电力系统内基于NTP协议的对时网络异常情况处理研究

电力系统要求各设备具有高度的时间同步性,因此对时系统的可靠运行是电力系统运行的重要保障。本文对基于NTP协议的网络对时方式的原理进行了分析研究,根据NTP协议的对时原理和网络结构,对运行中的换流站内出现的对时系统异常情况进行了分析,提出了增加对时网络层数来减轻GPS主机负荷的解决方案。本研究对提高换流站对时系统稳定,保证安全稳定运行有着非常重要的意义。     

三网融合传播学解释110问（一）

三网融合不仅是技术问题、体制问题,也是社会问题。无论广电还是电信,在三网融合过程中,都涉及到对三网融合的内涵：对运营商自身、对彼此关系及与公众的关系、对内部群体和行业、对用户需求、对媒介和媒体的应用和开发、对彼此文化和社会文化等问题的认识、理鳃和调整。没有对国家三网融合战略的理解,没有对广电和电信行业的理解,     

影响双光子非相干耦合孤子对强度包络的参量理论分析

采用数值方法对双光子光折变介质中非相干耦合亮-暗屏蔽光伏孤子对的耦合方程进行了求解。理论分析了启动光,分压系数和晶体温度对孤子对强度包络的影响。结果表明：孤子对包络宽度随启动光的增大而变大;随分压系数的增大而变小;晶体的温度增大,孤子对的宽度变大而峰值光强变小,晶体温度减小,孤子对的宽度变小而峰值变大。这些结果对双光子非相干耦合亮-暗空间孤子对的工程实践有一定参考价值。     

对CDMA系统的干扰方法分析

对CDMA下行信道和上行信道进行干扰,实现干扰CDMA系统的目的.重点分析了对CDMA下行信道的干扰方法和对CDMA上行信道的干扰方法,包括对下行信道的非相干压制式干扰、对下行公共信道的相干伪码扩频干扰和基于伪基站的欺骗式干扰,以及对上行信道非相干式压制式干扰和对接入信道的欺骗式干扰,归纳得到各种干扰方法的原理、优缺点、对侦察的需求及其适用范围.     

半导体制冷器“无限级联”温差电对工作参数的理论分析

在普通温差电对的ｐ型和ｎ型电臂之间淀积一层厚度适当的银膜实现短接,可在单级温差电对中形成类似多级半导体制冷器的无限级微温差电对串联,从而提高电对的制冷量和制冷温差．实验证明,这种“无限级联”温差电对的最大制冷温差可提高到普通电对的１．５～３倍．本文通过合理的简化,求解导热微分方程,给出“无限级联”温差电对的理论工作参数,并且给出焦耳热在电对冷端和热端的分配情况,从而在理论上对这种电对结构的优越性作出解释．     

数控机床常用对刀方法及误差分析

数控加工中经常涉及到对刀问题,对其处理的好坏直接影响到数控加工零件的精度,还会影响数控机床的操作。本文对数控机床对刀的基本原理、常用的对刀方法以及在对刀过程中容易出现的误差问题进行了探讨。     

用户是市场主体 质量是竞争核心

从市场经济特点出发,明确指出企业必须对产品负责、对用户负责;分析了当前存在的对科研成果、对设计图纸负责高于对产品负责的主要表现;并针对存在的问题提出了措施建议。     

基于eviews软件度量石油价格对碳排放的影响

采用计量经济学常用软件eviews度量了石油价格对碳排放量的影响.石油价格对碳排放的影响体现在两方面,一是石油价格作为影响因子对碳排放的直接影响;二是石油价格通过作用碳价对碳排放的间接影响.采用协整检验、状态空间模型分别考察了石油价格对碳排放的直接和间接影响.研究发现,石油价格对碳排放的直接影响效果不佳且具有一定滞后;当碳市场有效,石油价格对碳价的影响超过0.118时,石油价格对碳排放的间接影响力会高于直接影响力.     

被动传感器组网对干扰源的聚类定位算法

为了提高对机动干扰源的定位精度,提出一种基于数据质量分析思想的多地面被动传感器组网聚类定位算法。考虑到各种客观因素和主观操作对量测的影响,该算法首先对各量测在二维空间中产生的目标估计位置点进行数据质量度量,从而确定该量测对干扰源定位结果的贡献;引入聚类思想完成对高质量位置数据的实时筛选,并由该数据实现对干扰目标的定位。通过和MMSE算法相比较,基于数据质量分析的聚类定位算法可有效消除低质量量测对定位结果的不利影响,从而提高了对干扰源的定位精度。同时对传感器布站形式的研究表明,只要对网内各传感器进行合理配置与管理,该算法即可有效降低系统偏差等不利因素对定位系统的影响。     

PC插卡式短波接收机WR-G303的开发应用

基于VisualBasic6.0编程环境,对PC插卡式短波接收机WR-G303进行了开发应用,实现了对短波频带内无线信号的监测接收。详细论述了CPU对G303卡、声卡的控制及声卡对中频信号的采样过程和CPU对数字信号的分析;最后对其进一步开发做出了展望。     

