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geometric modeling of Holocene large-river delta growth patterns,as constrained by environmental settings

Science China Earth Sciences 2021年第2期64卷 318-328页

作者： Gaocong LI Qiong XIA Yaping WANG Zhiqiang LI Shu GAO Department of Marine Technology Guangdong Ocean UniversityZhanjiang 524088China Southern Marine Science and Engineering Guangdong Laboratory(Zhuhai) Zhuhai 519000China Marine Resources Big Data Center of South China Sea Southern Marine Science and Engineering Guangdong Laboratory(Zhanjiang)(Zhanjiang Bay Laboratory)Zhanjiang 524088China State Key Laboratory for Estuarine and Coastal Research East China Normal UniversityShanghai 200046China

Topographic/bathymetric conditions of the continental shelf can significantly influence the long-term growth of river *** particular,these conditions constrain the accommodation space for sedimentation in the deltaic *** this study,we use a conceptual geometric model to evaluate the role played by this factor,on the basis of the principle of mass *** Ganges-Brahmaputra,Mekong and Nile deltas are examined as three typical examples,in terms of their different original seabed *** control variate method is applied to eliminate the effect of the difference in model input *** results show that,assuming a constant sediment load,the delta growth rate will decrease with time;a higher value of the original seabed slope leads to a lower shoreline progradation rate for the subaerial delta and a higher growth rate for the subaqueous ***,the original seabed morphology represented by slope is a critical factor affecting the evolution of Holocene large-river *** results explain the interrelationships between sediment load,deltaic plain area,and the original seabed slopes for the 27 large-river deltas worldwide,located in the middle/low latitudes,with different tectonic *** the future,the conceptual geometric model may be combined with sediment dynamic modeling to identify more details of the evolution of these deltas.

关键词： Large-river deltas Original topography/bathymetry geometric modeling Growth geometry Holocene

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geometric modeling of underground ferromagnetic pipelines for magnetic dipole reconstruction-based magnetic anomaly detection

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Petroleum 2020年第2期6卷 189-197页

作者： Dandan Zhao Zhiyong Guo Jian Du Zhongxiang Liu Wei Xu Gaofei Liu School of Mechatronic Engineering Southwest Petroleum UniversityChengdu610500China China Petroleum Pipeline Insptection Technologies Co. LtdLangfang065000China

To aid the magnetic anomaly detection(MAD)of underground ferromagnetic pipelines,this paper proposes a geometric modeling method based on the magnetic dipole reconstruction method(MDRM).First,the numerical modeling of basic pipe components such as straight sections,bends and elbows,and tee joints are discussed and the relevant mathematical formulations for these components are ***,after analyzing the function of MDRM and various element division strategies,the sectional division and blocked division methods are introduced and applied to the appropriate pipeline components to determine the volume and center coordinates of each element,establishing the general models for the three typical pipeline components *** resulting volume and center coordinates of each component are the fundamental parameters for determining the MAD forwarding of underground ferromagnetic pipelines using the ***,based on the combination and transformation of the basic pipeline components considered,the visualized geometric models of typical pipeline layouts including parallel pipelines,pipelines with elbows,and a pipeline with a tee joint are *** results demonstrate the feasibility of the proposed method of geometric modeling for the MDRM,which can be further applied to the finite element modeling of these and other components when analyzing MAD ***,the models with output parameters proposed in this paper establish a foundation for the inversion of MAD.

关键词： Magnetic anomaly detection Magnetic dipole reconstruction Segmentation method Pipeline detection geometric modeling

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Derivative geometric modeling of Basic Rotational Solids on CATIA

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Computer Aided Drafting,Design and Manufacturing 2011年第1期21卷 22-27页

作者： MENG Xiang-bao PAN Zi-jian ZHU Yu-xiang LI Jun College of Mechanical Science and Engineering Jilin University Changchun 130025 China

Hybrid models derived from rotational solids like cylinders, cones and spheres were implemented on CATIA software. Firstly, make the isosceles triangular prism, cuboid, cylinder, cone, sphere, and the prism with tangent conic and curved triangle ends, the cuboid with tangent cylindrical and curved rectangle ends, the cylinder with tangent spherical and curved circular ends as the basic Boolean deference units to the primary cylinders, cones and spheres on symmetrical and some critical geometric conditions, forming a series of variant solid models. Secondly, make the deference units above as the basic union units to the main cylinders, cones, and spheres accordingly, forming another set of solid models. Thirdly, make the tangent ends of union units into oblique conic, cylindrical, or with revolved triangular pyramid, quarterly cylinder and annulus ends on sketch based features to the main cylinders, cones, and spheres repeatedly, thus forming still another set of solid models. It is expected that these derivative models be beneficial both in the structure design, hybrid modeling, and finite element analysis of engineering components and in comprehensive training of spatial configuration of engineering graphics.

