水位下降条件下西安D7裂缝土体孔隙变化特征试验

为研究压缩性土体在孔隙水压力下降下所引起的孔隙变化特征,选取孔隙度及分形维数作为评判指标,以西安D7地裂缝两侧可压缩性土层为研究对象,借助三维CT扫描成像技术,依托Matlab计算平台及VG Studio Max图像处理软件,对在水位下降过程中可压缩性土体压缩变形引起的孔隙度和分形维数孔隙变化进行定量评价,并探讨了固结压缩过程中土体孔隙分形维数的变化规律及其影响因素。研究表明:孔隙度随压缩进行大幅降低,由压缩前4.36%降至0.61%;土体分形维数与孔隙度、上覆压力均呈线性相关性,相关系数分别为0.947 2和0.966 0;而且分形维数可以很好的表征孔隙分布特点,是孔隙度的有效补充;通过分析土样孔隙度与分形维数关系,为后期建立区域上地裂缝—地下水开采耦合模型提供参数赋值基础。     

Segmentation of abdominal organs from CT using a multi-level,hierarchical neural network strategy

Precise measurements on abdominal organs are vital prior to the important clinical procedures. Such measurements require accurate segmentation of these organs, which is a very challenging task due to countless anatomical variations and technical difficulties. Although, several features with various classifiers have been designed to overcome these challenges, abdominal organ segmentation via classification is still an emerging field in order to reach desired precision. Recent studies on multiple feature–classifier combinations show that hierarchical systems outperform composite feature–single classifier models. In this study, how hierarchical formations can translate to improved accuracy, when large size feature spaces are involved, is explored for the problem of abdominal organ segmentation. As a result, a semi-automatic, slice-by-slice segmentation method is developed using a novel multi-level and hierarchical neural network (MHNN). MHNN is designed to collect complementary information about organs at each level of the hierarchy via different feature–classifier combinations. Moreover, each level of MHNN receives residual data from the previous level. The residual data is constructed to preserve zero false positive error until the last level of the hierarchy, where only most challenging samples remain. The algorithm mimics analysis behaviour of a radiologist by using the slice-by-slice iteration, which is supported with adjacent slice similarity features. This enables adaptive determination of system parameters and turns into the advantage of online training, which is done in parallel to the segmentation process. Proposed design can perform robust and accurate segmentation of abdominal organs as validated by using diverse data sets with various challenges.     

Start-Up and Optimization of the Ozone Disinfection Process At the Sebago Lake Water Treatment Facility

The purpose of the ozone process at the Sebago Lake Water Treatment Facility (SLWTF) is to meet the disinfection requirements of the Surface Water Treatment Rule with ozone and without filtration. The start-up experience is presented including initial operating strategies to meet disinfection requirements. An ozone system performance test conducted during the first month of plant operation is described and the results are reviewed. The initial and proposed activities of an ozone optimization project are discussed.     

髋关节股骨近端CT序列图像外轮廓提取研究

为正确有效地分割出髋关节的外轮廓,提出了一种基于最佳分割线的股骨近端外轮廓的提取方法。该方法利用自底向上CT序列图像的帧间相似性找到一条分割目标股骨与其他骨骼的闭合分割线,从而利用该分割线来精确定位目标骨骼的位置,并搜索边缘点。实验结果表明,该方法能够准确地识别出股骨近端的外轮廓,自适应强,抗干扰性好。     

基于网络统考课程的学习支持服务构建

为满足学生在网络统考课程学习中自主学习的需要,学习支持服务系统的研究、设计构建和有效运行至关重要。各试点高校关于网络统考学习支持服务的实践和做法很多,但系统性研究和理论总结不够,作者结合工作实际尝试构建了网络统考学习支持服务体系基本框架。     

开放型电石炉绝缘问题浅见

介绍了开放型电石炉绝缘的结构特点，分析了绝缘材料的运行条件，讨论了绝缘系统的设计问题，提出了绝缘测试的三种方法。     

浅谈化工企业的采购管理

化工企业应重视采购计划预算，开发和管理供应商，考核采购绩效，增强企业竞争力。     

基于CT扫描的致密砂岩脆性破坏裂纹扩展规律研究

岩石在荷载作用下产生宏观破坏,其破裂面细观形态变化可以直接地反映出结构破坏特征。目前,常采用扫描电镜法、透镜法和CT扫描技术对岩石细观结构进行表征。运用CT扫描技术对典型脆性岩样单轴压缩破坏后破裂面及全断面进行扫描,获取全断面的细观形态,分析和总结了典型脆性岩样破坏细观裂纹扩展的发展规律:每一条独立裂纹都以一恒定曲率半径系数K随层位向试样内部扩展,直至裂纹曲率半径趋近于无穷。此时若无其他因素影响,其曲率半径则不会再随层位继续扩展;并通过分析定义出岩石脆性破坏状态时裂纹的聚集域和非聚集域,同时根据能量守恒定律得出了衍生裂纹及新次生裂纹产生的判据。     

大学网上考试系统的设计与实现

在对大学网上考试系统的开发背景和应用意义进行阐述的基础上,对大学网上考试系统的功能模块设计、系统开发方案、数据库设计和系统功能实现进行了详细介绍。系统基于B/S模式,实现了在线生成试卷、学生在线参加考试、自动生成考试成绩、学生和教师在线互动答疑和管理员后台数据管理等功能,提高了考试管理效率,为大学课程的教学和考试提供了一种高效、灵活、可靠和便捷的方式。     

B/S架构在线考试系统的断线续考功能的实现

随着教育信息化不断发展,基于Web的网络学习平台越来越多.在线考试系统是网络学习平台的重要组成部分.在线考试时由于多种原因,经常引发断线,致使考试过程中断.在线考试系统必须具备断线续考功能.文章介绍了B/S构架下ASP在线考试系统断线续考功能的工作原理及实现方法.