适用于海底观测网络的恒流远供系统可靠性分析方法

以水下单元的短路/开路故障模式为基础,提出一种分析缆系海底观测网络恒流远供系统可靠性的方法。根据系统供电和结构特性,将系统分成不同的供电链路和链路段。详细研究处于不同位置的各种水下单元发生故障时,对链路和观测设备的供电状态的影响。归纳导致系统和各链路无法正常导通、观测设备无法得到供电的状态情况,分析不同故障状态发生的概率,进而得出求解系统、供电链路与供电设备的供电可靠度的方法。通过算例分析,进一步梳理了3种供电可靠性的共性规律,说明在设计和建设恒流远供系统时,应综合考量这3种供电可靠性。     

基于正交试验法的冗余捷联惯组故障诊断实验方法研究

冗余捷联惯组是运载火箭控制系统的重要设备,需要对其进行故障检测和隔离以保证系统正常工作,所应用的故障检测算法需要进行有效性评估。由于惯组器件配置和故障形式的多样性,所有故障情形进行逐一测试不可能的,因此提出利用正交试验法安排实验,对广义似然比故障检测算法进行性能检测。试验结果表明应用正交试验实现了故障情形的良好覆盖性,有效减少了试验次数,并且从测试数据中验证了故障检测算法的有效性。     

Understanding the ‘failure’ of the Séléka rebellion

This paper examines the downfall of the Séléka rebellion, which staged a coup in the Central African Republic in March 2013. The coup plunged the country into violence and chaos, and there has been an uneasy quest for peace ever since. This article explains why the leader of the rebellion lost control over his troops and was finally pushed by regional actors to leave power. The article concludes that the Séléka rebellion was already fragile and, together with the poor leadership demonstrated by the coalition leader, the rebellion was unable to hold on to power.     

Investigation on the foaming behaviors of NC-based gun propellants

To prepare the porous NC-based (nitrocellulose-based) gun propellants, the batch foaming process of using supercritical CO₂ as the physical blowing agent is used. The solubilities of CO₂ in the single-base propellants and TEGDN (trimethyleneglycol dinitrate) propellants are measured by the gravimetric method, and SEM (scanning electron microscope) is used to observe the morphology of foamed propellants. The result shows that a large amount of CO₂ could be dissolved in NC-based propellants. The experimental results also reveal that the energetic plasticizer TEGDN exerts an important influence on the pore structure. The triaxial tensile failure mechanism for solid-state nucleation is used to explain the nucleation of NC-based propellants in the solid state. Since some specific foaming behaviors of NC-based propellants can not be explained by the failure mechanism, a solid-state nucleation mechanism which revises the triaxial tensile failure mechanism is proposed and discussed.     

On a class of multiple failure mode systems

The primary objective of this work is to introduce and perform a detailed study of a class of multistate reliability structures in which no ordering in the levels of components' performances is necessary. In particular, the present paper develops the basic theory (exact reliability formulae, reliability bounds, asymptotic results) that will make it feasible to investigate systems whose components are allowed to experience m ≥ 2 kinds of failure (failure modes), and their breakdown is described by different families of cut sets in each mode. For illustration purposes, two classical (binary) systems are extended to analogous multiple failure mode structures, and their reliability performance (bounds and asymptotic behavior) is investigated by numerical experimentation. © 2002 Wiley Periodicals, Inc. Naval Research Logistics 49: 167–185, 2002; DOI 10.1002/nav.10007     

锚杆支护岩质边坡地震动力响应分析

目前的锚杆支护边坡地震动力设计主要采用拟静力的方法，无法考虑锚杆和边坡在地震作用下的相互作用，汶川地震边坡破坏现象调研表明，锚杆具有良好的抗震效果，所以有必要对锚杆抗震效果进行研究。利用动力有限差分软件FLAC^3D，通过分析一个岩质边坡算例坡面上监测点动力响应加速度峰值放大系数在锚杆支护前后变化，研究了锚杆在各种不同地震波作用下的抗震效果。结果表明：在不同地震波作用下，锚杆都能显著降低坡面加速度峰值放大系数，提高边坡的动力稳定性，具有良好的抗震效果。最后结合强度折减动力分析法对锚杆在地震作用下的破坏机理进行了研究，为锚杆支护边坡的抗震设计奠定基础。     

基于LUT的射频预失真技术

分析了当前文献中几种主要的预失真结构,发现这些预失真结构均不适用于多通道宽频带短波通信中高功率放大器的线性化.提出了一种新的数字射频预失真方案,该方案能够完全适应短波宽频通信的高精度、多通道、宽频带的要求,而且不需要使用射频非线性有源器件.仿真结果表明,在短波通信系统采用这种方案,可以在很大程度上改善功率放大器的线性度.     

舰用锅炉耐火纤维材料的失效模式和失效机理研究

针对舰用锅炉现用硅酸铝质耐火纤维材料,采用晶相显微分析、X 射线衍射分析(XRD)和激光粒度分析(LMS)等现代材料分析手段对其失效模式和失效机理进行了研究分析,研究结果为新型耐火材料的研制或改进提供了重要依据.     

装甲车辆使用故障探讨

从装甲车辆的故障及分类入手,引入使用故障的概念,以装甲车辆使用、维护过程中发生的典型使用故障案例为基本素材,运用归纳、分析的方法,真实体现使用故障的原因,客观提出预防使用故障的对策.     

有限次故障小修模型

针对具有小修的维修策略问题,在提出一定的假设条件后,建立经过长期运行后的单位时间期望损失的模型,研究并分析了有限次故障小修模型,最后通过相应的示例验证了研究结果。