检索结果-内蒙古大学图书馆

Converting CSG models into meshed B-Rep models using Euler operators and propagation based marching cubes

JOURNAL OF THE BRAZILIAN SOCIETY OF MECHANICAL SCIENCES AND ENGINEERING 2007年第4期29卷 337-344页

作者： Tsuzuki, Marcos de Sales G. Takase, Fabio K. Garcia, Murilo Antonio S. Martins, Thiago de Castro Univ Sao Paulo Escola Politeccn Dept Mechatron & Mech Syst Engn BR-05508900 Sao Paulo Brazil

The purpose of this work is to define a new algorithm for converting a CSG representation into a B-Rep representation. Usually this conversion is done determining the union, intersection or difference from two B-Rep represented solids. Due to the lack of explicit representation of surface boundaries, CSG models must be converted into B-Rep solid models when a description based on polygonal mesh is required. A potential solution is to convert a CSG model into a voxel based volume representation and then construct a B-Rep solid model. This method is called CSG voxelization, conceptually it is a set membership classification problem with respect to the CSG object for all sampling points in a volume space. marching cubes algorithms create a simple mesh that is, enough for visualization purposes.. However, when engineering processes are involved, a solid model is necessary. A solid ensures that all triangles in the mesh are consistently oriented and define a closed surface. It is proposed in this work an algorithm for converting CSG models into triangulated solid models through propagation based marching cubes algorithm. Three main new concepts are used in the algorithm: open boundary, B-Rep/CSG Voxelization mapping and constructive triangulation of active cells. The triangle supplied by the marching cubes algorithm need not be coherently oriented;the algorithm itself finds, the correct orientation to the supplied triangles. The proposed algorithm restricts the exploration to the space occupied by the solids boundary. Differently from normal marching cubes algorithms that explore the complete sampled space.

关键词： solid model marching cubes algorithm triangular meshes

来源：评论

学校读者我要写书评

暂无评论

A marching cubes based failure surface propagation concept for three-dimensional finite elements with non-planar embedded strong discontinuities of higher-order kinematics

引用

INTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN ENGINEERING 2013年第6期96卷 339-372页

作者： Linder, Christian Zhang, Xiaoxuan Stanford Univ Dept Civil & Environm Engn Stanford CA 94305 USA

This paper presents an advanced failure surface propagation concept based on the marching cubes algorithm initially proposed in the field of computer graphics and applies it to the embedded finite element method. When modeling three-dimensional (3D) solids at failure, the propagation of the failure surface representing a crack or shear band should not exhibit a strong sensitivity to the details of the finite element discretization. This results in the need for a propagation of the discrete failure zone through the individual finite elements, which is possible for finite elements with embedded strong discontinuities. Whereas for two-dimensional calculations the failure zone propagation location is easily predicted by the maximal principal stress direction, more advanced strategies are needed to achieve a smooth failure surface in 3D simulations. An example for such method is the global tracking algorithm, which predicts the crack path by a scalar level set function computed on the basis of the solution of a simplified heat conduction like problem. Its prediction may though lead to various scenarios on how the failure surface may propagate through the individual finite elements. In particular, for a hexahedral eight-node finite element, 256 such cases exist. To capture all those possibilities, the marching cubes algorithm is combined with the global tracking algorithm and the finite elements with embedded strong discontinuities in this work. In addition, because many of the possible cases result in non-planar failure surfaces within a single finite element and because the local quantities used to describe the kinematics of the embedded strong discontinuities are physically meaningful in a strict sense only for planar failure surfaces, a remedy for such scenarios is proposed. Various 3D failure propagation simulations outline the performance of the proposed concept. Copyright (c) 2013 John Wiley & Sons, Ltd.

