scholarly journals Orebody Modeling from Non-Parallel Cross Sections with Geometry Constraints

Minerals ◽  
2019 ◽  
Vol 9 (4) ◽  
pp. 229 ◽  
Author(s):  
De-Yun Zhong ◽  
Li-Guan Wang ◽  
Ming-Tao Jia ◽  
Lin Bi ◽  
Ju Zhang
Keyword(s):  
Cross Sections ◽  
Adaptive Sampling ◽  
Shape Control ◽  
Correction Algorithm ◽  
Hard Constraint ◽  
Rich Variety ◽  
Interactive Tools ◽  
Reconstruction Methods ◽  
Iterative Correction ◽  
External Position

In this paper, we present an improved approach to the surface reconstruction of orebody from sets of interpreted cross sections that allows for shape control with geometry constraints. The soft and hard constraint rules based on adaptive sampling are proposed. As only the internal and external position relations of sections are calculated, it is unnecessary to estimate the normal directions of sections. Our key contribution is proposing an iterative closest point correction algorithm. It can be used for iterative correction of the distance field based on the constraint rules and the internal and external position relations of the model. We develop a rich variety of geometry constraints to dynamically control the shape trend of orebody for structural geologists. As both of the processes of interpolation and iso-surface extraction are improved, the performance of this method is excellent. Combined with the interactive tools of constraint rules, our approach is shown to be effective on non-trivial sparse sections. We show the reconstruction results with real geological datasets and compare the method with the existing reconstruction methods.

3-D reconstruction and analysis of mammalian mitotic spindle structure

1992 ◽  
Vol 50 (1) ◽  
pp. 578-579
Author(s):  
Kent McDonald ◽  
David Mastronarde ◽  
Rubai Ding ◽  
Eileen O'Toole ◽  
J. Richard McIntosh
Keyword(s):  
Cross Sections ◽  
Mitotic Spindle ◽  
Experimental Studies ◽  
Video Camera ◽  
Three Dimensions ◽  
Mitotic Spindles ◽  
Black And White ◽  
Reconstruction Methods ◽  
Spindle Structure ◽  
Tissue Culture Line

Mammalian spindles are generally large and may contain over a thousand microtubules (MTs). For this reason they are difficult to reconstruct in three dimensions and many researchers have chosen to study the smaller and simpler spindles of lower eukaryotes. Nevertheless, the mammalian spindle is used for many experimental studies and it would be useful to know its detailed structure.We have been using serial cross sections and computer reconstruction methods to analyze MT distributions in mitotic spindles of PtK cells, a mammalian tissue culture line. Images from EM negatives are digtized on a light box by a Dage MTI video camera containing a black and white Saticon tube. The signal is digitized by a Parallax 1280 graphics device in a MicroVax III computer. Microtubules are digitized at a magnification such that each is 10-12 pixels in diameter.

FiXR: a framework to reconstruct fiber cross-sections from X-ray fiber diffraction experiments

2020 ◽  
Vol 76 (2) ◽  
pp. 102-117
Author(s):  
Biel Roig-Solvas ◽  
Dana H. Brooks ◽  
Lee Makowski
Keyword(s):  
Cross Section ◽  
Cross Sections ◽  
Amyloid Β ◽  
Diffraction Theory ◽  
Saxs Data ◽  
Molecular Conformations ◽  
X Ray ◽  
X Ray Scattering ◽  
Reconstruction Methods ◽  
Optimization Heuristics

