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Total 26 records

    Robust control of LVAD based on the sub-regional modeling of the heart

    , Article Scientia Iranica ; Volume 23, Issue 6 , 2016 , Pages 2934-2943 ; 10263098 (ISSN) Ravanshadi, S ; Jahed, M ; Sharif University of Technology
    Sharif University of Technology  2016
    Abstract
    Left Ventricular Assist Devices (LVAD) have received renewed interest as a bridge-to-transplantation as well as a bridge-to-recovery device. Ironically, reports of malfunction and complications have hindered the growth of this device. In particular, the main concern is LVAD's susceptibility to excessive backlash and suction as a result of ows that are either too low or high, respectively. This study utilizes a well-established physiological model of the cardiovascular system as a reliable platform to study a proposed adaptive robust controller for a rotary motor based LVAD which overcomes such shortcomings. Proposed controller performance is evaluated by comparing simulated natural heart... 

    Integrity checking for aggregate queries

    , Article IEEE Access ; Volume 9 , 2021 , Pages 74068-74084 ; 21693536 (ISSN) Dolatnezhad Samarin, S ; Amini, M ; Sharif University of Technology
    Institute of Electrical and Electronics Engineers Inc  2021
    Abstract
    With the advent of cloud computing and Internet of Things and delegation of data collection and aggregation to third parties, the results of the computations should be verified. In distributed models, there are multiple sources. Each source creates authenticators for the values and sends them to the aggregator. The aggregator combines the authenticated values and creates a verification object for verifying the computation/aggregation results. In this paper, we propose two constructions for verifying the results of countable and window-based countable functions. These constructions are useful for aggregate functions such as median, max/min, top-k/first-k, and range queries, where the... 

    Adaptive asymptotic tracking control of uncertain fractional-order nonlinear systems with unknown quantized input and control directions subject to actuator failures

    , Article JVC/Journal of Vibration and Control ; 2021 ; 10775463 (ISSN) Sabeti, F ; Shahrokhi, M ; Moradvandi, A ; Sharif University of Technology
    SAGE Publications Inc  2021
    Abstract
    This article addresses an adaptive backstepping control design for uncertain fractional-order nonlinear systems in the strict-feedback form subject to unknown input quantization, unknown state-dependent control directions, and unknown actuator failure. The system order can be commensurate or noncommensurate. The total number of failures is allowed to be infinite. The Nussbaum function is used to deal with the problem of unknown control directions. Compared with the existing results, the control gains can be functions of states and the knowledge of quantization parameters and characteristics of the actuator failure are unknown. By applying the backstepping control approach based on the... 

    An analytical method for the reliability evaluation of wind energy systems

    , Article TENCON 2005 - 2005 IEEE Region 10 Conference, Melbourne, 21 November 2005 through 24 November 2005 ; Volume 2007 , 2005 ; 21593442 (ISSN); 0780393112 (ISBN); 9780780393110 (ISBN) Ehsani, A ; Fotuhi, M ; Abbaspour, A ; Ranjbar, A. M ; Sharif University of Technology
    Institute of Electrical and Electronics Engineers Inc  2005
    Abstract
    Wind generation is one of the most successful sources of renewable energy for the production of electrical energy. The technical characteristics of wind generation make existing conventional generation models not directly applicable. This paper presents an analytical method for the reliability assessment of the flat-rated wind turbine generation systems. An example of flat rating is that of the MOD-2, a second-generation class of wind turbines. The power-velocity characteristic of the flat-rated wind turbines is employed in this paper to model the operating behavior of the installed wind turbine generators. For wind-power potential estimation, the Weibull distribution model is used. The... 

    Control of Fractional Order Systems

    , M.Sc. Thesis Sharif University of Technology Sabeti Meybod, Fatemeh (Author) ; Shahrokhi, Mohammad (Supervisor)
    Abstract
    This thesis addresses design of an adaptive tracking control of input-quantized strict-feedback fractional-order nonlinear systems with unknown control directions. The control design is achieved by using a hysteretic quantizer to avoid chattering. The main advantages of the proposed controller are: the fractional order is available for both commensurate and non-commensurate cases, the¬¬ controller design does not depend on the quantization parameters and some restrictive assumptions are relaxed. Additionally only one adaptive law has been used for the unknown control directions which leads to reduction of computational load. By utilizing the backstepping approach and based on the frequency... 

