Three-Phase Rectifier With Near Sinusoidal Input Currents and Capacitors Connected on the AC Side

An analysis of a three-phase low-harmonic diode rectifier equipped with inductors, capacitors connected on the ac side, and diodes is presented. Inductors and capacitors are used in conjunction with the three-phase diode bridge rectifier to improve the waveform of the currents drawn from the utility grid. The operation of the proposed converter is analyzed, and on this basis, design considerations are commented. The converter characteristics are determined as a function of the load current. Comparisons between the studied converter and other rectifiers (classical rectifiers with passive or active filters, three-phase rectifiers with near sinusoidal input currents and capacitors connected on the dc side, and three-phase low-harmonic rectifiers applying the third harmonic current injection) are also presented. Several possible applications of the two variants of the three-phase rectifiers with near sinusoidal input currents (with capacitors connected on the dc side or on the ac side) are mentioned. Analytically derived results are experimentally verified     

Small-signal analysis and design of weighted voltage control for amultiple-output forward converter

The small-signal model for a multiple-output forward power converter with weighted voltage control is derived. The effects of the weighting factors on the small-signal behavior are investigated. In addition, the small-signal characteristics of weighted voltage control are compared with the characteristics of a multiple-output power converter with coupled output-filter inductors. Finally, the effects of weighted voltage control on the small-signal characteristics of the converter with coupled inductors are examined. Based on the analysis, the design procedure for loop compensation is presented. The small-signal model and the design procedure are verified on an experimental two-output forward power converter     

Integral equation method in problems of electromagnetic-wave reflection from inhomogeneous interfaces between media

Problems on reflection of a plane electromagnetic wave from various irregular interfaces between media are studied by the integral equation method in the cases of two- and three-dimensional incident electromagnetic field. The reflecting surfaces are meant as periodic transparent interfaces between two media and plane boundaries with locally inhomogeneous and transparent sections. The boundary value problems for the system of Maxwell’s equations in an infinite domain with an irregular boundary are reduced to Fredholm or singular integral equations, depending on the problem considered. Numerical algorithms for solving such integral equations are developed. Results of calculation of currents induced on inhomogeneities and characteristics of the electric field in the far zone are presented.Problems on reflection of a plane electromagnetic wave from various irregular interfaces between media are studied by the integral equation method in the cases of two- and three-dimensional incident electromagnetic field. The reflecting surfaces are meant as periodic transparent interfaces between two media and plane boundaries with locally inhomogeneous and transparent sections. The boundary value problems for the system of Maxwell’s equations in an infinite domain with an irregular boundary are reduced to Fredholm or singular integral equations, depending on the problem considered. Numerical algorithms for solving such integral equations are developed. Results of calculation of currents induced on inhomogeneities and characteristics of the electric field in the far zone are presented.     

两镜系统分析

本文根据三级像差理论,讨论了满足系统为会聚光路、系统遮拦比|α|<1两个条件的两镜系统,分析了以消球差S_1=0为初始条件,同时校正其余像差系数S_(II),S_(III)的系统。对在不同非球面系数条件下,主镜、副镜的面形以及比较半径R_1,R_2随遮拦比α和放大率β的变化作了分析,并总结了现有已命名的经典系统。     

Linear codes with covering radius 2, 3 and saturating sets in projective geometry

Infinite families of linear codes with covering radius R=2, 3 and codimension tR+1 are constructed on the base of starting codes with codimension 3 and 4. Parity-check matrices of the starting codes are treated as saturating sets in projective geometry that are obtained by computer search using projective properties of objects. Upper bounds on the length function and on the smallest sizes of saturating sets are given.     

铝箔微孔的飞秒激光加工艺的研究

在飞秒激光与金属材料相互作用研究的基础上,在不同的激光器运行参数条件下利用飞秒激光器在金属铝箔上制备阵列微孔,研究了对阵列微孔的孔径与激光器工艺参数之间的关系。利用Origin7.0及SPSS13.0对实验数据进行分析,指明了飞秒激光器脉冲数、脉宽、单脉冲能量对孔径大小的影响。     

Cache sampling by sets

An approach to workload sampling in which, instead of selection of memory references based on the time parameter, sample decisions are based on where the cache is accessed. More specifically, the sampling heuristics are focused on analysis for set-associative caches. The validity of the heuristics is supported with empirical data. Four sampling policies are discussed, and simulation results based on a commercial database transaction workload are presented. Observations from simulation studies with SPEC 1.0 uniprogram benchmarks are also described. An environment in which congruence class sampling may be useful is illustrated     

