Improved LUT Technique for HPA Nonlinear Pre-Distortion in OFDM Systems

In this paper, we focus on the Look-up Table (LUT) technique for the compensation of HPA nonlinear distortion. An improved LUT method is proposed with better performance compared with conventional LUT technique in terms of convergence speeds, BER and total degradation (TD). It can get over 8 dB gain in out-of-band spectrum re-growth suppression and about 0.3 dB BER performance gain than conventional LUT technique with the same iteration times. Also, we propose an actual application of HPA with pre-distorter in OFDM transmitter. Ai Bo was born in Shannxi Province in China on February 7, 1974. He received a BSc. Degree from Engineering Institute of Armed Police Force in 1997, a Master and Dr. degree from Xidian University in 2002 and 2004 in China respectively, and now working as a post dr. in Dept. of E&E, state of key lab. on microwave and digital communications in Tsinghua University in China. He has once participated in the key research project on HDTV in TEEG (Team of Engineering Expert Group) of China. He is an editorial committee member of journal of “Computer Simulations”, “Information and Electronic Engineering”, an IEEE member and a senior member of Electronics Institute of China (CIE). He has published over 60 scientific papers in his research area till now. His current interests are the research and applications of OFDM techniques with emphasis on synchronization and HPA linearization techniques. Yang Zhi-Xing graduated from Tsinghua University, P.R. China in 1970. He is now a Professor and Deputy Director of State Key Lab. on Microwave and Digital Communication at the Department of Electronic Engineering and the Director of the DTV R&D Center in Tsinghua University. As a DTV technical expert for the Chinese government, Professor Yang has also been a member of the DTV standardization Committee of China and a leader of the DTV Standardization Harmonizing Group in Ministry of Information Industry of China. His major research interests include broadband information transmission technologies and DTV broadcasting systems. Pan Chang-Yong received the B.S. and M.S. degrees from the Department of Electronic Engineering in Tsinghua University, P.R. China, in 1996 and 1999, respectively. He is now an associate professor in the Department of Electronic Engineering and a member of the DTV R&D Center in Tsinghua University. His research interests are in the areas of broadband wireless transmission systems and satellite communications. Zhang Tao-Tao was born in Shandong Province in China in 1982, he received BSc. degree from Tsinghua University in 2004 and now pursing his Master degree in Dept. of E&E, state of key lab. on microwave and digital communications in Tsinghua University in China. His research interests is the power amplifier linearization techniques. Wang Yong was born in Shannxi Province in China in 1976. He received a BSc., a Master and a Dr. Degree from Xidian University in China in 1997, 2002 and 2005, respectively, and now is an associate professor in Xidian University. He has once participated in the key research project on HDTV in TEEG (Team of Engineering Expert Group) in China and is an IEEE Member. His interests are broadband multimedia communications. Ge Jian-Hua was born in September, 1961 in JiangSu Province in China. He received the B.Sc., Master and Ph.D. degree from Xidian University in 1982, 1985 and 1989, respectively. He is now the professor in both Xidian University in Xi’an and Shanghai Jiaotong University in Shanghai. He is the senior member of Chinese Electronics Institute. He has won lots of scientific and technical prizes in China and published many papers. His interests are transmission communications and web security.     

中国地区云量和云光学厚度的分布与变化趋势

利用最新的1983~2009年国际卫星云气候计划（ISCCP） D2月平均资料集,得到了中国地区总云量、低云量、中云量、高云量与云光学厚度的分布与变化趋势,结果表明：中国总云量和中云量呈现南多北少的分布,青藏高原地区高云量较大而低云量很小;总云量和中云量在东部呈增加趋势,西部呈减小趋势,低云量和高云量在大部分地区呈减小趋势。从不同季节来看,春季和秋季北方总云量增加,西部总云量减小;夏季大部分地区总云量增加,冬季大部分地区总云量减少。云的光学厚度呈现南多北少的分布,且在大部分地区呈增加趋势。同时利用中分辨率成像光谱仪（MODIS）资料分析了2001~2013年间中国不同污染地区总云量与云光学厚度的分布及变化趋势的异同,结果表明：中国不同污染地区云量与云光学厚度呈现不同的分布和变化规律。     

