bluuebunny/crossref_metadata_2025 huggingface dataset:
Parallelized Meso-Scale Kinetic Monte Carlo Simulations for SOFC Characterization
Authors: Tada Tomofumi , Watanabe N.
Published: October 2013

We propose a parallelized meso-scale kinetic Monte Carlo code for SOFC characterization. Five properties included in this code are 1) minimum input of the unit cell to build larger block structures, 2) piling blocks according to the three dimensional morphology, 3) symbolic definition of elementary events, 4) parallel implementation with the domain decomposition in open-MPI hybrid parallelization, and 5) boundary conditions for the closed, periodic, and open conditions. The reliability of the parallelized kMC program was confirmed from the calculated self-diffusion coefficients of oxygen ions in the cubic ZrO2 with 4% oxygen vacancies. The parallelization efficiencies were also tested up to 32 cores calculations, and good parallelization was confirmed.
Impact of Manifolding on Performance of a Solid Oxide Fuel Cell Stack
Authors: Nishida Robert , Beale Steven , Pharoah Jon G.
Published: October 2013

Most analyses of fuel cell stacks consider either transport or electrochemical phenomena, but neglect the coupling between the two. An original mathematical model was developed to solve the transport equations coupled with heterogeneous electrochemical reactions for large stacks with internal/external manifolds. The code was used to determine the effect of utilization on electrochemical performance and temperature distribution. The results are presented in terms of fluid flow, pressure, temperature, voltage, and current density distributions. The discussion highlights the importance of manifold design on performance and thermal management.
Three-Dimensional Numerical Simulations of Heat and Mass Transfer and Degradation in a SOFC Cell Stack
Authors: Mori Tetsuya , Nishimura Kouichi , Suzuki Minoru
Published: October 2013

We developed a three dimensional (3-D) mathematical model for a cell stack to perform comprehensive CFD analyses of degradation over a long period of time. The constructed 3-D CFD model consists of complete components in a practical SOFC stack. We calculated the concentration of the chemical species, the temperature distribution, the potential distribution, and the current density for each part of the stack. We also calculated the incremental electrical resistance using empirical formulas and predicted the change of electrical output and stack temperature distribution caused by degradation.
Microstructural Modeling and Effective Properties of Infiltrated SOFC Electrodes
Authors: Bertei Antonio , Pharoah Jon G. , Gawel Duncan A.W. , Nicolella Cristiano
Published: October 2013

A modeling framework for the microstructural modeling of infiltrated SOFC electrodes is presented. The model numerically reconstructs infiltrated electrodes through a sedimentation algorithm for the backbone generation and a novel Monte Carlo packing algorithm for the random infiltration. Effective properties are evaluated by means of Monte Carlo geometric analysis and finite volume method as a function of the loading and of the particle size of infiltrated particles. Infiltration into ion-conducting and composite backbones is analyzed in this study. Simulations show that the infiltration can lead to an increase in TPB density of about two orders of magnitude if compared with conventional composite electrodes. In addition, infiltration into monocomponent backbones can lead to a TPB density about twice the TPB achievable when infiltrating composite backbones. On the other hand, a critical loading of nanoparticles must be reached in monocomponent backbones while in a composite backbone the infiltration is always beneficial.
Recent Developments of 3D Coupled Multiphysics SOFC Modelling At Forschungszentrum Jülich
Authors: Peksen Murat , Al-Masri Ali , Peters Roland , Blum Ludger , Stolten Detlef
Published: October 2013

The Jülich SOFC modelling group has been performing 3D coupled multiphysics modelling of SOFCs, auxiliary components, as well as whole fuel cell systems since five years. Currently, emphasis has been given to the thermomechanical robust design and process optimisation of full-scale fuel cell stacks and whole fuel cell systems, including all auxiliary components. Particular attention is given to improve the understanding of the steady and transient processes, effecting the robustness and life-time duration of the components that directly influence the performance. Coupled CFD/FEM is used to mimic the thermofluid flow, electrochemical and chemical reactions, as well as thermo- mechanics.
Advanced 3D Imaging and Analysis of SOFC Electrodes
Authors: Tariq Farid , Kishimoto Masashi , Cooper Samuel J. , Shearing Paul R , Brandon Nigel P.
Published: October 2013

Solid Oxide Fuel Cells (SOFC) are electrochemical devices where performance is dependent on reactions inside porous electrode microstructures; their complexity is inadequately described using 2D imaging. Here we use X-ray Nano-CT tomographic techniques to probe 3D electrode structures (anodes and cathodes) at micro-nanometer length scales produced using a focused ion beam. Subsequently, micro/nano structural changes in SOFC electrodes are followed and quantified to facilitate understanding changes that occur in shape, structures and morphology at high sub-100nm resolution. Time-resolved (4D) imaging revealed Ni-YSZ oxidation markedly increased above 500 ºC and LSCF densification at 700 ºC may close pores. Utilising 3D electrode data as geometric inputs for numerical models, revealed that increased strains were located at Ni-YSZ interfaces and at microstructure constrictions for both anodes and cathodes when heated. The results show nano/micro structural changes can affect the performance of SOFC electrodes. This combined experimental and modelling approach can help in establishing structure/performance relationships providing key insights important for transport, electrochemistry and strains in both SOFC anodes and cathodes and understanding sources of performance degradation.
Simulation of Cracking of Electrode Assembly in Planar Solid Oxide Fuel Cell
Authors: Lin Chih-Kuang , Anam Khairul , Wu Si-Han , Lee Ruey-Yi
Published: October 2013