关键词： geometric modeling derivative solids of revolution industrial and conceptualdesign engineering graphics CATIA application

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3D indoor scene modeling from RGB-D data:a survey

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Computational Visual Media 2015年第4期1卷 267-278页

作者： Kang Chen Yu-Kun Lai Shi-Min Hu Tsinghua University Cardiff University

3D scene modeling has long been a fundamental problem in computer graphics and computer vision. With the popularity of consumer-level RGB-D cameras,there is a growing interest in digitizing real-world indoor 3D scenes. However,modeling indoor3 D scenes remains a challenging problem because of the complex structure of interior objects and poor quality of RGB-D data acquired by consumer-level *** methods have been proposed to tackle these challenges. In this survey,we provide an overview of recent advances in indoor scene modeling techniques,as well as public datasets and code libraries which can facilitate experiments and evaluation.

关键词： RGB-D camera 3D indoor scenes geometric modeling semantic modeling survey

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Software development for modeling irregular fine protrusions formed by sputter etching

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Visual Computing for Industry,Biomedicine,and Art 2020年第1期3卷 96-103页

作者： Sande Gao Keijiro Nakasa Loulin Huang Department of Mechanical Engineering School of Science and EngineeringMeisei University2-1-1HodokuboHino-shiTokyo 191-8506Japan High-Tech Research Center Hiroshima Kokusai Gakuin UniversityHiroshima 739-0321Japan School of Engineering Auckland University of TechnologyAuckland 1142New Zealand

Irregular fine protrusions formed on the surface of a mechanical part through biomimetic technology can enhance the part’s properties,including tribology,self-cleaning,and light ***,underlying principles for the formation of fine protrusions according to the requirements of their shapes,sizes,and material distributions have not been studied *** paper presents the software development for modeling irregular fine protrusions,which is essential for the simulation,experimentation,and analysis of fine protrusions formed by sputter etching.

关键词： geometric modeling Hermite surface Fine protrusions Software development

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Loop Subdivision Surface Based Progressive Interpolation

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Journal of Computer Science & Technology 2009年第1期24卷 39-46页

作者： Fu-Hua (Prank) Cheng Feng-Tao Fan Shu-Hua Lai Cong-Lin Huang Jia-Xi Wang 雍俊海 Department of Computer Science University of Kentucky Lexington KY 40506 U.S.A. Department of Mathematics and Computer Science Virginia State University Petersburg VA 23806 U.S.A. School of Software Tsinghua University Beijing 100084 China

A new method for constructing interpolating Loop subdivision surfaces is presented. The new method is an extension of the progressive interpolation technique for B-splines. Given a triangular mesh M, the idea is to iteratively upgrade the vertices of M to generate a new control mesh M such that limit surface of M would interpolate M. It can be shown that the iterative process is convergent for Loop subdivision surfaces. Hence, the method is well-defined. The new method has the advantages of both a local method and a global method, i.e., it can handle meshes of any size and any topology while generating smooth interpolating subdivision surfaces that faithfully resemble the shape of the given meshes. The meshes considered here can be open or closed.

关键词： geometric modeling Loop subdivision surface progressive interpolation

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The Differential Equation Algorithm for General Deformed Swept Volumes

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Journal of Computer Science & Technology 2000年第6期15卷 604-610页

作者：汪国平华宣积孙家广 DepartmentofComputerScienceandTechnology PekinUniversityBeijing100871P.R.China

The differential equation approach for characterizing swept volume boundaries is extended to include objects experiencing deformation. For deformed swept volume, it is found that the structure and algorithm of sweep-envelope differential equation (SEDE) are similar between the deformed and the rigid swept volumes. The efficiency of SEDE approach for deformed swept volume is proved with an example.

