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toloui--mostafa
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Microstructural evolution on streamlines during hot strip rolling using internal state variables
, Article Journal of Materials Processing Technology ; Volume 209, Issue 4 , 2009 , Pages 1717-1728 ; 09240136 (ISSN) ; Serajzadeh, S ; Sharif University of Technology
2009
Abstract
In this work, a numerical-based model has been proposed to calculate distributions of temperature, strain and strain rate during hot rolling as well as the subsequent microstructural changes after hot rolling of an aluminum alloy. For doing so, a transient finite difference analysis together with a stream function method have been coupled to calculate temperature distribution and velocity field within the rolling metal. A new approach considering internal state variables method has been employed to predict the kinetics of static recrystallization after hot rolling. The predicted results were then compared with the experimental ones and a good consistency was observed between the two sets of...
Modelling recrystallization kinetics during hot rolling of AA5083
, Article Journal of Materials Processing Technology ; Volume 184, Issue 1-3 , 2007 , Pages 345-353 ; 09240136 (ISSN) ; Serajzadeh, S ; Sharif University of Technology
2007
Abstract
In this work, a mathematical model has been developed to predict distributions of temperature, strain and strain rate during hot rolling as well as the subsequent microstructural changes after hot deformation. For doing so, a 2-D finite element analysis together with a stream function method have been coupled to calculate temperature distribution and velocity field within the rolling metal while the roll force has been estimated, through using an upper bound solution. Also the additivity rule and Avrami-type equation have been employed to predict the kinetics of static recrystallization after hot rolling. The model has been examined on AA5083. Hot rolling experiments have been conducted...
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) ; Firoozabadi, B ; Saidi, M. S ; Sharif University of Technology
2012
Abstract
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....
Validity of cauchy-born hypothesis in multi-scale modeling of plastic deformations
, Article International Journal of Solids and Structures ; 2017 ; 00207683 (ISSN) ; Jahanshahi, M ; Toloui, G ; Sharif University of Technology
Elsevier Ltd
2017
Abstract
The Cauchy-Born (CB) hypothesis has been widely used in multi-scale modeling of crystalline nano-structures. The violation of CB hypothesis in stress space and the transition to plasticity, which is equivalent to the violation of CB hypothesis in strain space, are generally confused and it becomes crucial to differentiate between the two distinct phenomena; the violation of the former usually occurs at high values of stress and at regions where the surface effects are manifest while the violation of the latter occurs at low stresses when the material loses its strength to tolerate the applied loading. In this paper, a novel technique is developed to investigate the validity of CB hypothesis...
Validity of cauchy–born hypothesis in multi-scale modeling of plastic deformations
, Article International Journal of Solids and Structures ; Volume 115-116 , 2017 , Pages 224-247 ; 00207683 (ISSN) ; Jahanshahi, M ; Toloui, G ; Sharif University of Technology
Elsevier Ltd
2017
Abstract
The Cauchy–Born (CB) hypothesis has been widely used in multi-scale modeling of crystalline nano-structures. The violation of CB hypothesis in stress space and the transition to plasticity, which is equivalent to the violation of CB hypothesis in strain space, are generally confused and it becomes crucial to differentiate between the two distinct phenomena; the violation of the former usually occurs at high values of stress and at regions where the surface effects are manifest while the violation of the latter occurs at low stresses when the material loses its strength to tolerate the applied loading. In this paper, a novel technique is developed to investigate the validity of CB hypothesis...
Numerical simulations of haemodynamic factors and hyperelastic Circumferential Strain/Stress in the ideal and healthy-patient-specific carotid bifurcations for different rheological models
, Article International Journal of Biomedical Engineering and Technology ; Volume 6, Issue 4 , 2011 , Pages 387-412 ; 17526418 (ISSN) ; Nikparto, A ; Firoozabadi, B ; Saidi, M. S ; Sharif University of Technology
2011
Abstract
To explore the role of hemodynamic in the initiation and progression of stenosis in carotid artery bifurcation, a Computational Fluid Dynamics (CFD) technique is applied. The effect of four rheology models is investigated as well as various mechanical phenomena. In this study, a Finite Element Method (FEM) was applied to simulate the physiologic Circumferential Strain/Stress (CS) Meanwhile, to investigate the role of vessel wall flexibility, a Fluid-Structure Interaction (FSI) analysis was applied. It was concluded that velocity profiles and WSS show sensitivity to arterial wall stiffening while shear thinning models do not have a dominant effect on the flow field
Numerical Fluid–Structure Interaction and non-Newtonian Simulation of Blood Flow in a Compliant Carotid Bifurcation
, M.Sc. Thesis Sharif University of Technology ; Firoozabadi, Bahar (Supervisor) ; Saidi, Mohammad Saeid (Co-Advisor)
Abstract
Researchers have done a lot of studies about the use of CFS in blood flow modeling in order to improve the supplementary devices or find mechanical factors which cause artery to be diseased. Blood is a complex rheological fluid, blood flow is a pulastile flow, and blood flow field interacts with the deformable vessel wall. Thus, blood flow modeling like other biological phenomena has its own complexities such as anisotropy, vsicoelasticity, and nonlinearity in stress-strain relationship of vessel wall. To explore the role of hemodynamics in the initiation and progression of stenosis in carotid artery bifurcation, a 3D Computational Fluid Dynamics (CFD) technique is applied. The effect of...
