聚苯胺导电纤维对电磁屏蔽效能的影响

本文介绍了聚苯胺导电纤维对电磁屏蔽效能的影响。聚苯胺（PANI）是最重要的导电聚合物之一,金属材料与导电聚苯胺复合形成屏蔽组分有效提高了复合电磁屏蔽材料的高频电磁屏蔽效能,从而扩展了屏蔽材料的屏蔽带宽。本文分析了复合电磁屏蔽材料中聚苯胺导电纤维对屏蔽效能的贡献及作用机理。结果表明聚苯胺与基体树脂相溶形成基体导电网络,有效阻碍了高频电磁波的穿透,是提高高频电磁屏蔽效能的主要原因。     

开孔屏蔽体电磁泄漏的抑制方法

反射式屏蔽抑制电磁泄漏要求屏蔽体具有良好的导电连续性,对屏蔽体上开孔的形状、尺寸、排列有诸多限制;吸波材料对电磁波有吸收作用,可以用来克服反射式屏蔽的不足.文章通过介绍吸波材料和回廊结构对屏蔽体上开孔处电磁泄漏的抑制情况,提出了一种改进的回廊结构.     

电磁防护材料专题

氧化铁-石墨／ABS复合材料制备及电磁屏蔽性能;碳纳米管负载纳米TiO2复合材料的制备及组织结构表征;正交排布碳纤维材料的电磁防护性能研究;电磁波屏蔽复合材料的研究进展;导电聚苯胺／羰基铁粉复合吸收效能的研究.     

滤波线滤波作用机理的概述

介绍了电线可以通过屏蔽、滤波等方式实现电磁兼容,并进一步详述了电磁屏蔽衰减电磁波的机理及缺点。为了克服电磁屏蔽的缺点,在电线的表面加工一层吸波材料,这样的电线就是滤波线。滤波线的滤波机理是在阻抗匹配的前提下,电磁波能最大限度地进入滤波材料内部,在滤波材料内部电磁波衰减主要有电损耗和磁损耗,其中磁损耗主要由磁滞损耗、涡流损耗和剩余损耗引起。通过组合不同吸收特性的滤波材料,可以使滤波线将高频波段的电磁波滤掉,只允许低频波段的电磁波通过。     

通过导电壁上窗口透入的电磁波对人体作用的研究

本文用时域有限差分法和人体非均匀电磁模型研究了通过无限大导电壁上窗口透入的电磁场与人体的相互作用。首先对平面电磁波通过导电壁上窗口的透入特性进行了计算,并与解析解进行比较,证明了计算的可靠性。在此基础上对不同极化情况的入射平面波的透入场与靠近窗口的坐姿人体模型的作用进行了研究。计算了人体模型中的电磁场分布和所吸收的电磁能量。     

基于海水的超宽带低反射、高吸收电磁屏蔽体设计

为了实现电子设备在复杂电磁环境下能安全可靠的工作,提出了一种基于海水溶液的超宽带低反射、高吸收电磁屏蔽体。利用海水介电常数和电导率较高,具有较强的吸波损耗能力这一特性,结合传输线阻抗匹配原理与遗传算法,优化和加载工作在中心频率为0.915GHz的超宽带内的多层匹配媒质层,实现入射电磁波全部进入海水层并被损耗掉。在超宽带内表现出良好的低反射、高吸收的电磁屏蔽效果,并保持较高的电磁屏蔽效能。     

等离子体技术在天线隐身中的应用

利用洛沦兹模型来研究等离子体的电磁响应特性。讨论了电磁波频率、等离子体密度和电子碰撞频率对电磁波衰减特性的影响,描述了等离子体的导电性能、反射和吸收电磁波的能力。提出了三种方式实现天线的隐身设计。分别阐述了几种方式实现隐身的原理,并分析了各自的适用范围和优缺点。     

导电高分子电磁屏蔽材料研究进展

导电高分子材料在电磁屏蔽领域有着广阔的应用前景.文章介绍了导电高分子材料的分类、掺杂、导电机理及电磁屏蔽的基本理论,并对导电高分子电磁屏蔽材料开发现状及应用中存在的问题进行了扼要综述,对其发展趋势做了展望.     

