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    Effect of CO2 partial pressure on the thermal decomposition kinetics of zinc carbonate hydroxide

    , Article International Journal of Engineering, Transactions B: Applications ; Volume 24, Issue 3 , 2011 , Pages 263-268 ; 1728-144X (ISSN) Pishahang, M ; Halali, M ; Nobari, A. H ; Sharif University of Technology
    2011
    Abstract
    In this work, the effect of carbon dioxide partial pressure on the calcination kinetics of high purity zinc carbonate hydroxide has been studied. Non-isothermal analysis has been performed on samples at different CO 2 partial pressures by TGA and DTA. It has been found that the calcination behaviour of this material corresponds to the shrinking core model and the reaction mechanism is phase boundary controlled. The calcination reaction of zinc carbonate hydroxide starts at 240 °C. Increasing the carbon dioxide partial pressure can result in an increase in the reaction start temperature of up to 30°C. The activation energy for the reaction is calculated as 180 ± 5 kJ/mol at... 

    Application of the modified reduced-order aerodynamics modelling approach to aeroelastic analysis

    , Article Proceedings of the Institution of Mechanical Engineers, Part G: Journal of Aerospace Engineering ; Volume 223, Issue 3 , 2009 , Pages 257-270 ; 09544100 (ISSN) Shahverdi, H ; Salehzadeh Nobari, A ; Haddadpour, H ; Behbahani Nejad, M ; Sharif University of Technology
    2009
    Abstract
    This study presents the application of the Proposed Modified Reduced-Order Aerodynamics Modelling approach for aeroelastic analysis based on the boundary element method (BEM) as a novel approach. The used BEM has the capability to capture the thickness effect and geometric complexity of a general three-dimensional model. In this approach the reduced-order aerodynamic model is defined through the eigenvalue problem of unsteady flow based on the unknown wake singularities. Based on the used aerodynamic model an explicit algebraic form of the aeroelastic equations is derived that reduces computational efforts and complexity. This special feature enables us to determine the aeroelastic... 

    Modeling of heat transfer during controlled cooling in hot rod rolling of carbon steels

    , Article Applied Thermal Engineering ; Volume 31, Issue 4 , 2011 , Pages 487-492 ; 13594311 (ISSN) Nobari, A. H ; Serajzadeh, S ; Sharif University of Technology
    2011
    Abstract
    A mathematical model is developed to predict temperature variations and austenite phase transformation kinetics in steel rods and wires during controlled cooling after hot rolling. Two-dimensional finite element analysis is employed to solve the governing heat conduction equation with non-uniform boundary conditions as it is subjected in practical cooling layout. The kinetics of austenite transformation is also determined using the cooling curves achieved from the thermal analysis together with the additivity rule. To verify the model results, temperature profiles in steel rods cooled under different conditions are measured experimentally in laboratory and also, temperature history during... 

    A study on microstructural changes and mechanical properties in steel rods subjected to uniform and non-uniform cooling layout using a finite element analysis

    , Article Proceedings of the Institution of Mechanical Engineers, Part B: Journal of Engineering Manufacture ; Volume 222, Issue 12 , 2008 , Pages 1639-1649 ; 09544054 (ISSN) Nobari, A. H ; Serajzadeh, S ; Sharif University of Technology
    2008
    Abstract
    This paper presents a mathematical model for prediction of temperature history, final microstructures, and transformation kinetics in steel rods subjected to non-uniform cooling conditions. To achieve this goal, a mathematical model based on two-dimensional finite element method is developed to solve the governing heat conduction equation with non-uniform boundary conditions. The additivity rule is coupled with the finite element analysis to assess the kinetics of austenite decomposition during continuous cooling. The effect of decarburization during heating stage is also considered in the model employing Fick's second equation. To verify the predictions, time-temperature histories during... 

    An investigation on the calcination kinetics of zinc carbonate hydroxide and Calsimin zinc carbonate concentrate

    , Article Chemical Engineering Journal ; Volume 121, Issue 2-3 , 2006 , Pages 79-84 ; 13858947 (ISSN) Nobari, A. H ; Halali, M ; Sharif University of Technology
    2006
    Abstract
    In this study the thermal calcination of two materials, high purity zinc carbonate hydroxide and the Calsimin zinc carbonate concentrate have been investigated. Isothermal studies have been performed on samples at different temperatures and times. Non-isothermal analysis has been carried out by TGA and DSC. It has been found that the calcination behaviour of both materials corresponds to the shrinking core model. The activation energy for the calcination of zinc carbonate hydroxide is found to be 88.7 kJ/mol, and that for the Calsimin sample is 97.3 kJ/mol. © 2006 Elsevier B.V. All rights reserved  

