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    Voltage regulation in private environments: opportunity or threat

    , Article IEEE Transactions on Power Delivery ; 2017 ; 08858977 (ISSN) Gharebaghi, S ; Safdarian, A ; Sharif University of Technology
    Institute of Electrical and Electronics Engineers Inc  2017
    Abstract
    Historically, the general target of affecting demand via voltage regulation was conservation, i.e., reducing peak demand and/or accumulated energy. In private environments however, profit maximization may take place of conservation, regardless of the social welfare and consumers' costs. This letter aims at highlighting the effectiveness of voltage regulation as a measure to maximize utilities' profit. The new strategy can indeliberately cause more payments for customers. The letter simulates different cases which reveal importance of the role regulatory bodies have to play to prevent unethical actions in private environments. IEEE  

    Optimal Placement of Remote Control Switches to Reduce Network Losses and Enhance Service Quality

    , M.Sc. Thesis Sharif University of Technology Gharebaghi, Sina (Author) ; Safdarian, Amir (Supervisor)
    Abstract
    Nowadays, improvement in operational condition of distribution networks considering daily growth in electrical energy usage with financial limits appears as a huge challenge for network operators. Under these kind of circumstances, operators need to have efficient and inexpensive plans more than ever. Considering high share of power losses in overall pro-duced power, utilities always tried to minimize losses in Iran and other points of world. In addition, numerous equipment in distribution networks compared with the transmission level, impose high costs to reliability plans. Therefore, reliability improvement plans have been paid low attention by distribution network operators. This lower... 

    Identification androbust control of a flapping wing system using fuzzy wavelet neural networks

    , Article Unmanned Systems ; 2023 ; 23013850 (ISSN) Mostafa Gharebaghi, S ; Banazadeh, A ; Sharif University of Technology
    World Scientific  2023
    Abstract
    This study explores the utilization of a fuzzy wavelet neural network for identifying the dynamic behavior of a time periodic flapping wing system. Additionally, we propose a combination of adaptive sliding mode learning algorithm and genetic algorithm to effectively adjust the network parameters. The identification process specifically focuses on the longitudinal mode and involves three inputs and three outputs. To generate the necessary input and output data for the network, we have developed a simulation platform using MATLAB software. The accuracy of the data has been validated through comparison with ADAMS simulations. Moreover, we have ensured the stability of the learning algorithm by... 

    Optimal network configuration considering network losses and service reliability

    , Article IEEE Proceedings 2017 Smart Grid Conference, SGC 2017 ; Volume 2018-January , 2018 , Pages 1-6 ; 9781538642795 (ISBN) Gharebaghi, S ; Izadi, M ; Safdarian, A ; Sharif University of Technology
    Institute of Electrical and Electronics Engineers Inc  2018
    Abstract
    Distribution networks are designed in loop structure, while they are operated as radial networks. In this regard, the location of normally open (NO) switches is usually determined by either minimizing real power losses or maximizing the reliability level. However, considering both losses and reliability in the decision making procedure may lead to a better solution. To do so, this paper proposes a mathematical model to find the optimal configuration of NO switches such that losses and reliability are optimized. The multi-objective model is scrutinized via weighted sum approach to achieve a single-objective model. The model is formulated in mixed integer quadratically constrained programming... 

    A linear model for AC power flow analysis in distribution networks

    , Article IEEE Systems Journal ; Volume 13, Issue 4 , 2019 , Pages 4303-4312 ; 19328184 (ISSN) Gharebaghi, S ; Safdarian, A ; Lehtonen, M ; Sharif University of Technology
    Institute of Electrical and Electronics Engineers Inc  2019
    Abstract
    The standard power flow (PF) equations are nonlinear, and their integration in the optimal PF (OPF) problem leads to a nonconvex hard-to-solve model. To attack the issue, this paper presents a linear PF model wherein real and imaginary parts of nodal voltages are variables. In the model, loads are interpreted via ZIP model including constant impedance, constant current, and constant power components. To preserve linearity of the model, the complex power is represented via a quadratic function of the hosting node voltage. The function coefficients are derived via curve fitting approaches. Since the model is linear, its solution does not need repetition and can be effectively integrated in the... 