电磁波屏蔽复合材料的研究进展

从电磁波屏蔽的机理出发,介绍导电型、导磁型以及导电导磁型电磁波屏蔽复合材料的发展现状,并展望了电磁波屏蔽材料未来的研究方向。     

助力无线产业发展SRTC国内率先提供SAR测试系统校准服务

SAR(specific absorption rate,电磁暴露)表示手机或无线产品的电磁波能量吸收比值,其定义为:在外电磁场的作用下,人体内将产生感应电磁场,由于人体各种器官均为有耗介质,因此体内电磁场将会产生电流,导致吸收和耗散电磁能量。生物剂量学中常用SAR来表征这一物理过程。     

Development of the readout system for waveguide multilayer optical card

Waveguide multilayer optical card （WMOC） is a novel storage device of three-dimensional optical information. An advanced readout system fitting for the WMOC is introduced in this paper. The hardware mainly consists of the light source for reading, WMOC, motorized stages addressing unit, microscope imaging unit, CCD detecting unit and PC controlling ＆ processing unit. The movement of the precision motorized stage is controlled by the computer through Visual Basic （VB） language in software. A control panel is also designed to get the layer address and the page address through which the position of the motorized stages can be changed. The WMOC readout system is easy to manage and the readout result is directly displayed on computer monitor.     

Nanoimprint Lithography -A Next Generation High Volume Lithography Technique

IntroductionNanoimprint Lithography is a well-acknowl-edged low cost, high resolution, large area pattern-ing process. It includes the most promising methods,high-pressure hot embossing lithography (HEL) [2],UV-cured imprinting (UV-NIL) [3] and micro contactprinting (m-CP, MCP) [4]. Curing of the imprintedstructures is either done by subsequent UV-lightexposure in the case of UV-NIL or by cooling downbelow the glass transition temperature of the ther-moplastic material in case of HEL…     

Collinear phase-matching study of terahertz-wave generation via difference frequency mixed in GaAs and Inp

The collinearly phase-matching condition of terahertz-wave generation via difference frequency mixed in GaAs and InP is theoretically studied. In collinear phase-matching, the optimum phase-matching wave hands of these two crystals are calculated. The optimum phase-matching wave bands in GaAs and lnP are 0.95-1.38μm and 0.7-0.96μm respectively. The influence of the wavelength choice of the pump wave on the coherent length in THz-wave tuning is also discussed. The influence of the temperature alteration on the phase-matching and the temperature tuning properties in GaAs crystal are calculated and analyzed. It can serve for the following experiments as a theoretical evidence and a reference as well.     

Effects of the alloy compositions on the phonon-polaritons in ternary mixed crystals

Composition dependence of bulk and surface phonon-polaritons in ternary mixed crystals are studied in the framework of the modified random-element-isodisplacement model and the Bom-Huang approximation. The numerical results for Several Ⅱ - Ⅵ and Ⅲ- Ⅴ compound systems are performed, and the polariton frequencies as functions of the compositions for ternary mixed crystals AlxGa1-xAs, GaPxAS1-x, ZnSxSe1-x, GaAsxSb1-x, GaxIn1-xP, and ZnxCd1-xS as examples are given and discussed. The results show that the dependence of the energies of two branches of bulk phonon-polaritons which have phonon-like characteristics, and surface phonon-polaritons on the compositions of ternary mixed crystals are nonlinear and different from those of the corresponding binary systems.     

