一种5阶1位∑-△调制器的设计

提出了一种稳定的5阶∑-△调制器的设计与调试方法.电路采用5阶级联结构,主要用CMOS开关电容技术实现,文章重点放在调制器结构的设计及几种防止系统发散和改进性能的途径上.模拟实验表明,经过改进的系统有较好的性能.     

酯化变性淀粉的制备与应用性能

以醋酸酐为改性剂合成了酯化变性淀粉，通过红外光谱验证了该反应的发生。探讨了改性剂用量、反应温度和反应时间对变性淀粉取代基含量的影响。实验结果表明，反应体系的最佳反应条件是pH值为8．0—8．5，醋酸酐质量为2．08，原淀粉质量为18g，反应时间为11h，反应温度为35℃。经改性后的变性淀粉的加工和应用性能都比原淀粉有了较大的改善。     

HDI—LineCard制造技术与应用初探

文章以设计、制造、组装的顺序对HDI-LineCard产品现状进行叙述。重点从对准度、通孔/盲孔成型、通孔/盲孔的金属化以及可靠性方面讲述了HDI-LineCard产品制造的着力点,文末对未来HDI-LineCard的技术发展趋势进行了展望。     

Pilot Symbol Assisted Hybrid Detection for OFDM‐Based Spatial Multiplexing Systems

In this paper, we provide a new detection scheme for a pilot symbol assisted interference nulling and cancellation operation to reduce unexpected effects owing to parallel transmission in orthogonal frequency division multiplexing (OFDM)‐based spatial multiplexing systems. We have shown that the investigated OFDM vertical Bell laboratories layered space time (VBLAST) detection based on hybrid processing performs better than ordinary OFDM‐VBLAST detections based on serial processing and parallel processing, respectively.     

Synthesis and characteristics of carbon-coated iron and nickel nanocapsules produced by arc discharge in ethanol vapor

Fe(C) and Ni(C) nanocapsules with low carbon content have been produced via an arc discharge process in ethanol vapor. It is clarified by X-ray diffraction that the core of the Fe(C) nanocapsules consists of γ-Fe, α-Fe and Fe₃C phase, while that of the Ni(C) nanocapsules contains only nickel. High-resolution transmission electron microscopy imaging confirms that these particles have a broad size distribution and the core/shell structure. Besides mutually independent nanocapsules with segregate graphitic shells, those with sharing shells are also observed in the Fe(C) nanocapsules. The remanence and the coercivity at room temperature of both the nanocapsules are higher than those of the corresponding microcrystallines, while the saturation magnetization is lower.     

国内未来车用汽油机技术的发展趋势

阐述了国内各车用汽油机制造厂商为满足国家乘用车新产品第二阶段燃油经济性法规的要求，最可能优先采用的对现有产品进行技术改造的方案，并展望了远期的发展趋势。     

精馏塔的故障诊断方案设计

本文简单地介绍了精馏塔故障诊断的必要性。主要讨论了精馏塔的故障诊断专家系统和故障诊断的具体步骤(其中主要包括建立设备档案、确定检测方法、检测周期及维修时间和性能预测及档案管理)。只有将维修技术、故障诊断技术和计算机远程监测技术有机的结合，才能有效地预防和避免事故、优化操作条件和延长操作周期，为企业取得更大的经济效益和社会效益。     

An automatic focusing algorithm

A simple and effective automatic focusing algorithm is proposed in this article. The principle of the proposed automatic focusing algorithm is based on that, for the radial test pattern, a best‐focused image should have the smallest blurred region in the middle of the acquired image, and hence, should have the smallest equivalent radius. The circular Hough transform has became a common method in numerous image‐processing applications for circle detection. Various modifications to the basic circular Hough transform have been suggested, such as: the inclusion of edge orientation, simultaneous consideration of a range of circle radii, the use of a complex accumulator array with the phase proportional to the log of the radius, or for filter operations. The purpose of this work is to show that a radius of a circular region extracted by a normalized circular Hough transform is a possible solution for determining the sharpness of images. To acquire high quality images with a given CCD camera, it is crucial that the camera be located exactly at the back length of the lens, i.e., the focus position of the lens. In the best conditions, the contours of the acquired images are of the sharpest, with none of the blurring effects associated with unfocused images. Acquiring such high quality images by these means is the main goal of the automatic focusing algorithm proposed in this article. © 2003 Wiley Periodicals, Inc. Int J Imaging Syst Technol, 12, 235–238, 2002; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ima.10029