scholarly journals MIGRATION OF LONGSHORE BARS

1980 ◽  
Vol 1 (17) ◽  
pp. 88
Author(s):  
Hans H. Dette
Keyword(s):  
Breaking Waves ◽  
Bottom Deposit ◽  
Size Distributions ◽  
Variable Intensity ◽  
Grain Sizes ◽  
Grain Size Distributions ◽  
Induced Currents ◽  
And Migration ◽  
The Stability ◽  
Wave Induced

It is known that nearshore areas occupied by longshore bars constitute a zone of active migration of bottom deposit due to agitation by breaking waves and wave-induced on-/offshore currents and longshore currents. So far there is still a lack Of actual data from the field itself concerning the magnitude and variability of single parameters involved in the stability and migration of longshore bar features. This paper summarizes data collected from a comprehensive field study in the years from 1976 to 1979 when grain size distributions were obtained from a narrow grid of core samples and repeated soundings and continuous measurements of waves and wave-induced currents were carried out. With regard to the characteristics of different longshore bar feature relationships e. g. in between bottom gradients and mean grain sizes are analyzed. Furthermore distinct types of topographic response within the submarine belt occupied by longshore bars depending upon the variable intensity and position of breaking waves and the resulting magnitude and variability of wave-induced currents are pointed out and presented for discussion as a contribution towards a general understanding of longshore bar characteristics and changes.

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 Subglacial comminution in till — evidence from microfabric studies and grain-size distributions

1997 ◽  
Vol 43 (145) ◽  
pp. 473-479 ◽  
Author(s):  
Yi Chaolu
Keyword(s):  
Size Range ◽  
Coarse Fraction ◽  
The Other ◽  
Size Distributions ◽  
Thin Sections ◽  
Grain Sizes ◽  
Altay Mountains ◽  
Large Particles ◽  
Grain Size Distributions ◽  
Basal Till

AbstractQuartz, feldspar and chlorite, the principal minerals in a basal till from the Halasi River catchment in the Altay Mountains, northwestern China, are present in approximately equal concentrations in the coarse fraction of the till, 1.0-0.125 mm. Quartz concentrations are significantly higher than those of the other two minerals in the 0.125-0.016 mm size range. Feldspar and chlorite concentrations are higher than those of quartz in the finest fraction. Quartz has a strong preferred mode at 0.063-0.032 mm. Feldspar and chlorite have two weak modes in the silt-size range, one between 0.063 and 0.032 mm and the other between 0.016 and 0.004 mm.Thin sections of oriented impregnated samples were used to study crushing and abrasion. Over 2700 daughter particles were identified as products of comminution of 925 parent grains. Quartz and feldspar are most likely to be broken into two particles of roughly equal size, as are fine chlorite grains. However, owing to their weakness and cleavage, larger grains of chlorite tend to he split into more than two daughter particles.Sizes of the daughter grains were measured and sizes of the original parent grains were estimated. Mean parent grain-sizes for quartz, feldspar and chlorite are 0.129, 0.078 and 0.059 mm, respectively, whereas mean daughter grain-sizes are 0.068,0.041 and 0.024 mm, respectively. The greater percentage reduction in the size of chlorite reflects its tendency to break into more than two daughter particles.Most grains tend to be crushed. Only a few large particles seem to have suffered from abrasion.

Feeding and Migration Patterns of the Pink Shrimp, Pandalus montagui, in the Estuary of the River Crouch, Essex, England

1967 ◽  
Vol 24 (3) ◽  
pp. 569-580 ◽  
Author(s):  
P. J. Warren ◽  
R. W. Sheldon
Keyword(s):  
Grain Size ◽  
Small Area ◽  
Tidal Flow ◽  
Size Distributions ◽  
Pink Shrimp ◽  
Migration Patterns ◽  
Bottom Deposits ◽  
Slack Water ◽  
Grain Size Distributions ◽  
And Migration

Feeding of the pink shrimp, Pandalus montagui, took place mainly in daylight at low slack water. There was relatively little feeding at low slack water at night, and almost no feeding at other times. Sand grains were ingested with the food and it was possible to identify areas where feeding could have occurred by comparing grain-size distributions of material from the stomachs with those of the bottom deposits. It was possible to show, by fishing in selected areas and by considering patterns of tidal flow, that feeding was restricted to a small area near the mouth of the River Crouch, and that P. montagui migrated from this area with the flood tide and returned to it on the ebb.

