Search for: three-dimensional-model
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    Kinetics of static strain aging after temper rolling of low carbon steel

    , Article Ironmaking and Steelmaking ; Volume 38, Issue 4 , 2011 , Pages 314-320 ; 03019233 (ISSN) Koohbor, B ; Serajzadeh, S ; Sharif University of Technology
    In this study, static strain aging behaviour of cold rolled steel strips was considered with emphasis on the distribution of residual hydrostatic stress developed during temper rolling. In order to assess residual stress distribution produced by the temper rolling, a three-dimensional model was first employed. Then, samples were rolled at a reduction of 4% under single and double pass rolling programmes and the kinetics of static strain aging phenomenon as well as the required activation energies were then evaluated using hardness and tensile tests on the deformed samples. Considering the predicted residual hydrostatic stress distribution, it was found that tensile hydrostatic stresses... 

    Thermo-mechanical and microstructural issues in dissimilar friction stir welding of AA5086-AA6061

    , Article Journal of Materials Science ; Volume 46, Issue 10 , 2011 , Pages 3258-3268 ; 00222461 (ISSN) Jamshidi Aval, H ; Serajzadeh, S ; Kokabi, A. H ; Sharif University of Technology
    In this research, thermo-mechanical behavior and microstructural events in dissimilar friction stir welding of AA6061-T6 and AA5086-O have been evaluated. The thermo-mechanical responses of materials during the process have been predicted employing a three-dimensional model together with a finite element software, ABAQUS. Then, mechanical properties and microstructures of the weld zone were studied with the aid of experimental observations and model predictions. It is found that the mixing of material in the weld nugget is performed more efficiently when AA5086 is in the advancing side and also the temperature field is distributed asymmetrically resulting in larger thermally affected region... 

    Endurance time method for multi-component analysis of steel elastic moment frames

    , Article Scientia Iranica ; Volume 18, Issue 2 A , 2011 , Pages 139-149 ; 10263098 (ISSN) Valamanesh, V ; Estekanchi, H. E ; Sharif University of Technology
    The Endurance Time (ET) method is a time history-based dynamic analysis procedure which uses special intensifying acceleration functions for evaluation of the seismic response of structures. One of the potential applications of the ET method is in the three-dimensional analysis of buildings under multidirectional excitations. In this paper, considering horizontal components of excitation, an algorithm for the multi-component analysis of building structures by the ET method is proposed, and results of the ET method for various steel moment frames with 1 to 7 stories are compared with results from time history analysis with real earthquakes. Results show that based on recommendations of... 

    Three dimensional modeling of axonal microtubules

    , Article 2014 21st Iranian Conference on Biomedical Engineering, ICBME 2014, 26 November 2014 through 28 November 2014 ; November , 2014 , Pages 298-302 ; 9781479974177 (ISBN) Manuchehrfar, F ; Shamloo, A ; Sharif University of Technology
    Institute of Electrical and Electronics Engineers Inc  2014
    Axon is a filament in neuronal system and axonal microtubules are bundles in axons. In axons, microtubules are coated with microtubule-associated protein tau, a natively unfolded profuse filamentous protein in the central nervous system. These proteins are responsible for the cross-linked structure of the axonal microtubule bundles. Through complimentary dimerization with other tau proteins, bridges are formed to nearby microtubules to create bundles. The transverse reinforcement of microtubules by cross-linking to the cytoskeleton has been shown to enhance their ability to bear compressive loads. Though microtubules are conventionally regarded as bearing compressive loads, in certain... 

    A numerical study of the effects of blood rheology and vessel deformability on the hemodynamics of carotid bifurcation

    , Article Scientia Iranica ; Volume 19, Issue 1 , February , 2012 , Pages 119-125 ; 10263098 (ISSN) Toloui, M ; Firoozabadi, B ; Saidi, M. S ; Sharif University of Technology
    Hemodynamic factors, such as Wall Shear Stress (WSS), play a substantial role in arterial diseases. In the larger arteries, such as the carotid artery, interaction between the vessel wall and blood flow affects the distribution of hemodynamic factors. In the present study, both rigid-wall and deformable-wall models are developed in a 3D numerical simulation to assess the effectiveness of arterial rigidity on worsening hemodynamics, especially WSS. Two different rheological models (Newtonian and CarreauYasuda) have been employed to evaluate the influence of blood, non-Newtonian properties, as well. The importance of vessel wall deformability was compared with the rheological model of blood.... 

