地形跟随飞行轨迹设计与仿真验证

研究优化低空突防地形跟随飞机过顶时的飞行轨迹,飞行要求稳定性和快速性,减小超调,实现地形跟随飞机"平飞推跃"过顶。为达到理想地形跟随轨迹,提出设计抑制函数,建立某型飞机的数学仿真模型,搭建控制航迹倾角的地形跟随系统结构,在MATLAB软件平台上对抑制函数进行仿真,结果表明,采用抑制函数能够减小过顶超调,缩短暴露时间,实现"平飞推跃"过顶,改善了飞机过顶综合性能。证明所设计的抑制函数能够满足地形跟随需要,并优化了过顶跟随轨迹动态性能。     

基于数字地图的亚音速飞行器最优地形跟随

针对真实高山地形设计了一套地形跟随系统;首先,根据数字地图结合航迹规划算法生成参考航迹;接着设计了一个基于滚动时域优化的航迹控制器,用于跟踪航迹、稳定速度并处理约束,将预测时域内的航迹点作为参考输入,通过最小化跟踪误差以及滚动优化实时求解控制量;仿真结果表明,与基于适应角导引的地形跟随系统相比,文章的方法具有更好的性能,能够满足亚音速飞行器地形跟随任务需求.     

基于模糊控制方法的自动地形跟随系统设计

对飞机纵向地形跟随控制系统控制律的设计问题进行了研究。为了消除干扰,提高跟踪效果,首先以飞机的纵向运动状态为研究对象,建立了相应的自动地形跟随控制系统结构模型,再应用模糊控制的方法分别通过控制航迹角和控制法向加速度两种方案设计了飞机纵向地形跟随系统的控制律,同时给出了仿真验证的模型,然后对模型各个输出的特性以及地形跟随的效果进行了仿真验证,仿真结果表明,设计的控制系统得到了良好的地形跟随效果,最后以控制航迹角的系统响应曲线为例,通过与传统的PID控制效果进行对比,说明经过模糊控制的系统具有良好的抗干扰性。     

机动性约束下低空突防航迹规划算法研究

研究飞行器多目标优化问题,为了寻求安全突防的飞行轨迹,结合低空突防中对飞行器实际飞行轨迹的要求,对航迹规划算法进行了研究.针对改善目前航迹规划过程中所存在的几何建模困难和所得轨迹不能符合实际可飞的问题,提出了一种新的垂直面轨迹规划方法.方法在水平面规划的基础上重点分析了飞行器垂直面内的运动状态,结合过载、航迹倾角等机动性约束条件对垂直面内的运动轨迹进行研究,将实际复杂的飞行轨迹简化为由直线段和圆弧段衔接而成的轨迹模型,针对简化模型进行轨迹规划.仿真结果表明,能够得到满足约束条件,并符合实际飞行的航迹.     

基于卡尔曼滤波的轨迹规划高度修正仿真实现

综合地形跟随/地形回避（TF/TA）是新一代低空突防技术,其中的轨迹规划技术是飞行器低空突防飞行控制律设计的重要依据.针对飞行器实时飞行过程中存在各种误差因素影响规划轨迹性能的情况,设计卡尔曼滤波器在实时轨迹规划中对所获取的飞行器高度值进行修正,可以获得比较精确的离地高度信息提供给飞行器,从而增加飞行器的安全系数.建立系统的状态与观测数学模型,在给定初始值和噪声方差阵的情况下进行了仿真.仿真结果显示所设计的卡尔曼滤波器可行,大大减小了组合导航系统误差模型的作用效果.     

