A terrain risk assessment method for military surveillance applications for mobile assets

This study proposes an analytical and flexible terrain risk assessment method for military surveillance applications for mobile assets. Considering the risk as the degree of possibility of insurgent presence, the assessment method offers an efficient evaluation of risk in the surrounding terrain for military combat operating posts or observation posts. The method is designed for unmanned aerial vehicles as the surveillance assets of choice to improve the effectiveness of their use. Starting with the area map and geographical data, the target terrain is first digitized for space representation. Then the data of nine geographical parameters are used to formulate five contributing risk factors. These factors are incorporated in an analytical framework to generate a composite map with risk scores that reveal the potential high-risk spots in the terrain. The proposed method is also applied to a real-life case study of COP Kahler in Afghanistan, which was a target for insurgent attacks in 2008. The results confirm that when evaluated with the developed method, the region that the insurgents used to approach COP Kahler has high concentration of high-risk cells.     

我国电力光缆应用和市场的发展及问题

追溯了我国电力光缆应用的发展过程，讨论了在市场和产业的形成、发展中所出现的问题。     

组合拱式管桥计算机模拟设计

本文在已有成果资料的基础上，为组合拱式管桥的设计建立了常规设计表达式，并研制出组合拱式管桥计算机模拟的程序软件ＣＡＰＢＤ。该软件具有以下计算功能：（１）计算组合管拱的几何特征参数；（２）计算组合管拱自重和组合拱式管桥的竖向荷载及其材料费用；（３）分析和计算各种载荷作用下组合拱式管桥的内力；（４）组合拱式管桥各控制截面强度校核、稳定性验算以及拱支墩稳定性验算和地基承载力强度校核。     

Vegetation Change in Great Lakes Coastal Wetlands: Deviation from the Historical Cycle

Water-level change is integral to the structure and function of Great Lakes coastal wetlands, and many studies document predictable relationships between vegetation and water level. However, anthropogenic stressors, such as invasive species, land-use change, and water-level stabilization, interact to shift the historical cycle (of native vegetation migration up- and down-slope) toward dominance by invasive Typha species. Knowing from earlier studies that water-level stabilization alters the historical vegetation cycle, we asked if similar shifts can occur where water levels are not stabilized. Using historical aerial photographs of three coastal wetlands (in Lake Michigan's Green Bay, Wisconsin), we determined that habitat dominated by Typha species has expanded to eliminate wet meadow habitat. Between 1974 and 1992, linear regressions showed strong, significant relationships of both meadow area (R² ≥ 0.894; p < 0.02) and marsh area (R² ≥ 0.784; p < 0.05) to water level in all three wetlands. In 2000, meadow area was below that predicted by the historical pattern due to the landward advance of marsh habitat during a year of decreasing water levels. In the same period, land use in the wetland watersheds converted from agriculture to urban. Urbanization and the replacement of native Typha latifolia by the invasive hybrid Typha xglauca may have overwhelmed the beneficial impact of water-level fluctuation. The documentation of vegetation shifts, as herein, is an essential step in the process of preserving and restoring ecological integrity.     

水下成像的现状和发展动向

本文以下水成像在军事，海洋开发工程应用为基础，论述了水下观测和成像中采用微光电视摄像机和激光器件及其系统的技术现状和发展动向。     

车联网中基于轨迹预测的无人机动态协同优化覆盖算法

针对城市车联网中出现的基站覆盖空洞及局部流量过载等问题,提出了一种基于车辆轨迹预测信息的动态预部署方案。首先,为了训练得到统一的seq2seq-GRU轨迹预测模型,多个携带边缘计算服务器的无人机在分布式联邦学习与区块链的架构下,去除中心聚合节点,采取改进的Raft算法,在每轮训练中根据贡献数据量的大小,选举得到节点来完成参数聚合及模型更新任务。其次,基于模型预测结果,提出了一种改进的虚拟力向导部署算法,通过各虚拟力来引导无人机进行动态地部署以提升车辆的接入率及通信质量。仿真结果表明,提出的训练架构能够加速模型的训练,部署算法在提升车辆接入率的同时提升了车辆与无人机之间的通信质量。     

架空乘人装置用隔爆兼本安型控制箱的研制

针对采用继电器控制方式控制架空乘人装置存在维护困难、工作效率低、安全性能差等问题,提出了一种基于PLC控制的架空乘人装置用控制箱的研制方案,介绍了该控制箱的硬件、软件设计及功能特点。该控制箱采用PLC作为控制核心、MT6070I系列触摸屏作为人机界面,实现了架空乘人装置及时停车、急停闭锁、状态及时显示、保护等功能。实际应用表明,该控制箱运行稳定,实现了全自动无人值守运行,提高了架空乘人装置的安全性和可靠性。     

无人机空中加油控制设计与仿真

无人机空中加油控制精度问题,无人受油机模型的各种不确定性与来自外部的各种干扰归结为扰动,造成控制精度差。为解决上述问题,提出一种免疫粒子群优化算法的自抗扰无人机自主空中加油飞行控制律设计方法。利用自抗扰控制能够自动检测并补偿内部与外部干扰影响的特点,并利用扩张状态观测器进行估计与补偿,从而增强了所设计飞行控制律的鲁棒性,用免疫粒子群优化算法对自抗扰控制器参数进行了优化研究,以提高设计效率。仿真结果表明,所设计的自抗扰自主空中加油控制系统具有优良的控制性能与较高的控制精度,能够满足无人机自主空中加油的要求。     

基于无人机倾斜摄影的嘉兴老城区住宅识别

为了应对老城区房屋数据信息不足、获取不便的问题,提出利用无人机（UAV）倾斜摄影测量技术实现老城区住宅自动识别的方法. 根据老城区典型多层住宅的外立面特征,确定出阳台构造、立面朝向和房屋长宽比3个参数控制的住宅判别标准. 通过无人机摄影测量获取嘉兴研究区的密集匹配点云、数字正射影像（DOM）和数字表面模型（DSM）数据. 融合DOM及DSM数据提取单体建筑轮廓,分割出单体房屋点云. 基于RANSAC算法提取房屋立面点云并确定立面朝向,根据立面的点云空间分布判断立面长度及阳台构造. 试验表明,在研究区应用该方法识别典型住宅的准确率可以达到90%.     

高空作业平台臂架伸缩运动的横向振动特性

为了探究高空作业平台做伸缩运动时变幅平面内的横向振动动力学特性,针对臂架的实际搭接和支承情况,将臂架等效为根部铰接、中间弹性支承且带有集中参数的变截面变长度梁. 基于牛顿第二定律建立各臂段的运动微分方程,采用模态叠加法、结合边界条件求解臂架一系列时刻的瞬态振型函数,曲线拟合时变参数以近似表示梁的振型,并依据伽辽金截断方法,得到广义坐标下的状态空间方程. 在Matlab/Simulink环境下进行动态仿真,得到伸缩过程中臂架头部的变幅平面横向振动动态响应. 结果表明,就横向振动振幅而言,搭接简化会带来15.63%计算结果误差;支承简化会加大臂架整体刚度、减小臂架振动响应,不可取。