水下目标跟踪粒子滤波算法性能分析

粒子滤波(PF)、扩展粒子滤波(EPF)和无迹粒子滤波(UPF)在非线性状态估计方面表现出更好的性能.分析了PF、EPF、UPF 3种算法,UPF的估计状态依赖于测量值,对历史模型信息的敏感度较低,并避免了雅可比矩阵的计算,比EPF更容易进行模型设计;EPF在计算上虽然高效,但跟踪效果不稳定.以AUV水下三维目标跟踪为...     

等离子喷涂Ni基合金涂层热腐蚀行为研究

为探究Ni基合金涂层的热腐蚀防护机理,采用等离子喷涂法在304不锈钢表面制备了NiCr和NiAl两种合金涂层,以75％Na2SO4+25％NaCl的混合盐溶液为腐蚀介质,研究了涂层在700℃下的热腐蚀情况.分别使用扫描电子显微镜、X射线衍射仪对涂层的热腐蚀形貌和晶相变化进行表征,并绘制了涂层的热腐蚀动力学曲线.结果表明...     

Defense spending and economic growth across the Taiwan straits: a threshold regression model

This paper employs both linear and non‐linear models to investigate the relationship between national defense spending and economic growth for Taiwan and China. Using data from 1953–2000 on defense spending, GDP, import, export and capital, we find that China's defense spending leads that of Taiwan. There exists the phenomenon of an arms race between both countries when official Chinese data are used. On the one hand, feedback relations prevail between economic growth and defense spending growth in Taiwan. On the other hand, China's national defense is found to lead economic growth.     

基于多传感器信息系统的仿人机器人步态规划算法改进研究

摘要：基于视觉传感器、角度传感器和力／力矩传感器组成的多传感器信息系统,对仿人机器人理想的步态规划算法进行了改进．以双目视觉立体标定原理处理视觉传感信息,从而判断目标距离及目标路径的可达性;通过角度传感器获取实时旋转角度,经参数调整减小执行误差;根据力／;5矩传感信息对支撑脚踝关节的侧摆角度进行增量式补偿．经实验验证,改进后的算法对机器人的步态稳定性控制具有良好的效果．     

亚洲再平衡——经济意义大于军事意义

美国亚洲再平衡战略的推出,似乎标志着亚太地区已取代欧洲成为美国安全战略重心.但仔细研究发现,该战略与以往任何战略都不同,它并不是完全意义上的军事战略,而更像是裹着军事外衣的经济战略,其经济意义远大于军事意义.     

基于CAS理论的多级维修保障系统建模与分析

针对多级维修保障系统的建模与优化问题,分析了3级维修3级库存维修保障系统模型,运用复杂适应系统(Complex Adaptive System,CAS)理论,建立了多Agent系统的刺激-反应模型,从规则描述、信用分派和规则发现等方面研究了系统建模和分析方法,并进行了模型分析,从而获得一种应用CAS理论研究装备维修保障系统的方法.     

图像融合的客观质量评估

随着图像融合技术在武器自动化系统中的广泛应用,图像融合的质量评估问题,即图像融合的性能评估问题,在融合方案的选择中具有重要地位。由于人工主观的图像融合评估具有很大的工程化和自动化难度,国际上研究人员都将研究目标投向了客观图像融合质量评估的研究中。从历史发展的角度系统地回顾了客观图像融合质量评估的发展历程和研究现状,对近十年来的客观图像融合质量评估方法进行了分类和分析。同时,对于国际上几种流行的图像融合质量评估方法的性能测定思路进行了介绍。对于图像融合质量评估现状的分析和讨论有助于我们对图像融合的质量评估方法进行更深入的研究。     

基于稀疏卷积非负矩阵分解的语音转换方法研究

为了在语音转换过程中充分提取语音的个人特征信息,同时考虑到语音的稀疏性,文章提出了一种基于稀疏卷积非负矩阵分解的语音转换方法。卷积非负矩阵分解得到的时频基可以承载语音信号中的个人特征信息及语音帧之间的相关性,而稀疏卷积非负矩阵分解得到的过完备时频基更能体现语音的细节,可以较好地保存语音中的个人特征信息。利用这一特点,通过稀疏卷积非负矩阵分解从训练数据中提取源说话人和目标说话人相匹配的过完备时频基,然后通过时频基的替换实现语音转换。相对于传统方法,该方法能够更好地保存语音个人特征信息和语音帧间相关性,从而可以进一步提高转换语音的质量和相似度。实验仿真及主、客观评价结果表明,与基于高斯混合模型、卷积非负矩阵分解的语音转换方法相比,该方法具有更好的转换语音质量和转换相似度。     

双向中继网络中基于MSK的物理层网络编码

文中提出一种基于最小频移键控(MSK)调制的双向中继网络物理层网络编码(PNC)方案。该方案利用MSK信号记忆特性,在中继节点处将MSK和信号空间状态转移条件映射为异或信号,采用维特比算法近似最大似然检测。在此基础上进一步简化和信号的网格图,降低解码复杂度。最后仿真验证了所提方案的有效性。     

Using container inspection history to improve interdiction logistics for illicit nuclear materials

Strengthening the United States' ability to prevent adversaries from smuggling nuclear materials into the country is a vital and ongoing issue. The prospect of additional countries, such as Iran, obtaining the know‐how and equipment to produce these special nuclear materials in the near future underscores the need for efficient and effective inspection policies at ports and border crossings. In addition, the reduction of defense and homeland security budgets in recent years has made it increasingly important to accomplish the interdiction mission with fewer funds. Addressing these complications, in this article, we present a novel two‐port interdiction model. We propose using prior inspection data as a low‐cost way of increasing overall interdiction performance. We provide insights into two primary questions: first, how should a decision maker at a domestic port use detection data from the foreign port to improve the overall detection capability? Second, what are potential limitations to the usefulness of prior inspection data—is it possible that using prior data actually harms decision making at the domestic port? We find that a boundary curve policy (BCP) that takes into account both foreign and domestic inspection data can provide a significant improvement in detection probability. This BCP also proves to be surprisingly robust, even if adversaries are able to infiltrate shipments during transit. © 2013 Wiley Periodicals, Inc. Naval Research Logistics 60: 433‐448, 2013