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A surface mesh Movement Algorithm for Aerodynamic Optimization of the Nacelle Position on Wing-Body-Nacelle-Pylon Configuration

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Transactions of Nanjing University of Aeronautics and Astronautics 2016年第6期33卷 -页

作者： Gao Yisheng Wu Yizhao Xia Jian Tian Shuling College of Aerospace Engineering Nanjing University of Aeronautics and Astronautics

A surface mesh movement algorithm,combining surface mesh mapping with Delaunay graph mapping,is proposed for surface mesh movement involving complex intersections,like wing/pylon ***,surface mesh mapping is adopted for the movement of intersecting lines along the spanwise direction and the wing surface mesh,and then Delaunay graph mapping is utilized for the deformation of the pylon surface mesh,guaranteeing consistent and smooth surface ***,the corresponding surface sensitivity procedure is implemented for accurate and efficient calculation of the surface *** proposed surface mesh movement algorithm and the surface sensitivity procedure are integrated into a discrete adjoint-based optimization framework to optimize the nacelle position on the DLR-F6 wing-body-nacelle-pylon configuration for drag *** results demonstrate that the strong shock on the initial pylon surface is nearly eliminated and the optimal nacelle position can be obtained within less than ten iterations.

关键词： aerodynamic optimization aerodynamics aircraft surface mesh adjoint

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Characterization of a human brain cortical surface mesh using discrete curvature classification and digital elevation model

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Journal of Biomedical Science and Engineering 2012年第3期5卷 133-140页

作者： Kamel Aloui Amine Nait-Ali Mohamed Saber Naceur LiSSi EA LaboratoryUniversite Paris-Est Creteil(UPEC)CreteilFrance LTSIRS Laboratory National Engineering SchoolTunisTunisia

In this paper we present a novel approach for brain surfacec characterization based on convexity and concavity analysis of cortical surface mesh. Initially, volumetric Magnetic Resonance Images (MRI) data is processed to generate a discrete representation of cortical surface using low-level segmentation tools and Level-Sets method. Afterward, pipeline procedure for brain characterization/labeling is developed. The first characterization method is based on discrete curvature classification. This is consists on estimating curvature information at each vertex in the cortical surface mesh. The second method is based on transforming the brain surface mesh into Digital Elevation Model (DEM), where each vertex is designed by its space coordinates and geometric measures related to a reference surface. In other word, it consists on analyzing the cortical surface as a topological map or an elevation map where the ridge or crest lines represent cortical gyri and valley lines represents sulci. The experimental results have shown the importance of these characterization methods for the detection of significant details related to the cortical surface.

关键词： Brain Curvature DEN Level-Sets MRI Mapping surface mesh

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Automatic Extraction Method of 3D Feature Guidelines for Complex Cultural Relic surfaces Based on Point Cloud

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Journal of Geodesy and Geoinformation Science 2024年第1期7卷 16-41页

作者： GENG Yuxin ZHONG Ruofei HUANG Yuqin SUN Haili College of Resources Environment and Tourism Capital Normal UniversityBeijing 100048China Key Laboratory of 3-Dimensional Information Acquisition and Application Ministry of EducationBeijing 100048China Chinese Academy of Cultural Heritage Beijing 100029China

Cultural relics line graphic serves as a crucial form of traditional artifact information documentation,which is a simple and intuitive product with low cost of displaying compared with 3D *** reduction is undoubtedly necessary for line ***,most existing methods for artifact drawing rely on the principles of orthographic projection that always cannot avoid angle occlusion and data overlapping while the surface of cultural relics is ***,conformal mapping was introduced as a dimensionality reduction way to compensate for the limitation of orthographic *** on the given criteria for assessing surface complexity,this paper proposed a three-dimensional feature guideline extraction method for complex cultural relic surfaces.A 2D and 3D combined factor that measured the importance of points on describing surface features,vertex weight,was *** the selection threshold for feature guideline extraction was determined based on the differences between vertex weight and shape index *** feasibility and stability were verified through experiments conducted on real cultural relic surface *** demonstrated the ability of the method to address the challenges associated with the automatic generation of line drawings for complex *** extraction method and the obtained results will be useful for line graphic drawing,displaying and propaganda of cultural relics.

关键词： point cloud conformal parameterization vertex weight surface mesh cultural relics feature extraction

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Numerical Evaluation of Longitudinal Motions of Wigley Hulls Advancing in Waves by Using Bessho Form Translating-Pulsating Source Green's Function

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Journal of Ocean University of China 2016年第3期15卷 429-437页

作者： XIAO Wenbin DONG Wencai Academy of Ocean Science and Technology National University of Defense Technology Department of Naval Architecture Naval University of Engineering

In the framework of 3D potential flow theory, Bessho form translating-pulsating source Green's function in frequency domain is chosen as the integral kernel in this study and hybrid source-and-dipole distribution model of the boundary element method is applied to directly solve the velocity potential for advancing ship in regular waves. Numerical characteristics of the Green function show that the contribution of local-flow components to velocity potential is concentrated at the nearby source point area and the wave component dominates the magnitude of velocity potential in the far field. Two kinds of mathematical models, with or without local-flow components taken into account, are adopted to numerically calculate the longitudinal motions of Wigley hulls, which demonstrates the applicability of translating-pulsating source Green's function method for various ship forms. In addition, the mesh analysis of discrete surface is carried out from the perspective of ship-form characteristics. The study shows that the longitudinal motion results by the simplified model are somewhat greater than the experimental data in the resonant zone, and the model can be used as an effective tool to predict ship seakeeping properties. However, translating-pulsating source Green function method is only appropriate for the qualitative analysis of motion response in waves if the ship geometrical shape fails to satisfy the slender-body assumption.

关键词： translating-pulsating source local-flow component wave component longitudinal motions Wigley hulls surface mesh

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