scholarly journals Subglacial sediment textures: character and evolution at Haut Glacier d’Arolla, Switzerland

1999 ◽  
Vol 28 ◽  
pp. 241-246 ◽  
Author(s):  
Urs H. Fischer ◽  
Bryn Hubbard
Keyword(s):  
Grain Size ◽  
Fractal Dimension ◽  
Fine Fraction ◽  
Particle Diameter ◽  
Fractal Dimensions ◽  
Textural Evolution ◽  
Grain Size Distributions ◽  
Percentage Weight ◽  
Sediment Deformation

AbstractFourteen subglacial debris samples have been recovered from the margins of, or beneath, Haut Glacier d’Arolla, Switzerland. The grain-size distributions of these sediments are presented and compared with each other as bivariate plots of percentage weight against (sieve-defined) particle size and log number of particles against log particle diameter. All of the samples recovered are composed of a broad range of clast sizes and approach self-similarity over the four orders of magnitude of grain-sizes analysed. Fractal dimensions range from 2.47 to 2.77. Sample intercomparison reveals the operation of at least two processes of textural evolution: the production of fines by in-situ weathering, interpreted in terms of abrasion associated with subglacial sediment deformation, and the loss of fines, interpreted in terms of eluviation by percolating subglacial meltwaters. These interpretations are supported and refined through comparison of the grain-size fractions gained (in the case of deformation) and lost (in the case of eluviation) with those fractions respectively generated in a laboratory-based simulation of sediment deformation and exiting the glacier suspended in the proglacial meltwater stream. While sediment deformation has the effect of increasing the fine fraction between 0 and 10ϕ and of raising the fractal dimension of undeformed sediments from 2.47 to 2.77, eluviation removes particles between 2 and 100, driving the fractal dimension of deformed sediments down from 2.77 to 2.54. These fractal dimensions are generally lower than those recorded at other comparable glaciers, consistent with the relatively low rates of sediment deformation inferred from other studies at Haut Glacier d’Arolla.

scholarly journals Three-Dimensional in situ Reconstructions of Microstructures with Bimodal Grain Size Distributions

2019 ◽  
Vol 25 (S2) ◽  
pp. 370-371
Author(s):  
Ashley Bucsek ◽  
Lee Casalena ◽  
Darren C. Pagan ◽  
Partha P. Paul ◽  
Yuriy Chumlyakov ◽  
...  
Keyword(s):  
Grain Size ◽  
Three Dimensional ◽  
Size Distributions ◽  
Grain Size Distributions ◽  
Bimodal Grain Size

Geochemical characterization of discrete grain size fractions within contemporary alpine dust, Uinta Mountains, Utah, USA

2020 ◽  
Author(s):  
Pratt Olson ◽  
Jeffrey Munroe
Keyword(s):  
Grain Size ◽  
Clay Minerals ◽  
Mineral Dust ◽  
Fine Fraction ◽  
Particle Diameter ◽  
Source Analysis ◽  
Dust Collector ◽  
Mountain Range ◽  
Uinta Mountains ◽  
Source Regions

<p>The contemporary aeolian system is poorly understood due in part to a scarcity of direct measurements of modern dust deposition. The Uinta Mountains of Northeastern Utah, USA are well-suited to the study of contemporary dust owing to their gently sloping, soil-mantled alpine zones and relatively inert, quartzite-dominated bedrock. Capitalizing on this unique setting, eight marble dust traps, as well as one active dust collector, have been installed throughout the mountain range. Previous study of samples from these collectors has supported the quantification of mineral dust inputs to alpine pedogenesis and identified isotopic fingerprints that link dust to potential source regions. This project focuses on dust emptied from these samplers in Fall 2019, representing two years of continuous dust accumulation. The mean dust flux for these years is 4.1 g/m<sup>2</sup>/y, which corresponds to historic flux measurements ranging from 2.7 g/m<sup>2</sup>/y to 4.4 g/m<sup>2</sup>/y. The relatively large dust mass of these multi-year samples allows for samples from each collector to be split into a coarse and fine fraction prior to further analysis. Before separation, the median grain size of 2019 dust samples is approximately 10 µm. After sample separation, carried out through timed settling following Stoke’s Law, the approximate median particle diameter is 6 µm for the fine fraction, and 20 µm for the coarse fraction. Coarse Uinta dust is more enriched in quartz and feldspar relative to fine dust, which is dominated by clay minerals. The coarse material is therefore more mineralogically similar to local bedrock, supporting the theory that larger particles are endogenous in origin. Clay minerals are less abundant in local bedrock, suggesting that fine mineral dust may have an exogenous source. Analysis of trace and major elemental abundances, as well as Sr and Nd isotopic fingerprinting will support additional interpretations about the nature and origin of modern dust in the Uintas. These results will contribute to ongoing efforts to better understand how specific dust source regions influence the properties of mineral aerosols arriving in remote alpine environments.</p>

scholarly journals In Situ Sampling of Relative Dust Devil Particle Loads and Their Vertical Grain Size Distributions

