scholarly journals SUBDIVISION SURFACE MID-SURFACE RECONSTRUCTION OF TOPOLOGY OPTIMIZATION RESULTS AND THIN-WALLED SHAPES USING SURFACE SKELETONS

2021 ◽  
Vol 1 ◽  
pp. 2771-2780
Author(s):  
Martin Denk ◽  
Klemens Rother ◽  
Kristin Paetzold
Keyword(s):  
Topology Optimization ◽  
Laser Scanning ◽  
Parametric Representation ◽  
Subdivision Surfaces ◽  
Subdivision Surface ◽  
Shape Preserving ◽  
Distance Transformation ◽  
Surface Control ◽  
Different Types ◽  
Polygon Meshes

AbstractPolygon meshes and particularly triangulated meshes can be used to describe the shape of different types of geometry such as bicycles, bridges, or runways. In engineering, such polygon meshes can occur as finite element meshes, resulting from topology optimization or laser scanning. This article presents an automated parameterization of polygon meshes into a parametric representation using subdivision surfaces, especially in topology optimization. Therefore, we perform surface skeletonization on a volumetric grid supported by the Euclidian distance transformation and topology preserving and shape-preserving criterion. Based on that surface skeleton, an automated conversation into a Subdivision Surface Control grid is established. The final mid-surface-like parametrization is quite flexible and can be changed by variating the control gird or the local thickness.

scholarly journals EUCLIDIAN DISTANCE TRANSFORMATION, MAIN AXIS ROTATION AND NOISY DILITATION SUPPORTED CROSS-SECTION CLASSIFICATION WITH CONVOLUTIONAL NEURAL NETWORKS

2021 ◽  
Vol 1 ◽  
pp. 1401-1410
Author(s):  
Martin Denk ◽  
Klemens Rother ◽  
Tobias Höfer ◽  
Jan Mehlstäubl ◽  
Kristin Paetzold
Keyword(s):  
Topology Optimization ◽  
Cross Section ◽  
Cross Sections ◽  
Computer Aided Design ◽  
Laser Scanning ◽  
Main Axis ◽  
Distance Transformation ◽  
The Cross ◽  
Axis Rotation ◽  
Polygon Meshes

AbstractPolygon meshes and particularly triangulated meshes can be used to describe the shape of different types of geometry such as bicycles, bridges, or runways. In engineering, such polygon meshes can be supplied as finite element meshes, resulting from topology optimization or from laser scanning. Especially from topology optimization, frame-like polygon meshes with slender parts are typical and often have to be converted into a CAD (Computer-Aided Design) format, e.g., for further geometrical detailing or performing additional shape optimization. Especially for such frame-like geometries, CAD designs are constructed as beams with cross-sections and beam-lines, whereby the cross-section is extruded along the beam-lines or beam skeleton. One major task in the recognition of beams is the classification of the cross-section type such as I, U, or T, which is addressed in this article. Therefore, a dataset consisting of different cross-sections represented as binary images is created. Noisy dilatation, the distance transformation, and main axis rotation are applied to these images to increase the robustness and reduce the necessary amount of samples. The resulting images are applied to a convolutional neuronal network.

Enumeration of Cryptosporidium oocysts from surface water concentrates by laser-scanning cytometry

2000 ◽  
Vol 41 (7) ◽  
pp. 197-202 ◽  
Author(s):  
F. Zanelli ◽  
B. Compagnon ◽  
J. C. Joret ◽  
M. R. de Roubin
Keyword(s):  
Surface Water ◽  
Water Samples ◽  
Laser Scanning ◽  
Immunomagnetic Separation ◽  
Entire Surface ◽  
Cryptosporidium Oocysts ◽  
Different Types ◽  
Laser Scanning Cytometry ◽  
Direct Microscopic Observation

The utilization of the ChemScan® RDI was tested for different types of water concentrates. Concentrates were prepared by cartridge filtration or flocculation, and analysed either without purification, or after Immunomagnetic separation (IMS) or flotation on percoll-sucrose gradients. Theenumeration of the oocysts was subsequently performed using the ChemScan® RDI Cryptosporidium application. Enumeration by direct microscopic observation of the entire surface of the membrane was carried out as a control, and recoveries were calculated as a ratio between the ChemScan® RDI result and the result obtained with direct microscopic enumeration. The Chemscan enumeration technique proved reliable, with recoveries yielding close to 100% in most cases (average 125%, range from 86 to 467%) for all the concentration/purification techniques tested. The quality of the antibodies was shown to be critical, with antibodies from some suppliers yielding recoveries a low as 10% in some cases. This difficulty could, however, be overcome by the utilization of the antibody provided by Chemunex. These data conclusively prove that laser scanning cytometry, which greatly facilitates the microscopic enumeration of Cryptosporidium oocysts from water samples and decreases the time of observation by four to six times, can be successfully applied to water concentrates prepared from a variety of concentration/purification techniques.

scholarly journals Shape preserving design of geometrically nonlinear structures using topology optimization

2019 ◽  
Vol 59 (4) ◽  
pp. 1033-1051 ◽  
Author(s):  
Yu Li ◽  
Jihong Zhu ◽  
Fengwen Wang ◽  
Weihong Zhang ◽  
Ole Sigmund
Keyword(s):  
Topology Optimization ◽  
Geometrically Nonlinear ◽  
Nonlinear Structures ◽  
Shape Preserving

Educational course "Creation of virtual geological outcrops of the outskirts of Lviv"

