Diffusion effects and "Ballistic transport"

The effects of both collisional drag and diffusion effects on the operation of GaAs n⁺-n-n⁺structures are determined using a momentum transport equation which includes velocity fluctuation effects. It is shown that diffusion effects are important in practical structures, and that previous interpretations of experimental results which claim to show "ballistic" transport can be seriously in error. The general limitations of single-particle transport models when used to try to understand the results of experiments, such as diode characteristic measurements which yield only ensemble averages, are discussed.     

阴极-敏感膜复合型真空微电子压力传感器研究

该文提出了阴极-敏感薄膜复合结构的新型真空微电子压力传感器,并研制出了阴极-敏感薄膜复合结构,对硅薄膜在外力作用下产生的形变及其应力分布进行了计算机模拟计算,并讨论了薄膜结构参数对其敏感特性的影响。     

"信号与系统"和"数字信号处理"课程改革的思路和实践

为适应信息技术日新月异的变化,培养高质量人才,迫切需要对电子信息类的主干课程-“信号与系统”和“数字信号处理”进行深化改革。第一部分指出传统课程体系和教学内容的不足,论述了构建新课程体系,整合与更新教学内容的基本思路和相应的教学方式方法改革的想法,第二部分从引入新体系教材,更新课堂教学方法,加强实践教学环节等方面介绍了改革实践,实践效果良好,今后还需提高改革实践的深度和广度。     

Surface recombination currents in "Type-II" NpN InP-GaAsSb-InP self-aligned DHBTs

Surface recombination effects are studied in non-passivated non-self-aligned and self-aligned NpN InP-GaAsSb-InP double heterostructure bipolar transistors (DHBTs) down to submicrometer emitter dimensions, and over current densities ranging from 10 A/cm/sup 2/ to 100 kA/cm/sup 2/. The present study is motivated by the drive to scale InP DHBTs for higher speeds and integration densities. Self-aligned InP-GaAsSb-InP DHBTs are characterized by weak emitter size effects (ESEs), and periphery recombination currents are found to be very nearly identical to published results for InP-GaInAs SHBTs despite the major differences in emitter junction band alignments ("type-II" versus "type-I") and injection mechanisms (thermal versus hot electron injection). The correspondence of measured periphery currents in both systems indicates that ESEs are dominated by a mechanism common to InP-GaAsSb and InP-GaInAs devices: this requirement is fulfilled by the direct electron injection from the InP emitter mesa sidewalls onto the extrinsic base surface. Consideration of band alignments and surface depletion effects at the extrinsic base surface is used to explain the commonality of emitter size effects in InP-GaAsSb and InP-GaInAs devices.     

自动控制理论课程建设与改革的探索

自动控制理论课程不仅是控制类专业而且是电子信息类专业的重要专业基础课.文章介绍了自动控制理论课程建设与改革的实践和体会,总结了教学、教改工作所取得的成果,提出了一些具体做法和措施,着重对课程教学内容、教学体系的整合和优化以及实验内容、实验教学方法与实验组织方式进行了讨论,旨在突出教学重点,增强学生的动手能力,进而提高教学质量.实践证明,效果良好.并对该课程的进一步改革提出了一些设想.     

"三开放"实践教学模式与创新能力的培养

分析了当前高校实践教学中存在的一些问题,介绍了“三开放”实践教学模式及在电子技术教学过程中对学生创新能力培养所做的一些尝试,并对进一步提高实践教学中学生的科学素质提出了设想。     

浅谈"集成电路版图CAD"课程建设

"集成电路版图CAD"课程是集成电路设计与微电子专业的一门重要的专业课。本文介绍了"集成电路版图CAD"课程建设和改革的实践和体会,提出了一些具体的想法和思路,着重对课程教学内容、教学体系的整合和优化、实验教学内容和教学方法进行了讨论,"一条主线、两个流程"贯穿实验教学,增强学生的工程实践技能,进而提高教学质量。     