空间互联网技术发展现状及趋势

空间互联网技术是人类进行航天测控、导航定位、远洋航行等空间应用的基础支撑,是实现全球互联互通的关键手段。首先介绍了空间互联网的概念及内涵、组成及结构、特点及优势等相关基础知识,接着总结了空间互联网的关键技术,然后阐述了空间互联网的发展现状和面临的问题,最后结合互联网技术发展趋势和航天应用的发展要求,对空间互联网技术的发展趋势进行了展望和预测。     

高速光纤综合通信网络平台研究

现代通信网络应能满足各种通信业务和通信容量日益发展的需求,实现话音、数据、视频、IP等业务的一体化综合交换和传输。在比较TDM、IP和ATM三种协议的基础上,提出"采用内置RPR和MPLS功能的MSTP平台"建设光纤综合通信网络平台的实现方法。MSTP采用SDH的数据帧结构,保持了SDH标准光接口、灵活分插低速信号、自愈环保护和功能强大的网管等优点,可对TDM、IP和ATM协议进行优化传输。     

带SIR结构新型多枝节加载双频滤波器

本文在传统λ/4阶梯阻抗谐振器的基础上,提出了一种新型的宽带双频滤波器改进设计方案。改进的滤波器增加了传输零点,此传输零点能有效的改进通带的选择性和阻带特性,且上阻带带宽很宽。结构简单,在传统类似滤波器同谐振频率基础上有效缩小了尺寸,并且设计的滤波器通带的中心频率和带宽是完全独立可控,方便我们应用到实际。工作在4.1 GHz和6 GHz两个频段,3 dB相对带宽分别为7.2%和2.2%,实测和仿真吻合良好。     

Towards Mobile Ubiquitous Service Environment

In this article we present a perspective on future vision of mobile communications and services which is referred to as Mobile Ubiquitous Service Environment (MUSE). Based on analysis of wireless communications and services, we exploit a conceptual model for MUSE via a top-down approach. The conceptual model consists of three major elements: Terminal Service Environment (TSE), Network Service Environment (NSE) and User Identity (UID). The concept of Always the Best Experience (ABE) is addressed as the hinge in design and development such that the user-centric services could be provided automatically and intelligently in the future diverse wireless world Based on these, we further discuss the issues on design and implementation of architecture of future wireless communication system. Requirements for architecture brought by the new features of MUSE are listed. Moreover, we also address several tradeoffs that should be taken into consideration in design. Finally, the deployment challenges for MUSE, such as reflectiveness of system, security and privacy, as well as peer-to-peer AAA are predicted.Ji Yang received PhD degree on Circuit and System, Bachelor degree on Telecommunication Engineering from Beijing University of Posts and Telecommunications (BUPT) in 2002 and 1993 respectively. Currently, he is an associate professor of BUPT, chief technical supervisor of Wireless Technology Innovation Institute, and vice manager of MTlab of Sino-Germany Software Institute. He leads the research on service and application in Future Forum in China. He also made much contribution to the China Communication Standardization Association (CCSA), including the vision of future Mobile Ubiquitous Service Environment, architecture of future B3G mobile terminal, etc. His research interests include architecture design for mobile ubiquitous networks, theory of self-organization, etc.Zhang Ping is now the professor of Beijing University of Posts and Telecommunications and director of Wireless Technology Innovation (WTI) Institute, BUPT. He has also served on the senior member of C3G Group, China MOST 863 future mobile communication FuTURE project, vice-chairman of China FuTURE Forum, and member of Vision Committee of World Wireless Research Forum(WWRF), he was vice chair of WWRF in 2005. He is also invited as the consultants for many domestic and oversea communication companies. He is very active on the international research activity on Beyond 3G area. He also participated in several European projects such as E2R and MOCCA. Until now, he has published 6 books, around 400 publications in journals and conferences in the area of telecommunications. His main research interests are theory and applications in wireless communication area. He was awarded by government, city of Beijing and Ministry of Information Industry several times for his great contribution to the industry and research activity in China.Hu Zheng is a PH.D candidate in mobile communications engineering in Wireless Technology Innovation Institute (WTI) at Beijing University of Posts and Telecommunications (BUPT). He received B.S degree from Nanjing University of Posts and Telecommunications in 2002, majoring in computer communications engineering. He currently works on serivce aspects of mobile ubiquitous communication system with focus on design and performance evaluation of interaction protocols and services in self-organized service environment.Wang Xu received the B.Tech. degree in electronic engineering from Beijing Polytechnic University (now named as Beijing University of Technology), Beijing, China, in 2002. Now he is working for his Ph.D. degree in Wireless Technology Innovation (WTI) Institute, Beijing University of Posts and Telecommunications (BUPT). His current interests include wireless communications in personal area, ad hoc networks and peer-to-peer system.Li Yinong received the BS degree major in Telecommunication Engineering in 1993 from Beijing University of Posts and Telecommunications, the MS degree and PhD degree major in Telecommunication and Electronic System in 1995 and 2003 from the Beijing University of Posts and Telecommunications. He is currently a lecture of STE (School of Telecommunication Engineering) of BUPT. His main research interests include service modeling, service composition approach, and intelligent service. In BUPT, he has given several lectures to both graduate and undergraduate students such as Information Theory, Speech Recognition, Pattern Recognition and Artificial Intelligence.     

