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reliability-analysis
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A Bayesian-reliability based multi-objective optimization for tolerance design of mechanical assemblies
, Article Reliability Engineering and System Safety ; Volume 213 , 2021 ; 09518320 (ISSN) ; Hassani, H ; Khodaygan, S ; Sharif University of Technology
Elsevier Ltd
2021
Abstract
Tolerances significantly affect the assemblability of components, the product's performance, and manufacturing cost in mechanical assemblies. Despite the importance of product reliability assessment, the reliability-based tolerance design of mechanical assemblies has not been previously considered in the literature. In this paper, a novel method based on Bayesian modeling is proposed for the tolerance-reliability analysis and allocation of complex assemblies where the explicit assembly functions are difficult or impossible to extract. To reach this aim, a Bayesian model is developed for tolerance-reliability analysis. Then, a multi-objective optimization formulation is proposed for obtaining...
A novel fault tolerant reconfigurable concept for vector control of induction motors
, Article EPE-PEMC 2006: 12th International Power Electronics and Motion Control Conference, Portoroz, 30 August 2006 through 1 September 2006 ; 2007 , Pages 1199-1204 ; 1424401216 (ISBN); 9781424401215 (ISBN) ; Shojaei, A ; Sharif University of Technology
2007
Abstract
AC drive users with sophisticated applications are demanding greater reliability to avoid process interruptions. AC motor drive systems are susceptible to sensors failure. A novel fault tolerant Field Oriented Control system for induction motors is introduced. The system maintains speed control in the event of sensors malfunction and adverse signal conditions, providing enhanced reliability. Different motor models are combined by a Fuzzy aggregation system in order to give a reliable estimate of flux vector. The proposed control system is an effective and easy to implement method giving a potential for motor drive reliability enhancement. © 2006 IEEE
Reliability of slope stability analysis using fuzzy set
, Article Annual Conference of the Canadian Society for Civil Engineering 2007: Where the Road Ends, Ingenuity Begins, Yellowknife, NT, 6 June 2007 through 9 June 2007 ; Volume 1 , 2007 , Pages 11-20 ; Sharif University of Technology
2007
Abstract
In this research, theory of fuzzy sets is used to deal with the uncertain nature of soil parameters and the inaccuracy involved in the analysis simultaneously. Soil parameters are defined using suitable fuzzy sets and the uncertainty inherent in the value of factor of safety is assessed. It is believed that this approach accounts for the uncertainty in soil parameters more realistically compared to the conventional probabilistic approaches reported in the literature. The proposed method is applied to a case study and the results are discussed subsequently
Fast reliability analysis method for sequential logic circuits
, Article Proceedings - ICSEng 2011: International Conference on Systems Engineering, 16 August 2011 through 18 August 2011, Las Vegas, NV ; 2011 , Pages 352-356 ; 9780769544953 (ISBN) ; Jahanirad, H ; Attarsharghi, P ; Sharif University of Technology
2011
Abstract
Reliability analysis of combinational logic circuits using error probabilities methods, such as PTM, has been widely developed and used in literature. However, using these methods for reliability analysis of sequential logic circuits will lead to inaccurate results, because of existence of loops in their architecture. In this paper a new method is proposed based on converting the sequential circuit to a secondary combinational circuit and applying an iterative reliability analysis to the resulting configuration. Experimental results demonstrate good accuracy levels for this method
An Approximation Method for Reliability Analysis of Standby Systems
, M.Sc. Thesis Sharif University of Technology ; Eshraghniaye Jahromi, Abdolhamid (Supervisor)
Abstract
Analyzing reliability of large cold-standby systems has been a complicated and time-consuming task, especially for systems with components having non-exponential time-to-failure distributions. In this research, an approximation model, which is based on the central limit theorem, is presented for the reliability analysis of binary cold-standby systems whit non-identical components. The proposed model can estimate the reliability of large cold-standby systems with binary-state components having arbitrary time-to-failure distributions in an efficient and easy way. The accuracy and efficiency of the proposed method are illustrated using several different types of distributions, such as...
Reliability evaluation of deregulated electric power systems for planning applications
, Article Reliability Engineering and System Safety ; Volume 93, Issue 10 , 2008 , Pages 1473-1484 ; 09518320 (ISSN) ; Ranjbar, A. M ; Jafari, A ; Fotuhi Firuzabad, M ; Sharif University of Technology
2008
Abstract
In a deregulated electric power utility industry in which a competitive electricity market can influence system reliability, market risks cannot be ignored. This paper (1) proposes an analytical probabilistic model for reliability evaluation of competitive electricity markets and (2) develops a methodology for incorporating the market reliability problem into HLII reliability studies. A Markov state space diagram is employed to evaluate the market reliability. Since the market is a continuously operated system, the concept of absorbing states is applied to it in order to evaluate the reliability. The market states are identified by using market performance indices and the transition rates...
