基于椭圆展开共反射点叠加的隧道地震波超前探测成像方法与应用

采用地震波法探明隧道前方断层、溶洞等不良地质体,是隧道施工安全的重要保障,而有效的成像方法则是关键。椭圆展开是一种新型的偏移成像方法,已在地表地震勘探中得到应用,然而尚未被引入隧道地震探测中。针对隧道环境,基于非标准椭圆方程,构建了隧道空间观测方式椭圆展开方法,同时重新设定隧道轴线方向为椭圆展开法向出射点方向,实现了对隧道掌子面前方区域地质的成像;通过共震源点地震记录的椭圆展开及相干叠加,最终实现掌子面前不良地质的识别和定位,形成了基于椭圆展开共反射点叠加的隧道地震波超前探测成像方法。在此基础上,基于交错网格有限差分方法,对岩性界面和断层进行了系统的正演成像研究,分析了不同地质模型的成像特征;最后,依托现场进行了探测试验,探测结果与开挖揭露情况基本一致,验证了成像方法的有效性和实用性。     

Learning via finitely many queries

This work introduces a new query inference model that can access data and communicate with the teacher by asking finitely many Boolean queries in a language L. In this model the parameters of interest are the number of queries used and the expressive power of L. We study how the learning power varies with these parameters. Results suggest that this model may help studying query inference in a resource bounded environment.AMS subject classification 68Q05, 68Q32, 68T05, 03D10, 03D80     

Graphical Search for Images by <Emphasis Type="Italic">PictureFinder</Emphasis>

The text searching paradigm still prevails even when users are looking for image data for example in the Internet. Searching for images mostly means searching on basis of annotations that have been made manually. When annotations are left empty, which is usually the case, searches on image file names are performed. This may lead to surprising retrieval results. The graphical search paradigm, searching image data by querying graphically, either with an image or with a sketch, currently seems not to be the preferred method partly because of the complexity in designing the query.In this paper we present our PictureFinder system, which currently supports “full image retrieval” in analogy to full text retrieval. PictureFinder allows graphical queries for the image the user has in his mind by sketching colored and/or textured regions or by whole images (query by example). By adjusting the search tolerances for each region and image feature (i.e. hue, saturation, lightness, texture pattern and coverage) the user can tune his query either to find images matching his sketch or images which differing from the specified colors and/or textures to a certain degree. To compare colors we propose a color distance measure that takes into account the fact that different colors spread differently in the color space, and which take into account that the position of a region in an image may be important.Furthermore, we show our query by example approach. Based on the example image chosen by the user, a graphical query is generated automatically and presented to the user. One major advantage of this approach is the possibility to change and adjust a query by example in the same way as a query which was sketched by the user. By deleting unimportant regions and by adjusting the tolerances of the remaining regions the user may focus on image details which are important to him.     

On the distribution of the estimated process yield index Spk

This paper considers an asymptotic distribution for an estimate of the process yield index proposed by Boyles (1994). The asymptotic distribution of is useful in statistical inferences for . An illustrative example is given for hypothesis testing and for interval estimation on the yield index . Copyright © 2002 John Wiley & Sons, Ltd.     

基于MATLAB机械优化设计问题的分析

采用新的软件解决机械优化设计问题,介绍了MATLAB优化工具箱在机械优化设计中的应用。利用MATLAB软件可以求解线性规划、无约束规划、二次规划和有约束非线性规划等优化设计问题。该软件编程工作量小,初始参数输入简单,符合工程设计语言,有着很大的优越性。通过给出的优化实例可以看出,应用该软件求解机械优化设计问题非常方便。     

Similarity is a Geometer

Multimedia databases (in particular image databases) are different from traditional system since they cannot ignore the perceptual substratum on which the data come. There are several consequences of this fact. The most relevant for our purposes is that it is no longer possible to identify a well defined meaning of an image and, therefore, matching based on meaning is impossible. Matching should be replaced by similarity assessment and, in particular, by something close to human preattentive similarity.In this paper we propose a geometric model of similarity measurement that subsumes most of the models proposed for psychological similarity.     

小井眼环空循环压耗预测系统方法

结合小井眼钻进的实际工况建立了适合小井眼的循环压耗计算模型。该模型考虑了钻杆接头、钻柱旋转和钻柱偏心对循环压耗的影响，适用于幂律和HB钻井液流变模式。应用该模型编制的软件对某井进行了循环压耗校核计算，相对误差小于10％，表明该方法具有较高的准确性，能够应用于小井眼水力参数设计、现场分析和指导施工。     

利用UAF42设计带阻滤波器的方法

文章介绍了美国ＢＢ公司的最新器件ＵＡＦ４２的主要特性与性能，利用它给出了设计带阻滤波器的计算公式，步骤及实例。     

学生选课系统的设计与实现

本文以一个具体的应用系统—学生选课信息系统的设计与实现来说明如何利用UML和EJB组件来设计和构建分布式软件系统平台。UML和组件技术结合使用能提高开发效率,增加系统的易维护性。     

浅谈计算机基础课中的PowerPoint教学

分析了计算机基础课传统的讲授Word、Excel、PowerPoint的顺序，提出了首先讲授PowerPoint的可行性和优点，最后具体阐述PowerPoint的教学方法和思路。