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- 저자 : Motevalli, Mahnaz (검색결과 5 건)
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NEW APPROACH FOR PERFORMING FAILURE ANALYSIS OF FUEL CELL-POWERED VEHICLES
V. MOTEVALLI1,M.-S. MOHD 한국자동차공학회 2009 International journal of automotive technology Vol.10 No.6
Safety of hybrid-electric and fuel cell vehicles is a critical aspect of these new technologies, since any accident exposing occupants of such vehicles to unconventional hazards may result in significant setbacks to successful market penetration. Fuel cell and hybrid-electric drive systems are complex, and it is essential to perform a thorough analysis to determine critical failure conditions. There are several safety concerns for routine operation of such systems, particularly for hydrogen-fueled vehicles. A modified Failure Modes and Effect Analysis (FMEA) has been developed, along with a Criticality Analysis (CrA), to identify potentially hazardous conditions for crash and non-crash situations. A mathematical model of fuel cell operation has been developed and used here in conjunction with the FMEA. Component failures during the event modes are simulated using vehicle models developed with Matlab Simulink tools. Six simulation models were created using the software. In addition, a preliminary finite element model of a fuel cell vehicle, using a Ford Taurus (91’) model year sedan, has been developed and implemented. This finite element model is used as a demonstration of the crash simulation of the vehicle. Safety of hybrid-electric and fuel cell vehicles is a critical aspect of these new technologies, since any accident exposing occupants of such vehicles to unconventional hazards may result in significant setbacks to successful market penetration. Fuel cell and hybrid-electric drive systems are complex, and it is essential to perform a thorough analysis to determine critical failure conditions. There are several safety concerns for routine operation of such systems, particularly for hydrogen-fueled vehicles. A modified Failure Modes and Effect Analysis (FMEA) has been developed, along with a Criticality Analysis (CrA), to identify potentially hazardous conditions for crash and non-crash situations. A mathematical model of fuel cell operation has been developed and used here in conjunction with the FMEA. Component failures during the event modes are simulated using vehicle models developed with Matlab Simulink tools. Six simulation models were created using the software. In addition, a preliminary finite element model of a fuel cell vehicle, using a Ford Taurus (91’) model year sedan, has been developed and implemented. This finite element model is used as a demonstration of the crash simulation of the vehicle.
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S. Ghafoori,M. Motevalli,M.G. Nejad,F. Shakeri,D. D. Ganji,M. Jalaal 한국물리학회 2011 Current Applied Physics Vol.11 No.4
In this study, a nonlinear oscillation equation is solved using a series-based analytical method called differential transformation method (DTM). The concept of differential transformation is briefly introduced,and its application for a nonlinear oscillator is studied. The results obtained employing DTMare compared with those achieved by using two other series-based analytical techniques named variation iteration method (VIM) and homotopy perturbation method (HPM) and also an accurate numerical solution to verify the accuracy of the proposed method. As an important result, it is depicted that the DTM results are more accurate in comparison with those obtained by HPM and VIM. After this verification, we analyze the effects of some physical applicable parameters to show the efficiency of DTM for this type of problems. It is shown that inmost cases,DTM is accurate enough; nevertheless some modifications should be applied to enhance the abilities of this technique.
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Rostami S. Hesami,Motevalli S. M.,Fadaei F.,Mohammadi S. 한국물리학회 2020 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.77 No.12
Zero-dimensional global particle balance modeling was applied to the JET-ILW tokamak to investigate the particle balance in the main plasma and wall inventory, including the wall recycling effect, co-deposition, and sputtered particles. In this model, we used the fueling rate, based on the experimental work and vacuum pumping of the JET-ILW. Our modeling results were then compared with experimental data from the JET-ILW tokamak. A qualitative agreement was observed between the model results and the experimental data. In addition, this model could be a promising for studing the particle behavior in ITER-like reactors.
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Dutta, Sudhir K.,Agrawal, Kireet,Girotra, Mohit,Fleisher, A. Steven,Motevalli, Mahnaz,Mah'moud, Mitchell A.,Nair, Padmanabhan P. Asian Pacific Journal of Cancer Prevention 2012 Asian Pacific journal of cancer prevention Vol.13 No.12
Introduction: Epidemiological studies suggest a protective role for ${\beta}$-carotene with several malignancies. Esophageal adenocarcinoma frequently arises from Barrett's esophagus (BE). We postulated that ${\beta}$-carotene therapy maybe protective in BE. Materials and Method: We conducted a prospective study in which 25 mg of ${\beta}$-carotene was administered daily for six-months to six patients. Each patient underwent upper endoscopy before and after therapy and multiple mucosal biopsies were obtained. Additionally, patients completed a gastroesophageal reflux disease (GERD) symptoms questionnaire before and after therapy and severity score was calculated. To study the effect of ${\beta}$-carotene at molecular level, tissue extracts of the esophageal mucosal biopsy were subjected to assessment of heat-shock protein 70 (HSP70). Results: A significant (p<0.05) reduction in mean GERD symptoms severity score from $7.0{\pm}2.4$ to $2.7{\pm}1.7$ following ${\beta}$-carotene therapy was noted. Measurement of Barrett's segment also revealed a significant reduction in mean length after therapy. In fact, two patients had complete disappearance of intestinal metaplasia. Furthermore, marked enhancement of HSP70 expression was demonstrated in biopsy specimens from Barrett's epithelium in four cases that were tested. Conclusions: Long-term ${\beta}$-carotene therapy realizes amelioration of GERD symptoms along with restitution of the histological and molecular changes in esophageal mucosa of patients with BE, associated with concurrent increase in mucosal HSP70 expression.
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