bluuebunny/crossref_metadata_2025 huggingface dataset:
AFM for Preparing Si Masters in Soft Lithography
Authors: Zhao Xiao Li , Dong Shen , Liang Ying Chun , Sun T. , Yan Yong Da
Published: March 2009

Atom Force Microscopy (AFM) can be employed to create surfaces in Si substrate with recessed features. The resulting patterns can serve as masters to make the required elastomeric stamps for soft lithography. Morphology analysis of patterned features on Si substrate and polydimethylsiloxane (PDMS) stamp by AFM imaging confirms that pattern can be successfully transferred from Si substrates to PDMS stamps. It is shown that this method for creating masters can be performed with an AFM, making this method particularly straightforward, economical and accessible to a large technical community that are provided with AFM for measurement.
Microwave-Assisted Synthesis of MWO4 and MMoO4 (M = Ca, Ni) Nano-Powders Using Citrate Complex Precursor
Authors: Ryu Jeong Ho , Yoon Jong Won , Lim Chang Sung , Shim Kwang Bo
Published: March 2009

Nano-sized MWO4 and MMoO4 (M = Ca, Ni) powders, which have scheelite and
wolframite type structure, were successfully synthesized at low temperatures by a modified citrate
complex method assisted by microwave irradiation. The citrate complex precursors were heattreated
at temperatures from 300 to 600 °C for 3 h. Crystallization of the MWO4 and MMoO4
precursors was detected at 400 °C and completed at a temperature of 500 °C. Most of the MWO4
and MMoO4 powders heat-treated between 300 and 600 °C showed primarily spherical and
homogeneous morphology. The average crystallite sizes of MWO4 (M = Ca, Ni) were between 22
and 39 nm, and those for MMoO4 (M = Ca, Ni) were between 19 and 35 nm respectively, showing
an ordinary tendency to grow with temperature.
Synthesis of Nanotubular Titanate from Titanium Using Hydrothermal Treatment
Authors: Kubo T. , Kato W. , Yamasaki Yuki , Nakahira Atsushi
Published: March 2009

In this study, the synthesis of nanotubular titanate was attempted though heat-treatment
in an oil bath (non-hydrothermal treatment), heat-treatment with stirring in an oil bath
(non-hydrothermal treatment), or hydrothermal treatment for metal Ti in NaOH aqueous solution
systems. Obtained products were characterized by various methods, such as X-ray diffraction
(XRD), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). XRD
results suggested that products obtained by both hydrothermal treatment and heat-treatment in an oil
bath with and without stirring could be identified as H2Ti4O9H2O. From TEM observations,
however, various morphologies for products obtained by these treatments were confirmed.
Therefore, it was considered that morphologies of these products strongly depended on synthesis
conditions.
Thermal Evolution of Single Phase Lanthanum Zirconate
Authors: Jarligo Maria Ophelia D. , Kang Y.S. , Kawasaki Akira
Published: March 2009

Lanthania (La2O3) and zirconia (ZrO2) powders in ethanol based suspension were mechanochemically treated in a planetary ball mill for 12 hours at 200 rpm, dried and sintered at various temperatures from 400 to 1500. Particles in nanometer sizes are produced after milling. X-ray diffractometry results show the formation of single phase lanthanum zirconate on subsequent heat treatment for 1h at 1500. Phase evolution based on the intensities of the XRD plots and BET surface area analysis indicates three stages of crystallization: below 800, between 800 and ~1100, and above 1100 where reflections of La2Zr2O7 with pyrochlore structure are increased with further heating. Only endothermic energy peaks are observed in the differential thermal analysis (DTA) curve of the milled powders, which could be attributed to the reactions involving dehydroxylation, decarboxylation and complete disintegration of ethanol. This indicates that probably, lanthanum zirconate has grown on sintering at high temperatures from the very fine particles produced by mechanochemical activation during milling. Thermogravimetric analysis has recorded a total weight loss of ~9% from the original weight of the milled powder on sintering at 1500. The values of the surface area of the powders are found to decrease while the crystallite size of La2Zr2O7 are increased with increasing temperature.
Estimation of Thermal Shock Resistance by Infrared Radiation Heating and Water Flow Cooling Techniques
Authors: Honda Sawao , Tanaka Hiroaki , Awaji Hideo
Published: March 2009

Thermal shock is a mechanism often leading to failure of ceramic materials that may occur during rapid heating or cooling. These tests were performed in order to compare the thermal shock resistance of ceramic materials by cooling with that of the heating method and hence to evaluate parameters such as thermal shock strength (R1c) and thermal shock fracture toughness (R2c). During the present study, thermal shock resistance of alumina and mullite ceramics was estimated experimentally and theoretically using the thermal shock parameters. The critical thermal stress at the onset of thermal shock fracture was calculated using fracture time, which is measured by an acoustic emission. Results show that thermal shock parameters of alumina specimens decreased with increasing temperature of fracture point. This effect can be attributed to the temperature dependence of the thermal properties. The experimental values of thermal shock parameters evaluated by IRH and WFC techniques were in good agreement at the temperature of fracture point. The thermal shock parameters enabled the definition of a unified thermal shock resistance of ceramics, which is independent of the nature of the testing techniques.
Analysis of Internal Friction on Silicon Nitride with Visco-Elastic Model
Authors: Sakaguchi Shuji
Published: March 2009

