隔气式磁流体水密封寿命的实验研究

磁流体旋转密封液体时,因磁流体与被密封液体界面存在稳定性问题,密封寿命较低。为提高其密封性能,设计了隔气式磁流体密封,避免磁流体与被密封液体直接接触,研究了该结构的密封原理,搭建了隔气式磁流体密封实验台,在该实验台上进行了磁流体密封水的耐压能力实验和密封寿命实验。理论与实验研究结果表明,隔气式磁流体密封结构对水的密封寿命明显延长,在各转轴转速下连续稳定工作120 h不泄漏,密封性能明显优于磁流体与被密封液体直接接触时的密封性能。     

基于单目视觉的同时定位与地图构建方法综述

增强现实是一种在现实场景中无缝地融入虚拟物体或信息的技术,能够比传统的文字、图像和视频等方式更高效、直观地呈现信息,有着非常广泛的应用.同时定位与地图构建作为增强现实的关键基础技术,可以用来在未知环境中定位自身方位并同时构建环境三维地图,从而保证叠加的虚拟物体与现实场景在几何上的一致性.文中首先简述基于视觉的同时定位与地图构建的基本原理;然后介绍几个代表性的基于单目视觉的同时定位与地图构建方法并做深入分析和比较;最后讨论近年来研究热点和发展趋势,并做总结和展望.     

VB下识别有机煤岩显微镜图片

在煤的有机岩石学中,镜下和照片中显微组分的识别是一件重要而又特别耗眼睛的工作。本文利用煤显微组分在镜下不同颜色显现的特点,用计算机VB编程对煤的三大显微组分进行灰度识别。     

Direct 3D Painting with a Metaball-Based Paint brush

1IntroductionComputertechnologyisnowchangingtheformandfunctionoftraditionalart.Oneinspiringaspectamongmostapplicationsinthefieldofartinvolvingcomputergraphicsisdigitalpainting.Aninteractivepaintsystemallowsanartisttoworkonasingleimage['].Whitteddescr...     

基于深度网格的大规模森林场景的动态模拟

为了降低大规模森林场景的数据量和较真实地模拟其在风力作用下的动态效果,提出一种完全基于GPU的森林场景动态模拟方法.首先采用一种基于深度图像并重建几何的方法对树模型进行优化,在优化后的模型中内建了多个层次细节,并进行有效的压缩;然后采用随机过程的方法对风场建模,用简化的过程式方法计算风力作用下树的位移和形变.实验结果表明,该方法可以实现以8 MB存储空间和85 MB显存空间为代价、实时模拟数量高达10万棵的大规模森林场景在风场作用下的动态效果,且模拟效果好、质量高.     

Precomputed Radiance Transfer Field for Rendering Interreflections in Dynamic Scenes

In this paper, we introduce a new representation – radiance transfer fields (RTF) – for rendering interreflections in dynamic scenes under low frequency illumination. The RTF describes the radiance transferred by an individual object to its surrounding space as a function of the incident radiance. An important property of RTF is its independence of the scene configuration, enabling interreflection computation in dynamic scenes. Secondly, RTFs naturally fit in with the rendering framework of precomputed shadow fields, incurring negligible cost to add interreflection effects. In addition, RTFs can be used to compute interreflections for both diffuse and glossy objects. We also show that RTF data can be highly compressed by clustered principal component analysis (CPCA), which not only reduces the memory cost but also accelerates rendering. Finally, we present some experimental results demonstrating our techniques.     

Shading with Curve Light Sources1

A new shading model for curve light sources is presented. It accounts for both diffuse reflection and specular reflection of the illuminated surface. By regarding a linear light source as a directional quadrilateral light source with very small width, a simple formula is derived first for calculating the diffuse reflection component due to the illumination of the linear segment. The diffuse reflection of the surface by direct illumination of a curve light source is then evaluated by approximating the curve light with a series of linear segments. The specular reflection component due to a curve light source is represented by an integration taking Phong's specular model as the kernel and evaluated by summing the contributions from the linear segments. Finally, an efficient shadow detection algorithm for curve light sources is proposed. The images rendered with the shading model are very photo-realistic.     

油气藏产量双曲线递减方程求解的新方法

基于对Ｊ．Ｊ．Ａｒｐｓ双曲线递减方程各种求解方法的研究分析，提出了一种新的联立方程求解法。该方法不受人为因素的影响，具有单一解的特点。同时，方法简单，方便，经实例验证，方法可靠有效。