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    Control and Optimization of Robotic Swarm Flocking Using Naturally Inspired Methods

    , M.Sc. Thesis Sharif University of Technology Vatankhah, Ramin (Author) ; Alasty, Aria (Supervisor)
    Abstract
    The idea of using groups of simple autonomous robots instead of one or limited number of very sophisticated robots is inspired by flocking behaviors of animals. Distributed control structures and artificial swarming have attracted lots of studies in robotics. There are many applications for robotic swarms in which members are very simple robots with low communication capabilities. These robots communicate only within very limited distances. In this thesis, a homogenous robotic swarm with at least two robots is assumed. Swarm robots are considered to be dimensionless with no time delay, which is a normal assumption in this field of studies. Robots move in planar space and their behaviors are... 

    Performance of RC Shear Walls Strengthened by Vertical Strips of Steel Plates under Seismic Loading

    , M.Sc. Thesis Sharif University of Technology VatanKhah Rahmani, Borna (Author) ; Khaloo, Alireza (Supervisor)
    Abstract
    Even though a considerable amount of research has been conducted on composite wall system during past years, very limited research has been reported on shear walls strengthened by steel plates. In 2008, the composite shear wall, which consisted of reinforced concrete wall, retrofitted by steel plates, attached to both sides of RC walls using mechanical connectors in form of shear studs, bolts or lateral ties tested under axial load and lateral force. In this research, seismic behavior of RC shear walls strengthened by vertical strips of steel plates is going to be studied. The result will be compared with RC shear wall which fully covered by steel plates. The behavior of RC shear wall will... 

    Formulation of Geometrically Nonlinear Microbeams Based on the Second Strain Gradient Theory

    , M.Sc. Thesis Sharif University of Technology Karparvarfard, Mohammad Hassan (Author) ; Asghari, Mohsen (Supervisor) ; Vatankhah, Ramin (Supervisor)
    Abstract
    Nowadays, the usage of beam-shaped structures has widely spread in micro- and nano-electromechanical systems; consequently, scholars are extremely interested in precise modeling of static and dynamic behaviors of them. As the beams utilized in MEMS and NEMS structures have thicknesses in the order of microns and sub-microns, the experimentally validated small scale effects would be considerable in their behavior. In fact, experiments manifest that the size-dependent behavior is an intrinsic feature of materials when they are used in small-scale structures. In the classical continuum mechanics, there exists no material length scale parameter. Thus, the classical theory is unable to capture... 

    Vibration Control of Nonclassical Microbeams Using Boundary Control Theory of Partial Differential Equations

    , Ph.D. Dissertation Sharif University of Technology Vatankhah, Ramin (Author) ; Alasty, Aria (Supervisor)
    Abstract
    Nowadays, continuous systems such as strings, bars, beams and plates have become widespread in science and engineering applications. To achieve the control purposes of continuous systems, most of engineers use discretization techniques to reduce the governing partial differential equation (PDE) into a set of ordinary differential equations (ODEs). From practical point of view, this model reduction can cause many problems such as in-domain measurement and actuation and control spillover. This thesis attempts to investigate the problem of vibration control of nonclassical microscale beams using the partial differential equation control theory which eliminates spillover instabilities. To this... 

    Passage-Way Identification and Crossing Control of an Experimental Swarm Robot

    , M.Sc. Thesis Sharif University of Technology Balaghi Enalou, Mohammad Hadi (Author) ; Alasti, Aria (Supervisor) ; Vatankhah, Ramin (Co-Advisor)
    Abstract
    The aim of the proposed thesis is to devise a method of passage-way identification and crossing control of an experimental swarm robot. In the previous works done in the Sharif University of Technology, The main focus was on the collective behaviours than can be emeged from a swarm robot. Collective behaviours are such a primitive behaviours that are combined in order to lead to a real mission. In this investigation, the main focus is on the design of a mission. In this way, by combining the aggregation-divegance, chain formation, leader following and wall following collective behaviours, the desired is fulfilled. The algorithms is so that in the first stage, the agents of the swarm... 

