基于STK/Scheduler的空间天文卫星任务规划研究

空间天文卫星任务规划是一类复杂的NP难问题,将STK/Scheduler(Satellite Tool Kit/ Scheduler,卫星仿真工具包/任务规划)商业软件从对地观测任务规划领域拓展应用至空间天文卫星任务规划领域,对于获取可靠解算结果、快速构建地面运控仿真环境、提供解算参考基准具有重要意义。根据空间天文卫星任务规划问题,建立了以最大获取科学回报为目标的多约束任务规划模型,开展了基于STK/Scheduler的空间天文卫星任务规划解算和实例验证。实验结果表明:利用STK/Scheduler开展空间天文卫星任务规划能够适应多种规划时段和解算要求,具有求解稳定等特点,可以满足空间天文卫星任务规划的基本需求。     

面向多星任务规划问题的改进遗传算法

卫星数量的快速增加为管控卫星的工作增加了很大的难度,如何有效地进行任务规划,有效管理卫星资源,成为了卫星领域的一个重要问题.针对此问题,本文构建了多星任务规划的数学模型,将最大化任务收益作为优化目标.本文分析了问题的难点并提出了一种包含两种优化策略的改进遗传算法,包括全局优化和局部优化两部分.全局优化和局部优化根据种群改进情况进行自适应切换.通过两种优化方法的结合可以提升任务规划的效果.本文还提出了一种任务规划算法,用于为改进遗传算法得到的任务序列选择合适的任务执行时间.仿真实验证明本文提出的改进遗传算法可以很好地解决多星任务规划问题,与对比算法相比可以得到更优的规划结果.改进遗传算法有很好的工程应用前景.     

敏捷凝视卫星密集点目标聚类与最优观测规划

针对敏捷凝视卫星密集点目标观测规划问题,提出一种快速观测任务聚类策略和启发式蚁群优化算法.首先,针对敏捷凝视卫星视场范围特点,提出基于顶点度的团划分算法,解决密集点观测任务聚类问题,形成系列团观测目标,有效提高观测效率;其次,为得到最优团目标观测序列,考虑目标可见时间窗口约束以及卫星敏捷机动能力约束,构建基于多目标观测收益和姿态机动能耗的性能指标,实现能量高效的任务规划;再次,为克服传统蚁群算法易陷入局部极小值和收敛较慢的缺点,设计一种同时考虑目标点优先级、目标可见时间窗口、目标之间卫星姿态转换时间等因素的启发式蚁群算法;最后,选取大规模密集地面目标验证所提出算法的可行性和高效性.     

面向深空探测任务的实数遗传编码多星任务规划算法

针对面向深空探测任务的多星任务规划问题,综合考虑卫星对目标时间窗口、卫星姿态机动以及工作能耗等约束条件,建立了面向深空探测任务的多星任务规划问题模型,针对常规01编码在进行大规模卫星任务规划时,存在的编码长度过长等问题,提出了一种基于实数编码方式的遗传算法,以求解面向深空探测的多星任务规划问题.该算法采用了一种以目标为染色体的实数编码方式,相比传统的以时间窗口为染色体的01编码方式,缩短了染色体长度,可有效提高算法的求解效率.通过仿真算例分析,验证了基于实数编码的遗传算法对求解多星任务规划问题的正确性、合理性和有效性,并将其与基于传统01编码方式的遗传算法进行对比分析,其结果表明基于实数编码方式的遗传算法在寻优能力和计算速度上具有明显优势,这为求解面向深空探测任务的多星任务规划问题提供了一种新的思路和方法.     

多维动态规划在对地观测卫星调度中的应用

对地观测卫星调度问题是指如何利用有限卫星资源,在时间、空间等多约束条件下提高对地观测任务执行效率,是一个多约束条件下的目标满足问题.多维动态规划是针对多维约束任务将有限资源进行合理分配、高效调度的有效方法.它以缩短任务完成时间为目标,通过先求解一系列子问题,再处理子问题间关系求得问题最终解,避免了计算的复杂性,又满足了时效性要求.针对卫星对地观测任务约束变量多的特点,将多维动态规划应用到对地观测卫星调度问题中,是解决该问题在时效性要求条件下的有效方法,其可行性通过想定任务在文章中得到证明.     

