玛丽亚别墅解析

通过实地考察、图解分析玛丽亚别墅,从时代背景、空间、几何特征、非标准化以及细部处理等方面对其进行深入剖析,以进一步丰富国内建筑师的设计思想与方法.     

Java3D在钢结构建模中的应用

Java3D是基于Java平台的、功能强大的面向对象的三维图形应用程序接口(API),它的设计是对目前流行的诸如OpenGL和Direct3D的3D图形API的重大革新。利用Java3D能使三维建模变得更加快捷和清晰。该文就如何应用Java3D建立三维钢结构模型进行了初步的探讨。     

海底集矿车的几何建模及运动的可视化

该文论述了OpenGL三维图形标准的操作和特点,及Delphi语言进行OpenGL程序开发的可能性。阐述了基于三维图形开发软件3DMAX建立海底集矿车几何模型的方法,分析了ASE文本数据的关于模型几何网格信息的存储格式,在基于Delphi浯言的OpenGL环境中实现了海底集矿车各部分几何模型数据的分别读取和重新绘制,再根据各部分相对位置进行移动和旋转组成整体模型。分析了海底集矿车运动的特点,利用OpenGL函数库提供的函数实现海底集矿车运动三维可视化的程序开发。     

通信车天线布局仿真设计模型的可视化研究

通信车天线布局仿真设计模型的可视化是几何建模、模型验证和电磁兼容分析的重要手段。该文提出了由面单元着色、面单元外法矢量显示、面单元及线单元编号显示构成的模型可视化的模式。针对面单元着色,提出了余数配色法;针对面单元外法矢量显示,推导出面单元质心、外法矢量方向、外法矢量终点三个要素的计算公式;针对单元编号的显示,提出了面单元及线单元编号显示的方法。实践表明,该文提出的方法具有满意的可视化效果并可推广应用于其他领域。     

基于扩展语义匹配的BIM和GIS三维建筑数据融合

目前,在BIM与GIS融合方面的研究主要分为三个方向,分别是数据格式转换、数据标准扩展和本体论。本项目选择通过本体论的模式进行IFC和CityGML的实体融合。首先,通过语义修正提取实体的三元组,用知识表示学习,将三元组表示为实体向量,将实体语义信息转换到低维向量空间,采取以扩展语义匹配为基础构建IFC和CityGML标准的匹配融合系统,解决在IFC和CityGML两个不同的标准下对同一实体的语义方面的理解偏差问题,并通过相似度计算进行聚类;其次,通过提取到的三元组,利用实体—关系—实体进行几何重构,将IFC标准的实体映射到CityGML标准的实体;最后,用建立的三维模型验证,实现了实体从BIM领域到GIS领域的转换。     

A topological derivative method for topology optimization

We propose a fictitious domain method for topology optimization in which a level set of the topological derivative field for the cost function identifies the boundary of the optimal design. We describe a fixed-point iteration scheme that implements this optimality criterion subject to a volumetric resource constraint. A smooth and consistent projection of the region bounded by the level set onto the fictitious analysis domain simplifies the response analysis and enhances the convergence of the optimization algorithm. Moreover, the projection supports the reintroduction of solid material in void regions, a critical requirement for robust topology optimization. We present several numerical examples that demonstrate compliance minimization of fixed-volume, linearly elastic structures.     

QuadriFlow: A Scalable and Robust Method for Quadrangulation

QuadriFlow is a scalable algorithm for generating quadrilateral surface meshes based on the Instant Field‐Aligned Meshes of Jakob et al. (ACM Trans. Graph. 34(6):189, 2015). We modify the original algorithm such that it efficiently produces meshes with many fewer singularities. Singularities in quadrilateral meshes cause problems for many applications, including parametrization and rendering with Catmull‐Clark subdivision surfaces. Singularities can rarely be entirely eliminated, but it is possible to keep their number small. Local optimization algorithms usually produce meshes with many singularities, whereas the best algorithms tend to require non‐local optimization, and therefore are slow. We propose an efficient method to minimize singularities by combining the Instant Meshes objective with a system of linear and quadratic constraints. These constraints are enforced by solving a global minimum‐cost network flow problem and local boolean satisfiability problems. We have verified the robustness and efficiency of our method on a subset of ShapeNet comprising 17,791 3D objects in the wild. Our evaluation shows that the quality of the quadrangulations generated by our method is as good as, if not better than, those from other methods, achieving about four times fewer singularities than Instant Meshes. Other algorithms that produce similarly few singularities are much slower; we take less than ten seconds to process each model. Our source code is publicly available.     

多通道小波在掌纹图象几何变换与消噪中的应用

提出了三通道小波变换的思路，解决了实际应用中获得的掌纹图象，由于采样问题而产生严重几何变形的校正问题，采用QMF的方法构造出多通道小波滤波器组，三通道小波分解后进行二插值重建对数字图象进行重采样，从而达到图象几何变换的目的，小波变换有分频的特性，在对图象进行几何变换处理的同时，也对采样效应引起的噪声（Morie条纹）进行了消除，掌纹图象经过处理后的效果令人满意，从而证明方案可行。     

Microclimatic modeling of the urban thermal environment of Singapore to mitigate urban heat island

This study investigates the urban heat island effect in Singapore and examines the key factors causing this effect. The possibilities of improving heat extraction rate by optimizing air flow in selected hot spots were explored. The effect of building geometry, façade materials and the location of air-conditioning condensers on the outdoor air temperature was explored using computational fluid dynamics (CFD) simulations. It was found that at very low wind speeds, the effect of façade materials and their colours was very significant and the temperature at the middle of a narrow canyon increased up to 2.5 °C with the façade material having lower albedo. It was also found that strategically placing a few high-rise towers will enhance the air flow inside the canyon thereby reducing the air temperature. Adopting an optimum H/W ratio for the canyons increased the velocity by up to 35% and reduced the corresponding temperature by up to 0.7 °C.