A fuzzy-monte carlo simulation approach for fault tree analysis
, Article 2006 Annual Reliability and Maintainability Symposium, RAMS'06, Newport Beach, CA, 23 January 2006 through 26 January 2006 ; 2006 , Pages 428-433 ; 0149144X (ISSN); 1424400074 (ISBN); 9781424400072 (ISBN) ; Miremadi, G ; Sharif University of Technology
2006
Abstract
Fault tree analysis is one of the key approaches used to analyze the reliability of critical systems. Fault trees are usually analyzed using mathematical approaches or Monte Carlo simulation (MCS). This paper presents a Fuzzy-Monte Carlo simulation (FMCS) approach in which the uncertain data is generated by the MCS approach. The FMCS approach is applied to the Weibull probability distribution which is widely been used in the analysis of reliability, availability, maintainability and safety (RAMS). Using the fuzzy arithmetic, times to failure (TTF) of the components are generated. These results are processed by a kind of fault tree (e.g. time-to-failure tree) to produce the TTF of the whole...
Estimation of damage induced by single-hole rock blasting: A review on analytical, numerical, and experimental solutions
, Article Energies ; Volume 14, Issue 1 , 2021 ; 19961073 (ISSN) ; Gokdemir, C ; Zhou, M ; Kordestani, H ; Muho, E. V ; Sharif University of Technology
MDPI AG
2021
Abstract
This paper presents a review of the existing models for the estimation of explosion-induced crushed and cracked zones. The control of these zones is of utmost importance in the rock explosion design, since it aims at optimizing the fragmentation and, as a result, minimizing the fine grain production and recovery cycle. Moreover, this optimization can reduce the damage beyond the set border and align the excavation plan with the geometric design. The models are categorized into three groups based on the approach, i.e., analytical, numerical, and experimental approaches, and for each group, the relevant studies are classified and presented in a comprehensive manner. More specifically, in the...
Assessment of Existing Jacket Type Offshore Platform against Environmental Wave Loading Utilizing Theory of Reliability
, M.Sc. Thesis Sharif University of Technology ; Golafshani, Ali Akbar (Supervisor)
Abstract
Assessment of existing jacket type offshore platform against environmental wave loading hazard is the central component of this work. Two general approaches exist in this context, deterministic and probabilistic assessment. In this study, a new probabilistic method (reliability analysis) to assess offshore structures under environmental loading (extreme wave) is introduced. Before describing this approach, several necessary elements such as collapse analysis, sampling methods and wave hazard analysis should be investigated. First of all, deterministic assessment of SPD2 platform located in Persian Gulf, which is the case study considered in this dissertation, is conducted utilizing...
Developing a New Approach for Reliability Evaluation of Large Scale Composite Systems
, M.Sc. Thesis Sharif University of Technology ; Fotuhi Firuzabad, Mahmud (Supervisor)
Abstract
The main concern of power system planners and operators is to serve electric energy services economically and in an acceptable reliability level. Nowadays, in developing integrated large-scale power networks, reliability evaluation becomes a very tough and time-consuming process. The complexity of this assessment is mainly because of the large number of components, their possible operating states, different faults that can happen, and environmental and other affecting parameters. In power systems, in order to address the complexity, reliability evaluation can be conducted in three different levels. The most complicated study among these three levels is HLII that is so-called composite...
Reliability Analysis of a Thrust Vector Control (TVC) System
, M.Sc. Thesis Sharif University of Technology ; Pourtakdoost, Hossein (Supervisor)
Abstract
Reliability modeling, analysis and computation of a Thrust Vector Control System (TVC) is investigated. In this respect, first the TVC subsystems including the jet vanes (JVs), sensors and actuators,... are identified and their pertinent Reliability Block Diagram (RBD) is depicted. Subsequently static reliability of a jet vane is calculated considering both structural and thermal loadings via related verified limit state functions. In addition, a sensitivity analysis is performed that identifies the key JVs design parameters from a reliability point of view. Next, knowing the structural and thermal reliability of the JVs, static reliability of the total TVC system is computed via utility of...
Reliability Analysis of Offshore Wind Turbine Structure with Integrity Management Viewpoint
, M.Sc. Thesis Sharif University of Technology ; Raie, Mohammad (Supervisor)
Abstract
In this study, a framework for reliability analysis of offshore wind turbine structures has been presented. The rapid development of these structures in the world due to the increasing need for electrical energy and limited sources of fossil fuels has increased the importance of research on the behavior and condition of these structures. For Iran, despite its fossil fuels resources due to its international voluntary commitments to reduce greenhouse gases such as Paris agreement, the use of renewable energy such as offshore wind energy is important. Also, the offshore wind turbine structure is affected by different forces and environmental conditions in its life cycle, which are associated...
