scholarly journals Assessment and Analysis of Precambrian Basement Soil Deposits Using Grain Size Distribution

2020 ◽  
Vol 66 (4) ◽  
pp. 235-243
Author(s):  
Gideon Layade ◽  
Charles Ogunkoya ◽  
Victor Makinde ◽  
Kehinde Ajayi
Keyword(s):  
Grain Size ◽  
Size Distribution ◽  
Grain Size Distribution ◽  
Textural Properties ◽  
Soil Samples ◽  
Sieve Analysis ◽  
Precambrian Basement ◽  
Statistical Parameters ◽  
Fine Grained ◽  
Transportation History

AbstractThe article presents the grain size distribution of soil samples from the Precambrian basement within the purview of the textural properties, deduced transportation history and the numerical assessments using statistical parameters. The fourteen soil samples collected from the study area were subjected to sieve analysis in the laboratory for the determination of their grain size distribution. The statistical parameters’ study includes the graphic mean, skewness, sorting and kurtosis. The result of the analysis of the soil samples ranged from coarse to fine-grained samples, moderately and poorly sorted, positively and negatively skewed and the kurtosis also shows leptokurtic as the most dominant which suggests the samples poorly distributed and moderately sorted at the centre of the grain size distribution. These results also suggest the geological environment of the soil samples could be responsible for the poorly and moderately sorted exhibited by the samples deposited in the location.

scholarly journals Microstructural evolution in the fine-grained region of the Siple Dome (Antarctica) ice core

2011 ◽  
Vol 57 (206) ◽  
pp. 1046-1056 ◽  
Author(s):  
R.W. Obbard ◽  
K.E. Sieg ◽  
I. Baker ◽  
D. Meese ◽  
G.A. Catania
Keyword(s):  
Grain Size ◽  
Size Distribution ◽  
Grain Size Distribution ◽  
Electron Backscatter Diffraction ◽  
Ice Core ◽  
Axis Orientation ◽  
Fine Grained ◽  
Depth Analysis ◽  
Siple Dome ◽  
Mean Grain Size

AbstractAn in-depth analysis of seven samples from the Siple Dome (Antarctica) ice core, using optical microscopy and electron backscatter diffraction, illustrates rotational recrystallization or polygonization in the fine-grained region of the core between 700 and 800 m. Between 640 and 700 m, the microstructure is characterized by a bimodal grain-size distribution and a broken girdle fabric with evidence of polygonization. From 727 to 770 m, mean grain size decreases and a single-maximum fabric is found, and, by 790 m, mean grain size has again increased and a multiple-maxima fabric manifests itself. We compare grain-size distribution, c- and a-axis orientation, and misorientation between adjacent grains. We found that misorientations between adjacent grains in the 727–770 m region were predominantly low-angle and typically around a common a-axis, suggesting polygonization. This conclusion is supported by radar evidence of a physical disturbance at 757 m, which may be correlated with higher than usual strain in the 700–800 m range. Below 770 m, larger less regular misorientations and textural evidence show that migration recrystallization is the primary recrystallization mechanism.

scholarly journals MINERAL COMPOSITION OF SOME LATGALE LAKE SEDIMENTS

2019 ◽  
Vol 1 ◽  
pp. 304
Author(s):  
Rasma Tretjakova ◽  
Andris Karpovičs
Keyword(s):  
Grain Size ◽  
Lake Sediments ◽  
Size Distribution ◽  
Clay Minerals ◽  
Mineral Composition ◽  
Grain Size Distribution ◽  
Sandy Loam ◽  
Clay Fraction ◽  
Fine Grained ◽  
Two Samples

Our research is focused on sedimentological conditions and postdepositional changes of recent fine grained lake sediments. We used bulk sediment mineralogical composition and grain size distribution as indicators to identify sediment source areas and possible changes during Holocene. We analysed fine grained (clayey) sediments from three Latgale lakes - Zeili, Pauguļi and Plusons, situated in Latgale upland. Lake sediments cover Late Pleistocene glacial deposits – loam and sandy loam. Bulk mineral composition of 6 sediment samples was determined by X-ray diffraction (XRD). Sediments contained typical minerals found in surrounding glacial sediments: rock-forming minerals as quartz, plagioclase, albite, enstatite, dolomite, calcite, and clay minerals - illite, kaolinite. To identify postdepositional changes in lake sediments of Holocene age clay minerals in clay fraction (<2 mkm) should be analysed. Particularly illite, smectite mixed layered minerals - illite/smectite (I/Sm) and chlorite. Additionally, grain size distribution of studied lake sediments was analysed. Accordingly, our studied sediments are clays, silty clays and clayey silts with bimodal particle distribution, except two samples from Zeiļi and Plusons with unimodal distribution.

