基于半实物的Ｓ频段卫星测控仿真系统平台设计

该仿真系统是为了满足Ｓ频段卫星测控演练的需要而提出的。根据航天测控系统和Ｓ频段测控设备的特点，明确了仿真系统的组成及功能，并对主要部分进行了详细的描述；确定了仿真系统运行工作模式、主要技术指标、接口之间关系；结合实际应用情况，通过与真星进行比对，证明通过建立半物理仿真数学模型，达到了在数据层上与真星具有等价性，并展望了未来发展方向。     

Reliability Analysis Method on Repairable System with Standby Structure Based on Goal Oriented Methodology

This paper presents a reliability analysis method on repairable system with standby structure based on goal oriented (GO) methodology. Firstly, a new combination of GO operator, which is composed of a new logical GO operator named Type 18A operator and a new auxiliary GO operator named Type 20 operator, is created to represent standby mode. The availability formula of standby equipment with translation exception is deduced based on Markov process theory. Then, the application method of combination of GO operator for standby mode and the analysis process of repairable system with standby structure based on GO method are proposed. Thirdly, this new combination of GO operator is applied in availability analysis of the hydraulic oil supply system of power‐shift steering transmission. Finally, the results obtained by the new GO method are compared with the results of fault tree analysis, Monte Carlo simulation, GO methods using Type 2 operator and Type 18 operator to represent the standby mode, respectively. And the comparison results show that this new GO method is applicable and reasonable for reliability analysis of repairable system with standby structure. All in all, this paper provides guidance for reliability analysis of repairable systems with standby structure. Copyright © 2015 John Wiley & Sons, Ltd.     

基于动态故障树的CTCS-3级ATP系统可靠性分析简

 针对传统的可靠性分析方法分析CTCS-3级ATP系统动态失效问题的不足,提出采用动态故障树分析其可靠性。首先,分析系统的结构和功能建立动态故障树模型;其次,采用深度优先最左遍历算法搜索动态故障树模型,得到独立的子树;最后,在引入可修系统可靠性指标基础上,采用解析法和马尔科夫矩阵迭代法求解子树,结合分层迭代方法对动态故障树分析法改进,以减小运算量,使得上述可靠性指标能用于CTCS-3级ATP系统的可靠性评估。计算所得可靠性指标与可靠性框图分析得到的结果对比表明：动态故障树能够更好地描述系统的冗余性和容错性等特点,提高了可靠性指标的精度。     

Identification of independent modules in fault trees which contain dependent basic events

The reliability performance of a system is frequently a function of component failures of which some are independent whilst others are interdependent. It is possible to represent the system failure logic in a fault tree diagram, however only the sections containing independent events can be assessed using the conventional fault tree analysis methodology. The analysis of the dependent sections will require a Markov analysis. Since the efficiency of the Markov analysis largely depends on the size of the established Markov model, the key is to extract from the fault tree the smallest sections which contain dependencies. This paper proposes a method aimed at establishing the smallest Markov model for the dependencies contained within the fault tree.     

Strategy and tool development for nuclear power plant design synthesis with measurement of reliability and simplicity

In this work, the conceptual design supporting tools for nuclear power plants have been developed. These tools are made for system synthesis, complexity measure and reliability analysis.This design synthesis program combined with the reliability analysis program accomplishes the system synthesis. This design strategy can reduce mistakes, effort and time. This design tool, based on Prolog language, is applied to the auxiliary feedwater system. A logic based fault tree analysis program (LOFT) is also developed using Prolog language. As LOFT performs symbolic computation during the fault tree analysis, linking with knowledge-base systems is very easy and the partial usage of the program is possible. The importance measure of components obtained from the system reliability analysis and the complexity measure of the system give very important information to the system designer.     

The Minimum Cut Sets of System Fault Based on Oriented Matrix Analysis

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Component-based modeling of systems for automated fault tree generation

One of the challenges in the field of automated fault tree construction is to find an efficient modeling approach that can support modeling of different types of systems without ignoring any necessary details. In this paper, we are going to represent a new system of modeling approach for computer-aided fault tree generation. In this method, every system model is composed of some components and different types of flows propagating through them. Each component has a function table that describes its input-output relations. For the components having different operational states, there is also a state transition table. Each component can communicate with other components in the system only through its inputs and outputs. A trace-back algorithm is proposed that can be applied to the system model to generate the required fault trees. The system modeling approach and the fault tree construction algorithm are applied to a fire sprinkler system and the results are presented.     

Posbist fault tree analysis of coherent systems

When the failure probability of a system is extremely small or necessary statistical data from the system is scarce, it is very difficult or impossible to evaluate its reliability and safety with conventional fault tree analysis (FTA) techniques. New techniques are needed to predict and diagnose such a system's failures and evaluate its reliability and safety. In this paper, we first provide a concise overview of FTA. Then, based on the posbist reliability theory, event failure behavior is characterized in the context of possibility measures and the structure function of the posbist fault tree of a coherent system is defined. In addition, we define the AND operator and the OR operator based on the minimal cut of a posbist fault tree. Finally, a model of posbist fault tree analysis (posbist FTA) of coherent systems is presented. The use of the model for quantitative analysis is demonstrated with a real-life safety system.     

