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任国屋 《固体电子学研究与进展》1983,(1)
<正>设计低噪声场效应放大器时,器件的“s”参数和最佳信源阻抗是极其重要的参数.根据GaAs MESFET“s”参数理论计算公式,从小信号等效电路元件值计算WC50型MESFET的“s”参数列于表1. 相似文献
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基于混合遗传算法的偏振双向反射分布函数优化建模 总被引:1,自引:0,他引:1
为了表征复杂涂层表面的光学散射特性,在微面元理论的基础上,建立了典型涂层样片的偏振双向反射分布函数模型.由于实验数据与模型参数之间存在复杂的非线性关系,采用了遗传算法对模型参数进行反演.针对遗传算法收敛速度慢及易限于局部极小的特点,在传统遗传算法参数反演的基础上,在适应度计算中引入了模拟退火算法对偏振双向反射分布函数模型进行优化建模.实验结果表明:模型的计算结果与实验结果吻合较好.从误差收敛曲线来看,这种混合遗传算法优化方法不仅可以有效避免目标函数陷入局部极小,而且可以有效缩短目标函数的收敛时间.这可以为后续的目标特征提取与识别工作提供参考. 相似文献
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本文基于二阶暂时分解模型,利用LSF参数的有序性,给出了一种用于LSF参数压缩的TD算法,在参数未量化的情况下可获得约为1.28dB的平均谱失真,对表征随时间变化的LSF参数序列的事件函数和事件函数矢量分别进行矢量量化,实验结果表明编码速率在500b/s以下时,能够获得一个相对较低的平均谱失真. 相似文献
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器件模型参数优化提取的混合算法 总被引:1,自引:0,他引:1
本文论述了器件模型参数优化提取中常采用的L-M算法存在的一些问题.提出了用(LM-BFGS)混合算法提取器件模型参数,这对优化收敛有极大的加速作用.本文例举了大量实验函数的计算结果并结合MOSFET的参数提取,证明了该算法可以大大减少迭代的次数和计算非线性目标函数的次数. 相似文献
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针对圆柱分层媒质ρ向格林函数的计算问题,提出了一种有效的计算方法.给出了谱域并矢格林函数的具体表达式,利用广义函数束法(GPOF)将谱域格林函数转化成闭合形式的空域格林函数,尤其是在文献[4-5]基础上对GPOF法中的积分路径进行了改进,有效解决了采样参数设定难、稳定性差的缺点,实现了快速计算的目的.利用二次包络提取法解决了探针与贴片连接处格林函数奇异性和慢收敛性的问题.通过仿真计算验证了本文方法的有效性,从而为利用矩量法求解探针馈电圆柱共形微带天线奠定了基础. 相似文献
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计算高温气体辐射特性对尾喷焰的远程探测具有重要意义.引入普朗克函数加权求吸收系数k的几率分布函数,建立了一种新的计算气体辐射特性的宽带k分布模型.从高温气体数据库(HITEMP)读取吸收气体谱线特性参数,计算得到二氧化碳和水汽的k分布吸收系数.用多项式拟合了宽带k分布模型参数,混合气体的k分布吸收系数由单一气体k分布吸收系数直接相加得到.用该模型计算了某尾喷焰红外谱段和可见谱段的远程探测辐射强度,与逐线积分计算作了比较,结果表明:该宽带k分布模型和逐线计算结果的相对误差在7%以内,大大减少了气体辐射特性的计算时间. 相似文献
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A. I. Chizhov 《Journal of Communications Technology and Electronics》2009,54(5):557-564
A procedure for calculating the parameters of matching circuits in the case of complex-valued impedances of the generator and the load has been developed. The procedure has been tested by calculating the parameters of a microwave amplifier based on a Schottky-barrier field-effect transistor and by measuring the amplifier’s characteristics. The test results are presented. 相似文献
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Charczenko W. Weitzman P.S. Klotz H. Surette M. Dunn J.M. Mickelson A.R. 《Lightwave Technology, Journal of》1991,9(1):92-100
Fast and accurate numerical techniques are developed for calculating the optical depth of modulation of integrated optical devices with various dielectric buffer layers. The matrix effective refractive-index method is used in calculating the LiNbO3 proton exchange single-channel optical mode parameters. An approximate technique for calculating electrode electric-field distributions as a function of various buffer layers is presented. Comparisons of computer simulations to experimental measurements performed on Mach-Zehnder modulators containing various buffer layers demonstrate that the numerical techniques are sufficiently accurate for computer-aided design use 相似文献
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为了实现能产生重复频率矩形高压脉冲输出的紧凑型脉冲功率源,设计了基于脉冲形成网络的直线型脉冲变压器。以陶瓷电容和光导开关构建全固态Blumlein型脉冲形成网络,分析了磁芯参数对能量效率和平顶度的影响,计算了设计的脉冲功率源的分布参数,并基于分布参数建立了了全电路模型。研究结果表明足够的磁芯伏秒数是直线型脉冲变压器运行的必要条件,而分布参数是引成输出脉冲畸变的另一重要因素。 相似文献
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B. M. Levin 《Journal of Communications Technology and Electronics》2012,57(4):388-392
