滚动轴承内外圈滚道的磁力研磨研究

采用直流励磁装置、磁性磨料及工件共同构成磁加工系统。磁性磨料在磁场的作用下，对轴承内、外圈滚道以磁刷的形式进行研磨。由于磨料的可流动性，加工时既能满足对被加工表面粗糙度的加工要求，又能较好地保持工件原有的形位精度；且加工后在被加工表面形成一定的压应力，使工件的抗疲劳强度提高，使用寿命延长。     

嵩山地区新构造运动研究

根据几年来对嵩山地区的考察和研究 ,通过对夷平面、河流阶地、串珠状洪积扇等诸多地貌现象的分析 ,论述了嵩山地区新构造运动以间歇性抬升运动和掀斜运动为主的特征。     

Grain-size related nitrogen distribution in southern Yellow Sea surface sediments

Forty-eight surface sediments of the southern Yellow Sea are separated into three grain-size fractions. Four forms of extractable nitrogen (nitrogen in ion-exchangeable form (Nie), nitrogen in weak-acid extractable form (Nwa), nitrogen in strong-alkali extractable form (Nsa) and nitrogen in strong-oxidant form (N50))are obtained by the sequential extraction. The results show that the contents and the distributions of the extractable nitrogen in the southern Yellow Sea surface sediments are closely related to sediment grain size. The distributions ofNie, Nso and total nitrogen (TN) present positive correlations with fine particles content, while Nwa and Nsa does not have such correlation. The net contents of all the forms of nitrogen increase with sediment grain size finer.     

Derivation of planetary topography using multi-image shape-from-shading

In many cases, the derivation of high-resolution digital terrain models (DTMs) from planetary surfaces using conventional digital image matching is a problem. The matching methods need at least one stereo pair of images with sufficient texture. However, many space missions provide only a few stereo images and planetary surfaces often possess insufficient texture.This paper describes a method for the generation of high-resolution DTMs from planetary surfaces, which has the potential to overcome the described problem. The suggested method, developed by our group, is based on shape-from-shading using an arbitrary number of digital optical images, and is termed “multi-image shape-from-shading” (MI-SFS). The paper contains an explanation of the theory of MI-SFS, followed by a presentation of current results, which were obtained using images from NASA's lunar mission Clementine, and constitute the first practical application with our method using extraterrestrial imagery. The lunar surface is reconstructed under the assumption of different kinds of reflectance models (e.g. Lommel-Seeliger and Lambert). The represented results show that the derivation of a high-resolution DTM of real digital planetary images by means of MI-SFS is feasible.     

Homoclinic and heteroclinic orbits in the photogravitational restricted three-body problem

We study numerically the asymptotic homoclinic and heteroclinic orbits around the hyperbolic Lyapunov periodic orbits which emanate from Euler's critical points L ₁ and L ₂, in the photogravitational restricted plane circular three-body problem. The invariant stable-unstable manifolds associated to these Lyapunov orbits, are also presented. Poincaré surface of sections of these manifolds on appropriate planes and several homoclinic and heteroclinic orbits for the gravitational case as well as for varying radiation factor q ₁, are displayed. Homoclinic-homoclinic and homoclinic-heteroclinic-homoclinic chains which link the interior with the exterior Hill's regions, are illustrated. We adopt the Sun-Jupiter system and assume that only the larger primary radiates. It is found that for small deviations of its value from the gravitational case (q ₁ = 1), the radiation pressure exerts a significant impact on the Hill's regions and on these asymptotic orbits.     

论地理科学体系建设

本文在论述重建地理科学体系必要性的基础上,提出和重点阐述一个新的地理科学体系的框架和内容,并由此分析我国未来地理科学学科建设的战略重点。     

A simple method using climatic variables to estimate canopy temperature,sensible and latent heat fluxes in a winter wheat field on the North China Plain

Estimation of evapotranspiration from a crop field is of great importance for detecting crop water status and proper irrigation scheduling. The Penman–Monteith equation is widely viewed as the best method to estimate evapotranspiration but it requires canopy resistance, which is very difficult to determine in practice. This paper presents a simple method simplified from the Penman–Monteith equation for estimating canopy temperature (T_c). The proposed method is a biophysically‐sound extended version of that proposed by Todorovic. The estimated canopy temperature is used to calculate sensible heat flux, and then latent heat flux is calculated as the residual of the surface energy balance. An eddy covariance (EC) system and an infrared thermometer (IRT) were installed in an irrigated winter wheat field on the North China Plain in 2004 and 2005, to measure T_c, and sensible and latent heat fluxes were used to test the modified Todorovic model (MTD). The results indicate that the original Todorovic model (TD) severely underestimates T_c and sensible heat flux, and hence severely overestimates the latent heat flux. However, the MTD model has good capability for estimating T_c, and gives acceptable results for latent heat flux at both half‐hourly and daily scales. The MTD model results also agreed well with the evapotranspiration calculated from the measured T_c. Copyright © 2008 John Wiley & Sons, Ltd.     

基于二次曲面的Shepard拟合法在GPS水准中的应用

针对GPS水准中常用拟合方法的不足,给出一种基于二次曲面的Shepard拟合法。通过某测区GPS水准实测数据,采用二次曲面拟合法、Shepard拟合法、多面函数法和基于二次曲面的Shepard拟合法对测区高程异常进行拟合,结果表明,基于二次曲面的Shepard拟合法计算得到的高程异常的精度和可靠性最高。     

无人机遥感真正射影像高精度制图

近年来无人机低空遥感技术不断发展,利用无人机影像生成的真正射影像（TDOM）在成图精度、制作流程方面仍有提高的空间。本文采用固定翼无人机和专业摄影相机采集影像,布设地面控制点,提出了利用运动恢复结构（SfM）和多视立体视觉（MVS）工作流来生成高精度数字表面模型（DSM）和数字正射影像（DOM）的方法;对遮蔽倾斜部分进行阴影检测、DSM修编和多视影像纹理补偿生成TDOM;最后用TDOM上随机分布的检查点进行精度检查,水平精度为3.3 cm,垂直精度为7.5 cm;消除了DOM中倾斜和阴影部分,使建筑物保持垂直视角,生成的满足1：500比例尺高精度并消除倾斜阴影的TDOM可用于农村宅基地确权、国土规划设计等领域。     

车载激光扫描数据分类支持下的路面数据提取

车载激光扫描系统可以快速采集道路及两旁的建筑物、植被、电杆等地物的点云数据,而点云数据的分类提取是车载激光扫描系统应用的关键。本文选用全景激光移动测量系统获取的激光点云数据,分析了路面点云数据的特征,采用渐进格网法进行了路面点云数据的提取研究;通过试验区的实例验证,取得了较好的分类效果。