ⎜⎝ ∂x 2 ∂y 2 ⎟⎠⎝ ∂twhere Cp*: dimensionless apparent specific heat, θ:dimensionless temperature.

2-3 Constitutive equation
In this study, Maxwell model was used as aconstitutive equation. Components of the Maxwell
model equation arexx component:⎧ ∂τ xx ∂ψ ∂τ xx ∂ψ ∂τ xx
+
−
∂y ∂x
∂x ∂y
⎩ ∂t

r

β
β = -πβ = -π/2

τ xx + We⎨⎛ ∂ 2ψ
⎞⎪⎫
∂ 2ψ
∂ 2ψ
− 2⎜⎜
τ xx + 2 τ xy ⎟⎟⎬ = 2∂x∂y∂y⎝ ∂x∂y⎠⎪⎭β = π/2(2-7)

xy component:⎧ ∂τ xy

τ xy + We⎨

⎩ ∂t

+

∂ψ ∂τ xy ∂ψ ∂τ xy
−
∂y ∂x
∂x ∂y

⎛ ∂ψ
⎞⎪⎫ ⎛ ∂ 2ψ ∂ 2ψ ⎞∂ 2ψ− ⎜⎜ − 2 τ xx + 2 τ yy ⎟⎟⎬ = ⎜⎜ − 2 + 2 ⎟⎟
∂y
∂y ⎠
⎝ ∂x
⎠⎪⎭ ⎝ ∂x
2

(2-8)
β =0

Fig.1 The coordinate system for analysis.

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2-5 Spectral finite difference formulation

dimensionless

The spectral expressions of variables by using
Fourier series are⎡ψ sk (r , t )⎤⎡ψ ck (r , t )⎤⎡ψ ⎤⎢ζ ⎥ ∞ ⎢ζ (r , t ) ⎥∞ ⎢ζ (r , t ) ⎥⎥ sin (kβ )⎥ cos(kβ ) + ∑ ⎢ sk
⎢ ⎥ = ∑ ⎢ ck
k =1 ⎢θ sk (r , t ) ⎥⎢θ ⎥ k =0⎢θ ck (r , t ) ⎥⎢⎣τ sk (r , t ) ⎥⎦⎢⎣τ ck (r , t ) ⎥⎦⎣⎢τ ⎦⎥(2-15)
ψck and ψsk…are Fourier coefficients that are thefunction of r and t. Then, substituting these variables
to Eq. (2-4) - (2-9), the equations are generally formed
as follows:
∞

∞

n =0

n =1

∑ Fcn (r , t ) cos(nβ ) + ∑ Fcn (r , t )sin (nβ ) = 0(2-16)The spatial variable β is separated and a system ofsimultaneous partial differential equations (withrespect to one spatial variable r and time t) is obtained.

(a) Time step = 200(∆ψ = 1.0×10-1, ∆θ = 5.0×10-1).

2-6 Boundary conditions
The fluid was assumed to be substantially
incompressible, so that no slip flow at the boundary
was assumed. The conditions become ψ = 0,∂ψ ∂r = 0 and θ = 0 at the boundary. Also, auxiliary
conditions at r = 0 (r = r0) were introduced. The
conditions of extra stress were obtained from theconditions of stream function.

3. Results and discussion
The material was assumed to be polyethylene. The
properties of polyethylene are shown in Table 1.

(b) Time step = 600(∆ψ = 1.0×10-1, ∆θ = 5.0×10-1).

Table 1 The properties of polyethylene.
PropertyValueρ [kg/m ]k [W/(mK)]

954
0.182

L [kJ/(kg)]∆H /R [K]

135.3

3

4.5×103

Fluid in the shape was assumed to be at rest before
the computation starts and the initial temperature andthe wall temperature were assumed to be 450K and
303 K respectively. Pr was fixed at 2.2×106 and We
was order of 10-2(c) Time step = 1000(∆ψ = 1.0×10-2,∆θ = 5.0×10-1).
Fig.2 The streamlines and isotherms
at PrRa = 1.0×105.

3-1 Flow and temperature field
Figure 2 shows streamlines and isotherms in the left
half and in the right half respectively. Among theisotherms, the temperature of the thick ones is under37

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dimensionless solidification temperature, θs. Fromthese figures, the process of cooling of hightemperature melt plastic can be observed. At the
beginning of the computation, the distance between
isotherms near the right angle is small, which showsthat the temperature gradient is large there. The
direction of flow (in the left of the figure) is
counterclockwise. The distance between streamlines issmall near the boundary of the phase since thetemperature difference is large there.

4
r Outer= r M-1
3.5

r Inner= r M-2

3

θ

2.5
2

Liquid

1.5

Transition1

3-2 Cooling curve

Solid

0.5

Figure 3 shows cooling curves near the wall at theright angle. The thick line shows the temperature next
to the wall, rM-1, and the thin line, rM-2. Dimensionlessmelting temperature, θm is 1.7 and θs is 1.0. This result
has the characteristic tendency which the cooling curveof material without phase change does not have. In
Fig.3, the temperature behavior changes at θm and θssince the latent heat is emitted between θm and θs.

0

400

300

200
Time steps

100

Fig.3 The cooling curve at PrRa = 1.0×105.
30

F

A

E
D

25

C

B

B

C
D
E

A

20

3-3 Nusselt number changes with timeF

Nu

Local Nusselt number, the dimensionless heat transfer coefficient, was calculated at r = rM-1 as,∂θ
Nu = −(3-1)∂r
Figure 4 gives the comparison of the change of Nu
with locations shown in Fig. 4. At the right angle, point
C in Fig. 4, Nu is the largest all the time, since thetemperature gradient is largest at this point, which isfound in Fig. 2. Figure.5 shows the comparison of Nu
with PrRa at the right angle. As PrRa is larger, thechange of Nu with time becomes sharper, since coolingof the melt plastic is advanced more at higher PrRa.

15

10

5

0

1

2
Time [s]34Fig. 4 Local Nusselt number at PrRa = 1.0×105.
35

PrRa =
1.0×105
103

30

4. Conclusion

101

25

In this study, using the spectral finite difference
scheme to solidification phenomenon of the melt
plastic, the characteristics of the flow and thermal
fields in the right angle branch were explained.

10-1

Nu

20
15

References

10[1] Yoshihiro MOCHIMARU, Effectiveness of a spectral
finite difference scheme, Comput. Fluid Dyn. Rev., 1998,

5

1(1998), pp. 563-568[2] Esam M. Alawadhi, Phase change process with free0

convection in a circular enclosure: numerical simulations,Comp. & Fluids, 2004, 33(10), pp. 1335-1348

10

20

30
Time [s]

40

50

60

Fig.5 Comparison of Nusselt number with PrRa.

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The effect of probe shape and wettability
for expanding applicability of micromanipulation using capillary force
Student Number: 04M18067 Name: Kenichi J. OBATA Supervisor: Kunio TAKAHASHI

操作プローブの先端形状と材質が
液架橋力マイクロマニピュレーションの適用範囲拡大に及ぼす影響
尾畑 賢一
現在，高機能材料やマイクロデバイスの開発を目的に，微小構造物を精緻に操作・組立する技術が求められている．
微小環境では凝着力が支配的なため，凝着現象を考慮したマニピュレーション手法が必要である．液架橋力を用いる
手法は対象物を傷つけない点などで優れており，実用化が期待されている．ところが従来提案された手法では，液体体積に対して液架橋力の制御可能範囲が小さいことが問題であった．そこで本研究では，液体体積制御による微小物
体操作の適用範囲を拡大するために，捕捉時には液架橋を大きく，配置時には液架橋力が小さくなるようなプローブ
形状を提案し，液架橋力の理論解析と実証実験を通して，その実現可能性を検証した．

scheme, it is assumed that the object shape is spherical,
and the probe and substrate surfaces are flat. The
profile of a liquid bridge between two solids wasanalyzed based on Orr’s theory [8], and the force
generated for the profile was presented clearly. These
analyses have indicated the feasibility of the proposed
scheme. The range of the force, however, never seems
large enough for practical/reliable micromanipulation.
In this study, we propose a probe with a concave-tip
as shown in Figure 1. The concaved probe-tip would
generate greater capillary force than a flat probe-tip sothat it can expand the possibility of picking up
manipulation. If a large amount of liquid was supplied,liquid must overflow to a flat surface, and capillary
force would be equivalent to the flat probe-tip case forsuccessful placing. Through both numerical estimationand its experimental verification, the magnified rangeof capillary force is presented as a function of
concavity radius, wettability, and liquid volume.

1 Introduction
Recently, micromanipulation techniques have been
in demand to fabricate highly functional micro-devices
or micro-electro-mechanical-systems (MEMS). In
micromanipulation, the influence of adhesional force isextremely large compared to gravitational force [1,2].
Furthermore, adhesional force has large dispersion
because of its dependence on surface condition such as
surface roughness, at each contact point. Thus, in orderto realize reliable micromanipulation, we need a force
that is controllable and greater than the adhesional
force, or some mechanism to avoid the dispersion ofadhesional force. Saito et al. have investigated themechanical force required to slip and roll an object inconsidering the adhesional effect [3]. The mechanicalmethod, however, might damage the object. Takahashi
et al. have evaluated the force generated by Coulombinteraction [4], although the electrostatic method mightcause a discharge or melt an object [5]. In order toavoid damaging the manipulated object, use ofcapillary force is considered effective if use of liquid isallowed. Actually, Tanikawa et al. have picked/placed
an object with a micro-hand and a micro-drop [6], butthey have not provided any analysis of the capillary
force involved. We have proposed a scheme formicromanipulation based on capillary force byregulation of the liquid volume [7]. In our previous

Figure 1: Schematic illustration of manipulation
procedure: (I) positioning, (II) lowering, (III) pickingup, (IV) positioning, (V) lowering, and (VI) placing.

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2H =

d
sin ε
(sin ε ) +
.
dX
X

(3)

Figure 2: Liquid bridge between a spherical object anda concave prove-tip: (a) whole menisci and (b) menisci
end at probe surface.

Since the Laplace pressure ∆P is hydrostatic, and thus,
constant at any local point, the local mean curvature H
is also constant anywhere on the meniscus. Therefore,
this equation can be solved as a two-point
boundary-value problem. The boundary conditions are
written as

2 Analysis of capillary force

 ε 1 = ϕ + θ1 ,ε 2 = π + φ − θ 2 ,(4)

Once the profile is obtained, H is determined fromequation (3), and F is obtained from equation (1). For
generalization, some parameters are normalized as thefollowing equation:

Figure 2 shows an axisymmetric model for the
analysis of a liquid bridge between a spherical object
and a concave probe-tip, where R is the radius of theobject, Rp is the radius of the concave curvature, D isthe distance from the concave probe-tip to the object, ϕis the filling angle of the object, φ is the filling angle ofthe probe-tip, F is the attractive force acting on theobject, and V is the volume of the liquid between two
solids. The meniscus forms contact angles θ1 at theobject and θ2 at the probe-tip. The profile of the liquid
bridge is expressed by the coordinates(X, Z). The valueof ε expresses the angle between the normal to themeniscus and the vertical axis. We make the following
assumptions. (i) The influence of gravity is negligible
and the profile of the liquid bridge follows
Young-Laplace equation [8]; (ii) the dynamic flow of
the liquid is negligible; (iii) the volume of the liquid isconserved; (iv) the contact angles are determined byYoung’s equation [2]; (v) The object and the probe areideally rigid. The capillary force acting on the object isthe sum of the pressure difference and the axial
component of the surface tension, i.e.,

F = −∆PπX 1 + 2πσX 1 sin ε1 ,X 1 = sin ϕ ,X 2 = Rp sin φ .

x=

X
Z
D
, z= , d= ,RRR

and rp =

Rp
R

.

f =

F
V
, v= 3,πRσR(5)Figure 3 shows a relation between the normalized
maximum capillary force and the normalized concavity
radius for v = 0.10. Both horizontal and vertical scale islogarithmic. Note that the variable horizontal axis is
not rp but rp-1. Maximum value of the capillary force isthe critical value of the object detachment from theconcaved probe-tip. This figure suggests that as theradius of concavity approaches to the sphere, themaximum capillary force increases drastically. If theobject and probe have smaller contact angles, capillary
force becomes much larger than that for relatively
large contact angles.

(1)

where ∆P is the Laplace pressure which is pressure
difference between inside and outside of meniscus, σ isthe surface tension of the liquid, and X1 and ε1 is the X
coordinate and the ε-angle, respectively, at themeniscus end of sphere side.
The Laplace pressure can be expressed by Laplace
equation, which relates the pressure difference to themeniscus profile;∆P = 2 Hσ ,(2)where H is the local mean curvature which can be
written by the meniscus geometry [8];Figure 3: The effect of the probe-tip curvature on the
maximum capillary force for v = 0.10.

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polytetrafluaroethylene: PTFE); with Rp = 3.1×10−3 m(of stainless steel). Spherical objects of several sizes
were attached to steel rods. With the combination of
the radii, the value of rp can be set to 1.033–1.562.
Contact angles for the materials were determined byobserving the edge of a water-drop deposited on a plateusing a video microscope: 50° for glass, 75° forstainless steal, and 85° for PTFE.
Figure 6 shows the measurement value of thecapillary force as a function of the distance d for theliquid volume v = 0.08. The experimental value of thecapillary force is obtained as square marks in an
approaching process, and as triangle marks in a
detaching process. Such hysteresis occurs due to theinequality of the contact angle between these processes.
The broken line and the dotted line denote thetheoretical value of the capillary force for the fixedcontact angle θ1 = θ2 = 60° and 75° (Sliding Mode [9]).
The solid line denotes the value of the force for thecontact angle transition from 60° to 75° (Pinning Mode[9]). Note that the maximum value of the capillary
force never achieves the theoretical maximum during
Pinning Mode.

Figure 4: Relation between the normalized maximum
capillary force and the normalized liquid volume for θ1= θ2 = 60°.
On the other hand, the capillary force should be
reduced for placing manipulation. The solid lines in
Figure 4 shows a relationship between the normalized
maximum capillary force and the normalized liquidvolume for θ1 = θ2 = 60° and rp = 1.1, 1.2, 1.5, and ∞ .
The infinite value of rp means the sphere-plate model.
As approaching rp to 1, the force difference regulatedby the liquid volume can be expanded. This means thatthe force control by the liquid volume is valid forreliable micromanipulation.

3 Measurement of capillary force
Figure 5 shows the experimental system used. The
experiment was performed in atmosphere. The order ofthe object size was determined according to the Bond
Number (ρgR2 /σ, where ρ is the density of the fluidand g is the gravitational acceleration). Since theinfluence of gravity is negligible as long as the Bond
Number is small enough, we adopted R = 1.984–3.175
×10-3 [m] for the object radii corresponding to thebond number ρgR2 /σ = 0.53–1.35, which might shift
the capillary force due to the gravity no more than 10%.
The liquid used was purified water with σ = 0.073[N/m], which was refined through ion-exchange
membrane process. A micro-pipette with a volume
resolution of 2⋅10−11 [m3] was used to determine thevolume of the liquid. An electronic balance (Sartorius,
TE153S) with a resolution of 10−5 [N] was used tomeasure the force between the object and the probe-tip.
Automatedprecisestages(Suruga
Seiki,−8
K701-20LMS) with a resolution of 5×10 m wereused to adjust the position of the object and the probe.
Probes having concave tips were fabricated with Rp =3.1 × 10−3 m and 3.3 × 10−3 m (of glass andFigure 5: Schematic illustration of experimental system
used.

Figure 6: Capillary force-curve for glass specimen forrp = 1.19 and v = 0.08.

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volume v > 0.1. In the case of v < 0.1, the experimental
value of capillary force and the calculation considering
contact angle hysteresis (broken lines) are almost thesame. Assuming transition distance dpin is constant, thecapillary force is reduced with decreasing liquidvolume. This means that too small supply of liquidcauses less capillary force generated. In order to realize
efficient and reliable manipulation, the normalized
liquid volume should be controlled from 0.1 to 10.

4 Conclusion
This study clarifies the most important factors forreliable capillary micromanipulation by concave probe,
i.e. the material wettability, the concave shape anddimension, and the amount of liquid supply. The shapeof the probe-tip can be designed as shown in Fig. 1 sothat the range of the capillary force can be extended
due to the change of the apparent contact angle for agiven liquid volume. If the outer flat part of the glassprobe, for instance, is coated with large-contact-angle
material such as PTFE, the expanded range of thecapillary force can be expected. This suggests thatmicromanipulation by capillary force has a great
potential for a wide range of applications.

Figure 7: The effect of concavity radius and wettability.

References

Figure 8: Relation between the normalized maximum
capillary force and the normalized liquid volume forglass specimen and rp = 1.116.

[1] K. L. Johnson, K. Kendall, and A. D. Roberts, Proc. R. Soc.
London, Ser. A, vol. 324, pp.301, 1971.
[2] J. Israelachvili, “Intermolecular and Surface Forces”,

The relations between the normalized maximum
capillary force fcap. and the normalized radius ofconcaved curvature rp for a given normalized liquidvolume v = 0.08 are shown in Figure 7. Lines denotethe values estimated from the numerical analysis forcontact angles θ1 = θ2=50°, 75°, and 85°. Circle, square,
and triangle marks denote the values actually measured
in the experiment. The experimental results are in good
agreement with the theoretical predictions for all threematerials. The force fcap. drastically increases as rp
approaches 1. Probes made of the material with small
contact angle generate much larger capillary force.
As shown in Figure 8, magnified capillary force canbe controlled by the regulation of liquid volume. Circle,
triangle, and square marks are expressing theexperimental values. These are in good agreement withtheoretical predictions for the range of the liquid

Academic, New York, 1985.
[3] S. Saito, H. T. Miyazaki, T. Sato, and K. Takahashi, Journalof Applied Physics, vol. 92, pp.5140, 2002.
[4] K. Takahashi, H. Kajihara, M. Urago, S. Saito, Y.
Mochimaru, and T. Onzawa, Journal of Applied Physics vol. 90,
pp.432 2001.
[5] S. Saito, H. Himeno, and K. Takahashi, Journal of Applied
Physics, vol. 93, pp.2219, 2003.
[6] T. Tanikawa, Y. Hashimoto, and T. Arai, Proceedings, 1998
IEEE International Conference on Intelligent Robots andSystems IEEE, Piscataway, NJ, pp. 776, 1998.
[7] K. J. Obata, T. Motokado, S. Saito, and K. Takahashi, J.
Fluid Mechanics, vol. 498, pp.113 2004.
[8] F. M. Orr, L. E. Scriven, and A. P. Rivas, J. Fluid Mechanics
vol. 67, pp.723, 1975.
[9] Oliver Pitois and Xavier Chateau, Langmuir vol. 18,
pp.9751-9756, 2002.

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A manipulation method of a dielectric micro-particle by electrostatic force
Student Number: 04M18216

Name: Min HAN

Supervisor: Kunio TAKAHASHI

静電気力による微小誘電体操作法
静電気力による微小誘電体操作法
韓 敏
本研究では、静電場数値解析によって、静電気力を用いた微小誘電体操作の可能性を示し、その検証実験を行った。
異なる材料の誘電体微小球に対して、再現性を調べた。さらに、実験現象に基づき、操作メカニズムを解明した。以上より、静電気力を用いた微小誘電体操作を実現させることを目的とする。

to show the possibility of manipulation. Based on theanalytical results, we do the experimental study using
two different types of dielectric sphericalmicro-particles to verify the reproducibility ofmanipulation. In addition, the mechanism of themanipulation is clarified according to the experimentphenomena. Therefore, the purpose of the present
research is to realize the dielectric micro-particle
manipulation by electrostatic force.

1 Introduction
In micro-manipulation, the adhesional force isdominant since the adhensional force is proportional to
the first power of the object size [1], whereas thegravitational force is proportional to the third power ofthe object size. In order to manipulate a micro-particle,
it is necessary to generate the force which is larger than
the adhensional force between objects.
It is generally known that electrostatic force can beeasily controlled and is effective for the generation of alarge force. In recent years, many researches withregard to electrostatic methods for manipulating a
conductive micro-particle have been carried out.
Takahashi et al. used the boundary element method(BEM) to analyze the applied voltage required for
detachment in electrostatic micro-manipulation[2].
Based on the analysis results, Saito et al. did theexperiments to determine the voltage required for
detachment. The results of experiment are in good
agreement with the analysis. Simultaneously, thekinetic control of the detached particle has beenrecognized to be indispensable to place the particle on
the substrate plate without any excessive impact [3]. By
considering the total work to the particle during theflight , Saito et al. clarified the condition of voltage andtime for the non-impact manipulation of a particle [4].
Kurihara did the experimental verifications Based on
the results of Saito et al. [5].
However, no research has been done to investigate
the detachment of a dielectric micro-particle. "Can we
use the electrostatic micro-manipulation to detach adielectric micro-particle?" Even the possibility ofmanipulation by electrostatic force is still unknown.
In the present research, the boundary element
method (BEM) is used to evaluate the Coulomb forces

2 Analysis of static electric field
A. Analysis Model

FIG. 1. A schematic illustration of the model used.

Figure 1 shows a schematic illustration of the modelused. The system consists of three objects: A
conductive manipulation probe, a dielectric sphericalparticle, and a conductive substrate plate. The
manipulation probe is assumed to be cylindrical with alength Lm and a radius Rm. The spherical particle with aradius Rs is right under the center of the probe tip. The
plate is assumed to have an infinite plate. Thus, thesystem has axial symmetry. The calculations arecarried out through the use of the mirror images of theobjects.
The charge density is assumed to be linear between
the ith nodal Pi and the (i+1)th nodal point Pi+1; the143Technical Report of International Development Engineering

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charge density at point P between Pi and Pi+1 isassumed to beq = (1 − s )qi + sqi + 1

3
Fadhesion = π∆γRs ,2(1)where ∆γ is the work of adhesion, which is thewhere qi is the charge density at Pi.
The voltages V1-VN can be written as a linear
combination of charge densities q1-qN; i.e.,

V = A⋅ qenergy change from the surface to the interface per unit
area [1].
The voltage required for pick-up can be obtained
from
FCoulomb > Fadhesion.
(2)
Therefore, the voltage for pickup can be plotted as
Figure 3. In Figure 3, the required voltage is obtained
as a function of the normalized radius of themanipulation probe.

(2)

where A is the matrix whose elements are determinedfrom the size of the objects.
Normal directions of the static electric fields nEk-nElof the sphere can be written as a linear combination of
charge densities q1-qN; i.e.,

Esphere = Dsphere ⋅ q

109
V/Rs(1/2) (V/m1/2)(3)n0 = Bsphere ⋅ q(4)where B is the matrix whose elements are determinedfrom the size of the objects and the dielectric constantof the micro-particle.
The voltages of the manipulator and the plate are
given, and the charge densities at the nodal points canbe calculated by the written Equations [6].

0



1

2

3

4

5

Detachment

Consider the case where the spherical Polystyrene
particle adheres to the center of the probe tip. In Figure
4, the force is plotted as a function of the normalizedgap (the distance between the sphere and the plate).
(N/V2)

L m/R s=1
L m/R s=10
L m/R s=100

FCoulomb/(ε0V2)

dielectric constant*of sphere: ε =2.56

Rm
Rs

10-3

Lm/Rs=1
Lm/Rs=10
Lm/Rs=100

100
V : Applied voltage
on manipulator
Rm
Lm

Normalized force(N/V2)
FCoulomb/(ε0V2)
Normalized force

L m/R s=1 anddielectric constant*of sphere: ε =2.56

104

According to the results of analysis, it is possible topick-up a dielectric micro-particle from a substrate byelectrostatic force. By applying a DC voltage between
the probe and the substrate, an electrostatic force whichis larger than the adhesional force can be generated forpicking.

Lm

Coulomb forces withan infinite substrate

10-4

105

FIG. 3 Voltage required to pickup a particle from the substrate.

101

10-2

106

Normalized radius of manipulator Rm/ Rs

 Pick-up
Consider the case where the spherical Polystyrene
particle is in contact with the center of the probe tip. In
Figure 2, the force is plotted as a function of thenormalized radius of the manipulation probe.

10-1

107

103

B. Results of analysis

100∆γ sp= 1∆γ sp= 0.1∆γ sp= 0.01

108

Applied voltage

where D is the matrix whose elements are determinedfrom the size of the objects.
Using the boundary condition of dielectric surface,formula (4) can be gotten.

V : Applied voltage
on manipulator

(1)

0
2
4
Normalized radius of manipulator Rm/ Rs

Rs
Dsp
Coulomb forces
when Rm/Rs=1
with an infinite substrate

10-1 -3
10

FIG. 2 Effects of the radius of the manipulation probe Rm on the force.

On the other hand, the force required to pick-up theadhered particle from the substrate can be written as

10-2

10-1

100

101

102

103

Normalized distance between sphere-plate Dsp/Rs

FIG. 4 Effects of the gap Dsp on the force.

2
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According to the results of analysis, it is impossible
to detach a dielectric micro-particle which is adheringto the tip of the probe. Because the electrostatic force
generated by the applied voltage is always upward. So
a repulsive force for detaching can not be generated.
However, in an actual manipulation, a dielectric
micro-particle is probably not completely insulated.
The effect of this phenomenon is difficult to estimate.
In the next session, we show the experimental
verifications

used as the dielectric spherical micro-particles. A
stainless-steel plate with a 50 mm×10 mm area and0.1-mm thickness was used as the substrate plate. The
plate was polished with emery papers to have surface
roughness similar to that of a mirror. As for thetranslational stages, triaxial translational stages with a
0.05-mm resolution were manually used to adjust theposition of the objects. A piezoelectric actuator stage
with a 1-nm resolution (Jena, Tritor 3D, custom made)was used to control the gap between probe and thesubstrate plate. The substrate plate was attached to oneof the manual stages. The manipulation probe was
attached to the piezoelectric actuator stage on anothermanual stage. An optical video microscope (Hirox,
KH-2200) was used to observe the manipulation probe,
the spherical micro-particle, and the substrate plate.
The power supply (Nihon matsusada, HJPM-3R5-L2)
was used to apply a voltage between the probe and theplate. An oscilloscope (Tektronix™, TDS-2012) wasused to monitor the actual voltage between the probe
and the plate.

3 Experimental verifications
A. Experimental system
Figure 5 shows the experimental system used. The
experiment was performed in atmosphere. The
manipulation part consisted of a probe, a dielectric
spherical micro-particle, and a substrate plate. The
axial direction of the probe was set vertical to theplate.

B. Results of the experiments
 Manipulation of a Phenol micro-ball with a
54-µµm diameter
When a DC voltage is applied to the probe, theparticle which was arranged right under the probe(Figure 6) is able to be caught by the probe (Figure 7).
Afterwards, even if the probe is brought close to thesubstrate side, the particle still adheres to the tip of theprobe without detachment (Figure 8).

FIG. 5 Illustration of the experimental system used.

A stainless-steel needle with approximately a14.3-µm tip radius was used as the manipulation
probe. Polystyrene micro-balls with a 60-µm diameterand Phenol micro-balls with a 54-µm diameter were

FIG.. 6. Photo obtained before micro-particle pickup.

FIG.. 7. Photo obtained after micro-particle pickup.

FIG. 8. Photo obtained after trying todetach micro-particle.

FIG.. 9. Photo obtained before micro-particle pickup. FIG.. 10. Photo obtained after micro-particle pickup. FIG. 11. Photo obtained after micro-particle
detachment.

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Manipulation of a Polystyrene micro-ball witha 60-µµm diameter

When a DC voltage is applied to the probe, theparticle which was arranged right under the probe(Figure 9) is able to be caught by the probe (Figure 10).
Afterwards, when the probe is brought close to thesubstrate side, the particle is able to detach from theprobe and be placed on the substrate (Figure 11).

FIG. 13. A reciprocal motion of a Polystyrene micro-particle.

As the result of the experiments, Polystyrene
micro-particle can be picked up and detached byelectrostatic force. It is not in agreement with theanalysis result. The reason for the movement of thepolystyrene micro-particle can be explained as follows:
A particle should be polarized by the static electricfield. Because of the incomplete insulation of thedielectric micro-particle, the surface of the particle has
the same charges as those of the substrate. Then, thepolarized particle is attracted by the probe. Once theparticle reaches the probe, its polarization would be
kept, but the charges on the surface of the particle
would be the same as those of the probe. Then, theparticle should detach from the probe by the repulsion
force generated by the same charge of the probe andparticle (Figure 13). Consequently, the particle bounces
back and forth between the probe and the substrate.

A reciprocal motion phenomenon of a
Polystyrene micro-ballWhen a DC voltage is applied to the probe and the
distance between the probe and the substrate is kept at
a constant, the particle which was arranged right under
the probe shows a reciprocal motion between the probe
and the substrate.

C. The mechanism of manipulation ofdielectric micro-particle


Polystyrene micro-particle

Phenol micro-particle

4 Conclusions
The manipulation mechanisms for dielectric
particles are discussed with both theoretical andexperimental approaches. Electrostatic force on ideal
dielectric materials is analyzed theoretically withnumerical simulation. The geometry of the probe
effects on the dielectric force. The ideal dielectricmaterials can be picked up, however, can not be placed.
The dielectric interaction is investigated also
experimentally. Phenol micro-particle is verified tohave the features of the ideal dielectric material.
However, Polystyrene micro particle is proved to beable to be picked up and placed, because it has both thefeature of the dielectric and the conductive materials.

FIG. 12. Generated electrostatic force of a Phenol micro-particle.

As the result of the experiments, Phenol
micro-particle can be picked up and can not be
detached by electrostatic force. It is in agreement withthe analysis result. We thought the Phenol
micro-particle used in the research is similar tocomplete insulation.
When a static electric field is given between theprobe and the substrate, the field is concentrated on theprobe side which has a smaller surface area. The
polarization in the dielectric micro-particle generated
by the static electric field should bias to the probe side.
Therefore, an attraction force by the probe is able to begenerated. It is possible to pickup the particle by theattraction force and it is impossible to detach theparticle adhered to the tip of the probe because there is
no repulsion force will be generated (Figure 12).

References[1] K. L. Johnson, K. Kendall, and A. D. Roberts, Proc. R. Soc. London, Ser. A 324 (1971)[2] K. Takahashi, H. Kajihara, M. Urago, S. Saito, Y. Mochimaru, and T. Onzawa, J. Appl. Phys. Vol.
90, No.1 (2001)[3] S. Saito, H. Himeno and K. Takahashi, J. Appl. Phys. Vol. 93, No. 4, (2003)[4] S. Saito, H. Himeno and K. Takahashi, Applied Physics Letters. Vol. 83, No. 10, (2003)[5] K. Kurihara, Master thesis, (2005)[6]M. Han, Bachelor thesis, (2004)

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BENEFICIAL 2-WAY INTERNATIONAL COOPERATION BETWEENJAPAN AND DEVELOPING COUNTRIES IN ASIA:TECHNOLOGY TRANSFER OF WELDING TECHNOLOGY CASE STUDY
Student Number: 04M18280

Name: Braga Bruno Martins

Supervisor: Takahashi Kunio

援助国及び被援助国双方の利益となる国際技術協力のあり方－溶接技術に関する国際協力を例として－
ブラガ・ブルーノ・マルチンス
現在行われている日本による開発途上国に対する国際協力は，日本および対象国の要求と実状に合ったものであるべきである．基礎教育だけでなく専門学術教育を支援する事は基礎教育だけの支援より早く貧困を撲滅する事に繋がる．技術に裏打ちされた経済的な発展に繋がるからである．本研究では，溶接技術を例に取り，国際協力を通じた日本の従来技術移転のあり方を検討している．国内外の溶接技術に関する
組織と実際に連携し，実際に技術移転支援に協力しながら国際技術協力のあり方を提案している．

high-level education. Due to this lack of balance, it isnecessary to better evaluate the priority of aid programs,
which may occur in many ways. Without discharging theimportance of basic and fundamental aid programs suchas poverty eradication, the action of international
cooperation between developed and developing countries
has to be optimized according to each country’s interests,
considering also specific programs such as professional
education.
Regardless the fact that international cooperation
with developing countries means “help”, the actions fromdeveloped countries seem clear, attracted by tradefacilitations, implementation of industry due to low costof labor and raw material, and finally standardization [5].
The repercussion of fixing own standards internationallyis obvious and beneficial for both sides, in many aspects.
The technical cooperation of professional education
requires, however, matching the demand and supply,
which means the developing countries’ needs for
specific/applicable knowledge and developed countries’
potentials for technology transfer.
This research aims to clarify the present situation ininternational cooperation between Japan and developing
countries in Asia taking welding technology as case study,
and to understand the effectiveness of current aid
mechanisms.

1 Introduction“Knowledge is like light. Weightless and intangible,
it can easily travel the world, enlightening the lives ofpeople everywhere. Yet billions of people still live in thedarkness unnecessarily.” [1]The influence of the globalization in the world
affects all areas, especially those related to development
and technology. The transfer of technology to developing
countries as international cooperation has been also
influenced by the velocity of the worldwide changes.
Developed countries are practically competing with eachother for opportunities of cooperation with developing
countries [2]. Japanese Official Development Assistance(ODA) has, however, decreased for 5 consecutive years,
as shown in Figure 1. Some measures are being
considered for this issue, under validation process by theJapanese government [3].
millions US$
24 000
21 00018 000
15 000
12 0002 Japanese welding technology

9 000
6 000
3 000

Welding technology is the case study took for thisresearch because of its large applicability in almost every
areas of industry. Despite the difficulty to measure thestrength of a country in a world of technology
competition, the high quality of Japan is still recognizedworldwide [6], and has a strong participation in scientificcommunities. The figure 2 presents the number of papers
published at the International Institute of Welding (IIW),
organization which congregates almost all welding

1985
France1990
Germany

1995
Japan

2000
UK

USA

Figure 1: Trends in ODA for the last 20 years [4]However, the needs of developing countries vary.
While some live in poverty, others have access to47

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•

Total

societies in the world [7].
160

•

140
120

•
•

100
80

impression of welding technology in Japan andown country;
past and future priorities for welding technology inown country;
future needs in welding technology;
use of aid resources in welding technology;

60
40
20
0

England

2005

2004
2003

2002
2001

Germany

2000
1999

1998
1997

1996

1995
1994

1993
1992

1991
1990

1989

Japan

USA

Figure 2: Publications in IIW for the last 15 years
It is worth to mention that there is no research
investigation in the present bibliography which analyzes
the present situation in international cooperation between
Japan and developing countries in Asia in welding
technology.

