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基于GVF Snake和边界跟踪的主动轮廓图像分割 被引量:4
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作者 蒋小波 梁久祯 周世兵 《济南大学学报(自然科学版)》 CAS 北大核心 2015年第4期269-274,共6页
梯度向量流蛇(GVF Snake)模型在处理图像分割问题上取得了较好的结果,但它对初始轮廓曲线的依赖程度较大且梯度向量场计算时间较长,故此提出一种基于GVF Snake模型和边界跟踪的轮廓提取图像分割算法。该算法利用边界跟踪算法进行粗糙的... 梯度向量流蛇(GVF Snake)模型在处理图像分割问题上取得了较好的结果,但它对初始轮廓曲线的依赖程度较大且梯度向量场计算时间较长,故此提出一种基于GVF Snake模型和边界跟踪的轮廓提取图像分割算法。该算法利用边界跟踪算法进行粗糙的分割,获取边缘位置有效信息点,经采样后生成一条初始轮廓线。同时,基于拉格朗日法求解梯度向量场的方法,提出一个距离终止条件以提高计算速度。实验结果表明,与GVF Snake、手动GVF Snake和CV活动轮廓算法相比,该算法有效提高了图像分割的自动化程度和分割精度。 展开更多
关键词 梯度向量流蛇模型 边界跟踪 初始化 梯度场计算 图像分割
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Photo-Detached Electron Flux Distribution in a Gradient Electric Field
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作者 王德华 唐田田 《Communications in Theoretical Physics》 SCIE CAS CSCD 2015年第5期591-598,共8页
This paper investigates the flux distributions of the electron photo-detached from Hion localized in a gradient electric field. In contrast with the photodetachment in the uniform electric field [Phys, Rev. A 40 (198... This paper investigates the flux distributions of the electron photo-detached from Hion localized in a gradient electric field. In contrast with the photodetachment in the uniform electric field [Phys, Rev. A 40 (1989) 4983], where only two electron trajectories interfere at each given point on a detector, for the photodetachment in a gradient electric field, the electrons waves can travel along multiple paths from the negative ion to a given point on the detector plane, which makes the electron flux distributions on the detector plane become much complex. Using the semi-classicaJ theory, we put forward a formula for calculating the electron flux. Our calculation results suggest that the electron flux distributions on a given detector plane is not only related to the propagation time of the detached electron, but also related to the detached electron's energy. With the increase of the detached electron's energy, the oscillating region in the electron flux distributions becomes enlarged and the oscillating structure in the flux distributions becomes much more complicated. This study will guide future experiment research on the photodetachment microscopy of the negative ions in the presence of non-uniform external fields. 展开更多
关键词 electron flux semi-classical theory gradient electric field
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