Biomedical Engineering Education: Enrollment, Courses, Degrees, and Employment

During the 1979-1980 academic year a two-page questionnaire on biomedical engineering education was sent to 251 engineering schools. 71 schools indicated that they had degree programs and an additional 35 indicated that they had official minor or option programs, 107 did not have a program, and 38 did not respond. For schools offering degrees in biomedical engineering, there were 2859 students enrolled in 37 B.S. programs, 830 students in 48 M.S. programs, and 469 students in 41 Ph.D. programs. Options or minors in biomedical engineering with a degree in another engineering discipline were available at the B.S. level at 41 schools, at the M.S. level at 42 schools, and at the Ph.D. level at 34 schools. Over the past two years, schools offered 109 courses in biomedical instrumentation, 74 in computers in medicine, 162 in physiological systems/modeling, 60 in biomechanics, 47 in biomaterials, 33 in hospital internship, 23 in clinical engineering, 9 in biomedical engineering lab, and 67 in other areas. During the academic year 1978-1979, schools awarded 464 B.S. degrees, 249 M.S. degrees, and 107 Ph.D. degrees in biomedical engineering. Of these graduates, 253 found jobs in industry, 23 in government, 35 in academia, and 66 in hospitals or clinics; 100 went to medical school, 96 to biomedical engineering graduate schools, and 57 to other graduate or professional schools.     

我国边缘群体科普公正问题研究

本文分析了我国流动人口、妇女、残疾人、农村人口、贫困人群等科普边缘群体的状况和成因,指出科普边缘群体低层次的科学素养和知识习得状况暴露了严重的科普公正问题,政府和社会在国家科普政策和关注重心、科普资源分配、具体的科普实践和科普实效三方面缺乏或者难以实现科普公正,最后提出了4条实现科普公正的建议。     

Wave propagation and scattering in random media and rough surfaces

The author presents a comprehensive review highlighting historical as well as new developments in the area of random media. Both discrete and continuous media are considered as well as rough surfaces. The author discusses wave propagation in turbulence and in a random continuum where the refractive index is a random function of space and time. Examples are optical propagation in the atmosphere, microwaves in the troposphere, ionosphere, planetary atmosphere, and solar wind, and acoustic scattering in ocean turbulence. The author describes multiple scattering by random distributions of discrete scatterers. Examples are optical and microwave scattering by rain, fog, smog, snow, ice particles, and vegetation, optical and ultrasound scattering by tissues and blood, optical and acoustic scattering in the ocean, and scattering in composite materials. Scattering by rough surfaces and interfaces is discussed. Examples are acoustic scattering by ocean surfaces, microwave and optical scattering by vegetation, terrain, and snow cover, and ultrasound scattering by rough interfaces in biological media     

The internationalization of engineering education: a tale of two countries

Two international exchange programs in engineering between universities in Japan and Canada, are described in order to explain the significant benefits gained by the undergraduate and graduate students, as well as the academic staff who participate, and to highlight key principles generally followed in the design and execution of exchange programs. One notable and successful engineering exchange program is between the University of Waterloo, located in Southern Ontario, Canada, and Tottori University in Japan, while the other is between the University of Waterloo and Kyoto University in Japan. Both of these programs include foreign students taking courses for credit or audit at the host university, and, for the case of graduate students, also receiving guidance in their research. Moreover, upon completion of one academic semester in Japan, all of the undergraduate Waterloo students studying at Tottori University are employed in Japanese industry for three to four months before returning to Canada. Of paramount importance to the education of the participating undergraduate and graduate students is the opportunity to learn, by first-hand experience, the language and culture of a foreign country. In fact, one of the key findings of a survey completed by Canadian and Japanese students who took part in the exchange programs, is that living in a different culture greatly enhanced their own personal development. The addition of this international perspective to a solid education in engineering opens many doors of opportunity for exchange program alumni, who are well prepared to fully participate in the global marketplace of the 21st century, and to assist society in responsibly reaching an equitable and sustainable future.     

