Mesh Accuracy Research Articles

3D point cloud regularization method for uniform mesh generation of mining excavations

3D point cloud regularization method for uniform mesh generation of mining excavations

Early-stage design support for ice-shell architecture with integrated snow drift simulation tool

Early-stage design support for ice-shell architecture with integrated snow drift simulation tool

Stress-related discrete variable topology optimization with handling non-physical stress concentrations

Stress-related discrete variable topology optimization with handling non-physical stress concentrations

Numerical investigation on dynamic flow characteristics of methane condensation in microchannels

Numerical investigation on dynamic flow characteristics of methane condensation in microchannels

Quality-preserving multilevel mesh generation for building models

ABSTRACT Three-dimensional (3D) high-fidelity building models are crucial for digital twin cities. Multi-scale modeling is crucial for accurately capturing the complexity of urban environments; however, existing methods often lack the flexibility required to satisfy the varied demands of diverse applications. In this paper, we propose a framework to continuously simplify 3D building models, it dynamically adjusts mesh accuracy to meet diverse needs, enabling seamless transitions from high-poly to medium and low-poly meshes. Our method contains three main stages: First, in the mesh repair stage, we introduce a novel mesh repair framework based on an advanced Marching Cubes 33 algorithm to ensure a watertight and clean topology mesh. Then, for generating medium-poly meshes, we employ a feature-preserving mesh simplification algorithm that combines curvature and area-weighted quadratic error metrics to achieve a high-fidelity simplified mesh. For generating low-poly meshes, we use the concept of carving visual hull to generate low-poly mesh with high visual similarity. Our method has been evaluated on building subsets of the Free3D and Thingi10 K datasets, as well as on various building models generated from different observation scales, and its superiority has been validated through extensive comparisons with state-of-the-art techniques.

NeRF-based multi-frame 3D integration for 3D endoscopy using active stereo.

3D measurement for endoscopic systems has large potential not only for cancer diagnosis or computer-assisted medical systems, but also for providing ground truth for supervised training of deep neural networks. To achieve it, one of the promising approach is the implementation of an active-stereo system using a micro-sized pattern-projector attached to the head of the endoscope. Furthermore, a multi-frame optimization algorithm for the endoscopic active-stereo system has been proposed to improve accuracy and robustness; in the approach, differential rendering algorithm is used to simultaneously optimize the 3D scene represented by triangle meshes and the camera/projector poses. One issue with the approach is its dependency on the accuracy of the initial 3D triangle mesh, however, it is not an easy task to achieve sufficient accuracy for actual endoscopic systems, which reduces the practicality of the algorithm. In this paper, we adapt neural radiance field (NeRF) based 3D scene representation to integrate multi-frame data captured by active-stereo system, where the 3D scene as well as the camera/projector poses are simultaneously optimized without using the initial shape. In the experiment, the proposed method is evaluated by performing 3D reconstruction using both synthetic and real images obtained by a consumer endoscopic camera attached with a micro-pattern-projector.Clinical relevance- One-shot endoscopic measurement of depth information is a practical solution for cancer diagnosis, computer-assisted interventions, and making annotations for machine learning training data.

Numerical investigation of optical characterization of polycarbonate panels

Numerical investigation of optical characterization of polycarbonate panels

Analysis of r - Adaptive coupling adaptive time integration strategy in FEM of seismic liquefaction

Analysis of r - Adaptive coupling adaptive time integration strategy in FEM of seismic liquefaction

Indoor Mapping with Entertainment Devices: Evaluating the Impact of Different Mapping Strategies for Microsoft HoloLens 2 and Apple iPhone 14 Pro.