Influence of PVK ： NPB hole transporting layer on the characteristics of organic light-emitting devices

A doping system consisting of NPB and PVK is employed as a composite hole transporting layer （CHTL）. By adjusting the component ratio of the doping system, a series of devices with different concentration proportion of PVK ： NPB are constracted. The result shows that doping concentration of NPB enhances the competence of hole transporting ability, and modifies the recombination region of charge as well as affects the surface morphology of doped film. Optimum device with a maximum brightness of 7852 cd/m^2 and a power efficiency of 1.75 lm/W has been obtained by choosing a concentration proportion of PVK ： NPB at 1：3.     

New insert layer structure OLEDs

An insert layer structure organic electroluminescent device（OLED） based on a new luminescent material （Zn（salen）） is fabricated. The configuration of the device is ITO/CuPc/NPD/Zn（salen）/Liq/LiF/A1/CuPc/NPD/Zn（salen）/Liq/LiF/A1. Effective insert electrode layers comprising LiF（1nm）/Al（5 nm） are used as a single semitransparent mirror, and bilayer cathode LiF（1 nm）/A1（100 nm） is used as a reflecting mirror. The two mirrors form a Fabry-Perot microcavity and two emissive units. The maximum brightness and luminous efficiency reach 674 cd/m^2 and 2.652 cd/A, respectively, which are 2.1 and 3.7 times higher than the conventional device, respectively. The superior brightness and luminous efficiency over conventional single-unit devices are attributed to microcavity effect.     

Analysis of error performance on Turbo coded FDPIM

Due to variable symbol length of digital pulse interval modulation（DPIM）, it is difficult to analyze the error performances of Turbo coded DPIM. To solve this problem, a fixed-length digital pulse interval modulation（FDPIM） method is provided. The FDPIM modulation structure is introduced. The packet error rates of uncoded FDPIM are analyzed and compared with that of DPIM. Bit error rates of Turbo coded FDPIM are simulated based on three kinds of analytical models under weak turbulence channel. The results show that packet error rate of uncoded FDPIM is inferior to that of uncoded DPIM. However, FDPIM is easy to be implemented and easy to be combined, with Turbo code for soft-decision because of its fixed length. Besides, the introduction of Turbo code in this modulation can decrease the average power about 10 dBm, which means that it can improve the error performance of the system effectively.     

A method for calculating the center position of collimated light

It is a key problem to accurately calculate beam spots＇ center of measuring the warp by using a collimated laser. A new method, named double geometrical center method （DGCM）, is put forward for the first time. In this method, a plane wave perpendicularly irradiates an aperture stop, and a charge couple device （CCD） is employed to receive the diffraction-beam spots, then the geometrical centers of the fast and the second diffraction-beam spots are calculated respectively, and their mean value is regarded as the center of datum beam. In face of such adverse instances as laser intension distributing defectively, part of the image being saturated, this method can still work well. What＇s more, this method can detect whether an unacceptable error exits in the courses of image receiving, processing and calculating. The experimental results indicate the precision of this method is high.     

Cost-effective test solutions for smart card and other integrated flash applications

From its emergence in the late 1980s as a lower cost alternative to early EEPROM technologies, flash memory has evolved to higher densities and speedsand rapidly growing acceptance in mobile applications.In the process, flash memory devices have placed increased test requirements on manufacturers. Today, as flash device test grows in importance in China, manufacturers face growing pressure for reduced cost-oftest, increased throughput and greater return on investment for test equipment. At the same time, the move to integrated flash packages for contactless smart card applications adds a significant further challenge to manufacturers seeking rapid, low-cost test.     

An improved parallel thinning algorithm with two subiterations

The parallel thinning algorithm with two subiterations is improved in this paper. By analyzing the notions of connected components and passes, a conclusion is drawn that the number of passes and the number of eight-connected components are equal. Then the expression of the number of eight-connected components is obtained which replaces the old one in the algorithm. And a reserving condition is proposed by experiments, which alleviates the excess deletion where a diagonal line and a beeline intersect. The experimental results demonstrate that the thinned curve is almost located in the middle of the original curve connectivelv with single pixel width and the processing speed is high.