Inventive payoff from R&D in Japanese industry: convergencewith the West

An attempt is made to determine if investment in R&D and the hiring of college-educated employees result in a higher rate of inventions. The relationship between the input of R&D and inventive output is studied in two samples of Japanese factories, 34 in 1982 and 44 in 1970. These results are compared with findings in a parallel American study. The correlations between R&D and inventive output are similar in Japan and America in the 1980s, despite some differences in the management of innovation in the two nations. Moreover, the most Westernized subsample of Japanese firms in the 1970s had correlations between R&D and invention similar to those observed in the American study. Thus, it is concluded that some degree of convergence may be taking place in R&D management strategies in the two nations     

重庆万盛采矿区内主要农作物的光谱测量和分析

矿山开采中产生的固体废弃物和废液会使矿区土壤中富集重金属元素,进而影响矿区内的农作物生长。选择重庆市万盛区矿区作为研究区,采集红薯和南瓜的实测高光谱数据和土壤样本的重金属含量数据。通过对土壤重金属含量和农作物的红边位置偏移进行相关分析,发现不同土壤重金属含量对研究区内主要农作物的影响是不同的。可以看出,在研究区内的两种主要农作物中,红薯对矿区土壤中的重金属Cr、Mn和Cd比较敏感,而南瓜则对以上三种土壤重金属具有一定的吸收和抵抗作用。该结果可以为万盛区矿区内农作物种植的选择提供理论依据。     

无人作战模拟仿真中的VV＆A

根据无人作战模拟研究、开发过程中分队级作战单位建模与仿真环节上所存在的VV&A问题,从军事建模的过程与军事工程技术的角度出发,将一般仿真过程中的VV&A技术与军事作战模拟的特点以及无人作战模拟的特殊性三者有机的结合在一起,深入的探讨了在无人作战模拟仿真过程中VV&A问题的解决办法以及实现过程。通过对无人作战模拟仿真中VV&A的研究与解决,为今后的作战模拟,特别是无人作战模拟中如何解决建模及仿真过程中所存在的类似问题提出了一套系统的、科学的实现办法,具有一定的理论及实践意义。对于我军无人作战研究的深入开展以及跨越式发展具有一定的参考价值。     

东海有机碳存量估算

海洋有机碳存量估算对研究碳循环过程和预估气候变化趋势有重要的作用。海洋有机碳存量可以通过遥感反射率、水体光学特性等参数反演得到。根据东海水域的水体特性,对比了多种有机碳反演算法,并结合东海有机碳垂直分布情况,得到一套完整的东海有机碳存量估算模型。利用2010年MODIS提供的遥感反射率数据和Argo提供的温盐数据,对中国东海区域的有机碳储量分季节进行计算分析。结果表明东海全水柱有机碳储量在1.530×1014 g到2.125×1014 g之间,真光层有机碳储量在4.119×1013 g到7.980×1013 g之间。全水柱有机碳储量整体呈现冬季高、春季低的特点,真光层有机碳储量整体呈现夏季高、冬季低的特点。从2006年至2015年,有机碳存量呈波动上升趋势。对东海有机碳存量进行了较为准确的估算,为今后我国海洋碳储量的评估提供了可供参考的思路。     