Due to their low cost and portability, using entertainment devices for indoor mapping applications has become a hot research topic. However, the impact of user behavior on indoor mapping evaluation with entertainment devices is often overlooked in previous studies. This article aims to assess the indoor mapping performance of entertainment devices under different mapping strategies. We chose two entertainment devices, the HoloLens 2 and iPhone 14 Pro, for our evaluation work. Based on our previous mapping experience and user habits, we defined four simplified indoor mapping strategies: straight-forward mapping (SFM), left-right alternating mapping (LRAM), round-trip straight-forward mapping (RT-SFM), and round-trip left-right alternating mapping (RT-LRAM). First, we acquired triangle mesh data under each strategy with the HoloLens 2 and iPhone 14 Pro. Then, we compared the changes in data completeness and accuracy between the different devices and indoor mapping applications. Our findings show that compared to the iPhone 14 Pro, the triangle mesh accuracy acquired by the HoloLens 2 has more stable performance under different strategies. Notably, the triangle mesh data acquired by the HoloLens 2 under the RT-LRAM strategy can effectively compensate for missing wall and floor surfaces, mainly caused by furniture occlusion and the low frame rate of the depth-sensing camera. However, the iPhone 14 Pro is more efficient in terms of mapping completeness and can acquire a complete triangle mesh more quickly than the HoloLens 2. In summary, choosing an entertainment device for indoor mapping requires a combination of specific needs and scenes. If accuracy and stability are important, the HoloLens 2 is more suitable; if efficiency and completeness are important, the iPhone 14 Pro is better.

An immersed boundary method‐discrete unified gas kinetic scheme simulation of particle‐laden turbulent channel flow on a nonuniform orthogonal mesh

AbstractParticle‐resolved simulations of turbulent particle‐laden flows provide a powerful research tool to explore detailed flow physics at all scales. However, efficient particle‐resolved simulations for wall‐bounded turbulent particle‐laden flows remain a challenging task. In this article, we develop a simulation approach for a turbulent channel flow laden with finite‐size particles on a nonuniform mesh by combining the discrete unified gas kinetic scheme (DUGKS) and the immersed boundary method (IBM). The standard discrete delta function was modified according to reproducible kernel particle method to take into account mesh non‐uniformity and correctly conserve force moments. Simulation results based on uniform and nonuniform meshes are compared to validate and examine the accuracy of the nonuniform mesh DUGKS‐IBM. Finally, the computational performance of the nonuniform mesh DUGKS‐IBM is discussed.

A three-dimensional high-order flux reconstruction lattice boltzmann flux solver for incompressible laminar and turbulent flows

A three-dimensional high-order flux reconstruction lattice boltzmann flux solver for incompressible laminar and turbulent flows

Research on the Detection Method of Coal Mine Roadway Bolt Mesh Based on Improved YOLOv7

Aiming at the environment of low illumination, high dust, and heavy water fog in coal mine driving face and the problems of occlusion, coincidence, and irregularity of bolt mesh laid on coal wall, a YOLOv7 bolt mesh-detection algorithm combining the image enhancement and convolutional block attention module is proposed. First, the image brightness is enhanced by a hyperbolic mapping transform-based image enhancement algorithm, and the image is defogged by a dark channel-based image defogging algorithm. Second, by introducing a convolutional block attention model in the YOLOv7 detection network, the significance of bolt mesh targets in the image is improved, and its feature expression ability in the detection network is enhanced. Meanwhile, the original activation function ReLU in the convolutional layer Conv of the YOLOv7 network is replaced by LeakyReLU so that the activation function has stronger nonlinear expression capability, which enhances the feature extraction performance of the network and thus improves the detection accuracy. Finally, the training and testing samples were prepared using the actual video of the drilling and bolting operation, and the proposed algorithm is compared with five classical target detection algorithms. The experimental results show that the proposed algorithm can be better applied to the low illumination, high dust environment, and irregular shape on the detection accuracy of coal mine roadway bolt mesh, and the average detection accuracy of the image can reach 95.4% with an average detection time of 0.0392 s.

