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Modified virtual internal bond model based on deformable Voronoi particles

Theoretical & Applied Mechanics Letters 2020年第2期10卷 87-91页

作者： Oleg Konovalov Shunying Ji Michael Zhuravkov Research Laboratory of Information Technologies and Computer Graphics Belarusian State UniversityMinsk 220030Belarus DUT-BSU Joint Institute Dalian University of TechnologyDalian 116023China State Key Laboratory of Structural Analysis for Industrial Equipment Dalian University of TechnologyDalian 116023China Department of Theoretical and Applied Mechanics Belarusian State UniversityMinsk 220030Belarus

In last time,the series of virtual internal bond model was proposed for solving rock mechanics *** these models,the rock continuum is considered as a structure of discrete particles connected by normal and shear springs(bonds).It is well announced that the normal springs structure corresponds to a linear elastic solid with a fixed Poisson ratio,namely,0.25 for threedimensional *** the shear springs used to represent the diversity of the Poisson ***,the shearing force calculation is not rotationally invariant and it produce difficulties in application of these models for rock mechanics problems with sufficient *** this letter,we proposed the approach to support the diversity of the Poisson ratio that based on usage of deformable Voronoi cells as set of *** edges of dual Delaunay tetrahedralization are considered as structure of normal springs(bonds).The movements of particle’s centers lead to deformation of tetrahedrals and as result to deformation of Voronoi *** each bond,there are the corresponded dual face of some Voronoi *** can consider the normal bond as some beam and in this case,the appropriate face of Voronoi cell will be a cross section of this *** during deformation the Voronoi face was expand,then,according Poisson effect,the length of bond should be *** above mechanism was numerically investigated and we shown that it is acceptable for simulation of elastic behavior in 0.1–0.3 interval of Poisson *** surprise is that proposed approach give possibility to simulate auxetic materials with negative Poisson’s ratio in interval from–0.5 to–0.1.

关键词： Discrete element method Real multi-dimensional internal bond Voronoi tessellation Micromechanical poisson ratio Barycentric coordinates Auxetic effects

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The 3D Trajectory-based Stress Visualizer

arXiv

引用

arXiv 2021年

作者： Wang, Junpeng Neuhauser, Christoph Wu, Jun Gao, Xifeng Westermann, Rüdiger The Computer Graphics & Visualization Group Technische Universität München Garching Germany The Department of Sustainable Design Engineering Delft University of Technology Delft Netherlands The Lightspeed & Quantum Studio Tencent America United States

We present the 3D Trajectory-based Stress Visualizer (3D-TSV), a visual analysis tool for the exploration of the principal stress directions in 3D solids under load. 3D-TSV provides a modular and generic implementation of key algorithms required for a trajectory-based visual analysis of principal stress directions, including the automatic seeding of space-filling stress lines, their extraction using numerical schemes, their mapping to an effective renderable representation, and rendering options to convey structures with special mechanical properties. In the design of 3D-TSV, several perceptual challenges have been addressed when simultaneously visualizing three mutually orthogonal stress directions via lines. We present a novel algorithm for generating a space-filling and evenly spaced set of mutually orthogonal lines. The algorithm further considers the locations of lines to obtain a more regular pattern repetition, and enables the extraction of a Focus+Context representation with user-selected levels of detail for individual stress directions. To further reduce visual clutter, the system provides the combined visualization of two selected principal directions via appropriately oriented ribbons. The rendering uses depth cues to better convey the spatial relationships between trajectories and improves ribbon rendering on steep angles. 3D-TSV is accessible to end users via a C++- and OpenGL-based rendering frontend that is seamlessly connected to a MATLAB-based extraction backend. A TCP/IP-based communication interface supports the flexible integration of alternative rendering frontends. The code (BSD license) of 3D-TSV is made publicly available. Copyright © 2021, The Authors. All rights reserved.