Theoretical analysis of the relationship between the Brillouin gain coefficient and the strain in the optical-fiber sensors

The relation between the power of the Brillouin signal and the strain is one of the bases of the distributed fiber sensors of temperature and strain. The coefficient of the Bfillouin gain can be changed by the temperature and the strain that will affect the power of the Brillouin scattering. The relation between the change of the Brillouin gain coefficient and the strain is thought to be linear by many researchers. However, it is not always linear based on the theoretical analysis and numerical simulation. Therefore, errors will be caused if the relation between the change of the Brillouin gain coefficient and the strain is regarded as to be linear approximately for measuring the temperature and the strain. For this reason, the influence of the parameters on the Brillouin gain coefficient is proposed through theoretical analysis and numerical simulation.     

Rural broadband: Gaps,maps and challenges

This paper examines challenges to evidence-based decision-making in the design and implementation of rural broadband investment programs. Our focus is on Canada, and the apparent need for further intra-rural broadband research and better data and mapping for informing public investment decisions, but similar challenges are evident in the international literature. Based on proprietary telecommunication provider datasets, the Canadian Radio-television and Telecommunication Commission (CRTC) estimates that broadband services with advertised speeds that meet its basic universal service targets (50 Mbps download and 10 Mbps upload) are available to 87.4 percent of households in Canada. In rural areas however, services that meet CRTC’s speed targets are available to 45.6 percent of households. Moreover, effective speeds and service quality levels that suppliers deliver and users experience tend to fall well below the government’s aspirational targets. In response to demand for better broadband, a variety of initiatives are directing public investment to the deployment of regional and rural broadband networks, which are typically owned and operated by private companies. There remains a serious lack of relevant data and its effective use in creating rural broadband strategies and managing public investment projects. Evidence from the literature suggest that this affects the degree and quality of geo-spatial and econometric analysis that results in a limited empirical basis to allocate scarce public investments, aggregate demand of consumers/communities, and assess the outcomes of rural broadband initiatives ex post. This paper provides a historical overview of rural broadband development in Canada and questions if the body of knowledge to inform public investment initiatives has grown sufficiently to ensure their effectiveness and sustainability. With a regional case from southwestern Ontario, Canada, we discuss the findings of the literature review, characterize the broadband data challenge, and discuss the importance of proprietary provider data cross-referenced with Internet user experience data.     

1xEV-DO与HSPA无线接入技术对比

HSPA与1xEV-DO具有相同的目的和基本相同的技术实现手段,本文主要对1xEV-DO与HSDPA从标准演进、关键技术、网络结构与性能、商用情况等方面进行了全面的对比分析。     

Graphene‐Based Nanomaterials: Synthesis,Properties, and Optical and Optoelectronic Applications

Graphene, a two‐dimensional, single‐atom‐thick carbon crystal arranged in a honeycomb lattice, shows extraordinary electronic, mechanical, thermal, optical, and optoelectronic properties, and has great potential in next‐generation electronics, optics, and optoelectronics. Graphene and graphene‐based nanomaterials have witnessed a very fast development of both fundamental and practical aspects in optics and optoelectronics since 2008. In this Feature Article, the synthesis techniques and main electronic and optical properties of graphene‐based nanomaterials are introduced with a comprehensive view. Recent progress of graphene‐based nanomaterials in optical and optoelectronic applications is then reviewed, including transparent conductive electrodes, photodetectors and phototransistors, photovoltaics and light emitting devices, saturable absorbers for ultrafast lasers, and biological and photocatalytic applications. In the final section, perspectives are given and future challenges in optical and optoelectronic applications of graphene‐based nanomaterials are addressed.     

开放和分解OTN网络技术研究和分析

如何构建开放和分解的OTN网络,以实现跨厂家设备的混合组网和光层互连,一直是运营商和设备商追求的目标,ONF和LFN这两大开源项目组织分别基于各自的SDN控制平台——ONOS和OpenDayLight,给出了自己的解决方案——ODTN+TAPI和OpenROADM+TPCE,本文对这两种技术方案作了深入的研究和分析,比较了这两种技术的异同点,并对当前这两种技术的发展和应用前景作了简要的说明。     

基于AdaBoost的音乐情绪分类

随着流媒体应用的蓬勃兴起,音频信号的自动分类开始成为工程与学术关注的热点之一。根据音乐信号对乐曲表现的情绪进行分类,由于涉及音乐信号的社会属性和自然属性的综合表征与模糊分类,因此处理方法相应需要在各种传统表征与分类方法的基础上进行机制筛选与架构优化。该文探讨了在AdaBoost算法,K-L变换和GMM模型的基础上构造弱分类器的方法,采用多层分类器结构,成功地实现了对音乐信号进行情绪分类。初步的实验对163首歌曲进行平静(Calm),悲伤(Sad),激动(Exciting)以及愉悦(Pleasant)4种类别的分类,训练集和测试集的分类准确率分别达到97.5%和93.9%,展示了这种方法的可行性和进一步发展的潜在价值。