IO单元自动排布算法IOAP

提出了一种应用于芯片物理设计过程中IO单元自动排布的新算法。IO单元排布是芯片物理设计过程中长期依赖经验的环节。IO单元排布的优化对布线,电源网格和设计收敛性的优化有很大贡献。文章重点研究边缘IO单元排布,提出了IO单元自动排布算法(IOAP)。此算法及其相关软件直接应用于视频解码芯片和无线传感器网络处理器芯片(已流片成功)的物理设计流程中。结果表明,IOAP有效改善了芯片的电源网格,时序和布线结果,减少了布线努力,提高了设计收敛性。     

ZnO纳米线光学特性测试的倏逝波耦合

使用纳米氧化硅光纤探针,利用倏逝波耦合方法,将紫外到红外的激光成功地耦合进单根ZnO纳米线,耦合效率可达25%.实验观测了单根纳米线的荧光特性,发现ZnO纳米线光传输损耗很低.研究证明:采用透镜聚焦激发纳米线发光的传统耦合方法,只能使用特殊激发波长的光;而倏逝波耦合方法具有高效、适用性强的特点,在半导体纳米线和纳米带的光学特性研究中有广泛的应用前景.     

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。