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在几何光学的透镜成像计算中，经常会遇到如下题目：例：已知凸透镜的焦距为ｆ，位于主轴上且垂直于主轴的物体ＡＢ从较远处沿主轴匀速地向透镜靠近，设物体的移动速度为ｖ物．当物体移动到离透镜距离为ｕ时，求像沿主轴方向的移动速度ｖ像．解法一、微元法设物距的微变化... 相似文献
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We present a novel helix slow wave structure with an elliptical cross section shielded by an elliptical waveguide. The rf characteristics including dispersion properties, interaction impedance of zero mode in this structure have been studied in detail. The theoretical results reveal that weaker dispersion even abnormal dispersion characteristics is obtained with the increasing eccentricity of the elliptical waveguide, while the interaction impedance is enhanced by enlarging the eccentricity of elliptical helix. 相似文献
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