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Improved Semi-empirical Model of Proton Exchange Membrane Fuel Cell Incorporating Fault Diagnostic Feature

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Journal of Modern Power Systems and Clean Energy 2021年第6期9卷 1566-1573页

作者： saad Saleem Khan Hussain Shareef Ahmad Asrul Ibrahim Department of Electrical Engineering College of EngineeringUnited Arab Emirates University IEEE Department of Electrical Electronic and Systems EngineeringFaculty of Engineering and Built EnvironmentUniversiti Kebangsaan Malaysia

The membrane water content of the proton exchange membrane fuel cell(PEMFC)is the most important feature required for water management of the PEMFC *** improper management of water in the fuel cell may lead to system *** various faults,flooding and drying faults are the most frequent in the PEMFC *** paper presents a new dynamic semi-empirical model which requires only the load current and temperature of the PEMFC system as the input while providing output voltage and membrane water content as its major *** other PEMFC systems,the proposed dynamic model calculates the internal partial pressure of oxygen and hydrogen rather than using special internal ***,the membrane water content and internal resistances of PEMFC are modelled by incorporating the load current condition and temperature of the PEMFC *** model parameters have been extracted by using a quantum lightening search algorithm as an optimization technique,and the performance is validated with experimental data obtained from the NEXA 1.2 k W PEMFC *** further demonstrate the capability of the model in fault detection,the variation in membrane water content has been studied via the *** proposed model could be efficiently used in prognostic and diagnosis systems of PEMFC fault.

关键词： Proton exchange membrane fuel cell(PEMFC)fault membrane water content modelling optimization quan-tum lightening search algorithm

Evolution of care in cirrhosis: Preventing hepatic decompensation through pharmacotherapy

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World Journal of Gastroenterology 2023年第1期29卷 61-74页

作者： Seohyuk Lee saad Saffo Department of Medicine Section of Digestive DiseasesYale School of MedicineNew HavenCT 06520-8019United States

Cirrhosis is a leading cause of morbidity and mortality,impacting more than 120 million people *** geographic differences exist,etiologic factors such as alcohol use disorder,chronic viral hepatitis infections,and non-alcoholic fatty liver disease are prevalent in nearly every ***,significant effort has been devoted to modifying these risks to prevent disease ***,more than 11%of patients with compensated cirrhosis experience hepatic decompensation each *** transition signifies the most important prognostic factor in the natural history of the disease,corresponding to a decline in median survival to below 2 *** the past decade,the need for pharmacotherapies aimed at reducing the risk for hepatic decompensation has been emphasized,and non-selective beta-blockers have emerged as the most effective option to ***,a critical therapeutic gap still exists,and additional therapies have been proposed,including statins,rifaximin,and sodium-glucose cotransporter-2 *** on the results of innovative retrospective analyses and small-scale prospective trials,these pharmacotherapies represent promising options,but further studies,including randomized controlled trials,are necessary before they can be incorporated into clinical *** report highlights the potential impact of these agents and others in preventing hepatic decompensation and discusses how this paradigm shift may pave the way for guideline-directed medical therapy in cirrhosis.

关键词： Cirrhosis Hepatic decompensation Beta-blockers Statins Sodium-glucose cotransporter-2 inhibitors Rifaximin

Routine rectal retroflexion during colonoscopy has a low yield for neoplasia

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World Journal of Gastroenterology 2008年第42期14卷 6503-6505页

作者： Abdo saad Douglas Kevin Rex Department of Medicine Division of Gastroenterology/Hepatology Indiana University School of Medicine Indianapolis IN 46202 United States

AIM： To investigate the value of retroflexion in detecting neoplasia in the distal rectum. METHODS： This was a prospective observational study performed in an academic endoscopy unit. Consecutive patients undergoing colonoscopy had careful forward viewing of the distal rectum by retroflexion. Of 1502 procedures, 1076 （72%） procedures were performed with a 140^o angle of view colonoscope and 426 （28%） were performed with a 170^o angle of view colonoscope. The outcome measurement was the yield of neoplasia in the distal rectum detected by forward viewing vs retroflexion. RESULTS： A total of 1502 patients, including 767 （51%） females and 735 （49%） males, with mean age of 58.8 ± 12.5 years were enrolled. Retroflexion was successful in 1411 （93.9%） patients, unsuccessful or not performed because the rectum appeared narrow in 91 （6.1%）. Forty patients had a polyp detected in the distal rectal mucosa. Thirty-three were visible in both the forward and retroflexed view （25 hyperplastic, 8 adenomatous）. Seven polyps were visualized only by retroflexion （6 hyperplastic sessile polyps, one 4 mm sessile tubular adenoma）. There was no significant difference in information added by retroflexion with 140^o vs 170^o angle of view instrument. CONCLUSION： To our knowledge, this is the largest reported evaluation of retroflexion in the rectum. Routine rectal retroflexion did not detect clinically important neoplasia after a careful forward examination of the rectum to the dentate line. Since retroflexion has risks and may cause discomfort, theuse of routine retroflexion should be at the discretion of the endoscopist.

