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1.
《IT时代周刊》2007,(19):37
冷链必须是全程的 实时的 作为国内拥有雄厚实力的进口疫苗分销商,泰凌医药集团旗下的海南泰凌生物制品有限公司肩负着一些垒球知名厂商的疫苗产品在中国的分销和冷链配送服务.每当看到专用的冷藏车将一箱箱的疫苗运送到仓库的时候,泰凌人的心中感受到更多的是责任.  相似文献   

2.
近两个月来,本刊网站的论坛里又不太安静。有个叫"高清迷"的香港网友遭到了广东一些网友的质疑。彼此论战的焦点大部分在说香港电视好看或不好看。"高清迷"网友说大陆电视越来越好,水平已经超过香港的电视节目。广东网友们则是缅怀香港电视的辉煌历史。这原本是简单的我说你好你说我好,互相捧场的事情,但是网络的奇妙性在于事情并没有朝积极的方向发展,其结果是吵架不可避免的发生了。外来的和尚是不是会念经,我们先不去管他。重要的是我们要弄清楚自己是怎么回事。本文,是专业电视人对我国各省卫视台做的调查评估。让我们了解一下我国的电视台的现状吧。  相似文献   

3.
ADSL服务     
现在使用ADSL上宽带网的用户是越来越多了,对ADSL设备的维护也成了一个不容忽视的问题.只有维护保养好它,不但让你的"宽带之旅"省心又省力,还能延长其寿命.ADSL的维护可分为软件和硬件两个方面来分析,软件主要是PPPOE协议的问题,和计算机本身的气操作系统,和网卡方面的事情.硬件主要是局端的节点设备,和用户端猫的问题.还有通信的线路等一些因素.  相似文献   

4.
雷鸣 《IT时代周刊》2005,(11):18-27
热闹了多年,也翻炒了多年,但中国的3G进程到现在仍处于一片迷茫当中。是谁卡住了中国3G进程的脖子?毫无疑问,部分跨国公司设置的高昂专利费是阻碍中国3G步伐前进的一块巨石。2005年4月23日,信息产业部副部长奚国华在参加2005年博鳌亚洲论坛年会时公开表示,跨国公司收取过高3G专利费这一行为导致3G进程缓慢,并呼吁这些跨国公司降低专利费用。奚国华副部长的一席话成为“3G专利谈判受阻”事件的最好注解。据悉,在这场关于WCDMA的专利费谈判过程中,高通公司在其他专利拥有者摩托罗拉、诺基亚、爱立信等同意降低专利费的情况下,谈判最终因高通公司的拒绝接受而搁浅。作为世界最大的通讯市场,中国通讯业的每一步进展都充满着坎坷;作为世界知名的通讯公司,高通公司已演变成CDMA生态圈里的巨鳄,其拥有的1400多项专利足以让人望而却步。这家出售知识产权的公司真的是阻拦中国3G进程的巨石吗?也许,从另一侧面观察,更能了解高通的真实面目。雷鸣先生是高通公司大中华区前总裁,他见证了高通的成长,更熟悉高通的一切事务。到底谁是卡住中国3G脖子的幕后主角?现在,经过雷鸣先生的观察和反思,一件件鲜为人知的事终于曝光在读者的面前。相信看完此文披露的诸多内幕,答案就在你的心中!  相似文献   

5.
高频电磁辐射作用于人体后,一部分被反射,一部分会被人体吸收,被吸收的电磁能量使人体组织内的分子和电介质的偶极子产生振动,媒质的磨擦把动能变为热能,从而导致使人体产生温升的热效应.电磁辐射的功率、频率、波形、环境温度以及人体被照射的部位等因素影响热效应伤害的深度和程度.  相似文献   

6.
汶川5·12大地震,这场突如其来的灾难让大半个中国遭受重创.我们每天被迫面对无数死伤的同胞和几乎被夷为平地的城市和村镇,悲痛欲绝的同时却又让我们达到空前的团结,5·12是悲惨的,也是悲壮的.我们感受到了全方位的力量,灾民、政府、同胞……尤其媒体的表现让所有人震撼,电视、广播、网络成为灾难的发言人,成为灾区与整个中国乃至全世界连接的信息生命线.  相似文献   

7.
通信技术的进步推动了电信市场的发展,当前ADSL用户的需求旺盛,给北京通信的发展创造了有利的商机,同时也给我们带来一些急需解决的新课题,如何利用北京通信的传统优势克服发展瓶颈、充分满足ADSL市场的需要.本文首先分析了目前阻碍ADSL发展的原因,结合北京通信的实际情况提出了利用语音分配点安装OSLAM设备以解决瓶颈问题的新思路,然后介绍了新研制的多功能有源交接箱的设计特点和应用前景及用户纤光缆交换点的建立储备.最后对采用本文的思路和应用新设备的投资、回报等进行了经济性分析,从而系统完整地提出了一套可行的解决方案和相关实施建议.  相似文献   

8.
李士超  邱玲 《信号处理》2011,27(3):357-361
作为下一代无线通信系统的关键技术,协作多点传输能够有效降低相邻小区之间的干扰,提高小区边缘用户的频谱效率。在频分双工系统中,其性能依赖于各基站获取的基于有线反馈的信道状态信息的准确性。然而,所有协作基站都获得相同精确程度的信道状态信息会导致用户终端的反馈开销随着协作基站数线性增长。本文关注于如何在性能增益和反馈开销之间取得折中,提出一种适用于协作多点联合传输的自适应预编码矩阵索引反馈方法。用户终端根据不同协作基站下行链路的信道质量指示的相对大小,自适应的用不同的比特数表示不同强度链路的预编码矩阵索引,即用较多比特数表示具有较高信道质量指示的预编码矩阵索引,反之亦然。仿真结果表明,与传统反馈方案相比,该方法在几乎不牺牲频谱效率的前提下,大幅降低了反馈开销。   相似文献   