Periodic solutions for a semi-ratio-dependent predator-prey dynamical system with a class of functional responses on time scales
, Article Discrete and Continuous Dynamical Systems - Series B ; Volume 9, Issue 2 , 2008 , Pages 267-279 ; 15313492 (ISSN) ; Hesaaraki, M ; Sharif University of Technology
2008
Abstract
In this paper we explore the existence of periodic solutions of a nonautonomous semi-ratio-dependent predator-prey dynamical system with functional responses on time scales. To illustrate the utility of this work, we should mention that, in our results this system with a large class of monotone functional responses, always has at least one periodic solution. For instance, this system with some celebrated functional responses such as Holling type-II (or Michaelis-Menten), Holling type-III, Ivlev, mx (Holling type I), sigmoidal [e.g., Real and mx2/((A + x)(B +x))] and some other monotone functions, has always at least one ω-periodic solution. Besides, for some well-known functional responses...
Modified Load Scheduling Using Smart Meters
, M.Sc. Thesis Sharif University of Technology ; Parniani, Mostafa (Supervisor)
Abstract
Implementation of various incentive-based demand response strategies has great potential to decrease peak load growth and customer electricity bill cost. Using advanced metering and automatic demand management makes it possible to optimize energy consumption, to reduce grid loss, and to release generation capacities for the sake of providing sustainable electricity supply, and reducing electricity bills for the customers. With these objectives, this thesis examines the previously suggested load scheduling programs in both residential and industrial sectors, and proposes new practical strategies for load management. This thesis has mainly focuses on three subdivisions of load management...
The Analysis of Total Productive Maintenance Based on Computerized Maintenance Management System
, M.Sc. Thesis Sharif University of Technology ; mostafavi, mostafa (Supervisor)
Abstract
The main purpose of this thesis is to analyze the total productive maintenance based on computerized maintenance management system. At first, a detailed study on total productive maintenance is performed and then the requirements of this maintenance strategy are specified. Also, a computerized maintenance management system is defined which can help total productive maintenance to reach to its requirements. Finally, a conceptual model and entity-relationship model for computerized maintenance management system data base has been created
Study of HVDC Transmission for Offshore Wind Farms Based on Voltage Source Converters
, M.Sc. Thesis Sharif University of Technology ; Parniani, Mostafa (Supervisor)
Abstract
In this thesis, DC transmission of offshore wind farms is studied thoroughly. Various system configurations that are introduced in the literatures are discussed and their control scheme for normal conditions and grid faults are studied. Then, the HVDC transmission based on voltage source converter, located between a local offshore ac grid and the onshore ac system is investigated as the most practical choice. The HVDC linke circuit elements are calculated and the control strategies of the offshore and onshore converters are introduced. DFIGs are considered to be the best choice for the offshore wind turbine generators. Then, the system is simulated and the frequency of the offshore grid is...
Feasibility Study of Producing Active Pharmaceutical Ingredient from Conceptual Process to Mass Production-Case Study
, M.Sc. Thesis Sharif University of Technology ; Mostafavi, Mostafa (Supervisor)
Abstract
The main aim of this thesis is to develop the technical knowledge of designing and making active ingredients of domestically produced drugs, decreasing the costs, independency in producing these products, and checking outflow of currency. It also aims to reduce the financial challenges of patients who have to pay huge amounts for such drugs. Conducting research in the field of reverse engineering and using its definition, and attempt in made to get knowledge into the stages of product development process, to determine the technical standards associated with each stage, to recognize how knowledge is shared during this process, and to present some methods of establishing the infrastructure...
Performance Improvement of Maximum Power Point Tracker in Grid-Connected Photovoltaic Systems
, M.Sc. Thesis Sharif University of Technology ; Parniani, Mostafa (Supervisor)
Abstract
Increase in growing concerns over environmental pollution and depletion of fossil fuel resources motivate the need for cleaner energy technologies and stimulate research in facilitating renewable energy systems. In recent years, photovoltaic systems have attracted great attention since they remove the need for energy storage systems and intermediate processess for energy conversion. However, high capital cost, low efficiency and low energy density per area of these systems, as compared with other technologies hinder its industrial use. To surmount these bottlenecks and improve technical performance of PV systems, it is crucial to optimize configuration of convertor connection and to improve...