关键词： Colonoscopy Colorectal polyps Retroflexion Rectum

Hydrogen Detection With FBG Sensor Technology for Disaster Prevention

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Photonic Sensors 2013年第3期3卷 214-223页

作者： Said saad Lotfi HASSINE Group of Electronics and Quantum Physics Laboratory of Advanced Materials and Quantum Phenomena Faculty of Sciences of Tunis 2092 Tunisia National Institute of Applied Sciences and Technology University of Carthage North Urban Center of Tunis-B.P.676 Cedex Tunis-1080 Tunisia

Three fiber Bragg grating （FBG） sensors systems for hydrogen detection are presented using the classic Pd （palladium） coating technique （500nm） as the hydrogen sensitive film and titanium （Ti） as the adhesive layer with the etched cladding. These systems are compared and used for disaster environment prevention in hydrogen leakage environment where higher values than the normal are presented which increase the risk of explosion. With these systems, 0. 1% - 4% of the hydrogen volume concentration range in the volume ratio was detected and monitored experimentally in the test room with the very sensitive and stable value which reached 60pm/1% HE. In addition, a fast response time, about 6 s, was obtained with an advanced sensor.

关键词： Fiber Bragg gratin (FBG) hydrogen detection sensor disaster environment prevention Pd coating technique

Oilfield produced water treatment in internal-loop airlift reactor using electrocoagulation/flotation technique

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Chinese Journal of Chemical Engineering 2018年第4期26卷 879-885页

作者： saad H.Ammar Ahmed S.Akbar Department of Chemical engineering AL-Nahrain University

Oilfield produced water is large quantities of salty water trapped in underground formations and subsisted under high temperatures and pressures that are brought to the surface along with oil during production. Produced water(PW) contains a lot of pollutants such as hydrocarbons and metals, this water must be treated before disposal. Therefore, different techniques are being used to treat produced water. Electrocoagulation is an efficient treatment technique involving the dissolution of anodes and formation of electro-coagulants, while the simultaneous generation of H_2 bubbles at the cathode leads to the pollutant removal by flotation. Electrocoagulation(EC)method is one of the most promising and widely used processes to treat oilfield produced water. In the present work, a conventional internal-loop(draught tube) airlift reactor was utilized as electrocoagulation/flotation cell for PW treatment by inserting two aluminum electrodes in the riser section of the airlift reactor. The EC airlift reactor was operated in a batch mode for the liquid phase. Different experimental parameters were studied on the oil and turbidity removal efficiencies such as current density, initial pH, electrocoagulation time, and air *** experimental results showed that mixing of the oil droplets in the PW was accomplished using only the liquid recirculation resulted by H_2 microbubbles generated by EC process which enhanced the oil removal. The experimental results further showed that the EC time required achieving ≥ 90% oil removal efficiency decreases from 46 to 15 min when operating current density increases from 6.8 to 45.5 mA·cm^(-2). This reactor type was found to be highly efficient and less energy consuming compared to conventional existing electrochemical cells which used mechanical agitation.

关键词： Produced water Wastewater treatment Electrocoagulation/flotation Internal loop Airlift reactor

Geotectonic significance of the Neoproterozoic ophiolitic metagabbros of Muiswirab area,South Eastern Desert,Egypt:constraints from their mineralogical and geochemical characteristics

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Acta Geochimica 2020年第6期39卷 887-910页

作者： Moustafa M.Mogahed Wlaa Mahmoud saad Geology Department Faculty of ScienceBenha University-EgyptP.O.Box 13518BenhaEgypt

Petrological and geochemical studies of Neo-proterozoic metagabbros were carried out in the Muiswirab area,South Eastern Desert of *** Muiswirab area comprises of ophiolitic metagabbroic rocks(MOM),which are tectonically thrusted over a thick pile of metavolcanic rocks and intruded by syn-and post-tectonic granitoid *** whole-rock geochemical variations coupled with chemical compositions of mineral constituents are used to attain the genesis and tectonic evolution of the studied *** geothermobarometric investiga-tion of the analyzed amphiboles from(MOM)revealed that these metagabbros underwent regional metamorphism under lower to upper greenschist facies(biotite zone)conditions(at a temperature of 450 to 500℃and pressure of 1-3 kbar).Geochemically,the metagabbros(MOM)show tholeiitic affinity and cxhibiting both arc-and MORB-like characters as evidenced by their clinopyrox-ene compositions and the Ti/V ratios(11.84-31.65),which considered as prominent features of forearc tectonic *** geochemical features suggest a probable fractionation of olivine±clinopyroxene±plagioclase as well as insignificant crustal *** parental magma of the investigated MOM rocks seems to be developed in a sub-arc mantle wedge setting due to the enrichments of LILE(e.g..Rb,Ba,Sr,Pb)over HFSE(e.g,Ti,Nb,Y,Zr,Hf,Ta).The studied MOM rocks have lower values of Nb/U relative to MORB and OIB indicating that their geochemical variation produced due to the enrichment of a lithosphere mantle by OIB like *** ratios of Zn/Fet,La/Sm,Sm/Yb,Th/Yb and Nb/Yb indicate that the MOM rocks represent a fragment of oceanic crust originated at a supra-subduction zone environment and their parental magma developed by 5-30%partial melting of a spinel lherzolite mantle rather than pyroxenite in an island arc setting and conformable with most of the Egyptian ophiolitic metagabbros.

