The Experts below are selected from a list of 264 Experts worldwide ranked by ideXlab platform
Sebastian Martorell - One of the best experts on this subject based on the ideXlab platform.
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evaluation of allowed Outage Time considering a set of plant configurations
Reliability Engineering & System Safety, 2002Co-Authors: Marko Cepin, Sebastian MartorellAbstract:Abstract Allowed Outage Time (AOT) is the maximum Time for which certain safety equipment can be put out of the operation without the plant is put in a safer operating state. A method for risk informed evaluation of AOTs is developed, which enables consideration of a set of plant configurations in the evaluation. The method bases on risk measures obtained from probabilistic safety assessment, e.g. conditional change of core damage frequency considering selected plant configurations. The results of selected examples show that better methods and more data included into the models may reduce the conservatism in the evaluations and may contribute to increased flexibility about decisions on AOT.
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improving allowed Outage Time and surveillance test interval requirements a study of their interactions using probabilistic methods
Reliability Engineering & System Safety, 1995Co-Authors: Sebastian Martorell, V Serradell, P K SamantaAbstract:Technical Specifications (TS) define the limits and conditions for operating nuclear plants safely. We selected the Limiting Conditions for Operations (LCO) and Surveillance Requirements (SR), both within TS, as the main items to be evaluated using probabilistic methods. In particular, we focused on the Allowed Outage Time (AOT) and Surveillance Test Interval (STI) requirements in LCO and SR, respectively. Already, significant operating and design experience has accumulated revealing several problems which require modifications in some TS rules. Developments in Probabilistic Safety Assessment (PSA) allow the evaluation of effects due to such modifications in AOT and STI from a risk point of view. Thus, some changes have already been adopted in some plants. However, the combined effect of several changes in AOT and STI, i.e. through their interactions, is not addressed. This paper presents a methodology which encompasses, along with the definition of AOT and STI interactions, the quantification of interactions in terms of risk using PSA methods, an approach for evaluating simultaneous AOT and STI modifications, and an assessment of strategies for giving flexibility to plant operation through simultaneous changes on AOT and STI using trade-off-based risk criteria.
Rajee Guptan - One of the best experts on this subject based on the ideXlab platform.
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NAPS PSA application allowed Outage Time optimisation
2010 2nd International Conference on Reliability Safety and Hazard - Risk-Based Technologies and Physics-of-Failure Methods (ICRESH), 2010Co-Authors: Nipu Phukan, Bhim Singh, L. K. Jain, A K Vijaya, Rajee GuptanAbstract:PSA provides an integrated model of the overall safety of the plant, which puts the safety issues in perspective, and helps in safety decisions related to both design and operations. NAPS Level-l PSA has been completed with the objective of presenting an integrated picture of safety of the NAPS which encompasses design, operational practices, component reliability, dependencies and human reliability. This has helped in understanding the weak links and plant vulnerabilities and the strengths in design and operational practices.
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NAPS PSA application allowed Outage Time optimisation
2010 2nd International Conference on Reliability Safety and Hazard - Risk-Based Technologies and Physics-of-Failure Methods (ICRESH), 2010Co-Authors: Nipu Phukan, Bhim Singh, L. K. Jain, A K Vijaya, Rajee GuptanAbstract:PSA provides an integrated model of the overall safety of the plant, which puts the safety issues in perspective, and helps in safety decisions related to both design and operations. NAPS Level-l PSA has been completed with the objective of presenting an integrated picture of safety of the NAPS which encompasses design, operational practices, component reliability, dependencies and human reliability. This has helped in understanding the weak links and plant vulnerabilities and the strengths in design and operational practices. There is always a desire to optimize the technical competency, resources and to operate the plant in most efficient practicable manner. In recent years, the operation of Indian Nuclear Power Plants has been characterized by improved availability/capacity factors and reduced forced Outages. NAPS Technical Specification for operation has been revised in the year 2009. NAPS PSA level-1 was extensively used as an engineering tool for Risk Informed Decision making for optimization of Station Technical Specifications with regard to Allowed Outage Time (AOT) and Surveillance Test Intervals (STIs). The approach outlined in USNRC RG-1.174 [5] andRG-1.177 [6] has been used as a guideline for optimization of Allowed Outage Time taking into consideration Instantaneous (conditional) risk, Cumulative Risk over the allowed Outage Time period, and the average risk over a long period. This paper outlines the approaches followed for the revision of AOTs in station technical specification. The paper also covers the acceptance criteria for the assessment of the submittals on technical specification change proposals. The illustrative clauses, where application of this methodology for technical specification optimization are presented.