    A new mixed fuzzy-LP method for selecting the best supplier using fuzzy group decision making

    , Article Neural Computing and Applications ; Volume 23, Issue SUPPL1 , 2013 , Pages 345-352 ; 09410643 (ISSN) Sepehriar, A ; Eslamipoor, R ; Nobari, A ; Sharif University of Technology
    2013
    Abstract
    Even though there have been so many articles and studies that focused on the supplier selection problem, a few of them considered the major decisions related to supplier selection. In this paper, the supplier selection problem is studied under a novel fuzzy approach in multiple sourcing conditions to select appropriate supplier in group decision-making environment regarding multiple sources. The use of the model is suitable in evaluating situations that involve subjectivity, vagueness and imprecise information. The group data have been used in multiple criteria decision making with multiple objective supplier selection. Trapezoidal fuzzy numbers are applied to evaluate the weights of... 

    Aeroelasticity consideration of supersonic vehicle using closed form analytical aerodynamic model

    , Article Aircraft Engineering and Aerospace Technology ; Volume 81, Issue 2 , 2009 , Pages 128-136 ; 00022667 (ISSN) Fathi Jegarkandi, M ; Salezadeh Nobari, A ; Mahdi, S ; Hassan, H ; Farhad, T ; Sharif University of Technology
    2009
    Abstract
    Purpose - The purpose of this paper is to investigate the aeroelastic behavior of a supersonic flight vehicle flying at moderate angles of attack using global analytic nonlinear aerodynamic model. Design/methodology/approach - Aeroelastic behavior of a supersonic flight vehicle flying at moderate angles of attack is considered, using nonlinear aerodynamics and linear elastodynamics and structural models. Normal force distribution coefficient over the length of the vehicle and pitching moment coefficient are the main aerodynamic parameters used in the aeroelastic modeling. It is very important to have closed form analytical relations for these coefficients in the model. They are generated... 

    Nonlinear control of multiple equilibrium systems and unknown sinusoidal disturbance by using backstepping technique and neural-fuzzy controller

    , Article ASME 2007 International Mechanical Engineering Congress and Exposition, IMECE 2007, 11 November 2007 through 15 November 2007 ; Volume 9 , 2007 , Pages 415-422 ; 0791843033 (ISBN) Abolfathi Nobari, N ; Alizadeh, D ; Sharif University of Technology
    American Society of Mechanical Engineers (ASME)  2007
    Abstract
    Controlling nonlinear systems have always been a challenging problem. Complexity is mostly the result of nonlinear systems behavior dependence on initial conditions and input. Linearization techniques are such kinds of nonlinear systems analysis tools, which can give suitable results in neighborhood of equilibrium points. In addition, phase portraits are very efficient for visualizing the behavior of system in equilibrium points' neighborhood. In this paper, designing a controller for a low order dynamic system with multiple equilibrium points in presence of a sinusoidal disturbance with unknown amplitude and unknown bounded frequency is investigated. The proposed controller is based on a... 

    Design and Implementation of Software Fault-Tolerance Techniques for an Embedded Processor

    , M.Sc. Thesis Sharif University of Technology Bazzaz Nobari Asl, Mostafa (Author) ; Ejlali, Alireza (Supervisor)
    Abstract
    Nowadays embedded system play an important role in human life. The majority of these systems work in harsh environments which intensifies the importance of fault tolerance in embedded systems. This capability is usually achieved by adding redundancy to the system. But common embedded systems are weaker than desktop and server systems and probably have a limited source of power which makes the redundancies expensive. Hardware fault tolerant techniques impose significant cost to system and increase the development time which makes software-only solutions more attractive. An important general purpose software-only technique in protecting the application data is EDDI. This technique is based on... 

    Power Management in Real-Time Embedded Systems Using Non-Volatile Memories

    , Ph.D. Dissertation Sharif University of Technology Bazzaz Nobari Asl, Mostafa (Author) ; Ejlali, Alireza (Supervisor)
    Abstract
    Real-time embedded systems play an important role in many areas of human life and energy consumption is an important constraint in their design. In these systems, SRAM-based on-chip scratchpad memories are used for holding code or data which suffer from high leakage power and low capacity per transistor. This has persuaded researchers to find alternative solutions and in recent years non-volatile memories have attracted a lot of attention. Compared to conventional memories like SRAM, non-volatile memories consume less leakage power and provide more capacity given the same number of transistors. In this dissertation, we propose new solutions for reducing the energy consumption of real-time... 

