基于弹性网格混合特征的脱机手写维文识别

手写体维文识别技术的关键在于特征提取方法的选择。为探求一种可靠性高、可分性强的脱机手写维文特征提取方法,在分析现有方法的基础上,结合维吾尔文字词自身的特点,提出一种在局部特征上基于弹性网格区域笔划密度、方向分解特征,在全局特征上提取交叉点、环、弧形笔划、附加笔划、外围轮廓特征的混合特征提取方法。通过在IFN/ENIT标准数据库及自采样数据集的聚类分析实验,识别正确率分别达到85%、84.3%。结果表明,方法综合统计特征和结构特征提取的优点,具有较强的抗扰能力,可分性优于GSC法。     

汽车发动机冷却风扇仿真方法对比

对比多参考坐标系(Multiple Reference Frame,MRF)模型和滑移网格模型(Sliding Mesh Model,SMM)在分析中的差异,分别应用FLUENT中的三维N-S方程和RNG湍流模型,对发动机冷却风扇的静止和旋转区域进行数值模拟,得到流道内空气的质量流量及风扇叶片表面的压力和速度矢量分布.SMM的结果更接近真实结果;根据SMM得出的结果说明MRF模型在工程领域的应用.     

注射成型流动模拟技术的发展

介绍了塑料成型过程中注射成型流动模拟技术的三个发展阶段,并分析了三种不同网格模型的特点。     

Inverse Procedural Modelling of Trees

Procedural tree models have been popular in computer graphics for their ability to generate a variety of output trees from a set of input parameters and to simulate plant interaction with the environment for a realistic placement of trees in virtual scenes. However, defining such models and their parameters is a difficult task. We propose an inverse modelling approach for stochastic trees that takes polygonal tree models as input and estimates the parameters of a procedural model so that it produces trees similar to the input. Our framework is based on a novel parametric model for tree generation and uses Monte Carlo Markov Chains to find the optimal set of parameters. We demonstrate our approach on a variety of input models obtained from different sources, such as interactive modelling systems, reconstructed scans of real trees and developmental models.     

Variational Tree Synthesis

Modelling trees according to desired shapes is important for many applications. Despite numerous methods having been proposed in tree modelling, it is still a non‐trivial task and challenging. In this paper, we present a new variational computing approach for generating realistic trees in specific shapes. Instead of directly modelling trees from symbolic rules, we formulate the tree modelling as an optimization process, in which a variational cost function is iteratively minimized. This cost function measures the difference between the guidance shape and the target tree crown. In addition, to faithfully capture the branch structure of trees, several botanical factors, including the minimum total branches volume and spatial branches patterns, are considered in the optimization to guide the tree modelling process. We demonstrate that our approach is applicable to generate trees with different shapes, from interactive design and complex polygonal meshes.     

A Projective Framework for Polyhedral Mesh Modelling

We present a novel framework for polyhedral mesh editing with face‐based projective maps that preserves planarity by definition. Such meshes are essential in the field of architectural design and rationalization. By using homogeneous coordinates to describe vertices, we can parametrize the entire shape space of planar‐preserving deformations with bilinear equations. The generality of this space allows for polyhedral geometric processing methods to be conducted with ease. We demonstrate its usefulness in planar‐quadrilateral mesh subdivision, a resulting multi‐resolution editing algorithm, and novel shape‐space exploration with prescribed transformations. Furthermore, we show that our shape space is a discretization of a continuous space of conjugate‐preserving projective transformation fields on surfaces. Our shape space directly addresses planar‐quad meshes, on which we put a focus, and we further show that our framework naturally extends to meshes with faces of more than four vertices as well.     

A study of PtRuO2 catalysts thermally formed on titanium mesh for methanol oxidation

Platinum-based catalysts, for the electro-oxidation of methanol, have been made by thermal decomposition of chloride precursors onto titanium mesh. The catalysed electrodes were successfully operated in acidic methanol electrolytes. Electrochemical characterisation has been carried out using cyclic voltammetry, electrochemical impedance spectroscopy and galvanostatic polarisations. A complete analysis of the electrochemical results showed that the preliminary performance of the catalysed titanium mesh was comparable to that achieved with carbon-supported PtRu catalysts. The catalysts formed on titanium mesh by thermal decomposition also exhibited dimensional stability. Catalysed titanium mesh therefore appears to be a promising alternative to carbon-supported catalysts for certain fuel cell applications.     

金属丝网载体气液色谱分离过程的研究

采用金属丝网填料作为固定相的载体,构建了制备气液色谱装置,并采用提前气化这种新进样方式。通过对二元共沸物正丙醇-水的分离考察了所构建制备气液色谱装置的分离过程。实验结果表明,采用金属丝网填料作为制备气液色谱固定相的载体是完全可行的;提前气化进样方式具有易于实现大进样量的优点。     

优化变形能的平面多边形同构剖分

平面多边形间的同构三角剖分是平面形状渐进过渡与插值的基础,降低对应三角形的变形程度是获得高质量应用的关键.文中提出一种基于变形能优化的2个平面多边形的同构剖分算法,其中包含同构剖分生成和变形能最小化2个模块.首先根据用户指定的对应特征点对多边形进行顶点重采样,得到顶点一一对应的2个多边形;然后利用带约束的Delaunay剖分对其中的一个多边形进行三角化,得到源网格;再用重心坐标将源网格的内部顶点嵌入到另一个多边形得到同构剖分(目标网格);最后逐一检查三角形的变形能,对源网格中变形能超过阈值的三角形进行细分,用同构剖分模块生成新的目标网格.实验及数据统计分析表明,该算法可以得到较好的同构三角剖分,提升网格质量,并能很好地避免纹理细节失真.     

基于STL文件的Laplacian网格优化算法

针对直接重构得到且以STL文件格式存储的网格模型质量不高的问题, 提出了一种基于Laplacian坐标的网格模型全局优化算法。该算法在提高三角面片质量的同时可以很好地保持原网格模型的局部几何特征, 其核心思想是通过在最小二乘意义下求解由权重控制的包含顶点位置和拉普拉斯坐标双重约束的线性系统来对网格顶点进行重新定位。从实验结果可以看出, 该算法较以往的Lapacian优化算法在对网格细节特征的保持上有一定优势。