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Full-Text Articles in Physical Sciences and Mathematics

Mid- And Low-Latitude Prompt-Penetration Ionospheric Zonalplasma Drifts, Bela G. Fejer, L. Scherliess Aug 1998

Mid- And Low-Latitude Prompt-Penetration Ionospheric Zonalplasma Drifts, Bela G. Fejer, L. Scherliess

Bela G. Fejer

We have used ion drift observations from the DE-2 satellite to determine the latitudinal variation and the temporal evolution of mid- and low-latitude prompt penetration zonal plasma drifts driven by magnetospheric electric fields. Our results indicate that sudden increases in convection lead to predominantly westward perturbation drifts which decrease equartorwards and have largest amplitudes in the dusk-midnight sector. The diurnal perturbation drift patterns shift to later local times with increasing storm time and decay to new quasi-equilibrium values in about 2 hours, as the ring current readjusts to the new polar cap potential. The daily and latitudinal variations and temporal …


Satellite Studies Of Mid- And Low-Latitude Ionospheric Disturbancezonal Plasma Drifts, L. Scherliess, Bela G. Fejer May 1998

Satellite Studies Of Mid- And Low-Latitude Ionospheric Disturbancezonal Plasma Drifts, L. Scherliess, Bela G. Fejer

Bela G. Fejer

We use low- and mid-latitude zonal ion drift observations from the DE-2 satellite and auroral electrojet indices to study the temporal and latitudinal variations of F-region perturbation drifts during magnetically disturbed conditions. These perturbation drifts are driven by magnetospheric and ionospheric disturbance dynamo electric fields with time constants from less than one to several hours. We determine, initially, the drift patterns due to the prompt penetration of magnetospheric electric fields and of longer lasting disturbances. In this study, we concentrate on the properties of the longer lasting perturbations which occur with latitude-dependent time delays after enhancements in the high-latitude ionospheric …


Overcoming The Multiplex‐Disadvantage Using Maximum‐Likelihood Inversion, Stephen E. Bialkowski Jan 1998

Overcoming The Multiplex‐Disadvantage Using Maximum‐Likelihood Inversion, Stephen E. Bialkowski

Stephen E. Bialkowski

A maximum-likelihood estimator, derived under quantum-noiselimited measurement conditions, is used to obtain wavenumber-ordered spectra produced by a model Michelson interferometer. The estimator is tested on a number of synthetic interferograms, and results are compared to similar spectra obtained by using the Fourier (cosine) transform. It is found that the maximum-likelihood inversion method does not result in white noise in the spectrum estimate when the spectrum is sparse. It thus may be used to circumvent the main disadvantage in multiplexed spectrometer measurements using quantum-noise-limited detectors for emissionbased measurements. It is also found that maximum-likelihood inversion methods can be used to obtain …


Games To Teach Mathematical Modelling, James A. Powell, J. Cangelosi, A. M. Harris Jan 1998

Games To Teach Mathematical Modelling, James A. Powell, J. Cangelosi, A. M. Harris

James A. Powell

We discuss the use of in-class games to create realistic situations for mathematical modelling. Two games are presented which are appropriate for use in post-calculus settings. The first game reproduces predator{prey oscillations and the second game simulates disease propagation in a mixing population. When used creatively these games encourage students to model realistic data and apply mathematical concepts to understanding the data.


Geometry,Mechanisms, And Significance Of Extensional Folds From Examples In The Rockymountain Basin And Range Province, Susanne U. Janecke, C. J. Vandenburg, J. J. Blankenau Jan 1998

Geometry,Mechanisms, And Significance Of Extensional Folds From Examples In The Rockymountain Basin And Range Province, Susanne U. Janecke, C. J. Vandenburg, J. J. Blankenau

Susanne U. Janecke

No abstract provided.