乒乓球的动态特性——旋转与速度相对原理

乒乓球的旋转与速度存在着相对关系,是乒乓球技术中的普遍规律。在论证中提出了相对速度与球心速度之比作为特征准数,将点的运动轨迹分为三类,分别为“螺旋线”“波纹线”和“旋轮线”。从而将复杂的乒乓球技术划分为“旋转型”“速度型”和“综合型”三种基本类型。运动员击球的点在第二轨迹不同的位置上合成速度不相等。因此,运动员在第二轨迹的不同阶段击球手感旋转不相同,而且该点的合成速度矢量决守乒乓球技术的打法特征。根据高吊弧圈球与前冲弧圈球的特征准数不同,说明了运动员对这两种球型接球手感旋转不同的原因。

Two New Multi-component BKP Hierarchies

We firstly propose two kinds of new multi-component BKP （mcBKP） hierarchy based on the eigenfunction symmetry reduction and nonstandard reduction, respectively. The first one contains two types of BKP equation with self-consistent sources whose Lax representations are presented. The two mcBKP hierarchies both admit reductions to the k-constrained BKP hierarchy and to integrable （1＋1）-dimensional hierarchy with self-consistent sources, which include two types of SK equation with self-consistent sources and of hi-directional SK equations with self-consistent

The Non-standard Characteristics of Functional SpacesK(X) and C_0(X)

In this paper,the non standard characteristics of functional spaces K(X) and C 0(X) are presented and proved.

Asymptotic analysis of mode Ⅰ propagating crack-tip field in a creeping material

Adopting an elastic-viscoplastic, the asymptotic problem of mode I propagat ing crack-tip field is investigated. Various asymptotic solutions resulting from the analysis of crack growing programs are presented. The analysis results show that the quasi-statically growing crack solutions are the special case of the dynamic propagating solutions. Therefore these two asymptotic solutions can be unified.

Investigations of 3D Surface Roughness Characteristic＇s Accuracy

The existing surface roughness standards comprise only two dimensions. However, the real roughness of the surface is 3D （three-dimensional）. Roughness parameters of the 3D surface are also important in analyzing the mechanics of contact surfaces. Problems of mechanics of contact surfaces are related to accuracy of 3D surface roughness characteristic. One of the most important factors for 3D characteristics determination is the number of data points per x and y axes. With number of data points we understand its number in cut-off length. Number of data points have substantial influence on the accuracy of measurement results, measuring time and size of output data file （especially along the y-axis direction, where number of data points are number of parallel profiles）. Number of data points must be optimal. Small number of data points lead to incorrect results and increase distribution amplitude, but too large number of data points do not enlarge range of fundamental information, but substantially increase measuring time. Therefore, we must find optimal number of data points per each surface processing method.

Pattern characteristics in patients with primary liver cancer in different clinical stages

OBJECTIVE： To explore the characteristics of prima- ry liver cancer in terms of Traditional Chinese Medi-cine （TCM） by analyzing the variations of the patterns along with the clinical stages. METHODS： The patients who were hospitalized in the Changhai Hospital of Traditional Chinese Medi- cine dated from March 1999 to December 2008 were included in this retrospective study. The patients were grouped according to their cancer stag- es, and their patterns were judged and quantified according to the ＂Standard diagnosis and quantitative criteria of the common patterns in primary liv-er cancer＂ formulated by the Changhai Hospital of Traditional Chinese Medicine. Statistics methods included ANOVA and nonparametric test, among others.RESULTS： The data of the 398 newly diagnosed patients showed that Qi Stagnation, Blood Stasis, and Dampness patterns were more frequent than the other basic patterns with relatively high scores; patterns of Liver Qi Stagnation, Liver Blood Stasis, and Dampness Heat were more than the other complex patterns and scored relatively high. Scores of Dampness and Liver Qi Stagnation patterns varied among the groups at different stages and the differences were statistically significant （PDampeness= 0.002, PLiver Qi Stagnation ： 0.020）. The highest scores of Damp- ness pattern and Liver Qi Stagnation pattern corresponded with Stage Ⅲ b, and Stage Ⅲ a, respectively. Dampness pattern frequency was higher （P = 0.001） in the Stage Ⅲb group than in other groups.CONCLUSION： Pattern characteristics in patients with primary liver cancer of different clinical stages might manifest in the variations of the Dampness pattern along the process of the disease and the major pathogenic factor of primary liver cancer might be Dampness.

ON QUASI-TORAL RESTRICTED LIE ALGEBRAS

This paper gives some su?cient conditions for the commutativity of quasi-toral restricted Lie algebras and characterizes some properties on semisimple quasi-toral restricted Lie algebras.

Conformally flat Lorentzian hypersurfaces in R_1~4 with three distinct principal curvatures

A three dimensional Lorentzian hypersurface x : M_1~3→ R_1~4 is called conformally flat if its induced metric is conformal to the flat Lorentzian metric, and this property is preserved under the conformal transformation of R_1~4. Using the projective light-cone model, for those whose shape operators have three distinct real eigenvalues, we calculate the integrability conditions by constructing a scalar conformal invariant and a canonical moving frame in this paper. Similar to the Riemannian case, these hypersurfaces can be determined by the solutions to some system of partial differential equations.

Fractal characteristics of far-field diffraction patterns for two-dimensional Thue-Morse quasicrystals

We report a numerical method to analyze the fractal characteristics of far-field diffraction patterns for two-dimensional Thue-Morse (2-D TM) structures. The far-field diffraction patterns of the 2-D TM structures can be obtained by the numerical method, and they have a good agreement with the experimental ones. The analysis shows that the fractal characteristics of far-field diffraction patterns for the 2-D TM structures are determined by the inflation rule, which have potential applications in the design of optical diffraction devices.