冗余技术在捷联惯导系统中的应用研究

在简要介绍冗余技术的基本概念和发展状况的基础上，指出了目前飞行器控制系统存在的主要问题，并将冗余技术引入捷联惯导系统，使捷联惯导系统可靠性迅速提高，同时获得了大量重复测量数据。最后给出了工程应用实例，并探讨了进行冗余设计时需要注意的几个问题。     

战术导弹发动机无线电干扰滤波器可靠性验证试验

战术导弹发动机无线电子干扰滤波器是确保导弹发动机战勤安全的一个重要电子产品。为了评价它的可靠性，需对其进行可靠性验证试验。据此，结合一种导弹发动机无线电干扰滤波器的可靠性验证试验，讨论了其可靠性验证试验的数学模型，试验方案设计和试验方面的有关问题。     

Three frequency GNSS navigation prospect demonstrated with semi-simulated data

Three frequency GNSS (Global Navigation Satellite Systems) signals will be fully accessible in the near future. It is theoretically well-understood that the GNSS navigation performance could be improved with introduction of the third frequency signals. However it remains unclear what numerical improvements can be achieved in the varying navigation scenarios. In this paper, we numerically demonstrate the superior navigation prospect of three frequency GNSS compared to dual-frequency case. Since the third frequency pseudorange is not fully accessible at current stage, a semi-simulation method is firstly introduced to generate the third frequency pseudorange based on the dual-frequency GPS pseudorange and phase measurements. Then the three frequency navigation precision, availability and reliability are examined, compared with their dual-frequency counterparts in varying simulated navigation scenarios. The results show that with three frequency GNSS signals the navigation precision can be improved by 10% in both horizontal and vertical components. More promisingly, the availability of navigation solutions is significantly improved (even by 50% for some scenarios) with higher reliability.     

KWD—502型可控硅稳压电源故障分析与测试

结合电路工作原理，重点介绍了ＫＷＤ－５０２型可挂硅直流稳压电源四种故障类型的分析处理及其测试方法，以便确保它在测量过程中的使用可靠性。     

Scatter factor confidence interval estimate of least square maximum entropy quantile function for small samples

Classic maximum entropy quantile function method (CMEQFM) based on the probabil-ity weighted moments (PWMs) can accurately estimate the quantile function of random variable on small samples, but inaccurately on the very small samples. To overcome this weakness, least square maximum entropy quantile function method (LSMEQFM) and that with constraint condition (LSMEQFMCC) are proposed. To improve the confidence level of quantile function estimation, scatter factor method is combined with maximum entropy method to estimate the confidence inter-val of quantile function. From the comparisons of these methods about two common probability distributions and one engineering application, it is showed that CMEQFM can estimate the quan-tile function accurately on the small samples but inaccurately on the very small samples (10 sam-ples); LSMEQFM and LSMEQFMCC can be successfully applied to the very small samples;with consideration of the constraint condition on quantile function, LSMEQFMCC is more stable and computationally accurate than LSMEQFM; scatter factor confidence interval estimation method based on LSMEQFM or LSMEQFMCC has good estimation accuracy on the confidence interval of quantile function, and that based on LSMEQFMCC is the most stable and accurate method on the very small samples (10 samples).     

潜在电路分析技术及在航天控制系统中的应用

简要介绍潜在电路分析（ＳＣＡ）技术的原理及实施方法，以及在我国航天控制系统中的初步研究成果，以期引起重视，推动这项研究在我国的进一步开展。     

Reliability analysis based on a novel density estimation method for structures with correlations

Estimating the Probability Density Function (PDF) of the performance function is a direct way for structural reliability analysis,and the failure probability can be easily obtained by integration in the failure domain.However,efficiently estimating the PDF is still an urgent problem to be solved.The existing fractional moment based maximum entropy has provided a very advanced method for the PDF estimation,whereas the main shortcoming is that it limits the application of the reliability analysis method only to structures with independent inputs.While in fact,structures with correlated inputs always exist in engineering,thus this paper improves the maximum entropy method,and applies the Unscented Transformation (UT) technique to compute the frac tional moments of the performance function for structures with correlations,which is a very efficient moment estimation method for models with any inputs.The proposed method can precisely estimate the probability distributions of performance functions for structures with correlations.Besides,the number of function evaluations of the proposed method in reliability analysis,which is determined by UT,is really small.Several examples are employed to illustrate the accuracy and advantages of the proposed method.     

Reliability evaluation of avionics system with imperfect fault coverage and propagated failure mechanisms

Fault tolerance designs are essential techniques for systems that require high levels of reliability, such as aircraft or spacecraft control system. Imperfect Fault Coverage (IFC) may lead to the failure of a system or subsystem even with adequate redundancy. Previous studies of IFC mostly concentrated on evaluating Coverage Factor (CF), whereas the system failure behaviors with IFC have rarely been involved. Failures that occur in low-layer may be covered by high-layer. However, if the coverage is imperfect, uncovered failure will have functional and physical impact on the system behavior. In this thesis, the failure behavior and reliability of IFC of multi-layer systems are studied and a Binary Decision Diagram (BDD)-based modeling and simulation method are proposed to evaluate system reliability. As a case, the failure behavior of an aero engine electronic controller with IFC is studied. The results show that the IFC may impact system behavior without taking the IFC into account, the system maintenance intervals may reduce, and thus the maintenance costs will increase.     

General aspects on structural integrity

This paper seeks to mark the fruitful collaborative research between scholars in the University of Southampton and Beihang University for last 25 years on structural integrity. Their efforts addressed some important issues in structural integrity such as fatigue and fracture behavior,fatigue load spectra, fatigue and fracture lifetimes, reliability-based service period, adhesively bonded composite patch repairs, Plain Woven Fabric(PWF) composites and composite artefacts.New advances in engineering approaches, experimental methods, numerical algorithms and understanding of failure mechanisms relating to structural integrity are highlighted. Probable limits(or drawbacks) are also discussed. This review provides an insight into the general aspects on structural integrity and constitutes a basis for pointers to the further works on structural integrity.     

基于签名的控制流错误检测算法检测能力的验证模型

目前主要采用实验测试的方法对基于签名的控制流错误检测算法进行评价,但由于控制流错误模型的不确定性,而导致测试结果存在一定的偏差,本文尝试采用模型验证的方法评价控制流检测算法的错误检测能力。本文首先简述了基于签名的控制流错误检测算法的基本原理,其次,提出了控制流错误跳转关系表示方法和指出了传统的控制流错误检测能力分析方法中未考虑的影响检测能力的因素,接下来,结合这些因素提出了基于签名的控制流错误检测能力验证模型,最后给出实例,通过验证模型分析了目前典型的基于签名的控制流错误检测能力。