    A Nonlinear Transmission Line Model for the Relativistic Magnetron

    , M.Sc. Thesis Sharif University of Technology Heyrani Nobari, Ali (Author) ; Farzaneh, Forouhar (Supervisor) ; Hashemi, Morad Ali (Co-Supervisor)
    Abstract
    Magnetron is one of the microwave-generating devices that operates based on the microwave-electron flow interaction in the active region of the tube, which is affected by the resonant cavities and It is used in a wide range of power (from kW range at home microwave ovens to several GW in relativistic high power magnetrons and the frequencies from the order of few too MHz to tens of GHz). Although nowday's low-power generators based on transistors have replaced microwave generating tubes and even MW radio transmitters are made based on the combination of semiconductor microwave generators, but in the production of RF pulses at higher frequencies and powers, the electron tubes are the main... 

    Introducing a New Boundary Condition Method in Dissipative Particle Dynamics and Simulation of Dilute Polymer Solution

    , M.Sc. Thesis Sharif University of Technology Nobari, Babak (Author) ; Saidi, Mohammad Saeid (Supervisor) ; Saidi, Mohammad Hassan (Supervisor) ; Shafiee, Mohammad Behshad (Supervisor)
    Abstract
    Dissipative particle dynamics (DPD) is an emerging mesoscopic computational method in which the interparticle forces arise because of coarse-graining at the molecular level. In the asymptotic limit of large length scales, the governing equations of continuum are reproduced, as demonstrated in this work. This method of simulation has the capability of simulating larger order of time and space in compare with dynamic molecular method. One of the important applications of DPD is simulating the dilute polymer solution. In this project, we developed a general code to simulate dilute polymer behavior which consists of polymeric forces and different types of usual DPD boundary conditions. This code... 

    Low SNR regime capacity analysis of MIMO systems using directional antennas

    , Article 2008 International Symposium on Telecommunications, IST 2008, Tehran, 27 August 2008 through 28 August 2008 ; 2008 , Pages 393-398 ; 9781424427512 (ISBN) Shariatpanahi, P ; Shishegar, A. A ; Khalaj, B. H ; Salavati, A. H ; Saligheh Rad, H. R ; Sharif University of Technology
    2008
    Abstract
    In this paper, we evaluate the capacity of Multiple-Input Multiple-Output (MIMO) systems using directional antennas in non-isotropic scattering environments. Our analytical analysis approach results in closed-form approximate formulas in low Signal to Noise Ratio (SNR) regime (in contrast to previous research works which have investigated the same problem by employing experimental or simulation frameworks). We propose an upper bound for the introduced approximate error. Our results show that MIMO systems equipped with directional antennas may have much higher capacity in nonisotropic scattering environments compared to MIMO systems equipped with omni-directional antennas. We also evaluate... 

    Multi-objective dynamic cell formation problem: A stochastic programming approach

    , Article Computers and Industrial Engineering ; Volume 98 , 2016 , Pages 323-332 ; 03608352 (ISSN) Zohrevand, A. M ; Rafiei, H ; Zohrevand, A. H ; Sharif University of Technology
    Elsevier Ltd  2016
    Abstract
    This paper addresses dynamic cell formation problem (DCFP) which has been explored vastly for several years. Although a considerable body of literature in this filed, two remarkable aspects have been significantly ignored so far, as uncertainty and human-related issues. In order to compensate such a shortage, this paper develops a bi-objective stochastic model. The first objective function of the developed model seeks to minimize total cost of machine procurement, machine relocation, inter-cell moves, overtime utilization, worker hiring/laying-off, and worker moves between cells; while the second objective function maximizes labor utilization of the cellular manufacturing system. In the... 

    On the performance of trace locality of reference

    , Article Performance Evaluation ; Volume 60, Issue 1-4 , 2005 , Pages 51-72 ; 01665316 (ISSN) Mahjur, A ; Jahangir, A. H ; Gholamipour, A. H ; Sharif University of Technology
    Elsevier  2005
    Abstract
    In this paper, trace locality of reference (LoR) is identified as a mechanism to predict the behavior of a variety of systems. If two objects were accessed nearby in the past and the first one is accessed again, trace LoR predicts that the second one will be accessed in near future. To capture trace LoR, trace graph is introduced. Although trace LoR can be observed in a variety of systems, but the focus of this paper is to characterize it for data accesses in memory management systems. In this field, it is compared with recency-based prediction (LRU stack) and it is shown that not only the model is much simpler, but also it outperforms recency-based prediction in all cases. The paper... 