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。     

高超声速飞行器飞行轨迹的模糊控制设计

针对高超声速飞行器飞行过程中因干扰造成的飞行轨迹散布问题,提出了采用飞行器飞行轨迹的模糊控制设计方法。方法以高超声速飞行器飞行轨迹线偏差和线偏差变化率作为模糊控制器输入,采用模糊推理设计飞行控制系统。在完成高超声速飞行轨迹控制系统数学建模的基础上,结合自动驾驶仪特点对飞行轨迹模糊控制系统进行了设计。结论通过仿真表明所设计的飞行控制系统满足飞行轨迹及攻角性能要求,验证了方法的正确性。     

飞行器整体航迹规划建模/仿真的研究与实现

航迹规划是低空突防过程中的关键技术,目的是得到一条既安全可靠又全局代价最优的三维航迹,是导航系统和控制系统的基础之一.在对整体航迹规划技术进行研究与实现的过程中,详细讨论了威胁建模、地形预处理、航迹规划算法等问题,并采用建模/仿真技术给出了实现流程以及试验结果.规划出的参考航迹能够满足低空突防飞行器进行"地形跟随/地形回避/威胁回避"机动飞行的需要.随着航迹规划问题的解决,建立了"地形跟随/地形回避/威胁回避"为主要手段的低空突防技术论证与试验环境.     

飞行器参考航迹规划方法研究

研究飞行器参考航迹规划优化控制问题,飞行器受到飞行达时间、油耗、威胁和地形环境等因素影响,传统的依靠飞行员的视觉效应,达不到优化的要求,同时飞行航迹实时性差.为了找到最优飞行器参考航迹,在分析当前飞行器航迹规划算法存在问题基础上,提出一种改进遗传算法的航迹规划方案.采用遗传算法对飞行器参考航迹进行全局搜索,快速找到全局最优解区域,并在全局最优区域通过模拟退火算法进行局部搜索,得到最优航迹.仿真结果表明,改进遗传算法能够快速找到最优参考航迹,能很好满足在线实时航迹规划的要求,是一种比较理想的飞行器参考航迹规划算法.     

基于遗传算法的飞行器参考航迹规划

针对飞行器航迹规划问题展开研究,为了规划出最优满意的飞行轨迹,分析了飞行器航迹规划中存在的威胁与自身约束条件,提出了一种关于遗传算法的航迹规划方案,采用改进编码机制对飞行器在已知威胁情况下飞行航迹进行整体规划。取航迹个体只包含一个染色体,每个染色体为一个航迹点序列,随机生成种群,通过选择交叉变异,并将各种威胁和约束条件的影响适当的加入到适应值函数中,得到优化路径进行仿真。仿真结果给出了不同加权比例下所得到的最优航迹,通过仿真验证了算法的有效性。     

煤矿井下安全监控分站的设计及其仿真实现

为了设计一种具有低成本、低功耗、易操作、功能强且可靠性高的煤矿井下安全分站,针对煤矿安全生产实际,文章提出了采用MCS-51系列单片机为核心、具有CAN总线通信接口的煤矿井下安全监控分站的设计方案;首先给出煤矿井下安全监控分站的整体构架设计,然后着重阐述模拟量输入信号处理系统的设计过程,最后说明单片机最小系统及其键盘、显示、报警、通信等各个组成部分的设计;为验证设计方案的可行性与有效性,使用Proteus软件对设计内容进行仿真验证,设计的煤矿井下安全监控分站具有瓦斯、温度等模拟量参数超标报警功能和电机开停、风门开闭等开关量指示功能;仿真结果表明:设计的煤矿井下安全监控分站具有一定的实际应用价值.     

View-based model-driven architecture for enhancing maintainability of data access services

In modern service-oriented architectures, database access is done by a special type of services, the so-called data access services (DAS). Though, particularly in data-intensive applications, using and developing DAS are very common today, the link between the DAS and their implementation, e.g. a layer of data access objects (DAOs) encapsulating the database queries, still is not sufficiently elaborated, yet. As a result, as the number of DAS grows, finding the desired DAS for reuse and/or associated documentation can become an impossible task. In this paper we focus on bridging this gap between the DAS and their implementation by presenting a view-based, model-driven data access architecture (VMDA) managing models of the DAS, DAOs and database queries in a queryable manner. Our models support tailored views of different stakeholders and are scalable with all types of DAS implementations. In this paper we show that our view-based and model driven architecture approach can enhance software development productivity and maintainability by improving DAS documentation. Moreover, our VMDA opens a wide range of applications such as evaluating DAS usage for DAS performance optimization. Furthermore, we provide tool support and illustrate the applicability of our VMDA in a large-scale case study. Finally, we quantitatively prove that our approach performs with acceptable response times.     

