bluuebunny/crossref_metadata_2025 huggingface dataset:
Experimental study of the degradation of 2,4-D induced by vacuum-UV radiation
Authors: Imoberdorf G. E. , Mohseni M.
Published: April 2011

Vacuum-UV (VUV) photoinduced degradation of the herbicide 2,4-D was studied. A flow-through VUV photoreactor was used (i) in batch mode to study the kinetics of degradation and (ii) in continuous mode under steady state to analyze the potential utilization of this process in commercial applications. In both cases, the reactants were recycled to minimize diffusive resistances. Experimental results from the batch studies showed that the initial degradation rate of 2,4-D in ultrapure water was independent of the initial concentration of the herbicide. However, a reduction in the reaction rate was obtained over the course of the treatment, largely due to the formation of 2,4-D partial oxidation by-products which compete with 2,4-D molecules for HO (scavenging effect). Increases in water alkalinity reduced 2,4-D degradation rate as a consequence of the scavenging of HO by carbonates and bicarbonates. The degradation of 2,4-D in raw surface waters was also investigated. A noticeable reduction in the degradation rate was observed because of the presence of NOM and alkalinity, both being known HO scavengers. Additionally, the presence of inorganic species/ions that absorb VUV may also have contributed to the reduction of the overall degradation rate. High conversions were obtained in the continuous system. At a residence time of 25 seconds, conversions of 97% and 65% were achieved for inlet herbicide concentrations of 1 and 10 mg L−1, respectively. Under these conditions, the received dose of 185 nm radiation was 44.8 mJ cm−2.
Novel anaerobic digestion process with sludge ozonation for economically feasible power production from biogas
Authors: Komatsu K. , Yasui H. , Goel R. , Li Y. Y. , Noike T.
Published: April 2011

A novel process scheme was developed to achieve economically feasible energy recovery from anaerobic digestion. The new process scheme employs a hybrid configuration of mesophilic and thermophilic anaerobic digestion with sludge ozonation: the ozonated sludge is first degraded in a thermophilic digester and then further degraded in a mesophilic digester. In small-scale pilot experiments of the new process scheme, degradation of VSS improved by 3.5% over the control (mesophilic-only configuration) with 20% less ozone consumption. Moreover, biogas conversion also improved by 7.1% over the control. Selective enrichment of inorganic compounds during centrifugation produced a dewatered sludge cake with very low water content (59.4%). This low water content in the sludge cake improved its auto-thermal combustion potential during incineration and added to the overall energy savings. We conducted a case study to evaluate power generation from biogas for a municipal wastewater treatment plant with an average dry weather flow of 43,000 m3/d. Electricity production cost was 5.2 ¢/kWh for the advanced process with power generation, which is lower than the current market price of 7.2 ¢/kWh. The new anaerobic digestion scheme with power generation may reduce greenhouse gas emissions by about 1,000 t-CO2/year compared with the conventional process without power generation.
Oily wastewater treatment by ultrafiltration using Taguchi experimental design
Authors: Salahi A. , Mohammadi T.
Published: April 2011

In this research, results of an experimental investigation on separation of oil from a real oily wastewater using an ultrafiltration (UF) polymeric membrane are presented. In order to enhance the performance of UF in API separator effluent treatment and to get more permeation flux (PF), effects of operating factors on the yield of PF were studied. Five factors at four levels were investigated: trans-membrane pressure (TMP), temperature (T), cross flow velocity (CFV), pH and salt concentration (SC). Taguchi method (L16 orthogonal array (OA)) was used. Analysis of variance (ANOVA) was applied to calculate sum of square, variance, error variance and contribution percentage of each factor on response. The optimal levels thus determined for the four influential factors were: TMP, 3 bar; T, 40˚C; CFV, 1.0 m/s; SC, 25 g/L and pH, 8. The results showed that CFV and SC are the most and the least effective factors on PF, respectively. Increasing CFV, TMP, T and pH caused the better performance of UF membrane process due to enhancement of driving force and fouling residence. Also, effects of oil concentration (OC) in the wastewater on PF and total organic carbon (TOC) rejection were investigated. Finally, the highest TOC rejection was found to be 85%.
Effects of common dissolved anions on the reduction of para-chloronitrobenzene by zero-valent iron in groundwater
Authors: Le C. , Wu J. H. , Deng S. B. , Li P. , Wang X. D. , Zhu N. W. , Wu P. X.
Published: April 2011

Batch tests were conducted to evaluate the influences of several common dissolved anions in groundwater on the reduction of para-chloronitrobenzene (p-CNB) by zero-valent iron (ZVI). The results showed that p-CNB reduction was enhanced by both Cl− and SO42−. HCO3− could either improve or inhibit p-CNB reduction, depending on whether the mixing speed was intense enough to rapidly eliminate Fe–carbonate complex deposited on ZVI surface. Above a concentration of 100 mg L−1, NO3− increased the p-CNB reduction rate. The reduction rate by ClO4− decreased because the ClO4− competed with p-CNB for electrons. The p-CNB reduction was inhibited by PO43−, SiO32− and humic acid, in the order humic acid < PO43− < SiO32−, since these ions could form inner-sphere complexes on iron surface. The reaction even ceased when the ion concentrations were greater than 4, 0.5, and 30 mg L−1, respectively. The results indicated that common dissolved anions in groundwater should be taken into account when ZVI is applied for contaminated groundwater remediation.
The microwave-assisted photo-catalytic degradation of organic dyes
Authors: Jung S. C.
Published: April 2011

