ATM技术及其研究现状

本文简述了信息传输技术的发展历史;阐明了ATM 技术的概念并指出交换技术是ATM 技术的核心;介绍了目前ATM 技术的研究状况,着重介绍了几种具有代表性的ATM 交换系统;讨论了ATM 技术的另外两个组成部分——突发编码技术和流量控制技术。     

IP与ATM的综合透视

本文就目前IP与ATM存在的问题,讨论了IP与ATM的融合技术。     

桌面ATM的前景与可能性

在通信行业中,ATM(异步传输模式)时下已成为一个热门话题.不少公司已经开始推出基于ATM的下一代通信产品.我国也把ATM技术列入待开发的技术之一.从长远来看,用户转向ATM已是一个不可避免的发展趋势,但是,在何时转向ATM技术,人们还存在着严重分歧.为了使读者能了解这一新兴技术的方方面面,本刊这一期从《Telecommunications》等杂志中选登了最新发表的长长短短近10篇文章组成了ATM专题.这种以专题形式报道某种产品和技术,对本刊来说还是第一次.我们殷切希望广大读者能就这种报道形式发表你们的看法,帮助本刊提高报道水平.     

ATM over xDSL技术在端到端的宽带网络中应用

ATM over xDSL代表了一种新的、不可忽视的宽带接入技术的发展趋势。本文介绍了利用xDSL技术作为ATM网络扩展到小区的传输手段,构造了一个端到端的宽带网络环境“ATM over xDSL”,以及在此网络上可以开展的应用。     

ATM技术概述及其发展状况的研究

介绍了异步传输模式（ATM）技术的原理与特点。在简要阐述ATM技术在国内外发展状况的基础上,从无线ATM、基于ATM的无源光网络、ATM与现有网络的兼容三个方面讨论并分析了ATM技术的发展趋势以及ATM研究中存在的问题,为研究ATM提供参考。     

ATM交换技术的发展前景

ATM是一种新的传输模式，目前Internet所依赖的IP技术的弱点会逐渐显露，将Internet与ATM结合可以较好地解决这个矛盾，因此Internet可以对ATM的发展起到促进作用，这是ATM发展的一个机会，从而加快了ATM的推广和应用。     

IP与ATM的综合透视

本文就目前IP与ATM存在的问题,讨论了IP与ATM的融合技术。     

无线ATM系统中的AAL5技术

信息产业正在经历着有史以来最深刻的变化.在全世界范围内,以Internet为代表的数据业务正以惊人的速度增长.不远的将来,语音业务与数据业务量相比将显得微不足道,数据业务依附电话网络的时代将过去,一个崭新的信息时代即将到来.针对这种情况,构筑一个新的信息网络模型,迎接数字化时代的到来势在必行.于是ATM在宽带接入技术中脱颖而出.ATM技术作为B-ISDN的基础,在传输包括话音、图象、数据的综合业务环境中具有现有其他技术所不具备的技术优势.当前,随着ATM技术标准的日益成熟,ATM的应用正成为研究的热点.如果说在20世纪90年代初期,ATM技术由于价格昂贵、技术复杂等一系列原因在市场方面受到抑制的话,目前,随着ATM交换机价格的下降,其所占市场份额正在逐渐扩大.另一方面,从ATM技术对现有技术的适应性来看,尽管ATM论坛(ATM Forum)在局域网仿真技术等方面作了大量的工作并取得不少的成效,但仍然存在需要解决的问题.无线ATM是一项跨世纪的新兴通信技术,受到了广泛的重视,世界各国都积级开展ATM技术的研究和B-ISDN的建设.     

ATM技术的回顾与展望

该文从ATM技术应用的角度,介绍了曾被广泛关注的各种ATM技术,分析了其存在的主要问题。高级信元传输技术是国内最早研究的下一代宽带网络技术之一。该文还介绍了解决当前ATM存在问题的思路和研究进展,并对ATM技术的未来进行了展望。该文的工作有助于读者了解ATM技术现状,建立ATM技术发展的全局概念,把握网络技术的发展趋势。     

慎选ATM

应ATM技术本身来讲,它的特点为高带宽（155Mbps以上）,并且具有QOS等级服务来提供不同的电信服务,如图象、话音及数据。但是QOS是ATM在不配置成局域网仿真时成立的。换句话说,当你的大楼局域网采用ATM／局域网仿真（LANEmulation）时,也就是仿真以太同时,您就无法使用到ATM技术在城域网（MAN）或广域网（WAN）上所有的QoS。ATM／局域网仿真是技术发展过程中的一种过渡,这是因为前几年千兆以太网（GE）还未成熟,所以ATM／局域网仿真才被采用。但是ATM到桌面不太现实,因为它需要主机操作系统、驱动程序。阿卡的全面…     

Resolution Enhancement Technology:Integrated Process Solutions using OPC

DUV lithography, using the 248 nm wavelength, is a viable manufacturing option for devices with features at 130 nm and less. Given the low kl value of the lithography, integrated process development is a necessary method for achieving acceptable process latitude. The application of assist features for rule based OPC requires the simultaneous optimization of the mask, illumination optics and the resist.Described in this paper are the details involved in optimizing each of these aspects for line and space imaging.A reference pitch is first chosen to determine how the optics will be set. The ideal sigma setting is determined by a simple geometrically derived expression. The inner and outer machine settings are determined, in turn,with the simulation of a figure of merit. The maximum value of the response surface of this FOM occurs at the optimal sigma settings. Experimental confirmation of this is shown in the paper.Assist features are used to modify the aerial image of the more isolated images on the mask. The effect that the diffraction of the scattering bars (SBs) has on the image intensity distribution is explained. Rules for determining the size and placement of SBs are also given.Resist is optimized for use with off-axis illumination and assist features. A general explanation of the material' s effect is discussed along with the affect on the through-pitch bias. The paper culminates with the showing of the lithographic results from the fully optimized system.     

