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Total 42 records

    Optimal Seismic Risk Mitigation by Prioritization of Structures for Retrofit

    , M.Sc. Thesis Sharif University of Technology Talebiyan, Hesam (Author) ; Mahsouli, Mojtaba (Supervisor)
    Abstract
    The objective of this thesis is to prioritize a portfolio of buildings for seismic retrofit. A new set of sensitivity measures is proposed to rank the buildings in accordance with the reduction in the loss of the entire portfolio. To this end, various risk measures are differentiated with respect to the cost of retrofit for each building. These risk measures are the moments of the portfolio cost probability distribution which imply the risk-neutral and risk-averse decision making. Two costs are considered: Construction cost due to retrofit and repair cost due to structural and non-structural damage. To quantify the risk, reliability methods are employed in which many interacting... 

    Introducing a Supervisory Hardware Platform for Wireless Body Area Sensor Network with an Anomaly Detection Ability

    , M.Sc. Thesis Sharif University of Technology Zare Dehabadi, Mohammad Saeed (Author) ; Jahed, Mehran (Supervisor)
    Abstract
    Wireless Body Area Network (WBAN) is a set of various physiological sensors for remote monitoring and controlling of the patient’s health status. Detection of anomalies, containing faults and physiological stresses, and distinguishing between them can eliminate the need for constant presence of specialists and decrease the occurrence of False Alarm Rate (FAR).A supervisory hardware platform for WBAN architecture is introduced and implemented in this thesis. The proposed architecture contains three sensors for recording of biomedical signals, heart rate, SpO2 and body temperature simultaneously and transmitting them to central node wirelessly through Wi-Fi standard. This proposed architecture... 

    Probabilistic Damage Models for Detailed Risk Analysis of Buildings with Reliability Methods

    , M.Sc. Thesis Sharif University of Technology Aghababaei Shahrestani, Mohammad (Author) ; Mahsuli, Mojtaba (Supervisor)
    Abstract
    A probabilistic approach to modeling the seismic damage incurred by structural and nonstructural components is developed in this study. For this purpose, Bayesian linear regression is employed to characterize the epistemic uncertainty in the model. In this approach, regressors are constructed based on the mechanics of damage. In turn, the probability distributions of the model parameters and the model error are quantified by Bayesian regression using real-life data from laboratory experiments and/or post-earthquake inspections of damaged components. The study presents the stepwise procedure of collecting the observations, quantifying the repair costs, developing model forms, performing model... 

    Fragility and Risk Analysis of Electrical Substation Equipment Using Reliability and Endurance Time Methods

    , M.Sc. Thesis Sharif University of Technology Delaviz Bonab, Arman (Author) ; Esmail Pourestekanchi, Homayoon (Supervisor)
    Abstract
    Electrical substations and its vital components such as switchgears, have experienced severe damage during recent earthquakes, followed by widespread blackouts around the world. To improve the seismic resiliency of power grids and use probabilistic decision-making frameworks, comprehensive fragility data for the different equipment is needed. The purpose of this study is to assess the vulnerability of equipment in substations and to develop fragility curves for this equipment. For this purpose, four main equipment of switchgear, namely circuit breaker, disconnect switch, current transformer and surge arrester, have been modeled in three dimensions and verified. After examining the different... 

    Operation Reserve Determination in a Power System Containing Renewable Generation

    , Ph.D. Dissertation Sharif University of Technology Ghaedi, Amir (Author) ; Abbaspour Tehranifard, Ali (Supervisor) ; Fotouhi Firouzabad, Mahmoud (Co-Advisor)
    Abstract
    Renewable energy resources, e.g. wind, solar and geothermal, experience rapid progresses in electric power industry all over the world. So, it becomes essential that these free-emission electrical energy resources be integrated in the existing generating capacity planning procedures. On the other hand, the uncertain and intermittent nature of these energies has led to some problems in their integration in power systems. The reserve requirement in a renewable-based power system is a main challenge, which has to be addressed properly. In this way, this research presents an analytical approach, based on the modified PJM method, to quantify the risk of renewable energies commitment during the... 

