scholarly journals Three-Dimensional Inversion of Borehole-Surface Resistivity Method Based on the Unstructured Finite Element

2021 ◽  
Vol 2021 ◽  
pp. 1-13
Author(s):  
Zhi Wang ◽  
Sinan Fang
Keyword(s):  
Numerical Solution ◽  
Surface Topography ◽  
Current Source ◽  
Three Dimensional ◽  
Surface Resistivity ◽  
Normal Equation ◽  
Inversion Algorithm ◽  
Field Source ◽  
Resistivity Method ◽  
Borehole Surface

The electromagnetic wave signal from the electromagnetic field source generates induction signals after reaching the target geological body through the underground medium. The time and spatial distribution rules of the artificial or the natural electromagnetic fields are obtained for the exploration of mineral resources of the subsurface and determining the geological structure of the subsurface to solve the geological problems. The goal of electromagnetic data processing is to suppress the noise and improve the signal-to-noise ratio and the inversion of resistivity data. Inversion has always been the focus of research in the field of electromagnetic methods. In this paper, the three-dimensional borehole-surface resistivity method is explored based on the principle of geometric sounding, and the three-dimensional inversion algorithm of the borehole-surface resistivity method in arbitrary surface topography is proposed. The forward simulation and calculation start from the partial differential equation and the boundary conditions of the total potential of the three-dimensional point current source field are satisfied. Then the unstructured tetrahedral grids are used to discretely subdivide the calculation area that can well fit the complex structure of subsurface and undulating surface topography. The accuracy of the numerical solution is low due to the rapid attenuation of the electric field at the point current source and the nearby positions and sharply varying potential gradients. Therefore, the mesh density is defined at the local area, that is, the vicinity of the source electrode and the measuring electrode. The mesh refinement can effectively reduce the influence of the source point and its vicinity and improve the accuracy of the numerical solution. The stiffness matrix is stored with Compressed Row Storage (CSR) format, and the final large linear equations are solved using the Super Symmetric Over Relaxation Preconditioned Conjugate Gradient (SSOR-PCG) method. The quasi-Newton method with limited memory (L_BFGS) is used to optimize the objective function in the inversion calculation, and a double-loop recursive method is used to solve the normal equation obtained at each iteration in order to avoid computing and storing the sensitivity matrix explicitly and reduce the amount of calculation. The comprehensive application of the above methods makes the 3D inversion algorithm efficient, accurate, and stable. The three-dimensional inversion test is performed on the synthetic data of multiple theoretical geoelectric models with topography (a single anomaly model under valley and a single anomaly model under mountain) to verify the effectiveness of the proposed algorithm.

Three-dimensional numerical solution for wear prediction using a mortar contact algorithm

2013 ◽  
Vol 96 (8) ◽  
pp. 467-486 ◽  
Author(s):  
F. J. Cavalieri ◽  
A. Cardona
Keyword(s):  
Numerical Solution ◽  
Three Dimensional ◽  
Wear Prediction ◽  
Contact Algorithm

scholarly journals Combining 3D Structured Light Imaging and Spine X-ray Data Improves Visualization of the Spinous Lines in the Scoliotic Spine

2020 ◽  
Vol 11 (1) ◽  
pp. 301
Author(s):  
Sławomir Paśko ◽  
Wojciech Glinkowski
Keyword(s):  
Radiation Exposure ◽  
Surface Topography ◽  
Structured Light ◽  
Spinous Process ◽  
Three Dimensional ◽  
Diagnostic System ◽  
Measurement Tool ◽  
Adequate Treatment ◽  
X Ray ◽  
Spinous Processes

Scoliosis is a three-dimensional trunk and spinal deformity. Patient evaluation is essential for the decision-making process and determines the selection of specific and adequate treatment. The diagnosis requires a radiological evaluation that exposes patients to radiation. This exposure reaches hazardous levels when numerous, repetitive radiographic studies are required for diagnostics, monitoring, and treatment. Technological improvements in radiographic devices have significantly reduced radiation exposure, but the risk for patients remains. Optical three-dimensional surface topography (3D ST) measurement systems that use surface topography (ST) to screen, diagnose, and monitor scoliosis are safer alternatives to radiography. The study aimed to show that the combination of plain X-ray and 3D ST scans allows for an approximate presentation of the vertebral column spinous processes line in space to determine the shape of the spine’s deformity in scoliosis patients. Twelve patients diagnosed with scoliosis, aged 13.1 ± 4.5 years (range: 9 to 20 years) (mean: Cobb angle 17.8°, SD: ±9.5°) were enrolled in the study. Patients were diagnosed using full-spine X-ray and whole torso 3D ST. The novel three-dimensional assessment of the spinous process lines by merging 3D ST and X-ray data in patients with scoliosis was implemented. The method’s expected uncertainty is less than 5 mm, which is better than the norm for a standard measurement tool. The presented accuracy level is considered adequate; the proposed solution is accurate enough to monitor the changes in the shape of scoliosis’s spinous processes line. The proposed method allows for a relatively precise calculation of the spinous process lines based on a three-dimensional point cloud obtained with a four-directional, three-dimensional structured light diagnostic system and a single X-ray image. The method may help reduce patients’ total radiation exposure and avoid one X-ray in the sagittal projection if biplanar radiograms are required for reconstructing the three-dimensional line of the spinous processes line.

