Methods for anchoring boundary nodes when smoothing a triangular surface mesh

In numerical modeling tasks that use surface meshes, remeshing is often required. However, while remeshing, distortion can occur. The accumulation of distortions can lead to the collapse of the solution. Smoothing algorithms are used to maintain the quality of the mesh during the calculation. When performing smoothing using methods that shift the mesh nodes, the border nodes are usually fixed to avoid distortion. However, simply fixing the nodes can lead to more severe distortion. This paper presents methods for working with boundary nodes to control such nodes during the smoothing process. Algorithms for working with pseudo-3D surface meshes, which are of particular interest, are also considered.

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Influence of seismic wave frequency on the quality of the landslide surface exploration in the light of numerical modeling

Geoinformatica Polonica ◽

10.2478/v10300-012-0015-0 ◽

2013 ◽

Vol 12 (1) ◽

Author(s):

Rafał Pilecki

Keyword(s):

Numerical Modeling ◽

Seismic Wave ◽

Wave Frequency ◽

Surface Exploration

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RRT based path planning for mobile robots on a 3D surface mesh

2021 Southern African Universities Power Engineering Conference/Robotics and Mechatronics/Pattern Recognition Association of South Africa (SAUPEC/RobMech/PRASA) ◽

10.1109/saupec/robmech/prasa52254.2021.9377014 ◽

2021 ◽

Author(s):

Cebisile Mthabela ◽

Daniel Withey ◽

Chioniso Kuchwa-Dube

Keyword(s):

Path Planning ◽

Mobile Robots ◽

Surface Mesh ◽

3D Surface

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Numerical modeling of seismic waves by discontinuous spectral element methods

ESAIM Proceedings and Surveys ◽

10.1051/proc/201861001 ◽

2018 ◽

Vol 61 ◽

pp. 1-37 ◽

Cited By ~ 7

Author(s):

Paola F. Antonietti ◽

Alberto Ferroni ◽

Ilario Mazzieri ◽

Roberto Paolucci ◽

Alfio Quarteroni ◽

...

Keyword(s):

Numerical Modeling ◽

Discontinuous Galerkin ◽

Large Scale ◽

Seismic Waves ◽

Spectral Element ◽

Fully Discrete ◽

Time Marching ◽

Space Discretization ◽

Large Earthquakes

We present a comprehensive review of Discontinuous Galerkin Spectral Element (DGSE) methods on hybrid hexahedral/tetrahedral grids for the numerical modeling of the ground motion induced by large earthquakes. DGSE methods combine the exibility of discontinuous Galerkin meth-ods to patch together, through a domain decomposition paradigm, Spectral Element blocks where high-order polynomials are used for the space discretization. This approach allows local adaptivity on discretization parameters, thus improving the quality of the solution without affecting the compu-tational costs. The theoretical properties of the semidiscrete formulation are also revised, including well-posedness, stability and error estimates. A discussion on the dissipation, dispersion and stability properties of the fully-discrete (in space and time) formulation is also presented. Here space dis-cretization is obtained based on employing the leap-frog time marching scheme. The capabilities of the present approach are demonstrated through a set of computations of realistic earthquake scenar-ios obtained using the code SPEED (http://speed.mox.polimi.it), an open-source code specifically designed for the numerical modeling of large-scale seismic events jointly developed at Politecnico di Milano by The Laboratory for Modeling and Scientific Computing MOX and by the Department of Civil and Environmental Engineering.

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Investigation of the Effects of Surrounding Media on the Distributed Acoustic Sensing of Helically-Wound Fiber-Optic Cable with Application to the New Afton Deposit, British Columbia

10.5194/se-2020-197 ◽

2020 ◽

Author(s):

Sepidehalsadat Hendi ◽

Mostafa Gorjian ◽

Gilles Bellefleur ◽

Christopher D. Hawkes ◽

Don White

Keyword(s):