Channel Estimation by Using Short Training Sequences in CDMA Systems

Multiuser detection techniques are known to be effective to counter the presence of multiuser interference in code division multiple access channels. Multiuser detectors can provide excellent performance only when the channel impulse responses of all the users are precisely known. Hence, channel estimation becomes a challenging issue in mobile communication systems. In this paper, we address the problem of efficient maximum likelihood mobile radio channel estimation at high channel efficiency that requires a short training sequence along with the known spreading sequence. The proposed system can be employed in both the uplink and downlink of a heavily loaded multiuser CDMA system. The extension of the approach with unknown users' delays are also proposed. We present results that show the success of this method in recovering the transmitted bits with a relatively small number of preamble bits. Ahmet Rizaner was born in Larnaca, Cyprus, on January 31, 1974. He received the B.S. and M.S. degrees in Electrical and Electronics Engineering from the Eastern Mediterranean University, Famagusta, North Cyprus, in 1996 and 1998, respectively. He completed his PhD. degree in Electrical and Electronic Engineering in Eastern Mediterranean University and joined Eastern Mediterranean University as a lecturer in 2004. He is lecturing in the School of Computing and Technology. His main research interests include CDMA communications, adaptive channel estimation, and multiuser detection techniques. Hasan Amca was born in 1961 in Nicosia-Cyprus. He graduated from the Higher Technological Institute in Magosa-Cyprus (which is renamed later as Eastern Mediterranean University). He joined EMU in 1985 after receiving a M.Sc. (Digital Signal Processing) degree from the University of Essex in England (1985). He took his Ph.D. (Mobile Communications) from the University of Bradford where he was on a Commonwealth scholarship. He has been teaching in the Electrical and Electronic Engineering Department of Eastern Mediterranean University since 1993 where he also served as the vice chairman from Spring 1998 to Spring 2000. He has been appointed as the Director of the School of Computing and Technology of the EMU since Spring 2000. His research interests include Multi User Detection of CDMA signals, Adaptive Equalisation, Multi Carrier Systems, Mobile Radio Systems and Networks, Internet and Information Technology Applications in Education. Kadri Hacıoğlu was born in Nicosia, Cyprus. He received the B.Sc., M.Sc., and Ph.D. degrees in electrical and electronic engineering from the Middle East Technical University, Ankara, Turkey, in 1980, 1984, and 1990, respectively. After his two-year military service, in 1992, he joined the faculty of Eastern Mediterranean University, Magosa, North Cyprus, as an Assistant Professor, and became an Associate Professor in 1997. While there, he taught several classes on electronics, digital communications, speech processing and neural networks. During this time, he conducted research on applying fuzzy logic, neural networks, and genetic algorithms to signal processing and communications problems. From 1998 to 2000, he was a Visiting Professor in the Department of Computer Science, University of Colorado, Boulder. Here, he taught classes on neural networks and continued his research. Since 2000, he has been a Research Associate at the Center for Spoken Language Research, University of Colorado. He has authored or coauthored numerous papers and supervised a dozen M.Sc./Ph.D. theses. His current research interests are concept-based language modeling, speech understanding, natural language generation, and search methods in speech recognition/understanding. He also does research on multiuser detection and equalization in CDMA systems. Ali Hakan Ulusoy was born in Eskişehir, Turkey, on June 3, 1974. He graduated from the double major program of the department of Electrical and Electronic Engineering and department of Physics in Eastern Mediterranean University as the first rank student of Faculty of Engineering in 1996. He received his M.S. degree in Electrical and Electronic Engineering in Eastern Mediterranean University in 1998. He completed his PhD. degree in Electrical and Electronic Engineering in Eastern Mediterranean University and joined Eastern Mediterranean University as a lecturer in 2004. He is lecturing in the School of Computing and Technology. His current research interests include receiver design, multi-user detection techniques, blind and trained channel estimation in Code Division Multiple Access (CDMA).     

