电离层斜向传播异常信号特性的研究

在对固定电路电离层斜向传播特性的长期连续观测过程中,发现了大量异常斜测电离图.通过对电离层行波扰动情况下电波传播路径的仿真计算,分析了它对电离层斜向传播信号的影响,并利用斜向探测数据,讨论分析了确定行波扰动基本参数的方法.     

斜向探测电离图描迹提取算法研究

电离层斜向探测工作在高频段,密集的外部干扰如短波通信,广播电台以及大气噪声等污染了接收数据,严重影响斜向探测电离图描迹的提取.针对上述问题,本文提出了一种提取斜向探测电离图描迹的算法.该算法由频域去干扰,有序统计量OS-CFAR检测,去虚警点三个步骤构成.对实测数据的处理结果表明这种方法的有效性和实用性.     

基于粒子群优化的斜测电离图反演研究

斜向探测是电离层探测的主要方式之一,它能获得电波传播群时延和频率关系的电离图。斜测电离图包含了探测距离上电离层状态的有用信息,可以通过对这种电离图的反演提取电离层的状态信息。采用粒子群算法对斜测电离图进行了反演,取得了良好的效果。结果证明,该方法能够克服线性求解的不稳定性,获得较好的反演结果,展示了在处理实际斜向探测电离图的应用前景。     

基于遗传算法斜向探测电离层参数反演研究

斜向探测是电离层探测的主要方式之一,它能够获得电波传播群时延和频率关系的电离图。由于传输信号的媒质是电离层,因此斜测电离图包含了收发站之间电离层状态信息,通过对斜测电离图的反演可以提取电离层的状态信息。利用遗传算法,对斜向探测电离层参数进行了反演,获得了较好的结果,展示了该方法在电离层参数反演研究中的优点和实际应用前景。结果证明该方法具有一定的抗噪能力,具有良好的应用价值。     

斜测电离图反演及其不稳定性研究

在已知固定地面距离的发射站和接收站之间的扫频斜向探测技术能够获得电波传播群时延对频率关系的斜测电离图。由于传输斜测信号的媒质是电离层，因此斜测电离图包含了探测距离上电离层状态的有用信息，可以通过对这种电离图的反演提取电离层的状态信息。采用Rao对返回散射电离图的反演算法和解不稳定问题正则方法的结合对斜测电离图进行了反演。该方法能够克服Rao算法的不稳定性，获得较好的反演结果，展示了在处理实际斜向探测电离图的应用前景。     

双基地高频返回散射探测前沿修正研究

高频电离层探测中某一电路形成的斜向探测电离图上各层传播模式的结合频率点应该位于包含该电路的返回散射前沿上,实测数据表明两者有差异.基于返回散射收发异地引起的差异,运用返回散射系统电波传播原理,对返回散射探测群距离P进行改进,通过改进前后自南到北三个方位的结果对比表明,返回散射前沿和斜测最高可用频率(Maximum Usable Frequency,MUF)均方根误差分别改善了12.2%、12.4%、12.8%,这对电离层高频斜向探测和返回散射探测模式信息融合有重要意义.     

斜测电离图F层二跳传播模式估算方法研究

提出了基于斜测电离图F层一跳模式估算二跳传播模式位置的新方法,与精确的短波射线追踪技术仿真结果进行了对比,并利用实测电离图数据进行了验证,分析了估算结果与实际探测结果的误差原因,仿真和试验结果均表明:该估算方法能够较准确地给出F层二跳传播模式的群路径范围和频率范围,有助于识别斜测电离图不同频率传播模式,可作为斜测电离图传播模式智能识别技术的先验和辅助信息。     

斜向探测通信选频试验研究

文中提出了一种集探测、通信、选频一体化的试验方法,该方法将斜向探测与短波通信、干扰选频结合起来,实现了斜向探测的同时通过通信得到选频结果,文中对发射部分和接收部分的关键模块进行了研究,并开展了斜向探测通信选频试验,通过斜向探测电离图得到无干扰的可通频率,结合解码得到的干净频率,选出通信可用频率,试验结果证明了该方法的可行性。     

返回散射电离图传播模式的自动识别方法

提出了返回散射电离图传播模式的自动识别方法.介绍的方法仅基于返回散射电离图本身,结合电离层传播机理,无须人工干预,自动识别出一幅返回散射电离图存在哪几个反射层(E层、Es层和F层)的回波,根据层数采用不同的算法提取各个层的回波前沿.最后,又提出了利用垂测和斜测电离图辅助判读返回散射电离图的方法,能够提高返回散射电离图模式识别和前沿提取的正确率,具有较好的应用前景.     

