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.     

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。     

Fourth quarter 2009 IEEE communications surveys and tutorials

Welcome to the fourth issue of 2009 of the IEEE Communications Surveys and Tutorials. Paper in this issue survey the research effort in several areas such mobility in Wimax, mobility models in VANET, handoff in cellular networks, admission control in MANETS, physical impairments in optical networks, physical layer issues in the 802.11n standard as well as jamming in wireless sensor networks     

South Pole温度风速廓线的统计分析

利用2008年South Pole的探空资料,通过大气温度和风速廓线,确定了South Pole地区冬季（6,7,8月）和夏季（12,1,2月）的大气边界层结构,边界层和对流层顶的高度。对近地面的温度、水汽压、风速和风向进行了统计分析。结果表明,South Pole大气边界层大多时候为稳定型,但在夏季也存在不稳定的情况,尤其在1月份较多;夏季夜晚的边界层平均高度为389米,比白天的304米大,冬季夜晚的边界层平均高度为591米,大于夏季夜晚;夏季白天对流层顶平均高度比夜晚略大,分别为6172米和5770米。South Pole高层大气理查森数的倒数基本都小于4,发生湍流的可能性很小。     

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.     

LIBS水下原位探测技术研究进展

作为一种分析技术,激光诱导击穿光谱(Laser induced breakdown spectroscopy, LIBS)近年来在各个领域有着快速的发展, 在水下的应用也逐渐受到关注。对LIBS水下研究从实验室模拟到现场试验、从机理研究到技术发展都进行了回顾,并以 中国海洋大学研制的深海LIBS原位探测系统LIBSea为例,给出了LIBS系统在海洋探测中获得的典型结果,最后对未 来5~10年LIBS水下研究方向进行了展望。     

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。     

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.     

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.     

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.     

低云中短波红外表观辐射模型研究

在对空红外系统的多光谱探测和红外仿真中，云的干扰不可忽略，所以，对云的辐射特性的研究至关重要。在不同的波段，云的辐射特性会有很大的差异，为了研究各个不同波段云的表现辐射特性．需要计算云的光谱辐射量。在典型观测模式下建立了低云的表观光谱辐射模型，研究了对云背景辐射有贡献的各个辐射分量的计算方法。基于传统的二流近似模型获取各个参数，引入云的光谱光学厚度的经验公式。进而获得了低云在中短波段的光谱辐射特性，有效地计算出了云背景在1-5μm的中短波段内的表现光谱辐亮度数据，并且节省了计算时间。经过比较发现，该模型的计算结果与实测结果有较好的一致性。可以为云背景多光谱分析、探测及仿真提供背景数据。     

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.     

A simple method to improve the transients in adaptive systems

A method, based on classical optimization techniques, is proposed to improve the adaptation transients in adaptive systems. Its philosophy consists basically in using a modified adaptation mechanism which alternately works in a priori mode, in which the optimization-correction horizon is slid forward in time, and in a posteriori mode, in which, by using an equivalent system, the parameters (and the adaptation gain matrix, if time varying) are recomputed over this horizon to generate the adaptive plant input.     

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。     

Relaxation l.s.a. mode in InP

What are believed to be the first convincing observations of relaxation l.s.a.-mode operation in InP are reported. Devices fabricated from vapour-phase epitaxial material have shown the characteristic `signatures? of the mode in oscillators operated in S- and X-bands. So far, conversion efficiencies have not exceeded those for comparable samples in GaAs, almost certainly owing to remaining material limitations in the relatively thick active layers. The significance of the results lies, in practical terms, in the promise of high-peak-power sources with acceptable efficiencies, and, in diagnostic terms, in the derived information on the magnitude of the fundamental transferred-electron characteristic peak/valley ratio in InP and in achievable material quality factors for thick epitaxial layers.     

Surgical applications of lasers

Because of an ability to coagulate, ablate, or vaporize tissue, argon, CO2, and Nd:YAG lasers have been employed extensively in surgery. The capability of transmitting argon and neodymium YAG energy through a flexible fiber which may be inserted in a fiberoptic instrument allows the application of the laser in a number of anatomic areas without the need for an incision. Extensive application has been made in utilizing laser techniques in treating lesions of the gastrointestinal tract, skin, central nervous system, bladder and urethra, spine, joints, ear, nose and throat, and in general surgery to provide control of bleeding. Surgical advances in the application of lasers would be assisted by engineering developments such as a tuneable laser, a flexible carbon dioxide transmission fiber, miniaturization, reduction in cost, improvement in cooling systems, and portability of the laser surgical instrument.     

