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    Control of planar motion of a magnetic microrobot using a novel electromagnetic actuation system

    , Article 4th International Conference on Manipulation, Automation, and Robotics at Small Scales, MARSS 2019, 1 July 2019 through 5 July 2019 ; 2019 ; 9781728109473 (ISBN) Yousefi, M ; Moradi, A ; Nejat Pishkenari, H ; Sharif University of Technology
    Institute of Electrical and Electronics Engineers Inc  2019
    A magnetic actuation system is a promising tool for untethered manipulation at the microscale that medical treatment can benefit from. This paper proposes a new magnetic actuation system that comprises of two coaxial coils on a rotary table. A fixed workspace is placed between coils. The proposed system is able to generate magnetic force with desired direction and magnitude in a plane. The conducted simulation and experiment confirm the capability of the proposed system to control the position of the microrobot. © 2019 IEEE  

    Directed motion of C60 on a graphene sheet subjected to a temperature gradient

    , Article Physical Review E - Statistical, Nonlinear, and Soft Matter Physics ; Volume 83, Issue 4 , 2011 ; 15393755 (ISSN) Lohrasebi, A ; Neek Amal, M ; Ejtehadi, M. R ; Sharif University of Technology
    Nonequilibrium molecular dynamics simulations are used to study the motion of a C60 molecule on a graphene sheet subjected to a temperature gradient. The C60 molecule is actuated and moves along the system while it just randomly dances along the perpendicular direction. Increasing the temperature gradient increases the directed velocity of C60. It is found that the free energy decreases as the C60 molecule moves toward the cold end. The driving mechanism based on the temperature gradient suggests the construction of nanoscale graphene-based motors  

    Analysis and Test of Magnetic Behavior of Special Materials and its Nano Scaling Behavior

    , M.Sc. Thesis Sharif University of Technology Aram, Mohammad Hassan (Author) ; Rashidian, Bijan (Supervisor)
    In the first part of this thesis, limitations on magnetic field distribution are studied. After that methods of creating high gradient magnetic field and limitations on it is discussed. In the second part, magnetic properties of materials and the effect of particle shape and size on these properties are studied. In this part a comprehensive analysis on demagnetizing field inside magnetic bodies is also conducted and its dependence on material susceptibility and shape is discussed. At the end of this part the effect of particle shape and size on its hysteresis loop is demonstrated theoretically, practically and by computer simulation. In order to ... 

    Nanoscale phase behavior on flat and curved membranes

    , Article Nanotechnology ; Vol. 25, issue. 50 , Dec , 2014 Andersen, T ; Bahadori, A ; Ott, D ; Kyrsting, A ; Reihani, S. N. S ; Bendix, P. M ; Sharif University of Technology
    The diverse physical properties of membranes play a critical role in many membrane associated biological processes. Proteins responsible for membrane transport can be affected by the lateral membrane order and lateral segregation of proteins is often controlled by the preference of certain membrane anchors for membrane phases having a physically ordered state. The dynamic properties of coexisting membrane phases are often studied by investigating their thermal behavior. Optical trapping of gold nanoparticles is a useful tool to generate local phase transitions in membranes. The high local temperatures surrounding an irradiated gold nanoparticle can be used to melt a part of a giant... 

    Low cost soft error hardened latch designs for nano-scale CMOS technology in presence of process variation

    , Article Microelectronics Reliability ; Volume 53, Issue 6 , June , 2013 , Pages 912-924 ; 00262714 (ISSN) Rajaei, R ; Tabandeh, M ; Fazeli, M ; Sharif University of Technology
    In this paper, two Low cost and Soft Error Hardened latches (referred to as LSEH1 and LSEH2) are proposed and evaluated. The proposed latches are fully SEU immune, i.e. they are capable of tolerating all particle strikes to any of their nodes. Moreover, they can mask Single Event Transients (SETs) occurring in combinational logics and reaching the input of the latches. We have compared our SEU/SET-tolerant latches with some well-known previously proposed soft error tolerant latches. To evaluate the proposed latches, we have done a set of SPICE simulations. The simulation results trough comparisons with other hardened latches reveal that the proposed latches not only have more robustness but... 