基于HF返回散射和斜向探测的PD变换新方法

提出了基于实测返回散射电离图和斜向探测电离图及三维射线追踪技术综合处理的群路径P到地面距离D变换（简称PD变换）的坐标配准系数（kr）修正方法,采用“归一化”的思想,计算射线追踪技术合成的斜测电离图和实测斜测电离图的归一化频率对应的群路径差值,利用该差值,修正不同距离的合成的群路径,特别是能够对远区没有信标参考地区的坐标配准系数进行修正。仿真分析了临界频率和反射高度估计存在误差时“归一化”方法修正的有效性,从而验证了该方法能够有效地克服电离层参数估计不准对坐标配准系数的影响。     

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.     

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.     

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。     

A bang-bang PLL employing dynamic gain control for low jitter and fast lock times

Bang-bang phase detector based PLLs are simple to design, suffer no systematic phase error, and can run at the highest speed a process can make a working flip-flop. For these reasons designers are employing them in the design of very high speed Clock Data Recovery (CDR) architectures. The major drawback of this class of PLL is the inherent jitter due to quantized phase and frequency corrections. Reducing loop gain can proportionally improve jitter performance, but also reduces locking time and pull-in range. This paper presents a novel PLL design that dynamically scales its gain in order to achieve fast lock times while improving jitter performance in lock. Under certain circumstances the design also demonstrates improved capture range. This paper also analyses the behaviour of a bang-bang type PLL when far from lock, and demonstrates that the pull-in range is proportional to the square root of the PLL loop gain. Michael Chan received his bachelor degrees in Electrical Engineering and Computer Science from the University of Queensland in 2003. He is currently working towards his PhD at the same institution. His research interests include the design of high-speed clock and data recovery systems, and high speed phase locked loops. Adam Postula received the M.S. degree in electrical engineering from the Warsaw University of Technology, Poland, in 1974 and the Ph.D. degree in signal processing from the Poznan University of Technology, Poland, in 1981. He was an Electronic System Designer with ABB Sweden and a Researcher with the Royal Institute of Technology, Stockholm, Sweden, from 1983 to 1992. He led the development of high-level synthesis tools at the Swedish Institute of Microelectronics and was engaged in VHDL standardization in Europe. Since 1995, he has been a Senior Lecturer in the Department of Computer Science and Electrical Engineering, University of Queensland, Brisbane, Australia. His research interests include digital system design methodology, synthesis of digital systems, specialized processor architectures, and VLSI signal processing. Ding Yong received his PhD from University of London in electrical engineering in 1991. He was with National University of Singapore as a research scientist working in industrial research projects on data channel and servo-system for CD technology. In 1995, he joined VLSI design group of Western Digital as a principle engineer, where he was engaged in the IC design of Hard Disk Controller and CD-ROM Decoder and Controller. From 2000, he has been leading a mixed-signal design group as design manager and chief architect with Nano Silicon responsible for development of high-speed serial data transmission IPs. Lech Jóźwiak is an Associate Professor, Head of the Section of Digital Circuits and Formal Methods, at the Faculty of Electrical Engineering, Eindhoven University of Technology, The Netherlands. He received his M.Sc. and Ph.D. degrees in Electronics from the Warsaw University of Technology, Warsaw, Poland, in 1976 and 1982, respectively. From 1979 to 1986, he was a chief of two R&D teams in the Research Institute of Computers in Warsaw, and consultant to the United Nations Industrial Development Organization and industry. From 1986, he works mainly in the Netherlands, but also from time to time in USA, Canada, Australia, Belgium and Poland, combining advanced theoretical research with professional engineering practice and collaborating with industry, academia and governments. He is an author of a new information-driven approach to digital circuit synthesis, and new theories and methodologies of information relationships and measures, general decomposition and quality-driven design that have a considerable practical importance. He is also a creator of a number of practical products in the fields of application-specific (embedded) systems and EDA tools. His research interests include system, circuit, information and design theories and technologies, decision and optimization methodology, artificial intelligence, circuit and system design and EDA, re-configurable and massively parallel high-performance systems, embedded systems, and system dependability, analysis and validation. He is an author of more than 130 journal and conference papers and of some book chapters. He is a Director of EUROMICRO, co-founder and Steering Committee Chair of the EUROMICRO Symposium on Digital System Design, VIP in the IEEE International Symposium on Quality Electronic Design, program committee member of many other conferences, member of IEEE, EDAA, and of the Advisory Committee of the IEE Professional Network Embedded and Real-Time System Engineering. He is an advisor to the industry, Ministry of Economy and Commission of the European Communities in the fields of microelectronics, information technology, technology development and transfer, and SMEs.     

