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torabi--hooman
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Entropy generation analysis of thermally developing forced convection in fluid-saturated porous medium
, Article Applied Mathematics and Mechanics (English Edition) ; Volume 29, Issue 2 , 2008 , Pages 229-237 ; 02534827 (ISSN) ; Ejlali, A ; Hooman, F ; Sharif University of Technology
2008
Abstract
Entropy generation for thermally developing forced convection in a porous medium bounded by two isothermal parallel plates is investigated analytically on the basis of the Darcy flow model where the viscous dissipation effects had also been taken into account. A parametric study showed that decreasing the group parameter and the Péclet number increases the entropy generation while for the Brinkman number the converse is true. Heatline visualization technique is applied with an emphasis on the Br < 0 case where there is somewhere that heat transfer changes direction at some streamwise location to the wall instead of its original direction, i.e., from the wall. © 2008 Editorial Committee of...
Entropy generation for forced convection in a porous channel with isoflux or isothermal walls
, Article International Journal of Exergy ; Volume 5, Issue 1 , 2008 , Pages 78-96 ; 17428297 (ISSN) ; Hooman, F ; Mohebpour, S. R ; Sharif University of Technology
Inderscience Publishers
2008
Abstract
A numerical study is reported to investigate the entropy generation due to forced convection in a parallel plate channel filled by a saturated porous medium. Two different thermal boundary conditions are considered being isoflux and isothermal walls. Effects of the Poclet number, the porous medium shape factor, the dimensionless temperature difference for isothermal walls, the dimensionless heat flux for isoflux walls, and the Brinkman number on the Bejan number as well as the local and average dimensionless entropy generation rate are examined. Copyright © 2008 Inderscience Enterprises Ltd
Reliability-based Evaluation and Calibration of Load Combinations for the Design of Steel Building Structures of Iran
, M.Sc. Thesis Sharif University of Technology ; Mahsuli, Mojtaba (Supervisor) ; Ghasemi, Hooman ($item.subfieldsMap.e)
Abstract
The objective of this thesis is to evaluate and calibrate design load combinations of steel building structures of Iran based on the reliability theory. The importance of this research stems from recognition that the design load combinations for steel structures in Section 6 of the National Building Code of Iran have been completely adopted from the ASCE/SEI 7-10 standard, whereas the factors that affect these load combinations differ in Iran from those of the United States. Examples are the difference in the construction industry economy, lower quality of here and the differences in probability distributions for the specifications of steel. Hence, the load combinations need to be calibrated...
Physical Modeling of Effect of Liquefaction-Induced Lateral Spreading on Single Piles
, M.Sc. Thesis Sharif University of Technology ; Haeri, Mohsen (Supervisor)
Abstract
Pile foundations suffered severe damages during the past earthquakes in all around the world. These damages were more severe in laterally spreading grounds and they mostly have been observed in gently sloping grounds and coastal areas. In these cases, Pile foundations not only are subjected to structures inertial loads and kinematic loads of liquefied soil but also lateral spreading intensifies damages. Thus, in the recent decade, several researches have been conducted to investigate the behavior of pile foundations in liquefiable and laterally spreading grounds, however, some uncertainties still remain in modeling of soil-pile interaction. In this study, the effects of liquefaction- induced...
Existence of Global Solution for Two Models of Cancer Invasion
, M.Sc. Thesis Sharif University of Technology ; Hesaaraki, Mahmoud (Supervisor)
Abstract
In this thesis we investigating two models of cancer invasion .First, a general mathematical model of cancer invasion is presented. In this model there are three factors: tumor cell, extracellular matrix and enzyme. The model consists of a parabolic partial differential equation (PDE) describing the evolution of tumor cell density , an ordinary differential equation modeling of extracellular matrix and a parabolic PDE governing the evolution of the matrix degrading enzyme concentration. This model is investigated in two special versions for existence and uniqueness of global solutions. In the first model we neglect the remodeling term, this model is named the chemotaxis-haptotaxis model....
