Effects of resolution on the measurement of grain ‘size’

1985 ◽  
Vol 49 (353) ◽  
pp. 539-546 ◽  
Author(s):  
R. Dearnley
Keyword(s):  
Grain Size ◽  
Image Analysis ◽  
Grain Boundary ◽  
Surface Area ◽  
Unit Volume ◽  
Fractal Dimensions ◽  
Size Analysis ◽  
Automatic Image Analysis ◽  
Fine Grained ◽  
Kinetics Of

AbstractMeasurements of fine-grained dolerites by optical automatic image analysis are used to illustrate the effects of magnification and resolution on the values obtained for grain ‘size’, grain boundary length, surface area per unit volume, and other parameters. Within the measured range of optical magnifications (× 26 to × 3571) and resolutions (1.20 × 10−3 cm to 8.50 × 10−6 cm), it is found that the values of all grain parameters estimated by chord size analysis vary with magnification. These results are interpreted in terms of the concepts of ‘fractal dimensions’ introduced by Mandelbrot (1967, 1977). For some comparative purposes the fractal relationships may be of little significance as relative changes of size, surface area, and other parameters can be expressed adequately at given magnification(s). But for many studies, for instance in kinetics of grain growth, the actual diameter or surface area per unit volume is an important dimension. The consequences are disconcerting and suggest that it may be difficult in some instances to specify the ‘true’ measurements of various characteristics of fine-grained aggregates.

Grain size and grain boundary character distribution in ultra-fine grained (ECAP) nickel

2008 ◽  
Vol 491 (1-2) ◽  
pp. 1-7 ◽  
Author(s):  
K. Sitarama Raju ◽  
M. Ghanashyam Krishna ◽  
K.A. Padmanabhan ◽  
K. Muraleedharan ◽  
N.P. Gurao ◽  
...  
Keyword(s):  
Grain Size ◽  
Grain Boundary ◽  
Grain Boundary Character Distribution ◽  
Boundary Character ◽  
Fine Grained ◽  
Grain Boundary Character ◽  
Character Distribution ◽  
Boundary Character Distribution

scholarly journals Grain size statistics and depositional pattern of the Ecca Group sandstones, Karoo Supergroup in the Eastern Cape Province, South Africa

2017 ◽  
Vol 9 (1) ◽  
Author(s):  
Christopher Baiyegunhi ◽  
Kuiwu Liu ◽  
Oswald Gwavava
Keyword(s):  
South Africa ◽  
Grain Size ◽  
Depositional Environments ◽  
Energy Conditions ◽  
Grain Size Analysis ◽  
Size Analysis ◽  
Equal Proportion ◽  
Eastern Cape Province ◽  
Eastern Cape ◽  
Fine Grained

AbstractGrain size analysis is a vital sedimentological tool used to unravel the hydrodynamic conditions, mode of transportation and deposition of detrital sediments. In this study, detailed grain-size analysis was carried out on thirty-five sandstone samples from the Ecca Group in the Eastern Cape Province of South Africa. Grain-size statistical parameters, bivariate analysis, linear discriminate functions, Passega diagrams and log-probability curves were used to reveal the depositional processes, sedimentation mechanisms, hydrodynamic energy conditions and to discriminate different depositional environments. The grain-size parameters show that most of the sandstones are very fine to fine grained, moderately well sorted, mostly near-symmetrical and mesokurtic in nature. The abundance of very fine to fine grained sandstones indicate the dominance of low energy environment. The bivariate plots show that the samples are mostly grouped, except for the Prince Albert samples that show scattered trend, which is due to the either mixture of two modes in equal proportion in bimodal sediments or good sorting in unimodal sediments. The linear discriminant function analysis is dominantly indicative of turbidity current deposits under shallow marine environments for samples from the Prince Albert, Collingham and Ripon Formations, while those samples from the Fort Brown Formation are lacustrine or deltaic deposits. The C-M plots indicated that the sediments were deposited mainly by suspension and saltation, and graded suspension. Visher diagrams show that saltation is the major process of transportation, followed by suspension.

Electrical properties of ultrafine-grained yttria-stabilized zirconia ceramics

1997 ◽  
Vol 12 (9) ◽  
pp. 2374-2380 ◽  
Author(s):  
Shusheng Jiang ◽  
Walter A. Schulze ◽  
Vasantha R. W. Amarakoon ◽  
Gregory C. Stangle
Keyword(s):  
Grain Size ◽  
Oxygen Vacancy ◽  
Grain Boundary ◽  
Oxygen Vacancies ◽  
Synthesis Process ◽  
Physical Parameters ◽  
Fine Grained ◽  
Oxygen Ion ◽  
Average Grain Size ◽  
Vacancy Concentrations

Nanoparticles of yttria-doped tetragonal zirconia polycrystalline ceramics (Y-TZP) with an average crystallite size of less than 9 nm were prepared by a combustion synthesis process. Dense and fine-grained (<200 nm) Y-TZP ceramics were obtained by fast-firing using temperatures lower than 1400 °C and dwell times of less than 2 min. Impedance spectroscopy was employed to measure conductivities of oxygen vacancies in the grain and the grain boundary of the fine-grained Y-TZP. The relationships between the concentration of the oxygen vacancies in the grain boundary and measurable physical parameters were determined semiquantitatively. The oxygen vacancy concentrations and activation energies for the oxygen-ion conduction in the grain and the grain boundary of the fine-grained Y-TZP were found to be independent of the average grain size in the average grain-size range of 90–200 nm. These experimental results suggest that, in order to retain the abnormally high oxygen vacancy concentrations of the Y-TZP nanoparticles and thus enhance the oxygen-ion conductivity, it may be necessary to decrease the average grain size to approximately 10 nm.

