Correction factor for resistivity and Hall mobility measurement of two-layer structures by spreading resistance techniques

The spreading resistance of a circular disc contact located on a two-layer semiconductor structure, and its relative change due to magnetic field has been determined, with the magnetic field perpendicular to the contact face, and with the physical magnetoresistance zero in both layers. The correct value of the spreading resistance differs from the result obtained by the usual approximation, especially if the contact diameter is comparable with the thickness of the upper layer. The conditions are given when the relative change in resistance due to the magnetic field is determined by the mobility in the upper layer only. The results show the applicability of the spreading magnetoresistance technique in determining the Hall mobility in a two-layer structure.     

Experimental design of a two-layer electromagnetically coupledrectangular patch with a global response surface modeling technique

A new approach, based on global response surface (GRS) modeling techniques, is used to design two-layer electromagnetically coupled rectangular patch antennas. Data from a grid of design points is used to construct a model of the input impedance of the antenna. The model is then optimized to provide the best design geometries for the frequency band of interest. Three examples are presented to validate the method     

THEORY AND APPLICATION OF FIELD PERTURBATION TO ELECTRICAL IMPEDANCE TECHNIQUE FOR MEDICINE

A new approach called field perturbation theory is presented to analyze the electricalimpedance technique for medicine.The formula of constant voltage and constant current fieldperturbation,modified G-L formula and the formula of electrical field perturbation evoked bysound field are derived.The application results of the theory in electroglottography are alsointroduced.     

Theory and application of a nondestructive photovoltaic technique for the measurement of resistivity variations in circular semiconductor slices

A nondestructive photovoltaic technique for measuring resistivity variations in high-resistivity semiconductor slices is described. The underlying theory of this measurement is reviewed, and the necessary expressions for its implementation are derived for a case of a small light spot scanned over a diameter of a large circular slice. The reduction of these theoretical results to practice is discussed and their validity demonstrated by comparing the results obtained with the photovoltaic technique to resistivity profiles of the same slice diameter measured by four-probe techniques.     

Bragg gratings in two-layer core planar silica-on-silicon waveguides and application to integrated lasers

A neodymium-doped glass waveguide laser based on a new structure employing two core layers is reported. This double-layer structure allows a photosensitive layer to be integrated with an efficient gain layer. Singlemode operation was obtained with a lasing threshold of 93 mW and an efficiency of 0.6%     

A two-layer magneto-TLM contact resistance model: application tomodulation-doped FET structures

The resistance for a two-layer structure with planar contacts is derived, with both the contacts and the region between the contacts modeled as transmission lines. Magnetic field effects are included, yielding additional information on mobilities and carrier concentrations. The theory can be fitted to the usual resistance-versus-contact-separation data as a function of magnetic field strength. Fitted parameters include mobilities and carrier concentrations in each layer, both under the contact and in the bulk material between the contacts, as well as specific contact resistivities for the contact barriers. Experimental results are obtained for an AlGaAs/InGaAs modulation-doped FET structure     

直放站的原理与应用

直放站是随着移动通信的发展而出现的一种无线通信设备。直放站的应用在第一代模拟移动通信网建立时就已经开始，当时的设备体积大、价格高、指标较差，使用中经常对网络造成干扰。目前使用的直放站设备外观和指标已经大大改善，但调试不好也会影响系统的性能。直放站的大量应用是近两年的事情，尤其随着CDMA网开通和GSM网的深度覆盖，制造厂家明显增多。     

条形码技术及应用

介绍了条码技术中的扫描和译码原理，在此基础上详细讨论了条码的制作技术和制作标准。     

雕刻技术的研制和应用

在对铝合金铸件进行X射线实时探伤时，由于采集回来的许多图像的目标物体的轮廓比较模糊，这样在评片时容易造成对铸件的误判和漏判。针对这种现象并结合这类图像噪声源多的特点，在研究常用卷积算法的基础上，采用特殊卷积（特殊的卷积核）操作，同时根据雕刻的艺术底色为灰色，最后给卷积结果加上灰度值128，实验结果表明图像中目标物体的轮廓变得更清楚，同时处理后的图像具有比较好的三维效果，这给工作人员在看图时带来了方便。     

水流法敷设光缆技术的研究与应用*

本文介绍了水流法敷设光缆技术的施工原理,对该技术的应用优势进行了分析。水压机产生高压水流作用于光缆表面形成的拖曳力以及气吹机对光缆的机械推力是光缆前进的动力,管道中水对光缆的浮力作用可减小管道对光缆的摩擦阻力。水敷法技术要求施工环境具备稳定、充沛的水源,具有敷设效率高、施工成本低、安全性高、提高管道利用率以及易于光缆更换升级的特点。国内已有气吹施工单位成功应用水敷缆技术的案例,在管道情况复杂条件下亦可通过该技术进行长距离光缆敷设。     

Transmission through a two-layer array of loaded slots

The mutual admittance method is used to calculate the transmission through a two layer array of slots. The slot arrays are thin and parallel. The plane wave illumination is at an arbitrary angle in either theE-plane orH-plane. The mutual admittance between two slot antennas, either in the same or different planes, is derived. In this derivation it is assumed that the slots are small enough so that when short-circuited at their terminals the electric field scattered from the slot is negligible. The evaluation of the mutual admittance sums is simplified by the extension to the slot case of certain impedance relationships established previously for a two-layer dipole array. For many applications the two-layer slot array is more desirable than a single-layer array since a wider passband and sharper skirts can be obtained with proper design. The analysis shows, however, that for high incidence angles the dip in the center of the passband may be deeper than for the similar two-layer dipole array.     