关键词： Egypt Eastern Desert Muiswirab area Ophiolitic metagabbros N-MORB Arc tholeiites Foreare tectonic regime Volcanic-arc setting

An Adaptive Full Order Sliding Mode Controller for Mismatched Uncertain Systems

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International Journal of Automation and computing 2017年第2期14卷 191-201页

作者： Sanjoy Mondal Jawhar Ghommam Maarouf saad Department of Electrical Engineering Ecole de technologie superieure Montreal Canada-H3C1K3 Canada

In this paper, an adaptive full order sliding mode （FOSM） controller is proposed for strict feedback nonlinear systems with mismatched uncertainties. The design objective of the controller is to track a specified trajectory in presence of significant mismatched uncertainties. In the first step the dynamic model for the first state is considered by the desired tracking signal. After the first step the desired dynamic model for each state is defined by the previous one. An adaptive tuning law is developed for the FOSM controller to deal with the bounded system uncertainty. The major advantages offered by this adaptive FOSM controller are that advanced knowledge about the upper bound of the system uncertainties is not a necessary requirement and the proposed method is an effective solution for the chattering elimination from the control signal. The controller is designed considering the full-order sliding surface. System robustness and the stability of the controller are proved by using the Lyapunov technique. A systematic adaptive step by step design method using the full order sliding surface for mismatched nonlinear systems is presented, Simulation results validate the effectiveness of the proposed control law.

关键词： Full order sliding mode adaptive sliding mode finite time convergence reference tracking mismatched uncertainty.

Nanoarchitectured LiMn_2O_4/Graphene/ZnO Composites as Electrodes for Lithium Ion Batteries

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Journal of Materials Science & Technology 2014年第5期30卷 427-433页

作者： saad Aziz Jianqing Zhao Carrington Cain Ying Wang Department of Mechanical & Industrial Engineering Louisiana State University

LiMn2O4 nanoparticles are facilely synthesized using a sol-gel processing method. Graphene is added to LiMn2O4 electrode aiming at increasing specific capacity and improving rate capability. In order to further improve cycling stability of LiMn2O4/graphene electrode, atomic layer deposition （ALD） is used to deposit ultrathin ZnO coating composed of six ZnO ALD layers and modify the surface of either LiMn2O4/graphene electrode or individual LiMn2O4 particles to form nanoarchitectured LiMn2O4/graphene/ZnO electrodes. Both ZnO-ALD-modified LiMn2O4/graphene electrodes demonstrate enhanced cycling performance at 1C, retaining the final discharge capacity above 122 mA h g 1 after 100 electrochemical cycles, which is higher than 115 mA h g-1 of pristine LiMn2O4/graphene electrode and 109 mA h g-1 of bare LiMn2O4 electrode. The improved electrochemical performance of nanoarchitectured LiMn2O4/graphene/ZnO electrodes can be attributed to the cooperative effects from high electronic conductivity of graphene sheets to facilitate electron transportation and effective protection of ZnO ALD coating to restrict Mn dissolution and electrolyte decomposition.

关键词： LiMn2O4/graphene nanocomposite Atomic layer deposition Cathode material Lithium ion battery

A Methodology to Reduce Thermal Gradients Due to the Exothermic Reactions in Resin Transfer Molding Applications

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Fluid Dynamics & Materials Processing 2023年第1期19卷 95-103页

作者： Aouatif saad Mohammed EL Ganaoui Advanced Systems Engineering Laboratory National School of Applied SciencesIbn Tofail UniversityKenitra242Morocco LERMAB/IUT Longwy Institut CarnotNancy186France

Resin transfer molding(RTM)is among the most used manufacturing processes for composite ***,the resin cure is initiated by heat supply to the *** supplementary heat generated during the reaction can cause thermal gradients in the composite,potentially leading to undesired residual stresses which can cause shrinkage and *** the present numerical study of these processes,a one-dimensional finite difference method is used to predict the temperature evolution and the degree of cure in the course of the resin polymerization;the effect of some parameters on the thermal gradient is then analyzed,namely:the fiber nature,the use of multiple layers of reinforcement with different thermal properties and also the temperature cycle *** validity of this numerical model is tested by comparison with experimental and numerical results in the existing literature.

关键词： Cure RTM finite difference method thermal gradients residual stresses