X线影像采集软件的设计与实现

针对没有数字输出接口的X光机,设计了X线影像数据的采集系统,在软件上以虚拟设备驱动和多线程为主要技术提高了影像采集、与影像处理的并行性。     

Active X技术用于开发流媒体Web页

介绍了Active X技术,探讨了在C++环境下创建Active X控件的方法,并以播放流媒体WindowsMedia Video为例说明了在Web中的应用。在教育部资助的网络多媒体项目开发过程中使用了多媒体Active X控件,使Internet应用程序更具有诱人的多媒体功能。     

X窗口系统通用剪贴板的设计与实现

剪贴板是窗口系统中不同客户间交互数据的重要手段。文章介绍了X窗口系统的选择机制和不同开发库的剪贴板实现,并针对不同实现间的不兼容问题提出了一个通用剪贴板管理器的设计思想,并在Linux系统上加以实现。     

一个基于多媒体X终端的协作CAD系统

本文提出了一种基于多媒体Ｘ终端的协作ＣＡＤ体系结构，它充分利用了Ｘ终端的网络透明性，将核心计算和用户间通讯的模块集中到高性能的主机上，从而提高了协作ＣＡＤ系统的性能。系统还提供了虚拟声音会议环境使得用户间可以直接地通过语音交互。     

基于X.509证书的授权管理中RBAC策略的研究

描述了基于角色的访问控制(RBAC)的策略以及基于策略的权限管理的系统框架,介绍了一个X.509权限管理模型及怎样来实现 RBAC,以及如何用XML设计网上交易系统权限管理的RBAC策略模型。     

计算机无线网络技术若干问题的探讨

概述了计算机无线网络的特点及其应用方向。对IEEE(institute of electrical and electronics engineers)制定的无线网络标准802．11x系列采用的关键技术和相互兼容性进行对比和分析。针对无线网络的WEP(wired equivalent privacy)加密漏洞，综合比较分析主要的网络公司采用的安全机制，如有线等效保密的改进方案(WEP2)、端口访问控制(802．1x Port Access Control for WLANs)、动态安全链路(DSL，dynamic security link)和虚拟专用网(VPN，virtual private network)等。     

Imaging biofilm in porous media using X-ray computed microtomography

In this study, a new technique for three-dimensional imaging of biofilm within porous media using X-ray computed microtomography is presented. Due to the similarity in X-ray absorption coefficients for the porous media (plastic), biofilm and aqueous phase, an X-ray contrast agent is required to image biofilm within the experimental matrix using X-ray computed tomography. The presented technique utilizes a medical suspension of barium sulphate to differentiate between the aqueous phase and the biofilm. Potassium iodide is added to the suspension to aid in delineation between the biofilm and the experimental porous medium. The iodide readily diffuses into the biofilm while the barium sulphate suspension remains in the aqueous phase. This allows for effective differentiation of the three phases within the experimental systems utilized in this study. The behaviour of the two contrast agents, in particular of the barium sulphate, is addressed by comparing two-dimensional images of biofilm within a pore network obtained by (1) optical visualization and (2) X-ray absorption radiography. We show that the contrast mixture provides contrast between the biofilm, the aqueous-phase and the solid-phase (beads). The imaging method is then applied to two three-dimensional packed-bead columns within which biofilm was grown. Examples of reconstructed images are provided to illustrate the effectiveness of the method. Limitations and applications of the technique are discussed. A key benefit, associated with the presented method, is that it captures a substantial amount of information regarding the topology of the pore-scale transport processes. For example, the quantification of changes in porous media effective parameters, such as dispersion or permeability, induced by biofilm growth, is possible using specific upscaling techniques and numerical analysis. We emphasize that the results presented here serve as a first test of this novel approach; issues with accurate segmentation of the images, optimal concentrations of contrast agents and the potential need for use of synchrotron radiation sources need to be addressed before the method can be used for precise quantitative analysis of biofilm geometry in porous media.     

大幅面超精密图形发生器X－Y工作台位置补偿校正

在超精密控制中，一般采用双频激光多卜勒测量系统作为位置测量元件．因存在机架、材料膨胀及材料、激光死区和环境空气变化，控制软件必须对此进行补偿校正．文中分析并推导出了有关的Ｘ－Ｙ工作台位置补偿校正公式，并给出了进行实际应用的例子．     

Effect of deteriorated microstructures on stress corrosion cracking of X70 pipeline steel in acidic soil environment

In order to investigate stress corrosion cracking (SCC) of X70 pipeline steel and its weld joint area in acidic soil environ-ment in China, two simulating methods were used: one was to obtain bad microstructures in heat affected zone by annealing at 1300°C for 10 min and then, quenching in water; the other was to get different simulating solutions of acidic soil in Yingtan in south-east China. The SCC susceptibilities of X70 pipeline steel before and after quenching in the simulating solutions were analyzed...