In this study, TiO2 photo-catalyst balls produced by the chemical vapour deposition method were used for degradation of organic dyes in which simultaneous irradiation of microwave and UV was evaluated. An electrodeless UV lamp that emits UV upon the irradiation of microwave was developed to irradiate microwave and UV simultaneously. The degradation reaction rate was shown to be higher with higher microwave intensity, under stronger acidic or basic conditions, and with a larger amount of O2 gas or H2O2 addition. The effect of addition of H2O2 was not significant when photo-catalysis was used without additional microwave irradiation or when microwave was irradiated without the use of photo-catalysts. When H2O2 was added under simultaneous use of photo-catalysis and microwave irradiation, however, considerably higher degradation reaction rates were observed.
Evaluation of the WHO helminth eggs criteria using a QMRA approach for the safe reuse of wastewater and sludge in developing countries
Authors: Navarro I. , Jiménez B
Published: April 2011

An analysis of the actual WHO recommendations to develop standards for the safe reuse of wastewater, excreta or sludge in agriculture using a quantitative microbial risk assessment (QMRA) is presented. The proposed values are defined using a risk-based model for Ascaris lumbricoides infection to assess the human risks associated with exposure to this pathogen from crops irrigated with polluted water, or from crops grown in biosolid-enriched soil. From the results it becomes evident that, with regard to helminth eggs, the WHO guidelines for wastewater reuse in agriculture seem more stringent than are needed in developing countries, while for the reuse of sludge they appear to be the opposite. Although more information is needed to confirm this conclusion, which was derived from a single piece of research, at the very least a more cautious approach is recommended when evaluating excreta or sludge for agricultural purposes in developing countries. Additionally, this work shows that the application of some barriers, other than wastewater and sludge treatment as suggested by WHO, can play an important role in controlling risks.
Composition and distribution of bacteria in an operating rainwater harvesting tank
Authors: Kim Mikyeong , Han Mooyoung
Published: April 2011

In this study, we investigated the phylogenetic distribution of the bacteria present in an operating rainwater tank by denaturing gradient gel electrophoresis (DGGE), and compared the bacterial composition in rainwater and biofilm from the inlet and outlet of the tank. Seventeen species were identified, the DGGE profiles of which showed a clear difference between the planktonic bacterial community and the community in the biofilm. Most of the bacteria were closely related to fresh water, soil, and biofilm bacteria found in natural environments. The high proportion of Proteobacteria indicates the generally clean oligotrophic nature of the tank water. Biofilm formation is an advantage for bacteria that exist in oligotrophic environments. The groups identified in the biofilm, such as Sphingomonas, Bacillus, and Sphingophyxis, have been demonstrated to degrade certain contaminants and to act as bio-control agents. Thus, biofilm formation in rainwater tanks not only represents a survival strategy for bacteria, but also serves as a natural filter by removing contaminants and bacteria from rainwater.
Degradation mechanism of Methyl Orange by electrochemical process on RuOx–PdO/Ti electrode
Authors: Du Lin , Wu Jin , Qin Song , Hu Changwei
Published: April 2011

The electrochemical degradation of Methyl Orange in 0.1 M NaCl solution over RuOx–PdO/Ti anode was investigated. Chemical oxygen demand (COD), ion chromatography (IC), Fourier Transform Infrared Spectroscopy (FTIR) and Gas chromatography-mass spectrometry (GC-MS) were employed to detect the intermediates formed during the electrochemical degradation. In the present reaction system, Methyl Orange could be effectively degraded. After 1 h treatment, the discoloration could reach 97.9% with COD removal of 57.6%. The results indicated that in the presence of chloride, the electrolysis was able to oxidise the dye with partial mineralisation of carbon, nitrogen and sulfur into CO2, NO3− and SO42−, respectively. After 8 h electrolysis, 62% of sulfur contained in Methyl Orange was transformed to SO42−, and 17.6% of nitrogen changed to NO3−. The intermediates during electroprocess were detected to be low molecular weight compounds, chlorinated compounds, derivatives of benzene and long chain alkanes. Based on these data, a possible degradation mechanism of Methyl Orange was proposed.
Photonic Bandgap Engineering in FBGs by Post Processing Fabrication Technique
Authors: Andrea Cusano  , Domenico Paladino  , Antonello Cutolo  , Agostino Iadicicco  , Stefania Campopiano
Published: April 2011

