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Optimization study of a PEM fuel cell performance using 3D multi-phase computational fluid dynamics model

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Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2007年第2期8卷 285-300页

作者： al-BAGhDADI maher A.R. Sadiq al-JANABI haroun A.K.Shahad Department of Mechanical Engineering International Technological University

An optimization study using a comprehensive 3D, multi-phase, non-isothermal model of a PEM （proton exchange membrane） fuel cell that incorporates significant physical processes and key parameters affecting fuel cell performance is presented and discussed in detail. The model accounts for both gas and liquid phase in the same computational domain, and thus allows for the implementation of phase change inside the gas diffusion layers. The model includes the transport of gaseous species, liquid water, protons, energy, and water dissolved in the ion-conducting polymer. Water is assumed to be exchanged among three phases： liquid, vapottr, and dissolved, with equilibrium among these phases being assumed. This model also takes into account convection and diffusion of different species in the channels as well as in the porous gas diffusion layer, heat transfer in the solids as well as in the gases, and electrochemical reactions. The results showed that the present multi-phase model is capable of identifying important parameters for the wetting behaviour of the gas diffusion layers and can be used to identify conditions that might lead to the onset of pore plugging, which has a detrimental effect on the fuel cell performance. This model is used to study the effects of several operating, design, and material parameters on fuel cell performance. Detailed analyses of the fuel cell performance under various operating conditions have been conducted and examined.

关键词： Optimization PEM fuel cell Multi-phase Water transport CFD (computational fluid dynamics)

Protective effect of naringenin on acetic acid-induced ulcerative colitis in rats

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World Journal of Gastroenterology 2013年第34期19卷 5633-5644页

作者： Salim S al-Rejaie hatem M Abuohashish maher M al-Enazi Abdullah h.al-Assaf Mihir Y Parmar Mohammed M Ahmed Department of Pharmacology andToxicology College of PharmacyKing Saud University Department of Medical Laboratory Sciences College of Applied Medical SciencesSalman bin Abdulaziz University Department of Science and Nutrition College of Food and Agricultural SciencesKing Saud University

AIM:To evaluate the ameliorative effect of naringenin(NG)during ulcerative colitis(UC)in ***:Rats were treated with three different doses(25,50 and 100 mg/kg per day)of NG and a single dose of mesalazine(MES,300 mg/kg per day)for seven days prior to ulcerative colitis induction by4%acetic acid(AA).Twenty four hours after AA rectal administration,animals were scarified and the colonic tissues were *** mucus content was estimated using alcian blue dye binding *** colon tissues,levels of total glutathione sulphadryls(T-GSh),non-protein sulphadryls(NP-Sh)and thiobarbituric acid reactive substances(TBARS)were *** activities of the antioxidant enzymes,catalase(CAT)and superoxide dismutase(SOD)were *** of nucleic acids(DNA and RNA)and total protein were also estimated in colon *** levels of tumor necrosis factor-(TNF-),interleukin-1(IL-1),interleukin-6(IL-6),prostaglandin E2(PGE2)and nitric oxide(NO)were *** cross section of colitis tissue the histopathological changes were ***:Colonic mucus content was decreased in AA compared to controls(587.09±65.59 mg/kg vs941.78±68.41 mg/kg,Ph(5.25±0.37 nmol/L vs 3.04±0.24 nmol/L,Ph(3.16±0.04 nmol/L vs 2.16±0.30 nmol/L,Phile TBARS,TNF-,IL-1,IL-6,PGE2 and NO levels(15.09±3.84nmol/L vs 59.90±16.34 nmol/L,Ph UC compared controls *** supplementation,significantly and dose dependently increased the colonic mucus *** elevated TBARS levels were significantly decreased(39.35±5.86nmol/L,P<0

关键词： Naringenin Ulcerative colitis Inflammatory bowel disease Oxidative stress

Preserving Data Secrecy and Integrity for Cloud Storage Using Smart Contracts and Cryptographic Primitives

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Computers, Materials & Continua 2024年第5期79卷 2449-2463页

作者： maher alharby Cybersecurity Department College of Computer Science and EngineeringTaibah UniversityMedina42353Saudi Arabia

Cloud computing has emerged as a viable alternative to traditional computing infrastructures,offering various ***,the adoption of cloud storage poses significant risks to data secrecy and *** article presents an effective mechanism to preserve the secrecy and integrity of data stored on the public cloud by leveraging blockchain technology,smart contracts,and cryptographic *** proposed approach utilizes a Solidity-based smart contract as an auditor for maintaining and verifying the integrity of outsourced *** preserve data secrecy,symmetric encryption systems are employed to encrypt user data before outsourcing *** extensive performance analysis is conducted to illustrate the efficiency of the proposed ***,a rigorous assessment is conducted to ensure that the developed smart contract is free from vulnerabilities and to measure its associated running *** security analysis of the proposed system confirms that our approach can securely maintain the confidentiality and integrity of cloud storage,even in the presence of malicious *** proposed mechanism contributes to enhancing data security in cloud computing environments and can be used as a foundation for developing more secure cloud storage systems.

