椭球膨胀法建立独立坐标系在公路工程中的应用

由于高斯-克吕格投影在海拔较高的地区投影变形问题,造成GPS测量的成果转换到国家统一的坐标系中不能直接应用于工程测量中,根据椭球膨胀法的原理,采用移动中央子午线和抬高投影面的方法,以减少投影变形的影响,并在内蒙古某黄河大桥中成功应用.应用这种方法不但能满足工程测量的要求,而且节省了人力财力,还提高了测量效率.     

基于椭球变形的植物果实造型

提出了一种适用于植物果实的造型方法。利用椭球曲面参数方程，根据植物果实的特征，对椭球面进行变形，以达到与实物相近的真实效果。重点分析了植物果实与椭球的关系，研究了对椭球面方程进行变形的数学模型。该方法简单直观，生成的图形真实感强，适用于虚拟植物果实的研究。     

水稻籽粒碰撞力学特性研究

根据水稻籽粒的物理特性建立了椭球体颗粒模型,采用离散元法模拟了籽粒与检测传感器碰撞力学过程.结果表明:对心碰撞时的峰值法向接触力Fn max随着曲率半径的增加而增大,偏心碰撞时籽粒将发生转动,Fn max随着法向重叠量的减小而减小;Fn max的差异随着粒径比γ的增加而增大,当y=3时峰值力比率η的最小值小于45％.斜碰撞时η的变化呈现出不对称特性,且η的变化范围也随之增大,当γ=3时η的最小值约为30％,接触力上升时间tr为14 ～ 26μs.采用PVDF压电薄膜作为敏感元件设计了检测传感器,并进行了水稻籽粒冲击力学试验.结果表明,在相同碰撞速度下,输出电压峰值在2～4V范围内波动,接触力上升时间tr为15～ 35 μs.     

家蚕第2长形卵的遗传学研究

在Ng系统中发现新的长形卵突变,其形态与长形卵(dp)相似,但更显细长。遗传分析结果:新的长形卵是由与dp独立遗传的隐性基因支配。定名为第2长形卵(ellipsoid egg2),基因记号dp-2。     

Measuring volume and density of a barley grain using ellipsoid approximation from a 2-D digital image

A digital imaging method was developed to determine the size, weight, volume and density of individual barley grains. Calibrations were developed using morphological measurements based on 2-D digital images, and were validated using a range of bulk barley samples.The validation of the grain diameter (minor) and grain weight algorithms gave high correlation coefficients (r = 0.93 and 0.97, respectively, P < 0.01), with low standard errors (0.09 mm and 1.37 mg, respectively) when compared to physical measurements.Estimated grain volume and density from image data, using three different mathematical approaches were compared: Model 1, a general ellipsoid; Model 2, a combination of two cone frustums with an ellipse top and base; and Model 3, a set of elliptical cylinders representing pixels along the image length. Derived grain volume data using Model 2 when compared to gas displacement volume measurements gave significant correlations (r = 0.97, P < 0.01) with the lowest standard error (0.97 mm³), in contrast to volume data estimated using Model 1 and Model 3. Even though Model 2 gave accurate and precise results for grain volume, Model 1 (with the slope adjusted) gave the highest correlation (r = 0.63, P < 0.01) with the lowest standard error (0.055 mg/mm³) for estimating grain density from image data, compared to gas displacement density measurements.