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    Nonlinear Distributed-Parameters Vibration Analysis of an AFM Microcantilever Beam in Dynamic Mode

    , Ph.D. Dissertation Sharif University of Technology Delnavaz, Aidin (Author) ; Zohoor, Hassan (Supervisor)
    Abstract
    Dynamic and vibration behavior of AFM microcantilever beam subject to the tip-sample interaction and/or contact is systematically investigated. An Euler-Bernoli microcantilever in 2D plane is considered with longitudinal and bending displacements. Inextensibility assumption and extended Hamilton’s principle is utilized to extract the single-variable integro partial equation of motion under: 1) tip-nanoparticle interactions, 2) tip-surface interactions in non-contact mode and 3) tip-surface interactions and contacts in intermittent-contact mode. Galerkin’s first mode approximation is then used to discretize the derived equations; and multiple time scales method is adopted to analyze the... 

    Boundary Stabilization and Motion Control of Flexible Crane Systems

    , Ph.D. Dissertation Sharif University of Technology Entessari, Farshid (Author) ; Alasty, Aria (Supervisor) ; Najafi Ardekany, Ali (Supervisor)
    Abstract
    In recent years, boundary control (BC) approach for distributed parameter systems and their applications has demonstrated that it can be a well-intentioned candidate for control system design. In this approach, the main focus is on the boundary actions, where the actuators are aligned on the boundaries of the media. BC may be considered as an ideal approach, especially from applied and engineering point of view, because it deals only with actuators and sensors along the boundaries. Moreover, the problem of boundary stabilization and motion control of flexible crane systems has been one of the remarkable problems for control engineers. In this research, we contemplate the boundary control... 

    Dynamic Modeling and Adaptive Controller design for Cooperative Flexible Manipulators to Grasp and Manipulation of an Object

    , M.Sc. Thesis Sharif University of Technology Hejrati, Mahdi (Author) ; Sayyaadi, Hassan (Supervisor)
    Abstract
    In a world where energy conservation is a critical topic, cooperative flexible manipulators will play an important role. Conventional robotic manipulators have been designed to have maximum stiffness to achieve both minimum vibration and good positioning accuracy of the end-effector, which causes more power consumption and reduced efficiency. Due to the high inertia of such arms, interaction with humans or sensitive environments is hazardous. On the other hand, Flexible Link Manipulators are designed to be lightweight, using lower energy and producing higher efficiency. Unfortunately, the link's flexibility increases vibrations and decreases the accuracy of the end-effector. Since, the... 

    Optimal Sensor Location for State Estimation and Monitoring of Gas Transmission Networks

    , M.Sc. Thesis Sharif University of Technology Khaladj, Nader (Author) ; Bozorgmehry Boozarjomehry, Ramin (Supervisor)
    Abstract
    Monitoring of natural gas transmission networks, is one of the necessities for efficient, safe, and economical operation of energy supply networks. In order to efficiently control and monitor the operation of gas transmission network, various states of the network (like temperature, pressure, and flow) should be available. Among these states, some can be easily measured, and the rest should be estimated based on these measurements throughout the network. In this project, an algorithm to obtain near optimal locations of various measuring devices has been proposed. Furthermore, a method for estimation of the states of transmission network based on these measurements and Machine Learning has... 

    Identification Of Surrogate Models for Hybrid Distributed Parameters Systems Using Machine Learning Algorithms

    , M.Sc. Thesis Sharif University of Technology Taghizadeh, Mohammad Javad (Author) ; Bozorgmehry Boozarjomehry, Ramin (Supervisor)
    Abstract
    In various industries, particularly in the process industries, computational fluid dynamics (CFD) stands as the predominant method for simulating distributed systems. In these methods, discretization of system geometry and partial differential equations is necessary, resulting in a system of algebraic or ordinary differential equations, or a combination thereof. The significant computational demands arising from the extensive number of equations derived from dynamic system simulations highlight the necessity for substantial processing and computing power. The objective of this project is to reduce the computational load associated with solving these equations. It focuses on utilizing machine... 