British Columbia ◽

Numerical Modeling ◽

Analytical Model ◽

Field Data ◽

Fiber Optic ◽

Incident Angle ◽

Acoustic Sensing ◽

Distributed Acoustic Sensing ◽

Straight Fiber

Abstract. Fiber optic sensing technology has recently become popular for oil and gas, mining, geotechnical engineering, and hydrogeology applications. With a successful track record in many applications, distributed acoustic sensing using straight fiber optic cables has become a method of choice for seismic studies. However, distributed acoustic sensing using straight fiber optic cables is not able to detect off-axial strain, hence a helically wound cable design was introduced to overcome this limitation. The helically wound cable field data in New Afton deposit showed that the quality of the data is tightly dependent on the incident angle (the angle between the ray and normal vector of the surface) and surrounding media. We introduce a new analytical two-dimensional approach to determine the dynamic strain of a helically wound cable in terms of incident angle in response to elastic plane waves propagating through multilayered media. The method can be used to quickly and efficiently assess the effects of various materials surrounding a helically wound cable. Results from the proposed analytical model are compared with results from numerical modeling obtained with COMSOL Multiphysics, for scenarios corresponding to a real installation of helically wound cable deployed underground at the New Afton mine in British Columbia, Canada. Results from the analytical model are consistent with numerical modeling results. Our modeling results demonstrate the effects of cement quality, and casing installment on the quality of the helically-wound cable response. Numerical modeling results and field data suggest that, even if reasonably effective coupling achieved, the soft nature of the rocks in these intervals would result in low fiber strains for the HWC. The proposed numerical modeling workflow would be applied for more complicated scenarios (e.g., non-linear material constitutive behaviour, and the effects of pore fluids). The results of this paper can be used as a guideline for analyzing the effect of surrounding media and incident angle on the response of helically wound cable, optimizing the installation of helically wound cable in various conditions, and to validate boundary conditions of 3-D numerical model built for analyzing complex scenarios.

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Investigation of Effective Mechanical Characteristics of Nanomodified Carbon-Epoxide Composite by Numerical and Analytical Methods

Turkish Journal of Computer and Mathematics Education (TURCOMAT) ◽

10.17762/turcomat.v12i5.1049 ◽

2021 ◽

Vol 12 (5) ◽

pp. 535-541

Author(s):

M.O. Kaptakov

Keyword(s):

Mechanical Properties ◽

Numerical Modeling ◽

Fracture Surface ◽

Mechanical Characteristics ◽

Modeling Methods ◽

Fullerene Soot ◽

The Matrix ◽

Numerical And Analytical Methods ◽

Composite Samples

In this work, the mechanical properties of composite samples prepared using a conventional and nanomodified matrix were studied. The thickness of the monolayers in the samples was 0,2 μm. It was found in experiments, that the addition of fullerene soot as a nanomodifierled to an increase in the mechanical properties of the samples along the direction of reinforcement. At the same time, an improvement in the quality of the contact of the matrix with the fibers in the samples with the nanomodifier was observed: on the fracture surface, the nanomodified matrix envelops the fibers, while the usual matrix completely exfoliates. The obtained effects of changing the strength of composites can be associated, among other things, with a change in the level of residual stresses arising in composites during nanomodification. Analytical and numerical modeling methods are used to explain these effects.

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Smoothing Algorithm for Planar and Surface Mesh Based on Element Geometric Deformation

Mathematical Problems in Engineering ◽

10.1155/2015/435648 ◽

2015 ◽

Vol 2015 ◽

pp. 1-9 ◽

Cited By ~ 2

Author(s):

Shuli Sun ◽

Minglei Zhang ◽

Zhihong Gou

Keyword(s):

Weighted Average ◽

Processing Unit ◽

Smoothing Algorithm ◽

Surface Mesh ◽

Polygonal Mesh ◽

Second Stage ◽

Geometric Deformation ◽

Error Metric ◽

The Individual

Smoothing is one of the basic procedures for improvement of mesh quality. In this paper, a novel and efficient smoothing approach for planar and surface mesh based on element geometric deformation is developed. The presented approach involves two main stages. The first stage is geometric deformation of all the individual elements through a specially designed two-step stretching-shrinking operation (SSO), which is performed by moving the vertices of each element according to a certain rule in order to get better shape of the element. The second stage is to determine the position of each node of the mesh by a weighted average strategy according to quality changes of its adjacent elements. The suggested SSO-based smoothing algorithm works efficiently for triangular mesh and can be naturally expanded to quadrilateral mesh, arbitrary polygonal mesh, and mixed mesh. Combined with quadratic error metric (QEM), this approach may be also applied to improve the quality of surface mesh. The proposed method is simple to program and inherently very suitable for parallelization, especially on graphic processing unit (GPU). Results of numerical experiments demonstrate the effectiveness and potential of this method.