3 Methodology
To verify the present situation in international
cooperation between Japan and developing countries in
Asia, taking welding technologies as example ofprofessional level education, this research has collected
data using questionnaire for welding related
professionals: during Asian Welding Federation (AWF)
meetings in Philippines (2004/10), Malaysia (2005/3),
and India (2005/10), since its establishment in 2004; andat the Japan International Cooperation Agency (JICA)
Welding Technology Training Course (2005/6). Although
the amount of data gathered was limited as shown intable 1, the respondents were participating ofinternational scale events for welding community.
Therefore, we consider it as very useful for thisresearch’s purpose.
Location
Philippines
Malaysia
JICA Course
India
Total:

Total of respondents
47 (29%)64 (40%)9 (6%)
41 (25%)161

Table 1：Respondents by location
Since the evaluation was not actually part of the
program at AWF meetings neither JICA Course, it wasadvised to build a compact questionnaire, focusing only
on the major interests of this research, to not become aninconvenience to the main activities. The figure 3
represents an example of the questionnaire used in thisresearch, divided in respondent’s characteristics and mainquestions, which aimed at the following:

Figure 3: Questionnaire used in this research

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3.1 Data Results
The analysis of the questionnaire revealed that theJapanese welding technology is also very recognizedamong developing countries. In a 1-5 scale from very
poor to very good, the average rating for Japan was 4.6,
against 3.7 for own country. The objective however is notnecessarily to compare these results, but understand theimpression that technicians from developing countries
have regarding Japan as well as their own country’s
welding technology. The results also confirm that the gapof technology level from developed and developing
countries is not completely understood. In the case of
JICA course, the participants were unanimous inchoosing their impression as 5 (very good) for Japan, andas 3 (not so good) for their own countries. The possible
reason is the fact that they had direct contact with theJapanese welding technology. Further, since the JICA
course participants are considered the top researchers
from their countries, their opinion should be emphasized.
Also, the average tendencies for the future use of
welding techniques are presented in figure 4, clarifying
the continuous decrease of Manual Metal Arc (MMA)
usage; a tenuous increase of interest in Submerged Arc
Welding (SAW) and Flux Cored Welding (FCW); and theGas Metal Arc Welding (GMAW) still remaining as themost used technique. There were some hand-writing
comments about interest on latest and top technologies,
such as laser welding (13%).
The last question of the questionnaire registeredcomments and suggestions, most of them regarding thenecessity of international cooperation for development of
welding and strengthening the Asia’s influenceworldwide.
MMA

The welding professionals also expect moreeducation and know-how related aid support, rather than
only financial support in international cooperation
programs, as presented in table 2, clarifying that there isdemand for education focused aid programs in welding
technology. In average, 71% of the respondents opted forknowledge supply. Some of them also chose bothanswers, representing around 15% of all respondents.
Preferred aid resources
Monetary
Knowledge
Funding
Supply15 (31%)34 (69%)22 (29%)55 (71%)4 (31%)
9 (69%)
11 (28%)29 (73%)

Location
Philippines
Malaysia
JICA Course
India
Total:

52 (29%)127 (71%)

Table 2：Preferred aid resources by location
The figure 6 express the fact that practically all
respondents agree that the international cooperation
programs for the development of welding technology canbe an important benefit for their countries. The
respondents who opted “no opinion” did not add any
comment, consequently the reason for choosing thisanswer is unknown.

Next 5 years
Last 5 years

GMAW

SAW

Figure 5: Usage of welding for the last 15 years

No
opinion
2%

50%

FCW

Figure 4: Shift of priorities by welding technique

Agree
98%

Comparing the data obtained from the questionnaire
to the values from developed countries [8], as presented infigure 5, we notice that the tendencies of use of welding
techniques are about the same. Since there is no suchinformation for developing countries, the questionnaire
aimed to capture the same concept from theprofessional’s opinions.

Figure 6: Can programs to help development of welding
technology be an important benefit for your country?

3.2 Findings
The major findings from this analysis are as
follows:

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TRIDE-2006-01, February 20, 2006 (ISSN 1880-8648)

Respondents are more interested in knowledge
supply, rather than financial support;
The high level of Japanese welding technology iswell recognized;
Despite tenuous differences between each group of
respondents, GMAW remains as priority;
International cooperation in welding technology
can be a good benefit for developing countries;
There is also interest in latest and top technologies
as well;Figure 7: Illustrative scheme of bilateral cooperation
procedure (present model)

4 Conclusion
This research clarified that the Japanese welding
technology can contribute to developing countries, also
being well recognized worldwide. The welding
professionals are willing to obtain know-how througheducation related aid programs, showing that there isdemand for educational related cooperation in welding
technology. Finally, a beneficial 2-way international
cooperation should be considered, focusing on the needsof developing countries and the needs of Japan as well,for promoting a sustainable cooperation. For Japan, thebenefits are establishing standards through the world andcreating better environment for Japanese industry
allocated overseas, among others, but not as direct andimmediate as the benefits for developing countries.

Figure 8: Illustrative scheme of multilateral cooperation
procedure (alternative model)

References[1] World Bank, “World Development Report:
Knowledge for Development” (Open Statement), p.4,
1998/99[2] Evans, P.C.; Oye, K.A., “International Competition:
This paper also presents some key factors to suggest Conflict and Cooperation in Government Export
a future project, which is an alternative for Japan to Financing”, 2004/4/29, p.113-158
transfer welding technologies, especially widely [3] 日本経済新聞，「外務省の来年度予算概算要求，
applicable techniques such as GMAW, which has been ODA11.9％増」，総合 p.3，2005 年 8 月 30 日
used in majority both in Japan and in developing [4] OECD-DAC, "Net ODA from DAC countries fromcountries in Asia. Instead of concentrating all tasks for 1950 to 2004", 2005/12/15 (Last Access: 2005/12/30)
Japanese government agencies (figure 7), the alternative <http://www.oecd.org/dataoecd/43/24/1894385.xls>
is to use AWF as intermediate, in a multilateral [5] Soesastro, H., “Sustaining East Asia's Economic
cooperation (figure 8). The major points of this proposal Dynamism: The role of Aid”, PRI-OECD Research
Project, 2004/5, p.4
are as follows:•
Key technology: Emphasize on more applicable [6] Eagar, T. W., “Technology Transfer and Cooperative
Research in Japan”, AWS Welding Journal, 1989/1,
technologies, such as GMAW;•
Method of Transfer: Focus on training and p.39~43
professional education, rather than financial [7] IIW, "IIW Technical Documents Database" (Last
Access: 2006/01/02) <http://www.iiw-iis.org/iiw/iiw
support only;•
Form of Cooperation: From bilateral to multilateral databases/technical/index.cgi>[8] Svensson, E.; Elvander, J., “Challenges for welding
cooperation (e.g.: intermediation of AWF);
consumables for the new millennium”, Svetsaren No.1–
1999/2, p.3-11
The expected outcome of this proposal is as follows:•
Increase & strengthen professional network;•
Increase visibility of welding technology field ininternational cooperation;•
Contributeinregional
cooperation&
standardization in Asia;•
Possible
simplificationonJapanside’sadministration;

5 Future prospect

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A STUDY ON PLASTIC DEFORMATION MECHANISM WITHOUT DISLOCATIONSIN METALS BY TRANSMISSION ELECTRON MICROSCOPY
Student Number :04M18162

Name: Hidetoshi Fujii

Supervisor:Satoshi Kojima

透過型電子顕微鏡を用いた金属の非転位塑性変形機構の研究
藤井英俊
金属の高速変形時に転位によらない変形機構が存在する可能性は、近年の研究を通じて極めて濃厚になっている。本研究では純金を用いて引っ張り破断実験を行い、亀裂進展部位に発生するボイドに特に注目し、その挙動から転位によらない新しい変形機構の存在可能性を検証するものである。

1. Introduction

2. Experimental Procedure

In the recent studies by Kiritani et al, many
experimental results which imply the existence of
deformation mechanism without dislocation werereported［1］.
In this deformation, many uniquefeatures can be seen which cannot be observed inusual deformation. For example, no dislocations areobserved and a large number of vacancy clusters like
SFT are observed at the fractured tip. Kiritani et al
proposed “Glide Element Model” as the new
deformation mechanism but the detail of thedeformation is still unknown.
Kojima revealed a new interesting fact in the tensile
fracture experiment in pure gold. Several numbers ofvoids were observed at the leading part of the fractured
region［2］. Such topics about voids in pure metal have
not yet been discussed before. Thus, this result has
possibility that suggest new deformation mechanism ofmetals.
In this study, we have paid an attention to thegeneration and behavior of voids during deformation intensile fracture experiment of pure gold through TEM(transmission electron microscope). At the same time,
we have observed behavior of other clustered defects(mainly dislocations) and their relationship with voids.
Finally, we will discuss the results of the observation,and propose a new deformation mechanism of metal.

2-1 Tensile specimen, holder for electron
microscopy utilizing Piezo devise

51

For this study, we prepared particular holder forelectron microscopy made by K.Hamada of
Hokkaido University to achieve more precise
experiment. Piezo devise has peculiar property that
length change by changing applied voltage.
This holder enabled us to perform fine tensile
fracture experiment at the range of nano meter inelectron microscope. The experiment was always
started from same voltage, because Piezo
devise has a property of hysterisis.
To operate this holder, electric power source,
control devise and PC were set. We connected eachother, and controlled the voltage of Piezo devise
using VBA (Visual Basic for Applications) .

2-2 Specimen
Pure gold (99.99%)was rolled to the thickness of 50
μm. They were annealed in Hiroshima Institute ofTechnology and cut to the pieces of 15mm×3mm.
At the middle of the specimen, a notch cut was
introduced in order to provide a starting point for
the tensile fracture. The specimen was set to thespecimen holder with Piezo devise for electron
microscopy.

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Observation 4 was made by rotating 90
degrees per second. Velocity is about 50 μm/s.
In each experiment, both bright and dark fieldobservation for TEM image were made before
and after deformation, and recorded the
behavior of defects during deformation bymovie.

3 Experimental Results
3-1 Deformation Process
Fig1. Specimen holder for microscope

specimen
Hand-operated
handlepiezo devise

Fig2. Specimen and specimen holder

2-3 In-situ tensile experiment
In order to investigate the tensile velocity
dependence to void reactions ,in-situ tensile
experiments were performed.
Observation 1 was made by decreasing voltage
for Piezo devise from 100v to 90v taking 100
seconds. In this observation, real velocity oftensile at specimen is about 1nm/s.Observation 2
was performed as well as observation 1. In thiscase, the tensile velocity is 100nm/s on an average.
Observation 3 and 4 are different from 1 and 2.We
used hand- operated handle attached specimen
holder instead of Piezo devise in theseobservations. If the handle is rotated by 10
degrees, then real displacement of specimen isabout 5μm.Observation 3 was made by rotating
this handle 5 degrees per second. Actual tensile
velocity is 3 μm/s.

52

Through the observation1 and 2, it could befound that two types of deformation exist justbefore fracture.
Case 1: Fracture tips glide each other along
glide line of dislocations, and reach to fracture.
In this case, the shape of saw-tooth portions isalmost well-shaped triangle. Their tops are
directed toward〈100〉direction.
Case 2: First, tangled dislocations move tobase portion, and all the dislocations
disappear at the elongated region. In thisregion, elastic strain reach to 10～20% [3]. The
saw-tooth portion shows a shape like trapezoid,
and the top directs toward 〈112〉direction.
The result of observation 2 is almost the sameas observation 1, but there was a different
point. In this case, almost all the observation
results of showed abnormal high strain
deformation process (case2 of observation1)
These results suggest the possibility that
non-dislocation deformation mechanism isappeared.

3-2 Generation of voids
In observation 3, several numbers of voids
were observed at the thick part of deformed
regions. The shape of voids was almost
sphere. In observation3 and observation 4,
since the tensile velocity was too fast to take amovie, the observation during deformation
was not made. However, because the top of all
saw-tooth portion which generated voids
directed toward〈112〉direction, there is apossibility that these deformation have beenproceeded under abnormal high strain.

Technical Report of International Development Engineering

TRIDE-2006-01, February 20, 2006 (ISSN 1880-8648)

〈100〉

200nm

〈010〉

(a)11.1 sec(b)64.32 sec(c)178.30sec(d)219.46sec

〈111〉
〈100〉
100nm

(e)18.56sec(f)179.04sec

Fig3. deformation process observed in observation1 ,case1 ｛(a)～(d) ｝,case2｛(e),(f)｝3-3 Distribution of voids in high speed
deformation
In observation4, a large number of voids areobserved in both the fracture region andsaw-tooth portion.
In this deformation, lots of oval-shaped voids as
if extended were observed. An interesting fact
was also found. Voids remained in saw-tooth
portion were arranged in a line. From themicrographs, we cannot understand the 3
dimensional direction, however, it is consideredthat these lines are arranged toward 〈 110 〉
direction. This direction is not the same as tensile
direction, thus this result may show how vacancy
clusters act during deformation.

4 Discussions
4-1 Deformation Process
From the observed results of the deformation process,it is considered that a deformation mechanism without
dislocation appears after all the dislocations
disappeared from the elongate part.
In thisdeformation, very high elastic strain occurred just53

before the fracture. Calculating the stress in thisarea from Young’s Module, the value reaches toabout 15Gpa. In usual deformation in metals, suchphenomena cannot happen.

4-2 Generation of Voids
In these experiments, voids were observed inobservation 3 and 4. These results mean that voids
start to appear at the velocity of more than 0.1～1μ/s. From this value, strain rate can be calculated toabout 1 s-1.
It is considered that this velocity
dependence of void nucleation is caused by thehigh internal stress in this area Thisphenomenon can be explained as follows. As
the strain rate become high, the production
rate of vacancy clusters also increase. Since
this concentration in material become high,the possibility of vacancy clusters reaching
into nano-crack increase.
This high stress also prevents the nuclei of
vacancy clusters from collapsing, unless vacancy
clusters become dislocation loops or SFT (stacking
fault tetrahedera).

Technical Report of International Development Engineering

TRIDE-2006-01, February 20, 2006 (ISSN 1880-8648)

50nm

〈100〉

100nm

(a)

〈111〉

(b)

Fig4. Voids remained in fracture region (a) observation3, (4) observation4, line- shaped distribution

tensile4-3 One dimensional motion of vacancies
In observation4, line shapes of voids were observed.
These lines directed toward 〈110〉.This observation
result suggests 1-dimensional motion of vacancy
clusters.

(b)

(a)

4-4 Proposal of new deformation mechanism－
Nano crack deformation
From these observation results and discussion, we
propose new deformation mechanism (Nano crack
deformation mechanism) in metal. This mechanism is
explained by the motion of vacancy clusters inspecimen.
Fig.5 shows the process of nano-crack
deformation. First, High stress open the lattice
space, nano-crack generate ｛ (a) ｝.Then, thenano-crack breaks into two, and move to thedirection〈110〉each other｛(b)｝. When a pair ofseparated nano-crack moves apart each other,
new atomic plain is created in the x direction｛(c)｝.
This process is necessary in order elongate amaterial.
Finally, these broken nano-cracks reach to thesurface, metal deformation progress ｛ (d) ｝ .This
hypothesis can explain all the observation results.
Nucleation of voids is explained as the result ofgathering vacancies into nano-cracks in the specimen.
And the arrangement of voids toward〈110〉direction
can be also explained by 1 dimensional nano-crack
action.

54

(c)

(d)
〈010 〉

x〈100〉

yFig.5 Nano-crack deformation mechanism

References[1] M.Kiritani “Dislocation free plastic deformation
under high stress” Maters. Science &Engineering
A350 (2003) 1-7.
[2] S.Kojima, H.Fujii “Formation of Voids in Thin
Foil Pure Gold during Plastic Deformation”
Maters. Trans. 47 (2006) to be published.
[3]Y.Matsukawa,
Yasunaga,M.Komatsu andM.Kiritani“Dynamic
observationofdislocation-free plastic deformation in gold thinfoils.” Materials Science &Engineering A350
(2003) 8-16.

Technical Report of International Development Engineering

TRIDE-2006-01, February 20, 2006 (ISSN 1880-8648)

STUDY OF MAHALANOBIS METRIC
Student Number: 04M18044

Name: Naoya Inoue

Supervisor: Yukihiko Yamashita

Mahalanobis 計量に関する研究
井之上直矢

パターン認識などではデータ間の距離を Mahalanobis 距離など確率的距離で用いることで単なるEuclid 距離を使うよりも認識精度や解析精度が向上することが知られている．Mahalanobis 距離を更に拡張した Mahalanobis 計量が提案されているが，それを与える Mahalanobis 計量方程式を充分な精度で計算することが出来なかった．そこで本研究では，Mahalanobis 計量を高速に高い精度で求める方法を開発した．

2 Mahalanobis distance

1 Introduction
The pattern recognition and the statistical anal-

Mahalanobis distance measures a probabilistic

ysis are actively researched. In many cases, there

distance between two vectors. Therefore, even if

exists the correlation in pattern data. There are

their Euclidean distance is small, the Mahalanobis

a lot of researches who measure them by a proba-

distance may be large.
Mahalanobis distance is given by changing innerbilistic distance.

product of Rn from hx, yi to hR−1 x, yi. Maha-

Mahalanobis distance is a well-known proba-lanobis distance between x, y ∈ Rn is shown asbilistic distance.[7](Fig.1)

l2 = hx − y, R−1 (x − y)i(1)

The normal distribution of which average is 0
and covariance matrix is R is given by1
exp(−hR−1 x, xi/2).
p(x) = p(2π)n det R
Fig.1: Probability density contour map

A normal distribution is transformed to thestandard normal distribution with the coordinate

However, Mahalanobis distance cannot corre-transform x0 = R−1/2 x. And, Mahalonobis dis-spond to a non-normal probability distribution.

tance is the pullback of hx0 , y 0 i by the transform.

Actual probability distribution is not normal.

In general, Mahalanobis distance provide more

Here we research on Mahalanobis metric that isaccurate result than Euclidean distance. Maha-an extension of Mahalanobis distance. Howeverlanobis distance depends only on covariance ma-

Mahalanobis metric equation cannot solved inenough efficiency.

(2)

trix. Therefore, for example, the part where distri-

So, we designed a method

bution bends are not accurately measured. How-to obtain Mahalanobis metric accurately andever, there are a lot of data according to a non-efficiently in this research.

normal distribution. So, it is necessary to extend
Mahalanobis distance.

55Technical Report of International Development Engineering

TRIDE-2006-01, February 20, 2006 (ISSN 1880-8648)

Thus, Mahalanobis metric equation does not depend on the metric of an original space. This is

3 Mahalanobis Metricextension of independence that Mahalanobis distance does not depend on the original inner prod-M

uct of the space[8].

qWhen we rewrite the expression (5), it becomes

T

g̃µν

gµν

∇µ ∇ν log p −

M0
q0

∂ α
Γ + Γηνµ Γααη = f gµν .
∂xν αµ(6)

Because f is an unknown scalar, the number of
unknowns is more than the number of equations,0gµν

and the equation cannot be solved directly.
The necessary and sufficient condition thatFig.2: Transformation of probability density function

a normalized probability density function q isisotropic independent is given by expression(7)with a certain scalar f .

We define Mahalanobis metric on manifold. M
00

and M are two manifolds, and T : M → M is a∇µ ∇ν log q = f gµν

diffeomorphism. We assume that probability den-(7)

sity function p is transformed to a normal distri-

By this theorem, when M 0 is Rn , the scalar f wasbution in M 0 by T .(Fig.2) Then, we haveto be the constant of less than 0. Therefor, we can0∇0µ ∇0ν log q 0 = f gµν
.

assume f = −1. And, the Mahalanobis metric is(3)

given as a solution of this equation.

∇0µ is the covariant differentiation decided by met0
ric tensor gµν
. g̃µν is define by the pull back of0
metric in M by T . (x, g̃µν ) and (x0 , gµν) become

4 Numerical analysis
Mahalanobis metric equation have to solved by

the relations of coordinate transformation. There-

the numerical method since it is complex. Here wefore, we have˜ µ∇˜ ν log q(x)√ = f g̃µν .
∇g̃

explain two numerical analysis methods.
(4)

The first one is the method of steepest Descent.
The method of Steepest Descent is the simplestg̃µν is rewritten with gµν and we define the follow-

gradient methods, and searches the direction thating formulary.
µ¶1∇µ ∇ν log p − log g = f gµν2a ball tumbles down when we search for the lowest
point. The direction is given by −gradf (x). The(5)advantages of the method are that computational

It is called Mahalanobis metric equation of metriccomplexity of each step is low and convergence istensor gµν and probability density function p withguaranteed. However, it takes very long time toa certain scalar f . Where ∇ is a covariant dif-convergence and it may converge not global but aferentiation and g is determinant of metric tensor

local minimum point.

gµν .

The second one is Newton’s method. First Ini-

The terms which depend on the original metrictial point x is provided, and draw the tangential

do not appear in the Mahalanobis metric equation.

line of y = f (x) at f (x, f (x1 )). Then, x2 is the56Technical Report of International Development Engineering

TRIDE-2006-01, February 20, 2006 (ISSN 1880-8648)

Fµν have to be vanished. Γkij is connection coefficients and a function of gµν . Then Fµν is afunction of only gµν .
Approximation is used for solving Newton’s
method. Our experiment, we use 51times51 mesh.
Fig.4(a) and (b) illustrate calculated g11 and g22
with ideal g11 andg22 , when x1 and x2 are changed
while x2 = 0 and x1 = 0, respectively.

Fig.3: Newton’s method

0.03

0.025

repeat the procedure. The update rule is described

0.02
g22

intersection of this tangential line and x axis. We
as
x←x−

f (x)
.
f 0 (x)

0.015

0.01

(8)

0.005
calculated g11
ideal g11

The advantage of Newton’s method is very fast0
-1

convergence, and drawbacks are there is no guar-

-0.5

0
x1

0.5

1

(a) Metric tensor g11 (x2 = 0)antee for convergence and it may converge not a
global but a local minimum point.

0.03

0.025

0.02
g22

5 Experiment

0.015

0.01

We solve Mahalanobis metric equation by

0.005

the computer, and calculate the metric tensor.

calculated g22
ideal g22
0
-1

The Mahalanobis metric equation in the 2D is

-0.5

0
x2

0.5

1

(b) Metric tensor g22 (x1 = 0)

described as

Fig.4: result(2/2)∂µ ∂ν log p − Γ1µν ∂1 log p − Γ2µν ∂2 log p+Γ1µν (Γ111 + Γ221 ) + Γ2µν (Γ112 + Γ222 )−∂ν (Γ11µ + Γ22ν ) + gµν = 0

Fig.5(a) and(b) illustrate the convergence of(9)squared error of Fµν and gµν , respectively.

Let Fµν denotes the left-hand-side of equation(9).
F11 = ∂1 ∂1 log p − Γ111 ∂1 log p − Γ211 ∂2 log p

6 Summary+Γ111 (Γ111 + Γ221 ) + Γ211 (Γ112 + Γ222 )∂− 1 (Γ111 + Γ221 ) + g11(10)∂x
F12 = ∂1 ∂2 log p − Γ112 ∂1 log p − Γ212 ∂2 log p

Compared to the previous result by Steepest descent method.(Fig.6). We cannot obtain enoughaccurate solution by Newton’s method. However+Γ112 (Γ111 + Γ221 ) + Γ212 (Γ112 + Γ222 )∂− 2 (Γ111 + Γ222 ) + g12
(11)
∂x
1
2
F22 = ∂2 ∂2 log p − Γ22 ∂1 log p − Γ22 ∂2 log p

for Steepest descent method, 100000 iterations andthe calculation of several days were necessary forconvergence. On the other hand, for Newton’s+Γ122 (Γ111 + Γ221 ) + Γ222 (Γ112 + Γ222 )−∂(Γ1 + Γ222 ) + g22∂x2 12

method, only 100 iterations and several hours werenecessary.

(12)

57

Technical Report of International Development Engineering

TRIDE-2006-01, February 20, 2006 (ISSN 1880-8648)[3] Tien, C.L. and Lienhard, J.H., Statistical Thermodynamics, Revised Printing, Hemisphere Publishing Corporation, Washington, 1985.
[4] Amari, S., “Defferncial geometrical method in
statistics,” Springer-Verg, Berlin Heidelberg, 1985.
[5] Fry. T.C., Probability and its engineering uses, second edition, D. Van Nostrand Company, Princeton, New Jersey, 1965.
[6] Spivak, M., A comprehensive introduction to differential geometry, second edition, vol.1–5, Publish
or Perish, Inc., Houston, Texas, 1979.
[7] Mahalanobis, P.C., ”Normalization of statisticalvariates and the use of rectangular co-ordinatesin the theory of sampling distributions,” Sankhay,
vol. 3, no. 1, pp.1–40, Jan. 1937.
[8] Yukihiko Yamashita, Hidemitu Ogawa, “Phase andoptimal image restoration filter of image space,”
Electronic information communication society thesis magazine(D-II), vol. 75-D-II, no. 2, pp.306–313,
Feb. 1992.
[9] Yukihiko Yamashita，“Consideration concerningnormal distribution on manifold,” The Technical
Report of the Institute of Electronics Information and Communication Engineers of Japan ，no.
PRMU 2000-174, Jan. 2001.
[10] Yukihiko Yamashita，“Consideration concerningnormal distribution on manifold to which characterization of Maxwell distribution is enhanced,”
The 2002 Japanese Joint Statistical Meeting Lecture papers, pp.136-137, Sept. 2002.
[11] Yukihiko Yamashita，“Consideration concerningnormal distribution on manifold to which characterization of Maxwell distribution is enhanced,”
The 2002 Japanese Joint Statistical Meeting Lecture papers, pp.136-137, Sept. 2002.
[12] Mariko Numakami，“Mahalanobis Metric on vector space,” The 2004 Tokyo Institute of Technology Department of Communications and Integrated Systems master’s thesis, pp.1-47, Mar. 2005.

0.018
Squared error of g
0.016

Squared error

0.014
0.012
0.01
0.008
0.006
0.004
0.002
0
0

20

40
60
Number of iterations

80

100

(a) convergence of squares of error of gµν1
Squared error of F
0.9
0.8

Squared error

0.7
0.6
0.5
0.4
0.3
0.2
0.1
0
0

20

40
60
Number of iterations

80

100

(b) convergence of squares of error of Fµν
Fig.5: Trial frequency and convergence of error

0.2
Squared error of g
Squared error of F

0.18
0.16

Squared error

0.14
0.12
0.1
0.08
0.06
0.04
0.02
0
0

20000

40000
60000
Iternations

80000

100000Fig.6: Trial frequency and convergenceof error by Steepest descent method

Convergence is not enough since it converges tolocal solution. It is a problem to be solved. We
will add the condition of the curvature, and search
for the parameter by which Newton’s method converges to the gloval solution.

References[1] Maistrov, L.E., Probability theory, a historicalsketch (Translated and Edited by Kotz, S.), Academic Press, New York and London, 1974.
[2] Feller, W., An introduction to probability theory
and its application, third edition, vol.1, John Wiley & Sons, New York, 1968.

58

Technical Report of International Development Engineering

TRIDE-2006-01, February 20, 2006 (ISSN 1880-8648)

Study of Improvement of Kernel Sample Space Method
Student Number: 04M18251

Name: Chenghan Piao

Supervisor: Yukihiko Yamashita

カーネル標本空間射影法の高精度化に関する研究
朴 成漢
パターン認識におけるカーネル法とは，得られたサンプルデータの情報をそのまま使うのではな
く，特徴空間と呼ばれる非常に高次元の空間へ非線形に写像してから識別を行う手法である. 本論文の目的は KSP（ カーネル標本空間射影法）を改良し，その認識精度を向上させることである. 一般のカーネル法では，カーネル関数は同じ非線型写像の内積で与えられていることを前提としている。本
研究ではカーネル法を拡張し ，内積の右辺と左辺に代入する非線型写像を異なるものとした理論をKSP に適用する. また訓練データに対して有効なカーネルパラメータを与える方法を開発するとともに，計算機実験によりその有効性を確かめる.

1

If eq.(3) is chosen as a kernel function, the map Φ is
an identity operator. If the polynomial function eq.(4)and the Gaussian kernel function eq.(5) are used, an Ndimensional input vector is mapped into a (N+d Cd −1)-dimensional and infinite dimensional space, respectively.
By using a mapping Φ, linear or quadratic discriminant in a feature space is equivalent to more complex
discriminant in the input space.

Introduction

Pattern recognition is a process to make an input pattern correspond to one of two or more concepts. recognition process consists of observation, preprocessing,feature extraction, classification. Our research is foucused on classification.The kernel-based learning machines, e.g. Support Vector Machines (SVMs)[9], Kernel Principal Component Analysis (KPCA)[8] and Kernel Fisher Discriminant (KFD) [4], have been proposed,
and achieved very low error rate. However, the kernel
function was not able to be used freely for the limitation 3 Kernel Sample Space Projectionthat the kernel function must be symmetry. To solve thisClassifier
problem, we propose the variable kernel sample space
projection method, and show its effectiveness by exper- We consider training samples f i , f i , . . . , and, f i of classLi
1 2
iments.
i, where Li is the number of samples in the class. We
define an operator as

2

Kernel Based MethodSi= [Φ( f1i ) Φ( f2i ) . . . Φ( fLi i )].

(6)

In kernel-based methods, an N-dimensional input vec- We call the space spanned by samples in the feature
tor f ∈ RN is mapped to a high dimensional space F by space “kernel sample space.” R(S ) is a kernel sample
ia nonlinear map Φ.
space, where R(Si ) is the range of Si .
In kernel-based methods, an input vector is mappedΦ : RN → F , f 7→ Φ( f )(1)
to a very high or infinite dimensional space. Its dimenWe call this high dimensional space F ’feature space.’ sion is almost much larger than the number of samples
The inner product in a feature space is calculated by a Li . Therefore a kernel sample space is non-dense spaceand expresses the feature of a class.
positive definite kernel function k as
In KSP, the similarity between an unknown input
vectorand a class i is evaluated by the norm of its prohΦ(x), Φ(y)i = k(x, y),(2)jection onto kernel sample space of the class. An unwhere h·i denotes inner product. The function k is a known input vector is classified to the class of which
norm is maximum(fig1)[10].
“Mercer kernel function.”
Now we describe it mathematically. Let
Mercer kernel functions which are widely used are
as follows
Ki = Si∗ Si(7)
k(x, y) = hx, yi : Identical(3)k( f1i , f1i ) · · · k( f1i , fLi i )


..
..
..
k(x, y) = (hx, yi + 1)d : Polynomial (4)= 
 , (8).
.
.
2kx − ykiiiik( fLi , f1 ) · · · k( fLi , fLi )) : Gaussian(5)
k(x, y) = exp(−
2σ 259

Technical Report of International Development Engineering

Φ( f x )TRIDE-2006-01, February 20, 2006 (ISSN 1880-8648)

4

FRegularization

Generally, a set of learning samples will include outliers or noisy samples. Thus, the generalization capability of classifiers may not be high, even if they canclassify finite learning samples correctly. This problemR(S )Φ( f2 )
is the over-fitting or over-learning problem, and it can
PR(S ) Φ( f x )be avoided by using regularization or model selection.
Φ( f1 )For example, [1] and [6], introduced a soft margin for
SVM and AdaBoost technique. In KSP, the learned patterns are always classified correctly as long as the Grammatrix is non-singular. Thus, the over-fitting problem
may occur when it is used.
The over-fitting problem occurs when the classifier
Figure 1: kernel sample space projection method
has a too complex decision boundary. If the classifier
has a discriminant function, the complexity of its decision boundaries is measured using the variation of thewhere Si∗ denotes an adjoint operator of Si . Ki isfunction with respect to a very small variation in the incalled “kernel gram matrix.”
put vector. Let ∆ be the former variation, δ fx be a small
Let A† be a Moore-Penrose generalized inverse opvariation of fx and d : RN → R be a discriminant funcerator of an operator A satisfies
tion. Then ∆ is expressed asAA† A = A(d( fx + δ fx ) − d( fx ))/d( fx )
∆ =
.
(14)
A† AA† = A†kδ fx k/k fx k
† ∗†(AA ) = AA
For KSP, ∆KSP is expressed as(A† A)∗ = A† A.
kPR(Si ) Φ( fx + δ fx ) − PR(Si ) Φ( fx )k
If A is a nonsingular operator, A† = A−1 .
∆KSP ≤·(15)kδ fx kA projection operator to R(A) is given as
k fx kPR(A) = AA†
(9)
.
(16)
kP
R(Si ) Φ( f x )k∗ † ∗= A(A A) A .
(10)
To suppress ∆KSP directly is difficult because Φ is nonlinear. Instead of ∆KSP , we introduce ∆0KSP , which is
Let fx be an unknown input vector, and h( fx ) bea variation of the feature with respect to a very small
variation δ Φ( fx ) of Φ( fx ). Then we haveh( fx ) = Si∗ Φ( fx )= (k( f1i , x) k( f2i , x) . . . k( fLi i , x)).