关键词： Stresses

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Impact of shape on apparent translucency differences 27

Impact of shape on apparent translucency differences

引用

27th Color and Imaging Conference: Color Science and Engineering Systems, Technologies, and Applications, CIC 2019

作者： Gigilashvili, Davit Urban, Philipp Thomas, Jean-Baptiste Hardeberg, Jon Yngve Pedersen, Marius Department of Computer Science Norwegian University of Science and Technology Gjøvik Norway Fraunhofer Institute for Computer Graphics Research IGD Darmstadt Germany

ISBN: (纸本)9780892083435

Translucency is one of the major appearance attributes. Apparent translucency is impacted by various factors including object shape and geometry. Despite general proposals that object shape and geometry have a significant effect on apparent translucency, no quantification has been made so far. Quantifying and modeling the impact of geometry, as well as comprehensive understanding of the translucency perception process, are a point of not only academic, but also industrial interest with 3D printing as an example among many. We hypothesize that a presence of thin areas in the object facilitates material translucency estimation and changes in material properties have larger impact on apparent translucency of the objects with thin areas. computergenerated images of objects with various geometry and thickness have been used for a psychophysical experiment in order to quantify apparent translucency difference between objects while varying material absorption and scattering properties. Finally, absorption and scattering difference thresholds where the human visual system starts perceiving translucency difference need to be identified and its consistency needs to be analyzed across different shapes and geometries. © 2019 Society for Imaging Science and technology.

关键词： Geometry

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Indoor Navigation for Mobile Agents: A Multimodal Vision Fusion Model

Indoor Navigation for Mobile Agents: A Multimodal Vision Fus...

引用

International Joint Conference on Neural Networks (IJCNN)

作者： Dongfang Liu Yiming Cui Zhiwen Cao Yingjie Chen Department of Computer Graphics Technology Purdue University West Lafayette USA Department of Electrical & Computer Engineering University of Florida Gainesville FL USA

ISBN: (数字)9781728169262

ISBN: (纸本)9781728169279

Indoor navigation is a challenging task for mobile agents. The latest vision-based indoor navigation methods make remarkable progress in this field but do not fully leverage visual information for policy learning and struggle to perform well in unseen scenes. To address the existing limitations, we present a multimodal vision fusion model (MVFM). We implement a joint modality of different image recognition networks for navigation policy learning. The proposed model incorporates object detection for target searching, depth estimation for distance prediction, and semantic segmentation to depict the walkable region. In design, our model provides holistic vision knowledge for navigation. Evaluation on AI2-THOR indicates that MVFM improves on the results of a strong baseline model by 3.49% for Success weighted by Path Length (SPL) and 4% for success rate respectively. In comparison with other state-of-the-art systems, MVFM performs in the lead in terms of SPL and success rate. Extensive experiments show the effectiveness of the proposed model.

关键词： Feature extraction Indoor navigation Task analysis Visualization Semantics Object detection

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Creative graphic works of first-year students of Bachelors' degree of engineering educational program 2

Creative graphic works of first-year students of Bachelors' ...

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2nd International Scientific Conference on Metrological Support of Innovative Technologies, ICMSIT II-2021

作者： Mukhametzyanova, A.G. Bronskaya, V.V. Kharitonova, O.S. Department of Computer Graphics Engineering and Computer-Assisted Design Kazan National Research Technological University 68 Karl Marx Street Kazan420015 Russia Department of Chemical Process Engineering Kazan National Research Technological University 68 Karl Marx Street Kazan420015 Russia Department of Information Systems Kazan Federal University 35 Kremlyovskaya Street Kazan420008 Russia Department of Chemical Technology of Petroleum and Gas Processing Kazan National Research Technological University 68 Karl Marx Street Kazan420015 Russia

Such a form of organization of extracurricular work as a scientific circle is considered in this article. The purpose and content of the scientific circle on descriptive geometry, engineering and computer graphics are... 详细信息

