北斗RDSS用户机测试系统关键技术研究

为了实现对北斗RDSS用户机检测的需求，研制了专用测试系统。介绍北斗RDSS用户机测试系统的基本组成和工作原理，分析了测试系统研制涉及到的部分关键技术：系统建模仿真、RDSS出站信号模拟、RDSS入站信号接收、入站信号质量分析等，最后列举了所研制的测试系统到达的主要技术指标。     

基于多指标综合评判法的空中加油机作战效能评估

针对空中加油机作战效能评估问题,构建了空中加油机作战效能评估指标体系,并对空中加油机的作战效能指标数据进行挖掘,利用信息熵概念求得各指标属性的重要度,并归一化处理为各效能指标的权重系数,克服了传统权重系数确定方法的主观性;然后,建立了基于理性解法的空中加油机作战效能多指标综合评价模型;最后,通过实例,对几种现役典型的空中加油机作战效能进行了评估,并得到了计算结果,同时验证了该模型的有效性。     

民用运输机积水跑道附加阻力计算评估方法

飞机在污染跑道上起降时,污染物产生的附加阻力对飞机的起降性能有很大影响。分析了积水跑道上附加阻力的形成机理,研究了附加阻力的计算评估方法。算例分析表明,该方法的计算结果规律正确、量级合理,达到了工程应用要求。     

计算机辅助功能危险评估方法研究

功能和安全一直是高风险复杂系统的关键问题。传统的功能危险评估由安全工程师手工进行分析，面对高度复杂系统时，就会变得难以完成且容易出错。解决这种问题的一个途径就是利用计算机进行辅助。为此提出一种计算机辅助的功能危险评估方法，采用状态图语言搭建系统状态模型，将功能失效影响直观地从系统状态转移图上表达出来。并且在系统状态模型的基础上，采用计算机编程快速计算出导致系统故障的失效组合以及最小割集。最后以飞机为对象证明了方法的可行性。     

Satellite collision probability estimation using polynomial chaos expansions

This paper presents the application of polynomial chaos (PC) to estimating the probability of collision between two spacecraft. Common methods of quantifying this probability for conjunction assessment use either Monte Carlo analyses or include simplifying assumptions to improve tractability. A PC expansion, or PCE, provides a means for approximating the solution to a large set of stochastic ordinary differential equations, which includes orbit propagation. When compared to Monte Carlo methods, non-intrusive, i.e., sampling-based, PCE generation techniques may greatly reduce the number of orbit propagations required to approximate the possibly non-Gaussian, a posteriori probability density function. The presented PC-based method of computing collision probability requires no fundamental simplifying assumptions, and reduces the computation time compared to Monte Carlo. This paper considers two cases where the common conjunction assessment assumptions are no longer valid. The results indeed demonstrate a reduction in computation time when compared to Monte Carlo, and improved accuracy when compared to simplified techniques.     

基于分层体系的现代作战飞机方案评估

针对目前作战飞机方案评估中体系与方法的不足,依据飞机发展的时序性和评估内容的细化程度,确定了现代作战飞机方案评估的5个层次,它们分别为综合作战能力层、综合作战效能层、综合使用效能层、综合使用效费层和方案评价决策层.在分析各评估层特性的基础上,建立了各评估层的细化指标体系,改进和完善了各评估层的理论模型和计算方法,通过现...     

Space Debris Reentry Analysis Methods and Tools

The reentry of uncontrolled spacecraft may be broken into many pieces of debris at an altitude in the range of 75-85 km. The surviving fragments could pose great hazard and risk to ground and people. In recent years, methods and tools for predicting and analyzing debris reentry and ground risk assessment have been studied and developed in National Aeronautics and Space Ad-ministration (NASA), European Space Agency (ESA) and other organizations, including the group of the present authors. This paper reviews the current progress on this topic of debris reentry briefly. We outline the Monte Carlo method for uncertainty analysis, breakup prediction, and parameters affecting survivability of debris. The existing analysis tools can be classified into two categories, i.e. the object-oriented and the spacecraft-oriented methods, the latter being more accurate than the first one. The past object-oriented tools include objects of only simple shapes. For more realistic simulation, here we present an object-oriented tool debris reentry and ablation prediction system (DRAPS) developed by the present authors, which introduces new object shapes to 15 types, as well as 51 predefined motions and relevant aerodynamic and aerothermal models. The aerodynamic and aerothermal models in DRAPS are validated using direct simulation Monte Carlo (DSMC) method.     

一种基于事故树的安全风险定量评估方法

针对目前安全风险评估方法的不足,提出了基于事故树的飞机部件安全风险定量评估方法.首先采用布尔代数理论对事故树进行逻辑表述,通过概率重要度表示部件故障的后果严重度,在此基础上对飞机部件的危险度进行计算,解决了当前安全风险定量评估的难题.实例证明,该方法能够较为准确地检验飞机部件对飞行安全的影响.     

航空发动机健康评估技术综述

健康评估技术是航空发动机健康管理的关键技术之一。详细阐述了航空发动机健康评估的研究内容,重点分析了发动机气路性能、结构以及机械系统健康评估的特点,并指出了开展航空发动机健康评估关键技术研究的重要性。     

贝叶斯网络在飞控系统可靠性评估中的应用

把一种基于贝叶斯网络的故障树分析法应用于飞控系统俯仰控制功能的可靠性评估中,突破传统故障树分析法的局限性——各部件独立、状态为二值,不但可以计算系统的可靠性指标,而且可以定量给出某个事件或某几个事件在系统可靠性中所占的地位,找出系统的薄弱环节。