An Approach for Establishing Enterprise Data Standards

Avoid the common pitfalls experienced by many organizations that have established enterprise data standards by following a straightforward process. Standards should be defined around a simple framework and be borrowed from third parties or vendors wherever possible to save time. It is better to reuse, rather than reinvent or create standards. To be used successfully, standards must be easy to understand, have a proven track record, be easy to use, and be readily available. Standards should be maintained in a central repository such as Lotus Notes or on an intranet Web site so that they are readily accessible to project teams.     

基于自由度分析的几何约束凝聚计算方法的改进

采用基于自由度分析的方法,对几何约束问题进行求解,就是用一定的模式在图形的GCG图中,进行不断匹配、求解的过程。对最常用到的几种模式的凝聚计算方法进行了改进,特别是提出可以对非构造性凝聚模式添加部分约束,这些约束的值将作为迭代变量,对约束耦合问题进行约束凝聚,凝聚过程结束后,没有用到的约束作为迭代的目标函数,进行迭代计算,大大减少了解决复杂约束耦合问题所需要的变量数,提高了计算过程的稳定性和计算速度。     

基于主题的数据订阅分发技术

基于主题的订阅分发技术是一种将源数据通过一定的方式发布到目的地的技术，它既可以发布数据库的实时数据，也可以发布实时应用数据。该技术可用于实时数据库备份、信息备份，也可用于数据仓库和数据分布的其他场合。     

DS-TE网络中改进的LSP抢占算法

Min_BW算法在优化被抢占移动交换路径(LSP)的优先级时,存在被抢占LSP个数多和优先级高的问题.为此,提出DS-TE网络中改进的LSP抢占算法(I_Min_BW),全面考虑可能被抢占的LSP组中LSP的个数、LSP的最高优先级以及LSP的优先级总和.实验结果表明,该算法抢占的LSP组中最高优先级小于等于Min_B...     

Bresenham画圆法提取图像信息

在图像处理中, 若操作图像某区域中的像素, 必须先提取这些待处理的像素。待处理的像素区域可以是规则的, 也可能是不规则的。对于规则区域, 可采用经典的图形学算法完成选取; 对于不规则区域, 可通过适当方法将其转换为规则区域来完成选取。讨论了24位真彩色图像文件的结构、位图数据阵列中的像素与其在屏幕上显示的像素间的关系; 采用Bresenham画圆法提取图像圆形区域中的像素并将其可视化等问题。     

Determining operations affected by delay in predictive train timetables

Constructing train schedules is vital in railways. This complex and time consuming task is however made more difficult by additional requirements to make train schedules robust to delays and other disruptions. For a timetable to be regarded as robust, it should be insensitive to delays of a specified level and its performance with respect to a given metric, should be within given tolerances. In other words the effect of delays should be identifiable and should be shown to be minimal. To this end, a sensitivity analysis is proposed that identifies affected operations. More specifically a sensitivity analysis for determining what operation delays cause each operation to be affected is proposed. The information provided by this analysis gives another measure of timetable robustness and also provides control information that can be used when delays occur in practice. Several algorithms are proposed to identify this information and they utilise a disjunctive graph model of train operations. Upon completion the sets of affected operations can also be used to define the impact of all delays without further disjunctive graph evaluations.     

ARP欺骗的自动探测、定位和隔离

ARP欺骗可以分为假冒网关和假冒计算机两种.本文实现了一种对抗ARP欺骗的架构,通过分析网关的Syslog事件,能够发现第一种ARP欺骗;通过分析路由器的ARP表,能够发现第二种ARP欺骗.在确定攻击者的MAC地址后,定位其接入交换机端口,然后关闭端口就能够隔离ARP攻击.并借助于数据库技术和SNMP协议,自动完成这些过程.     

Measuring Syntactic Variation in Dutch Dialects

This research applies dialectometric methods to purely syntacticdialect data. It will be shown that there is geographic cohesionin syntactic variation when viewed in the aggregate. The amountof syntactic variation which can be accounted for by geographywill be determined. Dialectometric techniques will be used todevelop an additive measure of syntactic differences. Multidimensionalscaling will be applied to visualise the geographic distributionof the Dutch dialects with respect to syntactic variation inthe aggregate. The Dutch dialect map based on a syntactic measurewill be compared with a dialect map based on subjective judgementsand a dialect map based on pronunciation differences to putthe syntactic measurement results into perspective. An alternativeway to measure syntactic distance will be presented and willprovide indications for future research to more accurately quantifysyntactic variation.     

非瑞利杂波中广义符号检测器的渐近性能

利用韦伯分布和对数正态分布两种非瑞利杂波模型,推导广义符号(GS)检测器相对于最佳线性参量检测器的渐近相对效率(ARE)计算公式.采用Monte Carlo法仿真广义符号(GS)检测器在非瑞利分布杂波背景下相对于最优线性检测器的渐近相对效率.雷达目标信号假定为非起伏,杂波的幅度包络满足韦伯分布和对数正态分布.渐进相对效率(asymptoticrelative efficiency,ARE)的仿真结果表明了广义符号检测器的有效性随着杂波分布偏离瑞利分布程度、采样参考单元的增加而增加.     

