Optimal sequencing of warm standby elements

Warm standby redundancy has been used as an effective design technique for improving the reliability of a system while achieving the compromise between restoration cost and operation cost of standby elements. This paper considers the optimal standby element sequencing problem (SESP) for 1-out-of-N: G heterogeneous warm-standby systems. Given the desired redundancy level and a fixed set of element choices, the objective of the optimal system design is to select the initiation sequence of the system elements so as to minimize the expected mission cost of the system while providing a certain level of system reliability. Based on a discrete approximation of time-to-failure distributions of the system elements, the system reliability and expected mission cost are evaluated using an iterative procedure. A genetic algorithm is used as an optimization tool for solving the formulated SESP problem for 1-out-of-N: G warm-standby systems with non-identical elements. As illustrated through examples, results generated using the suggested methodology can facilitate the system reliability versus cost trade-off study, which can further assist in the decision making about the best standby policy for fault-tolerant system designs.     

Sequencing Optimization in k-out-of-n Cold-Standby Systems Considering Mission Cost

The k-out-of-n: G heterogeneous cold-standby system structure is a widely used fault-tolerant system design method, where the sequence in which the different system elements are initiated can greatly affect the system reliability and mission cost. This paper considers the optimal standby element sequencing problem (SESP) for such systems. Given the desired cold-standby redundancy level and fixed set of element choices, the objective of the optimal system design is to select the initiation sequence of the system elements so as to minimize the expected system mission cost while meeting a certain level of system reliability constraint. Based on a discrete approximation of time-to-failure distributions of the system elements, the system reliability and expected mission cost are evaluated simultaneously using a numerical method. A genetic algorithm is used as an optimization tool for solving the formulated SESP problem for k-out-of-n: G heterogeneous cold-standby systems. Examples are given to illustrate the considered problem and the proposed solution methodology.     

Optimal completed work dependent loading of components in cold standby systems

This paper considers the modelling and optimization of 1-out-of-N: G cold standby (CS) systems with non-repairable components functioning at different levels of productivity or load. The productivity heterogeneity leads to difference in component failure behaviour as well as in operational and replacement costs. Thus, the choice of load or productivity of components can greatly affect the system reliability and mission cost. To make the optimal choice of component loading, we first suggest a method for analysing the reliability and expected mission cost of 1-out-of-N: G non-repairable CS systems with heterogeneous components. The optimal dynamic load distribution problem is then formulated and solved, in which the component loading is chosen depending on the amount of work completed prior to the component activation. The optimal loading is aimed at minimizing the expected mission cost, while meeting a certain system reliability constraint. Examples are given to demonstrate the proposed methodology and the improvement in the optimal design solution through introducing the component productivity’s dependence on the completed work.     

Warm standby in hierarchically structured process-control programs

We classify standby redundancy design space in process-control programs into the following three categories: cold standby, warm standby, and hot standby. Design parameters of warm standby are identified and the reliability of a system using warm standby is evaluated and compared with that of hot standby. Our analysis indicates that the warm standby scheme is particularly suitable for long-lived unmaintainable systems, especially those operating in harsh environments where burst hardware failures are possible. The feasibility of warm standby is demonstrated with a simulated chemical batch reactor system     

煤矿监控系统双机热备数据同步软件设计

针对现有的煤矿监控系统双机热备方案存在存储设备投资费用高、可靠性相对较差、主机中断后恢复数据算法复杂等缺点,设计了基于纯软件模式的双机热备数据同步软件,该软件依据煤矿监控系统的实际应用情况,将监控数据同步功能从双机热备系统中独立出来,形成一个独立的软件,降低了双机热备同步算法和同步内容的复杂度,提高了双机热备的可靠性。     

煤矿企业纯软件方式的双机热备系统研究

针对煤矿监控系统双机热备标准方案中硬件设备昂贵、维护成本较高的问题,设计了一种纯软件方式的双机热备系统。该系统利用文件差异备份以及MYSQL增量备份相结合的方式将数据保存到主、备机中,即采用RSYNC文件同步算法对文件进行备份,利用MYSQL数据库的Binary Log机制开启日志记录文件,将在一个时间间隔内发生修改的数据信息导出到增量备份文件中,并将增量备份文件发送到备机中,备机将修改数据导入数据库,从而达到数据库同步操作的目的。同样地,在主机出现故障后,在备机中修改的数据以同样的方式同步到主机中。该双机热备系统已投入实际应用,满足了煤矿监控系统中数据实时性与数据完整性的要求。     

浅淡山东空管分局基于纯软的办公服务器双机热备方案

双机热备份技术是目前主流应用的服务器容错技术的一种,具有安装简单,稳定的特点.但双机热备方案对硬件要求高,一般均需要磁盘柜或磁带机方能制定双机热备的方案,纯软热备也需要大量资金购买热备软件,从而导致热备方案成本很高.作者在长期的运行维护期间,依据所在单位服务器备份数据的现状,经过大量的实践操作,探索出另一种纯软件热备份的零成本方案.     