    Boundary control of a vertical nonlinear flexible manipulator considering disturbance observer and deflection constraint with torque and boundary force feedback signals

    , Article International Journal of Systems Science ; Volume 53, Issue 4 , 2022 , Pages 704-725 ; 00207721 (ISSN) Entessari, F ; Najafi Ardekany, A ; Alasty, A ; Sharif University of Technology
    Taylor and Francis Ltd  2022
    Abstract
    In this paper, boundary control (BC) laws are designed to find a BC solution for a single-link nonlinear vertical manipulator to suppress the link’s transverse vibrations and control the rigid body nonlinear large rotating motion. The governing equations of motions and boundary conditions, which all consist of a set of PDEs and ODEs have been derived based on the Hamilton principle. It is desired to regulate large angular orientation, suppress the flexible link’s transverse vibrations and compensate the boundary disturbance simultaneously. The amount of elastic boundary vibration has remained within the constraint range. By considering novel Barrier-Integral Lyapunov functional in order to... 

    Multi-objective optimization of functionally graded materials, thickness and aspect ratio in micro-beams embedded in an elastic medium

    , Article Structural and Multidisciplinary Optimization ; Volume 58, Issue 1 , July , 2018 , Pages 265-285 ; 1615147X (ISSN) Taati, E ; Sina, N ; Sharif University of Technology
    Springer Verlag  2018
    Abstract
    Optimal design of micron-scale beams as a general case is an important problem for development of micro-electromechanical devices. For various applications, the mechanical parameters such as mass, maximum deflection and stress, natural frequency and buckling load are considered in strategies of micro-manufacturing technologies. However, all parameters are not of equal importance in each operating condition but multi-objective optimization is able to select optimal states of micro-beams which have desirable performances in various micro-electromechanical devices. This paper provides optimal states of design variables including thickness, distribution parameter of functionally graded... 

    Nonlinear dynamics of nano-resonators: an analytical approach

    , Article Microsystem Technologies ; Volume 22, Issue 9 , 2016 , Pages 2259-2271 ; 09467076 (ISSN) Maani Miandoab, E ; Nejat Pishkenari, H ; Yousefi Koma, A ; Sharif University of Technology
    Springer Verlag 
    Abstract
    Prior to the design and fabrication of MEMS/NEMS devices, analysis of static and dynamic behaviors of these systems is necessary. In the present study, the nonlinear dynamic behavior of micro- and nano-mechanical resonators is investigated and classified based on the resonator’s physical parameters for first time. The Galerkin method is used to convert the distributed-parameter model to a nonlinear ordinary differential equation where mid-plane stretching, axial stress, DC electrostatic and AC harmonic voltages are taken into account. To obtain the analytical frequency response of the micro resonator near its primary resonance, the second order multiple scales method is applied to the... 

    Preclinical evaluation of 188 Re-HYNIC-PSMA as a novel therapeutic agent

    , Article Journal of Radioanalytical and Nuclear Chemistry ; Volume 331, Issue 2 , 2022 , Pages 841-849 ; 02365731 (ISSN) Hadisi, M ; Vosoughi, N ; Yousefnia, H ; Bahrami-Samani, A ; Zolghadri, S ; Vosoughi, S ; Alirezapour, B ; Sharif University of Technology
    Springer Science and Business Media B.V  2022
    Abstract
    In this study, optimized preparation, quality control, cell assessments and biostribution of 188Re-HYNIC-PSMA in normal rats and tumor bearing mice are studied. Optimized conditions for radiolabeling were evaluated and radiochemical purity (> 99%) was investigated using ITLC and HPLC methods. 188Re-HYNIC-PSMA was stable both in PBS (4 °C) and in human serum (37 °C) even after 48 h. The results showed the complex was cleared from the blood very fast via urinary track. This new radiolabeled compound has a high potential to be considered as an agent for the treatment of patients with PSMA expressing tumors however more biological studies are still needed. © 2022, Akadémiai Kiadó, Budapest,... 

    Thermal optimization of the continuous casting process using distributed parameter identification approach—controlling the curvature of solid-liquid interface

    , Article International Journal of Advanced Manufacturing Technology ; Volume 94, Issue 1-4 , 2018 , Pages 1101-1118 ; 02683768 (ISSN) Tavakoli, R ; Sharif University of Technology
    Springer London  2018
    Abstract
    Thermal optimization of the vertical continuous casting process is considered in the present study. The goal is to find the optimal distribution of the temperature and interfacial heat transfer coefficients corresponding to the primary and secondary cooling systems, in addition to the pulling speed, such that the solidification along the main axis of strand approaches to the unidirectional solidification mode. Unlike many thermal optimization of phase change problems in which the desirable (target) temperature, temperature gradient, or interface position are assumed to be a priori known, a desirable shape feature of the freezing interface (not its explicit position) is assumed to be known in... 

