Satellites for communications and broadcasting: The evolving european market

The paper traces the development of the market for communications and direct broadcasting satellites in Europe, since the original specification of the European Communications Satellite (ECS) in 1977. It reviews the experiments undertaken on the Orbital Test Satellite (OTS) and the way in which demonstrations with this satellite have influenced the way in which ECS is being developed. It continues by considering the impact of television on the market, first cable television and its distribution requirements, then direct broadcasting by satellite, where the introduction of homes into the customer configuration will bring with it programme content as a salient feature in market development. Finally it speculates on the possibilities for the future, both in terms of the effect of new and higher frequencies on satellite communications systems, and the possible effects that interaction from small earth-stations could have on satellite design.     

双星快速定位系统及提高定位精度的途径

本文扼要地介绍了双星快速定位系统的组成、功能、工作原理以及双星定位演示系统及演示试验的概况。最后对提高用户定位精度的途径进行了一些探索。     

星型子网的NoC映射研究

处理单元映射是NoC设计的重要环节,其实施结果对NoC通信功耗及QoS约束的满足均起着决定性的作用。本文选取的NoC拓扑结构为星型子网的片上网路结构SSBM NoC（Star-Subnet-Based-Mesh NoC）。为保证系统实时性和低能耗,文中建立了延时约束下功耗最小的NoC映射模型,提出了一种基于改进粒子群算法的优化方法。针对NoC映射的特点,在粒子群算法中引入了交换子和交换序算子,确保了映射的有效性。实验结果表明,文中算法在满足延时约束下,降低NoC通讯功耗20%以上,证明该算法优化效果显著。     

基于电力线载波低压电缆防盗方案

电力电缆被盗对电力系统造成了严重的安全威胁和财产损失。本文设计了一套基于电力线载波通信的电缆防盗报警方案。载波通信通过扩频调制解调电路来实现。防盗报警系统由报警主站和线路探测终端组成,报警主站根据与各线路探测终端的载波通信成败或者所接收的终端状态信息数据来判断是否发生电力电缆被盗等异常信息,当异常状态出现时,报警主站通过GSM网络拨打电话和短信息发送向远端值班室人员传送警情。同时本文介绍了如何克服电力线上的噪声对载波的干扰,以及如何对断点进行定位的方案。     

A review of digital twin in product design and development

In the era of digitalization, there are many emerging technologies, such as the Internet of Things (IoT), Digital Twin (DT), Cloud Computing and Artificial Intelligence (AI), which are quickly developped and used in product design and development. Among those technologies, DT is one promising technology which has been widely used in different industries, especially manufacturing, to monitor the performance, optimize the progresses, simulate the results and predict the potential errors. DT also plays various roles within the whole product lifecycle from design, manufacturing, delivery, use and end-of-life. With the growing demands of individualized products and implementation of Industry 4.0, DT can provide an effective solution for future product design, development and innovation. This paper aims to figure out the current states of DT research focusing on product design and development through summarizing typical industrial cases. Challenges and potential applications of DT in product design and development are also discussed to inspire future studies.     

CIMS实时通信网络体系结构的研究

ＣＩＭＳ环境下的实时控制系统通常需要特定的网络体系结构以支持紧要时间应用。本文给出了一种实时局域网（ＲＬＡＮ）体系结构，并详细论述了其ＬＬＣ层提供的实时面向连接服务及几种实时ＭＡＣ协议。     

5G网络中通信运营商的安全布局分析

针对5G网络的逐步商业化推进环境下通信运营商面对的需求、业务和挑战到通信运营商的网络安全责任。基于对网络安全构架和业务特征化的安全布局进行分析,重点对5G网络业务切片下的网络安全管理进行了安全策略差异化分析,着重提出了网络安全布局和策略建议。     

基于时间误差的循环神经网络参数压缩

循环神经网络被广泛应用于各种序列数据处理任务中,如机器翻译、语音识别、图像标注等。基于循环神经网络的语言模型通常包含大量的参数,这一点在一定程度上限制了模型在移动设备或嵌入式设备上的使用。在低秩重构压缩的基础上,增加时间误差重构函数,并采用长短时记忆网络中的输入激活机制,提出了一种基于时间误差的低秩重构压缩方法。多个数据集上的数值实验表明,该方法具有较好的压缩效果。     

Consensus Based Least Squares Estimation for Single-Integrator Multi-Agent Systems with a Time-Varying Reference State

This paper discusses consensus tracking of single-integrator multi-agent systems with a time varying reference state based on the least squares estimation theory to deal with the case of communications disturbance. Since none of the followers can communicate with the leader within the accepted time due to communications disturbance, least squares estimation is applied for online estimation of the time varying reference state and reducing the tracking errors occurred due to communications disturbance. A theoretical proof is provided under some assumptions while the necessary and sufficient conditions are demonstrated for which consensus is reached on the time-varying reference state in case of communications disturbance. Finally, a Matlab example is given to validate the effectiveness of the proposed approach.     

现代水声通信技术的发展及应用

本文介绍了通信技术中现代水声通信的历史,分析了水声通信发展的关键技术,讨论了水声信道的特点,并简要分析了水声通信技术的现状,对水声通信系统的特点作了一定的比较,最后对未来的水声通信技术作了预测。