基于LVDS的高速远程实时测控系统的设计

分析了LVDS在远程测控系统应用中的关键技术,介绍了基于LVDS的高速远程传输方式的设计方案。针对设计中的关键性问题,如电磁干扰、阻抗匹配、直流平衡以及信号驱动等问题提出了具体的解决方案,并给出了电路设计中阻抗匹配设计的线宽计算公式。最后结合实验分析了具体设计对于信号质量的影响。     

基于直\气复合的再入飞行器操纵耦合分析及鲁椿控制设计

为保证再入飞行器在剧烈变化飞行环境下的控制能力,传统单一气动舵面控制被直＼气复合控制模式取代.性能提升同时,多个参与飞行控制的执行机构之间引起的操纵耦合使系统耦合加剧.以再入飞行器为研究重点,分析了直＼气复合控制模式下的两类操纵耦合原理,建立数学模型.采用动态逆,模糊理论和变结构方法相结合策略设计鲁棒控制器.仿真结果表明该方法是行之有效的.     

面向普适计算应用的构件定义语言UCDL

普适计算的适应性特征对于软件重用的要求决定了构件模型是目前普适计算软件体系结构的理想选择.在面向普适计算的自适应软件平台UbiStar的研究过程中,为了准确地对普适应用中构件的外部特征进行抽象描述,参考了CORBA构件模型使用IDL3和CIDL对构件进行特征抽象的方法,结合UbiStar普适计算平台的特点与需求,提出了一种适用于普适计算环境的构件定义语言UCDL,并且给出了一个应用示例.     

助推滑翔飞行器复合控制系统线性化小偏差运动方程推导与控制系统设计

助推滑翔技术是制导武器实现增加射程、提高机动突防能力的关键技术之一,对飞行器姿态控制有较高的要求,需要设计复合控制方式的姿态控制系统.针对采用空气舵与燃气舵联动控制的飞行器,建立了动力学模型,详细推导了完整的三通道线性化小偏差运动方程,结合典型弹道数据给出了动力系数图像,分析了助推滑翔弹道各飞行段中飞行器的稳定性,在此基础上选取再入段低空飞行特征点进行了姿控系统设计,仿真结果验证了线性化小偏差运动方程的正确性和控制系统的有效性,为进行此类飞行器的稳定性分析与姿态控制系统设计提供了有益的参考.     

基于混合优化的前馈—反馈复合控制器最优设计

为了解决传统PID控制器在电动舵机系统设计中难以满足控制要求的问题,首先设计了一种规范化前馈-反馈控制系统,然后利用混沌优化算法和共轭梯度方法相结合的混合优化算法对前馈-反馈控制器参数进行了优化.仿真结果表明:基于混合优化算法的前馈-反馈控制器具有很好的动态和静态性能,增强了系统的稳定性和鲁棒性,降低了学习参数选择的盲目性和对经验的高度依赖性.     

信息中心网络缓存节点位置选择算法

信息中心网络（Information-Centric Networking, ICN）“泛在缓存”的特性,引发数据副本率过高、缓存空间不能充分利用等问题。为了解决上述问题,分别从用户、服务提供商和网络运营商的角度出发,以最小化网络流量与网络费用开销为优化目标建立两个单目标优化模型,并将二者结合为帕累托模型;基于帕累托求解方法中数学规划法的思想,详细描述缓存节点位置选择算法。仿真结果表明：在流量性价比方面,所提缓存节点选择算法优于ICN的默认缓存机制;在网络费用开销方面,所提算法更适用于只有少数内容较为流行的网络中,而在所有内容都流行的情况下,ICN中默认的“遍地缓存”机制更为适宜。     

The Gravity of Arms

The aim of this paper is to investigate the determinants of international arms transfers in a gravity model framework. By distinguishing between the decision to export arms (extensive margin) and the value of the arms exported (intensive margin), while also considering its interdependence, is what differentiates this paper from previous research. A theoretically justified gravity model of trade augmented with political and security motives is estimated using a two-stage panel data approach for 104 exporting countries over the period from 1950 to 2007. In addition to the usual gravity variables related to the economic mass of the trading countries and the trade cost factors, the model is extended with political and security factors. The level of democracy in both trading partners, political differences between trading partners and voting similarity with the United States in the UN General Assembly of the countries engaged in trade are the main political factors, whereas the existence of conflicts, military pacts, and embargoes are taken as security motives. The key result indicates that both political and security motives are an important determinant of an arms trade, but their effects on the extensive margin of exports (the decision to order a transfer) differs from their effect on the intensive margin (average value of exports). Moreover, the relative importance of the factors under study has changed since 1989. In the post-cold war period, countries that are less democratic are more likely to export arms, military pacts are less relevant and embargoes play a role.     

Optimum step‐stress accelerated life test plans for log‐location‐scale distributions

This article presents new tools and methods for finding optimum step‐stress accelerated life test plans. First, we present an approach to calculate the large‐sample approximate variance of the maximum likelihood estimator of a quantile of the failure time distribution at use conditions from a step‐stress accelerated life test. The approach allows for multistep stress changes and censoring for general log‐location‐scale distributions based on a cumulative exposure model. As an application of this approach, the optimum variance is studied as a function of shape parameter for both Weibull and lognormal distributions. Graphical comparisons among test plans using step‐up, step‐down, and constant‐stress patterns are also presented. The results show that depending on the values of the model parameters and quantile of interest, each of the three test plans can be preferable in terms of optimum variance. © 2008 Wiley Periodicals, Inc. Naval Research Logistics, 2008     

一种高效的显式模型检验方法

随着软硬件系统规模和功能的不断扩充,状态空间爆炸问题严重影响了模型检验的进一步发展与应用,成为验证大规模系统的瓶颈.在显式模型检验工具Murphi的基础上,针对其可达状态空间组织存在的问题进行改进,提出了基于整型指针与Fibonacci散列的可达状态空间组织方法,实现了一个高效的显式模型检验原型系统,在确保验证正确的同时有效缩短了验证时间,并能在系统规范不可满足的情况下给出反例,有助于系统设计人员快速定位错误.理论分析和实验结果表明了本方法的有效性.