The Experts below are selected from a list of 285912 Experts worldwide ranked by ideXlab platform
Ian A Hiskens - One of the best experts on this subject based on the ideXlab platform.
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numerical computation of critical System Recovery parameter values by trajectory sensitivity maximization
Conference on Decision and Control, 2019Co-Authors: Michael W Fisher, Ian A HiskensAbstract:Consider a particular finite-time disturbance applied to a System governed by ordinary differential equations and which possesses a stable equilibrium point. The Recovery of the System from a disturbance is a function of the System parameter values. It is an important though challenging problem to identify the System parameter values, called critical parameter values, for which the System is just marginally unable to recover from a particular disturbance. Such critical parameter values correspond to cases where the System state, at the instant when the disturbance clears, is on the boundary of the region of attraction of the stable equilibrium point. The paper proposes novel algorithms for numerically computing critical parameter values, both for one and arbitrary dimensional parameter spaces. In the latter case, the algorithm computes the critical parameter values that are nearest to a given point in parameter space. The key idea underpinning the algorithms is that on the boundary of the region of attraction, the trajectory becomes infinitely sensitive to small changes in parameter value. Therefore, critical parameter values are found by varying parameters so as to maximize trajectory sensitivities. The algorithms are demonstrated using a fourth-order power System test case.
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CDC - Numerical Computation of Critical System Recovery Parameter Values by Trajectory Sensitivity Maximization
2019 IEEE 58th Conference on Decision and Control (CDC), 2019Co-Authors: Michael W Fisher, Ian A HiskensAbstract:Consider a particular finite-time disturbance applied to a System governed by ordinary differential equations and which possesses a stable equilibrium point. The Recovery of the System from a disturbance is a function of the System parameter values. It is an important though challenging problem to identify the System parameter values, called critical parameter values, for which the System is just marginally unable to recover from a particular disturbance. Such critical parameter values correspond to cases where the System state, at the instant when the disturbance clears, is on the boundary of the region of attraction of the stable equilibrium point. The paper proposes novel algorithms for numerically computing critical parameter values, both for one and arbitrary dimensional parameter spaces. In the latter case, the algorithm computes the critical parameter values that are nearest to a given point in parameter space. The key idea underpinning the algorithms is that on the boundary of the region of attraction, the trajectory becomes infinitely sensitive to small changes in parameter value. Therefore, critical parameter values are found by varying parameters so as to maximize trajectory sensitivities. The algorithms are demonstrated using a fourth-order power System test case.
S.m. Shahidehpour - One of the best experts on this subject based on the ideXlab platform.
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A comprehensive long term dynamic simulation for power System Recovery
IEEE Transactions on Power Systems, 1994Co-Authors: I. Roytelman, S.m. ShahidehpourAbstract:The long term dynamic System behavior under severe frequency and voltage changes, and the logics of automatic control actions (e.g., underfrequency load shedding and underfrequency generator separation) are discussed. The long term power System dynamic simulation is devised as a tool for studying the coordination of emergency control techniques in order to prevent significant deviations in power Systems variables. A modification of the fast, decoupled power flow technique is considered for the quasi-stationary power flow solution. This approach is enhanced by the trapezoidal rule integration algorithm and the Runge-Kutta fourth order method for the solution of power System dynamic equations. Typical scenarios for the System Recovery after power outages are discussed, and recommendations for the implementation of these techniques in large-scale power Systems are provided. These topics are illustrated by two practical-examples for modern power Systems. >
Zhu - One of the best experts on this subject based on the ideXlab platform.
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CLUSTER - A System Recovery benchmark for clusters
Proceedings IEEE International Conference on Cluster Computing CLUSTR-03, 2003Co-Authors: Pramanick, Mauro, ZhuAbstract:High availability clusters are becoming increasingly common in IT environments today, and the level of availability offered by such Systems is a key factor used in their evaluation. However, no Systematic and consistent methodology exists to perform such an assessment. Thus there is a critical need to establish cluster availability benchmarks. This paper proposes a cluster availability benchmark, SRB-X, that measures the automatic Recovery time of a cluster framework in the event of a cluster node failure. SRB-X is a repeatable and portable benchmark, that measures a common outage mode for high availability clusters. After listing the main requirements of the underlying System Recovery benchmark framework, this paper describes the various properties of SRB-X. The calculation of the SRB-X metric is illustrated through two examples.
Kosuke Takano - One of the best experts on this subject based on the ideXlab platform.
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An Architecture for System Recovery Based on Solution Records on Different Servers
Advances on P2P Parallel Grid Cloud and Internet Computing, 2020Co-Authors: Takayuki Kasai, Kosuke TakanoAbstract:It is very important to quickly solve System failures in a System operation. Some studies have proposed fault tolerance Systems such as a flexible System architecture for dealing with System failures and automatic failure detection System. However, human identifies a System failure in many cases, and a support System to reduce the cost of trial and error for solving System failures is required. In this study, we propose an architecture for System Recovery based on solution records on different servers. In the experiment using prototype, we confirm the feasibility of the proposed System.
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3PGCIC - An Architecture for System Recovery Based on Solution Records on Different Servers
Advances on P2P Parallel Grid Cloud and Internet Computing, 2019Co-Authors: Takayuki Kasai, Kosuke TakanoAbstract:It is very important to quickly solve System failures in a System operation. Some studies have proposed fault tolerance Systems such as a flexible System architecture for dealing with System failures and automatic failure detection System. However, human identifies a System failure in many cases, and a support System to reduce the cost of trial and error for solving System failures is required. In this study, we propose an architecture for System Recovery based on solution records on different servers. In the experiment using prototype, we confirm the feasibility of the proposed System.
Jonathan L. Payne - One of the best experts on this subject based on the ideXlab platform.
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Marine anoxia and delayed Earth System Recovery after the end-Permian extinction
Proceedings of the National Academy of Sciences of the United States of America, 2016Co-Authors: Kimberly V. Lau, Kate Maher, Demir Altiner, Brian M. Kelley, Lee R. Kump, Daniel J. Lehrmann, Juan Carlos Silva-tamayo, K. L. Weaver, Jonathan L. PayneAbstract:Delayed Earth System Recovery following the end-Permian mass extinction is often attributed to severe ocean anoxia. However, the extent and duration of Early Triassic anoxia remains poorly constrained. Here we use paired records of uranium concentrations ([U]) and 238U/235U isotopic compositions (δ238U) of Upper Permian−Upper Triassic marine limestones from China and Turkey to quantify variations in global seafloor redox conditions. We observe abrupt decreases in [U] and δ238U across the end-Permian extinction horizon, from ∼3 ppm and −0.15‰ to ∼0.3 ppm and −0.77‰, followed by a gradual return to preextinction values over the subsequent 5 million years. These trends imply a factor of 100 increase in the extent of seafloor anoxia and suggest the presence of a shallow oxygen minimum zone (OMZ) that inhibited the Recovery of benthic animal diversity and marine ecoSystem function. We hypothesize that in the Early Triassic oceans—characterized by prolonged shallow anoxia that may have impinged onto continental shelves—global biogeochemical cycles and marine ecoSystem structure became more sensitive to variation in the position of the OMZ. Under this hypothesis, the Middle Triassic decline in bottom water anoxia, stabilization of biogeochemical cycles, and diversification of marine animals together reflect the development of a deeper and less extensive OMZ, which regulated Earth System Recovery following the end-Permian catastrophe.