关键词： Cloud storage data secrecy data integrity smart contracts cryptography

Arsenobetaine and thio-arsenic species in marine macroalgae and herbivorous animals: Accumulated through trophic transfer or produced in situ?

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Journal of Environmental Sciences 2016年第11期28卷 131-139页

作者： Simon Foster William maher Ecochemistry Laboratory Institute for Applied Ecology University of Canberra

Arsenobetaine（AB） and thio-arsenoribosides were measured in common macroalgae species（8 phaeophyta, 4 rhodophyta and 2 chlorphyta）, along the Australian south east coast line. As well, arsenic species profiles were measured for two common marine herbivores, the sea urchin Centrostephanus rodgersii and the fish Odax cyanomelas that graze on these macroalgae to understand if trophic transfer of these species would account for their presence in marine herbivores. AB was found in seven of the fourteen macroalgae species investigated but does not contributed significantly to any of the macroalgae arsenic content（0.01-1.2 μg/g）. AB was found in only two of the brown macroalgae and all the red and green macroalgae（with the exception of Corallina officinalis）. Thio-arsenic species were found sporadically, but not in high concentrations in any of the macroalgae *** present in macroalgae is likely to be associated with epiphytic organisms while thio-arsenoribosides are likely to be produced by decaying parts of damaged macroalgae.A laboratory feeding experiment in which the herbivorous gastropod, Austrocochlea constricta, was fed macroalgae containing thio-arsenoribosides for a 24 hr period every three days showed that these are readily accumulated over a short period. Thio-arsenoribosides in herbivores are therefore probably obtained through trophic transfer. Some AB is also obtained through trophic transfer; however, the presence of trimethylated arsonioribosides,a hypothesized precursor of AB formation in herbivores, suggests that some AB is produced within herbivores from the transformation of arsenoribosides accumulated from their diet.

关键词： Arsenobetaine Arsenic Metabolism Thio-arsenosugars Macroalgae Gastropods

Experimental and Numerical Analyses of the Pull-out Response of a Steel Post/Bovine Bone Cementless Fixation

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Journal of Bionic Engineering 2012年第4期9卷 501-507页

作者： Khaled Gammoudi Mohamed Kharrat maher Dammak National Engineering School of Sfax Electromechanical Systems Laboratory Soukra road km 3.5 B.P. 1173 3038 Sfax Tunisia higher Institute of Technological Studies of Gafsa University campus Sidi Ahmed Zarrouk 2112 Gafsa Tunisia Faculty of Sciences of Gafsa University campus Sidi Ahmed Zarrouk 2112 Gafsa Tunisia Preparatory Institute for Engineering Studies of Sfax Menzel Chaker Road Km 0.5 B.P. 1172 3018 Sfax Timisia

Effect of initial interference fit on pull-out strength in cementless fixation between bovine tibia and smooth stainless steel post was investigated in this study. Compressive behavior of bovine spongious bone was studied using mechanical testing in order to evaluate the elastic-plastic properties in different regions of the proximal tibia. Friction tests were carried out in the aim to evaluate the friction behavior of the contact between bovine spongious bone and stainless steel. A cylindrical stainless steel post inserted in a pre-drilled bovine tibia with an initial interference fit was taken as an in vitro model to assess the contribution of post fixation to the initial stability of the Total Knee Arthroplasty （TKA） tibial component. Pull-out experiments were carried out for different initial interference fits. Finite Element Models （FEM） using local elastic-plastic properties of the bovine bone were developed for the analysis of the experimental ultimate pull-out force results. At the post/bone interface, Coulomb friction was considered in the FEM calculations with pressure-dependent friction coefficient. It was found that the FEM results of the ultimate force are in good agreement with the experimental results. The analysis of the FEM interfacial stresses indicates that the micro-slip initiation depends on the local bone properties.

