共查询到20条相似文献，搜索用时 171 毫秒
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本文应用有限差分法计算了方同轴线(第二型)的电位分布,计算出电磁场分布和该方同轴线的特性阻抗,同时讨论了特性阻抗与方同轴线的内外导体尺寸比的关系和在有限差分法计算时网格粗细对计算结果的影响. 相似文献
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平衡电缆的传输性能直接关系到数据通讯的质量,而直流环路电阻、特性阻抗、衰减、近端串扰损耗、衰减与串扰比、结构回波损耗、传输延迟等电气特性参数,是影响平衡电缆通道传输性能的主要因素.本文上述几个电气特性参数进行了细致的分析. 相似文献
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带状多导体传输线的特性参数提取 总被引：1，自引：0，他引：1
文章运用数值计算法矩量法提取位于同种介质中具有两接地板多导体传输线的电容、电感矩阵元素以及特性阻抗。主要分析了几种常见的带状多导体传输线,并与有关文献进行了对比,其平均误差小于2％,为以后的辅助计算公式研究以及电路设计等方面提供数值计算结果。 相似文献
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杭州临安电讯线材厂为适应飞速发展的电视事业的需要,开发生产了电视电缆新产品——SS75—5—4,SS75—7—4,12月上旬通过技术鉴定,已批量生产。临安电讯线材厂生产的SS75系列电视电缆质量在浙江处于领先地位。其特性阻抗、衰减常数、驻波特性、绝缘电阻、工频耐压及结构尺寸等技术指标均达到电子工业部第二十三 相似文献
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利用Aglient-ADS软件,仿真和设计出用EBG结构代替3dBWilkinson功分器A／4部分,使其在频率f=2.4GHz时特性阻抗为70．7Ω,相移为90°,不断在原理图中对整体结构进行调试、优化,使得在该中心频率下回波损耗小于-30dB,很好的实现了功率二等分。制作实物通过测量,发现和仿真结果有很好的一致性,从而验证了此EBG结构应用于二等分功分器的可行性。 相似文献
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刘晓娟 《大科技．科学之谜》2008,(8):54
我认为我们所处的时空是许多平行空间中的一个,在一些特殊的情况下,我们可以由一个时空进入另一个时空,但由于我们不属于那个时空,所以到达那个时空后,人们的时间会发生改变,在我们这个时空已经过了几年甚至几十年,对于穿越时空的人来说也许只过了几分钟或者几个小时,比如,神秘失踪了几十年的一架美国客机又惊现十世,飞机上的人依然像几十年前一样年轻。 相似文献
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文章简要介绍了普通钢筋混凝土异形柱结构的优点和应用情况,并分析提出了其存在的几点不足.在此基础上,针对这几个不足之处,提出了解决问题的几点措施. 相似文献
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结合农村集体土地征收的有关规定和在具体工作中遇到的实际问题,从征收权界定的不严谨、征地补偿标准和范围的不尽合理、征收程序等几方面提出了农村集体土地征收制度需要完善的几点看法;同时就上述几点问题及征地补偿、土地收益分配、完善土地征收制度等几个方面提出了几点意见。 相似文献
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It is shown that Youla's theory of broadband matching between a passive load and a resistive generator with a preassigned transducer power gain characteristic is completely equivalent to Wohlers' solution to the problem of compatible impedences, which transforms a given passive impedance by a lossless coupling network into another specified one. 相似文献
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The exact solutions of the design of stepped impedance transformers presented up to now have been tedious and subject to computational error. We present here an exact synthesis procedure which requires less effort than other exact procedures. In addition, two recurrence formulae are given for determining the characteristic impedances of each section. The coefficients so obtained can be compared to eliminate computational errors. We also present a graphical design procedure which is sufficiently accurate for many purposes and which has the advantages of speed and easy use. 相似文献
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简述了数据、图像、声音传输设备中数据线的重要性,分析了当前数据、图像、声音传输设备中数据芯线的缺陷,要达到高频、高速、低衰减的传输要求,唯有降低数据线芯线的介电常数和介电损耗,重点阐述了双层复合PE发泡芯线的材料、结构及性能,从而满足高频、高速、低衰减的传输要求。 相似文献
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Andrew Sobczyk 《Journal of The Franklin Institute》1948,246(3):187-213
In a servomechanism using a two-phase alternating current control motor, a 90° difference is required in the phases of the carrier-frequency voltages applied to the fixed and control windings. This part describes and compares various methods of obtaining the phase difference.The question of the possibility of a phase-shifting proportional-derivative parallel “T” is answered in the negative, by the result that in any parallel “T” transfer characteristic, if the quadratic factor in the numerator is of the proportional-derivative form at the correct resonant frequency, the amount of phase shift which may be obtained from the remaining portion of the transfer characteristic is less than are tan , where n is twice the carrier frequency divided by notch width. Thus for values of n high enough to have an appreciable stabilizing effect, the maximum obtainable intrinsic phase shift is negligible.In order to obtain a large phase shift it is necessary to add either a series input or a load impedance to the parallel “T,” or to use a phase-shifting network preceding or following the parallel “T.” Formulae and design charts are given for determination of the values of the components of phase lag networks.The method of calculation of tolerance requirements on the components, in terms of allowable deviation from the correct phase, is illustrated by an example of a phase lag network used in conjunction with a bridge “T” proportional-derivative network. 相似文献
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针对操作系统的课程特点及传统教学方式,本文对操作系统的教学改革进行思考与研究,提出了采用体系化的教学模式、采用启发式教学模式、采用拓展学生知识的教学方式及采用循序渐进的教学模式等教学方法等内容。 相似文献
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The grid current required to fire a thyratron has been shown to depend theoretically upon the shape of the grid current characteristic before firing as well as upon the grid circuit constants.The three-element FG-17 and the four-element FG-95 and FG-98 thyratrons have been investigated.Anomalies where excessively large grid currents were required to start the arc, occurring below certain values of temperature and plate potential, have been found and are described in some detail.Although the argon-filled FG-98 was found to be free from temperature effects over the operating range, positive shield grid potentials introduced anomalies at low plate potentials.Even though the plate and shield potentials and the temperature were kept within the recommended optimum range, it was found that for minimum grid currents at firing the negative grid impedance of these tubes necessitated a grid resistance of 100 to 1000 megohms. 相似文献