Temperature dependence of internal friction on silicon nitride ceramics with yttria and alumina sintering aids was discussed using 4-elements visco-elastic model. It is known that the internal friction of this ceramic material shows a characteristic peak at around 1040 oC and an exponential increase over 1200 oC. This temperature dependence of internal friction was well approximated with using parallel Maxwell model. The parameters for this model and the relaxation time on this model were obtained. The relaxation time was very short, compared to the transient creep deformation of this ceramics. The analyzed results on internal friction could not be related with the creep deformation.
Process Optimization for Nanostructured HVOF -Sprayed Al2O3-Based Ceramic Coatings
Authors: Turunen Erja , Varis Tommi , Gustafsson Tom E. , Keskinen Jari , Lintunen Pertti , Fält Teppo , Nowak Roman , Hannula Simo Pekka
Published: March 2009

Special mechanical properties have widely been demonstrated with bulk nanocrystalline
materials. An increasing effort has been made to transfer such improvements also into thermal
sprayed ceramic coatings. This paper focuses on such efforts in alumina-based ceramic coatings. The
optimization of process conditions and effect of different process parameters on the mechanical
performance of high velocity oxy-fuel (HVOF) sprayed ceramic coatings is discussed.
Ultrasonic Spray Nozzle System with Piezoelectric Ceramics for Water Treatment Applications
Authors: Koh Jae Seok , Lee Jae Chun , Cho Soon Haing , Choi Seung Chul
Published: March 2009

A new type of ultrasonic spray nozzle was fabricated employing PZT and Pb-free
piezoelectric device. The spray nozzle was designed to disperse chemicals in a water treatment
mixing tank. The piezoelectrics were packaged in an aluminum case with silicone resin for the
aqueous solution proof packaging. Chemicals were dispersed with high efficiency, and the
ultrasonic fine particle spraying was able to reduce the chemicals consumption. The removal
efficiencies of heterotrophic bacteria and Escherichia coli by chemicals injected using designed
ultrasonic spray nozzle were higher than the conventional methods.
High Damping in Ferroelectric and Ferrimagnetic Ceramics
Authors: Fantozzi Gilbert , Bourim E.M. , Kazemi Sh.
Published: March 2009

High damping materials exhibiting a loss factor higher than 10-2 are generally considered as polymer or metallic materials. But, it will be interesting to consider ferroelectric or ferrimagnetic ceramics, in which internal friction can be due to the motion of ferroelectric or magnetic domains. High level of internal friction can be obtained in these ceramics in a given temperature range. In the case of ferroelectric ceramics, hard ferroelectrics, such as BaTiO3 or PZT, can show some relaxation peaks below the Curie temperature due the motion of domain walls and the interaction between the domain walls and the oxygen vacancies or cationic vacancies. In the case of ferrimagnetic ceramics, some anelastic manifestations due to the ferrimagnetic domain walls appear below the Curie Temperature TC. These peaks are linked to the interaction of domain walls with cation vacancies or cation interstitials or the lattice. Above the Curie temperature, a relaxation mechanism due to the exchange of cations Mn3+ and their vacancies on octahedral sites should occur.
Damping Mechanisms in Oxide Materials and Their Potential Applications
Authors: Fang Qian Feng , Liu T. , Li Chun , Wang X.P. , Zhang G.G.
Published: March 2009

In this paper, we review the damping mechanisms in oxide materials, such as the short-range jump of oxygen vacancies and cation vacancies, movement of domain walls, and grain boundary sliding. Some examples in doped ZrO2, La2CuO4+δ, La2Mo2O9 and other oxide materials are briefly discussed, in which the damping capacity can reach as high as 30%. These oxides could be possibly applied as high damping materials either in the form of bulk components, or as additives in composites, or as hard damping coatings. In the last two potential applications, the high hardness and strength as well as high damping capacity of the oxides are simultaneously exploited, which cannot be realized by the usual high-damping metals and alloys.
Advanced Techniques for Determining High and Extreme High Damping: OMI - A New Algorithm to Compute the Logarithmic Decrement
Authors: Stanislawczyk A.
Published: March 2009

A new algorithm OMI (Optimization in Multiple Intervals) for the computation of the
logarithmic decrement from exponentially damped harmonic oscillations is described. This method
is shown to be effective and computationally compact for high damping materials. A comparison
between the OMI algorithm and the four classical methods usually used in the computation of the
logarithmic decrement is reported. The OMI algorithm yields high precision in the computation of
the logarithmic decrement and the smallest dispersion of experimental points on the plots of
mechanical loss spectra. The effect of the acquisition parameters and the experimental conditions on
the results of computations of the logarithmic decrement and the relative error is discussed.
Defect Structure in (Zn,Mg)O Films Prepared on YSZ Substrate
Authors: Ryoken Haruki , Sakaguchi Isao , Ohashi Naoki , Adachi Yutaka , Ohgaki Takeshi , Hishita Shunichi , Haneda Hajime
Published: March 2009

The defect structure of undoped ZnO and (Zn1-x,Mgx)O solid-solution films were deposited on
YSZ substrate with pulsed laser deposition (PLD) to investigate defect equilibria in those films. In
particular, the effects of thermal treatment on the structures and prosperities of (Zn1-x,Mgx)O
solid-solution films were examined. The films with high MgO concentration (x>0.12) decomposed
to the wurtzite-type and rock-salt-type phase after thermal treatment, indicating that the solubility
limit of Mg was about x=0.12 and the wurtzite-type (Zn,Mg)O films with x>0.12 were indicated to
be non-equilibrium ones. The subsequent analyses of oxygen diffusivity in those films revealed that
the films under non-equilibrium state, i.e., wurtzite-type (Zn1-x,Mgx)O with x>0.12, contained
significantly high concentration of anion defects.
Synthesis and Characterization of BaTiO3 Nano-Particle by Aerosol Plasma Pyrolysis Process
Authors: Kodera Takayuki , Horikawa Hajime , Ogihara Takashi , Ogata Nobuo , Nakane Koji , Omura Suetaka , Uede Masao , Higeta Kazuya , Hiyama Susumu
Published: March 2009