Thyristor Input-Protection Device Suitable for CMOS RF IC’s

Based on simulation results and accompanying analysis, we suggest a thyristor-type ESD protection device structure suitable for implementation in standard CMOS processes to reduce the parasitic capacitances added to the input nodes, which is very important in CMOS RF ICs. We compare DC breakdown characteristics of the suggested device to those of a conventional NMOS protection device to show the benefits of using the suggested device for ESD protection. The characteristic improvements are demonstrated and the corresponding mechanisms are explained based on simulations. Structure dependencies are also examined to define the optimal structure. AC simulation results are introduced to estimate the magnitude of reduction in the added parasitic capacitance when using the suggested device for ESD protection. The analysis shows a possibility of reducing the added parasitic capacitance down to about 1/45 of that resulting with a conventional NMOS protection transistor, while maintaining robustness against ESD.Jin-Young Choi was born in Seoul, Korea in 1956. He received the B.S. degree in electrical engineering from the Seoul National University, Korea, in 1979, and the M.S. and Ph.D. degrees in electrical engineering from the University of Florida, USA, in 1986 and 1991, respectively. In 1991, he joined Samsung Electronics Memory Division, Korea, where he was engaged in high-speed SRAM development. In 1992, he moved to the Hongik University, Jochiwon, Korea, where he is now an associate professor. His recent research interests include the high-frequency modeling of CMOS devices, CMOS RF circuit design, and analysis & design for ESD protection.Woo Suk Yang was born in Seoul, Korea in 1957. He received the B.S. degree in electrical engineering from the Seoul National University, Korea, in 1979, and the Ph.D. degree in electrical and computer engineering from the North Calorina State University, USA, in 1990. His doctorial research was in the area of signal processing. In 1990, he joined LG Electronics Co. Korea. In 1991, he moved to the Hongik University, Jochiwon, Korea, where he is now a professor. His recent research interests include the high-frequency modeling and various topics in signal processing area.Dongmin Kim was born in Korea in 1956. He received the B.S. and M.S. degrees in electrical engineering from the Seoul National University, Korea, in 1979 and 1984, respectively and the Ph.D. degree in ECE from the University of Michigan, USA, in 1996. Now, he is an assistant professor of the Hongik University, Jochiwon, Korea. His recent research interests include circuit design and analysis.Youngju Kim was born in Seoul, Korea in 1957. He received the B.S. and M.S. degrees in electrical engineering from the Seoul National University, Korea in 1980 and 1985, respectively and the Ph.D. degree in electrical engineering from the Polytechnic University of New York, USA, in 1995, respectively. In 1996, he joined the Hongik University, Jochiwon, Korea, where he is now an assistance professor. His recent research interests include the RF circuit design and LIN wireless systems.     

Theory and application of wave propagation and scattering in random media

This paper presents a review of basic theories and recent advances in the studies of wave propagation and scattering in random media. Examples of the random media include the atmosphere, the ocean, and biological media whose characteristics are randomly varying in time and space. The study of electromagnetic, optical, and acoustic waves in such media has become increasingly important in recent years in the areas of communication, detection, and remote-sensing. Topics covered in this paper are divided into "waves in randomly distributed scatterers," "waves in random continua," and "remote-sensing of random media." Transport theory with various approximate solutions and multiple scattering theories are discussed and their relationships are clarified. Included in the analyses are propagation characteristics of intensities, wave fluctuations, pulse propagation and scattering, coherence bandwidth, and coherence time of communication channels through random media. Remote-sensing techniques include recent advances in the use of inversion techniques to deal with ill-posed problems.     

