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alavi-dehkordi--e
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Hydromagnetic micropump and flow controller. part a: experiments with nickel particles added to the water
, Article Experimental Thermal and Fluid Science ; Volume 33, Issue 6 , 2009 , Pages 1021-1028 ; 08941777 (ISSN) ; Shafii, M. B ; Alavi Dehkordi, E ; Sharif University of Technology
2009
Abstract
The novel idea of the Hydromagnetic Micropump and Flow Controller (HMFC) is used in this paper to construct a laboratory setup capable of bidirectional pumping and controlling the flow in microtubes. A laboratory setup, which contains no moving parts, is integrated with a pressure-driven flow setup to make the presented HMFC device. The device operation is based on controllable motion of magnetic particles, added to the carrier fluid, caused by the magnetic field, produced by solenoids located just next to the microtube. The magnitude of these forces is proportional to the strength and gradient of magnetic field which, in turn, is related to the electrical current and arrangement of the...
A novel hydro magnetic micro-pump and flow controller
, Article 6th International Conference on Nanochannels, Microchannels, and Minichannels, ICNMM2008, Darmstadt, 23 June 2008 through 25 June 2008 ; Issue PART B , June , 2008 , Pages 1537-1544 ; 0791848345 (ISBN); 9780791848340 (ISBN) ; Esmaily Moghadam, M ; Shafii, M. B ; ASME ; Sharif University of Technology
2008
Abstract
In order to deal with the limitations of micro-pumps and micro-valves and meet the advantages of magnetic systems a novel plan is described here. The idea behind the plan is that magnetic particles, mixed and dispersed in a carrier liquid, can be accumulated and retained at specific sites to form pistons in a micro-tube using some external magnetic field sources along the tube. In other words, using some solenoids and switching them on and off, in a specific order and period, causes the desired external magnetic field variation through the tube. Changing the period and the mode of activation and deactivation of the solenoids, which are called switching time and switching mode, respectively,...
Magnetic nanofluidic electrolyte for enhancing the performance of polysulfide/iodide redox flow batteries
, Article Electrochimica Acta ; Volume 369 , 2021 ; 00134686 (ISSN) ; Molaei Dehkordi, A ; Roberts, E. P. L ; Sharif University of Technology
Elsevier Ltd
2021
Abstract
In this article, the novel concept of using magnetic nanofluidic electrolyte for redox flow batteries is demonstrated for the first time. In this regard, the stable magnetic nanofluidic electrolytes are prepared by dispersing magnetic modified multiwalled carbon nanotubes (MMWCNTs) in the positive electrolyte of a polysulfide-iodide redox flow battery at mass concentrations of less than 0.3 g L−1. The electrochemical behavior of magnetic nanofluidic electrolyte was examined using cyclic voltammetry at different mass concentrations of MMWCNTs with a carbon felt electrode. Higher and stable peak current densities were observed at larger mass concentrations of MMWCNTs. A polysulfide-iodide...
The level set modeling of droplet dynamic in fluid-fluid interaction
, Article 39th AIAA Fluid Dynamics Conference, 22 June 2009 through 25 June 2009, San Antonio, TX ; 2009 ; 9781563479755 (ISBN) ; Mazaheri, I ; Dehkordi, A. M ; Schneider, G. E ; Sharif University of Technology
2009
Abstract
In this work, we present a level set method to simulate steady and unsteady mass transfer from a single droplet moving in a second phase fluid under buoyant force. We initially use level set to determine the interface between the two phases, where the shape of drop forms. Next, we extend this method to solve a unique mass transfer equation for the entire solution domain without considering the discontinuity appeared at the interface. We use a finite element method incorporated with the characteristic-based split (CBS) algorithm to implement axi-symmetric mass transfer equations on a stationary Eulerian grid. Of course, the convection-diffusion modeling of mass transfer is different from the...
