状态维修下通指装备可用度评估

随着监测诊断技术的发展,状态维修在通指装备维修中应用范围越来越广。根据系统模块之间的并联供求关系,以系统可用度求解为目标,建立多态串并联可控系统可用度精确求解模型。在对模型进行求解的过程中运用发生函数算法,对算法的运用范围进行拓展。实例结果证明评估模型的精确性,对于装备状态评估具有更强的指导性。     

TA2-B10管不同电偶腐蚀防护方式对B10管腐蚀特性的影响

为研究TA2-B10合金管在不同电偶腐蚀防护方式下对B10管腐蚀特性的影响,在青岛小麦岛海水试验场设置TA2-B10管直接连接、电绝缘连接、电绝缘＋涂层连接三组不同电偶腐蚀防护方式对照管道,依次进行1m/s、3m/s、4m/s流动海水与浸泡交替腐蚀试验。对试验后的三组B10管道线切割,通过管道内表面电位分布试验分析不同电偶腐蚀防护方式下B10管道的腐蚀类型;采用动电位极化曲线、电化学阻抗谱和微观表征,分析不同电偶腐蚀防护方式下距离法兰接头250mm处B10管试样的腐蚀特性。结果表明,直接连接TA2-B10管处于电偶腐蚀状态,B10端内电位正移腐蚀加速,电绝缘连接和绝缘＋涂层连接TA2-B10管均处于自腐蚀状态,但电绝缘＋涂层连接具有更好的绝缘效果;电绝缘＋涂层连接防护下的B10试样,腐蚀电流密度最小,自腐蚀电位最负;三组B10试样阻抗谱均呈现单容抗弧特征,电绝缘＋涂层连接防护下的B10试样具有更大的传递电阻和膜层电阻;电绝缘＋涂层连接能有效减缓点蚀、坑蚀和晶间腐蚀三种腐蚀倾向。以上结果综合说明,绝缘＋涂层防护方式具有更好的电偶腐蚀防护效果。     

遥操作交会对接轨道共享控制策略

由于时延和测量、控制偏差的影响,环月轨道遥操作交会对接最终平移段的轨道控制面临诸多问题。针对这些问题,对遥操作交会对接共享控制策略进行研究。运用相对轨道动力学方程构造遥操作交会对接的数学模型,在此基础上推导时延条件下的预显示模型。在考虑可控边界的条件下构造对接安全走廊,提出基于改进人工势场的自控方法,势场函数将航天器与安全走廊的相对距离和逼近速度作为参考量。结合操纵人员的手动控制操作特性,推导共享控制的权重系数,形成共享控制策略。在九自由度遥操作交会对接半实物仿真平台开展仿真试验。仿真结果表明:相比于采用自动控制和手动控制方式而言,共享控制方式能有效克服时延的影响,显著提高环月轨道交会任务对接精度和成功率,改善环月轨道遥操作交会对接控制性能。     

Merkle-Damgård Hash结构并行扩展算法

利用松弛密码架构将Merkle-Damgrd结构的Hash算法扩展为并行结构的算法,可以利用多核处理器提高杂凑效率。给出的证明过程表明松弛密码架构在处理不同长度的消息时不具备抗碰撞特性。提出的新并行扩展算法基于松弛密码架构设计,该算法弥补了其安全缺陷,并给出了新并行Hash结构的安全性分析。分析结果表明新结构抗碰撞特性不低于Merkle-Damgrd结构的Hash算法。实验结果表明,新并行Hash结构处理长消息时有较高的处理性能。     

基于分形理论的微地形的重建

对自然地表分形特征进行了分析和总结,并结合微地形所具有的自然特性,提出了具有方向性分形特征的中点随机位移法。实验结果表明该方法能较好地反映原始数据的总体轮廓,而且还能较好地再现原始微地形的粗糙起伏及各向异性,因而是一种可行的构造三维地形的插值方法。     

带挠性附件双自旋卫星的 Liapunov 稳定准则

本文研究了带挠性附件双自旋卫星的姿态稳定性问题。假定挠性双自旋卫星由无内部活动部件的半刚性平台、半刚性转子以及固连于平台的挠性附件构成,选择姿态角和模态坐标表示的相对能量函数为Liapunov 函数,建立了挠性双自旋卫星姿态稳定性判据。     

浅谈消防作战指挥中心建设

分析消防作战指挥中心的职能和建设中存在的问题,就消防作战指挥中心建设,提出了统一标准,树立超前意识;确保人员编配;明确职责任务;规范值班制度;严抓业务培训;加强设备管理维护;整合社会资源,建立长效联动资源数据库等对策.     

PUBLIC ATTITUDES REGARDING UNDOCUMENTED MIGRATION AND POLICING/CRIME

The incessant bomb attacks by the Niger Delta militants and Boko Haram elements among other popular movements, against the people and government targets, have unmistakably put Nigeria on the global terrorist nations’ map. The grievances of these groups which are political, economic and religious may not be unconnected from the design and operation of the federation; this paper thus examines the constitutional provisions, and political and economic attributes, of the Nigerian federation in the Fourth Republic with a view to discovering why a mechanism put in place with the objective of achieving interethnic unity, democratic stability and socio-economic development has worked to enthrone crisis, violence and disintegrative tendencies in the country. This paper argues that the current reign of terror is a manifestation of a more serious de-linkage and inconsonance between the state and the people, with popular movements providing an alternative platform for spaces, voices and benefits from the streets and away from the state. The paper concludes that the hope for federal renewal lies in the ability of the current handlers of the Nigerian statecraft to marry decentralist constitutional reforms with an agenda for mass-based socio-economic development of the country.     

THE MIDDLE EAST WMD-FREE ZONE CONFERENCE

This article reviews the origins and evolution of the Middle East weapons of mass destruction-free zone (WMDFZ) concept and the proposal for a 2012 conference on the subject, and explores new challenges and opportunities for regional arms control in the current regional environment. It suggests that new models may be necessary to revitalize regional arms control efforts. The establishment of a broad regional security forum could include, but should not be limited to, curtailing weapons of mass destruction through the zone approach. Even if the 2012 conference fails to materialize, or is limited to a one-time event, the proposal for such a conference has provided an important opportunity to rethink future options for a regional arms control and security process.     

A Bioterrorism Prevention Initiative

ABSTRACT

The threat of terrorist use of weapons of mass destruction remains a daunting concern. Governments have undertaken several initiatives at the national and international level to prevent such illicit use, yet challenges remain. Notable is the absence of a single collaborative international forum of experts dedicated solely to bioterrorism prevention. The establishment of a Bioterrorism Prevention Initiative could be a possible solution to address this gap. This article explores possibilities for such an initiative and the ways in which it could strengthen the existing bio-nonproliferation regime.