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1.
蓝牙技术与红外无线接入技术   总被引:3,自引:0,他引:3  
作为短程无线接入技术,蓝牙技术与红外无线接入技术各有自己的特点,且都得到了广泛的应用,本文首先分析了两种技术各自的特点,对两种技术进行了比较,然后分析了各自的应用领域及两种技术相互之间的关系。  相似文献   

2.
论半导体激光器及调制技术   总被引:1,自引:0,他引:1  
在当代的通讯传输领域中,半导体激光器及调制技术展示出前所未有和不可代替的技术成就。半导体激光器及调制技术的种类较多,从其对光源进行调制的方式上来区分,可分为光强度直接调制和光强度外部调制两种方式。本分别对这两种光强度调制方式进行了论述。  相似文献   

3.
系统芯片和系统级封装是目前微电子技术高速发展的两种技术路线,本文讨论了系统的基本概念,针对两种技术路线的基本特点进行了介绍和分析,从工艺兼容性、已知好芯片问题、封装、市场及设计的角度比较了两者的优缺点。  相似文献   

4.
本文主要针对目前基于有线电视网络上开展宽带接人业务的两种技术方式(Cable Modem和Dataover Coax同轴宽带接入技术),通过对两种技术在性能,安全可靠性和可管理性.可扩展性及投入产出比等性能指标进行分析比较,我们认为Cable Modem技术更加成熟完善,对将来多业务的支撑能力更强,但是需要进行网络双向改造,对网络质量要求很高,因此成本投入很高,投资回收期较长。同轴宽带接人技术投资小,且不需要双向改造,可以满足小规模的宽带接入业务,但是不具备可扩展性。两种技术各有优劣,因此根据这种差异,我们认为应根据自身情况和市场定位,合理利用两种技术方式,进行优势互补,会取得更理想的效果。  相似文献   

5.
城域网接入层技术的选择,在很大程度上决定了宽带IP城域网的建设模式。本力图通过对LAN和xDSL两种主要接入方式的技术及成本比较,分析两种模式各自的优势,为运营商在技术的选择上提供可参考的建设策略。  相似文献   

6.
OCDMA通信技术及其新发展   总被引:3,自引:1,他引:2  
介绍了OCDMA通信技术原理及其关键技术,然后分析和比较了用于OCDMA技术的地址码和编解码器技术,给出了两种OCDMA网络,最后分析了OCDMA技术存在的问题及发展前景。  相似文献   

7.
第四代移动通信提供高的数据传输速率,而MIMO和OFDM提高了频谱效率,从而提供高传输速率和系统容量的技术。两者的结合已经成为第四代移动通信技术研究中的热点。通过这两种技术的优势互补,可以为系统提供高传输速率,同时也能提高系统容量,降低成本。本文详细介绍了这两种技术及信道估计。  相似文献   

8.
无线光通信技术是一种宽带无线接入技术。是光通信技术和无线通信技术相结合的产物。介绍了两种无线光通信技术(自由空间光通信FSO和可见光通信VLC)的优势及不足,介绍了VLC在室内的一个典型应用,最后展望了这两项无线光通信技术未来的研究方向及发展趋势。  相似文献   

9.
随着云计算技术的不断成熟和发展,容器云与虚拟化技术的融合成为云平台新的部署和应用模式,结合容器和虚拟机各自的优势为用户提供多样的应用支撑手段。本文阐述了容器和虚拟机各自的优劣势,提出容器云和虚拟化平台的两种集成架构及技术原理,对比分析了各自的优劣势,并展望了两种技术架构未来的应用前景。  相似文献   

10.
第二层和第三层MPLS VPN   总被引:2,自引:0,他引:2  
VPN技术正在得到日益广泛的应用,这其中MPLS VPN技术由于成本和技术的优势越来越受到运营商的青睐。本文介绍了MPLS VPN的两种实现方式,第二层MPLS VPN和第三层MPLS VPN。从它们的实现原理、优缺点及应用范围等方面作了深入分析,并对于这两种技术的选择给出了考虑原则。  相似文献   

