Terrorism,crime and public spending: Panel VAR evidence from europe

Within a panel VAR framework and utilizing generalized impulse response and forecast error variance decomposition analysis, we explore the dynamic effects of terrorism and crime on public order and safety spending across European countries during the period 1994–2006. Our findings show that a ‘shock’ in terrorism and/or in crime, significantly increases the subsequent trajectory of public order and safety spending. As a by-product, we find that public spending is ineffective in reducing observed crime or terrorism.     

从简单句的切分看俄语词序

俄语词序有很大的自由度,但要受词汇、语法、交际目的和修辞色彩的限制,不能任意安排。本文拟从简单句的结构切分和实义切分着手分析,来了解俄语词序的一般规律及其功能。     

The NBUL class of life distribution and replacement policy comparisons

Let X and X_τ denote the lifetime and the residual life at age τ of a system, respectively. X is said to be a NBUL random variable if X_τ is smaller than X in Laplace order, i.e., X_τ ≤_L X. We obtain some characterizations for this class of life distribution by means of the lifetime of a series system and the residual life at random time. We also discuss preservation properties for this class of life distribution under shock models. Finally, under the assumption that the lifetimes have the NBUL property, we make stochastic comparisons between some basic replacement policies. © 2001 John Wiley & Sons, Inc. Naval Research Logistics 48: 578–591, 2001.     

非线性干扰观测器的高超声速飞行器自适应反演控制

针对高超声速飞行器参数不确定弹性体模型,提出了一种基于非线性干扰观测器的自适应反演控制器设计方法。将曲线拟合模型表示为严格反馈形式,采用反演方法设计控制器。采用动态面方法获取虚拟控制量的导数,避免了传统反演控制"微分项膨胀"问题。为了增强控制器的鲁棒性,基于二阶跟踪-微分器设计了一种新型非线性干扰观测器,以此对模型不确定项进行自适应估计和补偿。仿真结果表明,控制器对模型不确定性和气动弹性影响具有强鲁棒性,且能实现对速度和高度参考指令的稳定跟踪。     

数字化部队指挥网络系统效能评价模型

以结构熵理论为基础,分析数字化部队作战指挥信息网络系统组织结构对系统内信息流的影响,从信息的角度对系统组织结构的有序度进行评价,引入信息流的时效和质量的概念,建立定量评价系统结构有序度计算的时效质量模型,结合系统数据传输业务效能的评价方法,形成作战指挥信息网络系统整体综合效能的评价模型。最后辅以实例。     

基于差分法的二阶微分方程的模糊边值问题

本文讨论二阶微分方程的两点边值具有模糊不确定性时 ,运用模糊仿真原理和差分方法 ,求其边值问题的数值解法。     

用时序展开法求解瞬时无耗传输线方程

本文用时序展开法直接在时域中求解了任意终端和输入端时无耗时变传输线方程。给出了这个问题的一般解。此方法简单,结果的物理意义明确,对分析准行波系统的时域问题具有一定的参考价值。     

高阶累积量自适应波束形成的改进算法

针对线性约束最小方差(LCMV)算法在自适应波束形成时,存在的对噪声敏感、信噪比(SNR)较高时波束形成受小特征值扰动影响较大的情况。在基于高阶累积量的LCMV算法的基础上提出改进方法。该方法首先计算阵列接收数据的高阶累积量,然后对高阶累积量构造数据增广矩阵,进行奇异值分解求出伪逆,再用伪逆修正LCMV算法的权值,形成波束。仿真结果表明,相比于传统LCMV算法与基于高阶累积量的LCMV算法。算法能够有效地克服信噪比升高时小特征值扰动对波束形成的不良影响,且在较低快拍数下仍能有效形成波束。     

Approximation methods for the analysis of a multicomponent,multiproduct assemble‐to‐order system

In this article, we consider the performance evaluation of a multicomponent, multiproduct assemble‐to‐order (ATO) system. Each component is managed independently using a base‐stock policy at a supply facility with limited production capacity and an infinite buffer. The arrivals of demands follow a multivariate Poisson process and unfilled demands are backlogged. Because exact analysis of the proposed system is not feasible, we propose two approximation methods which provide upper and lower bounds for various performance measures such as fill rate, average waiting time, and average number of backorders of the proposed system. Our computational experiments demonstrate the effectiveness of the two approximation methods under various system settings. © 2011 Wiley Periodicals, Inc. Naval Research Logistics, 2011     

锆酸铅PbZrO3序参量的量子饱和

在503 K反铁电体PbZrO3发生立方-正交相变,序参量是反平行离子位移引起的超晶格;在低温相时,PbZrO3的反铁电超晶格反射强度随温度的变化成正比,可以由考虑量子效应的Landau唯象理论加以描述;高于室温时,Γ25超晶格反射强度显示了不同的温度依赖性。