Comparing analytical and numerical solution of nonlinear two and three-dimensional hydrostatic flows

2007 ◽  
Vol 53 (6) ◽  
pp. 1049-1062 ◽  
Author(s):  
Vincenzo Casulli ◽  
Paola Zanolli
Keyword(s):  
Numerical Solution ◽  
Three Dimensional

Three-dimensional numerical solution of eddy currents in thin plates

1975 ◽  
Vol 122 (6) ◽  
pp. 681 ◽  
Author(s):  
C.J. Carpenter ◽  
M. Djurović
Keyword(s):  
Numerical Solution ◽  
Eddy Currents ◽  
Three Dimensional ◽  
Thin Plates

A numerical and experimental investigation on the evolution of three-dimensional surface topography of 12Cr2Ni4A steel in shot peening

2021 ◽  
Vol 70 ◽  
pp. 259-270
Author(s):  
Jiuyue Zhao ◽  
Jinyuan Tang ◽  
Han Ding ◽  
Wen Shao ◽  
Xing Zhao ◽  
...  
Keyword(s):  
Experimental Investigation ◽  
Surface Topography ◽  
Shot Peening ◽  
Three Dimensional ◽  
Dimensional Surface

Study on Feed Offset in Elliptical Vibration Cutting

2014 ◽  
Vol 490-491 ◽  
pp. 600-606
Author(s):  
Jie Qiong Lin ◽  
Jin Guo Han ◽  
Dan Jing ◽  
Xian Jing
Keyword(s):  
Surface Topography ◽  
Surface Quality ◽  
Simulation Analysis ◽  
Three Dimensional ◽  
Curved Surface ◽  
Elliptical Vibration Cutting ◽  
Vibration Cutting ◽  
Elliptical Vibration ◽  
Tool Edge

Elliptical vibration cutting (EVC) process and three dimensional cutting surfaces are analyzed in this paper to understand the formation of surface topography. The model of EVC surface topography is established based on curved surface remove function under the assumption that the tool edge is sharp enough. And simulation analysis of surface topography is conducted with different feed offset ratios. Results indicate that RMS change with feed offset ratios λ. The range of RMS is larger when feed offset ratio ranges from both 0 to 0.4 and 0.6 to 1, while the range is smaller when feed offset ratio changes from 0.4 to 0.6. Whats more, RMS reaches the minimum when feed offset ratio is 0.5. The present research provides some references for reducing the height of vibration ripples and improving EVC surface quality.

Three-dimensional surface topography segmentation through clustering

Wear ◽  
2007 ◽  
Vol 262 (3-4) ◽  
pp. 395-410 ◽  
Author(s):  
N. Senin ◽  
M. Ziliotti ◽  
R. Groppetti
Keyword(s):  
Surface Topography ◽  
Three Dimensional ◽  
Dimensional Surface

scholarly journals On the Two-Scale Modelling of Elastohydrodynamic Lubrication in Tilted-Pad Bearings

Lubricants ◽  
2018 ◽  
Vol 6 (3) ◽  
pp. 78 ◽  
Author(s):  
Gregory de Boer ◽  
Andreas Almqvist
Keyword(s):  
Surface Topography ◽  
Load Capacity ◽  
Three Dimensional ◽  
Elastohydrodynamic Lubrication ◽  
Multiscale Methods ◽  
Operating Conditions ◽  
Real Surface ◽  
Micro Scale ◽  
Macro Scale ◽  
Heterogeneous Multiscale

A two-scale method for modelling the Elastohydrodynamic Lubrication (EHL) of tilted-pad bearings is derived and a range of solutions are presented. The method is developed from previous publications and is based on the Heterogeneous Multiscale Methods (HMM). It facilitates, by means of homogenization, incorporating the effects of surface topography in the analysis of tilted-pad bearings. New to this article is the investigation of three-dimensional bearings, including the effects of both ideal and real surface topographies, micro-cavitation, and the metamodeling procedure used in coupling the problem scales. Solutions for smooth bearing surfaces, and under pure hydrodynamic operating conditions, obtained with the present two-scale EHL model, demonstrate equivalence to those obtained from well-established homogenization methods. Solutions obtained for elastohydrodynamic operating conditions, show a dependency of the solution to the pad thickness and load capacity of the bearing. More precisely, the response for the real surface topography was found to be stiffer in comparison to the ideal. Micro-scale results demonstrate periodicity of the flow and surface topography and this is consistent with the requirements of the HMM. The means of selecting micro-scale simulations based on intermediate macro-scale solutions, in the metamodeling approach, was developed for larger dimensionality and subsequent calibration. An analysis of the present metamodeling approach indicates improved performance in comparison to previous studies.

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