HyperGraph based human mesh hierarchical representation and reconstruction from a single image

HyperGraph based human mesh hierarchical representation and reconstruction from a single image

A continuous field adaptive mesh refinement algorithm for isogeometric topology optimization using PHT-Splines

A continuous field adaptive mesh refinement algorithm for isogeometric topology optimization using PHT-Splines

Numerical simulation of turbulent natural convection heat transfer in an MW-class offshore wind turbine nacelle based on a multi-feature acquisition meshing technique

Numerical simulation of turbulent natural convection heat transfer in an MW-class offshore wind turbine nacelle based on a multi-feature acquisition meshing technique

Research on TA1 mesh low-melting-point alloy filling incremental forming process for cranial prosthesis

The single point incremental forming (SPIF) process is a flexible and progressive manufacturing technique in the monolithic molding domain of heterogeneous metal pressing panels, which can contribute to the monolithic molding of metal pressing panels with complex contour and applicable to the fabrication of a small amount of titanium mesh plates for cranial prosthesis. A sandwich construction of titanium mesh was proposed in this paper for the purpose of inhibiting the indentation on the product surface and the deformation extent of mesh opening, as well as the forming accuracy of titanium mesh. The method of finite element modelling was applied to analyze the influence rules of low-melting-point alloy/synergistic deformation mechanism of titanium mesh as well as low-melting-point alloy layer on titanium mesh incremental forming quality. At last, the horizontal arrangement of significance regarding process parameters on sandwich titanium mesh wall thickness and rebound ratio effects was confirmed.

A Simple Non-Conforming Isogeometric Formulation with Superior Accuracy for Free Vibration Analysis of Thin Beams and Plates

A set of non-conforming quadratic basis functions is introduced to formulate the mass and stiffness matrices that enable a superior frequency accuracy for isogeometric free vibration analysis of thin beams and plates. The non-conforming basis functions are expressed as a simple combination of the original basis functions and their second-order derivatives with an adjustable parameter. By construction, these quadratic non-conforming basis functions only affect the mass matrices and do not alter the stiffness matrices. The adjustable parameter arising from the non-conforming basis functions are determined through optimizing the frequency accuracy. In the case of thin beams, the proposed non-conforming isogeometric formulation leads to an increase of frequency accuracy order or superconvergence. For thin plates, the frequency error of the proposed method is guaranteed to be no larger than that of the standard isogeometric approach. Numerical results for thin beams and plates consistently verify that the proposed formulation with non-conforming basis functions is quite robust and produces very favorable frequency accuracy for both uniform and non-uniform meshes.

A Simple Automatic Hexahedron Mesh Generation and Polyhedral Smoothed Finite Element Method for Mechanics Problems

A Simple Automatic Hexahedron Mesh Generation and Polyhedral Smoothed Finite Element Method for Mechanics Problems

Comparative performance of novel nodal-to-edge finite elements over conventional nodal element for electromagnetic analysis

In nodal-based finite element method (FEM), degrees of freedom are associated with the nodes of the element whereas, for edge FEM, degrees of freedom are assigned to the edges of the element. Edge element is constructed based on Whitney spaces. Nodal elements impose both tangential and normal continuity of vector or scalar fields across interface boundaries. But in edge elements, only tangential continuity is imposed across interface boundaries, which is consistent with electromagnetic field problems. Therefore the required continuities in the electromagnetic analysis are directly obtained with edge elements whereas in nodal elements they are attained through potential formulations. Hence, while using edge elements, field variables are directly calculated but with nodal elements, post-processing is required to obtain the field variables from the potentials. Here, we present the finite element formulations with the edge element as well as with nodal elements. Thereafter, we have demonstrated the relative performances of different nodal and edge elements through a series of examples. All possible complexities like curved boundaries, non-convex domains, sharp corners, non-homogeneous domains have been addressed in those examples. The robustness of edge elements in predicting the singular eigen values for the domains with sharp edges and corners is evident in the analysis. A better coarse mesh accuracy has been observed for all the edge elements as compared to the respective nodal elements. Edge elements are also not susceptible to mesh distortion.

Hermite type radial basis function-based differential quadrature approach allows for free vibration beams for higher order equations

Hermite type radial basis function-based differential quadrature approach allows for free vibration beams for higher order equations