    Vibration Boundary Control in Micro-beams Equipped with a Layer of Piezoelectric Actuator

    , M.Sc. Thesis Sharif University of Technology (Author) ; Salarieh, Hassan (Supervisor) ; Alasti, Aria (Supervisor) ; Vatankhah, Ramin ($item.subfieldsMap.e)
    Abstract
    Nowadays, micro systems in many area of science and technology have special importance and status. The main function of these systems is based on the deformation of a beam at micro scale. Therefore study of behavior and control of micro-beams will have a great importance. Among micro-beams, clamped-free and clamped-clamped micro beams that actuated by piezoelectric and electrostatic actuators have wider applications. For example, clamped-free micro-beams are used in atomic force microscopy (AFM), micro switches, mass sensors and micro-accelerometers and clamped-clamped micro-beams are used in micro mirrors and Grating Light Valves (GLV). In this thesis, the studied system is clamped-free... 

    Design and Simulation of a Passive Microfluidic Device for Particle Separation

    , M.Sc. Thesis Sharif University of Technology Vatankhah, Parham (Author) ; Shamloo, Amir (Supervisor)
    Abstract
    Nowadays, separation and filtration of particles has many industrial applications in biology and medicine. In this thesis, passive microfluidics are designed and simulated which are able to separate and filter particles. Although particles aer generally expected to follow laminar flow streamlines in the absence of external forces, inertial forxes van cause particles to migrate across mictochannels in an accurate and predictable manner. The effect of these forces is invedtigated, and by using previous research, a model is developed to predict these forces. First design is a microchannel with Archimedean spiral which utilizes both inertial forces and Dean flow to separate particles in the... 

    Boundary Control of Vibration in Satellite Flexible Solar Panels

    , M.Sc. Thesis Sharif University of Technology Kaviani Rad, Hossein (Author) ; Alasty, Aria (Supervisor) ; Salarieh, Hassan (Supervisor) ; Vatankhah, Ramin (Co-Advisor)
    Abstract
    Many spacecrafts and satellites have long flexible components, the most common ones are the satellites with flexible solar panels, which are used to provide the satellite energy. The governing equations of the satellite rigid motion along with the solar panels vibrations are the combination of the coupled partial and ordinary differential equations. Various reasons, such as the satellite maneuvers and the external disturbances, cause the vibration of panels. Due to the dependence between the governing equations of the satellite rigid motion and the flexible components vibrations, these vibrations affect the satellite rigid dynamics and the control aims; therefore, in addition to the... 

    Formulation for Mechanical Modelling of Small-Scale Micro- and Nano- Beams and Plates for Statical and Vibrational Analysis Based on the Second Strain Gradient Theory

    , Ph.D. Dissertation Sharif University of Technology Momeni, Alireza (Author) ; Asghari, Mohsen (Supervisor) ; Vatankhah, Ramin (Co-Advisor)
    Abstract
    In this thesis, the formulation of beams and plates in the micro- and nano scales is presented based on the second strain gradient theory (SSGT) introduced by Mindlin. The SSGT is a non-classical continuum theory that includes the second-order gradients of strain tensor in its formulation and this leads to more accurate modeling for mechanical behavior of materials than the strain gradient theory. On the other hand, due to the ever-increasing use of micro- and nano-electromechanical systems, analysis of the mechanical behavior of their deformable components for design and construction is of particular importance. For this purpose, analysis of Timoshenko beams and Euler-bernoulli beams made... 

    Thermoeconomic analysis and multi-objective optimization of a novel trigeneration system consisting of kalina and humidificationdehumidification desalination cycles

    , Article Journal of Thermal Engineering ; Volume 8, Issue 1 , 2022 , Pages 52-66 ; 21487847 (ISSN) Behnam, P ; Faegh, M ; Fakhari, I ; Ahmadi, P ; Faegh, E ; Rosen, M. A ; Sharif University of Technology
    Yildiz Technical University  2022
    Abstract
    Low-temperature geothermal heat sources have the highest share of geothermal energy in the world. Utilization of these heat sources for energy and freshwater generation can play an important role in meeting energy and freshwater demands. To do so, this study aims to propose a novel trigeneration cycle powered by low-temperature geothermal sources. The proposed system, which is an integration of Kalina and humidification-dehumidification (HDH) cycles, is used for the generation of electricity, heating, and freshwater. For the Kalina cycle, an evaporative condenser is used. It also acts as a humidifier and heater of the humidification-dehumidification desalination cycle, resulting in a... 

