双余度核电DEH设计与马尔科夫模型分析

可靠性在核电汽轮机数字电液控制系统(Digital electro-hydraulic control system,DEH)质量中至关重要;从提升系统可靠性的角度出发,分析了核电DEH的工作原理,设计了基于异构处理器的核电DEH系统,给出了 DEH的系统架构、硬件构成及双余度设计方案;基于马尔科夫过程理论建立了双余度核电DEH的可靠度函数模型,结合可靠性框图及双余度系统状态转移图对核电DEH做了失效分类;引入失效率、维修率、共因失效因子与诊断覆盖率等参数,建立了状态转移方程,分析了系统在不同生命周期基于马尔科夫模型的可靠度;通过一个实例检验了双余度核电DEH的可靠性,为工程设计人员提供了指导与参考.     

无人机多余度航空电子系统研究与应用

无人机航空电子系统余度技术的利用大大提高了无人机系统的可靠性和安全性;通过分析多余度航空电子系统的可靠度方案,选取了合适的航空电子系统余度构型,并提出了适合三余度航空电子系统的余度架构和余度管理策略;另外对采用了基于余度策略的航空电子系统的关键技术——余度管理技术进行了研究,分析了航空电子系统余度管理的任务,在此基础上提出了管理算法方案;最后,建立了系统的可靠性模型,采用数值计算的方法,得到了系统可靠性的变化结果,为无人机航空电子系统余度设计提供了可供参考的依据。     

三余度飞控计算机关键技术研究及工程实现

针对小型飞行器飞控计算机可靠性指标要求,介绍了运用余度技术提高其可靠性与容错能力的方法,提出了采用三余度技术保证飞控计算机可靠性的设计方案,通过选择合适的冗余模式,建立了三余度飞控计算机的架构模型,经过详细分析与研究各模块结构,给出了余度策略、同步算法、表决面选取等关键技术工程实现的硬件电路与软件流程,仿真验证与试验结果表明,该方案设计合理,不仅较好地完成了飞控计算机的余度管理任务,而且有效地保证了系统的可靠性与容错能力。     

自监控二余度飞控计算机系统设计

提出了一种自监控二余度飞行控制计算机系统结构,并运用马尔科夫模型分析了系统的可靠性和安全性,描述了其结构特点和工作原理.讨论了本系统的余度管理关键技术,设计了在实时嵌入式操作系统VxWorks中,双机之间运用共享内存方式和共享信号量进行数据传输的方法,并且给出了设计流程和操作过程.采用了软硬件相结合的方式实现了系统的同步,这样的设计使得系统结构紧凑,可靠性和安全性得到了很大提高,方案切实可行.     

飞控计算机的余度架构及可靠性研究

余度架构设计是解决飞控计算机可靠性问题的有效途径.基于高可靠性飞控计算机系统对可靠性和容错性的特殊要求,提出一种新型三余度飞控计算机的余度架构方案,简要描述飞控计算机冗余设计方法,给出软硬件的总体框架设计,最后利用马尔可夫方法对该方案进行可靠性分析,通过观察故障覆盖率和失效率对飞控计算机整体可靠性的影响,验证了此余度架构方案的可行性.     

飞控系统余度管理算法在VxWorks中的实现

利用余度技术可以大大提高飞行控制计算机系统的可靠性和容错能力,余度设计的关键技术就是余度管理策略和方法,系统的故障容错能力主要是通过系统的余度管理来实现的。在有效的余度管理算法研究的前提下,结合嵌入式实时操作系统VxWorks的特点,详细描述了二余度飞控计算机系统余度管理算法在VxWorks中的调度策略。给出了设计流程和操作过程。采用这样的设计使得系统结构紧凑,提高了系统的实时性和安全性要求。     

无人飞行器伺服系统余度控制接口的设计与实现

介绍了一种在无人飞行器中设计应用的伺服系统余度控制接口,该接口实现了数字总线和模拟量两余度接口控制,可有效提高伺服系统的可靠性和抗干扰能力;分析了无人飞行器机载伺服系统的结构组成和工作模式,选择了CAN总线作为机载数字通讯总线,论述了机载伺服系统余度控制接口的工作原理,同时给出了伺服控制器的硬件接口电路及软件工作流程;实验结果表明余度控制接口工作稳定,控制通道转换平稳,该接口能满足无人飞行器控制系统的要求。     

基于270V的双余度无刷直流电机磁-热耦合分析

将余度技术引入到高压无刷电机设计中来,设计了两套定子绕组同槽嵌放和隔槽嵌放两种结构,并建立了两种结构下的双余度无刷直流电机数学模型,推导了电压平衡方程式.建立了双余度无刷直流电机的电磁场模型,并利用magnet对其进行了电磁场仿真,对比分析了单绕组工作,双余度隔槽工作和同槽工作时的转矩、转速等动态性能指标.并建立了双余度无刷直流电机的磁热耦合分析模型,对其双余度工作时的热场进行了仿真.仿真结果表明,双余度无刷直流电机在运行过程中,可以达到与单绕组工作时相同的动态特性,转矩为单绕组工作时的2倍,且大大提高了系统的可靠性.     

