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    Scattering of SH-Waves by a Cylindrical Multi Inhomogeneity Embedded in a Piezo-Electromagnetic Medium Using an Analytical Innovative Micromechanical Approach

    , Ph.D. Dissertation Sharif University of Technology Ordookhani, Ali (Author) ; Mohammadi Shodja, Hossein (Supervisor)
    Abstract
    This work examines the problem of the fully coupled magneto-electro-elastic (MEE) scattering of SH-waves incident upon a heterogeneous MEE scatterer which is embedded in an unbounded medium. The scatterer consists of a circular core and a circular encapsulator with eccentricity. All three regions: the core, encapsulator, and the surrounding matrix have distinct MEE properties and fully coupled constitutive relations. The generated coupled MEE fields coexist simultaneously in all these regions without resort to any simplifying assumptions. The precise description of the multifunctionality involves the solution of three fully coupled partial differential equations in three different regions.... 

    Central Difference Finite Volume Lattice Boltzmann Method for Simulation of Incompressible Electro-Magneto-Hydrodanamic Flows

    , M.Sc. Thesis Sharif University of Technology Taheri, Sina (Author) ; Hejranfar, Kazem (Supervisor)
    Abstract
    In the present study, the simulation of incompressible Electro-Magneto-hydrodynamic flows is performed using a finite volume lattice Boltzmann method (FVLBM). The Boltzmann transport equation is solved using a cell-centered finite volume method on structured meshes. A central difference scheme is used to discretize the spatial derivatives and the fourth-order numerical dissipation term is added to stabilize the solution. To discretize the temporal derivative, the fourth-order Runge-Kutta time stepping scheme is applied. The standard collision-streaming lattice Boltzmann method has been used to simulate EMHD flows in the literature, however, it has several deficiencies such as the... 

    Innovative Theories of Micro and Nano Ellipsoidal Inclusion and Inhomogeneity in Magneto-electro-elastic Media with General Anisotropy

    , Ph.D. Dissertation Sharif University of Technology Rashidinejad, Ehsan (Author) ; Mohammadi Shodja, Hossein (Supervisor)
    Abstract
    In the current work, the two- and three-dimensional electro-elastic fields of periodically as well as arbitrarily distributed interacting quantum wires (QWRs) and interacting quantum dots (QDs) of arbitrary shapes within a piezoelectric matrix are studied analytically. The lattice mismatch between the QWR/QD and the barrier is accounted through prescribing an initial misfit strain field within the QWR/QD. The distinction between the electro-mechanical properties of the QWR/QD and those of the barrier is treated by introducing a novel electro-mechanical equivalent inclusion method in Fourier space (FEMEIM). Moreover, the theory can readily treat cases where the QWRs/QDs are multi-phase or... 

    Physical-Phenomenological Constitutive Modeling and Numerical Analysis of Magnetic Shape Memory Alloys

    , M.Sc. Thesis Sharif University of Technology Mousavi, Mohammad Reza (Author) ; Arghavani, Jamal (Supervisor) ; Sohrabpour, Saeed (Supervisor) ; Naghdabadi, Reza (Co-Advisor)
    Abstract
    Magnetic shape memory alloys (MSMAs) are a new class of smart materials that exhibit characteristics of large recoverable strains and high frequency. These unique characteristics, make MSMAs interesting materials for applications such as actuators, sensors, and energy harvesters. This thesis presents a three-dimensional phenomenological constitutive model for MSMAs, developed within the framework of irreversible continuum thermodynamics. To this end, a proper set of internal variables is introduced to reflect the microstructural consequences on the material macroscopic behavior. Moreover, a stress-dependent thermodynamic force threshold needed for variant reorientation is introduced which... 

    Modeling of Magnetic Shape Memory Alloys Plates

    , M.Sc. Thesis Sharif University of Technology Naderi, Hossein (Author) ; Sayyaadi, Hassan (Supervisor)
    Abstract
    Magnetic shape memory alloys (MSMAs) are a new class of smart materials which exhibit properties such as large reversible strains and high performance frequencies. These unique properties, offer magnetic shape memory alloys as an option in applications such as actuators, sensors and energy harvesters. In this thesis, the equations of magnetic shape memory alloys by considering nonlinear terms of Von karaman in strain-displacement relations, is expanded by using the theory of thin plates in two dimensions which can be used for plate equations with any boundary conditions by applying elastic boundary. In order to verify the obtained model, the equations of motions of magnetic shape memory... 