Homogeneous BaTiO3 nano-sized powders were successfully prepared by spray pyrolysis using multiphase plasma under the air atmosphere. Particle size, morphology, crystal phase and crystallinity of as-prepared powders were characterized by SEM and XRD. The effect of starting precursor solution on the formation of nanoparticles was investigated. The use of Ba/Ti aqueous solution derived from malic acid led to formation of cubic BaTiO3 nanoparticles with 50 nm size.
Powder and Dielectric Characterization of Hydrothermally Synthesized Barium Titanate Nanopowders
Authors: Tokita Kouji , Sato Shigeki
Published: March 2009

Barium titanate (BaTiO3) particles with average size of smaller than 100 nm were synthesized by a hydrothermal process at 100°C to 300°C. The c- to a-axis ratios of the particles increased as the synthesis temperature increased. Disk capacitors were fabricated with as-synthesized particles and some additives to obtain X7R capacitors. The temperature coefficient of capacitance with particles synthesized at 100°C was much larger than that for 300°C, indicating that the former had uniform composition in the grain while the latter had a core-shell structure. This data show that barium titanate particles hydrothermally synthesized at high temperature are useful when creating the X7R capacitors with small grain size.
Influence of Annealing on Domain Structures of Bismuth-Titanate-Based Crystals
Authors: Katayama Shinichi , Noguchi Yuji , Miyayama Masaru
Published: March 2009

Influence of annealing on the domain structures of bismuth titanate (BiT) and rare-earth (La and Nd)-substituted BiT crystals (BLT or BNT) were investigated by optical microscope and piezoresponse force microscope (PFM). Annealing of BiT at 950°C in air significantly decreased the number of striped 90° domain walls, while charged 180° domain walls were still present in the crystals after the annealing. The annealing for the crystals of BLT and BNT at the same condition did not change their 90° domain structures. PFM observations indicated that antiphase domain boundaries in BLT play an important role in the formation of 90° domain structures.
Self Assemble Synthesis of Potassium Niobate at Room Temperature
Authors: Toda Kenji , Sugawara Akira , Uematsu Kazuyoshi , Sato Mineo , Osada Minoru
Published: March 2009

Nanoparticles and thin films of potassium niobate KNbO3 were prepared using a unique solution reaction at room temperature. Precursor solutions and as-prepared samples were characterized by Raman spectroscopy. The data demonstrated that the niobate nanosheets consist of distorted Nb-O polyhedra.
Fabrication and Electrical Characterization of Epitaxially Grown (Ba,Sr)TiO3 Thin Films Prepared by Sol-Gel Method
Authors: Hosokura Tadasu , Ando Akira , Sakabe Yukio
Published: March 2009

Epitaxially grown (Ba,Sr)TiO3 thin films were prepared on platinum-coated silicon substrate by sol-gel method using a (Ba,Sr)TiO3 sol derived from Ba(CH3COO)2, Sr(CH3COO)2 and Ti(O-i-C3H7)4. The morphology of the films was found to depend on the annealing condition. A columnar structure was obtained for (Ba,Sr)TiO3 thin film by annealing at 800 °C and a columnar grain was found to be single crystal by transmission electron microscope (TEM). The columnar grown film exhibits a preferred (111) orientation that follows the (111) orientation of Pt substrate. Measurement of the C-V in MFM was configured in order to demonstrate good dielectric properties. Obtained films showed high voltage tunability.
Functional Reorganization in Chronic Hemiparetic Patients after Training: fMRI Studies
Authors: Tae Ki Sik , Song Sung Jae , Lee So Young , Park Gi Young , Sohn Chul Ho , Kim Young Ho
Published: March 2009

The aim of this study was to evaluate effects of short-term repetitive-bilateral exercise on the activation of motor network using functional magnetic resonance imaging (fMRI). Eight control subjects and four chronic hemiparetic patients were investigated for the present study. The training program with a symmetrical upper-limb motion trainer was performed at 1 hr/day, 5 days/week during 6 weeks. Fugl-Meyer assessments (FMA) were performed every two weeks during the training. We compared cerebral and cerebellar cortical activations in two different tasks before and after the training program: (1) the only unaffected hand movement (Task 1), and (2) passive movements of the affected hand by the active movement of the unaffected hand (Task 2). fMRI was performed at 3T with wrist flexion-extension movement at 1 Hz during the motor tasks. All patients showed significant improvements of FMA scores in their paretic limbs after training. fMRI studies in Task 1 showed that cortical activations decreased in ipsilateral SMC but increased in contralateral sensorimotor cortex (SMC) and ipsilateral cerebellum (CRB). Task 2 showed cortical reorganizations in bilateral SMC, pre-motor area (PMA), supplementary area (SMA) and CRB. This study demonstrated that plastic changes of motor network occurred as a neural basis of the improvement subsequent to repetitive-bilateral exercises using the symmetrical upper-limb motion trainer.
Effects on Foot/Ankle Roll-Over Characteristics According to Different Heel Heights during Walking
Authors: Choi Hue Seok , Kim Han Sung , Kim Young Ho
Published: March 2009