    Analysis of Temporal Stability and Transferability of Trip Distribution Models Considering Urban Development Patterns: The Case of Shiraz

    , M.Sc. Thesis Sharif University of Technology Haghighi, Mohammad (Author) ; Shafahi, Yousef (Supervisor)
    Abstract
    Trip distribution is the second step of the four-step travel demand modeling. Like other travel demand models, the most important objective of trip distribution models generation is forecasting the travel data of a year in the future. On the one hand, extensive changes in cities’ urban structures and people’s travel behavior during the years brings up the essential question of how temporally stable and transferable trip distribution models are? This question becomes even more important when the more complex structure of trip distribution models compared to models such as trip generation is considered. On the other hand, it is logical to assume that the consideration of the effects of urban... 

    Bubble size distribution in two-dimensional gas-solid fluidized beds

    , Article Industrial and Engineering Chemistry Research ; Volume 51, Issue 18 , 2012 , Pages 6571-6579 ; 08885885 (ISSN) Movahedirad, S ; Molaei Dehkordi, A ; Banaei, M ; Deen, N. G ; Van Sint Annaland, M ; Kuipers, J. A. M ; Sharif University of Technology
    2012
    Abstract
    In this article, the digital image analysis (DIA) technique has been used to study the bubble size and bubble size distribution evolution in a pseudo-two-dimensional gas-solid fluidized bed. In addition, a numerical discrete bubble model (DBM) based on the bubble-bubble interactions was developed and the model predictions were compared with the experimental data. The developed model can predict the bubble size and bubble size distribution through the bed height and the lateral distribution of bubbles. Comparison between model predictions and the result of DIA measurements shows that bubble breakage has a significant effect on the bubble size distribution especially at heights far from the... 

    Distributed model predictive control with hierarchical architecture for communication: application in automated irrigation channels

    , Article International Journal of Control ; Volume 89, Issue 8 , 2016 , Pages 1725-1741 ; 00207179 (ISSN) Farhadi, A ; Khodabandehlou, A ; Sharif University of Technology
    Taylor and Francis Ltd 
    Abstract
    This paper is concerned with a distributed model predictive control (DMPC) method that is based on a distributed optimisation method with two-level architecture for communication. Feasibility (constraints satisfaction by the approximated solution), convergence and optimality of this distributed optimisation method are mathematically proved. For an automated irrigation channel, the satisfactory performance of the proposed DMPC method in attenuation of the undesired upstream transient error propagation and amplification phenomenon is illustrated and compared with the performance of another DMPC method that exploits a single-level architecture for communication. It is illustrated that the DMPC... 

    Coverage analysis of finite cellular networks: A stochastic geometry approach

    , Article 2018 Iran Workshop on Communication and Information Theory, IWCIT 2018, 25 April 2018 through 26 April 2018 ; 2018 , Pages 1-5 ; 9781538641491 (ISBN) Azimi Abarghouyi, S. M ; Makki, B ; Haenggi, M ; Nasiri Kenari, M ; Svensson, T ; Sharif University of Technology
    Institute of Electrical and Electronics Engineers Inc  2018
    Abstract
    This paper develops a tractable modeling and analysis framework for finite cellular wireless networks using stochastic geometry. Defining finite homogeneous Poisson point processes to model the number and locations of access points in a confined region, we study the coverage probability for an arbitrarily-located reference user that is served by the closest access point. The distance distribution and the Laplace transform (LT) of the interference are derived. We also derive a closed-form lower bound on the LT of the interference. Our analyses reveal that a higher path loss exponent improves the coverage probability and that there is a location where the coverage probability is maximized. ©... 

    Game theory meets distributed model predictive control in vehicle-to-grid systems

    , Article 11th International Conference on Electrical and Electronics Engineering, ELECO 2019, 28 November 2019 through 30 November 2019 ; 2019 , Pages 764-768 ; 9786050112757 (ISBN) Karimi, A ; Haeri, M ; Sharif University of Technology
    Institute of Electrical and Electronics Engineers Inc  2019
    Abstract
    Electric Vehicles (EVs) will be used rampantly in future transportation system. Although the uncontrolled charging of these EVs will be threatening for the stability of the grid, a compatible energy trading policy may provide beneficial services to the grid as well as preserving the sustainability of the system. In this paper, by taking advantage of block rate tariff, a wholesale pricing policy is introduced. A multi-objective approach is utilized to address the cost reduction and load leveling services concurrently. Due to the high computational complexity of a centralized problem, a game theoretic approach is exerted in order to design decentralized controllers for EVs. Moreover, an MPC... 