基于2007-2013年COSMIC掩星数据的电离层振幅闪烁研究

利用2007-2013年的COSMIC掩星数据，分析了E区与F区电离层闪烁的变化特征.发现用闪烁出现频次、闪烁发生率以及闪烁强度来表征的电离层闪烁出现规律比较相似.E区电离层闪烁在夏季半球的中纬地区最强，其次是春秋季的低纬地区和冬季半球.就经度分布来说，春秋季E区电离层闪烁呈四波结构.对F区电离层闪烁来说:南美-大西洋扇区在12月至点最为显著；非洲和太平洋扇区在6月至点最为显著；大西洋扇区在春秋分季最为显著.极区也出现中等强度的闪烁，尤其在南半球的90°E~180°E扇区较为显著.高纬E区电离层闪烁强度随太阳活动的增强而增强，而低纬和南半球的中纬E区闪烁随太阳活动的增强而减弱.高纬和低纬F区闪烁随太阳活动的增强而增强，而中纬F区电离层闪烁对太阳活动无显著依赖关系.对于赤道区来说，北半球60°W~60°E经度区闪烁强度随太阳活动的变化最为显著，其次是南半球60°E~210°E附近；而对于高纬地区来说，F区闪烁强度随太阳活动的变化最为显著的区域在南半球60°E~210°E附近.     

微视频在高校计算机操作性课程中的应用探究

微视频在学校各类教育中应用越来越普遍.依据微视频的教学特点,针对高校计算机操作性课程中存在的问题,本研究依据ADDIE模型和ARCS动机理论,探索构建微视频在高校计算机操作性课程中的教学应用模型,通过教学案例展示微视频在课堂应用中教与学的过程,利用微视频提高课堂教学质量.     

MPEG-2传输流中的时间信息与音视频同步

文中讨论了MPEG 2传输码流中的时间信息 (传输层中的节目参考时钟 ,PES层中的显示时间标签和节码时间标签 )在音视频同步中的作用。对理想解码器中的音频、视频同步原理作出了分析。指出了实际解码器实现视音频同步的困难之处并提出了解决办法。对实际解码中出现的视音频失同步的情况 ,通过对解码器的控制达到重复帧和丢帧的效果 ,从而重新实现了音、视频的同步。     

Regulatory reform in the broadcasting industries of Brazil and Argentina in the 1990s

Regulatory reform has changed the organization of the broadcasting industry in Brazil and Argentina in the past decade. Although responding to a similar set of pressure, the pace, instruments, and character of reforms have been different in the 2 countries, resulting in media markets of diverse natures. This study argues that these different policy outcomes in the reform of broadcasting regulation in Brazil and Argentina reflect variations in three factors: the nature of the political system, the structure of the existing broadcasting industry, and the ideological legacy in the regulation of communication industries. The case of regulatory reform in the broadcasting industry illustrates different policy patterns in the restructuring of state-industry relations in communications and information technology industries in the 2 neighboring countries.     

A comparison of Japanese and US high-technology transfer practices

Some empirical results and observations are presented which describe the principal ways in which a sample of industrial researchers in Japan and in the US utilize certain technologies resulting from university research. The findings are from a survey conducted in Japan and the US between October 1986 and December 1987. These results indicate that personal communications and technical collaboration are the key factors in the rapid diffusion of research results in both countries, and that in Japan, government agencies and professional societies take a much more active role in organizing and energizing the civilian technology-transfer process than do counterpart organizations in the US     

The antigen of transplantable cells immunologically related to the antigen of the normal human gastric mucosa

A newly detected antigen common for transplantable HeLa-like cell lines and human gastric mucosa has been revealed in all parts of the stomach and in highly differentiated gastric adenocarcinomas in humans. It is localized in the basal area of tall columnar cells in the mucosa and has one immunologically active subunit with molecular weight of 39 kDa. The antigen differs from the other earlier described gastrointestinal antigens in its localization in the organs and cells and in other characteristics.     

