A New Development of Multi-to-One Cell-Matching Method and Its Application in VOF Interface Tracking

2005 ◽  
Author(s):  
Yumin Xiao ◽  
R. S. Amano
Keyword(s):  
Unstructured Grid ◽  
Three Dimensional ◽  
Adaptive Mesh ◽  
Test Problems ◽  
Interface Tracking ◽  
Two Dimensional ◽  
Matching Method ◽  
Geometric Information ◽  
Convective Flux ◽  
New Development

A new algorithm—multi-to-one cell matching method for interface tracking in volume-of-fluid (VOF) calculation is presented. This method is based upon unstructured grid and implemented on cells having quadrilaterals or hexahedrons origin. This method utilizes the geometrical characteristic of each vertex in an arbitrary cell to classify the vertex type and to group faces into four (two dimensional) or six (three dimensional) groups. The final regrouped arbitrary cells have the similar geometric information and VOF distributions as that of quadrilaterals or hexahedrons. Convective flux to solve the volume evolution equation can then be exactly evaluated. The method was implemented on unstructured adaptive mesh for VOF simulation. Numerical results for those test problems provide evidence for the algorithm’s quality, and accuracy.

Multi-to-One Cell-Matching Method and Its Application in VOF Interface Tracking

2003 ◽  
Author(s):  
Yumin Xiao ◽  
Sami Bayyuk ◽  
R. S. Amano ◽  
Jianhui Xie
Keyword(s):  
Evolution Equation ◽  
Unstructured Grid ◽  
Three Dimensional ◽  
Adaptive Mesh ◽  
Test Problems ◽  
Interface Tracking ◽  
Two Dimensional ◽  
Matching Method ◽  
Geometric Information ◽  
Convective Flux

A new algorithm—multi-to-one cell matching method for interface tracking in volume-of-fluid (VOF) calculation is presented. This method is based upon unstructured grid and implemented on cells having quadrilaterals or hexahedrons origin. This method utilizes the geometrical characteristic of each vertex in an arbitrary cell to classify the vertex type and to group faces into four (two dimensional) or six (three dimensional) groups. The final regrouped arbitrary cells have the similar geometric information and VOF distributions as that of quadrilaterals or hexahedrons. Convective flux to solve the volume evolution equation can then be exactly evaluated. The method will enable the CFD-ACE+ to be implemented on unstructured adaptive mesh for VOF simulation. Numerical results for those test problems provide evidence for the algorithm’s quality, and accuracy.

Logically rectangular finite volume methods with adaptive refinement on the sphere

2009 ◽  
Vol 367 (1907) ◽  
pp. 4483-4496 ◽  
Author(s):  
Marsha J. Berger ◽  
Donna A. Calhoun ◽  
Christiane Helzel ◽  
Randall J. LeVeque
Keyword(s):  
Finite Volume ◽  
Shallow Water Equations ◽  
Adaptive Mesh Refinement ◽  
Three Dimensional ◽  
Adaptive Mesh ◽  
Finite Volume Methods ◽  
Adaptive Refinement ◽  
Two Dimensional ◽  
Equilibrium Solutions ◽  
Courant Number

The logically rectangular finite volume grids for two-dimensional partial differential equations on a sphere and for three-dimensional problems in a spherical shell introduced recently have nearly uniform cell size, avoiding severe Courant number restrictions. We present recent results with adaptive mesh refinement using the G eo C law software and demonstrate well-balanced methods that exactly maintain equilibrium solutions, such as shallow water equations for an ocean at rest over arbitrary bathymetry.

Improvement of Human Tracking in Stereoscopic Environment Using Subtraction Stereo with Shadow Detection

2011 ◽  
Vol 5 (6) ◽  
pp. 924-931 ◽  
Author(s):  
Kenji Terabayashi ◽  
◽  
Yuma Hoshikawa ◽  
Alessandro Moro ◽  
Kazunori Umeda ◽  
...  
Keyword(s):  
Stereo Matching ◽  
Tracking System ◽  
Three Dimensional ◽  
Shadow Detection ◽  
People Tracking ◽  
Matching Method ◽  
Search Range ◽  
Geometric Information ◽  
Three Dimensional Measurement ◽  
Crowded Environments

The combination of subtraction stereo with shadow detection we propose improves people tracking in stereoscopic environments. Subtraction stereo is a stereo matching method which is fast and robust for the correspondence problem – one of the most serious issues in computer vision – restricting the search range of matching to foreground regions. Shadow detection gives adequate foreground regions of tracked people by removing cast shadows. This leads to accurate three-dimensional measurement of positions in stereoscopic environment tracking. By focusing on disparity images obtained by subtraction stereo, we can detect people easily based on standard labeling. Objects can also be measured directly in size by subtraction stereo without geometric information about environments for tracking. This is important for installing the tracking system easily. To track multiple passing people, we use the extended Kalman filter to address the occlusion problem usually encountered in crowded environments. The proposed method is verified by experiments using unknown stereoscopic environments.