关键词： computer graphics

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Bilevel learning of regularization models and their discretization for image deblurring and super-resolution

arXiv

引用

arXiv 2023年

作者： Bubba, Tatiana A. Calatroni, Luca Catozzi, Ambra Crisci, Serena Pock, Thomas Pragliola, Monica Rautio, Siiri Riccio, Danilo Sebastiani, Andrea Department of Mathematical Sciences University of Bath United Kingdom CNRS UCA INRIA Laboratoire I3S France Department of Mathematical Physical and Computer Sciences University of Parma Italy Department of Mathematics and Physics University of Campania "Luigi Vanvitelli" Italy Institute of Computer Graphics and Vision Graz University of Technology Austria Department of Mathematics and Applications University of Naples Federico II Italy Department of Mathematics and Statistics University of Helsinki Finland School of Mathematical Sciences Queen Mary University of London United Kingdom Department of Mathematics University of Bologna Italy

Bilevel learning is a powerful optimization technique that has extensively been employed in recent years to bridge the world of model-driven variational approaches with data-driven methods. Upon suitable parametrization of the desired quantities of interest (e.g., regularization terms or discretization filters), such approach computes optimal parameter values by solving a nested optimization problem where the variational model acts as a constraint. In this work, we consider two different use cases of bilevel learning for the problem of image restoration. First, we focus on learning scalar weights and convolutional filters defining a Field of Experts regularizer to restore natural images degraded by blur and noise. For improving the practical performance, the lower-level problem is solved by means of a gradient descent scheme combined with a line-search strategy based on the Barzilai-Borwein rule. As a second application, the bilevel setup is employed for learning a discretization of the popular total variation regularizer for solving image restoration problems (in particular, deblurring and super-resolution). Numerical results show the effectiveness of the approach and their generalization to multiple *** Codes 65K10 Copyright © 2023, The Authors. All rights reserved.

关键词： Image reconstruction

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Tumor likelihood estimation on MRI prostate data by utilizing k-Space information

arXiv

引用

arXiv 2024年

作者： Rempe, Moritz Hörst, Fabian Seibold, Constantin Hadaschik, Boris Schlimbach, Marco Egger, Jan Kröninger, Kevin Breuer, Felix Blaimer, Martin Kleesiek, Jens University Hospital Essen Girardetstraße 2 Essen45131 Germany University Medicine Essen Hufelandstraße 55 Essen45147 Germany Fraunhofer Institute for Integrated Circuits IIS Am Hubland Würzburg97074 Germany Department of Urology University Hospital Essen Hufelandstraße 55 Essen45147 Germany Department of Physics The Technical University Dortmund Otto-Hahn-Straße 4a Dortmund44227 Germany Computer Algorithms for Medicine Laboratory Graz8010 Austria Institute of Computer Graphics and Vision Graz Austria University of Technology Inffeldgasse 16 Graz8010 Austria Partner Site Essen Hufelandstraße 55 Essen45147 Germany

We present a novel preprocessing and prediction pipeline for the classification of magnetic resonance imaging (MRI) that takes advantage of the information rich complex valued k-Space. Using a publicly available MRI raw dataset with 312 subject and a total of 9508 slices, we show the advantage of utilizing the k-Space for better prostate cancer likelihood estimation in comparison to just using the magnitudinal information in the image domain, with an AUROC of 86.1%±1.8%. Additionally, by using high undersampling rates and a simple principal component analysis (PCA) for coil compression, we reduce the time needed for reconstruction by avoiding the time intensive GRAPPA reconstruction algorithm. By using digital undersampling for our experiments, we show that scanning and reconstruction time could be reduced. Even with an undersampling factor of 16, our approach achieves meaningful results, with an AUROC of 71.4%±2.9%, using the PCA coil combination and taking into account the k-Space information. With this study, we were able to show the feasibility of preserving phase and k-Space information, with consistent results. Besides preserving valuable information for further diagnostics, this approach can work without the time intensive ADC and reconstruction calculations, greatly reducing the post processing, as well as potential scanning time, increasing patient comfort and allowing a close to real-time prediction. © 2024, CC BY.