我国发展低碳建筑存在的主要问题及对策研究

近年来,全球气候持续恶化,环境问题日益严重,低碳节能已成为世界各国普遍关注的热点问题,自2009年＂哥本哈根气候大会＂以来,在我国,低碳减排的思想逐渐深入人心,而低碳建筑作为建筑领域的理想建筑,其发展将成为大众趋势,但低碳建筑在我国的发展一直较为缓慢。通过对发展低碳建筑的必要性进行有效论证,总结其发展过程中存在的主要问题,最后给出我国发展低碳建筑的具体对策建议,可以为政府制定相关的政策提供部分建议,促进低碳建筑在我国顺利、快速、平稳地发展,为我国节能减排做出一定贡献。     

Effects of Defects on the Thermal and Optical Performance of High-Brightness Light-Emitting Diodes

Defects in terms of voids, cracks, and delaminations are often generated in light-emitting diodes (LEDs) devices and modules. During various manufacturing processes, accelerated testing, inappropriate handling, and field applications, defects are most frequently induced in the early stage of process development. One loading is due to the nonuniform loads caused by temperature, moisture, and their gradients. In this research, defects in various cases are modeled by a nonlinear finite-element method (FEM) to investigate the existence of interfaces, interfacial open and contacts in terms of thermal contact resistance, stress force nonlinearity, and optical discontinuity, in order to analyze their effects on the LED's thermal and optical performance. The simulation results show that voids and delaminations in the die attachment would enhance the thermal resistance greatly and decrease the LED's light extraction efficiency, depending on the defects' sizes and locations generated in packaging.     

一种基于时间序列的动态加密方法

加密技术在通信系统中有着广泛的应用,由于信道等环境的制约,所以对称加密方法更适合保密通信,尽管其有稳定性和安全性不够好,密钥生成单一,易破解等缺陷,特别是密钥的生成、管理方面的不足。为解决传统对称加密中密钥生成、保存、传输安全性不高的缺点,提出了一种基于时间序列的动态密钥生成方法用于信息加解密,以保证密钥的安全性,最后通过试验验证算法的可行性和稳定性。     

J-Sim: a simulation and emulation environment for wireless sensor networks

Wireless sensor networks have gained considerable attention in the past few years. They have found application domains in battlefield communication, homeland security, pollution sensing, and traffic monitoring. As such, there has been an increasing need to define and develop simulation frameworks for carrying out high-fidelity WSN simulation. In this article we present a modeling, simulation, and emulation framework for WSNs in J-Sim - an open source, component-based compositional network simulation environment developed entirely in Java. This framework is built on the autonomous component architecture and extensible internetworking framework of J-Sim, and provides an object-oriented definition of target, sensor, and sink nodes, sensor and wireless communication channels, and physical media such as seismic channels, mobility models, and power models (both energy-producing and energy-consuming components). Application-specific models can be defined by subclassing classes in the simulation framework and customizing their behaviors. We also include in J-Sim a set of classes and mechanisms to realize network emulation. We demonstrate the use of the proposed WSN simulation framework by implementing several well-known localization, geographic routing, and directed diffusion protocols, and perform performance comparisons (in terms of the execution time incurred and memory used) in simulating WSN scenarios in J-Sim and ns-2. The simulation study indicates the WSN framework in J-Sim is much more scalable than ns-2 (especially in memory usage). We also demonstrate the use of the WSN framework in carrying out real-life full-fledged Future Combat System (FCS) simulation and emulation.     

A Constraint Formulation for Minimum-Energy Multicast Routing in Wireless Multihop Ad-hoc Networks