“Determination of Economic Order and Production Quantity in Inventory System Regarding the Quality of Items”
, M.Sc. Thesis Sharif University of Technology ; Haji, Rasoul (Supervisor)
Abstract
EOQ and EPQ models have been among the most important and commonly used techniques for about 100 and 60 years respectively .But, they are involved in some assumptions that sometimes prevent them from being implemented in real situation of industry and production. One of these unrealistic assumptions is that all of items received or produced are of perfect quality. In order to overcome this constraint and make the mentioned models closer to the real environmentsome researches have been done. To this end,following the previous attemptsin this project we assumed to have destructive inspections and existence of imperfect and rejected items after rework. In our models, considering 3 circumstances...
Analysis and Simulation of Mars Rover Curiosity in the X and UHF Bands
, M.Sc. Thesis Sharif University of Technology ; Forouhar, Farzaneh (Supervisor)
Abstract
Mars rover Curiosity is a mobile scientific laboratory which it’s mission is to assess the biological potential of the landing site and characterize the geology of the landing region. This rover communicate to a Mars orbiter named MRO satellite in the UHF band which relies the signals to the Earth stations. Also this rover communicate to the Earth stations directly in the X band. In this thesis, we determine the technical characteristics of stations and simulate Earth-Mars radio links. So we calculate :
1. determine the technical characteristics of Earth stations
2. determine the technical characteristics of satellite and Curiosity
3. Earth-Mars orbital position in the...
1. determine the technical characteristics of Earth stations
2. determine the technical characteristics of satellite and Curiosity
3. Earth-Mars orbital position in the...
Impedance Control of a Knee Rehabilitation Exoskeleton Using Robust Adaptive Control
, M.Sc. Thesis Sharif University of Technology ; Vossoughi, Gholamreza (Supervisor)
Abstract
The present study deals with designing controller for Therapeutic Exercise Robots which belongs to larger group namely Rehabilitation robots. Therapeutic exercise robots are often realized in shape of exoskeleton robots. The main line of present research is involved with, designing controller for lower limb therapeutic exercise robots and offering and implementing technical rehabilitation ideas. Firstly, in order to have a reliable position-control, considering practical limitations (e.g. system uncertainties), a robust adaptive control has been designed. Adaptive control can deals with parameters uncertainties and covering unstructured uncertainties (e.g. disturbance and noise) can be...
Effect of lateral placement of ceramic and metal grains on thermal stress distribution throughout FGMS
, Article 28th Congress of the International Council of the Aeronautical Sciences 2012, ICAS 2012 ; Volume 3 , 2012 , Pages 1878-1884 ; 9781622767540 (ISBN) ; Abedian, A ; Sharif University of Technology
2012
Abstract
The properties of Functionally Graded Materials (FGM) are characterized by gradual variation of volume fraction of their constituents or phases over the thickness direction. They are normally ceramic in one side and metal in the other side. This kind of material has been employed as thermal barrier and also as coatings in many applications including turbine blades. Thermal stress behavior of FGMs is normally studied by simulating the material as a composite laminate where the properties ofeach layer are found by averaging the properties and volume fraction of FGM constituents through the thickness of the layer. However, it should be mentioned that the grains of FGM constituents are usually...
A kinetic study on the electrodeposition of nickel nanostructure and its electrocatalytic activity for hydrogen evolution reaction
, Article Journal of Applied Electrochemistry ; Volume 40, Issue 11 , November , 2010 , Pages 1941-1947 ; 0021891X (ISSN) ; Dolati, A ; Sharif University of Technology
2010
Abstract
The electrodeposition of nickel was studied using electrochemical techniques in different electrolytes and various agents. The voltammetry analysis clearly showed that the electrodeposition of nickel was a diffusion-controlled process associated with a typical nucleation process. The current transients represented instantaneous nucleation with a typical three-dimensional (3D) growth mechanism. Scharifker's equations were derived for instantaneous and progressive nucleation of the 3D growth of the spherical centers under diffusion-controlled condition. The number of nucleation sites increased with the increment in overpotential and Ni 2+ concentration. Atomic force microscopy was used to...