Cost-effective test solutions for smart card and other integrated flash applications

From its emergence in the late 1980s as a lower cost alternative to early EEPROM technologies, flash memory has evolved to higher densities and speedsand rapidly growing acceptance in mobile applications.In the process, flash memory devices have placed increased test requirements on manufacturers. Today, as flash device test grows in importance in China, manufacturers face growing pressure for reduced cost-oftest, increased throughput and greater return on investment for test equipment. At the same time, the move to integrated flash packages for contactless smart card applications adds a significant further challenge to manufacturers seeking rapid, low-cost test.     

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.     

An improved parallel thinning algorithm with two subiterations

The parallel thinning algorithm with two subiterations is improved in this paper. By analyzing the notions of connected components and passes, a conclusion is drawn that the number of passes and the number of eight-connected components are equal. Then the expression of the number of eight-connected components is obtained which replaces the old one in the algorithm. And a reserving condition is proposed by experiments, which alleviates the excess deletion where a diagonal line and a beeline intersect. The experimental results demonstrate that the thinned curve is almost located in the middle of the original curve connectivelv with single pixel width and the processing speed is high.     

Novel fiber-optical interferometer with miniaturized probe for in-hole measurements

Today, micro-system technology and the development of new MEMS （Micro-Electro-Mechanical Systems） are emerging rapidly. In order for this development to become a success in the long run, measurement systems have to ensure product quality. Most often, MEMS have to be tested by means of functionality or destructive tests. One reason for this is that there are no suitable systems or sensing probes available which can be used for the measurement of quasi inaccessible features like small holes or cavities. We present a measurement system that could be used for these kinds of measurements. The system combines a fiber optical, miniaturized sensing probe with low-coherence interferometry, so that absolute distance measurements with nanometer accuracy are possible.     

Development of the readout system for waveguide multilayer optical card

Waveguide multilayer optical card （WMOC） is a novel storage device of three-dimensional optical information. An advanced readout system fitting for the WMOC is introduced in this paper. The hardware mainly consists of the light source for reading, WMOC, motorized stages addressing unit, microscope imaging unit, CCD detecting unit and PC controlling ＆ processing unit. The movement of the precision motorized stage is controlled by the computer through Visual Basic （VB） language in software. A control panel is also designed to get the layer address and the page address through which the position of the motorized stages can be changed. The WMOC readout system is easy to manage and the readout result is directly displayed on computer monitor.     

Study of waveguide coupling efficiency in hybrid silicon lasers

This paper presents a new method to increase the waveguide coupling efficiency in hybrid silicon lasers. We find that the propagation constant of the InGaAsP emitting layer can be equal to that of the Si resonant layer through improving the design size of the InP waveguide. The coupling power achieves 42% of the total power in the hybrid lasers when the thickness of the bonding layer is 100 nm. Our result is very close to 50% of the total power reported by Intel when the thickness of the thin bonding layer is less than 5 nm. Therefore, our invariable coupling power technique is simpler than Intel＇s.     

Collinear phase-matching study of terahertz-wave generation via difference frequency mixed in GaAs and Inp

The collinearly phase-matching condition of terahertz-wave generation via difference frequency mixed in GaAs and InP is theoretically studied. In collinear phase-matching, the optimum phase-matching wave hands of these two crystals are calculated. The optimum phase-matching wave bands in GaAs and lnP are 0.95-1.38μm and 0.7-0.96μm respectively. The influence of the wavelength choice of the pump wave on the coherent length in THz-wave tuning is also discussed. The influence of the temperature alteration on the phase-matching and the temperature tuning properties in GaAs crystal are calculated and analyzed. It can serve for the following experiments as a theoretical evidence and a reference as well.     

Effects of the alloy compositions on the phonon-polaritons in ternary mixed crystals

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.     

New insert layer structure OLEDs

An insert layer structure organic electroluminescent device（OLED） based on a new luminescent material （Zn（salen）） is fabricated. The configuration of the device is ITO/CuPc/NPD/Zn（salen）/Liq/LiF/A1/CuPc/NPD/Zn（salen）/Liq/LiF/A1. Effective insert electrode layers comprising LiF（1nm）/Al（5 nm） are used as a single semitransparent mirror, and bilayer cathode LiF（1 nm）/A1（100 nm） is used as a reflecting mirror. The two mirrors form a Fabry-Perot microcavity and two emissive units. The maximum brightness and luminous efficiency reach 674 cd/m^2 and 2.652 cd/A, respectively, which are 2.1 and 3.7 times higher than the conventional device, respectively. The superior brightness and luminous efficiency over conventional single-unit devices are attributed to microcavity effect.