2021 ◽  
Author(s):  
Ihor Bubniak ◽  
Serhiy Tsikhon ◽  
Anatoliy Tserklevych ◽  
Yevheniy Shylo ◽  
Mariia Oliinyk
Keyword(s):  
Laser Scanning ◽  
Terrestrial Laser Scanning ◽  
Field Work ◽  
Geological Structure ◽  
The Third ◽  
Self Study ◽  
Different Types ◽  
Teaching Award ◽  
The City ◽  
Educational Course

<p>We present a new educational course "Creation of virtual geological outcrops of the outskirts of Lviv" for students of geological specialties. Discipline "Creation of virtual geological outcrops of the outskirts of Lviv" is a selective discipline for students of 2-3 courses of various specialties, which is lectured in the amount of 3 credits (according to ECTS). The course is 32 hours of classroom classes, 16 hours of these of lectures, the rest 16 hours of practical classes and 58 hours of self-study.</p><p>The course is in three parts. First is preparatory ones. Students get acquainted with the geological structure of Lviv, prepare equipment for field work.</p><p>The field stage (the second part of the course) includes the survey of 3-4 geological objects around Lviv. These can be natural outcrops, quarries. A particularly valuable object for learning is the Honey Cave, located within the city limits. Depending on the object, we choose the type of survey— digital photogrammetry or terrestrial laser scanning. Each group of 4 students explores 2 objects.</p><p>The third cameral period includes field data processing. Students create 3D geological models and perform various measurements on them. Students compare different types of models to choose the best one. At this stage, students use a variety of software available in institutions. The final stage of the course is the preparation of a report and passing the exam.</p><p>The project war partly financed by EGU HE Teaching Award.</p>

scholarly journals Modeling conoid surfaces

2002 ◽  
Vol 2 (4) ◽  
pp. 261-266 ◽  
Author(s):  
Ljubica Velimirovic ◽  
Mica Stankovic ◽  
Grozdana Radivojevic
Keyword(s):  
Geometric Approach ◽  
Parametric Representation ◽  
Wide Range ◽  
Different Types

In tins paper we consider conoid surfaces as frequently used surfaces in building techniques, mainly as daring roof structures. Different types of conoids are presented using the programme package Mathematica. We describe the generation of conoids and by means of parametric representation we get their graphics. The geometric approach offers a wide range of possibilities in the research of complicated spatial surface systems.

scholarly journals Spline approximation, Part 1: Basic methodology

2018 ◽  
Vol 12 (2) ◽  
pp. 139-155 ◽  
Author(s):  
Nikolaj Ezhov ◽  
Frank Neitzel ◽  
Svetozar Petrovic
Keyword(s):  
Laser Scanning ◽  
Spline Approximation ◽  
Point Clouds ◽  
Approximation Problem ◽  
Point Of View ◽  
Mathematical Function ◽  
Distributed Data ◽  
Advantages And Disadvantages ◽  
Engineering Geodesy ◽  
Different Types

Abstract In engineering geodesy point clouds derived from terrestrial laser scanning or from photogrammetric approaches are almost never used as final results. For further processing and analysis a curve or surface approximation with a continuous mathematical function is required. In this paper the approximation of 2D curves by means of splines is treated. Splines offer quite flexible and elegant solutions for interpolation or approximation of “irregularly” distributed data. Depending on the problem they can be expressed as a function or as a set of equations that depend on some parameter. Many different types of splines can be used for spline approximation and all of them have certain advantages and disadvantages depending on the approximation problem. In a series of three articles spline approximation is presented from a geodetic point of view. In this paper (Part 1) the basic methodology of spline approximation is demonstrated using splines constructed from ordinary polynomials and splines constructed from truncated polynomials. In the forthcoming Part 2 the notion of B-spline will be explained in a unique way, namely by using the concept of convex combinations. The numerical stability of all spline approximation approaches as well as the utilization of splines for deformation detection will be investigated on numerical examples in Part 3.

Parametric Representation for Geometry Variation in Digital Mechanical System

2014 ◽  
Vol 686 ◽  
pp. 507-512
Author(s):  
Wei Dong Liu ◽  
Yuan Sun
Keyword(s):  
Mechanical System ◽  
Parametric Representation ◽  
Location Error ◽  
Orientation Error ◽  
Cad System ◽  
Different Types ◽  
Geometry Error

Ideal geometry is mainly represented by several parameters in traditional CAD system. Based on these parameters, ideal geometry can be dynamically constructed to build the entire CAD entity; however, the modeling of variated geometry by parameters is not included, and parametric representation for variated geometry is introduced in this paper; sets of parameters for different types of geometry variation are discussed. Based on parametric representation for variated geometry, the translation and orientation error of part that affected by the variation of geometry is calculated, the process for converting geometry error to parametric part location error is introduced.

An Adjustable Adaptive Subdivision Surface Modeling Based on Triangle Meshes

2010 ◽  
Vol 26-28 ◽  
pp. 702-705
Author(s):  
Fu Qing Zhao ◽  
Xin Ai
Keyword(s):  
Standard Technique ◽  
Adjustable Parameter ◽  
Shape Modeling ◽  
Subdivision Surfaces ◽  
Subdivision Scheme ◽  
Subdivision Surface ◽  
Triangle Meshes ◽  
Good Surface ◽  
Adaptive Subdivision ◽  
Loop Scheme

Subdivision surfaces have become a standard technique for free shape modeling. But tradition subdivision scheme does not adjust the shape of subdivision results. In this paper, We introd uce adjustable adaptive subdivision as a new adaptive subdivision method for triangle meshes. This method applied to the method of adaptive subdivision constructs a new subdivision rule by introducing adjustable parameter to the traditional Loop scheme. The experiment shows that this method not only use fewer meshes to obtain the performance good surface but also can adjust the hape of subdivision surface to satisfy the actual need.

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