A new formulation for power system reliability assessment with AC constraints
, Article International Journal of Electrical Power and Energy Systems ; Vol. 56, issue , March , 2014 , p. 298-306 ; ISSN: 1420615 ; Fotuhi-Firuzabad, M ; Aminifar, F ; Lehtonen, M ; Sharif University of Technology
Abstract
Recent investigations have revealed the significant role of reactive power in blackout events. The associated disturbances frequently emerge in the form of voltage instability and collapse. Due to the computational complexity of modeling and analysis of enormous contingencies, DC approximation of the power flow, without accounting the role of reactive power, is usually used to evaluate the contingencies and to mitigate the associated probable violations. This paper, at first, presents a linear power flow model based on an approximated version of AC power flow formulation. The proposed model is then used to develop an efficient reliability assessment approach which is capable of taking both...
Reliability modeling of dynamic thermal rating
, Article IEEE Transactions on Power Delivery ; Vol. 28, issue. 3 , 2013 , p. 1600-1609 ; ISSN: 8858977 ; 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
Impacts of fault diagnosis schemes on distribution system reliability
, Article IEEE Transactions on Smart Grid ; Vol. 3, issue. 2 , 2012 , p. 720-727 ; ISSN: 19493053 ; Lehtonen, M ; Fotuhi-Firuzabad, M ; Sharif University of Technology
Abstract
Design and development of fault diagnosis schemes (FDS) for electric power distribution systems are major steps in realizing the self-healing function of a smart distribution grid. The application of the FDS in the electric power distribution systems is mainly aimed at precise detecting and locating of the deteriorated components, thereby enhancing the quality and reliability of the electric power delivered to the customers. The impacts of two types of the FDS on distribution system reliability are compared and presented in this paper. The first type is a representative of the FDS which diagnoses the deteriorated components after their failing. However, the second type is a representative of...
Integration of clustering analysis and reward/penalty mechanisms for regulating service reliability in distribution systems
, Article IET Generation, Transmission and Distribution ; Vol. 5, issue. 11 , 2011 , p. 1192-1200 ; ISSN: 17518687 ; Fotuhi-Firuzabad, M ; Billinton, R ; Sharif University of Technology
Abstract
This study proposes an approach for improving service reliability in the distribution network based on establishing competition among electric distribution utilities. The idea behind this approach is to categorise the utilities and compare the performance of utilities located in one cluster with the other members of the same cluster. The reward/penalty mechanism (RPM) as a quality regulating instrument is designed for each cluster and used to penalise the utilities with a performance worse than the benchmark and to reward them for providing a performance better than the benchmark. Based on the RPM, utilities located in one cluster compete to make more profit by serving customers in better...
Public participation role in sustainable urban management by quantitative strategic planning matrix (QSPM)
, Article International Journal of Environmental Research ; Vol. 8, issue. 4 , 2014 , p. 1309-1314 ; Abbaspour, M ; Monavari S.M ; Arjmandi R ; Lahijanian, A ; Sharif University of Technology
Abstract
Public participation is counted as one of the main indexes in sustainable urban management. Based on their nature, metropolitan cities has several and complex problems. For this purpose Tehran metropolitan area is selected. Quantitative Strategic Planning Matrix (QSPM) weighted through a made-byresearcher questionnaire. The reliability of the model was verified by Cronbach’s alpha coefficient. Evaluation matrix for internal and external factors was equal to 1.944 and 3.413, respectively. The strategies were classified and prioritize by quantitative matrix. Suitable strategies for Tehran city are as follows: developing a strategic plan in field of social control participatory management for...
Wind farm optimal connection to transmission systems considering network reinforcement using cost-reliability analysis
, Article IET Renewable Power Generation ; Volume 7, Issue 6 , 2013 , Pages 603-613 ; 17521416 (ISSN) ; Hosseini, S. H ; Sharif University of Technology
2013
Abstract
In this study, a novel network reinforcement model incorporating optimal wind farms (WFs) integration to power systems is proposed. Based on the reinforcement model, new transmission lines are added to the network for eliminating the transmission network congestion. In addition, a methodology for determining the WFs optimal capacities, the economical WF lines transfer rates and the appropriate reinforcement plan, whereas maximising the total benefit using cost-reliability analysis is presented. In this way, the objective of the proposed optimisation problem has been divided into a master problem and two subproblems. Benders decomposition is employed to connect the master and subproblems of...
Reliability modeling of dynamic thermal rating
, Article IEEE Transactions on Power Delivery ; Volume 28, Issue 3 , 2013 , Pages 1600-1609 ; 08858977 (ISSN) ; 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
Reliable design of a forward/reverse logistics network under uncertainty: A robust-M/M/c queuing model
, Article Transportation Research Part E: Logistics and Transportation Review ; Volume 48, Issue 6 , 2012 , Pages 1152-1168 ; 13665545 (ISSN) ; Tavakkoli Moghaddam, R ; Modarres, M ; Baboli, A ; Sharif University of Technology
2012
Abstract
This paper presents a novel model for designing a reliable network of facilities in closed-loop supply chain under uncertainty. For this purpose, a bi-objective mathematical programming formulation is developed which minimizes the total costs and the expected transportation costs after failures of facilities of a logistics network. To solve the model, a new hybrid solution methodology is introduced by combining robust optimization approach, queuing theory and fuzzy multi-objective programming. Computational experiments are provided for a number of test problems using a realistic network instance