关键词： marching cubes algorithm finite elements strong discontinuities failure of solids

来源：评论

学校读者我要写书评

暂无评论

Three-dimensional finite elements with embedded strong discontinuities to model failure in electromechanical coupled materials

引用

COMPUTER METHODS IN APPLIED MECHANICS AND ENGINEERING 2014年第May.1期273卷 143-160页

作者： Linder, Christian Zhang, Xiaoxuan Stanford Univ Dept Civil & Environm Engn Stanford CA 94305 USA

This paper presents new finite elements with embedded strong discontinuities to model failure in three dimensional electromechanical coupled materials. Following the strong discontinuity approach for plane electromechanical problems, the coupled boundary value problem is decomposed into a continuous global part and into a discontinuous local part where strong discontinuities in the displacement field and electric potential are introduced. Those are incorporated into general three-dimensional brick finite elements through nine mechanical separation modes and three new electrical separation modes. All the local enhanced parameters related to those modes can be statically condensed out on the element level, yielding a computationally efficient framework to model failure in electromechanical coupled materials. Impermeable electric boundary conditions are assumed along the strong discontinuities. Their initiation and orientation is detected through a configurational force driven failure criterion. A marching cubes based crack propagation concept is used to obtain smooth failure surfaces in the three dimensional problems of interest. Several representative numerical simulations are included and compared with experimental results of failure in piezoelectric ceramics to outline the performance of the new finite elements. (C) 2014 Elsevier B.V. All rights reserved.

关键词： Failure in 3D solids Strong discontinuities Electromechanical coupling Piezoelectric ceramics Configurational forces marching cubes algorithm

来源：评论

学校读者我要写书评

暂无评论

Level set based shape optimization using trimmed hexahedral meshes

引用

COMPUTER METHODS IN APPLIED MECHANICS AND ENGINEERING 2019年 345卷 555-583页

作者： Nguyen, Son H. Kim, Hyun-Gyu Seoul Natl Univ Sci & Technol Dept Mech & Automot Engn 232 Gongneung Ro Seoul 01811 South Korea

This paper presents a new approach for level set based shape optimization using trimmed hexahedral meshes that geometrically conform to shape and topology changes during the optimization process. The marching cubes algorithm is employed to generate trimmed hexahedral meshes at each optimization iteration by splitting a regular background hexahedral mesh with the zero-isosurface of a level set function. A simple method is proposed to handle nonconforming polyhedral elements at the interface due to the face ambiguity arising in the marching cubes algorithm. The motion of the zero-isosurface of a level set function is obtained from the solution of the Hamilton-Jacobi transport equation using a normal velocity field defined on the regular background hexahedral mesh. Numerical results show that the present approach provides a natural and effective tool to solve shape optimization problems relying on explicitly discretized meshes of the shapes throughout the optimization process. (C) 2018 Elsevier B.V. All rights reserved.

关键词： Shape optimization Level set method marching cubes algorithm Trimmed hexahedral mesh Polyhedral elements

来源：评论

学校读者我要写书评

暂无评论

Stress -constrained shape and topology optimization with the level set method trimmed hexahedral meshes

引用

COMPUTER METHODS IN APPLIED MECHANICS AND ENGINEERING 2020年 366卷 113061-113061页

作者： Nguyen, Son H. Kim, Hyun-Gyu Seoul Natl Univ Sci & Technol Dept Mech & Automot Engn 232 Gongneung Ro Seoul 01811 South Korea Korea Maritime & Ocean Univ Div Mech Engn 727 Taejong Ro Busan 49112 South Korea

In this paper, we present a novel approach to solve stress-constrained shape and topology optimization problems based on the level set method using trimmed hexahedral meshes. A trimmed hexahedral mesh is generated at each optimization iteration by cutting a regular hexahedral background mesh with the zero-isosurface of a level set function to minimize a volume with stress constraints. A clear and explicit boundary-conforming mesh can be obtained by using trimmed hexahedral elements placed at the boundary of the solid domain, which leads to an accurate estimation of stresses and shape sensitivities. Since the void domain is not considered in the optimization process, the singularity phenomenon in stress-constrained optimization problems is essentially eliminated without using any relaxation technique. Numerical examples show that the proposed method is an efficient and effective approach to solve stress-constrained shape and topology optimization problems.