This study investigated effects on foot/ankle roll-over characteristics according to heel heights during walking. Fifteen female volunteers who have neither musculoskeletal nor foot problems participated in gait analyses, wearing totally four pairs of shoes with different heel heights. To obtain roll-over shape of foot/ankle complex, we used trajectories of ankle, knee and the center of pressure (COP) between initial contact(IC) and opposite initial contact(OIC) to represent as circular arc using the least-square method. We found that the entire roll-over shape moved distally as the heel height increased but roll-over characteristics did not change significantly with different heel heights. In addition, we found that nondisabled persons automatically adapt their foot/ankle complex to changes in heel height shoes up to 6cm, by moving the origin of roll-over shape distally to keep the roll-over characteristics uniform. Roll-over characteristics in human walking would provide a new understanding of human walking, and furthermore can be applied to the design of prosthetics and orthotics of the lower extremity.
Development of an MR-Compatible ECG Amplifier
Authors: Chung Soon Cheol , Yi Jeong Han , Tack Gye Rae , Lee Bong Soo , Kwon Ji Hun , Kim Sin , Sohn Jin Hun
Published: March 2009

The purpose of the present study is to develop a magnetic resonance (MR)-compatible
electrocardiogram (ECG) amplifier. If ECG signals are measured simultaneously with the acquisition
of MR images, there can be a mutual interference effect. The present system was designed to block
noises caused by the main magnetic field, gradient magnetic field and radiofrequency (RF) pulse
when MR images are acquired. It uses analogue elements in order to remove any possible effect on
MR images. In addition, a radio-frequency-interference (RFI)-free optical data link using the
pulse-width modulation (PWM) technique is adopted in order to transmit ECG signals measured
inside the MR room.
Characterization of CMOS Pixel Detectors for Digital X-Ray Imaging
Authors: Cho Min Kook , Kim Ho Kyung , Graeve Thorsten , Kim Jung Min
Published: March 2009

In order to develop a cost-effective digital X-ray imaging system, we considered a CMOS
(complementary metal-oxide-semiconductor) photodiode array in conjunction with a scintillation
screen. Imaging performance was evaluated in terms of MTF (modulation-transfer function), NPS
(noise-power spectrum) and DQE (detective quantum efficiency). The presampled MTF was
measured using a slanted-slit method. The NPS was determined by 2-dimensional Fourier analysis.
Both the measured MTF and NPS, and a self-developed computational model for the X-ray spectral
analysis were used to determine the spatial frequency-dependent DQE. From the measured MTF, the
spatial resolution was found to be about 10.5 line pairs per millimeter (lp/mm). For a 45-kVp tungsten
spectrum, the measured DQE around zero spatial frequency was about 40%.
The Analysis of Slice-Induced Factors in Golf Swing Using a 3D Motion Capture System
Authors: Sim Tae Yong , Oh Seung Eel , Lee Sang Sik , Mun Joung H.
Published: March 2009

In golf, it is crucial that unintended shots, such as slices, be minimized. However, it has
proven rather difficult to improve golf performance via investigations of the causes of slicing, as this
particular phenomenon is induced by a cooperative effect by each segment of the body, rather than by
a single postural anomaly. Thus, the objective of this study was to isolate and characterize the factors
causing slicing, and to present possibilities for the improvement of golf performance via the
minimization of the number of slices executed, using a three dimensional motion capture system,
combined with multiple regression analysis, artificial neural network, and fuzzy logic techniques.
This study obtained some interesting results, such as the following: (1) We isolated 9 slice-inducing
factors, using a stepwise method. (2) Our artificial neural network (ANN) accurately separated 'slice'
from 'normal' shots (classification rate: 100%). (3)We could present the possibility of reducing the
number of slice using the fuzzy logic. We expect that our data might be eventually used to improve
golf performance.
An Approach To Discrete Spectrum Correction Based on Energy Centroid
Authors: Kang Ding , Dangdang Cao , Weihua Li
Published: March 2009

This paper proves that the energy centre of symmetric window function is the coordinate
origin in discrete spectrum analysis. The correction formula of frequency, amplitude and phase can be
obtained using this character. Simulation demonstrates that this method can correct averaged power
spectrum directly with simple algorithm and fast processing speed, and the interference of negative or
narrow interval frequencies has little influence on correction precision. This method is suitable for all
kinds of symmetric window. But it is not suited with dense frequencies signal or continuous spectrum.
Transition of Friction and Wear by Stick-Slip Phenomenon in Various Environments under Fretting Conditions
Authors: Jeong Sung Hoon , Park Jung Min , Lee Young Ze
Published: March 2009

The fretting wear arises when contacting surfaces undergo oscillatory tangential
displacement of small amplitude. Depending on the degree of stick and slip there are three kinds of
the contact motions, such as gross-slip, partial-slip and stick-slip. The fretting damage occurs most
severely when the transition from gross-slip to partial-slip happens. In this paper, the transitions of
friction and wear under fretting were investigated by ball-on-disk wear tests in various environments,
which were dry friction of air and nitrogen, and wet friction of mineral oil and engine oil. The
transition from partial-slip to stick-slip firstly occurred in nitrogen environment, and then in air. Later,
the transition occurred at higher load in mineral oil, and then lastly in engine oil.
PZT-Induced Lamb Waves and Pattern Recognition for On-Line Health Monitoring of Jointed Steel Plates
Authors: Roh Yong Rae , Kim Don Young , Yang Seung Han , Park Seung Hee , Yun Chung Bang
Published: March 2009