关键词： CAD geometric modeling sweeping motion deformation swept volume

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Ablation and geometry change study of solid armature in a railgun

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Chinese Physics B 2013年第8期22卷 410-415页

作者：张亚东阮江军胡元潮龚若涵文武 School of Electrical Engineering Wuhan University

Armature plays an important role in the electromagnetic launch process. Due to the skin effect, the current density distribution is neither uniform on the rail, nor on the armature. High current density centralization in one part could lead to a partial high temperature and make the armature material melt down and be ablated, especially at low velocity. In this paper we try to change the geometry of a Cshaped armature to improve the current density distribution and reduce the ablation. Four variants of C-shaped armatures are designed to study the specific features, including a conventional C-shaped armature （CCA）, a rounded leading edge C-shaped armature （LCA）, a rounded trailing edge C-shaped armature （TCA）, and a rounded incorporate edge C-shaped armature （ICA）. A novel low-speed experiment is constructed and tested. The armatures are ablated and recovered to compare the improved effects. Then finite element simulations according to the experimental results are performed to further analyze the experimental results. It is proved that the current density and hence the temperature distribution can be immensely improved by simply changing the armature geometry. LCA and ICA show that the erosion is more uniform on the contact surface due to the rounded leading edge. The curved trailing edge could improve the uniformity of the current on the interface. ICA which combinesthe effects of LCA and TCA is the best option in the four armatures. How much the leading edge and the trailing edge should be curved involves the geometry of CCA and the posture of the interface on the rail. A saddle shape is a good option to improve the current density and temperature distribution in the throat. Erosion mechanism is analyzed finally. The experiments and simulations support the erosion and transition mechanism. A detailed description of the experiments and simulations is also presented in this paper.

关键词： railgun ablation friction geometric modeling

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Simultaneous structure and geometry detail completion based on interactive user sketches

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Science China(Information Sciences) 2012年第5期55卷 1123-1137页

作者： YANG Shen 1,QI Yue 1 & QIN Hong 2 1 State Key Laboratory of Virtual Reality Technology and Systems,Beihang University,Beijing 100191,China 2 Department of Computer Science,State University of New York at Stony Brook,Stony Brook,New York 11794-4400,USA State Key Laboratory of Virtual Reality Technology and Systems Beihang University Beijing China Department of Computer Science State University of New York at Stony Brook Stony Brook New York USA

We articulate a novel approach to geometric model completion via interactive sketches in this ***,the initial incomplete model (with holes) is decomposed into a base model and a high-frequency component,which represents global rough shape and geometric details,*** then repair the base model via smooth hole-filling,and compute the geometry detail image using high frequency *** novel element of our approach is that we allow users to interactively sketch a few structural curves that span across hole regions,with a goal to repair both local geometric details and global *** the help of local parameterization,we convert detailed geometry into gradient-domain images which can propagate along user-specified *** integrating recovered gradient-domain images and base shape,we can generate a complete model that faithfully recovers both global structure and local *** salient contribution of this paper is the unified approach for user interaction,global structure,and geometry details towards high-fidelity model *** demonstrate our new approach using a number of examples that exhibit salient global structure as well as local geometry details.

关键词： model repair geometric modeling interactive sketch 3D graphics

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Lp shape deformation

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Science China(Information Sciences) 2012年第5期55卷 983-993页

作者： GAO Lin1,ZHANG GuoXin 1 & LAI YuKun 2 1 Department of Computer Science and Technology,Tsinghua University,Beijing 100084,China 2 School of Computer Science and Informatics,Cardiff University,Wales CF24 3AA,UK Department of Computer Science and Technology Tsinghua University Beijing China School of Computer Science and Informatics Cardiff University Wales UK

Shape deformation is a fundamental tool in geometric *** methods consider preserving local details by minimizing some energy functional measuring local distortions in the L 2 *** strategy distributes distortions quite uniformly to all the vertices and penalizes ***,there is no unique answer for a natural deformation as it depends on the nature of the *** by recent sparse signal reconstruction work with non L 2 norm,we introduce general L p norms to shape deformation;the positive parameter p provides the user with a flexible control over the distribution of unavoidable *** with the traditional L 2 norm,using smaller p,distortions tend to be distributed to a sparse set of vertices,typically in feature regions,thus making most areas less distorted and structures better *** the other hand,using larger p tends to distribute distortions more evenly across the whole *** flexibility is often desirable as it mimics objects made up with different *** specifying varying p over the shape,more flexible control can be *** demonstrate the effectiveness of the proposed algorithm with various examples.

关键词： shape deformation Lp norm geometric modeling

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