共查询到20条相似文献，搜索用时 343 毫秒
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姚明基 《中山大学学报论丛》2001,21(5):197-202
结合出版社印制管理工作的实际，论述印制人员应具备的整体素质，以达到提高出版社印制管理水平的目的，并达到提高出版社双效益的目标。 相似文献
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蓝军 《中国教育技术装备》2002,(1):21-22
仪器设备印制线路板的结构设计的训练对电子类相关专业学生和电子爱好者来说是必不可少的,但是学生对印制线路板的制作觉得无章可循,制作得往往很不规范。本文在此介绍印制线路板结构 相似文献
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两阶段方法能够高效地对稀有类进行分类，第一阶段(P阶段)训练P规则预测目标类的存在性．这些P规则覆盖绝大多数的正例(目标类例子)，在该阶段中尽量覆盖那些属于目标类的正例．第二阶段(N阶段)学习N规则预测目标类的不存在性，其所基于的数据集为所有P规则所覆盖的正例和反例(非目标类例子)集．N规则的目标是尽量去除由P规则所引入的反例，并尽可能地保留正例，在该阶段中尽量获得高精度．在测试阶段对所得到P规则和N规则根据一定的分值机制赋值，并根据这些规则的分值来分类． 相似文献
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运用物理雕刻的线路板制作系统的研制 总被引：2，自引：0，他引：2
首先介绍了传统的印制电路板的制作方法，接着介绍了自主开发的基于物理雕刻的PCB制作系统的原理，该系统把用户定义的PROTEL文件通过计算机控制输出到雕刻机，在空白的覆铜板上把不必要的铜泊铣去，形成用户定制的线路板，非常适合电子类学校进行线路板制作的课程实验。 相似文献
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《中学生(作文版)》2012,(12):64-64,F0003
可以吃的求生手册
某著名越野车品牌印制了一本很特别的野外求生手册。手册中有各式各样的求生技巧，而它最大的亮点是整本手册的印制原料皆是可食用的，使用者直接撕下来就能吃。关键时刻可以救自己一命。 相似文献
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积层印制电路板（简称积层板）是由独立的印制电路板或由内层间被绝缘材料分隔的电路板组成的。本文综述了国内外积层印制电路板的最新研究进展。 相似文献
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符兴昌 《乐山师范学院学报》2005,20(12):47-48
电子设计自动化（EDA）软件是电子工程师们进行电子设计的重要工具，protel是电子设计自动化中最为流行的软件之一。文中介绍了其最新版本protd99SE的功能特点，并通过设计一个由555定时器组成的报警电路为例，详细介绍了使用该软件设计电路原理图和设计印制电路板（PcB）的具体步骤，最后分析了在设计过程中出现的一些常见问题以及解决的具体措施。 相似文献
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基于Richards变换与Kuroda规则的射频滤波器设计 总被引：1，自引：0，他引：1
介绍了一种将集总参数转换为分布参数的Richards变换，利用双口网络演变而来的单位元件矩阵，论述了传输线结构之间的相互变换规则，即Kuroda规则。以这两种理论为基础设计出一种实用射频带通滤波器。 相似文献
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We used computational fluid dynamics （CFD） and mode superposition method instead of the energy balance method to compute transmission line aeolian vibrations induced by the Karman vortex. Firstly, we obtained the wind power inputs using CFD theory. The result is effective for aeolian vibration analyses compared with the power which were measured in wind tunnel tests. Then a new aeolian excitation was derived using the wind power equivalent principle, and the aeolian vibration distribution along transmission lines and the wind power input obtained by CFD can be account. Secondly, we formulated the motion equation of a conductor-damper system and derived a semi-analytial solution using the mode superposition method. The Stockbridge-type dampers attached were simplified to the forces transmitted by the clamps. Finally, the semi-analytical solution can be solved by iterative methods. Taking a 1 000 kV Ultra High Voltage transmission line as an example, we analyzed the line with and without dampers by the semi-analytical solution. Compared with the results which were computed by the energy balance method, the semi-analytical solution is precise enogh for aeolian vibration analyses. Besides, we also analyzed the influence of damper position and quantity. 相似文献
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HU Xin HE Sailing 《浙江大学学报(A卷英文版)》2007,8(8):1179-1182
We propose a new class of negative refractive index transmission line in which ideal operational amplifiers are applied to form the periodically loaded negative-impedance-converted inductors and capacitors. The phase response of the new trans-mission line is opposite to that of a positive refractive index conventional transmission line. Unlike the existing negative refractive index transmission line,the new negative refractive index transmission line is non-dispersive and thus can lead to many novel applications such as designing new broadband devices. 相似文献
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HDB3码是一种应用广泛的线路传输码。作者根据HDB3码的编码规则设计了硬件编码器,并在SYSTEMVIEW仿真软件平台上构建了仿真实验系统。仿真结果表明,设计正确,电路实现较为简便。可用于通信原理教学的课堂演示和设计性实验。 相似文献
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李靖平 《黎明职业大学学报》2014,(1):76-80
结合ARM、3G技术,设计一套输电线路状态的远程监测系统。监控终端采用处理器S3C6410为核心板,搭载控制芯片为OV9650的摄像头和中兴AD3812的3G模块。监控系统包含图像监控及周围环境参数监控,提供多种监控模式,灵活实用;在不影响监控效果的情况下,使用ARM11处理器对数字图像直接进行处理,降低开发成本;同时使用3G发送静态图像而不是视频减轻系统的工作负担;通过图像的预处理及识别程序,能智能化地判断出引起场景变化的人还是物。该系统具有覆盖范围广、传输特性好、功耗低及方便实用等特点,对输电线路的监测具有重要的现实意义。 相似文献
