Experimental study on explosion dispersion process of a multi-layer composite charge under different initiation modes

The influence of initiation modes on the explosive dispersion process of the multi-layer composite charge (MCC) was studied. Overpressure sensors and high-speed photography system were used to investigate the energy release process of an MCC with a specific structure. The shock wave pressure and explosive dispersion characteristics of the MCC under different initiation modes were compared. The forming and expanding process of the shock wave of the composite charge under different initiation modes was determined. The separation position of the shock wave and fireball interface was determined. The calculation formulas of the shock radius and overpressure of the composite charge are presented. The radius of the shock wave of the composite charge was significantly affected by the initiation mode. Moreover, the development process of the composite explosive fireball under different initiation modes was analyzed, the variation rules of the composite charge dispersion radius and fireball dispersion velocity with time were obtained under the different initiation modes, the explosion energy release rate of composite charge under simultaneous initiation modes was the highest, and the peak overpressure under the simultaneous initiation mode was 1.61 times that of central single-point initiation.     

A novel noise reduction technique for underwater acoustic signals based on complete ensemble empirical mode decomposition with adaptive noise,minimum mean square variance criterion and least mean square adaptive filter

Underwater acoustic signal processing is one of the research hotspots in underwater acoustics. Noise reduction of underwater acoustic signals is the key to underwater acoustic signal processing. Owing to the complexity of marine environment and the particularity of underwater acoustic channel, noise reduction of underwater acoustic signals has always been a difficult challenge in the field of underwater acoustic signal processing. In order to solve the dilemma, we proposed a novel noise reduction technique for underwater acoustic signals based on complete ensemble empirical mode decomposition with adaptive noise (CEEMDAN), minimum mean square variance criterion (MMSVC) and least mean square adaptive filter (LMSAF). This noise reduction technique, named CEEMDAN-MMSVC-LMSAF, has three main advantages: (i) as an improved algorithm of empirical mode decomposition (EMD) and ensemble EMD (EEMD), CEEMDAN can better suppress mode mixing, and can avoid selecting the number of decomposition in variational mode decomposition (VMD); (ii) MMSVC can identify noisy intrinsic mode function (IMF), and can avoid selecting thresholds of different permutation entropies; (iii) for noise reduction of noisy IMFs, LMSAF overcomes the selection of decomposition number and basis function for wavelet noise reduction. Firstly, CEEMDAN decomposes the original signal into IMFs, which can be divided into noisy IMFs and real IMFs. Then, MMSVC and LMSAF are used to detect identify noisy IMFs and remove noise components from noisy IMFs. Finally, both denoised noisy IMFs and real IMFs are reconstructed and the final denoised signal is obtained. Compared with other noise reduction techniques, the validity of CEEMDAN-MMSVC-LMSAF can be proved by the analysis of simulation signals and real underwater acoustic signals, which has the better noise reduction effect and has practical application value. CEEMDAN-MMSVC-LMSAF also provides a reliable basis for the detection, feature extraction, classification and recognition of underwater acoustic signals.     

基于部分可辨识振动系统的载荷恢复方法

在复模态分析和参数辨识的基础上,对部分可辨识振动系统的载荷识别问题进行了研究,提出了基于部分可辨识复模态参数的载荷恢复方法。恢复模型存在幅值模糊和相位模糊,不存在排列模糊。数值仿真验证了该方法的有效性,并讨论了提高恢复精度的方法。     

信息/求解 Petri 网系统

绝大多数 Petri 网在变迁发生后前集库所会失去标记,不便于表达一个条件一旦具备将永远具备的情形.针对该问题,基于0-1标识与变迁发生后其前集不失去标记的思想,提出了信息/求解扩展 Petri 网系统(I/S系统).给出了I/S系统的相关定义、部分基本性质、矩阵表示、求解发生权向量的求法和状态方程.最后,给出了以I/S系统表示的几种常见滑模变结构控制策略的设计过程,该例显示了I/S系统的模型表达能力.     