    Assessment of a parallel evolutionary optimization approach for efficient management of coastal aquifers

    , Article Environmental Modelling and Software ; Volume 74 , December , 2015 , Pages 21-38 ; 13648152 (ISSN) Ketabchi, H ; Ataie Ashtiani, B ; Sharif University of Technology
    Elsevier Ltd  2015
    This study presents a parallel evolutionary optimization approach to determine optimal management strategies of large-scale coastal groundwater problems. The population loops of evolutionary algorithms (EA) are parallelized using shared memory parallelism to address the high computational demands of such applications. This methodology is applied to solve the management problems in an aquifer system in Kish Island, Iran using a three-dimensional density-dependent groundwater numerical model. EAs of continuous ant colony optimization (CACO), particle swarm optimization, and genetic algorithm are utilized to solve the optimization problems. By implementing the parallelization strategy, a... 

    Modeling of Oxygen Transport and Exchange in an Acinus

    , M.Sc. Thesis Sharif University of Technology Mortazavi Ashkzari, Mohammad Sadegh (Author) ; Saeedi, Mohammad Saeed (Supervisor)
    An acinus is defined as the complex of airways supplied by one first order respiratory or transitional bronchiole. In this part, the replenishment of oxygen at the alveolar surface occurs by a combination of convective air flow with diffusion of oxygen in the air. So for studying gas exchange in the lung, modeling gas species transport and exchange in an acinus is important. Due to lacking direct measurements of the distribution of oxygen (or carbon dioxide) concentration in the acinus, several mathematical models have been developed and studied by numerical simulations. But in none of them the influence of breathing pattern and the role of blood flow in restricting the gas exchange rate have... 

    Evaluation of Endurance Time Method in Nonlinear Dynamic Analysis of Unreinforced Brick Masonry Buildings

    , M.Sc. Thesis Sharif University of Technology Kiani Nia, Mohammad Ali (Author) ; Esmaeil Pourestekanchi, Homayoon (Supervisor)
    The existing statistical studies implies that in Iran like most of developing countries, the great percent of houses are traditional. Statistics of the most disastrous current quakes also show damages caused by masonry structures in developing countries. The main problem of brick and masonry structures especially the unreinforced one is their weak performance against quake. Different methods are use to analyse the seismic performance of this structures. The modern endurance time method is a kind of time history analysis using standard increasing accelerograms which examines different parameters of structure behavior during excitation actions. In this project we analyse these structures using... 

    Numerical investigation of a stepped planing hull in calm water

    , Article Ocean Engineering ; Volume 94 , January , 2015 , Pages 103-110 ; 00298018 (ISSN) Lotfi, P ; Ashrafizaadeh, M ; Esfahan, R. K ; Sharif University of Technology
    Elsevier Ltd  2015
    Stepped planing hulls enable the feasibility of running at relatively low Drag-Lift ratio by means of achieving more optimal trim angle at high speeds. Currently, there is no precise method to analyze these hulls over the full range of operating speeds. In this study, a three-dimensional computational fluid dynamics (CFD) model using volume of fluid (VOF) approach is presented for examining the characteristics of a planing hull having one transverse step. A procedure is presented to transform a series of fixed-position simulations into a free to heave and pitch simulation. Resistance, lift, running draft, dynamic trim angle, and wetted area are compared with available experimental data and... 

    CFD-DEM Model for Simulation of Non-spherical Particles in Hole Cleaning Process

    , Article Particulate Science and Technology ; Volume 33, Issue 5 , 2015 , Pages 472-481 ; 02726351 (ISSN) Akhshik, S ; Behzad, M ; Rajabi, M ; Sharif University of Technology
    Taylor and Francis Inc  2015
    During the well drilling process, particles are produced in different shapes. The shape of particles can influence the characteristics of particles transport process. The aim of this work is to analyze the effects of particle shape on the transportation mechanism. For this purpose, a three-dimensional model is prepared for simulation of particle transportation with spherical and non-spherical shapes, during deviated well drilling. The motion of particles and the non-Newtonian fluid flow are simulated via discrete element method and CFD, respectively. The two-way coupling scheme is used to incorporate the effects of fluid-particle interactions. Three different samples of non-spherical shapes... 

