A generic strategy to obtain semi‐analytical mesh sensitivities/velocities for tetrahedral mesh generators

2021 ◽  
Author(s):  
Campbell Bam ◽  
Daniel N. Wilke ◽  
Schalk Kok
Keyword(s):  
Tetrahedral Mesh ◽  
Generic Strategy ◽  
Mesh Generators

Hexahedral Meshing of Subject-Specific Anatomic Structures Using Registered Building Blocks

2010 ◽  
Author(s):  
Amla Natarajan ◽  
Vincent A. Magnotta ◽  
Nicole M. Grosland
Keyword(s):  
Building Blocks ◽  
Tetrahedral Mesh ◽  
Computational Time ◽  
Patient Specific ◽  
Mesh Quality ◽  
High Quality ◽  
Subject Specific ◽  
Hexahedral Meshes ◽  
Mesh Generators ◽  
User Intervention

Generating high quality, subject-specific, 3D finite element anatomic models with minimal user-intervention remains a challenge. Numerous automated tetrahedral mesh generators are available, but hexahedral meshes are preferred due to their higher accuracy and faster computational time over tetrahedral meshes. Historically, the generation of hexahedral meshes for analysis is a tedious and time-consuming task. Therefore, the utilization of hexahedral meshes is often limited to baseline models that are powerful, but not patient-specific. Once a high quality mesh has been created, it would be ideal if it can be used to create meshes of similar surfaces from different subjects, without disrupting mesh quality.

Update to: Approaches to the Automatic Generation and Control of Finite Element Meshes

1996 ◽  
Vol 49 (10S) ◽  
pp. S5-S14 ◽  
Author(s):  
Mark S. Shephard
Keyword(s):  
Mesh Generation ◽  
Three Dimensional ◽  
Automatic Generation ◽  
Tetrahedral Mesh ◽  
Hexahedral Mesh ◽  
Automatic Mesh Generation ◽  
The Status ◽  
Automatic Mesh ◽  
And Control ◽  
Mesh Generators

This paper updates the status of efforts on the development of automatic mesh generation techniques for general three-dimensional domains. The technical areas reviewed include: (i) issues associated with automatic mesh generation of CAD geometric models, (ii) local mesh modification procedures for improving mesh quality, (iii) advances in tetrahedral mesh generators, (iv) generation of anisotropic meshes, (v) hexahedral mesh generators, and (vi) implementation of automatic mesh generators on parallel computers.

scholarly journals An automated tetrahedral mesh generator for computer simulation in Odontology based on the Delaunay’s algorithm

Exacta ◽  
2009 ◽  
Vol 6 (2) ◽  
pp. 237-244
Author(s):  
Mauro Massayoshi Sakamoto ◽  
José Roberto Cardoso ◽  
José Marcio Machado
Keyword(s):  
Computer Simulation ◽  
Software Package ◽  
Tetrahedral Mesh ◽  
Mesh Generator ◽  
Geometric Models ◽  
Homogeneous Structures ◽  
Mesh Generators

In this work, a software package based on the Delaunay’s algorithm is described. The main feature of this package is the capability in applying discretization in geometric domains of teeth taking into account their complex inner structures and the materials with different hardness. Usually, the mesh generators reported in literature treat molars and other teeth by using simplified geometric models, or even considering the teeth as homogeneous structures.

scholarly journals An automated tetrahedral mesh generator for computer simulation in Odontology based on the Delaunay’s algorithm DOI: 10.5585/exacta.v6i2.1204

Exacta ◽  
2009 ◽  
Vol 6 (2) ◽  
pp. 237-244
Author(s):  
Mauro Massayoshi Sakamoto ◽  
José Roberto Cardoso ◽  
José Marcio Machado
Keyword(s):  
Computer Simulation ◽  
Software Package ◽  
Tetrahedral Mesh ◽  
Mesh Generator ◽  
Geometric Models ◽  
Homogeneous Structures ◽  
Mesh Generators

In this work, a software package based on the Delaunay’s algorithm is described. The main feature of this package is the capability in applying discretization in geometric domains of teeth taking into account their complex inner structures and the materials with different hardness. Usually, the mesh generators reported in literature treat molars and other teeth by using simplified geometric models, or even considering the teeth as homogeneous structures.

scholarly journals Ultrasensitive nano-optomechanical force sensor operated at dilution temperatures

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Francesco Fogliano ◽  
Benjamin Besga ◽  
Antoine Reigue ◽  
Laure Mercier de Lépinay ◽  
Philip Heringlake ◽  
...  
Keyword(s):  
Thermal Conduction ◽  
Photon Counting ◽  
Force Sensor ◽  
Lateral Force ◽  
Oscillation Period ◽  
The Road ◽  
Field Gradients ◽  
Concomitant Reduction ◽  
Generic Strategy ◽  
Conduction Properties

AbstractCooling down nanomechanical force probes is a generic strategy to enhance their sensitivities through the concomitant reduction of their thermal noise and mechanical damping rates. However, heat conduction becomes less efficient at low temperatures, which renders difficult to ensure and verify their proper thermalization. Here we implement optomechanical readout techniques operating in the photon counting regime to probe the dynamics of suspended silicon carbide nanowires in a dilution refrigerator. Readout of their vibrations is realized with sub-picowatt optical powers, in a situation where less than one photon is collected per oscillation period. We demonstrate their thermalization down to 32 ± 2 mK, reaching very large sensitivities for scanning probe force sensors, 40 zN Hz−1/2, with a sensitivity to lateral force field gradients in the fN m−1 range. This opens the road toward explorations of the mechanical and thermal conduction properties of nanoresonators at minimal excitation level, and to nanomechanical vectorial imaging of faint forces at dilution temperatures.