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Rail Highway Grade Crossing Roughness Quantitative Measurement Using 3D Technology

2014 Joint Rail Conference ◽

10.1115/jrc2014-3778 ◽

2014 ◽

Cited By ~ 1

Author(s):

Teng (Alex) Wang ◽

Reginald R. Souleyrette ◽

Daniel Lau ◽

Peng Xu

Keyword(s):

Quantitative Method ◽

Cost Effective ◽

Actual Condition ◽

Subjective Rating ◽

3D Surface ◽

Grade Crossing ◽

Long Term Performance ◽

Term Performance

Quality of surface is an important aspect affecting both the safety and the performance of at-grade rail-highway crossings. Roughness may increase the risk of crashes for both trains and automobiles. Varying grades in crossing profiles increase the likelihood of high-centered crossing collisions between train and truck [1]. The US DOT Railroad Highway Grade Crossing Handbook [2] suggests that rough surfaces could distract a driver’s attention from oncoming trains and that the unevenness of the crossing could result in a driver losing control of their vehicle resulting in a crash. No quantitative method currently exists to quickly and economically assess the condition of rail crossings in order to evaluate the long term performance of crossings and set a quantitative trigger for their rehabilitation. The conventional method to measure the surface of quality of crossings is based on expert judgment, whereby crossing surfaces are classified as poor, fair or good after an inspector visits and drives over the crossing. However, actual condition of the crossing could be different from the subjective rating. Poor condition rating crossings may not always present the most cost-effective locations for preventive maintenance to lower overall life-cycle costs. Conventional ratings may derive from driving a passenger car of pickup once over the crossing. Effects of various speed, on various vehicles (suspension), and at various places (laterally) cannot be determined or even estimated except at the smoothest of crossings. A quantifiable and extensible procedure is desired. With rapid advances in computer science, 3D sensing and imaging technologies, it seems logical that a cost-effective quantitative method could be developed to determine the need to rehabilitate rail crossings and assess long term performance. Fundamental to the quantification of crossing condition is the acquisition of an accurate 3D surface model of the crossing in its present state. This paper reports on the development of an accurate, low cost and readily deployable sensor capable of rapid collection of this 3D surface. The research is seen as a first step towards automating the crossing inspection process, ultimately leading to the quantification and estimation of future performance of rail crossing.

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Fines mobility and distribution in streaming fibre networks: experimental evidence and numerical modeling

Cellulose ◽

10.1007/s10570-020-03443-9 ◽

2020 ◽

Vol 27 (16) ◽

pp. 9663-9682

Author(s):

Jakob D. Redlinger-Pohn ◽

Melanie Mayr ◽

Gregor Schaub ◽

David Gruber ◽

Stefan Radl

Keyword(s):

Numerical Modeling ◽

Flow Rate ◽

Removal Rate ◽

Small Particles ◽

Classical View ◽

Fibre Network ◽

Fibre Suspensions ◽

Fibre Suspension ◽

Network Strength

AbstractThe motion of flocculated fibres in a streaming suspension is governed by the balance of the network strength and hydrodynamic forces. With increasing flow rate through a channel, (1) the network initially occupying all space, (2) is then compressed to the centre, and (3) ultimately dispersed. This classical view neglects fibres-fines: we find that the distribution of these small particles differs in streaming suspensions. While it is known that fibre-fines can escape the fibre network, we find that the distribution of fibre-fines is non-homogenous in the network during compression: fibre-fines can be caged and retarded in the streaming fibre network. Hence, the amount of fibre-fines is reduced outside of a fibre network and enriched at the network’s interface. Aiming on selectively removing fibre-fines from a streaming network by suction, we identify a reduction of the fines removal rate. That documents a hindered mobility of fibre-fines when moving through the network of fibres. Additionally, we found evidence, that the mobility of fibre-fines is dependent on the fibre-fines quality, and is higher for fibrillar fines. Consequently, we suggest that the quality of fibre-fines removed from the suspension can be controlled with the flow regime in the channel. Finally, we present a phenomenological model to compute the length dependent fibre distribution in an arbitary geometry. For a fibre suspension channel flow we are able to predict a length-dependent fibre segregation near the channel’s centre. The erosion of a plug of long fibres was however underestimated by our model. Interestingly, our model with parameters fitted to streaming fibre suspension qualitatively agreed with the motion of micro-fibrillated cellulose. This gives hope that devices for handling flocculated fibre suspensions can be designed in the future with greater confidence.

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