Loading...
Search for:
taghi-esfidani--m
0.102 seconds
Total 19695 records
Modeling and experimental investigation of bubble formation in shear-thinning liquids
, Article Journal of Fluids Engineering, Transactions of the ASME ; Volume 139, Issue 7 , 2017 ; 00982202 (ISSN) ; Reza Oshaghi, M ; Afshin, H ; Firoozabadi, B ; Sharif University of Technology
American Society of Mechanical Engineers (ASME)
2017
Abstract
This investigation presents both theoretical and experimental studies on the size of a growing bubble in power-law non-Newtonian liquids. At first, some previous works on the prediction of bubble size in Newtonian liquids have been extended by considering the balance of forces acting on the bubble at the moment of separation. Predicted bubble sizes were validated against the experimental results for a wide range of operating conditions, including different gas flow rates and needle diameters as well as a wide range of physical properties of the Newtonian liquids. Furthermore, in order to determine the size of the bubbles formed in power-law non-Newtonian liquids with a similar analysis, the...
Computational study on design parameters of a solar chimney
, Article International Conference on Sustainable Mobility Applications, Renewables and Technology, 23 November 2015 through 25 November 2015 ; 2015 ; 9781467395298 (ISBN) ; Raveshi, S ; Shahsavari, M ; Sedaghat, A ; Sharif University of Technology
Institute of Electrical and Electronics Engineers Inc
2015
Abstract
Today, the production of energy and electricity is one of the major concerns of mankind. Electricity generation by solar energy is considered as one of the alternatives to fossil fuels. Solar chimneys mechanism is based on a natural phenomenon. In this process the solar energy heat up the earth's surface and the surrounding air. Due to the density difference between cold air and warm air, heated air ascends and causes air circulation. In this study, mathematical modelling of solar chimney and governing equations of this system will be discussed. In order to validate the numerical results, upwind velocity in chimney has been compared with a reliable reference results. As well as, the...
Exergy analysis of reactive combustion processes in gas heaters
, Article IEOM 2015 - 5th International Conference on Industrial Engineering and Operations Management, Proceeding, 3 March 2015 through 5 March 2015 ; 2015 ; 9781479960651 (ISBN) ; Haj Assad, M. E ; Gaith, M ; Esfidani, M. T ; Sharif University of Technology
Institute of Electrical and Electronics Engineers Inc
2015
Abstract
In this study, exergy analysis and second law efficiency of gas heaters with reactive combustion processes are considered. The reactive combustion of natural gas is modeled via a chain of eight chemical reactions along with first and second law of thermodynamics. The main constitutional elements react in combustion chamber is considered at constant pressure and temperature of the basic elements hydrogen, carbon, oxygen, and nitrogen from the fuel and air. Heat transfer is modeled assuming free convection and radiation mechanisms from gas heater outer surfaces. The governed equations were solved using Engineering Equation Solver (EES) software tool. Results of this study reveal that...
Experimental Study of a Single Bubble Formation and Its Deformation in Shear-thinning Fluids
, M.Sc. Thesis Sharif University of Technology ; Afshin, Hossein (Supervisor) ; Firoozabadi, Bahar (Supervisor)
Abstract
Bubble formation and bubble rising are widely used in many industrial processes such as bubble columns, extraction, fermentation, foaming and polymerization. Although many of these processes are faced with a series of bubbles, this study may help us better understand the hydrodynamics of single bubble formation and bubble rising and provides a deep insight into the modeling of a series of bubbles. Bubble velocity and drag coefficient in various fluids are the major parameters for designing the liquid-gas systems. These parameters are a function of the bubble size. In this study, single bubble formation is theoretically modelled in order to predict the size of the bubble at the moment of...