Astrobiology ◽  
2018 ◽  
Vol 18 (10) ◽  
pp. 1305-1317 ◽  
Author(s):  
Jan Raack ◽  
Dennis Reiss ◽  
Matthew R. Balme ◽  
Kamal Taj-Eddine ◽  
Gian Gabriele Ori
Keyword(s):  
Grain Size ◽  
Size Distributions ◽  
Dust Devil ◽  
Grain Size Distributions

scholarly journals Some Notes on Granular Mixtures with Finite, Discrete Fractal Distribution

2021 ◽  
Author(s):  
Emoke Imre ◽  
István Talata ◽  
Daniel Barreto ◽  
Maria Datcheva ◽  
Wiebke Baille ◽  
...  
Keyword(s):  
Fractal Dimension ◽  
Distinct Element ◽  
Fractal Dimensions ◽  
Internal Stability ◽  
Size Distributions ◽  
Entropy Theory ◽  
Micro Computed Tomography ◽  
Fractal Distribution ◽  
Granular Mixtures ◽  
Grain Size Distributions

Why fractal distribution is so frequent? It is true that fractal dimension is always less than 3? Why fractal dimension of 2.5 to 2.9 seems to be steady-state or stable? Why the fractal distributions are the limit distributions of the degradation path? Is there an ultimate distribution? It is shown that the finite fractal grain size distributions occurring in the nature are identical to the optimal grading curves of the grading entropy theory and, the fractal dimension n varies between –¥ and ¥. It is shown that the fractal dimensions 2.2–2.9 may be situated in the transitional stability zone, verifying the internal stability criterion of the grading entropy theory. Micro computed tomography (μCT) images and DEM (distinct element method) studies are presented to show the link between stable microstructure and internal stability. On the other hand, it is shown that the optimal grading curves are mean position grading curves that can be used to represent all possible grading curves.

scholarly journals On the sedimentological character of Alpine basal ice facies

1996 ◽  
Vol 22 ◽  
pp. 187-193 ◽  
Author(s):  
Bryn Hubbard ◽  
Martin Sharp ◽  
Wendy J. Lawson
Keyword(s):  
Grain Size ◽  
Fractal Dimension ◽  
Size Fraction ◽  
Fractal Dimensions ◽  
Western Alps ◽  
Similar Distribution ◽  
Self Similarity ◽  
Apparent Contradiction ◽  
Basal Ice ◽  
Self Similar

Seven basal ice facies have been defined on the basis of research at eleven glaciers in the western Alps. The concentration and texture of the debris incorporated in these facies are described. Grain-size distributions are characterised in terms of their: (i) mean size and dispersion, (ii) component Gaussian modes, and (iii) self-similarity.Firnified glacier ice contains low concentrations (≈0.2 g 1−1) of well-sorted and predominantly fine-grained debris that is not self-similar over the range of particle diameters assessed. In contrast, basal ice contains relatively high concentrations (≈4–4000 g 1−1 by facies) of polymodal (by size fraction against weight) debris, the texture of which is consistent with incorporation at the glacier bed. Analysis by grain-size against number of particles suggests that these basal facies debris textures are also self-similar. This apparent contradiction may be explained by the insensitivity of the assessment of self-similarity to variations in mass distribution. Comparison of typical size–weight with size–number distributions indicates that neither visual nor statistical assessment of the latter may be sufficiently rigorous to identify self-similarity.Apparent fractal dimensions may indicate the relative importance of fines in a debris distribution. Subglacially derived basal facies debris has a mean fractal dimension of 2.74. This value suggests an excess of fines relative to a self-similar distribution of cubes, which has a fractal dimension of 2.58. Subglacial sediments sampled from the forefield of Skalafellsjökull, Iceland, have fractal dimensions of 2.91 (A-horizon) and 2.81 (B-horizon). Debris from the A-horizon, which is interpreted as having been pervasively deformed, both most closely approaches self-similarity and has the highest fractal dimension of any of the sample groups analyzed.

Perimeter fractal dimension analysis of corrole islands on Au(111) at the solid-water interface

2020 ◽  
Vol 24 (05n07) ◽  
pp. 959-963
Author(s):  
Beatrice Bonanni ◽  
Massimo Fanfoni ◽  
Anna Sgarlata ◽  
Fabrizio Caroleo ◽  
Roberto Paolesse ◽  
...  
Keyword(s):  
Fractal Dimension ◽  
Quantitative Assessment ◽  
Fractal Dimensions ◽  
Scanning Tunneling ◽  
Water Interface ◽  
Tunneling Microscopy ◽  
A Value ◽  
Dimension Analysis ◽  
Fractal Dimension Analysis

Corrole molecules deposited from aqueous solution on Au(111) arrange flat forming mesa-like clusters (islands), as evidenced by in situ scanning tunneling microscopy (STM). A morphology quantitative assessment of the entire image is given by STM data analysis, evaluating the islands’ fractal dimension as a whole. To this end, two methods are employed: the first exploits the power law that binds the perimeter and the area of all the islands; the second is simply a value of an appropriate average of the fractal dimensions of the islands. In fact the two methods return very close results.