Anjana Jain - One of the best experts on this subject based on the ideXlab platform.
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Estimation of Fading Statistics of Nakagami Channel with Weibull Distributed Tolerable Outage Time
Wireless Engineering and Technology, 2020Co-Authors: Anjana JainAbstract:Characterization of a mobile radio channel plays an important role in designing a reliable wireless communication system. Such channels are analyzed by two state model, namely satisfactory and Outage state. This paper presents the analysis to estimate fading parameters of wireless channel with omission of certain Outage durations which are considered as “Tolerance Time”. Minimum Outage duration which can be tolerated by a wireless fading channel to achieve desired packet error rate is defined as tolerance Time. Normally a system with tolerable minimum Outage Time is analyzed based on Fade Duration Distribution (FDD) function over Rayleigh channel. In this paper Weibull function is used as FDD for varying tolerance Time. The approach is simple and in general applicable from Rayleigh to Nakagami channels. The analysis is extended to study the effect of Tolerance Time on channel fading statistics such as Average Fade Duration (AFD) and frequency of Outage. Further the effects of various fade margin and Doppler spread on fading parameters are also investigated. The analysis can also be used in case of Timeout expiration, connection resetting and congestion window control
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Stochastic Modeling and Performance Evaluation of Fading Channel for Wireless Network Design
21st International Conference on Advanced Information Networking and Applications Workshops (AINAW'07), 2007Co-Authors: Anjana Jain, Raksha Upadhyay, P.d. Vyavahare, L.d. AryaAbstract:Characterization of temporal variations in wireless channel impairments plays an important role in the design of a reliable and efficient mobile communication system. Such channels are termed as fading channels since various random phenomena in the propagation path result in fading of the received signal envelope. Simulation models are often used to estimate channel behavior due to higher complexity in developing analytical models for such channels. In this paper, Finite State Markov Model is developed for the evaluation of multi-path fading channel. Cumulative states and frequency duration analysis approach is used for computing rate of transition between satisfactory states and Outage states, and Outage Time, of the channel. Simulation results obtained for Rayleigh channel are then used to find correspondence between fade depth and Outage Time for a sample system. These results may be used in the estimation of bit error rate and deciding optimum sampling instant of the received signal. It will also assist in selection of appropriate channel code and interleaver design for a future wireless networks with enhanced channel capacity.
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AINA Workshops (2) - Stochastic Modeling and Performance Evaluation of Fading Channel for Wireless Network Design
21st International Conference on Advanced Information Networking and Applications Workshops (AINAW'07), 2007Co-Authors: Anjana Jain, Raksha Upadhyay, P.d. Vyavahare, L.d. AryaAbstract:Characterization of temporal variations in wireless channel impairments plays an important role in the design of a reliable and efficient mobile communication system. Such channels are termed as fading channels since various random phenomena in the propagation path result in fading of the received signal envelope. Simulation models are often used to estimate channel behavior due to higher complexity in developing analytical models for such channels. In this paper, Finite State Markov Model is developed for the evaluation of multi-path fading channel. Cumulative states and frequency duration analysis approach is used for computing rate of transition between satisfactory states and Outage states, and Outage Time, of the channel. Simulation results obtained for Rayleigh channel are then used to find correspondence between fade depth and Outage Time for a sample system. These results may be used in the estimation of bit error rate and deciding optimum sampling instant of the received signal. It will also assist in selection of appropriate channel code and interleaver design for a future wireless networks with enhanced channel capacity.
