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Articles 1 - 30 of 97
Full-Text Articles in Physical Sciences and Mathematics
Optical Estimation Of Auroral Ion Upflow: Theory, M. Zettergren, J. L. Semeter, P. L. Blelly, M. Diaz
Optical Estimation Of Auroral Ion Upflow: Theory, M. Zettergren, J. L. Semeter, P. L. Blelly, M. Diaz
Publications
This work presents a systematic analysis of optical emissions related to auroral ion upflow. Optical intensities and field‐aligned ion transport are computed for a set of monoenergetic incident electron beams using a combined fluid‐kinetic model. The kinetic portion models the energetic particle transport with a multiple stream approach and provides ionization, excitation, and heating rates to an eight‐moment fluid model of the ionosphere, which then calculates the resulting ion upflow. The analysis is used to develop a technique for estimating upward ion flux from photometric measurements at five discrete wavelengths: 427.8 nm, 557.7 nm, 630.0 nm, 732 nm, and 844.6 …
The General Relativistic Infinite Plane, Preston Jones, Gerardo Muñoz, Michael Ragsdale, Douglas Singleton
The General Relativistic Infinite Plane, Preston Jones, Gerardo Muñoz, Michael Ragsdale, Douglas Singleton
Publications
Uniform fields are one of the simplest and most pedagogically useful examples in introductory courses on electrostatics or Newtonian gravity. In general relativity there have been several proposals as to what constitutes a uniform field. In this article we examine two metrics that can be considered the general relativistic version of the infinite plane with finite mass per unit area. The first metric is the 4D version of the 5D “brane” world models which are the starting point for many current research papers. The second case is the cosmological domain wall metric. We examine to what extent these different metrics …
Electromagnetic Radiation From Temporal Variations In Space-Time And Progenitors Of Gamma Ray Burst And Millisecond Pulsars, Preston Jones
Electromagnetic Radiation From Temporal Variations In Space-Time And Progenitors Of Gamma Ray Burst And Millisecond Pulsars, Preston Jones
Publications
A time varying space–time metric is shown to be a source of electromagnetic radiation even in the absence of charge sources. The post-Newtonian approximation is used as a realistic model of the connection between the space–time metric and a time-varying gravitational potential. Rapid temporal variations in the metric from the coalescence of relativistic stars are shown to be likely progenitors of gamma ray burst and millisecond pulsars.
On The Variability Of Mesospheric Oh Emission Profiles, Romina Nikoukar, Gary R. Swenson, Alan Z. Liu, Farzad Kamalabadi
On The Variability Of Mesospheric Oh Emission Profiles, Romina Nikoukar, Gary R. Swenson, Alan Z. Liu, Farzad Kamalabadi
Physical Sciences - Daytona Beach
Mesospheric OH radiance limb profiles measured by the Sounding of the Atmosphere using Broadband Emission Radiometry (SABER) instrument aboard the Thermosphere Ionosphere Mesosphere Energetics and Dynamics (TIMED) spacecraft were inverted to yield altitude profiles of OH volume emission rates. The Abel inversion results of two months of data (from 1 June to 31 July 2004) were analyzed for the layer mean and standard deviation as a function of latitude and local time. Statistical analysis of SABER data shows that the global difference between the mean and standard deviation profiles for the OH(vu = 7, 8, 9; ∆v …
Enhancement Of Nd: Yag Libs Emission Of A Remote Target Using A Simultaneous Co/Sub 2/ Laser Pulse, Dennis K. Killinger, Susan D. Allen, Robert D. Waterbury, Chris Stefano, Edwin L. Dottery
Enhancement Of Nd: Yag Libs Emission Of A Remote Target Using A Simultaneous Co/Sub 2/ Laser Pulse, Dennis K. Killinger, Susan D. Allen, Robert D. Waterbury, Chris Stefano, Edwin L. Dottery
Publications
For the first time to the best of our knowledge, a simultaneous 10.6 μm CO2 laser pulse has been used to enhance the Laser Induced Breakdown Spectroscopy (LIBS) emission from a 1.064 μm Nd:YAG laser induced plasma on a hard target. The enhancement factor was on the order of 25 to 300 times, depending upon the emission lines observed. For an alumina ceramic substrate the Al emission lines at 308 nm and Fe impurity line at 278 nm showed an increase of 60x and 119x, respectively. The output energy of the Nd:YAG laser was 50 mJ/pulse focused to a 1 …