Cracking characteristics of the positive electrode-electrolyte-negative electrode (PEN) assembly under thermal stresses in a planar solid oxide fuel cell (SOFC) stack are studied, using finite element analysis (FEA). A 3-D FEA model is constructed for a multiple-cell stack to perform thermal stress analysis at both steady operation and shutdown stages. The stress intensity factors for various combinations of surface crack shape (semicircular and semi-elliptical) and size (1 µm, 10 µm, and 100 µm) at the highly stressed regions in the PEN are calculated at both room temperature and steady stage. Simulation results indicate the stress intensity factor is increased with crack size for semicircular surface cracks. A deep, semi-elliptical surface crack tends to grow wider, while a shallow one tends to grow deeper.
Improvement of SOFC System Efficiency by Incorporating Thermoelectric Power Generation Heat Exchanger
Authors: Terayama Takeshi , Nagata Susumu , Tanaka Yohei , Momma Akihiko , Kato Tohru , Yamamoto Atsushi
Published: October 2013

The effects of replacing a water heater at a bottom of 700 W class SOFC system with thermoelectric generation heat exchanger (TEG-HEX) was investigated by numerical simulation. A 2205 cm3 large TEG-HEX can generate additional power of 11.5 W in the case of each TE element height = 0.9 cm and heat transfer enhance rate = 3.0. This output power corresponds to improvement of SOFC power generation efficiency by 0.756 points. Increasing TE elements height are effective to increase output power of TEG-HEX, however, this leads to substantial decrease of power density estimated on TE elements volume. Decrease in the power density leads directly to higher cost, thus we should regard the power density as guiding principle of practical design. In addition, 30 % of the downstream of the TEG-HEX generate low power, thus cutting down this wasted part leads to improved power density and cost.
Density Functional Theory Calculation of Spin-State Transition in LaCoO3
Authors: Ishimoto Takayoshi , Ito Yumi , Kohno Haruhiko , Koyama Michihisa
Published: October 2013

We analyzed the dependence of X-ray absorption spectra for Co 2p orbital of LaCoO3 on the Hubbard U and lattice parameters by using the density functional theory (DFT) method. The X-ray absorption spectra and partial density of states (PDOS) are studied with the different U parameters ranging from 2.5 to 7.8. The characteristic peak position of X-ray absorption spectra is also investigated for different structures: i.e., the O atom positions assuming the displacement by thermal vibrations, the lattice expansion and the crystalline lattice distortion. The effect of the above parameters on the X-ray absorption spectra are discussed on the basis of theoretical calculation results.
Model Based Interpretation of Coupled Gas Conversion and Diffusion in SOFC-Anodes
Authors: Geisler Helge , Kromp Alexander , Hirn Sebastian , Weber André , Ivers-Tiffée Ellen
Published: October 2013

An approach to the understanding of the gas transport phenomena within the fuel gas channel and corresponding electrode substrate of Solid Oxide Fuel Cells (SOFC) via electrochemical impedance modeling is presented. In this work, a transient FEM-model is developed in COMSOL Multiphysics, with the aim to simulate electrochemical impedance spectra (EIS) of planar Anode Supported SOFCs (ASC) operated with H2/H2O fuel gas mixtures. Output of the isothermal 2D-model is a transient, space-resolved prediction of the gas species distribution along the gas channel and within the anode substrate, from which EIS spectra can be simulated. The model is capable of qualitatively reproduce the low-frequency characteristics of EIS spectra measured for different fuel flow rates. After validation with experimental data, the simulation results are used to analyze the gas transport for lower fuel flow rates. The interpretation of the results yields deeper knowledge about the coupling of gas transport phenomena and fuel consumption
Modelling a Methane Fed Solid Oxide Fuel Cell With Anode Recirculation System
Authors: Tsai Tsang-I , Du Shangfeng , Dhir Aman , Williams Arthur A. , Steinberger-Wilckens Robert
Published: October 2013

The high operation temperature of solid oxide fuel cells (SOFCs) allows methane and other hydrocarbons to be directly used as fuels since they could be self-reformed inside the cells. However, carbon deposition caused by the reforming processes at the anode side usually leads to a significant reduction of triple phase boundary (TPB) and resulting a poor SOFC performance or even complete failure. According to previous research, the recycling of water vapour from the anode exhaust could possibly overcome this problem but also decrease the SOFC's efficiency. In this work, Matlab® simulink® is used to optimise the recycle rates under different conditions and for building a high performance control system that allows minimised steam addition to the methane fuel stream.
Detailed Kinetic Modeling for SOFC Ni Pattern Anodes Fuelled by Methane
Authors: Ogura Teppei , Kohno Haruhiko , Liu Shixue , Ishimoto Takayoshi , Koyama Michihisa , Tsukikawa Hisayoshi , Tajima Masaki
Published: October 2013

High SOFC operating temperature allows direct internal reforming (DIR) of methane within the SOFC anode. However, carbon formation reduces considerably the performance and durability of the cells. A key step towards improving SOFC performance is to understand the detailed surface kinetics and electrochemistry for DIR of methane at the triple phase boundaries (TPBs) in SOFC anodes. In this study, we have performed kinetic simulations with a numerical model on Ni pattern anode, combined with surface reactions, charge transfer reactions, and diffusions for DIR of methane. The I-V characteristics of SOFC near TPBs are discussed.
Fuel-Flex SOFC Running on Internal Gradual Reforming
Authors: Nóbrega Shayenne D. , Fonseca Fabio C. , Gelin Patrick , Noronha Fabio B. , Georges Samuel , Steil M. Cesar
Published: October 2013

