产品数据管理（PDM）在制造业中的应用与发展

在计算机技术快速发展的今天，许多企业的软件使用者和领导者开始体会到新技术带来的效益和进一步发展的必要性，认为到企业信息化的基础是产品数据管理（PDM）从PDM的产生、特点、结构、应用和发展等方面，详细地介绍了PDM的功能及其地位，以及在实施中要注意的事项。     

关于Diophantine方程xp+2p=Dy2

设p是奇素数,D是无平方因子正整数。文章证明了:当p>3时,如果D不能被p或2kp+1形之素数整除,则方程xp+2p=Dy2没有适合gcd(x,y)=1的正整数解。     

The detection of structural deformation errors in attitude determination

In the determination of the attitude parameters from a multi-antenna GPS array, one of the major assumptions is that the body frame is rigid at all times. If this assumption is not true then the derived attitude parameters will be in error. It is well known that in airborne platforms the wings often experience some displacement during flight, especially during periods of initializing maneouvres, such as taking off, landing,and banking. Often it is at these points in time that it is most critical to have the most precise attitude parameters.There are a number of techniques available for the detection of modeling errors.The CUSUM algorithm has successfully been implemented in the past to detect small persistent changes. In this paper the authors investigate different methods of generating the residuals, to be tested by the CUSUM algorithm, in an effort to determine which technique is best suited for the detection of structural deformation of an airborne platform. The methods investigated include monitoring the mean of the residuals generated from the difference between the known body frame coordinates, and those calculated from the derived attitude parameters. The generated residuals are then passed to a CUSUM algorithm to detect any small persistent changes. An alternative method involves transforming the generated residuals into the frequency domain through the use of the Fast Fourier Transform. The CUSUM algorithm is then used to detect any frequency changes. The final technique investigated involves transforming the generated residuals using the Haar wavelet. The wavelet coefficients are then monitored by the CUSUM algorithm in order to detect any significant change to the rigidity of the body frame.Detecting structural deformation, and quantifying the degree of deformation, during flight will ensure that these effects can be removed from the system, thus ensuring the most precise and reliable attitude parameter solutions. This paper, through a series ofsimulations, will assess the effectiveness of the above mentioned techniques for detecting structural deformation effects on a GPS multi-antenna array. These principles are then tested with experimental data.     

Structure of the detoxification catalyst mercuric ion reductase from Bacillus sp. strain RC607

Several hundred million tons of toxic mercurials are dispersed in the biosphere. Microbes can detoxify organo-mercurials and mercury salts through sequential action of two enzymes, organomercury lyase and mercuric ion reductase (MerA). The latter, a homodimer with homology to the FAD-dependent disulphide oxidoreductases, catalyses the reaction NADPH + Hg(II)----NADP+ + H+ + Hg(0), one of the very rare enzymic reactions with metal substrates. Human glutathione reductase serves as a reference molecule for FAD-dependent disulphide reductases and between its primary structure and that of MerA from Tn501 (Pseudomonas), Tn21 (Shigella), p1258 (Staphylococcus) and Bacillus, 25-30% of the residues have been conserved. All MerAs have a C-terminal extension about 15 residues long but have very varied N termini. Although the enzyme from Streptomyces lividans has no addition, from Pseudomonas aeruginosa Tn501 and Bacillus sp. strain RC607 it has one and two copies respectively of a domain of 80-85 residues, highly homologous to MerP, the periplasmic component of proteins encoded by the mer operon. These domains can be proteolytically cleaved off without changing the catalytic efficiency. We report here the crystal structure of MerA from the Gram-positive bacterium Bacillus sp. strain RC607. Analysis of its complexes with nicotinamide dinucleotide substrates and the inhibitor Cd(II) reveals how limited structural changes enable an enzyme to accept as substrate what used to be a dangerous inhibitor. Knowledge of the mode of mercury ligation is a prerequisite for understanding this unique detoxification mechanism.     

方程(axm+1)/(ax+1)=yn的正整数解

设a,m是大于1的正整数,证明:当m>2,方程(axm 1)/(ax 1)=yn仅有有限多组解(x,y,n)适合min(x,y,n)>1,而且这些解都满足yn相似文献   

大型工程项目的新型合同结构模式

就大型工程项目的新型合同结构模式的内涵、特点及其实施进行研究,重点从合同结构模式对项目投资控制、进度控制、质量控制以及组织协调方面的影响说明其重要性,以期应用现代项目管理的新理论对不同合同结构模式的优缺点进行比较,提出符合当前我国大型工程项目特点的合同结构模式,并对其具体实施提出建议.     

一个素数猜想的反例

对于正整数n,设pn是第n个素数。本文证明了:不等式穴n 1雪pn-npn 1<12穴n 1雪950对于某些正整数n不成立。     

关于Diophantine方程x^p-2^mp=pDy^2

设p是奇素数,m是正整数.D是无平方因子正整数.本文证明了当p＞3,m＞1,D不能被p或2kp+1之形素数整除时,方程xp-2mp=pDy2没有适合gcd(x,y)=1的正整数解(x,y).     

单片机程序的限时服务策略及设计

针对单片机软件中由于任务超时导致的运行紊乱情况,提出了一种借助硬件的定时中断机制,只需只量资源就可实现的限时服务处理方法,并针对顺序操作和任务操作两种情况进行详细说明。能够防止和解决程序中出现因条件不满足而无法退出功能模块,出现独占MCU时间,以及多任务机制下的任务重叠,使资源间相互干扰而出现死循环状态或运行状态错误等问题,从而提高系统的冗余度和可靠性。     

信息化带动工业化的有效途径

大力推进信息化,以信息化带动工业化,是湖南完成工业化任务,发挥后发优势,实现生产力跨越式发展的新机遇.因此,深入研究和积极探索以信息化带动工业化的有效途径和方式,是摆在我们面前的一项重要任务.