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Eşfahān, Iran

Hassanzadeh M.,Tarbiat Modares University | Navidi F.,Iranian Space Agency
Electronic Library | Year: 2010

Purpose - This paper aims to provide knowledge about methods used to evaluate the accessibility of Iranian web sites through a real research environment. Design/methodology/approach - The main theoretical base of this article is that almost all research conducted to evaluate the accessibility of web sites has used only one of three methods (namely manual, automatic and users' experiences). However, it seems that using a combination of these three methods is actually necessary. Consequently, taking a critical approach this article examines 18 Iranian ministerial web sites using the three methods. Findings - Findings in both documents and evaluative studies show that each of the methods has deficits and it is necessary to employ a combination of the methods in order to conduct a reliable accessibility assessment. The different rankings of ministerial web sites in various evaluations have confirmed this view. Originality/value - Identifying the advantages and disadvantages of the three methods and employing them in real research environments to assess the accessibility of ministerial web sites has been a useful exercise. The work can not only be a starting point for further discussions on the reliability of accessibility evaluation methods, but can also be applied to other types of web site. Copyright © 2010 Emerald Group Publishing Limited. All rights reserved. Source

Raeisy B.,Shiraz University | Raeisy B.,Iranian Space Agency | Safavi A.A.,Shiraz University | Khayatian A.R.,Shiraz University
Iranian Journal of Fuzzy Systems | Year: 2012

In this study, the roll, yaw and depth fuzzy control of an Autonomous Underwater Vehicle (AUV) are addressed. Yaw and roll angles are regulated only using their errors and rates, but due to the complexity of depth dynamic channel, additional pitch rate quantity is used to improve the depth loop performance. The discussed AUV has four flaps at the rear of the vehicle as actuators. Two rule bases and membership functions based on Mamdani type and Sugeno type fuzzy rule have been chosen in each loop. By invoking the normalized steepest descent optimization method, the optimum values for the membership function parameters are found. Though the AUV is a highly nonlinear system, the simulation of the designed fuzzy logic control system based on the equations of motion shows desirable behavior of the AUV specially when the parameters of the fuzzy membership functions are optimized. Source

Taherian R.,Shahrood University | Nasr M.,Iranian Space Agency
International Journal of Energy Research | Year: 2014

In this research, a novel woven nanocomposite was manufactured as bipolar plate of proton exchange membrane fuel cell. The developed composite includes 40wt.% phenolic resin as binder and 45wt.%graphite, 10wt.% nanosheet expanded graphite, and 5wt.% carbon fiber as fillers, as well as a woven carbon fiber cloth in the middle. A single-cell assembly was manufactured by using the developed composite bipolar plate. Subsequently, the performance and power density curves were obtained from the developed cell. The results showed that the cell performs the maximum power density as high as 812mW/cm2 and current density 900mA/cm2 at 0.6V that are better than the cells prepared by the metallic and some commercial bipolar plates. In this research, in order to achieve the best cell performance, some of the operation factors containing the cell body temperature, oxygen inlet temperature, and hydrogen inlet temperature, as well as back pressure were optimized, and the results were properly discussed. Last, in order to select a suitable material for bipolar plate, using simple additive weighting method approach, a material selection was performed upon several alternatives including composite, graphite, SS316L, SS304, Hastelloy, Al, and Ti, which are currently being used for bipolar plate. The result of material selection specified that Al/CrN is the most suitable candidate to be used for bipolar plates. © 2013 John Wiley & Sons, Ltd. Source

Niknam T.,Shiraz University of Technology | Khooban M.H.,Shiraz University of Technology | Khooban M.H.,Iranian Space Agency
IET Science, Measurement and Technology | Year: 2013

This study deals with the problem of controlling class of uncertain non-linear systems in the presence of external disturbances. To achieve this goal, a robust fuzzy sliding mode (RFSM) controller is introduced. First known dynamics of the system are eliminated through feedback linearisation and then fuzzy sliding mode controller is designed using Takagi-Sugeno (TS) method, based on the Lyapunov method which is capable of handling uncertainties. There is no sign of the undesired chattering phenomenon in the proposed method. The globally asymptotic stability of the closed-loop system is mathematically proved. In order to evaluate the performance of the proposed controller, the results are compared with those obtained by optimal H8 adaptive proportional integral derivative controller and an optimal Type-2 fuzzy proportional integral derivative, which are the latest researches in the problem in hand. Simulation results show the effectiveness of the RFSM controller. © The Institution of Engineering and Technology 2013. Source

Ajabshirizadeh A.,Islamic Azad University at Tabriz | Nadiri Niri B.,Research Institute for Astronomy and Astrophysics of Maragha RIAAM | Nadiri Niri B.,Iranian Space Agency
Iranian Journal of Science and Technology, Transaction A: Science | Year: 2015

The energy loss of a 3-dimensional harmonic oscillator due to the quadrupole radiation in quadratic f (R) gravity is calculated. © 2015, Shiraz University. All rights reserved. Source

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