Statistical Characterisation of Grain-Size Distribution in Fluvial Sediment of Kelantan Rivers

2015 ◽  
Vol 74 (3) ◽  
Author(s):  
Wan Hanna Melini Wan Mohtar ◽  
Siti Aminah Bassa Nawang ◽  
Mojtaba Porhemmat
Keyword(s):  
Grain Size ◽  
Size Distribution ◽  
Coarse Sand ◽  
Soil Samples ◽  
Size Distributions ◽  
Mean Grain Size ◽  
Grain Size Distributions ◽  
Size Standard ◽  
Sand And Gravel ◽  
Skewness And Kurtosis

The characteristic of sediment, in particular the particle size distribution is important to be correctly determined for an accurate representation in sediment transport. This article reports the grain size distributions of soil samples taken from seven tropical rivers i.e. the Sungai (Rivers) of Sam, Galas, Lata Tunggil, Mei, Rek, Peng Datu and the major Sungai Kelantan catchment area which spanned about 11, 900 km2. The Sungai Galas is a direct tributary, whilst the Sungai Sam, Sungai Rek, Sungai Mei and Sungai Lata Tunggil are the tributaries into Sungai Lebir which subsequently feeds the Sungai Kelantan. Each obtained sample was sieved and the soil type distribution was determined. Statistical analysis of the samples was conducted; including the median grain size , mean grain size, standard deviation (sorting), skewness and kurtosis. Most of the samples have insignificant fractions of finer grains, where coarse sand and gravel were the dominant. All sediment samples are negatively skewed towards coarse sand, have very platykurtic kurtosis suggesting that the sediment has single provenance.

scholarly journals Effect of Strain-Induced Precipitation on the Recrystallization Kinetics in a Model Alloy

2021 ◽  
Author(s):  
Mo Ji ◽  
Martin Strangwood ◽  
Claire Davis
Keyword(s):  
Grain Size ◽  
Size Distribution ◽  
Grain Size Distribution ◽  
Avrami Exponent ◽  
Model Alloy ◽  
Size Distributions ◽  
Recrystallization Kinetics ◽  
Grain Size Distributions ◽  
Recrystallized Grain Size ◽  
Nb Addition

AbstractThe effects of Nb addition on the recrystallization kinetics and the recrystallized grain size distribution after cold deformation were investigated by using Fe-30Ni and Fe-30Ni-0.044 wt pct Nb steel with comparable starting grain size distributions. The samples were deformed to 0.3 strain at room temperature followed by annealing at 950 °C to 850 °C for various times; the microstructural evolution and the grain size distribution of non- and fully recrystallized samples were characterized, along with the strain-induced precipitates (SIPs) and their size and volume fraction evolution. It was found that Nb addition has little effect on recrystallized grain size distribution, whereas Nb precipitation kinetics (SIP size and number density) affects the recrystallization Avrami exponent depending on the annealing temperature. Faster precipitation coarsening rates at high temperature (950 °C to 900 °C) led to slower recrystallization kinetics but no change on Avrami exponent, despite precipitation occurring before recrystallization. Whereas a slower precipitation coarsening rate at 850 °C gave fine-sized strain-induced precipitates that were effective in reducing the recrystallization Avrami exponent after 50 pct of recrystallization. Both solute drag and precipitation pinning effects have been added onto the JMAK model to account the effect of Nb content on recrystallization Avrami exponent for samples with large grain size distributions.

scholarly journals Nonlinear Flow Behavior in Packed Beds of Natural and Variably Graded Granular Materials

2019 ◽  
Vol 131 (3) ◽  
pp. 957-983 ◽  
Author(s):  
J. H. van Lopik ◽  
L. Zazai ◽  
N. Hartog ◽  
R. J. Schotting
Keyword(s):  
Grain Size ◽  
Granular Materials ◽  
Flow Behavior ◽  
Nonlinear Flow ◽  
Packed Beds ◽  
Size Distributions ◽  
Flow Conditions ◽  
Grain Size Distributions ◽  
Sand And Gravel ◽  
Nonlinear Flow Behavior

