Quantum functional devices: resonant-tunneling transistors,circuits with reduced complexity, and multiple valued logic

Recent advances in the area of quantum functional devices are discussed. After a discussion of the functional device concept, resonant-tunneling bipolar transistors (RTBTs) with a double barrier in the base region are described. Design considerations for RTBTs with ballistic injection and the first observation of minority-electron ballistic RT are presented. RTBTs using thermionic injection and exhibiting a high peak-to-valley ratio at room temperature in the transfer characteristics are also described. Multiple-state RTBTs and their DC and microwave performance are then discussed. Circuit applications of RTBTs also are discussed. It is shown that RTBTs allow the implementation of many analog and digital circuit functions with a greatly reduced number of transistors and show considerable promise for multiple-valued logic. Experimental results on frequency multipliers and parity bit generators are presented. Analog-to-digital converters are memory circuits are also discussed. Two novel superlattice-base transistors are reported. Negative transconductance is achieved by suppression of injection into minibands. Gated quantum-well RT transistors are also discussed     

Globalizing IN for the new age

The future directions of intelligent network (IN) enhancements are discussed. The reasons why globalization of service provisions based on IN technology will be indispensable are also discussed. The functions required for global INs are analyzed. Possible schemes for IN function distributions are identified. The functions that should be centralized and distributed are clarified. Global IN architecture models are proposed. The areas which need extensive study for global INs are reviewed     

紫外防护品的防紫外光谱特性检测

讨论了紫外防护品(眼镜、防晒护肤品、织物)的防紫外检测原理,建立了实用的检测装置,对样品旋转不同的角度进行测试,测试结果与日本岛津UV-3150紫外分光光度计的测量结果比较,具有良好的一致性.检测11种不同类型的镜片,结果表明大多数镜片均能限制UVB(280～320 nm)的透过,但UVA(320～400nm)的透过率较高,镜片的防紫外线能力不理想.采用紫外吸光度法检测6种防晒护肤品,根据吸光度A值的大小,评价产品的性能,3种化妆品实测防紫外效果与产品标定的SPF值不相吻合,并且UVA的透过率较高.检测14种织物,计算得到织物防紫外指数UPF值,发现染色深及较厚的织物防紫外效果较好,纯棉及亚麻防紫外线效果较差.三种紫外防护品对UVB的防护效果都优于对UVA的防护,但UVA对人体同样造成伤害,应引起人们的重视.     

光电编码器检测装置研究现状与展望

随着科学技术的发展,各个研究单位对编码器的精度要求越来越高,因此,在编码器研制生产过程中,需要对其误差进行检测,虽然现有检测装置能够完成编码器的误差检测,但都存在着不足之处.文章在参考大量文献的基础上,首先介绍了光电编码器的原理,其次介绍了国内外编码器检测装置的结构及原理,并分析其优缺点,最后对其发展方向进行了展望.     

三维集成微波组件技术:进展与展望

介绍了三维集成微波组件的典型集成架构及其特点,综述了三维集成微波组件基板技术、垂直互连及热设计等关键技术研究现状,对主要技术性能进行了对比分析。介绍了三维集成微波组件可靠性理论与技术研究进展及后续研究方向。分析了三维集成微波组件技术发展趋势,提出了重点技术攻关方向建议,并对三维集成微波组件技术发展和应用前景进行了预测。     

脊波变换的研究现状与应用前景

简述了脊波变换的产生和发展，着重介绍了脊波变换理论及其在图像信号的奇异性分析中的应用，分析了现代信号处理中几种变换的优缺点及各自适用的范围，总结了脊波变换目前研究的主要问题，给出了这一领域研究发展的方向。     

效率、功率因数及其关系的讨论

效率和功率因数是电气与电子工程中的两个重要参数.它们既是两个不同的概念,又有密切的联系.但在目前的电路分析及模拟电子技术的部分教材中,关于效率、功率因数及其关系问题仍然存在一些错误概念,或者对这些重要的问题言之甚少.本文针对上述问题作了详细地讨论.并通过一个例子分析了效率及功率因数之间的关系,纠正了对这些问题的模糊认识,使这些概念更加明确.笔者认为文中的分析和讨论对电类各专业的学生掌握这些基本问题是有益的.     

RF MEMS电感的研究与进展

无线通信的迅速发展,对高性能电感有迫切的需要。本文介绍了目前电感的发展状况,包括表面螺旋电感、垂直平面螺旋电感、悬浮螺旋电感和螺线管电感。对各种电感的性能进行了比较,讨论了电感设计所需考虑的问题及相关因素,对各种电感的加工工艺作了介绍。总结了各种电感的品种因数。     

Historical review of OCR research and development

Research and development of OCR systems are considered from a historical point of view. The historical development of commercial systems is included. Both template matching and structure analysis approaches to R&D are considered. It is noted that the two approaches are coming closer and tending to merge. Commercial products are divided into three generations, for each of which some representative OCR systems are chosen and described in some detail. Some comments are made on recent techniques applied to OCR, such as expert systems and neural networks, and some open problems are indicated. The authors' views and hopes regarding future trends are presented     

Monte Carlo simulation for the prediction of the emission levelfrom multiple sources inside shielded enclosures