∆0KSP

Then, the projection operator PR(Si ) and the norm of the
projection of Φ( fx ) onto R(Si ) are given as=kPR(Si ) δ Φ( fx )kkΦ( fx )k·. (17)kδ Φ( fx )kkPR(Si ) Φ( fx )kSuppression of ∆ has been discussed in reference to ill(11) posed problems and regularization ([2]). Most ill-posedd( fx +δ fx )−d( fx ).
kPR(Si ) Φ( fx )k2 = hh( fx ), Ki† h( fx )i.
(12) problems are caused by the first part of ∆,kδ f x k
If d( f ) = kA f k, the maximum value of the first partof ∆ is given by its operator norm which is defined as
An unknown input vector fx is classified to the classkAk = supk f k=1 kA f k.
of which projection norm is maximum.
Tikhonov’s regularization avoids ill-posed problemskPR(Si ) Φ( fx )k2 > kPR(S j ) Φ( fx )k2 ∀ j 6= i([7]). It suppresses
p the Frobenius norm, which is de⇒ fx ∈ Ωi(13) fined as kAk2 = tr[A∗ A]. Since kAk ≤ kAk2 , we can
avoid ill-posed problems by suppressing the Frobenius
In KSP, an orthogonal projection can extract the fea- norm.
tures of each category. Thus, the projection norm of
We define the regularized KSP as follows. [Regularan unknown input vector Φ( fx ) onto R(Si ) stands for ized KSP] Regularized KSP is defined by the solution of
the similarity between fx and class i. However, KSP following optimization problem.
may extract features that belong to more than one class.
Such features cannot be used for classification, since
1 Li
2
min
:
J[X
]
=
i
∑ kΦ( fsi ) − Xi Φ( fsi )k(18)they may be as harmful as noise. They can be supLi s=1
pressed using an oblique projection which in used Sup(19)+µ kXi k22 ,presed KSP(SKSP), they can be suppresed, and we ex⊥pect higher performance.
subject to :N (X) ⊃ R(Si ) ,(20)
PR(Si )

= Si Ki† Si∗

60

Technical Report of International Development Engineering

TRIDE-2006-01, February 20, 2006 (ISSN 1880-8648)

where µ > 0 is a regularization parameter. A solutionof Regularized KSP is

5 Variable Kernel Method

In a kernel function has to be symmetric.Here, we apply(21) the asymmetric kernel theorem to KSP and SKSP, andwhere I denotes the identity matrix. If KUi is nonsin- propose the variable kernel sample space method(VKSP)
0
and thr variable suppresed kernel method(VSKSP).
gular, PR(Sis a projection operator onto R(Si ).
i)
In the previous kernel method, the kernel function is
If KUi is nonsingular,
defined
by
0
0
PR(S
P
= PR(S,(22)
k(x, y) = hΦ(x), Φ(y)i.
(30)
i ) R(Ui )i)00
PR(Ui ) PR(Si ) = PR(Si ) ,(23)
In the variable kernel method, it is defined by
P̃R(Si ) = Si (KSi + µ Li I)−1 Si∗ ,where PR(Ui ) is the orthogonal projection operator ontok(x, y) = hΦ1 (x), Φ2 (y)i
(31)
R(Ui ).
0
If KUi is nonsingular, PR(Si ) v = 0 for all v ∈ R(Ti ).
0
PR(SΦ( fx ) can be considered as follows. First, Φ( fx )k1 (x, y) = hΦ1 (x), Φ1 (y)i(32)i)
is orthogonally projected onto R(Ui ), after it is prothat is, the kernel function it is given as a product injected onto R(Si ) along R(Ti ). The similarity between
the result of two the difference mappings to the feature0
fx and Ωi against Ψi is given as kPR(Si ) Φ( fx )k. If Ψi =space. The Gauss kernel is used as a kernel function
0
φ , PR(S= PR(Si ) . Thus, SKSP is an extension of KSP. in this thesis. Because test sample is an unknown, thei)In actual problems, KSP can extract necessary fea- kernel parameter uses a constant parameter about thetures by itself. Thus we do not have to use all sam- test sample.
ples of other classes, only the samples that are similar
The variable kernel function is given asµ¶K³´to Ωi have to be included in Ψi . Since the similarity of2
σ0√k(x,y)=
exp − 2(σkx−yk
an input vector is evaluated using the projection norm
2 (x)+σ 2 )22
σ (x)+σ11
onto R(Si ), it is sufficient that samples whose projecandtion norms are large are included in Ψi .
¶Kµ³´
kx−yk2σWe also introduce a Tikhonov’s regularization term0exp−
k1 (x, y) = √ 2222(σ (x)+σ (y))σ (x)+σ 2 (y)to SKSP as well as KSP. Regularized SKSP is definedparameterofthe
Variablekernelsamplespace proas
jection(VKSP) is changed according to the density of
input pattern. parameters decided by For each training
min :samples the parameter os set to the minimum Euclidean
1 Li
distance to (1)all tranning sample of the other categoryii 2
J[Xi ] =∑ kΦ( fs ) − Xi Φ( fs )k (24) or (2)all the other training samples or (3)all the otherLi s=1
samples in the own category. Because the kernel funcα Mi
i 22+ ∑ kXi Φ(gt )k + µ kXi k2(25) tion is given by a product in these two vectors, it beMi t=1
comes variable.
⊥
Let fx be an unknown input vector, and h1 ( fx ) be
subjectto :N (Xi ) ⊃ R(Ui ) ,(26)
where µ > 0 is the regularization parameter.
Letµ¶Li ILi 0Li ,MiD̃i =.
0Mi ,Li Mαi IMi
A solution of Regularized SKSP is0
P̃R(S= Ui Di (KUi + µ D̃i )−1Ui∗ .
i)

h1 ( fx ) = Si∗ Φ1 ( fx )= (k1 ( f1i , x) k1 ( f2i , x) . . . k1 ( fLi i , x)).
(27) Then, the projection operator PR(S ) and the norm of theiprojection of Φ( fx ) onto R(Si ) are given as
PR(Si )(28)

kPR(Si ) Φ( fx )k

2

[11]
Let
K̃Ui = KUi + µ D̃i ,hi ( fx ) = Ui∗ Φ( fx )= (k( fx , f1i ), . . . , k( fx , fLi i ),=hh1 ( fx ), Ki† h1 ( fx )i.

(33)
(34)

Regularized KSP is defined by the solution of following optimization problem.
min :k( fx , gi1 ), . . . , k( fx , giMi ))> ,then the similarity between an unknown input vector fx
and Ωi against Ψi is given as
0kP̃R(SΦ( fx )k2i)

= Si Ki† Si∗

subject to :J[Xi ] =1 Li2∑ kΦ2 ( fsi ) − Xi Φ1 ( fsi )k(35)Li s=1+µ kXi k22 ,N (X) ⊃ R(Si )⊥ ,= hhi ( fx ), K̃U−1
Di KUi Di K̃U−1
hi ( f(29)
x )i.
i
i
where µ > 0 is a regularization parameter.

61

(36)
(37)

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6

TRIDE-2006-01, February 20, 2006 (ISSN 1880-8648)

Experiment

how to decide the kernel parameter has to be investigated.

We used several practical data sets that were used in [6],[3] and [5]1 . It consists of 13 binary classification problems and each dataset consists of 100 or 20 realizations.
We also conduct experiments of two-class classification
problems. The mean test error rates and their standard
deviations are shown in Table 1 and 2. All values aredescribed in percentage and bold font means the better
than KSP or SKSP by T-test result in those methods.

References[1] C. Cortes and V. Vapnik, “Support-Vector Networks,” Machine Learning, vol.20, no.3, pp.273–
297, 1995.
[2] C.W. Groetsch, Inverse problems in the mathematical sciences, Vieweg, 1993.

Table 1: Results of two-class classification
Name
BananaB.Cancer
F.SolarGermanHeart
Ringnorm
SpliceThyroid
Titanic
Twonorm

VKSP
10.4 ± 0.5
28.3 ± 4.4
38.5 ± 4.7
29.8 ± 2.0
15.4 ± 3.4
19.9 ± 1.8
12.1 ± 0.7
4.2 ± 2.3
28.3 ± 9.4
2.4 ± 0.1

KSP
10.4 ± 0.5
29.7 ± 4.5
39.1 ± 2.4
31.3 ± 2.5
15.4 ± 3.3
19.9 ± 1.8
12.6 ± 0.7
4.2 ± 2.3
28.3 ± 9.4
2.3 ± 0.1

SVM
11.5 ± 0.7
26.0 ± 4.7
32.4 ± 1.8
23.6 ± 2.1
16.0 ± 3.3
1.7 ± 0.1
10.9 ± 0.7
4.8 ± 2.2
22.4 ± 1.0
3.0 ± 0.2

[3] S. Mika, G. Rätsch, J. Weston, B. Schölkopf, and
K.R. Müller, “Fisher discriminant analysis withkernels,” Neural Networks for Signal Processing
IX, ed. Y.H. Hu, J. Larsen, E. Wilson, and S. Douglas, pp.41–48, IEEE, 1999.

KFD
10.8 ± 0.5
24.8 ± 4.6
33.2 ± 1.7
23.7 ± 2.2
16.1 ± 3.4
1.5 ± 0.1
10.5 ± 0.6
4.2 ± 2.1
23.3 ± 2.1
2.6 ± 0.2

[4] K.R. Müller, S. Mika, G. Rätsch, K. Tsuda, and
B. Schölkopf, “An introduction to kernel-basedlearning algorithms,” IEEE Transactions on Neural Networks, vol.12, no.2, pp.181–201, 2001.
[5] G. Rätsch, Robust Boosting via Convex Optimization, Ph.D. thesis, University of Potsdam,
Neues Palais 10, 14469 Potsdam, Germany, October 2001.

Table 2: Results of two-class classification
Name
BananaB.Cancer
F.SolarGermanHeart
Ringnorm
SpliceThyroid
Titanic
Twonorm

7

VSKSP
10.4 ± 0.5
25.8 ± 4.3
36.7 ± 5.3
23.5 ± 1.6
15.6 ± 3.2
16.4 ± 0.9
11.1 ± 0.6
4.2 ± 2.3
28.9 ± 12.9
2.4 ± 0.1

SKSP
10.4 ± 0.5
26.0 ± 4.5
37.2 ± 4.5
23.4 ± 1.6
15.8 ± 3.1
18 ± 2.3
11.2 ± 0.7
4.6 ± 2.2
29.4 ± 10.3
2.4 ± 0.1

SVM
11.5 ± 0.7
26.0 ± 4.7
32.4 ± 1.8
23.6 ± 2.1
16.0 ± 3.3
1.7 ± 0.1
10.9 ± 0.7
4.8 ± 2.2
22.4 ± 1.0
3.0 ± 0.2

KFD
10.8 ± 0.5
24.8 ± 4.6
33.2 ± 1.7
23.7 ± 2.2
16.1 ± 3.4
1.5 ± 0.1
10.5 ± 0.6
4.2 ± 2.1
23.3 ± 2.1
2.6 ± 0.2

[6] G. Rätsch, T. Onoda, and K.R. Müller, “Soft margins for AdaBoost,” Machine Learning, vol.42,
no.3, pp.287–320, March 2001. also NeuroCOLTTechnical Report NC-TR-1998-021.
[7] A.N. Tikhonov and V.Y. Arsenin, Solution of Illposed problems, V. H. Winston and Sons, 1977.
[8] K. Tsuda, “Subspace classifier in the Hilbert
space,” Pattern Recognition Letters, vol.20, no.5,
pp.513–519, 1999.
[9] V.N. Vapnik, Statistical Learning Theory, Wiley,
New-York, 1998.

Discussion[10] 鷲沢嘉一 and 山下幸彦, “カーネル標本空間射影
The VKSP outperforms the KSP in four kinds of data
法によるパターン認識,” 第 6 回情報論的学習理
sets. Besides, almost the same recognition rate as KSP
論ワークショップ IBIS2003 予稿集, pp.149–154,
was obtained. The VSKSP exceeded the recognition
Nov. 2003.
rate of SKSP in six kinds of data sets. This is because
the separating boundary is more correctly expressed by [11] 鷲沢嘉一 and 山下幸彦, “抑制型カーネル標本空
variable kernel functions than by fixed kernel functions.
間射影法によるパターン認識,” 電子情報通信学
会技術研究報告 PRMU2003-270 予稿集, pp.85–
90, March. 2004.

8

Conclusions

We proposed variable kernel sample space projection
method (VKSP and VSKSP), the feature and effectiveness were shown by the recognition experiment. For the
future work they have to be applyed various problems,
calculation time has to be reduced and needed about
1 The
data
sets
were
downloadedfrom‘http://ida.first.fraunhofer.de/projects/bench/benchmarks.htm’.

62

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Support vector machine with asymmetric kernels
Student Number: 04M18274

Name: Shen Liu

Supervisor: Yukihiko Yamashita

非対称カーネルサポートベクターマシン
柳森
パターン認識におけるカーネル法とは，得られたサンプルデータの情報をそのまま使うのではなく，特徴空間と呼ばれる非常に高次元の空間へ非線形に写像してから識別を行う手法である. 本研究の目的は SVM（サポートベクターマシン ）を改良し，その認識精度を向上させることである. 一般のカーネル法では，カーネル関数は同じ非線型写像の内積で与えられていることを前提としている。本研究ではカーネル法を拡張し，内積の右辺と左辺に代入する非線型写像を異なるものとした理論を SVM に適用する. また訓練データに有効なカー
ネルパラメータを与える方法とその有効性を計算機実験により確かめる.

1

Introduction

x2

Optimal hyperplane classifier (OHC) classifies aninput pattern by a hyperplane. Support vector machine (SVM), which is a kernelized version of OHC,
attained high classifier accuracy. A nonlinear andcomplicated boundary can be realized by the kernel method. However, since a kernel function has
to be symmetric and positive-definite, the direct realization of SVM with a variable kernel function
is a difficult problem. In order to solve this problem, we apply the asymmetric kernel method to
OHC, and proposed the SVM with a variable kernel founction. Furthermore, we apply it to twoclass classification problems and show experimental results.

2

OHC of SVM

2.1

Linear Support Vector Machine

|θ|
kwk

x1

M

d(x) = 0

Figure 1: OHC or Margin

Hyperplanes (hw, xi + b = ±1)are parallel and thatno training point falls between them.Thus we canfind the pair of hyperplanes which gives the maxi2.1.1 The separable casemum margin by minimizing kwk2 , subject to conAssume that patterns are in Rd . Let Y = {+1, −1} straints (3).
be a set of labels. Consider the labeled training
data {x1 , y1 }, . . . , {xn , yn } ∈ Rd × Y. Suppose we 2.1.2 The non-separable casehave some hyperplane which separates the positivefrom the negative examples. The support vector al- The above algorithm for separable data, when apgorithm simply looks for the separating hyperplane plied to non-separable data, will find no feasible
with largest margin. It can be formulated as fol- solution. SVM is extend these ideas to handle nonlows : suppose that all the training data satisfy the separable data. We would like to relax the constraints (1), but only when necessary, that is, wefollowing constraints,
would like to introduce a further cost for doinghw, xi + b ≥ +1 f or yi = +1
(1) so. This can be done by introducing positive slack
hw, xi + b ≤ −1 f or y j = −1
(2) variable ξi > 0, i = 1, · · · , l in the constraints, whichthen become:
These can be combined into one set of inequalilhw, xi + b ≥ +1 − ξi f or yi = +1
(4)
ties:
(5)
hw, xi + b ≤ −1 + ξi f or y j = −1
yi (hw, xi i + b) − 1 ≥ 0(3)63

Technical Report of International Development Engineering

TRIDE-2006-01, February 20, 2006 (ISSN 1880-8648)

x2

Thus, for an error to occur, the corresponding ξimust exceed unity, so ∑ ξi is an upper bound on
the number of training errors. Hence a natural way
to assign an extra cost for errors is to change theobjective function to be minimized from kwk2 /2
to kwk2 /2 + C ∑ ξi , where C is a parameter to bechosen by the user, a larger C corresponding to assigning a higher penalty to errors.

Class A

1

-1

1

x1

Class B-1

2.2 Nonlinear Support Vector Machine (Kernel method)
The above methods are generalized to the case where
the decision function is not a linear function of
the data. Now suppose we first mapped the data
to some other (possibly infinite dimensional) Euclidean space ℜ ,using a mapping which we willcall Φ : Rd → ℜ. Then of course the training algorithm would only depend on the data through theinner products in ℜ, i.e. on functions of the formhΦ(xi ), Φ(x j )i.
Consider about the identification of two classes
A and B. The samples of classes A and B as figures2,
f1A = (1, 1),

f2A = (−1, −1)(6)

f1B = (1, −1),

f2B = (−1, 1)(7)

Figure 2: examples of the kernel method:A
x3

2

x2
Class A1

1

x1

Class B

-2

Figure 3: examples of the kernel method:B

are given. In this case, this sample cannot be sepa3 Variable Kernel Method
rated by the linear identification function. In otherwords, classes A and B can not be separated by the In the kernel method, the complexity of the boundstraight line. When mapping Φ
ary depends on the kernel function of SVM thatwas limited to be a positive definite symmetry funcΦ : R2 → R3
tion. So it was difficult to make the kernel param(x1 , x2 )> 7→ (x12 , x22 , 2x1 x2 )>(8) eter variable. The complexity of the best boundary
for identification varies according to place. So it
is used and the samples areis necessary to make it variable. In a conventional
kernel method,Φ( f1A ) = (1, 1, 2), Φ( f2A ) = (1, 1, 2)(9)k(x, y) = hΦ(x), Φ(y)i(14)
Φ( f1B ) = (1, 1, −2), Φ( f2B ) = (1, 1, −2) (10)the kernel function is defined by the inner prodThe new sample are illustrated in figure 3．As a uct between the images by the same mapping Φ
result, it comes to be able to separate the sample like expression (14). Therefore, the condition ofof class A and B by the plane. Now if there were a positive-definite symmetric function was necessary”kernel function” K such that K(xi , x j ) = hΦ(xi ), Φ(x jfor
)i, the kernel function. In the asymmetric kernel,
we would only need to use K in the training alk(x, y) = hΦ1 (x), Φ2 (y)i(15)
gorithm, and would never need to explicitly evenknow what Φ is, The examples of the kernel func- the kernel function is assumed the inner producttion are given as
between two images by the two different feature

mapping Φ1 and Φ2 like expression (15). The asymmetric kernel method is applied to SVM. In this rek(x, y) = (hx, yi + 1)d : Polynomial(12) search, we use the Gauss kernel. Here, the parameter to the feature space previously gives a changekx − yk2k(x, y) = exp(−):
Gaussian(13)
able nonlinear map, and the kernel function is pro2σ 2vided by the map. Let σ (x) be a changeable kernel parameter for the learning pattern, and σ1 bek(x, y) = hx, yi : Identical

(11)

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TRIDE-2006-01, February 20, 2006 (ISSN 1880-8648)

a fixed kernel parameter for an unknown pattern.
Table 1: Results of two-class classification
Moreover, Let σ0 be a standard kernel parameter,
and the value uses the kernel parameter of comName
SVM in thesis
SVM
VSVM
Banana11.5 ± 0.7 10.85 ± 0.62 10.48 ± 0.52
pared SVM.
26.0 ± 4.7
28.79 ± 4.6
24.8 ± 4.6
Here, the variable nonlinear map Φ1 (x) and Φ2 (x) B.Cancer
Diabetes
23.5 ± 1.73 24.09 ± 1.89 23.26 ± 1.73
to feature space are definited by
F.Solar32.4 ± 1.8
37.51 ± 2.9
32.4 ± 1.8
German23.6 ± 2.1 24.07 ± 2.18
23.6 ± 2.1µ¶K −kx−yk2
σ0
Heart
16.0 ± 3.3 17.48 ± 3.36
16.0 ± 3.3
2 (x)
2
σ
(Φ1 (x))(y) =e(16)Ringnorm
1.7
±
0.1
1.64
±
0.12
1.7 ± 0.1
1/4(2π ) σ (x)Thyroid
4.8 ± 2.2
5.4 ± 2.41
4.05 ± 2.14µ¶K −kx−yk2
Titanic
22.4 ± 1.0 22.28 ± 1.03
22.4 ± 1.0
σ02
Twonorm
3.0 ± 0.2
2.62 ± 0.17
3.0 ± 0.2
(Φ2 (x))(y) =
e 2σ1
(17)
1/4
(2π ) σ1
Waveform
9.9 ± 0.4
9.88 ± 0.42
9.9 ± 0.4
The necessary variable kernel functions are givenask(x, y)= hΦ1 (x), Φ2 (y)iZ=

(Φ1 (x))(z)(Φ1 (y))(z)dzK
−kx−yk2
σ0 e 2(σ 2 (x)+σ12 )= q
σ 2 (x) + σ12RKandk1 (x, y)= hΦ1 (x), Φ1 (y)iÃσ0p=
σ 2 (x) + σ 2 (y)the same identification rate as SVM was shown.
This is because a complex identification boundary(18) is expressd well according to the density distribu(19) tion. and the feature of the sample is effectively
extracted.
(20)

6Conclusion

The kernel method was extended, the variable kernel SVM is proposed and effectiveness is shown by
the recognition experiment. Moreover, application
to a variety of recognition problems are enumer(21)ated as a problem in the future. Moreover, a further!K−kx−yk2
work is needed about how to decide the parameter.
e 2(σ 2 (x)+σ 2 (y) (22)References

In this research, we choose zl from all training patterns xl when the distance between the separating [1] C. Cortes and V. Vapnik, “Support-vector
hyperplane and xl is less than 1.1 · kwk. Moreover,
networks,” Machine Learning, vol.20, no.3,
p
pp.273–297, 1995.
σ1 = σ0 α /2(23)p
σ (zl ) = β (zl )σ0 1 − α /2(24) [2] Y.S. Hwang and S.Y. Bang, “An efficientmethod to construct a radial basis function
α is asymmetric parameter. β (zl ) is assumed 0.5
neural network classifier,” Neural Networks,
when zl is mis-recognized, and, besides, assumed
vol.10, no.8, pp.1495–1503, Nov. 1997.
to 1.0.
[3] J. Mercer, “Functions of positive and negative
type, and their connection with the theory of
4 Computer Experimentintegral equations.,” Trans. Lond. Phil. Soc.
(A), vol.209, pp.415–446, 1909.
We also conduct experiments by two-class classification problems. The mean test error rates and [4] S. Mika, G. Rätsch, J. Weston, B. Schölkopf,
A.J. Smola, and K.R. Müller, “Invariant featheir standard deviations are shown in Table 1. All
ture extraction and classification in kernel
values are described in percentage and bold fontspaces,” Advances in Neural Information Promeans the best result in this method.
cessing Systems 12, ed. M.S. Kearns, S.A.
Solla, and D.A. Cohn, pp.526–532, MIT Press,
5 Discussion
2000.
The variable kernel SVM was surpassing of the [5] M.T. Musavi, W. Ahmad, K.H. Chan, K.B.
identification rate of the previous SVM. Their adFaris, and D.M. Hummels, “On the training
vances are also shown by T-test. Besides, almost

65

Technical Report of International Development Engineering

TRIDE-2006-01, February 20, 2006 (ISSN 1880-8648)

of radial basis function classifier,” Neural Networks, vol.5, no.4, pp.595–603, Aug. 1992.
[6] B. Schölkopf, A. Smola, and K. Müller, “Nonlinear component analysis as a kernel eigenvalue problem,” Neural Computation, vol.10,
no.5, pp.1299–1319, 1998.
[7] Koji Tsuda, “Support Vector Machine with
Variable Kernel Function,” Technical Reportof Ieice,no.PRMU98-175, pp.195–202, Dec.
1998.
[8] Eisaku Maeda and Hiroshi Murase, “Pattern recognition by kernel nonlinear subspacemethod” Technical Report of Ieice (D-II),
vol.J82-D-II, no.4, pp.600–612, April 1999.
[9] Koji Tsuda, “Subspace classifier in the Hilbert
space,” Pattern Recognition Letters (D-II),
vol.J82-D-II, no.4, pp.592–599, April 1999.
[10] C.J. C. Burges,“A Tutorial on Support Vector Machines for Pattern Recognition” Data
Mining and Knowledge Discovery,vol.J82-DII, pp.121-167,1998

66

Moving picture coding with pixel motion
compensation
TRIDE-2006-01,
February 20, 2006 (ISSN 1880-8648)
prediction

Technical Report of International Development Engineering

Student Number 04M18133 Name Takayuki SHINOZAKI Super visor Yukihiko YAMASHITA

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MPEG

1 Introduction
In recent years, the information communication technology called IT (Information Technology) is splendidly
developed. Not only a document but also picture, asound, etc. are widely used for communication. However, the amount of information of the multimedia data
which generally contains digitized pictures and sounds
are huge. Therefore, in order to treat the information,
the transmission way and the mass storage medium of abroadband are needed. Then, research on reduction of
the information by the data compression of pictures orsounds so-called compression coding came to be popular for the purpose of efficient use. Although the broadband communication can be used in wide area, narrowband communication is also used. Then, efficiency ofimage coding has to be increased.
Video coding is the method of compressing by reducing the redundancy included in video. There are
two kinds of the redundancy of video data. One is thespatial redundancy and the other is time redundancy.
The former is mainly used still picture coding. JPEG
(JointPhotographic Experts Group) which is the international standard system of still picture coding is the technique used very widely. And the algorithm called motion compensation prediction is used in the latter reduction. This is used in by MPEG (Moving Picture Experts
Group) which is the international-standard system ofvideo coding. It became possible to code and compress
video data at high efficiency by these two techniques
compared with the former. However, such algorithm
had the problem in a decoding picture. Visual degra-

dation called block distortion is produced from process
per block.
In order to solve this problem, we propose the moving picture coding with pixel motion compensation prediction. The wavelet coding which reduces block distortion is applied to video coding. Therefore, motion
compensation prediction which is a process in a block isconventionally performed per pixel. Thereby, the problem of block distortion is removed. Moreover, various
movement toward rotation, expansion reduction, etc. whichwere not able to respond conventionally can be extracted
more correctly. Since correlation of data becomes high,it becomes possible to perform efficient compression.
Therefore, it is thought that decoding which suppressed
quality-of-image degradation is realizable in small amountof data. This thesis explains the algorithm of the proposal technique. Next, the validity is confirmed by comparing with MPEG which is a general video coding system by using a computer experiment.

2 MPEGAn MPEG standard is a standard of the multimedia
coding for accumulation media, broadcast, communication, etc. It mainly consists of three regulations, such as
the regulation on the coding method of a video signal,
the regulation on the coding method of an audio signal,and for both integrated method.
Video data is realized by set of the still picture located in a line on the time-axis generally called a frame.
MPEG performs compression coding by reducing thosespatial redundancy and time redundancy. Reduction of67

spatial redundancy is called the coding in a frame, andTechnical Report
International
Development
Engineering
performs
DCTof(discretecosinetransform),
quantization,and coding every 8×8 [pixel] block. Moreover, reduction of time redundancy is called the coding between
frames, and is performed using the technique of motion
compensation prediction. This is extracting and treating
the motion information on a certain domain in a picturein two near frames in time. More than it reduces only
the redundancy in a frame, it is the technique of making
it possible to reduce the redundancy of video. Generally, block matching is performed every 16×16 [pixel]
block. And the motion vector which is motion information is extracted. The general procedure of motion
compensation prediction is shown below.
1. Extraction of moving vector by comparing frame
for encoding with reference frame
2. Generation of the prediction picture by the motion vector and the reference frame

3 Moving picture coding with pixel
TRIDE-2006-01, February 20, 2006 (ISSN 1880-8648)
motion compensation prediction
In the coding using the block matching method represented by MPEG, the problem of producing block distortion which is visual lattice-like degradation was in
the reconstructed video. On the other hand, in the fieldof still picture coding, the coding which reduces block
distortion using wavelet transform and subband conversion as a technique has been advocated. Then, in order
to control block distortion produced in video, we try toapply the coding (wavelet coding) which used wavelet
transform. In order to control block distortion using
wavelet, the motion compensation prediction which isused block matching is not efficient. Then, we propose the pixel motion compensation prediction which
extracts the information on a motion in a pixel.

3.1 Pixel motion compensation prediction

3. Generation of the picture of the difference by thedifference of the prediction picture and the frame
for coding
4. Coding of the motion vector and the picture ofdifference

The reliability of matching is high since motion presumption by the conventional block matching method
might use the macro block of 16×16 pixel. Comparison of the value of a pixel will realise motion presumption in a pixel unit. However, this lacks in the reliability

5. Execution of 1. to the following two frames

as a presuming method. Therefore, in order to obtain
exact matching of a pixel, by the proposal technique,

The main coding parts of MPEG are realized with the
combination of the coding between frames and inside

we use the recursive algorithm which narrows down atarget from the rectangle range of a certain amount ofof a frame. First of all as a basic procedure of MPEG,
the frame of the beginning of video or the frame usedsize gradually. Moreover, in order to prevent a motion

as a starting point performs only the coding in a frame.

vector coming dispersing, a smooth portion is detectedby the picture and processing suitable for the portion is

These frames omit Intra-coded picture and are called
I-picture. I-picture which had conversion-quantization

performed. The algorithm of pixel unit motion compensation prediction is as follows.

performed here is reverse-changed by the local decoder,and is temporarily memorized by the frame memory.

1. A target block is made to match with a reference
frame using the block of 16×16[pixel]. The variance of each pixel value is calculated, and when

Next, frames other than I-picture perform the coding between frames which uses motion compensation predic-

the value is below fixed, a block is not divided
any more.

tion. There are P-picture and B-picture in these frames.
The obtained prediction picture which is made based ona vector and it, and the picture of the difference of a target frame are coded. This reduces time redundancy and2. 4 division (it is called a mini block) of the target
block is carried out.

more efficient compression is performed.

3. To four of each, if the length of the neighborhoodof a mini block is not 1 pixel, go to Step 3. Whena target block becomes 1 pixel (it is called a target
pixel), it is to Step 4.

68

4. It is search within the limits and a mini block is
Technical
ReportInternational
Engineeringmadetoofmatch.
The Development
size of a matching
block isTRIDE-2006-01, February 20, 2006 (ISSN 1880-8648)

made into a mini block twice. A motion vector
can be extracted thereby more correctly. At thistime, the search range is the square domain extended by halves of a length of one side of a mini
block on the four directions of the place which
the mini block was referring to. A mini block is
considered as a new target block, and it returns to
Step 2.

Fig. 1: Intersection

5. It matches in the corresponding 1-pixel range ofthe pixel circumference using the block of 2×2
pixel. Then, the pixel which corresponded in thematched block is made into a reference pixel, anda motion vector is calculated.

3.2 Wavelet coding
Wavelet coding is used for the compression coding in
the case of mainly inclining information for every frequency band. When especially energy inclines toward
the low cycle, it is known that coding of very high efficiency is possible. There is the coding method called
SPIHT (Set Partitioning In Hierarchical Trees) which is
specialized in the tree structure of wavelet. This cod-Fig. 2: PSNR for different bitrates (I frame)
is used for numerical assessment. PSNR is given by thefollowing formulas here.

ing method is used for the coding part of the proposal
technique. Correlation will become high supposing the
2-dimensional motion vector obtained by motion compensation prediction of a pixel unit is extracting the motion correctly. Therefore, information inclines toward
lower frequency domain. Moreover, the absolute valueof the pixel of the picture of the difference becomesvery small. Therefore, both information is compressible at high efficiency using the above-mentioned wave
let coding.

3.3 Image coding experiment
In an experiment, two frames of the standard video
sequence for assessment of are used for I-picture andP-picture, respectively. And coding and decoding were
performed by the proposal technique. The example of aframe is shown in Fig. 1. Moreover, it compared with
MPEG used as codec of Hi-Vision or standard qualityof-image television. And quality-of-image degradationof a decoding picture was evaluated numerically. PSNR

MSE =

255
PSNR(dB) = 20 log
MSEs−1 H−102∑W
x=0 ∑y=0 ( f (x, y) − f (x, y))
WH

(1)
(2)

In coding of I-picture, the block distortion of the shapeof a lattice produces MPEG which performs block processing in a decoding picture. However, block distortion is not produced by the proposal technique. By comparison by PSNR, it turned out in the amount of marks
with the same proposal technique that a picture better
than MPEG is obtained. This result is shown in Fig. 2.
In coding of P-picture, The motion vector of the x directions expressed by tone of before and after coding to
Fig. 3 and 4 are shown. Moreover, the result of having performed comparison with MPEG by numericalassessment is shown in Fig. 5. In order to carry out assessment, the same bit length used for MPEG, I-picture
and P-picture of the proposal technique is taken as thesame quantity. This shows that P-picture is surpassingof MPEG at 0.51 [bpp]. However, the proposal tech-

69

Technical Report of International Development Engineeringcrease. Therefore, motion detection method has to be
progressed. TRIDE-2006-01, February 20, 2006 (ISSN 1880-8648)
Moreover, there is one more problem in this technique. It is that decoding takes time. The reason isfor wavelet transform and SPIHT which codes coefficients to take time. The measurement result of the time
concerning these is shown in Table 1. Considering that
MPEG processes 30 frames in 1 second, it turns out that

Fig. 3: Before encoding

this has taken time overwhelmingly.
SPIHT

wavelettarget frame

3.00

0.51

difference and MV

0.79

1.52

Table 1: decoding time [sec]4 Conclusions
Fig. 4: After decoding
nique has caused remarkable quality-of-image degradation in the domain which is carrying out regular form
like the white line of a crossing paved road or a track ina target frame. This is because matching in a detailed
portion is wrong and correlation of a motion vector be-

In this paper, the video coding method using pixel
motion compensation prediction was proposed, and thecomputer experiment was conducted. Moreover, the advantage was shown by comparing with MPEG which
is an international image coding standard. For future
work, we have to develop the pixel motion detection
method that provides more highly correlated motion vectors, and a more efficient coding method for the differ-comes low in the case of pixel motion compensationence image. Furthermore, calculation speed have to beprediction.
increased.
However, for complicated and high frequency domains,such as persons and characters, matching accuracy ishigh. Therefore, it turned out that degradation is reduced in such regions. If a motion vector can be correctly extracted by high correlation, distortion will de-References[1] Yoshinori Sakai Toshiyuki Yoshida “Image information encoding”, Ohmsha, 2001.
[2] Sadayasu Ono Junji Suzuki “Achievement
method of comprehensible JPEG/MPEG2”
Ohmsha, 1995.
[3] Susumu Sakakibara “Wavelet beginner’s guide”
Tokyo Electrical Engineering College Publications
Service 1995.
[4] Amir Said, William A.Pearlman “A New Fast andEfficient Image Codec Based on Set Partitioningin Hierarchical Trees” IEEE Trans. Circuits andSystems for Video Technology, vol.6, pp.243-250,

Fig. 5: PSNR for different bitrates (P frame)

June. 1996.

70

Technical Report of International Development Engineering

TRIDE-2006-01, February 20, 2006 (ISSN 1880-8648)

Propagation Paths Measurement System for Electronic Toll
Collection Systems (ETC)
Student Number: 04M18038

Name: Yumihiko ANNAKA

Supervisor: Jun-ichi TAKADAETC 電波伝搬パス同定システムの提案
安中 弓彦
自動料金収受システム (Electronic Toll Collection Systems, ETC) は，高速道路料金所において，停車することな
く料金の支払いを無線通信によって行うシステムである．このシステムにおいて，マルチパスや隣接レーンからの漏洩などの不要波により，通信障害が発生する．問題が起きうる不要波抑圧のために，料金所では電波吸収体が設置されているが，吸収性能が経年劣化するため，その性能を随時確認出来るシステムが必要となる．このような背景から本研究では ETC の実信号を用い，実時間で電波の伝搬経路を同定できるシステムを提案する．このシステ
ムにより同定された個々の伝搬経路に着目し，個々の劣化した電波吸収体の劣化度を評価することができる．また，伝搬経路を同定するアルゴリズムについても，種々の検討を行った．

1

Introduction

1.1

Background

For the real time measurement, it is beneficial thatthe system is installed on a car. When this car passes
through a toll gate, it receives the ETC signal andrecords it.

Recently, the demand for short range wireless communications has been increasing.
In express ways, the intelligent transport systems (ITS), 1.3 Objective of the study
a new transportation system in order to resolve traffic From several reasons mentioned in the subsection 1.2,
problems by sharing information networks among peo- the propagation paths measurement system using a mulple, road, and vehicles [1], is considered. ITS covers sev- tichannel receiver equipped with an array antenna iseral development areas. One of them is the electronic proposed in this thesis.
toll collection systems (ETC).
The objective of this study is to propose the propagaThe ETC is a wireless communication system between tion paths measurement system for the ETC that cana transmitter at the toll gate and a receiver attached be operated in a real time by using the real ETC signal.
inside the car. This system executes the automatic pay- The system should be installed on a car, equipping thements without stopping at the toll gate.
array antenna.
Also, this thesis develops a new AOA estimation scheme
1.2 Problems of radiowave propagation using only amplitude data.

in ETCIn Japan, the ETC has some problems in system operations due to undesired waves via unexpected paths[2]. The undesired waves may cause the communication
error, such as a double accounting, crashing to gate, or
unexpected accounting.
The Japan Highway Public Corporation (JH) installs
the radio absorbers on the whole surfaces of the tollgates to surpress the reflected waves, and also installs
the transparent radio absorbers between adjacent lanes
in order to suppress the inter-lane interference. However, the function of absorbers may be degraded byaging deterioration, so the function of the absorbers
should be regularly maintained for the sustainable usage of the system. Then, the system that can evaluate
the performance of the radio absorbers is needed. The
propagation paths measurement system can do that. It
is impossible to estimate the propagation path directly,
instead, we estimate the angles of arrival (AOA) of individual paths and identify the scattering points. The
system can resolve the paths to identify each individual
contribution of the absorber.
In addition, the measurement at the gates in operation should be finished within a short period of time,
because the long time measurements cause traffic congestion. Then, a real time measurement system is required.