Book Review: Moore On Mercury: The Planet And The Missions, T. D. Oswalt
Book Review: Moore On Mercury: The Planet And The Missions, T. D. Oswalt
Publications
This document is Dr. Oswalt’s review of Moore on Mercury : the Planet and the Missions by Patrick Moore. Springer, 2006 139p, 1846282578 $29.95, 9781846282577 $29.95
Characteristics Of Short-Period Wavelike Features Near 87 Km Altitude From Airglow And Lidar Observations Over Maui, J. H. Hecht, A. Z. Liu, R. L. Walterscheid, S. J. Franke, R. J. Rudy, M. J. Taylor, P. -D. Pautet
Characteristics Of Short-Period Wavelike Features Near 87 Km Altitude From Airglow And Lidar Observations Over Maui, J. H. Hecht, A. Z. Liu, R. L. Walterscheid, S. J. Franke, R. J. Rudy, M. J. Taylor, P. -D. Pautet
Physical Sciences - Daytona Beach
Small-scale (less than 15 km horizontal wavelength) wavelike structures known as ripples are a common occurrence in OH airglow images. Recent case studies attribute their origin to the presence of either convective or dynamical instabilities. However, little is known about their frequency of occurrence and period. The Maui-MALT Observatory, located at Mt. Haleakala, is instrumented with a Na wind/temperature lidar, which allows the determination of whether the atmosphere is dynamically or convectively unstable, and a fast OH airglow camera which takes images every 3 s with a sensitivity high enough to see the ripples. This study reports on 2 months …
Gis Assessment Of Environmental Impacts On Urban Forests, Richard Snow, Mary Snow
Gis Assessment Of Environmental Impacts On Urban Forests, Richard Snow, Mary Snow
Publications
No abstract provided.
Wide-Field Survey Of Globular Clusters In M31. I. A Catalog Of New Clusters, Sang Chul Kim, Myung Gyoon Lee, Doug Geisler, Ata Sarajedini, Hong Soo Park, Ho Seong Hwang, William E. Harris, Juan C. Seguel, Ted Von Hippel
Wide-Field Survey Of Globular Clusters In M31. I. A Catalog Of New Clusters, Sang Chul Kim, Myung Gyoon Lee, Doug Geisler, Ata Sarajedini, Hong Soo Park, Ho Seong Hwang, William E. Harris, Juan C. Seguel, Ted Von Hippel
Publications
We present the result of a wide-field survey of globular clusters (GCs) in M31 covering a 3o x 3o field centered on M31.We have searched for GCs on CCD images taken with Washington CMT1 filters at the KPNO 0.9 m telescope using the following steps: (1) inspection of morphological parameters given by the SExtractor package such as stellarity, full width at half-maximum, and ellipticity; (2) consulting the spectral types and radial velocities obtained from spectra taken with the Hydra spectrograph at the WIYN 3.5 m telescope; and (3) visual inspection of the images of each object. We …
Testing Lorentz Symmetry With Gravity, Quentin G. Bailey
Testing Lorentz Symmetry With Gravity, Quentin G. Bailey
Publications
In this talk, results from the gravitational sector of the Standard-Model Extension (SME) are discussed. The weak-field phenomenology of the resulting modified gravitational field equations is explored. The application of the results to a variety of modern gravity experiments, including lunar laser ranging, Gravity Probe B, binary pulsars, and Earth-laboratory tests, shows promising sensitivity to gravitational coefficients for Lorentz violation in the SME.
Gis Analysis Of Lightning Strikes Within A Tornadic Environment, Richard Snow, Mary Snow, Nicole Kufa
Gis Analysis Of Lightning Strikes Within A Tornadic Environment, Richard Snow, Mary Snow, Nicole Kufa
Publications
Recent research suggests that a maximum rate of lightning strikes occurs at least 15 to 20 minutes prior to tornado formation within a supercell storm. These maxima are associated with strengthening updrafts as they appear in radar measurements. An increase in lightning rates correlates with an increase of shear in the lower part of the storm. In combination with a strong updraft or downdraft, this shear can provide the ingredients for rotation and possibly a tornado. Polarity reversal of lightning around the time of tornado touchdown also has been examined. Thus, increasing lightning flash rates and reversal of lightning strike …
Evolution Of The American Ecological Paideia, Mary Snow, Richard K. Snow
Evolution Of The American Ecological Paideia, Mary Snow, Richard K. Snow
Publications
No abstract provided.