基于改进的判定表的故障树建模方法

针对过程控制系统故障树建模问题提出了一种以步进方式求结构函数的判定表法。采取以事件为条件桩、0和1为条件项的二态判定表的方式,列举各事件所有可能的状态组合,根据每种情况下部件的相互作用演绎输出事件,然后对具有相同输出事件的事件序列求并集以排除重复事件和不相关事件,得到约简的结构函数。通过对硝酸冷却系统建模的验证,用这种方法建树的结果与原文的结果是一致的。     

基于决策树算法的多联机气分插反故障诊断

本文将决策树算法应用于多联机气分插反故障诊断中,搭建了多联机实验平台采集数据,根据专家知识及数据变化模型验证选取了建模的特征变量,采用决策树C5.0算法构建气分插反故障诊断模型,进一步对由模型分类规则生成的最优变量即过冷器的EEV（电子膨胀阀）进行深入分析和验证。结果表明：将决策树算法应用于多联机气分插反故障诊断的方法,准确率为96%,有较高的准确性和可靠性,此诊断方法能满足多联机故障诊断实际运用的需要。由于多联机发生气分插反故障时,系统过热度降低,为保证多联机系统的制冷效果和能效比,可通过增大过冷器EXV开度调节。     

Reliability modeling and optimization of K/N phased mission system with backup missions and global redundancy strategy

The mission success probability (MSP) is a critical indicator for phased mission systems (PMSs). In the modern aerospace industry, redundancy techniques, including component/phase redundancy, are commonly seen to increase the MSP of the whole system. These component/phase redundancies make the reliability analysis more complex. Meanwhile, one or more components are required for normal working for different subsystems, called the K/N structure. In this article, a Markov-process method is proposed for PMS with K/N subsystems and different redundancy strategies. Then, a universal system optimization model is proposed to optimize system structure and redundancy strategies for all subsystems at the same time. Then, an improved genetic algorithm (GA) is used to resolve the optimization problem. At last, a propulsion system is used as an engineering case, showing the proposed binary decision diagram-based method.     

合理利用测控资源的动态调度模型

通过研究小卫星系统测控需求，地面测控资源以及两者之间的关系，建立了一套测控资源动态调度数学模型，以反映小卫星测控要求和测控资源的函数关系，旨在寻找一种资源分配随时间动态改变的最优调度方法，本文提出的测控资源动态调度模型，可用于小卫星系统概念设计阶段运行费用的估算以及提高测控中心的自动化程度，从而保证小卫星大效益。     

我国航天测控系统的现状与发展

随着我国航天任务的日益复杂化、多样化，对测控的需求也向“高、精、尖”方向发展，航天测控系统再一次面临新的机遇与挑战。在综合分析国内外航天测控发展历程与现状的基础上，总结了航天测控的发展特点与发展趋势，提出了符合我国国情的“优化地基测控网、建设和发展天基测控网、构建深空探测网，循序渐进构建天地空一体化测控通信系统”的整体发展思路，并对我国地基、天基、深空探测测控通信系统发展及重点技术进行了分析探讨。     

Dynamic fault tree analysis using Monte Carlo simulation in probabilistic safety assessment

Traditional fault tree (FT) analysis is widely used for reliability and safety assessment of complex and critical engineering systems. The behavior of components of complex systems and their interactions such as sequence- and functional-dependent failures, spares and dynamic redundancy management, and priority of failure events cannot be adequately captured by traditional FTs. Dynamic fault tree (DFT) extend traditional FT by defining additional gates called dynamic gates to model these complex interactions. Markov models are used in solving dynamic gates. However, state space becomes too large for calculation with Markov models when the number of gate inputs increases. In addition, Markov model is applicable for only exponential failure and repair distributions. Modeling test and maintenance information on spare components is also very difficult. To address these difficulties, Monte Carlo simulation-based approach is used in this work to solve dynamic gates. The approach is first applied to a problem available in the literature which is having non-repairable components. The obtained results are in good agreement with those in literature. The approach is later applied to a simplified scheme of electrical power supply system of nuclear power plant (NPP), which is a complex repairable system having tested and maintained spares. The results obtained using this approach are in good agreement with those obtained using analytical approach. In addition to point estimates of reliability measures, failure time, and repair time distributions are also obtained from simulation. Finally a case study on reactor regulation system (RRS) of NPP is carried out to demonstrate the application of simulation-based DFT approach to large-scale problems.     

