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    Development of thermo-elastic tapered and spherical superelements

    , Article Applied Mathematics and Computation ; Volume 265 , 2015 , Pages 380-399 ; 00963003 (ISSN) Shamloofard, M ; Movahhedy, M. R ; Sharif University of Technology
    Elsevier Inc  2015
    Abstract
    Special superelements are often used to improve the computational efficiency and improve accuracy of finite element modeling. Structures with tapered and spherical geometry exist in many engineering problems. In this work, special tapered and spherical superelements are presented that can be used for modeling of tapered and spherical bodies in thermo mechanical analyses with computational efficiency. The performance of these superelements under thermal and structural loads is demonstrated by presenting several examples and comparing the results with those from conventional 3D brick elements, which shows high accuracy at reduced computational cost  

    Development of a shell superelement for large deformation and free vibration analysis of composite spherical shells

    , Article Engineering with Computers ; 2020 Shamloofard, M ; Hosseinzadeh, A ; Movahhedy, M. R ; Sharif University of Technology
    Springer  2020
    Abstract
    Finite element analysis of huge and/or complicated structures often requires long times and large computational expenses. Superelements are huge elements that exploit the deformation theory of a specific problem to provide the capability of discretizing the problem with minimum number of elements. They are employed to reduce the computational cost while retaining the accuracy of results in FEM analysis of engineering problems. In this research, a new shell superelement is presented to study linear/nonlinear static and free vibration analysis of spherical structures with partial or full spherical geometries that exist in many industrial applications. Furthermore, this study investigates the... 

    Mesoporous nanostructures of NiCo-LDH/ZnCo2O4 as an efficient electrocatalyst for oxygen evolution reaction

    , Article Journal of Colloid and Interface Science ; Volume 604 , 2021 , Pages 832-843 ; 00219797 (ISSN) Shamloofard, M ; Shahrokhian, S ; Amini, M. K ; Sharif University of Technology
    Academic Press Inc  2021
    Abstract
    Increasing energy demands for pollution-free and renewable energy technologies have stimulated intense research on the development of inexpensive, highly efficient, and stable non-noble metal electrocatalysts for oxygen evolution reaction (OER). In this study, a superior OER performance was achieved using a tri-metallic (Zn, Co, Ni) high-performance electrocatalyst. We successfully fabricated a peony-flower-like hierarchical ZnCo2O4 through an additive-free hydrothermal reaction followed by heat treatment. Then NiCo-LDH (layered double hydroxides) nano-flakes was electrodeposited on the ZnCo2O4/GCE surface to prepare NiCo-LDH/ZnCo2O4/GCE which was used as electrode for OER. The structure and... 

    Development of a shell superelement for large deformation and free vibration analysis of composite spherical shells

    , Article Engineering with Computers ; Volume 37, Issue 4 , 2021 , Pages 3551-3567 ; 01770667 (ISSN) Shamloofard, M ; Hosseinzadeh, A ; Movahhedy, M. R ; Sharif University of Technology
    Springer Science and Business Media Deutschland GmbH  2021
    Abstract
    Finite element analysis of huge and/or complicated structures often requires long times and large computational expenses. Superelements are huge elements that exploit the deformation theory of a specific problem to provide the capability of discretizing the problem with minimum number of elements. They are employed to reduce the computational cost while retaining the accuracy of results in FEM analysis of engineering problems. In this research, a new shell superelement is presented to study linear/nonlinear static and free vibration analysis of spherical structures with partial or full spherical geometries that exist in many industrial applications. Furthermore, this study investigates the... 

    Electrochemical Sensors Based on Electrodes Modified with Composites of Carbon Nanostructures and Polypyrrole; Application to Electrochemical Investigations and Determination of Nifedipine and Tizanidine

    , M.Sc. Thesis Sharif University of Technology Shamloofard, Maryam (Author) ; Shahrokhian, Saeed (Supervisor)
    Abstract
    In the first part, the electropolymerization of pyrrole was performed in the presence of Titan Yellow (TY) as a dopant anion on the surface of the electrode precoated with CNTs. The modified electrode was used to study the voltammetric response of tizanidine (TIZ). A remarkable increase was observed in the anodic peak current of TIZ on the surface of the modified electrode relative to the bare GCE. The surface morphology PPY/CNT/GCE was thoroughly characterized by scanning electron microscopy (SEM) and cyclic voltammetry (CV) techniques. Under the optimized analysis conditions, the modified electrode showed two linear dynamic ranges of 0.01 - 1 μM and 1-10 μM with a detection limit of 3 nM... 

