锦屏电站大坝右岸洞室开挖过程控制及对策

锦屏一级水电站大坝右岸地下洞室具有地质条件复杂、施工条件差、干扰因素多、难度大、工程量大、质量要求高、工期紧等诸多特点,因此施工过程控制极其重要。     

P~3中的Desargues对合定理

本文将射影平面上的Ｄｅｓａｒｇｕｅｓ对合定理推广到三维射影空间Ｐ３的完全四棱锥面与完全四面锥面中。     

A new heuristic algorithm for general integer linear programming problems

1 Introduction ? Since the cutting plane method [1] and branch-and- bound principle [2] were developed as two types of efficient approaches for integer linear programming problems, how to improve them or to find new algorithms more efficient has become an…     

改建公路的设计与施工

安阳地区近几年来公路改建中应注意平面、纵断面设计的问题以及主要的路基横断面型 式,同时根据改建公路老路面状况,老路补强的路面结构设计与施工的几种方法应当推广。     

Direct observation of nodeless superconductivity and phonon modes in electron-doped copper oxide Sr1−xNdxCuO2

The microscopic understanding of high-temperature superconductivity in cuprates has been hindered by the apparent complexity of crystal structures in these materials. We used scanning tunneling microscopy and spectroscopy to study the electron-doped copper oxide compound Sr_1−xNd_xCuO₂, which has only bare cations separating the CuO₂ planes and thus the simplest infinite-layer structure of all cuprate superconductors. Tunneling conductance spectra of the major CuO₂ planes in the superconducting state revealed direct evidence for a nodeless pairing gap, regardless of variation of its magnitude with the local doping of trivalent neodymium. Furthermore, three distinct bosonic modes are observed as multiple peak-dip-hump features outside the superconducting gaps and their respective energies depend little on the spatially varying gaps. As well as the bosonic modes, with energies identical to those of the external, bending and stretching phonons of copper oxides, our findings reveal the origin of the bosonic modes in lattice vibrations rather than spin excitations.     

复域上一类过极限环的积分流形的几何结构

本文以一类存在惟一极限的多项式自治系统(En)作为研究对象，用数值计算与定性分析相结合的方法，我们得到了复域上过极限环的积分流形在相空间中Riemann曲面的几何结构。     

线阵组合平面阵的指向性研究

利用Bridge乘积定理得到了线阵组合平面阵的指向性函数,并运用MATLAB软件绘制出该阵列的三维指向性图.借助于此图分析了线阵组合平面阵的指向性特点,以及声波的波长、阵列的尺寸对指向性的影响.该研究对线阵组合平面阵的设计提供了参考.     

对速度瞬心的动量矩定理及其应用

本文从动能定理出发论证了对速度瞬心的动量矩定理,并通过实例阐述了用它求解有瞬心的力学问题更简洁有效。     

A three-dimensional examination of the planar nature of the golf swing

Previous planar models of the downswing in golf have suggested that upper limb segments (left shoulder girdle and left arm) move in a consistent fixed plane and that the clubhead also moves only in this plane. This study sought to examine these assumptions. Three-dimensional kinematic analysis of seven right-handed golfers of various abilities (handicap 0?–?15) was used to define a plane (named the left-arm plane) containing the 7th cervical vertebra, left shoulder and left wrist. We found that the angles of this plane to the reference horizontal z axis and target line axis (parallel to the reference x axis) were not consistent. The angle to the horizontal z axis varied from a mean of 133° (s = 1°) at the start of the downswing to 102° (s = 4°) at impact, suggesting a “steepening” of the left-arm plane. The angle of the plane to the target line changed from ??9° (s = 16°) to 5° (s = 15°) during the same period, showing anticlockwise (from above) rotation, although there was large inter-individual variation. The distance of the clubhead from the left-arm plane was 0.019?m (s = 0.280?m) at the start at the downswing and 0.291?m (s = 0.077?m) at impact, showing that the clubhead did not lie in the same plane as the body segments. We conclude that the left arm and shoulder girdle do not move in a consistent plane throughout the downswing, and that the clubhead does not move in this plane. Previous models of the downswing in golf may therefore be incorrect, and more complex (but realistic) simulations should be performed.     

质点运动的描述

指出了绝对静止系，绝对匀速运动系，绝对加速运动系，惯性系，非惯性系并不存在，确定了相对静止系，相对匀速运动系，相对加速运动系的概念，用位于参照系中的线位置矢量，运动方程，运动轨道描述了质点的运动。