A fast and effective model for wavelet subband histograms and its application in texture image retrieval.

This paper presents a novel, effective, and efficient characterization of wavelet subbands by bit-plane extractions. Each bit plane is associated with a probability that represents the frequency of 1-bit occurrence, and the concatenation of all the bit-plane probabilities forms our new image signature. Such a signature can be extracted directly from the code-block code-stream, rather than from the de-quantized wavelet coefficients, making our method particularly adaptable for image retrieval in the compression domain such as JPEG2000 format images. Our signatures have smaller storage requirement and lower computational complexity, and yet, experimental results on texture image retrieval show that our proposed signatures are much more cost effective to current state-of-the-art methods including the generalized Gaussian density signatures and histogram signatures.     

Domains of attraction of Shalvi-Weinstein receivers

Domains of attraction (DoA) of Shalvi-Weinstein (1990) receivers are analyzed. It is shown that there is a one-to-one correspondence between DoA in the receiver parameter space and those in the global (or combined channel-receiver) parameter space. For general noiseless channels, DoA of SW receivers in the global response space are the minimum distance decision regions on a unit sphere. In the presence of noise and for the class of orthogonal channels, DoA of SW receivers for independent and identically distributed (i.i.d.) input signals are the minimum distance decision regions on an ellipsoid determined by the channel coefficients and the noise variance. The DoA in the receiver parameter space are also characterized for the general nonuniformly distributed sources. The size of the DoA is shown to be affected by the signal power, the signal constellation, the noise level, and the channel condition. It is also demonstrated that although the optima of the Shalvi-Weinstein algorithm and those of the constant modulus algorithm are one-to-one correspondent, their DoA are different in general     

航天发射场推进剂环境污染治理技术研究

环境保护和污染控制是建设生态型发射场的重要组成部分.分析了中国航天发射场的环境污染,针对推进剂四氧化二氮泄漏提出了采用钙基高活性粉剂处理技术,介绍了研制的系列处理装置,提出了臭氧-紫外光-活性炭联合工艺处理推进剂废水和高温燃烧处理推进剂废气废液技术,研制了移动式处理装置,解决了常规液体推进剂的发射环境污染难题,为航天发...     

基于Stackelberg博弈的动态频谱接入控制

为了解决多主用户和多次级用户共存网络的频谱资源分配问题,提出了一种基于斯塔科尔伯格（Stackelberg）博弈的动态频谱接入控制算法。该算法通过三阶段Stackelberg博弈模拟主用户频谱竞价,博弈过程中次级用户以最大化传输速率为目的接入主用户频谱,同时设计了一种迭代过程来求解纳什均衡。实验计算与结果分析证明了纳什均衡唯一存在性的充要条件,并说明了迭代过程的收敛性以及主用户最佳效用的影响因素。     

Board level solder joint reliability analysis and optimization of pyramidal stacked die BGA packages

Due to requirements of cost-saving and miniaturization, stacked die BGA has recently gained popularity in many applications. However, its board level solder joint reliability during the thermal cycling test is not as well-studied as common single die BGA. In this paper, solder joint fatigue of wirebond stacked die BGA is analyzed in detail. 3D fatigue model is established for stacked die BGA with considerations of detailed pad design, realistic shape of solder ball, and non-linear material properties. The fatigue model applied is based on a modified Darveaux's approach with non-linear viscoplastic analysis of solder joints. The critical solder ball is observed located between the top and bottom dice corner, and failure interface is along the top solder/pad interface. The modeling predicted fatigue life is first correlated to the thermal cycling test results using modified correlation constants, curve-fitted from in-house TFBGA (thin-profile fine-pitch BGA) thermal cycling test data. Subsequently, design analyses are performed to study the effects of 16 key design variations in package dimensions, material properties, and thermal cycling test conditions. In general, smaller top and bottom dice sizes, thicker top or bottom die, thinner PCB, thicker substrate, higher solder ball standoff, larger solder mask opening size, smaller maximum ball diameter, smaller PCB pad size, smaller thermal cycling temperature range, longer ramp time, and shorter dwell time contribute to longer fatigue life. The effect of number of layers of stacked-die is also investigated. Finally, design optimization is performed based on selected critical design variables.     

Multiwavelength fibre laser with wavelength selectable from 1590 to 1645 nm

A multiwavelength fibre laser with a semiconductor optical amplifier is reported. The lasing wavelength of the laser can be adjusted from 1590 to 1645 nm by adjusting the round-trip cavity loss. Simultaneous lasing of over 40 wavelengths with signal-to-noise ratio of over 40 dB was achieved from 1612 to 1645 nm.     

PHS网络优化与信令分析

网络优化是无线市话(PHS)网络系统实际运营过程中的重要环节.本文简单介绍了PHS网络优化的基本思想,通话测试中的信令分析.最后对测试中遇到的常见问题进行讨论,并提出解决方案.     

基于大数据的全媒体平台发展战略研究

互联网带来了第四次传播革命,使得信息更为公开和透明,信息的数量也呈指数级快速增加。2013年,人类开始进入"大数据元年"、"移动互联元年"。在移动互联和云计算的双重推动下,大数据开始进入爆发增长期。在这种巨变的时代大背景下,传统媒体的转型发展,既是技术问题,也是战略问题,必将对未来的媒体形态和格局产生深远影响。如何才能有效利用大数据技术实现传统媒体质的飞跃,进入全媒体阶段,探讨了大数据时代下全媒体平台发展的主要战略。     

GaAs MESFET栅取向效应中背栅的作用

根据压电效应模型,本文详细研究了压电电荷对GaAs MESFET沟道与衬底界面耗尽层的影响。认为正压电电荷比负压电电荷所引起的阀值电压漂移大,较好解释了(100)衬底上沿[011]和[011]取向的GaAs MESFET阈值电压非对称反向漂移的现象。     

光纤电视系统

随着我国经济的发展,光纤(有线)电视系统也将在全国有一个大发展。本文将目前光纤电视技术的发展情况用深入浅出的文字作一综合叙述,其中包括光纤电视和目前无线电广播电视在质量上的比较、光纤电视系统及其布线结构。对光纤电视系统的两项重要技术:调制及多路复用,作了进一步探讨,提出了有关光纤电视系统将来在技术方面的可能发展。最后作者对我国发展光纤电视系统提出了一些看法。