Energy conservation is a critical issue in wireless multihop ad-hoc networks, which have nodes powered by batteries only. One major metric for energy conservation is to route a communication session along the routes that require the lowest total energy consumption. To do this, we introduce in this paper a new concept called Virtual Relay. Based on this new concept, we present a constraint formulation for the minimum-energy multicast routing problem in terms of mixed integer linear programming. Experiment results show that in a typical multihop ad-hoc network with 50 nodes, the optimal solutions can always be solved in a timely manner, and it also provides a way to evaluate the realistic performance of different heuristic algorithms. Song Guo received the B.S. degree in computer science from Huazhong University of Science and Technology, Wuhan, China, in 1995 and the M.S. degree in electrical and computer engineering from Beijing University of Posts and Telecommunications, Beijing, China, in 1998. Since 2001 he has been a Ph.D. student in the School of Information Technology and Engineering at University of Ottawa, Canada. His main research interests lie in mobile ad-hoc routing protocols and algorithms, power-aware design and optimization for ad-hoc wireless networks, and performance evaluation. Oliver Yang is a Professor in the School of Information Technology and Engineering at University of Ottawa, Ontario, Canada. Dr. Yang received his Ph.D. degree in Electrical Engineering from the University of Waterloo, Ont., Canada in 1988. He has worked for Northern Telecom Canada Ltd. and has done various consulting. His research interests are in modeling, analysis and performance evaluation of computer communication networks, their protocols, services and interconnection architectures. The CCNR Lab under his leadership has been working on various projects in the traffic control, traffic characterization, switch architecture and traffic engineering issues in both wireless and photonic networks. This has been reported in more than 200 technical papers. Dr. Yang is also interested in queuing theory, simulations, computational algorithms and their applications such as reliability and traffic analysis. Dr. Yang is currently the editor of IEEE Communication Magazine.     

基于校园网的虚拟电工实验模式的研究

电工实验是大学电路理论、电工技术基础课程教学中必不可少的一环。针对传统开设的实验课程中存在实验仪器陈旧,教学方法单一,学生缺乏学习主动性和创造性等问题,结合培养应用型人才的目标,本文研究了基于校园网虚拟电工实验教学的新模式。该模式将仿真设计与实际操作、虚拟仪器技术和网络技术结合,进行网上虚拟电工实验,实验结果和设计内容可以在校园网上发布。文中详细介绍了这一模式的具体内容和实验方式。该实验模式充实了我校电工实验手段,提升了电工实验水平,激发了学生的实验兴趣,为培养应用型人才打下良好基础。     