L.d. Arya - One of the best experts on this subject based on the ideXlab platform.
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A smooth bootstrapping based technique for evaluating distribution system reliability indices neglecting random interruption duration
International Journal of Electrical Power & Energy Systems, 2013Co-Authors: Rajesh Arya, Aditya Tiwary, S.c. Choube, L.d. AryaAbstract:Abstract Average interruption duration, interruption duration per year and failure rate at a load point are the basic reliability indices required to be evaluated. These indices depend on failure rate and average repair Time of each feeder. Usually in reliability assessment of distribution system failure and repair rates are assumed constant. Further it has been observed that random Outage Time may be neglected at load point. This has been an important issue in determining the modified reliability indices accounting random Outage Time. Hence this paper presents a methodology to determine basic reliability indices subject to neglecting of certain repair Time which is truly a random variable. The methodology is based on smooth boot strapping technique along with Monte Carlo simulation (MCS). The developed algorithm has been implemented on two sample test systems. The results obtained has been compared those with MCS and obtained with general boot strapping.
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Stochastic Modeling and Performance Evaluation of Fading Channel for Wireless Network Design
21st International Conference on Advanced Information Networking and Applications Workshops (AINAW'07), 2007Co-Authors: Anjana Jain, Raksha Upadhyay, P.d. Vyavahare, L.d. AryaAbstract:Characterization of temporal variations in wireless channel impairments plays an important role in the design of a reliable and efficient mobile communication system. Such channels are termed as fading channels since various random phenomena in the propagation path result in fading of the received signal envelope. Simulation models are often used to estimate channel behavior due to higher complexity in developing analytical models for such channels. In this paper, Finite State Markov Model is developed for the evaluation of multi-path fading channel. Cumulative states and frequency duration analysis approach is used for computing rate of transition between satisfactory states and Outage states, and Outage Time, of the channel. Simulation results obtained for Rayleigh channel are then used to find correspondence between fade depth and Outage Time for a sample system. These results may be used in the estimation of bit error rate and deciding optimum sampling instant of the received signal. It will also assist in selection of appropriate channel code and interleaver design for a future wireless networks with enhanced channel capacity.
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AINA Workshops (2) - Stochastic Modeling and Performance Evaluation of Fading Channel for Wireless Network Design
21st International Conference on Advanced Information Networking and Applications Workshops (AINAW'07), 2007Co-Authors: Anjana Jain, Raksha Upadhyay, P.d. Vyavahare, L.d. AryaAbstract:Characterization of temporal variations in wireless channel impairments plays an important role in the design of a reliable and efficient mobile communication system. Such channels are termed as fading channels since various random phenomena in the propagation path result in fading of the received signal envelope. Simulation models are often used to estimate channel behavior due to higher complexity in developing analytical models for such channels. In this paper, Finite State Markov Model is developed for the evaluation of multi-path fading channel. Cumulative states and frequency duration analysis approach is used for computing rate of transition between satisfactory states and Outage states, and Outage Time, of the channel. Simulation results obtained for Rayleigh channel are then used to find correspondence between fade depth and Outage Time for a sample system. These results may be used in the estimation of bit error rate and deciding optimum sampling instant of the received signal. It will also assist in selection of appropriate channel code and interleaver design for a future wireless networks with enhanced channel capacity.
Marko Cepin - One of the best experts on this subject based on the ideXlab platform.
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evaluation of allowed Outage Time considering a set of plant configurations
Reliability Engineering & System Safety, 2002Co-Authors: Marko Cepin, Sebastian MartorellAbstract:Abstract Allowed Outage Time (AOT) is the maximum Time for which certain safety equipment can be put out of the operation without the plant is put in a safer operating state. A method for risk informed evaluation of AOTs is developed, which enables consideration of a set of plant configurations in the evaluation. The method bases on risk measures obtained from probabilistic safety assessment, e.g. conditional change of core damage frequency considering selected plant configurations. The results of selected examples show that better methods and more data included into the models may reduce the conservatism in the evaluations and may contribute to increased flexibility about decisions on AOT.