scholarly journals Tetrahedra of varying density and their applications

2021 ◽  
Author(s):  
Dennis R. Bukenberger ◽  
Hendrik P. A. Lensch
Keyword(s):  
Tetrahedral Mesh ◽  
Rotational Inertia ◽  
Exact Mass ◽  
Accurate Analysis ◽  
Exact Integration ◽  
Voronoi Cells ◽  
Current State ◽  
Chebyshev Norm ◽  
Exact Calculations ◽  
Vector Matrix

Abstract We propose concepts to utilize basic mathematical principles for computing the exact mass properties of objects with varying densities. For objects given as 3D triangle meshes, the method is analytically accurate and at the same time faster than any established approximation method. Our concept is based on tetrahedra as underlying primitives, which allows for the object’s actual mesh surface to be incorporated in the computation. The density within a tetrahedron is allowed to vary linearly, i.e., arbitrary density fields can be approximated by specifying the density at all vertices of a tetrahedral mesh. Involved integrals are formulated in closed form and can be evaluated by simple, easily parallelized, vector-matrix multiplications. The ability to compute exact masses and centroids for objects of varying density enables novel or more exact solutions to several interesting problems: besides the accurate analysis of objects under given density fields, this includes the synthesis of parameterized density functions for the make-it-stand challenge or manufacturing of objects with controlled rotational inertia. In addition, based on the tetrahedralization of Voronoi cells we introduce a precise method to solve $$L_{2|\infty }$$ L 2 | ∞ Lloyd relaxations by exact integration of the Chebyshev norm. In the context of additive manufacturing research, objects of varying density are a prominent topic. However, current state-of-the-art algorithms are still based on voxelizations, which produce rather crude approximations of masses and mass centers of 3D objects. Many existing frameworks will benefit by replacing approximations with fast and exact calculations. Graphic abstract

scholarly journals Boosting heritability: estimating the genetic component of phenotypic variation with multiple sample splitting

2021 ◽  
Vol 22 (1) ◽  
Author(s):  
The Tien Mai ◽  
Paul Turner ◽  
Jukka Corander
Keyword(s):  
Random Effect ◽  
Simulated Data ◽  
Fixed Effect Model ◽  
Accurate Estimate ◽  
Limited Attention ◽  
Effect Model ◽  
Generic Strategy ◽  
Multiple Sample ◽  
Inference Strategy ◽  
Resistance Data

Abstract Background Heritability is a central measure in genetics quantifying how much of the variability observed in a trait is attributable to genetic differences. Existing methods for estimating heritability are most often based on random-effect models, typically for computational reasons. The alternative of using a fixed-effect model has received much more limited attention in the literature. Results In this paper, we propose a generic strategy for heritability inference, termed as “boosting heritability”, by combining the advantageous features of different recent methods to produce an estimate of the heritability with a high-dimensional linear model. Boosting heritability uses in particular a multiple sample splitting strategy which leads in general to a stable and accurate estimate. We use both simulated data and real antibiotic resistance data from a major human pathogen, Sptreptococcus pneumoniae, to demonstrate the attractive features of our inference strategy. Conclusions Boosting is shown to offer a reliable and practically useful tool for inference about heritability.

A study of real-time simulation of liver of virtual surgical robot based on biologically position-based dynamic model

2021 ◽  
pp. 1-16
Author(s):  
Dan Luo ◽  
Yu Zhang ◽  
Jia Li ◽  
Jisheng Li
Keyword(s):  
Soft Tissue ◽  
Real Time ◽  
Surgical Instruments ◽  
Organic Polymer ◽  
Tetrahedral Mesh ◽  
Virtual Surgery ◽  
Constraint Force ◽  
Real Time Simulation ◽  
Time Simulation ◽  
Spring Force

Virtual surgery robot can accurately modeling of surgical instruments and human organs, and realistic simulation of various surgical phenomena such as deformation of organic tissues, surgery simulation system can provide operators with reusable virtual training and simulation environment. To meet the requirement of virtual surgery robot for the authenticity and real-time of soft tissue deformation and surgical simulation in liver surgery, a new method is proposed to simulate the deformation of soft tissue. This method combines the spring force, the external force of the system, and the constraint force produced by the constraint function of the position-based dynamics. Based on the position-based dynamics, an improved three-parameter mass-spring model is added. In the calculation of the elastic force, the nonlinearity and viscoelasticity of the soft tissue are introduced, and the joint force of the constraint projection process and the constraint force of the position-based dynamics is used to modify mass points movement. The method of position-based dynamics based on biological characteristics, not only considers the biomechanical properties of biological soft tissue as an organic polymer such as viscoelasticity, nonlinearity, and incompressibility but also retains the rapidity and stability of the position based dynamic method. Through the simulation data, the optimal side length of tetrahedral mesh in the improved three-parameter model is obtained, and the physical properties of the model are proved. The real-time simulation of the liver and other organs is completed by using the Geomagic touch force feedback device, which proves the practicability and effectiveness of this method.

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