scholarly journals FRACTAL MODEL OF ESTIMATING QUALITY OF COLD WORKED FUEL CLADDING TUBES

2021 ◽  
pp. 57-63
Author(s):  
V.S. Vakhrusheva ◽  
V.M. Volchuk ◽  
N.V. Hruzin ◽  
I.A. Tiutieriev
Keyword(s):  
Grain Size ◽  
Fractal Dimension ◽  
Grain Boundary ◽  
Cold Deformation ◽  
Fractal Dimensions ◽  
Grain Structure ◽  
Iteration Step ◽  
Cold Plastic Deformation ◽  
Fuel Cladding ◽  
Average Grain Size

A possibility was considered concerning estimation of grain anisomery in the structure of fuel cladding tubes of corrosion-resistant 026Cr16Ni15Mo3Nb steel of austenitic class rolled according to two flow charts: regular and intensive technologies using fractal formalism. Role of grain boundary hardening during cold plastic deformation was analyzed by studying the effect of the fractal dimension of grains D and their boundaries Dg on 0.2, w, and 5. The best correlation among those that were considered was observed between relative elongation and fractal dimensions of the grain structure (R2 = 0.90). The smallest correlation was observed with the yield stress (R2 = 0.64). It is because of variation of plastic flow processes towards a decrease in the degree of hardening in the material rolled according to the intensive technology. Cold deformation results in refining of the average grain size from 15.50 to 15.42 µm. In this case, extent of the grain boundary length L increased by 17.62% at an iteration step  commensurate with the average grain size which is indicated by a change in the fractal dimension according to L ~ δ1-D. Degree of the grain structure inhomogeneity was estimated using ratios of self-similarity of regions of fractal dimensions of the structure. The obtained results on the level of mechanical properties of fuel cladding tubes made of austenitic steel indicate advantage of the intensive technology over regular one that was confirmed by results of fractal modeling.

scholarly journals On the sedimentological character of Alpine basal ice facies

1996 ◽  
Vol 22 ◽  
pp. 187-193 ◽  
Author(s):  
Bryn Hubbard ◽  
Martin Sharp ◽  
Wendy J. Lawson
Keyword(s):  
Grain Size ◽  
Fractal Dimension ◽  
Size Fraction ◽  
Fractal Dimensions ◽  
Western Alps ◽  
Similar Distribution ◽  
Self Similarity ◽  
Apparent Contradiction ◽  
Basal Ice ◽  
Self Similar

Seven basal ice facies have been defined on the basis of research at eleven glaciers in the western Alps. The concentration and texture of the debris incorporated in these facies are described. Grain-size distributions are characterised in terms of their: (i) mean size and dispersion, (ii) component Gaussian modes, and (iii) self-similarity.Firnified glacier ice contains low concentrations (≈0.2 g 1−1) of well-sorted and predominantly fine-grained debris that is not self-similar over the range of particle diameters assessed. In contrast, basal ice contains relatively high concentrations (≈4–4000 g 1−1by facies) of polymodal (by size fraction against weight) debris, the texture of which is consistent with incorporation at the glacier bed. Analysis by grain-size against number of particles suggests that these basal facies debris textures are also self-similar. This apparent contradiction may be explained by the insensitivity of the assessment of self-similarity to variations in mass distribution. Comparison of typical size–weight with size–number distributions indicates that neither visual nor statistical assessment of the latter may be sufficiently rigorous to identify self-similarity.Apparent fractal dimensions may indicate the relative importance of fines in a debris distribution. Subglacially derived basal facies debris has a mean fractal dimension of 2.74. This value suggests an excess of fines relative to a self-similar distribution of cubes, which has a fractal dimension of 2.58. Subglacial sediments sampled from the forefield of Skalafellsjökull, Iceland, have fractal dimensions of 2.91 (A-horizon) and 2.81 (B-horizon). Debris from the A-horizon, which is interpreted as having been pervasively deformed, both most closely approaches self-similarity and has the highest fractal dimension of any of the sample groups analyzed.

The Fractal Research of 16MnR Steel Fatigue Fracture after High Temperature

2012 ◽  
Vol 568 ◽  
pp. 191-195
Author(s):  
Su Zhang ◽  
An Zhong Liu
Keyword(s):  
Mechanical Properties ◽  
Grain Size ◽  
Fractal Dimension ◽  
High Temperature ◽  
Fatigue Fracture ◽  
High Temperatures ◽  
Fractal Dimensions ◽  
Three Dimensions ◽  
Fracture Surfaces ◽  
Computer Picture

In this paper, the computer picture technology was used for recovering three dimensions shape of 16MnR steel fatigue fracture. The fractal dimensions of the 16MnR fatigue fracture surfaces were calculated after high temperatures. The relation between the fractal dimension of fatigue fracture and heating temperatures, the relation between the fatigue mechanical properties and heating temperatures were researched. The relation between the grain size of 16MnR steel and the fractal dimension of fatigue fracture, and the relation between the grain size of 16MnR steel and the fatigue mechanical properties were discussed.

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