Toward Robust Speech Recognition and Understanding

The principal cause of speech recognition errors is a mismatch between trained acoustic/language models and input speech due to the limited amount of training data in comparison with the vast variation of speech. It is crucial to establish methods that are robust against voice variation due to individuality, the physical and psychological condition of the speaker, telephone sets, microphones, network characteristics, additive background noise, speaking styles, and other aspects. This paper overviews robust architecture and modeling techniques for speech recognition and understanding. The topics include acoustic and language modeling for spontaneous speech recognition, unsupervised adaptation of acoustic and language models, robust architecture for spoken dialogue systems, multi-modal speech recognition, and speech summarization. This paper also discusses the most important research problems to be solved in order to achieve ultimate robust speech recognition and understanding systems. Dr. Sadaoki Furui is currently a Professor at Tokyo Institute of Technology, Department of Computer Science. He is engaged in a wide range of research on speech analysis, speech recognition, speaker recognition, speech synthesis, and multimodal human-computer interaction and has authored or coauthored over 450 published articles. From 1978 to 1979, he served on the staff of the Acoustics Research Department of Bell Laboratories, Murray Hill, New Jersey, as a visiting researcher working on speaker verification. He is a Fellow of the IEEE, the Acoustical Society of America and the Institute of Electronics, Information and Communication Engineers of Japan (IEICE). He was President of the Acoustical Society of Japan (ASJ) from 2001 to 2003 and the Permanent Council for International Conferences on Spoken Language Processing (PC-ICSLP) from 2000 to 2004. He is currently President of the International Speech Communication Association (ISCA). He was a Board of Governor of the IEEE Signal Processing Society from 2001 to 2003. He has served on the IEEE Technical Committees on Speech and MMSP and on numerous IEEE conference organizing committees. He has served as Editor-in-Chief of both Journal of Speech Communication and the Transaction of the IEICE. He is an Editorial Board member of Speech Communication, the Journal of Computer Speech and Language, and the Journal of Digital Signal Processing. He has received the Yonezawa Prize and the Paper Awards from the IEICE (1975, 88, 93, 2003), and the Sato Paper Award from the ASJ (1985, 87). He has received the Senior Award from the IEEE ASSP Society (1989) and the Achievement Award from the Minister of Science and Technology, Japan (1989). He has received the Technical Achievement Award and the Book Award from the IEICE (2003, 1990). He has also received the Mira Paul Memorial Award from the AFECT, India (2001). In 1993 he served as an IEEE SPS Distinguished Lecturer. He is the author of “Digital Speech Processing, Synthesis, and Recognition” (Marcel Dekker, 1989, revised, 2000) in English, “Digital Speech Processing” (Tokai University Press, 1985) in Japanese, “Acoustics and Speech Processing” (Kindai-Kagaku-Sha, 1992) in Japanese, and “Speech Information Processing” (Morikita, 1998) in Japanese. He edited “Advances in Speech Signal Processing” (Marcel Dekker, 1992) jointly with Dr. M.M. Sondhi. He has translated into Japanese “Fundamentals of Speech Recognition,” authored by Drs. L.R. Rabiner and B.-H. Juang (NTT Advanced Technology, 1995) and “Vector Quantization and Signal Compression,” authored by Drs. A. Gersho and R. M. Gray (Corona-sha, 1998).     

Cover Picture: Biomineralized Polysaccharide Capsules for Encapsulation,Organization, and Delivery of Human Cell Types and Growth Factors (Adv. Funct. Mater. 6/2005)

The cover shows biomineralized polysaccharide capsules with specifiable make‐up, which can provide microenvironments for stabilization, growth, and differentiation of human cell types, as reported by Oreffo and co‐workers on p. 917. The capsules are amenable to complexation with a range of bioactive molecules and cells, offering tremendous potential as multifunctional scaffolds and delivery vehicles in tissue regeneration of hard and soft tissues. The construction of biomimetic microenvironments with specific chemical and physical cues for the organization and modulation of a variety of cell populations is of key importance in tissue engineering. We show that a range of human cell types, including promyoblasts, chondrocytes, adipocytes, adenovirally transduced osteoprogenitors, immunoselected mesenchymal stem cells, and the osteogenic factor, rhBMP‐2 (BMP: bone morphogenic protein), can be successfully encapsulated within mineralized polysaccharide capsules without loss of function in vivo. By controlling the extent of mineralization within the alginate/chitosan shell membrane, degradation of the shell wall and release of cells or rhBMP‐2 into the surrounding medium can be regulated. In addition, we describe for the first time the ability to generate bead‐in‐bead capsules consisting of spatially separated cell populations and temporally separated biomolecule release, entrapped within alginate/chitosan shells of variable thickness, mineralization, and stability. Such materials offer significant potential as multifunctional scaffolds and delivery vehicles in tissue regeneration of hard and soft tissues.     