scholarly journals On the Origin of Ultramylonites

2020 ◽  
Author(s):  
Jacques Précigout
Keyword(s):  
Grain Size ◽  
Grain Boundary ◽  
Host Rock ◽  
Shear Zones ◽  
Smooth Transition ◽  
Seismogenic Zone ◽  
Fine Grained ◽  
Lattice Preferred Orientation ◽  
Dislocation Densities ◽  
Creep Cavitation

&lt;p&gt;&lt;span&gt;Deformation of lithospheric rocks regularly localizes into high-strain shear zones that include fine-grained ultramylonites. Occurring as quasi-straight layers of intimately mixed phases that often describe sharp transitions with the host rock, these structures may channelize fluid flow&lt;strong&gt;&lt;sup&gt;[1,2]&lt;/sup&gt;&lt;/strong&gt; and could serve as precursors for deep earthquakes&lt;strong&gt;&lt;sup&gt;[3]&lt;/sup&gt;&lt;/strong&gt;. However, although intensively documented, ultramylonites originate from still unknown processes. Here I focus on a mylonitic complex that includes numerous mantle ultramylonites in the Ronda peridotite (Spain). Among them, I was able to highlight one of their precursors that I better describe as a long and straight grain boundary, along which four-grain junctions are observed with randomly oriented grains of olivine and pyroxenes. This precursor starts from a pyroxene porphyroclast and extends to an incipient, weakly undulated ultramylonite, where intimate phase mixing arises with asymmetrical grain size distribution. While the finer grain size locates on one side, describing a sharp &amp;#8211; but continuous &amp;#8211; transition with the host rock, the grain size gradually increases towards the other side, giving rise to a smooth transition. All phases have a very weak lattice preferred orientation (LPO) in the ultramylonite, which strongly differs from the host rock where olivine is highly deformed with evidence of high dislocation densities and a strong LPO. Altogether, these features shed light on the origin of mantle ultramylonites that I attribute to a migrating grain boundary, the sliding of which continuously produces new grains by phase nucleation, probably at the favor of transient four-grain junctions. Nucleated grains then grow and progressively detach from the precursor as it keeps on migrating depending on the dislocation densities in the host rock. Although such an unusual grain boundary remains to be understood in terms of source mechanism, these findings provide new constraints on the appearing and development of ultramylonites.&lt;/span&gt;&lt;/p&gt;&lt;p&gt;&amp;#160;&lt;/p&gt;&lt;p&gt;[1] Fusseis, F., Regenauer-Lieb, K., Liu, J., Hough, R. M. &amp; De Carlo, F. Creep cavitation can establish a dynamic granular fluid pump in ductile shear zones. Nature &lt;strong&gt;459&lt;/strong&gt;: 974&amp;#8211;977 (2009)&lt;/p&gt;&lt;p&gt;[2] Pr&amp;#233;cigout, J., Prigent, C., Palasse, L. &amp; Pochon, A. Water pumping in mantle shear zones. Nat. commun. &lt;strong&gt;8&lt;/strong&gt;: 15736, https://doi.org/10.1038/ncomms15736 (2017)&lt;/p&gt;&lt;p&gt;[3] White, J. C. Paradoxical pseudotachylyte &amp;#8211; Fault melt outside the seismogenic zone. J. Struct. Geol. &lt;strong&gt;38&lt;/strong&gt;: 11-20 (2012)&lt;/p&gt;

scholarly journals Extraction and parametrization of grain boundary networks in glacier ice, using a dedicated method of automatic image analysis

2013 ◽  
Vol 250 (2) ◽  
pp. 130-141 ◽  
Author(s):  
T. BINDER ◽  
C.S. GARBE ◽  
D. WAGENBACH ◽  
J. FREITAG ◽  
S. KIPFSTUHL
Keyword(s):  
Image Analysis ◽  
Grain Boundary ◽  
Automatic Image Analysis ◽  
Glacier Ice

Simulation of the Kinetics of Grain-Boundary Nucleated Phase Transformations

2011 ◽  
Vol 172-174 ◽  
pp. 1128-1133 ◽  
Author(s):  
Eric A. Jägle ◽  
Eric J. Mittemeijer
Keyword(s):  
Grain Size ◽  
Grain Boundary ◽  
Phase Transformations ◽  
Size Distribution ◽  
Grain Size Distribution ◽  
Kinetic Models ◽  
Micro Structure ◽  
Boundary Area ◽  
Random Nucleation ◽  
Kinetics Of

The kinetics of phase transformations for which nucleation occurs on parent-micro-structure grain boundaries, and the resulting microstructures, were investigated by means ofgeometric simulations. The influences of parent microstructure grain-boundary area density,parent grain-size distribution and parent→product kinetics were analysed. Additionally, thesimulated kinetics were compared with predictions from two kinetic models, namely a modelproposed for spatially random nucleation and a model proposed for grain-boundary nucleation.It was found that the simulated transformed fraction as function of time lies in between the twomodel predictions for all investigated parent microstructures and parent→product kinetics.

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