Congestion due to Rate Variations in cdma2000 Data Networks

In order to support high data rate requirements and effectively manage the scarce wireless resources, additional bandwidth channels are allocated and taken away from mobile stations in 3G wireless data networks quite frequently. A TCP sender connected to the mobile, on seeing ACKs coming at a faster pace after additional bandwidth allocation, turns overtly optimistic and injects data into the network at a rate that might be excessive for an intermediate router, thereby leading to loss of multiple packets and subsequent prolonged recovery and periods of underutilization. In this work, we characterize this problem using an analytical model for losses based on continuous flow approximation as well as an extensive simulation setup. We also illustrate how bandwidth oscillations create more severe congestion than an increase in number of users to the extent that even RED algorithm is unable to check the sharp growth of queues. As a result, multiple packets are lost in a droptail fashion. We further demonstrate the dependence of congestion due to bandwidth allocation on the time during which mobiles' rates are increased and observe the degradation in performance for typical load scenarios. We also try to identify the boundary for stable operation of RED and finally present some possible methods for improving the performance. Vikas Paliwal graduated with a Bachelor of Technology degree in Electrical Engineering from IIT (Indian Institute of Technology), Kanpur, India and an M.S. in Systems and Computer Engineering from Carleton University, Ottawa, Canada. He has five years of research and work experience in telecommunications area in a variety of work environments across the globe. During his under-graduation he worked on a research project in micro-electronics area with IMS Research Labs, Hanover, Germany, and developed some innovative algorithms for circuit schematics and layouts. After graduating from IIT, Vikas was the core Engineering and Marketing Consultant for GMG Telecom Consultants India Limited, New Delhi, India, and helped GMG in developing a level of technical expertise in the areas of security systems that resulted in key research projects from firms such as ADT and Honeywell. Later, as part of his Masters research at Carleton University, Ottawa, Canada, Vikas worked on performance analysis of CDMA data networks and queue management techniques that resulted in five research papers in various academic journals/conferences. His Masters research project also attracted the interest of Nortel Networks, Ottawa, Canada, and helped in starting joint research projects in the area of wireless systems simulation, which was of particular interest to Nortel. Vikas then worked with Solana Networks, Ottawa, on network topology detection and on products that improve the performance of mission-critical IP networks and wireless LANs. This was followed by a year of work with Qualcomm, UK, on modem software design and implementation for Qualcomm's 3G chipsets. Currently he works with Qualcomm Inc., San Diego, CA, on physical layer of WCDMA and HSxPA systems. At Qualcomm, he continues his research activities in advanced wireless systems design and implementation by actively participating in various technical forums and conducting several training/discussion sessions on UMTS systems. Ioannis Lambadaris was born in Thessaloniki, Greece. He received a diploma in Electrical Engineering from the Polytechnic School of the Aristotle University of Thessaloniki in 1984. He was a recipient at a Fulbright Fellowship (1984–1985) for graduate studies in USA. He received a M.Sc. degree in Engineering from Brown University, Providence, RI, USA in 1985 and a Ph.D. degree in Electrical Engineering from the University of Maryland, College Park, MD, USA in 1991. He was employed as a research associate at Concordia University, Montreal, Quebec, Canada, in 1991–1992. Between September 1992 and July 1997 he has been an Assistant Professor in the Department of Systems and Computer Engineering at Carleton University, Ottawa, Ontario, Canada. Currently he is an associate professor in the same department and a member of IEEE. While at Carleton he received the Premier %92\,s Research Excellence Award (2000), and the Carleton University Research Excellence Award (2000–2001) for his research achievements in the area of modeling and performance analysis of computer networks. Professor Lambadaris' interests lie in the area of applied stochastic processes, stochastic control, queuing theory and their application for modeling and performance analysis of computer communication networks. His current research concentrates on quality of service (QoS) control for IP networks, resource allocation in optical networks, and optimal routing and flow control in ad-hoc wireless systems. Biswajit, a co-founder of Solana Networks, has15 years of experience in the area of data communication. He has worked at Nortel Networks, Bell Northern Research, Tropic Networks and Belair Networks. The primary focus of his work has been in the area of IP networking protocols and architecture. As an Independent Contributor at Nortel Networks, he spearheaded various advance technology programs and R&D projects in IP networking. He worked as a Network Architect with the MPLS team and as a member of the architecture team at Tropic Networks to address complex optical networking issues. He worked as a System Architect on WLAN mesh networking products at BelAir Networks. Dr. Nandy has a PhD in Electrical and Computer Engineering from the University of Waterloo and has been an Adjunct Research Professor with Systems and Computer Engineering at Carleton University since 2001. He holds an M.Tech in Electrical Engineering from Indian Institute of Technology, Kanpur and a B.E. in Electronics and Telecommunication Engineering from Jadavpur University, Calcutta. He has authored and presented over 25 research papers in International conferences and holds 12 US patents. He has actively participated in various Work Groups in IETF and author of several IETF proposals in the form of Internet Drafts and RFC.     

