Islamic Azad University at Central Tehran
Tehran, Iran

The Islamic Azad University Central Tehran Branch is a university located in Tehran, Iran. The university is the oldest and the largest branch of Islamic Azad University established in 1982, originally as "Islamic Azad University of Tehran".The university campuses rest on 297,904 m² of various districts of Tehran.It offers approximately 180 undergraduate and graduate degree programs in a wide range of disciplines. Wikipedia.

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Tahery R.,Islamic Azad University at Central Tehran
Journal of Solution Chemistry | Year: 2017

Surface tensions (σ) for the binary mixtures chlorocyclohexane + tetrahydrofuran and chlorobenzene + tetrahydrofuran at 298.15 K and 1.013 bar have been determined as a function of the mole fraction. In order to analyze the surface tension behavior, the extended Langmuir (EL) and Shereshefsky models were used and parameters of the models were obtained for these mixtures. The standard Gibbs energy of adsorption ((Formula presented.)) was calculated using both models. The Gibbs energy change for replacing 1 mol of solute with 1 mol of solvent in the surface region (∆GS), and the excess number of molecular layers of solute in the surface region, were calculated using Shereshefsky’s model. The magnitudes of ∆GS and (Formula presented.) are discussed in terms of the nature and type of intermolecular interactions in the binary mixtures. © 2017 Springer Science+Business Media New York

Toloo M.,Islamic Azad University at Central Tehran | Nalchigar S.,University of Tehran
Expert Systems with Applications | Year: 2011

The success of a supply chain is highly dependent on selection of best suppliers. These decisions are an important component of production and logistics management for many firms. Little attention is given in the literature to the simultaneous consideration of cardinal and ordinal data in supplier selection process. This paper proposes a new integrated data envelopment analysis (DEA) model which is able to identify most efficient supplier in presence of both cardinal and ordinal data. Then, utilizing this model, an innovative method for prioritizing suppliers by considering multiple criteria is proposed. As an advantage, our method identifies best supplier by solving only one mixed integer linear programming (MILP). Applicability of proposed method is indicated by using data set includes specifications of 18 suppliers. © 2011 Elsevier Ltd. All rights reserved.

Sabbaghi-Nadooshan R.,Islamic Azad University at Central Tehran
Performance Evaluation | Year: 2013

This paper proposes and evaluates a shuffle-exchange as an efficient alternative to the popular mesh topology for Network-on-Chips (NoCs). Although the proposed topology imposes the cost equal to that of the mesh topology, the proposed topology (1) provides lower diameter for NoC, (2) offers better performance under uniform, hotspot, and matrix-transpose traffic patterns and (3) consumes lower energy for packet delivery. To speed up the evaluation process of the proposed topology, an analytical performance model is proposed in the paper to predict the performance of NoCs. The model uses a network of M/G/1 queues to consider channels of the NoC. In this way, the model accurately estimates the average message latency which is a widely used representative for the network performance. Results obtained from the analytical model are in good agreement with those of simulations for a wide range of working conditions (e.g. various network sizes, different message lengths, and different traffic patterns). The proposed analytical model provides a minimum of 400% speed-up in the evaluation process of the proposed topology. © 2013 Elsevier B.V. All rights reserved.

Fayyazbakhsh A.,Islamic Azad University at Central Tehran | Pirouzfar V.,Islamic Azad University at Central Tehran
Fuel | Year: 2016

In this study, the effect of ethanol-diesel blends with different types of additives on performance and exhaust emission is experimentally investigated through experimental modeling and optimization methods. Experiments are performed on a turbocharged common rail direct injection (CRDI) engine. The modeling is used to optimize the emission, engine performance, and physico-chemical properties by implementing factorial design considering four main parameters, namely, choice of oxygenate and nitrogenate such as Nitroethane (NE), Nitromethane (NM) and 2-methoxy ethyl ether (MXEE) and metal additives such as Manganese (MN) and Cerium (CE), engine speed (2200 and 1500 rpm) and load (370, 275, 180 and 20 N m). Findings by modeling show that the quadric and cubic terms of these four variables had significant effects. The obtained results prove that using the diesel-ethanol-(NE + MN) is better to decrease soot emissions and increase cetane number. The properties under study were cetane number and viscosity experiment. The emissions decrease with increasing the engine speed. The effect of blending (MXEE + CE) with diesel-ethanol on improvement of the engine performance is higher than other additives. The optimal conditions are found to be the NE, MN, engine speed and load of 1500 rpm and 168 N m, respectively. Under these conditions, the model estimated the soot content, formation of NOx and CO2, brake specific fuel consumption (BSFC) and powers of 27.6, 441.3, 28.1 ppm, 224.2 g/kW h and 26.5 kw, respectively. The modeling techniques and developed models can be employed as a useful tool for design and optimization of appropriate ethanol-diesel fuels with effective performance for various industrial applications. © 2015 Elsevier Ltd. All rights reserved.

