共变系数

It has been deduced that the search direction remains the same but that the step length decreases in optimizing the improved cost function with the conjugate gradient algorithm from the gradient of the cost function that the FIR filter apporaches the contrary point spread function more, and that the estimated image is closer to the original one.

从代价函数的梯度入手推导出共轭梯度算法，其搜索方向保持不变而搜索步长变小，使滤波系数更加逼近于点扩展函数逆算子，从而使估计图像与原始图像更加接近。

Nano- and Micro-Hardness Testers（Nano Indentor/Micro Indentor）- Quantitative measurement of mechanical surface properties: elastic modulus and hardness - Analysis of fracture modes, cracking,… Nano- and Micro-Scratch Testers - Adhesion and anti-scratch properties of coatings and films - Profilometry Tribometers - High Temperature, Vacuum and Nano Tribology - Wear and Friction studies Calotest / Calowear - Coating thickness measurement - Wear rate testing 3D Imaging - Atomic Force Microscope - Confocal Microscope

动态压痕测试仪器为您提供纳米或微米尺度下材料的硬度、弹性模量、蠕变、断裂韧性等性质。我们还为您提供纳米级、微米级摩擦磨损测试仪器，用以测量材料的摩擦系数和磨损率。我们的球磨仪器是测量薄膜厚度最简单准确的工具。我们同时提供光学显微镜、原子力显微镜、白光共焦显微镜成像工具。我们在瑞士的分析测试中心随时准备为您提供高质量测试服务。

In the ***, all types and fundamental principles of Radon transform are summarized systematacially. This *** starts from the general linear Radon transform, and then researches how to use the damped least square method to find the solution of the forward transform. However, the least squares smoothing effect will lead to a certain degree of trails in the data of Radon domain, which led to the application\'s limitations. After that the implementation in Radon domain and relative merits of linear Radon transform, parabolic Radon transform and polynomial Radon transform which have time invariance are introduced, the conjugate gradient method that can solve numerical solution is also given. And then the high resolution Randon transform is discussed, it introduces the regularization theory and Bayes principle into inversion, which successfully remove the negative affect caused by discrete Radon transform. Finally, we introduce the optimal weighting similar coefficient Radon transform, which adapt to the time variant quality of hyperbolic Radon transform.

本文系统总结了Radon变换的各种类型及其基本原理，从τ- p变换(即一般线性Radon变换)出发，研究利用阻尼最小二乘平方法求解其正变换，但是最小平方法的平滑作用会导致Radon域数据存在一定程度的拖尾效应，给这种方法的应用带来了很大的局限性；然后先容了具有时不变性的线性、抛物和多项式Radon变换在频率域的实现及其优缺点，给出了求解其数值解的共轭梯度算法；接着讨论了高分辨率Radon变换，它把正则化思想和贝叶斯原理引进到了反演中，很好的克服了离散Radon变换产生的截断效应对结果的不利影响；最后先容了适应双曲Radon变换时变性质的高分辨率最优相似系数加权Radon变换。

The plastic deformation induced due to cyclic rotation of principal stress axes alone can be in the same magnitude as that due to shear with fixed principal stress axes. 2 The volumetric strain due to shearing of cyclic rotation of principal stress axes is found to be composed of a reversible dilatancy component and an irreversible dilatancy component. The former is characterized by its reversibility and is independent of past shear history, the latter by its irreversibility increases with the increase of cycle number yet its increase rate decreases with its accumulation. 3 The obvious non-coaxiality between directions of the principal stresses and principal strain increments is found and its degree depends largely on the change of shear stress component. 4 The intermediate principal stress has considerable effects on the deformation behavior of sands in the condition of cyclic rotation of principal stress axes. The accumulation rate of the irreversible dilatancy component increases with the increase of the intermediate principal stress parameter.

具有初始各向异性的砂土在纯应力主轴循环旋转排水条件下的主要变形规律为：①纯应力主轴循环旋转可产生与应力主轴固定单调剪切处于同一数量级的塑性变形；②纯应力主轴循环旋转引起的剪切体变包含可逆性剪切体变分量和不可逆性剪切体变分量两部分，其中可逆性剪切体变分量在一周内可完全恢复，基本与应力历史无关；不可逆性剪切体变分量随循环周数的增加呈单调增加，且增加速率随其自身累积值的增大呈减小趋势；③应变增量主轴与应力主轴之间的非共轴现象显著，且在一周内具有分段性；④中主应力对应力主轴循环旋转条件下砂土的变形特性有重要影响，不可逆性剪切体变分量的累积速率随中主应力系数的增加而增加。

Multiple linear regression is the simplest way to build the relationship between the several explanatory variables and response variable. However, MLR often causes the estimated regression coefficients unstable or even unaccessible when the number of explanatory variables is more than that of objects. Especially, the explanatory variables are highly intercorrelated which called multi-collinear data. Therefore, many methods have been developed to analyze multi-collinear data, such as variable selection methods, ridge regression, principal components regression and partial least squares regression.

当要同时建立多个解释变数与反应变数间的关系时，最简单的方式是以复回归来处理，但是当解释变数数目远多於样本数，或者变数之间具有高度相关性时，会使得回归系数的估计变得不稳定甚至无法求得，这样的资料又称为共线性资料，在面临这样的资料时可以利用变数选取的方式降低资料组的维度，或者以脊回归、主成分回归及净最小平方回归等方法来灭种共线性的干扰。

An application of conjugate gradient method to fit concrete creep coefficient is in good agreement with experimental results. 4. There are 8 CFST members bearing capacity tests with different initial stress factor and eccentric distances having been launched. 5. A generalized analysis program which could be considered steel tube initial stress influence of CFST arch bridge is developed. The correct and accuracy of the program were verified by the experimental results of the axis, eccentric compression initial stress CFST member and a model of CFST arch bridge.

应用共轭斜量法拟合混凝土徐变系数，拟合结果与试验值吻合良好； 4、开展了8根不同初应力系数和偏心距的钢管混凝土初应力构件承载力试验； 5、编制了钢管混凝土拱桥考虑钢管初应力影响的综合分析程序，程序得到轴心受压、偏心受压初应力试验构件和模型拱桥的验证。

Breath, muscle contraction of the buttocks; arch body, as far as possible to hold his head, right leg straight towards the ceiling (peg-leg knee in order to avoid muscle tension).

呼气，收缩臀部肌肉；拱起身体，尽量抬起头来，右腿伸直朝向天花板（膝微屈，以避免肌肉紧张）。

The cost of moving grain food products was unchanged from May, but year over year are up 8%.

粮食产品的运输费用与5月份相比没有变化，但却比去年同期高8％。