双焊缝方矩形钢管生产工艺介绍

介绍了双焊缝方矩形钢管生产技术的特点及冷弯等边槽钢孔型设计参数.通过双焊缝方矩形钢管用冷弯等边槽钢的孔型设计、生产,实现了大截面双焊缝方、矩形钢管的生产,满足了客户的需求.     

Cubic Bézier approximation of a digitized curve

In this paper we present an efficient technique for piecewise cubic Bézier approximation of digitized curve. An adaptive breakpoint detection method divides a digital curve into a number of segments and each segment is approximated by a cubic Bézier curve so that the approximation error is minimized. Initial approximated Bézier control points for each of the segments are obtained by interpolation technique i.e. by the reverse recursion of De Castaljau's algorithm. Two methods, two-dimensional logarithmic search algorithm (TDLSA) and an evolutionary search algorithm (ESA), are introduced to find the best-fit Bézier control points from the approximate interpolated control points. ESA based refinement is proved to be better experimentally. Experimental results show that Bézier approximation of a digitized curve is much more accurate and uses less number of points compared to other approximation techniques.     

Discrete quadratic curvature energies

We present a family of discrete isometric bending models (IBMs) for triangulated surfaces in 3-space. These models are derived from an axiomatic treatment of discrete Laplace operators, using these operators to obtain linear models for discrete mean curvature from which bending energies are assembled. Under the assumption of isometric surface deformations we show that these energies are quadratic in surface positions. The corresponding linear energy gradients and constant energy Hessians constitute an efficient model for computing bending forces and their derivatives, enabling fast time-integration of cloth dynamics with a two- to three-fold net speedup over existing nonlinear methods, and near-interactive rates for Willmore smoothing of large meshes.     

On methods of defuzzification of parametrically represented fuzzy numbers

A comparative analysis of such methods of defuzzification of fuzzy numbers as WABL (Weighted Averaging Based on Levels), centroid, and mean of maxima (MOM) is presented in the study. Analytic formulas are presented for calculating the defuzzification values for parametrically represented fuzzy numbers of triangular and trapezoidal form.     

方格网法在城市公共绿地建设规划中的应用

阐述了方格网法的含义及特点,探讨了该法的应用领域和要点,认为它在城市绿地系统规划和近期绿地建设规划中可有效指导公共绿地进行均衡布局,并分析了广州市在近期绿地建设规划中运用该法的具体实践案例,以进一步完善和论证该法的应用。     

用最小二乘法恢复逐行倒相副载波

介绍ＰＡＬ制彩色全电视信号中色同步信号编码原理及恢复逐行倒相副载波的过程中，两种计算色同步信号相位角的方法。并且在实验的基础上得出：最小二乘法在ＰＡＬ制电视信号的副载波相位角计算中不仅可以满足精度要求，而且简便灵活。     

橡胶挤出机平均温差分析与计算

从理论上推导挤出机平均温差的计算公式，并指出与一般换热器平均温差计算的异同。     

高精度合成地震记录制作技术研究

制作高精度的合成地震记录是精细储层描述的基础，本文在分析合成地震记录原理的基础上，从地震剖面的极性判断、平均速度的选取，反射系数的准确提取，子波的精确估算等方面对制作合成记录的要点进行了分析，通过提高以上四方面的精度，提高了制作合成地震记录的精度，并提出了一套可行的合成地震记录的检查方法。