A joint mid-course and terminal course cooperative guidance law for multi-missile salvo attack

Salvo attacking a surface target by multiple missiles is an effective tactic to enhance the lethality and penetrate the defense system. However, existing cooperative guidance laws in the mid-course or terminal course are not suitable for long- and medium-range missiles or stand-off attacking. Because the initial conditions of cooperative terminal guidance that are generally generated from the mid-course flight may not lead to a successful cooperative terminal guidance without proper mid-course flight adjustment. Meanwhile, cooperative guidance in the mid-course cannot solely guarantee the accuracy of a simultaneous arrival of multiple missiles. Therefore, a joint mid-course and terminal course cooperative guidance law is developed. By building a distinct leader-follower framework, this paper proposes an efficient coordinated Dubins path planning method to synchronize the arrival time of all engaged missiles in the mid-course flight. The planned flight can generate proper initial conditions for cooperative terminal guidance, and also benefit an earliest simultaneous arrival. In the terminal course, an existing cooperative proportional navigation guidance law guides all the engaged missiles to arrive at a target accurately and simultaneously. The integrated guidance law for an intuitive application is summarized. Simulations demonstrate that the proposed method can generate fast and accurate salvo attack.     

系统思想在航天企业全面风险管理实施中的应用

介绍了风险管理国际标准ISO31000的核心内容——风险管理框架,以及系统思想的基本理念;以系统观点和方法为基础,对国际标准在航天企业全面风险管理中的应用进行了探讨。通过对全面风险管理工作的系统分解与集成,并以其中的"环境"分系统建设为例,进一步细分工作内容,与现有业务管理工作相结合,探索出全面风险管理工作在航天企业落地的基本路径。     

自动铺丝最小间隙路径规划与复合材料锥壳结构制造

自动铺丝技术（AFP）是提高复合材料构件制造效率和降低其制造成本的关键技术和重要手段。铺放轨迹的设计是控制自动铺丝工艺质量的关键。对于复杂的结构形式，合理的铺丝路径对保证可制造性及铺贴质量至关重要。本文针对简化后的后机身锥壳特征结构，研究了基于固定角法、测地线法和变角度法的自动铺丝轨迹算法设计，解决了铺放复杂曲面满覆盖问题；总结对比获得了不同铺丝轨迹方法的特点和适用范围。以保证工艺性并满足结构设计铺层方向为原则，选用了带宽为6.35 mm的自动铺丝预浸料完成工艺验证件制造，并通过有限元分析评估了自动铺丝轨迹算法的合理性。结果表明：该结构宜采用测地线法铺放0°方向铺层以减少褶皱；采用固定角法铺放90°方向铺层能够保证连续铺放；采用结合预浸窄带侧弯试验结果的变角度轨迹规划方法铺放此锥类构件±45°方向铺层能够保持最小间隙。铺丝间隙使锥壳结构单层等效模量下降约30%，整体强度下降约10%。因而在结构优化设计时需考虑自动铺丝工艺对安全裕度影响的因素。     

一个实用的WIN95启动界面

本文通过用简单的方法修改ＭＳＤＯＳ．ＳＹＳ和重新配置ＡＵＴＯＥＸＥＣ．ＢＡＴ文件。     

用于省内公路干线网规划研究的启发式模型

本文阐述了一种将运量在运输线路上的配置和投资在项目上的分配相结合的启发式方法的模型。文章对这种方法的原理与应用进行了研究探讨。     

规则回转体自动铺丝轨迹规划与丝束增减

为满足自动铺丝轨迹的满铺覆性要求，针对现阶段自动铺丝轨迹规划存在的不足，提出了不同的丝束增减算法。首先讨论纤维铺放方向的确定和中心轨迹数量的计算，设计不同铺放方向轨迹的生成算法。然后以丝束重叠系数为重要参数，对于纤维局部堆积和空缺问题提出单侧纤维裁剪算法和双侧纤维裁剪算法，并对裁剪后的重叠区域和间隙区域进行面积求解，使得纤维丝束均匀覆于芯模表面。最后基于CATIA CAA二次开发平台，将上述算法集成到纤维铺放CAD系统中，通过运动仿真系统验证算法的正确性。利用提出的丝束增减算法，实现了间隙/重叠区的均匀分布，尽量降低了富树脂区等相关缺陷的聚集对性能的不良影响。     

Optimization of beamforming and path planning for UAV-assisted wireless relay networks

Recently, unmanned aerial vehicles （UAVs） acting as relay platforms have attracted considerable attention due to the advantages of extending coverage and improving connectivity for long-range communications. Specifically, in the scenario where the access point （AP） is mobile, a UAV needs to find an efficient path to guarantee the connectivity of the relay link. Motivated by this fact, this paper proposes an optimal design for beamforming （BF） and UAV path planning. First of all, we study a dual-hop amplify-and-forward （AF） wireless relay network, in which a UAV is used as relay between a mobile AP and a fixed base station （BS）. In the network, both of the AP and the BS are equipped with multiple antennas, whereas the UAV has a single antenna. Then, we obtain the output signal~to-noise ratio （SNR） of the dual-hop relay network. Based on the criterion of maximizing the output SNR, we develop an optimal design to obtain the solution of the optimal BF weight vector and the UAV heading angle. Next, we derive the closed-form outage probability （OP） expression to investigate the performance of the dual-hop relay network conveniently. Finally, computer simulations show that the proposed approach can obtain nearly optimal flying path and OP performance, indicating the effectiveness of the proposed algorithm. Furthermore, we find that increasing the antenna number at the BS or the maximal heading angle can significantly improve the performance of the considered relay network.     

Investigations into sensing characteristics of circular thin-plate electrostatic sensors for gas path monitoring

Circular thin-plate electrostatic sensors are promising in gas path monitoring due to their advantages of non-intrusiveness and easy installation. The spatial sensitivity and filtering effect are two important performance parameters. In this paper, an analytically mathematical model of induced charge on a circular thin-plate electrode is first derived. Then the spatial sensitivity and filtering effect of the circular electrostatic sensor are investigated by numerical calculations. Finally,experimental studies are performed to testify the theoretical results. Both theoretical and experimental results demonstrate that circular thin-plate electrostatic sensors act as a low-pass filter in the spatial frequency domain, and both the spatial filtering effect and the temporal frequency response characteristics depend strongly on the spatial position and velocity of the charged particle. These conclusions can provide guidelines for the optimal design of circular thin-plate electrostatic sensors.     

基于遗传模拟退火算法的无人机航迹规划

航迹规划技术是无人机任务规划系统中重要的核心技术之一,无人机飞行空间广阔,需要一种快速搜索最佳路径的方法.首先在飞行区域中建立数字地图模型和防空威胁区模型,在满足无人机飞行约束条件的情况下,为无人机航迹规划提供一种遗传模拟退火算法,充分利用模拟退化算法的概率突跳特性和遗传算法强大的快速搜索能力.仿真结果表明,使用该算法无人机能够自动避开模拟数字地图的威胁区,搜索出一条安全有效航迹,并保证航线的完整性和最优性.     

基于三维空域网格的低空飞行航迹战略规划方法

针对复杂低空环境下航空应急救援飞行安全问题,提出了一种基于三维空域网格的飞行航迹战略规划方法。将空域网格化分成多个飞行航迹节点,同时考虑地形、气象、飞行规则以及航空器性能等多种约束,使用改进的A*算法搜索单个航空器的最优飞行航迹。在单个航空器初始飞行航迹基础上,结合时间窗原理,提出两种方法解决了多机无冲突航迹战略规划问题。最后,通过案例仿真验证了方法的有效性。