Utilization of hydrogen in gas turbines: a comprehensive review
, Article International Journal of Low-Carbon Technologies ; Volume 17 , 2022 , Pages 513-519 ; 17481317 (ISSN) ; Fahim Alavi, M ; Salem, M ; Assad, M. E. H ; Sharif University of Technology
Oxford University Press
2022
Abstract
The concerns regarding the consumption of traditional fuels such as oil and coal have driven the proposals for several cleaner alternatives in recent years. Hydrogen energy is one of the most attractive alternatives for the currently used fossil fuels with several superiorities, such as zero-emission and high energy content. Hydrogen has numerous advantages compared to conventional fuels and, as such, has been employed in gas turbines (GTs) in recent years. The main benefit of using hydrogen in power generation with the GT is the considerably lower emission of greenhouse gases. The performance of the GTs using hydrogen as a fuel is influenced by several factors, including the performance of...
Novel magnetic flowable electrode for redox flow batteries: A polysulfide/iodide case study
, Article Industrial and Engineering Chemistry Research ; Volume 60, Issue 2 , 2021 , Pages 824-841 ; 08885885 (ISSN) ; Molaei Dehkordi, A ; Gharibi, H ; Roberts, E. P. L ; Sharif University of Technology
American Chemical Society
2021
Abstract
A novel approach named a magnetic flowable electrode (MFE) is proposed for the first time to enable enhancement of redox flow batteries (RFBs) performance. This approach enables the formation of a high active surface area electrode from magnetic nanomaterials, without the need to fabricate a self-supporting three-dimensional electrode structure. To form a simple MFE, magnetic modified carbon nanotubes are dispersed in the electrolyte, and permanent magnets are embedded behind the current feeder to apply a magnetic field across the flow cell channels. With circulating electrolyte, magnetic carbon nanotubes are aggregated on the graphite bipolar plate to form a well-structured nanoscale...
Hour-ahead demand forecasting in smart grid using support vector regression (SVR)
, Article International Transactions on Electrical Energy Systems ; Vol. 24, issue. 12 , 2014 , p. 1650-1663 ; Fereidunian A ; Gholami-Dehkordi H ; Lesani H ; Sharif University of Technology
2014
Abstract
Demand forecasting plays an important role as a decision support tool in power system management, especially in smart grid and liberalized power market. In this paper, a demand forecasting method is presented by using support vector regression (SVR). The proposed method is applied to practical hourly data of the Greater Tehran Electricity Distribution Company. The SVR parameters are selected by using a grid optimization process and an investigation on different kernel functions. Moreover, correlation analysis is used to find exogenous variables. Acceptable accuracy of load prediction is shown by comparing the result of SVR model to that of the artificial neural networks and the actual data,...
Using nucleators to control freckles in unidirectional solidification
, Article Experimental Thermal and Fluid Science ; Volume 33, Issue 8 , 2009 , Pages 1209-1215 ; 08941777 (ISSN) ; Alavi Dehkordi, E ; Esmaily Moghadam, M ; Mohseni Koochesfahani, M ; Sharif University of Technology
2009
Abstract
Buoyancy-induced fluid flow, which is responsible for most forms of macro-segregation and channel-type segregates in castings, is not directly controllable. If left uncontrolled, natural convection will contribute to non-uniform distribution of alloy constituents and grain structure during solidification of a casting. Non-uniform distribution of chemical composition and physical structure in an alloy casting can significantly affect the reliability of mechanical components. Therefore, materials with acceptable defects can be produced only by trial-and-error and their acceptability is determined by costly inspections. We present a novel technique to control the formation of chimneys and...
Modeling carbon dioxide emission of countries in southeast of Asia by applying artificial neural network
, Article International Journal of Low-Carbon Technologies ; Volume 17 , 2022 , Pages 321-326 ; 17481317 (ISSN) ; Fahim Alavi, M ; Salem, M ; Assad, M. E. H ; Prabaharan, N ; Sharif University of Technology
Oxford University Press
2022
Abstract
Energy and economy play a substantial role in environmental issues such as the emission of greenhouse gases. CO2 is one of the greenhouses that is hugely produced in industrial processes and other human being activities. The major share of CO2 emission is related to the energy-related activities. As a result, modeling the amount of produced CO2 by utilization of different energy sources must be considered. Moreover, by considering economic indicators such as gross domestic product, the accuracy of the model could be improved. In the present work, artificial neural network (ANN) with two transfer functions including normalized radial basis and tansig is used to model CO2 production of...