Errors due to spatial discretization and numerical precision in thefinite-element method

The effects of the spatial discretization and the numerical precision on a plane wave propagating through a finite-element mesh are investigated in this work. The spatial discretization results in dispersion in the amplitude and the phase of the wave and in a non-uniform rate of convergence within an element. The finite precision in the calculations used in a finite-element code results in degraded accuracy. These errors are investigated as a function of the node density, the order of the elements, and the precision of the calculations used in the finite element code. The errors for first- through eighth-order elements are investigated both analytically and numerically     

狭叶柴胡根发育过程中柴胡皂苷积累的超微细胞化学研究

用醋酸铅溶液对狭叶柴胡（Bupleurum scorzonerifolium Willd.）根内的药用成分柴胡皂苷进行细胞化学定位,在透射电镜下探讨不同发育时期根的结构特征与柴胡皂苷积累的关系。结果表明：狭叶柴胡根的初生结构和次生结构类似一般双子叶植物。在根的初生分生组织中表皮原及皮层原均有皂苷的分布。在根的初生结构中,柴胡皂苷分布于表皮、皮层、中柱鞘、初生韧皮部及原生木质部的薄壁组织细胞内,其中中柱鞘和韧皮部是主要的分布部位。在根的次生结构中,柴胡皂苷主要分布于中柱鞘和次生韧皮部薄壁组织细胞内,在次生木质部及形成层中也有少量分布。高尔基体可能与皂苷的合成有关,且胞间连丝参与皂苷的运输。柴胡皂苷在幼嫩结构中的含量高于次生结构,但其总含量低于次生结构。     

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。     

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.     

Effect of photovoltage on current flow in metal-semiconductor schottky-barrier contacts

It is shown that changes in device characteristics and an increase in the light-to-electrical energy conversion efficiency in metal-semiconductor Schottky barrier contacts are associated with a peripheral electric field built into the contact. For contacts with longer perimeters, variations in device characteristics and the light-to-electrical energy conversion efficiency are significantly larger. Since the photovoltage and peripheral electric fields in the contact region are codirected with the intrinsic electric field of the space-charge region, contact illumination results in a larger increase in the “dead” zone in forward portions of current-voltage characteristics, a larger decrease in the effective Schottky barrier height, and an increase in the field electron emission. An increase in the reverse field emission under photovoltage leads to an increase in the recombination current in the space-charge region, which provides dc photocurrent flow in the circuit.     

Noise in solid-state devices and lasers

A survey is given of the most important noise problems in solid-state devices. Section II discusses shot noise in metal-semiconductor diodes, p-n junctions, and transistors at low injection; noise due to recombination and generation in the junction space-charge region; high-level injection effects; noise in photodiodes, avalanche diodes, and diode particle detectors, and shot noise in the leakage currents in field-effect transistors (FETs). Section III discusses thermal noise and induced gate noise in FETs; generation-recombination noise in FETs and transistors at low temperatures; noise due to recombination centers in the space-charge region(s) of FETs, and noise in space-charge-limited solid-state diodes. Section IV attempts to give a unified account of 1/f noise in solid-state devices in terms of the fluctuating occupancy of traps in the surface oxide; discusses the kinetics of these traps; applies this to flicker noise in junction diodes, transistors, and FETs, and briefly discusses flicker noise in Gunn diodes and burst noise in junction diodes and transistors. Section V discusses shot noise in the light emission of luminescent diodes and lasers, and noise in optical heterodyning. Section VI discusses circuit applications. It deals with the noise figure of negative conductance amplifiers (tunnel diodes and parametric amplifiers), and of FET, transistor, and mixer circuits. In the latter discussion capacitive up-converters, and diode, FET, and transistor mixers are dealt with.     

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。     

欧洲科学商店及其启示

科学商店是荷兰在20世纪70年代创造的,现在已扩展到欧洲许多国家。科学商店不是传统意义上的商店,而是一种科学传播的理念和服务。它运用双向互动的科学传播创新机制,支持科研人员深入社区、拓宽研究范围;为社区居民提供科学和研究服务;为大学学生创造实践和了解社会的机会。参与科学商店研究项目的工作人员、科研人员、市民和其他专业人员都可以从中受益。我国的科普工作可以借鉴欧洲科学商店的运作机制和成功经验,在建立全社会支持科普工作的机制和网络、创新社区科学传播活动和提高公众的科学素质和参与度等方面进行思考和探索。