    Time-variant Seismic Risk Analysis of Transportation Networks Considering Economic and Socioeconomic Impacts

    , M.Sc. Thesis Sharif University of Technology Yazdi-Samadi, Mohammad Reza (Author) ; Mahsuli, Mojtaba (Supervisor) ; Samimi, Amir (Co-Advisor)
    Abstract
    This thesis targets the multidisciplinary area of time-variant seismic risk analysis of transportation networks. For this purpose, a new methodology and a library of probabilistic models are developed. Risk, in this context, denotes the probability of exceeding the sum of direct and indirect losses due to seismic events. Direct economic losses are due to the repair cost of the physical damage in the components of the network, such as bridges. The indirect losses are due to the reduced capacity of the components for traffic flow, which results in increased travel times in the network. This leads to socioeconomic losses. In this research, a reliability-based approach is adopted to carry out... 

    Reliability Assessment of DSSC devices and Optimal Placement of them with the aim of Enhancing Power System Loadability and Reliability

    , M.Sc. Thesis Sharif University of Technology Dorostkar Ghamsari, Mohammad Reza (Author) ; Fotuhi-Firuzabad, Mahmoud (Supervisor)
    Abstract
    One of the important problems in fulfilling the consumers' power demand that has been especially intensified after restructuring is transmission line congestion. To solve this problem, either new transmission lines should be constructed or the existing transmission lines should be better utilized. Construction of new transmission lines is both expensive and time consuming. Therefore, it is usually better to enhance the utilization of the existing transmission assets. FACTS devices have been introduced over the past decades to enhance power systems operation. However, wide scale deployment of them has not occurred yet due to their high initial investment cost and some other problems. In order... 

    Seismic Risk Assessment of Tehran Masonry School Buildings

    , M.Sc. Thesis Sharif University of Technology Alimohammadi, Hassan (Author) ; Bakhshi, Ali (Supervisor)
    Abstract
    This thesis aims to assess the seismic risk of the community of schools with masonry buildings in the Tehran metropolitan in the next 50 years and to prioritize the buildings of this community for seismic retrofit based on the optimal mitigation of risk of the community. Tehran is among the largest cities with the highest level of seismic risk in the world, and Masonry buildings are among the structures with poor seismic performance; Therefore, it is essential to conduct a comprehensive and accurate evaluation of the seismic risk of schools, as one of the most critical and sensitive occupancies, in this region and with this type of structure. It is also very beneficial to reduce the seismic... 

    Wind turbine productivity considering electrical subassembly reliability

    , Article Renewable Energy ; Volume 35, Issue 1 , 2010 , Pages 190-197 ; 09601481 (ISSN) Arabian-Hoseynabadi, H ; Oraee, H ; Tavner, P.J ; Sharif University of Technology
    2010
    Abstract
    This paper proposes a reliability model for the electrical subassemblies of geared wind turbine systems with induction generators. The model is derived considering the failure of main subassemblies and their parameters are calculated. A productivity comparison is performed between the selected wind turbine systems including reliability issues. Two methods of modification for variable-speed wind turbines with Doubly Fed Induction Generators (DFIG) to improve their availability are finally suggested  

    Time-variant reliability-based prediction of COVID-19 spread using extended SEIVR model and Monte Carlo sampling

    , Article Results in Physics ; Volume 26 , 2021 ; 22113797 (ISSN) Shadabfar, M ; Mahsuli, M ; Sioofy Khoojine, A ; Hosseini, V. R ; Sharif University of Technology
    Elsevier B.V  2021
    Abstract
    A probabilistic method is proposed in this study to predict the spreading profile of the coronavirus disease 2019 (COVID-19) in the United State (US) via time-variant reliability analysis. To this end, an extended susceptible-exposed-infected-vaccinated-recovered (SEIVR) epidemic model is first established deterministically, considering the quarantine and vaccination effects, and then applied to the available COVID-19 data from US. Afterwards, the prediction results are described as a time-series of the number of people infected, recovered, and dead. Upon introducing the extended SEIVR model into a limit-state function and defining the model parameters including transmission, recovery, and... 

