A general fan-beam reconstruction algorithm for free-form trajectories

In this paper we develop a general exact fan-beam reconstruction algorithm for free-form trajectories not only closed but also unclosed, based on the fan-beam reconstruction formula recently developed by Noo et al.. A mathematical proof is then provided with the geometrical explanation of equi-spatial detectors. With this algorithm we can obtain exact region of interest (ROI) reconstruction if and only if every projecting line passing through the ROI intersects the free-form source trajectory, when the projections are not truncated. Furthermore, under the condition that the source-to-detectors distance changes slowly enough relative to the length itself, we obtain a very good approximate reconstruction algorithm, which is the same as the algorithm of the circular trajectory except that the source-to-detectors distance is a function of the rotation angle. Then the algorithms are tested using the Shepp-Logan phantom and the experiment shows that the algorithms can get perfect numerical results.     

微振动对空间实验室微重力环境的影响研究

针对大型刚柔组合体空间结构(空间实验室)的特点,建立系统的动力学方程,并对机柜内设备、太阳阵的转动、宇航员活动产生的激扰力进行了简化。利用计算机建立组合体的简化模型,对空间组合体在各种微振动激扰下的加速度响应进行了仿真研究,并将这些仿真结果用于空间实验室微重力环境的预测。     

武钢二炼钢厂炉机匹配系统算法研究

武钢集团第二炼钢厂的炉机匹配系统可简化为两道工序的车间作业排程问题。其问题的关键在于合理调配3台转炉的工作时段以满足4台铸机的不间断运转。本文提出了一种快速有效的算法——压缩-扩张算法，为整个系统的最后实现，提供了最关键的支持。     

基于PNX1500的多路硬盘录像机设计

基于Philips公司的多媒体数字信号处理器PNX1500实现的多路嵌入式硬盘录像机方案,成本较低,开发难度小,易于大规模应用。文章对PNX1500与目前比较常用的视频处理芯片进行对比并作简要的分析;介绍PNX1500的主要性能和特点,详细阐述以PNX1500为核心的多路嵌入式硬盘录像机的构成和工作原理;提出简单可靠地扩展硬盘接口的一种方案,使其能保存更多的录像资料;简要说明外围芯片的选择,主、从软件的设计方法和工作流程,并对系统的应用作了介绍。此方案拥有广阔的应用前景。     

Preparation and characterization of Ni/Co bimetallic nano-clusters

Ni/Co bimetallic nano-cluters have been prepared from the aqueous solution by reducing their corresponding metal salts under suitable conditions. The experimental conditions including the type and concentration of protective agent, feeding order and the pH of the solution that influence the average particle size have been studied in detail. Transmission electron microscopy (TEM) indicates that the shape of those bimetallic nano-cluster particles is spheroid. The alloy structure has been shown by X-ray powder diffraction (XRD). The X-ray photoelectron spectroscopic (XPS) data have confirmed that the nickel and cobalt in the bimetallic nano-clusters are in the zero-valence state.     

iButton技术在安防系统中的应用

本文介绍了一种新型的智能化信息载体iButton以及iButton在安防系统上的应用举例，着重介绍了其硬件、软件设计及工作原理。     

用InTouch、MATLAB和VC++开发工业监控系统软件

本文针对工业自动控制的需要开发了基于InTouch、MATULB以及VC 三者混合编程的具有普通分散控制系统不具备的较完善控制功能(例如人工神经网络控制)的控制系统监控软件。本系统可通过通信连入控制网络。开发时充分利用了三者各自的优点。使本系统具有较高的开发效率和应用价值。     

智能型超声波钢轨探伤仪

文中介绍采用三片单片机设计的新型智能STG-2000型超声波钢轨探伤仪。它具有全数字式控制、便携性好、低功耗、高速动态检测、实时报警、整体操作简便等特点。由于内核采用三片兼容MCS-5l单片机构造的多机并行系统，这个产品使超声波钢轨探伤工作提高到了一个新的水平。     

络合剂对胶束三元络合物显色体系的影响1──锆(Ⅳ)-m-NPF-CTMAB 显色体系及其应用

在０．２４～０．４２ｍｏｌ／ＬＨＣｌ介质中，研究了１７种络合剂对锆（Ⅳ）－ｍ－ＮＰＦ－ＣＴＭＡＢ显色反应的影响。除乳酸、甘露醇、α－羟基异丁酸、氧代戊二酸和柠檬酸外，其余络合剂都使体系的吸光度降低。有乳酸和甘露醇存在下，有色络合物的表观摩尔吸光系数为１．３０×１０５Ｌ·ｍｏｌ－１·ｃｍ－１。Ｚｒ（Ⅳ）在０～１０μｇ／２５ｍＬ符合比尔定律。方法用于铝合金中微量锆的测定，结果满意。     

血红素中卟啉Fe（Ⅱ）的简正模式分析

将血红素中卟啉Ｆｅ（Ⅱ）环作成一个Ｃ４ν群，并导出了其简正坐标与简正振动模式．