查询词典 gradient of scalar field

The choice of step-length strongly affects the convergence rate of the Gradient Method, the classical Gradient Method—the method of steepest descent converges rather slowly in most cases, the poor behavior of the method is due to the optimal choice of step-length.

步长的选取对梯度法的收敛速度影响非常大，经典的梯度法-最速下降法在大多数情况下收敛得相当慢的原因在于最优步长的选取。

The results of cloud image analysis show that the TBB is lower than 230K (-44℃) when the convection grows most prosperously and the area with the brightness temperature difference of lower than -4℃ corresponds to the place where is most affected by the strong thunderstorm. The center of low value with T≤-7℃ corresponds to the strong echo of radar. There is a good correspondence between the strong convective weather and maximum gradient of TBB, which distributes along the moving cloud cluster. The moving path of strong storm is similar to that of the maximum positive gradient of T.

FY-2C卫星云图定量分析结果表明这次飑线过程对流最旺盛期TBB低于230K(-44℃)；长波红外分裂窗双谱组合T≤-4的低值区与强风暴天气影响区域相对应，T≤-7低值中心与强雷达回波区相对应；强对流天气区域与分布在沿对流云团前进方向的TBB梯度最大区域有很好的对应关系，强风暴天气发生区的移动路径与T正梯度最大区域的移动路径相似。

Across the altitudinal gradient, a total of 12635 individuals belonging to 6 phyla, 15 classes and 33 orders were collected. With increasing altitude, the density of soil fauna decreased, but the group number was less affected. There was a higher co-occurrence of soil faunal communities along the altitudinal gradient, and Nematoda, Acarina, and Collembola were the dominant groups. Below the altitude 370 m, the Shannon-Wiener index, Pielou index, and Margalef abundance index increased with increasing altitude; while above the altitude 370 m, the Shannon-Wiener index and Pielou index decreased but the abundance index increased after an initial slight decrease.

结果表明：土壤动物密度随海拔升高而下降，类群数受海拔影响较小，各海拔群落的共有度较高，优势类群基本均为线虫、蜱螨目和弹尾目；Shannon-Wiener指数、Pielou均匀度指数及Margalef丰富度指数仅在海拔370 m以下随海拔升高而增加，而在海拔370 m以上，Shannon-Wiener指数与Pielou均匀度指数下降，丰富度指数在略有下降后再次上升。

In order to solve problem, this paper proposes the natural gradient algorithms with nonholomic constraints. We derive it by incorporating a nonholonomic constraint into the natural gradient learning algorithm.

章提出了不完整约束的自然梯度算法，该算法是由不完整约束条件与自然梯度算法的结合而推导出来的。

In the last part of this dissertation, we discuss how to model an image is discussed and how to segment an image by EDEK.Zero-Cross principle is a classical concept in signal processing. We generalize the concept to be zero normal curvature after the geometry frame built. Furthermore, we present the explanation to choose the dual parameters in SPMVIF. And we research why the Laplacian gradient superior to edge gradient.

梯度方向二阶导数过零原理是信号处理中的经典结论，在运用微分几何的知识建立SPMVIF的几何框架的同时，将这个结论推广到零-法曲率的形式；另外我们对SPMVIF的双参数选取规则进行了讨论并给出它们的几何意义，并且对SPMVIF中法向矢量选取时拉普拉斯梯度优于边缘图像梯度的结论给予统计信息熵的解释。

This spatial information is normalized gradient vector information instead of ordinary gradient information,and it can enhance the noise resistibility greatly during coarse registration.

文中利用的空间信息不同于一般的图像梯度信息，它是归一化的GVF矢量场信息，把它用于粗配准，抗噪性能良好。

It can be concluded that to meet with the ideal separation effect in a relative short period, the following optional selection of experimental conditions should be carried on strictly: centrifuge rotor and gradient medium, which will influence separation capability; gradient density range, shape and slope, which is very important in separation degree; the methods of reorienting rotor,low and high rotor speed exchange and Gmax could be used in order to shorten separating time.

通过研究认为在相对短的时间内要达到理想的分离效果，应该对以下实验条件进行优化选择并严格控制：包括实验中影响分离本领的转头、梯度介质选择；为获得满意分离度应严格选择梯度的密度范围、梯度形状以及梯度的斜率；为了缩短分离时间，可采用重定向梯度、二次变速及Gmax等方法。

The electrochemical analysis results show that the polarization potential of gradient coating was obviously lower than that of the non-gradient coating electrode.

电化学测试结果表明，与非梯度镀层相比，梯度镀层的极化电位在各电流密度条件下都显著低于非梯度镀层电极。

In this region, small holes around the existence of pressure gradient and temperature gradient.

在这个区域，小孔的周围存在压力梯度和温度梯度。

The projection gradient method will be a possible way to solve the problem that we just get. It has been shown that the projections of the every directions, of which is the boundary point in linear restraint problems, are the possible decent directions, and the projection of negative grads direction is a decent direction. In 1960, Rosen proposed the basic idea of projection gradient methods, and then lots of researchers have been tried to find the convergence of this method. But most of them get the convergence with the condition to amend the convergence itself.

在约束最优化问题的算法中怎样寻找有效的下降方向是构造算法的重要内容，在寻找下降方向方面可行方向法中的投影梯度法有效的解决了下降方向的寻找问题，利用线性约束问题边界点的任意方向在边界上的投影都是可行方向，而负梯度方向的投影就是一个下降方向。60年代初Rosen提出投影梯度法的基本思想，自从Rosen提出该方法以后，对它的收敛性问题不少人进行了研究，但一般都是对算法作出某些修正后才能证明其收敛的，直到最近对Rosen算法本身的收敛性的证明才予以解决。

62Mm prototype A-91 bullpup assault rifle, as made in mid-1990s.

7.62原型- 91无托步枪，如中提出，20世纪90年代。

A starfish is all arms and appetite; it has no brain, yet in spite of this, time-lapse photography has shown that the starfish maintains an active social life.

一只海星就只是手臂和食欲；它没有大脑，可尽管如此，慢速摄影却显示出海星维持了一种活跃的社交生活。