The incredible growth of Fiber Bragg Gratings (FBGs) from both the research and the commercial points of view, has forced the development of several methods able to tailor their spectral characteristics for specific applications. Basically, two different approaches can be adopted to specialize the grating spectra: one is based on complex grating profiles induced directly at the fabrication stage. Another, more interesting, approach relies on post processing methodologies that introduce localized defects along the grating, breaking its periodic structure. The presence of the defects leads to the formation of allowed bands or defect states within the grating bandgap. The introduction of finer scale spectral features results in new interesting perspectives in both telecommunications and sensing fields. In addition, the possibility to accurately control the defect states spectral features - depth, bandwidth, and spectral position - could allow the complete engineering of the FBG bandgap, opening the way to the realization of several new advanced and attractive photonic devices. This chapter is focused to review the main advancements in FBGs post processing to easily control the spectral features of the final device for specific applications.
Fiber Bragg Grating Interrogation Systems
Authors: Jose Luis Santos  , Luis Alberto Ferreira  , Stefania Campopiano
Published: April 2011

Fiber Bragg Gratings are structures with remarkable characteristics that have induced new qualitative developments in the broad field of optical fiber technology, most notably in optical communications and in optical sensing. When these devices are applied for sensing, the underlying concept is the modulation of the grating Bragg wavelength by the measured and, therefore, a central issue is the sensitive and accurate conversion of the resonant wavelength into a proportional electrical signal with the adequate format for further processing. This topic is broadly known as Fiber Bragg Grating interrogation and is the subject of the present chapter. It is organized in two parts: in the first one, the techniques developed by the scientific community looking for this functionality are reviewed, with emphasis on the identification of general conceptual classes where they fit; in the second part, illustrative and state-of-the-art commercial Fiber Bragg Grating interrogation systems are described.
Multiplexing Techniques for FBG Sensors
Authors: Manuel Lopez-Amo  , Jose Miguel Lopez-Higuera
Published: April 2011

One of the main goals of fiber optic sensor technology is to multiplex together a high number of sensors in the same fiber in order to share expensive terminal equipment and reduce the size and weight of the optical cable. Both passive and active multiplexing techniques are used for telemetry in sensor networks. The different multiplexing techniques for Fiber Bragg Grating sensors will be described and compared here, including networks using optical amplification and lasing multiplexing systems.
Fiber Bragg Grating Sensors in Civil Engineering Applications
Authors: Jinping Ou  , Zhi Zhou  , Genda Chen
Published: April 2011

Fiber Bragg Gratings (FBG) have been regarded as one of the most promising local monitoring sensors and are widely deployed in civil infrastructures. In this chapter, those FBG-based sensors aiming at civil structures have been briefly presented, including direct packaged strain and temperature sensors, indirect sensors constructed using FBG as a sensing element, and FBG based smart civil structures. Specific issues concerning methods of effectively and correctly applying the FBG sensors to civil infrastructures have been discussed. Those issues involve sensor installation technique, strain transfer based error modification, and temperature compensation. Finally, more than ten case studies of critical infrastructures outfitted with FBG sensors have been reported. Both research and practical applications show that FBG sensors are now competitive with conventional electrical sensors in long-term structural health monitoring.
Fiber Bragg Grating Sensors for Railway Systems
Authors: Hwa-yaw Tam  , Shun-yee Liu  , Siu-lau Ho  , Tin-kin Ho
Published: April 2011

Fiber Bragg Grating (FBG) sensor technology has been attracting substantial industrial interests for the last decade. FBG sensors have seen increasing acceptance and widespread use for structural sensing and health monitoring applications in composites, civil engineering, aerospace, marine, oil & gas, and smart structures. One transportation system that has been benefited tremendously from this technology is railways, where it is of the utmost importance to understand the structural and operating conditions of rails as well as that of freight and passenger service cars to ensure safe and reliable operation. Fiber-optic sensors, mostly in the form of FBGs, offer various important characteristics, such as EMI/RFI immunity, multiplexing capability, and very long-range interrogation (up to 230 km between FBGs and measurement unit), over the conventional electrical sensors for the distinctive operational conditions in railways. FBG sensors are unique from other types of fiber-optic sensors as the measured information is wavelength-encoded, which provides self-referencing and renders their signals less susceptible to intensity fluctuations. In addition, FBGs are reflective sensors that can be interrogated from either end, providing redundancy to FBG sensing networks. These two unique features are particularly important for the railway industry where safe and reliable operations are the major concerns. Furthermore, FBGs are very versatile and transducers based on FBGs can be designed to measure a wide range of parameters such as acceleration and inclination. Consequently, a single interrogator can deal with a large number of FBG sensors to measure a multitude of parameters at different locations that spans over a large area.
FBG is the most promising, cost-effective and distributed sensor technology that provides an ideal platform to monitor the condition and structural health of tracks, carriages and underframe equipment in railway systems. In the last few years, a number of field trial railway projects using FBG sensors for axle counting, track and train vibration measurements, monitoring of bogie conditions, structural health monitoring of train bodies, and interaction between overhead contact lines and current collectors (pantograph) were successfully conducted by a few research institutions. These studies demonstrated the superiority of FBG sensors over conventional sensors in many crucial aspects. However, major barriers, such as lack of proprietary and custom specifications, packaging and reliability standards, insufficient field experience, have yet to be resolved before major railway operators are to embrace the FBG sensor technology.
Fiber Bragg Grating Sensors in Nuclear Environments
Authors: Francis Berghmans  , Andrei Gusarov
Published: April 2011