Electrolyte-supported single fuel cells based on yttria-stabilized zirconia components with a ceria-based catalytic layer added to the anode were operated with three different fuels: hydrogen, methane, and ethanol. Methane and ethanol were directly fed to the fuel cells without water or any oxidizing agent. Fuels were interchanged during continuous polarization and fuel cell accumulated ~160 hours of operation delivering comparable current densities for each fuel. Such result was supported by stability curves, impedance spectroscopy, and energy-dispersive X-ray spectroscopy analyses, which showed that deleterious carbon deposits are absent in the anode of tested fuel cells.
Biomass Gasifier–SOFC Systems: From Electrode Studies to the Development of Integrated Systems and New Applications
Authors: Aravind P.V. , Liu Ming , Fan Liyuan , Promes Eva , Giraldo Sandra , Woudstra Theo
Published: October 2013

An overview of the research activities and on-going multiple projects at Delft University of Technology aimed at the development of Gasifier–Solid Oxide Fuel Cell (SOFC) based power plants are presented. Biosyngas generated in gasifiers consists of a mixture of carbon monoxide (CO), carbon dioxide (CO2), methane (CH4), hydrogen (H2), nitrogen (N2), water vapor (H2O), and minor impurities. Biosyngas can be a good fuel for SOFCs provided that the gas is sufficiently cleaned. Influence of biosyngas compositions and biomass-derived contaminants on SOFCs is presented and the removal of potential contaminants such as tar, particulates, H2S, HCl, and alkali compounds from biosyngas is discussed. It appears that the gasification product gas can be cleaned to meet the requirements of SOFCs using currently known gas cleaning methods. Additionally, a brief discussion on the achievable system efficiencies with gasifier–SOFC systems is presented. Innovative applications of the gasifier-SOFC systems being developed at Delft, such as advanced gasifier–SOFC systems for toilet development, are also presented.
Methanol as an Oxygenated SOFC Fuel: An In Situ Optical Analysis of the Fuel Utilization Chemical Mechanism
Authors: Pomfret Michael B , Steinhurst Daniel A , Owrutsky Jeffrey C
Published: October 2013

Methanol utilization in solid oxide fuel cells (SOFCs) is studied with Fourier-transform IR emission spectroscopy and near-IR thermal imaging and the results are compared to the methane case. Adsorbed CO2 is identified on the anode surface of the SOFCs with both fuels. The stronger surface CO2 IR signal with methanol indicates more complete fuel oxidation. Methanol pyrolyzes to CO and H2, resulting in less carbon deposition than methane. The current dependence of surface and gas-phase species show methanol pyrolysis is more efficient at higher temperatures. These results provide clear mechanistic insight into fuel breakdown and oxidation in SOFCs.
The Effect of Carbon Fiber Growth on the Deactivation of Nickel-Based Anode for Solid Oxide Fuel Cells Operated on Methane
Authors: Xiao Jie , Xie Yongmin , Zhang Li , Liu Jiang
Published: October 2013

Solid oxide fuel cells (SOFC) with Ni-based anode support were prepared and operated on humidified methane fuel at three different temperatures (700, 750, 800 oC). Carbon deposition formed at three different temperatures was investigated by SEM and EDX measurements. Results showed that at 700 oC carbon fibers were found growing on the anode with concomitant deactivation and pulverization of the anode support while at higher temperatures of 750 or 800 oC most of the carbon dissolved into the Ni particles with accompanying fracture of the cell. The deactivation mechanism of Ni-based anode in SOFC operated on carbon-containing fuel is analyzed in terms of carbon fiber growth catalyzed by nickel particles. Also some suggestions on protecting Ni-based anode from deactivation by carbon fiber growth are proposed according to the mechanism of carbon fiber growth.
Study on Fuel Composition for the Performance Enhancement of Solid Oxide Fuel Cell Operated with Biodiesel Fuel
Authors: Tran Quang Tuyen , Shiratori Yusuke , Kakihara Yusuo , Kitaoka Takuya , Sasaki Kazunari
Published: October 2013

In principle, direct internal reforming of practical biodiesel fuels (BDFs) in solid oxide fuel cell (SOFC) is viable. However, direct feed of practical BDFs to a SOFC caused severe carbon deposition accompanied by C2H4 formation, which were more significant for higher degree of unsaturation of BDFs. Performance of SOFC running on BDF can be enhanced by increasing the content of a fatty acid methyl ester (FAME) with lower degree of unsaturation. To suppress formation of carbon and C2H4, a flexible catalyst composed of inorganic fiber network was applied for the operation of SOFC running on FAMEs. In this study, rather high power density of 0.84 W cm-2 at 0.7 V was achieved in the feed of a mixture of oleic- and palmitic-FAMEs.
Hybrid Direct Carbon Fuel Cells with Different Types of Mineral Coal
Authors: Jiang Cairong , Ma Jianjun , Arenillas Ana , Irvine John T. S.
Published: October 2013