71

2

System ArchitectureThis section introduces the format of the ETC signal
and architecture of the hardware.

2.1

Format of the ETC signal

The ETC signal has been standardized by Associationof Radio Industries and Businesses (ARIB) [3].
The wireless access method of the ETC signal is TDMAFDD, which is a method that the frequency of uplinksignal is different from that of downlink signal, and different time slots are allocated for different users.
Since the proposed system uses the downlink signal,
the ETC signal in this thesis represents the downlink
signal. The specification of the ETC signal is shownas Table 1. The modulation scheme is amplitude shift
keying (ASK), which uses split-phase encording.

2.2

Hardware of the proposed channelsounding techniqueThis subsection describes the hardware architecture of
the proposed system. Two types of hardware are introduced. One measures both phase and amplitude of thereceived signal, The other does amplitude only.

Technical Report of International Development Engineering

TRIDE-2006-01, February 20, 2006 (ISSN 1880-8648)

Table 1: Specification of the ETC signal (downlink)
Multiple-accessFrequency
Bit rate
Modulation
Flame length
Polarization

TDMA-FDD
5.795, 5.805GHz
1024kbps
ASK
Less than 900 bytes
Right hand circular polarization

PIN
SwitchSpectrum
Analyzer

2.2.1

Hardware to measure phase and ampliFigure 2: Hardware to measure only amplitude of thetude
received signal
Figure 1 illustrates the hardware to measure amplitude
and phase of the received signal. The structure is similar to the conventional channel sounders, such as [4]. sented. The first scheme is to estimate phase by Hilbert
It consists of several heterodyne receivers, and all re- transform and reconstruct received signal. The second
ceivers share the common local oscillator (LO) in order scheme is to use the power spectrum to jointly estimate
the cross spectra for all the AOAs simultaneously.
to synchronize themselves for measuring phase.
The parameters to be estimated are amplitude al andantennaangle of arrival φl , where l is the index of the path.
I/Q
ATT
ATT
(patch antenna)
IF
AMP
ASK
Figure 3 shows the coordinates to define φl . Let us
LPF
DEMOD
D/C
AMP
Ich
modulated wave
assume a linear array aligned on x axis. H(x) denotes
Qch
isolator
the voltage of the received signal at position x, and isexpressed as
A/Dantenna
AMP

isolator
ATT

PLO
RF:5795
ATT

ATT

ATT
D/C

LPF

I/Q
IF
DEMOD
AMP
Ich

H(x) =



8 or 16ways
isolator

al exp(jkc x cos φl )

(1)

l=1

Qch



L
X

where kc is a wavenumber 2π/λ, L is the number ofarrival waves, λ is a wavelength.

8 or 16
ways
LO
AMP

al (amplitude)

OCXO
PLO
RF:5805φl (azimuth angle)
Figure 1: Hardware to measure phase and amplitude of
the received signal

2.2.2





x

Hardware to measure only amplitude

Figure 3: The definition of coordinate and parameters
Figure 2 illustrates the hardware to measure only amplitude of received signal. The system has a simpler
structure than the system described in the section 2.2.1,
because the synchronization among channels is not nec- 3.1 Phase reconstruction scheme assumessary. Therefore it costs lower.
ing maximum-phase system
Two types of the hardware architectures for measuring
only the amplitude of the received signal can be consid- This scheme requires the following 2 conditions.
ered. One is to use RF PIN switch and a single receiver,• Measurement environment shall be line-of-sightshown as Figure 2. The other is to prepare multiple re(LOS).
ceivers, just like Figure 1, but it is not necessary to use
The arrival angle θd of the strongest wave, i.e. dicommon LO.
rect wave shall be known prior to the signal processing.

3

AOA estimation scheme using
only amplitude• Two linear arrays shall be used.
These base-lines shall not be in parallel, such as a
V-shaped array dipicted in Figure 4.

In this chapter, two novel AOA estimation schemes usThe key point of this algorithm is the phase estimaing only the amplitude data of array output are pre- tion from |H(x)| with an assumption that H(x) is the72Technical Report of International Development EngineeringLinear array 1

TRIDE-2006-01, February 20, 2006 (ISSN 1880-8648)

8. Derive the angular spectrum h̃02 (θ) in the linear
array 2 by the same process from 1 to 7.

Linear array 2

9. Compare h̃01 (θ) with h̃02 (θ) and the peaks appearedin the same angles are determined as the true
waves.

ααθdAntenna element

These procedures are shown as a flowchart in Figure
5.

The strongest wave

x2

x1
Obtain |H1(x1)|by the linear array 1.

θEstimate the phase of
H1(x1) , assuming H1(x1)
is the maximum-phase.

Figure 4: V-shaped array

Reconstruct Hm1(x1) .

maximum-phase. The estimation is carried out in thefollowing steps:

Transform Hm1(x1) to thewavenumber space by the
Fourier transform.

1. Obtain the amplitude of |H1 (x1 )| by the linear
array 1 defined in Figure 4, where H1 (x1 ) is areceived signal by the linear array 1, and x1 axis
is an array axis of the linear array 1.
2. Estimate the corresponding phase of |H1 (x1 )| by
using Hilbert transform by assuming H1 (x1 ) is the
maximum-phase [5],arg Hm1 (x1 ) = Ψ [log |H1 (x1 )|] ,

k
0

∆k1
h01(k)(2)

where Hm1 (x1 ) is an estimated complex signal assuming the maximum-phase condition, Ψ [·] denotes the Hilbert transform.

k
−∆k1

0

∆k1
h001 (k)(kd1 = kc cos(θd − α))3. Reconstruct the received signal Hm1 (x1 ) by
Hm1 (x1 ) = |H1 (x1 )| exp (j arg Hm1 (x1 )) .

The same signal processing asthat in the left box,
conducted by the linear array 2.

h1(k)

(3)

k
kd1 − ∆k1 kd1 kd1 + ∆k1

4. Transform Hm1 (x1 ) to the wavenumber space by
the Fourier transform asZ ∞h1 (k) =H1 (x1 )e−jkx1 dx1 .
(4)Same length0h˜1 (θ)

False

−∞

True

0
h˜2 (θ)

False

True

θ

θ

θd

θd

Where h1 (k) satisfies the causalty in the spacedomain h1 (k) = 0; k < 0. Due to the limitationof the amplitude measurement, the waves that has Figure 5: Flowchart of AOA estimation assuming thenegative and positive k cannot be distinct. The maximum-phaseformer is projected to the latter. The peak at
k = k 0 (> 0) has an ambiguity whether its true
peak is at k = k 0 or k = −k 0 .

3.2

Direct AOA estimation from power

5. Turn back the wavenumber spectrum h1 (k) at k =spectrum0,½
h1 (k) k ≥ 0
h01 (k) =(5) The algorithm also requires the knowledge about the
AOA of the strongest wave. The received spatial powerh1 (−k) k < 0.
spectrum P (x) = |H(x)|2 is
6. Shift h01 (k) so much as +kc cos(θd − α) along k
axis,h001 (k) = h01 (k − kc cos(θd − α)).

P (x) =L X
L
X

n=1 m=1(6)an a∗m exp (j(kn − km )x) .

(9)

The Fourier transform of P (x) is

7. Transform h001 (k) to the angular domain,h̃1 (φ) = h001 (kc cos φ),(7)h̃01 (θ) = h̃1 (θ − α).

(8)

73

p(k) =L X
L
X

n=1 m=1

an a∗m δ (k − (kn − km )) .

(10)

Technical Report of International Development Engineering

TRIDE-2006-01, February 20, 2006 (ISSN 1880-8648)

The peaks of p(k) are at {∆kn,m = kn −km }Ln,m=1 . The
implementation flow of this algorithm is following:

on a car, which equips the array receiver to estimate
AOA.
AOA estimation algorithms using only amplitude are
discussed. Although they are advantageous in the implementation of the hardware, their performance arepoor. The conventional scheme utilizing both amplitude
and phase was finally considered for the proposed application. The detail is not described in this abstract, but
successive interference cancellation based space-alternating
generalized EM (SIC-SAGE) [6][7][8][9] has been considered. The difficulty was the detection of the weak paths,
which needs further investigation.

1. Obtain the spatial power spectrum P (x) by array
antenna.
2. Calculate p(k) by the Fourier transform of P (x).
The maximum k value of the peak position is∆k1,L , assuming the condition k1 > k2 > · · · >kL .
3. Choose any (L − 1) peak positions of p(k) except∆k1,L , and let the value of k at these chosen (L−1)
peaks be ∆k̂2,L , ∆k̂3,L , · · · , ∆k̂(L−1),L .

References

4. Estimate L C2 peak positions {∆k̂n,m }Ln,m=1 bychosen (L − 1) peak positions as[1] Road Bureau ITS homepage.
http://www.mlit.go.jp/road/ITS/∆k̂n,m = ∆k̂n,L − ∆k̂m,L(11)[2] K. Haneda, J. Takada, T. Iwata, Y. Wakinaka,
and T. Kunishima, “Experimental Determination of
5. Confirm if L C2 peak positions estimated in the
Propagation Paths for the ETC System - Equipment
previous step match the original L C2 peak posiDevelopment and Field Test,” IEICE Trans. Fundations.
mentals, Vol. E87-A, No. 11, pp. 3008-3015, Nov
2004.
6. If they match, they are final estimates of ∆kn,L .
If not match, come back to step 3 and other L [3] “Dedicated Short-Range Communication System,peaks are chosen again.
ARIB Standard” Association of Radio Industries
and Business.
7. The maximum peak value among these L peaks
corresponds to the peak of the direct wave, and [4] K. Sakaguchi, J. Takada, and K. Araki, “A novel
its position can be kM − kL . Then, it is possible
architecture for MIMO spatio-temporal channel
to estimate k1 , k2 , · · · , kL .
sounder,” IEICE Trans. Electron., Vol. E85-C, No.
3, pp. 436-441, Mar, 2002.
From Shannon’s sampling theorem, the length d between antenna elements must satisfy d < λ/4, which [5] Y. Annaka, J. Takada, “Direction of arrival esis half a length when the conventional AOA estimation
timation based on amplitude-only array output,”algorithm applys. It means that the angular resolusion
IEEJ Instrumentation & Measurement Society, IMis half of other conventional methods, because the array05-027, pp. 43-47, June, 2005.
size is halved for the same number of elements.
[6] J. A. Fessler, A. O. Hero, “Space-Alternating Generalized Expectation-Maximization Algorithm,” IEEE
3.3 Evaluation of proposed schemes
Transactions on Signal Processing, Vol. 42, No.10,
In this section, two AOA estimation schemes using only
pp. 2664-2677, October, 1994.
the amplitude of array output are presented.
The first one reconstructs the complex signal assuming [7] B. H. Fleury, M. Tschudin, R. Heddergott, D.
Dahlhaus, and K. I. Pedersen, “Channel Parameterthe maximum-phase condition. Further mathematical
Estimation in Mobile Radio Environments Using theinvestigation revealed that this algorithm can estimate
SAGE Algorithm,” IEEE Journal on Selected ArAOAs if and only if all waves but direct wave arrive at
eas in Communications, vol. 17, No. 3, pp. 434-450,
only one side with respect to the direct wave. If more
March, 1999.
than 2 waves arrive at the both sides, AOAs can not be
estimated correctly.
The second one uses the spatial power spectrum. This [8] B. H. Fleury, D. Dahlhaus, R. Heddergott,
Mtschudin, “Wideband Angle of Arrival Estimation
algorithm can estimate AOAs if all the real peaks can be
Using the SAGE Algorithm,” in Proc. IEEE Fourth
distinguished from sidelobes. But the angular resolution
Int. Symp. Spread Spectrum Techniques and Appliof this algorithm is worse than the conventional one.
cations, Mainz, Germany, pp. 79-85, Sept, 1996.
It is concluded that AOA estimation algorithm using
only the amplitude is not feasible for the proposed ap- [9] B. H. Fleury, X. Yin, K. G. Rohbrandt, P. Jourplication.
dan, A. Stucki, “Performance of a High-Resolution
Scheme for Joint Estimation of Delay and Bidirection Dispersion in the Radio Channel,” in Proc.
4 Conclusion
IEEE 55th Veicular Technology Conference (VTC
2002/Spring), pp. 522-526, May 2002.
In this thesis, the radio propagation measurement system for the ETC is proposed. The system is installed

74

Technical Report of International Development Engineering

TRIDE-2006-01, February 20, 2006 (ISSN 1880-8648)

Analysis of Radio Wave Propagation in Highway Electronic Toll
Collection Gate  

(@?#A)$ (=&7BD' C .E)FG4 ETC[^k *,+- ?7(IA#H%l%J%m,K=n L7"gMON(O]#P%oVQ 3S[^Rk TV U !#C "%$%&#')( (%ETC
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P =9L5[@aS|,X }% C U 3 ] .O2~oV4%W^i [DX=kj#Y %C  f@[Dw x1 y#E zh { .@[^i  j2h535t 4u=)Sh9a17)<\-/. .10 2%3,f~,<%11+71Z5g:;+#\S< 2%3
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Student Number: 04M18268 Name: Junsheng Lu Supervisor: Jun-ichi TAKADAETC

1Introduction

The Electronic Toll Collection System (ETC) has beendevelopped in last several years. In March 2001, theETC service was started. Until March 2004, ETC system had been implemented in more than 900 toll gatesacross the country [1].
Recently, there were some problems reported on the
ETC system. One of the most reported problems isthe electronic wave interference happened between two
adjacent lanes. As the result, for example, the bar does
not open even the toll is collected, or the the toll iscollected twice when the automobile passes the toll gate.
The reason of the interference is considered to be thereflection and diffraction of the electronic waves.
In this research, where the interference happened in
ETC gate was found out by experiment and computer
simulations.

2

Experiment

2.1

Preparing Experiment

Figure 1: Receiver Signal Level Characteristics Experiment Result

In order to see where the measurement point would be
set on, the preparing experiment, receiver signal level
characteristics experiment, was conducted by Japan Highway. As the result, the receiver signal around 2 metersarea is higher than −70dB, the threshold for malfunction. Hence, the ultrawideband array measurement was
conducted around 2 meters area. The receiver signal
level characteristics experiment result is shown in Figure 1.

2.2

Propagation Path Estimation Experiment

The propagation path estimation experiment was doneon Feburary 24th, 2005 in Akiruno toll gate in the central Tokyo Area. The measurement area includes tollgate, two lanes and one spraying lorry. Figure 2 showsthe experiment environment.
The propagation path estimation includes two parts.
One is Direction of Arrival (DoA) estimation and delay time estimation. Ultrawideband array measurement
was conducted for propagation path estimation. The
mesurement system is shown in Figure 3.

75

Figure 2: Experiment Environment

Technical Report of International Development Engineering

TRIDE-2006-01, February 20, 2006 (ISSN 1880-8648)

Figure 3: Measurement System

The transmission antenna is double ridged guidehorn
antenna, and the receiver is synthetic array of biconical antenna. The synthetic array antenna is formed by apositioner and a biconical antenna. The size of the array
antenna is 7 × 7 × 2. The reason why array antenna wasused is that the DoA can be estimated by array antenna.
The experiment result is obtained from vector network
analyzer. In this research, ultrawideband (UWB) signals was used because the time resoltion is very high.
The frequency band is from 3.1GHz to 10.6GHz, hence
the delay resolution is 0.13ns.

is longer than that of direct wave is considered to be
the delay time of a path. Each peak should be cut out
from the delay profile to avoid the interference fromother waves. The window function is used to cut out
the peaks from time delay profile. Here the delay timeof a path is estimated.
The signals of separated peaks are once Fourier transformed to obtain the frequency charateresitcs. The last
step of signal processing is beamforming. By using theFourier transform result of separated peaks, the DoA of
the waves can be estimated.
On the other hand, Sapce-Alternatin Generalized Experctation Maximization (SAGE) Algorithm is a wellused maximum likelihood based algorithm for angle anddelay estimation. Comparing the result of proposed algorithm and that of SAGE algorithm implemented byanother member of the group, the latter revealed to bebetter. Hence, the result by using SAGE algorithm wasused in data analysis.
2.3.1

Fourier Transform

Consider about the environment that there are L input
waves whose complex amplitudes are (s1 , s2 , ..., sL ), delay times are (τ1 , τ2 , ..., τL ). Then the output of antennaX(f ) isX(f ) =

LX

si exp(−j2πf τi )

(1)

i=1

2.3

It inverse Fourier transform is

Signal processing

Space-Alternating Beaforming (SABF) Algorithm is a
proposed algorithm to do propagation path estimeation[4]. The flow chat of proposed propagation path estimation algorithm is shown in Figure 4.

f (τ )=Z ∞X(f ) exp(j2πf t)df

−∞

=

Z ∞ X
L

si exp(−j2πf τi ) exp(j2πf t)df−∞ i=1=LX

si δ(τ − τi )

(2)

i=1

But, time delay profile is a function to δ only when
the integral interval is infinite in the frequency domain.
In the case of digital signal processing, the bandwidth
for integration is limited, so the function is mordified asfollows,

f (τ ) =2
Z f0 + ∆F

X(f ) exp(j2πf τ )df

2
f0 − ∆F

=

si

L
X

si ∆F exp(j2πf0 (τ − τi )sinc((τ − τi )∆F ))i=1

Figure 4: Flow Chat of Space-Alternating Beamforming(SABF)=2
Z f0 + ∆FLX

2
f0 − ∆F

exp(j2πf (τ − τi ))df

i=1

(3)
The data obtained from vector network analyzer isfrequency transfer fucnction. The first step of signal
processing is to obtain time delay profile after inverse
Fourier transform. Each of the peak whose delay time

76

where
sinc(x) =sin πxπx(4)Technical Report of International Development Engineering

2.4

TRIDE-2006-01, February 20, 2006 (ISSN 1880-8648)

Experiment Result

In this section, the experiment result is introduced.
First of all, the direct path is found in experiment result. The azimuth angle, elevation angle and the delay
time of experiment result is nearly as same as the theoretical value, calculated as direct wave. However, thepath gain of experiment result is less than the theoretical value, shown in Table 3. The considerable value isa part of array was shadowed by gantry.
Table 1: Experiment Result of Direct Wave

Azimuth angle[deg]Elevation angle[deg]Delay time[ns]Path gain[dB]experimentresult
156.2
37.6
21.64
-82.4

Figure 5: Experiment Result 1

theoreticalvalue
154.2936.1
21.84-64.11

Except the direct path, there are three major singlebounce paths were identified. These three major singlebounce paths are reflected from the roof of driving seat,
the sensor and the pole, respectively. The experimentresult of single-bounce paths is shown in Figure 5 andTable 3.
The method to identify a single-bounce path is introduced followed. Assume that there is one direction ofarrival has been estimated. If the reflection point canbe found in the direction of arrival, the distance between reflection point and receiver can be calculated.
By the same way, the distance between reflection point
and transmitter can be also calculated. Hence, the delay time is known. If the delay time of experiment result
is equal or very close to the theoretical value, a singlebounce path can be identified.
Table 2: Experiment Result of Single-Bounce Path
Reflection
point
AzimuthAngle[deg]Elevation
Angle[deg]PathGain[dB]

roof ofdriving seat170.0

sensor

pole

245.3

224.8

15.7

17.5

16.9

-88.0

-87.4

-86.5

On the other hand, if the delay time of experimentresult is longer than that of theoretical value of singlebounce path, the estimation result can be considered to
be a double or multiple bounce path. As the directionof transmission is unknown, then the double or multiple bounce path can not be uniquely identified. Some
double or multiple bounce paths are also found in theexperiment, which is shown in Figure 6.

Figure 6: Experiment Result 2

3

Computer Simulation

For comparison, a commercial simulation named Raplab
by Kozokeikaku Engineering Inc. [5] was used. Raplab
is ray-tracing simulator. Geometrical optics (GO) andgeometrical theory of diffraction (GTD) are deployed
for scattering calculation. Reflcetion on flat surface anddiffraction on edge are modeled [3, Page:745-773].

Figure 7: Simulation Result 1
The direct path is found in simulation result, shown in
Figure 7. The azimuth angle, elevation angle and delay
time of simulation result is nearly as same as those ofexperiment result. The path gain of simulation result77Technical Report of International Development Engineering

TRIDE-2006-01, February 20, 2006 (ISSN 1880-8648)

is close to theoretical value, greater than that of experiment result. The reason was explained previously.
Table 3: Comparison in Reflecion of Pole

Azimuth angle[deg]Elevation angle[deg]Delay time[ns]Path gain[dB]experimentresult
224.8
16.9
49.23
-83.82of simulation result is greater than that of experimentresult.
Curved surface is usually modeled in this way in raytracing simulation. However, it is cause great error,
which is proved in this research once more.

simulation
result
225.6
17.3
48.67
106.31The single paths reflected from the roof of driving seatand the pole are also found in simulation result, shownin Figure 8. the path loss of simulation result is greaterthan that of experiment result. The considerable reason
is modeling method of ray-tracing simulation.
Table 4: Comparison in Reflecion of Roof of Driving
Seat

Azimuth angle[deg]Elevation angle[deg]Delay time[ns]Path gain[dB]experimentresult
170.0
15.7
32.12
-88.82

Figure 9: Simulation Analysis

simulation
result
171.3
16.1
31.80
106.68

4

Conclusion

Experiment has been done to find the paths which causeinterference to the adjacent lane in ETC toll gates. Several dominant paths are identified.
On the other hand, simulation has also been done
for comparison. The simulator could predict the major paths accurately, but the path gain values were erroneous as the reflection from the curved surface wasmodeled by the edge diffraction at the polyhedren.
In order to improve the simulator, the reflection of
curved surface should also be accurately modeled bygeometrical optics.

References[1] Road Bureau ITS homepage.
http://www.mlit.go.jp/road/ITS/[2] K.Haneda, J.Takada, T.Iwata, Y.Wakinaka, andT.Kunishima, “Experimental Determination of
Propagation Paths for the ETC System - Equipment
Development and Field Test” IEICE Trans. Fundamentals, Vol.E87-A, No.11 Nov 2004.

Figure 8: Simulation Result 2

In the ray-tracing simulation, the curved surface was [3] Constantine A. Balanis, “Advanced Engineering
approximately modeled as polyhedren. As the result,
Electromagnetics,” John Wiley & Sons,Inc., 1989.
the reflected path in experiment becomes diffracted pathin simulation, shown in Figure 9. The path loss of [4] Don H. Johnson, Dan E. Dudgeon, “Array Signal Processing Concepts and Techniques,” P T R
diffraction is much more than that of reflection (usuPrentice-Hall, Inc., 1993.
ally order of 20dB weaker than reflection). In this research, the reflection points of main single bounce paths[5] Raplab Homepage.
are the roof of driving seat pole. All of these reflection
http://www.kke.co.jp/raplab/
points are on curved surface. Hence, the reflection happened in these reflection points became diffraction in
the computer simulation. As the result, the path gain78

Technical Report of International Development Engineering

TRIDE-2006-01, February 20, 2006 (ISSN 1880-8648)

Location Estimation for Wild Animals
Student Number: 04M18021

Name: Jun-ichi ABE

Supervisor: Jun-ichi TAKADA

野性動物の生態調査用位置推定システムの開発
阿部 順一
今日，様々な開発に伴う野性動物の生態環境の破壊が問題になっている．開発の事前と事後で野性動物の生態環境がどのように変化したか，動物の行動を追跡調査する手段が求められている．現在，動物に小型送信機を取り付け，
観測地点の周囲に八木宇田アンテナを備えた受信局を複数配置し，動物からの電波を受信，電波の到来方向を推定し，動物の位置を特定，追跡するシステムが存在する．しかし，電波の到来方向の推定を八木宇田アンテナの回転による電界強度の測定により行っているため，1 回の観測に時間がかかり，追跡精度が良くない．本研究では，アレーアンテナを使用した信号処理技術を用いて, 高速に方向推定を行うシステムの開発を行い, 屋外実験にて評価を行った.

1

Introduction

Today, there are a lot of environmental problems. One
such problem is the ecosystem of wild animals. Before
and after developments, for example river improvement,
there is a need to investigate the living area of wild animals. Telemetry system is one of the methods used
for tracing animals’ movement. A telemetry system
uses a small transmitter and attaches it to wild animals. More than one receiver stations with Yagi-Uda
antennas are set in the measurement field and the stations receive signals from the wild animals by rotating
Yagi-Uda antenna and are searching for the strongest
direction of electric field. Then these measured data
are collected and the location of animals are estimatedFigure 1: Test field : river (Chikuma river)by triangulation[1].
Target animals are small wild animals, for example
raccon dogs, rabbits, and fish. But it is difficult to
use the conventional for fast-moving animals like birds
System Design
because it takes more than two minutes to rotate the 3
Yagi-Uda antenna and search for its direction, and thetarget animals may move during this period. The au- The proposed system has the following characteristics.
thors have proposed a fast direction of arrival (DOA)• A small transmitter is attached to wild animals
estimation system for wild animals by using an array
antenna and signal processing. We have aimed at a fast
• More than one receiver stations which estimate
estimation of direction.
direction of signal arrival are set around the meaIn this paper, we first explain the system design andsurement field.
then describe the development of the receiver station• Wireless LAN network connects between receiverand the preliminary experiment to certain the perforstations and data collection PC.
mance of the system.

2• Radio frequency band is 144MHz to be compatible
with conventional system.

Measurement Environment

Figure 2 shows the whole system and the functions.

Telemetry system are required in the following fields.
• grassland

1. The transmitter radiates the signal.

• forest

2. Receiver stations detect the signal.

• river (Figure 1)

3. Receiver stations estimate DOA.

At a river, target animals are fishes and birds. In ourcase, birds live in sandbanks. The measurement field isabout a few hundred meters square because these target
animals do not move long distances.
In these fields, there are a lot of obstacles e.g. vegetation, and the signal is scattered, diffracted, and reflectedby them[2]. Therefore these environment make multipath propagation.

79

4. Receiver stations send the result to the data collection server using wireless LAN (IEEE 802.11b).
5. Data collection server receives the results.
6. Data collection server estimates the location ofwild animals.

Technical Report of International Development Engineering
Array antenna....
2. Receive the signal

TRIDE-2006-01, February 20, 2006 (ISSN 1880-8648)
1m 1m

Array antenna

2 elements HB9CV

1m 1m 1m 1m 1m....

PC Receiver
3. Estimation of DOA

1. Transmit the signal

4.Transmit the result
by using wireless LAN

Wild animals
attached a transmitter

PC

Receivertripodhight
1.5m

store room
(receivers inside)

8

Measurement field
Array antenna
....

PC

ReceiverFigure 4: 8 elements of array antenna

Signal from animals
PC
Wireless LAN signal
5.Receive the results
6.Estimaton of animal’s locationmust be in the range from −50dBm to −100dBm. Output signal level must be less than 250mV.

Figure 2: Proposed DOA system

4

5.3

Transmitter

The transmitter is the “MBFT-7A” which is a small sizetransmitter[3] manufactured by LOTEK.
This transmitter emits a pulsed signal to save battery
power at the frequency band at about 144MHz.

5

Baseband Amplifier

The output signal voltage of the receiver is less than
250mV, but maximum input voltage range of A/D converter is 10V for sufficient data precision, the output signal of the receiver shall be amplified. Since the output
channels of the receiver are 16, a 16ch precise amplifier
was fabricated (Figure 5).

Receiver station

The receiver station has an array antenna, 8 channel(ch) I/Q receiver, 16ch amplifier, synchronous sampling
unit and PC with A/D board and DOA estimation software as depicted in Figure 3.
Synchronous
sampling unit
PC

16ch
AMP

ReceiveroutputReceiverGain control
terminal

AD board

RF input
8

DA board

Figure 5: 16ch amplifier

coaxial cablearray antenna

Figure 3: Receiver station

5.1

Figure 6 shows an amplifier circuit for a single channel. This circuit is an inverting amplifier and the magnification of the amplifier is 39. Operational amplifier
OP37G was used. It has wide-band, low noise and precision characteristics.

Array antenna

We used the HB9CV type antenna for the array element, which is commonly used among amateur radio.
It consists of two linear antenna elements and is unidirectional in order to suppress the influence of multipath
from the rear of the array antenna.

5.2

Input 1K

39K

+12V

1

5

2

6



3 +

ReceiverBy-pass
condenser
0.1 F
Output74


The receiver is equipped 8 RF input channels (0-7ch).
This receiver has a common local oscillator because DOA
estimation algorithm requires the phase difference between channels. If each channel has an independent
local oscillator, phase information is lost. This receiverconverts the signal down from 144.700-144.900MHz to
DC-100KHz, and outputs the I/Q signals. According
to the specifications of the receiver, input signal level

80

1K
-12V

OP37G 8
By-pass
condenser
0.1 F

Figure 6: Amplifier circuit

50K

Technical Report of International Development Engineering

5.4

TRIDE-2006-01, February 20, 2006 (ISSN 1880-8648)

A/D converter and synchronous sam- The calibration matrix C can be written as·pling unitα0

C = diagexp(j(φ0 − φ1 )), · · · ,α1
The A/D converter board converts the output analog¸
signal from the 16ch amplifier to 14bit digital data. I
α0exp(j(φ0 − φM )) ,(4)
used a commercial A/D converter board “AD681-PCI”
αM
manufactured by Microscience.
where α0 , · · · , αM and φ0 , · · · , φM refer to as the signal
This A/D converter board has 16 channels but it does
not have a function of synchronous sampling because amplitude and phase associated at each array element.
it has only a single channel of A/D converter, and it
uses a multiplexer and samples all channels when A/D
Field test
converter has to sample more than one channel. An 7
optional unit “synchronous sampling unit (SHU-516)”
is available and between amplifier and A/D converter Field test was held at Public Works Research Institute(PWRI). A photo of the actual measurement field isboard, it can realize pseudo-synchronous sampling.
shown in Figure 7.

5.5

DOA Estimation Algorithm

There are several types of DOA estimation algorithms.
Among them, beamformer and MUSIC algorithm werechosen.
Beamformer algorithm is the most basic DOA estimation algorithm. It is equivalent to the Fourier transformof the array response. This algorithm does not provide
super-resolution, but this algorithm may be more robust than subspace-based algorithms such as MUSIC, if
the measurement field is a multipath environment.
MUSIC algorithm is a well-known subspace-based superresolution DOA estimation algorithm. If the measurement field is open and multipath is negligible, superresolution algorithm can estimate more precise than beam
former algorithm. However if the coherent signals e.g.
Figure 7: Test Field
multipath waves arrive, the spatial smoothing preprocessing(SSP) scheme should be introduced to decorrelate the signals[4].
We set the 7-element array antenna and a transmitter as Figure 8 since one channel of the receiver was
broken at the field test. When the broadside direction
6 Calibrationof the array antenna is set as 0 degree, we measured
Array output vector from M -element array antenna can the signal from a transmitter in 7 directions, namely,−60, −40, −20.0, 20 40 and 50 degrees. The distancebe modeled as
between Tx and the center of the array antenna is 40m.
x(t) = ãs(t) + n(t).
(1)-20where ã = Ka, s(t) is an arriving signal with arrival
angle θ, n(t) is an M × 1 noise vector, a is a steeringvector which is expressed as the equation below.
·a(t) = 1µ¶2πd sin θ
exp −j
λ

0

20

-40

40
50

-60

40m

···

¶¸T
µ
2πd sin θ(M − 1).
exp −jλ(2)
0d is distance between each antenna element. K is an
M × M error matrix which arise for the impairment of
RF channels. The errors cause the phase and amplitude
mismatch between channels.
Then the errors have to be cancelled by calibration
techniques. The calibration matrix C is defined as C =K−1 [5].
If the calibration matrix C is applied the measured
signal, the calibrated signal can be denoted byx̃ = Cx(t) = Cãs(t) + Cn(t).

(3)

81

...

40m

Array antenna

Figure 8: Arrangement measurement

7.1

Level diagram

Figure 9 is the level diagram of this measurement. It
shows the receiving power margin is 55dB.

Technical Report of International Development Engineering

EIRP
1.6 dB
Path loss
L dB

8ch

-80

I/Q
Receiver

Cable
loss
2dB

Azimuth(degree)
0
0
20

-20

40

60

80

-5
Music
-10

-15
Music with SSP

Link margin-20-75dBmRx antenna Input level
Gainof receiver
6dB(5.6 - L)dB

-25

Figure 10: MUSIC spectrum
Receiversensitivity

References[1] M. Denda, K. Shimatani, J. Kukita and S. Iwamoto:“Development of Multi Telemetry Sytem for Monitoring ecosystem of wild animals”, Public works research institute.

Measurement result

Measurement results are shown in Table 1. The 0 degree
measured data were used as the calibration data The
errors between actual angles and estimated angles areless than 3 degree except -60 degree case. In −60 degree
case, the estimation error was the biggest. It seems thatthe error is due to the directivity of HB9CV. A HB9CV
has 3dB beamwidth of ±50◦ , and the antenna is notsuitable for estimating angles outside this range.
The dynamic range of the MUSIC spectrum is about
10dB without SSP as shown in Fig 10. But if SSP is
applied, it is improved 20 dB. It seems that error ofmeasurement settings e.g. location of array element israndamized by SSP. Detail investigation is required.
Table 1: Measurement result
MUSIC
MUSIC with SSP
Tx point Estimation
Estimation(degree)(degree)(degree)-60-52.91-52.87-40-39.63-39.64-20-17.59-17.82
20
18.14
18.06
40
38.00
37.44
50
48.64
48.03

8

-40

-20

Figure 9: Level diagram

7.2

-60

Intensity of spectrum(dB)

T
r
a
n
s
m
i
t
t
e
r

Transmit of
ATT
power
15dB
17dBm
+
connector
loss

TRIDE-2006-01, February 20, 2006 (ISSN 1880-8648)

Conclusion

The DOA measurement system for real time tracing ofwild animals’ movement was built and was checked inexperiment at the open space. This system can not set
permanently. And it is required the many improvements
e.g. automatic calibration and handling of multipath
environment. But it is the first time to show the posibility of real time tracing of wild animals’ movement.

82[2] NC Rogers: “A Generic Model of 1-60GHz Radio
Propagation through Vegetation - Final Report”,
QinetiQ, 2002.
[3] Lotek Fish & Wildlife Monitoring Systems, “MBFT
Pulsed Radio Tags”
http://www.lotek.com/mbft.htm[4] N. Kikuma: “Adaptive signal processing using array
antenna”, Science and Technology Publishing Company Inc, 1998.
[5] G. Sommerkorn, D. Hanpicke, R. Klukas, A.
Richter, A. Schneider, R. Thoma, “Reduction of
DOA estimation errors caused by array antenna imperfections,” in 29th Europian Microware Conference, Oct. 1994.

Technical Report of International Development Engineering

TRIDE-2006-01, February 20, 2006 (ISSN 1880-8648)

Investigation of the Wave Scattering Characteristics by using
Physical Optics Approximation
Student Number: 04M18297 Name: Navarat LERTSIRISOPONSupervisor: Jun-ichi TAKADA
Abstract
The structure of some scatterer objects in the propagation channel such as signboards and metallic plates are modelled to examine the effects of scattered fields
or waves at the observer point. The objective of my research is to utilize Physical
Optics (PO) approximation to investigate in more detail the characteristics of wave
scattering using a simulation model and to predict the radio wave scattering characteristics. Moreover, polygon meshes are introduced to model scatterer constructions
including 2D and 3D geometrical objects and to simplify the complex calculation of
the induced current for examining the scattered field. This approach is called “POusing polygon mesh”.

