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从非周期信号的FT到周期信号的FS 被引量:2
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作者 宫二玲 孙志强 刘亚东 《电气电子教学学报》 2015年第6期42-44,共3页
傅里叶分析是"信号与系统"课程中的一个重要内容,一般的讲授顺序是由周期信号的傅里叶级数演变出非周期信号的傅里叶变换;若是反过来讲授,即如何由非周期信号的频谱密度函数得到周期信号的傅里叶级数系数,是否行得通?针对这... 傅里叶分析是"信号与系统"课程中的一个重要内容,一般的讲授顺序是由周期信号的傅里叶级数演变出非周期信号的傅里叶变换;若是反过来讲授,即如何由非周期信号的频谱密度函数得到周期信号的傅里叶级数系数,是否行得通?针对这一问题,本文应用两种不同的思路加以解决,从而澄清了傅里叶级数系数和频谱密度函数之间的关系,有助于学生对傅里叶分析理论体系的深刻理解。 展开更多
关键词 信号与系统 傅里叶级数系数 频谱密度函数
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双折射晶体时域电光综合器
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作者 王吉明 刘立人 +1 位作者 刘德安 赵栋 《光学学报》 EI CAS CSCD 北大核心 2006年第2期283-289,共7页
提出了一种利用电光双折射网络实现的光波波形综合器。该综合器由偏振器、多块具有电光效应的双折射晶体和补偿器组成,输入余弦信号,组成一多级电光双折射网络。利用琼斯理论对该综合器进行了理论分析,根据扩展傅里叶级数系数正向对比法... 提出了一种利用电光双折射网络实现的光波波形综合器。该综合器由偏振器、多块具有电光效应的双折射晶体和补偿器组成,输入余弦信号,组成一多级电光双折射网络。利用琼斯理论对该综合器进行了理论分析,根据扩展傅里叶级数系数正向对比法,实现了其他类型的周期性时域波形。给出一类三元综合器的分析与设计方法,得到合成矩形波与三角波所需的多组结构参量,并对输入信号误差及方位角误差对波形的影响进行了分析。 展开更多
关键词 光电子学 电光综合器 偏振干涉 扩展傅里叶级数系数对比法 波形
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On the universal third order Stokes wave solution 被引量:2
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作者 SONG ZhiYao ZHAO HongJun +1 位作者 LI Ling Lü GuoNian 《Science China Earth Sciences》 SCIE EI CAS 2013年第1期102-114,共13页
This paper presents a universal third-order Stokes solution with uniform current. This solution is derived on the basis of potential theory by expanding the free surface and potential function in Fourier series and de... This paper presents a universal third-order Stokes solution with uniform current. This solution is derived on the basis of potential theory by expanding the free surface and potential function in Fourier series and determining the Fourier coefficients by solving a set of nonlinear algebraic equations through the Taylor expansion and perturbation method. The universal solution is expressed upon the still water depth with the still water level as datum and retains a global perturbation parameter. The wave set-up term generated by the self-interaction of oscillatory waves is explicitly included in the free surface function. With the use of different definitions for the wave celerity, different water levels as the datum, different non-dimensional variables as the perturbation parameter, and different treatments for the total head, the universal solution can be reduced to the existing various Stokes solutions, thus explaining the reasons and the physical significance of different non-periodic terms in them, such as the positive or negative constant term in the free surface expression and the time-or space-proportional term in the potential function. 展开更多
关键词 universal Stokes wave solution uniform current global perturbation parameter SET-UP non-periodic terms
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Inequalities Relative to Vilenkin-Like System
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作者 ZHANC Xue Ying ZHANC Chuan Zhou 《Journal of Mathematical Research and Exposition》 CSCD 2009年第3期463-470,共8页
For bounded Vilenkin-Like system, the inequality is also true:(∑ k=1 ^∞ kp-2|f^^(k)|^p)^1/p ≤ C||f||Hp, 0 〈 p ≤ 2, where f^^(·) denotes the Vilenkin-Like Fourier coefficient of f and the Hardy s... For bounded Vilenkin-Like system, the inequality is also true:(∑ k=1 ^∞ kp-2|f^^(k)|^p)^1/p ≤ C||f||Hp, 0 〈 p ≤ 2, where f^^(·) denotes the Vilenkin-Like Fourier coefficient of f and the Hardy space Hp(Gm) is defined by means of maximal functions. As a consequence, we prove the strong convergence theorem for bounded Vilenkin-Like Fourier series, i.e., (∑ k=1 ^∞ k^p-2||Skf||p^p)^1/p≤C||f||Hp,0〈p〈1. 展开更多
关键词 Hardy space Vilenkin-Like systems strong convergence.
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