光学期刊联合编辑部成功参展中国国际光电周

第十一届ILOPE展会于2006年12月5-7日在北京召开,此次展会包含了一个光电展览,四个技术/产业论坛和一个中外贸易交流会.吸引了来自14个国家近400家参展商,展出面积达1万多平米.国内主流的激光、光学和红外厂商悉数到场,同时国外FLIR、光谱物理、相干、镭宝、贰陆、HGH、Senko、美国Photonics、尼康等国际知名企业也携新产品、新技术参与.     

Graph Laplacian Matrix Learning from Smooth Time-Vertex Signal

In this paper,we focus on inferring graph Laplacian matrix from the spatiotemporal signal which is defined as“time-vertex signal”.To realize this,we first represent the signals on a joint graph which is the Cartesian product graph of the time-and vertex-graphs.By assuming the signals follow a Gaussian prior distribution on the joint graph,a meaningful representation that promotes the smoothness property of the joint graph signal is derived.Furthermore,by decoupling the joint graph,the graph learning framework is formulated as a joint optimization problem which includes signal denoising,timeand vertex-graphs learning together.Specifically,two algorithms are proposed to solve the optimization problem,where the discrete second-order difference operator with reversed sign(DSODO)in the time domain is used as the time-graph Laplacian operator to recover the signal and infer a vertex-graph in the first algorithm,and the time-graph,as well as the vertex-graph,is estimated by the other algorithm.Experiments on both synthetic and real-world datasets demonstrate that the proposed algorithms can effectively infer meaningful time-and vertex-graphs from noisy and incomplete data.     

8848从顶峰走向衰微的历史见证

人不可能两次迈进同一条河流，而8848却似乎可以。近段时间，因为速达的“收购传闻”，8848再一次成为业界关注的焦点。因为如今的8848内部风雨飘摇，外部官司缠身，它有何被收购的价值?公司总裁吕春维为何早早投怀送抱、急于为收购造势?谁是这一出“收购闹剧”的幕后主使?在诸多疑问背后，很少有人能看清事情本质。老8848的创始人王峻涛知道，但他不说，因为此8848已非当年之彼8848。几年前，盛极一时的老8848就是这样被幕后资本强行拉入分拆和兼并的资本游戏，被胜利冲昏头脑的大股东妄图运用资本力量主导企业发展，对他们来说，更重要的是上市圈钱。但因为牵扯的利益太多，诱惑太多，8848的发展最终陷入极度迷茫中，在资本疯狂追逐最大利益的时候，企业却错过了发展的最佳时机，并从此一步步走向衰微。6年来，8848经历了最辉煌的巅峰时期，同样也经历了无数是是非非。即使当时剩下的钱仍可使8848运营数十年，但是，商人们已经对8848的未来失去了耐心与信心，老8848最终难逃遭清算厄运。后来，所谓“王者归来”的新8848更是虚有其表，连核心业务也惹上纠纷，最后股东终于按捺不住……现在经常有人问王峻涛，如果当时不要上市，如果当时不分拆，如果……但王说：假设没有意义，我懂得了一点：创业者要坚持、坚持、再坚持。张朝阳也说：做自己的，不要听华尔街的。或许这就是本文要寻找的答案。     

中国这样进行专利谈判肯定不行——美国移通半径公司亚太区总裁雷鸣硅谷对话《IT时代周刊》

3G谈判受阻的主要原因是在谈判中，电信研究院作为一家研究机构实力太弱，如果能聘请外国在专利谈判上有丰富经验的律师或律师行主谈，加上中国政府的免费授权政策和运营商有关采购3G设备政策的出台，专利谈判可能是另外一个结果。     

Intelligent Passive Detection of Aerial Target in Space-Air-Ground Integrated Networks

Passive detection of moving target is an important part of intelligent surveillance. Satellite has the potential to play a key role in many applications of space-air-ground integrated networks(SAGIN). In this paper, we propose a novel intelligent passive detection method for aerial target based on reservoir computing networks. Specifically, delayed feedback networks are utilized to refine the direct signals from the satellite in the reference channels. In addition, the satellite direct wave interference in the monitoring channels adopts adaptive interference suppression using the minimum mean square error filter. Furthermore, we employ decoupling echo state networks to predict the clutter interference in the monitoring channels and construct the detection statistics accordingly. Finally, a multilayer perceptron is adopted to detect the echo signal after interference suppression. Extensive simulations is conducted to evaluate the performance of our proposed method. Results show that the detection probability is almost 100% when the signal-to-interference ratio of echo signal is-36 dB, which demonstrates that our proposed method achieves efficient passive detection for aerial targets in typical SAGIN scenarios.     