    Estimating the parameters of mixed shifted negative binomial distributions via an EM algorithm

    , Article Scientia Iranica ; Volume 26, Issue 1E , 2019 , Pages 571-586 ; 10263098 (ISSN) Varmazyar, M ; Akhavan Tabatabaei, R ; Salmasi, N ; Modarres, M ; Sharif University of Technology
    Sharif University of Technology  2019
    Abstract
    Discrete Phase-Type (DPH) distributions have one property that is not shared by Continuous Phase-Type (CPH) distributions, i.e., representing a deterministic value as a DPH random variable. This property distinguishes the application of DPH in stochastic modeling of real-life problems, such as stochastic scheduling, in which service time random variables should be compared with a deadline that is usually a constant value. In this paper, we consider a restricted class of DPH distributions, called Mixed Shifted Negative Binomial (MSNB), and show its flexibility in producing a wide range of variances as well as its adequacy in fitting fat-tailed distributions. These properties render MSNB... 

    Exponential stabilization of flexural sway vibration of gantry crane via boundary control method

    , Article JVC/Journal of Vibration and Control ; Volume 26, Issue 1-2 , 2020 , Pages 36-55 Entessari, F ; Najafi Ardekany, A ; Alasty, A ; Sharif University of Technology
    SAGE Publications Inc  2020
    Abstract
    This paper aims to develop a boundary control solution for complicated gantry crane coupled motions. In addition to the large angle sway motion, the crane cable has a flexural transverse vibration. The Hamilton principle has been utilized to derive the governing partial differential equations of motion. The control objectives which are sought include: moving the payload to the desired position; reducing the payload swing with large sway angle; and finally suppressing the cable transverse vibrations in the presence of boundary disturbances simultaneously. These simultaneous boundary control objectives make the problem challenging. The proposed control approach is based on the original... 

    An empirical study on TCP flow interarrival time distribution for normal and anomalous traffic

    , Article International Journal of Communication Systems ; Volume 30, Issue 1 , 2017 ; 10745351 (ISSN) Arshadi, L ; Jahangir, A. H ; Sharif University of Technology
    John Wiley and Sons Ltd  2017
    Abstract
    In this paper, we study the effects of anomalies on the distribution of TCP flow interarrival time process. We show empirically that despite the variety of data networks in size, number of users, applications, and load, the interarrival times of normal flows comply with the Weibull distribution, whereas specific irregularities (anomalies) causes deviations from the distribution. We first estimate the scale and shape parameters and then check the discrepancy of the data from a Weibull distribution with the estimated parameters. We also utilize the Weibull counting model to recheck the conformance of small flow interarrival times with the distribution. We perform our experiments on a diverse... 

    LMI-based cooperative distributed model predictive control for Lipschitz nonlinear systems

    , Article Optimal Control Applications and Methods ; Volume 41, Issue 2 , 2020 , Pages 487-498 Adelipour, S ; Haeri, M ; Sharif University of Technology
    John Wiley and Sons Ltd  2020
    Abstract
    In this paper, a distributed model predictive control is proposed to control Lipschitz nonlinear systems. The cooperative distributed scheme is considered where a global infinite horizon objective function is optimized for each subsystem, exploiting the state and input information of other subsystems. Thus, each control law is obtained separately as a state feedback of all system's states by solving a set of linear matrix inequalities. Due to convexity of the design, convergence properties at each iteration are established. Additionally, the proposed algorithm is modified to optimize only one control input at a time, which leads to a further reduction in the computation load. Finally, two... 

    Model reduction of a solid oxide fuel cell (SOFC) for control purposes

    , Article Iranian Journal of Chemistry and Chemical Engineering ; Volume 32, Issue 3 , 2013 , Pages 91-105 ; 10219986 (ISSN) Mirabi, E ; Pishvaie, M. R ; Abbasian, M ; Sharif University of Technology
    Jihad Danishgahi  2013
    Abstract
    Fuel cells belong to an avant-garde technology family for a wide variety of applications including micro-power, transportation power, stationary power for buildings and other distributed generation applications. The first objective of this contribution is to find a suitable reduced model of a Solid Oxide Fuel Cell (SOFC). The derived reduced model is then used to design a state estimator. In the first step, the distributed model of the SOFC that is derived using the first principle balance equations is solved by the method of lines. Since this model is too complex and sluggish for real-time applications, a representation of this model with lower number of states and good accuracy is needed.... 