Microstructural changes during static recrystallization of austenitic stainless steel 304l: cellular automata simulation
, Article Metallography, Microstructure, and Analysis ; Volume 9, Issue 2 , 2020 , Pages 223-238 ; Serajzadeh, S ; Sharif University of Technology
Springer
2020
Abstract
Static recrystallization and microstructural changes in austenitic stainless steel 304L were studied. The rolling experiments at 200 °C were carried out, and then, annealing treatment was made at temperatures ranging between 500 and 830 °C. A model was also developed to simulate the kinetics of non-isothermal recrystallization within the rolled steel. The distribution of plastic strains during rolling was predicted utilizing an elastic–plastic finite element formulation performed in ABAQUS/Explicit, while the predicted results were used to generate the as-rolled microstructure and to estimate the stored energy. Finally, microstructural–thermal model based on cellular automata was developed...
Simulation of recrystallization and martensite revision in 304L austenitic stainless steel after multi-pass rolling processes
, Article Multiscale and Multidisciplinary Modeling, Experiments and Design ; Volume 3, Issue 4 , 2020 , Pages 227-244 ; Serajzadeh, S ; Sharif University of Technology
Springer Science and Business Media B.V
2020
Abstract
In this work, non-isothermal annealing of cold-rolled 304L austenitic stainless steel was studied at temperatures ranging between 400 and 800 °C. In the first place, a dual-phase structure containing work-hardened austenite and strain-induced martensite was produced by means of multi-pass plate rolling, and then, the deformed steel was subjected to annealing heat treatments. To determine the distribution of stored strain energy in the rolling operations, an elastic–plastic finite-element modeling was conducted. Afterwards, an artificial neural network technique was coupled with the thermal-cellular automata model for prediction of martensite reversion, temperature history, and...
Measurement of vertical and horizontal idiocentrism and allocentrism in small groups
, Article Small Group Research ; Volume 38, Issue 4 , 2007 , Pages 556-564 ; 10464964 (ISSN) ; McCormick, J ; Sharif University of Technology
2007
Abstract
A new conceptual framework of collective orientation in team contexts has recently been proposed in terms of vertical and horizontal dimensions of idiocentrism and allocentrism. A two-phase longitudinal study of 270 university students engaged in 86 academic groups partly confirmed the conceptualization by identifying four interpretable factors: vertical and horizontal idiocentrism, horizontal allocentrism, and avoiding arguments. The results of exploratory and confirmatory factor analyses and a structural model of relationships between the four dimensions in both phases of the study are reported in this article. © 2007 Sage Publications
Self-Leadership Strategies in Teamwork and Share Leadership Orientation with the Mediating Effect of Self-Efficacy
, M.Sc. Thesis Sharif University of Technology ; Alavi, Babak (Supervisor)
Abstract
The main purpose of this study is to evaluate the linkage between two constructs about teamwork activities. One of them is "self-leadership in teamwork", the extent to which a person could control and manage his thoughts and activities in teamwork. The other is "shared leadership orientation", which is about orientation of people to contribute in leadership processes. This linkage evaluated with consideration of "self-efficacy in shared leadership" as a moderator.
Questionnaires of self-leadership in teamwork and self-efficacy in shared leadership elicited from literature with a little change and shared leadership questionnaire developed in another study by the author.Questionnaires...
Questionnaires of self-leadership in teamwork and self-efficacy in shared leadership elicited from literature with a little change and shared leadership questionnaire developed in another study by the author.Questionnaires...
The Hidden Side of Coin: What Self Leadership Strategies Are Applied by Successful Iranian Women Entrepreneurs?
, M.Sc. Thesis Sharif University of Technology ; Alavi, Babak (Supervisor)
Abstract
Women are going to play more important roles in the economy of most countries including Iran. Hence, since the number of entrepreneurs among women is increasing, identifying characteristics and other factors that cause these group to be successful, is a critical issue. Studies show that entrepreneurs, especially women entrepreneurs, face numerous problems in their career. These problems are especially more demanding in societies with unique cultural attributes. Therefore, applying personal and managerial solutions in order to overcome these problems are necessary. On the other hand, researchers believe that one of the most effective and beneficial concepts helping entrepreneurs in their...
