Automatic medical image segmentation based on gradient vector flow 结合对心脏序列图像的分割
Detection of motion - target based on improved gradient vector flow snake model 基于改进梯度向量流形变模型的动目标检测方法
We discuss several different definitions of directional derivative and gradient vector 摘要讨论了几种不同的方向导数和梯度的定义。
The gradient vector can be used to construct the initial errors 这时可以对梯度向量本身进行分析,或者用这个梯度向量构造初始误差场。
Adjoint method provides an efficient tool to calculate the gradient vector of the cost function to the initial field 利用伴随方法,可以求出该度量函数关于初始场的梯度向量。
Therefore the gvf ( gradient vector field ) is used to substitute the traditional potential field and it overcomes the defects of the traditional active contour 于是,我们采用一种梯度向量流场作为外力,从而有效地克服了传统势能场的弱点,给曲线的移动以很好的指向。
When using modem optimization methods , the gradient vector information of the target function is not necessary , so there is much flexible in solving complex optimization problems 使用现代优化技术时不需要目标函数的梯度向量,因此在解决复杂优化问题时有更大的灵活性。
2 . study the working principle of the vector transducer , mainly for two - dimensional pressure - gradient transducer . and the experimental results for directional pattern of two - dimensional pressure - gradient vector transducer at frequency 3khz and 5khz are given 重点对本文所要研究的压差式矢量水听器进行研究,并运用消声水池实测数据绘出了二维压差式矢量水听器在3khz和5khz下的指向性图。
To corner feature , both gradient magnitude change and direction change of gradient vector are discontinuity in a local image neighborhood , hence gradient - direction variation and gradient magnitude are used as another decision rule of the corner detection to improve antinoise 为了提高抗噪声,根据角特征不仅灰度变化是不连续的,且相对周围其他点的梯度方向也是不连续的,提出利用梯度角变化和梯度幅值作为角特征检测的另一个准则。
There are two methods to optimize the parameters and structures of neuro - fuzzy networks : one is the differential coefficient optimization method based on gradient vector ; the other is based on modern optimization methods , such as genetic methods , simulated annealing etc , in which , the researches on genetic methods are most prominent 目前,对模糊神经网络的权值或结构进行优化的方法有两类:一类是基于梯度向量的导数优化方法;第二类方法是基于现代最优化技术的非导数优化方法,如遗传算法、模拟退火算法等,其中以遗传算法的研究最为突出。