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Articles 1 - 9 of 9
Full-Text Articles in Physical Sciences and Mathematics
Application Of Permutations To Lossless Compression Of Multispectral Thematic Mapper Images, Ziya Arnavut, Sunil Narumalani
Application Of Permutations To Lossless Compression Of Multispectral Thematic Mapper Images, Ziya Arnavut, Sunil Narumalani
Department of Earth and Atmospheric Sciences: Faculty Publications
The goal of data compression is to find shorter representa- tions for any given data. In a data storage application, this is done in order to save storage space on an auxiliary device or, in the case of a communication scenario, to increase channel throughput. Because re- motely sensed data require tremendous amounts of transmission and storage space, it is essential to find good algorithms that utilize the spa- tial and spectral characteristics of these data to compress them. A new technique is presented that uses a spectral and spatial correlation to create orderly data for the compression of multispectral …
Boundary Conditions For Convergent Radial Tracer Tests And Effect Of Well Bore Mixing Volume, Vitaly A. Zlotnik, John David Logan
Boundary Conditions For Convergent Radial Tracer Tests And Effect Of Well Bore Mixing Volume, Vitaly A. Zlotnik, John David Logan
Department of Earth and Atmospheric Sciences: Faculty Publications
Convergent radial flow tracer tests have a complex spatial nonaxial transport structure caused by the flow in the vicinity of the injection well and its finite mixing volume. The formulation of the boundary value problem, and especially the treatment of the boundary conditions at the injection well, is nontrivial. Hodgkinson and Lever [1983], Moench [1989, 1991], and Welty and Gelhar [1994] have developed different models and methods for the analysis of breakthrough curves in the extraction well. To extend interpretation techniques to breakthrough curves in the zone between injection and extraction wells, an analysis of conventional transport models is given, …
Theory Of Dipole Flow In Uniform Anisotropic Aquifers, Vitaly A. Zlotnik, Glenn Ledder
Theory Of Dipole Flow In Uniform Anisotropic Aquifers, Vitaly A. Zlotnik, Glenn Ledder
Department of Earth and Atmospheric Sciences: Faculty Publications
A theory of dipole flow is developed to model flow induced by a vertical circulation well consisting of injection and extraction chambers in a single borehole. Included in the theory are an analytical description of the kinematic flow structure around a vertical circulation well and the drawdown in the well chambers. Using Stokes’ stream function, simple criteria are derived to determine the region of intensive recirculation. This region extends (from the dipole center) approximately five distances between chamber centers in the radial direction and two distances between chamber centers in both vertical directions. The vertical scale does not depend on …
Paleolimnological Records Of Climatic Change In North America, Sherilyn C. Fritz
Paleolimnological Records Of Climatic Change In North America, Sherilyn C. Fritz
Department of Earth and Atmospheric Sciences: Faculty Publications
Lacustrine fossil records provide long time series of data on limnological and climatic conditions; these data are useful for establishing natural patterns of climate variability and for generating testable hypotheses about atmospheric circulation and climate-ecosystem linkages. Shoreline features can indicate past lake-level fluctuations that may reflect changes in moisture balance, but often these records are discontinuous and are evidence of only extreme conditions. The organisms, geochemistry, and sedimentology of lake sediments may provide a more continuous sequence of direct and indirect lake-climate interactions in the past. The most clearly interpretable paleolimnnological records of climatic change are those that use several …
Century-Scale Paleoclimatic Reconstruction From Moon Lake, A Closed-Basin Lake In The Northern Great Plains, Kathleen R. Laird, Sherilyn C. Fritz, Eric C. Grimm, Pietra G. Mueller
Century-Scale Paleoclimatic Reconstruction From Moon Lake, A Closed-Basin Lake In The Northern Great Plains, Kathleen R. Laird, Sherilyn C. Fritz, Eric C. Grimm, Pietra G. Mueller
Department of Earth and Atmospheric Sciences: Faculty Publications