《电力电子技术》多媒体课件的设计与应用

根据“电力电子技术”课程波形图多、开关器件换流过程及电磁概念抽象的特点,利用多媒体信息具有图文并茂及动域效果的优点,采用Authorware和Flash作为软件开发平台,进行了多媒体课件的设计制作。经过教学实践应用,获得了较好的教学效果。本文结合“电力电子技术”多媒体课件的部分示例,主要介绍了课件的设计思想及应用中注意的问题。     

A "Mix of Attributes" Approach to the Study of Media Effects and New Communication Technologies

The purpose of this article is to discuss the media effects approach broadly, to point out limitations the traditional approach imposes on the field, and to discuss a "mix of attributes" approach with a focus on the study of "new" technologies for the dissemination of news. It is argued that the mix of attributes approach would better serve to advance both theory and empirical research, not only in the area of new media technologies, but also for more traditional media effects research.     

MPEG-4的视频"档次"及其"等级"技术

首先阐述了ＭＰＥＧ－４版本１的“档次”和“等级”概念,然后详细叙述了各种视频对象类型和工具、各种视频的“档次”定义以及每个“档次”上的“等级”划分技术,最后简要介绍了ＭＰＥＧ－４版本１可能的应用领域。     

信息时代下加强对"一岗双责"履行情况的指导、检查和考核

该文诠释了领导干部和业务部门履行党风廉政建设"一岗双责"概念,提出了推进"一岗双责"所要达到的工作目标,阐述了建立和应用双向融入的"一岗双责"工作机制和主要做法,取得的工作成效和体会.     

Modeling the "Early effect" in bipolar transistors using an empirical but effective parameter

Previous attempts at modeling the "Early effect" in transistors were not valid over wide ranges of operating conditions. A model parameter is defined here which accounts for the desired effects and has the important attributes of being independent of current, temperature, or other parameters for a given device type. The expressions proposed recently by Logan and by Lindholm and Hamilton for including the Early effect in transistor current gain are shown to be equivalent for all temperatures and currents. A new method is proposed for measuring the empirical parameter VN.     

半导体激光阵列“Smile”效应下快轴准直镜的装调

针对3种典型"Smile"形态的半导体激光阵列(LDA)如何装调快轴准直镜的问题,开展"Smile"条件下快轴准直实验定量研究。利用光纤近场扫描法和最小二乘法获得LDA的"Smile"值,采用Zemax非序列模式,模拟"Smile"下LDA的快轴准直。结果表明,LDA的"Smile"大小及形态分布影响准直镜装调位置,透镜光轴需要与LDA匹配,否则会造成光束质量的劣化。这为实际掌握LDA的快轴准直安装提供一种思路,为进一步集成高功率高光束质量的大功率半导体激光器提供了理论和实验基础。     

半导体激光阵列“Smile”效应下快轴准直镜的装调

针对3种典型“Smile”形态的半导体激光阵列(LDA)如何装调快轴准直镜的问题, 开展“Smile”条件下快轴准直实验定量研究。利用光纤近场扫描法和最小二乘法获得LDA的“Smile”值, 采用Zemax非序列模式, 模拟“Smile”下LDA的快轴准直。结果表明, LDA的“Smile”大小及形态分布影响准直镜装调位置, 透镜光轴需要与LDA匹配, 否则会造成光束质量的劣化。这为实际掌握LDA的快轴准直安装提供一种思路, 为进一步集成高功率高光束质量的大功率半导体激光器提供了理论和实验基础。     

"互联星空"与"天天在线"的商务模式比较分析

通过对比分析 "互联星空"和"天天在线"的商务模式,提出令人深思的问题:中国电信和中国网通为了避免价格竞争,分别采取实现服务差异化的新商务模式,然而最终由于"互联星空"和"天天在线,,是中国电信和中国网通在相同的细分市场中利用基本相同的商务模式在竞争,他们最后将不得不共同面对再次陷入原始的价格竞争的危险.     