Analog behavioral modeling by multi-companding and wavelet collocation method

In this paper, we develop a wavelet collocation method with multi-companding for behavioral modeling of analog circuits. In the multi-companding procedure, the nonlinear companding algorithm is developed to control the error distribution continuously, while the adaptive scheme is employed to reduce the number of used wavelets. Consequently, the proposed multi-companding algorithm can not only modify the modeling error distribution continuously but also decrease the number of basis functions efficiently. Moreover, the companding function generation is automatic and can be applied for the behavioral modeling of any analog circuits. Jun Tao received the B.S degree in electrical engineering from Fudan University, China, in 2002. Now she is currently working toward the Ph.D. degree in micro-electronic engineering at the Fudan University. Her research interest includes analog behavioral modeling, analog circuit simulation and DFM. Xuan Zeng (M97) received the B.Sc. and Ph.D. degrees in electrical engineering from Fudan University, Shanghai, China, in 1991 and 1997, respectively. She joined the Electrical Engineering Department, Fudan University in 1997 and became a full professor in Microelectronics Department in 2001. Now she serves as the Vice Director of ASIC & System State key Lab. and the Associate Head of Microelectronics Department Fudan University. She was a visiting professor in the Electrical Engineering Department, Texas A&M University, USA and Microelectronics Department of TU Delft, Netherland in 2002 and 2003 respectively. Her research interests include DFM, analog and mixed signal design automation (behavioral modeling, circuit simulation and analog layout generation), high speed interconnect analysis and design and ASIC design. Dr. Zeng received the Cross-Century Outstanding Scholar Award from the Ministry of Education of China in 2002. She was selected into “IT Top 10” in Shanghai China in 2003. She served in the technical program committee of IEEE/ACM ASP-DAC in 2000 and 2005. Dian Zhou received the B.S degree in physics and M.S degree in electrical engineering from Fudan University, China, in 1982 and 1985, respectively, and the Ph.D. degree in electrical and computer engineering from the University of Illinois in 1990. He joined the University of North Carolina at Charlotte as an assistant professor in 1990, where he became an associate professor in 1995. He joined the University of Texas at Dallas as a full professor in 1999, and joined Fudan university as a Changjiang Professor in 2003 (on-leave from the University of Texas at Dallas). Currently, he serves as the dean of Microelectronics School, director of National Key Lab. on ASICs and Systems, and director of Miro-nano-electronics Innovation Platform at Fudan University. His research interests include: High-speed VLSI systems, CAD tools, mixed-signal ICs, and algorithms. Charles Chiang received his Bachelor degrees from the Department of Political Science, Tunghai University at Taichung, Taiwan in 1980, and Department of Computer Science, New Mexico State University, Las Cruces, New Mexico in 1986. Then he had his Masters and Ph.D. degree from the Department of Electrical Engineering and Computer Science, Northwestern University, Illinois in 1988 and 1991, respectively. After working at IBM and EDA companies for 10 years, he joined the Advanced Technology Group at Synopsys, Inc. in 2001. His research interests include routing, placement, floorplan, and signal integrity. His main research focus is now on design for manufacturability (DFM). Dr. Chiang has been a Senior Member of IEEE since 1998. He received the Superior Design Recognition award and the ADAL award from IBM Rochester in 1993 and 1994, respectively. He is one of the top 15 winners with new patent filing in 2005 and 2006 in Synopsys. He has served on the technical committee of ICCAD from 2004 to 2006, on that of Field Programming Logic (FPL) from 2002 to 2003, as well as on the committee of ASP-DAC in 2007. He has published more than 40 technical papers and filed 10 US patents.     

虚拟现实技术在高校计算机教学中的应用

虚拟现实技术是一种模拟现实环境的计算机技术，近年来其在教学中得到了广泛应用。在高校计算机教学中应用虚拟现实技术，不仅可以节约教学成本，还能满足学生的差异化需求。高校计算机教学涉及的内容专业性强，且较为抽象，传统教学存在情境单一、互动不足、方法僵化等问题。虚拟现实技术的应用推动了高校计算机教学的创新，丰富了教学手段，对推动高校计算机教学的发展具有重要意义。文中分析了虚拟现实技术的特点，并探究了虚拟现实技术在高校计算机教学中的应用。     

Superconducting magnets and their applications

Since the discovery of superconductivity almost a century ago, there has been a steady increase in the variety of superconducting magnet applications. Progress in superconducting magnet technology has resulted in applications in areas of basic science, medicine, separation, and levitation. Performance improvements in a variety of materials, from low-temperature to high-temperature superconductors, are the foundation of recent rapid development. In addition, large increases in affordable computing power, along with steady refinement of three-dimensional analytical tools and improved materials characterization, have allowed many more advanced magnet concepts to be realized directly in hardware without scale prototype testing than was previously possible. This in turn has broadened opportunities for new science and technology results in many fields including the basic sciences, medical imaging, fusion, environmental remediation, and transportation. In this paper, a few examples of these applications will be discussed, representing a range in magnetic field, current density, and overall size, from the practical to the developmental.     

