Two novel critical shock models based on Markov renewal processes

In this paper, we investigate systems subject to random shocks that are classified into critical and noncritical categories, and develop two novel critical shock models. Classical extreme shock models and run shock models are special cases of our developed models. The system fails when the total number of critical shocks reaches a predetermined threshold, or when the system stays in an environment that induces critical shocks for a preset threshold time, corresponding to failure mechanisms of the developed two critical shock models respectively. Markov renewal processes are employed to capture the magnitude and interarrival time dependency of environment-induced shocks. Explicit formulas for systems under the two critical shock models are derived, including the reliability function, the mean time to failure and so on. Furthermore, the two critical shock models are extended to the random threshold case and the integrated case where formulas of the reliability indexes of the systems are provided. Finally, a case study of a lithium-ion battery system is conducted to illustrate the proposed models and the obtained results.     

深化党的建设制度改革的几点思考

党的十八届三中全会在总结历年来党的建设经验、不断深化对党的建设规律认识和把握的基础上,把制度建设放在了突出地位,明确强调：“紧紧围绕提高科学执政、民主执政、依法执政水平,深化党的建设制度改革。”现阶段,要全面建成小康社会,加快推进社会主义现代化,就必须深化党的建设制度改革,为全面深化改革提供坚强的政治保证。     

化学键合胶凝材料抗硫酸盐侵蚀性能

采用浸-烘循环的方法模拟干湿循环交替环境进行新型化学键合胶凝材料抗硫酸盐加速侵蚀试验.侵蚀溶液为质量浓度为5％的硫酸钠溶液,一组试验采用全浸-烘循环,另一组试验采用半浸-烘循环.在经受30×N(N=1,2,3,4,5)次循环后,测定试件的强度耐蚀系数和质量损失率,以此评价化学键合胶凝材料抗硫酸盐侵蚀性能.试验结果表明:半浸-烘循环的侵蚀比全浸-烘循环的侵蚀严重;在经受150次侵蚀循环后,试件外观无严重破损,质量不减反增,强度也不降低,说明化学键合胶凝材料具有优良的抗硫酸盐侵蚀性能.     

Pakistan’s nuclear weapons: how safe is safe enough? Transparency versus opacity

Due to expanding and increasing religious extremism and terrorism coupled with political instability in Pakistan, most western observers believe that Pakistan's nuclear weapons are not secure and could be taken over by terrorists. This would have adverse implications for the region and for global peace, especially for the security of USA and Europe. This article argues that this perception is based on a flawed understanding and knowledge of how Pakistan's command and control setup has evolved and operates. Pakistan's nuclear weapons are as safe as any other state's nuclear weapons. Pakistan has also been active in supporting and participating in global efforts to improve nuclear safety and security. Over the years, Pakistan has been quite open in sharing information regarding how it is improving its command and control system with western governments as well as scholars. This article argues that the steps Pakistan has taken to secure its nuclear weapons are adequate and that Pakistan would continue to further strengthen these measures; however, it is the expanding religious extremism, terrorism and anti-Americanism in the country which make the international perception of Pakistan extremely negative and then seep into the perception of Pakistan's nuclear weapons safety and security.     

军用装备镁合金表面微弧氧化层SEM微观形貌及耐蚀性分析

利用微弧氧化技术的恒电流方式,在含有Na：SiO,和KF等电解质的溶液中制备了AZ91D镁合金微弧氧化层,通过扫描电镜观察分析及Cu加速盐雾腐蚀试验,研究了电解液中Na：SiO,和KF质量浓度对微弧氧化层结构及耐蚀性的影响。结果表明：在相同反应条件下,微弧氧化层厚度和表面粗糙度随Na：SiO,和KF质量浓度的增加而增加,微弧氧化层的耐蚀性取决于其表面粗糙度和厚度,粗糙度小、具有一定厚度的致密微弧氧化层耐蚀性好。     

玄武岩纤维增强塑料筋耐海水腐蚀性研究

海工工程中由于海水的腐蚀,混凝土中的钢筋会出现锈蚀等问题.玄武岩纤维增强塑料筋作为一种新型建筑材料,用来代替钢筋用在海工工程等腐蚀性较强的混凝土中,以此避免钢筋锈蚀带来的耐久性问题.研究了玄武岩纤维增强塑料筋耐海水腐蚀性,采用常温长期浸泡和高温浸泡加速腐蚀试验方法,得出玄武岩纤维增强塑料筋在常温下耐海水腐蚀性较强,而在...     

3维C/SiC-ZrC复合材料的制备及其性能研究

针对超高温环境应用需求,采用化学气相渗透工艺(CVI)与先驱体浸渍-裂解工艺(PIP)联用制备了3维碳纤维增强SiC-ZrC基复合材料(C/SiC-zrC),并研究了SiC含量对C/SiC-ZrC复合材料力学性能、抗氧化性能和抗烧蚀性能的影响.结果表明,随着SiC含量的增加,C/SiC-ZrC复合材料的强度逐渐降低,静...     

论实现党委科学决策应重点把握的三个要素

实现党委科学决策,必须在学习理论中“扩容”思维,在学习科技中“升级”本领,在学习党章中“硬化”原则,夯实党委决策的基础;必须运用选点实验的方法为决策“试车探路”,运用咨询专家的方法为决策“出谋划策”,运用信息化手段方法为决策“助推加力”,丰富党委决策的方法;必须建立健全调研论证、民意表达、监督制约、失误追究等制度,规范党委决策的流程。     

舰空导弹武器系统作战效能评估综述

在舰空导弹武器系统作战效能评估研究现状基础上,分析武器系统作战效能评估的关键研究方向,如作战效能评估方法及模型、作战指挥效能评估、武器系统使用可用性评估、人机系统可靠性评估、武器系统生存能力评估、任务完成程度评估、武器系统战场抢修研究等,展望了该研究领域的发展动向。     

地空导弹反导作战拦截次数计算模型及仿真

在分析地空导弹武器系统拦截来袭目标过程的基础上,通过分析地空导弹发射区纵深建立了地空导弹武器系统可拦截次数模型.利用该模型可计算地空导弹武器系统对单个来袭目标在杀伤区内的拦截次数.仿真结果揭示了地空导弹武器系统在不同目标特性(速度、高度、航路捷径)下对目标的可拦截次数的影响.