    Study the Books of Science and Physics Education in Iran from the Perspective of Current Philosophy of Science

    , M.Sc. Thesis Sharif University of Technology Nayyerhoda, Taha Reza (Author) ; Golshani, Mahdi (Supervisor)
    Abstract
    In this research, I intend to case study formal education textbook in Iran that responsible for educate science in elementary school or educate physics in high school that to study the situation of education in this field of knowledge in Iran. The method of this research is study the text of textbook and find instance that somehow build philosophy of science assumption in students’ minds. In the following, I categorize these founded phrase that find in all related books, following the current philosophy of science theories. In the end of this research, I present an explanation of these authors textbook’s assumption  

    Application of Artificial Neural Networks for Identification and Modeling of Time Periodic Flapping Wing Systems

    , M.Sc. Thesis Sharif University of Technology Mostafa Gharebaghi, Shabnam (Author) ; Banazadeh, Afshin (Supervisor)
    Abstract
    For complex systems, it is difficult to obtain an accurate model of system dynamics using physical laws. Therefore, one of the most common solutions is to use system identification techniques. Flapping wings are one of the most challenging systems in the engineering world. In this study, we use a fuzzy wavelet neural network to identify time periodic flapping wing systems. In order to extract network’s input and output information, we use analytical simulation using MATLAB software. After validating the input and output information of the system with the help of the ADAMS software, the identification process of the flapping wing system is performed in longitudinal and lateral-directional... 

    Conceptual Design and Performance Simulation of a Vibration Measurement Device for Modal Analysis of Rotating Cylindrical Shells

    , M.Sc. Thesis Sharif University of Technology Gharebaghi, Taha (Author) ; Saadat Foumani, Mahmoud (Supervisor)
    Abstract
    Cylindrical shells play an important role in a wide range of engineering applications such as mechanics, aerospace, marine engineering, and nuclear applications due to their high load-carrying capacity, light structure, and economic advantages. Because these structures are often made of high lengths and thin sheets, they are very prone to vibration, especially under the conditions that they play a role in the rotating state, which can cause failure. For the reasons mentioned, the vibration analysis of rotating cylindrical shells will be essential in engineering designs. In the present study, after introducing general concepts regarding the analysis of structural vibrations, previous research... 

    Impacts of bad data injection on power systems security: intruder point of view

    , Article 2017 IEEE Smart Grid Conference, SGC 2017, 20 December 2017 through 21 December 2017 ; Volume 2018-January , March , 2018 , Pages 1-6 ; 9781538642795 (ISBN) Gharebaghi, S ; Hosseini, S. H ; Izadi, M ; Safdarian, A ; Sharif University of Technology
    Institute of Electrical and Electronics Engineers Inc  2018
    Abstract
    Nowadays communication and monitoring systems play an important role in power systems security. However, these systems are exposed to bad data injection through attackers. This paper is aimed to propose a priority order list of attacked buses in order to be fully informed about the attacker decision. To do so, system security is evaluated through two well-known risk indices including under voltage risk index and overloading risk index. A genetic algorithm (GA) is employed to determine the most severe attack for each of the security indices. The effectiveness and accuracy of the proposed model are scrutinized through simulations on the IEEE 30-bus network. The paper reveals that knowing the... 

    An investigation on the effect of cement and silica fume on properties of self-compacting concrete

    , Article Proceedings of the 13th East Asia-Pacific Conference on Structural Engineering and Construction, EASEC 2013 ; September , 2013 Moshiri, F ; Atashnama, A ; Panahi, M ; Gharebaghi, R ; Mahlouji, J ; Sharif University of Technology
    Hokkaido University collection of Scholarly Academic Papers, HUSCAP  2013
    Abstract
    Self-Compacting concrete (SCC) is identified as a high performance concrete with the ability of self compaction, using its own weight without any external vibration. SCC is able to fill congested area and voids, even in highly reinforced concrete members whilst it flows without segregation. The fresh properties of SCC such as workability can be determined using different tests including slump-flow, J ring, V-funnel, U box, L box, GTM and column technique. In this paper the effect of different amount of cementitious material, silica fume and W/C ratios on workability and compressive strength of SCC are investigated. The results indicate that the workability of mixtures is reduced by... 

    Error estimation, adaptivity and data transfer in enriched plasticity continua to analysis of shear band localization

    , Article Applied Mathematical Modelling ; Volume 31, Issue 6 , 2007 , Pages 983-1000 ; 0307904X (ISSN) Khoei, A. R ; Asil Gharebaghi, S ; Tabarraie, A. R ; Riahi, A ; Sharif University of Technology
    2007
    Abstract
    In this paper, an adaptive FE analysis is presented based on error estimation, adaptive mesh refinement and data transfer for enriched plasticity continua in the modelling of strain localization. As the classical continuum models suffer from pathological mesh-dependence in the strain softening models, the governing equations are regularized by adding rotational degrees-of-freedom to the conventional degrees-of-freedom. Adaptive strategy using element elongation is applied to compute the distribution of required element size using the estimated error distribution. Once a new mesh is generated, state variables and history-dependent variables are mapped from the old finite element mesh to the... 