    An embedded elliptic nano-fiber in anti-plane strain couple stress elasticity

    , Article 2008 ASME International Mechanical Engineering Congress and Exposition, IMECE 2008, Boston, MA, 31 October 2008 through 6 November 2008 ; Volume 13, Issue PART A , 2009 , Pages 145-152 ; 9780791848746 (ISBN) Mohamadi Shodja, H ; Haftbaradaran, H ; Sharif University of Technology
    The application of higher order continuum theories, with size effect considerations, have recently been spread in the micro and nano-scale studies. One famous version of these theories is the couple stress theory. This paper utilizes this theory to study the anti-plane problem of an elliptic nano-fiber, embedded in an infinite medium, both made of centrosymmetric isotropic material. In this framework, a characteristic length appears in the formulation, by which examination of the size effect is possible. This work presents an analytical solution for the proposed problem. Copyright © 2008 by ASME  

    Physicomechanical Properties of Porous Materials by Spark Plasma Sintering

    , Article Critical Reviews in Solid State and Materials Sciences ; Volume 45, Issue 1 , 2020 , Pages 22-65 Azarniya, A ; Azarniya, A ; Safavi, M. S ; Farshbaf Ahmadipour, M ; Esmaeeli Seraji, M ; Sovizi, S ; Saqaei, M ; Yamanoglu, R ; Soltaninejad, M ; Madaah Hosseini, H. R ; Ramakrishna, S ; Kawasaki, A ; Adams, S ; Reddy, M. V ; Sharif University of Technology
    Taylor and Francis Inc  2020
    Metallic or ceramic micro/nanoporous materials have attracted particular attention due to some interesting structural and functional properties. There exist a variety of methods for producing porous materials by which optimized features can be reached. Spark plasma sintering (SPS) is one of these new-emerging approaches. This technique is often combined with conventional technologies and produce a variety of porous structures with tailorable microstructure and physicomechanical properties. This review addresses SPS and obtainable porous materials with nanoscale and microscale microstructural features. The processing methods, microstructural phenomena, and physicomechanical properties of... 

    Effects of the electric field configuration's variation due to micro-cantilever beam's curvature on pull-in phenomenon

    , Article 2006 ASME International Mechanical Engineering Congress and Exposition, IMECE2006, Chicago, IL, 5 November 2006 through 10 November 2006 ; 2006 ; 1096665X (ISSN); 0791837904 (ISBN); 9780791837900 (ISBN) Ghaemi Oskouei, S. B ; Ahmadian, M. T ; Sharif University of Technology
    American Society of Mechanical Engineers (ASME)  2006
    Micro-electromechanical systems (MEMS) have wide application in the development of sensors for the detection of magnitudes in almost any domain [1]. Resonant mode operation of micro and nano-scale oscillators have gained wide interest for applications including filters, amplifiers, non-linear mixers, atomic scale imaging, biological and chemical sensors. The device that we propose is an electrically actuated microcantilever beam. More precisely, in our design the microcantilever constitutes the movable plate of a micro-capacitor and its displacement is controlled by the voltage applied across the plates. Review of literature shows that the electric field pattern between the beam and the... 

    Numerical Modeling of a Nano Crack in Fcc Solids Using RKPM Based Dipolar Gradient Elasticity

    , M.Sc. Thesis Sharif University of Technology Shariatzadeh, Babak (Author) ; Mohammadi Shodja, Hosain (Supervisor)
    In many structures, crack creation is one of the most significant fracture mechanisms. To predict these fracture mechanisms accurate numerical modeling is necssary. Finite Element Method (FEM) is one of the substantial methods in analysis of numerical fracture problems in recent past decades. But, this method has difficulties in remeshing of elements in each step of calculation in fracture mechanics or large deformation analysis. Therefore, the theory was defined that, without using elements, just with setting of characteristics nodes in geometry of problem, the differential equations can be solved. These methods are called Meshfree or Meshless methods. RKPM is a new meshfree method for... 