    Percolation theory in reservoir engineering

    , Book King, P. R ; Masihi, Mohsen
    World Scientific  2018

    Nonlinear free vibration analysis of in-plane Bi-directional functionally graded plate with porosities resting on elastic foundations

    , Article International Journal of Applied Mechanics ; Volume 14, Issue 1 , 2022 ; 17588251 (ISSN) Hashemi, S ; Shahri, P. K ; Beigzadeh, S ; Zamani, F ; Eratbeni, M. G ; Mahdavi, M ; Heidari, A ; Khaledi, H ; Abadi, M. R. R ; Sharif University of Technology
    World Scientific  2022
    Abstract
    This paper deals with the nonlinear free vibration analysis of in-plane bi-directional functionally graded (IBFG) rectangular plate with porosities which are resting on Winkler-Pasternak elastic foundations. The material properties of the IBFG plate are assumed to be graded along the length and width of the plate according to the power-law distribution, as well as, even and uneven types are taken into account for porosity distributions. Equations of motion are developed by means of Hamilton's principle and von Karman nonlinearity strain-displacement relations based on classical plate theory (CPT). Afterward, the time-dependent nonlinear equations are derived by applying the Galerkin... 

    Wavelet-Based biphase analysis of brain rhythms in automated wake-sleep classification

    , Article International Journal of Neural Systems ; 2022 ; 01290657 (ISSN) Mohammadi, E ; Makkiabadi, B ; Shamsollahi, M. B ; Reisi, P ; Kermani, S ; Sharif University of Technology
    World Scientific  2022
    Abstract
    Many studies in the field of sleep have focused on connectivity and coherence. Still, the nonstationary nature of electroencephalography (EEG) makes many of the previous methods unsuitable for automatic sleep detection. Time-frequency representations and high-order spectra are applied to nonstationary signal analysis and nonlinearity investigation, respectively. Therefore, combining wavelet and bispectrum, wavelet-based bi-phase (Wbiph) was proposed and used as a novel feature for sleep-wake classification. The results of the statistical analysis with emphasis on the importance of the gamma rhythm in sleep detection show that the Wbiph is more potent than coherence in the wake-sleep... 

    Location and distribution management of relief centers: A genetic algorithm approach

    , Article International Journal of Information Technology and Decision Making ; Volume 14, Issue 4 , July , 2015 , Pages 769-803 ; 02196220 (ISSN) Najafi, M ; Farahani, R. Z ; De Brito, M. P ; Dullaert, W ; Sharif University of Technology
    World Scientific Publishing Co. Pte Ltd  2015
    Abstract
    Humanitarian logistics is regarded as a key area for improved disaster management efficiency and effectiveness. In this study, a multi-objective integrated logistic model is proposed to locate disaster relief centers while taking into account network costs and responsiveness. Because this location problem is NP-hard, we present a genetic approach to solve the proposed model  

    Multiphase simulation of liquid jet breakup using smoothed particle hydrodynamics

    , Article International Journal of Modern Physics C ; Volume 28, Issue 4 , 2017 ; 01291831 (ISSN) Pourabdian, M ; Omidvar, P ; Morad, M. R ; Sharif University of Technology
    World Scientific Publishing Co. Pte Ltd  2017
    Abstract
    This paper deals with numerical modeling of two-phase liquid jet breakup using the smoothed particle hydrodynamics (SPH) method. Simulation of multiphase flows involving fluids with a high-density ratio causes large pressure gradients at the interface and subsequently divergence of numerical solutions. A modified procedure extended by Monaghan and Rafiee is employed to stabilize the sharp interface between the fluids. Various test cases such as Rayleigh-Taylor instability, two-phase still water and air bubble rising in water have been conducted, by which the capability of accurately capturing the physics of multiphase flows is verified. The results of these simulations are in a good... 

    Modeling the probability distribution of the bacterial burst size via a game-theoretic approach

    , Article Journal of Bioinformatics and Computational Biology ; Volume 16, Issue 4 , 2018 ; 02197200 (ISSN) Malekpour, S. A ; Pakzad, P ; Foroughmand Araabi, M. H ; Goliaei, S ; Tusserkani, R ; Goliaei, B ; Sadeghi, M ; Sharif University of Technology
    World Scientific Publishing Co. Pte Ltd  2018
    Abstract
    Based on previous studies, empirical distribution of the bacterial burst size varies even in a population of isogenic bacteria. Since bacteriophage progenies increase linearly with time, it is the lysis time variation that results in the bacterial burst size variations. Here, the burst size variation is computationally modeled by considering the lysis time decisions as a game. Each player in the game is a bacteriophage that has initially infected and lysed its host bacterium. Also, the payoff of each burst size strategy is the average number of bacteria that are solely infected by the bacteriophage progenies after lysis. For calculating the payoffs, a new version of ball and bin model with... 

