Self-similarity of parallel machines

Self-similarity is a property of physical systems that describes how to scale parameters such that dissimilar systems appear to be similar. Computer systems are self-similar if certain ratios of computational forces, also known as computational intensities, are equal. Two machines with different computational power, different network bandwidth and different inter-processor latency behave the same way if they have the same ratios of forces. For the parallel conjugate gradient algorithm studied in this paper, two machines are self-similar if and only if the ratio of one force describing latency effects to another force describing bandwidth effects is the same for both machines. For the two machines studied in this paper, this ratio, which we call the mixing coefficient, is invariant as problem size and processor count change. The two machines have the same mixing coefficient and belong to the same equivalence class.     

On the efficiency of bootstrap method into the analysis contingency table

The bootstrap method is a computer intensive statistical method that is widely used in performing nonparametric inference. Categorical data analysis, in particular the analysis of contingency tables, is commonly used in applied field. This work considers nonparametric bootstrap tests for the analysis of contingency tables. There are only a few research papers which exploit this field. The p-values of tests in contingency tables are discrete and should be uniformly distributed under the null hypothesis. The results of this article show that corresponding bootstrap versions work better than the standard tests. Properties of the proposed tests are illustrated and discussed using Monte Carlo simulations. This article concludes with an analytical example that examines the performance of the proposed tests and the confidence interval of the association coefficient.     

一种6.9 ppm/℃92 dB PSRR基准电压源的设计

提出了一种利用简单结构实现高阶指数曲率补偿和高电源电压抑制比的带隙基准电压源。利用正温度系数的反向饱和电流IS和双极型晶体管正向导通时的电流增益β以及Trimming修条电阻实现温度补偿,同时采用Wilson电流镜和电压负反馈技术来提高PSRR。仿真结果表明,该基准电压源达到了6.9 ppm/℃的温度系数,低频时PSRR最高达92 dB和39.3 ppm/V的线性调整率。     

复杂背景下的多阈值人眼定位新算法*

提出了一种基于复杂背景下的多阈值人眼定位算法。该算法首先对图像进行光线补偿,减小由于光照不均等因素造成的影响;然后根据对人眼灰度特征的分析来确定3个人眼二值化阈值,从而分离出人眼候选区域;最后根据人脸的几何特征、人眼位置判定准则以及计算二维相关系数来排除非人眼区域,从而定位双眼。实验结果表明,该算法能在不同条件下准确定位人眼,且具有较快的定位速度和较高的检测率。     

非均匀分布颗粒群中的曳力分布

本文采用格子Boltzmann方法(LBM)在图形处理器(GPU)上计算了由静止圆柱阵列组成的团聚物周期单元内的不可压缩流体流动,流固交界面处采用直接反弹以实现无滑移边界,每个圆柱上的曳力通过统计动量交换直接求得。根据LBM求得的流体速度,对于团聚物中的单圆柱按能量最小多尺度(EMMS)模型计算平均曳力系数,并考察了将聚团近似为均匀悬浮的临界条件。对颗粒雷诺数Re_p在0～10之间的80种固相份额的模拟结果表明,密相空隙率可以表征这种临界条件。当固相份额恒定时,该临界空隙率随着Re_p的增加而降低;当Re_p恒定时,该临界空隙率随着固相份额的增加而降低。     

超声波在电梯平衡系数测量中的应用

针对传统的电梯平衡系数测试中,人工检测平衡状态所带来的误差大、效率低、成本高等问题,设计了一种基于超声波的电梯平衡状态自动检测系统,该系统运行后无需人工干涉,在电梯运行过程中自动检测平衡状态,并通过无线传输检测结果,准确、稳定、高效、安全。该系统摒除了人为因素对获取平衡状态的影响,使检验手段更加科学合理。     

多氯联苯（PCBS）分配系数的估算和预测

基于烷烃分子距边矢量,将以原子为基准的距离－边数 量扩展为以基团为基准的距离－边数矢量。研究发现新分子距边矢量与多氯联苯正辛醇／水分配系数的对数有很好的线性关系：ｌｏｇＫｏｗ＝４．１０８８４＋０．５２４２３７ｕ１－０．０９２９０６２ｕ２ｎ＝３７,ｒ＝０．０９９０８,Ｓ＝０．１７７５,ＥＶ＝０．９８１１,Ｆ＝１８６８。     

机构影响系数统一计算模型

基于机构矩阵型式运动学方程和速度加速度统一模型,讨论了机构运动影响系数通用 计算公式的结构和自动构造算法,得出的一组运动影响系数统一计算公式具有普遍的意义, 并可以方便地由计算机程序自动构造并求解．本文内容建立了机构速度及加速度分析和动力 学自动分析的基础,为通用计算机辅助分析系统的研制创造了先决条件．     

基于HVS彩色图像的扩展零树小波编码方法的研究

提出了一种基于视觉系统（HVS）特性和小波系数的扩展零树的彩色图像压缩编码方法。该算法按视觉重要性排序,产生一种嵌入式比特流。它不仅保留了EZW算法的高效、嵌入式编码的优点,而且获得了在低比特率下的彩色图像经压缩后的优良的复原图像效果。本算法同其他算法相比,在相同的压缩比条件下,恢复图像具有更好的视觉质量。     

Estimation of the Bivariate Stable Spectral Representation by theProjection Method

A method of estimating the spectral representation of a generalized bivariatestable distribution is presented, based on a series of maximum likelihood (ML)estimates of the stable parameters of univariate projections of the data. Thecorresponding stable spectral density is obtained by solving a quadraticprogram. The proposed method avoids the often arduous task of computing themultivariate stable density, relying instead on the standard univariate stabledensity. The paper applies this projection procedure, under the simplifyingassumption of symmetry, to simulated data as well as to foreign exchangereturn data, with favorable results. Kanter projection coefficients governingconditional expectations are computed from the estimated spectral density. For the simulated data these compare well to their known true values.