AbstractUnder certain flow conditions, fluid flow through porous media starts to deviate from the linear relationship between flow rate and hydraulic gradient. At such flow conditions, Darcy’s law for laminar flow can no longer be assumed and nonlinear relationships are required to predict flow in the Forchheimer regime. To date, most of the nonlinear flow behavior data is obtained from flow experiments on packed beds of uniformly graded granular materials (Cu = d60/d10 < 2) with various average grain sizes, ranging from sands to cobbles. However, natural deposits of sand and gravel in the subsurface could have a wide variety of grain size distributions. Therefore, in the present study we investigated the impact of variable grain size distributions on the extent of nonlinear flow behavior through 18 different packed beds of natural sand and gravel deposits, as well as composite filter sand and gravel mixtures within the investigated range of uniformity (2.0 < Cu < 17.35) and porosity values (0.23 < n < 0.36). Increased flow resistance is observed for the sand and gravel with high Cu values and low porosity values. The present study shows that for granular material with wider grain size distributions (Cu > 2), the d10 instead of the average grain size (d50) as characteristic pore length should be used. Ergun constants A and B with values of 63.1 and 1.72, respectively, resulted in a reasonable prediction of the Forchheimer coefficients for the investigated granular materials.

Statistical Analysis of Grain Size Distribution in Pleistocene Sediments from Lake Biwa, Japan

1988 ◽  
Vol 30 (1) ◽  
pp. 12-18 ◽  
Author(s):  
Kenji Kashiwaya ◽  
Atsuyuki Yamamoto ◽  
Kaoru Fukuyama
Keyword(s):  
Time Series ◽  
Grain Size ◽  
Statistical Analysis ◽  
Size Distribution ◽  
Lake Biwa ◽  
Size Distributions ◽  
Solar Insolation ◽  
The Past ◽  
Grain Size Distributions ◽  
Milankovitch Theory

Time series of grain-size distributions from Pleistocene sediments deposited in Lake Biwa during the past 550 millennia show dominant periods of 40,000 and 20,000 yr that are very close to those predicted by the Milankovitch theory, as well as a period of about 70,000 yr not directly predicted by this theory. The 70,000-yr period is strongest, followed by the 20,000-yr period. The sequences also show that coarser particles were deposited, in general, during strong solar insolation, whereas finer particles were deposited during weak insolation.

scholarly journals Controls on the grain size distribution of landslides in Taiwan: the influence of drop height, scar depth and bedrock strength

2021 ◽  
Vol 9 (4) ◽  
pp. 995-1011
Author(s):  
Odin Marc ◽  
Jens M. Turowski ◽  
Patrick Meunier
Keyword(s):  
Grain Size ◽  
Size Distribution ◽  
Grain Size Distribution ◽  
Block Size ◽  
Fragmentation Model ◽  
Size Distributions ◽  
Drop Height ◽  
Size Segregation ◽  
Grain Size Distributions ◽  
Strong Segregation

Abstract. The size of grains delivered to rivers by hillslope processes is thought to be a key factor controlling sediment transport, long-term erosion and the information recorded in sedimentary archives. Recently, models have been developed to estimate the grain size distribution produced in soil, but these models may not apply to active orogens where high erosion rates on hillslopes are driven by landsliding. To date, relatively few studies have focused on landslide grain size distributions. Here, we present grain size distributions (GSDs) obtained by grid-by-number sampling on 17 recent landslide deposits in Taiwan, and we compare these GSDs to the geometrical and physical properties of the landslides, such as their width, area, rock type, drop height and estimated scar depth. All slides occurred in slightly metamorphosed sedimentary units, except two, which occurred in younger unmetamorphosed shales, with a rock strength that is expected to be 3–10 times weaker than their metamorphosed counterparts. For 11 landslides, we did not observe substantial spatial variations in the GSD over the deposit. However, four landslides displayed a strong grain size segregation on their deposit, with the overall GSD of the downslope toe sectors being 3–10 times coarser than apex sectors. In three cases, we could also measure the GSD inside incised sectors of the landslides deposits, which presented percentiles that were 3–10 times finer than the surface of the deposit. Both observations could be due to either kinetic sieving or deposit reworking after the landslide failure, but we cannot explain why only some deposits had strong segregation. Averaging this spatial variability, we found the median grain size of the deposits to be strongly negatively correlated with drop height, scar width and depth. However, previous work suggests that regolith particles and bedrock blocks should coarsen with increasing depth, which is the inverse of our observations. Accounting for a model of regolith coarsening with depth, we found that the ratio of the estimated original bedrock block size to the deposit median grain size (D50) of the deposit was proportional to the potential energy of the landslide normalized to its bedrock strength. Thus, the studied landslides agree well with a published, simple fragmentation model, even if that model was calibrated on rock avalanches with larger volume and stronger bedrock than those featured in our dataset. Therefore, this scaling may serve for future modeling of grain size transfer from hillslopes to rivers, with the aim to better understanding landslide sediment evacuation and coupling to river erosional dynamics.

