In this paper, by considering the stochastic proces s of the busy period and the idle period, and introducing the unfinished work as a supplementary variable, a new vector Markov process was presented to study th e M...In this paper, by considering the stochastic proces s of the busy period and the idle period, and introducing the unfinished work as a supplementary variable, a new vector Markov process was presented to study th e M/G/1 queue again. Through establishing and solving the density evolution equa tions, the busy-period distribution, and the stationary distributions of waitin g time and queue length were obtained. In addition, the stability condition of th is queue system was given by means of an imbedded renewal process.展开更多
A two-stage directed Semi-Markov repairable network system is presented in this paper to model the performance of many transmission systems, such as power or oil transmission network, water or gas supply network, etc....A two-stage directed Semi-Markov repairable network system is presented in this paper to model the performance of many transmission systems, such as power or oil transmission network, water or gas supply network, etc. The availability of the system is discussed by using Markov renewal theory, Laplace transform and probability analysis methods. A numerical example is given to illustrate the results obtained in the paper.展开更多
Gearbox in offshore wind turbines is a component with the highest failure rates during operation. Analysis of gearbox repair policy that includes economic considerations is important for the effective operation of off...Gearbox in offshore wind turbines is a component with the highest failure rates during operation. Analysis of gearbox repair policy that includes economic considerations is important for the effective operation of offshore wind farms. From their initial perfect working states, gearboxes degrade with time, which leads to decreased working efficiency. Thus, offshore wind turbine gearboxes can be considered to be multi-state systems with the various levels of productivity for different working states. To efficiently compute the time-dependent distribution of this multi-state system and analyze its reliability, application of the nonhomogeneous continuous-time Markov process(NHCTMP) is appropriate for this type of object. To determine the relationship between operation time and maintenance cost, many factors must be taken into account, including maintenance processes and vessel requirements. Finally, an optimal repair policy can be formulated based on this relationship.展开更多
In the present work, it is assumed that the n-components are arranged in the hierarchial order. The n-cascade system surviving with loss of m components by k number of attacks is studied;the general equation for the r...In the present work, it is assumed that the n-components are arranged in the hierarchial order. The n-cascade system surviving with loss of m components by k number of attacks is studied;the general equation for the reliability is obtained for the above said system;and the system reliability is computed numerically for 6-cascade system for 2-number of attacks.展开更多
分布式能源在电力系统中的渗透率不断提升,使得配电网系统呈现出更大的复杂性和不确定性,这将对电力网络的可靠性产生影响。为确定配电网系统中可再生能源发电机组的最优安装位置和容量,文章结合随机模糊期望值算子和马尔科夫蒙特卡洛法...分布式能源在电力系统中的渗透率不断提升,使得配电网系统呈现出更大的复杂性和不确定性,这将对电力网络的可靠性产生影响。为确定配电网系统中可再生能源发电机组的最优安装位置和容量,文章结合随机模糊期望值算子和马尔科夫蒙特卡洛法(Markov Chain Monte Carlo,MCMC),提出了一种可靠性评估框架。该模型建立了风电和光伏出力的多状态概率密度函数,采用随机模糊期望值算子模拟配电网功率损耗和电压稳定性的不确定性。在考虑配电系统拓扑结构的情况下,利用MCMC模拟配电网系统中所有非源元件的随机性,由指数分布生成配电网组件故障事件及恢复时间。最后,在IEEE-33节点标准配电网上,对系统平均停电次数、系统平均停电持续时间、电量不足期望值3种可靠性指数进行评价,实验结果证明了所提出方法的有效性。展开更多
基金Project supported by the National Natural Science Foundation of China(Grant No.70171059)
文摘In this paper, by considering the stochastic proces s of the busy period and the idle period, and introducing the unfinished work as a supplementary variable, a new vector Markov process was presented to study th e M/G/1 queue again. Through establishing and solving the density evolution equa tions, the busy-period distribution, and the stationary distributions of waitin g time and queue length were obtained. In addition, the stability condition of th is queue system was given by means of an imbedded renewal process.
文摘A two-stage directed Semi-Markov repairable network system is presented in this paper to model the performance of many transmission systems, such as power or oil transmission network, water or gas supply network, etc. The availability of the system is discussed by using Markov renewal theory, Laplace transform and probability analysis methods. A numerical example is given to illustrate the results obtained in the paper.
文摘Gearbox in offshore wind turbines is a component with the highest failure rates during operation. Analysis of gearbox repair policy that includes economic considerations is important for the effective operation of offshore wind farms. From their initial perfect working states, gearboxes degrade with time, which leads to decreased working efficiency. Thus, offshore wind turbine gearboxes can be considered to be multi-state systems with the various levels of productivity for different working states. To efficiently compute the time-dependent distribution of this multi-state system and analyze its reliability, application of the nonhomogeneous continuous-time Markov process(NHCTMP) is appropriate for this type of object. To determine the relationship between operation time and maintenance cost, many factors must be taken into account, including maintenance processes and vessel requirements. Finally, an optimal repair policy can be formulated based on this relationship.
文摘In the present work, it is assumed that the n-components are arranged in the hierarchial order. The n-cascade system surviving with loss of m components by k number of attacks is studied;the general equation for the reliability is obtained for the above said system;and the system reliability is computed numerically for 6-cascade system for 2-number of attacks.
文摘分布式能源在电力系统中的渗透率不断提升,使得配电网系统呈现出更大的复杂性和不确定性,这将对电力网络的可靠性产生影响。为确定配电网系统中可再生能源发电机组的最优安装位置和容量,文章结合随机模糊期望值算子和马尔科夫蒙特卡洛法(Markov Chain Monte Carlo,MCMC),提出了一种可靠性评估框架。该模型建立了风电和光伏出力的多状态概率密度函数,采用随机模糊期望值算子模拟配电网功率损耗和电压稳定性的不确定性。在考虑配电系统拓扑结构的情况下,利用MCMC模拟配电网系统中所有非源元件的随机性,由指数分布生成配电网组件故障事件及恢复时间。最后,在IEEE-33节点标准配电网上,对系统平均停电次数、系统平均停电持续时间、电量不足期望值3种可靠性指数进行评价,实验结果证明了所提出方法的有效性。