11.
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   

12.
胆小管超微细胞酶学研究   总被引:1,自引:0,他引:1  
以电镜细胞化学的方法,观察了小鼠胆小管酶的分布。观察的12种酶中,NDPase和G6Pase三种酶分布于胆小管微绒毛;AlPase、Na~+-K~+ATPase、Mg~(++)-ATPase、Ca~(++)-ATPase、CMPase、ACase和5'-Nase等7种酶分布于胆小管微绒毛,也分布于肝细胞邻接面细胞膜和Disse间隙微绒毛;ACPase、细胞色素氧化酶以及线粒体ATPase不分布胆小管微绒毛,也不分布Disse间隙微绒毛和肝细胞膜。据信,胆小管微绒毛上的酶参与胆汁成份的转运,提供转运所需能量以及还可能与某些代谢过程有关。本实验中磷酸水解酶类使用的铈基法及亚铁氰化钾半还原的锇酸后固定法,效果优于铅法。  相似文献   

13.
This paper presents a systematic review of models and methodologies that integrate information and communication technologies (ICT) and education. The systematic review was based on the methodology of Kitchenham. The steps used and developed correspond to the steps proposed in the methodology. The starting point of the review are the research questions, then keywords, selection of the databases, definition of the inclusion and exclusion criteria, the definition of the search chains, search process and selection of papers, the analyzes of the paper and the results of the systematic review to answer the questions posed. In the systematic review, 919 papers were found in 6 academic databases and 129 relevant papers were selected. The work developed intends to know the different models and methodologies that integrate the ICT and the education. Develop an analysis and characterize to find common elements among models and methodologies. The idea is to find limitations, disadvantages and spaces that allow to propose a new model. This systematic review is the first step in the development of a doctoral research in which the development of a U-Learning model based on Connective Learning and Experience Learning is proposed.  相似文献   

14.
米酵菌酸对小鼠肝和心肌细胞毒性作用的超微结构研究   总被引:4,自引:0,他引:4  
目的:观察米酵菌酸对小鼠肝、心肌细胞毒性作用的超微结构改变,探讨米酵菌酸中毒的机理,方法:小鼠腹腔注射不同剂量的米酵菌酸,2h后取其肝和心肌组织,通过电镜观察其细胞超微结构的改变,结果:电镜下可见肝细胞和心肌细胞的线粒肿胀,内嵴断裂,模糊或消失,基质局部或全部空亮,呈囊泡样变,偶见其中含髓样小体,上述线粒体内嵴和膜结构的病变随米酵菌酸剂量的增加而加重,结论:米酵菌酸对小鼠肝、心肌细胞毒性作用以线粒体的损伤较为突出,因此我们认为,线粒体内膜的破坏造成线粒体的功能障碍,影响细胞呼吸,使细胞缺氧导致小鼠中毒死亡。  相似文献   