    Letter to “a contribution to the understanding of isothermal diesel spray dynamics”

    , Article Fuel ; Volume 187 , 2017 , Pages 468-469 ; 00162361 (ISSN) Ghahremani, A. R ; Karimi, H ; Saidi, M. H ; Mozafari, A. A ; Sharif University of Technology
    2017

    Whole-genome analysis of de novo somatic point mutations reveals novel mutational biomarkers in pancreatic cancer

    , Article Cancers ; Volume 13, Issue 17 , 2021 ; 20726694 (ISSN) Ghareyazi, A ; Mohseni, A ; Dashti, H ; Beheshti, A ; Dehzangi, A ; Rabiee, H. R ; Alinejad Rokny, H ; Sharif University of Technology
    MDPI  2021
    Abstract
    It is now known that at least 10% of samples with pancreatic cancers (PC) contain a causative mutation in the known susceptibility genes, suggesting the importance of identifying cancer-associated genes that carry the causative mutations in high-risk individuals for early detection of PC. In this study, we develop a statistical pipeline using a new concept, called gene-motif, that utilizes both mutated genes and mutational processes to identify 4211 3-nucleotide PC-associated gene-motifs within 203 significantly mutated genes in PC. Using these gene-motifs as distinguishable features for pancreatic cancer subtyping results in identifying five PC subtypes with distinguishable phenotypes and... 

    A method for evaluation and mitigation of AC induced voltage on buried gas pipelines

    , Article Scientia Iranica ; Volume 9, Issue 4 , 2002 , Pages 311-320 ; 10263098 (ISSN) Vakilian, M ; Valadkhani, K ; Shaigan, A. A ; Nasiri, A. H ; Gharagozlo, H ; Sharif University of Technology
    Sharif University of Technology  2002
    Abstract
    This paper has been prepared, based on reports regarding extraordinary induced ac voltage on buried gas pipelines in residential and industrial areas of the capital city of Tehran, especially in densely populated central areas. Also, some reports are considered on the existence of ac induced voltage in buried gas pipelines under the overhead transmission lines, for example, one case located 80 Km to the west of Tehran, in an agricultural region of the town of Abyek. In this paper, the results of an extensive theoretical, experimental and practical investigation and implementation of methods carried out during the last two years are introduced. Furthermore, this paper includes evaluation of... 

    Multi-objective optimization of lean and sweep angles for stator and rotor blades of an axial turbine

    , Article Proceedings of the Institution of Mechanical Engineers, Part G: Journal of Aerospace Engineering ; Volume 229, Issue 5 , June , 2015 , Pages 906-916 ; 09544100 (ISSN) Asgarshamsi, A ; Benisi, A. H ; Assempour, A ; Pourfarzaneh, H ; Sharif University of Technology
    SAGE Publications Ltd  2015
    Abstract
    The axial turbine is one of the most challenging components of gas turbines for industrial and aerospace applications. With the ever-increasing requirement for high-aerodynamic performance blades, three-dimensional aerodynamic shape optimization is of great importance. In this research, the rear part of a gas turbine consisting of a one-stage axial turbine is optimized numerically. A useful optimization algorithm is presented to improve the efficiency and/or pressure ratio of the axial turbine with two different objective functions. The three-dimensional blade-shape optimization is employed to study the effects of the turbine stator and rotor lean and sweep angles on the turbine performance.... 

    Microstructural evolution and mechanical properties of semisolid stir welded zinc AG40A die cast alloy

    , Article Journal of Materials Processing Technology ; Volume 209, Issue 8 , 2009 , Pages 4112-4121 ; 09240136 (ISSN) Narimannezhad, A ; Aashuri, H ; Kokabi, A. H ; Khosravani, A ; Sharif University of Technology
    2009
    Abstract
    A high quality joint of zinc based pressure die cast alloys can be hardly achieved by conventional fusion welding. In this study, a novel technique to achieve the globular weld structure using stirring the localized semisolid zone during butt joining of Zamak-3 pressure die cast alloy is proposed and effect of welding parameters on mechanical and microstructural properties are investigated. A gas heating system was designed to heat up the nitrogen gas to desired temperature accurately to create a localized semisolid pool. At this stage a fine stirrer was introduced into the weld seam in order to mix the two sides into a single uniform joint. By presented process, globular microstructure of...