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    Using genetic algorithm in heat treatment optimization of 17-4PH stainless steel

    , Article Materials and Design ; Volume 28, Issue 7 , 2007 , Pages 2034-2039 ; 02613069 (ISSN) Zakeri, M ; Bahrami, A ; Mousavi Anijdan, S. H ; Sharif University of Technology
    Elsevier Ltd  2007
    In this investigation heat treatment optimization of 17-4PH stainless steel has been carried out by a genetic algorithm. The optimum technique of heat treatment, adaptive to 17-4PH stainless steel, was obtained from the initial data set by the use of genetic algorithms based on modeling with artificial neural network. The results strongly indicate that the presented model has the great ability for heat treatment optimization of 17-4PH stainless steel to yield the highest strength levels in different working temperatures. © 2006 Elsevier Ltd. All rights reserved  

    Origin of working temperature in H2S sensing process of SnO2-CuO thin bilayer: A theoretical macroscopic approach

    , Article Sensors and Actuators, B: Chemical ; Volume 252 , 2017 , Pages 944-950 ; 09254005 (ISSN) Boroun, Z ; Ghorbani, M ; Mohammadpour, R ; Moosavi, A ; Sharif University of Technology
    Elsevier B.V  2017
    Resistive sensors composed of SnO2 and CuO, are known to be highly efficient in detection of detrimental H2S gas in terms of sensitivity, selectivity and speed. Recently, dependency of electrical response of the sensor toward H2S gas concentration has been related to the selective mechanism (formation of CuS) by a theoretical model. Another important factor in design of gas sensors is the working temperature which so far has not been explicitly explained for H2S sensing process of SnO2-CuO system. In present study, origin of this temperature for SnO2-CuO thin bilayer based on the selective mechanism has been theoretically interpreted. For this purpose, Poisson, Laplace and continuity... 

    Numerical simulation of PV cooling by using single turn pulsating heat pipe

    , Article International Journal of Heat and Mass Transfer ; Volume 127 , 2018 , Pages 203-208 ; 00179310 (ISSN) Alizadeh, H ; Ghasempour, R ; Shafii, M. B ; Ahmadi, M. H ; Yan, W. M ; Nazari, M. A ; Sharif University of Technology
    Elsevier Ltd  2018
    Electrical efficiency of photovoltaic (PV) modules depends on their working temperature. Effective cooling is required in order to achieve higher performance. Pulsating heat pipes (PHPs) are compact heat transfer devices with high effective thermal performance due to the two-phase heat transfer mechanism. Since the lower temperature of PV modules leads to higher electricity generation and better efficiency, PHPs can be applied for PV cooling. In this work, the PV cooling by applying a single turn PHP is numerically investigated. In addition, a copper fin with the same dimensions as the PHP for cooling the PV panel is simulated to compare the performance of the PHP with a solid metal like... 

    Optimal experiment design for plasma thermal spray parameters at bending loads

    , Article International Journal of Surface Science and Engineering ; Volume 6, Issue 1-2 , 2012 , Pages 3-14 ; 1749785X (ISSN) Azadi, M ; Moridi, A ; Farrahi, G. H ; Sharif University of Technology
    Ceramic thermal barrier coatings are applied on gas turbines and diesel engine components to protect metals from heat and this enhances the service lifetime by means of a reduction in working temperature. In the present paper, optimisation of plasma thermal spray parameters, including feed rate and nozzle distance from the specimen surface is performed by using the design of experiment method. Due to factorial approach, by considering two parameters with three variation levels, nine experiments of bending test are needed. The base material is cast aluminium alloy, A356.0-T7. The coating layers consist of a bond coat, Ni-Cr-Al-Y with a thickness of 150 μm and a top coat, ZrO2-8wt%Y2O3 with a... 

    Adiabatic shear banding in an Al-Mg-Si alloy processed by equal channel angular pressing

    , Article Materials Science Forum, 2 August 2010 through 6 August 2010, Cairns, QLD ; Volume 654-656 , 2010 , Pages 1014-1017 ; 02555476 (ISSN) ; 0878492550 (ISBN) Vaseghi, M ; Taheri, A. K ; Yoo, J. H ; Joo, S. H ; Kim, H. S ; Sharif University of Technology
    Equal channel angular pressing is an outstanding method for imposing large plastic deformation to metallic materials without any decreasing in cross section area of as processed samples. In this paper, the effect of working temperature, ram speed and the number of passes on the formation of adiabatic shear bands in Al6061 during equal channel angular pressing was investigated. Billets of the alloy were processed up to four passes via route BC from room temperature to 200°C with two ram speeds using a die that imparts an effective strain of ∼1.1 per pass. The results have demonstrated that the onset of the adiabatic shear banding in this alloy strongly depends on the ram speed: more... 

    Pd doped WO3 films prepared by sol-gel process for hydrogen sensing

    , Article International Journal of Hydrogen Energy ; Volume 35, Issue 2 , 2010 , Pages 854-860 ; 03603199 (ISSN) Fardindoost, S ; Iraji zad, A ; Rahimi, F ; Ghasempour, R ; Sharif University of Technology
    The sol gel method was employed to prepare peroxopolytungstic acid (P-PTA). Palladium chloride salt was dissolved in the sol with different Pd:W molar ratios and coated on Al2O3 substrates by spin coating method. XRD and XPS techniques were used to analyze the crystal structure and chemical composition of the films before and after heat treatment at 500 °C. We observed that Pd can modify the growth kinetic of tungsten trioxide nanoparticles by reducing the crystallite size and as a result can improve hydrogen sensitivity. Resistance-sensing measurements indicated sensitivity of about 2.5 × 104 at room temperature in hydrogen concentration of 0.1% in air. Considering all sensing parameters,... 

    Evaluation of desiccant wheel and prime mover as combined cooling, heating, and power system

    , Article International Journal of Green Energy ; Volume 16, Issue 3 , 2019 , Pages 256-268 ; 15435075 (ISSN) Mohammadian Korouyeh, M ; Saidi, M. H ; Najafi, M ; Aghanajafi, C ; Sharif University of Technology
    Taylor and Francis Inc  2019
    In this research heating, cooling and electrical demands of a residential tower are evaluated for Iran various weather conditions. For this purpose, several cities are selected as the representative of the specific weather conditions. To meet the cooling demand, desiccant cooling system plus alternative systems are applied. To analyze desiccant wheel, outlet humidity and temperature have been modeled. Also, the effect of rotational speed and regeneration temperature on entropy generation of the desiccant wheel has been studied based on the obtained results. It is deduced that the entropy generation may be increased by increasing the regeneration temperature and the rotational speed. To... 

    Numerical analysis of photovoltaic solar panel cooling by a flat plate closed-loop pulsating heat pipe

    , Article Solar Energy ; Volume 206 , 2020 , Pages 455-463 Alizadeh, H ; Alhuyi Nazari, M ; Ghasempour, R ; Shafii, M. B ; Akbarzadeh, A. A ; Sharif University of Technology
    Elsevier Ltd  2020
    Photovoltaic (PV) panels provide a suitable way for the direct conversion of solar energy into electricity. The electrical output and efficiency of PV modules are dependent on working temperature. The present study contributes to investigate the efficiency of utilizing a flat plate closed-loop pulsating heat pipe (CLPHP) to cool down a PV panel in both thermal and economic aspects. Accordingly, a numerical investigation is employed to obtain the surface temperature and electrical gain of the PV panel through four scenarios, including natural cooling without additional equipment, CLPHP-based passive cooling, CLPHP-based active cooling, and a conventional flat plate cooling methods. The...