卫星遥感温室气体的大气观测技术进展

全球、区域及城市的碳浓度、碳源汇信息是应对气候变化、达成双碳目标、完善国际谈判、支持治理政策制定与执行的重要依据。国际认可的“自上而下” 方法将卫星观测作为基础的通量计算技术, 是验证温室气体排放清单的重要手段。系统介绍了温室气体的卫星探测载荷原理、类别和发展, 以及反演、估算CO2、CH4 和N2O 的浓度和排放通量的方法, 还有探测缺失和误差存在的影响因素等; 分析了对卫星探测温室气体能力提高的迫切需求, 浓度反演和排放量估算精度不足, 以及N2O、氟化物等其他温室气体遥感研究缺乏、地基遥感验证能力薄弱等问题; 最后总结了我国温室气体卫星遥感技术的发展趋势, 主要是面向主被动高时空分辨率卫星的研制应用、高精度多尺度排放量估算(特别针对城市、小区域和点源尺度)、氟化物遥感评估等主题, 以加强对碳排放的量化观测, 并增强对碳循环的理解, 提高感知和应对气候变化的能力。     

Performance of a burst-frame-based CSMA/CA protocol: Analysis and enhancement

In this paper, we develop an analytical model to evaluate the delay performance of the burst-frame-based CSMA/CA protocol under unsaturated conditions, which has not been fully addressed in the literature. Our delay analysis is unique in that we consider the end-to-end packet delay, which is the duration from the epoch that a packet enters the queue at the MAC layer of the transmitter side to the epoch that the packet is successfully received at the receiver side. The analytical results give excellent agreement with the simulation results, which represents the accuracy of our analytical model. The results also provide important guideline on how to set the parameters of the burst assembly policy. Based on these results, we further develop an efficient adaptive burst assembly policy so as to optimize the throughput and delay performance of the burst-frame-based CSMA/CA protocol. Kejie Lu received the B.E. and M.E. degrees in Telecommunications Engineering from Beijing University of Posts and Telecommunications, Beijing, China, in 1994 and 1997, respectively. He received the Ph.D. degree in Electrical Engineering from the University of Texas at Dallas in 2003. In 2004 and 2005, he was a postdoctoral research associate in the Department of Electrical and Computer Engineering, University of Florida. Currently, he is an assistant professor in the Department of Electrical and Computer Engineering, University of Puerto Rico at Mayagüez. His research interests include architecture and protocols design for computer and communication networks, performance analysis, network security, and wireless communications. Jianfeng Wang received the B.E. and M.E. degrees in electrical engineering from Huazhong University of Science and Technology, China, in 1999 and 2002, respectively, and the Ph.D. degree in electrical engineering from University of Florida in 2006. From January 2006 to July 2006, he was a research intern in wireless standards and technology group, Intel Corporation. In October 2006, he joined Philips Research North America as a senior member research staff in wireless communications and networking department. He is engaged in research and standardization on wireless networks with emphasis on medium access control (MAC). Dapeng Wu received B.E. in Electrical Engineering from Huazhong University of Science and Technology, Wuhan, China, in 1990, M.E. in Electrical Engineering from Beijing University of Posts and Telecommunications, Beijing, China, in 1997, and Ph.D. in Electrical and Computer Engineering from Carnegie Mellon University, Pittsburgh, PA, in 2003. Since August 2003, he has been with Electrical and Computer Engineering Department at University of Florida, Gainesville, FL, as an Assistant Professor. His research interests are in the areas of networking, communications, multimedia, signal processing, and information and network security. He received the IEEE Circuits and Systems for Video Technology (CSVT) Transactions Best Paper Award for Year 2001, and the Best Paper Award in International Conference on Quality of Service in Heterogeneous Wired/Wireless Networks (QShine) 2006. Currently, he serves as the Editor-in-Chief of Journal of Advances in Multimedia, and an Associate Editor for IEEE Transactions on Wireless Communications, IEEE Transactions on Circuits and Systems for Video Technology, IEEE Transactions on Vehicular Technology, and International Journal of Ad Hoc and Ubiquitous Computing. He is also a guest-editor for IEEE Journal on Selected Areas in Communications (JSAC), Special Issue on Cross-layer Optimized Wireless Multimedia Communications. He served as Program Chair for IEEE/ACM First International Workshop on Broadband Wireless Services and Applications (BroadWISE 2004); and as a technical program committee member of over 30 conferences. He is Vice Chair of Mobile and wireless multimedia Interest Group (MobIG), Technical Committee on Multimedia Communications, IEEE Communications Society. He is a member of the Best Paper Award Committee, Technical Committee on Multimedia Communications, IEEE Communications Society. Yuguang Fang received a Ph.D. degree in Systems Engineering from Case Western Reserve University in January 1994 and a Ph.D. degree in Electrical Engineering from Boston University in May 1997. He was an assistant professor in the Department of Electrical and Computer Engineering at New Jersey Institute of Technology from July 1998 to May 2000. He then joined the Department of Electrical and Computer Engineering at University of Florida in May 2000 as an assistant professor and got an early promotion to an associate professor with tenure in August 2003 and to a full professor in August 2005. He has published over 200 papers in refereed professional journals and conferences. He received the National Science Foundation Faculty Early Career Award in 2001 and the Office of Naval Research Young Investigator Award in 2002. He has served on several editorial boards of technical journals including IEEE Transactions on Communications, IEEE Transactions on Wireless Communications, IEEE Transactions on Mobile Computing and ACM Wireless Networks. He have also been actively participating in professional conference organizations such as serving as The Steering Committee Co-Chair for QShine, the Technical Program Vice-Chair for IEEE INFOCOM’2005, Technical Program Symposium Co-Chair for IEEE Globecom’2004, and a member of Technical Program Committee for IEEE INFOCOM (1998, 2000, 2003–2007). He is a senior member of the IEEE.     

