基于双信道结构的S-CDMA接入协议性能仿真分析

讨论了基于S-CDMA的HFC网上行信道的高效接入协议SAMA,提出了双信道接入机制的工作原理,通过计算机仿真对系统采用二进制指数后退算法(BEB)时的吞吐量及时延性能进行了研究与分析,得到一些有意义的结论。     

Review of carbon dioxide (CO2) based heating and cooling technologies: Past,present, and future outlook

Refrigerants bearing high global warming potential (GWP) and ozone depletion potential (ODP) were outlawed or facing time-beared permission under the Montreal (1987), Kyoto (1997) protocols, F-Gas law (2015), Paris Accord (2016), and recent Kigali Amendment to Montreal Protocol (2019). In order to modify followed by the paradigm shift of existing heating and cooling systems, American Society of Heating, Refrigeration, and Air-Conditioning Engineers (ASHRAE) envisaged natural and synthetic refrigerants (Synrefs) are under investigation globally. Carbon dioxide (CO₂) is a popular natural refrigerant (Natref) replacing Synrefs used in commercial heating, ventilation, air conditioning, and refrigeration (HVAC&R) systems globally. A rampant rise is observed in markets of Asia (Japan and China), North America (the United States and Canada), the Australian continent, and Africa (South Africa) by reaching 20 000 CO₂-stores around the globe. The European markets are leading the utilization of CO₂ in the heat pump, and refrigeration, CO₂ based markets estimate 14% of the total food retail stores (400 m²). Japan is the second leading market of CO₂ heat pump and refrigeration with more than 10 200 CO₂ condensing units. CO₂ transcritical systems have a share of more than 10% in only European market (large stores); however, their share is less than 10% of total stores in other major markets of the world. New pump and compressor-driven transcritical CO₂ systems integrate ejectors, condensers, and booster systems to reduce energy consumptions, enhance efficiency, efficacy, and coefficient of performance. This article reports a critical review of the CO₂ based heating, cooling, and refrigeration system and presents updated literature along with barriers and challenges on commercial use of Natref-based heating and cooling applications worldwide.     

宽带网络的“窄”问题

HFC网络一直被认为是广电在宽带网上挑战电信的有力武器。但从技术实践来看 ,HFC表现出来的并不完全是宽带的特性。所谓的HFC宽带更多意义上是从电缆的频带特性本身去考虑 ,而未从网络的整体和业务的实现去考虑。从HFC网络的拓扑结构、网络环境、业务传递、网络分配等方面分析了限制HFC网络在发展宽带业务时存在的技术问题 ,并给出了发挥HFC网络优势的建议。     

基于HFC网的无线市话组网方案

介绍无线市话室内信号覆盖的实现方法,阐述基于HFC网络的无线市话组网方案及其基本工作原理。     

HFC 134a as a substitute refrigerant for CFC 12

In response to international protocol agreements and national regulatory actions promoted by the increasing concern for ozone depletion and the greenhouse effect, HFC 134a has emerged as a leading candidate for CFC 12 substitution in automotive air conditioners, centrifugal chillers and residential refrigerators and freezers. This Paper discusses compressor and refrigeration system requirements and information gaps for HFC 134a application as a CFC 12 substitute.     

HFC宽带网网管系统的开发

介绍如何利用SNMP自主开发HFC宽带网网管系统，对CMTS、Cable Modem以及其他的网络设备、服务器的重要参数进行实时监测管理，确保HFC宽带网业务的稳定运营。     

新型光链路设计在HFC网络中的应用

以往的有线电视HFC光链路设计中,一般的步骤是由下而上,这种设计可以让光发射机的光功率得到最大利用,但缺点也很明显.而采用新型的由上而下的设计:先选定光发射机和光分路器,再计算出各光分路器的传输距离,再将距离相近且地理位置相近的光点接到同一个光分路器,有利于维护和管理,扩展更容易,可组成N 1冗余备份.     

两种宽带接入方式HFC与ADSL的比较

宽带接入技术发展迅速，HFC和ADSL作为目前非常具有竞争力的两种宽带接入技术，有他们的共同点，即利用现有的网络资源，同时，他们又有着各自的特点，本文先对他们作了简要介绍，然后是试从带宽、速率，安全性，可靠性等几个方面对他们进行了比较。     

The Video-On-Demand Trial in Taiwan: A Partially DAVIC Compliant System

This paper reviews the Video-On-Demand technical trial conducted by Computer & Communication Research Laboratories in Taiwan. This trial is one of the key realization of Taiwan's National Information Infrastructure. The primary goal is to provide a testbed and platform for new product development, interoperability test, and interactive multimedia applications. It also explores the technical difficulties from which experiences can be gained for future large scale deployment. Open system and end-to-end system are the most important requirements of the VOD system in this trial. Open system allows a variety of video servers and set-top boxes to be integrated into the system while end-to-end system requires system integration know-how.An overview of the Video-On-Demand system is provided in this paper. The architecture of the video server, delivery network and set-top box will be examined. The system integration issues including content preparation will also be discussed.     

氟里昂替代品——HFC—134a的研制简述

本文简述制备致冷剂替代品－－HFC－134a的催化剂及工艺的几个核心问题，并提出催化剂的发展方向。