    Implementation and Analysis of Optical Isolation using Reciprocal and Nonreciprocal Elements

    , M.Sc. Thesis Sharif University of Technology Pooya Fard, Ali (Author) ; Mehrany, Khashayar (Supervisor)
    Abstract
    In this thesis we study the possibility of unidirectional transmission of light using reciprocal and nonreciprocal elements. Unidirectional transmission will allow us to separate the coupling of light into and out of resonators and design unidirectional waveguides. We start by studying the effects of one-sided modulations of dielectric constant of reciprocal structures. One-sided modulation will satisfy the phase matching condition for the coupling of two waves only in one direction. Using coupled mode theory, we study one sided modulation in layered media. Next, we find the exact solution to such strucures using transfer matrix method and analyze one-sided modulation in waveguide... 

    Improvement of the in-Memory Automata Processor Accelerators using Emerging Memories

    , M.Sc. Thesis Sharif University of Technology Yazdanpanah, Ali (Author) ; Hessabi, Shahin (Supervisor)
    Abstract
    Non-deterministic finite automata (NFA) are an elementary type of Turing machines with very high processing power. NFA processors provide parallelism at the data and task level because they can be in several different output states in one clock cycle. Implementing such machines with memory is a good strategy because if we consider each of the memory columns as a state, by selecting a row of the memory, we can activate several states at the same time, which is an implementation of NFA. NFA-based automata processors were first introduced by Micron and were very powerful for issues such as pattern matching, DNA sequencing, or regular expressions and, in general, for machine learning topics.... 

    Anomalous Reflection and Transmission in Resonant Magneto-Optic Structures

    , M.Sc. Thesis Sharif University of Technology Pahlavan, Payman (Author) ; Mehrany, Khashayar (Supervisor) ; Rajaei, Behzad (Co-Advisor)
    Abstract
    In this thesis, light transmission in dielectric slit arrays on metallic and magneto-optical material has been analyzed by mode matching method together with numerical simulations on commercial softwares such as Comsol Multiphysics and CST microwave studio. It has been shown that light transmission can be attributed to either the Fabry-Perot resonances or a collective resonance phenomenon across the array. In the first case, the transmission resonance is related to the slit depth and is confined to a single slit. In the second case; however, the resonant mechanism affects several neighboring slits. Surprisingly the former is converted to the latter by increasing the slit depth. Furthermore... 

    Study on Motion of Electrical Conductor Fluid Plug Actuated Electromagnetically in Microsystems

    , Ph.D. Dissertation Sharif University of Technology Karmozdi, Mohsen (Author) ; Shafii, Mohmmad Behshad (Supervisor) ; Afshin, Hossein (Supervisor)
    Abstract
    Micropumps are regarded as one of the devices used in microsystems, which are responsible for pumping working fluid. The Mercury Magneto Reciprocating (MMR) micropump, which has been introduced for less than a decade, is an innovative kind of micropumps which the pumping agent includes three liquid metal droplets (LMD) placed inside lateral chambers and reciprocated by the electromagnetic force inside the chambers. The working fluid located inside the main channel is pumped through due to the movement of these three LMDs. The equations governing this micropump are complex and their numerical solution is a time-consuming process, due to electromagnetic, hydrodynamic, and unsteady effects. The... 

    Laser and solar light-induced degradation of pollutant dyes using bi-plasmonic ag-au nanoparticles-decorated magnetic tio2 for textile wastewater treatment

    , Article Journal of Nanostructures ; Volume 12, Issue 1 , 2022 , Pages 45-61 ; 22517871 (ISSN) Nezhadali, A ; Shapouri, M. R ; Amoli-Diva, M ; Sharif University of Technology
    University of Kashan  2022
    Abstract
    Eight eco-friendly, and magnetically-separable heterogeneous photocatalysts including five Au nanoparticles (NPs) modified magnetic TiO2@Fe3O4 NPs and three Ag-Au bi-plasmonic NPs-decorated TiO2@Fe3O4 NPs with enhanced photocatalytic performance under visible light were synthesized and used for photodegradation of methyl orange (MO) as a model pollutant in textile wastewater samples. The photocatalytic activity was assessed using two radiation sources namely, an intense linear 532-nm laser and a continuous solar-simulated xenon lamp. Compared to the TiO2 alone, the prepared photocatalysts revealed efficient photocatalytic activity in visible region due to the presence of two localized... 