混合三余度无人机飞控计算机硬件结构设计及可靠性分析

飞控计算机是整个无人机飞控系统的核心部件,其可靠性直接影响着无人机的飞行安全;为了提高飞控计算机的稳定性和可靠性,结合工程实践,提出了一种混合三余度无人机飞控计算机硬件结构设计方案,概括描述了各组成部分的工作原理,并采用马尔科夫模型对该方案进行了可靠性分析;数据结果表明,混合三余度无人机飞控计算机较单机可靠性有了明显提高,满足无人机飞控计算机的可靠性要求,可作为高可靠性长航时无人机飞控计算机设计的参考方案。     

时滞系统的状态预测观测器及预测控制器设计

研究基于状态空间模型的时滞控制系统的状态预测观测器及最优预测控制器的设计问题。针对控制项含有时滞的系统，设计一种全维状态预测观测器，并将其用于时滞控制系统的最优状态预测反馈控制。通过该状态预测观测器可将闭环系统的时滞项移至系统闭环结构之外，从而使其优化控制规律完全可按无时滞系统进行设计。所给出的性能指标计算公式表明，该预测控制器关于二次型性能指标是次优的。     

Bi-objective optimization of the reliability-redundancy allocation problem for series-parallel system

The main objective of this paper is to solve the bi-objective reliability redundancy allocation problem for series-parallel system where reliability of the system and the corresponding designing cost are considered as two different objectives. In their formulation, reliability of each component is considered as a triangular fuzzy number. In order to solve the problem, developed fuzzy model is converted to a crisp model by using expected values of fuzzy numbers and taking into account the preference of decision maker regarding cost and reliability goals. Finally the obtained crisp optimization problem has been solved with particle swarm optimization (PSO) and compared their results with genetic algorithm (GA). Examples are shown to illustrate the method. Finally statistical simulation has been performed for supremacy the approach.     

Cost-oriented task allocation and hardware redundancy policies in heterogeneous distributed computing systems considering software reliability

Task allocation policy and hardware redundancy policy for distributed computing system (DCS) are of great importance as they affect many system characteristics such as system cost, system reliability and performance. In recent years, abundant research has been carried out on the optimal task allocation and/or hardware redundancy problem, most of which took a reliability-oriented approach, i.e., the optimization criterion was system reliability maximization. Nevertheless, besides system reliability, other system characteristics such as system cost may be of great concern to management. In this paper, we take a cost-oriented approach to the optimal task allocation and hardware redundancy problem for DCS, which addresses both system cost and system reliability issues. A system cost model which could reflect the impact of system unreliability on system cost is developed, and by minimizing the total system cost, a satisfactory level of system reliability could be reached simultaneously. In the reliability modeling and analysis of DCS, we take both hardware reliability and software reliability into account. Two numerical examples are given to illustrate the formulation and solution procedures, in which genetic algorithm is used. Results show that based on the developed system cost model, appropriate decision-makings on task allocation and hardware redundancy policies for DCS could be made, and the result obtained seems to be a fairly good trade-off between system cost and system reliability.     

Multi-objective reliability-redundancy allocation problem using particle swarm optimization

This paper considers the multi-objective reliability redundancy allocation problem of a series system where the reliability of the system and the corresponding designing cost are considered as two different objectives. Due to non-stochastic uncertain and conflicting factors it is difficult to reduce the cost of the system and improve the reliability of the system simultaneously. In such situations, the decision making is difficult, and the presence of multi-objectives gives rise to multi-objective optimization problem (MOOP), which leads to Pareto optimal solutions instead of a single optimal solution. However in order to make the model more flexible and adaptable to human decision process, the optimization model can be expressed as fuzzy nonlinear programming problems with fuzzy numbers. Thus in a fuzzy environment, a fuzzy multi-objective optimization problem (FMOOP) is formulated from the original crisp optimization problem. In order to solve the resultant problem, a crisp optimization problem is reformulated from FMOOP by taking into account the preference of decision maker regarding cost and reliability goals and then particle swarm optimization is applied to solve the resulting fuzzified MOOP under a number of constraints. The approach has been demonstrated through the case study of a pharmaceutical plant situated in the northern part of India.     

SpaceWire总线冗余备份优化方法

在现场可编程门阵列(FPGA)资源有限的情况下,提出一种基于FPGA的SpaceWire总线冗余备份优化方法。采用调整内部功能子模块可靠度的方法,实现整个系统的备份优化,提高系统可靠性。根据失效率λ计算节点内各功能子模块的可靠度。基于评分分配法,计算每个子模块所应达到的可靠度指标。同时从数学角度,基于线性规划理论寻找冗余备份优化问题最优解。仿真实验结果表明,该方法能够在满足可靠度要求的前提下节约FPGA的片上资源。     

Reliability Measure Based on Average Loss of Capacity

We present an effective measure of system reliability based on average loss of call capacity that is appropriate for telecommunication hardware. We are led to consider a system consisting of units with many states with appropriately chosen performance effectiveness indices, while all atomic units are binary. In this respect, this effective measure of partial system availability is a variant of customer-centered reliability methodology. We also identify the importance of a new structure called a 'pool' that behaves as a hybrid of series and parallel configurations. We present an algorithm for approximately calculating partial system unavailability, which solves the system decomposition problem for arbitrarily complex highly reliable systems made of hierarchically arranged k-out-of-n sub-structures. The algorithm agrees with our intuition for important special cases and has been programmed into an object oriented software tool. This method has been successfully used for the reliability analysis of Globalstar^TM gateways.     