Fiber Bragg Grating sensors are evaluated for applications in environments where the presence of highly energetic radiation is a concern, such as space and nuclear industry. To assess the feasibility of using this sensor technology in these particular application environments it is essential to evaluate the behavior of Fiber Bragg Gratings when exposed to different types of ionizing radiation. We, therefore, review the effects of ionizing radiation on several types of Fiber Bragg Gratings.
Fiber Bragg Grating Evanescent Wave Sensors for Chemical and Biological Applications
Authors: Andrea Cusano  , Domenico Paladino  , Antonello Cutolo  , Agostino Iadicicco  , Stefania Campopiano
Published: April 2011

While Fiber Bragg Grating (FBG) sensors continue to act as valuable sensing platforms specially when physical parameters have to be measured in single or multipoint configuration, great efforts have been focused in the last decade to convey the great advantages of FBG technology towards the development of new devices and components employable in modern chemical and biological applications. Since the first attempt carried out in 1996 by Meltz et al., many sensing schemes have been proposed based on the evanescent wave effect arising from the surrounding refractive index sensitization of the final device by tailoring either the grating structure or the host fiber. In this chapter, we review the main advances in the area of FBG evanescent wave sensors, with particular emphasis on principles of operation, technological developments, overall performances and discussing in details perspectives and challenges that lie ahead.
Fiber Bragg Grating Sensors in Microstructured Optical Fibers
Authors: Tomasz Nasilowski
Published: April 2011

The unusual properties of Fiber Bragg Gratings in microstructured fibers deliver significantly improved performance in some respect to traditional fibers. They are also superior in one or few characteristics and eventually unveil the novel properties of fiber Bragg grating sensors, leading to the superiority of implementations and original applications, which are briefly discussed in this chapter. Moreover, a very promising functionality of doped core microstructured fibers in perspective of material and geometrical guiding mechanism competition is clarified and encouraged. Furthermore, such fibers are greatly advantageous for Fiber Bragg Grating inscription and instead of scarifying important properties they pave the way to novel applications fulfilling the industrial requirements. Additionally, very interesting and hopeful research and development of pure silica microstructured Fiber Bragg Gratings are presented as well.
Polymer Fiber Bragg Gratings
Authors: David John Webb  , Kyriacos Kalli
Published: April 2011

This chapter deals with gratings recorded in polymeric optical fibers (POFs); predominantly those based on poly (methyl methacrylate) (PMMA). We summarize the different mechanical and optical properties of POFs which are relevant to the application of POF Bragg gratings and discuss the existing literature on the subject of the UV photosensitivity of PMMA. The current state of the art in POF grating inscription is presented and we survey some of the emerging applications for these devices.
Determinants of debt rescheduling in Eastern European countries
Authors: Lausev Jelena , Stojanovic Aleksandar , Todorovic Natasa
Published: April 2011

This study utilizes Panel Logit Models applied to a set of macroeconomic,
financial, and political variables to estimate the debt rescheduling
probabilities of 15 Eastern European countries during the transition period
from 1990-2005. These transition economies became a very attractive region
for foreign investment. Specifically, the region became the largest recipient
of net non-FDI flows among all emerging market regions in 2005. Therefore, it
is relevant for policy makers and institutional and private foreign investors
to investigate factors that influence debt rescheduling probabilities, as
these may directly affect the size of and return on investments in these
countries. Our findings suggest that policy efforts focused on reducing
government expenditure, attracting foreign direct investment, increasing
export revenues, and keeping a good repayment record result in low debt
rescheduling probabilities and, in turn, decrease the cost of debt for these
countries. This is a common finding for all countries in the sample,
including those that have become EU members.
Market risk stress testing for internationally active financial institutions
Authors: Markovic Petar , Urosevic Branko
Published: April 2011

The paper develops a comprehensive framework for market risk stress testing
in internationally active financial institutions. We begin by defining the
scope and type of the stress test and explaining how to select risk factors
and the stress time horizon. We then address challenges related to data
gathering, followed by in-depth discussion of techniques for developing
realistic shock scenarios. Next the process of shock application to a
particular portfolio is described, followed by determination of portfolio
profit and loss. We conclude by briefly discussing the issue of assigning
probability to stress scenarios. We illustrate the framework by considering
the development of a ?worst case? scenario using global financial market data
from Thomson Reuters Datastream.
Liquidity, price impact and trade informativeness: Evidence from the London stock exchange
Authors: Teodorovic Natasa
Published: April 2011