scholarly journals Grain-size distribution unmixing using the R package EMMAgeo

2019 ◽  
Vol 68 (1) ◽  
pp. 29-46 ◽  
Author(s):  
Elisabeth Dietze ◽  
Michael Dietze
Keyword(s):  
Grain Size ◽  
Size Distribution ◽  
Grain Size Distribution ◽  
Synthetic Data ◽  
Model Parameters ◽  
Size Distributions ◽  
Sediment Sources ◽  
Data Set ◽  
Depositional Processes ◽  
Grain Size Distributions

Abstract. The analysis of grain-size distributions has a long tradition in Quaternary Science and disciplines studying Earth surface and subsurface deposits. The decomposition of multi-modal grain-size distributions into inherent subpopulations, commonly termed end-member modelling analysis (EMMA), is increasingly recognised as a tool to infer the underlying sediment sources, transport and (post-)depositional processes. Most of the existing deterministic EMMA approaches are only able to deliver one out of many possible solutions, thereby shortcutting uncertainty in model parameters. Here, we provide user-friendly computational protocols that support deterministic as well as robust (i.e. explicitly accounting for incomplete knowledge about input parameters in a probabilistic approach) EMMA, in the free and open software framework of R. In addition, and going beyond previous validation tests, we compare the performance of available grain-size EMMA algorithms using four real-world sediment types, covering a wide range of grain-size distribution shapes (alluvial fan, dune, loess and floodplain deposits). These were randomly mixed in the lab to produce a synthetic data set. Across all algorithms, the original data set was modelled with mean R2 values of 0.868 to 0.995 and mean absolute deviation (MAD) values of 0.06 % vol to 0.34 % vol. The original grain-size distribution shapes were modelled as end-member loadings with mean R2 values of 0.89 to 0.99 and MAD of 0.04 % vol to 0.17 % vol. End-member scores reproduced the original mixing ratios in the synthetic data set with mean R2 values of 0.68 to 0.93 and MAD of 0.1 % vol to 1.6 % vol. Depending on the validation criteria, all models provided reliable estimates of the input data, and each of the models exhibits individual strengths and weaknesses. Only robust EMMA allowed uncertainties of the end-members to be objectively estimated and expert knowledge to be included in the end-member definition. Yet, end-member interpretation should carefully consider the geological and sedimentological meaningfulness in terms of sediment sources, transport and deposition as well as post-depositional alteration of grain sizes. EMMA might also be powerful in other geoscientific contexts where the goal is to unmix sources and processes from compositional data sets.

Effect of grain size distribution on the maximum and minimum void ratios of granular soils

2020 ◽  
Vol 17 (2) ◽  
pp. 26-33
Author(s):  
Jose Duque ◽  
William Mario Fuentes Lacouture ◽  
Jorge Andres Barros Ayala
Keyword(s):  
Grain Size ◽  
Size Distribution ◽  
Grain Size Distribution ◽  
Granular Soil ◽  
Granular Soils ◽  
Size Distributions ◽  
Experimental Procedure ◽  
Practical Applications ◽  
Grain Size Distributions ◽  
Properties Of Soil

The maximum and minimum void ratios define the loosest and densest conditions of a granular soil. Correlations with some granulometric properties of soil are of interest for practical applications, but the experimental procedure to determine these variables can be time consuming. In this work the influence of the grain size distribution on the maximum and minimum void ratios is investigated. Twenty different granular soils with varying grain size distributions were prepared and tested. The experimental results, together with a compilation of 56 additional results reported in the literature, are statistically analysed. The analysis is conducted to examine the influence of some granulometric properties (D10, D30 and D60) on the maximum and minimum void ratios. As a result, some correlations considering the aforementioned variables are proposed. Subsequently, it is shown that the proposed correlations have better agreement with the experimental data than other proposals reported in the literature. The paper ends with some concluding remarks.