并行任务可靠性约束下的资源最小化调度

可靠性是系统的一项重要质量指标,在安全关键的系统中极其重要.应用资源冗余的方式可以提高系统的可靠性,但会消耗更多的系统资源.研究了异构多处理器系统执行并行任务时最小化系统资源并保证可靠性的问题.首先以任务在各处理器上的平均最坏执行时间为参考,将系统可靠性目标转换为单个任务的可靠性目标,分别给出了非复制和复制情况下任务可靠性目标的计算方法;然后设计了一个可靠性约束下的资源最小化非复制算法,当给出的可靠性目标要求不高于系统可达到的最高可靠性时,该算法总能将任务分配到合适的处理器并使系统满足可靠性要求.由于非复制算法不能满足系统更高可靠性目标要求,最后设计了2个基于任务复制的算法.应用实际并行任务和随机生成的并行任务将提出的算法和MaxRe算法、RR算法以及MRCRG算法进行比较,实验结果表明：提出的算法在满足系统可靠性目标的同时消耗的资源更少.     

云计算任务冗余调度优化模型

为了解决现有云计算平台的高度动态性和异构性带来的可靠性低的问题,提出了一种基于冗余调度的可靠云计算模型。针对云计算按需付费的特点,基于该可靠模型,建立了基于服务费用约束的冗余调度优化模型,以保证在该费用约束下获得最大的云计算服务可靠性。最后,用遗传算法解决该最优冗余分配问题。     

Optimal cost effective design of hybrid hardware redundant systems

In many critical applications of digital systems, fault tolerance has been an essential architectural attribute for achieving high reliability. We address the problem of designing an optimal hybrid hardware redundant system. The designer of a system is always confronted with the problem of trading off reliability against cost. On the one hand, it is essential to provide for each vital module of the system as many spare units as possible in order to ensure high reliability. On the other hand, it is essential not to have an excessively costly, heavy or bulky system. In this paper we determine the optimal number of spare units which minimizes the expected total system cost. A numerical example is provided to illustrate the methods.     

Reliability evaluation and optimal design in heterogeneous multi-state series-parallel systems

This paper addresses the heterogeneous redundancy allocation problem in multi-state series-parallel reliability structures with the objective to minimize the total cost of system design satisfying the given reliability constraint and the consumer load demand. The demand distribution is presented as a piecewise cumulative load curve and each subsystem is allowed to consist of parallel redundant components of not more than three types. The system uses binary capacitated components chosen from a list of available products to provide redundancy so as to increase system performance and reliability. The components are characterized by their feeding capacity, reliability and cost. A system that consists of elements with different reliability and productivity parameters has the capacity strongly dependent upon the selection of constituent components. A binomial probability based method to compute exact system reliability index is suggested. To analyze the problem and suggest an optimal/near-optimal system structure, an ant colony optimization algorithm has been presented. The solution approach consists of a series of simple steps as used in early ant colony optimization algorithms dealing with other optimization problems and offers straightforward analysis. Four multi-state system design problems have been solved for illustration. Two problems are taken from the literature and solved to compare the algorithm with the other existing methods. The other two problems are based upon randomly generated data. The results show that the method can be appealing to many researchers with regard to the time efficiency and yet without compromising over the solution quality.     

Entropy based region reducing genetic algorithm for reliability redundancy allocation in interval environment

This research paper presents a multi-objective reliability redundancy allocation problem for optimum system reliability and system cost with limitation on entropy of the system which is very essential for effective sustainability. Both crisp and interval-valued system parameters are considered for better realization of the model in more realistic sense. We propose that the system cost of the redundancy allocation problem depends on reliability of the components. A subpopulation and entropy based region reducing genetic algorithm (GA) with Laplace crossover and power mutation is proposed to determine the optimum number of redundant components at each stage of the system. The approach is demonstrated through the case study of a break lining manufacturing plant. A comprehensive study is conducted for comparing the performance of the proposed GA with the single-population based standard GA by evaluating the optimum system reliability and system cost with the optimum number of redundant components. Set of numerical examples are provided to illustrate the effectiveness of the redundancy allocation model based on the proposed optimization technique. We present a brief discussion on change of the system using graphical phenomenon due to the changes of parameters of the system. Comparative performance studies of the proposed GA with the standard GA demonstrate that the proposed GA is promising to solve the reliability redundancy optimization problem providing better optimum system reliability.