基于 CBR SWC模型的 VOC框架模板生成技术研究

虚拟原型逼真设计作为虚拟产品开发研究的一个方面，是近几年发展起来的新技术，主要研究虚拟环境下的产品建模问题以及基于仿真的集成产品和过程设计问题。智能支持的计算机辅助VOC荻取与分析综合工具是虚拟原型逼真设计模型实现的重要模块之一，这里研究了顾客需求(VOC)荻取和综合分析工具实现的关键技术，着重论述了基于事例推理的加权相似性计算(CBR-WSC)模型的VOC框架自动生成技术，给出了模型的结构、算法步骤，结合仪表产品应用实例验证了模型的有效性。     

A note on the attractor-property of infinite-state Markov chains

In the past 5 years, a series of verification algorithms has been proposed for infinite Markov chains that have a finite attractor, i.e., a set that will be visited infinitely often almost surely starting from any state. In this paper, we establish a sufficient criterion for the existence of an attractor. We show that if the states of a Markov chain can be given levels (positive integers) such that the expected next level for states at some level n>0 is less than n−Δ for some positive Δ, then the states at level 0 constitute an attractor for the chain. As an application, we obtain a direct proof that some probabilistic channel systems combining message losses with duplication and insertion errors have a finite attractor.     

前言

人们对后3G的要求是:在全球范围内实现无缝覆盖,进行包括语音、文本、图像、视频等在内的高速多媒体通信。为此,在有限频谱资源条件下,必须缩短无线信号的传输半径,极大限度地复用频谱资源,提高单位空间的信道容量。采用各种先进的无线传输技术的无线传输网络则在中、小范围内提供高速率、高质量的无线移动通信服务。因而WLAN和WPAN的需求和应用在不断增长,超宽带(UWB,ultra wide-band)等短距离、高空间容量的技术日益兴起,成为目前无线通信领域的热点。UWB的核心是冲激无线电技术,即利用持续时间非常短(纳秒、亚纳秒级)的脉冲波形来…     

Termination detection for distributed computations

A simple derivation of a general solution to the problem of detecting the termination of a distributed computation is presented.     

更实际的并行算法的设计

大规模并行计算机的出现和发展迫切要求有新的并行处设计理论和技术来指导更实际的并行算法的设计。本文首先简单介绍了针对ＭＰＣ提出孤ＬｏｇＰ和Ｂａｒｒｉｅｒ－ＬｏｇＰ并行计算模型，然后借助于Ｂａｒｒｉｅｒ－ＬｏｇＰ模型从通信平衡、数据分配和重叠通信与计算这三个方面讨论了更实际的并行算法设计的一般方法和技巧。     

Halo World: Tools for Parallel Cluster Finding in Astrophysical N-body Simulations

Cosmological N-body simulations on parallel computers produce large datasets--gigabytes at each instant of simulated cosmological time, and hundreds of gigabytes over the course of a simulation. These large datasets require further analysis before they can be compared to astronomical observations. The “Halo World” tools include two methods for performing halo finding: identifying all of the gravitationally stable clusters in a point-sampled density field. One of these methods is a parallel implementation of the friends of friends (FOF) algorithm, widely used in the field of N-body cosmology. The new IsoDen method based on isodensity surfaces has been developed to overcome some of the shortcomings of FOF. Parallel processing is the only viable way of obtaining the necessary performance and storage capacity to carry out these analysis tasks. Ultimately, we must also plan to use disk storage as the only economically viable alternative for storing and manipulating such large data sets. Both IsoDen and friends of friends have been implemented on a variety of computer systems, with parallelism up to 512 processors, and successfully used to extract halos from simulations with up to 16.8 million particles.     

水工设计中的几个水力学问题

从工程实际出发，对多层泄水道平均能头，无压隧洞泄流量，隧洞出口水头损失及截流龙口水深等水力学问题的估算方法作了初探。     

DISCRIMINATION BETWEEN BEERS WITH SMALL COLOUR DIFFERENCES USING THE CIELAB COLOUR SPACE

Commercial beers which recorded the same colours by either the European Brewery Convention (EBC) Recommended Method or by visual comparison against standard colour discs in a Lovibond Comparator, exhibited qualitative differences in their visible spectra. These differences, in turn, translated into measurable differences in colour, expressed as ΔE_a,b, when described by the CIELAB colour system. Visual difference tests revealed that, in some cases, beers with the same EBC colour could be discriminated by observers under ideal viewing conditions. A threshold value for ΔE_a,b, (which varied with EBC colour), below which no significant difference in beer colour could be detected by visual comparison, was determined by consideration of the corresponding ΔE_a,b, values for these beers. This threshold was used to assess the accuracy of a rapid method for colour analysis which uses transmittance values at five selected wavelengths. This new method was shown to give ΔE_a,b values, with respect to a reference method, which were within the limit of visually detectable colour differences. This, therefore, provides a valuable yardstick for assessing the worth of new tristimulus-based colour measurement techniques and instrumentation.     

区域分解地震波场数值模拟算法

区域分解法是一种计算偏微分方程数值解的新方法。该法把研究区域分解为形态规则的小区域，在各子区域内采用最有效的计算方法求解，能充分发挥各种数值模拟方法的优点，提高求解正演问题有效性。     

tanh变换在电磁散射中的应用

在劈的电磁射研究中，复宗量Ｆｒｅｓｎｅｌ函数和Ｍａｉｌｕｚｈｉｎｅｔｓ函数的数值计算是一个既极其重又相当困难的问题，本文运用ｔａｎｈ变换，圆满地解决了这两个特殊函数在整个复平面内的计算机数值计算问题，通过计算机计算与两组精确值的比较，本文所给出了的方法计算精度高，并且计算速度快。