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The origin of the familiar valence band-forbidden gap-conduction band features of the electronic energy level scheme of a crystalline solid is developed according to 1) the extension of the atomic energy level scheme for individual atoms, 2) examination of the quantized momentum spectrum of a valence electron gas in a periodic potential enclosure, and 3) analogy with the pass-band and stop-band features in the frequency characteristic of a periodically-loaded mechanical transmission line. Since the first two approaches are amply treated in the conventional literature, this paper dwells particularly on the third approach, which may be preferred over the other two by readers having more extensive backgrounds in mechanical or electrical engineering than in theoretical physics. A simple mechanical wave transmission apparatus is described, with which the frequency characteristic can be observed and plotted. This characteristic is then related to the energy band picture of a solid by recognizing that a crystal can be regarded as a "loaded" transmission line for electron waves. 相似文献
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研究了光脉冲通过光子晶体线缺陷波导的透射特性.分析发现光子晶体线缺陷波导的透射行为与波导的几何尺寸有关.通过调制波导的几何结构可以获得较平坦的透射谱.另外发现耦合线缺陷所选择的点缺陷是影响线缺陷波导透射特性的重要因素,通过调节点缺陷的尺寸,缺陷间可以很完美的耦合并获得超平坦的杂质带.该分析结果为光子晶体线缺陷波导的设计提供重要参考. 相似文献
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In the last twenty years, researchers have studied students’ mathematical and scientific conceptions and reasoning. Most of this research is content‐specific. It has been found that students often hold ideas that are not in line with accepted scientific notions. In our joint work in mathematics and science education, it became apparent that many of these alternative conceptions hail from a small number of intuitive rules. We have so far identified two such rules: ‘The more of A, the more of B’, and, ‘Everything can be divided by two’. The first rule is reflected in students’ responses to many tasks, including all classical Piagetian conservation tasks (conservation of number, area, weight, volume, matter, etc.), all tasks related to intensive quantities (density, temperature, concentration, etc.), and tasks related to infinite quantities. The second rule is observed in responses related to successive division of material and geometrical objects, and in seriation tasks. In this paper we describe and discuss the second rule and its relevance to science and mathematics education. In a previous paper (Stavy and Tirosh 1995, in press) we described and discussed the first rule. 相似文献
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In the last twenty years researchers have studied students’ mathematical and scientific conceptions and reasoning. Most of this research is content‐specific. It has been found that students often hold ideas that are not in line with accepted scientific notions. In our joint work in mathematics and science education it became apparent that many of these alternative conceptions hail from the same intuitive rules. We have so far identified two such rules: ‘The more of A, the more of B’ and, ‘Everything can be divided by two’. The first rule is reflected in students’ responses to many tasks, including all classical Piagetian conservation tasks (conservation of number, area, weight, volume, matter, etc.), in all tasks related to intensive quantities (density, temperature, concentration, etc.), and in tasks related to infinite quantities. The second rule is observed in responses related to successive division of material and geometrical objects, and in successive dilution tasks. In this paper we describe and discuss the first rule and its relevance to science and mathematics education. In a second paper (Tirosh and Stavy, in press) we shall describe and discuss the second rule. 相似文献
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田婧 《湖南第一师范学报》2009,9(2):130-132
目的论包含目的法则、连贯法则和忠实法则。通过分析可以发现,王佐良的英译本《雷雨》符合目的论的三个法则．实现了他的预期目的。译本把握了原作的创作精神,再现了戏剧人物形象——谈吐恰如其人,语气切合其境,句式流畅明快。 相似文献