1

Introduction

tions from the source Ei and from scattered field Es
which can be determined by the equivalent electricand magnetic surface currents I and M respectively
on the surface S [4].

Propagation mechanisms in urban areas are basically wall reflections, building edges and roof diffractions. Some measurement results however show thatscattering from some objects in the environment canhave strong impact on the urban propagation channel [1]. Careful analysis of these results reveals thatthese scattered objects, which can be any surrounding metallic object, such as signboards, street lights,
traffic lights and traffic signs, are involved in transferring transmitted signals to the receiver [2].
One of these propagation mechanisms is called
scattering, which can be calculated from the electromagnetic fields on the scatterer surface. In thecase of a conducting body, the induced currents on
the surface must be determined or approximated inorder to compute the electromagnetic fields scattered from the scatterer. In [3], PO approximation
is utilized to simulate the induced surface current tohandle non-specular scattering. The simulation results showed good agreement with the experimental
results; therefore, these led the author to continue
further studies about the scattering from surrounding objects in urban areas by utilizing the PO approximation method.

2

E= Ei + Es= Ei − jωµA − j∇∇ · A− ∇ × B (1)ωεwhere,
A

=

B

=

Z
e−jkr
1
I
dS
4π S
r
Z
1
e−jkr
M
dS
4π S
r

(2)
(3)

are electric and magnetic vector potentials and r is
the distance between the integration point and theobserver. Time-harmonic wave is assumed and ejωtomitted. Furthermore, ε and µ denote the permittivity and permeability of free space, respectively,
whereas k = 2π/λ is the propagation constant infree space.
In PO approximation, the induced electric current is approximated as the scatterer is replacedby an infinite ground plane, which is tangential to
the surface of the scatterer at the point of interest. When the scatterer is a perfect electric conductor (PEC), then the simple image theory is applied.
Only the tangential component of magnetic field isdoubled, while the normal component is cancelled.
The equivalent electric current I is given by 2n̂ × Hi
on the illuminated part of the surface Sl while on
the shadowed part Ss of the scatterer, the current
I is zero, Hi is the unperturbed incident magnetic
field. For PEC, M is always 0, as the tangential

Physical Optics Algorithm

PO is a type of high frequency approximation
method, meaning the surface of the object is muchbigger than the wavelength of the signal. From thefield equivalence theorem, the field at an observation
point P is exactly expressed as the sum of contribu-

83
1Technical Report of International Development Engineering

TRIDE-2006-01, February 20, 2006 (ISSN 1880-8648)

3. Rearrange all triangular meshes matrix to calculate the normal vector (n) at the center point ofeach triangular mesh by defining two vectors, C andD, from 3 points (P1 , P2 and P3 ) of each triangle
which is described below.

electric field vanishes on the PEC surface. Then
IP O
MP O

= 2n̂ × Hi for illuminated part Sl ; (4)= 0(5)In this case, the field in PO is simplified asE=∇∇ · AE − jωµA − j
ωε
i

(6)
normal vector

Furthermore, if the observer P is in the far field region of the scatterer, the second term of the scattering field just eliminates the radial component of thefirst term and the electric field is expressed by using
the unit vector r0 towards the observer as follows:E3= Ei − jωµA × r̂0 × r̂0

3.2

(7)

P3 − P1
C×D|C × D|n=(8)

Three-Dimensional Geometry

CircleHemi − Sphere

Figure 2: Half sphere produced from circular disk
According to this characteristic, not only thecomplex scatterer shapes can be represented but thesurface integration can also be simplified as the summation of each small area when the the size of eachtriangle mesh is suitable and small enough. Therefore, the surface integration can be represented as
the small area summation which is:

Two-Dimensional Geometry

By using a toolbox in MATLAB, the following sequence covers the steps to generate the triangulation
and applied in the PO algorithm.
1. Open a drawing tool to draw the basic 2D geometrical objects (circle, rectangle, ellipse or polygon) as shown in Fig.1.

A =B

CircleD =To generate the triangulation in 3D geometrical objects, the author mapped the triangulation of 2D
geometrical objects by adding the height as shownin Fig. 2, while the other sequences are still thesame as described in subsection 3.1.

Polygon Meshed Method

SquareP2 − P1

4. Substitute the normal vector (n) in the PO
algorithm to obtain I and get the scattered field.

To represent the data structures of scatterers
and simplify the calculation, the scatterers should
be modelled by polygon structures. Although there
are a variety of algorithms available to generate thiskind of structure, the triangulation of a polygon is
utilized in this research since the curved surfaces
being subdivided into triangles can be handled efficiently. The triangulation algorithm is a fundamental operation in computational geometry under theassumption that the polygon is simple, i.e., that thevertices of the polygon are the only points of theplane that belong to two edges, and that no pointof the plane belongs to more than two edges.

3.1

C =

=

1 X e−jkrI∆s4πr
1 X e−jkr
M
∆s
4π
r

(9)
(10)

Moreover, to detemine the appropriate size of thepolygon mesh, a polygon mesh ratio defined by thefollowing relationship was used.

Ellipse

Polygon Mesh Ratio =Figure 1: Varieties of scatterer shapes in 2D geometry4

2. Initialize the triangular mesh which consistsof a Point matrix, an Edge matrix, and a Triangle
matrix. In the mesh, minimal regions are triangulated into sub domains, and border segments andboundary segments are broken up into edges.

avg(polygon area)
λ2

(11)

Simulation and discussion

To evaluate and demonstrate the effectiveness ofusing polygon meshes applied in PO, the following
simulation parameters were conducted with simulation conditions shown in Table 1.
84
2

Technical Report of International Development Engineering

TRIDE-2006-01, February 20, 2006 (ISSN 1880-8648)

ratio =1.22

y (m.)

0.1

0

−0.1
−0.1
0.1

0
x (m.)
ratio =0.08

0

−0.1
−0.1

0.1

0
x (m.)

0

−0.1
−0.1
0.1

y (m.)y (m.)

Square0.09 m. x 0.09 m.
5.2 GHz
20 meters
40 dBm60◦
30◦
210◦
Parallely (m.)

Scatterer shape
Size
Frequency
Observer distanceTransmitted power
Incident θi
Incident φiScatterer φs
Polarization

ratio =0.30

0.1

Table 1: Simulation parameters

0.1

0x (m.)
ratio =0.02

0.1

0x (m.)

0.1

0

−0.1
−0.1

Figure 4: Varying polygon mesh ratio in squareplate
θi=60, φi=30

Magnitude of scattering field [dB]

0

−30

−60

−90

−120
−90

Figure 3: Plane wave scattering from a square plate

ratio =1.22
ratio =0.30
ratio =0.08
ratio =0.02

−60

−30

0
θ [degree]

30

60

90

Figure 5: Scattering field corresponging to polygon
mesh ratio using PO polygon mesh

Figure 3 shows the scattering of a plane wave by
a rectangular plate sized a × b in the x-y plane. The
incidence propagating in K̂i is coming from (θi , φi )and has the parallel polarization (only θi component) while the observer is in the direction of K̂d or(θ, φ).
Figure 4 illustrates how the polygon mesh method
can construct the scatterer when the size of eachpolygon mesh is varied by the polygon mesh ratio
and Fig. 5 illustrates the magnitude of scatterer
fields from the rectangular plate with respect to theelevation angle at the observer point. From thesefigures, it can be seen that when the polygon meshratio decreases, the sidelobe also decreases. However, all of them still can construct the signal mainreflection beam. As a result, this can be inferredthat the signal sidelobe alters proportionally to thepolygon mesh ratio.
However, to justify whether the polygon meshmethod can be appicable in PO Approximation, we
need to compare the results with the PO analytical or conventional model as described in [4]. From
this reason, the comparison between PO using polygon mesh method and PO analytical method is illustrated in Fig. 6. A high accuracy for both PO casesin the direction of main radiation (θ = 60◦ ) is observed. This reveals that the PO polygon mesh canperform as well as the PO analytical one. Since thecharacteristics of PO treats only the portion of thescatterer that can be observed by the source (illu-

minated portion), the simulated scattering field will
deviate from MoM as the observer moves away fromthe illumated portion and into the shadowed region.
In the real environment, not only the simple construction shape can represent all the obstructions in
the channel model, for example, traffic light and its
pole, car, etc., the 3D objects should also be simulated in order to implement this algorithm in thereal propagation measurement. Therefore, the simulation of the finite cylinder and sphere, which arecommon 3D objects, were conducted. Nevertheless,only the analytical solution of the scattering from asphere [5] is known so that PO using polygon meshfor 3D geometrical cases can be evaluated by comparing its output with this analytical result.
The structure of sphere is modelled whose radius
is 5λ (0.2885 m.) and simulated under the condition
that frequency is 5.2 GHz and the incident plane
wave impinged at the bottom of the sphere (−z axis)
and with the observer at φ = 0◦ , as shown in Fig
7. In simulating the scattering field, only half of thesphere was used, since in PO, only the illuminatedpart can be seen which corresponds to half of thesphere centered on the incident wave. To evaluate
the accuracy of this approach, the simulation is conducted and compared with the analytical model asshown in Fig.8.

85
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Technical Report of International Development Engineering

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θi=60, φi=30

Scatterer Fields of the Perfectly Conducting Sphere
10−30

PO polygon mesh
PO analytical
MoM

Magnitude of scattering field [dB]

Magnitude of scattering field [dB]

0

−60

−90

−120

−150
−90

−60

−30

0
θ [degree]

30

60

−10
−20
−30
−40
−50
−60
−70

90

Figure 6: Comparing scatterer fields of PO using
polygon mesh method with PO analytical model and
MoM

Analytical Model
PO polygon mesh

0

100

120

140
θ [degree]

160

180

Figure 8: Comparison of the scattered fields fromPO polygon mesh and analytical model
ically accurate method of moments (MoM) in the2D geometrical case. For the 3D geometrical case,the analytical solution of the sphere is used to verify
the accuracy of this approach. From the results ofboth 2D and 3D cases, PO analytical and PO using
polygon mesh have great agreement with each other;
however, they can perform high accuracy only in theregion of main direction and is slowly degraded in
the shadow region as a result of PO’s simplification.
Therefore, further investigation should be considered to enhance this approach for utilization in thereal environment.

Figure 7: Plane wave scattering from a sphere

References[1] Mir Ghoraishi, Jun-ichi Takada, and Tetsuro
Imai, “Identification of the Scatterers in the
Urban Microcell Environments,” Technical report of IEICE, WBS2004-164, AP2004-345,
RCS2004-432, MoMuC2004-215, MW2004-342(2005-03).

The well-known characteristic of PO, in which
the acccuracy is expected in the region of main direction but degraded in the shadow region was observed in both 2D and 3D geometrical cases. Moreover, a polygon mesh ratio of 0.1 is sufficient for the
scattering field to converge.

5[2] Mir Ghoraishi, Junichi Takada and Tetsuro
Imai, “Investigating Dominant Scatterers in Urban Mobile Propagation Channel,” IEEE International Symposium on Communications andInformation Technologies 2004 (ISCIT 2004),
Oct., 2004 (Sapporo, Japan).

Conclusion

This study introduced the polygon mesh method
applied in PO approximation not only to model thesurrounding objects but also to simplify the complex
calculation of the induced current in order to examine the scattered field. This approach was called“PO using polygon mesh”.
Simulations of the scattered field from 2D and
3D geometrical objects by either varying the incident directions or varying the observer directions
were conducted to evaluate and demonstrate theeffectiveness of polygon meshes applied in PO approximation. The relationship between signal wavelength and average area of polygon mesh called “Polygon mesh ratio” is also stated to indicate the proper
size of polygon mesh providing a reasonable scattered field.
Furthermore, this approach is verified by comparing it to the PO analytical model and the numer-[3] Hary Budiarto, Kenshi Horihata, Katsuyuki
Haneda, and Jun-ichi Takada, “Experimental
Study of Non-specular Wave Scattering from
Building Surface Roughness for the Mobile Propagation Modeling,” IEICE Transactions on
Communications, vol. E87-B, no.4, pp. 958-966,
Apr. 2004.
[4] I. Yamashita, Eikichi, “Analysis Methods forElectromagnetic Wave Problems. - 2Rev.ed,”
Artech House Inc.1990.
[5] Nagayoshi Morita, Nobuaki Kumagai, Joseph R.
Mautz, “Integral Equation Method for Electromagnetics” Artech House Inc, 1990.

86
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Sorption and flushing characteristic of heavy metal ion response to sandStudent Number：04M18015

Name：Masatoshi AOKI Supervisor：Hideki Ohta

砂質土に対する重金属イオンの吸着洗浄特性青木雅俊

社会環境の変化と土壌汚染対策法が施行されたことにより、安価な地盤浄化技術の開発がいっそう強く求められている。そこで、本研究では、「小規模でありながらも経済的な原位置での汚染地盤浄化技術の実用化」を目的として、汚染された砂質土の吸着浄化実験を行った。東京都大田区の砂を用いて、粒度分布を求め、粒径が小さい粒子が土粒子全体の表面積のほとんどを占めていること示した。その後、砂質土の汚染物質に対する吸着・洗浄特性について調べた。

Therefore, the majority of contaminants stay in finesoil particle’s surface area. Eliminating fine soil
particles, majority of contaminants can be eliminatedfrom the contaminated ground with relatively small
cost.
The following is the concept of soil wash system inthis study.
Fig. 2-1 shows that contaminant soils exist in the
sandy ground.
Fig. 2-2 shows that a cylinder is set on the groundand a hole is drilled into ground surface area. During
drilling, water is filled in the hole; this action means
not to collapse the side wall of hole.
Fig. 2-3 shows that the soil particles and water withcontaminant is stirred in the hole. In this time,
contaminants adhere to the surface area of soil
particles because contaminants and soil particles haveelectric charge.
Fig. 2-4 shows that the hole is left for certain amountof days. Finally, the soil particles sedimented asshown in Fig. 2-5.
Fig. 2-6 shows that fine soil particles in the upper
part are taken away after sedimentation, lots ofcontaminants are eliminated.

1 Introduction
It has been two years since soil contamination
countermeasures law becomes effective. The purposeof this law is to protect the citizen’s health. The mostimportant change of this law is responsible. Before
2003 February, the responsible was usually the person
who contaminates lands, however now the responsible
is the person who owns the land.
The influence of this law, when small and medium
size companies close their factories due to economic
difficulty, companies must clean the land, if their landis contaminated. However, the cost is so high that they
can not sell their land. As a result, the land remains
unused. Because of this reason, to clean more cheaplyis necessary. Therefore cheap soil wash system inpractice is needed. In Ohta Lab., Suga(2005)
developed in-situ wash system which is economicaland small in scale. In this study, he converted a part ofexisting boring machine which can excavate by wayof running water from tip and circulate stirred water.
In this study, sieve test and sedimentation analysis iscarried out and the relationship between grain size andsurface area on soil is calculated. The result of
sorption and flushing experiment is carried out toknow the condition when soils and water are stirred.
In this experiment, Bio-surfactant is used. The effectis considered
2 Concept of soil wash system
The soil wash system used in this study focuses that
contaminants adhere to surface area of soil particles.
The soil wash system eliminates only fine soil deposit.
Because fine soil particles consist of only small
fraction of total soil weight, it is very easy to eliminate.
Fine soil particles consist most of soil surface area.
87Technical Report of International Development Engineering

TRIDE-2006-01, February 20, 2006 (ISSN 1880-8648)

size sands consist most of surface area in sand.
Surface area of fine grain size sands whose diameter isless than 0.1mm are 70% of all soil particles although
the weight of fine sands are on the about 10% of total
weight of all sands.

Sand layer
Ground water level

the percentage of soil through(%)

100

contaminantFig. 2-1
Initial condition

Fig. 2-2
Drilling into ground

80
60
40
20
0
0.001

0.01
0.1
1
10
diameter (mm)Fig. 3-1 the result of grain size distribution
the percentage of surface area among each grain size
0
10
20
30
40 %

Fig. 2-3
Stirring

grain size
0-0.0038
0.0107-0.0038
0.0151-0.0107
0.026-0.0151
0.0407-0.026
0.0567-0.0407
0.075-0.0567
0.106-0.075
0.25-0.106
0.425-0.25
0.85-0.425
2-0.85
4.75-2
9.5-4.75
19-9.5

Fig. 2-4
Leaving for a certain period

Take off fine soil particle

Fine particles

Divided number

50
100
200
300

The percentage
soil throughFig. 3-2 the relationship between surface area ofsand and grain size

Coarse particles

3

Fig. 2-5

Fig. 2-6

The shape of
sedimentation

Eliminating fineparticle soils

1. Divide amount equally from A to
B by
N
B

y(b)

y(a)+⊿w
y(a)

•

S(1)
A
a ⊿r ⊿rb

grain size

A and B mean the result of grain
size distribution.
area of soils which
S ( k ) Surface
diameter is from a+⊿r×(k-1) toPhysical property of sand

2. Calculate surface area S(k) in eachgrain size zone to use following
equations.
All soil particle is calculated
as a sphere.

3. If the value of N is big enough, thevalue S(k) becomes true value.
4. Surface area of soil grains ( S all )which diameter is from A to B are
possible to calculate.

a+⊿r×k.

The sand is taken at Ohta district where small andmedium size companies exist.
Grain size
distribution and surface area of sands are investigated.
Fig. 3-1 shows the result of grain size distribution.
Fig 3-2 shows the relationship between surface area ofsand and grain size. Surface areas of sands arecalculated by using the concept shown in Fig. 3-3.
In the concept shown in Fig.3-3, the author assumed
that the soil particles are plain spheres. Fine grain

S all

Surface area of soils whichdiameter is from A to B.

4π L2

Average of diameter

L = a + ( k − 0.5) Δ r S ( k ) = Δ W 4

Weight per one particle4
π L3 ρ
3

Surface area per particle

4π L2

=

=

πL ρ
3
y ( a ) − y (b ) 3
NLρ3y ( a ) − y (b ) 4π L2
4N
π L3 ρ3

N

S all = ∑ S ( k )1Fig. 3-3 The concept to calculate surface area88Technical Report of International Development Engineering

4

TRIDE-2006-01, February 20, 2006 (ISSN 1880-8648)

Table.4-1 the result of investigations of contaminants
MinimumMaxelement
resultconcentration concentration

Sorption and flushing characteristics of heavy
metal to soil particles

Before the experiments, contaminants in the sandused in this study are investigated by ICP shown in
Fig.4-1. Table. 4-1 shows the result of investigationsof contaminants in the sands. It can be seen from
Table.4-1 that value of contaminants in the sands are
extremely small. In this study, the author assumes
that there are no contaminants in the sands.
Therefore, to investigate the characteristic of sorption
and flushing the sands are contaminated by Cu, Zn, Pb,
and Cd. Four contaminants selected in this study(1)
sorption experiment
The process of sorption experiment is following,
1. Water, contaminants and soils in bottle is put.
The table.4-2 shoes amount of water,
contaminants and soils.
Fig.4-2 shows thebottles in water, contaminants and soils.
2. The bottles are shaken as shown Fig.4-2. During
shaking contaminants adhere to soil grain surfacearea.
3. Contaminants which adhere to soil grain surface
area measured using ICP at 1, 2, 4,6,8,10,16 days.
Fig 4-3 shows that the relationship between
concentration of sorption and time and amount ofsorption becomes constant values.
This shows that all of cases the concentrations ofsorption experience were became equilibrium in sevendays. The most absorbent material was Pb, second was
Cd, third was Cu the last was Zn.

Si○26.209104.836

As

×

0

0.051

Hg

×

0

0.017

Cr

×

0

0.006

Co

×

0

0.008

Mn

○

0.042

0.167

Fe

○

1.604

6.416

Zn

×

0

0.002

Ni

○

0.008

0.033

Cu

○

0.016

0.063

Cd

×

0

0.033

Mo

×

0

0.009

Pb

×

0

0.072

Ag

×

0

0.007

Table 4-2
Amount of water, contaminants and water
Water
1ℓ
Cu
20×10-3mol
Cd
20×10-3mol
Zn
20×10-3mol
Pb
20×10-3mol
Soil
500g

(2)
flushing experiment
The process of flushing experiment is following.
1. Water contaminated sands which were used insorption experiment and Bio-surfactant are put inbottles. Table. 4-3 shows amount of water,
contaminated soil and Bio-surfactant.
2. The bottles are shaken as shown Fig.4-2. During
shaking the contaminants leave from surface area.
3. Contaminants which adhere to soil grain surface
area measured using ICP at 3,17th hours 1, 2, 4, 5,
6,7th days
Fig. 4-4, 5, 6, 7 shows the relationship between theweight of flushing contaminants and time. The
concentration of Cd and Zn became equilibrium in
one day.
The concentration of Pb became
equilibrium in two day. However the concentrationof Cu did not become equilibrium.
From theseresults, the more concentration of Bio-surfactant, themore contaminant dissolved out.

Concentra ion
sorption(%)
percentage
of ofsorption(％)

Fig. 4-2 bottles and shaker
60
50
40

Cu
Zn
Pb
Cd

30
20
10
0
0

5

10
time (day)Concentration of sorption=
present concentration of solution
1initial concentration of solution

Fig. 4-3 the result of sorption experimentFig. 4-1 ICP
89

15

Technical Report of International Development Engineering

TRIDE-2006-01, February 20, 2006 (ISSN 1880-8648)

weightWeight ofofflushing
Pb in solution
Pb (mg) (mg)Table. 4-3
amount of water, contaminated soils andconcentration of Bio-surfactant
Water
0.6ℓ
Contaminated soil
300g
Bio-surfactant
0mg/ℓ
5 cases
5mg/ℓ
20mg/ℓ50mg/ℓ
100mg/ℓ0mg/l
5mg/l
20mg/l50mg/l
100mg/l

0.1

5

In this study, sorption and flushing characteristics ofheavy metal soil particle are investigated to put into
practice for n e w s o i l w a s h i n g s y s t e mdeveloped by Suga(2005).
Throughouts o r p t i o n t e s t , all of cases the concentrations ofsorption experience were became equilibrium in sevendays. The most absorbent material was Pb, second was
Cd, third was Cu the last was Zn.T h r o u g h o u t
f l u s h i n g t e s t , The concentration of Cd and Zn
became equilibrium in one day. The concentration of
Pb became equilibrium in two day. However theconcentration of Cu did not become equilibrium.
From these results, the more concentration of
Bio-surfactant, the more contaminant dissolved out.

100mg/l

0mg/l

0.05

Reference
1)

0
0

1

2

time (day)小 澤 英 明 (2003):
土 壌 汚 染 対 策 法
pp.16-17
2) 佐藤雄也，土と基礎(2004): 土壌汚染とその対策～土壌汚染対策法の施工から 1 年余が経過して～,土と基礎 vol.9 pp.2-33) 平田建正，土と基礎(2004): 地盤環境汚染のメカニズムの解明から最新技術開発まで
vol.10 pp3
4) 浅見 輝夫, 「日本土壌の有害金属汚染」
pp.17-21
5) Asami,T.(1997): Cadmium pollution of paddy
fields and human health in Japan ;in
Biogeochemistryof
Trace
Metals,(Adriano,D.C.,Chen,Z-S.,Yang,S-S, and Iskandar,
I.K.eds.),
pp.217-264,Science
Reviews,
Northwood.
6) 社団法人 地盤工学会(2002): 土壌･地下水
汚染の調査・予測・対策 pp.3、 pp.9-127) 菅 良一(2005): 汚染された砂質地盤の原位
置攪拌洗浄 東京工業大学卒業論文
8) 財団法人 地盤工学会(2000): 土質試験の方法と解説(第一回改訂版)
9) Kyoung-Jin
Hong(2000),ApplicationofPlant-Derived Biosurfactant to Heavy Metal
Removal from Fly Ash and Soil, doctor thesis,
p66-p87
10) Ta Thi Thao(2005), heavy metal content inroadside deposits collected in Tokyo, JAPAN andHANOI, VIETNAM: A CASE STUDY , Drarchitect3

weightin solution(mg)Weightofof Cd
flushing
Cd (mg)Fig. 4-4 the result of Pb in flushing experiment
0mg/l
5mg/l
20mg/l50mg/l
100mg/l

0.14
0.12
0.1

100mg/l

0mg/l

0.08
0.06
0

1

2

time (day)3

Weight ofZn (mg)weightofflushing
Zn in solution(mg)Fig. 4-5 the result of Cd in flushing experiment
0.07

0mg/l
5mg/l
20mg/l50mg/l
100mg/l0.06
0.05

100mg/l
0mg/l

0.04
0.03
0

1

time (day)2

3

Fig. 4-6 the result of Zn in flushing experimentweightofflushing
Cu in solution(mg)Weight ofCu (mg)Conclusion

0.1

0mg/l
5mg/l
20mg/l50mg/l
100mg/l

100mg/l

0.05

0mg/l

0
0

1

time (day)2

3

Fig. 4-7 the result of Cu in flushing experiment90

Technical Report of International Development Engineering

TRIDE-2006-01, February 20, 2006 (ISSN 1880-8648)

POSSIBLE MECHANISM OF HYDRAULIC FRACTURING INITIATION
Student Number:04M18140 Name:Emiko TAKAHASHI Supervisor: Hideki OHTA and Pipatponsa THIRAPONG

ハイドロリックフラクチャリングの発生機構に関する基礎的研究
高橋笑美子
ハイドロリックフラクチャリング(HF)はダム堤体に亀裂を生じ水が浸透する破壊現象であるが，その発生機構は未だ解明されておらず，精密かつ実用的な安全評価法が存在していない．実験的結果によると正しいとされる Seed の HF 発生基準によっては壊れてもおかしくないと評価されたダムのほとんどは破壊せず立っていることも矛盾点である．本研究ではまず，HF と破壊機構において共通点を持つ八王子の斜面崩壊の例を取り上げ，斜面下の低透水層の持つ特性を調べ亀裂ではなくヒービングが起こったことを証明した．また，異なる土の異なる条件下で透水破壊実験を行い HF 発生の傾向を評価した．

1

failed in earth dam history.

Introduction

Hydraulic fracturing (HF) is a failure mechanism inwhich water pressure generates a formation of crack in
low permeable layer of soil, followed by water seepage.
Even though dam’s HF is a big problem, no precise,practical safety evaluation method based on HF exists
today.
This is because the details of fracture
morphology are poorly known. Previous researchers
have observed that when water pressure becomes
greater than minimum principal stress, vertical cracks
form and seepage failure occurs. However, many
dams in Japan that were judged “dangerous” by this HF
evaluation method have not failed and still stand today.
Apart from dam, there was failure case sharing thesame mechanism. An excavated slope failed after
heavy rainfall. It was analyzed that low permeable
layer was uplifted by the rise of water pressure in sandlayer beneath, but there was no evidence of water
spouting nor vertical cracks.
The objective of this study is to investigate further
the failure mechanism of the slope and to observe
initiation of HF to seek for trend of its mechanism. In
order to do so, close investigation on properties ofslope site soil was conducted. Then, seepage failure
experiment was carried out for different states anddifferent types of soils, simulating the slope site andboundary of dam’s core material and sand.

2

Background and previous studies

2.1 Hydraulic fracturing incidents
On June 5, 1976, Teton dam in Idaho, USA,suddenly broke down at the stage of first filling of thereservoir as shown in Fig.1.
Piping holes that werediscovered on the downstream side surface of the dam
body enlarged drastically in few hours as the water
overflowed, which then led to the vanishment ofnearly the complete dam body. It was a significant
event for earth dam geotechnical engineers, because
no dam of such a height (about 90 m) had previously

Fig.1 Breaching of Teton dam

2.2 Proposed mechanism of HF
After the Teton dam failure, H.Seed and J.Duncan(1976) proposed different criteria for HF initiation.
Δu > σ 3 + σ t(1)Seed’s criterion:
Duncan’s criterion: Δu > σ 1 + σ t(2)where Δu is the increase of pore water pressure, σ1
the maximum principal stress, σ 3 the minimum
principal stress, andσt the tensile strength of soil. σt
is small to be often neglected.
Fig.2 shows dam body in three dimension. Dam isusually considered that σ z is largest, σ x is about
half as much as σz, which is nearly equal to σy.
Cracks form in planes perpendicular to each stress. If
the effective stress σ’y becomes 0 or negative, thenvertical crack forms on up-down stream direction plane,
which is the most critical plane for HF since water caneasily penetrate into the crack and seepage failure may
begin.
What is minimum or maximum principal stress in asoil varies corresponding to the state of the soil.
Referring to Fig.3, in K0<1 state (such a condition isusually normally consolidated(NC)) where verticalstress σ ｖ is greater than horizontal stress σ ｈ ,according to Seed’s criterion when the water pressure
becomes larger thanσｈ, vertical cracks form and water
penetrates into a plane perpendicular toσh, where K0 isdefined as

K0 =

91

σ h'
σ v'

(3)

Technical Report of International Development Engineering

TRIDE-2006-01, February 20, 2006 (ISSN 1880-8648)

On the other hand, in K0>1 state, (such a condition isusually overconsolidated(OC)) when water pressure
becomes greater thanσｖ , horizontal cracks form andwater penetrates into a plane perpendicular toσv.

uplifted the loam layer as shown in Fig.6. In
conjunction, the area softened by excavation slipped.
Questions remain though, that if the failure was due
to water pressure, why did no vertical cracks form nor
evidence of water passage exist? According to
Seed’s criterion, vertical cracks must have formed
before such a heaving phenomenon.

Vertical crack plane ③

σz

Coefficient of Permeability
Loam : 1.0×10-6 (cm/sec)
Sand, Gravel : 1.0×10-3 (cm/sec)σy

σxHorizontal crack plane ①

Overburden pressureA

105 kN/m2

Vertical crack plane ②
σx (total stress in up-down stream direction)
σy (total stress in dam axis direction)σz (total vertical stress)

S

Most criticalwater path forseepage failureG

AP：130m
×

AP
135m
×

S

×AP：120m

HF when

HF whenu is larger than σ 1

σ1

u

σ3

K0 > 1

vertical crackσ1

σ1Previous studies mostly involved cylindrical or
cubical specimens, tested under triaxial conditions, inwhich a small hole allowed the application of waterpressure. They compared the pressure necessary to
fracture the specimen with the minimum total principal
stress and reached a conclusion that Seed’s criterion iscoherent with their experiment results.
As recent studies, T. Ishiguro(2005) and Y. Arai(2005) each conducted laboratory test and numericalanalysis of Kamihikawa dam and Surikiamigawa dam
respectively. They prepared specimens using dam’s
core materials, set in triaxial apparatus, and plotted therelationship between difference in water pressure andminimum principal stress when HF occurred. The
experiment result followed Seed’s criterion. They
also defined HF safety factor based on Seed’s criterion:

σ3

u
σ3

2.4 Previous studies

horizontal crack,or uplift

K0 < 1horizontal crack,or uplift

Fig.6 Failure mechanism of Hachioji excavated slope

σ1

vertical crack

σ3

150 kN/m2
S Sand Bed G Gravel Bed L Loam

Duncan’s Criterion Δu > σ 1

u is larger than σ 3uuFig.3 Conceptual diagram of each criterion

2.3 Failure of Hachioji slope
Slope of excavated road in Hachioji, Tokyo, failed
after one night of intense rain on October 1, 2002.
Sidewalk uplifted up to 1.6 m, and cliff fell about 4.0
m as shown in Fig.4 and Fig.5.
Takeyama (2005) focused on geological structure of
the site ground. At the bottom laid high permeable
Komiya sand layer (Ksg), and on top of it laid low
permeable loam layer (Lc). The altitude of the sandlayer surface was 10 m below the Tama River whichflows nearby. When there was heavy rain, the ground

Fsh =

σ3
Δu

(4)

and evaluated many existing dams in Japan. Most
dams in Japan were judged “dangerous” by this safety
factor, but these had not failed and still stand today.

3

Properties of the object soil

Samples 5-② and 5-③ were extracted from theground 5 to 6 m below the surface of uplifted sidewalk
and the author conducted laboratory tests.

1:
1.
5

Slip drop cliff
4.0

A’

Water pressure

Fig.2 Dam body in 3 dimension
Seed’s Criterion Δu > σ 3

LGreen blocks
5
1:0.

Sidewalk
uplift1.6

3.1 Physical properties

3.0
0

5(m)

Fig.4 Sidewalk uplift
Fig.5 Cross-section
water level in the sand layer suddenly rose up andthere was 10m difference of water head in Komiya
sand layer. Based on measurements and analysis,
Takeyama concluded that due to the heavy rainfall,water pressure in Komiya sand layer became greaterthan the overburden pressure, and the water pressure

Results of laboratory tests are shown in Table 1.
Oedometer test of undisturbed Hachioji sample wasconducted to know the consolidation property andpre-consolidation stress of the soil. Fig.7 shows thee-logσv curve.

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under Hachioji sidewalk was greater than 1; and same
soil of OCR=9.7～23.7 has K0 of greater than 1.

Table 1 Physical properties of Hachioji loam
sample name (depth): Hachioji 5-②, 5-③ (5-6m)
water content test
density test
water content w(%) density ρs(g/cm3)
5-②
56.7
2.664
5-③
55.1
2.664
LL/PL test
liquid limit wL(%) plastic limit wp(%) plasticity index Ip
5-②
91.0
44.3
46.70
5-③

800

K0 < 1
K0 > 1600
σv' (kPa)grain size test
fine gravel (%) coarse sand (%) medium sand (%)
fine sand (%)
5-②
0.1
0.1
1.2
2.2
5-③
0.0
0.2
1.3
4.2
silt (%)
clay (%)
maximum grain size (mm) 50% grain size D50
5-②
64.3
32.1
4.75
0.0243
5-③
60.9
33.4
2
0.0264

Fig.8 K0 apparatus

pc=420kPa

1.6

K0 = 1

K0=0.45
OCR=1

400

K0=2.12
OCR=9.7200

K0=2.68
OCR=12.8

K0=3.57
OCR=23.7 0
0

1.5

200

400
σh' (kPa)

600

800

Fig.9 K0 state plotted (unload)
e 1.4

4

1.3

1.2 0
10

As stated, most researchers had conducted HF tests
in triaxial apparatus which has an advantage incontrolling and measuring cell pressure σ h.
However in this study the horizontal deformation isrestricted, which expresses the better actual ground anddam condition, which are also horizontally confined bypressure of sideways soil.
The experiment applies water pressure to saturated
consolidated soil from the sand layer beneath. The
sample is modeled to be uniform. Assuming that thestress conditions do not change, the author discusses
Seed’s criterion under initial stress conditions. Twostates are investigated: NC and OC. Three samples
were used: silica flour, Hachioji’s loam, and kaolin.

Cc=0.496
101

102
log σv(kPa)103

Fig.7 e-logσv curve
By Casagrande’s method, pre-consolidation stress pc
was determined as 420 kPa. From equation
σ v' = (γ t − 1)h ⋅ γ w(5)vertical effective stress was calculated to lie between
24.5kPa to 29.4kPa in depth of 5 to 6m.
Overconsolidation ratio is defined asOCR =σ v' max.
σ v'

Seepage failure experiment(6)

Therefore, OCR of this sample must lie between

4.1 Experiment apparatus and procedure

14 ≤ OCR ≤ 17

(7)
From the result, it was discovered that the loam layer
was highly overconsolidated.