9.
介绍了一种利用厂商发布的漏洞补丁信息分析漏洞细节的方法.该方法的关键是利用PE文件在安装补丁前后的不同,综合运用模式比较的方法建立模式匹配图,从而分析处漏洞的细节以及问题代码.该方法函数比较算法的清晰,以及模式图的差异的直观性,很容易分析出问题代码的位置,从而有效地提高了漏洞分析的成功率.  相似文献   

10.
追日     
去年10月一个温暖的早晨,在澳大利亚内陆深处,14名麻省理工学院的学生和校友上午6点就爬出了他们的睡袋,准备车队,进行又一天的艰苦驾驶,在护卫队的护送下,他们驶过一段平坦、笔直、炎热、灰尘弥漫的道路.领头的车辆迎着其他车流,形成了一个缓冲带,一辆货车断后以监测整个队伍的进程.  相似文献   

11.
Towards Mobile Ubiquitous Service Environment   总被引:2,自引:0,他引:2  
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.  相似文献   

12.
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。  相似文献   

13.
This paper presents a unified treatment of various important signal processing techniques for the extraction of the instantaneous envelope and phase of a real signal. These techniques include Complex Demodulation, Hilbert Transformation, In-Phase and In-Quadrature Filtering, Phase-Locked Loop Demodulation, and Peak Amplitude and Zero-Crossing Detection. The salient points in the mathematical theory and implementation of these techniques are outlined, as well as their interrelationships via the theory of analytic signals. The advantages and limitations of each of these techniques are elaborated upon, and Complex Demodulation is shown to be the most effective and flexible method from an implementation point of view. The relation of the above techniques to Fourier spectrum analysis is elucidated, and an example is presented of applying Complex Demodulation for the quantification of time nonstationarities in the electrographic morphology of an EEG waveform.  相似文献   

14.
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。  相似文献   

15.
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.  相似文献   

16.
The anisotropic growth of one-dimensional or filamental crystals in the form of microwires and nanowires constitutes a rich domain of epitaxy and newly enabled applications at different length and size scales. Significant progress has been accomplished in controlling the growth, morphology, and properties of semiconductor nanowires and consequently their device level performance. The objective of this review is two-fold: to highlight progress up to date in nanowire doping and to discuss the remaining fundamental challenges. We focus on the most common semiconductor nanowire growth mechanism, the vapor-liquid-solid growth, and the perturbation of its kinetic and thermodynamic aspects with the introduction of dopants. We survey the origins of dopant gradients in nanowire growth and summarize quantification techniques for dopants and free-carrier concentrations. We analyze the morphological changes due to dopants and the influence of growth droplet seeds on composition and morphology and review growth aspects and alternatives that can mitigate these effects. We then summarize some of the remaining issues pertaining to dopant control in nanowires.  相似文献   

17.
李峰 《长江信息通信》2021,34(2):167-171
数字经济时代,企业面临更加激烈的市场竞争环境,传统的供应链管理模式的问题日趋显现,亟需进行数字化转型。企业的发展需要更加智能、高效的数字化供应链的支撑。针对这一现状和需求,文章着力于研究如何解决传统企业供应链数字化转型的问题,设计了一套基于SAP ERP和EWM系统为核心的企业数字化供应链的解决方案:通过SAP ERP和EWM系统的无缝对接实现了企业物流相关业务的自动流转;通过EWM与WCS系统的无缝对接以及WCS系统与自动化立体仓库硬件设备的集成实现了仓库所有出入库作业的自动传递和执行;通过引入条码技术以及与RF设备的集成实现了全流程作业的自动识别和准确高效的处理。该解决方案的设计与实现,帮助企业极大地提高了供应链各个环节的作业效率,提高了整个供应链的透明度,进而提升了企业的整体运营效率和管理水平,使得企业能在日趋激烈的市场竞争环境中保持竞争优势,并取得长足发展。  相似文献   

18.
Composition dependence of bulk and surface phonon-polaritons in ternary mixed crystals are studied in the framework of the modified random-element-isodisplacement model and the Bom-Huang approximation. The numerical results for Several Ⅱ - Ⅵ and Ⅲ- Ⅴ compound systems are performed, and the polariton frequencies as functions of the compositions for ternary mixed crystals AlxGa1-xAs, GaPxAS1-x, ZnSxSe1-x, GaAsxSb1-x, GaxIn1-xP, and ZnxCd1-xS as examples are given and discussed. The results show that the dependence of the energies of two branches of bulk phonon-polaritons which have phonon-like characteristics, and surface phonon-polaritons on the compositions of ternary mixed crystals are nonlinear and different from those of the corresponding binary systems.  相似文献   

19.
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。  相似文献   

20.
提供了一种用于安德鲁反射测量样品制备新方法. 该方法采用聚焦粒子束刻蚀和磁控溅射,可以获得可控的、干净的、无应力的纳米接触用于自旋极化探测. 所制备的样品中,磁性和非磁性材料样品的反射谱都表现出复杂的峰和谷结构,这些结构可能源于与界面相关的零偏压反常以及与激发态相关的准离子相互作用. 对另一个Co40Fe40B20合金样品采用简单的钕针尖压针方法进行了对比性测量,反射谱中没有观察到谷结构,但谱结构出现较明显的热扩展,这种热扩展可能来源于界面处的非弹性输运. 所有的反射谱目前还不能由现有的理论给出令人满意的解释. 利用点接触反射方法获得可靠的自旋极化信息还有赖于接触界面特征的进一步分析. 而一个更切合实际的、更完善的理论成为迫切的需要.  相似文献   

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