方向导数

In this paper, a new edge detection method——method using extremum of first directional derivative is proposed, based upon a general gradient edge model.

文中通过傅里叶变换，在频率域，通过求垂直于边缘的一阶方向导数，并检测其极值点来确定边缘。

Edge detection ; first directional derivative ; extremum ; Fourier transform

边缘检测；一阶方向导数；极值；傅里叶变换

By Code extraction method is to investigate the edge of each image pixel in a neighborhood Gray-scale changes in the region, using the edge of the neighboring first-order or second-order directional derivative Changes of a few simple ways to detect the edge.

经 典的边缘提取方法是考察图像的每个像素在某个邻域内灰度的变化，利用边缘邻近一阶或二阶方向导数变化规律，用简单的方法检测边缘。

We get theexistence theorem of directional derivative of convex fuzzy mapping, and discuss the relationsamong directional derivative, differential, gradient and subdifferential.

得到了这类模糊映射的凸映射的方向导数的存在性定理。

However, to establish global convergence for these latter methods, one must enforce either sufficient decrease conditions (the Armijo-Goldstein-Wolfe conditions)or a fraction of Cauchy decrease condition - all of which rely on explicit numerical function values, as well as explicit approximations to the directional derivative at the current iterate.

但是，为了保证后面方法的全局收敛，必须有足够的减少条件（Armijo-Goldstein-Wolfe条件）或者部分柯西减少条件——它们全都依赖于外在的数值函数值，就和在当前迭代逼近方向导数一样。

Using the directional derivative formula, the governing equation is discreted in the physical domain in which a nonorthogonal grid system is used. Two kinds of AF2 schemes, i. e. AF2-plane relaxation and full implicit AF2, for the TSD equation are proposed. Numerical results show that the full implicit AF2 scheme converges faster than AF2plane relaxation scheme. For the rectangular wing and swept wing, the results of the present method are compared with FP results, and the agreement is good.

采用适合于梯形机翼和后掠机翼的斜网格，利用方向导数公式直接在物理空间对主管方程进行离散；将近似因式分解方法应用于绕机翼的跨音速小扰动势流问题，提出AF2—面松弛和AF2全隐式两种迭代格式，并对它们的收敛速度进行比较，结果表明后者明显快于前者；直机翼和后掠机翼的算例表明，本文方法的结果与精确势流方法的结果吻合良好。

A algorithm of dim small targets detection in infrared image is proposed. Image is processed by using median filter and unsharp mask. The infrared image intensity surface is fitted by Haralickd discrete orthogonal polynomial basis function,and then the maximum points are detected on the fitted intensity surface by convolving the image with the second order directional derivative operators.

提出一种红外弱小多目标图像检测方法，图像先经过中值滤波、高提升滤波增强处理，再用基于Haralick离散正交多项式曲面拟合图像，拟合曲面的极大值点即目标点，可以利用导出的二阶方向导数算子与图像进行卷积得到。

In the differentiation step,directional derivatives in only two directions are necessary,when DD operators are used.

在分化阶段，只有两种情况需要用到方向导数。一种是使用DD设备是。

Based on the duality theorem of linear programming, the directional derivatives of the objective function can be expressed as a linear programming which is very important in the practical calculation for nonmono tone line search subproblems.

基于线性规划的对偶定理，目标函数的方向导数可以表示成线性规划问题，这在实际计算非单调线搜索子问题时是非常重要的。

In Chapter 6, based on discretization technique an implementable algorithm for nonconvex generalized semi-infinite minimax problems is presented and, utilizing properties of generalized quasi-directional derivative, its global convergence is proven under weak conditions.

对于广义极大极小问题，本文第六章在较弱的条件下，利用广义伪方向导数的性质，用离散化的技巧给出了非凸广义半无限极大极小问题的一种可实现的全局收敛算法。

He and Nina moved to California and lived at 2005 Ivar Street, Apt.

他和Nina搬到加州，并在2005年伊瓦尔街，公寓生活。

Droperidol （ potently inhibits transfected HERGchannels and this is the probable mechanism for QT prolongation.

氟哌利多有效地抑制了转染的 HERG 钾通道，可能是 QT 间期延长的机制。