    Development of an inverse isogeometric methodology and its application in sheet metal forming process

    , Article Applied Mathematical Modelling ; Volume 73 , 2019 , Pages 266-284 ; 0307904X (ISSN) Shamloofard, M ; Assempour, A ; Sharif University of Technology
    Elsevier Inc  2019
    Abstract
    This paper proposes an inverse isogeometric analysis to estimate the blank and predict the strain distribution in sheet metal forming processes. In this study, the same NURBS basis functions are used for drawing a final part and analysis of the forming process. In other words, this approach requires only one modeling and analysis representation, in contrast to inverse FEM. This model deals with minimization of potential energy, deformation theory of plasticity, and infinitesimal deformation relations with considering a new non-uniform friction model. One advantage of the presented methodology is that the governing equations are solved in two-dimensional space without concerning about... 

    Investigation of Electrocatalytic Behavior of Some Transition Metal Oxides, Sulfides and Phosphides Nanostructures Toward Electrochemical Water Splitting

    , M.Sc. Thesis Sharif University of Technology Shamloofard, Maryam (Author) ; Shahrokhian, Saeed (Supervisor)
    Abstract
    Energy and the environment issues are among the most important concerns of the present age. Global demand for energy is growing rapidly and energy demand is projected to double in the coming years. However, today most of the energy consumption comes from fossil fuels, which have limited and unstable reserves and are among the sources of environmental pollution. Hence, the production and conversion of clean energy from renewable sources is considered as an intelligent solution to significantly reduce dependence on fossil fuels and protect the environment. Fuel cells, metal-air batteries, and water electrolysis are among the simplest, most efficient, and most reliable technologies among... 

    Dual-electrocatalysis behavior of star-like zinc-cobalt-sulfide decorated with cobalt-molybdenum-phosphide in hydrogen and oxygen evolution reactions

    , Article Nanoscale ; Volume 13, Issue 41 , 2021 , Pages 17576-17591 ; 20403364 (ISSN) Shamloofard, M ; Shahrokhian, S ; Sharif University of Technology
    Royal Society of Chemistry  2021
    Abstract
    Although important advances have been acquired in the field of electrocatalysis, the design and fabrication of highly efficient and stable non-noble earth-abundant metal catalysts for the oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) remain a significant challenge. In this study, we have designed a superior bifunctional catalyst for OER and HER in alkaline media based on the Co-Mo-P/Zn-Co-S multicomponent heterostructure. The as-prepared multicomponent heterostructure was successfully obtained via a simple three-step hydrothermal-sulfidation-electrodeposition process consisting of star-like Co-Zn-S covered with Co-Mo-P. The structure and morphology evaluation of the... 

    Simulation of sheet metal forming processes by presenting a bending-dependent inverse isogeometric methodology

    , Article International Journal of Advanced Manufacturing Technology ; Volume 112, Issue 5-6 , 2021 , Pages 1389-1408 ; 02683768 (ISSN) Shamloofard, M ; Assempour, A ; Sharif University of Technology
    Springer Science and Business Media Deutschland GmbH  2021
    Abstract
    Recently, eliminating the gap between design and formability analysis of sheet metal parts has been studied to simulate sheet metal stamping processes. In this regard, a transfer-based inverse isogeometric formulation has been proposed. This method has various advantages such as solving the governing equations in two-dimensional networks without any concern about the convergence; however, it neglects the bending effect which is a major contributor in die/punch profile radii. The present work aims to consider the bending effects by introducing a bending-dependent inverse isogeometric formulation. The developed model deals with the minimization of potential energy, deformation theory of... 

    Optimum design of middle stage tool geometry and addendum surfaces in sheet metal stamping processes using a new isogeometric-based framework

    , Article Proceedings of the Institution of Mechanical Engineers, Part B: Journal of Engineering Manufacture ; 2021 ; 09544054 (ISSN) Shamloofard, M ; Isazadeh, A. R ; Bostan Shirin, M ; Assempour, A ; Sharif University of Technology
    SAGE Publications Ltd  2021
    Abstract
    An efficient isogeometric-based framework is presented to integrate optimum design and formability analysis of sheet metal forming processes. To assess the quality of the formed parts, several objective functions such as fracture, wrinkling, thickness variation, and stretching are studied. In this framework, geometric parameters of addendum surfaces and middle tools are considered as design variables, the objective functions are calculated using the recently developed one-step and multi-step inverse isogeometric methods, and the optimum design variables are obtained using the genetic global optimization algorithm. The major advantage of employing the inverse methods is to analyze the... 

