Topology evolutions of silhouettes

We give the topology changing of the silhouette in 3D space while others study the projections in an image. Silhou- ettes play a crucial role in visualization, graphics and vision. This work focuses on the global behaviors of silhouettes, especially their topological evolutions, such as splitting, merging, appearing and disappearing. The dynamics of silhouettes are governed by the topology, the curvature of the surface, and the view point. In this paper, we work on a more theoretical level to give enu- merative properties of the silhouette including: the integration of signed geodesic curvature along a silhouette is equal to the view cone angle; in elliptic regions, no silhouette can be contained in another one; in hyperbolic regions, if a silhouette is homotopic to a point, then it has at least 4 cusps; finally, critical events can only happen when the view point is on the aspect surfaces (ruled surface of the asymptotic lines of parabolic points with surface itself). We also introduce a method to visualize the evolution of silhouettes, especially all the critical events where the topologies of the silhouettes change. The results have broad applications in computer vision for recognition, graphics for rendering and visualization.     

国人辽宁地区下颌磨牙的活体研究

本研究对238名(男110、女126)年令在18～43周岁,国人辽宁地区青、中年的下颌磨牙1062颗,其中第一磨牙(M_1)476颗,第二磨牙(M_2)476颗,第三磨牙(M_3)110颗进行了观测。测出下颌磨牙的牙尖数,面沟型及牙尖与淘组合型在各类磨牙的分布状志,取得了国人活体的各项数据。在讨论中。从国人活体牙各项数值与国内.外各有关数值进行了比较,得出活体牙与尸牙的异同及人种间的差异,并扼要地进行了解剖学及人类学的探讨。     

基于尖点突变模型的企业技术创新产生研究

技术创新对企业的发展有重要的推动作用,是企业获得核心竞争力的关键途径。在分析企业技术创新突变特性的基础上,构建企业技术创新产生过程的尖点突变分析模型,选取知识存量作为技术创新产生的状态变量,协同效应和研发投入力度作为控制变量,并应用尖点突变模型分析企业技术创新的产生过程。在分析的基础上,提出企业提高技术创新产生的策略,具有一定的理论与现实意义。