    Modified Green–Lindsay analysis of an electro-magneto elastic functionally graded medium with temperature dependency of materials

    , Article Mechanics of Time-Dependent Materials ; 2021 ; 13852000 (ISSN) Mirparizi, M ; Razavinasab, S. M ; Sharif University of Technology
    Springer Science and Business Media B.V  2021
    Abstract
    This article presents a modified Green–Lindsay (MG-L) thermoelasticity model considering temperature and strain rate. Previously, this model has been developed based on the Green–Lindsay theory of thermoelasticity using strain and temperature rate dependent thermoelastic equations. This study analyzes stress and thermal wave propagation of a functionally graded medium exposed to an electromagnetic field and a thermal shock. All magnetic, elastic, and thermal features of the medium are considered to vary in the longitudinal direction. Additionally, the properties of the material are dependent on the temperature in the form of a cubic function. Using the large displacement formulation and the... 

    Shear horizontal surface acoustic waves in functionally graded magneto-electro-elastic half-space

    , Article Journal of Engineering Mathematics ; Volume 97, Issue 1 , 2016 , Pages 83-100 ; 00220833 (ISSN) Shodja, H. M ; Eskandari, S ; Eskandari, M ; Sharif University of Technology
    Springer Netherlands 
    Abstract
    The propagation of shear horizontal surface acoustic waves (SHSAWs) in an inhomogeneous magneto-electro-elastic (MEE) half-space with 6-mm symmetry is studied. By virtue of both the direct approach and Stroh-formalism, the dispersion relations corresponding to two general cases of material properties variation are obtained. In the first case, it is assumed that all material properties involving the MEE properties and density vary similarly in depth, whereas, the second case considers identical variation for the MEE properties, which differs from the variation of the density. The non-dispersive SHSAW velocities pertinent to the homogeneous MEE media are obtained under eight different surface... 

    Dynamic stability analysis of a sandwich beam with magnetorheological elastomer core subjected to a follower force

    , Article Acta Mechanica ; Volume 231, Issue 9 , 2020 , Pages 3715-3727 Rokn Abadi, M ; Yousefi, M ; Haddadpour, H ; Sadeghmanesh, M ; Sharif University of Technology
    Springer  2020
    Abstract
    In the present study, the effect of using magnetorheological elastomer materials and a magnetic field on the dynamic stability of a sandwich beam under a follower force has been investigated for various boundary conditions. The considered sandwich beam consists of a magnetorheological elastomer core constrained by elastic layers. The structural governing equations are derived using Hamilton’s principle and solved by the finite element method. The validity of the result is examined by comparison with those in the literature. The effects of variation in the parameters such as magnetic field intensity and the thickness of the layers on the stability of the sandwich beam are studied. Finally,... 

    Magnetic field effect on free vibration of smart rotary functionally graded nano/microplates: a comparative study on modified couple stress theory and nonlocal elasticity theory

    , Article Journal of Intelligent Material Systems and Structures ; Volume 29, Issue 11 , 2018 , Pages 2492-2507 ; 1045389X (ISSN) Shojaeefard, M. H ; Saeidi Googarchin, H ; Mahinzare, M ; Eftekhari, S. A ; Sharif University of Technology
    SAGE Publications Ltd  2018
    Abstract
    In this article, free vibration behavior of a rotating nano/microcircular plate constructed from functionally graded magneto-elastic material is simulated with the first-order shear deformation theory. For the sake of comparison, the nonlocal elasticity theory and the modified couple stress theory are employed to implement the small size effect in the natural frequencies behavior of the nano/microcircular plate. The governing equations of motion for functionally graded magneto-elastic material nano/microcircular plates are derived based on Hamilton’s principle; comparing the obtained results with those in the literature, they are in a good agreement. Finally, the governing equations are... 

    Torsional vibration analysis of a rotating tapered sandwich beam with magnetorheological elastomer core

    , Article Journal of Intelligent Material Systems and Structures ; Volume 29, Issue 11 , 2018 , Pages 2406-2423 ; 1045389X (ISSN) Bornassi, S ; Navazi, H. M ; Sharif University of Technology
    SAGE Publications Ltd  2018
    Abstract
    In this study, the torsional vibration analysis of a rotating tapered sandwich beam with a magnetorheological elastomer core has been investigated. The magnetorheological elastomer material is used as a constrained damping layer embedded between two elastic constraining skins in order to improve the vibrational behavior of the sandwich beam. The three layers of the sandwich beam have rectangular cross-sections with symmetric arrangement. The problem formulation is set up based on the torsional theory of rectangular laminated plates. The assumed modes method and the Lagrange equations are used to derive the governing equations of motion of the system. The validity of the presented formulation... 