On the primary resonance of an electrostatically actuated MEMS using the homotopy perturbation method
, Article Proceedings of the ASME Design Engineering Technical Conference, 30 August 2009 through 2 September 2009, San Diego, CA ; Volume 6 , 2009 , Pages 569-574 ; 9780791849033 (ISBN) ; Moghimi Zand, M ; Taghi Ahmadian, M ; Sharif University of Technology
2009
Abstract
In this paper, primary resonance of a double-clamped microbeam has been investigated. The Microbeam is predeformed by a DC electrostatic force and then driven to vibrate by an AC harmonic electrostatic force. Effects of midplane stretching, axial loads and damping are considered in modeling. Galerkin's approximation is utilized to convert the nonlinear partial differential equation of motion to a nonlinear ordinary differential equation. Afterward, a combination of homotopy perturbation method and the method of multiple scales are utilized to find analytic solutions to the steady-state motion of the microbeam, far from pull-in. The effects of different design parameters on dynamic behavior...
Size-dependent instability of carbon nanotubes under electrostatic actuation using nonlocal elasticity
, Article International Journal of Mechanical Sciences ; Vol. 80 , 2014 , pp. 144-152 ; ISSN: 00207403 ; Rastgoo, A ; Taghi Ahmadian, M ; Sharif University of Technology
2014
Abstract
In this paper, the classical and nonlocal elasticity are applied to investigate the deflection and instability of electrostatically actuated carbon nanotubes. The results are presented for different geometries and boundary conditions. They reveal that increasing radius and gap and decreasing length confine to increasing pull-in voltages of the carbon nanotubes. The results prove that application of the nonlocal elasticity theorem leads to stiffer structures with higher pull-in voltages. Thus, in order to obtain more accurate results about the mechanical and electromechanical behaviors of the carbon nanotubes, one should apply the nonclassical elasticity theories such as that applied in this...
Macro modeling of steel-concrete composite shear walls
, Article Structures ; Volume 23 , 2020 , Pages 383-406 ; Epackachi, S ; Taghi Kazemi, M ; Sharif University of Technology
Elsevier Ltd
2020
Abstract
To date, many researchers have developed various types of macro models to simulate the general response of conventional steel plate and reinforced concrete shear walls. Although extensive numerical and experimental studies have been conducted to assess the seismic response of steel-plate concrete composite shear walls, a robust macro-model for simulation of the cyclic response of such systems has not been developed yet. Herein, a fiber-based model is proposed to simulate the nonlinear seismic response of SC walls using PERFORM-3D program. The details of the proposed model, including material properties, element type, and boundary condition, are presented. The proposed model is validated...
Cyclic performance of composite shear walls with boundary elements
, Article Structures ; Volume 27 , 2020 , Pages 102-117 ; Epackachi, S ; Taghi Kazemi, M ; Sharif University of Technology
Elsevier Ltd
2020
Abstract
In the past three decades, several experiments were conducted to investigate the seismic behavior of composite plate shear walls (C-PSW) because of their advantages to conventional reinforced concrete (RC) and steel plate shear walls (SPSW). Numerical studies, however, are limited due to the complexities for the finite element modeling of the steel and concrete material behaviors and their composite action. Herein, the cyclic behavior of various C-PSW with and without boundary elements (BE) is investigated numerically. The effects of design parameters such as aspect ratio, axial load ratio, and the length of the BE on the response of C-PSW are investigated. The advanced finite element...
Data Transform Design in Smart oil Drilling Well
, M.Sc. Thesis Sharif University of Technology ; Ahmadian, Mohammad Taghi (Supervisor) ; Manzuri, Mohammad Taghi (Supervisor)
Abstract
In drilling oil well with respect to depth of several thousand meters, knowing the physical conditions of down-hole well such as temperature, pressure and stress have particular importance in prevention of possible injuries such as breaking the drill bit or increasing temperature. If these data can transfer from down-hole to bore-hole of the well, the operators can prevent from critical conditions such as intertangle of the drill-string. Currently, because of this lack of information, there are irreparable damages in oil industry annually. Based on researches, because of down-hole conditions of the well, these data can’t transfer with electromagnetic telemetry. Currently one of the data...