复杂多态系统的冗余备份元件优化

在复杂的多态系统中,系统可靠性非常重要,最常见的是冷热备份模式来实现系统的可靠性.本文中我们提出了混合冗余备份模式,计算复杂系统的可靠性和任务成本,解决复杂系统中的备份元件优化分布和初始化问题.本文主要是通过离散数学的概率分布计算复杂系统中元件的可靠性和任务成本,利用量子遗传算法来解决冗余备份元件的优化分布问题.最后同时通过仿真实验来计算出系统的可靠性和预期的任务成本,以及冗余备分元件的优化分布,得出了复杂系统可靠性与成本的平衡关系.     

Multi-objective reliability optimization for dissimilar-unit cold-standby systems using a genetic algorithm

A genetic algorithm approach is used to solve a multi-objective discrete reliability optimization problem in a k dissimilar-unit non-repairable cold-standby redundant system. Each unit is composed of a number of independent components with generalized Erlang distributions arranged in a series–parallel configuration. There are multiple component choices with different distribution parameters available for being replaced with each component of the system. The objective of the reliability optimization problem is to select the best components, from the set of available components, to be placed in the standby system in order to minimize the initial purchase cost of the system, maximize the system MTTF (mean time to failure), minimize the system VTTF (variance of time to failure) and also maximize the system reliability at the mission time. Finally, we apply a genetic algorithm with double strings using continuous relaxation based on reference solution updating (GADSCRRSU) to solve this multi-objective problem, using goal attainment formulation. The results are also compared against the results of a discrete-time approximation technique to show the efficiency of the proposed GA approach.     

Analysis and optimal design of systems operating in a random environment and having a rescue option

The paper presents a model for a system exposed to a random environment characterized by the Poisson shock processes. A subset of the system components ?_M is required for a mission completion. Failures of some components of this subset terminate a mission, whereas failures of other components are not terminal and allow for a rescue operation that is activated immediately upon failure. This operation is performed by a subset ?_R of the system components and succeeds if all components from ?_R survive all shocks occurring until its completion. The subsets ?_M and ?_R overlap. The duration of the rescue operation depends on the time of its activation. The components that are engaged only in the rescue operation remain in the warm standby mode during the primary mission. An approach for obtaining the mission success and the system survival probabilities is developed and an algorithm for the corresponding numerical computation is presented. An example analyzing the tradeoff between these two probabilities and illustrating optimization of the system protection design is given.     

Optimal elements separation in non-repairable phased-mission systems

Enhancement of the survivability of a system can be achieved by separating its elements. Since different elements can play different roles in fulfilling the system mission, the way in which they are separated strongly affects the achieved level of the mission survivability. Thus, the optimal separation problem arises. This paper formulates a new problem of optimal element separation in non-repairable phased-mission systems (PMSs) where the mission consists of multiple, consecutive and non-overlapping phases of operation. An accurate survivability analysis of a PMS must consider the statistical dependence of element states across phases as well as dynamics in system structure function and element failure behaviour. We suggest a method for finding the separation of the system elements that provides a maximal possible level of the PMS survivability while satisfying a certain separation cost constraint. A backward recursion algorithm is applied for determining the survivability of a vulnerable PMS. A genetic algorithm is used as an optimization tool in solving the newly formulated separation problem for PMSs.     

考虑多维修台异步多重休假的温贮备冗余系统可靠性模型

考虑多维修台保障多个系统时维修力量存在调度与分配的情况,引入多维修台异步多重休假策略;以温贮备冗余系统为研究对象,针对以往研究利用指数分布等典型分布导致模型约束条件过于严格的问题,采用连续phase-type(PH)分布描述系统中工作部件寿命、温贮备部件寿命以及维修台休假时间和维修时间,建立通用性更好的系统可靠性解析模型,给出系统可靠度、系统稳态可用度等冗余系统可靠性指标和稳态忙期维修台数量等维修台稳态指标;利用算例验证模型适用性,演示了维修台数量、系统温贮备部件数量变化以及修理工休假速率、维修速率变化对系统各可靠性指标和维修台稳态指标的影响.算例计算结果表明,所提出的可靠性模型能够有效复现多维修台调度对冗余系统可靠性的影响,从而为维修台数量的合理安排及系统部件数量的优化配置提供理论基础和实践参考.     