Coordinated Voltage Control of Power Systems in Normal and Emergency Operation States
, Ph.D. Dissertation Sharif University of Technology ; Parniani, Mostafa (Supervisor)
Abstract
One of the main objectives in operating a power system is to maintain the system voltage properly to avoid equipment damage and transfer power efficiently. Automatic control of transmission network voltage provides significant improvements in security, quality and efficiency of power system operation. This thesis investigates coordinated voltage control of power systems in normal, alert and emergency states. The aim is to propose a comprehensive framework for real-time operation of practical power systems, ensuring secure operation of the system in the normal state and after occurrence of sever contingencies.
At the first, a new coordinated voltage control scheme is proposed to ensure...
At the first, a new coordinated voltage control scheme is proposed to ensure...
The Analysis of Knowledge Management, Dimensions and Implementation Methods-Case study: Sardsaz Khodro Ind. Co
, M.Sc. Thesis Sharif University of Technology ; Mostafavi, Mostafa (Supervisor)
Abstract
Today, organizations are surrounded by basic and continuous changes such as declining organizational resources, reduction of the production cycles, and the need for rapid adaption. Those organizations remain competitive while maintaining their productivity, that have following characteristics: accurately plan and assess their knowledge resources, create and absorb beneficial knowledge, store and organize their knowledge, disseminate knowledge to needed areas, and use knowledge in practice and decision making, to improve their products/services as well as their performance. Therefore, the human capital has been considered as knowledge owners and the most important organizational resource, on...
Feyerabend’s Point of View on Scientific Progress
, M.Sc. Thesis Sharif University of Technology ; Taghavi, Mostafa (Supervisor)
Abstract
Feyarabend’s philosophy of science is against method and rule such that he believes that “anything goes”. However, he sometimes applies the term “progress”. Reviewing his publications shows that from his point of view, progress is qualitative and relative. So, unlike other philosophers of science Feyarabend ignores the clarification of the concept; subsequently, his applications of the term “progress” are somewhat ambiguous. However, by studying his philosophy, one may realize what should be done to achieve progress in any sense. The affirmative aspect of Feyerabend’s philosophy, while highlights the social and ethical elements, considering his humanitarian outlook as well as his special...
Analyzing the Healthcare Wastes and Feasibility Study of Related Items (Plastics)
, M.Sc. Thesis Sharif University of Technology ; Mostafavi, Mostafa (Supervisor)
Abstract
Increasing population and competition for producing various productions and also more consumption in recent decades, result in producing more wastes. Therefore effective and continuous waste management is essential for monitoring the process (from the wastes generation source to the waste disposal) and establishing the efficient strategies to reduce wastes. One of the major sources of waste generation is hospitals that cause lots of environmental problem unless they are managed properly.Recycling is an important element of waste management that can reduce costs by innovative and proper management. The purpose of this research is identification of recyclable plastic items and estimates the...
Analyzing Cost Engineering Along With Presenting A Model To Reduce Cost Of industrial Products
, M.Sc. Thesis Sharif University of Technology ; Mostafavi, Mostafa (Supervisor)
Abstract
Lack of financial sources for production and performing projects has been an effective issue in all governmental and non-governmental organizations. So, using a structure with capability of detecting and forecasting all expenses and costs, and being able to convert the mass of data into useful and instrumental reports for managerial decision such as estimating total cost, selecting the syntax of production and etc is obvious for recourse management of every organization. Among the various components of the cost engineering system, cost management system by recording and allocating cost is an important issue in efficiency of every cost engineering system.In this thesis, Automotive Industrial...
Feasibility Study of Manufacturing of Disposable Plant Containers
,
M.Sc. Thesis
Sharif University of Technology
;
Mostafavi, Mostafa
(Supervisor)
Abstract
Although laws vary in the competitive business world of today and the changing supply and demand parameters show that the process of delivering new products to market is very important.Most organizations today have found that spending more than ever on trusting in traditional competitive levers such as quality, cost reduction and differentiation in selling more products and services are not enough to be successful in market, instead notions such as speed, flexibility andagility can have a significant trend toward offering new products and services. There aresome good reasons for knew that organizations need new ways to develop their new products to survival, compete with its competitors and...
Research to Provide Iranian Customer Satisfaction Index Model in Industry, Case Study: Iran Khodro Co., Golrang Co. and Kaleh Co
, M.Sc. Thesis Sharif University of Technology ; Mostafavi, Mostafa (Supervisor)
Abstract
In recent decades many countries have attempted to measure and formulate customer satisfaction index (CSI), as an important factor in micro and macro-economic level. In developed country CSI has the same value of GNP. Customer Satisfaction Index model actually represents the relationship between primary factors of satisfaction and satisfaction results in the macro level for a country and includes all business aspects. In many countries, industrial companies have a wide range of products and providing Customer Satisfaction Index model for this aspect which can be a base of presenting national customer satisfaction index model. Accordingly, the main goal of this study is providing an Iranian...