高效双光子引发剂及水相中制备水凝胶微结构的研究进展

对双光子引发剂的设计合成和飞秒激光双光子聚合技术的基本原理进行了简单介绍。着重介绍了用于水凝胶双光子聚合的引发剂的研究进展,主要包括通过扩大共轭链长度、引入强供/吸电子基团、加入共引发体系等来增大双光子吸收截面,引入自由基淬灭基团以降低荧光量子产率,增加引发剂的水溶性来降低微结构细胞毒性等方面。这些研究为生物相容性三维水凝胶微纳结构的制备及应用提供了科学基础,是更好地模拟体内细胞生长微环境的必要条件。接着,介绍双光子聚合制备的水凝胶微纳结构及其在组织工程领域中的应用。最后,对生物相容性水凝胶微结构在应用中存在的问题与未来发展趋势进行总结和展望。     

On Fixed-Mobile Network Convergence

As the convergence in digital industry takes shape, the digital networks, both wireline and wireless, are also converging to offer seamless services and enhanced experience to the user. With the arrival of the mobile Internet the mobility is also moving into new areas, e.g., imaging, games, video, multimedia, and across different types of networks. In this paper we explore why, what, and how of the network convergence, and identify how the industry viewpoints align and differ. We also identify the key barriers to achieving true network convergence. We then discuss the role of the Internet Protocol (IP) as the common thread that enables network convergence, and the key industry and standards initiatives to actually provide solutions and the equipment to implement a cost-efficient and high performance converged network. Sudhir Dixit joined Nokia Research Center in 1996, where he is currently a Research Fellow and works on next generation wireless networks. From 1996 to 2003 he was a Senior Research Manager, focusing on IP/ATM, wireless, content networks, and optical networks. Prior to that he worked at NYNEX Science & Technology (now Verizon), GTE (now Verizon), Codex Motorola, Wang, Harris, and STL (now Nortel Europe Labs). He has published or presented over 150 papers, published three books, and holds 14 patents. He is on the Editorial Board of the IEEE Communications Magazine, Springer's Wireless Personal Communications Journal, and KIC's Journal of Communications and Networks. He received a B.E. degree from MANIT, Bhopal, India, an M.E. degree from BITS, Pilani, India, a Ph.D. degree from the University of Strathclyde, Glasgow, Scotland, and an M.B.A. degree from Florida Institute of Technology, Melbourne. He is a Fellow of IEE (UK) and IETE (India). He represents Nokia on the Steering Board of the Wireless World Research Forum, and is also Chair of the SIG on Self-Organization of Wireless World Systems.