15.
This paper describes the design and implementation of a hybrid intelligent surveillance system that consists of an embedded system and a personal computer (PC)-based system. The embedded system performs some of the image processing tasks and sends the processed data to the PC. The PC tracks persons and recognizes two-person interactions by using a grayscale side view image sequence captured by a stationary camera. Based on our previous research, we explored the optimum division of tasks between the embedded system and the PC, simulated the embedded system using dataflow models in Ptolemy, and prototyped the embedded system in real-time hardware and software using a 16-bit CISC microprocessor. This embedded system processes one 320 × 240 frame in 89 ms, which yields one-third of the rate of 30 Hz video system. In addition, the real-time embedded system prototype uses 5.7 K bytes of program memory, 854 K bytes of internal data memory and 2 M bytes external DRAM. Koichi Sato is a Ph.D. student in the Department of Electrical and Computer Engineering at The University of Texas at Austin. He earned his B.S. in University of Tokyo, Japan in 1993. He worked for Automotive Development Center in Mitsubishi Electric Corporation where he was involved in lane and automobile recognition in vehicle video processing products such as automatic cruise control and drowsiness detection systems. He enrolled in the current University at 1998 and received an M.S in 2000. In his Master's thesis he worked on human tracking and human interaction recognition. His current work includes velocity extraction using the TSV transform, object tracking, and 3D object reconstruction. Brian L. Evans is a tenured Associate Professor in the Department of Electrical and Computer Engineering at The University of Texas at Austin. His research and teaching efforts are in embedded real-time signal and image processing systems. In signal processing, his research group is focused on the design and real-time software implementation of ADSL and VDSL transceivers, for high-speed Internet access. In image processing, his group is focused on the design and real-time software implementation of high-quality halftoning for desktop printers, smart image acquisition for digital still cameras, and 3-D sonar imaging systems. In signal and image processing, Dr. Evans has published over 100 refereed conference and journal papers. Dr. Evans is the primary architect of the Signals and Systems Pack for Mathematica, which has been on the market since October 1995. He was a key contributor to UC Berkeley's Ptolemy Classic electronic design automation environment for embedded systems, which has been successfully commercialized by Agilent and Cadence. His BSEECS (1987) degree is from the Rose-Hulman Institute of Technology, and his MSEE (1988) and PhDEE (1993) degrees are from the Georgia Institute of Technology. From 1993 to 1996, he was a post-doctoral researcher in the Ptolemy project at UC Berkeley. He is a member of the Design and Implementation of Signal Processing Systems Technical Committee of the IEEE Signal Processing Society, and a Senior Member of the IEEE. He is the recipient of a 1997 National Science Foundation CAREER Award. J.K. Aggarwal has served on the faculty of The University of Texas at Austin College of Engineering since 1964 and is currently Cullen Professor of Electrical and Computer Engineering and Director of the Computer and Vision Research Center. His research interests include computer vision and pattern recognition focusing on human motion. A Fellow of IEEE since 1976 and IAPR since 1998, he received the Senior Research Award of the American Society of Engineering Education in 1992, the 1996 Technical Achievement Award of the IEEE Computer Society and the graduate teaching award at The University of Texas at Austin in 1992. He has served as Chairman of the IEEE Computer Society Technical Committee on Pattern Analysis and Machine Intelligence (1987--1989); Director of the NATO Advanced Research Workshop on Multisensor Fusion for Computer Vision, Grenoble, France (1989); Chairman of the IEEE Computer Society Conference on Computer Vision and Pattern Recognition (1993), and President of the International Association for Pattern Recognition (1992--1994). He is a Life Fellow of IEEE and Golden Core member of IEEE Computer Society. He has authored and edited a number of books, chapters, proceedings of conferences, and papers.  相似文献   

16.
小信号多腔速调管主要性能指标简化分析   总被引:1,自引:0,他引:1  
宁曰民 《微波学报》2005,21(3):43-47
介绍了速调管在我国的发展现状和小信号条件下速调管的各种主要性能指标的简化分析方法。在这种简化分析方法中,首先不考虑非线性和相对论效应等带来的影响,并把多腔速调管看作是几个双腔速调管的级联,得出了增益、效率、带宽和输出功率等重要参数的计算公式。然后通过给出部分参数的修正系数说明了这种简化分析方法的实用价值及理论指导意义。  相似文献   

17.
电子学的崛起、发展和广泛应用是20世纪最伟大的科学技术领域之一.在电磁波理论和自由电子发展的基础上,1904年出现了第一只真空二极电子管,一般认为这标志着电子学的诞生.电磁波频谱资源的开发和利用是电子学发展的基础和动力.从电磁频谱统一的观点看,光已经象微波一样进入到电子学的领域,成为无线电电子学中不可分割的组成部分.电子学的基本任务是:研究带电粒子流与电磁场相互作用的物理概念和物理过程,以及利用相互作用的不同物理机制实现粒子与场之间能量有效转化的方法和条件.从电子器件的观点看,电子学可分为真空电子学与固态电子学;而从电子运动规律的观点看,现代电子学将处理自由电子,准自由电子和束缚电子的运动规律及其与电磁场的相互作用.1958年,电子学领域出现三个重要发现和发明:集成电路、激光和相对论自由电子的回旋辐射.相应的,半导体电子学(微电子学)、激光电子学和相对论电子学等现代电子学领域则发端于此.电子器件小型化、微型化、功能集成化将电磁频谱的开拓和占领推向光波和红外毫米波.  相似文献   