A Model for Hierarchical Production Planning in a Make-to-order System
,
M.Sc. Thesis
Sharif University of Technology
;
Kianfar, Farhad
(Supervisor)
Abstract
A hierarchical production system in make-to-order environment is presented in this thesis. This production system is consisted of three different decision making levels. Maximum acceptance for production within customer specified time interval was done in the first stage, which is called order arriving stage, based on different client criteria, type of demanded product, and production system constraints. A new hierarchical decision making structure for accepting or rejecting arriving orders is proposed in this level. The output of this acceptance level is orders having maximum production system defined criteria, and minimum production cost along with order delivery time with minimum delay is...
Identifying the Ethical Dilemmas Confronting Human Resource Managers of Iranian Project Based Companies and Exploring their Causes
, M.Sc. Thesis Sharif University of Technology ; Alavi, Babak (Supervisor)
Abstract
The present study was performed aiming to identify the ethical dilemmas human resource managers confront with in Iranian project-based organizations as well as to trace out the underlying causes. “Ethical dilemma” refers to a decision making situation in which ethical considerations render all the alternatives inapt, thence making the decision making process ethically complex. First of all, a theoretical framework was developed based on the preceding research; then, the study was further conducted utilizing a qualitative research method with an exploratory approach. The data were collected using in-depth interviews and analysed using the theme analysis method. The corresponding interviewees...
Multiple Case Study of Distributed Leadership Effectiveness in Educational Major FoundingTeams of Sharif University of Technology
,
M.Sc. Thesis
Sharif University of Technology
;
Alavi, Babak
(Supervisor)
Abstract
Using Distributed leadership framework while studying the leadership phenomena in teams, especially in educational environment, has received more attention by scholars in these years. Although the results of these researches indicated positive consequences mostly, the need for exploratory studies to identify situational and contextual factors in distributed leadership effectiveness has been mentioned. In other words, it has been suggested that the effectiveness of distributed leadership in teams may be affected by situational and contextual factors. In the current multiple case study, after the initial study of leadership and its functions in some schools of Sharif University of Technology,...
Identification of Influence Mechanisms of Executive/non-executive Board Composition on Board’s Attribution Style
, M.Sc. Thesis Sharif University of Technology ; Alavi, Babak (Supervisor)
Abstract
The influence mechanisms of executive/non-executive board compostion on board’s attribution style have been explored. In two case studies, I have examined boards’ causal interpretation about a critical incident which had a significant impact on firm performance. A qualitative research approach has been taken in the case studies. Data was gathered through semi-structured interviews with all board members and was analyzied with the theme analysis method. According to the results, board of directors’ collective attribution formation process can be devided into three stages of members’ expression of information and facts at board meetings, forming the individual judgements of members and at...
Establishment of ISO/TS 16949:2002 Standard and Combining with Sapco 86 and AR/8601 Saipa Sazeh Gostar Requirements in Auto Parts Manufacturing Company
, M.Sc. Thesis Sharif University of Technology ; Hajji, Rasoul (Supervisor)
Abstract
The quality is the last word of customer satisfaction concept. The structure and the main goal of many of large and small companies have been formed with systems aggregate related to process and product quality. Whereas quality is not achieved only under the protection of inspecting and controlling, then the quality management standards have been designed and produced to control all the activities and organization effective processes. Quality management standards in auto industries have been developed with increasing of customer desire and their severity simultaneously. Which the set of some standards such as ISO 9000, QS 9000, VDA, … and the most ISO TS 16949 requirements have been used....
A Study on Relationships between Career Anchors and Career Orientations
, M.Sc. Thesis Sharif University of Technology ; Alavi, Babak (Supervisor)
Abstract
Career Orientations or career choices, can be affected by internal and external factors. External factors are the environmental conditions that the reward and the attractiveness of selecting a career choice are dependent to them. Internal factors include the needs of oneself from his/her job, his/her beliefs and his/her skills and competencies about the job. In this research the internal antecedents of managerial and technical orientations between programmers have been identified. On the other hand the perception of people about the compensation system as an external factor which can affect the mentioned relationships, have been analyzed. It seems that this is the first research which career...