normal vectors
Recently Published Documents


TOTAL DOCUMENTS

243
(FIVE YEARS 54)

H-INDEX

21
(FIVE YEARS 3)

Author(s):  
Mong Hien Thi Nguyen ◽  
◽  
Minh Hieu Tran ◽  

This paper presents the research results of automatic estimation of the neck girth and inside leg to extract the size and body shape from the male sizing system table. The data used in the study is the 3D scan file *.obj from the 3D body scanner. The author uses the interpolation and optimization method in the algorithm to automatically extract 2 primary dimensions combined with the fuzzy logic method to extract sizes, body shapes. Besides, rotate matrix method combines with the optimal function used to write an algorithm to estimate the neck girth, inside leg measurements. Furthermore, a simple approach based on vertices and surface normal vectors data and optimal search was adapted to estimate the neck girth and inside leg measurements. These extraction results will be linked to the algorithm of the fuzzy logic to run for the automated process. This automatic algorithm will be very useful in face-to-face clothing purchases or online or for garment manufacturers in reducing shopping time and choosing sizes to design samples for customers.


Author(s):  
Jiasheng Li ◽  
Yegao Qu ◽  
Yong Chen ◽  
Hongxing Hua ◽  
Junyun Wu

This paper focuses on the development of a three-dimensional panel method in time and frequency domains combined with the finite element method for analyzing the hydroelastic responses of rotating marine propellers in the wake of ships. A fully non-penetration boundary condition imposed on the deformed blade surface is conducted, in which the corrections of both the incoming flow velocities and the normal vectors imposed on the deformed and undeformed blade surface are taken into account. The added-mass and -damping matrices due to strongly coupled fluid-structure interaction are considered. Results of the present method are compared with experimental data available in the literature. It is observed that the fully non-penetration boundary condition applied on the deformed blade surface should be imposed to predict the unsteady performance of elastic propellers, which is due to the change of the added damping predicted by considering different non-penetration boundary conditions.


2021 ◽  
Vol 11 (24) ◽  
pp. 11804
Author(s):  
Gabriela Bariczová ◽  
Ján Erdélyi ◽  
Richard Honti ◽  
Lukáš Tomek

Building information modeling (BIM) represents significant progress in the field of digitalization and informatization of the construction process. The virtual model (BIM model) is the source of graphic data among other information, which are applicable for geometry verification of the building’s structures. For this purpose, data and information about the building should be collected. Comparison of the BIM model (design) with as-built 3D models enables the evaluation of the quality of the as-built structures. The most effective methods for spatial data collection are terrestrial laser scanning (TLS) and close-range photogrammetry. Using both methods, measurement can result in a point cloud. The paper describes an approach for verifying the geometry of wall structures. The graphic data of designed structures are represented by the existing BIM model. The approach presented uses the Industry Foundation Classes (IFC) file format from which the designed geometry is derived. The as-built models of the structures are created from point clouds. Point cloud segmentation uses a combination of regression, filtering based on local normal vectors, and curve segmentation. Consequently, the designed and the as-built models (segmented from the point cloud) are compared.


2021 ◽  
Vol 2021 (12) ◽  
Author(s):  
Song He ◽  
Zhenjie Li ◽  
Qinglin Yang

Abstract We propose that the symbol alphabet for classes of planar, dual-conformal-invariant Feynman integrals can be obtained as truncated cluster algebras purely from their kinematics, which correspond to boundaries of (compactifications of) G+(4, n)/T for the n-particle massless kinematics. For one-, two-, three-mass-easy hexagon kinematics with n = 7, 8, 9, we find finite cluster algebras D4, D5 and D6 respectively, in accordance with previous result on alphabets of these integrals. As the main example, we consider hexagon kinematics with two massive corners on opposite sides and find a truncated affine D4 cluster algebra whose polytopal realization is a co-dimension 4 boundary of that of G+(4, 8)/T with 39 facets; the normal vectors for 38 of them correspond to g-vectors and the remaining one gives a limit ray, which yields an alphabet of 38 rational letters and 5 algebraic ones with the unique four-mass-box square root. We construct the space of integrable symbols with this alphabet and physical first-entry conditions, whose dimension can be reduced using conditions from a truncated version of cluster adjacency. Already at weight 4, by imposing last-entry conditions inspired by the n = 8 double-pentagon integral, we are able to uniquely determine an integrable symbol that gives the algebraic part of the most generic double-pentagon integral. Finally, we locate in the space the n = 8 double-pentagon ladder integrals up to four loops using differential equations derived from Wilson-loop d log forms, and we find a remarkable pattern about the appearance of algebraic letters.


