无人机三维航迹规划方法研究

航迹规划算法是无人机关键技术之一,同时也是任务规划系统（Mission Planning System）核心之一。针对固定目标规划问题,提出一种voronoi图改进算法和动态稀疏A*算法融合的三维航迹规划方法。该方法针对固定威胁目标,通过改进voronoi图规划算法快速求解二维航迹路径,然后在该路径参考下,用动态稀疏A*算法求解符合无人机飞行动力学约束的三维航迹。试验表明,该算法比动态稀疏A*算法规划速度快,并保证了航迹最优性。     

基于稀疏A*搜索和改进人工势场的无人机动态航迹规划

针对不同属性的障碍物所构成的威胁分布模型, 本文提出了一种基于稀疏A*搜索算法预规划和改进人工势场相结合的无人机动态避障算法. 该算法首先对威胁分布建立栅格化模型; 然后根据静态威胁, 基于稀疏A*搜索算法进行全局航迹规划; 最后结合预规划路径和动态威胁分布, 利用改进人工势场法完成无人机的动态避障. 仿真结果表明, 该方法能够规划出给定威胁指标下的全局最优路径并达到良好的动态规避性能.     

基于贝叶斯网络和蚁群算法的航路优化

为了提高无人机（UAV）的作战效率和生存概率,在UAV执行任务前,必须为其设计高效的飞行航路。采用将贝叶斯网络模型威胁强度评估算法与蚁群算法相结合的航路规划方法,根据UAV航路规划问题的特点对蚁群算法进行改进。仿真结果表明,该方法能更好地满足实时战场需要,得到良好的优化航路。     

A*初始化的变异灰狼优化的无人机路径规划

无人机(unmanned aerial vehicle,UAV)路径规划问题是无人机任务规划系统的重要组成部分,需要在一个存在威胁区的搜索空间中获得最优路径.为解决灰狼优化算法存在收敛速度慢、容易陷入局部最优等问题,提出了一种基于A*初始化的变异灰狼优化算法.该算法首先将模型离散化,进而使用A*算法进行头狼的初始化,使...     

UAV/UGV协同环境下的目标识别与全局路径规划研究

针对单独机器人难以执行复杂环境中任务的问题,Unmanned Air/Ground Vehicle(UAV/UGV)协同系统近年来受到了广泛关注。为了提高执行任务的工作效率,提出一种基于视觉传感器下UAV/UGV协同系统中UAV目标识别下UGV全局路径规划的方法,无人机利用高空视野优势获取目标物与环境信息, SURF算法和图像分割实现环境建模。无人车根据无人机获取的信息,利用优化的A*算法完成全局路径规划,并且在典型搜救场景中进行了仿真验证。实验表明,SURF算法能满足目标识别的精确度、实时性和鲁棒性;并且利用优化的A*算法实现了UGV快速准确的全局路径规划。     

基于遗传算法的UAV自适应航迹规划

根据遗传算法与动态的稀疏A*搜索(Dynamic Sparse A*Search,DASA)算法各自的特点,提出一种组合优化算法来实现在不确定战场环境中自适应航迹规划.在无人机(UAV,Unmanned Aerial Vehicles)飞行前,采用全局搜索能力强的遗传算法进行全局搜索,对从起始点到目标点的飞行航线进行规划,生成全局最优或次优的可行参考飞行航线;在无人机任务执行阶段,以参考飞行航线为基准,采用DASA算法进行在线实时航迹再规划.仿真结果表明,与遗传算法相比,该组合算法不但能生成近似最优解,而且能够满足在线实时应用的要求.     

3维复杂山地环境下旋翼无人飞行器高时效航迹规划策略

针对3维复杂山地环境中执行无碰撞低空飞行任务的旋翼无人飞行器,提出了一种高时效、低代价的航迹规划策略,设计并采用了改进的稀疏A*算法和生物启发神经动力学模型的融合算法.该算法在稀疏A*全局优化搜索的基础之上融入生物启发神经动力学模型来调整局部航线以加快最优航迹的形成,并运用神经动力学模型来实时获取和处理环境中的局部动态信息,实现了融合算法的在线规划能力,从而解决了传统最优路径搜索算法无法实现的动态规划的难题.通过在3维空间中设置多峰山地,尤其是凹形山体作为障碍进行仿真实验,实验结果表明,该融合算法不仅降低了A*算法的复杂度和耗时,而且改善了生物启发神经动力学模型尚未考虑的代价花费问题,更能够在线应对任务空间中的突发威胁,使旋翼无人飞行器在动、静态障碍物相结合的复杂环境下能够规划出一条安全、快速抵达目标点的低代价且优质的航迹.     

基于改进A*算法的无人机航迹规划

在无人机航迹规划问题的研究中,针对在执行飞行任务前,需要根据所经区域内已知的地形、地貌、障碍和威胁等信息以及飞机本身机动能力的限制计算出飞行航迹, 并根据规划出的航迹完成飞行任务.能准确识别起始点到目标航路,提出了一种基于改进A*算法的无人机航迹规划方法,将无人机自身的性能和飞行任务结合到A*算法中去,在节点的搜索过程中解决了A*算法大空间搜索耗时多的问题.通过简单的路径消减算法去除不必要的航迹点,使得规划出来的航迹能够最大程度上满足无人机的运动特性.仿真结果表明采用的方法计算速度快并且规划达到最优性能.     