关键词： Stress constraints Shape and topology optimization Level set method marching cubes algorithm Trimmed hexahedral mesh

来源：评论

学校读者我要写书评

暂无评论

Mixed aleatory and epistemic uncertainty quantification using fuzzy set theory

引用

INTERNATIONAL JOURNAL OF APPROXIMATE REASONING 2015年 66卷 1-15页

作者： He, Yanyan Mirzargar, Mahsa Kirby, Robert M. Univ Utah Sci Comp & Imaging Inst Salt Lake City UT 84112 USA Univ Utah Sch Comp Salt Lake City UT 84112 USA

This paper proposes algorithms to construct fuzzy probabilities to represent or model the mixed aleatory and epistemic uncertainty in a limited-size ensemble. Specifically, we discuss the possible requirements for the fuzzy probabilities in order to model the mixed types of uncertainty, and propose algorithms to construct fuzzy probabilities for both independent and dependent datasets. The effectiveness of the proposed algorithms is demonstrated using one-dimensional and high-dimensional examples. After that, we apply the proposed uncertainty representation technique to isocontour extraction, and demonstrate its applicability using examples with both structured and unstructured meshes. (C) 2015 Elsevier Inc. All rights reserved.

关键词： Aleatory uncertainty Epistemic uncertainty Fuzzy set Uncertainty modeling marching cubes algorithm Isocontour extraction

来源：评论

学校读者我要写书评

暂无评论

GPU-based parallel construction of compact visual hull meshes

引用

VISUAL COMPUTER 2014年第2期30卷 201-211页

作者： Chang, Byungjoon Woo, Sangkyu Ihm, Insung Sogang Univ Dept Comp Sci & Engn Seoul South Korea

Building a visual hull model from multiple two-dimensional images provides an effective way of understanding the three-dimensional geometries inherent in the images. In this paper, we present a GPU accelerated algorithm for volumetric visual hull reconstruction that aims to harness the full compute power of the many-core processor. From a set of binary silhouette images with respective camera parameters, our parallel algorithm directly outputs the triangular mesh of the resulting visual hull in the indexed face set format for a compact mesh representation. Unlike previous approaches, the presented method extracts a smooth silhouette contour on the fly from each binary image, which markedly reduces the bumpy artifacts on the visual hull surface due to a simple binary in/out classification. In addition, it applies several optimization techniques that allow an efficient CUDA implementation. We also demonstrate that the compact mesh construction scheme can easily be modified for also producing a time- and space-efficient GPU implementation of the marching cubes algorithm.

关键词： Visual hull Volumetric approach Compact mesh GPU algorithm CUDA implementation marching cubes algorithm

来源：评论

学校读者我要写书评

暂无评论

marching cub es-base d isogeometric topology optimization method with parametric level set

引用

APPLIED MATHEMATICAL MODELLING 2022年 107卷 275-295页

作者： Zhou, Mian Xiao, Mi Zhang, Yan Gao, Jie Gao, Liang Huazhong Univ Sci & Technol State Key Lab Digital Mfg Equipment & Technol 1037 Luoyu Rd Wuhan 430074 Hubei Peoples R China Huazhong Univ Sci & Technol Sch Aerosp Engn Dept Engn Mech 1037 Luoyu Rd Wuhan 430074 Hubei Peoples R China Wuhan Univ Sci & Technol Key Lab Met Equipment & Control Technol Minist Educ Wuhan 430081 Peoples R China

The level set method can provide superior benefits for topology optimization problems because of its smooth and distinct description of structural boundaries. However, in this method, the elements cut by structural boundaries are not descripted accurately. This paper proposes a marching cubes-based isogeometric topology optimization method with the parametric level set to address this issue. In the proposed method, the marching cubes algorithm is applied in the framework of isogeometric analysis to clearly distinguish the structural boundaries, enabling the creation of an accurate material description model during topology optimization. The relaxed topology derivative (RTD) is introduced to measure the sensitivity of the Lagrange function and alleviate the dependence on the initial design in the level set method. Several 2D and 3D numerical examples for minimizing mean compliance problems are tested to illustrate the effectiveness of the proposed method, including a multi-patch structure with a complicated design domain.(c) 2022 Elsevier Inc. All rights reserved.