CDMA直放站干扰案例分析

2007年11月17日22点35分.我站值班人员接到中国联通梅州分公司的电话投诉.称其在梅州城区的多个CDMA基站收到不明信号的干扰.严重影响CDMA用户的正常使用。接到投诉后.我站迅速组织技术力量查找干扰     

Boston-Power集资发展新一代锂离子电池技术

Boston-Power公司(Boston-Power,Inc.)是创新便携式电源解决方案的供应商,其解决方案可满足当今市场对更安全、更持久锂离子电池的需求.日前,该公司宣布募集了4500万美元的新资金.C系列融资是由Oak Investment Partners主导,并包括现有的蓝筹投资者Venrock Associates、Granite Global Ventures及Gabriel Venture Partners.     

新起点 新机遇——BIRTV2008吹响广播影视新技术的集结号

2008年7月11日.BIRTV2008筹备工作通报会在北京梅地亚中心召开,广电总局科技司王效杰司长、中央电视台何宗就副台长、中央人民广播电台钱岳林总工、广电总局广播科学研究院马炬院长、广播电视规划院姜文波院长、中央电视台技管办黄平刚主任以及中广国际总公司李金荣总经理等领导出席会议,与120多位参展厂家的代表和媒体界的朋友们在会上进行了座谈.     

信息产业部苟仲文副部长亲临一线指导江西抗寒救灾

2月4日,信息产业部苟仲文副部长深入省内通信运营企业现场查看了机房、通信基站和野外倒塌的电线杆,并召开座谈会,详细了解全省通信行业的受灾情况,指导江西通信业抗灾保通信畅通工作。苟仲文高度评价了江西省通信行业抗灾保通信畅通工作,对全省通信行业广大干部员工在抗雪灾行动中的无私奉献表示感谢,并勉励全省通信行业要继续战斗,做好后期的抗灾工作。     

农村电子商务的5个问题和建议

目前我国农业管理部门已经重视到电子商务对农村经济发展的重要性,农村信息化建设步伐加快,进一步促进农村电子商务发展.从对中国互联网认识和使用的群体来看,绝大部分都集中于受过高等教育的人口,虽然会有分布于农业行业的部分,但总体所占比率很低.全国各种涉农网站为实现农业增效和农民增收,每天都发布农产品供求信息.无论从交易规模、数量、还是经济效益来看,中国农村电子商务都滞后于其他领域电子商务的发展.……     

The effect of cathode materials on reactive ion etching of silicon and silicon dioxide in a CF4 plasma

Silicon and silicon dioxide have been Reactive Ion Etched in a CF₄ plasma using a diode sputtering configuration to achieve etching. Pressures ranged from 20 to 100 millitorr and power densities to the RF cathode were between 0.1 and 1.0 W/cm². The effect of cathode material on the quality of etched surfaces and on etch rates has been investigated. It has been observed that the etch rate of silicon decreases as the area of silicon exposed to the plasma is increased and that this silicon loading effect is strongly influenced by the material covering the balance of the cathode. For instance, the silicon loading effect is much more pronounced when silicon dioxide rather than aluminum is used to cover the balance of the cathode. This silicon loading effect was investigated further by varying RF power. It was found that loading a silicon dioxide covered cathode with silicon wafers decreases the dependence of silicon etch rate on power. The silicon dioxide etch rate and its dependence on RF power are the same whether silicon, silicon dioxide or aluminum is used to cover the balance of the cathode. Possible explanations for these experimental results will be discussed.     

高压高功率VHF-PECVD的微晶硅薄膜高速沉积

采用高压高功率(hphP)甚高频等离子体强强化学气相沉积(VHF-PECVD)法对微晶硅(μc-Si:H)进行高速沉积,在最优沉积条件参数下对hphP和低压低功率(lplP)两组样品沉积速率、光电导、暗电导及光敏性等性能参数进行测试,得到了1.58 nm/s的较高沉积速率、光电性能优秀和更适合薄膜太阳能电池的μc-Si...     

Uniformity of silicon microcrystallinity in large area RF capacitive reactors

In this work, a controlled, nonuniform RF power distribution is produced across a large area PECVD reactor. The effect of the RF power distribution on the crystallinity of silicon thin films deposited from silane‐hydrogen discharges is studied. Results show that, even with a strongly nonuniform RF distribution (70%), uniform crystallinity can still be achieved for films deposited at the limit between amorphous and microcrystalline silicon provided that the input silane concentration is sufficiently low (nominal concentration lower than ≈︂1˙2%). This work shows that to deposit silicon with a uniform microcrystallinity over large area using high silane concentration, the reactor design must guarantee a highly uniform power distribution. Copyright © 2008 John Wiley & Sons, Ltd.     

