H．265标准现状和发展应用趋势

一．前言 目前世界上的视频编解码标准主要来源于国际电联ITU-T和国际标准化组织ISO,ITU的H．26x系列视频压缩标准经过了H．261,H．263,H．263＋这样一个演进过程,而ISO的视频压缩标准是MPEG系列,从MPEG1．MPEG2到MPEG4,之后两个标准化组织走向合作,成立了JVT,推出了在当前最有效的视频压缩标准,H．264／AVC,从H．264标准发布到如今已经五年时间,     

H.263视频编码的码率控制算法及硬件实现

提出了一种H．263低码率视频压缩编码的自适应码率控制方法，这种方法可以用FPGA来实现，为了达到实时性的要求，对硬件实现的具体方法进行了优化。所提出的码率控制优化方法已在H．263标准的硬件系统中实现。     

视频压缩编码中的运动估计搜索算法

对可用于视频压缩编码中的运动估计搜索算法原理进行了分析，对这些算法在H．263＋测试模型上进行了测试。通过对测试数据的比较，基于中心的三步搜索法（CTSS）具有搜索精度高，速度快的优点，可用于视频压缩编码中。     

基于可编程处理器的H．264实现

随着多媒体编码技术的发展，视频压缩标准在很多领域都得到了成功应用．如VCD(MPEG-1)、视频会议(H．263)、DVD(MPEG-2)、机顶盒(MPEG-2)等等。     

H264及相关视频编码标准论述

视频压缩国际标准主要有：由ITU—T制定的H．261、H．262、H．263、H．264和由MPEG制定的MPEG-1、MPEG-2、MPEG-4，其中H．262／MPEG-2和H．264／MPEG-4AVC由ITU—T与MPEG联合制定。     

H.263简介

介绍最新的有关低比特率视频压缩的国际标准化建议H．263的系统构成和比特流结构。对其包含的四个可选的编码选项作了说明。     

H.26L视频压缩编码协议及其性能分析

在与H.263协议进行比较的基础上简要介绍了H.26L视频压缩编码协议，并结合H.26L和h.263对Forman序列、silent序列进行的编码，以及得到的比特率和信噪比分析了两者的性能，给出了分析结果。     

图像压缩编码国际标准化的发展

●视频压缩是多媒体通信的关键环节●现今视频压缩的国际标准多种并存●与其它标准相比,ITU-T的新提建议H.263 所采用的技术更全面,适用的范围更广泛     

H．264／AVC视频编码的重要价值

MPEG(Moving Picture Experts Group)和VCEG(Video Coding Experts Group)已经联合开发了一个比早期研发的MPEG和H．263性能更好的视频压缩编码标准，这就是被命名为AVC(Advanced Video Coding)的，也被称为ITU—TH．264建议和MPEG-4的第10部分的标准，在这里，就简称它为H．264/AVC或H．264。这个标准已于2003年3月被ITU—T通过并在国际上正式颁布。     

异军突起的H.264标准

随着多媒体编码技术的发展，视频压缩标准在很多领域都得到了成功应用，如VCD（MPEG-1）、视频会议（H-263）、DVD（MPEG-2）、机顶盒（MPEG-2）等。而网络带宽的不断提升和高效视频压缩技术的发展使得人们逐渐把关注的焦点转移到了宽带网络数字电视（IPTV）、流媒体等基于传输的业务上来。带宽的增加为流式媒体的发展铺平了道路，而高效的视频压缩标准的出台则是流媒体技术发展的关键。     

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.     

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.     

Design and experimental study of compensation fitting on the angle-tuned filters

For a 100 GHz DWDM angle-tuned filter with low polarization dependent loss, the insertion loss and the Gaussian- transformation tendency of the transmission spectrum will become more serious as the incident angle is increased. It is because of that the optical path and the transmission modes of the thin film filter will change when the incident angle is varied. According to the thin film matrix theory, the analysis model is established, the displacement change of the transmis- sion field is simulated, and a dynamic compensation fitting is also designed and fabricated in the paper. The experimental results show that it can effectively reduce the insertion loss and the phenomenon of Gaussian process. Using the compen- sation fitting, the tunable range of the filter is at about 20 nm which coincides with the theoretical design.     

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.     