Author(s):  
O. L. Shved ◽  
V. V. Tkachenko

When generalizing the geometrically nonlinear law of Murnaghan elasticity to plasticity, a formally mathematical criterion was introduced for deformational macrofracture (macrocrack appearance) associated with an increase in elastic and plastic anisotropy as a failure cause. The use of the double potentiality of the governing equations in stresses and their velocities made it possible to obtain the reliable information on the structure of the deviatory section of the yield surface, the existence of which is a classical hypothesis in solid mechanics. The normal vector to the surface of the deviatory section is selected from two mutually orthogonal eigenvectors of the constructed operator. There are two families of regular concave surfaces, and a section surface is formed by joining the parts of two representatives of the families at singular points. To select normal vectors, the obtained ratio for them is used for isotropy. In connection with the considered problem of a double simple shift, it is established that multiple eigenvalues appear for the both normal vectors. To unambiguously determine the normal vector at a regular point, it is necessary to exclude the presence of multiple eigenvalues for the both normal vectors at the same time. At a singular point, the appearance of a multiple eigenvalue of one of the normal vectors is still unacceptable. These two conditions are necessary and sufficient to validate the governing equations of the generalized Murnaghan model. Otherwise, a macrocrack occurs. The theoretical construction is supported by the developed software complexes.


Materials ◽  
2021 ◽  
Vol 14 (20) ◽  
pp. 6187
Author(s):  
Alfred Zmitrowicz

Friction models are proposed for anisotropic and heterogeneous dry friction on boundaries of polymer solids. Unit vectors and oriented angles of sliding velocities, radii of curvature and unit normal vectors of sliding trajectories are taken as independent variables in constitutive equations of anisotropic and heterogeneous friction. Heterogeneous dry friction of a polymer pin in pin-on-disc tests is illustrated in the case of Archimedean spiral trajectory. Individual molecular chains composing polymer materials can move inside the material with a high degree of friction anisotropy. The resistance of macromolecule motion is considered with respect to micromechanical models of macromolecules, their kinematics, and friction laws. Two approaches are applied for modeling of anisotropic friction inside polymer materials: continuum-based models (anisotropic viscous friction) and micromechanical models (anisotropic dry friction). Examples of macromolecule dry friction are considered under conditions of spinning and sliding of a disc-like macromolecule and snake-like sliding of a long macromolecule.


2021 ◽  
Vol 12 ◽  
Author(s):  
Shuzhi Wu ◽  
Ping Lin ◽  
Yanyan Zheng ◽  
Yifei Zhou ◽  
Zhaobang Liu ◽  
...  

Located deep in the temporal bone, the semicircular canal is a subtle structure that requires a spatial coordinate system for measurement and observation. In this study, 55 semicircular canal and eyeball models were obtained by segmentation of MRI data. The spatial coordinate system was established by taking the top of the common crus and the bottom of the eyeball as the horizontal plane. First, the plane equation was established according to the centerline of the semicircular canals. Then, according to the parameters of the plane equation, the plane normal vectors were obtained. Finally, the average unit normal vector of each semicircular canal plane was obtained by calculating the average value of the vectors. The standard normal vectors of the and left posterior semicircular canal, superior semicircular canal and lateral semicircular canal were [−0.651, 0.702, 0.287], [0.749, 0.577, 0.324], [−0.017, −0.299, 0.954], [0.660, 0.702, 0.266], [−0.739, 0.588, 0.329], [0.025, −0.279, 0.960]. The different angles for the different ways of calculating the standard normal vectors of the right and left posterior semicircular canal, superior semicircular canal and lateral semicircular canal were 0.011, 0.028, 0.008, 0.011, 0.024, and 0.006 degrees. The technology for measuring the semicircular canal spatial attitudes in this study are reliable, and the measurement results can guide vestibular function examinations and help with guiding the diagnosis and treatment of BPPV.