Distribution estimation consistent in total variation and in twotypes of information divergence

The problem of the nonparametric estimation of a probability distribution is considered from three viewpoints: the consistency in total variation, the consistency in information divergence, and consistency in reversed-order information divergence. These types of consistencies are relatively strong criteria of convergence, and a probability distribution cannot be consistently estimated in either type of convergence without any restrictions on the class of probability distributions allowed. Histogram-based estimators of distribution are presented which, under certain conditions, converge in total variation, in information divergence, and in reversed-order information divergence to the unknown probability distribution. Some a priori information about the true probability distribution is assumed in each case. As the concept of consistency in information divergence is stronger than that of convergence in total variation, additional assumptions are imposed in the cases of informational divergences     

真空光镊系统及其在精密测量中的研究进展

光镊具有非接触、低损伤和适用范围广等特性,被广泛应用于生命科学、纳米科技等领域。光镊系统通过调制束缚光场操控机械振子的运动,借助光动量和角动量的检测获取振子的运动状态,以实现对振子物理参量的精密测量。与传统液体光镊系统不同,真空光镊系统中的机械振子可获得与外界环境近乎完全隔离的状态,具有超高灵敏度的探测能力,是精密测量和基础物理研究的理想平台。首先介绍了真空光镊系统相关的基础理论,然后介绍了真空光镊系统的实验配置方案及其在精密测量中的典型应用,最后总结了真空光镊系统的发展现状,并给出了未来的发展建议。     

Simulation of lung function evolution after heart-lung transplantation using a numerical model

A morphometry-based computational model for expiratory flow in humans was used to study the unusual configuration of the maximum expiratory flow-volume (MEFV) curve associated with alterations in lung function after heart-lung transplantation (HLT). The postoperative MEFV curve showed a peak, followed by a gently sloping plateau over the midvolume range, ending in a knee where the flow suddenly fell, instead of the usual observed uniform decrease in expiratory flow. We have tested several hypotheses about the relationship between the pattern of changes in the configuration of the MEFV curve and pathological changes in the airway mechanics through computer simulations. Principally, effects of lung denervation and airway obstruction, associated with the development of bronchiolitis obliterans in the lung periphery, have been investigated. The calculated curves are similar in appearance to the measured postoperative flow-volume curves and confirm reliability of the earlier hypotheses. We conclude that the plateau-knee configuration of the MEFV curve can result from flow limitation in one of the first airway generations, that this flow limitation coupled with an increase in peripheral airway resistance results in plateau shortening, and that flows exceeding predicted values during the second part of expiration may be produced by lung denervation. Additionally our results demonstrate that airways larger than the transitional and respiratory bronchioles can be involved in pulmonary function deterioration observed in patients affected with obliterative bronchiolitis. Our findings indicate that the computational model, based on a symmetrical dichotomous branching structure of the bronchial tree, along with pathological data, can be employed to evaluate the effects of heterogeneous changes in the lung periphery. Index Terms-Airway mechanics, forced expiration, lung transplantation, mathematical modeling, maximal expiratory flow-volume curve.     

扬声器单元TS参数偏差对系统频率响应曲线的影响

在闭箱、开口箱、被动辐射体箱和带通箱系统的设计中,人们已认识到单元的TS参数和箱体的声学参数有紧密的配合关系。一旦箱体的结构设计有所确定,安装在箱体上的扬声器单元的TS参数也必须确定,这样,系统的低音频特性就因此而定。但是在批量投产时,TS参数的偏差将对系统的低音频特性产生变化。以开口箱的系统频率响应曲线为分析目标,要观察TS参数的偏差所产生的变化。为此,采用LEAP5扬声器设计软件作相应的模拟,证明只要TS参数的偏差在一定的范围内,频率响应曲线的变化也可以维持在一个偏差带内。这样,可根据系统的技术指标来确定TS参数的偏差。