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17 results on '"Pryde, A. K. A."'

6. Comparison of watershed boundaries derived from SRTM and ASTER digital elevation datasets and from a digitized topographic map

Author

Pryde, J. K., Osorio, J., Wolfe, Mary Leigh, Heatwole, Conrad D., Benham, Brian L., Cardenas, A., Pryde, J. K., Osorio, J., Wolfe, Mary Leigh, Heatwole, Conrad D., Benham, Brian L., and Cardenas, A.

Abstract

Watersheds are natural integrators of hydrological, biological, and geological processes and as such require an integrated approach to data analysis and modeling, which usually starts delineating accurately a polygon vector layer of watershed boundaries as input. In that way, the Río Illangama watershed in Alto Guanujo, Ecuador, had been isolated with the objective of evaluate the accuracy of watershed boundaries derived from three different sources: One was delineated by hand and the other two were derived from a 30-m ASTER DEM and a 90-m SRTM DEM, using the Spatial Analyst extension of ArcGIS. Visually, there are small differences between the manually-delineated and the SRTM-based boundaries, while the ASTER-based varies from the manually-delineated one. The area of the watershed delineated manually is 13,061.3 ha, while the SRTM-based and the ASTER-based watershed are 0.66% and 2.6% larger. The regression analyses comparing the complete boundaries yielded an R2 of 0.999 between the SRTM and manual boundaries and the 0.988 for the ASTER and the manual boundaries. The t-test comparing DEMs indicated a significant difference (p

Published
2007

7. Comparison of watershed boundaries derived from SRTM and ASTER digital elevation datasets and from a digitized topographic map

Author

Sustainable Agriculture and Natural Resource Management (SANREM) Knowledgebase, Pryde, J. K., Osorio, J., Wolfe, Mary Leigh, Heatwole, Conrad D., Benham, Brian L., Cardenas, A., Sustainable Agriculture and Natural Resource Management (SANREM) Knowledgebase, Pryde, J. K., Osorio, J., Wolfe, Mary Leigh, Heatwole, Conrad D., Benham, Brian L., and Cardenas, A.

Abstract

Watersheds are natural integrators of hydrological, biological, and geological processes and as such require an integrated approach to data analysis and modeling, which usually starts delineating accurately a polygon vector layer of watershed boundaries as input. In that way, the Río Illangama watershed in Alto Guanujo, Ecuador, had been isolated with the objective of evaluate the accuracy of watershed boundaries derived from three different sources: One was delineated by hand and the other two were derived from a 30-m ASTER DEM and a 90-m SRTM DEM, using the Spatial Analyst extension of ArcGIS. Visually, there are small differences between the manually-delineated and the SRTM-based boundaries, while the ASTER-based varies from the manually-delineated one. The area of the watershed delineated manually is 13,061.3 ha, while the SRTM-based and the ASTER-based watershed are 0.66% and 2.6% larger. The regression analyses comparing the complete boundaries yielded an R2 of 0.999 between the SRTM and manual boundaries and the 0.988 for the ASTER and the manual boundaries. The t-test comparing DEMs indicated a significant difference (p

Published
2007

16. Analysis of the incommensurately modulated OS phase of SiO2 tridymite.

Author

Pryde, Alexandra K. A. and Heine, Volker

Abstract

The structure, symmetry and origin of the incommensurately modulated OS phase of tridymite (SiO2) and its lock-in to the OP three-fold superlattice structure are discussed in a computational study. The structure of the OS phase (which has not been determined experimentally) is deduced as the only geometrically possible structure derived from the parent OC phase by rotation and translation of the SiO4 tetrahedra without significant distortion of these units. It can be visualised conveniently in terms of the McConnell formalism of two component difference structures C1 and C2 whose space group symmetries are derived. The results are in accordance with the known lock-in structure at wave vector Q= a*. In the latter, the ±C1 regions expand and the structure can square up in a very general way to take advantage of the lost symmetries (lost compared with the OC phase). [ABSTRACT FROM AUTHOR]

Published
1998
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17. Cars vs bikes.

Author

Pryde, W. K.

Subjects
*LETTERS to the editor, *BICYCLES
Abstract

A letter to the editor is presented in response to the article "Through Afghan eyes."

Published
2008

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