混沌理论在雷达中的应用

混沌动力学作为一门新学科已经引起了世界各国科学界的重视,是近年来非线性科学领域的热门学科,混沌系统初值的敏感性和两个混沌系统间同步的实现,使得混沌用于保密通信成为可能,海杂波的混沌特性使人们开始探索混沌在雷达中的应用.研究表明,混沌在杂波分析与建模、信号检测、目标识别及伪随机码波形设计等领域内取得了可喜的成果.研究了混沌在雷达中的应用,分析了目前混沌在雷达中的应用现状,预测了未来研究发展的趋势.     

坦克装甲车辆火控技术的现状及发展

对坦克火控系统的技术现状和发展前景进行了较为详尽的论述,并指出了当前国内火控发展中面临的主要技术难题及解决办法.     

核动力装置一回路辅助系统失水事故的仿真研究

运用一种操作简便、计算速度快的工具软件对某核动力装置一回路辅助系统典型位置的失水事故进行了仿真.通过分析仿真结果得出不同位置的破口引起不同后果的事故,其中有些事故可以忽略,有些事故则相当严重.     

一种运用遗传算法确定船舶航向控制模糊规则的方法

为了克服船舶航向控制模糊规则确定过程中的盲目性,引入一种与之相适应的遗传算法,以使结果成为某种意义下的最优解,从而从根本上解决这一重要问题.文中运用Matlab的C语言MEX-文件技术,将遗传算法源代码与Matlab直接结合起来,利用后者的强大建模能力,建立起完整的仿真模型.仿真结果表明,船舶的航向控制能力得到明显改善.     

武器系统研制单位管理水平的贝叶斯评估分析

将Bayes理论应用于对武器系统研制单位管理水平的评估.克服了验前评估方法主观性大的缺陷,充分利用收集到的补充信息,对评估结果作了后验预分析,得到了更加可信的评估结论,从而改进了决策过程.     

适用于北斗混合星座的相对定位随机模型建模策略

为提高模糊度解算成功率和基线解精度,提出适用于北斗的相对定位随机模型建模策略,即混合随机建模策略。采用最小二乘方差分量估计方法对北斗单差观测量方差进行估计。对处于不同高度的三轨道卫星观测量方差分别建模:对地球静止轨道卫星观测量方差采用载噪比模型建模,对倾斜地球同步轨道卫星和中地球轨道卫星观测量方差均采用仰角模型建模。根据不同模型实时组建观测量的随机模型。试验结果表明:相比于采用传统简化模型和单一的仰角或载噪比模型,混合随机模型能更加真实地反映不同卫星观测量的随机噪声特性,模糊度解算成功率和相对定位精度均有提高,总体性能最优,因而能更好地适用于北斗系统。     

Merely ‘Docile Self-Deception’? German Experiences with Nuclear Consultation in NATO

ABSTRACT

Recent nuclear-weapons-related consultation in NATO within the framework of the Defence and Deterrence Posture Review sheds light on historical experiences with nuclear consultation in NATO. In the early years of the Nuclear Planning Group (NPG), which became the main forum for multilateral nuclear consultation in the alliance, developing a nuclear weapons first use doctrine was of particular importance. This process led to the adoption of the Provisional Political Guidelines (PPGs) on the threat to initiate the use of nuclear weapons. With a focus on West Germany as the primary addressee of the NPG, it will be postulated that nuclear consultation functioned and may still be seen as an essential tool to manage the credibility of US extended nuclear deterrence in the framework of NATO.     

Value management of diagnostic equipment with cancelation,no‐show,and emergency patients

Magnetic resonance imaging and other multifunctional diagnostic facilities, which are considered as scarce resources of hospitals, typically provide services to patients with different medical needs. This article examines the admission policies during the appointment management of such facilities. We consider two categories of patients: regular patients who are scheduled in advance through an appointment system and emergency patients with randomly generated demands during the workday that must be served as soon as possible. According to the actual medical needs of patients, regular patients are segmented into multiple classes with different cancelation rates, no‐show probabilities, unit value contributions, and average service times. Management makes admission decisions on whether or not to accept a service request from a regular patient during the booking horizon to improve the overall value that could be generated during the workday. The decisions should be made by considering the cancelation and no‐show behavior of booked patients as well as the emergency patients that would have to be served because any overtime service would lead to higher costs. We studied the optimal admission decision using a continuous‐time discrete‐state dynamic programming model. Identifying an optimal policy for this discrete model is analytically intractable and numerically inefficient because the state is multidimensional and infinite. We propose to study a deterministic counterpart of the problem (i.e., the fluid control problem) and to develop a time‐based fluid policy that is shown to be asymptotically optimal for large‐scale problems. Furthermore, we propose to adopt a mixed fluid policy that is developed based on the information obtained from the fluid control problem. Numerical experiments demonstrate that this improved policy works effectively for small‐scale problems. © 2016 Wiley Periodicals, Inc. Naval Research Logistics 63: 287–304, 2016     

The fateful phoenix: the revival of Al-Qa’ida in Iraq

Although the Islamic State in Iraq and al-Sham (ISIS) is seen as a novel manifestation of Islamic extremism, it is in fact the latest, albeit perhaps the most effective, of a long line of revivalist movements in the Islamic and the Arab worlds. Its motivations – hisba and jihad – differ little from its predecessors and its ambitions – to create a state organised in accordance with the precepts of the Islamic caliphate – reflect a long-standing Islamic ambition. It differs, of course, in terms of the sophistication of its political and military strategies, which mirror the contemporary complexities of the world in which it operates, but its objectives recall long-standing Islamic ideals, even if articulated in radically brutal and extremist ways. More importantly, perhaps, ISIS or Da’ish, to give it its Arabic sobriquet, reflects the enormous degree of resentment inside the Middle East at the ways in which Western powers have intervened in regional affairs over recent years, particularly their support for regimes and economic systems there that have betrayed, in the popular imaginary, the essential principles of social justice that lie at the root of Islamic vision of ideal social order. Indeed, in many respects, its analysis of the world in which it operates and of the objectives it seeks differ little in essence from those any other resistance and rejectionist movement, whether religious or sectarian. More specifically, it has been the sectarian conflict that resulted from the reversal of political order in Iraq as a result of the 2003 American-led invasion that has driven the success of the movement in capturing widespread Sunni support. Whether it can manage the complexities of the administration of a state remains open to question.     

高精度有限体积格式在三维曲线坐标系下的应用

为了构造在光滑区具有较高分辨率并且可以无振荡捕捉激波的高精度有限体积格式,同时降低格式在模板选择上遇到的困难,基于逐维重构方法,发展了结构网格下的高精度有限体积格式,并将这一格式推广到三维曲线坐标系下,从而可以适应相对复杂外形下的计算。为充分验证格式的有效性,选取一系列典型算例进行计算:在等熵涡输运和二维喷管流动中验证了格式的精度可以达到设计精度;在双马赫反射问题中格式也表现出良好的捕捉激波的能力。数值计算表明,上述格式在曲线网格上具有较高的数值精度和鲁棒的激波捕捉能力,适用于流体力学方程的计算。