An efficient real‐time method of analysis for non‐coherent fault trees

Fault tree analysis is commonly used to assess the reliability of potentially hazardous industrial systems. The type of logic is usually restricted to AND and OR gates, which makes the fault tree structure coherent. In non‐coherent structures not only components' failures but also components' working states contribute to the failure of the system. The qualitative and quantitative analyses of such fault trees can present additional difficulties when compared with the coherent versions. It is shown that the binary decision diagram (BDD) method can overcome some of the difficulties in the analysis of non‐coherent fault trees. This paper presents the conversion process of non‐coherent fault trees to BDDs. A fault tree is converted to a BDD that represents the system structure function (SFBDD). An SFBDD can then be used to quantify the system failure parameters but is not suitable for the qualitative analysis. Established methods, such as the meta‐products BDD method, the zero‐suppressed BDD (ZBDD) method and the labelled BDD (L‐BDD) method, require an additional BDD that contains all prime implicant sets. The process using some of the methods can be time consuming and is not very efficient. In addition, in real‐time applications the conversion process is less important and the requirement is to provide an efficient analysis. Recent uses of the BDD method are for real‐time system prognosis. In such situations as events happen, or failures occur, the prediction of mission success is updated and used in the decision‐making process. Both qualitative and quantitative assessments are required for the decision making. Under these conditions fast processing and small storage requirements are essential. Fast processing is a feature of the BDD method. It would be advantageous if a single BDD structure could be used for both the qualitative and quantitative analyses. Therefore, a new method, the ternary decision diagram (TDD) method, is presented in this paper, where a fault tree is converted to a TDD that allows both qualitative and quantitative analyses and no additional BDDs are required. The efficiency of the four methods is compared using an example fault tree library. Copyright © 2008 John Wiley & Sons, Ltd.     

Fault tree developed by an object-based method improves requirements specification for safety-related systems

Fault tree analysis is frequently used to improve system reliability and safety. To be suitable for analysis of software in computerised safety-related systems, it has to be modified accordingly. This paper presents a new application: the fault trees developed by an object-based method. The object-based method integrates structural and behavioural models of a system. The developed fault tree includes information on structure and the failure behaviours of classes of the system. Away from traditional use of the fault tree, which for traditional systems emphasises qualitative and quantitative results, the result of the new application emphasises the process of fault tree development and its qualitative results. Such fault tree application reduces the probability of failures in the requirements specification phase within the software life cycle, which increases the reliability of its product; however, it does not confirm this in a quantitative manner.     

空间遥控机械手的声控识别与应答系统

描述了用自然语言控制空间遥控机械手执行远程操作的自然语言接口系统。该系统以孤立词语音识别为核心,着重于系统的可靠性和实用性。为此,在系统的开发过程中,考虑了人类语音交互的听觉感知特点、汉语的一字一音节特点、具体识识时语音的声学模型不必与其语言学模型严格一致的特点以及环境噪声对系统性能的影响等,提出以过渡段＋韵母段作为识别基元,采取多层识别策略进行识别。识别实验与仿真实验结果表明,系统达到了预期性能     

无人机发动机点火停车电路故障在线检测研究

为了解决某型无人机发动机的飞行故障隐患,通过对发动机点火停车电路所存在故障的模型研究,运用Pspice仿真软件对电路故障进行仿真,采用基于故障字典的故障诊断技术,建立了诊断故障字典．利用单片机设计了一套在线故障检测系统,提出了“状态传递”的测试策略进行测点优化,简化了系统设计,提高了故障诊断效率,实现了无人机发动机点火和停车电路故障的在线检测,确保了无人机的飞行安全和飞行任务的完成．     

A method of human reliability analysis and quantification for space missions based on a Bayesian network and the cognitive reliability and error analysis method

Analyses of human reliability during manned spaceflight are crucial because human error can easily arise in the extreme environment of space and may pose a great potential risk to the mission. Although various approaches exist for human reliability analysis (HRA), all these approaches are based on human behavior on the ground. Thus, to appropriately analyze human reliability during spaceflight, this paper proposes a space‐based HRA method of quantifying the human error probability (HEP) for space missions. Instead of ground‐based performance shaping factors (PSFs), this study addresses PSFs specific to the space environment, and a corresponding evaluation system is integrated into the proposed approach to fully consider space mission characteristics. A Bayesian network is constructed based on the cognitive reliability and error analysis method (CREAM) to model these space‐based PSFs and their dependencies. By incorporating the Bayesian network, the proposed approach transforms the HEP estimation procedure into a probabilistic calculation, thereby overcoming the shortcomings of traditional HRA methods in addressing the uncertainty of the complex space environment. More importantly, by acquiring more information, the HEP estimates can be dynamically updated by means of this probabilistic calculation. By studying 2 examples and evaluating the HEPs for an International Space Station ingress procedure, the feasibility and superiority of the developed approach are validated both mathematically and in a practical scenario.     

Reliability modelling of repairable systems using Petri nets and fuzzy Lambda–Tau methodology

A methodology is developed which uses Petri nets instead of the fault tree methodology and solves for reliability indices utilising fuzzy Lambda–Tau method. Fuzzy set theory is used for representing the failure rate and repair time instead of the classical (crisp) set theory because fuzzy numbers allow expert opinions, linguistic variables, operating conditions, uncertainty and imprecision in reliability information to be incorporated into the system model. Petri nets are used because unlike the fault tree methodology, the use of Petri nets allows efficient simultaneous generation of minimal cut and path sets.