基于星载照射源的被动SAR系统时频同步误差影响分析

时间和频率同步问题是基于星载照射源的被动SAR系统的关键技术之一。为了研究时、频同步误差对其成像的影响,针对系统工作特性,分析了时、频同步误差的产生机理,建立了时、频同步误差模型,并利用二阶距离模型和RD成像算法,建立了完整的时、频同步误差到成像结果的传递模型,仿真验证了理论分析的准确性。理论推导和仿真计算结果指出了基于星载照射源的被动SAR系统对时间同步和频率同步的精度要求。分析结论对于指导基于星载照射源的被动SAR系统设计及同步方法研究具有重要意义。     

YHFT-DX处理器全定制EDA技术的开发与应用

在YHFT-DX处理器的研制中,研究并实现了多项支撑全定制设计的EDA技术。针对全定制设计的功能验证,研究并实现了层次式功能模型自动提取技术,能够将晶体管级网表转化为等效的RTL级网表。研究并实现了晶体管级混合时序分析方法,可自动分析全定制设计的延时,并采用多线程并行的方法获得了约10倍左右的速度提升。为提高模拟结果分析的效率,开发了一个延时提取的工具Aimeasure。开发了两个信号完整性分析工具PNVisual和NoiseSpy,分别用于全定制设计的IR-Drop分析和噪声分析。上述技术已在YHFT-DX处理器的设计中得到了广泛应用,有效提高了全定制设计的效率与质量。     

Multinational counterinsurgency: the Western intervention in the Boxer Rebellion 1900–1901

This article proposes a case study of the multinational counterinsurgency operations that occurred in China during the Boxer Rebellion in 1900–1, to provide a better understanding of the political and military dynamics specific to this type of mission. The study focuses primarily on the nature of the cooperation on the ground, the various national approaches to counterinsurgency, and the asymmetry of strategic approach between the Westerners and the Chinese. A discussion is also proposed, highlighting that combined counterinsurgency is not per se an obstacle to the unity of command, but that politically international coalitions create unique challenges to counterinsurgency operations.     

光纤陀螺温度场分析及结构优化设计

从导热微分方程出发,建立了光纤陀螺温度场有限元模型,对模型进行了稳态温度场和瞬态温度场仿真分析。利用铂电阻测温电路对仿真结果进行实验验证,两者相对误差小于3%,证明仿真分析的结果是正确和有效的。针对光纤环温度场分布不均匀的情况,对光纤陀螺结构进行了优化设计。光纤陀螺在25℃环境中稳定工作时,稳态温度场分析结果表明,优化设计后光纤环最高与最低温度差为0.05℃,较优化前的0.19℃减小了73.7%;将陀螺置于60℃环境且处于非开机状态时,10min瞬态温度场分析结果表明,优化设计后光纤环最高与最低温度相差0.11℃,较优化前的0.19℃减小了42.1%。     

基于pLSA模型的人体动作识别

提出一种基于主题模型的人体动作识别方法。该方法首先提取时空兴趣点(STIP,space-time interest point)来描述人体运动,然后提出使用慢特征分析(SFA, slow feature analysis)算法计算兴趣点梯度信息不变量最优解,最后使用概率潜在语义分析 (pLSA, probabilistic Latent Semantic Analysis) 模型识别人体动作。SFA计算的梯度不变量最优解可以表示时空兴趣点固有特征,能够无歧义反映时空兴趣点在空间及时间方向上的信息。同时,针对pLSA隐性主题正确性无法保证的缺点,算法将主题与动作标签“一对一”相关,通过监督方式得到主题,保证了训练中主题的正确性。该算法在KTH人体运动数据库和Weizmann人体动作数据库进行了训练与测试,动作识别结果正确率分别在91.50%和97%以上。     

基于OCSVM和MCSVM的新故障检测与诊断技术研究

针对SVM故障诊断方法无法对新故障模式进行有效检测的问题,在阐述OCSVM原理的基础上,详细分析了各种参数对其性能的影响,提出了基于OCSVM和多类分类MCSVM相结合的新故障检测与诊断方法．实验结果表明,该算法在故障诊断及新故障检测方面有较高的精度,具有良好的推广性．     

NON‐LINEARITY IN THE DEFENCE EXPENDITURE – ECONOMIC GROWTH RELATIONSHIP IN TAIWAN

As we enter the 21st Century, technologies originally developed for defense purposes such as computers and satellite communications appear to have become a driving force behind economic growth in the United States. Paradoxically, almost all previous econometric models suggest that the largely defense‐oriented federal industrial R&;D funding that helped create these technologies had no discernible effect on U.S. industrial productivity growth. This paper addresses this paradox by stressing that defense procurement as well as federal R&;D expenditures were targeted to a few narrowly defined manufacturing sub‐sectors that produced high tech weaponry. Analysis employing data from the NBER Manufacturing Productivity Database and the BEA’ s Input Output tables then demonstrates that defense procurement policies did have significant effects on the productivity performance of disaggregated manufacturing industries because of a process of procurement‐driven technological change.     

IN SEARCH OF THE AVERAGE TRANSNATIONAL TERRORIST ATTACK VENUE

In this paper we develop an empirical model for transnational terrorist activity for a panel consisting of 139 countries over the period 1985–1998. Essentially, we attempt to sketch the profile of the average terrorist attack venue. Our findings suggest that the terrorist attack venue is, on average, characterized by low economic openness, high demographic stress, and a high level of international disputes. Furthermore, we document a strong regional component suggesting the presence of infectious contagion on a spatial level. Our results also support the presence of addictive contagion captured by a strong autoregressive component in each country’s terrorist activity. Finally, we find a weak statistical link between the level of democracy and terrorist activity, although the level of democracy is a significant determinant of the potential under‐reporting bias of terrorist activity.     

Measuring defense conversion in Russian industry

This paper develops and implements a methodology for quantifying defense conversion in Russian manufacturing in the early 1990s. A two‐sector, three‐good model is employed to analyze the flows of resources from military to non‐military uses and applied to firm‐level survey data under alternative definitions of military production and the MIC. An aggregation framework is constructed to estimate the total quantity and change in Russian military production, the latter decomposed into intrafirm and intersectoral resource reallocation and overall industrial decline. Although there is evidence of substantial decline in military production, the data show little reallocation to productive civilian uses, neither within the MIC nor to other manufacturing sectors.