    Spare parts management algorithm for wind farms using structural reliability model and production estimation

    , Article IET Renewable Power Generation ; Volume 10, Issue 7 , Volume 10, Issue 7 , 2016 , Pages 1041-1047 ; 17521416 (ISSN) Mani, S ; Oraee, A ; Oraee, H ; Sharif University of Technology
    Institution of Engineering and Technology 
    Abstract
    Doubly fed induction generators (DFIGs) are widely used in wind power systems; hence their reliability model is an important consideration for production assessment and economic analysis of wind energy conversion systems. However, to date mutual influences of reliability analysis, production estimations and economic assessments of wind farms have not been fully investigated. This study proposes a reliability model for DFIG wind turbines considering their subcomponent failure rates and downtimes. The proposed production estimation algorithm leads to an economic assessment for wind farms. A comprehensive spare parts management procedure is then presented in the study. As a case study,... 

    Role of outage management strategy in reliability performance of multi-microgrid distribution systems

    , Article IEEE Transactions on Power Systems ; Volume 33, Issue 3 , May , 2018 , Pages 2359-2369 ; 08858950 (ISSN) Farzin, H ; Fotuhi Firuzabad, M ; Moeini Aghtaie, M ; Sharif University of Technology
    Institute of Electrical and Electronics Engineers Inc  2018
    Abstract
    This paper develops a general framework for reliability assessment of multi-microgrid (MMG) distribution systems. It also investigates reliability impacts of coordinated outage management strategies in a MMG distribution network. According to the proposed reliability evaluation framework, which is based on sequential Monte Carlo simulation method, distribution system is divided into smaller sections/microgrids based on protection system configuration and operating measures are efficiently simulated considering different operation modes. In order to demonstrate the role of outage management strategy in reliability performance of MMG distribution systems, at first, the required features of an... 

    Reliability study of HV substations equipped with the fault current limiter

    , Article IEEE Transactions on Power Delivery ; Vol. 27, issue. 2 , 2012 , p. 610-617 ; ISSN: 8858977 Fotuhi-Firuzabad, M ; Aminifar, F ; Rahmati, I ; Sharif University of Technology
    Abstract
    Of particular interest to restrict the short-circuit level of interconnected power systems is to exploit fault current limiter (FCL) technologies. FCLs let the system planners devise new reliable and rather economical substation configurations and provide the possibility of proposing a promising cost-effective and prompt solution to the fault current over duty problem in the existing substations. This paper attempts to assess reliability of substation architectures accommodating the FCL operation and, besides, numerically investigates the FCL's impacts on the substation reliability indices. In order to clarify the proposed approach, two case studies with and without FCL are analyzed and... 

    Reliability study of HV substations equipped with the fault current limiter

    , Article IEEE Transactions on Power Delivery ; Volume 27, Issue 2 , 2012 , Pages 610-617 ; 08858977 (ISSN) Fotuhi Firuzabad, M ; Aminifar, F ; Rahmati, I ; Sharif University of Technology
    2012
    Abstract
    Of particular interest to restrict the short-circuit level of interconnected power systems is to exploit fault current limiter (FCL) technologies. FCLs let the system planners devise new reliable and rather economical substation configurations and provide the possibility of proposing a promising cost-effective and prompt solution to the fault current over duty problem in the existing substations. This paper attempts to assess reliability of substation architectures accommodating the FCL operation and, besides, numerically investigates the FCL's impacts on the substation reliability indices. In order to clarify the proposed approach, two case studies with and without FCL are analyzed and... 

    Reliability modeling of run-of-the-river power plants in power system adequacy studies

    , Article IEEE Transactions on Sustainable Energy ; Vol. 5, issue. 4 , 2014 , p. 1278-1286 ; ISSN: 19493029 Khalilzadeh, E ; Fotuhi-Firuzabad, M ; Aminifar, F ; Ghaedi, A ; Sharif University of Technology
    Abstract
    Deployment of renewable energies for the electricity generation is on the rise around the world, among which is the run-of-the-river (ROR) power plant whose output power is variable throughout the year depending on the water flow of the respective river. The inherent uncertainty associated with renewable energy resources calls for new stochastic modeling approaches to measure the impacts of using these energies on the power system performance. This paper develops an analytical reliability model for ROR power plants. The model is based on the state-space analysis and is devised with the intention of being used in adequacy studies of power systems. Failure of related components and the... 