    Nonlocal Nanoscale Modeling of Shape Memory Alloys Behavior Using Finite Element Method

    , M.Sc. Thesis Sharif University of Technology Soveity, Salem (Author) ; Naghdabadi, Reza (Supervisor) ; Sohrabpour, Saeed (Supervisor)
    Shape memory alloys (SMAs) are smart materials with the ability to recover their original shape. Growing the industrial and laboratory applications of SMAs, the study of their mechanical behavior is extremely important. Recently, the shape memory alloys have been investigated by empirical and experimental methods. The results show that these materials also in nano scale keep up their particular properties to a critical size. Because of the size dependence of the material properties at the nano scale, the constitutive models based on classical continuum mechanics cannot describe phenomena observed in the nano scale. For a successful application of SMAs at nano scale, nonlocal theory can be... 

    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)
    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... 

    Coarse-gained Multi-scale Modeling for Numerical Simulation of Nonlinear Behavior of Materials in Nano-scale

    , M.Sc. Thesis Sharif University of Technology Mohammadi, Khashayar (Author) ; Khoei, Amir Reza (Supervisor)
    In this thesis, a coarse-grained multi-scale method for 2D crystallyn solids based-on finite element consepts has presented. In this method, both scales are atomic scale and similar to what we see in non-local QC method, the entire atomic structure will be intact. Accordingly, calculations of potential functions and forces in the domain will have the atomic accuracy. In the presented method to reduce the domain’s degrees of freedom, the classical finite-element meshing concept to mesh the elastic linear areas in the domain is used and the MD calculations will done on the mesh nodes. Therefore, degrees of freedom in the system will reduce and consequently, the computational cost will reduce.... 

    Molecular Dynamics Simulation of Protein Channels

    , M.Sc. Thesis Sharif University of Technology Rismanian, Milad (Author) ; Saeedi, Mohammad Saeed (Supervisor) ; Firoozabadi, Bahar (Supervisor)
    By studying change of ion concentrations in animal cells, researchers have reach to important information about cell cycles such as cell growth, muscle cell contraction and cell migration. Manner and amount of passage of ions through cell membrane are basic information that for studying the cell cycle is required. In this thesis, by using two methods, Forward-Reverse constant velocity Steered Molecular Dynamics (FR-cv-SMD) and classical Equilibrium Molecular Dynamics (EMD), diffusion coefficient and Potential of Mean Force (PMF) of sodium and potassium permeation through their protein channels are obtained. For verification the molecular dynamics (MD) methods, diffusion coefficient of K+... 

    Modeling the Nonlinear Behavior of Nano-Materials Via Hierarchical RVE-based Multi-Scale Method

    , M.Sc. Thesis Sharif University of Technology Nikravesh Kazerooni, Yousef (Author) ; Khoei, Amir Reza (Supervisor)
    In this paper, a hierarchical RVE-based continuum-atomistic multiscale framework is established on the basis of the nonlinear finite element method and molecular dynamics simulation in order to model the geometric and material nonlinearities of deformable solids. In this framework, the coarse scale material properties required for nonlinear finite element method are directly exploited via fine scale atomistic simulation of atomic RVEs designated for each coarse scale integration point and required boundary conditions for atomic RVE simulation are achieved from the coarse scale kinematical response. In order to ensure the kinematical and energetic consistency between the two scales, the... 

    Size-dependent characteristics of electrostatically actuated fluid-conveying carbon nanotubes based on modified couple stress theory

    , Article Beilstein Journal of Nanotechnology ; Volume 4, Issue 1 , 2013 , Pages 771-780 ; 21904286 (ISSN) Fakhrabadi, M. M. S ; Rastgoo, A ; Ahmadian, M. T ; Sharif University of Technology
    The paper presents the effects of fluid flow on the static and dynamic properties of carbon nanotubes that convey a viscous fluid. The mathematical model is based on the modified couple stress theory. The effects of various fluid parameters and boundary conditions on the pull-in voltages are investigated in detail. The applicability of the proposed system as nanovalves or nanosensors in nanoscale fluidic systems is elaborated. The results confirm that the nanoscale system studied in this paper can be properly applied for these purposes  

    A layout-based approach for multiple event transient analysis

    , Article Proceedings - Design Automation Conference ; 2013 ; 0738100X (ISSN) ; 9781450320719 (ISBN) Ebrahimi, M ; Asadi, H ; Tahoori, M. B ; Sharif University of Technology
    With the emerging nanoscale CMOS technology, Multiple Event Transients (METs) originated from radiation strikes are expected to become more frequent than Single Event Transients (SETs). In this paper, a fast and accurate layout- based Soft Error Rate (SER) estimation technique with consideration of both SET and MET fault models is pro- posed. Unlike previous techniques in which the adjacent MET sites are obtained from logic-level netlist, we perform a comprehensive layout analysis to extract MET adjacent cells. It is shown that layout-based technique is the only effective solution for identification of adjacent cells as netlist-based techniques significantly underestimate the overall SER.... 