    Hydrodynamic and electrochemical modeling of vanadium redox flow battery

    , Article Mechanics and Industry ; Volume 16, Issue 2 , 2015 ; 22577777 (ISSN) Ozgoli, H. A ; Elyasi, S ; Mollazadeh, M ; Sharif University of Technology
    EDP Sciences  2015
    Two and three dimensional modeling of a single cell of vanadium redox flow battery has been done thoroughly according to electrochemical and fluid mechanic equations in this study. The modeling has been done in stationary state and its results have been presented in three chemical, electrical and mechanical sub models. The parametric analysis on some of important factors in cell operation demonstrated that increase in electrode and membrane conductivity and electrode porosity contributes to electric potential increase in cells. Also operational temperature increase leads to decrease in cells' voltage. Better fluid distribution on the electrode surface area results in better cell operation,... 

    Linear and nonlinear model of cutting forces in peripheral milling: A comparison between the accuracy of 2D and 3D models

    , Article 2009 ASME International Mechanical Engineering Congress and Exposition, IMECE2009, Lake Buena Vista, FL, 13 November 2009 through 19 November 2009 ; Volume 3 , 2010 , Pages 955-962 ; 9780791843765 (ISBN) Moradi, H ; Movahhedy, M. R ; Vossoughi, G ; Sharif University of Technology
    Peripheral milling is extensively used in manufacturing processes, especially in aerospace industry where end mills are used for milling of wing parts and engine components. Knowledge of the cutting forces is the first necessary stage in analysis of the milling process. In this paper, cutting forces are presented for both two and three dimensional models. Instead of the common linear dependency of cutting forces to the cut chip thickness, two nonlinear models are presented. In the first model, cutting forces are considered as a function of chip thickness with a complete third order polynomial. In the second one, the quadratic and constant terms of the third order polynomial are set to zero.... 

    Modeling of cell deformation under external force using artificial neural network

    , Article ASME International Mechanical Engineering Congress and Exposition, Proceedings (IMECE), 12 November 2010 through 18 November 2010 ; Volume 2 , 2010 , Pages 659-665 ; 9780791844267 (ISBN) Ahmadian, M. T ; Vossoughi, G. R ; Abbasi, A. A ; Raeissi, P ; Sharif University of Technology
    Embryogenesis, regeneration and cell differentiation in microbiological entities are influenced by mechanical forces. Therefore, development of mechanical properties of these materials is important. Neural network technique is a useful method which can be used to obtain cell deformation by the means of force-geometric deformation data or vice versa. Prior to insertion in the needle injection process, deformation and geometry of cell under external point-load is a key element to understand the interaction between cell and needle. In this paper the goal is the prediction of cell membrane deformation under a certain force, and to visually estimate the force of indentation on the membrane from... 

    Effect of different configurations on 3-D analysis of flow through stay vanes And guide vanes of a francis turbine

    , Article Scientia Iranica ; Volume 17, Issue 6 B , NOVEMBER-DECEMBER , 2010 , Pages 419-432 ; 10263098 (ISSN) Dadfar, R ; Firoozabadi, B ; Ahmadi, G ; Sharif University of Technology
    Stay and guide vanes (distributor) are essential parts of a turbine. They are used to control the flow rate and to appropriately transfer the flow momentum to the runner. In this work, flow through the distributor is analyzed. For various Boundary Conditions (BC) and different configurations, threedimensional flows in the distributor of a Francis turbine are evaluated and compared with each other. The numerical simulations were carried out using Fluent software and the results were validated with a GAMM Francis turbine, where the geometry and detailed best efficiency measurements were publically available. In these simulations, the flow was assumed to be steady and the effect of turbulence... 

    3D Modeling of damage growth and crack initiation using adaptive finite element technique

    , Article Scientia Iranica ; Volume 17, Issue 5 A , 2010 , Pages 372-386 ; 10263098 (ISSN) Moslemi, H ; Khoei, A. R ; Sharif University of Technology
    In this paper, the continuum damage mechanics model originally proposed by Lemaitre (Journal of Engineering Materials and Technology. 1985; 107: 83-89) is presented through an adaptive finite element method for three-dimensional ductile materials. The macro-crack initiation-propagation criterion is used based on the distribution of damage variable in the continuum damage model. The microcrack closure effect is incorporated to simulate the damage evolution more realistic. The Zienkiewicz-Zhu posteriori error estimator is employed in conjunction with a weighted Superconvergence Patch Recovery (SPR) technique at each patch to improve the accuracy of error estimation and data transfer process.... 