This paper presents a non-destructive evaluation (NDE) technique for detecting damages on a jointed steel plate on the basis of the time of flight and wavelet coefficient, obtained from wavelet transforms of Lamb wave signals. Probabilistic neural networks (PNNs) and support vector machines (SVMs) were applied for pattern classification. In this study, the applicability of the PNNs and SVMs was investigated for the damages in and out of the Lamb wave path. It has been found that the present methods are very efficient in detecting the damages simulated by the loose bolts on the jointed steel plate.
Gear Fault Classification Using Kernel Discriminant Analysis
Authors: Li Wei Hua , Ding Kang , Shi Tie Lin , Liao Guang Lan
Published: March 2009

This paper presents a study of KDA(kernel discriminant analysis) in gearbox failure feature
extraction and classification. Experimental gearbox vibration signals measured from normal, gear
small spall, gear severe spall and gear wear operating conditions are analyzed using either
KPCA(kernel principal component analysis) or KDA as the feature extraction and fault classification
methods. Experiment results indicate the effectiveness and thesuperiority of KDA for gear fault
classification over KPCA.
The Identification of Relationship between Vibration and Noise of Universal Motor in Working Status
Authors: Kim Min Gi , Hwang Won Woo , Lee Soo Hun
Published: March 2009

As the home appliances are systemized, they have complicatedly assembled structure. It is
reasonable to see the noise problem of home appliance in the viewpoint of system like vehicle and
ship. There are various system analysis methods to resolve the noise problem [1-3]. To use system
analysis methods, the system information like modal and path properties must be gathered and analyzed.
But it takes many times to find out the system properties, so the simpler system analysis methods are
needed. The coherence analysis method is useful as the system analysis method, since the method can
identify the system property like the relationship between inputs and outputs directly and simply.
In the paper, the partial coherence analysis is used for identification of the MISO system of washing
machine, in which multi-input signals are vibration signals of motor bracket and an output signal is
noise signal of washing machine. The relationship between the noise of washing machine and the
vibration of the motor bracket in working status was identified and the parts of bracket closely
correlated with noise were also proved by the relationship. And the noise of washing machine was
controlled by redesigning the parts of bracket associated with the noise of washing machine based on
the coherence function in octave band.
The Evaluation of Weldability for AZ31B-H24 and AZ91C-F Mg Alloys in Friction Stir Welding
Authors: Chang Woong Seong , Kim Heung Ju , Noh Joong Suk , Bang Han Sur
Published: March 2009

In the present study, an investigation has been carried out on the friction stir welding
(FSW) of two magnesium alloys. Hot-rolled and Die-casting plates of AZ type magnesium alloys
were successfully joined by friction stir welding. AZ31B-H24 and AZ91C-F plates with the
thickness of 4mm were used, and the microstructural development in stir zone (SZ) was
investigated using optical and scanning electron microscopes. Hardness of SZ in AZ31B-H24 alloy
has been slightly decreased due to the coarse structure. On the other hand, Hardness of SZ in
AZ91C-F alloy has been remarkably increased due to very fine recrystallized grain structure. The
result of EPMA showed Al Solid solution hardening by Solid solution of β intermetallic compound
to α-Mg. While tensile strength of the FSWelded AZ31B-H24 alloy showed about 80% values
compare to Base metal, AZ91C-F showed about 68% values due to strongly affected by formation
of the intermetallic compounds, β-Al12Mg17.
Numerical Modeling of Shape Memory Alloy Thin Film Actuators and Their Applications
Authors: Roh Jin Ho , Han Jae Hung , Lee In
Published: March 2009

The thermomechanical behavior of SMA thin film actuator and their application are
investigated. The numerical algorithm of the 2-D SMA thermomechanical constitutive equation is
developed using user material (UMAT) subroutine written by FORTRAN. For the numerical results
of SMA thin film, the ABAQUS finite element program has been utilized with UMAT subroutine of
the numerical algorithm of SMA. The application of SMA thin film for the membrane pump actuator
is demonstrated.
Structural Integrity Assessment of Tunnel Concrete Lining by the Resonance Search Technique
Authors: Kang Tae Ho , Joh Sung Ho , Cho Mi Ra
Published: March 2009

Concrete lining of underground structures is one of structural elements to require the structural integrity assessment. In this paper, for the structural-integrity assessment of concrete lining, the resonance search (RS) technique based on stress-wave propagation is proposed. The RS technique is the combination of the Spectral-Analysis-of-Surface-Waves (SASW) method and the resonance method. In the RS method, the shear-wave velocity profile is first determined by the SASW measurements. Then, the thickness of concrete lining is determined using the search technique to match the measured resonant frequency and the theoretical resonant frequency evaluated by the numerical modeling. The validity of the proposed procedure was verified by the numerical simulations of the method, the field test at a test concrete lining and the practical application to a real concrete lining of tunnel ManDeok in Korea. The slab thicknesses obtained by coring and Ground Penetrating Radar (GPR) scanning were also compared with the thickness by the RS technique.
Development of Imaging Technique for Evaluating the RC Plate Containing Epoxy-Repaired Delamination
Authors: Cheng Chia Chi , Pei Kuang Chih , Wu Jiunn Hong
Published: March 2009