    Visibility testing and counting for uncertain segments

    , Article Theoretical Computer Science ; Volume 779 , 2019 , Pages 1-7 ; 03043975 (ISSN) Abam, M. A ; Alipour, S ; Ghodsi, M ; Mahdian, M ; Sharif University of Technology
    Elsevier B.V  2019
    Abstract
    We study two well-known planar visibility problems, namely visibility testing and visibility counting, in a model where there is uncertainty about the input data. The standard versions of these problems are defined as follows: we are given a set S of n segments in R 2 , and we would like to preprocess S so that we can quickly answer queries of the form: is the given query segment s∈S visible from the given query point q∈R 2 (for visibility testing) and how many segments in S are visible from the given query point q∈R 2 (for visibility counting). In our model of uncertainty, each segment may or may not exist, and if it does, it is located in one of finitely many possible locations, given by a... 

    3D distributed modeling of trolling-mode AFM during 2D manipulation of a spherical cell

    , Article Journal of Nanoparticle Research ; Volume 23, Issue 4 , 2021 ; 13880764 (ISSN) Mohammadi, S.Z ; Nejat Pishkenari, H ; Mohammadi Moghaddam, M ; Sharif University of Technology
    Springer Science and Business Media B.V  2021
    Abstract
    In this study, a general 3D distributed modeling of Trolling-Mode AFM (TR-AFM) as a nanorobot is presented to analyze the 2D manipulation process of a spherical cell. To this aim, the analysis is categorized into 3 sections. In the first section, 6 deformations of TR-AFM are taken into account, and the standard model of the system is obtained. Moreover, the system is simulated in ANSYS Workbench. The results of modal and transient analyses of the system from both analytical and software methods reveal high agreement, which confirms the accuracy of the presented analytical model. In the second section, by utilizing the 3D derived model, displacement of a spherical yeast single cell (W303)... 

    Adaptive asymptotic tracking control of uncertain fractional-order nonlinear systems with unknown quantized input and control directions subject to actuator failures

    , Article JVC/Journal of Vibration and Control ; Volume 28, Issue 19-20 , 2022 , Pages 2625-2641 ; 10775463 (ISSN) Sabeti, F ; Shahrokhi, M ; Moradvandi, A ; Sharif University of Technology
    SAGE Publications Inc  2022
    Abstract
    This article addresses an adaptive backstepping control design for uncertain fractional-order nonlinear systems in the strict-feedback form subject to unknown input quantization, unknown state-dependent control directions, and unknown actuator failure. The system order can be commensurate or noncommensurate. The total number of failures is allowed to be infinite. The Nussbaum function is used to deal with the problem of unknown control directions. Compared with the existing results, the control gains can be functions of states and the knowledge of quantization parameters and characteristics of the actuator failure are unknown. By applying the backstepping control approach based on the... 

    A new algorithm for fault location on transmission lines

    , Article 2009 IEEE Power and Energy Society General Meeting, PES '09, Calgary, AB, 26 July 2009 through 30 July 2009 ; 2009 ; 9781424442416 (ISBN) Shiroei, M ; Daniar, S ; Akhbari, M ; Sharif University of Technology
    IEEE  2009
    Abstract
    In this paper, a new algorithm for fault detection/location on transmission line based on linear state estimation is presented. The proposed technique uses phasor measurements from PMU's. Fault location and voltage of fault point are added as the new state variables in a linear state estimator based on PMU data. In addition, by using the ability of bad data identification in the state estimation, a new scheme for fault location and identification of faulted transmission line is proposed. For test and validation of the proposed algorithm, simulation results on a six bus test case are presented. ©2009 IEEE  

    FDTD analysis of distributed amplifiers based on the fully distributed model

    , Article 2007 Asia-Pacific Conference on Applied Electromagnetics, APACE2007, Melaka, 4 December 2007 through 6 December 2007 ; 2007 ; 1424414350 (ISBN); 9781424414352 (ISBN) Mirzavand, R ; Abdipour, A ; Shishegar, A. A ; Sharif University of Technology
    2007
    Abstract
    In this paper a wave approach has been introduced to study the performance of a distributed amplifier. The time domain response of a FET is obtained by means of the fully distributed model. By applying the procedure to a pi-gate GaAs MESFET, the S matrix is computed from time domain results over a frequency range of 2-20 GHz. Scattering parameters of gate and drain lines are extracted from three-dimensional FDTD simulation. The result obtained by this wave approach is compared with device lumped model and Quasi static approach of transmission line. © 2007 IEEE  