The Solution of Three-Dimensional, Composite Media Heat Conduction Problems by Synthesis Methods

1971 ◽  
Vol 93 (2) ◽  
pp. 221-228 ◽  
Author(s):  
J. B. Yasinsky
Keyword(s):  
Heat Conduction ◽  
Mixed Boundary ◽  
Synthesis Method ◽  
Three Dimensional ◽  
Test Problems ◽  
Synthesis Methods ◽  
Heat Conducting ◽  
Two Dimensional ◽  
Composite Media ◽  
Mixing Coefficients

A method, known as synthesis, is applied to the task of obtaining approximate solutions to the static heat conduction equation for three-dimensional, composite media problems with mixed boundary conditions. The method is based upon an expansion in terms of known two-dimensional solutions of the problem of interest. These known two-dimensional solutions (trial functions) are blended over the remaining dimension by unknown mixing coefficients which are defined by means of variational techniques. A modified canonical variational principle is derived which permits the use of discontinuous trial functions, which expands the class of problems to which the synthesis method can be applied. The equations defining the mixing coefficients are derived in some detail, and the results of several test problems display the potential of this method for analyzing realistic heat conducting systems.

High Resolution Microscopy of Multi-Layered Biological Crystals

1982 ◽  
Vol 40 ◽  
pp. 80-83
Author(s):  
H.A. Cohen ◽  
T.W. Jeng ◽  
W. Chiu
Keyword(s):  
High Resolution ◽  
Low Dose ◽  
Three Dimensional ◽  
Data Interpretation ◽  
Two Dimensional ◽  
Biological Objects ◽  
Density Maps ◽  
Density Map ◽  
Complex Crystal ◽  
High Resolution Microscopy

This tutorial will discuss the methodology of low dose electron diffraction and imaging of crystalline biological objects, the problems of data interpretation for two-dimensional projected density maps of glucose embedded protein crystals, the factors to be considered in combining tilt data from three-dimensional crystals, and finally, the prospects of achieving a high resolution three-dimensional density map of a biological crystal. This methodology will be illustrated using two proteins under investigation in our laboratory, the T4 DNA helix destabilizing protein gp32*I and the crotoxin complex crystal.

Instrumentation For Quantitative Microscopy

1977 ◽  
Vol 35 ◽  
pp. 206-209
Author(s):  
B. Ralph ◽  
A.R. Jones
Keyword(s):  
Volume Fraction ◽  
Three Dimensional ◽  
Two Dimensional ◽  
Automatic Data ◽  
Phase Volume Fraction ◽  
Statistical Confidence ◽  
Resultant Data ◽  
Automatic Data Collection ◽  
Third Dimension ◽  
Evolution Of Microstructure

In all fields of microscopy there is an increasing interest in the quantification of microstructure. This interest may stem from a desire to establish quality control parameters or may have a more fundamental requirement involving the derivation of parameters which partially or completely define the three dimensional nature of the microstructure. This latter categorey of study may arise from an interest in the evolution of microstructure or from a desire to generate detailed property/microstructure relationships. In the more fundamental studies some convolution of two-dimensional data into the third dimension (stereological analysis) will be necessary.In some cases the two-dimensional data may be acquired relatively easily without recourse to automatic data collection and further, it may prove possible to perform the data reduction and analysis relatively easily. In such cases the only recourse to machines may well be in establishing the statistical confidence of the resultant data. Such relatively straightforward studies tend to result from acquiring data on the whole assemblage of features making up the microstructure. In this field data mode, when parameters such as phase volume fraction, mean size etc. are sought, the main case for resorting to automation is in order to perform repetitive analyses since each analysis is relatively easily performed.

A linearity test for thick specimens imaged by HVEM over a 180° angular range

1991 ◽  
Vol 49 ◽  
pp. 552-553
Author(s):  
Yu Liu
Keyword(s):  
Phase Contrast ◽  
Three Dimensional ◽  
Angular Range ◽  
Two Dimensional ◽  
Back Projection ◽  
Line Integral ◽  
Exponential Law ◽  
Transmission Electron ◽  
Absorption Law ◽  
Linearity Test

The image obtained in a transmission electron microscope is the two-dimensional projection of a three-dimensional (3D) object. The 3D reconstruction of the object can be calculated from a series of projections by back-projection, but this algorithm assumes that the image is linearly related to a line integral of the object function. However, there are two kinds of contrast in electron microscopy, scattering and phase contrast, of which only the latter is linear with the optical density (OD) in the micrograph. Therefore the OD can be used as a measure of the projection only for thin specimens where phase contrast dominates the image. For thick specimens, where scattering contrast predominates, an exponential absorption law holds, and a logarithm of OD must be used. However, for large thicknesses, the simple exponential law might break down due to multiple and inelastic scattering.

An Image Reconstruction System Applied to High Voltage Microscopy

1975 ◽  
Vol 33 ◽  
pp. 292-293
Author(s):  
D. E. Johnson
Keyword(s):  
High Voltage ◽  
Prior Information ◽  
Block Diagram ◽  
Three Dimensional ◽  
Real Space ◽  
Two Dimensional ◽  
Efficient Manner ◽  
Fourier Methods ◽  
Tilt Series ◽  
Methods Of Reconstruction

Increased specimen penetration; the principle advantage of high voltage microscopy, is accompanied by an increased need to utilize information on three dimensional specimen structure available in the form of two dimensional projections (i.e. micrographs). We are engaged in a program to develop methods which allow the maximum use of information contained in a through tilt series of micrographs to determine three dimensional speciman structure.In general, we are dealing with structures lacking in symmetry and with projections available from only a limited span of angles (±60°). For these reasons, we must make maximum use of any prior information available about the specimen. To do this in the most efficient manner, we have concentrated on iterative, real space methods rather than Fourier methods of reconstruction. The particular iterative algorithm we have developed is given in detail in ref. 3. A block diagram of the complete reconstruction system is shown in fig. 1.

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