随机共振技术在微弱舰船轴频电场信号检测中的应用

针对在强背景噪声中检测微弱舰船轴频电场信号的问题,提出了基于随机共振技术的检测方法.首先,介绍了随机共振利用噪声增强信号能量从而提高信噪比的基本原理,并在此基础上给出了利用随机共振检测微弱周期信号的模型.然后,将低信噪比的船模轴频电场测量数据输入到检测模型并对输出信号作功率谱分析,结果表明:随机共振技术能十分有效地从复杂背景噪声中检测出微弱舰船轴频电场信号,在微弱信号处理领域相比传统方法具有很大的优势.最后,结合检测实例,初步分析了系统参数对随机共振系统输出信号频谱分布的影响,为随机共振技术的进一步工程应用打下了良好的基础.     

A generalized assignment model for dynamic supply chain capacity planning

We consider a generalization of the well‐known generalized assignment problem (GAP) over discrete time periods encompassed within a finite planning horizon. The resulting model, MultiGAP, addresses the assignment of tasks to agents within each time period, with the attendant single‐period assignment costs and agent‐capacity constraint requirements, in conjunction with transition costs arising between any two consecutive periods in which a task is reassigned to a different agent. As is the case for its single‐period antecedent, MultiGAP offers a robust tool for modeling a wide range of capacity planning problems occurring within supply chain management. We provide two formulations for MultiGAP and establish that the second (alternative) formulation provides a tighter bound. We define a Lagrangian relaxation‐based heuristic as well as a branch‐and‐bound algorithm for MultiGAP. Computational experience with the heuristic and branch‐and‐bound algorithm on over 2500 test problems is reported. The Lagrangian heuristic consistently generates high‐quality and in many cases near‐optimal solutions. The branch‐and‐bound algorithm is also seen to constitute an effective means for solving to optimality MultiGAP problems of reasonable size. © 2012 Wiley Periodicals, Inc. Naval Research Logistics, 2012     

防空导弹主动雷达导引头地/海杂波功率谱计算

中/远程防空导弹通常采用复合制导体制,并采用高抛弹道技术来增大射程。这样,在中末制导交班阶段或末制导阶段,主动雷达导引头需要在地/海杂波背景下截获和跟踪目标。介绍了一种计算主动导引头地/海杂波功率谱的方法,根据杂波功率谱的估算结果,可以确定导引头的杂波下可见度(SCV)指标或设立导引头跟踪的频率禁区。     

基于Logistic映射的混沌序列扩频序列生成算法

直序扩频通信系统中,扩频序列的各项性能指标直接影响到通信系统的扩频增益、抗干扰性能以及多用户复用性能等。混沌序列具有良好的相关性、可重生性等特性,可作为理想的直序扩频码应用于低压电力线通信中。对混沌扩频技术在电力线通信中的应用进行了探讨,提出了一种利用Logistic映射得到大量适用于直序扩频系统的混沌扩频序列的算法,并在Matlab环境下编程实现了该算法。在此基础上分析了所得混沌序列的性能并与M序列、Gold序列加以比较,证明了算法的可行性。     

爆扩桩抗拔承载力计算公式研究

目前关于扩底桩尤其是爆扩桩抗拔力计算公式很少。在有限的扩底桩计算公式中,普遍存在着对爆扩桩的承载机理不清楚,对扩大头作用的体现机理表达不准确等问题。首先介绍一些典型的抗拔计算公式,选出有代表性的且适用于爆扩桩的抗拔计算公式, 然后根据工程试桩的计算结果,结合理论分析对公式的合理性进行探讨,最后根据爆扩桩的抗拔机理和试验分析给出易于运用的软土中大直径爆扩桩的抗拔承载力计算公式,并给出相应的构造要求。     

论提高灭火救援组织指挥能力

建设科学合理、准确高效的灭火救援作战组织指挥体系,能提高消防部队的组织指挥的能力,以最快、最有效的方法处置各类事故,真正做到＂拉得出、冲得上、打得赢＂。阐述了建立灭火救援作战组织指挥体系的基本要求,提出了提高灭火救援指挥员指挥水平的对策。     

形态滤波和自相关降噪的Hilbert边际谱在轴承故障诊断中的应用

Hilbert边际谱是Hilbert-Huang变换在频域的一种表示形式,适合分析机械故障诊断中广泛存在的非平稳信号,但是噪声会影响Hilbert边际谱的分析精度。针对从装甲车辆机械系统采集的振动信号中噪声的特点,将形态滤波和自相关相结合,对振动信号进行降噪,提高了Hilbert边际谱对振动信号的分析精度,并在某型坦克变速箱主轴7216轴承滚动体点蚀故障诊断中得到了应用。     

复杂电磁环境下的电磁频谱管理效能评估研究

针对复杂电磁环境下的电磁频谱管理效能评估问题,提出一套系统地效能评估方法.首先对效能评估的指标体系进行了分析,然后提出了一种多模型混合的效能评估方法,最后对整个过程中效能评估的流程进行研究.通过实例仿真研究表明,该方法可以有效地对复杂电磁频谱下的电磁频谱管理效能进行评估.     

多普勒频谱及JEM效应在空中目标识别中的应用分析

为了获取进行空中目标识别的有效特征量,分析了多普勒频谱结构识别、调制谱识别和JEM周期特征识别等方法.采用将相位和幅度综合的方法,获得了更接近理论值的JEM周期平均值特征量,仿真结果说明综合特征量具有较小的估计标准差.最后,指出了该领域可能的研究方向.     

Defending Australia in the digital age: toward full spectrum defence

Australian defence strategy is disjointed and incomplete. Some would say that it is non-existent. Either way, this paper argues that Australia’s underwhelming approach to defence is the product of a crippling geographically focused strategic dichotomy, with the armed forces historically having been structured to venture afar as a small part of a large coalition force or, alternatively, to combat small regional threats across land, sea, and air. However, it is argued that Australia can no longer afford to drift between these two settings and must take measures to define a holistic “full spectrum defence” strategy and develop capability to fight effectively and independently across all domains of the twenty-first century-battlespace: land, sea, air, space, and the cyber realm.