Three types of coal, anthracite, bituminous and lignite with no pretreatment, were investigated in hybrid direct carbon fuel cells (HDCFC). The HDCFC is composed of 1 mm YSZ electrolyte-supported cell with a NiO-YSZ anode and a LSM-YSZ cathode, and lithium-potassium carbonate mixed with coal in the anode chamber. Anthracite and bituminous coals show promising performance. Bituminous coal shows good initial cell performance as well as short term durability in two hour tests; whilst anthracite coal shows good initial cell performance but a slightly faster performance drop as compared to bituminous coal. It seems that coal with high carbon content and low sulphur content is desirable for direct carbon fuel cell application. Gas analysis shows that the ratio of carbon to oxygen content in coal, is likely to be of importance for the cell performance in terms of carbon oxidation process.
Innovative Dual Membrane Architecture for Reversible Fuel Cells
Authors: Viviani Massimo , Thorel Alain Sylvain , Barbucci Antonio , Vladikova Daria , Chesnaud Anthony , Genov Ivaylo , Raikova Gergana , Mercadelli Elisa , Piccardo Paolo , Carpanese Maria Paola , Stoynov Zdravko , Presto Sabrina , Sanson Alessandra
Published: October 2013

Steam electrolysis by means of reversible Fuel Cells is a promising concept for compensating the intermittency of renewable energy sources. Several tests on SOFC stacks operated in reverse mode (SOEC) reported faster degradation than in power production mode. Although not completely clarified, the degradation mechanisms appear partly related to the higher steam concentration at the electrode compartments. This work introduces a novel type of cell with dual anionic-protonic conductivity, which allows the separation of the steam compartment from the electrodes compartments. The concept is presented together with a set of experimental results pointing out the potential advantages of this approach.
Degradation Study of the La0.6Sr0.4Co0.2Fe0.8O3 Solid Oxide Electrolysis Cell (SOEC) Anode after High Temperature Electrolysis Operation
Authors: Lay-Grindler Elisa , Laurencin Jérôme , Villanova Julie , Kieffer Isabelle , Usseglio-Viretta François , Le Bihan Tristan , Bleuet Pierre , Mansuy Aurore , Delette Gérard
Published: October 2013

Microstructural evolution of a Solid Oxide Electrolyser Cell (SOEC) La0.6Sr0.4Co0.2Fe0.8O3 (LSCF) anode is investigated using 3D reconstruction techniques both on a reference and a long-term tested cell. In this framework, reconstructions have been obtained from focused ion beam-scanning electron microscopy and synchrotron X-ray nano-tomography techniques. Microstructural properties extracted from the 3D reconstructions exhibit a slight evolution during the test. Synchrotron X-ray Absorption Spectroscopy (XAS) was also performed, and a modification of the cobalt oxidation state is found. LSCF conductivity decrease due to the change in Co mixed valence has been discussed. Evolutions of both morphological parameters and electrical conductivity were introduced in an in-house micro model to evaluate their impacts on the electrode degradation.
Influence of the Anode Gas Flow Rate and Composition on Solid Oxide Electrolysis Cell Performance
Authors: Nechache A. , Cassir Michel , Ringuedé A.
Published: October 2013

Electrochemical Impedance Spectroscopy (EIS) is a powerful tool to get a deeper insight on the performance of high-temperature electrolysis cells. Indeed, when used in particular conditions, this technique allows distinguishing different phenomena contributing to electrochemical reactions and degradation mechanisms. Besides, the two-electrode configuration allows applying EIS to any kind of single cell. In this study, EIS and chronopotentiometry were combined in order to analyze the influence of the anode gas flow rate and composition on the electrochemical performance of a commercial cathode-supported cell, at different temperatures and current densities.
Fast Switching Electrochromic Devices Containing Optimized BEMA/PEGMA Gel Polymer Electrolytes
Authors: Garino N. , Zanarini S. , Bodoardo S. , Nair J. R. , Pereira S. , Pereira L. , Martins R. , Fortunato E. , Penazzi N.
Published: October 2013

An optimized thermoset gel polymer electrolyte based on Bisphenol A ethoxylate dimethacrylate and Poly(ethylene glycol) methyl ether methacrylate (BEMA/PEGMA) was prepared by facile photo-induced free radical polymerisation technique and tested for the first time in electrochromic devices (ECD) combining WO3sputtered on ITO as cathodes and V2O5electrodeposited on ITO as anodes. The behaviour of the prepared ECD was investigated electrochemically and electro-optically. The ECD transmission spectrum was monitored in the visible and near-infrared region by varying applied potential. A switching time of ca. 2 s for Li+insertion (coloring) and of ca. 1 s for Li+de-insertion (bleaching) were found. UV-VIS spectroelectrochemical measurements evidenced a considerable contrast between bleached and colored state along with a good stability over repeated cycles. The reported electrochromic devices showed a considerable enhancement of switching time with respect to the previously reported polymeric ECD indicating that they are good candidates for the implementation of intelligent windows and smart displays.
Incident Occurrence Modeling during Hurricane Evacuation Events: The Case of Alabama's I-65 Corridor
Authors: Fonseca Daniel J. , Lou Yingyan , Moynihan Gary P. , Gurupackiam Saravanan
Published: October 2013