光通信地面网络候选站址的大气信道特性统计检验

激光通信地面站址的大气信道特性决定着设备性能的有效发挥。选择四个候选站址,西藏阿里、青海德令哈、四川稻城和河北兴隆,统计检验云量覆盖、大气透过率、天空辐射度和大气湍流等特征对激光通信的影响。结果显示,单站可用度条件以阿里为最佳；三站联合可用度以阿里-德令哈-兴隆最好,在少云条件下(云量低于60%)全年可用度85%以上;少云条件下的四站联合可用度在5~8月为91\%~96\%,其它月份98%以上。四个候选站址的大气光学特性均能满足激光通信传输的要求。高海拔站址的大气透过率与辐射度有明显优势,阿里、稻城的夜间大气相干长度在10 cm以上,德令哈在8~12 cm间, 兴隆站在6 cm以上。在多站联合模式下应能在高海拔的少云区选择出足够高可用度的站址。     

京西生态涵养区日照时数变化特征及影响因素

为详细了解京西生态涵养区日照情况, 利用北京市门头沟、斋堂两个国家气象站 1975–2019 年逐日总云量、 低云量、降水日数、相对湿度、日照时数等资料, 采用气候倾向率、 Mann-Kendall 检验等方法分析了京西生态涵养 区日照时数时空变化特征及其与各气象要素之间的相关性。结果表明: 在 1975–2019 年间, 京西生态涵养区年、月、 日日照时数均呈西部山区多、东南平原少的特征, 且两站日日照时数呈显著相关性, 约 80% 的差值在 −2∼2 h 范围。 其中月均日照时数峰值出现在 4–5 月, 谷值出现在 11–12月, 6 月、 9–10 月减少趋势最明显; 四季日照时数分布较均匀, 但呈春季多、冬季少的特征; 2002–2010 年年日照时数连续低于均值, 东南平原区减少趋势 [−51.6 h·(10a)−1] 大于西部 山区 [−39.5 h·(10a)−1]。年、四季日照时数异常偏少情况主要出现在 2000 年以后, 接近异常偏多年份在 20 世纪 80–90 年代较集中。 1982–1990 年日照时数明显增加, 1991 年发生明显减少突变, 1991–2019 年日照时数明显减少。综合分 析表明该地区的日照时数与总云量、低云量、日平均湿度、日降水量呈负相关, 与日分钟风速、能见度呈正相关, 该 结论对首都京西生态涵养区建设和气候评价具有重要参考价值。     

木薯块根膨大初期淀粉体形态及发育的扫描电镜观察

对华南木薯3个品种（SC124、SC8、Arg7）膨大初期的木薯块根淀粉体的大小、形态、分布排列和发育等特性进行了扫描电镜观察。结果表明：淀粉主要沉积在木薯块根的次生韧皮部和木质部的薄壁细胞中。木薯块根淀粉体形态品种间没有明显差异,主要为球形,常见有椭球体、不规则的半球体、多极球体等形态,但淀粉体大小及空间排列在3个品种间差异显著。SC124淀粉体平均直径最小,淀粉体的变异系数大,淀粉体间空隙较大,呈层状排布;SC8淀粉体大小较为一致,变异系数小,淀粉体排列紧密,呈束状排布;Arg7淀粉体大小及变异系数都较小,淀粉体排列较为疏松,成团状排布。结论：淀粉体的大小、形态、空间排列及增殖方式可能是影响木薯块根淀粉充实程度和品质特性直接原因。