The paper introduces a newly developed imaging technique for evaluating the integrity of
concrete structures. The image of normalized amplitude spectra is obtained from B-scan of
impact-echo tests. The normalizing process was carried out by obtaining the simulated transfer
functions, in which the displacement of R-wave waveform of the impact-echo response multiplying a
correcting factor is used as the simulated force-time function. Two specimens, one reinforced and the
other unreinforced concrete plates, containing naturally delaminated cracks with crack widths 1 mm,
3 mm and 5 mm were constructed and repaired by injected epoxy into the delaminated cracks. The
NDT method was performed on the specimens before and after the repairing work for comparison.
The spectral image shows consistent high intensity at the crack-depth-frequency for specimens at
crack stages and less in intensity for the ones at repaired stage.
The Application of Nondestructive Methods for Degradation Evaluation of Modified 9Cr-1Mo Steel
Authors: Park Jong Seo , Baek Un Bong , Nahm Seung Hoon , Han Sang In , Choi Song Chun
Published: March 2009

The nondestructive evaluation technique for the material degradation is necessary because
of the limitation of conventional destructive methods. In this study, an ultrasonic velocity
measurement method was attempted for the estimation of the creep damage of degraded modified
9Cr-1Mo steel. The specimens with seven different kinds of aging periods were prepared by an
isothermal heat treatment at 690 . The ultrasonic velocity was measured by an immersion method.
The correlation between the measured ultrasonic velocity and tensile properties were studied. The
ultrasonic velocity has an declining tendency with the increase of heat treatment time. A correlation
between the ultrasonic velocity and aging parameter were established, which allows one to estimate
the material degradation of modified 9Cr-1Mo steel.
Effect of Sulfuric Acid Concentration on Acoustic Emission Signals in Uniform-Corrosion
Authors: Prateepasen Asa , Jirarungsatean Chalermkiat , Tuengsook Pongsak
Published: March 2009

In petroleum industry, corrosion failures of steel structures are common. The severity of
corrosion in oil distillery inorganic compounds is higher than in those of organic compounds.
Inorganic compounds such as sulfur are the most influential corrosive activators inside oil or
chemical storage tanks. They normally have the tanks inspected and repaired along their life time.
In addition the concentration of sulfur compound increases due to the accumulation of the residuals
inside the tank, and so does the corrosive rate. In this paper, Acoustic Emission (AE) has been
chosen to study the characteristic of AE signals received from the uniform corrosion mechanism of
mild steel (A36) in various concentrations of Sulfuric acid (H2SO4) solution. AE signals were
captured using a wide band sensor (WD) and recorded by AE system model LOCAN 320. The
relationship between AE signals and sulfur concentrations as well as pH were exhibited.
Fatigue Crack Propagation of Magnesium Alloy and Aluminum Alloy in Biaxial Stress Fields
Authors: Ito Yasumi , Shimamoto Akira
Published: March 2009

In this research, fatigue crack propagation tests of magnesium alloy AZ31B and aluminum alloy 2024T3 were conducted under conditions of biaxial and uniaxial loading by using a cruciform specimen in a biaxial fatigue machine, in order to investigate the effect of non-singular stress cycling. From these comprehensive experiments, in the magnesium alloy, the remarkable effect was found in the specific biaxial load stress ratio RB (= σx 0/σy 0) on KI-da/dN relation. On the other hand, in the aluminum alloy, it was confirmed that there is no influence of a RB on KI-da/dN relation.
Separation and Concentration of Particles in Fluid Using Ultrasonic Standing Wave
Authors: Lee Young Sup , Kwon Jaehwa
Published: March 2009

This paper presents the theory, design, and evaluation of a smart device for the enhanced
separation of particles mixed in fluid. The smart device takes advantage of the ultrasonic standing
wave, which was generated by the operation of a piezoceramic PZT patch installed in the smart
device. The details of the device design including the electro-acoustical modelling for separation and
PZT transducer are described at first. Based on this design, the separation device was fabricated and
evaluated. In the experiments, an optical camera with a zoom lens was used to monitor the position of
particles within the separation channel layer in the device. The electric impedance of the PZT patch
bonded on the separation device was measured .The device shows a strong levitation and separation
force against 50μm diameter particles mixed with water at the separation channel in the device.
Experimental results also showed that the device can work at both heavy and light sand particles
mixed with water due to the generated standing wave field in the separation channel.
Structural Health Monitoring of Composite Structures Using Guided Lamb Waves
Authors: Balasubramaniam Krishnan , Sekhar B.V. Soma , Vardan J. Vishnu , Krishnamurthy C.V.
Published: March 2009

Structural Health Monitoring (SHM) of aircrafts is of great relevance in the present age aircraft industry. The present study demonstrates three techniques that have the potential for the SHM of multi-layered composite structures. The first technique is based on multi-transmitter-multireceiver (MTMR) technique with tomographic methods used for data reconstruction. In the MTMR, the possibility of SHM using algebraic reconstruction techniques (ART) for tomographic imaging with Lamb wave data measured in realistic materials is examined. Defects (through holes and low velocity impact delaminations) were synthetic and have been chosen to simulate impact damage in composite plates. The second technique is a single-transmitter-multi-receiver (STMR) technique that is more compact and uses reconstruction techniques that are analogous to synthetic aperture techniques. The reconstruction algorithm uses summation of the phase shifted signals to image the location of defects, portions of the plate edges, and any reflectors from inherent structural features of the component. The third technique involves a linear array of sensors across a stiffener for the detection of disbanded regions.
Numerical and Experimental Studies on the Scattering of Lamb Waves in a Bent Plate
Authors: Gunawan Arief , Hirose Sohichi
Published: March 2009

