The potential use of petrological analysis in provenancing volcanic ash. Tempering in lowland maya pottery

1981 ◽  
Vol 1 (1) ◽  
pp. 147-150
Author(s):  
L. Jones
Keyword(s):  
Volcanic Ash ◽  
Potential Use ◽  
Lowland Maya

The Analysis and Distribution of Volcanic Ash-Tempered Pottery in the Lowland Maya Area

1979 ◽  
Vol 44 (1) ◽  
pp. 79-91 ◽  
Author(s):  
Michael P. Simmons ◽  
Gerald F. Brem
Keyword(s):  
El Salvador ◽  
Volcanic Ash ◽  
Petrographic Analysis ◽  
Time And Space ◽  
Maya Area ◽  
Lowland Maya

Petrographic analysis of potsherds from Dzibilchaltun and other Maya sites conclusively establishes the presence of volcanic ash temper in ceramics from northern Yucatan. The distribution of ash-tempered ceramics in time and space suggests import of ash in bulk from sources in highland Guatemala or El Salvador in exchange for salt. The homogeneous nature of the ash in northwestern Yucatan supports the idea that certain trading organizations enjoyed exclusive access to that region, while competing for markets in other lowland areas.

scholarly journals Neural network multispectral satellite images classification of volcanic ash plumes in a cloudy scenario

2015 ◽  
Vol 57 ◽  
Author(s):  
Matteo Picchiani ◽  
Marco Chini ◽  
Stefano Corradini ◽  
Luca Merucci ◽  
Alessandro Piscini ◽  
...  
Keyword(s):  
Neural Network ◽  
Volcanic Ash ◽  
Satellite Images ◽  
Test Cases ◽  
Multispectral Images ◽  
The Neural Network ◽  
Multispectral Satellite Images ◽  
Potential Use

<div class="WordSection1"><div class="page" title="Page 1"><div class="layoutArea"><div class="column"><p><span>This work shows the potential use of neural networks in the characterization of eruptive events monitored by satellite, through fast and automatic classification of multispectral images. The algorithm has been developed for the MODIS instrument and can easily be extended to other similar sensors. Six classes have been defined paying particular attention to image regions that represent the different surfaces that could possibly be found under volcanic ash clouds. Complex cloudy scenarios composed by images collected during the Icelandic eruptions of the Eyjafjallajökull (2010) and Grimsvötn (2011) volcanoes have been considered as test cases. A sensitivity analysis on the MODIS TIR and VIS channels has been performed to optimize the algorithm. The neural network has been trained with the first image of the dataset, while the remaining data have been considered as independent validation sets. Finally, the neural network classifier’s results have been compared with maps classified with several interactive procedures performed in a consolidated operational framework. This comparison shows that the automatic methodology proposed achieves a very promising performance, showing an overall accuracy greater than 84%, for the Eyjafjalla - jökull event, and equal to 74% for the Grimsvötn event. </span></p></div></div></div><p><em><br /></em></p><p><em><br /></em></p></div><em><br clear="all" /></em>

scholarly journals Measuring Water Content of Soil Substitutes with Time-domain Reflectometry (TDR)

1998 ◽  
Vol 123 (4) ◽  
pp. 734-737 ◽  
Author(s):  
F.F. da Silva ◽  
R. Wallach ◽  
A. Polak ◽  
Y. Chen
Keyword(s):  
Water Content ◽  
Volcanic Ash ◽  
Irrigation Management ◽  
Linear Equations ◽  
Bound Water ◽  
Time Domain Reflectometry ◽  
Grape Marc ◽  
Controlled Environments ◽  
Calibration Equations ◽  
Potential Use

Optimization of irrigation and fertilization regimes in greenhouses and other controlled environments requires accurate and frequent measurements of soil-water content. Recent studies on TDR use in gravely soils and in closed-container studies have indicated a potential use of this method in horticulture. In this study, TDR calibration curves were determined for tuff (granulated volcanic ash), vermiculite, perlite and a mix of two composted agricultural wastes (grape marc, separated cow manure). Widely used as horticultural substrates, mixes of these materials were tested as well. For all soil substitutes tested, measured calibration results are well described by linear equations throughout tested values of water content that cover the working range in horticulture. Ledieu's equation, widely used in soils, describes fairly well the measured results for perlite, but underestimates those obtained for organic media, vermiculite (because of the presence of bound water) and tuff (probably due to water in occluded pores). The differences obtained between the measured calibration equations and Ledieu's equation indicate that in order to avoid an erroneous irrigation management, calibration is necessary whenever a new soil substitute is used.

The growth of mica polytypes as studied by conventional and high-resolution TEM

1983 ◽  
Vol 41 ◽  
pp. 174-177
Author(s):  
A. Baronnet ◽  
M. Amouric
Keyword(s):  
Water Pressure ◽  
Point Of View ◽  
Temperature Fields ◽  
Natural Occurrence ◽  
Growth Mechanisms ◽  
Long Period ◽  
High Resolution Tem ◽  
Layer Stacking ◽  
Experimental Works ◽  
Potential Use

The origin of mica polytypes has long been a challenging problem for crystal- lographers, mineralogists and petrologists. From the petrological point of view, interest in this field arose from the potential use of layer stacking data to furnish further informations about equilibrium and/or kinetic conditions prevailing during the crystallization of the widespread mica-bearing rocks. From the compilation of previous experimental works dealing with the occurrence domains of the various mica "polymorphs" (1Mr, 1M, 2M1, 2M2 and 3T) within water-pressure vs temperature fields, it became clear that most of these modifications should be considered as metastable for a fixed mica species. Furthermore, the natural occurrence of long-period (or complex) polytypes could not be accounted for by phase considerations. This highlighted the need of a more detailed kinetic approach of the problem and, in particular, of the role growth mechanisms of basal faces could play in this crystallographic phenomenon.

An atomic-resolution microscope study of Al contracts on GaAs

1986 ◽  
Vol 44 ◽  
pp. 726-727
Author(s):  
Z. Liliental-Weber ◽  
C. Nelson ◽  
R. Ludeke ◽  
R. Gronsky ◽  
J. Washburn
Keyword(s):  
High Speed ◽  
Schottky Contacts ◽  
Detailed Knowledge ◽  
The Past ◽  
Semiconductor Interfaces ◽  
Deposited Metal ◽  
Microwave Applications ◽  
Free Interfaces ◽  
Potential Use

The properties of metal/semiconductor interfaces have received considerable attention over the past few years, and the Al/GaAs system is of special interest because of its potential use in high-speed logic integrated optics, and microwave applications. For such materials a detailed knowledge of the geometric and electronic structure of the interface is fundamental to an understanding of the electrical properties of the contact. It is well known that the properties of Schottky contacts are established within a few atomic layers of the deposited metal. Therefore surface contamination can play a significant role. A method for fabricating contamination-free interfaces is absolutely necessary for reproducible properties, and molecularbeam epitaxy (MBE) offers such advantages for in-situ metal deposition under UHV conditions

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