Ab initio reconstruction methods have revolutionized the capabilities of small-angle X-ray scattering (SAXS), allowing the data-driven discovery of previously unknown molecular conformations, exploiting optimization heuristics and assumptions behind the composition of globular molecules. While these methods have been successful for the analysis of small particles, their impact on fibrillar assemblies has been more limited. The micrometre-range size of these assemblies and the complex interaction of their periodicities in their scattering profiles indicate that the discovery of fibril structures from SAXS measurements requires novel approaches beyond extending existing tools for molecular discovery. In this work, it is proposed to use SAXS measurements, together with diffraction theory, to infer the electron distribution of the average cross-section of a fiber. This cross-section is modeled as a discrete electron density with continuous support, allowing representations beyond binary distributions. Additional constraints, such as non-negativity or smoothness/connectedness, can also be added to the framework. The proposed approach is tested using simulated SAXS data from amyloid β fibril models and using measured data of Tobacco mosaic virus from SAXS experiments, recovering the geometry and density of the cross-sections in all cases. The approach is further tested by analyzing SAXS data from different amyloid β fibril assemblies, with results that are in agreement with previously proposed models from cryo-EM measurements. The limitations of the proposed method, together with an analysis of the robustness of the method and the combination with different experimental sources, are also discussed.

Interface Shape Control in a Cylindrical Directional Solidification Stage

1999 ◽  
Author(s):  
Christopher M. Neils ◽  
Linda J. Hayes ◽  
Kenneth R. Diller
Keyword(s):  
Melting Point ◽  
Numerical Model ◽  
Directional Solidification ◽  
Cross Sections ◽  
Shape Control ◽  
Initial Temperature ◽  
Phase Interface ◽  
Point Of View ◽  
Large Phase ◽  
Solidification Stage

Abstract A numerical model of 1-D heat transfer and freezing in water has been used to support the development of thermal controls for an optical-axis directional solidification stage. By placing the observer’s point of view on the ice growth axis, this new cryostage improves the microsopic resolution with which cross-sections of growing ice dendrites can be observed. This arrangement also permits a large phase interface (1-cm diameter) so that the dendrite dimensions are not constrained by contact with the container surfaces. The numerical model simulated directional solidification with a constant chilling rate on one boundary. When the initial temperature was equal to the melting point, the interface speed was constant. An initial temperature above the melting point led to an accelerating interface when the second boundary was insulated and a decelerating interface when the second boundary temperature was fixed at the initial temperature.

scholarly journals Experimental computer tomograph

2015 ◽  
Vol 1 (1) ◽  
pp. 290-293
Author(s):  
D. Heinemann ◽  
A. Keller ◽  
D. Jannek
Keyword(s):  
Cross Sections ◽  
Low Dose ◽  
Measured Data ◽  
Reconstruction Technique ◽  
Reconstruction Algorithms ◽  
Non Invasive ◽  
The Third ◽  
Construction Design ◽  
Reconstruction Methods ◽  
Set Up

AbstractThe computed tomography is one of the most important medical instruments, allowing the non-invasive visualization of cross sections which are free from superpositions. Since 2000 an experimental computer tomo-graph of the third generation for the purpose of education and research was set up and further developed. Besides the mechanical construction design reconstruction algorithms, including certain corrections of the measured data were developed and implemented. In 2013 iterative reconstruction methods were investigated and implemented for advanced reconstructions and dose reduction using various ray tracing algorithms. The new reconstruction technique leads to improvements in image quality and low dose reconstructions.

Solving Branching Problems for Surface Reconstruction From Free-Form Contours

1999 ◽  
Author(s):  
Jaehun Jeong ◽  
Kwangsoo Kim ◽  
Hyungjun Park
Keyword(s):  
Rapid Prototyping ◽  
Surface Reconstruction ◽  
Cross Sections ◽  
Shape Reconstruction ◽  
New Method ◽  
Experimental Result ◽  
Free Form ◽  
Branching Structures ◽  
Reconstruction Methods ◽  
3D Shape Reconstruction

Abstract The 3D shape reconstruction of an object from its 2D cross-sections is important for reproducing it by NC machining or rapid prototyping. Although several different reconstruction methods have been proposed, most of them have allowed only simple branching, or have had difficulty in handling complex branching structures. In this paper, we present a new method for solving branching problems for reconstructing surfaces from a set of free-form contours in planar cross-sections. In this method, we decompose each multiple branching region into a set of single branching regions by providing a set of intermediary contours using modified distance maps. Then, each pair of contours in the single branching regions is linked with triangular facets. An experimental result is given to show that our method gives reasonably good solutions for the representation of complex-shaped objects from planar contours.