Variation of the Descriptive Grain Size Distribution Along Cores From the Sebkha of Sidi El Hani, Eastern Tunisia

2022 ◽  
pp. 197-214
Author(s):  
Elhoucine Essefi ◽  
Soumaya Hajji
Keyword(s):  
Grain Size ◽  
Size Distribution ◽  
Grain Size Distribution ◽  
Method Of Moments ◽  
Statistical Treatment ◽  
Special Care ◽  
Statistical Parameters ◽  
Sedimentary Dynamics

In this chapter, cores were the object of descriptive classifications of the grain size distribution, which were meant to describe the grain size continuous variability within cores and to correlate between them. The statistical treatment of the crude data was done on the basis of two different methods (the method of moments statistics and the method of inclusive graphic statistics) to compute statistical parameters of the grain size distribution such as mean and median. The correlations between cores were done on the basis of sand/silt/clay percentages. Even though it has given special care to test different methods of studying the grain size distribution, this study has not deviated from its primary purpose of investigating the filling of the playa; correlations between different cores were meant to infer their sedimentary dynamics.

Changes in Grain Size Distribution of a Submicron Grained Al-Sc Alloy during High Temperature Annealing

2006 ◽  
Vol 519-521 ◽  
pp. 1617-1622 ◽  
Author(s):  
N. Burhan ◽  
Michael Ferry
Keyword(s):  
Grain Size ◽  
Size Distribution ◽  
Grain Size Distribution ◽  
Elevated Temperatures ◽  
Large Fraction ◽  
Direct Consequence ◽  
Size Distributions ◽  
Grain Coarsening ◽  
Fine Grained ◽  
Grain Size Distributions

Severe plastic straining is an established method for producing submicron grain (SMG) structures in alloys. However, the development of such a fine grained structure in single-phase alloys is usually futile if they are to be exposed or processed at elevated temperatures. This is a direct consequence of the natural tendency for rapid and substantial grain coarsening which completely removes the benefits obtained by grain refinement. This problem may be avoided by the introduction of nanosized, highly stable particles in the metal matrix. In this work, a SMG structure was generated in an Al-0.3 wt.% Sc alloy by Equal Channel Angular Pressing (ECAP). The alloy was prepared initially to produce a fine grained microstructure exhibiting a large fraction of high angle grain boundaries and a dispersion of nanosized Al3Sc particles. The evolution of microstructure during annealing at temperatures up to 550 °C was examined in detail and grain size distributions generated from the data. It was shown that grain coarsening is rapid at temperatures above 450 °C and the initial log-normal grain size distribution exhibiting low variance and skewness was altered considerably. The statistical information generated from the grain size distributions confirms that discontinuous grain coarsening occurs in this alloy only at temperatures greater than 500 °C.

scholarly journals Failure Mechanisms of Alloys with a Bimodal Graine Size Distribution

2020 ◽  
pp. 521-534
Author(s):  
Vladimir A. Skripnyak ◽  
Evgeniya G. Skripnyak ◽  
Vladimir V. Skripnyak
Keyword(s):  
Grain Size ◽  
Titanium Alloys ◽  
Size Distribution ◽  
Dynamic Loading ◽  
Grain Size Distribution ◽  
High Strain ◽  
Fine Grained ◽  
Localization Of Plastic Deformation ◽  
Grain Size Distributions ◽  
Bimodal Grain Size

