偏心偶极子漂移速率的计算与分析

本文根据国际地磁参考场模型ＤＧＲＦ１９４５－１９８５、ＩＧＲＦ１９９０和ＳＶ１９９０－１９９５、计算近期偏心偶极位置和漂移速度,并对西向漂移速度进行了分析,结果表明,１９７０年以前,漂移速度是连续下降,到１９７０最低值,以后,又呈上升趋势,这一现象与地磁长期变化加速度的突然变化即“Ｊｅｒｋ”有很好的相关性。     

极座标测设法在桩基工程施工中的应用

本文阐述了极座标测设法的基本原理及其在桩基工程施工中延伸变形的应用。介绍了具体的注意事项。通过与直角座标测设法的对比，阐明了极座标测设法“精度高、速度快、可灵活操作”的优越性。     

Expression of strain and rotation tensor in geodetic coordinates

In this paper, unit moving trihedron is first constructed for a point on the surface of a revolution ellipsoid. Via translation, the origin of the trihedron coincides with that of Cartesian coordinates established at the center of the ellipsoid, and then through two coordinate rotations, the trihedron completely coincides with the Cartesian coordi-nates. Transformation formulae between the moving trihedron and unit Cartesian coordinate frameworks as well as transformation of point displacement between two unit coordinate frameworks are presented. Based on the above transformation formulae between two different coordinate frameworks, due to the fact that the displacement and moving trihedron of the point are both functions of the geodetic coordinates, components in the corresponding axis for differential of displacement vector and geodetic curves arc differential at the point in geodetic system can be obtained through complicated derivation. Displacement gradient matrix at the point in geodetic system is also given. Finally, expressions of strain and rotation tensor in geodetic coordinates are presented. Geometric meanings of the rotation tensor are explained in detail. The intrinsic relationship between strain tensors of sphere and ellip-soid are also discussed.     

极座标法放样公路中线的精度保证

本文根据全站仪的特点和极座标法放样的过程,利用极座标法放样的点位精度估算原理,对影响全站仪极座标法放放样公路中线精度的因素进行了分析,提出保证精度的措施。     

怎样读三角形座标图

最近南昌石京秀等读者来信，要求介绍怎样读三角形座标国(见下国)，现请赵滢介绍如下。     

Flow-Induced Vibration of A Nonlinearly Restrained Curved Pipe Conveying Fluid

Investigated in this study is the flow-induced vibration of a nonlinearly restrained curved pipe conveying fluid. The nonlinear equation of motion is derived by equilibrium of forces on microelement of the system under consideration. The spatial coordinate of the system is discretized by DQM (differential quadrature method). On the basis of the boundary conditions, the dynamic equation is solved by the Newton-Raphson iteration method. The numerical solutions reveal several complex dynamic motions for the variation of the fluid velocity parameter, such as limit cycle motion, buckling and so on. The result obtained also shows that the sub parameter regions corresponding to the several motions may change with the variation of some parameters of the curved pipe. The present study supplies a new reference for investigating the nonlinear dynamic response of some other structures.     

用红外测距仪测设曲线点

由于“偏角法”（又称极座标法）不受地形限制，所以它是野外测设曲线点的一种常用方法。但是这种方法，曲线点是由弦长C和一定偏角值的视准轴交会而得，所以测设时比较麻烦，尤其在地势起伏较大的地区更是不便。本方法是安置红外光测距仪（例如DI-3S）在曲线起点，根据偏角值和曲线起点到各曲线点的水平距离，直接测定各曲线点位置，因此使测量方法简便。     

直,曲道路相交处交点座标与里程桩号计算

在道路施工中，常会遇到直线怀曲线或曲线与曲线型道路在某处相交。本文运用线方程求解交点和坐标和里程桩号，它具有解算方便、误差小、精度高、成果可靠等优点，完全能满足道路工程规划设计及施工放样的要求。     

An Impact Study of the Vertical Coordinate on a Non-hydrostatic Mesoscale High-Resolution Model

With the high-speed development of high-powered computer techniques, it is possible that a high-resolution and multi-scale unified numerical model is applied to the operational weather prediction. Some techniques about mesoscale non-hydrostatic numerical weather prediction are addressed, and the impact of the vertical coordinate system is one of them. Based on WRF (Weather Research and Forecasting) model, the influence of vertical coordinates on the non-hydrostatic mesoscale high-resolution model is compared. The results show that the error of various coordinates in lower levels is almost same when we use the geometry height (z) and the pressure (p) to set up a terrain-following coordinate; but the error of the height terrain-following coordinate in higher levels is smaller than that of the pressure terrain-following coordinate. The higher the resolution is, the bigger the error will be. The results of the high-resolution simulation exhibited that the trend of the difference in the two coordinates existed. In addition, the correlative coefficient and standard error are also analysed by the comparison between the forecast fields and the corresponding analysis fields.