scholarly journals A Surface Geometry Model for LiDAR Depth Completion

Author(s):  
Yiming Zhao ◽  
Lin Bai ◽  
Ziming Zhang ◽  
Xinming Huang
1998 ◽  
Vol 122 (1) ◽  
pp. 71-77 ◽  
Author(s):  
Charalabos Doumanidis ◽  
Eleni Skordeli

Recent solid freeform fabrication methods generate 3D solid objects by material deposition in successive layers made of adjacent beads. Besides numerical simulation, this article introduces an analytical model of such material addition, using superposition of unit deposition distributions, composed of elementary spherical primitives consistent with the mass transfer physics. This real-time surface geometry model, with its parameters identified by in-process profile measurements, is used for Smith-prediction of the material shape in the unobservable deposition region. The model offers the basis for a distributed-parameter geometry control scheme to obtain a desired surface topology, by modulating the feed and motion of a moving mass source. The model was experimentally tested on a fused wire deposition welding station, using optical sensing by a scanning laser stripe. Its applications to other rapid prototyping methods are discussed. [S0022-0434(00)02301-7]


2014 ◽  
Vol 800-801 ◽  
pp. 342-347
Author(s):  
Min Li Zheng ◽  
Jin Hui Xu ◽  
Wei Zhang ◽  
Zhao Xing Zhang ◽  
Tong Wu

Mould surface loading state is one of the most important factors which would affect the mould performance in the course of service. According to the established hardened steel milling surface geometry model, a bending forming numerical simulation of hardened steel milling is conducted, the influence law of service process surface load state is analyzed under machined surface geometry structure which is formed by different milling parameters. The research results show: surface load concentrated area is mainly focusing on mould edge transition and fillet in the course of service; the surface geometry structure has an important influence on the mould service load in the course of service, service load more smaller which is more helpful to improve the mould service performance in the course of service.


Author(s):  
Martin B. Hamper ◽  
Conrad Ruppert ◽  
Cheng Wei ◽  
Ahmed A. Shabana

Contact between the wheel and rail can have a significant effect on the dynamics of vehicle/track interaction models. Many existing rail surface models rely on curve based geometry which may lead to some geometric inaccuracy in the case of variable cross-section rails. This investigation will focus on the development of a new spatial geometry based rail surface description which reduces this geometric inaccuracy. It has been shown in literature that certain CAD geometry types, such as B-Spline curves and surfaces, may be converted to equivalent absolute nodal coordinate formulation (ANCF) finite elements without a loss of geometric accuracy. To this end, a new ANCF surface description of variable cross-section rails is developed. This investigation also demonstrates the feasibility of using, in the future, 3D surface scanning techniques as well as profile curve measurements to develop a rail surface geometry model using the new ANCF surface which can be systematically integrated with complex multibody system (MBS) models. A realistic railroad vehicle example of a turnout, which includes variable cross-section rails, is tested for the case of the new ANCF surface. A study of the numerical results reveals the benefits of using the ANCF surface geometry developed in this investigation.


2013 ◽  
Vol 690-693 ◽  
pp. 2990-2993 ◽  
Author(s):  
Hui Wang ◽  
Jin Ning Nie ◽  
Peng Wang ◽  
Peng Hui Guo

In this paper, structure characteristics of frame on towing machine were analyzed. Based on shell element as the meshing type, finite element surface geometry model was established. The forms of loading on towing condition were studied, it is confirmed that drum was simplified as the key point on towing condition, and then the load was transmitted by rigid connection which got key point and frame connected together; and the load was applied at centre of gravity of parts; based on the safety performance on different conditions verified by finite element analysis, the structure improvement advice was proposed for frame.


2014 ◽  
Vol 1017 ◽  
pp. 44-49 ◽  
Author(s):  
Yong Qing Wang ◽  
B. Hou ◽  
Q. Ma ◽  
H.B. Liu ◽  
Xian Jun Sheng

Belt grinding is characterized by elastic contact grinding. Generally, the non-uniform material in complex machining area could be removed by repeated grinding or longer dwell-time grinding to obtain the required grinding capacity, which leads to low efficiency, difficult dimension accuracy control and poor surface quality. It should be considered thoroughly surface geometry, grinding force and system stiffness in surface belt grinding. Belt grinding parameters can be then dynamically adjusted. This paper focuses on controlling material removal efficiently and uniformly in marine propeller belt grinding. The material removal process is modelled considering elastic contact between grinding wheel and workpiece. Then, a grinding depth and grinding dwell time control strategy of surface belt grinding is proposed based on rigid-flexible coupled analysis. The variable feed grinding experiments were carried out on the developed five-axis CNC belt grinding machine integrated measuring and machining. The marine propeller with cast aluminum bronze (ZCuAl8Mn13Fe3Ni2) was employed to validate the proposed controllable material removal strategy. It is shown that the proposed strategy is feasible and efficient.