AbstractA multi-scale computational approach was used for the investigation of a high strain rate deformation and fracture of magnesium and titanium alloys with a bimodal distribution of grain sizes under dynamic loading. The processes of inelastic deformation and damage of titanium alloys were investigated at the mesoscale level by the numerical simulation method. It was shown that localization of plastic deformation under tension at high strain rates depends on grain size distribution. The critical fracture stress of alloys depends on relative volumes of coarse grains in representative volume. Microcracks nucleation at quasi-static and dynamic loading is associated with strain localization in ultra-fine grained partial volumes. Microcracks arise in the vicinity of coarse and ultrafine grains boundaries. It is revealed that the occurrence of a bimodal grain size distributions causes increased ductility, but decreased tensile strength of UFG alloys. The increase in fine precipitation concentration results not only strengthening but also an increase in ductility of UFG alloys with bimodal grain size distribution.

scholarly journals Rating of malt grist fineness with respect to the used grinding equipment

2016 ◽  
Vol 62 (No. 3) ◽  
pp. 141-146
Author(s):  
A. Smejtková ◽  
P. Vaculík ◽  
M. Přikryl ◽  
Z. Pastorek
Keyword(s):  
Grain Size ◽  
Size Distribution ◽  
Grain Size Distribution ◽  
Sieve Analysis ◽  
Barley Malt ◽  
Roller Mill ◽  
Disk Mill ◽  
Grinding Machines ◽  
Made In ◽  
Grinding Mill

Grain size distribution of grist is dependent on the type of grinding mill. The most widely used crushers used for malt grinding are roll grinding machines and dispersants are the disc mills. For rating of grist fineness grists made in the two-roller mill KVM 130/150 and dispersant the disk mill Skiold SK 2500 was used. The selected types of barley malt were processed: light malt, Munich malt, caramel malt and colouring malt. Rating of malt grist fineness was made with a help of sieve analysis using a “Pfungstadt sifter”. Conclusions from the measurements are as follows: by using the two-roller mill the coarsest grist is got from caramel malt and the finest malt from the light malt. The dispersant was processing grist at a speed of 1,500 rpm and 2,800 rpm. For each speed, the coarsest grist was obtained from caramel malt and the finest grist was obtained by crushing colouring malt.  

scholarly journals Image analysis for measuring stratigraphy in sand-gravel laboratory experiments

2013 ◽  
Vol 1 (1) ◽  
pp. 973-1018
Author(s):  
C. Orrú ◽  
V. Chavarrías ◽  
W. S. J. Uijttewaal ◽  
A. Blom
Keyword(s):  
Grain Size ◽  
Image Analysis ◽  
Size Distribution ◽  
Grain Size Distribution ◽  
Laboratory Experiments ◽  
Sieve Analysis ◽  
Sediment Layer ◽  
Conversion Model ◽  
Areal Fraction ◽  
Sediment Layers

Abstract. Measurements of spatial and temporal changes in the grain size distribution are crucial to improving the modelling of sediment transport and associated grain size-selective processes. We present three complementary techniques to determine such variations in the grain size distribution in sand-gravel laboratory experiments, as well as the resulting stratigraphy: (1) particle colouring, (2) removal of sediment layers, and (3) image analysis. The resulting stratigraphy measurement method has been evaluated in two sets of experiments. In both sets three grain size fractions within the range of coarse sand to fine gravel were painted in different colours. Sediment layers are removed using a wet vacuum cleaner. Subsequently areal images are taken of the surface of each layer. The areal fraction content, i.e. the relative presence of each size fraction over the bed surface, is determined using a colour segmentation algorithm which provides the areal fraction content of a specific colour (i.e., grain size) covering the bed surface. Particle colouring is not only beneficial to this type of image analysis but also observing and understanding grain size-selective processes. The stratigraphy based on areal fractions is measured with sufficient accuracy. Other advantages of the proposed stratigraphy measurement technique are: (a) rapid collection and processing of a large amount of data, (b) very high spatial density of information on the grain size distribution (so far unequalled in other methods), (c) the lack of disturbances to the bed surface, (d) only minor disturbances to the substrate due to the removal of sediment layers, and (e) the possibility to return a sediment layer at its original elevation and continue the flume experiment. The areal fractions can be converted into volumetric fractions using a conversion model. The proposed empirical conversion model is based on a comparison between the photogrammetry results and dry sieve analysis.

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