    Optimum design of middle stage tool geometry and addendum surfaces in sheet metal stamping processes using a new isogeometric-based framework

    , Article Proceedings of the Institution of Mechanical Engineers, Part B: Journal of Engineering Manufacture ; Volume 236, Issue 6-7 , 2022 , Pages 741-757 ; 09544054 (ISSN) Shamloofard, M ; Isazadeh, A. R ; Shirin, M. B ; Assempour, A ; Sharif University of Technology
    SAGE Publications Ltd  2022
    Abstract
    An efficient isogeometric-based framework is presented to integrate optimum design and formability analysis of sheet metal forming processes. To assess the quality of the formed parts, several objective functions such as fracture, wrinkling, thickness variation, and stretching are studied. In this framework, geometric parameters of addendum surfaces and middle tools are considered as design variables, the objective functions are calculated using the recently developed one-step and multi-step inverse isogeometric methods, and the optimum design variables are obtained using the genetic global optimization algorithm. The major advantage of employing the inverse methods is to analyze the... 

    Thermo-elastic Development of Cylindrical and Spherical Superelements and Introduce a New Gigh Speed Angular Contact Bearing Superelement Model

    , M.Sc. Thesis Sharif University of Technology Shamloofard, Mansoor (Author) ; Movahhedy, Mohammad Reza (Supervisor)
    Abstract
    Angular contact bearings are utilized in many industrial types of machinery, including machine tools’ spindle. Spindle is one of the most important parts of a machine tool, which has a substantial impact on dynamic properties and stability of machining processes. Spindles’ motion takes place under guidance of bearings, which are mainly angular contact type. Since bearings’ loading under forces that are resulted from angular velocity and temperature increment are intensified, it is required to control the applied forces in operating situation, in order to predict the hardness, accuracy, efficiency, and life time of spindle. Thus, determining the dynamic performance of machine tool’s spindle,... 

    Development of Inverse Isogeometric Formulations in Simulation of Sheet Metal Forming Processes

    , Ph.D. Dissertation Sharif University of Technology Shamloofard, Mansoor (Author) ; Assempour, Ahmad (Supervisor)
    Abstract
    This research presents inverse isogeometric models based on the deformation theory of plasticity to predict the blank and strain distribution in sheet metal forming processes. In this study, the NURBS functions are utilized for both modeling of a final part and analysis of the forming process. Therefore, the developed models require only one modeling and analysis representation, in contrast to finite element models which deal with two separate modeling and analysis representations. In this research, a membrane one-step inverse isogeometric model is initially presented to analyze sheet metal forming processes. This method has various advantages such as solving the governing equations in... 

    Probability of missed detection as a criterion for receiver placement in MIMO PCL

    , Article IEEE National Radar Conference - Proceedings, 7 May 2012 through 11 May 2012, Atlanta, GA ; 2012 , Pages 0924-0927 ; 10975659 (ISSN) ; 9781467306584 (ISBN) Majd, M. N ; Chitgarha, M. M ; Radmard, M ; Nayebi, M. M ; Sharif University of Technology
    IEEE  2012
    Abstract
    Using multiple antennas at the transmit and receive sides of a passive radar brings both the benefits of MIMO radar and passive radar. However one of the obstacles arisen in such configuration is the receive antennas placement in proper positions so that the radar performance is improved. Here we just consider the case of positioning one receiver among multiple illuminators of opportunity. Indeed it is a start for the solution of optimizing the geometry of the multiple receivers in a passive radar  

    An efficient method for the ring opening of epoxides with aromatic amines by Sb(III) chloride under microwave irradiation

    , Article Journal of Chemical Research ; Issue 4 , 2008 , Pages 220-221 ; 03082342 (ISSN) Ghazanfari, D ; Hashemi, M. M ; Mottaghi, M. M ; Foroughi, M. M ; Sharif University of Technology
    2008
    Abstract
    SbCl3 supported on montmorillonite K-10 is an efficient catalyst for the ring opening of epoxides with aromatic amines under solvent-free conditions and microwave irradiation to give the corresponding b-amino alcohols in high yields with high regioselectivity  

    MIMO radar signal design to improve the MIMO ambiguity function via maximizing its peak

