Size-graded, igneous layering in an Icelandic intrusion

1972 ◽  
Vol 109 (5) ◽  
pp. 393-404 ◽  
Author(s):  
M. J. Roobol
Keyword(s):  
Grain Size ◽  
Laminar Flow ◽  
Physical Properties ◽  
Size Distribution ◽  
Grain Size Distribution ◽  
Simple System ◽  
Mineral Species ◽  
Basalt Magma ◽  
Grain Sizes ◽  
Igneous Layering

SummaryThe Vesturhorn Intrusion of SE Iceland contains a tilted block consisting largely of size-graded, igneous-layered, eucritic gabbro, which is described in some detail. Size-graded, igneous layering is remarkably uncommon and at present there appear to be only two known occurrences. The physical properties of basalt magma suggest that most igneous layering is likely to form from currents moving by laminar flow. Considerations of flow in such a simple system do not satisfactorily account for the scarcity of this structure. It is suggested that size-graded, igneous layering may reflect the availability of convecting magmas containing crystals with appreciable proportions of different grain sizes of each mineral species. Such a grain size distribution, together with other features considered here, may indicate primocryst growth outside the chamber of deposition.

scholarly journals Modified Gompertz sigmoidal model removing fine-ending of grain-size distribution

2019 ◽  
Vol 11 (1) ◽  
pp. 29-36 ◽  
Author(s):  
Rui Yuan ◽  
Bo Yang ◽  
Yingfei Liu ◽  
Lingyu Huang
Keyword(s):  
Grain Size ◽  
Size Distribution ◽  
Grain Size Distribution ◽  
Cumulative Probability ◽  
Second Stage ◽  
Grain Sizes ◽  
Third Stage ◽  
Moments Method ◽  
Sigmoidal Model ◽  
Parameters Calculation

Abstract Because of the laboratory operating, the fineending of grain-size distribution (GSD) are simply combined as one point, which results in the information loss of the fine and very-fine clastic particles, and affects the geological parameters calculation of GSD. To remove the fine-endings, a modified Gompertz sigmoidal model is proposed in this paper. The first stage is establishing and solving the modified Gompertz sigmoidal model; the second stage is fitting and evaluating the cumulative probability and frequency of GSD; the third stage is calculating the geological parameters. Taking 113 samples for example, coefficients of determination (COD) between measured and fitted individual cumulative probability and frequency are bigger than 0.98980 and 0.97000 respectively, which proves the goodness of fitting results. By moments method using frequency data, the COD between fitted and measured mean is 0.97578, while CODs of sorting, skewness and kurtosis are in low values, which suggest that the fine-endings has little influence on the average grain-sizes of GSD and large influence on its geometry. Besides, modified Gompertz sigmoidal model offers another quick numerical way to calculate median, mean and sorting of GSD by graphical method using cumulative probability data. The proposed method is useful to remove the fine-endings and contribute to calculate the geological parameters of GDS.

The Inverse Hall-Petch Effect—Fact or Artifact?

2000 ◽  
Vol 634 ◽  
Author(s):  
Carl C. Koch ◽  
J. Narayan
Keyword(s):  
Grain Size ◽  
Size Distribution ◽  
Grain Size Distribution ◽  
Computer Simulations ◽  
Nanocrystalline Materials ◽  
Grain Sizes ◽  
Average Grain Size

ABSTRACTThis paper critically reviews the data in the literature which gives softening—the inverse Hall-Petch effect—at the finest nanoscale grain sizes. The difficulties with obtaining artifactfree samples of nanocrystalline materials will be discussed along with the problems of measurement of the average grain size distribution. Computer simulations which predict the inverse Hall-Petch effect are also noted as well as the models which have been proposed for the effect. It is concluded that while only a few of the experiments which have reported the inverse Hall-Petch effect are free from obvious or possible artifacts, these few along with the predictions of computer simulations suggest it is real. However, it seems that it should only be observed for grain sizes less than about 10 nm.

Topology Based Growth Law and New Analytical Grain Size Distribution Function of 3D Grain Growth

2007 ◽  
Vol 558-559 ◽  
pp. 1183-1188 ◽  
Author(s):  
Peter Streitenberger ◽  
Dana Zöllner
Keyword(s):  
Grain Size ◽  
Distribution Function ◽  
Size Distribution ◽  
Grain Growth ◽  
Grain Size Distribution ◽  
Three Dimensional ◽  
Size Distribution Function ◽  
Change Rate ◽  
Grain Sizes ◽  
Self Similar

Based on topological considerations and results of Monte Carlo Potts model simulations of three-dimensional normal grain growth it is shown that, contrary to Hillert’s assumption, the average self-similar volume change rate is a non-linear function of the relative grain size, which in the range of observed grain sizes can be approximated by a quadratic polynomial. In particular, based on an adequate modification of the effective growth law, a new analytical grain size distribution function is derived, which yields an excellent representation of the simulated grain size distribution.