    Modeling magneto-mechanical behavior of Fe3O4 nanoparticle/polyamide nanocomposite membrane in an external magnetic field

    , Article Journal of Composite Materials ; Volume 52, Issue 11 , 2018 , Pages 1505-1517 ; 00219983 (ISSN) Tayefeh, A ; Wiesner, M ; Mousavi, A ; Poursalehi, R ; Sharif University of Technology
    SAGE Publications Ltd  2018
    Abstract
    The magnetic response of a polyamide nanocomposite membrane under applying a magnetic field has been modeled to evaluate elastic deformation order of magnitude. A PA-Fe3O4 nanocomposite membrane is considered to be modeled under influence of volume plane stress caused by a magnetic field. The modeling of the mechanical behavior of Fe3O4-PA nanocomposite membrane suggests that nanoparticle displacements within the nanocomposite, in the order of 200 nm under applying an external magnetic field, are greater than free volumes or porosities of the polyamide membrane. The membrane can be excited to mechanically vibrate by applying an alternating magnetic field lower than 0.1 T. As the results... 

    Aeroelastic analysis of a sandwich panel with partially treated magneto-rheological fluid core

    , Article Journal of Intelligent Material Systems and Structures ; Volume 30, Issue 1 , 2019 , Pages 140-154 ; 1045389X (ISSN) Asgari, M ; Rayyat Rokn Abadi, M ; Yousefi, M ; Haddadpour, H ; Sharif University of Technology
    SAGE Publications Ltd  2019
    Abstract
    This study considers the aeroelastic instability of a partially treated magneto-rheological fluid sandwich panel in supersonic airflow. The linear first-order piston theory is used for modeling the aerodynamic pressure. Using classical Hamilton’s principle along with the finite element method, the equations of motion are derived. The critical value of the non-dimensional aerodynamic pressure is obtained by traditional p-method scheme. The validity of the finite element formulation is examined through comparison with those obtained from the assumed mode formulation and the available results in the literature. Various parametric studies including the effects of applied magnetic field, core and... 

    Aeroelastic analysis of a sandwich panel with partially treated magneto-rheological fluid core

    , Article Journal of Intelligent Material Systems and Structures ; Volume 30, Issue 1 , 2019 , Pages 140-154 ; 1045389X (ISSN) Asgari, M ; Rayyat Rokn Abadi, M ; Yousefi, M ; Haddadpour, H ; Sharif University of Technology
    SAGE Publications Ltd  2019
    Abstract
    This study considers the aeroelastic instability of a partially treated magneto-rheological fluid sandwich panel in supersonic airflow. The linear first-order piston theory is used for modeling the aerodynamic pressure. Using classical Hamilton’s principle along with the finite element method, the equations of motion are derived. The critical value of the non-dimensional aerodynamic pressure is obtained by traditional p-method scheme. The validity of the finite element formulation is examined through comparison with those obtained from the assumed mode formulation and the available results in the literature. Various parametric studies including the effects of applied magnetic field, core and... 

    Analysis and modification of a common energy harvesting system using magnetic shape memory alloys

    , Article Journal of Intelligent Material Systems and Structures ; 2020 Sayyaadi, H ; Mehrabi, M ; Hoviattalab, M ; Sharif University of Technology
    SAGE Publications Ltd  2020
    Abstract
    In this paper, a common energy harvester is investigated which uses a specimen of magnetic shape memory alloy (MSMA). The aim of this study is to improve system performance and to evaluate the magneto-mechanical loading on the MSMA material. Since demagnetization effect is not included in the employed original MSMA model, a method to incorporate this effect is proposed which has a good performance for the specific magneto-mechanical loading of this problem. In order to decrease the need for bias magnetic field and increase system efficiency, a new return mechanism for the MSMA specimen is proposed. The results indicate that the maximum harvested power from the improved system is obtained at... 

    Modeling of magnetic shape memory alloy plates for pressure sensor application

    , Article Journal of Intelligent Material Systems and Structures ; 2020 Sayyaadi, H ; Naderi, H ; Sharif University of Technology
    SAGE Publications Ltd  2020
    Abstract
    This article investigates the basis for pressure sensor application based on the magnetic shape memory effect in membranes. Von Karmans nonlinear terms are considered in strain–displacement relationships of thin films, and a new method is presented for solution of large deflections of thin films with arbitrary boundary condition. In this study, the equations of motion of magnetic shape memory alloys are extended. In pressurized membranes, the complex distribution of mechanical stress can cause the martensitic reorientation, which is the underlying mechanism for sensing applications in magnetic shape memory alloys. To examine the obtained model, the governing equations of magnetic shape...