Contraflow on major evacuation routes is one scheme that has been adopted in many Gulf and eastern coastal states for hurricane evacuation. The idea is to reverse one direction of the roadway in order to accommodate the often substantially increased travel demand moving away from the impact area. Efficient planning and operation is critical to a successful contraflow implementation. Alabama has an approximately 140-mile contraflow segment on I-65 between exit 31 and exit 167 and has carried out contraflow operations several times in past hurricane evacuations. The timing for the deployment of equipment and personnel and the initiation and termination of actual contraflow affects the effectiveness, safety, and cost of the operation. Researchers from the University of Alabama were tasked with the design of a decision support system for contraflow evacuation planning. The conceived decision support system consists of three main modules: the demand module, the network optimization module, and the incident and characterization module. This paper focuses on the design of the traffic incident generation and characterization module of the planned decision support system.
Vascular Tortuosities of the Upper Eyelid: A New Clinical Finding in Fabry Patient Screening
Authors: Michaud Langis
Published: October 2013

Purpose. To report a new clinical finding related to Fabry disease.Methods. Fabry subjects were enrolled in the study, matched for age and sex with healthy individuals as a control group. This is a prospective review of all upper lid pictures taken for every subject at their last visit. A 4-step grading scale is proposed to classify this new entity.Results. Group A (Fabry) comprised 16 males and 22 females, aged 40 (±14) years on average. Group B (control) comprised 7 males and 8 females, aged 37 (±12) Vessels tortuosity was identified on the external superior lid in 36 of the Fabry patients (94.7%), while none of the subjects in group B showed similar vessels tortuosity. In addition, microaneurysms (MAs) were found in 10/38 group A subjects while none in group B presented a similar finding. The differences are highly significant.Conclusion. This paper proposes that blood vessels tortuosity on the upper eyelid be recognized as a new clinical entity for inclusion among the classic ocular manifestations of Fabry’s disease. Without evidence of any negative impact, it should be considered a benign sign contributing to evidence of suspected Fabry disease.
On the Jacobson Radical of an (m,n)-Semiring
Authors: Zhu Yongwen
Published: October 2013

The notion of n-ary semimodules is introduced so that the Jacobson radical of an (m,n)-semiring is studied and some well-known results concerning the Jacobson radical of a ring (a semiring or a ternary semiring) are generalized to an (m,n)-semiring.
Membership-Degree Preserving Discriminant Analysis with Applications to Face Recognition
Authors: Yang Zhangjing , Liu Chuancai , Huang Pu , Qian Jianjun
Published: October 2013

In pattern recognition, feature extraction techniques have been widely employed to reduce the dimensionality of high-dimensional data. In this paper, we propose a novel feature extraction algorithm called membership-degree preserving discriminant analysis (MPDA) based on the fisher criterion and fuzzy set theory for face recognition. In the proposed algorithm, the membership degree of each sample to particular classes is firstly calculated by the fuzzyk-nearest neighbor (FKNN) algorithm to characterize the similarity between each sample and class centers, and then the membership degree is incorporated into the definition of the between-class scatter and the within-class scatter. The feature extraction criterion via maximizing the ratio of the between-class scatter to the within-class scatter is applied. Experimental results on the ORL, Yale, and FERET face databases demonstrate the effectiveness of the proposed algorithm.
Output Feedback Control of Discrete Impulsive Switched Systems with State Delays and Missing Measurements
Authors: Li Xia , Karimi Hamid Reza , Xiang Zhengrong
Published: October 2013

This paper is concerned with the problem of dynamic output feedback (DOF) control for a class of uncertain discrete impulsive switched systems with state delays and missing measurements. The missing measurements are modeled as a binary switch sequence specified by a conditional probability distribution. The problem addressed is to design an output feedback controller such that for all admissible uncertainties, the closed-loop system is exponentially stable in mean square sense. By using the average dwell time approach and the piecewise Lyapunov function technique, some sufficient conditions for the existence of a desired DOF controller are derived, then an explicit expression of the desired controller is given. Finally, a numerical example is given to illustrate the effectiveness of the proposed method.
Microclimate Variations between Semienclosed and Open Sections of a Marathon Route
Authors: Wong Paulina , Lai Poh-Chin , Hart Melissa
Published: October 2013

The Hong Kong Standard Chartered Marathon, held annually, is one of the most popular international marathon events. Its primarily urban environmental setting characterized by high-density urban areas, semienclosed tunnels, and suspension bridges, together with the herds of runners, has an influence on the microclimate along the marathon course. This study focused on assessing and comparing variations in temperature and vapour pressure (vis-à-vis relative humidity) against the crowd of runners, or the herd effects, in two different environmental settings along the marathon course: semienclosed (a tunnel) versus open space (a suspension bridge). A series of small iButtons were deployed at strategic locations along the course to undertake minute-by-minute measurements of temperature and relative humidity. It was found that herd effects of varying degrees were present in both semienclosed and open settings. Various environmental differences also played a role in ameliorating or amplifying the climatological effects of the herd of runners. Our study suggests that microclimate variations in different environmental settings and crowd conditions could have an impact on runners. This new knowledge can inform the design of marathon routes. It also establishes the feasibility of employing the iButton logging sensors for widespread deployment and monitoring of meteorological situations.
WSPT's Competitive Performance for Minimizing the Total Weighted Flow Time: From Single to Parallel Machines
Authors: Tao Jiping , Liu Tundong
Published: October 2013