    On N2-vertex coloring of graphs

    , Article Discrete Mathematics, Algorithms and Applications ; Volume 10, Issue 1 , 2018 ; 17938309 (ISSN) Akbari, S ; Alipourfard, N ; Jandaghi, P ; Mirtaheri, M ; Sharif University of Technology
    World Scientific Publishing Co. Pte Ltd  2018
    Abstract
    Let G be a graph. A vertex coloring ψ of G is called N2-vertex coloring if |ψ(v)|≤ 2 for every vertex v of G, where ψ(v) is the set of colors of vertices adjacent to v. Let t2(G) be the maximum number of colors used in an N2-vertex coloring of G. We provide some lower and upper bounds for t2(G) in terms of girth, diameter or size of G. Also, for every tree T, we obtain t2(T). © 2018 World Scientific Publishing Company  

    Highly efficient and stable perovskite solar cells based on a low-cost carbon cloth

    , Article Advanced Energy Materials ; Volume 6, Issue 20 , 2016 ; 16146832 (ISSN) Gholipour, S ; Correa Baena, J. P ; Domanski, K ; Matsui, T ; Steier, L ; Giordano, F ; Tajabadi, F ; Tress, W ; Saliba, M ; Abate, A ; Morteza Ali, A ; Taghavinia, N ; Grätzel, M ; Hagfeldt, A ; Sharif University of Technology
    Wiley-VCH Verlag  2016
    Abstract
    A low-cost carbon cloth is applied in perovskite solar cells (PSC) as a collector composite and degradation inhibitor. This study incorporates carbon fibers as a back contact in perovskite solar cells, which results in enhancement in all photovoltaic parameters. This material is suitable for large-scale fabrication of PSCs as it has shown an improved long-term stability when compared to the gold counterpart under elevated temperatures  

    Effect of CsCl additive on the morphological and optoelectronic properties of formamidinium lead iodide perovskite

    , Article Solar RRL ; Volume 3, Issue 11 , 2019 ; 2367198X (ISSN) Chavan, R. D ; Prochowicz, D ; Yadav, P ; Tavakoli, M. M ; Nimbalkar, A ; Bhoite, S. P ; Hong, C. K ; Sharif University of Technology
    Wiley-VCH Verlag  2019
    Abstract
    The quality of perovskite films plays a crucial role in improving the optoelectronic properties and performance of perovskite solar cells (PSCs). Herein, high-quality CsxFA1−xPbI3 perovskite films with different compositions (x = 0, 5, 10, and 15) are achieved by controlling the amount of cesium chloride (CsCl) in the respective FAPbI3 precursor solution. The effects of CsCl addition on the morphological and optoelectronic properties of the resulting perovskite films and on the performance of the corresponding devices are systematically studied. Introduction of CsCl into FAPbI3 shows a great potential to stabilize the α-FAPbI3 perovskite phase by forming CsxFA1−xPbI3 films with improved... 

    A rare type of Rhenium(I) diimine complexes with unsupported coordinated phosphine oxide ligands: Synthesis, Structural Characterization, Photophysical and theoretical study

    , Article European Journal of Inorganic Chemistry ; Volume 2019, Issue 39-40 , 2019 , Pages 4350-4357 ; 14341948 (ISSN) Nayeri, S ; Jamali, S ; Pavlovskiy, V. V ; Porsev, V. V ; Evarestov, R. A ; Kisel, K. S ; Koshevoy, I. O ; Shakirova, J. R ; Tunik, S. P ; Sharif University of Technology
    Wiley-VCH Verlag  2019
    Abstract
    This paper presents synthesis and photophysical investigation of a very rare type of the ReI diimine complexes, [Re(diimine)(CO)3(OPR3)]+, R = Ph, Cy; diimine – phenanthroline and neocuproine, containing monodentate (unsupported) phosphine oxide ligands. The obtained compounds have been structurally characterized in solid phase by using XRD crystallography, which revealed unusual distortions in the pseudo octahedral rhenium environment, which may be ascribed to intramolecular interligand (phosphine oxide – diimine) interaction rather than to crystal packing effect. Optimization of the ground state structure of these molecules with the DFT method also confirmed intramolecular origin of the...