Scattering analysis of Lamb waves in perpendicularly bent plates with and without a crack
is presented. Single cracks on the inner or outer surface of a bent part are considered. The scattering
behaviors of Lamb waves in the bent plate with or without a crack are discussed in order to investigate
the potential of Lamb wave ultrasonic method for characterizing cracks in a bent part. Experimental
study is also carried out to verify the numerical results.
Fabrication of a 40 MHz Single Element Ultrasonic Transducer Using a PMN-PT Single Crystal
Authors: Paeng Dong Guk , Kim Hyung Ham , Lee Sang Goo , Rhim Sung Min , Choi Min Joo
Published: March 2009

PMN-PT, a piezoelectric single crystal, has been known to be a better material for
transducer arrays due to its high electromechanical coupling coefficient (k33) and high dielectric and
piezoelectric constants. It may also be good even for high frequency single element transducers using
relatively high kt and low attenuation and velocity dispersion. However, it’s challenging to fabricate
high frequency transducers using PMN-PT since it is easily breakable and requires small area and
thickness of the transducer. A KLM model was used to simulate a 40 MHz single element transducer
including 2 matching layers and a conductive backing. The simulation showed that the PMN-PT
transducer turned out to be better in sensitivity and bandwidth than a 40 MHz LiNbO3 transducer. A
40 MHz PMN-29%PT transducer was fabricated and the pulse echo signals were obtained and
analyzed. Its sensitivity was found to be –48 dB and –6dB bandwidth was about 48 %.
Synthesis of Ba(MgxNb1-x)O3 Nanoparticles by a Glycothermal Process
Authors: Kim Rak Hee , Son Jung Hoon , Bae Dong Sik
Published: March 2009

Ba(MgxNb1-x)O3 nanoparticles were prepared under high temperature and pressure
conditions by precipitation from metal nitrates with aqueous potassium hydroxide. Ba(MgxNb1-x)O3
nanoparticles were obtained in the temperature range of 170185 for 4 h. TEM and X-ray
diffraction patterns showed that the synthesized particles were crystalline. The average size and size
distribution of the synthesized particles were around 100 nm and broad, respectively.
Numerical Study of Crack Propagation in Stiff Clays
Authors: Wang Shan Yong , Lam K.C. , Fung Ivan W.H. , Zhu Wan Cheng , Xu Tao , Li Lian Chong
Published: March 2009

Many stiff clays forming part of natural slopes and earth dams exist in the fissured state.
When these cracks are subjected to gravity induced normal and shear stresses they may propagate.
The present discussion presents a numerical method to study the propagation direction of cracks
under stress fields similar to those found in the field. Not only did the results on one crack
propagation direction obtained from the numerical method and the analytical results agree well, but
numerical results have been used to investigate the mechanisms of the whole process of two
horizontal cracks initiation and propagation and coalescence in stiff soils.
Fatigue Damage and Life Prediction under Sequential Biaxial Loading
Authors: Jin Dan , Wu Jian Hua , Chen Xu
Published: March 2009

Fatigue tests are conducted on 304 stainless steel and 45C steel under fully reversed strain control conditions with two different loading modes. 45C steel exhibits cyclic softening under each phase loading. While for 304 stainless steel, much additional hardening is observed in out-of-phase loading. The damage values for failure of 45C steel is similar to the previous research, however, 304 stainless steel is not. Fatigue life is predicted based on the linear damage rule, the double linear damage rule, and the plastic work model of Morrow. The damage value is different in the same loading mode for the two materials according to linear damage rule.
An Closed Form Solution for Antiplane Problem of Doubly Periodic Non-Uniform Cracks
Authors: Xu Yao Ling , Tan Wen Feng
Published: March 2009

Inhomogeneous materials with doubly periodic non-uniform cracks under antiplane shear is dealt with. By using conformal mapping technique and elliptic function theory, the stress field and stress intensity factor at the tip of each crack are derived in closed form. Numerical examples show the influences of some microstructure parameters of crack distribution on stress intensity factor.
A Numerical Study on Ductile Material Failure
Authors: Qin K. , Yang Li Ming
Published: March 2009

Experiments show that the failure of ductile materials can be characterized by a
rate-independent parameter, relative spacing d defined as the ratio of the distance between two voids and
the radius of voids. In this study, this experimental phenomenon is analyzed via numerical simulations
using 3-D finite element model. Considering that hydrostatic stress is a dominant factor in the evolution
of microvoid nucleation, growth and coalescence in ductile materials, numerical simulations are
performed to obtain the relationship between relative spacing d and hydrostatic stress in the ligament
between voids. Numerical results show that hydrostatic stress along matrix ligament is sensitive to the
change of the relative spacing. Further analysis shows that the failure of ductile materials can modeled by
using a criterion of the threshold of local hydrostatic stress in the ligament. Based on such a criterion, a
curve displaying the relationship between the strength of ductile material and strain rate is obtained
numerically. It is concluded that the failure criterion of ductile materials can be described by using local
hydrostatic stress and relative spacing between two voids, which is not sensitive to strain rates.
3D Anisotropic Elastoplastic-Damage Model and its Application in Simulating the Behavior of Rock Materials
Authors: Zhang Jun Feng , Qi Tao
Published: March 2009

