Response Time in Data Broadcast Systems: Mean,Variance and Tradeoff

Data broadcast has been suggested as a promising method of information dissemination [2,33]. In such an environment, the information server cannot afford to serve the requests from a large population of users individually. Instead, the server uses a broadcast channel to deliver information to all users. A single transmission of a data item satisfies all pending requests for that item. The response time of a request depends on the broadcast time of the desired data item, which is scheduled by the server according to the overall demands for various data items. Therefore, the response time may vary in a large range. We argue that, in addition to mean response time, the variance of response time should also be taken into account by the broadcast scheduler. In this paper, we address the issue of variance optimization in regard to response time. Building on our previous research on mean response time optimization, we propose an algorithm which can minimize the variance of response time. Furthermore, we evaluate an algorithm that facilitates a tradeoff between the mean and variance of response time. Numerical examples that illustrate the performance of our algorithms are also presented.     

基于TTS语音模块的人体感知电子解说系统设计

介绍一种基于单片机和科大讯飞TTS语音模块的人体感知电子解说系统,可用于旅游景点或相关展品的智能解说。利用热释电红外传感器获取人体接近信息,配合TTS语音模块完成对相关景点或展品的自动解说与信息播报功能。文中给出了系统的详细硬件设计方案及主要软件流程图。经测试,该系统稳定地实现了当人体接近特定地点时的语音信息自动播报功能,可给同类装置的设计及应用提供借鉴。     

从法律角度看县长直播销售农产品新思路

科技发展背景下直播带货行业愈加深入人心,消费者足不出户就能买到心仪产品。线上直播销售农副产品能提升农村经济水平,实现产业振兴,支持我国乡村建设。但是由于行业整体起步较晚的原因,其依然存在农产品质量安全难以保证、平台发布信息不实和消费者维权途径不明确等问题。县长直播销售农产品模式作为新兴销售模式不应当仅是权宜之计,而应着力在实践中优化使之成为长久之计。本文围绕县长直播销售农产品展开,认可其弥补网红直播不足方面的优势,指出尚且存在的不足。通过完善对供应商履行义务的监督,加强对消费者合法权益的保障,规范市场秩序,整治市场乱象,使其健康平稳发展,为社会主义新农村的建设作出巨大贡献。     

动态电压恢复器的改进最小能量控制

动态电压恢复器(DVR)被用来补偿电压凹陷,它的补偿能力主要决定于最大电压注入能力和存储的能量。为了使DVR的有功输出PDVR最小化,同时减轻对负荷的扰动,文中采用了负荷端电压相量角α按恒定步长△α缓慢变化的控制策略,根据对电压凹陷期间DVR装置的PDVR-α曲线的分析,提出了通过判断特定量的符号决定补偿方向的DVR的改进最小能量补偿控制方式,比直接求最优α角的计算量小,并且分析了考虑DVR注入电压限值的改进最小能量控制。仿真结果证明了该方法比传统控制方式更能有效地减少DVR的有功输出,比直接计算最优α角的最小能量控制方式在凹陷开始和结束的暂态过程中使负荷端电压的变化更加平稳,对敏感负荷造成的扰动更小。     

Convergence of Broadcast and New Telecom Networks

The demand of the new telecom industry for cost efficient provision of mobile multimedia services is faced with the reality of scarce radio resources. The requirement of spectrum efficiency has driven the development of various digital radio technologies that have been optimized for specific services, namely for broadcast or for mobile communication. However, existing and emerging multimedia services exhibit challenging requirements in terms of asymmetry, interactivity, real-time, and multicast communication. This paper describes an IP based multi-radio infrastructure that enables the co-operation of existing radio networks to combine their capabilities to ensure a spectrum efficient provision of high-quality mobile multimedia services. Further the need for a dynamic allocation of spectrum to radio services is motivated. The basic functionality and the architecture of a multi-radio system is outlined, with a special emphasis on the cooperation between different radio systems. Further an evolution path for the convergence of broadcast and new telecom is desribed, starting from today's systems and leading to a fully coordinated system.     

基于DVB-C的数据广播系统的设计与实现

针对传统有线电视网络,我们设计了一套基于DVB－C协议的数据单向广播系统。本文详细讲座了该系统的设计思想、协议体系,并简要介绍了前端和用户端的实现,本文系统能够以低廉的成本,可靠的性能为广大有线电视用户提供内容丰富的数据广播服务。     

RF LDMOS功率晶体管及其应用

论述了 RF LDMOS功率晶体管的基本结构和特点。从与双极晶体管相比较的角度 ,讨论了这种器件的优异性能。对其发展动态和应用情况作了介绍。     

Indexing Techniques for Power Management in Multi-Attribute Data Broadcast

In this paper, we discuss the power conservative indexing techniques for managing multi-attribute data broadcast on wireless channels. These indexing techniques, namely, index tree, signature and hybrid, aim at improving the battery power consumption of mobile clients. By taking into account the broadcast management factors such as clustering and scheduling, these three indexing schemes may significantly reduce tune-in time while maintaining a reasonable access time. Cost models for single and multi-attribute query processing are developed. Our performance evaluation shows that the signature and hybrid methods are superior to the index tree method.     

电视台制播一体网建设初探

梅河口电视台20010年6月建立了非线性编辑制作网络和硬盘自动播出系统,本文就中小型电视台制播一体网建设中所涉及到的关于设计思路、设备选型以及技术问题做一个简要的回顾和总结。     

非编网络化制播系统的设计与实现

根据浙江民生休闲频道非编网络制播系统的特点,介绍该系统的总体业务流程、体系结构、重要设备组成、网络安全管理,对系统关键技术及创新设计进行了详细的阐述,并对该系统今后的发展前景作了展望。