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Development of Finite Volume Method for Coupled Radiative, Convective, and Conductive Heat Transfer in Participating Media
, Ph.D. Dissertation Sharif University of Technology ; Darbandi, Masoud (Supervisor)
Abstract
Numerical simulations of participating media need careful solution of the radiation transfer equation (RTE) along the fluid flow governing equations. Evidently, the accuracy of achieved solutions highly depends on the accuracy of radiation transfer calculations. Despite numerous efforts performed in the previous researches, the RTE calculation still faces with several challenges from both accuracy and computational cost perspectives. The main objective of this research is to present new contributions in overcoming such challenges. So, a finite-volume (FV) solver is suitably developed to solve the RTE numerically. This extended solver is then coupled with an existing FV flow solver. The...
Electrophoretic Deposition of Graphene Oxide Nanocomposite on Magnesium substrate Modified by PEO
, M.Sc. Thesis Sharif University of Technology ; Ghorbani, Mohammad (Supervisor)
Abstract
Plasma electrolyte oxidation process is one of the surface coating methods which is recommended to use as a surface preparation before applying the final coating on magnesium alloys due to its unique properties such as excellent adhesion.The aim of this study was to create an oxide layer on the AZ91 substrate and after optimizing the PEO coating conditions and choosing the best coating in order to increase adhesion and corrosion resistance, the composite coating of graphene oxide, hydroxyapatite and chitosan was applied by electrophoretic method. After studying the morphology of PEO oxide coating at current densities of 0.25, 0.35, 0.4, 0.5 and 0.6 amp/cm2 during times of 5 and 8 minutes, it...
Investigation and Modeling of Polymer Electrolyte Membranes in PEM Fuel Cells
, M.Sc. Thesis Sharif University of Technology ; Roshandel, Ramin (Supervisor)
Abstract
Fuel cells convert the chemical energy of hydrogen and oxygen directly into the electricity. Their high efficiency and low emissions have made them a prime candidate for powering the next generation electric vehicles. Polymer electrolyte membrane is a key component of the PEM fuel cells. One of the critical problems to overcome in some PEM fuel cells is the water management because If there is not enough water, the membrane becomes dehydrated which leads to a rapid increase in ohmic resistance. On the other hand, if too much water is present, flooding may occur resulting in the pores of the gas diffusion filled by water and the available passage for reactant gases is decreased. In this work...
CFD simulation of natural draught cooling tower wind-covering
, Article Applied Mechanics and Materials, Dubai ; Volume 307 , 2013 , Pages 279-284 ; 16609336 (ISSN) ; 9783037856598 (ISBN) ; Salemkar, H ; Behrouzifar, A ; Abrar, B ; Sharif University of Technology
2013
Abstract
Past experiences have shown that a local wind can considerably affect the performances of powerplant cooling towers and factory chimneys. In thermal powerplants, the performance of Rankin cycles would reduce if the temperature of its condenser increases. This issue is very important to powerplants located in countries with strong local winds. To remedy the malperformance of a natural cooling tower in windy conditions, it is required to understand the physics of flow around cooling towers more clearly. One adverse physics is known as the wind covering problem which can drastically affect the natural draught through a cooling tower in windy conditions. In this paper, we focus on wind-covering...
Impact of leadership styles on employees’ performance with moderating role of positive psychological capital
, Article Total Quality Management and Business Excellence ; Volume 32, Issue 9-10 , 2021 , Pages 1085-1105 ; 14783363 (ISSN) ; Iqbal, S ; Abrar, M ; Ahmad Baig, I ; Amjad, F ; Zia-ur-Rehman, M ; Awan, M. U ; Sharif University of Technology
Routledge
2021
Abstract
The study aimed to investigate the most effective leadership style that enhances the employees’ performance at the workplace and also evaluate the impact of leadership styles (Laissez-faire leadership, Transformational leadership, Transactional leadership,) on employees’ performance in the textile sector of Pakistan. The study explored the moderating role of Positive psychological capital to examine the relationship between leadership styles and employee performance. A quantitative research technique was used, and Data were collected from the lower to middle-level manager of the textile sector. The findings of this study showed that laissez-faire leadership has a significant but negative...