Estimates of past lake-water salinity from fossil diatom assemblages were used to infer past climatic conditions at Moon Lake, a climatically sensitive site in the northern Great Plains. A good correspondence between diatom-inferred salinity and historical records of mean annual precipitation minus evapotranspiration (P - ET) strongly suggests that the sedimentary record from Moon Lake can be used to reconstruct past climatic conditions. Century-scale analysis of the Holocene diatom record indicates four major hydrological periods: an early Holocene transition from an open freshwater system to a closed saline system by 7300 B.P., which corresponds with a transition from spruce forest …
Linking Planktonic Diatoms And Climate Change In The Large Lakes Of The Yellowstone Ecosystem Using Resource Theory, Susan S. Kilham, Edward C. Theriot, Sherilyn C. Fritz
Linking Planktonic Diatoms And Climate Change In The Large Lakes Of The Yellowstone Ecosystem Using Resource Theory, Susan S. Kilham, Edward C. Theriot, Sherilyn C. Fritz
Department of Earth and Atmospheric Sciences: Faculty Publications
Resource-based physiology of the eight important planktonic diatom species in the large lakes of the Yellowstone region can be used to explain their relative abundances and seasonal changes. The diatoms are ranked along resource ratio gradients according to their relative abilities to grow under limitation by Si, N, P, and light. Hypotheses based on resource physiology can be integrated with observations on seasonal changes in diatom assemblages to explain the present distributions of diatoms and to test the causal factors proposed to explain diatom distributions over the Holocene. Knowledge of the limnology of these lakes and process-oriented physiology provide the …
Geology Beneath The Primary Management Systems Evaluation Area (Msea) Site Southwest Of Shelton, Buffalo County, Nebraska, Robert F. Diffendal Jr., Frank A. Smith
Geology Beneath The Primary Management Systems Evaluation Area (Msea) Site Southwest Of Shelton, Buffalo County, Nebraska, Robert F. Diffendal Jr., Frank A. Smith
Department of Earth and Atmospheric Sciences: Faculty Publications
In 1990, as part of a national presidential initiative on water quality, researchers from the University of Nebraska-Lincoln (UNL) Institute of Agriculture and Natural Resources (IANR) received a multi-year grant from the United States Department of Agriculture, Cooperative State Research Service, to study management of irrigated com and soybeans to minimize groundwater contamination. D.G. Watts, R.F. Spalding, and J.S. Schepers, of the IANR led a study at one of the Management Systems Evaluation Areas (MSEA). This area was made up of two sites, a primary site on a terrace of the Platte River near Shelton and a secondary site nearer …
Estimation And Abundances In Two-Component Mineral Mixtures Using Mid-Infrared Laser Reflectance Ratios, Ram M. Narayanan, Kristin K. Warner, Robert F. Diffendal Jr.
Estimation And Abundances In Two-Component Mineral Mixtures Using Mid-Infrared Laser Reflectance Ratios, Ram M. Narayanan, Kristin K. Warner, Robert F. Diffendal Jr.
Department of Earth and Atmospheric Sciences: Faculty Publications
The mid-infrared spectral region (8-14 μm wavelength) is emerging as a viable geologic remote sensing tool due to the presence of reststrahlen bands for minerals such as silicates and carbonates. An experimental study was carried out to characterize the mid-infrared laser reflectance of mineral mixtures, and to explore the potential of laser remote sensing systems to estimate mineral abundances in two-component mixtures. An empirical model was developed to establish a relationship between laser reflectance ratios at judiciously selected wavelengths and percentage of one of the minerals in the mixture. It was found that the abundances can be estimated to within …
Upper Cretaceous Calcareous Nannofossil Biostratigraphy And Paleoceanography Of The Southern Ocean, David K. Watkins, Sherwood W. Wise Jr., James J. Popsichal, Jason Crux
Upper Cretaceous Calcareous Nannofossil Biostratigraphy And Paleoceanography Of The Southern Ocean, David K. Watkins, Sherwood W. Wise Jr., James J. Popsichal, Jason Crux
Department of Earth and Atmospheric Sciences: Faculty Publications
Nannofossil data from the Naturaliste Plateau (DSDP Legs 26 & 28), Falkland Plateau (DSDP Legs 36 & 71), Maud Rise (ODP Leg 113), Northeast Georgia Rise (ODP Leg 114), and Kerguelen Plateau (ODP Leg 120) yield a set of consistent, reliable biohorizons that form the basis of a revised calcareous nannofossil zonation for the Southern Ocean Upper Cretaceous. Analysis of this zonation indicates significant changes in the circum-Antarctic climatic regime during the Campanian and Maastrichtian that foreshadow the more dramatic climatic shifts of the Palaeogene. Calcareous nannofossils from the Turonian through the Lower Campanian of the studied sections are characterized …