The rapid development of electronic trading has significantly changed stock
exchange markets. Electronic systems providing trading processes have
defined a new stock market environment. Such a new environment requires
trading process redefinition (generally defined as algorithmic trading), as
well as redefinition of well known microstructure hypotheses. This paper
conducts standard Hasbrouck?s (1991a, 1991b) market microstructure time
series analysis to examine adverse selection and information asymmetry
issues on diverse liquidity leveled stocks listed on the London Stock
Exchange, which is a market with a significant algorithmic trading share.
Based on the results obtained from the considered sample, this paper
suggests that the contribution of unexpected trade in the volatility of the
efficient price is larger for intensively traded stocks, arguing that
Hasbrouck?s (1991a, 1991b) model recognizes algorithmic trading as an
unexpected trade, i.e. as a trade caused by superior information.
Distribution and forms of iron in the vertisols of Serbia
Authors: Jelic Miodrag , Milivojevic Jelena , Trifunovic Srecko , Djalovic Ivica , Milosev Dragisa , Seremesic Srdjan
Published: April 2011

Soil of arable land and meadows from the Ap horizon, taken from ten different
localities, were investigated for different forms of Fe, including total
(HF), pseudo-total (HNO3), 0.1M HCl extractable and DTPA-extractable. A
sequential fractional procedure was employed to separate the Fe into
fractions: water soluble and exchangeable Fe (I), Fe specifically adsorbed
with carbonates (II), reducibly releasable Fe in oxides (III), Fe bonded with
organic matter (IV) and Fe structurally bonded in silicates (residual
fraction) (V). The soil pH, CEC, and size fractions (clay and silt) had a
strongest influence on the distribution of the different forms of Fe. The
different extraction methods showed similar patterns of the Fe content in
arable and meadow soils. However, the DTPA iron did not correspond with the
total iron, which confirms the widespread incidence of iron-deficiency in
vertisols is independent of the total iron in soils. The amount of
exchangeable (fraction I) and specifically adsorbed (II) iron showed no
dependence on its content in the other fractions, indicating low mobility of
iron in vertisols. The strong positive correlation (r = 0.812 and 0.956)
between the content of iron in HNO3 and HF and its contents in the primary
and secondary minerals (fraction - V) indicate a low content of plant
accessible iron in the vertisol. The sequential fractional procedure was
confirmed as suitable for accessing the content and availability of iron in
the vertisols of Serbia.
Starting radial subdiffusion from a central point through a diverging medium (a sphere): Heat-balance integral method
Authors: Hristov Jordan
Published: April 2011

The work presents an integral solution of the time-fractional subdiffusion
equation as alternative approach to those employing hypergeometric functions.
The integral solution suggests a preliminary defined profile with unknown
coefficients and the concept of penetration (boundary layer) well known from
the heat diffusion and hydrodynamics. The profile satisfies the boundary
conditions imposed at the boundary of the boundary layer that allows its
coefficients to be expressed through the boundary layer depth as unique
parameter describing the profile. The technique is demonstrated by a solution
of a time fractional radial equation concerning anomalous diffusion from a
central point source in a sphere.
Effects of surface morphology on thermal contact resistance
Authors: Huang Haiming , Xu Xiaoliang
Published: April 2011

The thermal contact resistance is common in aerospace industry, nuclear
reactors and electronic equipments. The work addresses a new scheme for
determining the thermal contact resistance between a smooth surface of a film
and a rough surface of a metal specimen. The finite element method was used
as a tool to explore the surface morphology effect on the thermal contact
resistance while the temperature of the contact surface was determined by a
regression method. According to the results developed, the temperature on the
contact surfaces linearly drops with the increasing average height of surface
roughness and nonlinearly drops with the increasing ratio between non-contact
area and nominal contact area. On the other hand, the thermal contact
resistance increases linearly with increases in the average height of the
surface roughness. What?s more, the thermal contact resistance increases in a
non-linear manner as the ratio of the non-contact area to the nominal contact
area is increasing.
A novel algorithm for solving the classical Stefan problem
Authors: Wu Zhaochun , Luo Jianping , Feng Jingmei
Published: April 2011

A novel algorithm for solving the classic Stefan problem is proposed in the
paper. Instead of front tracking, we preset the moving interface locations
and use these location coordinates as the grid points to find out the arrival
time of moving interface respectively. Through this approach, the difficulty
in mesh generation can be avoided completely. The simulation shows the
numerical result is well coincident with the exact solution, implying the new
approach performs well in solving this problem.
Analysis of Marangoni convection of non-Newtonian power law fluids with linear temperature distribution
Authors: Zhang Yan , Zheng Liancun , Wang Xiaojing , Song Guhua
Published: April 2011

The problem of steady, laminar, thermal Marangoni convection flow of
non-Newtonian power law fluid along a horizontal surface with variable
surface temperature is studied. The partial differential equations are
transformed into ordinary differential equations by using a suitable
similarity transformation and analytical approximate solutions are obtained
by an efficient transformation, asymptotic expansion and Pad? approximants
technique. The effects of power law index and Marangoni number on velocity
and temperature profiles are examined and discussed.
Analysis of non-Fourier thermal behavior for multi-layer skin model
Authors: Liu Kuo-Chi , Cheng Po-Jen , Wang Yan-Nan
Published: April 2011

