北斗导航信号电离层闪烁模拟及其影响

电离层闪烁具有突发性、偶发性和区域性,且难以建模准确刻画。针对电离层闪烁影响下的北斗导航信号复现问题,研究了基于应用伽马分布和零均值高斯分布模型的导航信号电离层闪烁序列生成方法,并基于国防科技大学电子科学与工程学院研制的NSS8000型多体制导航信号模拟器给出了北斗导航信号电离层闪烁模拟的硬件架构。在此基础上,通过中频信号采样和软件接收机处理,分析了电离层闪烁对北斗接收机跟踪环路的影响。结果表明:在相位闪烁指数为0,幅度闪烁指数为0.9时,码环鉴相误差可达0.05 chip;而在幅度闪烁指数为0,相位闪烁指数为0.5时,载波环鉴相误差可达15°,处于失锁的临界状态。     

一种变质心高速旋转炮弹鲁棒姿态控制律

针对采用变质心技术的高速旋转炮弹的姿态控制问题,提出一种基于扩张状态观测器的动态面控制方法。根据由弹体和单滑块组成的多体系统的特点,建立了系统的姿态动力学模型,并对其进行了合理的简化。将系统的滚转通道引起的强耦合、建模误差及外部扰动等视为未知不确定干扰,并且考虑由于炮弹尺寸限制而引起的多体系统控制输入(滑块位移)的有限性,设计了扩张状态观测器和辅助系统,分别对系统的干扰进行观测以及处理控制输入的有限性,综合动态面控制技术设计了姿态控制律,最后基于李雅普诺夫稳定性原理证明了控制器的稳定性。仿真结果表明,该控制器能够在克服干扰的前提下快速稳定地跟踪指令信号,具有良好的控制精度和鲁棒性。     

基于MIMO技术的山体滑坡雷达

现有山体滑坡雷达是轨道式的,这样就需要精确控制雷达的运动来获得高方位向分辨率,因此,硬件设备要求极高。利用多输入多输出(MIMO)技术通过分时发射和接收信号来获取高方位向分辨率,可以免去雷达运动,从而简化了雷达设备和降低雷达成本。此外,结合步进频连续波技术可以使山体滑坡雷达保持高距离向分辨率的同时进一步降低对硬件的要求,更易于工程实现,成本更低。通过MATLAB仿真初步验证了该方案的可行性。     

对地攻击型无人机作战效能评估

由于对地攻击型无人机与有人机在性能参数和作战方式等方面存在诸多不同,为了评估其作战效能,首先建立了对地攻击型无人机作战效能评估的指标体系,然后在此基础上建立了对地攻击型无人机的综合指标模型,同时对效能模型中各分项能力的评估模型进行了完善。最后以6种无人机综合作战效能评估为例计算并检验了模型的可用性。     

军用车载电源异常电压监测模块的研制

对由蓄电池供电的某军用特种车辆供电系统的异常电源信号进行监测模块的设计,为系统控制终端进行分析及故障排除提供参考数据。监测模块采用C8051F040单片机为控制核心,通过对"系统DC26V"和"系统DC5V"电源进行监测,记录超出正常范围的异常电压值,并可以通过RS-485通信方式将异常数据上传到控制终端。该模块具有体积小,采集速度快,记录时间标记和运行稳定的特点。通过实际应用证明可以准确地记录各种在运行过程中电源异常的情况。     

装备保障能力评估指标选择方法研究

针对当前装备保障能力评估指标选择方法存在主观性较大、评估精度低、评估结果一致性差等问题,提出了3种装备保障能力评估指标确定方法。依据面向能力的思路,通过对能力、性能与特性关系的分析提出了指标确定方法;基于本体论与文本挖掘技术,对装备保障能力相关文本的特征进行表示和提取,最后定义合适的文本挖掘泛化规则提炼出评估指标和权重;利用FP-Growth关联规则和模糊贝叶斯网络建立混合模型获取评估指标及权重,最后通过案例验证各方法的客观性、有效性和一致性。     

雷达对抗侦察装备作战能力的ANP幂指数评估方法

针对雷达对抗侦察装备综合作战能力对电磁环境的依赖性,提出一种基于网络层次分析法(Analytic Network Process,ANP)的雷达对抗侦察装备在不同电磁环境下作战能力的幂指数评估方法。通过对雷达对抗侦察装备作战任务及复杂电磁环境下的表现进行分析,确定装备作战能力指标;利用ANP分析各指标间的相互关系,计算出指标相对的权重;把该权重作为各指标的幂指数,计算雷达对抗侦察装备在不同电磁环境下的作战能力指数;最后结合某型装备多次不同环境下试验的数据,对该装备的综合作战能力进行评估。     

备件冷储备方案下装备群任务可靠性建模

针对具有相同结构功能的装备群系统可靠性评估问题,根据任务周期内对装备完好数的要求,合理表示了系统状态转移过程。以部件任务期间状态变化为研究对象,将系统等效表示为多阶段任务系统,即串行k/N(G)系统。在确定系统可行状态过程基础上,分别建立了部件寿命分布在3种不同情形下的系统任务可靠性模型,并分析了备件冷储备方案的影响。为确定系统任务期间备件携带量提供决策支持,最后给出了一个应用实例。     

Generalizing the survival signature to unrepairable homogeneous multi‐state systems

The notion of signature has been widely applied for the reliability evaluation of technical systems that consist of binary components. Multi‐state system modeling is also widely used for representing real life engineering systems whose components can have different performance levels. In this article, the concept of survival signature is generalized to a certain class of unrepairable homogeneous multi‐state systems with multi‐state components. With such a generalization, a representation for the survival function of the time spent by a system in a specific state or above is obtained. The findings of the article are illustrated for multi‐state consecutive‐k‐out‐of‐n system which perform its task at three different performance levels. The generalization of the concept of survival signature to a multi‐state system with multiple types of components is also presented. © 2016 Wiley Periodicals, Inc. Naval Research Logistics 63: 593–599, 2017     

The probability of the existence of a feasible flow in a stochastic transportation network

Stochastic transportation networks arise in various real world applications, for which the probability of the existence of a feasible flow is regarded as an important performance measure. Although the necessary and sufficient condition for the existence of a feasible flow represented by an exponential number of inequalities is a well‐known result in the literature, the computation of the probability of all such inequalities being satisfied jointly is a daunting challenge. The state‐of‐the‐art approach of Prékopa and Boros, Operat Res 39 (1991) 119–129 approximates this probability by giving its lower and upper bounds using a two‐part procedure. The first part eliminates all redundant inequalities and the second gives the lower and upper bounds of the probability by solving two well‐defined linear programs with the inputs obtained from the first part. Unfortunately, the first part may still leave many non‐redundant inequalities. In this case, it would be very time consuming to compute the inputs for the second part even for small‐sized networks. In this paper, we first present a model that can be used to eliminate all redundant inequalities and give the corresponding computational results for the same numerical examples used in Prékopa and Boros, Operat Res 39 (1991) 119–129. We also show how to improve the lower and upper bounds of the probability using the multitree and hypermultitree, respectively. Furthermore, we propose an exact solution approach based on the state space decomposition to compute the probability. We derive a feasible state from a state space and then decompose the space into several disjoint subspaces iteratively. The probability is equal to the sum of the probabilities in these subspaces. We use the 8‐node and 15‐node network examples in Prékopa and Boros, Operat Res 39 (1991) 119–129 and the Sioux‐Falls network with 24 nodes to show that the space decomposition algorithm can obtain the exact probability of these classical examples efficiently. © 2016 Wiley Periodicals, Inc. Naval Research Logistics 63: 479–491, 2016