    Distributed and decentralized state estimation in gas networks as distributed parameter systems

    , Article ISA Transactions ; Volume 58 , September , 2015 , Pages 552-566 ; 00190578 (ISSN) Ahmadian Behrooz, H ; Bozorgmehry Boozarjomehry, R ; Sharif University of Technology
    ISA - Instrumentation, Systems, and Automation Society  2015
    Abstract
    In this paper, a framework for distributed and decentralized state estimation in high-pressure and long-distance gas transmission networks (GTNs) is proposed. The non-isothermal model of the plant including mass, momentum and energy balance equations are used to simulate the dynamic behavior. Due to several disadvantages of implementing a centralized Kalman filter for large-scale systems, the continuous/discrete form of extended Kalman filter for distributed and decentralized estimation (DDE) has been extended for these systems. Accordingly, the global model is decomposed into several subsystems, called local models. Some heuristic rules are suggested for system decomposition in gas pipeline... 

    A hybrid implementation of the TLM method for the analysis of high frequency interference

    , Article 2003 Asia-Pacific Conference on Applied Electromagnetics, APACE 2003, 12 August 2003 through 14 August 2003 ; 2003 , Pages 124-127 ; 0780381297 (ISBN); 9780780381292 (ISBN) Attari, R ; Barkeshli, K ; Ndagijimana, F ; Dansou, J ; Sharif University of Technology
    Institute of Electrical and Electronics Engineers Inc  2003
    Abstract
    An efficient hybrid method is presented for the analysis of the interference phenomenon in high frequency communication circuits. The method is based on the transmission line matrix (TLM) method, augmented with a time domain integral formulation using the free space Green's function to account for the radiation of equivalent sources on boundary surfaces. The method is highly effective in reducing the dispersion effects in the TLM method and drastically reduces its computational intensity. © 2003 IEEE  

    Robust stability and performance analysis of positive systems using linear programming

    , Article 24th Mediterranean Conference on Control and Automation, 21 June 2016 through 24 June 2016 ; 2016 , Pages 100-105 ; 9781467383455 (ISBN) Babazadeh, M ; Nobakhti, A ; MCA ; Sharif University of Technology
    Institute of Electrical and Electronics Engineers Inc 
    Abstract
    This work presents a new necessary and sufficient condition for robust stability and robust performance of positive linear time invariant (LTI) systems with structured uncertainties. It is known that robustness analysis of LTI systems with structured uncertainties requires evaluation of structured singular value (SSV), which is known to be NP-hard. This paper shows that for positive systems, the structured singular value can be estimated efficiently using linear programming. Thus, the robustness analysis of positive systems is simplified to easily verifiable conditions that scale linearly with the dimensions of the system. This property finds great utility in analysis and synthesis of large... 

    A switching decentralized and distributed extended Kalman filter for pressure swing adsorption processes

    , Article International Journal of Hydrogen Energy ; Volume 41, Issue 48 , 2016 , Pages 23042-23056 ; 03603199 (ISSN) Fakhroleslam, M ; Fatemi, S ; Bozorgmehry Boozarjomehry, R ; Sharif University of Technology
    Elsevier Ltd  2016
    Abstract
    A continuous-discrete Distributed and Decentralized Switching Kalman Filter (DDSKF) is designed for estimation of spatial profiles in Pressure Swing Adsorption (PSA) processes. The introduced observer is an integral part of the control strategy of hybrid systems in general and PSA systems in particular. A reduced order model is developed based on the mechanistic model of the process. The sensors are optimally located and observability of the process is studied. The proposed observer is used to estimate the spatial profiles of various states of a two-bed, six-step PSA system used for production of pure H2 from a H2–CH4 gas mixture. The spatial profiles of the system have been estimated using... 

    Estimation of 3-D pore network coordination number of rocks from watershed segmentation of a single 2-D image

    , Article Advances in Water Resources ; Volume 94 , 2016 , Pages 264-277 ; 03091708 (ISSN) Rabbani, A ; Ayatollahi, S ; Kharrat, R ; Dashti, N ; Sharif University of Technology
    Elsevier Ltd  2016
    Abstract
    In this study, we have utilized 3-D micro-tomography images of real and synthetic rocks to introduce two mathematical correlations which estimate the distribution parameters of 3-D coordination number using a single 2-D cross-sectional image. By applying a watershed segmentation algorithm, it is found that the distribution of 3-D coordination number is acceptably predictable by statistical analysis of the network extracted from 2-D images. In this study, we have utilized 25 volumetric images of rocks in order to propose two mathematical formulas. These formulas aim to approximate the average and standard deviation of coordination number in 3-D pore networks. Then, the formulas are applied...