The method for calculating parameters of transparent metal films is improved. An equation for the current flowing along a
transparent radiator is derived and solved. The current distribution along the radiator’s axis is analyzed on the basis of
a solution to this equation. It is shown that, depending on parameters, transparent materials fall into two groups with two
different types of the current distribution. Antenna variants are calculated. A specific model antenna is proposed. 相似文献
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K. S. Sunduchkov A. L. Golik S. E. Volkov A. S. Yashchuk I. K. Sunduchkov 《Radioelectronics and Communications Systems》2014,57(8):369-375
It is proposed a number of new technical solutions to implement the delivery of multimedia signals 4G services with data transfer rate for each subscriber 6–12 Mb/s, which move at a speed of 300–350 km/h with a total capacity of the network over a thousand subscribers. The block diagram (architecture) of transfer network in the millimeter wavelength band is developed. We derived balance equation for the network radio energy, which is the basis of the method for calculating the radio channel parameters. Examples of calculation of radio wireless access parameters to mobile terminals in the millimeter range are presented. 相似文献
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信号瞬时参数计算方法评价 总被引:30,自引:1,他引:29
在许多实际问题中,信号瞬时参数的提取有重要意义。数十年来,人们已提出多种计算方法,但这些方法均有一定局限性。本文通过几个有代表性的信号对一些典型算法的误差与适用范围作了分析与比较。我们在文中提出了一种适用于单纯变频信号的瞬时频率精确计算方法。最后,介绍了一种近期内发展起来的适用于一般非线性、非平稳信号的经验模式分解方法。 相似文献
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提出了计算语音信号线谱对(LSP)参数的高效算法NRSPF。首先利用牛顿法-拉夫森函数及斯蒂芬森加速求高阶非线性方程的一个实根,再使用多项式综合除法降阶,最后采用费拉里算法求其余的根,即得LSP参数。通过TI-DSP平台的实例研究表明,NRSPF算法与APF算法相比,迭代次数减少、收敛速度加快,计算量小,并且在精度提高10倍、100倍和1000倍情况下,APF算法可能出现被零除错误和死循环,而NRSPF算法不仅避免了该错误,而且迭代次数增加很少,收敛速度仍然很快,得到更精确的结果。本文提出的算法高效、可靠、实时性强,可应用于超低码率语音实时通信系统、语音编解码器等。 相似文献
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A method for determining the noise parameters of MESFET's solely from their S parameters is presented in this paper. The enhanced Johnson noise, the diffusion noise, the thermal noise, the influences of bias condition, the effect of parastic resistances and the aftermath of package are all taken into consideration in the noise model. The calculating results of our method agree very well with the measured data. This method can be employed rapidly, conveniently, both at the wafer stage of device fabrication and to packaged devices. 相似文献
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A. A. Anosov R. V. Belyaev V. A. Vilkov A. S. Kazanskii Yu. A. Less A. D. Mansfel’d A. S. Sharakshane 《Journal of Communications Technology and Electronics》2010,55(9):1044-1051
The correlation and noncorrelation methods for the reception of thermal acoustic radiation are tested experimentally. For
the correlation reception, a formula is obtained for calculating the temperature distribution of an object from the measured
crosscorrelation pressure functions of thermal acoustic radiation. Noncorrelation measurements with the use of two mutually
perpendicular planar arrays, each consisting of seven sensors, have made it possible to determine the parameters of the 3D
temperature distribution. The measurement duration is 10 s. 相似文献