This paper studies the effect of micro-structural interaction on bioheat
transfer in skin, which was stratified into epidermis, dermis, and
subcutaneous. A modified non-Fourier equation of bio-heat transfer was
developed based on the second-order Taylor expansion of dual-phase-lag model
and can be simplified as the bio-heat transfer equations derived from Pennes?
model, thermal wave model, and the linearized form of dual-phase-lag model.
It is a fourth order partial differential equation, and the boundary
conditions at the interface between two adjacent layers become complicated.
There are mathematical difficulties in dealing with such a problem. A hybrid
numerical scheme is extended to solve the present problem. The numerical
results are in a good agreement with the contents of open literature. It
evidences the rationality and reliability of the present results.
Application of lattice Boltzmann method and field synergy principle to the heat transfer analysis of channel flow with obstacles inside
Authors: Wang Cheng-Chi , Yau Her-Terng , Lin Chien-Nan , Cheng Po-Jen , Hung Wei-Min
Published: April 2011

In this paper the lattice Boltzmann method and field synergy principle are
applied to simulate two-dimensional incompressible steady channel flow under
low Reynolds number, and analyze the local influence on velocity field and
temperature field caused by inserting cylinder obstacles of different
cross-section. Furthermore, field synergy principle of elliptic flow type is
applied to demonstrate that the increased interruption within the fluid
increases the synergistic level between the velocity field and temperature
gradient field. As the intersection angle between the velocity vector and the
temperature gradient vector decreases by inserting cylinder obstacles to
fluid field, the results of heat transfer will improve significantly.
The heat and fluid flow analysis for water heater
Authors: Lin Chien-Nan , Wang Cheng-Chi , Kuo Yi-Pin
Published: April 2011

In this paper, the heat transfer and fluid flow are studied for the water
heater of RV cars, in which the hot water is heated by the combustion energy
of liquefied petroleum gases. Three types of combustion tubes are performed
in this investigation, which are circular tube, elliptic tube and elliptic
tube with screwed wire inserted. The heat transfer performances of numerical
simulation results are compared with those of the experimental works; they
are in good trend agreement. The elliptic combustion tube performs better
than the circular one, which indicates the average 7% energy saving for the
elliptic combustion tube and 12% energy saving for the elliptic combustion
tube with screwed wire under static heating.
A numerical investigation into electroosmotic flow in microchannels with complex wavy surfaces
Authors: Yau Her-Terng , Wang Cheng-Chi , Cho Ching-Chang , Chen Cha’o-Kuang
Published: April 2011

This study investigates the flow characteristics of electroosmotic flow in a
microchannel with complex wavy surfaces. A general method of coordinate
transformation is used to solve the governing equations describing the
electroosmotic flow in the microchannel. Numerical simulations are performed
to analyze the effects of wave amplitude on the electrical field, flow
streamlines, and flow fields in the microchannel. The simulation results show
that, compared to a traditional pressure-driven flow, flow recirculation is
not developed in the electroosmotic flow in a microchannel with complex wavy
surfaces. The simulations also show that the electrical field and velocity
profiles change along the channel in the region of wavy surfaces. Non-flat
velocity profiles are observed in different cross-sections of the channel in
the region of wavy surfaces.
A thermodynamic cavitation model applicable to high temperature flow
Authors: Liu De-Min , Liu Shu-Hong , Wu Yu-Lin , Xu Hong-Yuan
Published: April 2011

Cavitation is not only related with pressure, but also affected by
temperature. Under high temperature, temperature depression of liquids is
caused by latent heat of vaporization. The cavitation characteristics under
such condition are different from those under room temperature. The paper
focuses on thermodynamic cavitation based on the Rayleigh-Plesset equation
and modifies the mass transfer equation with fully consideration of the
thermodynamic effects and physical properties. To validate the modified
model, the external and internal flow fields, such as hydrofoil NACA0015 and
nozzle, are calculated, respectively. The hydro-foil NACA0015?s cavitation
characteristic is calculated by the modified model at different temperatures.
The pressure coefficient is found in accordance with the experimental data.
The nozzle cavitation under the thermodynamic condition is calculated and
compared with the experiment.
Evaluation of Nusselt number for a flow in a microtube using second-order slip model
Authors: Cetin Barbaros , Bayer Ozgur
Published: April 2011

In this paper, the fully-developed temperature profile and corresponding
Nusselt value is determined analytically for a gaseous flow in a microtube
with a thermal boundary condition of constant wall heat flux. The flow
assumed to be laminar, and hydrodynamically and thermally fully developed.
The fluid is assumed to be constant property and incompressible. The effect
of rarefaction, viscous dissipation and axial conduction, which are
important at the microscale, are included in the analysis. Second-order slip
model is used for the slip-flow and temperature jump boundary conditions for
the implementation of the rarefaction effect. Closed form solutions for the
temperature field and the fully-developed Nusselt number is derived as a
function of Knudsen number, Brinkman number and Peclet number.
Determination of temperature distribution for annular fins with temperature dependent thermal conductivity by HPM
Authors: Ganji Domiri , Ganji Ziabkhsh , Ganji Domiri
Published: April 2011