2021 ◽  
Author(s):  
Amirsaeed Yazdani

Image relighting has emerged as a problem of signif?icant research interest inspired by augmented reality ap?plications. Physics-based traditional methods, as well asblack box deep learning models, have been developed. The existing deep networks have exploited training to achieve a new state of the art; however, they may perform poorly when training is limited or does not represent problem phe?nomenology, such as the addition or removal of dense shad?ows. We propose a model which enriches neural networks with physical insight. More precisely, our method gener?ates the relighted image with new illumination settings via two different strategies and subsequently fuses them using a weight map (w). In the first strategy, our model predicts the material reflectance parameters (albedo) and illumina?tion/geometry parameters of the scene (shading) for the re?lit image (we refer to this strategy as intrinsic image de?composition (IID)). The second strategy is solely based on the black box approach, where the model optimizes its weights based on the ground-truth images and the loss terms in the training stage and generates the relit output directly (we refer to this strategy as direct). While our pro?posed method applies to both one-to-one and any-to-any relighting problems, for each case we introduce problem?specific components that enrich the model performance: 1) For one-to-one relighting we incorporate normal vectors of the surfaces in the scene to adjust gloss and shadows ac?cordingly in the image. 2) For any-to-any relighting, we propose an additional multiscale block to the architecture to enhance feature extraction. Experimental results on the VIDIT 2020 and the VIDIT 2021 dataset (used in the NTIRE 2021 relighting challenge) reveals that our proposal can outperform many state-of-the-art methods in terms of well?known fidelity metrics and perceptual loss


2021 ◽  
Vol 13 (8) ◽  
pp. 168781402110377
Author(s):  
Xigui Wang ◽  
Jie Tang ◽  
Yongmei Wang ◽  
Jiafu Ruan ◽  
Siyuan An

The pre-research project aims to propose a method of optimizing tooth surface modification (TSM) fitting under thermoelastic lubrication (TEL) conditions to reveal the most popular and concerned mechanism issues in the field of mechanical engineering. This is an exploratory study, mainly considering the gear comprehensive error and TSM state of TEL contact interfaces are extremely harsh, which complicates simulation analysis and optimal design. TSM simulation has fitted numerically agreement with optimized results obtained experimentally, which means that they can, whether isolated or by using a multiscale coupling method, start to be adopted to revise, and verify meta-models for thermoelastic characteristics (TECs) under TEL problems. This subject involves the TSM fitting of the theoretical teeth surface superimposed structure, and performs 3D and diagonal modification optimization design, obtains the modified surface position and normal vectors, according to load teeth contact analysis (LTCA), a variety of optimized modification models are established and complex curved surfaces are analyzed to fit the actual gear teeth surface thermoelastic contact numerical simulation, which has been further demonstrated and expressed in the type experiment combined with actual key working conditions and multiple influencing parameters, which is of great significance to the development of modern gear transmission system.


2021 ◽  
Vol 9 ◽  
Author(s):  
Xiao Long Cheng ◽  
Lu Peng Liu ◽  
Jun Xiao ◽  
Qi Hua Zhang ◽  
Jian Xue ◽  
...  

In rock engineering, block theory is a fundamental theory that aims to analyze the finiteness, removability, and mechanical stability of convex blocks under different engineering conditions. In practice, the possible combinations of the fractures and joint sets that may generate key blocks can be identified by stereographic projection graphs of block theory. However, classic key block theory does not provide solutions for nonconvex blocks, which are very common in civil projects, such as those with underground edges, corners, and portals. To enhance the availability of block theory, a general algorithm that can analyze the removability and stability of blocks of arbitrary shapes is proposed in this paper. In the proposed algorithm, the joint pyramid for blocks of arbitrary shapes can be computed, and the faces of the blocks are grouped according to their normal vectors such that parallel or nonadjacent sliding faces with the same normal vector can be immediately identified when the sliding mode is determined. With this algorithm, blocks of arbitrary shapes can be analyzed, and users do not need to have experience interpreting graphs of block theory to take advantage of its accuracy and effectiveness. The proposed algorithm was verified by several benchmarking examples, and it was further applied to investigate the stability of the left bank rock slope of a dam. The results showed that the proposed algorithm is correct, effective, and feasible for use in the design and support of excavation in complex rock masses.


Sign in / Sign up

Export Citation Format

Share Document