量子技术在武器装备中的应用展望

量子技术是基于量子力学和其他学科交叉产生的新兴学科,已经涉及到计算、信息、导航、能源等多个应用领域。近年来,随着量子技术的快速发展和应用潜力,量子技术已成为研究热点并逐步走向应用。与此同时,世界新军事革命发展中武器装备须具有远程精确化、职能化、隐身化、无人化的技术特点。结合量子技术的特点,从量子计算,量子通信与量子密码、量子控制、量子导航、量子雷达,量子电池,量子技术对作战模式的改变等方面对武器装备领域的应用、作战能力和作战模式进行阐述。研究表明,量子计算的发展必然使现有武器装备的性能得到提高、作战能力得到提升,进而改变现有作战模式。     

美“海军一体化火力控制--制空”能力发展现状与启示

美“海军一体化火力控制－制空”（ NIFC－CA）是美军海上盾牌防御体系概念的重要组成部分。该体系经过多年的发展已初见成效。首先，对美“海军一体化火力控制———制空”的基本概念及内涵进行了阐述，对其主要组成CEC、E－2D预警机、宙斯盾系统及标准－6舰空导弹在防御体系中的功能进行了分析；然后，介绍了美NIFC－CA的6种主要指挥控制模式，并对其协同指挥决策模式进行了分析，得出了指挥决策分布处理的特点；最后，总结了美NIFC－CA发展对我海军海上防御力量发展建设的启示。     

舰艇作战系统工作模式及其作战对策分析*

探讨了基于敌情事件触发的舰艇作战系统工作模式及其作战对策。根据舰艇的内外部需求,依据传感器系统与武器系统所处的状态,提出了舰艇作战系统的五种工作模式。并研究了在敌情事件触发下,如何根据舰艇所处的工作模式,迅速做出相应的作战对策,给出各种模式下的模式转换流程。这种作战对策可使作战过程自动化、信息传输扁平化,从而提高舰艇在紧急状况下的反应速度。     

电磁脉冲武器对抗来袭目标可行性研究

针对电磁脉冲武器独特的毁伤机理,计算了杀伤覆盖区域和辐射到目标处的功率密度等作战能力指标,并以反舰导弹为例分析了强电磁脉冲的耦合途径,通过评估前后门耦合的电磁能量,在理论上论证了用电磁脉冲武器对抗来袭目标的可行性.     

Balancing a one‐way corridor capacity and safety‐oriented reliability: A stochastic optimization approach for metro train timetabling

In urban rail transit systems of large cities, the headway and following distance of successive trains have been compressed as much as possible to enhance the corridor capacity to satisfy extremely high passenger demand during peak hours. To prevent train collisions and ensure the safety of trains, a safe following distance of trains must be maintained. However, this requirement is subject to a series of complex factors, such as the uncertain train braking performance, train communication delay, and driver reaction time. In this paper, we propose a unified mathematical framework to analyze the safety‐oriented reliability of metro train timetables with different corridor capacities, that is, the train traffic density, and determine the most reliable train timetable for metro lines in an uncertain environment. By employing a space‐time network representation in the formulations, the reliability‐based train timetabling problem is formulated as a nonlinear stochastic programming model, in which we use 0‐1 variables to denote the time‐dependent velocity and position of all involved trains. Several reformulation techniques are developed to obtain an equivalent mixed integer programming model with quadratic constraints (MIQCP) that can be solved to optimality by some commercial solvers. To improve the computational efficiency of the MIQCP model, we develop a dual decomposition solution framework that decomposes the primal problem into several sets of subproblems by dualizing the coupling constraints across different samples. An exact dynamic programming combined with search space reduction strategies is also developed to solve the exact optimal solutions of these subproblems. Two sets of numerical experiments, which involve a relatively small‐scale case and a real‐world instance based on the operation data of the Beijing subway Changping Line are implemented to verify the effectiveness of the proposed approaches.     

地铁火灾应急预案的制定

介绍地铁火灾发生时的几个主要的特点以及其巨大的危害性,引出了地铁火灾应急预案制定模式的重要性。通过对已有的资料进行研究、分析,同时结合实际,对地铁火灾应急预案制定时所包含的主要内容进行了科学的完善,得出了一个完整的预案制定模式。