    Detection of High Frequency Oscillations from ECoG Recordings in Epileptic Patients

    , M.Sc. Thesis Sharif University of Technology Gharebaghi Asl, Fatemeh (Author) ; Hajipour, Sepideh (Supervisor) ; Sinaei, Farnaz (Co-Supervisor)
    Abstract
    The processing of brain signals, including the electrocorticogram (ECoG) signal, is widely used in the investigation of neurological diseases. Conventionally, the ECoG signal has frequency components up to the range of 80 Hz. Studies have proven that in some conditions, such as epilepsy, the brain signal includes frequency components higher than 80 Hz, which are called high-frequency oscillations (HFO). Therefore, HFOs are recognized as a biomarker for epilepsy. The aim of this thesis is to review the previous methods of detecting HFOs and to present new methods with greater efficiency in the direction of diagnosis or treatment of epileptic patients. For this purpose, we used the ECoG data... 

    Deformation Analysis of Magnetic Elastomers using Finite Element Method

    , M.Sc. Thesis Sharif University of Technology Norouzi, Faezeh (Author) ; Naghdabadi, Reza (Supervisor) ; Sohrabpour, Saeed (Supervisor) ; Goudarzi, Taha (Co-Advisor)
    Abstract
    Magnetic elastomers are smart materials that consist of a combination of elastomeric matrix and magnetic particles. The mechanical and magnetic properties of this materials are changed by Applying an external magnetic field. The presence of an external magnetic field can cause these elastomers deform largely.Significant deformations of the magnetic elastomers, has made them suitable for a wide range of applications. The aim of this project is to solve the governing equations of magnetic elastomers with finite element method. Since there are no suitable models for the behavior of these elastomers in the commercial softwares, magnetic field module and solid mechanics module should be coupled... 

    Studying the Wisdom of Crowd Through Large-Scale Experiment & Statistical Simulations

    , M.Sc. Thesis Sharif University of Technology Nasiri Garabolagh, Mahdi (Author) ; Ejtehadi, Mohammad Reza (Supervisor) ; Yaseri, Taha (Co-Supervisor)
    Abstract
    In this thesis, we have tried to study one of the most well known collective behavior phenomena known as the Wisdom of the crowd, from the perspective of statistical physics. In recent decades with the appearance of Social Networks and mass media, collective social phenomena have become a critical topic in the life of every human being. In the Wisdom of crowd phenomenon, the overall process is to ask the crowd’s opinion regarding a special topic and after aggregating the predicted values, the aggregated quantity is declared as the wisdom of the crowd. It has been observed that in some polls and elections, the result of the wisdom of crowd outperforms every individual of the group and in some... 

    Multiscale Multiphysics Analysis of Deformable Microwave Metasurfaces Under Large Deformations and Prototype Fabrication

    , Ph.D. Dissertation Sharif University of Technology Karimi Mahabadi, Rayehe (Author) ; Naghdabadi, Reza (Supervisor) ; Sohrabpour, Saeed (Supervisor) ; Goudarzi, Taha (Co-Supervisor)
    Abstract
    Electromagnetic metamaterials are designed artificial materials with sub-wavelength resonant inclusions. They can exhibit extraordinary properties such as negative permittivity, negative permeability, and anomalous reflection/refraction. Metasurfaces are 2D counterparts of metamaterials. Here, we proposed a framework for the multiscale multiphysics analysis of deformable metasurfaces. Nonlinear mechanical analysis (Geometry and material behavior), periodic boundary conditions, homogenization, multiscale analysis, and electromagnetic analysis are implemented in this framework. Benefiting from the framework, we proposed a multifunctional hyperelastic structured surface that can generate... 

    Modeling of Fischer-Tropsch Synthesis Reactor for GTL Process

    , M.Sc. Thesis Sharif University of Technology Al Taha Motahar, Narges Khatoon (Author) ; Khorasheh, Farhad (Supervisor) ; Taghikhani, Vahid (Supervisor)
    Abstract
    There is a need from the natural gas and energy industries to seek for an economically attractive way of converting remote gas reserves into transportable products, such as high quality fuels or petrochemicals. A possible way for the conversion of natural gas to middle distillates is based on a three-step process. Firstly, production of syngas from natural gas. Secondly,catalytic conversion of syngas into hydrocarbons, mostly parafins from C5 to C100. (Fischer-Tropsch (F-T) synthesis). Thirdly, hydrocracking of the heavy paraffinic hydrocarbons to middle distillates. The F-T synthesis step is highly exothermic. In order to control the temperature within the reactor, when considering high...