关键词： Topology optimization Isogeometric analysis marching cubes algorithm Parametric level set Relaxed topology derivative

来源：评论

学校读者我要写书评

暂无评论

An interdisciplinary approach to studying archaeological vase paintings using computed tomography combined with mineralogical and geochemical methods. A Corinthian alabastron by the Erlenmeyer Painter revisited

引用

JOURNAL OF CULTURAL HERITAGE 2018年 31卷 63-71页

作者： Karl, Stephan Kazimierski, Kamil S. Hauzenberger, Christoph A. Karl Franzens Univ Graz Inst Archaeol Univ Pl 3 A-8010 Graz Austria Karl Franzens Univ Graz Inst Math & Sci Comp NAWI Graz Heinrichstr 36 A-8010 Graz Austria Karl Franzens Univ Graz Inst Earth Sci Mineral & Petr NAWI Graz Univ Pl 2 A-8010 Graz Austria Dr Emperger Weg 14 A-8052 Graz Austria

This paper presents the results of an investigation of an unusual unpainted area in the Corinthian vase painting silhouettes painting technique during the Archaic Period (late 7th to 6th century BC). A painting of two panthers in the heraldic scheme done by the Erlenmeyer Painter on an alabastron contains a striking unpainted circular area inside the shoulder of one of the panthers. Since this feature cannot be explained by iconographical constraints, it has previously been referred to as an "opening". However, by combining X-ray methods, particularly computed tomography (CT) and related 3D surface renderings, with mineralogical and geochemical methods (SEM-EDS, XRD) and stylistic arguments, we have arrived at a new interpretation. The CT data revealed a feature directly beneath the unpainted circular area that was shaped like an angular plug and had similar structural properties and attenuation coefficients as the surrounding clay matrix. A visible inclusion on the surface of this alabastron was identified as a rock fragment, most likely sandstone or sandy shale, which suggests that a problematic large inclusion had been removed from the vessel and was subsequently filled with clay during the firm leather-hard stage. We argue that the painter intentionally deviated from the usual compositional form by leaving the area of the repair unpainted and adapting the drawing of the panther accordingly. One advantage of this method, particularly for vase collections, is that CT is a non-invasive technique that collects data from the entire ceramic body, which in combination with geoscience methods such as SEM-EDX and XRD allows for minimally invasive analysis that can strengthen the X-ray-based evaluation. Therefore, we contend that integrating CT data combined with mineralogical and geochemical data into pottery studies will open new avenues for the study of ancient vase painting, particularly for interpreting unpainted areas and other irregularities within black-glazed sil

关键词： Corinthian pottery Ancient vase painting Computed tomography marching cubes algorithm Manufacturing technique Erlenmeyer Painter

来源：评论

学校读者我要写书评

暂无评论

A comparative study of isodensity surfaces using ab initio and ASA density functions

引用

JOURNAL OF MOLECULAR GRAPHICS & MODELLING 1998年第4-6期16卷 190-196页

作者： Gironés, X Amat, L Carbó-Dorca, R Univ Girona Inst Computat Chem Girona 17071 Catalonia Spain

In this article, we report a visual comparison between several of the available methods for constructing electronic density functions. The density forms studied include ab initio, atomic shell approximation, and promolecular densities. A graphical comparison is made for six different molecules at different levels of density function values. The differences between the various density functions are analysed by considering a molecular quantum self-similarity measure and the required computational time for all molecules at all computation levels is considered. (C) 1999 by Elsevier Science Inc.

关键词： ab initio densities atomic shell approximation densities marching cubes algorithm promolecular densities molecular quantum similarity measures

来源：评论

学校读者我要写书评

暂无评论

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

请选择保存的检索档案：

请选择收藏分类：

通借通还

建议与咨询 留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

请选择保存的检索档案： 新增检索档案 确定 取消

请选择收藏分类： 新增自定义分类 确定 取消

通借通还

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

请选择保存的检索档案：

请选择收藏分类：