The diagram of the specimen is shown in Fig.10.
Dial gauge was set on the loading ram to measure thevertical displacement, water tube was connected topore water pressure meter, then to a water tank and to aburet to measure the seepage amount. Samples wereprepared as slurry by mixing well with water. Air
was carefully got rid of inside the specimen and on theway in all tubes and valves. If the apparatus is turned
onto the side, the sample can be interpreted as the corematerial of dam which is given water pressure from left
hand side, with the sand layer being filter material ofloading ram
dam.

3.2 K0 load-unload test
K0 load-unload test was conducted for undisturbed
Hachioji sample. The specimen was set in K0
measuring apparatus shown in Fig.8 and given backpressure, cell pressure, and vertical load. Afterloading the specimen until it is considered to benormally consolidated, unloading steps were taken by
giving extra height of the specimen Δ h(cm) anddecreasing the cell pressure. When the specimen is
at K0 state, equation
ΔV (cm3 ) = A(cm 2 ) ⋅ Δh(cm)(8)
must be satisfied, where Δh times the area of thespecimen equals to the change in water volume ΔV .
Fig.9 shows the result of unloading test. Black
plot signifies the specimen is not at K0 state, while redplot signifies the specimen is in K0 state. OCR of theplotted values at K0 state range from 9.7 to 23.7, which
include the OCR obtained from oedometer test.
Therefore we now know 2 things: K0 of the loam layer

96.9mmcross-sectional area
A=73.79cm2
198.7mm

metal plate
porous metal plate

filter paper
filter paper
filter papersoilsand and gravel
greasewater flow

Fig.10 Diagram of the specimen
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The vertical stress was 20 kPa all cases. In Fig.13,
coefficient of permeability of NC abruptly rises atcertain points, while it is nearly constant for the OC(OCR=13). This can interpret that in NC, a water path
was developed in sample. Vertical displacement rates
are also different for NC and OC. NC sample heaves
up slowly and nonlinearly possibly because considerable
amount of water flowed out through the crack, while OC
sample heaves up rapidly and linearly because all water
was caught in between the loam layer and sand layer.
Evidence of water passing through the NC loam can also
be observed in Fig.14 and Fig.15, in which soil particles
and red ink were recognized above the porous metal.
There was no evidence of such water passage in OC(Fig.16). Safety factor based on Seed’s criterion for
OC sample at heaving can be calculated by

4.2 Results and discussion
After applying water pressure greater than thevertical load, vertical cracks formed in NC silica flour(Fig.11) while no vertical crack formed in OC silica
flour (Fig.12) of OCR=8.
For Hahioji loam sample, vertical displacement d(mm) of the sample, applied water pressure u (kPa) andseepage amount q (cm3/s) were recorded and plottedagainst time (min) in Fig.13.

Fig.11 NC silica flour

Fig.12 OC silica flourd (mm)-15-10-5

u (kPa)

0
0
30

Fsh =

100

200

100

200

20

(11)

Kaolin was tested similarly, and for NC cases
coefficient of permeability also changed abruptly,
pointing out the possibility of crack formation. As
shown in Fig.17, unlike Hachioji sample in which no300 recognizable crack formed around the perimeter, kaolin
formed cracks in the perimeter. The water seemed totarget the loosest spot in the sample.

10

0
-7 0
[×10 ] 6
5
4
3
2
1
0
0

20
= 0.83 < 1
24

5Conclusions

300

k (cm/s)

Hachioji landslide mechanism can be explained byheaving of the loam layer uplifted by water pressure in
the sand layer. Because it was overconsolidated, thelayer lifted up with no evidence of seepage and hence novertical cracks. There was an evidence of formation of
100
200
300
time (min)water path or crack inside NC sample at around Δu=σFig.13 Hachioji loam, NC(purple) and OC(orange)
There was no3, which follows Seed’s criterion.
Coefficient of permeability, k=v/i(cm/s) was calculated
evidence of formation of water path or crack inside OC
sample before and after heaving, which follows Seed’sq (cm3 /s)
from
(9)
v=
2
criterion. Heaving occurred when the safety factor was
A (cm )
lower than 1. The water pressure at HF was different
for Hachioji loam and kaolin. Hachioji loam has lowerp (kN/m 2 )
and
.
(10)
i=
3
permeability than kaolin, therefore even though theyh (m) ⋅ γ w (kN/m )were under the same confined pressure, it can besoil particles
considered that crack was easier to form in soil with low
permeability. Although the crack formation features
are different among different samples, all of themfollowed Seed’s criterion.

References

Fig.14 NC Hachioji loam Fig.15 NC Hachioji with ink[1] Ohta,H., Yoshikoshi,Y., Mori,Y., Tomobe,Y.,
Ishiguro,K., Fujiyama,T.: Safety evaluation of large
rockfill dams during first reservoir filling, ICOLD, 2006.
[2] Seed,H.B. and Duncan,J.M.: The Teton Dam
Failure-A petrospective Review, Proc.,10th Int.Conf.
S.M.F.E., 1981.
[3] Takeyama,Y., Ohta,H.: Slope failures triggered byrise of local ground water level caused by the localized
torrential downpour, TITech master thesis, 2005.
[4] Murdoch, L.C.: Hydraulic fracturing of soil duringlaboratory experiments, Geotechnique 43, 1992.

Fig.16 OC Hachioji loam Fig.17 NC kaolin with ink
94Technical Report of International Development Engineering

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Proposed Design Method of Cathodic Protection
for Reinforced Concrete Member under Chloride Attack
Student Number: 04M18080 Name: Keiyu KAWAAI Supervisor: Nobuaki OTSUKI

塩害劣化した鉄筋コンクリート部材に対する電気防食設計手法の提案
河合 慶有
本研究では，鉄筋コンクリート材料の不均一，欠陥および劣化進行過程が電気防食工法の効果に及ぼす影響について実験的および解析的に検討を行った．その結果，以下のことが明らかとなった．①防食電流はコンクリートの欠陥部に優先的に流入し，欠陥部の鉄筋部位は過防食になる危険性が示された．なお，この傾向は，いずれの腐食劣化進行過程においても同様であった．②多段配筋された鉄筋コンクリート部材では，通電電流密度に関わらず，部材の最深部に配置された鉄筋に流入する防食電流を制御することは困難である．特に，本研究の範囲内では陽極から 250mm 以上離れた鉄筋において所定の防食効果を得ることは困難である
ことが実験的，解析的に示された．③鉄筋コンクリート部材に対する電気防食設計手法が提案された．本手法は，防食基準電位を-0.85〜-1.0（V vs CSE）とした電位制御による防食設計手法とした点に特長がある．

1such as incubation and propagation on the steel bar.
However there are few researches about the influences ofthese factors on cathodic protection. Therefore, the purposesof this study are as follows: (1) To clarify the influences of thematerial property of reinforced concrete, defects in concrete,and deterioration period of steel bar on the effectiveness ofcathodic protection. (2) To develop a numerical analysis
technique using FEM to optimize the cathodic protection to
the steel bar in concrete. (3) To propose a systematic design
method of appropriate cathodic protection for reinforced
concrete members.

Introduction

Cathodic protection method has been recognized as
one of the most effective corrosion control methods in recent
years due to its reliability and effectiveness against steel
corrosion in concrete under such as chloride attack.
In order to make use of cathodic protection method effectively,
it is necessary to develop a systematic design method forappropriate cathodic protection. As a prerequisite, it isimportant to design the electric circuit properly in order toprovide appropriate current on the steel1). Nowadays, thismethod is applied to existing reinforced concrete structureusing a polarization about 0.1V at each region on the steel
bar. Generally, it is very difficult to carry out an optimal
corrosion protection to the steel bar in concrete and toevaluate the effectiveness of corrosion protection. This isbecause the current distribution is affected by theheterogeneity of reinforced concrete, defects in concrete suchas cold-joint and crack, and deterioration period of steel bar

2 Experimental Procedure(1) Outline of Experiment
There were two types of specimens (case A and B)
used in this study as shown in Fig.1 and 2. The size of
specimens embedded with divided steel bars as shown in
Pic.1 was 100×100×400mm. In the case of case A without
cold-joint and case B specimen, concrete was cast at one time.
On the other hand, in the case of case A with cold-joint,
concrete was cast in the mold half-full and after 24H, newconcrete was placed on the top of the hardened concrete. As
for the reinforcement used, 14 elements of divided deformed
steel bars with the diameter of 13mm were attached together

Fig.1 Case A specimen

Lead wire

10

13

Steel bar

Epoxy resin
Unit : mm

Fig.2 Case B specimen

Pic.1 Divided steel bars

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Current density (A/m2)

0-0.2

TRIDE-2006-01, February 20, 2006 (ISSN 1880-8648)

0

0.5

1

1.5

The measurements of polarization curves give E0 and r(j),and V is external voltage. Thus, all boundary conditions havebeen defined and FEM can be used to calculate the current
distribution in the steel bar in concrete.

2

-0.4

Potential (V)

-0.6
-0.8

3

-1.2
-1.4

Fig.3 Example of polarization curveusing an epoxy resin to one straight bar. These bars wereembedded in case A specimens respectively. In the case ofcase B specimen, the divided steel bars consisted of 4
deformed steel elements. Each steel element had lead wires
soldered on it serving as a connection for the electricalmeasurement. After demolding, all the specimens were cured
in tap water for 28 days. Initial measurements wereconducted on the specimens prior to their exposure in Clacceleration chamber to accelerate corrosion on the steel bar.
The acceleration process involved a cycle of subjecting thespecimens under wet condition for 36H (40℃, more than
95% R.H.) and submerged condition for 24H in watercontaining Cl- (3%) during 3 months period.
(2) Outline of Numerical Analysis
The distribution of potential in the concrete complies
with the following Laplace’s equation2);∇(σ∇φ ) = 0

4

(1)

(2)

Where, n is normal vector of the insulation wall.
On the surface of steel and anode, polarization
phenomenon occurs under current flows. The polarization
behavior is described with an equilibrium potential E0 andan over potential as a function of current, as follows;

E steel = E steel − rsteel ( j )（3）

E anode = E anode − ranode ( j ) + V(4）0Current density (A/m2)

Potential (V vs CSE)

0

Result and Discussion(1) Influence of materials properties, defects in concrete anddeterioration period on the effectiveness of cathodic
protection
Fig.4 shows the relationship between current
distribution on the steel bars and steel elements in case A
specimen without defects during propagation period. From
this figure, it can be said that the current distribution in
concrete was influenced by materials properties in concretein each electric current density even if there was nocold-joint in concrete. The Coefficient of variation of current
distribution on the steel bars was 25.4%, 25.0%, 26.2% ineach electric current density, 10, 20, 30mA/m2. This isbecause electric conductivity was different at each region in
concrete due to concrete heterogeneity and shape of steel bar.
On the other hand, Fig.5 shows the relationship between
current distribution and steel elements in case A specimen
with cold-joint at the center part of concrete during
propagation period. From this figure, it can be said that

Where, σ is the conductivity of concrete, φ is potential inconcrete.
The boundary conditions have two types namely
insulation wall and metal electrode surface. At the insulation
wall, the current doesn’t flow through the wall, and its
boundary condition is given by the equation below;n ⋅ (σ∇φ ) = 0

Measurement Items

In this study, linear anode system was used as theelectric condition. Under this condition, three levels of
current density, 10, 20, 30mA/m2 were investigated. The
measurement items considered in this study were as follows:(1) Thecurrent distribution, half cell potential andpolarization resistance in each steel element were measured
using an ammeter and a potentiostat connected with leadwires. Coefficient of variation in the current flowing alongthe 14 steel elements was calculated to determine thevariations of anticorrosive current. (2) Moreover, thepolarization curve which was the relationship between
current density and potential on the steel bar were measured
by using potentiostat (HOKUTO DENKO,HZ-3000) as
shown in Fig3. And the potential scanning rate was 1mV/s
with Ag/AgCl serving as a reference electrode. Thus, thepotential on each steel element can be calculated by using
the current distribution and polarization curve. Furthermore,
the relationship was used as a boundary condition on themetal surface, steel and titanium mesh in numericalanalysis.

-1

Fig.4 Current distribution, case A

Fig.5 Current distribution, case A

Fig.6 Potential distribution, case A

Fig.7 Potential distribution, case A

Without defects

With Cold-joint

Without defects

With Cold-joint

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current flowed locally into the steel bar at cold-joint in
concrete more than any other parts without defect. To
compare the result without defects in concrete, the current
density which flowed into the steel bar at cold-joint was
about 3.3 times than the maximum value obtained in the
result in each electric current density.
Fig.6 shows the relationship between potential of thesteel bars and steel elements. From this figure, it can be said
that the potential distribution on the steel bars varied even if
it was under cathodic protection. The coefficient of variationof potential was 6.2%, 6.9%, 7.7% in each electric current
density. On the other hand, Fig.7 shows the relationshipbetween potential distribution and steel element. From thisfigure, the potential on the steel bar at cold-joint was
relatively lower than any other parts. According to past
research, it is reported that if the potential of steel bar islower than -1V, the evolution of H2 occurs on the steel bar
and deteriorate the covering concrete3). Therefore, thepotential of steel bar should be more than -1V, so that thepotential of the steel bar at cold-joint was locally overprotected as the current density became higher.
This tendency was the same as the result during
incubation period. Therefore, the potential of the steel bar at
cold-joint in concrete tended to be locally over protected inspite of deterioration period.

specimen during incubation period. This graph shows therelationship between potential of steel bar and each layer ofsteel bar. From this figure, we can see that the potential ofsteel bar in the arrangement of steel bars near the distancefrom the anode became higher as the electric current density
became higher. However, it was observed that the potential
distribution at a distance over 250mm from the anode wasalmost constant in spite of electric current density. Therefore,
the potential distribution at a distance over 250mm from theanode can not be controlled.
Fig.9 shows the modeling of the case B specimen for
numerical analysis technique using FEM. After modeling,
the conductivity value was set as σ=1/20 (1/Ωm), and thepolarization values of steel bar were set as Esteel0 = -0.545 andrsteel = -0.61. These experimental values were used to define
the boundary conditions as shown in Fig.10. Similarly, Eanode= 0.24 and ranode = 0.846 were set in the part of anode. The
calculated potential distribution of cathodic protection on thesteel bar in the case of electric current density, 10mA/m2, asshown in Fig.11 (before □). From this figure, it can be said
that the analytical result using the technique obtained frompast researches, had a good correlation with theexperimental results. However, the analytical result obtained
from the potential distribution in the steel bar at a distanceabout 150mm from anode was relatively lower as comparedwith experimental results. This is because approximate
linear polarization curve considered consisted only of one
linear component. Thus, the calculated potential distribution
was lower than the actual value especially in the case of-0.2

Potential (V vs CSE)

Current density mA/m 22
30
20
10

-0.4

-0.6

0
-0.4

Esteel = −0.295 − 2.02 j-0.8

Esteel = −0.545 − 0.61 j

-1.2
-1.6

-0.8
0

100

0

200
300
400
Distance from anode (mm)

0.5

1

1.5

2

Current density (mA/m2)

Fig.8 Potential of steel bars case B specimen

Fig.10 Boundary condition (part of cathode)

Potential (V vs CSE)

Potential (V vs CSE)

(2) Comparison Experimental result and FEM analytical result in
the case of case C specimen.
Fig.8 shows the experimental results in the case B

Concrete

Divided steel bars
Titanium mesh

0
-0.2
-0.4
-0.6

After
BeforeSteel result
elements
Experimental

-0.8
-1

Fig.9 Modeling of case B specimen

0

100

200
300
400
Distance from anode (mm)Fig.11 Comparison (FEM vs Experimental result)

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0

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in case A specimen without cold-joint. From these graphs, it
can be said that the potential distribution resulted in eachcase using the conventional method was not enough forappropriate cathodic protection. Therefore, it is necessary tokeep the potential of the steel bar less than -0.85V. Moreover,
if the concrete member has cold-joint it is also necessary tokeep the potential of the steel bar at the cold-joint less than
-1V based from the result in (1). Fig.12 shows the results
obtained using the method proposed in this study. Electric
current density 30mA/m2 was applied in each case. From
this figure, the potential distribution was on the range
between about -0.85 and -1.0V. Therefore, the appropriate
effectiveness of cathidic protection can be obtained to use themethod which is to keep the potential of steel bar below-0.85V at each region on the steel bar.

Passive state
condition

-0.2
-0.4
-0.6
-0.8
-1

Cold-joint
-1.2
0

5

Half-cell potential
Without defects
With cold-joint

10

Conventional method
Without defects
With cold-joint

15

Steel elements
Proposed method
Without defects
With cold-joint

Fig.12 Comparison (Conventional vs Proposed)

applying low electric current density in the steel bar.
Therefore, the boundary condition should be
evaluated appropriately. In order to do this, two components
were used in approximating the linear polarization curve asshown in Fig.10. The second polarization values were Esteel0 =-0.295 and rsteel = -2.02. From Fig.11 (after ■), it can be said
the re-calculated potential distribution has better correlation
with experimental results. Consequently, this FEM
analytical method was applicable for the practical andcomplex 3-D member.

5

Conclusions

The conclusions derived from this study can besummarized as follows.
(1) It was confirmed that current and potential distributionof the steel bar under cathodic protection was influenced
by material properties, especially resistance of eachmaterials, defects in concrete, and deterioration period.
In particular, current flowed locally in the steel bar at
concrete defects such as cold-joint and crack. Therefore,
the steel bar at defects in concrete tended to be overprotected for cathodic protection in spite of deterioration
period.
(2) In the case of arrangement steel bars in concrete, it was
confirmed that the potential distribution of the steel bar
at distance over 250mm from the anode can not be
controlled both in the experiment and the numericalanalysis.
(3) A design method of cathodic protection for reinforced
concrete member was proposed. During propagation
period, it was important to keep the potential of thesteel bar between -0.85 and -1V in order to provide
better cathodic protection.

(3) Proposed design method of cathodic protection
Nowadays, cathodic protection method is applied toexisting reinforced concrete structure using a polarization
about 0.1V at each region on the steel bar. However, it was
confirmed in this study that the potential of the steel bars
varied even if it was under cathodic protection during
propagation period. It meant that corrosion still occurredunder cathodic protection. Therefore, the catohdic protection
method should be applied to reinforced concrete structure
appropriately during propagation period. In order to do this,a design method was proposed in this study. Proposed
method was to control the potential of steel bar between-0.85V and -1V. Based on the guideline for corrosive
protection of marine structures, the potential in the steel bar
should be less than -0.85V in order to maintain a passive
state condition. It means that under this condition corrosion
may not occur on the steel bar.
Fig.12 shows the results using conventional andproposed method for case A specimen with or without
cold-joint. This graph shows the relationship between
potential of steel bars and steel elements. The white dots ingraph show the half-cell potential which is initial potential.
The gray dots in graph show the potential distribution using
this method during propagation period. Electric current
density 10 mA/m2 was applied in each case. From this figure,the potential of steel bar in the specimen without cold-joint
lied on the range between -0.6 and -0.75V. On the other hand,in the case of specimen with cold-joint, except for the part
where there is cold-joint, the result obtained was similar as

References[1] Concrete Library: “Guideline of Electro-Chemical Repair
Methods”, JSCE, 2001.11[2] Shigeru Aoki, Kenji Amaya, Matsuho Miyasaka,“ Boundary Element Analysis on Corrosion Problems”[3] Toyoharu Kobayashi, Toshio Yonezawa, Keizou Shuttou,“Diagnosis of corrosion on steel bar”, 1993, 5[4] “ Guideline of corrosive protection for marine reinforced
concrete structure”, JCI,1983, 298

Technical Report of International Development Engineering

TRIDE-2006-01, February 20, 2006 (ISSN 1880-8648)

RC 部材中の塩化物イオンと水平鉄筋周りの境界相が鉄筋腐食に及ぼす影響
学籍番号：04M18222

氏名：宋暘

指導教官：大即 信明

INFLUENCE OF CHLORIDE ION AND ITZ AROUNDHORIZONTAL STEEL BARS ON THE CORROSION OFSTEEL BARS IN CONCRETE
Yang SONG
本研究では、コンクリート中の内在 Cl‑濃度と水平鉄筋周りの境界相が鉄筋腐食に及ぼす影響を定量的に評価した．その結果、①内在 Cl‑濃度と境界相厚さが鉄筋腐食に影響することを定量的に示した。また①に関連して、②境界相が小さい場合（平均厚さ 8.6μm 以下）、Cl‑濃度が 5kg/m3 と高くても腐食が発生せず③境界相が大きい場合（平均厚さ 75.3μm以上）、Cl‑濃度 0.3kg/m3 と低くても発生する場合があることが確認された。

In order to simulate different Cl- concentration in the

Introduction

specimens, Cl - content of 0.3kg/m3,0.6kg/m3,5kg/ m3,10kg/
m3 of Cl- was admixed in the concrete mix.

Today, steel corrosion in concrete due to chloride has
become a major concern around the world. Based on the

2.1 Detail of Specimen

Code of the Japan Society of Civil Engineers (JSCE), the(1) type-1 specimen (The casting height = 5cm, steel bar

steel bar in concrete should not be corroded if the Cl-

covered by cement paste before casting): Fig.1 shows the3concentration is limited under the 1.2kg/m .

outline of the concrete specimen. Fig.2 shows the outline

On the other hand, other than the Cl- concentration theof the divided steel bar embedded in the concrete specimen.

ITZ around the horizontal steel bar may also influence the

The divided steel bars were attached together using an

1)2). The threshold value of

epoxy resin. Lead wires were also soldered in each of

Cl concentration (1.2kg/m by JSCE) may be changed if

steel elements in order to measure the current density

the ITZ around the steel bar changed. But there are few

flowing in the bar. Prior to the casting of concrete thestudies considering the combined effect of chloride attack

horizontal steel bars were coated with cement paste (W/Cand ITZ thickness on the corrosion of horizontal steel bar＝30％) in order to simulate a very small size of ITZ. Cl -in concrete. Given this background, the purposes of thiswas also admixed in the cement paste.

research are as follows: (1) To evaluate the influence of(2) type-2 specimen (The casting height = 5cm, the steel

chloride ion concentration on the corrosion of horizontal

bar was not coated with cement paste) Fig.1 also shows thesteel bars (2) To evaluate the influence of ITZ around theoutline of the concrete specimen.

horizontal steel bars on the corrosion of reinforced(3) type-3 specimen (The casting height =145cm),

corrosion of steel bar in concrete-

3

concrete exposed to chloride attack. (3) To investigate theFig.3 shows the outline of the reinforced concrete

combined effect of chloride concentration and ITZ

specimen. The higher the casting position is, the more

thickness on corrosion of horizontal steel bar in concrete.

bleeding water will be concentrated under the horizontal
steel bar. In this way we can get specimens with very large

Experimental Procedure

ITZ.
2. Mix proportion
In this research, In order to form larger ITZ around

1. Experimental Cases
In order to get different ITZ thickness,three types ofhorizontal steel bar, high water mix proportions (w=225kg/m3) was used to simulate high bleeding in concrete.

specimens were prepared as follows: (1) specimens withvery small ITZ size (2) specimens with normal ITZ size (3)Table 3 shows the mix proportions

specimens with very large ITZ size.
99Technical Report of International Development Engineering

TRIDE-2006-01, February 20, 2006 (ISSN 1880-8648)

3. External environment
In this research, wetting (for 24 hours) and drying (for72 hours) cycle conditions were simulated considering thecondition in the tidal zone in the sea.
4. Measurement items
The measurement items considered in this study are as
follows: (1)Measurement of macrocell corrosion current
density by using a zero resistance ammeter device, (2)Measurement of microcell corrosion current density byusing a corrosion monitor, (3)Measurement of oxygen
permeability in concrete by using a potentiostat,(4)Fig.3: Outline of TYPE-3 Specimen

Measurement of the size of thickness of ITZ formed aroundthe horizontal steel bar by using a Digital Microscope,（5）Table 1: Experimental Case of

Measurement of bleeding ratio of fresh concrete in each
TYPE-1 and TYPE-2specimen
TYPE‑1
TYPE‑2
specimen
specimen*
Clbleeding
concentration
Time of vibratingratio
3(second)（kg/m ）
0
30
120
30
0.3
●
●
●
●
1.23%
0.6
2.10%
●
●
●
●
5
2.25%
●
●
10
0.96%
●
●
●
●
20
0.51%
●
●
●
●
* Steel bar is covered by cement paste (W/C=0.3)
Table 2: Experimental Case of TYPE-3 specimen

experimental case ， (6)Calculation of the total corrosion
rate

by

using

(1)and(2).Lastly,(7)Calculation

of

the

corrosion propagation by using the total corrosion rate.
(Corrosion rate measurement was done at the end of the 9th
cycle of the wetting and drying）.

Cl‐concentratio TYPE‑3
specimenn(kg/m3)
0.3
●
0.6
●
10
●
20
●

Fig.1: Outline of TYPE-1 and TYPE-2 Specimen

Epoxy

5cm

lead wire

5cm【divided steel bar】

bleeding
ratio
1.46%
1.25%
0.65%
0.50%

5cm
Epoxy

Sectional viewXbamboo Round
Steel bar Steel bar Steel bar

Sectional
view

Steel
bar

Dividedsteel bar
ITZ under
the steel bar
concrete

1 mm
Fig.2: Outline of the divided steel bar

Fig.4: ITZ under the divided steel bar

Table-3 Mix Proportions
W/C (%)
55

W (kg/m 3)

C (kg/m3)

225
409
AE： Air-entraining Agent

S(kg/m3)

A(kg/ m3)

Cl- (kg/m3)

AE(g/m3)

760
924
10
2863
AEWEA： Air-entraining Water-reducing Agent100

AEWRA (g/m3)
4090

Technical Report of International Development Engineering

TRIDE-2006-01, February 20, 2006 (ISSN 1880-8648)

Result and Discussion

dangerous zone .Comparing with the safe zone as defined

1. Influence of Chloride Ion Concentration on theby the JSCE code, it was found out in this study that inCorrosion of Horizontal Steel Bars

some zones identified to be safe were actually not safe, on-

Fig. 5 shows the relationship between Cl concentration

the other hand there also zones that were identified to be

and the total corrosion rate. From the figure, we candangerous in the JSCE code was actually safe in thisobserve that the tendency of corrosion rate in the horizontal

research. Defining therefore the safe zone should not only

steel bar tends to increase as the Cl-

be based on the Cl- concentration but also on some otherconcentration

increases. However, from Table 4 even in the same Cl-

related factor such as ITZ.

concentration the total corrosion rate of specimen with

0.3 kg/m3

Total corrosion rate
(mm/year)different ITZ thickness varies widely. This simply indicatesthat the Cl - concentration is not the only factor that
influences the corrosion of the steel bar.
2. Influence of ITZ around the Horizontal Steel Bars on the
Corrosion of Steel in Concrete
rate

in

the

steel

bar

is

larger

10kg/m3

0.03
0.025
0.02

varies widely

0.015
0.01
0.005
0

The criteria of corrosion is defined as follows: if thecorrosion

5 kg/m3

0

than

5

10

15

Cl- concentration (kg/m3)

0.00036mm/year, this means that the time until crack

Fig.5 Relationship between the Clconcentration and total corrosion rate.

occurs may be under 35 years and the steel bar is said to becorroded (dangerous).
Fig.6 〜 Fig.8 shows the relationship between ITZ

Table 4: Difference corrosion rate in same Cl- concentration

thickness and the total corrosion rate. As shown, in eachCl- concentration (0.3kg/m3 5 kg/m3 10 kg/m3) we canobserve that the total corrosion rate in the horizontal steel

Total

bar increases as the ITZ thickness becomes larger.

Corrosion

Presumably due to the high oxygen permeability inconcrete, as shown in Fig.

9.

Cl- concentration (kg/m3)

rate

As shown, the oxygen

permeability tends to increase as the ITZ thickness(mm/year)

0.3

5

10

becomes larger. This means that more water and oxygen

Maximum

3.5×

8.4×

2.8×

value

10 − 410 − 310 − 2

Minimum

9.4×

1.5×

7.7×

factor that influences corrosion in the steel bar. As shownvalue

10 − 610 − 310 − 3in Fig.7, if the ITZ thickness is large enough(60.8μm andMax／Min
37.45

5.48

3.64

diffuses into the horizontal steel bar, thereby, promoting
faster and higher corrosion reaction
We can also observe that the ITZ thickness is another106μm) the steel bar may be corroded even if the Cl
concentration is as low as 0.3kg/m3. On the other hand,-（times）

inFig.7 and Fig.9, if the ITZ thickness is small enough (lessTotal corrosion rate
(mm/year)than 8.6μm) the steel bar will not be corroded even if theCl- concentration is higher than 5kg/m3.
3. The Combined Effect of Chloride Concentration and ITZ
Thickness on Corrosion of Horizontal Steel Bar inConcrete.
In Fig.10, a line was drawn with the same corrosion rate(the time until the crack occur is 35years). The figure

0.03
0.025
0.02
0.015
0.01
0.005
0
0

shows that both Cl - concentration and ITZ thickness

50

100

150

200

significantly influences the corrosion of the steel bar. The

ITZ thickness (μm)

figure also delineates the location of the safe zone and theFig.6 Relationship between ITZ
thickness and total corrosion rate.
(Cl-=10kg/m3 )101

TRIDE-2006-01, February 20, 2006 (ISSN 1880-8648)

0.00036mm/year (corroded)

0.00040.008

0.00030.006

0.00020.004

0.0001

0.002

0

0

0.00036mm/year (corroded)

2E-10
1E-10
0

ITZ thickness (μm)

ITZ thickness (μm)

Fig.7 Relationship between ITZ
Thickness and total corrosion rate.
(Cl-=0.3kg/m3)

Fig.8 Relationship between ITZ
thickness and total corrosion rate.
(Cl-=5kg/m3)

Fig.9 Relationship between
ITZ thickness and oxygen permeability.
(Cl-=10kg/m3 )

50

100

150

200

0

20

40

60

Corrosion rate = 0.00036 (mm/year)
time until crack occur=35(years)
Safe specimen (time until crack occur ＞35 (years))

×

Dangerous zone
(corroded)

×
×

40

×
×

×
×

Safe zone

0
0

1.2

2

4

6

8

Cl- concentration (kg/m3)

80

50 40
40
20

196
400

Safe

0 1.2 2

Very safe

Fig.10 Relationship between
Cl-concentration and ITZ thickness

2 years

3 years
5 years0

10

1 yearVery dangerous

Safe

×
×

80

35 years

ITZ thickness (μm)

Safe zone
defined by JSCE

Dangerous

120

×
×

Time until the crack occur is over 60 years
Time until the crack occur is less than 35 years

Time until crack occur (years)

× dangerous specimen (time until crack occur ＜35(years))
ITZ thickness (μm)

3E-10

0
50
100
150
200
ITZ thickness under the horizontal steelbar （μm）

0

120

4E-10

oxygen permeability（mol/cm2/sec）

0.01

0.0005Dangerous7 years

50

4

5

6

8

2.5
Bleeding ratio （%）

Total corrosion rate
(mm/year)Technical Report of International Development Engineering

2.5

2

121

1.5
1

659

0.5

Assumedsafe zone

1.1
0.2years

0
0

10

5

10

15

-

20

25

3

Cl concentration （kg/m ）Cl- concentration (kg/m3)

Fig.11 Relationship between
Cl-concentration and ITZ thickness

Fig.12 Concept for finding relationshipbetween the Cl - concentration and thebleeding ratio (casting height = 5cm)

Fig.11 shows the time (years) until crack occurs in

the horizontal steel bar. In the case of the specimens

specimens. If the ITZ thickness is small and the Cl-

with large ITZ (over 75µm thickness), the steel bar isconcentration is low the specimens are very safe.

corroded even if the Cl - concentration is as low as

Fig.12 shows the concept for finding relationship between

0.3kg/m3.

-

On the other hand, in the case of thethe Cl concentration and the bleeding ratio. Since it isspecimens with small ITZ size (less than 8.6µm

impractical to measure the ITZ in real structures,thickness), the steel bar is not corroded even if themeasurement of the bleeding ratio in the concrete mix is

Cl-concentration is as high as 5kg/m3.

3. The corrosion rate of horizontal steel bars can be

the best alternative. Higher bleeding ratio means more
bleeding water is trapped around the horizontal steel bars

evaluatedcausing the formation of larger ITZ. From the engineering

concentration and ITZ thickness.

by

the

relationshipbetweenCl-

point of view, it is important to know the relationshipbetween the Cl- concentration and the bleeding ratio by

REFERENCES

conducting further research.
1)

Conclusions

Nobuaki Otsuki et.al ： Experimental Study on theeffects of Rebar and Matrix Properties on the Gap at
the Interfacial Transition Zones in

The following conclusions were derived from this study.

Reinforced

Concrete pp.1271-1276，1998．

-

1. It was confirmed in this study that Cl concentration

2)

T.U.Mohammed et.al ： Chloride-Induced Corrosion

has a great influence on the corrosion of the horizontalof Steel Bars in Concrete with Presence of Gap atsteel bar. However the corrosion rate of the steel bar

Steel-Concrete

cannotbeexplained

only

based

on

the

Cl

-

nterface ， ACI Materials Journal ，

99/No.2，pp149-156，2002．

concentration.

2. ITZ thickness has a great influence on the corrosion of102

Technical Report of International Development Engineering

TRIDE-2006-01, February 20, 2006 (ISSN 1880-8648)

SEASONAL AND DIURNAL FLUXES OF MOMENTUM, ENERGY,WATER VAPOR AND CO2 OVER TOKYO BAY
Student Number: 04M18050

Name: Ryoko ODA

Supervisor: Manabu KANDA

東京湾における運動量・熱・水蒸気・CO2 フラックスの季節・日変化
小田 僚子
首都圏で顕在化している都市大気環境問題に対し、隣接する東京湾における各種フラックスのシンク・ソース機構は重要な役割を果たしていると考えられる。そこで本研究では、東京湾上で長期連続的なフラックス現地観測を実施し、その結果、東京湾上の大気は都市からの移流または
海陸風循環により陸域の影響を強く受け CO2 のシンクになること、一般的な外洋海面と比して顕著な海表面温度日変化が現れることなど、現行の数値シミュレーションでは考慮されていない興味深い特徴が認められた。

1

Introduction

30 km

Most of the mega-cities in Asia are located in coastal
regions. Therefore, the interaction between sea surface
and the atmosphere is very important factors forunderstanding the Asian urban climates.
In recent years, FLUXNET have started building up
since 2001 [1]. As for ocean field, sea surface flux data
set for the global ocean, which were estimated from ship,in situ and satellite observations, has accomplished forthe period from 1981 to 2002 [2]. Therefore various
fluxes between land/ocean surface and atmosphere
increase our knowledge of surface energy balance. On
the other hand, few studies has reported air-waterinteraction in closed or semi-closed water area, such as
lake and bay, especially which adjacent to the mega-cities.
This is probably because that the sea surface is believed
to be insensitive to diurnal variation of radiative forcing
due to its large heat capacity. Actually, in most of themesoscale numerical predictions, it is assumed that
surface temperature is constant and that CO2 flux is zero.
These assumptions are derived from the data measured inocean surface far from the land. However, theseassumptions would not be the case for theclosed/semi-closed water surface, especially whichadjacent to the mega-cities. They often have limited fetch
and are expected to be influenced by the advection fromthe land. Hence, it is necessary to measure sea surface
temperature or the fluxes based on direct measurementwith the aim of accurate estimating about air-waterinteraction.
In this study, I focused on the flux based on direct
measurement in Tokyo Bay. Tokyo Bay is adjacent toTokyo Metropolitan area, which is expected to mitigate
the severe atmospheric environment in Tokyo. I
constructed a flux measurement system in Tokyo Bay,and investigated the fluxes between the sea surface andthe atmosphere.
The purposes of this study are (1) to evaluate thefluxes by the eddy correlation method, and (2) tounderstand the seasonal and diurnal pattern of themeasured fluxes. Also the observational results werecompared with that at a suburban area (Kugahara) inTokyo [3].

