视频编码标准H．264运动矢量搜索算法

高清视频的信息量巨大，传输比较困难。 H．264作为视频压缩的主流标准，可以有效去除视频的冗余信息，提高视频的网络传输能力。针对H．264中运动估计算法耗时严重的问题，提出一种新的X型搜索算法。 X型算法由粗到细地进行搜索，先以X型快速搜索确定运动矢量的可能范围，然后在可能范围内进行局部全搜索，最终确定运动矢量。试验结果表明，X型搜索能够在保证视频质量的情况下大幅度缩短编码时间，有效提高运动估计算法的效率，兼顾了速度与精度，为高清视频的实时传输提供了保障。     

美军“力量提供者”系统与野营装备建设

以美军“力量提供者”系统为研究对象，介绍其功能参数和模块组成以及部署流程，并对其先进性和不足之处进行综合评价。对照现有野营装备建设现状，提出应该加强野营装备研究、增强战略投送能力、建立专业保障力量等思考，以提高未来信息化联合作战中野营装备建设水平。     

基于Hankel范数近似的磁悬浮控制系统模型降阶

对于磁悬浮系统而言,忽略轨道的弹性进行控制算法设计,是一种常见的方法。但是,当轨道的刚度较小时,这种方法的控制性能较差。考虑轨道弹性所设计的控制算法,理论上能确保系统的良好性能但是会使得系统复杂度增加。本文采用Hankel范数近似法对基于弹性轨道的模型进行降阶。针对刚性轨道系统模型和降阶模型设计控制算法,利用仿真结果验证降阶模型的可行性。     

离子束加工误差对散射损失的影响研究

离子束加工(Ion Beam Figuring,IBF)去除函数对加工残差具有重要的影响,而加工残差引起的表面散射则导致光学性能发生变化.为了减小加工残差对光学性能的影响,利用基于CCOS成形原理的离子束加工仿真程序对光学镜面进行修形,分析不同去除函数宽度对散射损失(Ratio of Scattering Loss,RSL)指标的影响.通过研究可知,随着去除函数宽度的减小,加工残差对散射损失的影响越来越小.因此,根据加工残差对RSL指标的影响程度以及RSL指标要求,可以合理选择去除函数宽度,从而在满足面形精度的同时,优化加工工艺.     

Dynamic signatures and their use in comparing the reliability of new and used systems

The signature of a system with independent and identically distributed (i.i.d.) component lifetimes is a vector whose ith element is the probability that the ith component failure is fatal to the system. System signatures have been found to be quite useful tools in the study and comparison of engineered systems. In this article, the theory of system signatures is extended to versions of signatures applicable in dynamic reliability settings. It is shown that, when a working used system is inspected at time t and it is noted that precisely k failures have occurred, the vector s [0,1]^n‐k whose jth element is the probability that the (k + j)th component failure is fatal to the system, for j = 1,2,2026;,n ‐ k, is a distribution‐free measure of the design of the residual system. Next, known representation and preservation theorems for system signatures are generalized to dynamic versions. Two additional applications of dynamic signatures are studied in detail. The well‐known “new better than used” (NBU) property of aging systems is extended to a uniform (UNBU) version, which compares systems when new and when used, conditional on the known number of failures. Sufficient conditions are given for a system to have the UNBU property. The application of dynamic signatures to the engineering practice of “burn‐in” is also treated. Specifically, we consider the comparison of new systems with working used systems burned‐in to a given ordered component failure time. In a reliability economics framework, we illustrate how one might compare a new system to one successfully burned‐in to the kth component failure, and we identify circumstances in which burn‐in is inferior (or is superior) to the fielding of a new system. © 2009 Wiley Periodicals, Inc. Naval Research Logistics, 2009     

表面类裂纹缺陷与地磁场相对空间位置对漏磁场检测的影响

采用低频电磁场的有限元单元分析方法，分析铁磁性金属零件表面类裂纹缺陷与地磁场的空间相对位置变化对缺陷处漏磁场的影响，并通过试验进行了验证。结果表明：相对空间位置对漏磁场强度值影响较大，但对漏磁场强度曲线的变化特征影响不大。当缺陷与地磁场磁力线相互垂直时，漏磁场强度值最大；当缺陷与地磁场磁力线平行时，漏磁场强度值最小。这表明当采用漏磁场检测方法进行无损探伤时，零件的空间方向可能会影响探伤结果。     

The Trump effect downunder: U.S. allies,Australian strategic culture,and the politics of path dependence

Donald Trump’s election precipitated a debate in Australia about the value of retaining close alliance ties with the United States. Similar dynamics are discernible in other U.S. allies as the negative impact of Trump administration policies becomes clearer. Yet despite this “Trump effect,” we argue Australia is unlikely to distance itself from the United States because at the core of Australia’s strategic culture is a very positive “cultural orientation” toward the United States that is highly institutionalized in treaties, formal bilateral ties, Track 2 diplomacy, and public opinion. Such institutionalized ties have powerful path dependent effects. Accordingly, we conclude that the Trump effect does not constitute a powerful enough “exogenous shock” to move Australia off its well-worn grand-strategic path. But this alliance relationship is marked by both high cultural affinity and high institutionalization: American policy-makers should seriously consider whether other U.S. allies can tolerate similar levels of “stress.”     

新型叶片式磁流变阻尼器结构设计

以传统叶片式减振器为基础,设计了具有"失效安全"特性的新型叶片式磁流变减振器。首先基于平板模型和B ingham模型推导了磁流变减振器力矩数学模型,然后分析了初始阻尼力不变情况下的阻尼力可调倍数影响因素,最后应用有限元分析软件ANSOFT对所设计的磁路进行仿真,分析了磁场分布。理论分析及仿真结果表明,叶片式磁流变减振器的阻尼力可调范围能满足重型车辆半主动悬挂系统的需要。     

型号研制与产品数据管理

介绍了产品数据管理(PDM)的概念和基本功能,结合当前型号研制的特点和计算机信息技术应用的状况、发展,研究了型号研制产品数据管理的需求、功能及实施,为当前型号研制依靠CIMS技术实现产品数据管理提出了8条基本原则。     

Does Military Spending Nonlinearly Affect Economic Growth in South Africa?

Using annual data collected from 1988 to 2015, this study provides evidence of a non-linear relationship between military spending, economic growth and other growth determinants for the South African economy. The empirical study is based on estimates of a logistic smooth transition regression (LSTR) model and our empirical results point to an inverted U-shaped relationship between military spending and economic growth for the data. Furthermore, our empirical results suggest that the current levels of military spending, as a component of total government expenditure, are too high in the South African economy and need to be transferred towards more productive non-military expenditure in order to improve the performance of economic growth and other growth determinants.