We consider the classical online scheduling problem over single and parallel machines with the objective of minimizing total weighted flow time. We employ an intuitive and systematic analysis method and show that the weighted shortest processing time (WSPT) is an optimal online algorithm with the competitive ratio ofP+1for the case of single machine, and it is (P+(3/2)−(1/2m))-competitive for the case of parallel machines(m>1), wherePis the ratio of the longest to the shortest processing time.
The Flow and Heat Transfer of a Nanofluid Past a Stretching/Shrinking Sheet with a Convective Boundary Condition
Authors: Mansur Syahira , Ishak Anuar
Published: October 2013

The boundary layer flow of a nanofluid past a stretching/shrinking sheet with a convective boundary condition is studied. Numerical solutions to the governing equations are obtained using a shooting method. The results are found for the local Nusselt number and the local Sherwood number as well as the temperature and concentration profiles for some values of the convective parameter, stretching/shrinking parameter, Brownian motion parameter, and thermophoresis parameter. The results indicate that the local Nusselt number is consistently higher for higher values of the convective parameter. However, the local Nusselt number decreases with increasing values of the Brownian motion parameter as well as the thermophoresis parameter. In addition, the local Sherwood number increases with increasing Brownian motion parameter and decreases with increasing convective parameter and thermophoresis parameter.
Effect of the Evaporative Cooling on the Human Thermal Comfort and Heat Stress in a Greenhouse under Arid Conditions
Authors: Abdel-Ghany A. M. , Al-Helal I. M. , Shady M. R.
Published: October 2013

Thermal sensation and heat stress were evaluated in a plastic greenhouse, with and without evaporative cooling, under arid climatic conditions in Riyadh, Saudi Arabia. Suitable thermal comfort and heat stress scales were selected for the evaluation. Experiments were conducted in hot sunny days to measure the required parameters (i.e., the dry and wet bulb temperatures, globe temperature, natural wet bulb temperature, and solar radiation flux) in the greenhouse. The results showed that in the uncooled greenhouse, workers are exposed to strong heat stress and would feel very hot most of the day time; they are safe from heat stress risk and would feel comfortable during night. An efficient evaporative cooling is necessary during the day to reduce heat stress and to improve the comfort conditions and is not necessary at night. In the cooled greenhouse, workers can do any activity: except at around noon they should follow a proposed working schedule, in which the different types of work were scheduled along the daytimes based on the heat stress value. To avoid heat stress and to provide comfort conditions in the greenhouses, the optimum ranges of relative humidity and air temperature are 48–55% and 24–28°C, respectively.
Ultra-Low Leakage Arithmetic Circuits Using Symmetric and Asymmetric FinFETs
Authors: Moshgelani Farid , Al-Khalili Dhamin , Rozon Côme
Published: October 2013

We are examining different configurations and circuit topologies for arithmetic components such as adder and compressor circuits using both symmetric and asymmetric work-function FinFETs. Based on extensive characterization data, for the carry generation of a mirror full adder using symmetric devices, both leakage current and delay are decreased by 25% and 50%, respectively, compared to results in the literature. For the 14-transistor (14T) full adder topology, both leakage and delay are decreased by 23% and 29%, respectively, compared to the mirror topology. The 14T adder topology, using asymmetric devices without any additional power supply, achives reduction in leakage current by 85% with a small degradation of 7% in delay. The compressor circuits, using asymmetric devices for one of the proposed configurations, achieve reduction in both leakage current and delay by 86% and 4%, respectively. All simulations are based on a 25 nm FinFET technology using the University of Florida UFDG model.
Global Modeling of N2O Discharges: Helicon Plasma Thruster Application
Authors: Katsonis Konstantinos , Berenguer Chloe
Published: October 2013

A global (volume averaged) model pertaining to N2O discharges is used to design and to study electric propulsion applications, especially helicon plasma thrusters fed with pure N2O and also with N2/O2mixtures including air. Results obtained for N2O feeding are discussed and compared to those pertaining to an air-like N2/O2mixture feeding. An interesting similarity is observed. Comparison of the N2O model results versus those of Ar shows lower ionization percentage with higher electron temperature for N2O propellant.
Microscale Investigation of Arsenic Distribution and Species in Cement Product from Cement Kiln Coprocessing Wastes
Authors: Yang Yufei , Xue Jingchuan , Huang Qifei
Published: October 2013

To improve the understanding of the immobilization mechanism and the leaching risk of Arsenic (As) in the cement product from coprocessing wastes using cement kiln, distribution and species of As in cement product were determined by microscale investigation methods, including electron probe microanalysis (EPMA) and X‐ray absorption spectroscopy. In this study, sodium arsenate crystals (Na3AsO412H2O) were mixed with cement production raw materials and calcined to produce cement clinker. Then, clinker was mixed water to prepare cement paste. EPMA results showed that As was generally distributed throughout the cement paste. As content in calcium silicate hydrates gel (C‐S‐H) was in low level, but higher than that in other cement mineral phases. This means that most of As is expected to form some compounds that disperse on the surfaces of cement mineral phases. Linear combination fitting (LCF) of the X‐ray absorption near edge structure spectra revealed that As in the cement paste was predominantly As(V) and mainly existed as Mg3(AsO4)2, Ca3(AsO4)2, and Na2HAsO4.
Sensitivity of Rabbit Ventricular Action Potential and Ca2+Dynamics to Small Variations in Membrane Currents and Ion Diffusion Coefficients
Authors: Lo Yuan Hung , Peachey Tom , Abramson David , McCulloch Andrew , Michailova Anushka
Published: October 2013