超图理论及其应用

综述了超图理论及其应用方面的主要研究成果，提出了一些新的概念和研究途径，探讨了超图理论及其应用方面的四个课题，讨论了超图理论及其应用的发展前景，提出了一些尚待研究的问题。     

Amplitude, width, and interarrival distributions for noise impulseson intrabuilding power line communication networks

Estimates are presented of probability distributions for the amplitude, width, and interarrival time of noise impulses. These estimates are based on measurements in both industrial and residential buildings and usefully complement the noise spectral density estimates of others. The results are based on measurements with and without specific electrical loads on the 120-V power line network. All measurements are between line and neutral conductors. The harmful effects of power line impulse noise on digital communications are indicated. Some suggestions for combatting these effects are presented, based on the impulse noise measurement results     

Digital satellite networks in Europe

Developments of digital satellite networks are progressing in Europe at international as well as national levels. EUTELSAT and its signatories are actively setting up two regional networks based on the ECS satellites built by ESA. One will carry large bundles of telephone circuits between national gateways; the other will provide special services to corporate organizations and businesses. On the other hand, several countries are implementing or planning their own national networks, all for small-station services. These are France with Telecom 1, Sweden with TELE-X, Norway with NORSAT II, Italy with ITALSAT, the Federal Republic of Germany with DFS/Copernicus, and the United Kingdom with UNISAT. These projects are described here and their characteristics compared. The paper brings out the great diversity in the approaches, as illustrated by Telecom 1 where the accent is on the development of an ISDN, TELE-X where it is on the low cost of user stations, and ITALSAT on the flexibility of the network.     

Variational method for planar transmission lines with anisotropicmagnetic media

Upper and lower bounds on the line inductances are presented for the first time for planar transmission lines with anisotropic magnetic media. Green's functions are derived for the general structure by using recurrent relations. Numerical examples involving striplines and coplanar waveguide are presented, and the calculated values of the quasi-static characteristics of stripline on an anisotropic magnetic substrate with the tensor permeability are in good agreement with measured values     

Methods for null control and their effects on the radiation pattern

Several methods for synthesis of array antenna patterns with prescribed nulls are reviewed. Methods based on full amplitude/phase control at each array element and methods with a restricted number of degrees of freedom are compared, with attention focused on the characteristic features of the resultant patterns. These features are largely independent of any algorithm for achieving the nulls, and therefore they also provide a perspective on the performance of adaptive antenna systems, which employ these various control architectures.     

脊位于窄边的四种加载介质波导传输特性的有限元计算

运用矢量有限元方法对脊位于窄边的四种加载介质双脊波导的主模截止波长和单模带宽特性进行了计算和分析,四种波导分别为脊位于窄边的加载介质双脊矩形波导、加载介质双脊梯形波导、加载介质双脊V形波导以及加载介质双脊椭圆形波导。计算结果表明,脊位于窄边的四种加载介质双脊波导的两种传输特性总体相似,和脊位于宽边相比,脊位于窄边的主模归一化截止波长和单模带宽总体小很多,且脊位于宽边时的特性变化趋势比脊位于窄边时剧烈。这些计算结果将有助于微波器件及微波系统的设计。     

Detailed resist film modeling in stochastic lithography simulation for line-edge roughness quantification

Modeling the lithography process with stochastic principles enables the consideration of resist material and process effects variability on critical dimensions and line-edge or line-width roughness of printed features. These principles are applied for a resist system where polymer and photo-acid-generator (PAG) are blended, and for the same system with the PAG molecules bonded on the main polymer chain. Three-dimensional chain-like models of resist and PAG are considered and examples of their effect on critical dimensions and on resist edge roughness are presented. Comparison with experimental results from the literature proves the validity of the current approach and suggests that it can be used for the prediction of the resist resolution and low roughness capabilities.     

Influence of Bioreceptor Layer Structure on Myelin Basic Protein Detection using Organic Field Effect Transistor‐Based Biosensors

Organic field‐effect transistor (OFET)‐based biosensors with antibody receptors are widely considered for protein antigen detection. To the authors' knowledge, there are no comparative evaluations to date of different choices for the matrix polymer to which the antibodies are attached. Herein, multiple acrylic copolymers are studied as receptor layers with myelin basic protein and its corresponding antibody as an archetypal antibody–antigen pair. Stability against multiple washing steps and the capacity for immobilizing antibodies on polymers on device surfaces with the help of fluorescein isothiocyanate‐labeled antibodies are compared. Electronic detection and selectivity are also observed. The conclusions provide guidance on the selection of bioreceptor material for increasing sensitivity and process stability of OFET biosensors.     