    Dissipative particle dynamics simulation of electroosmotic flow in nanoscale channels

    , Article 48th AIAA Aerospace Sciences Meeting Including the New Horizons Forum and Aerospace Exposition, Orlando, FL, 4 January 2010 through 7 January 2010 ; 2010 ; 9781600867392 (ISBN) Darbandi, M ; Zakeri, R ; Schneider, G. E ; Sharif University of Technology
    This Paper presents the simulation of electroosmotic flow in nanochannels using the dissipative particle dynamics (DPD) method. Most of the past electroosmotic phenomenon studies have been carried out using the continuum flow assumptions. However, there are many electroosmotic applications in nanoscales NEMS and microscales MEMS, which need to be treated using non-continuum flow assumptions. We simulate the electroosmotic flow within the mesoscopic scale using the DPD method. Contrary to the ordinary molecular dynamics method, the DPD method provides less computational costs. We will show that the current DPD results are in very good agreement with other available non-DPD results. To expand... 

    Crosstalk modeling to predict channel delay in Network-on-Chips

    , Article Proceedings - IEEE International Conference on Computer Design: VLSI in Computers and Processors, 3 October 2010 through 6 October 2010 ; October , 2010 , Pages 396-401 ; 10636404 (ISSN) ; 9781424489350 (ISBN) Patooghy, A ; Miremadi, S. G ; Shafaei, M ; Sharif University of Technology
    Communication channels in Network-on-Chips (NoCs) are highly susceptible to crosstalk faults due to the use of nano-scale VLSI technologies in the fabrication of NoCs. Crosstalk faults cause variable timing delay in NoC channels based on the patterns of transitions appearing on the channels. This paper proposes an analytical model to estimate the timing delay of an NoC channel in the presence of crosstalk faults. The model calculates expected number of 4C, 3C, 2C, and 1C transition patterns to predict delay of a K-bit communication channel. The model is applicable for both non-protected channels and channels which are protected by crosstalk mitigation methods. Spice simulations are done in a... 

    Torsion of an eccentrically two-phase circular nanobar

    , Article 2010 IEEE 5th International Conference on Nano/Micro Engineered and Molecular Systems, NEMS 2010, 20 January 2010 through 23 January 2010 ; January , 2010 , Pages 70-73 ; 9781424465439 (ISBN) Pahlevani, L ; Shodja, H. M ; Sharif University of Technology
    The effect of surface and interface elasticity in analysis of the Saint-Venant torsion problem of an eccentrically two-phase circular nanobar is considered. The problem is formulated in the context of Gurtin's surface elasticity. For a rigorous solution of the proposed problem, conformal mapping together with a Laurent series expansion are employed. At the nanoscales the usual classical theories cease to hold and the corresponding results deteriorate. The numerical results well illustrate that the torsional rigidity of the mentioned nanosized structural elements are significantly affected by the size. Some applications of the given results can be contemplated in the design of micro/nano... 

    Planar molecular dynamics simulation of Au clusters in pushing process

    , Article International Journal of Nanomanufacturing ; Volume 5, Issue 3-4 , 2010 , Pages 288-296 ; 17469392 (ISSN) Mahboobi, S. H ; Meghdari, A ; Jalili, N ; Amiri, F ; Sharif University of Technology
    Based on the fact that the manipulation of fine nanoclusters calls for more precise modelling, the aim of this paper is to conduct an atomistic investigation for interaction analysis of particle-substrate system for pushing and positioning purposes. In the present research, 2D molecular dynamics simulations have been used to investigate such behaviours. Performing the planar simulations can provide a fairly acceptable qualitative tool for our purpose while the computation time is reduced extremely in comparison to 3D simulations. To perform this study, Nose-Hoover dynamics and Sutton-Chen interatomic potential will be used to investigate the behaviour of the aforementioned system. Pushing of...