Call for Papers The 6^th International Conference on Grid and Cooperative Computing

Recent years have seen rapid advances in various grid-related technologies, middleware, and applications. The GCC conference has become one of the largest scientific events worldwide in grid and cooperative computing. The 6th international conference on grid and cooperative computing (GCC2007) Sponsored by China Computer Federation (CCF),Institute of Computing Technology, Chinese Academy of Sciences (ICT) and Xinjiang University ,and in Cooperation with IEEE Computer Soceity ,is to be held from August 16 to 18, 2007 in Urumchi, Xinjiang, China.     

A pragmatic multi-method investigation of discrepant technological events: Coping,attributions, and ‘accidental’ learning

Discrepant technological events or situations that entail a problem, a misunderstanding or a difficulty with the Information Technology (IT) being employed, are common in the workplace, and can lead to frustration and avoidance behaviors. Little is known, however, about how individuals cope with these events. This paper examines these events by using a multi-method pragmatic approach informed by coping theory. The results of two studies – a critical incident study and an experiment – serve to build and test, respectively, a theoretical model that posits that individuals use a variety of strategies when dealing with these events: they experience negative emotions, make external attributions, and adopt engagement coping strategies directed at solving the event, eventually switching to a disengagement coping strategy when they feel they have no control over the situation. Furthermore, users’ efforts may result in ‘accidental’ learning as they try to overcome the discrepant IT events through engagement coping. The paper ends with a discussion of the results in light of existing literature, future opportunities for research, and implications for practice.     

The Distributed Time-Triggered Simulation Scheme: Core Principles and Supporting Execution Engine

Distributed real-time simulation is a young technology field but its practice is under increasing demands. In recent years the author and his collaborators have been establishing a new approach called the distributed time-triggered simulation (DTS) scheme which is conceptually simple and easy to use but widely applicable. The concept was initiated in the course of developing a new-generation object-oriented real-time programming scheme called the time-triggered message-triggered object (TMO) programming scheme. Some fundamental issues inherent in distributed real-time simulation that were learned during recent experimental studies are discussed along with some approaches for resolving the issues. An execution engine developed to support both the TMOs engaged in control computation and the TMOs engaged in DTS is also discussed along with its possible extensions that will enable significantly larger-scale DTSs.     

Software-Konfigurationsmanagement in großen Softwareprojekten

Zusammenfassung Mit zunehmender Größe der Softwaresysteme verschärfen sich die für die Software-Herstellung typischen Probleme: Beherrschen großer Objektmengen, Erhalten der Systemkonsistenz, Kontrolle der ständigen Änderungseinflüsse und Gewährleisten einer langen Lebensdauer. Die Disziplin Konfigurationsmanagement bildet den methodischen Ansatz, diese Probleme besser zu beherrschen. Software-Konfigurationsmanagement faßt die Herstellung von Softwaresystemen als eine Abfolge von kontrollierten Änderungen an gesicherten Zwischen- und Endergebnissen auf. Dargestellt werden die Objekte und Funktionen des Software-Konfigurationsmanagements sowie die hierfür in großen Software-Projekten benötigten Methoden, Instanzen und Hilfsmittel.     

Information for Authors

正http://www.zju.edu.cn/jzus http://www.springerlink.com Aim The Journals of Zhejiang University-SCIENCE(A/B/C)are edited by the international board of distinguished Chinese and foreign scientists,and are aimed to present the latest developments and achievements in scientific research in China and     

Editorial:Brain-machine interface(BMI) and cyborg intelligence

正Brain-machine interfaces(BMIs)aim at building a direct communication pathway between the brain and an external device,and represent an area of research where significant progress has been made during the past decade.Based on BMIs,mind information can be read out by neural signals to control     

Information for Authors

正http://www.zju.edu.cn/jzus http://www.springerlink.com Aim The Journals of Zhejiang University-SCIENCE(A/B/C)are edited by the international board of distinguished Chinese and foreign scientists,and are aimed to present the latest developments and achievements in scientific research in China and overseas to the world’s scientific circles,especially to stimulate     

SCIENCE CHINA Information Sciences SUBJECT INDEX TO VOLUME 57(2014)

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