关键词： total knee arthroplasty bovine bone/steel post fixation interference fit puU-out strength FEM

A Comprehensive Review on Charging Topologies and Power Electronic Converter Solutions for Electric Vehicles

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Journal of Modern Power Systems and Clean Energy 2024年第3期12卷 675-694页

作者： Abdelfatah.ali hossam h.h.Mousa Mostafa F.Shaaban maher A.Azzouz Ahmed S.A.Awad the Department of Electrical Engineering American University of Sharjah26666 SharjahUnited Arab Emirates the Department of Electrical Engineering South Valley University83523 QenaEgypt the Department of Electrical and Computer Engineering University of WindsorWindsorON N9B 3P4 Canada Electrical Engineering Department Qatar UniversityDoha 2713Qatar Department of Electrical and Computer Engineering Sultan Qaboos UniversityMuscat123Oman

Electric vehicles(EVs)are becoming more popular worldwide due to environmental concerns,fuel security,and price *** performance of EVs relies on the energy stored in their batteries,which can be charged using either AC(slow)or DC(fast)***,EVs can also be used as mobile power storage devices using vehicle-to-grid(V2G)*** electronic converters(PECs)have a constructive role in EV applications,both in charging EVs and in ***,this paper comprehensively investigates the state of the art of EV charging topologies and PEC solutions for EV *** examines PECs from the point of view of their classifications,configurations,control approaches,and future research prospects and their impacts on power *** can be classified into various topologies:DC-DC converters,AC-DC converters,DC-AC converters,and AC-AC *** address the limitations of traditional DC-DC converters such as switching losses,size,and high-electromagnetic interference(EMI),resonant converters and multiport converters are being used in high-voltage EV ***,power-train converters have been modified for high-efficiency and reliability in EV *** paper offers an overview of charging topologies,PECs,challenges with solutions,and future trends in the field of the EV charging station applications.

关键词： Charging station charging topology electric vehicle power electronic converter vehicle-to-grid

BROWDER AND SEMI-BROWDER OPERATORS

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Acta Mathematica Scientia 2012年第3期32卷 942-954页

作者： Fatma Fakhfakh maher Mnif D'epartement de Math'ematiques Universit'e de SfaxFacult'e des Sciences de SfaxRoute de SoukraKm 3.5B.P.11713000 SfaxTunisie

In this article, we study characterization, stability, and spectral mapping the- orem for Browder＇s essential spectrum, Browder＇s essential defect spectrum and Browder＇s essential approximate point spectrum of clos... 详细信息

关键词： Browder and semi-Browder operators Browder's essential spectrum Browder's essential defect spectrum Browder's essential approximate point spectrum

Radio Frequency Induction Plasma Spraying of Molybdenum

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Plasma Science and Technology 2003年第4期5卷 1895-1900页

作者：蒋显亮 maher Boulos Institute of Surface and Coatings Technology Central South UniversityChangsha 410083China Plasma Technology Research Center University of SherbrookeSherbrooke J1K 2R1Canada

Radio frequency (RF) induction plasma was used to make free-standing deposition of molybdenum (Mo). The phenomena of particle melting, flattening, and stacking were investigated. The effect of process parameters such as plasma power, chamber pressure, and spray distance on the phenomena mentioned above was studied. Scanning electron microscopy (SEM) was used to analyze the plasma-processed powder, splats formed, and deposits obtained. Experimental results show that less Mo particles are spheroidized when compared to the number of spheroidized tungsten (W) particles at the same powder feed rate under the same plasma spray condition. Molten Mo particles can be sufficiently flattened on substrate. The influence of the process parameters on the flattening behavior is not significant. Mo deposit is not as dense as W deposit, due to the splash and low impact of molten Mo particles. Oxidation of the Mo powder with a large particle size is not evident under the low pressure plasma spray.

关键词： induction plasma molybdenum spheroidi/ation flattening deposition density

ESSENTIal APPROXIMATE POINT SPECTRA FOR UPPER TRIANGULAR MATRIX OF LINEAR RELATIONS

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Acta Mathematica Scientia 2013年第4期33卷 1187-1201页

作者： Souhir ELLEUCh maher MNIF Département de Mathématiques Université de Sfax Faculté des Sciences de SfaxLaboratoire de Physiques Mathématiques

When A E ∈LR（h） and B E ∈LR（K） are given, for C E∈LR（K, h） we denoteby Mc the linear relation acting on the infinite dimensional separable hilbert space h Kof the formIn this paper, we give the necessary and sufficient conditionson A and B for wh{ch Mc is upper semi-Fredholm with negative index or Weyl for some C C ∈LR（K, h）.

关键词： linear relation Fredholm and semi-Fredholm relation essential approximatepoint spectra for linear relation