An Integrated Simulation-DEA Approach to Multi-criteria Ranking of Scenarios for Execution of Operations in a Construction Project
, M.Sc. Thesis Sharif University of Technology ; Mahlooji, Hashem (Supervisor)
Abstract
Before a construction project gets under way an attempt is made to examine different ways and scenarios for its implementation. Through such a process the more appropriate scenarios should be selected based on several criteria that are not necessarily at the same level in terms of importance. The purpose of this study is to examine different scenarios for implementing operations in the pre-construction phase of a project, based on several competing criteria with different importance levels in order to achieve a more efficient execution plan. This paper presents a new framework that integrates discrete event simulation (DES) and data envelopment analysis (DEA) to rank different scenarios for...
Studying the Characteristics of 2D Materials for Electronic Circuits Devices Master Thesis
, M.Sc. Thesis Sharif University of Technology ; Fardmanesh, Mehdi (Supervisor)
Abstract
The need for further improving the operation of the electronic and optoelectronic devices to raise the speed of the circuits, and to decrease their power dissipation, has led many researchers to investigate the structure of 2D material, such as graphene, transition metal dichalcogenides (TMDs) as MoS2, and other 2D compounds such as BN, due to their prominent electronic properties. TMDs have the highest significant potential for the next generation transistors due to their salient semiconductor characteristics such as electron mobility, band gap, and conductivity. For instance, Graphene is a favorable candidate for analog devices due to zero bandgap. Regarding the importance of bandgap in...
An investigation of the surface morphology of nanostructured nickel thin films prepared by electrodeposition
, Article International Journal of Surface Science and Engineering ; Volume 10, Issue 5 , 2016 , Pages 444-455 ; 1749785X (ISSN) ; Dolati, A ; Sharif University of Technology
Inderscience Enterprises Ltd
2016
Abstract
Nickel nanostructure thin films were electrodeposited on copper plates to investigate the fractal study. Scharifker's equations were derived for instantaneous and progressive nucleation and 3D growth of hemispherical centres under diffusion-controlled condition to calculate in situ change of fractal dimension of surface. It was assumed that the layer could be formed completely when fractal dimension of surface inclined to 2. Moreover, the fractal analysis of atomic force microscopy (AFM) images has confirmed the presumed model. Also, the power values of power spectral density (PSD) of the AFM images were determined using fast Fourier transform (FFT) algorithms. The PSD plots are approximated...
Thesis Submitted in Partial Fulfillment of the Requirements for the Master's Degree in TEFL
, M.Sc. Thesis Sharif University of Technology ; Salehi, Mohammad (Supervisor)
Abstract
In the last decades, Reaction Time research has been extended to cognitive science and more specifically human information-processing research and has gained momentum (Shim, 1996). The present study examined the reaction time in processing marked and unmarked structures with regard to the four types of conditionals (considered as unmarked, less marked, marked and strongly markedness, respectively) and prepositions (preposition pied piping that is considered as unmarked and preposition stranding as marked). To this end, two softwares were developed for which the items relating to conditionals were chosen from the Bernet’s test (1985) and the ones pertinent to prepositions were taken from...
A novel approach for robust control of single-link manipulators with visco-elastic behavior
, Article 10th International Conference on Computer Modelling and Simulation, EUROSIM/UKSim2008, Cambridge, 1 April 2008 through 3 April 2008 ; 2008 , Pages 685-690 ; 0769531148 (ISBN); 9780769531144 (ISBN) ; Jahed, M ; Sharif University of Technology
2008
Abstract
Overwhelming number of control laws has been studied for control of robot manipulators with rigid links and joints. However controllers designed under this assumption may not accurately control the manipulator link due to visco-elastic properties that appear in the link behavior. In this study, a novel approach for robust control of a single-link manipulator is presented to force the link to have rigid motions, while it has visco-elastic behavior. In this regard, initially robot dynamics is extracted, followed by the design of four appropriate controllers through the loop-shaping approach. The obtained model is first represented in state space, however later converted to transfer function...