The emission level from multiple sources inside shielded enclosures is presented. Fields are expressed through the dyadic Green's function. Integrated circuits are modeled as electric and magnetic dipoles. Induced electric current magnitudes on the walls of the enclosures are analytically calculated. Probabilistic models based on measurement data for various source configurations are derived and Monte Carlo simulations are produced. The results are used for the prediction of possible emission margins. Applications in PCB design are discussed and suggestions are made     

红外光源在有害气体检测中的应用研究

研究了红外光源在有害气体检测中的地位和作用。介绍了三类 不同红外光源的结构原理,比较了它们相互之间的优缺点,并对其应用情况进行了综述。然后详细分析 了气体检测技术对红外光源性能的要求以及在光源选型时的注意事项。最后,根据有害气 体检测的发展需求,阐明了红外光源的发展趋势。     

Spectral density function of multilevel continuous-phase FM

Compact formulas are derived for the spectral density function of an ensemble of continuous-phase constant-envelope multilevel FM waves. The results are general and are presented in terms of averages of elementary functions. Both continuous and discrete spectra are treated, and conditions in terms of the modulation parameters are given under which lines in the spectrum are present. The formulas are applicable in the study ofN-ary FM data transmission systems as well as in pulse frequency modulation.     

Analysis of the fast acquisition method in frequency hopping systems

Versions of implementing initial synchronization in systems with pseudorandom operating frequency tuning are studied. These versions are based on applying a recurrent acquisition with an autoregressive spectral estimation. Known algorithms are analyzed, and versions of their modification are proposed. Simulation models of considered solutions are constructed, and quantitative data that characterize their noise immunity are obtained.     

Stability of digital filters implemented with two's complementtruncation quantization

The stability of digital filters implemented with two's complement truncation quantization is investigated. Both the direct-form and normal-form realizations are considered and regions in the parameter plane are obtained where the filters are globally asymptotically stable. Regions within the stability triangle of a direct-form digital filter are also studied where limit cycles of period one and two are possible. The results are illustrated with several examples     

星载寄生式SAR系统干涉性能与空间分辨能力分析

以星载寄生式SAR系统成像信号模型为基础,详细分析了这一新系统的干涉性能和空间分辨能力,给出了 各自的限制条件。分析了两者限制的本质一致性,并统一以基线形式表示出来,同时提出了距离向有效基线和方位向有效 基线的新概念。最后以Cartwheel编队构形进行了实例分析,特别指出了基线耦合、多基线对性能的影响。     

导电聚苯胺在铝电解电容器中的应用

导电高分子在电子元件中的应用十分广泛。比较了几种用于铝电解电容器中的固体电解质:二氧化锰、TCNQ、聚吡咯、聚苯胺,其中聚吡咯、聚苯胺的性能优势明显,尤其是聚苯胺的电导率和热稳定性最好。介绍了聚苯胺结构特征、合成方法以及聚苯胺铝电解电容器的制造方法和性能,展望了聚苯胺的应用前景。     

Robust estimators of the 2-parameter gamma distribution

The available estimators for parameters of the gamma distribution are moment estimators, maximum-likelihood estimators, and approximations to the maximum-likelihood estimators. These estimators are not suitable for small samples; however, they are still being used at the present time. The proposed robust estimators for scale and shape parameters are more suitable for small samples. They have RMS (root-mean-square) errors that are considerably smaller than those of the other estimators. In addition, they are easier to calculate, and are therefore appropriate in many applications     

Human errors: A review

This paper briefly reviews human errors in engineering systems. Definitions for human reliability and human errors are presented. Consequences and causes of human errors are discussed. Historical developments in human reliability are briefly described. Breakdowns of human errors are given. Human error prevention and reduction methods are discussed along with human reliability data banks. In particular, Data Store and Operational Recording and Data System (OPREDS) are described. Human errors in structures and computer systems are discussed. Error rates for selected tasks are presented.     

高阶模糊函数的收敛性分析

本文讨论用于多项式相位信号参数估计的高阶模糊函数的收敛性质.对于复高斯白噪声污染的时变振幅多项式相位信号,证明了其高阶模糊函数样本估计和相位多项式最高阶系数估计的强收敛性质.特别地,对于常数振幅情形,得到了多项式系数估计的强收敛速度.模拟实验证实了所得到的理论结果.     

A syntax-directed translation for the synthesis ofdelay-insensitive circuits

A syntax-directed translation procedure for the synthesis of delay-insensitive circuits from graph-theoretic specifications is presented. No isochronic fork assumption is required for the correct operation of the synthesized circuits. The synthesized circuits are different from those obtained from Ebergen's synthesis method. In Ebergen's circuits, the voltage levels of a set of wires are used to encode which input events are most recently received. Special circuit elements (the N-element or the RCEL element) and two-phase to four-phase converters are needed to change the voltage levels of the encoding wires when input events are received. In the circuits obtained from the method in this paper, the wires encoding which input events are most recently received are the outputs of the toggles. When input events are received, they are sent directly or via demultiplexers to the toggles to change the voltage levels at their outputs. Two-phase to four-phase converters are not needed. The synthesis method is compared with Ebergen's synthesis method