A High Gain and Broadband C-Band Aperture-Coupled Patch Antenna

A aperture-coupled patch antenna is designed with parasitic elements connecting to the rectangle ring on the bottom of antenna substrate through metal vias, which lead the current induced by patch radiator to the top surface of antenna substrate. Therefore, the effective radiation is enhanced and higher gain is achieved. The bandwidth is broadened simultaneously due to the structure of aperture-coupled patch antenna with parasitic elements. Compared to the conventional aperture-coupled patch antenna, the antenna gain increases averagely 2 dB due to the novel structure. Compared to patch antenna of electromagnetic band-gap, the dimensions of novel patch antenna greatly decreases, which can be used as element in the array antenna. Two kinds manufactured antenna are both measured in an anechoic chamber. The good agreements between numerical simulation and experimental prototype have been obtained.     

奇异系统Hamilton正则方程的Mei对称性、Noether对称性和Lie对称性

研究奇异系统Hamilton正则方程的形式不变性即Mei对称性，给出其定义、确定方程、限制方程和附加限制方程.研究奇异系统Hamilton正则方程的Mei对称性与Noether对称性、Lie对称性之间的关系，寻求系统的守恒量.给出一个例子说明结果的应用. 关键词： 奇异系统 Hamilton正则方程 约束 对称性 守恒量     

256色模式下调色板的匹配

在计算机屏幕上同时显示两幅颜色相差较大、调色板各异的图像，需要匹配两幅图像的调色板．本文引入了两种匹配算法：颜色中和算法和颜色分类算法，并分别详述这两种算法的基本原理和在２５６色模式下的实现方法．     

Terahertz electromagnetic radiation from quantum wells

The observation of terahertz electromagnetic dipole radiation from quantum well structures has finally proven the existence of charge oscillations in semiconductors associated with wave packet dynamics. This article closely examines the physics behind the emission of terahertz electromagnetic radiation from excitonic charge oscillations in such quantum well structures, points out similarities and differences between the various generation schemes, and discusses the various relaxation mechanisms involved. Finally, we show how both amplitude and phase of charge oscillations and the corresponding terahertz emission can be manipulated using phase-locked optical pulses.     

Error bounds for analytic systems and their applications

Using a 1958 result of Lojasiewicz, we establish an error bound for analytic systems consisting of equalities and inequalities defined by real analytic functions. In particular, we show that over any bounded region, the distance from any vectorx in the region to the solution set of an analytic system is bounded by a residual function, raised to a certain power, evaluated atx. For quadratic systems satisfying certain nonnegativity assumptions, we show that this exponent is equal to 1/2. We apply the error bounds to the Karush—Kuhn—Tucker system of a variational inequality, the affine variational inequality, the linear and nonlinear complementarity problem, and the 0–1 integer feasibility problem, and obtain new error bound results for these problems. The latter results extend previous work for polynomial systems and explain why a certain square-root term is needed in an error bound for the (monotone) linear complementarity problem.The research of this author is based on work supported by the Natural Sciences and Engineering Research Council of Canada under grant OPG0090391.The research of this author is based on work supported by the National Science Foundation under grants DDM-9104078 and CCR-9213739 and by the Office of Naval Research under grant 4116687-01.     

Convexification of Nonsmooth Monotone Functions<Superscript>1</Superscript>

We consider a convexification method for a class of nonsmooth monotone functions. Specifically, we prove that a semismooth monotone function can be converted into a convex function via certain convexification transformations. The results derived in this paper lay a theoretical base to extend the reach of convexification methods in monotone optimization to nonsmooth situations. Communicated by X. Q. Yang This research was partially supported by the National Natural Science Foundation of China under Grants 70671064 and 60473097 and by the Research Grants Council of Hong Kong under Grant CUHK 4214/01E.     

非定常的热传导-对流问题的非线性Galerkin混合元法(Ⅲ):时间二阶精度的全离散格式

In this paper, a fully discrete format of nonlinear Galerkin mixed element method with two-step discretization of time for the non stationary conduction-convection problems is presented. The existence and the convergence of the fully discrete mixed element solution are shown. On the basis of [9] and [10], we have proved that the schemes have second-order convergence accuracy for the time discretization.     

Application of computer vision and laser interferometer to the inspection of line scale

In the paper machine vision, laser interferometer and coordinate measuring machine (CMM) are combined to develop a vision inspection system. The measurement capability of the developed system is investigated by measuring the distances between the lines on a standard line scale. The vision camera is used to replace the probe of the CMM to take the images of the interested lines on a line scale at two different positions. Meanwhile, the displacement of the CCD camera is measured using laser interferometer. Using subpixel edge localization and outlier-excluding least-squares regression, the distance between two interested lines is computed under an image plane coordinate system. By adding the displacement of the CCD camera measured using laser interferometer, the line space can be determined. Experiments have been performed repeatedly to measure the line space on the 1.00 and 300.0 mm line scales. Results indicate that the measured data only have a little fluctuation and are close to those obtained by the NML (National Measurement Laboratory, Taiwan).     

Anomalous magnetoresistance in [ Sr2Bi2-xPbxO4] RS[ CoO2] y (x = 0, 0.3, and 0.4; y ≈ 1.85) single crystals

Magnetoresistance (MR) of the [ Sr₂Bi_2-xPb_xO₄] ^RS[ CoO₂] _y (x = 0, 0.3, and 0.4; y ≈ 1.85; RS is referred to rocksalt block) single crystals is investigated systematically. A nonmonotonic variation of the isothermal in-plane and out-of-plane MR with the field is observed. The out-of-plane MR is positive at high temperatures and increases with decreasing T, and exhibits a pronounced hump, then changes the sign from positive to negative at a certain temperature. These results strongly suggest that the observed MR consists of two contributions: one negative and one positive component. The isothermal MR in high magnetic fields follows a H² law. The negative contribution comes from spin scattering of carriers by localized-magnetic-moments based on the Khosla-Fischer model.     

Synthesis and characterization of novel aromatic poly(imide–benzoxazole) copolymers

New poly(imide–benzoxazole) copolymers were prepared directly from a dianhydride, a diacid chloride, and a bis(o‐diaminophenol) monomer in a two‐step method. In the first step, poly(amic acid–hydroxyamide) precursors were synthesized by low‐temperature solution polymerization in an organic solvent. Subsequently, the thermal cyclodehydration of the poly(amic acid–hydroxyamide) precursors at 350 °C produced the corresponding poly(imide–benzoxazole) copolymers. The inherent viscosities of the precursor polymers were around 0.19–0.33 dL/g. The cyclized poly(imide–benzoxazole) copolymers had glass‐transition temperatures in the range of 331–377 °C. The 5% weight loss temperatures ranged from 524 to 535 °C in nitrogen and from 500 to 514 °C in air. The poly(imide–benzoxazole) copolymers were amorphous, as evidenced by the wide‐angle X‐ray diffraction measurements. The structures of the precursor copolymers and the fully cyclized copolymers were characterized by Fourier transform infrared, ¹H NMR, and elemental analysis. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 6020–6027, 2005