In this paper, homotopy perturbation method has been used to evaluate the
temperature distribution of annular fin with temperature-dependent thermal
conductivity and to determine the temperature distribution within the fin.
This method is useful and practical for solving the nonlinear heat transfer
equation, which is associated with variable thermal conductivity condition.
The homotopy perturbation method provides an approximate analytical solution
in the form of an infinite power series. The annular fin heat transfer rate
with temperature-dependent thermal conductivity has been obtained as a
function of thermo-geometric fin parameter and the thermal conductivity
parameter describing the variation of the thermal conductivity
Meshless local RBF-DG for 2-D heat conduction: A comparative study
Authors: Soleimani Soheil , Ganji Domiri , Ghasemi Esmaiil , Jalaal Maziar , Bararnia Hasan
Published: April 2011

Meshless local radial basis function-based differential quadrature method is
applied to 2-D conduction problem. Numerical results are compared with those
gained by homotopy perturbation method. Outcomes are presented through graphs
which prove the accuracy of homotopy perturbation method and its
applicability in heat transfer problems.
A new model for flow and heat of a power law fluid in a pipe
Authors: Li Botong , Zheng Liancun , Zhang Xinxin
Published: April 2011

In this paper, a new model is proposed for flow and heat transfer of a power
law fluid in a pipe. The flow is hydro-dynamically fully-developed and
laminar while the characteristic of the fluid viscosity changes with the
entrance distance considered. We assume that the power-law index is no longer
a constant but a function of the entrance distance. Also, in terms of analogy
between the viscous boundary layer and the thermal one, the thermal diffusion
coefficient is considered as a power-law function of temperature gradient as
Zheng?s model. A control volume technique based on the finite difference
model coupled with the LU decomposition method is adopted and the least
squares polynomial is used to approximate the non-linear item. The results
show that the heat transfer behavior strongly depend on the value of the
power law index.
Similarity solution for natural convection from a moving vertical plate with internal heat generation and a convective boundary condition
Authors: Makinde Oluwole
Published: April 2011

Steady laminar natural convection flow over a semi-infinite moving vertical
plate in the presence of internal heat generation and a convective surface
boundary condition is examined in this paper. It is assumed that the left
surface of the plate is in contact with a hot fluid while the cold fluid on
the right surface of the plate contains a heat source that decays
exponentially with the classical similarity variable. The governing
non-linear partial differential equations have been transformed by a
similarity transformation into a system of ordinary differential equations,
which are solved numerically by applying shooting iteration technique
together with fourth order Runge-Kutta integration scheme. The effects of
physical parameters on the dimensionless velocity and temperature profiles
are depicted graphically and analyzed in detail. Finally, numerical values of
physical quantities, such as the local skin-friction coefficient and the
local Nusselt number are presented in tabular form.
A comparison of traditional and computer-aided bracket placement methods
Authors: Israel Matthew , Kusnoto Budi , Evans Carla A. , BeGole Ellen
Published: April 2011

Objective:

To test the hypothesis that there is no difference in the accuracy of bracket placement produced by OrthoCAD iQ indirect bonding (IDB) and that of an in-house fabricated IDB system by measuring the quality of intra-arch dental alignment at the end of simulated orthodontic treatment.

Materials and Methods:

Twenty-eight artificial teeth were arranged to resemble a typical preorthodontic malocclusion. Forty-six sets of models were duplicated from the original malocclusion and randomly divided into two sample groups. Half of the models had their bracket positions selected by OrthoCAD, while the others were completed by a combination of faculty and residents in a university orthodontic department. Indirect bonding trays were fabricated for each sample and the brackets were transferred back to the original malocclusion following typical bonding protocol. The individual teeth were ligated on a .021 × .025-inch stainless steel archwire to simulate their posttreatment positions. The two sample groups were compared using the objective grading system (OGS) originally designed by the American Board of Orthodontics.

Results:

The mean total OGS score for the OrthoCAD sample group was 39.25 points, while the traditional IDB technique scored 41.00 points. No statistical difference was found between total scores or any of the four components evaluated. Similar ranges of scores were observed, with the OrthoCAD group scoring from 30 to 52 points and the traditional IDB group scoring from 33 to 53 points.

Conclusions:

The hypothesis is not accepted. OrthoCAD iQ does not currently offer a system that can position orthodontic brackets better or more reliably than traditional indirect bonding techniques.
On the index of nonlocal elliptic operators for compact Lie groups
Authors: Savin Anton
Published: April 2011

We consider a class of nonlocal operators associated with a compact Lie group G acting on a smooth manifold. A notion of symbol of such operators is introduced and an index formula for elliptic elements is obtained. The symbol in this situation is an element of a noncommutative algebra (crossed product by G) and to obtain an index formula, we define the Chern character for this algebra in the framework of noncommutative geometry.
Erosion Behavior of Glass-epoxy Composites Filled with SiC from Bamboo Leaf
Authors: Mantry S. , Mohapatra Sankar , Mohapatra S. , Singh S. K. , Mandal A. , Satapathy A.
Published: April 2011

