Characterizing microwave planar circuits using the coupledfinite-boundary element method

A general approach is presented for the analysis of microwave planar circuits. The technique is particularly well suited to the analysis of circuits with complicated geometries and dielectric loads. The technique is a hybrid, consisting of an amalgamation of the finite-element and boundary-element techniques. It can handle problems with mixed electric and magnetic walls, as well as complicated dielectric loads, such as those composed of ferrite materials. Computed and measured data for various complicated devices are compared, showing excellent agreement     

Improved decoder for transform coding with application to the JPEGbaseline system

Transform coding, a simple yet efficient image coding technique, has been adopted by the Joint Photographic Experts Group (JPEG) as the basis for an emerging coding standard for compression of still images. However, for any given transform encoder, the conventional inverse transform decoder is suboptimal. Better performance can be obtained by a nonlinear interpolative decoder that performs table lookups to reconstruct the image blocks from the code indexes. Each received code index of an image block addresses a particular codebook to fetch a component vector. The image block can be reconstructed as the sum of the component vectors for that block. An iterative algorithm for designing a set of locally optimal codebooks is developed. Computer simulation results demonstrate that this improved decoding technique can be applied in the JPEG baseline system to decode enhanced quality pictures from the bit stream generated by the standard encoding scheme     

A new design of the CMOS full adder

By using the transmission function theory, two CMOS full adders are designed, both of which have simpler circuits than the conventional full adder. Computer simulations with SPICE2G5 show that they can realize the expected logic functions and they have desirable transfer characteristics     

Analytical expressions of the guided mode field distribution:analysis and comparison

Methods for determining the parameters of the three different approximate solutions for the fundamental mode field distribution of Ti:LiNbO₃ optical waveguides by using the variational technique are presented. This analysis gives closer approximation not only to the field distribution, but also to the propagation constant. Comparison with the exact results for the exponential index distribution in depth shows that these trial functions are closer to the real solution. It is also shown that these solutions are as accurate as the effective index method for Ti:LiNbO₃ strip waveguides. The analysis provides an approach for comparing and assessing these solutions     

时间延迟谱技术及测量系统

时间延迟谱技术(TDS)是一项较新的测量技术,它可以用于测量电声系统的复频响应和复时域响应。本文讨论了TDS的一些基本概念和一种简化的实现方法并给出了一个具体的测量系统。该系统由本文作者设计,它以一台IBMPC-AT为核心,软件为主体,具有丰富的测量功能。最后,本文给出了一些测量实例以演示和验证这套系统的功能。     

日本广播电视的新动向

本文介绍了日本广播电视的发展动向!并且简要集中地介绍了日本HDTV及EDTV两种新的电视广播形式。     

面向对象的程序设计在机载雷达模拟器软件中的应用

面向对象的程序设计方法在软件设计中得到了越来越广泛的应用。随着计算机内存的增加与速度的显著提高,雷达软件的设计趋向于模块化,以提高程序的可移植性与可维护性。详细讨论了面向对象的程序设计方法在机载雷达模拟器软件设计中的应用及Ｃ＋＋语言的实现。     

基于最小能量原理的SMT焊点三维形态预测

本文应用最小能量原理和有限元方法建立表面组装技术（ＳＭＴ：Ｓｕｒｆａｃｅ Ｍｏｕｎｔ Ｔｅｃｈｎｏｌｏｇｙ）形成的焊点三维形态预测模型,并运用该模型对塑料球栅阵列（ＰＢＧＡ：Ｐｌａｓｔｉｃ Ｂａｌｌ Ｇｒｉｄ Ａｒｒａｙ）器件焊点三维形态问题进行了预测和分析。最后将预测结果与试验结果以及国外学者用数学分析模型所得的预测结果进行了对比验证。     

红外光谱辐射计的研制

介绍了红外光谱辐射计的组成及工作原理,分析了其信号处理方法。红外光谱辐射计的核心是分光元件、光学系统及信号处理部分。该设备采用容易调整的高像质反射光学系统和波长在２５～１４μｍ连续可变的分光系统,并采用高集成度、高精度的数据采集、数字锁相和数据处理、存储系统。观察瞄准、探测接收的光学系统以及数据采集、处理系统都被放到一个体积很小的测量头中,具有体积小、质量轻牢固可靠、抗干扰性能强和使用方便等优点。入瞳的最小可探测率为１０－１２Ｗ／ｃｍ２,光谱分辨率为２％,测量速度为１０条谱线／ｓ。经实际检测和使用,该设备的性能达到国内外先进水平,并具有野外工作的特点。