Transform of Downhole's Information to Acoustic Signals in Smart Drilling
, M.Sc. Thesis Sharif University of Technology ; Ahmadian, Mohammad Taghi (Supervisor) ; Manzuri, Mohammad Taghi (Supervisor)
Abstract
Drilling in oil industry, is an expensive process in produce and extract oil from well. Any mistake in drilling may cause many drawbacks for industry owners. Phisic’s quantities information at downhole like tempreture, pressure and force on bit synchronously can inform user from torrid conditions and prevent undesired events by actions like evoke bit from downhole or change at rotation velocity in drilling and finally stop operations. With attention to a lot of problems in data transport from long distance more than one kilometer from downhole, scientists believe that one of the methods to do this process is converting data gathered at the bottom hole to acoustic waves and transmit them to...
Automatic Highlight Detection in Football Videos using Audio and Video Information
, M.Sc. Thesis Sharif University of Technology ; Manzuri, Mohammad Taghi (Supervisor)
Abstract
Today, with the spread of various videos especially sports video and availability of them, the need for automated methods for search and retrieval of concepts from videos is strongly felt. On the other hand, summarizing video in order to making significant parts of them available is very important. One of the broadest scope that researchers have provided methods for extracting semantic concepts, is soccer videos. Often to extract high-level events, we need a definition and use of intermediate concepts. In this thesis "replay", "audio highlights" and "view type" are used to extract important events in the game. Here, two new methods are introduced for replay detection and view type...
Inferring Gene Regulatory Networks, Using Machine Learning Approaches
, M.Sc. Thesis Sharif University of Technology ; Manzuri, Mohammad Taghi (Supervisor)
Abstract
Gene regulatory network consists of a set of genes; interacting with each other via their protein products. Such interations lead to the regulation of the genes’ production rate. A breakdown in the regulatory process, may lead to some kinds of diseases. Therefore, understanding the gene regulatory process, is beneficial for both diagnosis and treatment. In this thesis, gene regulatory networks are modeled by the means of dynamic Bayesian networks. We have used sampling based methods, in order to learn the network structure. As these methos have a very high computational cost; we have used a correlation test to prune the search space. This way, an undirected network skeleton is obtained; for...
Change Point Estimation for Multistage Processes
, Ph.D. Dissertation Sharif University of Technology ; Akhavan Niaki, Taghi (Supervisor)
Abstract
Knowing the time of change would narrow the search to find and identify the variables disturbing a process. Having this information, an appropriate corrective action could be implemented and valuable time could be saved. Multistage processes that are often observed in current manufacturing processes must be monitored to assure quality products. The change-point detection of such processes has not been proposes investigated yet. Thus, this dissertation proposes maximum likelihood step-change estimators of two kinds of these processes. First, a multistage process with variable quality characteristics is considered and formulated by the first-order auto-regressive model. For the location...
Design and Analysis of a Cell Injection Manipulator Made of a Piezo-Driven Double-Deck Stewart Platform
, M.Sc. Thesis Sharif University of Technology ; Ahmadiyan, Mohammad Taghi (Supervisor)
Abstract
With respect to the introduction of bio-material into cells (transfection) , microinjection is a highly efficient technique amongst existing methodologies. In cell injection, a manipulator injects the needle into a cellwhich is hold by a pipet mechanism. The moving range for the needle in this operation is of centimeter order and the resolution for the needle tip should be less than the cell’s diameter. In this thesis a Stewart system is used as for the manipulator. Stewart systems are used in flight simulators systems for decades, as mechanisms which are capable of providing multi-axis movements. In high accuracy positioning and multi-axis applications Stewart systems are highly reliable....