Microwave remote sensing of a two-layer random medium

A two-variable expansion technique is used to solve for the mean Green's function from the Dyson equation under the nonlinear approximation. The Bethe-Salpeter equation then gives rise to a set of modified radiative transfer (MRT) equations which accommodate coherent effects essential to bounded media. It is found that the nonlinear approximation, instead of the more popular bilocal approximation, should be used for the case of bounded media. The two approximations yield identical results for unbounded media. The MRT equations are then solved for a two-layer random medium. The MRT equations give rise to simple and useful solutions which are applicable to both active and passive microwave remote sensing.     

特高压屏蔽测试大厅弱电抗干扰施工原理与工艺

2000k V交流特高压屏蔽测试大厅是利用电磁屏蔽原理,在其内部进行特高压设备研发测试的工艺装置。在测试过程中,存在电晕放电,特高压交变电磁场干扰。弱电集成研究在监控大厅内用屏蔽技术消除辐射干扰及穿越屏蔽层消除、抑制传导干扰方法。屏蔽效能列线图验算,解决了屏蔽效能的工程验算;截止波导管的概念及工程验算,滤波器安装,光纤应用,接地介绍了传导干扰抑制方法。高速球防浪涌设计,屏蔽网线、机柜及门禁系统安装介绍了屏蔽的应用实例。期待对EHV环境弱电施工提供工程借鉴。     

路径重构算子及应用

为了有效地利用目标的长度和方向信息增强目标物体滤波效果,提出一种新的基于形态重构的二值路径重构算子.定义了标识图中路径开的邻域形式;对掩模图划分连通区域;根据标识图中对应区域的δ路径长度,有选择地重构掩模图中的连通区域;利用阈值分解再叠加的方法,将二值路径重构算子推广到灰度图像领域.实验结果表明,本文路径重构滤波器能够有效利用梯度信息,并兼顾目标长度和方向属性,性能优于传统滤波器.     

Theory and application of self-heated thermistors

A thermistor is defined in conjunction with its application as a two-terminal circuit element. The three major thermistor characteristics, by which all applications are classified, are defined and discussed. Of the three characteristics, the static voltage-current characteristic is the subject of emphasis in the discussion, with mention made of both the corresponding applications and the theoretical and practical limitations on the performance of the incorporated thermistors. Small-and large-signal analysis techniques are described and a small-signal equivalent circuit for a thermistor is developed. Both the large- and small-signal analysis techniques are applied to typical thermistor sensor stage circuits wherein the operation of the thermistor is defined by its static voltage-current characteristic. It is shown that the thermistor small-signal analysis, as based on the application of a thermistor small-signal equivalent circuit, and the large-signal analysis, as accomplished by graphical techniques, are completely compatible with their respective counterparts in vacuum tube analysis. As an illustrative example, a thermal conductivity gas analyzer is designed and experimentally evaluated against its theoretical performance as predicted by large-signal analysis. Excellent agreement is shown. A portion of the total range of the gas analyzer is then chosen such as to be in keeping with the constraints imposed on the use of the small-signal equivalent circuit and, again, it is shown that the theoretical response is experimentally verified.     

基于霍尔效应弱磁场测量装置的研制与应用

为了解决弱磁场强度测量困难的问题,基于霍尔效应开发了以线性霍尔元件为探头弱磁场测量装置。对磁场测量装置各部分电路模块进行了详细设计,并结合矩形线圈磁场分布特征进行了实测值与仿真理论值的对比分析。结果表明,测量结果与理论值具有较好的拟合程度,该装置测量精度为0.01 m T,测量范围为±10 m T,最大测量误差为0.29 m T,具有测量精度高、操作简单方便、设计成本低等优点,可应用于各类线圈弱磁场强度的检测及逐点测量实验中。     

光子计数成像技术及其应用

随着微光像增强技术和弱光成像器件的发展 ,光子计数成像技术近年来发展很快并日趋成熟 ,光子计数成像在军事、天文学、物理学、化学、生物学、量子电子学等领域得到了广泛应用。介绍了光子计数成像的原理、技术特点及其应用。     

FPGA动态可重构技术及其应用

本文介绍了ＦＰＧＡ动态可重构技术原理,探讨了其应用前景,并讨论了影响其实用化的有关技术难点。     

Ultraviolet communication technique and its application

With recent developments of deep ultraviolet(DUV)light-emitting diodes and solar-blind detectors,UV communica-tion(UVC)shows great potential in replacing traditional wireless communication in more and more scenarios.Based on the at-mospheric scattering of UV radiation,UVC has gained considerable attention due to its non-line-of-sight ability,omnidirection-al communication links and low background noise.These advantages make UVC an ideal option for covert secure communica-tion,especially for military communication.In this review,we present the history and working principle of UVC with a special fo-cus on its light sources and detectors.Comprehensive comparison and application of its light sources and detectors are provided to the best of our knowledge.We further discuss the future application and outlook of UVC.Hopefully,this review will offer valuable insights into the future development of UVC.     

Characteristics of a two-layer electromagnetically coupled rectangular patch antenna

Experimental results on the characteristics of a two-layer electromagnetically coupled rectangular patch antenna are presented. The variations of pattern shape, 3 dB beamwidth and impedance bandwidth with spacing s between the two layers are studied for s between 0 and 0.37?0. A relatively high-gain region is found for s between 0.31?0 and 0.37?0.