面向观测任务的小卫星轨道仿真优化设计

研究对地观测小卫星轨道设计问题,是以区域覆盖性能为优化目标,对小卫星进行轨道设计。传统轨道设计方法要建立复杂的轨道动力学模型,优化过程计算量大、效率低,优化结果对不确定因素考虑不足。针对以上问题,结合遗传算法(GA)与灵敏度分析对面向区域观测任务的小卫星轨道进行优化设计。通过连接STK与VC实现覆盖性能计算,利用遗传算法实现小卫星轨道优化,采用灵敏度分析方法研究优化后的轨道参数变化对覆盖性能的影响程度。仿真结果表明优化后的小卫星轨道满足设计要求,能够达到覆盖性能最优。仿真结论,改进方法简单有效,优化效率高,可为实际工程中的小卫星轨道设计提供借鉴。     

基于实值编码GA的卫星巡天扫描方法

巡天扫描是天文卫星进行天体观测的基础,但是使用传统方法很难实现全天球覆盖,并且会遇到能源输出瓶颈。因此,本文针对天文卫星巡天扫描所遇到的问题,提出了使用基于实值编码的遗产算法(Real-codedGA)对卫星飞行任务进行智能规划的方法。该算法智能规划飞行任务,与仅依靠被动的分段式扫描方法相比,很好解决了能源输出的问题,还大大缩短了巡天扫描的时间。从仿真结果来看,该模型是十分有效的。     

基于协商对策的卫星任务规划冲突消解

主要对卫星任务规划过程中预处理阶段的目标冲突进行研究.为了更合理地确定卫星应用任务的时间窗口及个时间窗口的属性值,更有效地利用昂贵的卫星资源,首先对卫星任务规划预处理阶段的目标冲突进行了分析,给出了冲突的数学描述,针对冲突的特点提出了基于协商对策的冲突消解方法及协商流程,最后通过实例分析验证了方法在卫星任务规划中对目标冲突消解的有效性.     

基于对地观测需求分析的多星协同任务规划研究

由于对地观测的应用目标不同,各业务部门对遥感数据的需求存在差异。为了在多星协同任务规划中最大限度地满足用户提出的任务需求,构建了对地观测任务需求模型,整合了观测要素对于传感器的观测时限、空间分辨率和光谱需求,并基于改进层次分析法(AHP)评估了卫星资源对于任务需求的适宜度;进而,提出了以任务需求适宜度及任务优先级为优化子目标的约束满足模型,通过遗传禁忌混合算法实现了时空谱一体化的多星对地协同观测。以“一路”重点区域南海及周边地区为试验区域,结果表明,本文提出的方法取得的目标函数平均值及任务需求适宜度平均值较大,能够对成像点目标分配适宜观测的卫星资源。通过对比三种算法,本算法的运行时间较短,能够满足实际应用需求。     

基于分解优化的多星合成观测调度算法

某些卫星的侧摆性能较差, 必须进行合成观测以提高观测效率. 研究了多星联合对地观测中的任务合成观测调度问题. 提出了将原问题分解为任务分配与任务合成的分解优化思路. 任务分配为任务选择卫星资源及时间窗口; 任务合成则针对该分配方案,将分配到各卫星的任务按照轨道圈次分组, 分别进行最优合成. 采用蚁群优化算法(Ant colony optimization, ACO)求解任务分配问题, 通过自适应参数调整及信息素平滑策略, 实现全局搜索和快速收敛间的平衡.提出了基于动态规划的最优合成算法, 求解任务合成子问题,能够在多项式时间内求得最优合成方案. 依据分配方案的合成结果, 得到优化方案的特征信息, 反馈并引导蚁群优化算法对任务分配方案的搜索过程. 大规模测试算例验证了本文算法的效率.     

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.     

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.     

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.     

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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