Presenting a Framework for Evaluation of Knowledge Management Development Level in Inter-Organization Perspective
, M.Sc. Thesis Sharif University of Technology ; Isai, Mohammad Taghi (Supervisor)
Abstract
In accomplishment of knowledge management in real world, organization can be in different processes of awareness about importance of knowledge management and its achievements. Recognition of strength and weakness points of organization helps to logical planning and success in performance of knowledge management. For avoiding from failing in knowledge management projects, it is necessary that before stating for project performance, evaluate development level of organization from viewpoint of knowledge management, and determine some approaches for control of general problems of knowledge management, like abundance of information, work complexities, knowledge Storage.
In literature of...
In literature of...
Image Registration by Mapping Defined-Functions Around Regions of Interest
, M.Sc. Thesis Sharif University of Technology ; Manzuri, Mohammad Taghi (Supervisor)
Abstract
Image registration is the process of matching two or more images captured at different times, angles or even sensors. Image registration is finding a transformation between two images. Image registration has many applications in different fields of Image Processing and machine vision. In the field of remote sensing, image registration can be used for environmental monitoring, generating graphical maps and gathering data for geogeraphical information systems, also in the field of medical image processing it can be used to detect tumor growth. Generally whenever there is need to extract information from many images; image registration is considered as an important pre-processing step....
Direct Displacement Based Design of Steel Moment Resisting Frames and Comparison of Use in Building Codes
, M.Sc. Thesis Sharif University of Technology ; Kazemi, Mohammad Taghi (Supervisor)
Abstract
Recent research in the field of earthquake engineering has seen the development of a number of different displacement-based seismic design (DBD) methods. Such methods aim to overcome limitations with the force-based design methods incorporated in current codes, and the most developed DBD method currently available is the Direct DBD approach, presented by Priestley. The objective of this work is to investigate the performance of the Direct DBD design procedure for steel moment-resisting frame structures. For this purpose, a series of regular steel MRF frames, varying from 4 to 20 stories in height are designed based on DDBD approach and utilizing displacement design spectrum of the Iranian...
Numerical Simulation of Large Deformations in Impact to Composite Concrete-Steel Structures Using Coupled Damage-plasticity Model
, Ph.D. Dissertation Sharif University of Technology ; Kazemi, Mohammad Taghi (Supervisor)
Abstract
Concrete has long been considered by engineers as one of the most used constructional materials. Therefore, recognition of mechanical behavior of concrete materials is of particular importance. So, extensive studies have been undertaken to understand and analyze its behavior under different loading conditions. Based on these studies, many models for describing the behavior of concrete are presented. Of these, many models are based on the combination of plastic theory and damage mechanics, and by using them, significant success has been achieved in the correct modeling of concrete materials. On the other hand, one of the important loading conditions encountered by concrete structures is in...
Investigation of the Recovery Time and Hyper-Viscoelastic Properties of the Brain Tissue
, M.Sc. Thesis Sharif University of Technology ; Ahmadian, Mohammad Taghi (Supervisor)
Abstract
FE simulations have been widely used to investigate the response of the brain tissue in various circumstances. The accuracy of the material models critically affects the results of the numerical simulation. However, despite the numerous studies aiming for the material modeling of the brain, there is still divergence between the results reported in the literature. A part of this discrepancy is due to the inherent difference between samples. Nonetheless, another part of it is resulted from the differences between testing protocols used by researchers. In some protocols multiple mechanical tests are performed on each sample. Enough recovery time should be considered between consecutive test...
A Machine Learning and Time-Frequency Domain Combined Approach for Improving Stock Portfolio Management
, Ph.D. Dissertation Sharif University of Technology ; Manzuri, Mohammad Taghi (Supervisor)
Abstract
Price prediction in financial markets is an exciting problem for a vast majority of groups and people; however, investment portfolio managers and owners are always looking for holistic predic-tion approaches and tools having high functional accurate metrics. Strictly speaking, players in fi-nancial markets are always in search of methods and toolboxes since they need to overcome the un-certainty of their buy, sell, or hold decisions in order to reduce the investment risk. In this research, we have tried to deal with the stock price prediction problem as an asset pricing problem and find a novel approach to push forward the state-of-the-art of the problem based on the fundamental pric-ing...