Statistical analysis of the parameters and grain size distribution functions of single-phase polycrystalline materials

2020 ◽  
Vol 86 (4) ◽  
pp. 39-45
Author(s):  
S. I. Arkhangelskiy ◽  
D. M. Levin
Keyword(s):  
Grain Size ◽  
Distribution Function ◽  
Size Distribution ◽  
Grain Size Distribution ◽  
Single Phase ◽  
Distribution Functions ◽  
Grain Structure ◽  
Polycrystalline Materials ◽  
Grain Sizes ◽  
Average Grain Size

A statistical analysis of the grain size distribution is important both for developing theories of the grain growth and microstructure formation, and for describing the size dependences of various characteristics of the physical and mechanical properties of polycrystalline materials. The grain size distribution is also an important characteristic of the structure uniformity and, therefore, stability of the properties of the products during operation. Statistical Monte Carlo modeling of single-phase and equiaxed polycrystalline microstructures was carried out to determine the type of statistically valid distribution function and reliable estimates of the average grain size. Statistical parameters (mean values, variances, variation coefficient) and distribution functions of the characteristics of the grain microstructure were obtained. It is shown that the distribution function of the effective grain sizes for the studied polycrystal model is most adequately described by γ-distribution, which is recommended to be used in analysis of the experimental distribution functions of grain sizes of single-phase polycrystalline materials with equiaxed grains. The general average (mathematical expectation) of the effective grain size (projection diameter) with γ-distribution function (parameters of the distribution function are to be previously determined in analysis of the grain structure of polycrystalline materials) should be taken as a statistically valid and reliable estimate of the average grain size. The results of statistical modeling are proved by the experimental data of metallographic study of the microstructures of single-phase model and industrial materials with different degree of the grain structure heterogeneity.

On the Grain Size Distribution of MnO Doped ZnO Ceramics

2007 ◽  
Vol 336-338 ◽  
pp. 2361-2362
Author(s):  
Shu Ai Li ◽  
Da Nian Liu ◽  
Jiang Hong Gong
Keyword(s):  
Grain Size ◽  
Size Distribution ◽  
Grain Size Distribution ◽  
Sintering Temperature ◽  
Grain Morphology ◽  
Holding Time ◽  
Grain Sizes ◽  
Different Temperatures ◽  
Doped Zno ◽  
Zno Ceramics

A series of MnO-doped ZnO with different grain sizes and grain morphologies were prepared by sintering the samples at different temperatures for different holding times. The grain size distribution for each sample was determined. It was found that, although the grain size increases and the grain morphology varies with the sintering temperature and/or the holding time, the normalized grain size distribution keeps invariable.

scholarly journals Investigation of sand in piping

2012 ◽  
pp. 115-128
Author(s):  
Laslo Nadj
Keyword(s):  
Grain Size ◽  
Size Distribution ◽  
Grain Size Distribution ◽  
Solid Particles ◽  
Granular Soils ◽  
Volcanic Cone ◽  
Size Fractions ◽  
Grain Sizes ◽  
High Flood ◽  
Grain Size Fractions

For the investigation of the grain size distribution of the material washed out from the piping, we used 20 samples originating from different places on the Danube and the Tisza rivers. The grading characteristics of these samples were investigated based on selected grain sizes and the uniformity of gradients. Based on the investigations it has become possible to identify which grain size fractions are likely to be washed out, and how to characterize those fractions. Based on the grain size distribution curves it has been made possible to define the boundaries of the zone susceptible to piping. The zone limits of granular soils liquefied by earthquakes and the zone limits of the soil out washed from piping are very similar. This apparent correspondence already formerly raised the hypothetic question of whether piping occurring during high flood can be simulated by shape to similar surface liquefaction phenomena experienced during earthquakes, as in both cases a volcanic cone is formed through the crater of which water is constantly issuing, dragging away solid particles.

scholarly journals Spatial Mapping of Riverbed Grain-Size Distribution Using Machine Learning

