中心导数

Though comparing Canny operator and center B spline dyadic wavelet, the following conclusion is proven in this dissertation: a Center B spline function has tight support and Canny operator hasn't. b Center B spline function asymptotic convergence to Gaussian function and the derivative of Center B spline function asymptotic convergence to Canny operator. c The derivative of fourth order center spline B function is more suitable as a optimal edge detector than Canny operator. d Center B spline function can balance the smoothing and approximation of original data, and the fourth center B spline function is the only optimal solution of two order smoothing problem. e The error between the valve of time-frequency uncertainty of the fourth center B spline function and the lower bound of time-frequency uncertainty does not exceed 0.143% of the lower bound. f The derivative of center spline B function can construct a stability dyadic wavelet and can give a fast algorithm for multiscale edge detection, but Canny operator can do neither.

作者给出了Canny算子与中心B样条二进小波严格的比较证明，得出如下结论：a中心B样条函数具有紧支集，Canny算子不具有紧支集。b中心B样条函数的极限收敛于高斯函数，中心B样条函数的导数收敛于Canny算子。c四阶中心B样条函数的导数比Canny算子更接近最佳边缘检测滤波器。d中心B样条函数比高斯函数更能兼顾对原函数平滑和逼近的折中要求，并且四阶中心B样条函数是二阶逼近问题的唯一最优解。e四阶中心B样条函数的时频测不准关系值与时频测不准关系下界的逼近误差不超过0.143％。f中心B样条函数的导数可以构成稳定的二进小波，存在快速的多尺度算法；而Canny算子不构成稳定的二进小波，无法给出快速的多尺度算法。

Let be the center of Curvature at.

设已知曲线的方程是，且其二阶导数在点不为0，则曲线在对应点的曲率中心的坐标为

According to the some properties of the differentiation ,I found that the symmetry of the graph is closely related to the first-order differentiation and the second-order differentiation .from this ,I search for a way to identify the symmetry of the functional graph for the direct line or the central symmetry of the functional graph for the some dot .

摘 要：利用导数的一些性质，发现了函数图象的对称性与函数的一阶、二阶导数的密切关系。根据这些关系，找到了一种判定函数图象是否关于某一直线对称或关于某点成中心对称的方法。

This paper reveals the relationship between the parity of derivative function and the symmetry of the graph function, finding a effective way to judge whether the functional graph can have the axial symmetry or central symmetry.

揭示了函数导数的奇偶性与函数图像对称性的关系，发现了一种可以用来判定函数图像是否具有轴对称性或中心对称性的有效方法。

This model used the finite—difference approximation to the advection— dispersion equation. The spatial derivatives in the flow equation are approximated by central difference written about grid—block boundaries and time derivatives are approximated by a fully implicit backward scheme.

水流方程的空间导数采用中心差分格式离散，时间导数采用隐式差分格式离散，建立了土壤水分和污染物在各种饱和度的条件下迁移转化方程耦合求解的二维数值计算模型。

Then, using the second-order central difference to discretize the time derivative of the displacement, and applying the quadrature formula to the mass matrix, a fully discrete lumped mass Morley element method i...

然后利用中心差分格式离散时间方向的二阶导数，再利用适当的求积公式得到薄板弯曲问题的集中质量Morley元全离散格式。

An important property of the ROC of the globally optimized fusion system is obtained, that is, the slope of a curve in the ROC at a particular point can be used to determine the decision thresholds at fusion center and all the sensors required to achieve the detection and false alarm probabilities of that point.

5推导出了全局最优化融合系统工作特性曲线的一个重要性质，即根据融合系统检测概率对虚警概率的导数，可以确定使融合系统工作在该工作点所需的融合中心及各部传感器的判决门限。该性质是对单传感器检测系统ROC曲线性质的重要推广，从而丰富了检测融合理论的研究成果。

The fourth-derivative analysis was performed on the spectra to set up the uniform initial central wavelengths for excitation spectra of dinophyta and bacillariophyta,respectively,according to the position and number of maxima on the derivative spectra.

对其作四阶导数分析的基础上，根据导数光谱中出现的极大值位置和数量，对甲藻门和硅藻门的激发光谱分别设定统一的初始中心波长。

Good effect is obtained. The application of derivative sign binary algorithm in interference fringe skeletonizing overcomes the difficulty of threshold picking in ordinary binary methods.

导数符号二值图法在提取干涉条纹中心过程中的运用，克服了普通二值化方法中阈值难以选取的问题，提高了测量的精确度。

It has been put forward that there exists single Ball point and double Ball points on the symmetrical connecting-rod curves of equilateral mechanisms.

从鲍尔点的形成原理出发，分析对称连杆曲线上鲍尔点的产生条件，提出等边机构的对称连杆曲线上有单鲍尔点和双鲍尔点。

The factory affiliated to the Group primarily manufactures multiple-purpose pincers, baking kits, knives, scissors, kitchenware, gardening tools and beauty care kits as well as other hardware tools, the annual production value of which reaches US$ 30 million dollars.

集团所属工厂主要生产多用钳、烤具、刀具、剪刀、厨具、花园工具、美容套等五金产品，年生产总值3000万美元，产品价廉物美、选料上乘、质量保证，深受国内外客户的青睐