Pacific
Ocean
Tokyo Bay

Kugahara

Fig.1 Environment of the study sites. Location ofTokyo Bay and Kugahara tower in Japan. Gray
area indicates built-up area where artificial
structures occupy significant surfaces. The data
source is “Global Map” (ISCGM), available fromhttp://www.iscgm.org/.

2

Methods

2.1 Site Description
The study sites belong to the monsoon region that thewind directions have the seasonal reversal. Wind blows
the south during summer and from the north during
winter.
Tokyo Bay – The measurements have been conductedat the height of 12 m above mean sea level by using an
existing tower (N35.6°, E140.0°) since December, 2004.
The shortest distance from the land is about 3 km in the
direction of northeast. The seacoast region is almost an
industrial area which includes a food complex, steel and apetrochemical complex.
Kugahara – The measurements have been made since
May 2001 in a low-residential area, which mainly
consists of densely built-up houses, paved roads andsmall playgrounds, in Kugahara, Tokyo (N35.6°,
E139.7°). The height of a tower is 29 m. There is ahomogeneous residential area that the mean buildingheight is 7.3 m over 1 km. The distance to Tokyo Bay
tower is about 30 km.

2.2 Experimental Setup
I measured wind speeds, air temperatures, water
vapor densities, CO2 densities and radiant intensities at
each site. Fluctuations of wind speeds and air
103Technical Report of International Development Engineering

TRIDE-2006-01, February 20, 2006 (ISSN 1880-8648)

Table 1The list of the observation equipments

Tokyo Bay (H)Kugahara (H)Tokyo Bay (Ts-Ta)
Kugahara (Ts-Ta)

300

12
9

200

6

100

3

0

0

-100

-3

-200

-6
0

3

6

9

12

15

18

21

temperature difference
between air and surface (℃)

sensible heat flux (Wm-2)

400

air and surface temperature (℃)

Tokyo Bay
Kugahara
Items
Instruments
sampling
Instruments
sampling
wind speed
3-D Sonic Anemometer
Ultrasonic Anemometer
10Hz non ave.
air temperature(Campbell Scientific Inc., USA ; CSAT3)(Metek GmbH, Germany ; USA-1)
Height : 12m
8Hz non ave.
CO2 gasOpen Path CO2/H2O Analyser
Open Path CO2/H2O Analyser
above mean sea
Height : 29m
lebel
H2O gas(LI-COR, Inc., USA ; LI-7500)(LI-COR, Inc., USA ; LI-7500)
1Hz 10min. ave.
up/downward
Pyranometers
Pyranometers
Height : 12m
shortwave radiation(Kipp&Zonen, Netherlands ; CM3)
(Eko Instruments, Japan ; MS-62,42) 1Hz 20min ave.
Height : 25m
above mean sea
up/downward longwave
Pyrgeometer
Pyrgeometer
lebel
radiation(Kipp&Zonen, Netherlands ; CG3)
(Eko Instruments, Japan ; MS-201,202)

20
18
16
14
12
10
8
6
4
2
0

24

0

3

23 Dec. 2004

6

9

12
9

200

6

100

3

0

0

-100

-3

-200

-6
0

3

6

9

12

15

18

21

24

Japan Standard Time (hour)(b) 29th Jul. 2005

Fig. 2 Diurnal variations of sensible
heat flux (H) and a differenceof temperature（Ts-Ta）

air and surface temperature (℃)

300

40
38
36
34
32
30
28
26
24
22
20

12

15

18

21

24

Japan Standard Time (hour)rd(a)temperature difference
between air and surface (℃)

sensible heat flux (Wm-2)

rdTokyo Bay (H)Kugahara (H)Tokyo Bay (Ts-Ta)
Kugahara (Ts-Ta)

400

1000m

Tokyo Bay

Japan Standard Time (hour)(a)Winter

2000m

Tokyo Bay (Ta)Kugahara (Ta)Tokyo Bay (Ts)Kugahara (Ts)23 Dec. 2004
Advection

Tokyo Bay (Ta)Kugahara (Ta)Tokyo Bay (Ts)Kugahara (Ts)

Kanto Plain

3

6

9

12

15

18

21

24

BosoPeninsula

Summer

2000m
0

Tokyo Bay

1000m

Japan Standard Time (hour)(b) 29th Jul. 2005

Fig. 3 Diurnal variations of air
temperature (Ta) and surface
temperature（Ts）

temperatures were measured by a three-dimensional sonicanemometer. Densities of CO2 and water vapor were
measured by an open-path type infrared gas analyzer. Up
and downward short- and long-wave radiation intensities
were measured separately by using two sets ofpyranometers and pyrgeometers. Table 1 shows theobservation equipments which were installed at each site.

Tokyo Bay

Return flow
Return flow Descending flow
General wind

Kanto Plain

Tokyo Bay

BosoPeninsulaFig. 4 Schematic depiction of advection and sea
breeze circulation

2.3 Data Processing
The fluxes of momentum, energy, water vapor and
CO2 were evaluated by the eddy correlation method every
60 minute. For example, data of 8 o’clock means anaverage of 8 to 9 o’clock (JST). Over Tokyo Bay, notethat data of the radiant intensities were the instantaneous
values every hour until the middle of July, and data ofabsolute air temperature was corrected using data at anearest weather station, which was located in Tokyo Bay
water front. The water vapor and CO2 fluxes werecorrected for the effect of fluctuations in air density.
Coordinate axes were rotated so that mean verticalvelocity was zero.
For the evaluation of diurnal courses, I discuss thefluxes of data from December and July because each data
was representative for winter and summer, respectively.
As for the evaluation of seasonal courses, I used dataof 12 o’clock, which show clearly difference between
Tokyo Bay and Kugahra due to strong radiant intensity.
But it was removed that the data due to precipitation or
sensor malfunction. I analyzed the data from December
2004 to November 2005. Mean wind direction was

calculated using mean wind vector. I defined that upward
flux was positive.

3

Diurnal Variation of Fluxes in Summer
and WinterIn this discussion, the results for two specified days,
23rd December 2004 and 29th July 2005, which are typical
one in winter and summer, are used.

3.1 Momentum Flux

Momentum flux M (kgm-1s-2) over Tokyo Bay was
smaller than that in Kugahara in spite of strong wind (notshown here). This is because that sea surface is smootherthan urban surfaces. M showed a little dependency onwind speed WS, especially in the range of WS over 10
ms-1. Windswell develops as WS increase over sea, i.e.
the roughness of the surface becomes larger with strong
WS.

104

Technical Report of International Development Engineering
Tokyo Bay (12/23)
Kugahara (12/23)
Tokyo Bay (7/29)
Kugahara (7/29)

500
400

2.0
1.5
CO2 flux (mgm-2s -1)

latent heat flux (Wm -2)

TRIDE-2006-01, February 20, 2006 (ISSN 1880-8648)

300
200
100
0

1.0
0.5
0.0
-0.5

Tokyo Bay (12/23)
Kugahara (12/23)
Tokyo Bay (7/29)
Kugahara (7/29)

-1.0
-1.5

-100

-2.0

0

3

6

9

12

15

18

21

24

0

3

6

Japan Standard Time (hour)Fig. 5 Diurnal variations of latent heat
flux (LE)

12

15

18

21

24

Fig. 7 Diurnal variations of CO2 flux

500

2.0

Tokyo Bay (12)Tokyo Bay (07)400Tokyo Bay (12)Tokyo Bay (07)1.5
CO2 flux (mgm-2s-1)

latent heat flux (Wm -2)

9Japan Standard Time (hour)

300
200
100
0

1.0
0.5
0.0
-0.5
-1.0
-1.5

-100

-2.0

0

3

6

9

12

15

18

0

3

-1

6

9

12

15

18

wind speed (ms )wind speed (ms-1)

Fig. 6 The relation between latent
heat flux (LE) and wind speed

Fig. 8 The relation between CO2 flux andwind speed
days, and especially in winter the magnitude was muchlarger. This is probably because in winter drier air was
advected to Tokyo Bay, and thus the evaporation wasenhanced. Figure 6 shows the relationship between LE
and wind speed WS. LE over Tokyo Bay variedcorresponding to WS especially in winter. This result
suggests that WS was a more important factor for themagnitude of LE in winter rather than radiative forcing.

3.2 Sensible Heat Flux
Figure 2 shows the diurnal variation of sensible heat
flux H (Wm-2) and the difference of temperature [Ts-Ta](surface temperature minus air temperature), Ts and Ta areshown in Fig. 3. Ta in Kugahara can be regarded as arepresentative of urban air temperature because thediurnal course of Ta in Kugahara was similar to that of
Ootemachi, central business district in Tokyo (not shownhere). Ts was derived from Stefan-Boltzmann law
assumed that emissivity is 0.98 in Tokyo Bay and 1.0 in
Kugahara.
The variation of H is corresponding to [Ts-Ta]. H
over Tokyo Bay tended to begin to decrease in the
midmorning (Fig. 2). Ts had a peak in the early afternoon,
whereas Ta over Tokyo Bay was still high even in the lateafternoon (Fig. 2). Moreover, Ta over Tokyo Bay had awide daily range compared with Ts. This is because thatthe advection and sea breeze circulation occur in winterand summer, respectively. In winter, there mainly occurs
the advection from land to sea due to the Asia monsoon.
In summer, Ishii et al. [4] suggested that the atmosphere
over Tokyo Bay was influenced by urban air due to thesea breeze circulation, and thus the air above Tokyo Bay
was adiabatically heated due to the subsidence flow.
These would cause air temperature over Tokyo Bay ishigh even in the late afternoon, and it to be warmer than
the sea surface temperature. Schematic of advection
and sea breeze circulation are shown in Fig. 4.
In addition, the diurnal range of Ts in Tokyo Bay waslarger than that in the open sea [5]. As I described in
introduction, the diurnal change of sea surface
temperature is ignored in the current numerical models.
But this assumption is not adequate for theclosed/semi-closed water area adjacent to the mega-city.

3.4 CO2 Flux
Figure 7 shows diurnal variation of CO2 flux. The
flux of CO2 in Tokyo Bay was negative (CO2 sink),
whereas that in Kugahara was positive (CO2 source)
throughout the day. These results were attributed to thatthe air of high CO2 density in the urban area wastransported over Tokyo Bay due to advection in winter or
sea breeze circulation in summer. In recent years, several
researchers have made a study on gas exchange at the
air/water interface and pointed out that wind speed WS
over about 10 ms-1 increased gas transfer velocity [6].
Negative CO2 flux was corresponding to WS, especiallyover 10 ms-1, in our observation (Fig. 8).

4

Seasonal Variation of Fluxes

Figures 9 (a) to (e) show in the variation of the fluxesof momentum M, sensible heat H, latent heat LE, CO2,
and net radiation Rn and storage heat G, respectively.
M over Tokyo Bay was smaller than that in Kugahara
throughout the year (annual mean value was 0.03 kgm-1s-2,
0.39 kgm-1s-2, respectively) (Fig. 9 (a)). As mentioned in
3.1, sea surface is smooth, i.e. the surface drag is verysmall. Therefore the atmosphere over Tokyo Bay is notconductive to vertical exchange.
H was smaller than that in Kugahara (Fig. 9 (b)). H in
Tokyo Bay was positive in winter whereas it was
negative in summer. As mentioned in 3.2, the variation of
H over Tokyo Bay depended on the advection or sea
breeze circulation.

3.3 Latent Heat Flux
Figure 5 shows the diurnal variation of latent heat
flux LE (Wm-2). LE over Tokyo Bay was positive in all105

Oct-0 5

Nov-0 5

Sep-0 5Jul-0 5Aug-0 5

Jun-0 5

Dec-0 4

Oct-05

Nov-05

Sep-05Jul-05Aug-05

Jun-05M ay-05

Apr-05-2

storage heat flux G (Wm )(c) Latent heat
Tokyo Bay (Rn)
Kugahara (Rn)
Tokyo Bay (G)Kugahara (G)

1000
800
600
400
200
0

(d) CO2

Oct-05

Sep-05Jul-05Aug-05

Jun-05

May-05

Apr-05

Feb-05Mar-05Jan-05-200
Dec-04net radiation R n and
Oct-05

Nov-05

Sep-05Jul-05Aug-05

Jun-05

Apr-05M ay-05

M ar-05

Jan-05

Dec-04

Tokyo Bay
Kugahara

Feb-05

C O2 flux (mgm s )

-2 -1

1.0
0.8
0.6
0.4
0.2
0.0
-0.2
-0.4
-0.6
-0.8
-1.0

M ar-05

Jan-05

Feb-05

Dec-04

Oct-05

No v-05

Jul-05

Au g-0 5

Ju n-05

Ap r-05

M ay-05

M ar-05

Jan-05

Feb-05

Dec-04

Sep-05(b) Sensible heat(a) Momentum

Apr-0 5

Tokyo Bay
Kugahara

-200

-0.2

M ay-0 5

-2

0
-100

M ar-0 5

0.0

100

Tokyo Bay
Kugahara

Nov-05

0.2

200

350
300
250
200
150
100
50
0
-50
Jan-0 50.4

300

Feb-0 50.6

400latent h eat flux (Wm )Tokyo Bay
Kugahara

0.8

TRIDE-2006-01, February 20, 2006 (ISSN 1880-8648)

-2

1.0

sensible heat flux (Wm )-1 -2

momen tu m flu x (kg m s )Technical Report of International Development Engineering(e) Net radiation and Storage heatFig. 9 Seasonal variation of the fluxes
LE over Tokyo Bay was positive in all seasons (Fig. 9(c)). Dry air moved from the land to Tokyo Bay due toadvection or sea breeze circulation. Therefore, theevaporation would be activated in Tokyo Bay even insummer. On the other hand, vapor-pressure deficit had
not significant seasonal variation, whereas that in
Kugahara was shown seasonal course correspond to LE(not shown here). These results suggest that LE overTokyo Bay depends on wind speed WS rather than solar
radiant intensity.
The flux of CO2 in Tokyo Bay had large scatter but
negative flux was sometimes obtained, whereas that in
Kugahara was positive during almost all seasons (Fig. 9(d)). These results indicate that the urban air of high CO2
density was transported to Tokyo Bay. This caused a
difference of the CO2 density between the atmosphereand the vicinity of water surface, and thus the CO2 flux
was downward over Tokyo Bay. The negative flux was
shown especially in December and July, because
advection and sea breeze circulation is significant in
winter and summer, respectively.
G is determined as the energy balance residual fromdirect observation of Rn, H and LE.
G = Rn − H − LE

impact of Tokyo Bay.
Through my observation study, it was found thatTokyo Bay acts as source of heat in winter, sink of heatin summer, and source of water vapor and sink of CO2
almost throughout a year. This is because the fluxes were
influenced by the urban air due to advection and/or sea
breeze circulation. The advection and/or sea breeze
circulation also influence on larger diurnal range of sea
surface temperature.
In these result, it should be noted that significant
diurnal change of sea surface temperature occurred andthat CO2 flux was not zero. Therefore, current numericalmodels should include the diurnal change of sea surface
temperature and the variation of CO2 flux.

References[1] FLUXNET:
http://www.fluxnet.ornl.gov/fluxnet/index.cfm[2] Objectively Analyzed Air-Sea Fluxes (OAFlux) for
the Global Oceans: http://oaflux.whoi.edu/data.html[3] Moriwaki, R., Kanda, M., “Seasonal and Diurnal
Fluxes of Radiation, Heat, Water Vapor, and Carbon
Dioxide over a Suburban Area”, J. Appl. Meteorol. 43,
pp.1700-1710, 2004.
[4] Ishii, H., Kanda, M., Moriwaki, R., Okuzono, K.,“Observational Study on The Atmospheric
Environment over Tokyo Bay”, Annual J. Hydraulics
Eng., 43, pp.233-238, 1999. (in Japanese)[5] Kawai, Y., Kawamura, H.: “Evaluation of the Diurnal
Warming of Sea Surface Temperature Using
Satellite-Derived Marine Meteorological Data”, J.
Oceanogr., 58, pp.805-814, 2002.
[6] Asher, W. E., Wanninkhof, R., “The effect of
bubble-mediated gas transfer on purposefuldual-gaseous tracer experiments”, J. Geophys. Res.,
103, pp.10,555-10,560, 1998.

(1)

G in Tokyo Bay was larger in summer whereas that in
Kugahara did not have significant seasonal change (Fig. 9(e)). The large G in Tokyo Bay was because H and LE
decreased (see Fig. 9 (b)(c)) and Rn increased in summer.
The large amount of energy almost equal to Rn was storedin Tokyo Bay in summer.

5

Conclusions

The evaluation of closed/semi-closed water area
based on direct flux measurement is very important but
not well-known. I measured the fluxes in order toprecisely and quantitatively evaluate the atmospheric
106

Technical Report of International Development Engineering

TRIDE-2006-01, February 20, 2006 (ISSN 1880-8648)

Turbulent flow similarity in open air scaled models for urban micro
meteorology
Student Number: 04M18073 Name: Masahiko KANEGA Supervisor: Manabu KANDA

屋外スケールモデル実験における乱流相似則の検討
金賀将彦

屋外スケールモデルは都市接地層の微気象を研究するための有効な手段である。本研究ではこのスケー
ルモデルで得られた結果の都市への応用性を調べるために、乱流相似則の成立を確認した。この検証に基
づき、相似則理論の下で用いられている運動量粗度、熱粗度を算出した。運動量粗度は地表面形状の変化にかなり敏感であること、一方熱粗度は地表面形状に対して鈍感であるが、地表面代表温度のとり方でその挙動が大きく変わってしまうことがわかった。

1. Introduction

were investigated using the same scale models withdifferent size. And then, based on its results,roughness length for momentum and heat, which istreated within the framework of the similarity theory,
and which determines the efficiency of transport ofmomentum and heat in many atmospheric models,
was calculated and its behaviour was investigated.

Atmospheric surface layer is the main sink or sourceof momentum, heat, and scalars in the wholeatmosphere. Therefore, it is important to investigate
how these quantities are transported into the air
above from the surface layer. These issues have been
well investigated in relatively flat terrain, orvegetation surface, but not enough in city because of
its complexity and economical and social restriction.
If one overcomes and observation is conducted incities, the representativeness of these results is often
doubted due to inherent inhomogeneity in city:
variability of the local land use, and theconfiguration.
To clarify these uncertainties, scaled models
were constructed in outdoor. Simple cubic elements
reduced its dimension were arranged in flat concrete
plate. And then, various measurement equipments
were installed there. The advantages of using
outdoor scaled models for the research of urban
micro meteorology are following: first, naturalforcing of momentum and heat, which is difficult torecreate in wind tunnel, is realized. Second,
homogeneous roughness array makes the problem
referred above simple. Third, various physicalquantities are measurable. From these characteristicsof the outdoor scaled models, it is expected that it
becomes effective tool or infrastructure for the studyof urban micro meteorology.
Until now, the outdoor scaled models havecontributed much to the modeling of urban heatbudget [1]. However, detailed analysis about air
flow such as the similarity of the turbulent flow
between the scaled models and real surface layer,
has not been focused on. The similarity of the flow
is basic, but critical assumption for the scaled
models. Therefore, in this paper, the nature of the
turbulent flow over the outdoor-scaled models, andthe applicability of the existing similarity theory

2. Overview of Experiments
Two different scale models (named ‘1/5 model’ and‘1/50 model’ after the average height of theresidential area of Kugahara, Tokyo) wereconstructed at the private ground of Nippon Instituteof Technology (39.04N, 139.7E).
The description of 1/5 model is following.
1.5m-concrete cubes are regularly arranged spacing
the same distance of its length, on the flat concrete
plate of 100×50 m. Land use around the site isalmost rice fields. Three slender towers formeasurement instruments are at the center, and bothends of the model. Instruments used, measured
component, and data acquisition period is Fig.1 andtable 1.
1/50 model is almost the same but its size andthe way to install the instruments. The length of the
cube is 0.15m, and its base is 12m-squere plate
placed near the 1/5 model (separated from about
15m). The configuration of cubes is completely thesame as that of 1/5 model. Instead of towers, steal
pipes (φ=4.8cm) were built up for the setting of
instruments.
For the following analysis, temporal averaging
was over 60 minutes and fluctuation was calculatedwith linear detrending for every component. The
data acquired was almost unstable condition even innighttime, due to the large heat capacity of concrete,
so only the unstable case was analyzed.

3. Theoretical background107Technical Report of International Development Engineering

TRIDE-2006-01, February 20, 2006 (ISSN 1880-8648)

Fine bare T.C.
Fine bare T.C.

Radio meter

Sonic anemometerthermometer

T.C. embedded
heat plate

Radio meter

T.C. embedded heat
plate

4.5m

3.0m

0.30m

0.15m
0.15m

1.5m 1.5m
N

0.45m

1.5m (=H)

N

1.5m
1.5m

0.15m

Sonic anemometerthermometer

0.15m (=H) 0.15m

Figure1 Schematic diagram of scale models and measurement instruments (left: 1/5model, right: 1/50model)
table 1 Instrument used, measured components, and period the data acquired
Instrument

Sonic anemometer

Measuredcomponent

Period dataacquired(1/5)（1/50）

Fine bare thermocouple

Shortwave longwave radio meter

T.C. embedded heat platewind componentu , v, w (ms-1)
sonic temperatureT (K)air temperatures
Ta ( z ) (K)downward shortwave S ↓ (Wm-2)
upward shortwave S ↑ (Wm-2)
downward longwave L ↓ (Wm-2)
upward longwave L ↑ (Wm-2)

conductive heat flux ofeach face i
G (i ) (Wm-2)
surface temperature ofeach face i Ts (i )(Wm-2)

04 12/16- 05 8/2,
05 10/21- 05 12/19

04 12/16- 05 8/2,
05 10/21- 05 12/19

04 12/16- 05 8/2,
05 10/21- 05 12/19

05 10/21- 05 12/19

the same above

the same above

the same above

04 12/27- 05 12/19

where, U ( z ' ) is mean, along wind (ms-1) at heightz ' , Taero is representative temperature (K) at
zT + d called aerodynamic temperature (referred
after), Ta ( z ' ) is air temperature (K) at height z ' ,ΨM and ΨH are stability correction terms, and z 'equals to z - d , d (m) is set up value for highroughness, called displacement height. The conceptof roughness length for momentum zm and heat zT(m) appears here. These parameters mean the
conductance of fluxes against mean properties, andare determined by the characteristics of surface, notdepending on the state of flow, in MOS framework.
For spectra S ( f ) of u , w , T , and cospectraCo( f ) of u ' w' , w'T ' (where, f is frequency(s-1)), MOS is also valid. Kaimal and Finnigan [2]showed the nondimensional form of spectra andcospectra.
These formulae were derived from horizontallyhomogeneous, flat terrains, and the validity of thesehas been confirmed in many places. The results
obtained in flat terrain are compared with the results
obtained in scale models, and the similarity is
discussed in following chapter. The results obtainedin flat surface are indicated as ‘ref’, or ‘MOS’,
hereafter.

Monin-Obukhov Similarity theory (MOS) is surface
layer similarity theory, discussed here. Its essence isthat, in horizontally homogeneous terrain withstationary condition, any properties concerned in air
flow can be scaled by u* , T* , z ,and L , and theresultant nondimensional properties become only thefunction of z / L , a measure of atmospheric stability.
Definitions of u* (ms-1), T* (K), L (m) arefollowing:u* = (−u ' w')0.5
T* = − w'T ' / u*2
L = u* / k ( g / T )T*

(1)
(2)
(3)

where, u 'w' is momentum flux (m2s-2), w'T ' issensible heat flux (Kms-1), k is Karman constant(0.4), g / T is gravity parameter (ms-2K-1), z isheight from the ground (m), and u , w , T , is alongwind, vertical wind (ms-1) and temperature (K)component, respectively. Dash denotes fluctuationfrom mean value and overbar denotes temporalmean.
For mean wind and temperature profile,assuming constant flux layer and integrating theflux-gradient relationships over z, following formula
is derived:U ( z ' ) / u* = [ln(z ' / zm ) + ΨM ( z ' / L, zm / L)] / k

4. Results and Discussion(4)

4.1 Flow similarity
Figure 3 shows cospectra of u ' w' and w'T ' withall stability range. In unstable (-0.1> z ' / L ) ones, theplots disappear at low frequency part, and the other− (Taero − Ts ( z ' )) / T* = [ln(z ' / zT ) + ΨH ( z ' / L, zT / L)] / k

(5)

108

Technical Report of International Development Engineering

TRIDE-2006-01, February 20, 2006 (ISSN 1880-8648)

1

1

0.1

0.1

0.001
-4
10

0.01

-3

10

-2

10

-1

0

10
10
n=f(z-d)/U

1

10

1

0.1

z/L<-10-10<z/L<-1
2
10-1<z/L<-0.1-0.1<z/L<-0.01-0.01<z/L<-0.001-0.001<z/L<0reffCo(f)wT/wT

fCo(f)uw/uw

0.01

0.001
10-4

1

10-3

10-2 10-1 100
n=f(z-d)/U

101

102

1

10

0.1

0.01

0.01

0.001
10-4 10-3 10-2 10-1

100

101

0.001
-4
-3
-2
-1
0
10
10
10
10
10
n=f(z-d)/U102

n=f(z-d)/U

102

Figure2 Cospectra of u 'w' and w'T ' (upper: 1/5 lower: 1/50). ‘ref’ is from [2].

plots increase in 1/5 model of momentum transport.
This means inverse correlation ( u 'w' >0) at low
frequency part. On the other hand, also in unstable(-0.01> z ' / L ) case, low frequency contribution
clearly appears in 1/50 model of momentum. In
common, the low frequency contributions notobserved in MOS appear. Assuming Taylor’s frozen
turbulence hypothesis, the low frequency
phenomena mean large scale eddy motions beyond
the measurement height or whole site scales. It is outof MOS framework. Generally, it is said that MOS
works ranging to z ' / L =-10, and stability indicatedabove is within this range. However, MOS isviolated. Probably, the outer layer eddy, originatedfrom convective mixed layer or outer surface layerisaffects on and thus, the local z ' / L
inappropriate to a measure whether MOS works ornot. Outer layer information would be needed toquantify these phenomena, but we don’t have.
However, qualitatively, these are suggestive results
for the problem of the source area of momentum in
unstable, convective conditions. In neutral case, inother words, greater z ' / L than indicated above,
momentum cospectra fairly agree with the MOS,
even though the contribution of lower frequencies isstill observed, especially in 1/50 model. From theseresults, we judged MOS framework for momentum
transport is valid in neutral case.
Cospectra of sensible heat surprisingly agree
well with MOS in unstable condition, and the low
frequency contribution is not observed. This fact isalso interesting. Physical interpretation about theinconsistency of turbulent transfer between

momentum and heat in convective condition
observed in this site is difficult and cannot beanswered here, but the result may give hints when
the turbulent transfer in complex terrain is studied.
In neutral case, cospectra of sensible heat cannot be
define because of low correlation between w and
T . Additionally, T includes the noise of sensor(from spectral results, not shown). From the results
above, similarity of turbulent transfer about sensible
heat holds though there remains uncertainty inneutral case.
4.2 Roughness length for momentum and heat
Roughness length was estimated by least square fit
to the equation (4) and (5), using observed values
within the stability range specified above discussion.
Displacement height was determined by the model
proposed by Macdonald et al. [3]. The estimate forscale model configuration is d / H =0.455.
Fig.3 shows the relation between roughness
length for momentum and wind direction. 0 (deg)indicates the wind direction from the long axis of thesite. In the site, geometric configuration for windchanges with wind direction: Frontal area index,
defined as the area of roughness element projectedby the wind direction over unit plan area, increases
with wind direction (0.25 for 0 to 0.35 for 45 (deg)),
and arrangement also changes from square array(0deg) to staggered array (otherwise). Roughness
length for momentum is sensitive to the change ofthe configuration in this building-area ratio (0.25).
The estimates from the model equation of roughness
length for momentum proposed by Macdonald et al.

109

TRIDE-2006-01, February 20, 2006 (ISSN 1880-8648)

0.2

0.2

0.15

0.15
z m /Hz m /HTechnical Report of International Development Engineering

0.1

0.1
0.05

0.05
0

0
-45

-30

-15

0

15

30

45

-45

wind direction (deg)1/5Ma β=0.55

-30

-15

0

15

30

45

wind direction (deg)Ma β=1.0

1/50

Ma β=0.55

Ma β=1.0

Figure3 Roughness length for momentum .vs. wind direction: Ma indicates the model estimates by Macdonald
et al. [3]. β means parameter for arranging: 0.55 is for square, 1.0 is for staggered.

kB T-130
25

1/5 TR

1/5 TC

1/5 Teff20

1/50 TR

1/50 TC

1/50 Teff

regTC-1

regTeff-1

15

regTR-1

1/5 Tsc

1/50 Tsc

100

1000

10
5
0
-5
10

100

1000
Re*

10000

100000 10

100

1000

10000

100000 10

100

1000
Re*

Re*

Figure4 kBT −1 = ln( zm / zT ) .vs. Re* for various Taero .

[3] are also plotted in Fig 3. Model parameters of
this are d / H , frontal area index, and thearrangement (staggered or square). It reproduces
reasonable results. As the first approximation, theexisting model is sufficiently valid.
Estimation of roughness length for heat is moredifficult than that for momentum, because Taero isanother unknown for the estimation. In this paper,
three types of the representative surface temperature( TR , radiation temperature: derived from emitted
long wave radiation from the surface, TC , complete
surface temperature: area weighted surface
temperature, and Teff , effective surface temperature:area and local heat transfer coefficient weighted
temperature [1]), and the air temperature inside thecanyon space( Tsc screen temperature: airtemperature measured at 0.5H) were examined for
Taero .
Fig.4 shows the ratio of roughness length formomentum to heat against roughness Reynolds
number defined as Re* = zmu* /ν , where ν ismolecular viscosity. The estimates of zT by
substituting the surface temperatures for Taero havedependency on roughness Reynolds number, while
the estimates by Tsc doesn’t. This result means zTderived from the surface temperatures has
dependency on scale, strength of wind shear, andmolecular viscosity. MOS framework is not valid forthem because they depend on the state of the flow.
On the other hand, zT from the screen temperature
has no dependency on Re* and thus, MOS
framework is valid.

10000

100000 10

10000

100000Re*

Each character is defined in the text.

Turbulent flow similarity between real surface layer
and the scaled models in open air was investigated.
Momentum transfer in unstable condition does notfollow the existing similarity theory due to the effectof outer layer phenomena. In near neutral case,similarity theory generally holds. For sensible heattransfer, it holds in unstable case, and is obscure inneutral case.
Based on the discussion above, roughness length
for momentum and heat were calculated and its
behaviour was investigated. Roughness length formomentum is sensitive to the surface configurationin this building density. Roughness length for heat
derived from the surface temperature depends onroughness Reynolds number and thus beyond theframework of similarity theory. Whereas roughness
length for heat derived from the screen temperature
is independent of roughness Reynolds number andscalable by roughness length, and thus, it is withinsimilarity framework.
Reference[1] Kanda,M., Kawai,T., Kanega,M., Narita,K., andHagishima,A., 2005: A Simple Energy Balance
Model for Regular Building Arrays. Boundary
Layer Meteorology, 116, 423-443.
[2] Kaimal,J.C., and Finnigan,J.J., 1994:
Atopmospheric Boundary Layer Flow (Their
Structure and Measurement), Oxford University
Press.
[3] Macdonald,R.W., Griffiths,R.F., and Hall,D.J.,
1998: An Improved Method for the Estimation ofSurface Roughness of Obstacle Arrays.
Atmospheric Environment, 32, 1857-1864.

5. Conclusion

110Technical Report of International Development Engineering

TRIDE-2006-01, February 20, 2006 (ISSN 1880-8648)

OBSERVATION STUDY ON WATER AND HEAT TRANSFER PROCESSESIN URBAN SEWAGE SYSTEM
Student Number: 04M18156

Name: Yu NAKAYAMA

Supervisor: Manabu KANDA

都市下水道による水・熱輸送過程に関する観測研究中山 有
近年、都市の過密化・拡大に伴いヒートアイランド現象をはじめとした熱環境の悪化が明らかになっている。本研究では都市において利用された水・熱が都市下水道を通じてどのように水圏へと流出していくのかを明らかにするために 2 つのスケールで観測を行った。1 つは水・熱利用の起点となる住宅地における観測であり、もう 1 つは都市全体で利用された水を集める下水処理場での観測である。観測の結果、住宅地および都市全体における年間水・熱フローが明らかになり、都市の水・熱環
境における下水道の役割が判明した。

1

Introduction

2.1

The expansion and concentration of urban areas cause
the urban environment degradation, e.g. revealed as heatisland phenomena. Many researchers have reported on
the anthropogenic heat impact to the atmosphere, while
few researchers have reported on the impact to the hydrosphere. However, the temperature of water discharged
from wastewater treatment plant (WWTP) has been increasing for the past 35 years [1] and the discharged water may harm the environment of the hydrosphere suchas rivers and the sea adjacent to an urban area.
The water transfer and heat transfer in urban areas
consist of not only meteorological fluxes like net radiation and sensible heat flux, but also underground fluxes
like tap water and sewage. Such an artificial drainage
system represented by tap water and sewage is one of
the major features of urban areas.
Moriwaki and Kanda have pointed out that surface
water and heat flux impact on the atmosphere in an urban residential area [2], but how the fluxes contributeto an artificial drainage system was unknown. Thus, twoscale observations were executed to study water and heatflow processes in the drainage network. First, the waterand heat balance was observed in a residential area thatgenerates the origin of wastewater flow [3, 4]. Second,
water and heat transfers were observed at WWTP targeting whole urban area. Based on these observations, thisthesis describes the estimation of anthropogenic heat due
to water use, and the water and heat transfer processes inan urban drainage system.