The present article reports the processing, mechanical characterization and solid particle erosion response of a new class of multi phase composites consisting of epoxy resin reinforced with E-glass fiber and SiC particulates. The SiC powder synthesized from bamboo leaf employing DC extended thermal plasma technique has been used as the filler in this glass-epoxy composite. It is observed that with increasing percentage of filler particles, there is a decline in tensile and flexural strength, but there is significant improvement in hardness and erosion wear performance. It is also observed that, among all the factors, impact velocity is the most significant factor followed by filler percentage and impingement angle, while erodent size has the least significance on erosion of the hybrid composite. Taguchi's orthogonal arrays have been used to identify the controlling factors influencing the erosion wear rate.
Modelling Behaviour of PET for Stretch and Micro-Blow Moulding Applications Using an Elasto-Visco-Plastic Material Model
Authors: Mir H. , Thibault F. , DiRaddo R.
Published: April 2011

Polyethylene terephthalate (PET) has been widely used in the stretch blow moulding (SBM) process for packaging applications. Finite element analysis has become extensively useful for assessing container designs and enabling the designers to perform analyses earlier in the design cycle to determine the best material and the best structure. However, there are several challenging issues due to various processing parameters and complex material behaviour, which is both temperature and strain-rate dependent. In this paper, we generalize the G'Sell-Jonas law in the three-dimensional (3D) case to model and simulate the elasto-visco-plastic (EVP) behaviour of PET, taking into account strain-hardening and strain-softening. In addition, it is observed that the internal pressure (inside the preform) is significantly different from the nominal pressure (imposed in the blowing device upstream) since the internal pressure and the enclosed volume of the preform are fully coupled. In order to accurately simulate this phenomenon, a thermodynamic model was used to characterize the pressure-volume relationship (PVR). The predicted pressure evolution is therefore more realistic when imposing only the machine power of the blowing device (air compressor or vacuum pump). Mechanical and temperature equilibrium equations are fully nonlinear and solved separately with implicit schemes on the current deformed configuration, which is updated at each time step. Biaxial characterization tests were used to determine the model parameters in order to simulate the SBM process using the PVR. Three industrial case studies, comparing simulated thickness predictions to experimental measurements, will be presented in order to illustrate the applicability of the proposed model.
Factorial Optimisation of the Effects of Melt Spinning Conditions on Biodegradable As-spun Aliphatic-Aromatic Co-Polyester Fibres
Authors: Younes B. , Fotheringham A. , Mather R.
Published: April 2011

In order to optimize the melt spinning process of biodegradable as-spun linear aliphatic-aromatic co-polyester fibres, a fractional factorial experimental design and appropriate statistical analysis for the thirty-two screening trials involving five control parameters were used. Depending on previous studies (Younes and Fotheringham, 2011a, Younes, et al., 2009, 2010, Younes, et al., 2011b), the low melt flow index grade has been utilized in this work. Die head pressure of the extrusion machine, a range of crystallographic orders presented as full-width half-maximum of an X-ray scattering of as-spun fibres and thermo-graphic measurement of extruded filament in the air quench cooling window were investigated. Statistical analyses explained the relationship between, on the one hand, throughput flow rate and spinning temperature of filaments and, on the other hand, the crystallographic structure of the as-spun filaments. It has been found that spinning temperature and metering pumps speed are by far the most important factors affecting the die head pressure. Low spinning temperature leads to higher viscosity, higher flow resistance through the spinneret's nozzle and high die head pressure. Crystallographic order is affected significantly by metering pump speed, and the interaction between spinning temperature and quench air cooling speed. Metering pump speed, spinning temperature, winding speed and quench air cooling speed affect the filaments' temperature average. The obtained optimization helps to produce the most satisfactory properties in the biodegradable fibre based textiles, as environmentally-friendly attractive materials alternative to commercial chemical fibres for different applications.
Microstructural Evolution of PP/EPDM/Organoclay Nanocomposites in a Twin Screw Extruder
Authors: Khosrokhavar R. , Naderi G. , Bakhshandeh G. R. , Ghoreishy M. H. R.
Published: April 2011

The offline Microstructure of nanocomposites based on Poly-Propylene (PP), Ethylene-Propylene Diene Monomer (EPDM) and Cloisite 15A along the twin screw extruder barrel was investigated by X-Ray diffraction, Transmission Electron Microscopy (TEM) and rheological measurements. To assess the effect of screw zones, the microstructural development of nanocomposites along the screw was investigated. Accordingly, dead-stop experiment samples were taken at four different positions of the extruder after abruptly stopping the machine and opening the barrel. Effect of clay loading on the evolution of morphology in the extruder was studied. X-Ray diffraction results showed that at lower clay contents (up to ∼7 wt.%), the intercalation process is independent of screw geometry and accomplishes as soon as the matrix is melted; and on the other hand, excessive melt mixing of the samples containing higher clay loadings (10 wt.%) might lead to the collapse of silicate layers and consequently poor degrees of intercalation/exfoliation. Results were confirmed by TEM micrographs and also XRD patterns of the nanocomposites sensitively detecting the microstructural changes of the samples.