    Reliability modeling of PMUs using fuzzy sets

    , Article IEEE Transactions on Power Delivery ; Vol. 25, issue. 4 , 2010 , p. 2384-2391 ; ISSN: 8858977 Aminifar, F ; Bagheri-Shouraki, S ; Fotuhi-Firuzabad, M ; Shahidehpour, M ; Sharif University of Technology
    Abstract
    Probabilistic analyses of a wide-area measurement system (WAMS) would require equivalent reliability models for its components which include phasor measurement units (PMUs). In this paper, the reliability modeling of PMU is proposed and the proposed model is extended to consider options for the PMU hardware. The Markov process is employed to analyze the proposed model and to present an equivalent two-state model of PMUs. Reliability parameters of PMU are estimated with major difficulties associated with limited and uncertain data. In this paper, uncertainties are taken into account to achieve more realistic estimates of PMU characteristics. Fuzzy sets along with reliability analyses and... 

    Reliability modeling of PMUs using fuzzy sets

    , Article IEEE Transactions on Power Delivery ; Volume 25, Issue 4 , August , 2010 , Pages 2384-2391 ; 08858977 (ISSN) Aminifar, F ; Bagheri Shouraki, S ; Fotuhi Firuzabad, M ; Shahidehpour, M ; Sharif University of Technology
    2010
    Abstract
    Probabilistic analyses of a wide-area measurement system (WAMS) would require equivalent reliability models for its components which include phasor measurement units (PMUs). In this paper, the reliability modeling of PMU is proposed and the proposed model is extended to consider options for the PMU hardware. The Markov process is employed to analyze the proposed model and to present an equivalent two-state model of PMUs. Reliability parameters of PMU are estimated with major difficulties associated with limited and uncertain data. In this paper, uncertainties are taken into account to achieve more realistic estimates of PMU characteristics. Fuzzy sets along with reliability analyses and... 

    Reliability modeling of multistate degraded power electronic converters with simultaneous exposure to dependent competing failure processes

    , Article IEEE Access ; Volume 9 , 2021 , Pages 67096-67108 ; 21693536 (ISSN) Samavatian, V ; Fotuhi Firuzabad, M ; Dehghanian, P ; Blaabjerg, F ; Sharif University of Technology
    Institute of Electrical and Electronics Engineers Inc  2021
    Abstract
    Depending on the application in which power electronic converters (PECs) are deployed, failure processes may endanger the desirable performance of PECs. This paper offers holistic insights on reliability modeling of PECs considering dependencies in two simultaneous failure processes, namely gradual wearing-out degradation and vibration sudden degradation. While sudden and gradual degradation processes may individually affect the useful lifetime of PECs, their mutual interdependencies could significantly accelerate the aging mechanisms. A new analytical model for reliability assessment of PECs is proposed that can capture such mutual interdependence of simultaneous failure processes. The... 

    Reliability modeling of dynamic thermal rating

    , Article IEEE Transactions on Power Delivery ; Vol. 28, issue. 3 , 2013 , p. 1600-1609 ; ISSN: 8858977 Shaker, H ; Zareipour, H ; Fotuhi-Firuzabad, M ; Sharif University of Technology
    Abstract
    In this paper, a Markov model for reliability analysis of transmission lines equipped with a dynamic thermal rating (DTR) system is proposed. Moreover, a fuzzy procedure is proposed to determine an annual equivalent fuzzy DTR number to represent hourly variations of the line DTR. To implement the fuzzy annual DTR in composite system reliability analysis, an interactive method resolution technique for solving fuzzy optimization problems is developed. This method is chosen to address the fuzzy constraints associated with the lines equipped with the DTR system. Numerical results are presented using the 24-bus IEEE RTS, and demonstrate the validity of the proposed approaches  

    Reliability modeling of dynamic thermal rating

    , Article IEEE Transactions on Power Delivery ; Volume 28, Issue 3 , 2013 , Pages 1600-1609 ; 08858977 (ISSN) Shaker, H ; Zareipour, H ; Fotuhi Firuzabad, M ; Sharif University of Technology
    2013
    Abstract
    In this paper, a Markov model for reliability analysis of transmission lines equipped with a dynamic thermal rating (DTR) system is proposed. Moreover, a fuzzy procedure is proposed to determine an annual equivalent fuzzy DTR number to represent hourly variations of the line DTR. To implement the fuzzy annual DTR in composite system reliability analysis, an interactive method resolution technique for solving fuzzy optimization problems is developed. This method is chosen to address the fuzzy constraints associated with the lines equipped with the DTR system. Numerical results are presented using the 24-bus IEEE RTS, and demonstrate the validity of the proposed approaches