关键词： Magnetic resonance imaging

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Brain Tumour Removing and Missing Modality Generation using 3D Wavelet Diffusion Model

arXiv

引用

arXiv 2024年

作者： Ferreira, André Luijten, Gijs Puladi, Behrus Kleesiek, Jens Alves, Victor Egger, Jan Center Algoritmi LASI University of Minho Braga4710-057 Portugal Computer Algorithms for Medicine Laboratory Graz Austria University Medicine Essen Girardetstraße 2 Essen45131 Germany University Medicine Essen Hufelandstraße 55 Essen45147 Germany Partner Site Essen Hufelandstraße 55 Essen45147 Germany Institute of Computer Graphics and Vision Graz University of Technology Inffeldgasse 16 Graz8010 Austria Institute of Medical Informatics University Hospital RWTH Aachen Aachen Germany Department of Oral and Maxillofacial Surgery University Hospital RWTH Aachen Aachen Germany Department of Physics TU Dortmund University Dortmund Germany

This paper presents the second-placed solution for task 8 and the participation solution for task 7 of BraTS 2024. The adoption of automated brain analysis algorithms to support clinical practice is increasing. However, many of these algorithms struggle with the presence of brain lesions or the absence of certain MRI modalities. The alterations in the brain’s morphology leads to high variability and thus poor performance of predictive models that were trained only on healthy brains. The lack of information that is usually provided by some of the missing MRI modalities also reduces the reliability of the prediction models trained with all modalities. In order to improve the performance of these models, we propose the use of conditional 3D wavelet diffusion models. The wavelet transform enabled full-resolution image training and prediction on a GPU with 48 GB VRAM, without patching or downsampling, preserving all information for prediction. The code for these tasks is available at https://***/ShadowTwin41/BraTS_2023_2024_solutions. Copyright © 2024, The Authors. All rights reserved.

关键词： Magnetic resonance imaging

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Smooth Triaxial Weaving with Naturally Curved Ribbons

引用

Physical Review Letters 2021年第10期127卷 104301-104301页

作者： Changyeob Baek Alison G. Martin Samuel Poincloux Tian Chen Pedro M. Reis Department of Mechanical Engineering Massachusetts Institute of Technology Cambridge Massachusetts 02139 USA Flexible Structures Laboratory Institute of Mechanical Engineering École Polytechnique Fédérale de Lausanne (EPFL) Lausanne 1015 Switzerland Fivizzano Italy Computer Graphics and Geometry Laboratory School of Computer and Communication Sciences École Polytechnique Fédérale de Lausanne (EPFL) Lausanne 1015 Switzerland

Triaxial weaving is a handicraft technique that has long been used to create curved structures using initially straight and flat ribbons. Weavers typically introduce discrete topological defects to produce nonzero Gaussian curvature, albeit with faceted surfaces. We demonstrate that, by tuning the in-plane curvature of the ribbons, the integrated Gaussian curvature of the weave can be varied continuously, which is not feasible using traditional techniques. Further, we reveal that the shape of the physical unit cells is dictated solely by the in-plane geometry of the ribbons, not elasticity. Finally, we leverage the geometry-driven nature of triaxial weaving to design a set of ribbon profiles to weave smooth spherical, ellipsoidal, and toroidal structures.

关键词： Elasticity Topological defects Crystal structures Thin films Finite-element method Geometry Laser techniques

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A computational aperture stop for optical fiber bundles

A computational aperture stop for optical fiber bundles

引用

Computational Optical Sensing and Imaging, COSI 2020 - Part of Imaging and Applied Optics Congress 2020

作者： Orth, Antony Ploschner, Martin Wilson, Emma R. Maksymov, Ivan Gibson, Brant C. Computer Vision and Graphics Group National Research Council of Canada OttawaON Canada School of Information Technology and Electrical Engineering University of Queensland BrisbaneQLD Australia ARC Centre of Excellence for Nanoscale BioPhotonics RMIT University MelbourneVIC Australia Centre for Micro-Photonics Swinburne University of Technology HawthornVIC Australia

Optical fiber bundles are flexible image conduits used for endoscopy. We will discuss how the angular sensitivity of the bundle’s waveguiding cores can be leveraged for computational imaging. © 2020 The Authors.

ISBN: (纸本)9781557528209

关键词： Computational Imaging

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