Little is known about how small variations in ionic currents andCa2+andNa+diffusion coefficients impact action potential andCa2+dynamics in rabbit ventricular myocytes. We applied sensitivity analysis to quantify the sensitivity of Shannon et al. model (Biophys. J., 2004) to 5%–10% changes in currents conductance, channels distribution, and ion diffusion in rabbit ventricular cells. We found that action potential duration andCa2+peaks arehighly sensitiveto 10% increase in L-typeCa2+current;moderately influencedby 10% increase inNa+-Ca2+exchanger,Na+-K+pump, rapid delayed and slow transient outwardK+currents, andCl−background current;insensitiveto 10% increases in all other ionic currents and sarcoplasmic reticulumCa2+fluxes. Cell electrical activity is strongly affected by 5% shift of L-typeCa2+channels andNa+-Ca2+exchanger in between junctional and submembrane spaces whileCa2+-activatedCl−-channel redistribution has the modest effect. Small changes in submembrane and cytosolic diffusion coefficients forCa2+, but not inNa+transfer, may alter notably myocyte contraction. Our studies highlight the need for more precise measurements and further extending and testing of the Shannon et al. model. Our results demonstrate usefulness of sensitivity analysis to identify specific knowledge gaps and controversies related to ventricular cell electrophysiology andCa2+signaling.
Reducing the Complexity of Complex Gene Coexpression Networks by Coupling Multiweighted Labeling with Topological Analysis
Authors: Benso Alfredo , Cornale Paolo , Di Carlo Stefano , Politano Gianfranco , Savino Alessandro
Published: October 2013

Undirected gene coexpression networks obtained from experimental expression data coupled with efficient computational procedures are increasingly used to identify potentially relevant biological information (e.g., biomarkers) for a particular disease. However, coexpression networks built from experimental expression data are in general large highly connected networks with an elevated number of false-positive interactions (nodes and edges). In order to infer relevant information, the network must be properly filtered and its complexity reduced. Given the complexity and the multivariate nature of the information contained in the network, this requires the development and application of efficient feature selection algorithms to be able to exploit the topological characteristics of the network to identify relevant nodes and edges. This paper proposes an efficient multivariate filtering designed to analyze the topological properties of a coexpression network in order to identify potential relevant genes for a given disease. The algorithm has been tested on three datasets for three well known and studied diseases: acute myeloid leukemia, breast cancer, and diffuse large B-cell lymphoma. Results have been validated resorting to bibliographic data automatically mined using the ProteinQuest literature mining tool.
Solvability for Discrete Fractional Boundary Value Problems with ap-Laplacian Operator
Authors: Lv Weidong
Published: October 2013

This paper is concerned with the solvability for a discrete fractionalp-Laplacian boundary value problem. Some existence and uniqueness results are obtained by means of the Banach contraction mapping principle. Additionally, two representative examples are presented to illustrate the effectiveness of the main results.
Optimization and Soft Constraints for Human Shape and Pose Estimation Based on a 3D Morphable Model
Authors: Zhang Dianyong , Miao Zhenjiang , Chen Shengyong , Wan Lili
Published: October 2013

We propose an approach about multiview markerless motion capture based on a 3D morphable human model. This morphable model was learned from a database of registered 3D body scans in different shapes and poses. We implement pose variation of body shape by the defined underlying skeleton. At the initialization step, we adapt the 3D morphable model to the multi-view images by changing its shape and pose parameters. Then, for the tracking step, we implement a method of combining the local and global algorithm to do the pose estimation and surface tracking. And we add the human pose prior information as a soft constraint to the energy of a particle. When it meets an error after the local algorithm, we can fix the error using less particles and iterations. We demonstrate the improvements with estimating result from a multi-view image sequence.
A Novel Solar Driven Photocatalyst: Well-Aligned Anodic WO3Nanotubes
Authors: Lai Chin Wei , Abd Hamid Sharifah Bee , Sreekantan Srimala
Published: October 2013

Well-aligned anodic tungsten trioxide (WO3) nanotubes were successfully synthesized by anodization of W foil at 40 V in a bath with electrolyte composed of 1 M of sodium sulphate (Na2SO4) and 0.5 wt% ammonium fluoride (NH4F). The effect of electrochemical anodization times on the formation mechanism of anodic WO3nanotubular structure was investigated. It was found that minimum of 15 min is required for completing transformation from W foil to WO3nanotubular structure with an average diameter of 50 nm and length of 500 nm. The photocatalytic ability of the samples was evaluated by degradation of methyl blue (MB) dye. The results indicate that the surface morphology of anodic WO3affected the photocatalytic MB degradation significantly under solar illumination.
Limit-Point/Limit-Circle Results for Superlinear Damped Equations
Authors: Bartušek M. , Graef John R.
Published: October 2013

The authors study the nonlinear limit-point and limit-circle properties for second-order nonlinear damped differential equations of the form(a(t)|y'|p-1y')'+b(t)|y'|q-1y'+r(t)|y|λ-1y=0,where00, andr(t)>0. Examples to illustrate the main results are included.
Functionally Defective High-Density Lipoprotein and Paraoxonase: A Couple for Endothelial Dysfunction in Atherosclerosis
Authors: Eren Esin , Yilmaz Necat , Aydin Ozgur
Published: October 2013