From "macro" to "micro" manipulation: models and experiments

This paper addresses various problems related to manipulation in the micro domain, a field which is increasingly important for research and application. Grasping and manipulating parts with size ranging between a few micrometers and about 1 millimeter (defined in this paper as "micro parts") are required for an increasing number of applications: the assembly of micro systems and micro machines; and the operation in tiny and unpredictable environments, such as for inspection and interventions in pipes and for micro surgery. The aim of this work is to find out similarities and differences between traditional manipulation and micro manipulation, by investigating which requirements are still valid and which must be redefined when the object size scales down. The similarities between the two application domains "macro" and "micro" are pointed out along with the differences, and both are taken into account for the evaluation of different grasping typologies. Dedicated models for the adhesion forces arising at the micro level are presented, preliminarily tested, and discussed.     

基于what和where信息的目标检测方法

根据视觉系统两条通路理论,提出了一种基于what和where信息的目标检测方法.采用以环境为中心的where信息进行自顶向下的注意控制,指导what信息驱动的自底向上的注意.自顶向下的注意包括预注意和集中注意两个阶段,预注意依据where信息为特定目标出现与否提供先验,做出是否继续搜索的判定.集中注意的结果与what信息相结合,将注意指向目标最有可能出现的图像区域,并得到一系列样本显著区域.应用于多幅自然图像的实验结果证明了算法的有效性.     

Deterministic signals and interference in FM reception: The "Instantaneous" approach, with undistorted inputs

The purposes of this study are several: 1) to extend earlier models of the FM reception process, to include as much "realism"-i.e., nonideality of both the linear and nonlinear elements of the typical FM receiver-as possible, and still retain analytical and computational feasibility; 2) to examine explicit cases of interference produced by one or more deterministic signals; and 3) with such specific examples, both to provide insights into the distortion effects generated by the nonlinar interactions of the various (desired and undesired) signals in the receiver and to present the analytical framework of the instantaneous outputs required in any (subsequent) fully statistical treatment, where now the interference (e.g., "noise") is noticeably non-Gaussian. In addition, these deterministic models may also provide useful structures for simulation studies. The instantaneous receiver outputs are obtained for the following receiver models (A) and interference "scenarios" (B). For (A), (I) "superclipping" and an ideal discriminator; (II) no limiting and ideal discriminator; (III) "superclipping" and a nonideal discriminator; (IV) no limiting and a nonideal discriminator. For (B), with each (A), we consider explicitly the cases of: (i)one cochannel interfering signal; (ii) one adjacent channel interferer, and (iii) M symmetrical interferers (M = 1, 5). All the above are obtained here for idealized (i.e., sufficiently wide-band) RF-IF receiver stages, which are essentially linear under this condition. The results are illustrated with cases for selected, typical parameters of the combination of the interference-receiver structure.     

Staying Protected from "Social Engineering"

"Your Internet Connection" we provided wealth of information on different protection tools. Although these tools are indeed necessary for anyone brave enough to surf the Internet today, there is no substitute for sound judgement. "Your Internet Connection" describing Internet security resources, the Anti-Phishing Working Group's (APWG) and the Phishing Incident Reporting and Termination squad (http://wiki.castlecops.com/PIRT) were listed among other important security resources.Many criminals generating their garbage from the "sewers of the Internet" employ so called "social engineering" techniques. Just to make sure we are on the same page, here is the definition for the term "social engineering" from SearchSecurity.com: "In computer security, social engineering is a term that describes a non-technical kind of intrusion that relies heavily on human interaction and often involves tricking other people to break normal security procedures.     

Decay Dynamics of Excited Nd $^{+3}$ Ions in Nd:YVO $_{4}$ Following Weak Excitation

Decay dynamics of the upper-laser energy level of $hbox{Nd:YVO}_{4}$ are re-evaluated. In order to reduce the effects of re-absorption, comparative measurements among crushed samples with different doping concentrations were conducted. The magnitude of re-absorption was estimated experimentally by comparing the relative intensity of the emitted fluorescence spectra at different wavelengths, and estimated theoretically by employing a simplified model. The temporal decay dynamics are found to be non-exponential and the associated rate parameters are presented. The room temperature intrinsic life time value of the $^{4}hbox{F}_{3/2}$ energy level is found to be significantly shorter than the value accepted today.