18.
王鹏周政 《微波学报》2012,28(S2):361-363
GPS 卫星定位技术已广泛应用于航空航天系统。本文通过阐述GPS 接收机的工作原理及GPS 信号的特点,分 析了接收机交调互调传导敏感度测量原理,扩展了GPS 接收机交调互调传导敏感度的试验方法。该测试方法快捷、易 于掌握,便于得到接收机互调交调抑制比参数。  相似文献   

19.
时岩 《电子技术》2012,(3):12-13
在深入理解ARM和TMSC320C5000在参与基于OMAP5910的3G无线终端的多媒体应用平台硬件系统设计基本原则的基础上,文章画出一个硬件系统原理图和印刷电路板图;各种功能模块进行测试和调试;完成与CPLD相关的硬件语言设计和调试,在QuartusII软件下用VerilogHDL编写;在掌握Linux操作系统及嵌入式操作系统的移植和开发及Linux下的驱动程序开发的基础上,完成DSP、Camera、触摸屏等底层驱动程序的开发;完成Microwindow下顶层用户界面和JPEG等应用程序的开发,和Linux驱动程序开发。  相似文献   

20.
A study of the enhancement of the mechanical sensitivity of an area-changed capacitive accelerometer by optimization of the device geometry is presented. The movable mass of the accelerometer was designed with many fingers connected in parallel and suspended over the stationary electrodes composed of differential comb fingers by means of mechanical beams anchored onto the substrate. The maximum displacement possible based on the chosen design structure was determined. From this displacement value the spring constant was calculated, and based on this spring constant value various combinations of the beam length and width were selected. The lengths and the widths were then varied and simulated using the Coventorware 2001.3 software. This was done as theoretical analysis showed that the mechanical beam dimensions are significantly more dominant in the overall device sensitivity. The displacement and spring constant variations with the beam dimensions at an applied acceleration was observed and analyzed. The same process was done for the number of fingers, length and thickness of each finger. Each of these was done in isolation based on the optimum geometry of the mechanical beams and tested to ensure that alterations of these aspects do not have a significant effect on the overall sensitivity. The modal and harmonic analysis were also simulated and observed to ensure the linearity and the stability of the dominant mode of the operation of the device. Optimum results of the device geometry are presented and discussed, along with suggested next steps.Badariah Bais received the B.S. and M.S. degrees from the Worcester Polytechnic Institute, Worcester, MA, in 1990 and 1992, respectively. Since 1997, she has been serving at the Department of Electrical, Electronics and Systems Engineering at Universiti Kebangsaan Malaysia as a teaching staff. She is currently pursuing her Ph.D. in Microelectronics at the Institute of Microengineering and Nanoelectronics (IMEN) at Universiti Kebangsaan Malaysia. Her research interests include MEMS sensors and microfabrication. She is a member of the Institute of Electrical and Electronics Engineer (IEEE).Burhanuddin Yeop Majlis received his Ph.D. in Microelectronics from University of Durham, UK in 1988, MSc. in Microelectronics from University of Wales, UK in 1980 and BSc. (Hons.) in Physics from Universiti Kebangsaan Malaysia in 1979. Now he is the director of Institute of Microengineering and Nanoelectronics (IMEN). He is a senior member of the Institute of Electrical and Electronics Engineer (IEEE) and the Chairman of IEEE Electron Devices Malaysia Chapter since 1994. He is also a member of Malaysian Solid State Science and Technology (MSSS). He has published three text books in electronics and one book on Integrated Circuits Fabrication Technology for undergraduate courses and more than 110 academic research papers. His current interest are MEMS sensor for automotive and RF applications.  相似文献   

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