一阶

The first and second derivative plates of concave pressure build-up curve are presented in this paper.

本文提出了凹型压力恢复曲线的一阶导数图版和二阶导数图版。

Experimental results show the recognition rate of the method is 95%for a known expresser and 72% for a novel expresser. Aiming at the shortcomings of optical flow technique,two improved optical flow algorithms are presented.One way is to introduce forward and backword constraint eqution and Hessian matrix of optical flow equation is computed.The well- posedness of each point of local neighbourhood is examined and the weight of Lucas-Kanade's method is defined as the reciprocal of the conditioning number of its Hessian Matrix.

3针对传统光流法的缺点，分别提出了两种不同的改进方法：其一为引入前向-后向光流方程，计算其Hessian矩阵，把Hessian矩阵条件数的倒数作为Lucas-Kanade光流法的加权阵，可有效消除局部邻域中不可靠约束点，同时提高基本约束方程解的稳定性；其二为针对传统光流法只适用于刚体运动的特点，在扩展约束光流方程的基础上引入了div-curl样条函数作为扩展光流约束方程的附加约束条件，给出了一阶和二阶div-curl样条约束下光流的数值解。

When the contingency table is sparse, we replace it with the first- and second-order marginals and modify the test statistic.

而当列联表有稀少情形发生时，我们将用一阶和二阶边际来取代并且修正检定统计量。

The surface representation in discrete form and its differential computation are important issues in computer graphics and geometric design.

0引言一般来说，曲面的一阶微分量是指曲面的切平面方向和法向量，二阶微分量是指曲面的曲率等有关量·它们作为重要的曲面信息度量指标，在计算机图形学，机器人视觉和计算机辅助设计等领域发挥了重要的作用·传统的曲面是连续形式的参数曲面和隐式曲面，其微分量的计算已经有了较完备的方法·随着激光测距扫描等三维数据采样技术和硬件设备的长足进步，以及图形工业对任意拓扑结构光滑曲面造型的需求日益迫切，离散形式的曲面———细分曲面、网格曲面和点云曲面正在逐渐成为计算机图形学和几何设计领域的新宠·于是，对这种离散形式的曲面如何估

The paper showed the conception and species of the edge,and deeply explored the differential operator methods of first order and differential operator methods of second order.

通过介绍边缘的概念及种类，对传统的一阶微分方法和二阶微分方法进行了深入的探索，对各种微分方法的原理及过程，以及各种方法对图像的处理结果进行了对比分析，最后对遥感图像边缘提取方法所面临的问题和今后的发展方向表达了自己的观点。

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。

Since these merits, Dyn's four-point scheme is one of the classical subdivision schemes in CAGD.

本文讨论的是前者。1987年，Dyn提出了四点细分算法，它形式简单，最高具有四次收敛阶，并可以生成一阶连续的极限曲线，由于这些明显的优点，四点法成为CAGD中经典的细分算法。

Firstly, we give the geometric interpretation of the scheme.Secondly, we use the method developed in Dyn's original four-point paper to discuss the sufficient conditions for the limit curve to be C0,C1,C2 respectively.

首先给出了算法的几何意义，然后我们用Dyn在1987年发表的四点法中使用的办法，详细讨论了极限曲线连续，一阶连续，二阶连续的充分条件。

Chapter 2 is started from the basic theory of elastodynamics, the zero and the first order reflection and transmission coefficients of rough interface are derived in theory, and some numerical examples are given. Also dispersion characters of diffraction waves are discussed in the case of micro-rough interface in deep layers.

第二章从弹性动力学的基本理论出发，通过求解波动方程的定解问题，从理论上导出了地震波在粗糙界面上的零阶和一阶反射透射系数，并给出了数值算例；该章还讨论了深层微粗糙界面的绕射波的频散特征。

The relations of electrophoresis velocity, electroosmosis velocity and electric dispersion velocity are also investigated with these expressions. The results show that this new model offers a better explanation for peak compression effect on the migration behaviour of charged solute in CEC. The retention time will be shorter by peak compression effect, which is similar to a solvent gradients process. The peak compression effect is not steady, and doesn't appear until the conditions are fitted in some special situation.

基于弛豫理论所建立的基本模型，在考虑溶质在两相中皆有可能发生正、反向迁移的情况下，得到了流出曲线一阶原点矩和二阶中心矩的理论表达式，并通过对溶质在两相中电扩散速率与电泳速率、电渗流速率关系的分析结果证实：溶质在固定相表面的电扩散行为可以使其保留变弱，出峰加快；而这种电扩散导致的超常柱效峰的出现具有不稳定性，只有在多方面因素综合影响匹配的情况下才可能出现。

We have no common name for a mime of Sophron or Xenarchus and a Socratic Conversation; and we should still be without one even if the imitation in the two instances were in trimeters or elegiacs or some other kind of verse--though it is the way with people to tack on 'poet' to the name of a metre, and talk of elegiac-poets and epic-poets, thinking that they call them poets not by reason of the imitative nature of their work, but indiscriminately by reason of the metre they write in.

索夫农 、森那库斯和苏格拉底式的对话采用的模仿没有一个公共的名称；三音步诗、挽歌体或其他类型的诗的模仿也没有——人们把&诗人&这一名词和格律名称结合到一起，称之为挽歌体诗人或者史诗诗人，他们被称为诗人，似乎只是因为遵守格律写作，而非他们作品的模仿本质。

The relationship between communicative competence and grammar teaching should be that of the ends and the means.

交际能力和语法的关系应该是目标与途径的关系。