Analysis of STEM micrographs of thick objects

1978 ◽  
Vol 36 (2) ◽  
pp. 106-107
Author(s):  
S. Golladay
Keyword(s):  
Inelastic Scattering ◽  
Multiple Scattering ◽  
Mass Distribution ◽  
Cross Sections ◽  
Phase Contrast ◽  
Image Point ◽  
Contrast Effects ◽  
Total Cross Sections ◽  
Elastic And Inelastic Scattering

The theory of multiple scattering has been worked out by Groves and comparisons have been made between predicted and observed signals for thick specimens observed in a STEM under conditions where phase contrast effects are unimportant. Independent measurements of the collection efficiencies of the two STEM detectors, calculations of the ratio σe/σi = R, where σe, σi are the total cross sections for elastic and inelastic scattering respectively, and a model of the unknown mass distribution are needed for these comparisons. In this paper an extension of this work will be described which allows the determination of the required efficiencies, R, and the unknown mass distribution from the data without additional measurements or models. Essential to the analysis is the fact that in a STEM two or more signal measurements can be made simultaneously at each image point.

Direct Observation of Heat Exchanger Deposits by Cross Sectioning

1967 ◽  
Vol 25 ◽  
pp. 364-365
Author(s):  
R. W. Anderson ◽  
D. L. Senecal
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Heat Exchanger ◽  
Direct Observation ◽  
Cross Sections ◽  
Preparation Method ◽  
Specimen Preparation ◽  
Flowing Water ◽  
Transmission Electron ◽  
Deposit Layer

A problem was presented to observe the packing densities of deposits of sub-micron corrosion product particles. The deposits were 5-100 mils thick and had formed on the inside surfaces of 3/8 inch diameter Zircaloy-2 heat exchanger tubes. The particles were iron oxides deposited from flowing water and consequently were only weakly bonded. Particular care was required during handling to preserve the original formations of the deposits. The specimen preparation method described below allowed direct observation of cross sections of the deposit layers by transmission electron microscopy.The specimens were short sections of the tubes (about 3 inches long) that were carefully cut from the systems. The insides of the tube sections were first coated with a thin layer of a fluid epoxy resin by dipping. This coating served to impregnate the deposit layer as well as to protect the layer if subsequent handling were required.

An Analysis of Dissociation of Molecules in a High Resolution Electron Microscope

1973 ◽  
Vol 31 ◽  
pp. 486-487
Author(s):  
Mihir Parikh
Keyword(s):  
Electron Microscope ◽  
High Resolution ◽  
Cross Sections ◽  
Resolving Power ◽  
Peak Intensity ◽  
Molecular Film ◽  
Resolution Electron ◽  
Dissociation Cross Section ◽  
High Resolution Electron Microscope ◽  
The Stability

It is well known that the resolution of bio-molecules in a high resolution electron microscope depends not just on the physical resolving power of the instrument, but also on the stability of these molecules under the electron beam. Experimentally, the damage to the bio-molecules is commo ly monitored by the decrease in the intensity of the diffraction pattern, or more quantitatively by the decrease in the peaks of an energy loss spectrum. In the latter case the exposure, EC, to decrease the peak intensity from IO to I’O can be related to the molecular dissociation cross-section, σD, by EC = ℓn(IO /I’O) /ℓD. Qu ntitative data on damage cross-sections are just being reported, However, the microscopist needs to know the explicit dependence of damage on: (1) the molecular properties, (2) the density and characteristics of the molecular film and that of the support film, if any, (3) the temperature of the molecular film and (4) certain characteristics of the electron microscope used

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