Impedance analysis of growth and morphology of electropolymerized polypyrrole nanocomposites [electronic resource]
, Article Journal of New Materials for Electrochemical Systems ; 2014, Volume 17, Number 2 ; Sadrnezhaad, S. K ; Sharif University of Technology
Abstract
Pure polypyrrole (PPy), PPy/Al2O3 and PPy/SiO2 nanocomposites synthesized galvanostatically using different polymerization charges. Electrochemical impedance measurements of pure polypyrrole revealed that the film thickness affected the impedance responses. The characteristic frequencies vs. film thickness that obtained using Cole-Cole plots showed that electrodeposition mechanism changed from 3D to 1D after nuclei overlapping for pure PPy. Analysis of the nanocomposites impedance spectrums revealed no changes during the film growth, i.e. deposition continues 3D even after nuclei overlapping. Scanning electron microscopy (SEM) confirmed the impedance results and showed that the morphology of...
Integrated procurement, production, and delivery scheduling in a generalized three stage supply chain [electronic resource]
, Article International Journal of Industrial and Systems Engineering (JISE)-Iranian Institute of Industrial Engineering ; 2009, Vol. 3, No. 3, pp. 189-212 ; Eshghi, Kourosh ; Torabi, S. Ali ; Sharif University of Technology
Abstract
In this research, we investigate a three-stage supply chain with one supplier, several manufacturers and multiple retailers where the supplier provides a common raw material to each manufacturer, who in turn uses a single stage production facility to convert it into final products that are delivered at fixed lot sizes to retailers. An integrated economic procurement, production, and delivery model is developed whose objective is to find the common production cycle length, production sequences of final products at manufacturers and delivery frequencies of final products to retailers minimizing the total costs of considered supply chain. We propose an analytical solution procedure and an...
An accurate derivation of spatial green's function for finite dielectric structures using characteristic green's function-perfectly matched layer method
, Article IEEE Transactions on Antennas and Propagation ; Vol. 62, Issue. 6 , 2014 , pp. 3201-3211 ; ISSN: 0018926X ; Shishegar, A. A ; Sharif University of Technology
2014
Abstract
A closed-form spatial Green's function for a truncated dielectric slab is derived by using a combination of the characteristic Green's function (CGF) and perfectly matched layer (PML) method. The original structure is terminated by PML that is backed by perfect electric conductor (PEC) in semi-infinite layer at the top and/or bottom. The eigenmodes of the closed structure by PML construct the continuous spectrum contribution of the original structure efficiently. Derived Green's function is exact for separable finite structure while it is approximate for nonseparable one especially in the corners. Generalized scattering matrix (GSM) of truncating surface which contains possible conversions...
An efficient 2D rough surface scattering analysis using strong harmonics extraction and the Kirchhoff approach
, Article Applied Computational Electromagnetics Society Journal ; Volume 29, Issue 2 , 1 February , 2014 , Pages 163-169 ; ISSN: 10544887 ; Shishegar, A. A ; Sharif University of Technology
2014
Abstract
An efficient method for scattering analysis from slightly rough surfaces is introduced. This method can be used in ray tracing algorithm where the computational efficiency is important due to the complexity and size of problems. In this method, the Kirchhoff approach is used for a periodic extension of the finite surface, which is approximated by strong harmonics of its Fourier series. Typical asphalt surfaces are analyzed by this method in millimeter-wave band and validated with the method of moments. The dominant scattering angles and ray widths of the scattered field can be easily used in ray tracing algorithm. The computation time and accuracy of results show that this method can be used...
An efficient approach for reflectivity and coupling computation in an abruptly ended planar layered waveguide using modified formulation of CGF-RFFM
, Article German Microwave Conference, GeMiC 2016, 14 March 2016 through 16 March 2016 ; 2016 , Pages 128-131 ; 9783981266870 (ISBN) ; Shishegar, A. A ; Sharif University of Technology
Institute of Electrical and Electronics Engineers Inc
2016
Abstract
An efficient method for computation of surface wave (SW) reflectivity and coupling in an abruptly ended planar layered waveguide is presented. Using characteristic Green's function (CGF) technique, the original structure is approximated by a separable structure. Then by applying rational function fitting method (RFFM) a uniform and closed-form expression of spatial Green's function for separable structure is derived. Having a full wave solution of the original structure, an optimization problem is defined to find the reflection coefficients of SW modes. Unlike the previous presented CGF based method called CGF-complex images (CI), CGF-RFFM leads to easy incorporation of radiation modes...