2020 ◽  
Vol 2 ◽  
Author(s):  
Huiying Ren ◽  
Zhangshuan Hou ◽  
Zhuoran Duan ◽  
Xuehang Song ◽  
William A. Perkins ◽  
...  
Keyword(s):  
Machine Learning ◽  
Grain Size ◽  
Physical Properties ◽  
Size Distribution ◽  
Grain Size Distribution ◽  
Numerical Models ◽  
Influential Factors ◽  
Velocity Shear ◽  
Sediment Grain Size ◽  
Substrate Size

Recent alluvial sediments in riverbeds play a significant role in controlling hydrologic exchange flows (HEFs) in river systems. The alluvial layer is usually associated with strong heterogeneity in physical properties (e.g., permeability and hydraulic conductivity), which affects local HEFs and therefore biogeochemical processes. The spatial distribution of these physical properties needs to be determined to inform the numerical models used to reveal the realistic hydro-biogeochemical behaviors. Such information can be obtained based on the intrinsic link between sediment grain-size distribution and hydraulic properties where sediment texture information is available. However, grain-size measurements are usually spatially sparse and do not have adequate coverage and resolution, particularly for a relatively large domain such as the Hanford Reach of the Columbia River. In this paper, we adopted machine learning (ML) approaches for categorizing and mapping the spatial distributions of riverbed substrate grain size and filling in missing areas of substrate data using the ML models along the reach. Such ML models for substrate size mapping were trained at 13,372 locations using measured substrate sizes along with observed and simulated attributes, including bathymetric attributes (e.g., elevation, slope, and aspect ratio) from LIDAR and bathymetric surveys, and hydrodynamic properties (e.g., water depth, velocity, shear stress, and their statistical moments). An ensemble bagging-based ML technique, Random Forest, was adopted to identify the most influential factors as predictors to develop the predictive models with over-fitting issues addressed. The models were evaluated with respect to each individual substrate size class and the lumped group, and then used to generate the final substrate size maps covering all the grid cells in the numerical modeling domain.

Production of ceramic bodies from Tunisian Cretaceous clays

Clay Minerals ◽  
2012 ◽  
Vol 47 (1) ◽  
pp. 59-68 ◽  
Author(s):  
M. Hachani ◽  
W. Hajjaji ◽  
B. Moussi ◽  
M. Medhioub ◽  
F. Rocha ◽  
...  
Keyword(s):  
Grain Size ◽  
Physical Properties ◽  
Size Distribution ◽  
Grain Size Distribution ◽  
Late Cretaceous ◽  
Mineralogical Composition ◽  
International Standards ◽  
Raw Material ◽  
Ceramic Tiles ◽  
Firing Range

AbstractThe aim of this research was to assess the potential application of the Late Cretaceous levels as raw material for the production of ceramic tiles. Mineralogical, chemical and grain size distribution studies were carried out on four clays sampled at different sites in the Tunisian Central Atlas. Clays are mainly composed of phyllosilicates, usually illite and kaolinite. Quartz, feldspars and dolomite were also detected.Tiles were prepared by pressing clay bodies at 250 bar and then firing at different temperatures following industrial conditions as closely as possible. Thermal analysis showed the influence of mineralogical composition and grain size distribution on the material behaviour during firing. The physical properties of fired tiles were obtained from specific tests in accordance with international standards (ISO), i.e. the firing shrinkage, water absorption, apparent density and flexural strength. The development of physical properties indicates an optimal firing range between 1050–1150°C. Results demonstrate the potential of Late Cretaceous materials as raw materials for the production of ceramic tiles.

Grain Growth in Vapor Deposited Aluminium Alloys

1986 ◽  
Vol 77 ◽  
Author(s):  
Uwe Köster ◽  
Paul S. Ho
Keyword(s):  
Grain Size ◽  
Size Distribution ◽  
Grain Growth ◽  
Grain Size Distribution ◽  
Aluminium Alloys ◽  
Boundary Migration ◽  
Grain Boundary Migration ◽  
Quantitative Electron Microscopy ◽  
Grain Sizes ◽  
Grain Coalescence

ABSTRACTIn a number of vapor deposited aluminium alloys grain growth has been investigated systematically by means of quantitative electron microscopy and found to proceed not by grain boundary migration, but by grain coalescence. Parameters influencing the observed mode of grain growth will be discussed with respect to the formation of microstructures with optimal resistance to electromigration, i.e. microstructures with large grain size, high homogeneity in the grain size distribution as well as a strong texture.Analyses of grain size distribution after annealing indicate a strong retardation in grain growth by the solute in all aluminium alloys except Al(Cu). Relative large grain sizes and very small lognormal standard deviations have been observed in Al-l%Cu as well as ternary Al(Cu,Hf) thin films.

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