遗传算法在数量型关联规则提取中的应用

关系数据库中数量属性的关联规则挖掘问题是关联规则挖掘中经常要遇到的问题。该文利用遗传算法解决FCM模糊聚类问题主要是为了避免FCM算法的局部极小问题。利用聚类的结果可以使数量型属性关联规则转换成类别型属性,类别型属性再转化为布尔型属性,这样,即可以使用许多已有关联规则挖掘方法挖掘出有意义的规则。     

Maximum likelihood neural approximation in presence of additivecolored noise

In many practical situations, the noise samples may be correlated. In this case, the estimation of noise parameters can be used to improve the approximation. Estimation of the noise structure can also be used to find a stopping criterion in constructive neural networks. To avoid overfitting, a network construction procedure must be stopped when residual can be considered as noise. The knowledge on the noise may be used for "whitening" the residual so that a correlation hypothesis test determines if the network growing must be continued or not. In this paper, supposing a Gaussian noise model, we study the problem of multi-output nonlinear regression using MLP when the noise in each output is a correlated autoregressive time series and is spatially correlated with other output noises. We show that the noise parameters can be determined simultaneously with the network weights and used to construct an estimator with a smaller variance, and so to improve the network generalization performance. Moreover, if a constructive procedure is used to build the network, the estimated parameters may be used to stop the procedure.     

Implications of We-Awareness to the Design of Distributed Groupware Tools

We-awareness is the socially recursive inferences that let collaborators know that all are mutually aware of each other’s awareness. While we-awareness is easy afforded in face to face collocated collaboration, it is much more difficult to design distributed groupware tools to provide equivalent capabilities: there can be no awareness unless it is programmed in via system features. We identify a series of questions that must be considered if we-awareness is to be supported. What types of awareness information is crucial and should thus be added to the ‘blank slate’ of a screen sharing system? How can that awareness information be captured through technology, and what information will be lost during this capture process? How should that information be translated, transformed and encoded into a digital form, and—as part of that—what information will be altered as part of that translation process? How will that information be transmitted, and what are the network effects in terms of that information being received in a timely manner? How will that information be represented to other participants in order to enable the rich and subtle interactions that occur in the face-to-face setting? We illustrate the nuances of these questions and why they are difficult to answer by revisiting several prior technical solutions to we-awareness.     

CAI: Program and programming techniques that utilize the microcomputer as an interactive audio-visual device

Choosing the concepts that are to be taught by this computer assisted technique is not difficult to do. Look for topics, concepts, problems that are time consuming to teach. The production of complex and elaborate diagrams that would normally be drawn on the blackboard, can be done on the computer before the lesson. Concepts that have to be covered many times during a semester are candidates for such a process. Through this process, and as the years pass, more and more programs can be added to the instructional library.Even though some programs will have to be modified and others will be rejected as unsatisfactory, the computer will have become an integral and indispensable part of the instructor's lesson plan. This must be one of the major goals of this paper. Some of the other goals might be the following: the improvement of the instructional process, the demonstration of the practicality of using computers in the classroom, overcoming the natural reluctance of most teachers for using computers, and proselytizing its use to other instructors, especially in fields other than the sciences.The author encourages those that are interested in acquiring the programs or those who wish to discuss these and other techniques to contact him.     

Using axial dimensions to determine the proportions of line drawings in computer graphics

The axial dimensions in an engineering drawing can be used to determine line length so that the drawing will be to scale unless out of scale dimensions are explicitly used. In addition, over and under dimensioning can be detected. Therefore changes can be made to the dimensions and the drawing will be changed automatically. This technique has been used for local scaling of both in-line and out-of-line subpictures.     

A method for double series summation

The method of summation by diagonals is shown to be a practical method for the summation of double series which can give good results. Where problems arise an elementary analysis can often be used which enables the sum to be calculated to a high degree of accuracy. The method can be extended in an obvious manner to higher dimensional series.     

手机实时操作系统RTXC在Windows环境中的模拟

为支持手机MMI软件开发，通常需要在Windows平台中建立针对手机硬件和下层软件接口的模拟环境，其中手机实时操作系统RTXC的功能也需要在模拟环境中实现。通过用单个Windows线程来模拟运行RTXC内核和它所有的任务，可以继承使用RTXC绝大多数源代码；但技术难点是：需要在Windows环境中重新定义RTXC任务切换的堆栈帧结构，重写任务上下文切换过程．模拟实现外部中断的禁止／使能和外部中断服务程序ISR同RTXC内核的接口。     

Finite element algorithms for contact problems

Summary The numerical treatment of contact problems involves the formulation of the geometry, the statement of interface laws, the variational formulation and the development of algorithms. In this paper we give an overview with regard to the different topics which are involved when contact problems have to be simulated. To be most general we will derive a geometrical model for contact which is valid for large deformations. Furthermore interface laws will be discussed for the normal and tangential stress components in the contact area. Different variational formulations can be applied to treat the variational inequalities due to contact. Several of these different techniques will be presented. Furthermore the discretization of a contact problem in time and space is of great importance and has to be chosen with regard to the nature of the contact problem. Thus the standard discretization schemes will be discussed as well as techiques to search for contact in case of large deformations.     

变频器与PLC连接应注意的问题

作为典型的工控产品,变频器和PLC常配合使用,完成各种控制任务。在应用中,变频器和PLC间的控制信号连接时应注意哪些实际问题？文章分述并总结了三个方面应注意的问题：数字量信号连接应注意的问题;模拟量信号连接应注意的问题;变频器运行时对P L C干扰应注意的问题。     

基于倾斜摄影的三维模型单体化方法研究

利用三角面片的可分割性质,解决倾斜摄影数据的三维模型可分离单体化问题。该方法首先绘制切割多边形,确定单体化模型边界,然后使用包围盒方法进行求交检测,获得需要切割的三角面片。之后计算求交检测所得三角面片与切割多边形的交点,然后详细分析切割多边形与三角面片相交时的不同相交情形,并针对不同的相交情形采用不同的切割方法。最后,对相交区域三角面片进行裁切并重构,再纹理重构并实现多细节分层后得到分离的单体化模型。实验结果表明,该方法可有效实现倾斜摄影三维模型的分离单体化。