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Hooshyari K.,Amirkabir University of Technology | Javanbakht M.,Amirkabir University of Technology | Naji L.,Amirkabir University of Technology | Enhessari M.,Amirkabir University of Technology | Enhessari M.,Islamic Azad University at Naragh
Journal of Membrane Science | Year: 2014

In this study, the preparation and characterization of Nafion/Fe2TiO5 nanocomposite membranes for proton exchange membrane fuel cells (PEMFCs) were investigated. Nafion/Fe2TiO5 nanocomposite membranes were prepared by dispersion of Fe2TiO5 nanoparticles within the pure commercial Nafion membranes. The composition percentage of the nanocomposite membranes and the solvent used for the dispersion of nanoparticles within the membranes were varied in order to study the effect of these variations on the proton conductivity, water uptake and also the thermal stability of the membranes. The nanocomposites membranes were characterized by using thermogravimetric analysis (TGA), scanning electron microscopy (SEM) coupled with energy dispersive X-ray (EDX) spectroscopy and impedance spectroscopy (IS). The prepared Fe2TiO5 nanocomposite membranes showed a higher water uptake, proton conductivity and thermal stability compared with the pure commercial Nafion membranes. The highest proton conductivity (226mS/cm) was observed for the membranes containing 2wt% of Fe2TiO5 nanoparticles and prepared in de-ionized water (DI) as solvent. © 2013 Elsevier B.V. Source


Khansari A.,Guilan University | Enhessari M.,Islamic Azad University at Naragh | Salavati-Niasari M.,University of Kashan
Journal of Cluster Science | Year: 2013

Nickel oxide nanoparticles have been synthesized by thermal treatment of N,N′-(bis(salicylidene)-ethylene-1,2-diamine)Nickel(II); [Ni(salen)]; as precursor which has been synthesized via two methods: [Ni(salen)] were obtained by solid state reaction in absence solvent and co-precipitation reaction in presence of propanol as solvent, respectively. Nickel oxide nanoparticles were characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy and Fourier transform infrared spectroscopy. © 2013 Springer Science+Business Media New York. Source


Roghanian E.,K. N. Toosi University of Technology | Foroughi A.,Islamic Azad University at Naragh
International Journal of Industrial Engineering Computations | Year: 2010

Data Envelopment Analysis (DEA) has been one of the most important tools on measuring the relative efficiency of different similar units such as transportation systems using terminals, airports, etc. In this study, we perform an empirical analysis on Iranian airports based on DEA methods to measure the efficiencies of various airports. One of the primary issues on many traditional DEA methods is that the data are almost always contaminated with noise. We use a DEA method which could handle the uncertainty associated with input and output data. The results of this comprehensive study show that most of the active airlines are practically inefficient and the government could significantly increase the efficiencies of the airports by setting new regulations and rules. © 2010 Growing Science Ltd. All rights reserved. Source


Khodabin M.,Islamic Azad University at Karaj | Maleknejad K.,Islamic Azad University at Karaj | Rostami M.,Islamic Azad University at Naragh | Nouri M.,Islamic Azad University at Karaj
Computers and Mathematics with Applications | Year: 2012

In this paper, we obtain stochastic operational matrix of block pulse functions on interval [0,1) to solve stochastic Volterra-Fredholm integral equations. By using block pulse functions and their stochastic operational matrix of integration, the stochastic Volterra-Fredholm integral equation can be reduced to a linear lower triangular system which can be directly solved by forward substitution. We prove that the rate of convergence is O(h). Furthermore, the results show that the approximate solutions have a good degree of accuracy. © 2012 Elsevier Ltd. All rights reserved. Source


Shabanikia A.,Amirkabir University of Technology | Javanbakht M.,Amirkabir University of Technology | Amoli H.S.,Iranian Research Organization for Science and Technology | Hooshyari K.,Amirkabir University of Technology | And 2 more authors.
Electrochimica Acta | Year: 2015

In this work, perovskite-type SrCeO3 nanoparticles were used for improving the properties of high temperature polybenzimodazole (PBI) based proton exchange membranes. Novel proton conducting membrane nanocomposites were prepared using different amounts of SrCeO3 nanopowders dispersed into by solution casting method.The nanocomposite membranes were studied by using AC impedance spectroscopy, scanning electron microscopy coupled with energy dispersive X-ray and thermo gravimetric analysis. The prepared nanocomposite membranes showed a higher acid uptake, proton conductivity and thermal stability compared with the pure PBI membranes. The highest acid uptake (190%) and proton conductivity (0.105 S/cm at 180 °C and 0% RH) were observed for phosphoric acide-dopped PBI nanocomposite membranes containing 8 wt% of SrCeO3 nanoparticles (PSC8). The PSC8 nanocomposite membranes were tested in a fuel cell and the polarization and power curves were obtained at different temperatures. The PSC8 showed 0.44 W/cm2 power density and 0.88 A/ cm2 current density in 0.5 V at 180°C. The result obtained from our studies shows the enhanced potential of the PSC8 as proton exchange membranes for high temperature proton exchange membrane fuel cells. © 2014 Elsevier Ltd. All rights reserved. Source

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