碳化硅电力电子器件在电力系统的应用展望

就目前来看,我国的科学技术得到快速发展。在这一背景下,半导体的器件在制作以及生产的工艺上都得到一定的发展。而碳化硅属于宽带材料的一种,其主要的特点是高热导率、高饱和电子漂移速率以及高击穿场强等。通过这种新型的半导体,可以实现大功率、高压以及高温应用。另外,由于碳化硅成本的大幅度降低,且其性能得到提升,使得碳化硅在电力系统中得到普遍使用。本文将对电子系统中碳化硅电力电子器件的应用进行了深入的分析以及探讨。     

高功率CO2激光作用下硅镜热畸变的动态过程研究

以光学干涉方法,实验研究了在CO2激光束入射在硅镜上,硅镜热畸变的动态过程。在变形之初,硅镜镜面的位移量变化迅速。对于一面70mm,厚8mm的硅镜,吸收激光功率140W,作用时间4s时最大挠变形0.76μm.这对于高功率短波长激光器而言是不可忽略的。     

Czochralski-grown nitrogen-doped silicon: Electrical properties of MOS structures; A positron annihilation study

Czochralski-grown nitrogen-doped (NCZ) silicon was studied using different methods. Measurements of interface traps density, effective generation lifetime and effective surface generation velocity were performed on selected Metal-Oxide-Semiconductor (MOS) structures. Application of the positron annihilation technique (PAS)—pulsed low energy positron system (PLEPS)—was focused on the detection of nitrogen-related defects in NCZ silicon in the near surface region. PAS—PLEPS technique gave relevant results on p-type NCZ silicon. Low sensitivity in the application to n-type NCZ silicon discriminates the PAS—PLEPS technique and should be alternated by other experimental technique. On the other hand, more pertinent measurement of generation lifetime was performed on MOS structures with n-type Si. Although the generation lifetime decreases in NCZ silicon, considerable lateral homogenization of the relaxation time was observed on the wafer.     

Crystalline silicon solar module technology: Towards the 1 € per watt‐peak goal

Crystalline silicon solar module manufacturing cost is analysed, from feedstock to final product, regarding the equipment, labour, materials, yield losses and fixed cost contributions. Data provided by European industrial partners are used to describe a reference technology and to obtain its cost breakdown. The analysis of the main cost drivers allows to define new generation technologies suitable to reduce module cost towards the short‐term goal of 1 € per watt‐peak. This goal roughly corresponds with the cost level needed to enable ‘grid parity’: the situation solar electricity becomes competitive with retail electricity. The new technologies are described and their costs are analysed. Cost reductions due to scale effects in production are also assessed for next generation manufacturing plants with capacities in the range of several hundreds of megawatts to one gigawatt of module power per year, which are to come in the near future. The combined effects of technology development and economies of scale bring the direct manufacturing costs of wafer‐based crystalline silicon solar modules down into the range of 0·9–1·3 € per watt‐peak, according to current insights and information (the range results from differences between technologies as well as from uncertainties per technology). Copyright © 2008 John Wiley & Sons, Ltd.     

强激光系统中硅镜变形数值分析

本文运用数值传热学中全隐差分格式交替方向块迭代法,对周边绝热强激光照射非稳态条件下硅镜的温度及挠变形进行了数值模拟,给出了形变随激光功率、光斑直径、镜片直径、镜片厚度以及照射时间等参数的变化规律,并对镜片局部最高温度的变化作了探讨和分析.     

a-Si/μc-Si叠层电池中间层材料SiO_x:H制备研究

为提高a-Si/μc-Si叠层太阳电池的效率,采用射频等离子体增强化学气相沉积(RF-PECVD)技术,制备了系列n型掺磷硅氧(SiOx:H)薄膜作为中间层,研究了CO2/Si H4气体流量比、沉积功率和PH3掺杂浓度等工艺参数对材料光电特性的影响,获得了折射率、电导率和禁带宽度能够在较大范围内调控的SiOx:H薄膜。     

Experimental characterization of electron-hole generation in silicon carbide

Thermal generation in wide bandgap semiconductors can be observed by monitoring the capacitance recovery transients of npn (or pnp) storage capacitors in which the middle layer is floating. In this article, we report a study of thermal generation in 4H and 6H silicon carbide (SiC). Three generation mechanisms are identified: bulk generation in the depletion regions of the pn junctions, surface generation at the periphery of the capacitors, and defect generation associated with imperfections in the material. All three generation mechanisms are thermally activated. Bulk generation and surface generation have activation energies of approximately half bandgap, while defect generation exhibits field-induced barrier lowering resulting in an apparent activation energy less than half bandgap. Because the generation rate is extremely low, most measurements are conducted at elevated temperatures (250-350°C). However, we also describe a long-term measurement at room temperature in which the 1/e recovery time appears to be in excess of 100 years.