Quantitative Material Contrast

Secondary (SE) and backscattered electron (BSE) signals in the SEM provide high resolution monochrome images. BSE signal strength is modulated by mean atomic number and ‘false” colour can be introduced to enhance material contrast. Colour can also be introduced using multiple SE detectors, each with a different sensitivity to topographic and compositional information: by controlling signal mixtures and colours, the operator effectively has access to a powerful “studio” to generate aesthetically pleasing colour images. In both these examples, the correspondence between local elemental content and colour is entirely arbitrary and under subjective control of the operator, Elemental x-ray maps can be acquired and combinations colour coded to reveal phase distributions. For large numbers of maps and images, chemometric techniques such as PCA may be used to discover common relationships and assist the process of colour coding. Images derived from x-ray maps are usually low resolution and the analyst has to decide which elements to include and do a fair amount of data manipulation before any conclusions can be drawn.

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Topographic and material contrast in low-voltage scanning electron microscopy

Scanning ◽

10.1002/sca.4950170607 ◽

2006 ◽

Vol 17 (6) ◽

pp. 387-394 ◽

Cited By ~ 9

Author(s):

J. Hejna

Keyword(s):

Electron Microscopy ◽

Scanning Electron Microscopy ◽

Low Voltage ◽

Material Contrast ◽

Voltage Scanning ◽

Scanning Electron

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Non-monotonic material contrast in scanning ion and scanning electron images

Ultramicroscopy ◽

10.1016/j.ultramic.2011.08.016 ◽

2011 ◽

Vol 111 (11) ◽

pp. 1564-1573 ◽

Cited By ~ 4

Author(s):

L.A. Giannuzzi ◽

M. Utlaut

Keyword(s):

Material Contrast ◽

Scanning Electron

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Sequences of seismic and aseismic slip on bimaterial faults show dominant rupture asymmetry and potential for elevated seismic hazard

10.31223/x54c9v ◽

2021 ◽

Author(s):

Mohamed Abdelmeguid ◽

Ahmed Elbanna

Keyword(s):

Seismic Hazard ◽

Normal Stress ◽

Nucleation Site ◽

Rupture Propagation ◽

Aseismic Slip ◽

Earthquake Physics ◽

Slip Rates ◽

Seismicity Pattern ◽

Sequence Of Events ◽

Material Contrast

We perform numerical simulations of sequences of earthquake and aseismic slip on planar rate and state faults separating dissimilar material within the 2-D plane strain approximation. We resolve all stages of the earthquake cycle from aseismic slip to fast ruptures while incorporating full inertia effects during seismic event propagation. We show that bimaterial coupling results in favorable nucleation site and subsequent asymmetric rupture propagation. We demonstrate that increasing the material contrast enhances this asymmetry leading to higher slip rates and normal stress drops in the preferred rupture propagation direction. The normal stress drop, induced by the bimaterial effect, leads to strong dynamic weakening of the fault and may destabilize the creeping region on a heterogeneous rate and state fault, resulting in extended rupture propagation. Such rupture penetration into creeping patches may lead to more frequent opening of earthquake gates, causing increased seismic hazard. Furthermore, bimaterial coupling may lead to irregular seismicity pattern in terms of event length, peak slip rates,and hypocenter location, depending on the properties of the creeping patches bordering the seismogenically active part of the fault . Our results highlight robust characteristics of bimaterial interfaces that persist over long sequence of events and suggest the need for further exploration of the role of material contrast in earthquake physics and models of seismic hazard.

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Features of metallurgy waste mainly processing with account for raw material contrast

E3S Web of Conferences ◽

10.1051/e3sconf/202019202026 ◽

2020 ◽

Vol 192 ◽

pp. 02026

Author(s):

Alexander Burdonov ◽

Vyacheslav Barakhtenko ◽

Konstantin Prokhorov ◽

Yuri Novikov

Keyword(s):

Particle Size ◽

Raw Materials ◽

Spectroscopic Studies ◽

Raw Material ◽

Mineralogical Analysis ◽

Fundamental Factor ◽

Fundamental Possibility ◽

Material Contrast ◽

Two Phases ◽

Finely Dispersed Powder

This work presents research studies of alumina-containing estimates formed during the production of aluminum on electrolyzers with self-burning anodes during technological operations at PJSC RUSAL Bratsk. Material from the territory of the electrolysis workshop, with a mark of ± 0, is a mixture of finely dispersed powder, 2.5 mm in size (on average 62.78% by weight) with pieces of material from 0.5 to 6 cm in size. , 26% by weight). As a result of the work, the particle size and chemical-metallurgical properties of an alumina-containing estimate were studied. During the research, the content of valuable components and impurities in the sample of various classes was determined. In the process of mineralogical analysis, two phases were identified in the products: dark, black-gray and light, grayish-white. It is proved that these phases have significant differences in the chemical composition of the feed. Spectroscopic studies showed significant differences in the colorimetric characteristics of the raw materials, which is a fundamental factor for the use of photometric separation. Based on preliminary studies on the separation of alumina-containing estimates by photometric separation, the fundamental possibility of purifying contaminated material from technological impurities has been established.

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Homogenization of Random Porous Materials With Low-Order Virtual Elements

ASCE-ASME J Risk and Uncert in Engrg Sys Part B Mech Engrg ◽

10.1115/1.4043475 ◽

2019 ◽

Vol 5 (3) ◽

Author(s):

Marco Pingaro ◽

Emanuele Reccia ◽

Patrizia Trovalusci

Keyword(s):

Elastic Moduli ◽

Volume Element ◽

Homogenization Procedure ◽

Virtual Element Method ◽

Low Contrast ◽

Statistical Homogenization ◽

Random Composites ◽

Material Contrast ◽

Virtual Element ◽

Definition Of

A fast statistical homogenization procedure (FSHP) based on virtual element method (VEM)—previously developed by the authors has been successfully adopted for the homogenization of particulate random composites, via the definition of the representative volume element (RVE), and of the related equivalent elastic moduli. In particular, the adoption of virtual elements of degree one for modeling the inclusions provided reliable results for materials with low contrast, defined as the ratio between mechanical properties of inclusions and matrix. Porous media are then here described as bimaterial systems in which soft circular inclusions, with a very low value of material contrast, are randomly distributed in a continuous stiffer matrix. Several simulations have been performed by varying the level of porosity, highlighting the effectiveness of FSHP in conjunction with virtual elements of degree one.

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