The Surficial Sediments of the Big Bay Section of the Bay of Quinte, Lake Ontario

1974 ◽  
Vol 11 (11) ◽  
pp. 1562-1576 ◽  
Author(s):  
V. Damiani ◽  
R. L. Thomas
Keyword(s):  
Grain Size ◽  
Energy Levels ◽  
Textural Properties ◽  
Surficial Sediments ◽  
Sediment Distribution ◽  
Organic C ◽  
Mean Grain Size ◽  
Size Standard ◽  
Northern Shore ◽  
Skewness And Kurtosis

Ninety-six samples of the uppermost 3 cm of sediment were taken from the Big Bay section of the Bay of Quinte. The samples were analyzed for grain size, Eh, pH, organic C, and inorganic C. The Big Bay section contains three depositional basins and has a mean depth of 4.7 m. The sediment distribution was mapped by conventional echosounding and showed that the coarser sediments, sands and gravels, occurred on the northern shore and in the eastern part of the study area, with clayey silts and silty clays offshore in the three depositional basins. This distribution was confirmed by the grain size analyses.The textural properties of the sediments, mean grain size, standard deviation, skewness, and kurtosis, are related to the variable mixing of three populations comprising gravel, sand, and silt/clay. Trends in the grain-size statistics related to sediment distribution suggested that the distribution observed is a result of increasing energy levels downwind under prevailing westerly and southwesterly winds.

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.

Grain Size Distribution and Degree of Texture in Films Used in Integrated Circuits

1998 ◽  
Vol 523 ◽  
Author(s):  
R. Lindsay ◽  
J. N. Chapman ◽  
A. J. Craven ◽  
D. Mcbain ◽  
I. Molchanov
Keyword(s):  
Grain Size ◽  
Electrical Properties ◽  
Integrated Circuits ◽  
Size Distribution ◽  
Size Distributions ◽  
Cross Sectional ◽  
Polysilicon Film ◽  
Conductive Films ◽  
Grain Sizes ◽  
Grain Size Distributions

AbstractAs miniaturisation proceeds, the electrical properties of conductive films used in modem IC's are increasingly influenced by the grain sizes and the texture of the films. There is a need therefore to devise techniques which can examine these properties. Described in this work are two new cross-sectional TEM techniques for use on fully-processed IC's to determine quantitatively grain size distributions and the degree of texture in a film. The technique which investigates texture is used to determine how quickly the texture develops through a polysilicon film.

scholarly journals Uniform grain-size distribution in the active layer of a shallow, gravel-bed, braided river (the Urumqi River, China) and implications for paleo-hydrology

2018 ◽  
Author(s):  
Laure Guerit ◽  
Laurie Barrier ◽  
Youcun Liu ◽  
Clément Narteau ◽  
Eric Lajeunesse ◽  
...  
Keyword(s):  
Grain Size ◽  
Size Distribution ◽  
Grain Size Distribution ◽  
Active Layer ◽  
Size Distributions ◽  
Gravel Bed ◽  
Surface Samples ◽  
River Bed ◽  
Braided Stream ◽  
Grain Size Distributions

Abstract. The grain-size distribution of ancient alluvial systems is commonly determined from surface samples of vertically exposed sections of gravel deposits. This method relies on the hypothesis that the grain-size distribution obtained from a vertical cross-section is equivalent to that of the river bed. We report a field test of this hypothesis on samples collected on an active, gravel-bed, braided stream: the Urumqi River in China. We compare data from volumetric samples of a trench excavated in an active thread and surface counts performed on the trench vertical faces. We show that the grain-size distributions obtained from all samples are similar and that the deposit is uniform at the scale of the river active layer, a layer extending from the surface to a depth of approximately ten times the size of the largest clasts.

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