Optimization for limited angle tomography in medical image processing

This paper aims to reduce the problems of incomplete data in computed tomography, which happens frequently in medical image process and analysis, e.g., when the high-density region of objects can only be penetrated by X-rays at a limited angular range. As the projection data are available only in an angular range, the incomplete data problem can be attributed to the limited angle problem, which is an ill-posed inverse problem. Image reconstruction based on total variation (TV) reduces the problem and gives better performance on edge-preserving reconstruction; however, the artificial parameter can only be determined through considerable experimentation. In this paper, an effective TV objective function is proposed to reduce the inverse problem in the limited angle tomography. This novel objective function provides a robust and effective reconstruction without any artificial parameter in the iterative processes, using the TV as a multiplicative constraint. The results demonstrate that this reconstruction strategy outperforms some previous ones.     

铁路线路智能CAD(IRLCAD)系统中的三维景观动态仿真

铁路线路是大地上长大带状建筑物。自然环境和既有的人工建筑对线路走向的规划起着根本性的作用。在计算机上用三维景观动态仿真技术模拟现实环境,让工程师动态地对规划线路经行地区的环境进行观察和分析,从而作出线路走向决策,将是一种理想的设计境界。介绍了铁路线路智能CAD系统中的三维景观动态仿真技术。     

一个实用的面向中小型企业的产品数据管理系统

介绍了一个面向中小型企业的产品数据管理系统SMPDM。它是一个建立在PDM基本框架之上,集产品结构与配置管理、图档管理、工艺卡片管理及编码管理为一体的实用系统。它实施简单,见效快,是管理中小型企业产品数据的良好工具。     

对MMI质量流量计计量系统通信故障的处理

武汉石油化工厂计量办检测站于１９９５年５月投用了一套用于成品油水路出厂计量的质量流量计微机计量系统,运行两年多,工厂的成品油出厂损耗逐年下降（目前实际出厂损耗率已经控制在１０．１％以内,远远低于±０．３％的国家标准）,用户索赔情况日趋减少,取得了较好的经济效益和社会效益。其后,该系统的通信部分突发故障,计算机无法采集流量计的数据,造成系统停用。我们经过认真检测、分析,终于排除了故障,保证了成品油出厂计量。具体介绍如下,供交流。１系统简介 检测站毗邻我厂的长江码头,进出厂的油品管线均经过此地。按规…     

CORBA动态测试工具设计

在网络管理系统中CORBA技术被广泛应用在北向接口模块中,在测试这类模块时通常会针对不同的规范开发专门的测试程序,费时费力,且没有通用性。该文介绍了一个基于idl语法分析的动态测试工具,可动态测试不同规范的CORBA接口,大大提高了生产效率。     

Structural-symmetry-related sequence patterns of the proteins of beta-propeller family

It is still not very clear to what extent and how does the amino acid sequences of proteins determine their tertiary structures. In this paper, we report our investigations of the sequence-structure relations of the proteins in the beta-propeller fold family, which adopt highly symmetrical tertiary structures while their sequences appear "random". We analyzed the amino acid sequences by using a similarity matrix plus Pearson correlation method and found that the sequences can show the same symmetries as their tertiary structures only if we deduce the conditions of sequence similarity. This suggests that some key residues may play an important role in the formation of the tertiary structures of these proteins.     

Performance lower bounds in stochastic robust and adaptive control

The fundamental issues of capability of robust and adaptive control in dealing with uncertainty are investigated in stochastic systems. It is revealed that to capture the intrinsic limitations of adaptive control, it is necessary to use sup_t types of transient and persistent performance, rather than lim sup_t types which reflect only asymptotic behavior of a system. For clarity and technical tractability, a simple first-order linear time-varying system is employed as a vehicle to explore performance lower bounds of robust and adaptive control. Optimal performances of nominal, robust and adaptive control are explicitly derived and their implications are discussed in an information framework. An adaptive strategy is scrutinized for its achievable performance bounds. The results indicate that intimate interaction and inherent conflict between identification and control result in a certain performance lower bound which does not approach the nominal performance even when the system varies very slowly. Explicit lower bounds are obtained when disturbances are either normally or uniformly distributed     

工控系统组态软件体系结构的研究

详细地论述了工控系统的典型结构,各部分的功能和作用,以及组态软件的设计思想和体系结构。提出了工控系统组态软件设计所涉及的重要相关技术问题。     

低压长袋脉冲袋式除尘器设计与应用

以工业原料尤里卡沥青(EP)为对象，详细论述了低压长袋脉冲袋式除尘器的主要设计环节，着重分析了新型脉冲阀技术。指出了该技术在化肥行业原料干燥、风扫制备等方面的推广应用和发展趋势。