Statistical Analysis of Grain Structures Formed by Solid-State Diffusion at Annealing

2020 ◽  
Vol 989 ◽  
pp. 301-305
Author(s):  
Alexey V. Stolbovsky
Keyword(s):  
Grain Size ◽  
Solid State ◽  
Grain Structure ◽  
Structure Evolution ◽  
Solid State Diffusion ◽  
Size Distributions ◽  
Grain Sizes ◽  
Grain Structures ◽  
State Diffusion ◽  
Grain Size Distributions

Grain structures of Nb3Sn layers, formed by solid-state diffusion, have been analyzed using statistical methods. To determine parameters of grain structure from grain size distributions, a statistical model with combination of lognormal and standard distributions was used. Histograms of grain size distributions in Nb3Sn layers, formed by solid-state diffusion in different composites, appeared to have only one group of crystallites after various regimes of heat treatment. It has been established that there is strong correlation between average grain sizes and the standard deviations, and this statement is also fulfilled at the grain structure evolution under additional annealing.

Grain Size and Burnup Dependence of Spent Fuel Oxidation: Geological Repository Impact

1999 ◽  
Vol 556 ◽  
Author(s):  
E. J. Kansa ◽  
B. D. Hanson ◽  
R. B. Stout
Keyword(s):  
Grain Size ◽  
Present Model ◽  
Size Distributions ◽  
Spent Fuel ◽  
Grain Sizes ◽  
Geological Repository ◽  
Grain Size Distributions ◽  
Effective Grain Size ◽  
Oxidation Model ◽  
High Burnup

AbstractFurther refinements to the oxidation model of Stout et al. have been made. The present model incorporates the burnup dependence of the oxidation rate and an allowance for a distribution of grain sizes. The model was tested by comparing the model results with the oxidation histories of spent-fuel samples oxidized in thermogravimetric analysis (TGA) or oven dry-bath (ODB) experiments. The experimental and model results are remarkably close and confirm the assumption that grain-size distributions and activation energies are the important parameters to predicting oxidation behavior. The burnup dependence of the activation energy was shown to have a greater effect than decreasing the effective grain size in suppressing the rate of the reaction U4O9→U3O8. Model results predict that U3O8 formation of spent fuels exposed to oxygen will be suppressed even for high burnup fuels that have undergone restructuring in the rim region, provided the repository temperature is kept sufficiently low.

scholarly journals Subglacial comminution in till — evidence from microfabric studies and grain-size distributions

1997 ◽  
Vol 43 (145) ◽  
pp. 473-479 ◽  
Author(s):  
Yi Chaolu
Keyword(s):  
Size Range ◽  
Coarse Fraction ◽  
The Other ◽  
Size Distributions ◽  
Thin Sections ◽  
Grain Sizes ◽  
Altay Mountains ◽  
Large Particles ◽  
Grain Size Distributions ◽  
Basal Till

Abstract Quartz, feldspar and chlorite, the principal minerals in a basal till from the Halasi River catchment in the Altay Mountains, northwestern China, are present in approximately equal concentrations in the coarse fraction of the till, 1.0-0.125 mm. Quartz concentrations are significantly higher than those of the other two minerals in the 0.125-0.016 mm size range. Feldspar and chlorite concentrations are higher than those of quartz in the finest fraction. Quartz has a strong preferred mode at 0.063-0.032 mm. Feldspar and chlorite have two weak modes in the silt-size range, one between 0.063 and 0.032 mm and the other between 0.016 and 0.004 mm. Thin sections of oriented impregnated samples were used to study crushing and abrasion. Over 2700 daughter particles were identified as products of comminution of 925 parent grains. Quartz and feldspar are most likely to be broken into two particles of roughly equal size, as are fine chlorite grains. However, owing to their weakness and cleavage, larger grains of chlorite tend to he split into more than two daughter particles. Sizes of the daughter grains were measured and sizes of the original parent grains were estimated. Mean parent grain-sizes for quartz, feldspar and chlorite are 0.129, 0.078 and 0.059 mm, respectively, whereas mean daughter grain-sizes are 0.068,0.041 and 0.024 mm, respectively. The greater percentage reduction in the size of chlorite reflects its tendency to break into more than two daughter particles. Most grains tend to be crushed. Only a few large particles seem to have suffered from abrasion.

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.

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