备用复式控制系统的可靠性预计及其应用

本文全面分析了备用复式系统的可靠性问题,推导出成套的预计公式并给出一个详细的计算实例. 首先,通过考虑监控器和转换开关的动态和静态故障,细致地剖析了自动控制器本身的故障.然后,按照公用与独立两种型式的转换器,划分这些故障为独立与相依两类,并且归结到独立转换器远比公用转换器为优.同时指出转换器本身的故障必须小于各个分系统的故障,否则就不可能提高总系统的可靠性.此外,对自动停车措施的得失及温冷混合贮备的优点,也都得到了明确的结论.     

具有单重休假和修复不如新的两部件温贮备系统

研究了修理工单重休假且由两个不同型部件和一个修理工组成的可修型温贮备系统. 系统考虑了在工作故障和贮备 故障都不能 “修复如新”, 部件 1 是修复非新而部件 2 修复如新的条件下, 假设部件的工作寿命、贮备寿命、故障后的修理时间和贮备故障后的修理时间均服 从不同的指数分布, 修理工休假服从一般连续型分布. 运用几何过程理论、补充变量法、 拉普拉斯变换及拉普拉斯--司梯阶变换, 得到了系统的可用度、可靠度和系统首次故障前平均时间等可靠性指标. 最后, 通过数值模拟验证了结果的有效性.     

基于双机热备的控制计算机系统研究与实现

可靠性是控制计算机系统的重要性能之一,它已经在很多应用领域成为衡量系统质量的一个重要指标。双机热备是提高系统可靠性的有效方法之一,介绍了双机热备的概念,研究对比了单机与双机热备系统的可靠性,给出了系统组成、工作原理及实现双机热备系统的关键技术。基于双机热备的控制计算机系统已经投入使用,在应用过程中效果良好。     

Optimal operational planning of steam power systems using an IPSOSA algorithm

The operation optimization problem of steam power systems for multiperiod operation with varying demands is formulated. The objective function of the mode! is to minimize the operational cost of steam power systems for all periods, by taking into account the cost of fuel, and feed-water, as well as the expenses of maintenance and startup/shutdown. In order to obtain the optimal solution of the foregoing model, an improved particle swarm optimization method based on the ideal of simulated annealing algorithm (IPSOSA) is proposed, in which IPSOSA are applied to make particles have tendency to global optimum. Finally, cases are considered for illustrating the advantage of proposed optimization approach, with quantitive results presented. Results show that the IPSOSA algorithms are much more efficient and generate higher quality solutions than some existing particle swarm optimization algorithms.     

基于云模型的指挥信息多重协同过滤算法研究

针对传统协同过滤算法在构建指挥员与指挥要素间的协同过滤关系时面临着数据稀疏、冷启动等问题,提出了一种面向反恐任务的指挥信息多重协同过滤算法。该算法首先通过作战类型对指挥要素进行基于云模型的预协同过滤,然后将凝聚子集分析融入基于用户的协同过滤中,挖掘特定战斗类型下的指挥员与指挥要素间的相似性关系,进而实现精准推荐。实验表明,该算法贴合面向作战任务的指挥信息系统应用实践,有效提高了系统的推荐效率和准确度。     

Optimal number of minor failures before replacement

This paper extends a replacement model based on failure number to include a repair-cost limit for general failure distributions. The stochastic behaviour of failures and repair costs are modelled by a non-homogeneous Poisson process. An efficient marginal analysis algorithm is presented for finding the optimal failure number for replacement that minimizes the average cost rate.     

考虑电能与备用联合出清的日前调度优化方法

为解决电力现货市场与辅助服务市场改革不断深入带来的日前调度计划编制模式转变问题,提出了一种考虑电能与备用辅助服务联合出清的日前调度优化方法。首先,剖析了电能与备用辅助服务之间的耦合关系,从机组运行特性和电网承载能力两个维度出发明确了电能与备用联合出清中需要考虑的运行约束项。接着,以综合购电成本最低为优化目标,全面考虑电网运行、电力平衡、机组运行等三方面约束条件,构建了电能与备用辅助服务联合出清下的日前调度优化模型。并根据模型特点,明确了求解方法。最后基于我国某省区电网实际数据构造的算例表明,该方法能够有效提升发电资源调用效率,避免由于备用均摊等方式造成的发电机组中标量超过系统承载能力或发电机组发电能力的问题。     

Profit function analysis of system with mixture of warm and cold standby

This paper deals with the profit function analysis of a single-server two-unit standby system with two modes of each unit normal (N) and total failure (F). Regarding the standby unit, an interconversion is made repeatedly after a random length of time from warm to cold and cold to warm. Upon failure of the operative unit, the standby unit, if it is warm, starts the operation instantaneously; otherwise the system goes down until the cold standby starts operation. System failure occurs when both units fail totally. Identifying the system at suitable regenerative instants, integral equations are set up and explicit expressions of interest to system designers are obtained to carry out the profit function analysis. The results of two particular cases are also derived.