Alternative Schemes for Dynamic Secure VPN Deployment in UMTS

Three alternative schemes for secure Virtual Private Network (VPN) deployment over the Universal Mobile Telecommunication System (UMTS) are proposed and analyzed. The proposed schemes enable a mobile node to voluntarily establish an IPsec-based secure channel to a private network. The alternative schemes differ in the location where the IPsec functionality is placed within the UMTS network architecture (mobile node, access network, and UMTS network border), depending on the employed security model, and whether data in transit are ever in clear-text, or available to be tapped by outsiders. The provided levels of privacy in the deployed VPN schemes, as well as the employed authentication models are examined. An analysis in terms of cost, complexity, and performance overhead that each method imposes to the underlying network architecture, as well as to the mobile devices is presented. The level of system reliability and scalability in granting security services is presented. The VPN management, usability, and trusted relations, as well as their behavior when a mobile user moves are analyzed. The use of special applications that require access to encapsulated data traffic is explored. Finally, an overall comparison of the proposed schemes from the security and operation point of view summarizes their relative performance. Christos Xenakis received his B.Sc. degree in computer science in 1993 and his M.Sc. degree in telecommunication and computer networks in 1996, both from the Department of Informatics and Telecommunications, University of Athens, Greece. In 2004 he received his Ph.D. from the University of Athens (Department of Informatics and Telecommunications). From 1998–2000 was with the Greek telecoms system development firm Teletel S.A., where was involved in the design and development of advanced telecommunications subsystems for ISDN, ATM, GSM, and GPRS. Since 1996 he has been a member of the Communication Networks Laboratory of the University of Athens. He has participated in numerous projects realized in the context of EU Programs (ACTS, ESPRIT, IST). His research interests are in the field of mobile/wireless networks, security and distributed network management. He is the author of over 15 papers in the above areas. Lazaros Merakos received the Diploma in electrical and mechanical engineering from the National Technical University of Athens, Greece, in 1978, and the M.S. and Ph.D. degrees in electrical engineering from the State University of New York, Buffalo, in 1981 and 1984, respectively. From 1983 to 1986, he was on the faculty of Electrical Engineering and Computer Science at the University of Connecticut, Storrs. From 1986 to 1994 he was on the faculty of the Electrical and Computer Engineering Department at Northeastern University, Boston, MA. During the period 1993–1994 he served as Director of the Communications and Digital Processing Research Center at Northeastern University. During the summers of 1990 and 1991, he was a Visiting Scientist at the IBM T. J. Watson Research Center, Yorktown Heights, NY. In 1994, he joined the faculty of the University of Athens, Athens, Greece, where he is presently a Professor in the Department of Informatics and Telecommunications, and Director of the Communication Networks Laboratory (UoA-CNL) and the Networks Operations and Management Center. His research interests are in the design and performance analysis of broadband networks, and wireless/mobile communication systems and services. He has authored more than 150 papers in the above areas. Since 1995, he is leading the research activities of UoA-CNL in the area of mobile communications, in the framework of the Advanced Communication Technologies & Services (ACTS) and Information Society Technologies (IST) programmes funded by the European Union (projects RAINBOW, Magic WAND, WINE, MOBIVAS, POLOS, ANWIRE). He is chairman of the board of the Greek Universities Network, the Greek Schools Network, and member of the board of the Greek Research Network. In 1994, he received the Guanella Award for the Best Paper presented at the International Zurich Seminar on Mobile Communications.     

Characteristics of gradually doped LWIR diodes by hydrogenation

The hydrogenation effects on HgCdTe diode performance are presented and the mechanism of hydrogenation is revealed. By the hydrogenation, R₀A is increased by 30 times and photo-response is also improved. It is supposed that these are explained by the increased minority carrier lifetime by the hydrogenation. However, it is found from LBIC measurements that the minority carrier lifetime doesn’t increase by the hydrogenation. An important clue that explains the hydrogenation effects is found from Hall measurements. It is found that, after the hydrogenation, the doping concentration of Hg-vacancy doped substrate decreases and the mobility increases. For the heavily hydrogenated bulk substrate, it is also found that the hydrogen passivates the whole Hg-vacancy and reveals the residual impurity and p-type doping concentration is exponentially graded. From these measurements, the diffusion current model of gradually doped diode is proposed. This model shows that the diffusion current of the graded junction diode is 2 orders of magnitude smaller than that of the abrupt junction diode, which clearly explains the R₀A increase by the hydrogenation. Medicisimulation to investigate the change of LBIC signal by the doping grading also coincides with the measurements. From these measurements and model, the hydrogenation effects are attributed to the grading of Hg-vacancy doped p-type substrate by the diffused hydrogen.     

Computing the polyadic decomposition of nonnegative third order tensors

Computing the minimal polyadic decomposition (also often referred to as canonical decomposition or sometimes Parafac) amounts to finding the global minimum of a coercive polynomial in many variables. In the case of arrays with nonnegative entries, the low-rank approximation problem is well posed. In addition, due to the large dimension of the problem, the decomposition can be rather efficiently calculated with the help of preconditioned nonlinear conjugate gradient algorithms, as subsequently shown, if equipped with an algebraic calculation of the globally optimal stepsize in low dimension. Other algorithms are also studied (gradient and quasi-Newton approaches) for comparisons. Two versions of each algorithm are considered: the enhanced line search version (ELS), and the backtracking version alternating with ELS. Computer simulations are provided and demonstrate the good behavior of these algorithms dedicated to nonnegative arrays, compared to others put forward in the literature. Finally, applications in the context of data analysis illustrate various algorithms. The main advantage of the suggested approach is to explicitly take into account the nonnegative nature of the loading matrices in the problem parameterization, instead of enforcing positive entries by projection. According to the experiments we have run, such an approach also happens to be more robust with respect to possible modeling errors.     

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.     

位屏蔽多叉树搜索射频识别防碰撞算法

针对RFID树型防碰撞算法中时隙数多、数据通行量大等问题,提出了一种改进的多叉树防碰撞算法,阅读器准确检测碰撞位并向标签反馈碰撞位信息,标签对阅读器已知的ID位进行屏蔽,把ID号转换成连续碰撞的序列号.阅读器利用屏蔽位信息和标签返回的碰撞位编码信息,对标签进行分层分类搜索.通过对标签ID进行屏蔽,阅读器和标签间仅发送对方不知道的碰撞位信息.该算法减少了碰撞时隙和识别时隙,避免了空闲时隙,减少了阅读器和标签间的数据通信量.理论分析和仿真结果表明,该算法减少了系统的时隙总数和数据通信量,提高了阅读器的识别效率.     

用FFT对8FSK信号进行解调方法的比较

随着DSP技术的发展,快速傅里叶变换(FFT)的应用越来越广泛。利用FFT算法对频移键控(FSK)信号进行频谱分布,通过比较FFT计算结果来确定信号的频率,可以实现对FSK信号的解调。采用MIL-STD-188-141A中的8FSK调制信号作为仿真信号,用MATLAB6.1对解调进行仿真。在提到的三种FFT的检测方案中,在没有频偏的情况下,第一种要较好;但当有频偏存在时,第二种方法较好。