多径环境下运载火箭高码率传输性能研究

针对运载火箭高码率情况下遥测信道的特点,对导致高码率遥测信道衰落重要原因之一的多径效应进行了深入研究,详细分析了运载火箭多径效应的典型特点,建立了PCM/PSK体制下的遥测信道数学模型,分析了多径环境下运载火箭PCM/PSK高码率传输性能,对于不同影响因素对遥测信道的影响进行了仿真,对多径环境下高码率传输误码率进行了分析,通过对运载火箭真实飞行过程数据分析,证明了数学模型的准确性。     

小型遥测数据采集存储装置设计

目前,运载火箭遥测系统多采用无线传输的方式,其信道具有一定带宽和容量限制。随着日渐增加的数据采集需求,原有遥测波道趋于饱和。为此,提出了一种小型遥测数据采集存储装置设计方案。该方案以FPGA作为核心控制模块,采用FLASH作为存储介质,可对待测信号进行采集、编帧以及存储。并采取了位置识别技术、分页存储技术、冗余设计等多种可靠性设计措施。该装置以低成本方式解决了现有遥测系统信道余量不足的问题,具有设计简便、可回收、体积小的特点,为后续运载火箭的设计改进提供了有效的数据支持,具备较高的通用性及可靠性。     

无线网在飞行试验遥测传输中的研究与应用

提出基于无线网技术来实现"飞行试验遥测数据实时远程传输"的新思路和技术方案,参照iNET标准对飞行试验遥测传输中的无线组网技术和数据安全进行研究,并以某大型运输机为飞行测试平台进行空地数据单向传输试验;试验结果表明,无线网最大传输距离达到202公里,最大传输位速率为2Mbps;在使用AES和MARS加密算法增强网络数据安全和解决无线网天线对活动目标实时跟踪问题后,无线网可用于飞行试验遥测数据传输。     

基于多链路聚合的无线实时视频传输系统

无线实时视频传输已成为当前通信领域发展的热点,但当前的无线通信技术提供的带宽尚无法满足高码率的实时视频传输的需求.针对这一问题,设计并开发一个基于多链路聚合技术的无线实时视频传输系统.该系统通过聚合多链路带宽,对各链路运用TFRC速率控制,有效地提高数据传输速率和稳定性,同时采用提早丢弃和关键帧优先发送等实时性优化策略,获得更好的视频传输质量.     

LoRa 无线数据传输模块的设计与实现

针对现有无线数据传输模块功耗高、传输距离短、可靠性低的缺陷,该文提出了一种新型的基于 LoRa 技术的无线数据传输模块。该模块以 SX1276 为射频芯片,采用低功耗微处理器 STM8L151为主芯片并移植了 Contiki 嵌入式操作系统。该文详细介绍了数据传输模块的硬件设计、软件设计并测 试了模块的主要性能。测试结果表明,该数据传输模块具有功耗低、传输距离远、可靠性高等优点,适用于无线抄表、环境监测等系统中。     

基于GPRS的水情测报系统的设计

针对目前我国水情测报系统的硬件可扩展性差、功能单一和数据传输方式不便的问题,采用ARM9处理器和GPRS技术,设计了一种新型的水情测报系统。该系统充分利用现有的GPRS技术实现现场的遥测站与数据中心之间的信号传输功能,有效地克服了以往系统中数据传输采用有线传输方式(如架线困难等)的多种缺陷;通过ARM9处理器代替单片机,克服了以往系统性能不强大、二次开发和升级不方便等缺点。实际应用表明,该系统可靠性高、可扩展、检测精确、维护方便,具有一定的实用性。     

基于单向无线网的飞行试验视频遥测传输技术

针对目前飞行试验视频遥测传输中遇到的遥测频带资源有限、传输视频路数少、数据保密性差等技术问题进行了分析,提出了采用单向无线网络进行数字视频遥测传输的技术优势,并对飞行试验单向无线网络数据传输中的网络通信协议进行了分析说明。提出采用H.264视频压缩技术进行飞行试验图像数据遥测传输的技术优势,针对在无线环境下视频传输需要解决的压缩数据编码问题,提出了采用分级编码技术和误码掩盖技术。结合飞行试验对研究结果进行了技术验证,并对试验方法和结果进行了说明。     

基于OFDM的井下遥测系统的FPGA实现

传统测井系统中,测井电缆上应用单载波调制技术进行数据传输,传输速率低,带宽受限,严重制约了测井系统尤其是成像测井系统的发展.OFDM(正交频分复用)技术信道利用率高,抗干扰能力强,应用OFDM技术能够较好地解决以上测井数据传输的问题.在分析了传统测井电缆传输的信道特性和正交频分复用技术原理的基础上,使用Altera 公司的DSP Builder软件设计了一种基于OFDM技术的井下数据遥测系统,并在Altera公司的Stratix EP1S25系列FPGA开发板上实现系统的仿真和验证.     

CEATEC JAPAN 2007，演示新技术

日前,USB应用者论坛(USB-IF)推出了USB 2.0的短距无线USB技术。它可以让PC和USB设备,比如打印机,扫描仪和移动硬盘进行高带宽的无线数据传输。使用UWB(超宽带技术)的无线USB设备可在10m范围内进行最高480Mbps速率的传输。数据传输在2～3m内达到峰值,在10m距离时传输率会降到     

用于煤矿设备信息化升级的无线数据传输节点

针对现有煤矿无线数据传输技术存在多径效应显著、传输距离短、耐噪特性较差和灵敏度较低等不足,以及煤炭行业大规模设备信息互联互通的需求,设计了用于煤矿设备信息化升级的无线数据传输节点。该节点通过LoRa-CSS技术建立设备间的可靠无线数据通道,利用基于IP核结构的可编程片上系统PSoC灵活适配各种煤矿设备的数据接口,并采用统一规格化数据格式进行指令和数据信息交互。电磁隔离特性测试结果表明,该节点具有较强的隔离特性,不受冲击电压影响,可以有效地将短时高强度浪涌信号降到设备容限值以下。实际应用结果表明,各无线数据传输节点与上位机和煤矿设备之间的数据通信效果较为理想,可以有效地构建由中心站到设备的稳定数据传输通道。     

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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