基于虚拟检测函数下的IMM-UKF机动目标跟踪

为了有效提高对机动目标的跟踪效果,将无迹卡尔曼滤波(UKF)引入到交互多模型(IMM)算法框架内,加强状态估计精度;引入强跟踪滤波器(STF)到UKF算法中,避免对强机动目标的过大时间延迟和跟踪性能差的缺点;提出虚拟检测函数法,在跟踪过程中自适应调整"当前"统计模型的机动参数,加大模型集与目标真实运动模式匹配概率。仿真结果验证了改进算法的有效性。     

考虑输入受限的高超声速飞行器预设性能控制

针对考虑输入幅值与速率受限的高超声速飞行器跟踪性能问题,提出基于受限指令滤波器的预设性能控制方案。为了提高系统瞬态和稳态性能,设计预设性能反演控制器,并通过设计新的性能函数使得跟踪误差超调量更小。引入指令滤波器来处理反演控制器设计中难以求导的问题。针对输入受限问题,构造一种受限指令滤波器来约束系统控制律,保证控制输入满足幅值和速率的限制要求,并进行相应的理论证明。另外,考虑系统参数不确定性与外界干扰,采用线性扩张状态观测器进行观测并补偿。基于Lyapunov稳定理论证明系统的所有跟踪误差最终一致有界。通过仿真验证该方法的有效性。     

水中兵器延寿样本的装载可靠度鉴定试验方案

针对延寿样本子样少,按经典GJB899法对装载可靠度鉴定需要较长的试验时间这一实际情况,提出了一种减少试验时间的Bayes方法.该方法通过挖掘延寿前装载失效率信息,确定先验分布,再开展陆上加速装载试验以增加装载信息,并结合实际装载信息制定了装载可靠度鉴定试验新方案.实例计算表明:在确保鉴定效果的前提下,新方法可在较小的延寿样本条件下快速完成装载可靠度鉴定工作,满足水中兵器延寿工程的实际需要.     

新型光电装备延伸保修决策方法研究

延伸保修是开展军民融合式装备保障的重要技术手段之一,通过合理选择延伸保修策略,可以在有限的经济条件下较好地完成维修保障任务,提高装备维修保障效益.针对新型光电装备特点,在考虑安全性、任务性和经济性因素的背景下,提出一种由逻辑决断分析法和模糊层次分析法相结合的延伸保修决策方法.通过逻辑决断分析从定性角度选择合理的延伸保修策略,采用模糊层次分析法对逻辑决断得到的结果进行定量补充分析,为类似装备的延伸保修决策提供决策参考.     

机动目标状态估计的最小均方误差界

基于多项式模型的各种自适应滤波算法被广泛应用于机动目标跟踪领域,但尚没有统一的评估标准来衡量这些跟踪算法的优劣。由于存在确定的时变未知输入,机动目标的状态估计实际为有偏估计。基于状态估计均方误差最小的准则,推导了多项式模型滤波的最小均方误差界计算方法,获得了使状态估计均方误差最小的过程噪声方差变化规律。该方法给出了各种基于多项式模型的机动目标跟踪算法的估计均方误差下限,也为机动目标跟踪中最优过程噪声方差的设定提供了依据。仿真结果验证了算法的有效性。     

NUCLEAR REDUCTIONS AND MIDDLE EAST STABILITY

The United States faces a series of strategic and policy conundrums as it attempts to promote strategic stability in the Persian Gulf and the wider Middle East. This article examines the relationship between a reduced US nuclear arsenal and strategic stability in the Persian Gulf and the Middle East. It argues that a series of interrelated political and military factors play a much more significant role in regional security and stability than the US strategic arsenal, which has never, with a few extraordinary exceptions, played a direct role in maintaining regional security. The United States has constructed a system of regional stability based on conventional deterrence and defense that has seen it forward base forces at various installations in the region in combination with efforts to arm, train, and equip host-nation militaries. Nuclear weapons have never played a prominent role in this regional system. Evidence presented in this article suggests that there is no compelling reason for the United States to abandon and/or modify the defensive system of conventional deterrence and defense by adding nuclear-backed guarantees to the mix.     

变质心再入飞行器自抗扰控制器设计(英文)

再入飞行器采用变质心控制不但可以保持较好的气动外形,还町以增大机动能力,但变质心控制较强的非线性和耦合性大大增加了控制系统设计难度,使控制器设计和实施的代价较高。针对这一问题,基于自抗扰控制技术,设计了变质心再入飞行器双通道解耦控制器。通过构造连续光滑扩张状态观测器,不加区分飞行器的各类干扰与耦合,对其统一进行估计:利用非线性状态反馈控制律,并自适应调节控制参数对其进行补偿,实现对飞行器姿态的解耦控制。仿真结果表明:该方法大大降低了对系统模型精度的要求与控制器设计实施代价,对变质心再入飞行器非线性、耦合性以及参数摄动具有较强的鲁棒性。     

基于通信延迟误差补偿的协同导航算法

多自主水下航行器(MAUV)协同导航技术是解决水下定位的重要手段。主从式多AUV协同导航系统利用水声通信方式实现数据共享,但由于声速在水中传播较慢,使得接收到的量测信息具有通信延迟。因此,针对通信延迟问题提出了一种新息重建的状态估计补偿方法,通过对从AUV进行状态递推,获得在有无量测延迟两种情况下的状态误差,将此误差作为重建的新息补偿到状态估计中。仿真结果验证了该方法能够有效地补偿协同导航中由于通信延迟造成的定位误差,提高从AUV的定位精度。     

被动式寻的导弹的目标自适应制导算法

主要解决以下两个问题 :一是在仅有角度信息的被动制导中如何获得距离信息 ;二是对攻击点的选择问题作了初步的探索 ,在获得距离信息的基础上 ,利用交战双方几何关系实现目标自适应制导算法 ,解决在红外被动制导中跟踪点和攻击点不同的问题。文末给出实验仿真结果及分析     

Security assurances and proliferation risks in the Trump administration

Comments that Donald Trump made while campaigning to be U.S. president have raised concerns that his administration will pull back from U.S. alliance commitments and encourage countries such as Japan and South Korea to acquire nuclear arms. The new article by Frühling and O’Neil outlines an institutional framework that can be helpful in assessing the risks that Trump administration policies will lead to nuclear proliferation. An institutional perspective shows that important elements of U.S. security assurances will continue to function, and this reduces the chances that President Trump’s actions or statements will trigger proliferation by U.S. allies. The greatest risk to global non-proliferation efforts posed by a Trump administration in fact lies elsewhere, in the possibility that President Trump will seek to abrogate the Iran nuclear deal.