2018 ◽  
Vol 781 ◽  
pp. 165-169
Author(s):  
Alexey Kalinichenko ◽  
Irina Lobanova ◽  
Vladimir Meshheryakov ◽  
Anatoly Surzhikov

Nondestructive penetrant testing is effective, and in some cases, it is the only possible method of accidents prevention at high-risk sites. But in nowadays liquid-filled discontinuity model has not been adequately studied. Hydrodynamics in the open-end capillaries characterize the flow of liquids using the methods of leak detection. To detect surface discontinuities that are capillary, capillary flaw detection methods are used. Until now, the theoretical relation l = l (t) has not been find out. This relation makes it possible to calculate the absorption kinetics in any capillary at all its stages, which would coincide with experimental data with high accuracy. The studies show that the time of filling the capillaries by liquid is usually higher than the theoretically predicted one. Therefore, revealing the regularities of filling capillaries with liquids to the maximum depth and the duration of filling the capillary with liquid by a given depth is an actual task. The authors suggest a model for determining the velocity of fluid in dead-end and open-end and through capillaries, which take into account the fractal topology of the surface.


2005 ◽  
Vol 3 (4) ◽  
pp. 471-486 ◽  
Author(s):  
Sambit Datta ◽  
David Beynon

Recovering the control or implicit geometry underlying temple architecture requires bringing together fragments of evidence from field measurements, relating these to mathematical and geometric descriptions in canonical texts and proposing “best-fit” constructive models. While scholars in the field have traditionally used manual methods, the innovative application of niche computational techniques can help extend the study of artefact geometry. This paper demonstrates the application of a hybrid computational approach to the problem of recovering the surface geometry of early temple superstructures. The approach combines field measurements of temples, close-range architectural photogrammetry, rule-based generation and parametric modelling. The computing of surface geometry comprises a rule-based global model governing the overall form of the superstructure, several local models for individual motifs using photogrammetry and an intermediate geometry model that combines the two. To explain the technique and the different models, the paper examines an illustrative example of surface geometry reconstruction based on studies undertaken on a tenth century stone superstructure from western India. The example demonstrates that a combination of computational methods yields sophisticated models of the constructive geometry underlying temple form and that these digital artefacts can form the basis for in depth comparative analysis of temples, arising out of similar techniques, spread over geography, culture and time.


2019 ◽  
Vol 2019 (1) ◽  
pp. 37-42
Author(s):  
Davit Gigilashvili ◽  
Jean-Baptiste Thomas ◽  
Marius Pedersen ◽  
Jon Yngve Hardeberg

Gloss is widely accepted as a surface- and illuminationbased property, both by definition and by means of metrology. However, mechanisms of gloss perception are yet to be fully understood. Potential cues generating gloss perception can be a product of phenomena other than surface reflection and can vary from person to person. While human observers are less likely to be capable of inverting optics, they might also fail predicting the origin of the cues. Therefore, we hypothesize that color and translucency could also impact perceived glossiness. In order to validate our hypothesis, we conducted series of psychophysical experiments asking observers to rank objects by their glossiness. The objects had the identical surface geometry and shape but different color and translucency. The experiments have demonstrated that people do not perceive objects with identical surface equally glossy. Human subjects are usually able to rank objects of identical surface by their glossiness. However, the strategy used for ranking varies across the groups of people.


Sensors ◽  
2021 ◽  
Vol 21 (11) ◽  
pp. 3857
Author(s):  
Jakub Lorencki ◽  
Stanisław Radkowski ◽  
Szymon Gontarz

The article compares the results of experimental and modelling research of switched reluctance motor at two different operational states: one proper and one with mechanical fault, i.e., with dynamic eccentricity of the rotor. The experiments were carried out on a test bench and then the results were compared with mathematical modelling of quasi-static and dynamic analysis of 2D geometry model. Finally, it was examined how the operation with dynamic eccentricity fault of the motor affected its main physical parameter—the phase current. The analysis was presented in the frequency domain using the Fast Fourier Transform (FFT); however, individual current waveforms in the time domain are also shown for comparison. Applying results of the research could increase reliability of the maintenance of SRM and enhance its application in vehicles for special purposes as well as its military and industrial applications.


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