Adaptive decorrelating detectors for CDMA systems

Multi-user detection allows for the efficient use of bandwidth in Code-Division Multiple-Access (CDMA) channels through mitigation of near-far effects and multiple-access noise limitations. Due to its inherent noise and multipath immunity, CDMA multi-access is being considered as a platform for personal communication systems (PCS). As CDMA based digital communication networks proliferate, the need to determine the presence of a new user and integrate knowledge of this new user into the detection scheme becomes more important. The decorrelating detector is a linear multi-user detector that is asymptotically optimal in terms of near far resistance; however, in the presence of a new unknown user, performance of the decorrelator is severely degraded. Adaptive decorrelators are constructed which adaptively augment an existing conventional decorrelator to demodulate a new active user in addition to existing users. Several likelihood ratio based schemes are employed. Both synchronous and asynchronous communication are investigated.This research was supported by the U.S. Army Research Office under Grant DAAH04-93-G-0219.     

在光阻材料中过滤器吸附机制的作用(英文)

近来尼龙过滤被广泛用于光刻工艺流程来改善良率,因为许多IC和光阻制造商有实验性证据表明尼龙滤膜能吸附杂质。然而,尼龙滤膜降低缺陷的机制尚不清楚。通过致力于特定的光阻成分来研究不同的缺陷发生机制是十分有用的。利用表面改性和不同的光阻成分进行了各种吸附试验来测量尼龙滤膜的耐受性,包括表面张力,光酸发生剂和光酸抑制剂。最后,研究希望通过致力于如何最佳贯彻尼龙过滤策略来确定最有效的方法提高良率。     

Oxidation-sulfidation behavior of Ni aluminide in oxygen-sulfur mixed-gas atmospheres

Oxidation-sulfidation studies were conducted on sheet samples of nickel aluminide, containing 23.5 at. % Al, 0.5 at. % Hf, and 0.2 at. % B in an annealed condition and after preoxidation treatments. Continuous weight-change measurements were made by a thermogravimetric technique in exposure atmospheres of air, a low- gas mixture, and low- gas mixtures with several levels of sulfur. Detailed scanning electron microscopy (SEM), X-ray, and electron microprobe analyses of the corrosion product scale layers were performed. The air-exposed specimens developed predominantly nickel oxide; the specimen exposed to a low- .     

Impact of power electronics packaging on the reliability of grid connected photovoltaic converters for outdoor applications

This paper deals with thermal and reliability aspects of converters for grid connected photovoltaic applications (rate power approximately 100 W) which can be integrated into solar modules. The use of these Module Integrated Converters (MIC) promises a reduction of costs due to mass production. It improves behaviour of the whole photovoltaic system, as there is no voltage mismatch caused by shading effects. The electronic components of the MIC are exposed to extreme environmental conditions. Lifetime limiting factors are described. Methods to increase the lifetime of the most crucial components in the MIC, electrolytic capacitors, are described. The presented 1st generation Low Profile MIC with “optimised design” is capable of running in very high ambient temperatures. This design maximises availability of the photovoltaic system, which consequently leads to a cost reduction of the electrical energy delivered to the grid. Different realisations of how to integrate the designed Low Profile MIC into the solar module are discussed. A detailed thermal simulation is used to optimise the MIC design according to temperature and reliability issues. The models used for thermal simulation are described.     

一种基于显著不相关检验的快速分形图像编码方法

针对分形编码计算量过大的缺点,本文提出一种基于显著不相关检验的分形编码方法。对于文中的测试图像（Lenn256×256×8ppb和Boat256×256×8ppb）,其编码速度比基于子块分类的分形编码方法快2～15倍,而解码图像质量（PSNR）没有明显下降,压缩比还有一定的提高。     

The Effect of He Implantation on the Tensile Properties and Microstructure of Cu/Fe Nano‐Bicrystals

In situ uniaxial tensile experiments on as‐fabricated and helium‐implanted 100 nm‐diameter Cu/Fe bicrystals unearth the effect of individual face‐centred‐cubic/body‐centred‐cubic (fcc‐bcc) interfaces on improving radiation‐damage tolerance and helium absorption. Arrays of nanotensile specimens, each containing a single Cu grain in the bottom half and a single Fe grain on top, were fabricated by templated electron‐beam lithography and electrodeposition. Helium is implanted at 200 keV to a dose of 10¹⁴ ion/cm² nominally into the interface region. High‐resolution, site‐specific transmission electron microscopy (TEM) and through‐focus analysis reveal that the interfaces are nonplanar and contain ≈5 nm‐spaced He bubbles with diameters of 1–2 nm. Nanomechanical experimental results show that the irradiated samples exhibit yield and ultimate tensile strengths more than 60% higher than the as‐fabricated ones, while they retain comparable ductility. Tensile failure always occurs gradually, along the interfaces, with no noticeable shape localization. The absence of brittle failure in He‐irradiated metals might be explained, in part, by the inability of the small He bubbles to serve as sufficient stress concentrators for cracking. In addition, the non‐orthogonal orientation of the interfaces with respect to the loading axes results in the development of both normal‐ and shear‐stress components. Tensile loading along the pillar axes may cause those interfacial regions subjected to normal stresses to detach, while the inclined regions, subjected to shear, to carry plastic deformation until final fracture.     

弱激光辐照油松种子生物效应与生物细胞膜的渗透性

从植物生理学观点出发,用物理学方法讨论了He－Ne激光对生物细胞膜的渗透性影响。结果表明用He－Ne激光场辐照油松种子,有利于其细胞膜渗透能力的提高,并可产生有益的生物效应。     

基于辐射中心分解的天线辐射场合成

采用逆投影算法对观测天线不同方向辐射场的仿真数据进行成像处理,获取其辐射强度的分布图像,并引入偶极子辐射中心的概念,采用参数估计法对天线辐射场进行分解并合成,合成结果与直接计算的不同距离的天线辐射场分布数据吻合较好,有效地解决了近场散射建模中天线辐射场的描述问题。同时,该方法也可应用于双站RCS数据压缩、天线反设计及雷达仿真应用等方面。     

基于对数正态分布参数判别加速实验中失效机理一致性

The failure mechanism stimulated by accelerated stress in the degradation may be different from that under normal conditions, which would lead to invalid accelerated life tests. To solve the problem, we study the re- lation between the Arrhenius equation and the lognormal distribution in the degradation process. Two relationships of the lognormal distribution parameters must be satisfied in the conclusion of the unaltered failure mechanism, the first is that the logarithmic standard deviations must be equivalent at different temperature levels, and the second is that the ratio of the differences between logarithmic means must be equal to the ratio of the differences between reciprocals of temperature. The logarithm of distribution lines must simultaneously have the same slope and regular interval lines. We studied the degradation of thick-film resistors in MCM by accelerated stress at four temperature levels （390, 400, 410 and 420 K）, and the result agreed well with our method.     

CTA8280集成电路测试系统的研究应用

集成电路测试系统对测试精度、测试速度、测试功能等方面提出了越来越高的要求,测试系统并行测试和乒乓测试结合可以更好地利用现有的硬件资源,最大限度地提高系统的测试效率,降低测试成本。针对CTA8280测试系统结构、关键技术、应用案例进行分析介绍。