    A novel distributed model of the heart under normal and congestive heart failure conditions

    , Article Proceedings of the Institution of Mechanical Engineers, Part H: Journal of Engineering in Medicine ; Volume 227, Issue 4 , 2013 , Pages 362-372 ; 09544119 (ISSN) Ravanshadi, S ; Jahed, M ; Sharif University of Technology
    2013
    Abstract
    Conventional models of cardiovascular system frequently lack required detail and focus primarily on the overall relationship between pressure, flow and volume. This study proposes a localized and regional model of the cardiovascular system. It utilizes noninvasive blood flow and pressure seed data and temporal cardiac muscle regional activity to predict the operation of the heart under normal and congestive heart failure conditions. The analysis considers specific regions of the heart, namely, base, mid and apex of left ventricle. The proposed method of parameter estimation for hydraulic electric analogy model is recursive least squares algorithm. Based on simulation results and comparison... 

    Modeling and Calibrating the Soil Moisture and Discharge with VIC Model and SMAP Satellite Data, Saghez Station, Zarinehrood River Basin

    , M.Sc. Thesis Sharif University of Technology Karimi Yalmeh, Mohammad Reza (Author) ; Tajrishi, Masoud (Supervisor) ; Jalilvand, Ehsan (Co-Supervisor)
    Abstract
    In this thesis we evaluate VIC hydrological model’s simulated soil moisture and discharge at Saghez synoptic station, located at ZarinehRood sub basin, Urmia Lake basin in three time periods to overcome observational and satellite data scarcity in the basin. All the input files for this macro scale semi-distributed model chose from satellite data. With a multi-objective calibration algorithm called NSGA-II and utilizing Nash-Sutcliffe (NSE) and R2 as objective functions for discharge calibration and correlation coefficient and RMSE for soil calibration, the model results evaluated. As where as we didn’t have access to observational soil moisture data, we utilized SMAP satellite soil moisture... 

    Critical-Item Supply-Chain Using Agent-Based Modelling

    , M.Sc. Thesis Sharif University of Technology Malaek, Mohammad Matin (Author) ; Haji, Alireza (Supervisor)
    Abstract
    One of the crucial matters in the area of Supply Chain Management is the ability of a supply chain to act and react under different circumstances. A helpful tool to understand the supply chain is simulation modeling. With the help of simulation modeling, we can provide the opportunity for the agents in a model to perform based on the defined environment.In the current research, a complete literature review is performed on the topics of supply chain planning and various distribution models and algorithms. With the focus on the vaccine as a critical item, we propose a model to distribute vaccines based on the degree of agents, and we realize that vaccine distribution, while facing huge demand... 

    Distributed Robust Model Predictive Control for Multi-zone Air Conditioning Systems

    , M.Sc. Thesis Sharif University of Technology Azim Mezerji, Hojat (Author) ; Moradi, Hamed (Supervisor)
    Abstract
    Optimizing the energy consumption of air conditioning systems has gained great importance in recent years. In addition, maintaining thermal comfort and air quality in buildings is important. The multi-evaporator air conditioning system, which is a direct expansion system, shows the complex and distributed structure of air conditioning systems due to the thermal connection between zones and its large scale. The modeling of these systems is associated with uncertainties. Therefore, designing a suitable control structure for multi-zone systems is very important to achieve optimal energy consumption and maintain comfort conditions in the presence of uncertainty. Model predictive control has been... 

    Modelling of fischer-tropsch synthesis in a fluidized bed reactor

    , Article Advanced Materials Research ; Volume 586 , 2012 , Pages 274-281 ; 10226680 (ISSN) ; 9783037855232 (ISBN) Kazemeini, M ; Maleki, R ; Fattahi, M
    2012
    Abstract
    The FT reaction involves the conversion of syngas which is derived from natural gas or coal to different kinds of products according to the operating conditions and the type of the catalyst. In other words, it is a practical way to convert solid fuel (coal) and natural gas to various hydrocarbons (C1-C60) and oxygenates such as alkanes, alkenes etc. The main products of the reaction are naphtha and gasoline. This paper deals with developing a proper product distribution model for FT process using the appropriate kinetic model, optimizing the respective rate constants while applying them in product distribution equations. The results revealed only 8.09% deviations from the olefin experimental...