The endothelium is the primary target for biochemical or mechanical injuries caused by the putative risk factors of atherosclerosis. Endothelial dysfunction represents the ultimate link between atherosclerotic risk factors that promote atherosclerosis. HDL-C is thought to exert at least some parts of its antiatherogenic facilities via stimulating endothelial NO production, nearby inhibiting oxidative stress and inflammation. HDL-C is capable of opposing LDL’s inductive effects and avoiding the ox-LDL’s inhibition of eNOS. Paraoxonase 1 (PON1) is an HDL-associated enzyme esterase which appears to contribute to the antioxidant and antiatherosclerotic capabilities of HDL-C. “Healthy HDL,” namely the particle that contains the active Paraoxonase 1, has the power to suppress the formation of oxidized lipids. “Dysfunctional HDL,” on the contrary, has reduced Paraoxonase 1 enzyme activity and not only fails in its mission but also potentially leads to greater formation of oxidized lipids/lipoproteins to cause endothelial dysfunction. The association of HDL-C PON1 and endothelial dysfunction depends largely on the molecules with exact damaging effect on NO synthase coupling. Loss of nitric oxide bioavailability has a pivotal role in endothelial dysfunction preceding the appearance of atherosclerosis. Analyses of HDL-C and Paraoxonase1 would be more important in the diagnosis and treatment of atherosclerosis in the very near future.
Activin A and Follistatin as Biomarkers for Ectopic Pregnancy and Missed Abortion
Authors: Daponte Alexandros , Deligeoroglou Efthimios , Garas Antonios , Pournaras Spyros , Hadjichristodoulou Christos , Messinis Ioannis E.
Published: October 2013

Activin A as a predictor of pregnancy failure has been the focus of heated debate, but the value of a combined activin A and follistatin (FS) measurement in serum to predict pregnancy failure has not been reported yet. We assessed whether a single serum measurement of the two physiological antagonists at 6–8 weeks gestation could differentiate ectopic pregnancies (EP) or missed abortions (MA) from healthy intrauterine pregnancies (IUP). activin A concentrations were significantly lower in women with EP ( = 30, median value of 264 pg/mL) and women with MA ( = 30, median value of 350 pg/mL) compared to IUP ( = 33, median value of 788 pg/mL); . At a threshold value of 505 pg/mL, activin A had 87.9% sensitivity and 100% specificity and negative predictive value of 0.974 for discriminating an ectopic pregnancy from viable pregnancies. FS was able to discriminate IUP from EP (ROC curve ) as was their ratio (ROC curve ), but was unable to discriminate a MA from an EP. In EP, activin A did not correlate with beta HCG levels. The present findings support the thesis that activin A or FS could be considered promising biomarkers for the discrimination between an IUP and a failed pregnancy (MA or EP).
Phat Diem: Nationalism, Religion, and Identity in the Franco-Viet Minh War
Authors: Spector Ronald H.
Published: October 2013

The wars of postcolonial Asia, although often viewed by U.S. officials as struggles between Communist and non-Communist forces or between colonial powers and independence movements, were in fact far more complex and ambiguous in nature. The conflicts displayed some of the characteristics of civil war, brigandage, and ethnic, regional, and religious warfare. This article exams the experience of Phat Diem, a predominantly Catholic enclave in northern Vietnam, during the First IndochinaWar, to highlight the dynamics of these cross-currents of regionalism, nationalism, and religion. Ultimately Phat Diem's attempts to steer a middle course between Communism and French colonialism ended disastrously, but its story highlights several important but little recognized aspects of the war in Indochina and the nature of Asia's wars in the first decade after the end of World War II.
Computer Virus Sculptures and the Science That Inspired Them
Authors: McCluer Forrest
Published: October 2013

This article explores the remarkable shape and structure of biological viruses through the lens of sculptures composed of parts from discarded computers. The science that inspired these sculptures is briefly reviewed. Collectively, these artworks are called the Computer Virus Sculpture series.
A Mechanism for Explaining the Maximum Intraseasonal Oscillation Center over the Western North Pacific*
Authors: Liu Fei , Wang Bin
Published: October 2013

During late boreal summer (July–October), the intraseasonal oscillation (ISO) exhibits maximum variability over the western North Pacific (WNP) centered in the South China Sea and Philippine Sea, but many numerical models have difficulty in simulating this essential feature of the ISO. To understand why this maximum variability center exists, the authors advance a simple box model to elaborate the potential contribution of the mean-state-dependent atmosphere–ocean interaction. The model results suggest that the WNP seasonal mean monsoon trough plays an essential role in sustaining a strong stationary ISO, contributing to the existence of the maximum intraseasonal variability center. First, the monsoon trough provides abundant moisture supply for the growing ISO disturbances through the frictional boundary layer moisture convergence. Second, the cyclonic winds associated with the monsoon trough provide a favorable basic state to support a negative atmosphere–ocean thermodynamic feedback that sustains a prominent stationary ISO. In an active phase of the ISO, anomalous cyclonic winds enhance the monsoon trough and precipitation, which reduce shortwave radiation flux and increase evaporation; both processes cool the sea surface and lead to an ensuing high pressure anomaly and a break phase of the ISO. In the wintertime, however, the wind–evaporation feedback is positive and sustains the Philippine Sea anticyclone. The result here suggests that accurate simulation of the boreal summer climatological mean state is critical for capturing a realistic ISO over the WNP region.