A 3D anisotropic elastoplastic-damage model was presented based on continuum damage mechanics theory. In this model, the tensor decomposition technique is employed. Combined with the plastic yield rule and damage evolution, the stress tensor in incremental format is obtained. The derivate eigenmodes in the proposed model are assumed to be related with the uniaxial behavior of the rock material. Each eigenmode has a corresponding damage variable due to the fact that damage is a function of the magnitude of the eigenstrain. Within an eigenmodes, different damage evolution can be used for tensile and compressive loadings. This model was also developed into finite element code in explicit format, and the code was integrated into the well-known computational environment ABAQUS using the ABAQUS/Explicit Solver. Numerical simulation of an uniaxial compressive test for a rock sample is used to examine the performance of the proposed model, and the progressive failure process of the rock sample is unveiled.
Cyclic Plasticity and Fatigue Crack Growth
Authors: Zhang Rui , Yi Sun
Published: March 2009

The relation between material’s cyclic plastic behavior and fatigue crack growth is
investigated. The present model is proposed on the dislocation-free zone (DFZ) theory. A cohesive
zone theory is developed to determine the stress field of the DFZ and the value of J-integer under
cyclic loading. The crack growth criterion is proposed based on J-integral. The calculated curve of
fatigue crack growth rate da/dN is agreement with the general propagation pattern and the predicted
threshold accords with the experiment threshold well. It is found that the near threshold
characteristics are most determined by the cyclic deformation behavior of the material. The relation
between fatigue crack growth threshold and material’s cyclic hardening behavior is discussed.
Research on the Microstructure and Micro-Mechanics Properties of NiAl Intermetallic Coatings
Authors: Jin Guo , Li Qing Fen , Xu Bin Shi , Wang Hai Dou , Wei Shi Cheng
Published: March 2009

A new thermal spraying technique, electro-thermal explosion directional spraying
(EEDS), was used to prepare NiAl intermetallic coatings. The microstructure, elements distribution
and phase structures were determined by means of SEM, EDAX and X-Ray diffraction,
respectively. Micro-mechanics properties were tested by using nano-indentation tester. The wear
resistance of the coating was also investigated. Results showed that NiAl coating was characterized
by compact construction. The main phase of the coating was Ni-Al and the content of oxide was
little. The obvious elements diffusion showed that the bond between the coating and the substrate
was metallurgical one. The nano-hardness and the modulus were 7.6 GPa and 218.8 GPa,
respectively. The coatings processed good wear resistance and the main wear failure mechanism
was the micro-plowing.
Effect of Stress-Induced Damage Evolution on Long-Term Creep Behavior of Nonlinear Viscoelastic Polymer
Authors: Zhao Rong Guo , Luo Wen Bo , Wang Chu Hong , Tang Xin
Published: March 2009

The mechanical behaviors were investigated by nonlinear creep tests of poly(methyl
methacrylate) under different temperatures. The test duration was 4000 seconds. The corresponding
temperature shift factors, stress shift factors and temperature-stress shift factors were obtained
according to time-temperature superposition principle, the time-stress superposition principle and
the time-temperature-stress superposition principle (TTSSP). The master creep compliance curve up
to about 1-month at a reference temperature 22 degrees centigrade and a reference stress 14 MPa
was constructed, and the effect of stress-induced damage evolution on the long-term creep behavior
of polymeric material was accounted. It was shown that TTSSP provides an effective accelerated
test technique in the laboratory, the results obtained from a short-term creep test of poly(methyl
methacrylate) specimen at high temperature and stress level can be used to construct the master
creep compliance curve for prediction of the long-term mechanical properties at relatively lower
temperature and stress level, and the master creep compliance curve with damage considered can be
applied to accurately characterize the long-term creep behavior of nonlinear viscoelastic polymer.
Experimental and FEM Analysis of the Fracture Behavior in NiTi Shape Memory Alloys
Authors: Wang Xin Mei , Yue Zhu Feng
Published: March 2009

In the present work, the fracture toughness of a NiTi pseudoelastic alloy has been
obtained by experiments on CT specimens, which is KIC =39.38MPa·m1/2. Then the stress induced
phase transformation behavior in front of the crack tip of the CT specimen is simulated by a
micromechanical model considering the different elastic properties between martensite and
austenite. The results show that the pre-crack promotes phase transformation at the crack tip. And
the phase transformation is localised near the crack tip. It is also shown that phase transformation
reduces the Mises stress around the crack tip.
Research on ELID Grinding of Nano-Cemented Carbide Tool
Authors: Zhang Fei Hu , Gui J.C. , Liu Yi Zhi , Zhang Hua Li
Published: March 2009

Nano-cemented carbide is a novel material, which is superior to common cemented
carbide on physical and mechanical properties, such as high hardness, toughness, flexural strength
and higher wear resisting property. It is proposed to have wide application prospect to tools and
mould manufacturing.
In this paper, ELID grinding technique is applied to grind nano-cemented carbide tools. And the
ground surface quality, cutting edge radius, and machinability of nano-cemented carbide tools are
studied, compared with common cemented carbide. It is demonstrated by experimental results that
nano-cemented carbide has higher grinding surface quality with less surface flaw than that of
common cemented carbide. The cutting edge radius of nano-cemented carbide tool is less than that
of common cemented carbide tool. Under the same conditions, the tool life of nano-cemented
carbide is 1~2 times longer than that of common cemented carbide. The research results indicate
that ELID grinding technique is suitable for grinding cemented carbide tools. Nano-cemented
carbide tools have better machinability than common cemented carbide tools.