基于定向A*算法的多无人机同时集结分步策略

设计一种基于定向A*算法的多无人机同时集结分步策略.首先,提出一种定向A*算法,将无人机最大俯仰角与偏航角作为A*算法搜索约束,从而缩小节点扩展区域,并通过循环寻优规避“死区”点,进而产生平滑可飞的预规划航迹;其次,论述了补偿航程差的变步长多点搜索、三维盘旋机动、虚拟威胁等分步再规划算法,使得多无人机同时集结于目标点附近.仿真结果表明,所提出的算法能够有效完成多无人机同时集结任务.     

基于A*算法的高超声速飞行器航迹规划方法

为了提高A*算法应用于高超声速飞行器航迹规划时的效率和稳定性,并保证航迹可飞性,提出基于改进型变步长稀疏A*算法的航迹规划方法。首先根据飞行器飞行区域不存在地形限制的特点,在规划过程中采取变步长策略,有效地提高了远程规划时的稳定性和效率;然后依赖飞行器的过载计算最大转弯角和爬升/俯冲角,根据计算角度构建规划空间,同时将飞行器飞行过程燃料/时间、航向、飞行高度、航迹末端、禁飞区域等约束用于规划空间优化,减少扩展节点的数量,进一步提高了规划效率并保证航迹的可飞性;最后基于威胁约束设计特殊的代价函数,保障了飞行安全和航迹规划的稳定性。仿真结果表明:规划出的航迹满足高超声速飞行器各种飞行要求,能避开各种威胁,规划时间短,稳定性好。得到的航迹能够作为航迹跟踪控制系统设计时的参考输入。     

Evidence-based recommendations for building better bras for women treated for breast cancer

Participating in exercise is beneficial for women who have been treated for breast cancer. However, not being able to find a comfortable exercise bra can be a barrier to exercise participation. This study aimed to systematically investigate what breast support women treated for breast cancer want when they exercise in order to provide evidence-based recommendations to improve exercise bra designs for these women. Based on 432 responses from a national online survey, frequency and relationship data were analysed (binary logistic regression) to understand exercise bra issues pertinent to this population. These issues included being able to control for asymmetrical cup sizes, managing heightened skin sensitivity, managing fluid (size) fluctuations, managing a prosthesis and restoring body image by restoring shape. This study provides evidence-based recommendations to inform an exercise bra design that will meet the unique needs of women treated for breast cancer. Rigorous, evidence-based evaluations of exercise bras for women treated for breast cancer may contribute to their well-being and quality of life through enhanced designs.     

一种SIP穿越NAT的解决方案

NAT使得SIP端到端的应用变得非常困难,文章分析了几种SIP穿越NAT方法及其不足,提出了一种基于STUN和TURN方法的穿越方案.其基本思想是根据NAT的不同采用不同的方式实现SIP信令的穿越,而媒体流的穿越则通过对所有可用媒体地址进行连接检查来实现.方案不改动现有NAT,在应用层上实现了对所有NAT的有效穿越,避免单独使用其它方法带来的缺陷.     

医院多功能情报监控系统的研究

介绍了基于AT89S52单片机设计的医院多功能情报监控系统,该系统分为监测端和控制端2个部分.监测端位于病房内,和控制端通过CAN总线进行通讯,传递病房内的环境参数以及室内环境调节装置的控制信息.控制端位于控制室内,通过RS232与上位机通信,可以使用计算机上的C语言编译的人机对话界面,对各个病房的环境进行实时监测调节.     

Grammar engineering for multiple front-ends for Python

In this paper, we describe our experience in grammar engineering to construct multiple parsers and front ends for the Python language. We present a metrics-based study of the evolution of the Python grammars through the multiple versions of the language in an effort to distinguish and measure grammar evolution and to provide a basis of comparison with related research in grammar engineering. To conduct this research, we have built a toolkit, pygrat , which builds on tools developed in other research. We use pygrat to build a system that automates much of the process needed to translate the Python grammars from EBNF to a formalism acceptable to the bison parser generator. We exploit the suite of Python test cases, used by the Python developers, to validate our parser generation. Finally, we describe our use of the menhir parser generator to facilitate the parser and front-end construction, eliminating some of the transformations and providing practical support for grammar modularisation.     

Regional Process Modeling for Design for Environment

This research is an effort towards providing higher level Design for Environment (DFE) tools for a broad industrial region. Issues ranging from the levels immediately above existing design tools, to the envisioned highest level for a broad geographical region are discussed. A tool for the regional planning of the DFE activities is proposed, considering a model construction based on material flows across the industry. The Multi-Lifecycle approach is supported by organizing the input/output flows for industries, potentially utilizing waste material, side products and recycling. Capitalizing on the conceptual integration of the design and process activities, an Abstract Design Environment is used for the design of the basically process oriented material flow tool. Within the context, the relations among design, process and flow-modeling concepts are discussed.     

Louvers design for LED displays for sunny days

The use of louvers attached to variable information display needs to be optimized taking into account different intrinsic and extrinsic parameters. The analysis of the performance of the display–louvers system takes into account the location, orientation, and daily and seasonal variations. The observation of the system is divided depending on the distance of observation. The far distance vision performance use the background luminance. The medium distance performance needs the use of the Contrast Sensitivity Function of the eye.