Technical efficiency and use of information and communication technology in Spanish firms

The literature concerned with the relationship between performance and information and communications technology (ICT) is usually focused on the ICT investments. This paper shows that it is the level of use of ICT within organisations, with preference as regards the expenses of ICT, which is responsible for the effect on performance. A general sample of 2255 Spanish companies has been used. Firms’ performance is measured as technical efficiency, which is determined by a data envelopment analysis (DEA), in which special attention is paid to the problem of the outliers. Finally, the analysis of the level of use of ICT is focused on a key area of the organisations, the supply chain, which affects the technical efficiency of the firms analysed. Results show that there is evidence of a positive effect of the use of ICT on technical efficiency. This effect is especially notable at intensive use levels in activities related to operations/manufacturing, purchasing or sales.     

煤矿安全监控系统升级改造方案设计与实现

针对现有煤矿安全监控系统存在的不足,提出从系统数据传输方式以及各类传感器配接方式入手,在最大程度兼容原监控系统的基础上设计改造方案。课题采用光纤传输技术和对配接传感器柔性好的数据采集分站作为系统数据的传输手段和数据采集中继站。在林南仓煤矿安全监控系统升级改造过程中的具体应用表明,升级改造方案正确、可行,从根本上解决了原系统存在的不足。     

空中异构战术网络IP通信架构及协议开销分析

空中异构战术无线网络由多种不同类型的无线数据链网络构成,IP通信技术可有效解决空中平台异构无线网络的互联互通问题。给出了空中异构战术无线网络模型,并根据不同类型的无线数据链网络特点,分析了端到端通信协议栈关系以及不同无线数据链网络间协议转换与适配方式。探讨了网络静态和动态IP地址分配方法以及网络的路由架构与寻址方式,提出了不同无线数据链网络间IP报文传输的打包方式。对传输的开销性能仿真对比分析表明,基于通用成帧协议的打包方式的协议开销性能较优。     

无线Ad Hoc网络中基于活跃节点数预测的时隙ALOHA算法

针对采用时隙ALOHA算法的无线Ad Hoc网络,考虑数据包到达的动态性与数据包传输的随机性,以最大化吞吐量为目标,同时满足数据队列稳定性,构建了关于接纳控制与竞争接入的随机优化问题。由于在时隙ALOHA算法中数据包传输的最优概率取决于无线Ad Hoc网络中数据队列非空的活跃节点数,提出了一种基于活跃节点数预测的时隙ALOHA算法。该算法要求无线Ad Hoc网络中的所有发送节点实时地侦听通信信道的忙闲状态,计算基于信道状态的活跃节点数条件期望,从而动态地预测无线Ad Hoc网络在不同时刻的活跃节点数,达到网络节点依据局部网络状态信息自适应地优化数据包传输概率的目的。仿真结果表明,所提算法能够有效估计无线Ad Hoc网络在每个时隙的活跃节点数,从而显著提升网络吞吐量并且降低数据包的平均排队时延。     

基于BWAS的无线传感器网络静态分簇路由算法

为提高路径搜索效率,避免动态分簇较多的能量消耗,提出了基于最优-最差蚂蚁系统(BWAS )的无线传感器 网络静态分簇路由算法。BWAS是对蚁群算法的改进,在路径搜寻过程中评价出最优最差蚂蚁 ,引入奖惩机制,加快了路径搜索速度。通过无线传感器网络静态分簇、簇内动态选举簇头 ,在簇头节点间运用BWAS算法搜寻从簇头节点到汇聚节点的多跳最优路径,能减少路径寻优 能量消耗,实现均衡能量管理,延长网络寿命,且具有较强的鲁棒性。通过与基于BWAS的 动态分簇和基于蚁群算法的动态分簇路由的仿真实验相比较,证实了本算法的有效性。     

无线传感器网络密钥管理研究进展

分析了当前无线传感器网络密钥管理协议设计中所存在的主要问题,在对具有代表性 的最新研究成果进行系统论述的基础上,全面分析了其利弊以及适应性问题。考虑到传感器 网络应用背景的细化和结构、功能的多元化,提出了今后的研究方向。     

整合营销传播理论在我国休闲业中的应用研究

由于休闲产业极易受其消费者无形的不可量化的因素的影响,当前休闲产业中所使用4Ps和4Cs等传统营销理论已难以适应休闲业急速发展的需求。本文借用整合营销传播理论的理念,从休闲产品合理定位、口径一致的品牌形象塑造,休闲产业社会营销等方面研究了休闲业整合营销传播策略的实施。     

Entering the mobile service market via mobile platforms: Qualcomm's BREW platform and Nokia's Preminet platform

The mobile telecommunication market has evolved from simple voice to multimedia services. In the past, the primary players in mobile services were local operators in different countries; international telecommunication vendors, such as Qualcomm and Nokia, were seldom involved in the mobile service market. In order to enter this market, Qualcomm and Nokia have separately introduced their mobile application platforms, called respectively BREW and Preminet. This paper examines how the two companies attempt to share the mobile service market through their mobile platforms and internationalized business models. This paper also analyzes their mobile platforms’ business models and their strategic implications.     

Singapore Technologies Electronics——Committed to Growth in China

Headquartered in Singapore, ST Electronics has almost 40 years of experience providing electronics, communications and ICT （information communications technologies） solutions to governments and commercial enterprises worldwide.     

结合全双工与协作干扰的无线网状网物理层安全策略

针对无线网状网中缺少窃听者先验知识不利场景中的安全连接问题,提出了一种结合全双工和协作干扰技术的物理层安全策略。利用全双工通信中的自干扰消除技术和协作干扰技术,提出的安全策略可有效劣化位于信息传播范围内包括潜伏在接收节点附近窃听者的接收性能。为保证信息的安全传输给出了协作干扰节点的选择方法,基于随机几何等数学方法导出了选定路径的安全连接概率表达式。性能分析和仿真结果表明,所提方法与仅基于全双工或协作干扰技术的方法相比,其安全性能有较大提升。