Si衬底和Si-SiO_2-Si柔性衬底上的GaN生长

使用MBE方法在Si(111)衬底和Si SiO2 Si柔性衬底上生长了GaN外延层 ,并对在两种衬底上生长的样品进行了对比分析 .在柔性衬底上获得了无裂纹的外延层 ,其表面粗糙度为 0 6nm .研究了GaN外延层中的应力及其光学性质 ,光致发光测试结果表明柔性衬底上生长的外延层中应力和杂质浓度明显低于直接生长在Si衬底上的样品的值 .研究结果显示了所用柔性衬底有助于改善GaN外延膜的质量     

八角晶格光子晶体光纤的色散特性分析

应用多极法对八角晶格光子晶体光纤(O-PCF)的色散特性进行了数值模拟,并与空气填充率相同的六角晶格光子晶体光纤(H-PCF)进行了对比,发现O-PCF比H-PCF更易用于色散补偿;研究了O-PCF包层空气孔直径、孔间距和孔层数对色散特性的影响,得到了色散随各个结构参数变化的规律;最终选择了适当的结构参数,设计了在1.3～1.6 μm波段内具有超平坦零色散特性的O-PCF.文章的计算和分析可以为设计适当色散特性的光子晶体光纤提供理论依据.     

Detecting landmines with ground-penetrating radar using feature-based rules, order statistics, and adaptive whitening

An approach to detecting landmines using ground-penetrating radar (GPR) based on feature-based rules, order statistics, and adaptive whitening (FROSAW) is described. FROSAW relies on independent adaptation of whitening statistics in different depths and combining feature-based methods with anomaly detection using rules. Constant false alarm rate (CFAR) detectors are used for anomaly detection on the depth-dependent adaptively whitened data. A single CFAR confidence measure is computed via a function of order statistics. Anomalies are detected at locations with high CFAR confidence. Depth-dependent features are computed on regions containing anomalies. Rules based on the features are used to reject alarms that do not exhibit mine-like properties. The utility of combining the CFAR and feature-based methods is evaluated. The algorithms and analysis are applied to data acquired from tens of thousands of square meters from several outdoor test sites with a state-of-the-art array of GPR sensors.     

An information-theoretic and game-theoretic study of timing channels

This paper focuses on jammed timing channels. Pure delay jammers with a maximum delay constraint, an average delay constraint, or a maximum buffer size constraint are explored, for continuous-time or discrete-time packet waveforms. Fluid waveform approximations of each of these classes of waveforms are employed to aid in analysis. Channel capacity is defined and an information-theoretic game based on mutual information rate is studied. Min-max optimal jammers and max-min optimal input processes are sought. Bounds on the min-max and max-min mutual information rates are described, and numerical examples are given. For maximum-delay-constrained (MDC) jammers with continuous-time packet waveforms, saddle-point input and jammer strategies are identified. The capacity of the maximum-delay constrained jamming channel with continuous-time packet waveforms is shown to equal the mutual information rate of the saddle point. For MDC jammers with discrete-time packet waveforms, saddle-point strategies are shown to exist. Jammers which have quantized batch departures at regular intervals are shown to perform well. Input processes with batches at regular intervals perform well for MDC or maximum-buffer-size-constrained jammers.     

MEMS光开关

采用 MEMS体硅工艺 ,制作了三种结构的微机械光开关 :水平驱动 2 D(二维 )光开关、垂直驱动 2 D光开关和扭摆驱动 2 D、3D(三维 )光开关 .水平驱动光开关采用单层体硅结构 ,另外两种光开关都采用了硅 -玻璃的键合结构 .它们的工作原理都基于硅数字微镜技术 .这三种光开关均采用了静电力驱动 ,具有较低的驱动电压 ,其中扭摆式光开关的驱动电压小于 15 V.对于 2 D开关阵列 ,在硅基上制作了光纤自对准耦合槽 .对后两种光开关的开关特性进行了计算机模拟与分析 ,结果表明这两种光开关具有小于 1ms的开关时间