Toloo M.,Islamic Azad University at Central Tehran
Computers and Mathematics with Applications | Year: 2012

In conventional data envelopment analysis (DEA) models, a performance measure whether as an input or output usually has to be known. Nevertheless, in some cases, the type of a performance measure is not clear and some models are introduced to accommodate such flexible measures. In this paper, it is shown that alternative optimal solutions of these models has to be considered to deal with the flexible measures, otherwise incorrect results might occur. Practically, the efficiency scores of a DMU could be equal when the flexible measure is considered either as input or output. These cases are introduced and referred as share cases in this study specifically. It is duplicated that share cases must not be taken into account for classifying inputs and outputs. A new mixed integer linear programming (MILP) model is proposed to overcome the problem of not considering the alternative optimal solutions of classifier models. Finally, the applicability of the proposed model is illustrated by a real data set. © 2012 Published by Elsevier Ltd.

Amirfakhrian M.,Islamic Azad University at Central Tehran
Soft Computing | Year: 2012

We introduce a fuzzy norm on a subset of all fuzzy numbers by a distance and we use it to analyze an approximate solution of a system of fuzzy linear equations. By a theorem we give two error bounds for error of an approximate solution of a system of fuzzy linear equations. © 2012 Springer-Verlag.

Tanhayi M.R.,Islamic Azad University at Central Tehran
Physical Review D - Particles, Fields, Gravitation and Cosmology | Year: 2014

Recently, in the context of dS/CFT correspondence, quasinormal modes have been put forward to address certain features of this conjecture. In particular, it is argued that the dual states of quasinormal modes are in fact the states of CFT3 which are created by operator insertions. For a scalar field in dS4, quasinormal modes which are singular on the past horizon of the south pole and decay exponentially towards the future have been considered in [G.S. Ng and A. Strominger, Classical Quantum Gravity 30, 104002 (2013); D.L. Jafferis et al., arXiv:1305.5523]; these modes lie in two complex highest-weight representations of the dS4 isometry group. In this work, we present a simple group representation analysis of these modes so that the de Sitter invariance is obviously manifest. By making use of the so-called plane wave method, we will show that the quasinormal modes correspond to one class of the unitary irreducible representation of the de Sitter group. This consideration could be generalized straightforwardly for higher-spin fields and higher dimensions; in particular, we will study the quasinormal modes for gauge and spinor fields, and, in the case of a scalar field, the generalization to higher dimensions is also obtained. © 2014 American Physical Society.

Eshghi M.,Islamic Azad University at Central Tehran | Mehraban H.,Semnan University
Few-Body Systems | Year: 2012

In this research, we have been obtained the Dirac equation for q-parameter modified Pöschl-Teller potential including a Coulomb-like tensor interaction with arbitrary spin-orbit coupling quantum number by choosing a position-dependent mass. The energy eigenvalues equation and the corresponding unnormalized wave functions have been obtained. The Nikiforov-Uvarov method has been used in the calculations. © 2011 Springer-Verlag.

Khademi M.,Islamic Azad University at Central Tehran
International Journal of Thermal Sciences | Year: 2016

The present work examines the effect of thermal radiation from the solid phase on the fluid and solid temperature inside a porous medium by studying forced convection heat transfer process within a parallel plates porous micro-channels. The Darcy-Brinkman model is considered in the momentum equation and two energy equations are used to evaluate solid and fluid temperatures. Results are reported in terms of average Nusselt numbers and dimensionless temperature profiles as a function of Biot number (Bi), effective thermal conductive ratio (k), Darcy number (Da), accommodation coefficients (tangential momentum and thermal) and Knudsen number. © 2015 Elsevier Masson SAS.

Fathi M.,Islamic Azad University at Central Tehran
Chinese Physics C | Year: 2013

In this article, we assume that a cold charged perfect fluid is constructing a spherical relativistic star. Our purpose is the investigation of the dynamical properties of its exterior geometry, through simulating the geodesic motion of a charged test-particle, while moving on the star. © 2013 Chinese Physical Society and the Institute of High Energy Physics of the Chinese Academy of Sciences and the Institute of Modern Physics of the Chinese Academy of Sciences and IOP Publishing Ltd.

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