Outline of the Observations

Observations were conducted in the residential area of
Kugahara, Ota-ku, Tokyo metropolitan. At first, the flowrate and temperature of sewer were measured downstreamof a catchment to evaluate water and heat flux discharged
from the residential area (Fig. 1). The catchment area is12-ha and 1830 residents live in 407 dwellings in thisarea. Analysis of aerial photographs and GIS data showthat 34 % of the land cover in this area is pervious, while
66 % of it is impervious. Combined sewer system havebeen developed in the catchment. Moriwaki and Kanda
have already observed meteorological flux by tower-based
measurements a tower (Meteorological measurement site
on Fig. 1).
Rain is one of the major inputs of water and heat tothe catchment. Therefore, the hydrological measurementsite has been set in a vegetated field near the catchment,
where precipitation and air temperature are observed. To
evaluate the water storage of pervious area and measure
the soil temperature, soil moisture sensors and temperature sensors have been set at 6 depths from the ground to
the depth of 2 m.
Tap water is another major input, and the corresponding data is provided by the bureau of waterworks, Tokyo
metropolitan government.

2.2

Water Balance in a Residential Area

Water flow in a residential area can be devided into two
drainage systems; an artifical drainage system (ADS)
and a natural drainage system (NDS). The artificial drainage system consists of water supply pipes, residence and2 Water Balance and Heat Balance sewage pipes that receive tap water as input and discharge sewage as output. The natural drainage system
in a Residential Area
comprises underground soil that receives rain as input
Residential water use dominates the most of urban water and discharges evapotranspiration, leaching water anduse. Therefore a residential area was chosen as an origin surface runoff into sewage pipes as output (Fig. 2). The
for the measurement of the water and heat balance in an different drainage systems and its constituents can be deurban area.
scrived by equation (1) and (2) respectively.
ADS:
111

QI + QGW + QS = QO

(1)

Technical Report of International Development Engineering

TRIDE-2006-01, February 20, 2006 (ISSN 1880-8648)
Unit: mm year

Rain Q
1691

-1

N

R

Water Use

Evapotranspiration Q
261

E

Advection Q

1663

Meteorological
Measurement SiteA

Tap Water

Q

Surface Runoff

I

Wastewater Q
1663

I

Q

S

650

Change in water storage

123

dS/dt
-26

Leaching water Q
930

GW

Sewage pipe

Catchment

3243
Total Runoff

Q

Sewer
Measurement
Site

O

Figure 2: Annual water balance in residential area, 2004
now only set on the heat flow within an artifical drainage system. The heat balance equation of the artificial
drainage system is analogous to the water equation (1):

0

300m

Hydrological
Measurement Site

HI + ∆HU + HGW + HS − ∆HG = HO

Figure 1: The arrangement of measuring instrument
dS
+ QA
(2)
dt
where QI is tap water, QGW is leaching water from soil
to sewage pipe, QS is surface runoff, QO is total runoff,
QR is rain, QE is evapotranspiration, dS/dt is the change
in water storage and QA is advection flow. Combining
the two equations, we can express the whole drainage
system (WDS) as equation (3).
NDS: QR = QE + QGW + QS +WDS: QR + QI = QE + QO +

dS
+ QA
dt

(3)

All parameters are calculated for every month. The
following parameters are known: QI from the bureau ofwaterworks, QO , QR , QE and dS/dt from the observations. The unknown parameters, QGW , QS and QA are estimated as below. To calculate QGW , QO is averaged overone month excluding rain times. Thus QS in equation (1)becomes equal to zero, and QGW can be calculated. The
threshold of no rain time is defined as is less than 1mm
precipitation during the previous 12 hours. Assuming
QGW is constant when it rains or not, QS can be calculated from equation (1). QA is calculated as the residualof equation (2).
As a result, the annual water balance in residential
area is revealed (Fig. 2). The input water, tap water andrain have approximately the same magnitude. Seweragetransfers not only wastewater from residences but also
46% natural water QGW and QS . When it doesn’t rain
sewage still contains 27% QGW , so that the sewerage has
a function (1) of an underground river. The same situation happens in Sapporo city, the sewage contains about
30% of ground water [5].

(4)where HI is the heat of tap water into the system, ∆HU isheat added by the water use, HGW is the heat that leaching water takes from the soil into the sewage pipe, HS
is the heat that the surface runoff takes into the sewage
pipe, ∆HG is the heat conducted from sewage out of thepipe, HO is the heat that the sewage takes away from thesystem (Fig. 3).
To define each heat flux, it is neccesarry to set a reference temperature. Tap water temperature TI is taken
as the reference temperature because the objective is toestimate the heat added by using water and tap water isthe input of artificial drainage system. Thus, each heat
flux is defined as below.
∆HU = ρ c p QI (TU − TI )HGW = ρ c p QGW (TGW − TI )HS = ρ c p QS (TS − TI )HO = ρ c p QO (TO − TI )

(5)
(6)
(7)
(8)

where ρ c p is the heat capacity of water (= 4.19 × 106 J
m−3 K−1 ), TU is temperature of used water, TGW is leaching water temperature, TS is the temperature of surface
runoff, TO is temperature of total runoff. Of course, HI =0. ∆HG is driven by the difference between the sewage
temperature and the soil temperature. Thus, the sewage
temperature before heat conduction TO0 is expressed as
equation (9).
(TO0 − TG ) · exp(−kt) = TO − TG

(9)where k is a coefficient, t is the time at that wastewaterreaches the observation point. ∆HG is defined as below.
∆HG = ρ c p QO (TO0 − TO )(10)

HO consists of known data. If the observed soil temperature is used as TGW and TG , HGW and ∆HG can becalculated. If it doesn’t rain, ∆HU is calculated from
2.3 Heat Balance in a Residential Area
equation (4), if it rains, ∆HU is assumed as the same as
The heat flow in connection with water flow in a residen- in the no rain case, while HS is calculated then.
As a result, the heat added by water use is up to 0.7 W
tial area is similar to that of the water flow. The focus is
m−2 in summer and 3.4 W m−2 in winter and each value
112

Technical Report of International Development Engineering

TRIDE-2006-01, February 20, 2006 (ISSN 1880-8648)

Unit: W m

-2

MiyagiTreatment Area Nakagawa
Shingashi WWTP
Treatment Area
Ukima WWTP

Added heat by water use

∆HU

0.44
Tap water

HI=0

Shingashi
Treatment Area

Surface Runoff

HU

Wastewater
0.44

Mikawashima WWTP
Mikawashima
Kasai
Treatment Area
Treatment Area
Ochiai WWTP
Sunamachi
OchiaiTreatment
Area
Treatment Area
Shibaura
Shibaura
Treatment
Treatment Area
Area
Sunamachi
WWTP
Kasai WWTP
Shibaura
WWTP
Morigasaki
Ariake WWTP
Treatment AreaHS

Nakano WWTP

0.019
Leaching water
Sewage pipe

Nakagawa WWTP

KosugeTreatment Area
Kosuge WWTP

Miyagi WWTP
WWTP
Miyagi

HGW

-0.25

HG

Heat conducted from sewer to soil ∆

0.15
0.016

Total Runoff

HO

Figure 3: Heat balance in residential area in July

Kugahara

Tokyo Bay

Tokyo Bay

Unit: W m

-2

Morigasaki WWTP

Added Heat by using Water

∆HU

1.93
Tap water

HI=0
HU

Wastewater
1.93

Figure 5: Wastewater treatment plant(WWTP) map

Surface Runoff

HS

0.011
Leaching water
Sewage pipe

HGW
3.28

1.37

HG

Conduction Heat from Sewer to soil ∆

0.002

10.8
1827

8.89
1498
3.59
604

Rain QR

Surface Runoff QS

10.8
1827
Urban Area Wastewater
Tap Water
QI
QI

Total Runoff

HO

Figure 4: Heat balance in residential area in January

Evapotranspiration QE

3.82
644

R
ive
ra
nd
WWTP
S
Influent QTP1 Effluent QTP2 ea
0.74
125

18.2
3075

Total Runoff QO

Water Use
Unit
Upper: x108 m3 year-1
Lower: mm year-1

Pumping discharge QP
Pumping Station

Leaching
Water QGW

17.5
2950
0.45
77

17.0
2873

Sludge and Reclaimed Water QL

is equivalent to 3.2% of the whole anthropogenic heat insummer and 10% in winter (Fig. 3, 4). In summer, cold
Figure 6: Annual water balance in whole urban area
leaching water from the soil into the sewer pipe dilutes
the sewage heat, whereas in winter, warm leaching water
gives heat to the sewage.
water. However, when it rains, a part of the total runoff isdischarged to directly rivers or the sea via pumping sta3 Water Balance and Heat Balance tions without having been treated to drain a large amountof rain. Thus, the water flow downstream of an urban
in the Whole Urban Area
area can be expressed by equations (11) and (12).
The used water reaches the WWTPs and is discharged tothe hydrosphere after it has been treated. The WWTPs
play a role of an interface between urban area and hydrosphere. Therefore, additional observations have been
conducted at WWTPs in an urban area.

3.1

Outline of the Observations

To estimate heat flux discharged from urban area, temperature sensors were set at all 13 WWTPs in the 23
wards of Tokyo metropolitan area. 8,396,000 residents
live in catchment area of 621.49 km2 . The set sensors
are the same as that used in the residential area observation. The flow rate of influents into WWTPs and effluents from WWTPs are provided by the bureau of sewerage, Tokyo metropolitan government.

3.2

Water Balance in the Whole Urban Area

QO = QTP1 + QP
QTP1 = QTP2 + QL

(11)
(12)

where QO is the total runoff (the same as in the residential area), QTP1 is the influent into WWTP, QP is thepumping discharge, QTP2 is the effluent from WWTP, QL
is the sludge and reclaimed water. As QTP1 , QTP2 and QP
are known, QO and QL can be calculated (Fig. 6).
As a result, the amount of tap water supplied in urban
area is larger than the amount of rain, i.e. the urban area
receives some amount of water from outside of the urban
area and the urban area isn’t sustainable by rain falling
down only the area (Fig. 6). Natural water QGW and
QS is 35% of the total runoff QO which is similar to theobservations in the residential area.

3.3

Heat Balance in the Whole Urban Area

The water flow in the whole urban area is basically thesame as that in the residential area. WWTPs and pump- When estimating the heat balance in the whole urban
ing stations exist downstream of the urban area. When area, the heat added in WWTP is different from the water
it doesn’t rain, all runoff flows into WWTPs and is dis- balance (equation (14)).
charged to river or sea after the treatment. A part of water
HO = HTP1 + HP
(13)
has been burned as sludge during the treatment processes
0
HTP1 + ∆HTP = HTP2
(14)
and another part of water has been re-used as reclaimed
113

Technical Report of International Development Engineering
Unit
Upper: TJ day
Lower: W m

-1

-2

Rain

0.47 Surface Runoff HS
0.009
61.2
1.19
Urban Area Wastewater
Tap Water
HI=0 Water Use HU
61.2
1.19

Leaching
Water HGW

4

Pumping discharge HP
Pumping Station

Total Runoff HO

24.0
0.47

0.29
0.006

11.3
0.22

Added Heat in Sludge and Reclaimed
WWTP ∆HTP Water HLHeat conducted fromsewer to soil ∆HG

Figure 7: Heat balance in whole urban area in August
Unit
Upper: TJ day
Lower: W m

-1

-2

Rain

3.9 Surface Runoff HS
0.076
146
2.84
Urban Area Wastewater
Tap Water
HI=0 Water Use HU
146
2.84

16.1
0.31

Heat added bywater use ∆HU

0.13
0.003
16.3
0.32 Pumping discharge HP

Evapotranspiration

Pumping Station

Leaching
Water HGW

150
2.92
Total Runoff HO

Heat conducted fromsewer to soil ∆HG

Ri
ve
ra
nd
WWTP
S
Influent HTP1 Effluent HTP2 ea
149
2.92

-0.17
-0.003

144
2.82

5.0
0.097

Added Heat in Sludge and Reclaimed
WWTP ∆HTP Water HL

Figure 8: Heat balance in whole urban area in February
0
HTP2= HTP2 + HL

Conclusions

The water balance and heat balance in a residential area
are estimated, and the following results were obtained byobservations.
1. Leaching water from soil into sewer pipe dominates 27% of the whole wastewater.
2. The heat added by the use of water amounts to
0.7 W m−2 in summer and 3.4 W m−2 in winterand each value is equivalent to 3.2% of whole anthropogenic heat in summer and 10% in winter,
respectively.
3. In summer, cold leaching water from the soil into
the sewer pipe dilutes the heat added by the useof water, whereas in winter, warm leaching water
gives heat to the sewage.

Ri
ve
ra
nd
WWTP
S
Influent HTP1 Effluent HTP2 ea
12.9
0.25

13.0
0.25

31.6
0.62

Heat added bywater use ∆HU

0.06
0.001

Evapotranspiration

-17.0
-0.33

TRIDE-2006-01, February 20, 2006 (ISSN 1880-8648)(15)

The water transfer and heat transfer in the whole urban area are estimated by observation as follows.
4. The heat added by water use in urban area during
one year amounts to 9.1% of whole energy use.
5. The process of heat flow in sewage is revealed.
In summer, the sewage loses its heat by conduction from the sewage out of the pipe and gains
heat at WWTP. Totally, the sewage system reduces
the heat and is discharged. In winter, both theconducted heat and the heat added in WWTP aresmall. Thus the sewage system doesn’t change theheat.

where HO is the heat, the sewage takes away from theurban area, HTP1 is the heat influent to WWTP, HP is theheat drained at the pumping stations, ∆HTP is the heat0
is the sewage
added during the treatment in WWTP, HTP2
heat after treating, HTP2 is the heat effluent from WWTP
to the hydrosphere. HL is going out of WWTP as evap- Referencesoration by burning sludge and as reclaimed water. They
are defined by equations (16)-(21).
[1] Tsuyoshi Kinouchi. Long-term trend in thermal impact of urban water use on the receiving water - Case
(16)
HTP1 = ρ c p QTP1 (TTP1 − TI )study of the sewerage system in the central Tokyo
HP = ρ c p QP (TP − TI )(17)
area and the Tokyo bay -. J. Hydroscience and Hydraulics Eng., Vol. 47, pp. 25–30, 2003.
∆HTP = ρ c p QTP1 (TTP2 − TTP1 )
(18)
0
HTP2
= ρ c p QTP1 (TTP2 − TI )HTP2 = ρ c p QTP2 (TTP2 − TI )HL = ρ c p QL (TL − TI )

(19)
(20)
(21)

[2] Ryo Moriwaki and Manabu Kanda. Radiation, Heat,
Water Vapor and CO2 Fluxes in an Urban Surface
Layer. J. Japan Society of Hydrology and Water Resources, Vol. 16, No. 5, pp. 477–490, 2003.

where TTP1 is the influent temperature into WWTP, TP is[3] Tsuyoshi Kinouchi, Yu Nakayama, Ryo Moriwaki,
the drained water temperature at the pumping stations,and Manabu Kanda. Investigation and modeling
TTP2 is the effluent temperature from WWTP, TL is theof water and heat transport in an urbanized catchesludge and reclaimed water temperature. The observed
ment - Based on hydro-meteorological monitoring
temperature at influent point in WWTP is used as TTP1
data collected in the Kugahara Experimental Site -.
and TP , the other observed temperature at effluent point
J. Hydroscience and Hydraulics Eng., Vol. 48, pp.
in WWTP is used as TTP2 and TL .
175–180, 2004.
As a result of the calculation, the heat added by water use in urban area for one year amounts to 9.1% of the [4] Yu Nakayama, Manabu Kanda, Tsuyoshi Kinouchi,
whole energy use. The process of heat flow in sewage isand Ryo Moriwaki. Observation Study on Water andrevealed. In summer, the sewage loses its heat by conHeat Transfer in Urban Sewage System. J. Hydroduction from the sewage out of the pipe and gains heatscience and Hydraulics Eng., 2006. accepted.
at WWTP. Totally, the sewage system reduces the heatand is discharged (Fig. 7). In winter, both the conducted [5] Yukio Hosoya. Sapporo-shi no chikasui shinsui
boushi taisaku jigyou ni tsuite. J. Japan Sewage
heat and the heat added in WWTP are small. Thus theWorks Association, Vol. 22, No. 249, pp. 112–123,
sewage system doesn’t change the heat (Fig. 8).
1985.

114

Technical Report of International Development Engineering

TRIDE-2006-01, February 20, 2006 (ISSN 1880-8648)

Airport Capacity Analysis considering Terminal Air Traffic Flow
Control and Airlines’ Aircraft Sizing Behavior
Student Number: 04M18191

Name: Naoki YAMADASupervisor: Tetsuo YAI

空港管制とエアラインの行動からみた空港容量拡大に関する研究
山田直樹
わが国では航空需要の増加に対し，滑走路の新設等ハード面からの空港容量拡大によって対応してきており，管制方法やエアラインの行動の変化による容量増加等，ソフト面からの対策はあまり考慮されてきていない．本論文では，国内最大の混雑空港である羽田空港を対象として，容量拡大のための新たな管制方法とそれに対応した統計的容量算定方式の提案をし，さらに空港容
量算定シミュレーションを活用し複数滑走路のインタラクションを考慮した容量拡大についても分析を行った．最後に，空港容量に大きな影響を与える機材構成について羽田空港再拡張後のエアラインの機材導入行動をモデル化し予測した．

1

leading aircraft.
Secondly, the total capacity of
HANEDA Airport after the new 4th runway construction(called re-expansion) was estimated by using the micro
simulation (4) which can reproduce terminal air traffic
flow in an airport with multiple runways when theseveral capacity enhancement scenarios were
implemented. Finally, airlines’ aircraft sizing behavior
after the expansion of HANEDA was analyzed since theaircraft mix in the future is also important for estimating
capacity.

Introduction

The demand of air transportation in Japan has
increased steadily in recent years. The airport capacity
has been improved mainly by developing infrastructuresuch as runway expansions. From the viewpoint ofairlines, they have coped with the growth of air
passenger demand by enlarging aircraft size.
In several foreign countries, airport capacity has beenenhanced also by implementing flexible terminal air
traffic control considering the aircraft size mix inaddition to infrastructure improvements. Aircraft
characteristics such as runway occupancy time,
separation minima are different for each aircraft size. It
is therefore important to consider these characteristics
when considering airport capacity. Many academic
researches also focuses on how to improve the capacity
by flexible air traffic control (1)(2)(3), but there are few
researches of air traffic control for improving capacity inJapan.
Interaction ofmultiple runways
Multiple-Runway

Chap.2.2-2.3

Chap.2.4

Separation
ROT

Operation

Aircraft-Size

Airport capacity enhancement by flexible
terminal air traffic flow control

2.1

The current calculation method of airport
capacity in Japan 5)

This section shows the current calculation method of
airport capacity of HANEDA Airport by Ministry ofLand, Infrastructure and Transport (MLIT).
In
HANEDA, a takeoff and landing aircraft are basicallyoperated separately in two runways before re-expansion.
Since the runway capacity of landing is smaller than thatof take-off, the total runway capacity is determined by
the landing capacity (the number of landing and take-off
aircraft should be the same). Therefore, the runway
capacity of landing is only shown below.
The runway capacity is basically determined by thelarger separation shown below;(a) The separation of the arrival aircraft in final
approach（’Terminal radar control separation’ or‘Wake turbulence separation’）,(b) Runway occupancy time (ROT) which means thetime duration of passing through 1NM from runway
threshold to end of exit-way.
Here, (a) is currently defined as 120 seconds regardlessAirport Capacity

Single Runway

2

Chap.3

Fig.1 Relation of runway capacity and aircraft size
With these backgrounds, first, this paper proposed a
new method for calculating capacity corresponding to theflexible terminal flow control where the separation
between two successive landing aircrafts is changed
depending on the runway occupancy time (ROT) of the115

Technical Report of International Development Engineering

TRIDE-2006-01, February 20, 2006 (ISSN 1880-8648)

of aircraft size mix, and (b) is defined as the sum of thethree kinds of time duration as follows (also see Fig. 2).
①30.0 (sec): the passage time of the distance of 1(NM)before the runway threshold, which is the time duration
required to direct Go-Around when the leading aircraft
still remains in runway (t1);② 79.5 (sec): time duration between the runway
threshold and the runway lateral edge at exit, which is
calculated by summing 60 seconds of average and 19.5
seconds (2.6 times of 7.5 seconds of standard deviation)(t2);③15.0 (sec): time duration between the runway lateraledge (start point of exit-way) and stop line (end point ofexit-way) (t3)①+②+③= 124.5 (sec)
Because of Time (a) < Time (b), the runway capacityof landing is 3600/124.5=28.9≒28 (movements / hour).
However, the latest declared capacity by MLIT is 30(movements / hour) since t2 becomes 77 (sec) and t1
becomes 27 (sec) in the recent field survey of ROT in
HANEDA Airport.

t2

t1

2.3

If ROT is less than 120 (sec), the flying separation atterminal area will become a bottleneck because it isdefined as 120 (sec) uniformly. However, the ROTwith the proposed new air traffic control may not be over120 (sec). Therefore, we must consider also thecapacity based on the flying separation at terminal area.
According to the Air Traffic Control Standard, theseparation is different depending on the combination of
the size of successive aircrafts as shown in Table 2.
However, in the present condition, management of theseparation by the wake turbulence according to aircraft
size is not performed. The flexible separation control
might give the air traffic controller more workload.
However, the flexible separation control is actually
performed in several foreign countries such as Los
Angeles international airport (LAX). Figure 4 shows
the time separation of each aircraft size combination in
LAX and HANEDA and Table 3&4 show the statistical
test of the separation difference. From these results, we
can see that LAX actually performs the flexible
separation control. Therefore, HANEDA also has apotential to perform the flexible control although thecurrent separation in HANEDA is uniform.
Average separation when considering the flexible
separation control can be less than 120 (sec) because theseparation after the medium size aircraft is around 90(sec). Therefore it might not be the bottleneck todetermine the capacity. However, the speed difference
and the runway exit position depending on aircraft size
are also necessary to consider all together. These
factors are considered in the next section.

1NM

Fig. 2 Runway occupancy time classification on runway
of arrival aircraft

2.2

Proposal of a new terminal air traffic
control and corresponding calculation
method of capacity

In this section, we proposed a new flexible terminal
flow control where the separation between two
successive landing aircrafts is changed depending on the
ROT of the leading aircraft. And we showed also themethod for calculating capacity corresponding to the new
air traffic control.
①present

A8A6？
＊① ＝ ② + ③③
Newconcept

A8

②

③
A6

Examination of flying separation interminal area

4-5NM
6NM

Fig.3 Concept of new terminal air traffic flow control

Table.2 Separation distance of wake turbulence
leading airdraft following aircraft separation(NM)
Heavy
Heavy
4
Medium5
MediumHeavy
3
Medium3

Table.1 Estimated runway capacity
The exit position of an arrival aircraft that are A6 andA8 exit (see Fig.3) can be grasped in advance in general

200

Capacity
/hour
30.29
29.35

200

LAX

150
sec

New concept
Present

ROT+Safetymargin118.84122.66100
50

according to the aircraft size. Based on this premise,the separation of two successive landing aircrafts can be
set 4-5NM when the leading aircraft is expected to use
A6 exit (prior exit), and 6NM when the leading aircraft is

HANEDA

150
sec

t3

expected to use A8 exit (secondary exit).
This flexible air traffic control enables shortening ofvariation of ROT which is considered for calculating
Time 2 (t2, see 2.1) because the variation of inter-group(here, group means exit A6 and A8) can be ignored bytaking the risk of its variation with different separation
mentioned above.
The result of calculating the landing capacity based on
this new method is shown in Table.1. The actual
observed data of ROT of each exit were used for thiscalculation. The result shows that this new air traffic
control can increase the capacity of 1 (movement/hour)comparing the current method.

100
50

0
H-H H-M H-S M-H M-M M-S S-H S-M S-S
coutinuous aircraft

0
H-H

H-M

M-H

M-M

coutinuous aircraft

Fig.4 Separation time at runway threshold（Los Angeles International Airport and HANEDA）
116

Technical Report of International Development Engineering

TRIDE-2006-01, February 20, 2006 (ISSN 1880-8648)(Operation 3) Segregation of runway usage according toaircraft size (only small aircrafts (B737) A-runway
landing and others landing to C-runway(D). (inoperation1, the separation of landing aircraft in
C-runway is larger than normal separation minima, so
aircraft mix has almost no effect on capacity in
C&D-runway. However landing of only small (medium)aircraft may have significant effect on capacity in
A-runway(scenario 3 ));Table.5 shows the results on each scenario. It was
shown that the capacity of the airport increased by eachscenario. Especially by operation 1 airport capacity
increase significantly because in MLIT plan there may be
still unused capacity in C-runway. Then figure 6 shows
relationship between airport capacity and aircraft size
composition. It shows the share of aircraft has
considerable influence to airport capacity. Therefore,
according to it and scenario3 the trend of aircraft size
mix in the future is also important for enabling
abovementioned flexible air traffic controls and effect toairport capacity. In the next chapter, we developed themodel of aircraft purchase behavior by airlines andanalyzed the future trend of aircraft size mix after
re-expansion on HANEDA Airport.

Table 3 Result of t-test about time separationdifference in HANEDA Airport
H-H

H-M
P=0.56

H-H
H-M
M-H

Table 4

M-H
P=0.48P=0.29Result of t-test about time separationdifference in LAX

P value H-H④ H-M⑤ H-S⑥ M-H③ M-M③ M-S④
H-H④
×0.011** 0.031** 0.016** 0.841 0.015**
H-M⑤
×
×
0.700
0.00* 0.002* 0.00*
H-S⑥
×
×
×
0.00* 0.014** 0.00*
M-H③
×
×
×
×
0.013** 0.862
M-M③
×
×
×
×
×
0.010*
M-S④
×
×
×
×
×
×
S-H③
×
×
×
×
×
×
S-M③
×
×
×
×
×
×
S-S③
×
×
×
×
×
×

2.4

M-M
P=0.28P=0.18P=0.59S-H③ S-M③ S-S③
0.007* 0.005** 0.027**
0.00* 0.00*
0.00*
0.00* 0.00*
0.00*
0.323 0.553
0.665
0.007* 0.003* 0.03**
0.252 0.418
0.571
×
0.589
0.647
×
×
0.996
×
×
×

Estimation of capacity enhancement after
HANEDA re-expansion by using air
traffic simulation system and by changing
aircraft size composition

In this section, the estimation of the airport capacity of
HANEDA with 4 runways (see Fig.5) is conducted byusing air traffic micro simulation system developed by
Hiramatsu (4). This simulation system can reproduce
the microscopic behavior of landing and take-off aircraftat terminal air flow control area and it is alreadyvalidated comparing with actual current capacity data.
This system is very useful to estimate airport capacity
because it can consider the interaction of multiple
runways and can change aircraft behaviors easily. Fig.5
shows also the planned capacity after re-expansion by
MLIT.
We first estimated the capacity when implementing the
new air traffic control introduced in section 2.2 and 2.3.
Secondly, we also designed the other two kinds of new
air traffic flow control and estimated the capacity withthose controls.
We hypothecated analysis scenarios as follow.

B

Analysis scenario and result of each scenario

Senario(Operation0): Separation Control considering Leading Aircraft's ROT(Operation1): Alternating Control of Landing and Take-off in C-runway

28 arrival/h

Base
○(A)
−

1
○(A)
○

2
○(A)
○

3
○(A)
○

−

−

−

○

○

(preventing large ROT caused by each airline's terminal building position)(Operation3): Segregation of Runway Usage according to Aircraft Size

−

−

−

−

○

28.0
12.0
12.0
28.0

30.0
10.8
20.0
20.4

30.1
19.0
24.9
24.9

30.2
19.0
24.8
25.1

32.1
18.2
25.4
25.4

40.0

40.9

49.1

49.2

50.3

40.0

40.4

49.8

49.8

50.7

(medium aircraft in A-runway and heavy aircraft in C-runway)

Landing in A-runway
Landing in C-runway
Take-off in C-runway
Take-off in D-runway
Landing -TOTAL
Take-off - TOTAL

Estimated
Capacity(movements/ hour)Aircraft-size Mix and Capacity of HANEDA Airport
with runway segregation by airline

53.0

28 departure/h

C

A

MLIT
−
−

(Operation2): Segregation of Runway Usage according to Airlines

Airport Capacity (landings / hour

12 departure/hTable.5

without runway segregation by airline

52.5

without runway segregation by airline with runway
segregation by aircraft

52.0
51.5
51.0
50.5
50.0
49.5
49.0
48.5
0%

D

20%

40%

60%

80%

100%

Rate of Medium-size Aircraft (%)

Fig.6 Result of Aircraft size mix and airport capacity

12 arrival/hin HANEDA Airport

Fig.5

3.

Arrival and Departure route after re-expansion
in HANEDA(Operation 0)In A-runway landing separation control
considering leading aircraft’s ROT which introduced in
section 2.2&2.3 (All scenario except Mlit plan);(Operation 1)Separation control of landing aircraft in
C-runway for alternating control of landing in C-runway
and take-off in each C- & D-runways; (Basicallyalternating control of landing and take-off might be mostefficient in one runway, so the landing separation in
C-runway is controlled based on the minimum separation
required for take-off in C & D-runway between landing
aircrafts of C-runway)(scenario 1, 2, 3);(Operation 2) Segregation of runway usage according toairlines (the airlines which use Terminal1 is landing in
A-runway and which use Terminal 2 islanding in
C-runway )(if aircraft which uses Terminal 2 is landing
A-runway, this one tend to use far runway exit and takelonger time than using C-runway)(scenario 2, 3)

Model analysis of airline’s aircrafts
purchase behavior after HANEDA
re-expansion

Officially, further expansion of the capacity of
HANEDA airport is scheduled in 2009. I conducted themodel analysis of airlines’ aircraft sizing behavior tounderstand the trend which airlines purchase and holdaircrafts after the expansion.

3.1

Model

We assume that there are two homogeneous airline
industries in the market. Airlines seek to maximize thenet present value over 20 years. The timing of decisionpurchasing aircrafts of airline is year 2007, by which I
take into account the duration for the education of pilot
and time lag between order and delivery of aircrafts. I
also assume that airlines have the two options for117

Technical Report of International Development Engineering

TRIDE-2006-01, February 20, 2006 (ISSN 1880-8648)

purchasing aircrafts. The first option is carried out in2009 when HANEDA Airport will be re-expanded.
The second option is exercised in 2014, five years’ laterof HANEDA’s re-expansion. Except for these twotimings, airlines can neither purchase aircrafts nor
increase flight volume. All purchased aircrafts are used
for service.
I assume that the three strategies of airlines forpurchasing aircrafts for simplification.
1. Purchasing large-sized aircrafts
2. Purchasing small-sized aircrafts
3. Deferring purchase for aircrafts
When airlines purchase new aircrafts, they will decide
the number of purchased aircrafts so that they can shipten million passengers per year. I set the number ofseats of large-sized aircrafts is 400 people assuming they
are B747 or B777, while those of small-sized aircrafts
are 100 people assuming that they are B737 or RJ.
Annual average Load Factor (LF) is fixed to be 70%.
When the traffic volume which will be assigned bylogit-based passenger demand model exceed the number
of offered seats in the future, airlines’ will choose one of
the following two options: (1) changing small-sizedaircrafts to large-sized aircrafts; (2) abandoning theexcess demand (which will assumed to shift to othertravel modes).
Assume strategy of aircraft perchance

Calculating average seatsno
Change small size aircraft to large

profit of overflow＞
profit of change aircraft

60
40
Small aircraft
Large aircraft

20
0
period 1

5

7

airlineflight volumes of airline

40

Small aircraft
Large aircraft

20

9

11

13

15

17

19

period 1

3

5

7

9

11

13

15

17

Perchance Strategy
B

Large Large Large Small Small Small Deferring Deferring Deferring

Large Small
Large Deferring
Small
Small

yes

Large
Small

Max Min solution

Small Deferring
Deferring Large

Decision of aircraft possessions

Deferring Smallt>TDeferring

Distribution ofslots divided into 2 times

Large Large

t=t+1

Pareto optimality
Considering
LCC to entry

Deferring DeferringnoyesCalculating
profit according to strategy

Fig.9

4

Calculating net present value

Optimal strategy

Conclusion

calculating Max-Min strategy solution

The result of this research is the following two points.
・ The new terminal air traffic controls for enhancing
the capacity were proposed.
・ The future aircraft size mix after HANEDA
re-expansion was analyzed by modeling airline’s
aircraft purchasing behavior.

Decision of airline’s strategy of aircraft purchase

Fig.7

3.2

19

Number of aircraft possession

A
Large Small DeferringLarge Small Deferring Large Small
Perchance Strategy

offering seats （ＬＦ７０％）＞Acquisition demand

Input aircraft possessions
to the next period

60

0
3

Fig.8

Calculating offering seats

yes

Number of aircraft possesion
Large-Small strategy

80

NumberNumber80

Calculating flight volume

no

100

Number of aircraft possesion
Small-Small strategy

100

aggregate demandflight volumes of other airline

Seats of large size aircraft and small size aircraft
Calculating aircraft possession

implies that unless two airlines try to purchases theiraircrafts in cooperation with each other, airline operatehighly-frequent career service with small-sized aircraft inorder not to lose share of slot to competitors. On theother hand, if airlines behave cooperatively, airlines
operate large-sized aircrafts with low cost per seat mile,
and with low frequency in response to demand increases,
keeping mint slots.
Now, we assume that the expansion of HANEDA will
be conducted at two-steps and the slots for airlines are
released 2 times. Fig.9 also shows the Max-Min
solution for such situation: purchasing large-sizedaircrafts at the first step and choosing small-sizedaircrafts to buy at the second. Pareto optimality is also
as same as slots released 1 times. It implies that if thegovernment increases the airport capacity by slow
degrees, airlines tends to upsize their aircrafts in earlier
stage.

Algorism for calculating airlines’ profit

Numerical Simulation

Each airline decides the type and the number ofpurchased aircrafts. Finally, their owned aircrafts andprofit will be calculated for each time period. Thistakes the form of a strategic game between competitive
two airlines and they will decide the optimal strategy
according to their NPV. The detailed procedure for thisis shown in Fig.7. Parameters for numerical simulation
are not shown due to limited space.
Fig.9 shows the equilibria (i.e. the combination of
Max-Min strategies) in two-person game for several
situations.
For the case where the expansion of
HANEDA will be conducted only in 2009 (single
expansion), the solution of the game is purchasing
small-sized aircrafts for each airline for each stage, while
Pareto optimality in this game is pass up at first stage andpurchase large-sized aircrafts at second stage.
It

Reference
1） Eugene P. GILBO [1993], “Airport Capacity: Representation,
Estimation, Optimization”, IEEE Transactions on Control Systems
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2） D.E.Pitfield, E.A.Jerrard [1999], Monte Carlo comes to Rome：a note on the estimation of unconstrained runway capacity at
Rome Fiumucino International Airport , Journal of Air Transport
Management, Vol.5, Issue.4, pp.185-192.
3） Matteo Ignaccolo [2003], “A Simulation Model for Airport
Capacity and Delay Analysis”, Transportation Planning andTechnology, Vol.26, No.2, pp.135-170.
4） Takeshi HIRAMATSU [2005], “Calculation Method of Airport
Capacity Considering Air Traffic Management and Aircrafts’
Noise”, Master's thesis of Tokyo Institute of Technology
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