    , Article Signal Processing ; Volume 118 , 2016 , Pages 139-152 ; 01651684 (ISSN) Chitgarha, M. M ; Radmard, M ; Nazari Majd, M ; Karbasi, S. M ; Nayebi, M. M ; Sharif University of Technology
    Elsevier  2016
    Abstract
    One of the important obstacles in MIMO (Multiple Input Multiple Output) radars is the issue of designing proper transmit signals. Indeed, the capability of signal design is a significant advantage in MIMO radars, through which, the system can achieve much better performance. Many different aspects of this performance improvement have been considered yet, and the transmit signals have been designed to attain such goal, e.g., getting higher SNR or better detector's performance at the receiver. However, an important tool for evaluating the radar's performance is its ambiguity function. In this paper, we consider the problem of transmit signal design, in order to optimize the ambiguity function... 

    Detection-localization tradeoff in MIMO radars

    , Article Radioengineering ; Volume 26, Issue 2 , 2017 , Pages 581-587 ; 12102512 (ISSN) Nazari Majd, M ; Radmard, M ; Chitgarha, M. M ; Bastani, M. H ; Nayebi, M. M ; Sharif University of Technology
    2017
    Abstract
    Two gains play key roles in recently developed MIMO wireless communication systems: "spatial diversity" gain and "spatial multiplexing" gain. The diversity gain refers to the capability to decrease the error rate of the MIMO channel, while the multiplexing gain implicitly refers to the amount of increase in the capacity of the MIMO channel. It has been shown that there is a fundamental tradeoff between these two types of gains, meaning interplay between increasing reliability (via an increase in the diversity gain) and increasing data rate (via an increase in the multiplexing gain). On the other hand, recently, MIMO radars have attracted much attention for their superior ability to enhance... 

    Antenna placement and power allocation optimization in MIMO detection

    , Article IEEE Transactions on Aerospace and Electronic Systems ; Vol. 50, Issue 2 , April , 2014 , pp. 1468-1478 Radmard, M ; Chitgarha, M. M ; Majd, M. N ; Nayebi, M. M ; Sharif University of Technology
    2014
    Abstract
    It is a well known fact that using multiple antennas at transmit and receive sides improves the detection performance. However, in such multiple-input multiple-output (MIMO) configuration, proper positioning of transmitters and receivers is a big challenge that can have significant influence on the performance of the overall system. In addition, determining the power of each transmitter under a total power constraint is a problem that should be solved in order to enhance the performance and coverage of such a system. In this paper, we design the Neyman-Pearson detector under the Rayleigh scatter model and use it to introduce a criterion for the antenna placement at both transmit and receive... 

    Ambiguity function of MIMO radar with widely separated antennas

    , Article Proceedings International Radar Symposium ; 16 -18 June , 2014 ; ISSN: 21555753 Radmard, M ; Chitgarha, M. M ; Nazari Majd, M ; Nayebi, M. M ; Sharif University of Technology
    2014
    Abstract
    There has been much interest, recently, towards exploiting the Multiple-Input Multiple-Output (MIMO) technique in radar. It is shown that using multiple antennas at transmit and receive sides can improve the performance of the system. However, in order to analyze the system's performance, its ambiguity function, i.e. the ambiguity function of a MIMO radar, is needed to be defined. In this paper, beginning from the information theoretic definitions, we derive such function, specifically for a MIMO radar with widely separated antennas  

    Choosing the position of the receiver in a MISO passive radar system

    , Article European Microwave Week 2012: "Space for Microwaves", EuMW 2012, Conference Proceedings - 9th European Radar Conference, EuRAD 2012 ; 2012 , Pages 318-321 ; 9782874870293 (ISBN) Chitgarha, M. M ; Majd, M. N ; Radmard, M ; Nayebi, M. M ; Sharif University of Technology
    2012
    Abstract
    By combining the two ideas of MIMO (Multiple Input Multiple Output) and PCL (Passive Coherent Location) in radar, one can achieve the advantages of both recently developed techniques simultaneously. While using multiple antennas at the receive side provides a spatial diversity of the object to be detected, using multiple illuminators of opportunity, most importantly, makes the radar covert to the interceptors. One obstacle in such MIMO configuration is choosing the positions of the receive antennas. In this paper, after analyzing the Neyman-Pearson detector for the DVB-T based PCL, we introduce the probability of missed detection as a criterion to place the receive antenna. Here, we only...