    On the multi-scale computation of un-bonded flexible risers

    , Article Engineering Structures ; Volume 32, Issue 8 , August , 2010 , Pages 2287-2299 ; 01410296 (ISSN) Bahtui, A ; Alfano, G ; Bahai, H ; Hosseini Kordkheili, S. A ; Sharif University of Technology
    The purpose of this paper is to model the detailed effects of interactions that take place between components of un-bonded flexible risers, and to study the three-dimensional motion responses of risers when subjected to axial loads, bending moments, and internal and external pressures. A constitutive law for un-bonded flexible risers is proposed and a procedure for the identification of the related input parameters is developed using a multi-scale approach. A generalized finite element structural model based on the Euler-Bernoulli beam theory is developed in which the constitutive law is embedded. The beam theory is enhanced by the addition of suitable pressure terms to the generalized... 

    Three dimensional numerical investigation of air flow over domed roofs

    , Article Journal of Wind Engineering and Industrial Aerodynamics ; Volume 98, Issue 3 , 2010 , Pages 161-168 ; 01676105 (ISSN) Faghih, A. K ; Bahadori, M. N ; Sharif University of Technology
    Domed roofs have been used in Iran and many other countries to cover large buildings such as mosques, shrines, churches, schools, etc. However their favorable thermal performance made them to be employed in other buildings such as bazaars, or market places, in Iran. The aim of this study was to determine the air pressure distribution over domed roofs, employing a numerical method. In this investigation, a three-dimensional model and a laminar inlet air flow were considered. The k-ε RNG method was employed for the turbulent flow simulation method. Simulation was run under three conditions of windows and a hole on top of the dome being open, or closed. The results were compared with the... 

    Three-dimensional simulation of turbulent flow in 3-sub channels of a VVER-1000 reactor

    , Article Scientia Iranica ; Volume 17, Issue 2 B , 2010 , Pages 83-92 ; 10263098 (ISSN) Ganjiani, H ; Firoozabadi, B ; Sharif University of Technology
    In this study, the fluid dynamics and convective heat transfer for turbulent flows through a 3-sub channel of a rod bundle, which is representative of those used in VVER-1000, are examined. The rod bundle is constructed from parallel rods in a hexagonal array. The rods are on constant pitch by spacer grids spaced axially along the rod bundle. The geometry details of the bundle and heat flux from the fuel rod are similar to that of the Iranian nuclear reactor under construction. A numerical study using Computational Fluid Dynamics (CFD) was carried out to estimate the flow field, pressure loss and heat transfer coefficients in spacer grids and rod bundles. Turbulence has been modeled using... 

    A physically-based three dimensional fracture network modeling technique

    , Article Scientia Iranica ; Volume 19, Issue 3 , 2012 , Pages 594-604 ; 10263098 (ISSN) Masihi, M ; Sobhani, M ; Al Ajmi, A. M ; Al Wahaibi, Y. M ; Khamis Al Wahaibi, T ; Sharif University of Technology
    In poorly developed fractured rocks, the contribution of individual fracture on rock conductivity should be considered. However, due to the lack of data, a deterministic approach cannot be used. The conventional way to model discrete fractures is to use a Poisson process, with prescribed distribution, for fracture size and orientation. Recently, a stochastic approach, based on the idea that the elastic energy due to fractures follows a Boltzmann distribution, has been used to generate realizations of correlated fractures in two dimensions. The elastic energy function has been derived by applying the appropriate physical laws in an elastic medium. The resulting energy function has been used... 

    Axial-flow compressor performance prediction in design and off-design conditions through 1-D and 3-D modeling and experimental study

    , Article Journal of Applied Fluid Mechanics ; Volume 9, Issue 5 , 2016 , Pages 2149-2160 ; 17353572 (ISSN) Peyvan, A ; Hajilouy benisi, A ; Sharif University of Technology
    Isfahan University of Technology 
    In this study, the main objective is to develop a one dimensional model to predict design and off design performance of an operational axial flow compressor by considering the whole gas turbine assembly. The design and off-design performance of a single stage axial compressor are predicted through 1D and 3D modeling. In one dimensional model the mass, momentum and energy conservation equations and ideal gas equation of state are solved in mean line at three axial stations including rotor inlet, rotor outlet and stator outlet. The total to total efficiency and pressure ratio are forecasted using the compressor geometry, inlet stagnation temperature and stagnation pressure, the mass flow rate...