A Multimedia Approach To Climate Change Education, Richard Snow, Mary Snow
A Multimedia Approach To Climate Change Education, Richard Snow, Mary Snow
Publications
This paper discusses the development of an upper-level college course on Climate Change created as part of an interdisciplinary Honors Seminar Series. The course makes use of multimedia instructional techniques to examine the physical, economic, and political dynamics of climate change. The curriculum includes an appraisal of assorted global warming websites, computer-based simulations and analysis of relevant climate data, as well as a review of the literature and other media including documentaries such as An Inconvenient Truth. The so-called global warming debate subsidized by the fossil fuel industry also is discussed.
Scattered Homoclinics To A Class Of Time-Recurrent Hamiltonian Systems, Gregory S. Spradlin
Scattered Homoclinics To A Class Of Time-Recurrent Hamiltonian Systems, Gregory S. Spradlin
Mathematics - Daytona Beach
A second-order Hamiltonian system with time recurrence is studied. The recurrence condition is weaker than almost periodicity. The existence is proven of an infinite family of solutions homoclinic to zero whose support is spread out over the real line. © EDP Sciences, SMAI 2007.
Measurements Of Mesospheric Sodium Abundance Above The Hawaiian Islands, Lewis C. Roberts, Jr., L. William Bradford, Christopher R. Neyman, Alan Z. Liu
Measurements Of Mesospheric Sodium Abundance Above The Hawaiian Islands, Lewis C. Roberts, Jr., L. William Bradford, Christopher R. Neyman, Alan Z. Liu
Physical Sciences - Daytona Beach
Laser guide stars have increased the utility of adaptive optics systems by expanding the number of observable objects. The most common type of laser excites sodium in the mesosphere, and mesospheric sodium density is key to the performance of the laser. While a variety of observatories have conducted studies of the mesospheric sodium density, there are no published studies from Hawaii, which is home to some of the largest telescopes in the world. This paper presents mesospheric sodium densities measured by the University of Illinois lidar for 165 hr spanning 25 nights over 3 years. The mean sodium column density …
O(1s), Oh, And O2(B) Airglow Layer Perturbations Due To Agws And Their Implied Effects On The Atmosphere, Fabio Vargas, Gary Swenson, Alan Liu, Delano Gobbi
O(1s), Oh, And O2(B) Airglow Layer Perturbations Due To Agws And Their Implied Effects On The Atmosphere, Fabio Vargas, Gary Swenson, Alan Liu, Delano Gobbi
Physical Sciences - Daytona Beach
The O(1S) (green line) night airglow emission in response to atmospheric gravity wave (AGW) perturbations was simulated with a linear, one-dimensional model. The results were combined with previously modeled O2(b, 0–1) atmospheric band and OH Meinel band emission response (Liu and Swenson, 2003) to derive amplitude and phase relations among multiple airglow layers in response to gravity waves with various intrinsic parameters and damping rates (β). The simulations show that the vertical profile of the standard deviation of the perturbed green line volume emission rate (VER) has a centroid altitude that is 3 km …
Scattered Homoclinics To A Class Of Time-Recurrent Hamiltonian Systems, Gregory S. Spradlin
Scattered Homoclinics To A Class Of Time-Recurrent Hamiltonian Systems, Gregory S. Spradlin
Greg S. Spradlin Ph.D.
A second-order Hamiltonian system with time recurrence is studied. The recurrence condition is weaker than almost periodicity. The existence is proven of an infinite family of solutions homoclinic to zero whose support is spread out over the real line.
A Spitzer White Dwarf Infrared Survey, F. Mullally, Ted Von Hippel, Et Al.
A Spitzer White Dwarf Infrared Survey, F. Mullally, Ted Von Hippel, Et Al.
Publications
We present mid-infrared photometry of 124 white dwarf stars with the Spitzer Space Telescope. Objects were observed simultaneously at 4.5 and 8.0 μm with sensitivities better than 0.1 mJy. This data set can be used to test models of white dwarf atmospheres in a new wavelength regime, as well as to search for planetary companions and debris disks.
Numerical Modeling Of A Gravity Wave Packet Ducted By The Thermal Structure Of The Atmosphere, Yonghui Yu, Michael P. Hickey Ph.D.
Numerical Modeling Of A Gravity Wave Packet Ducted By The Thermal Structure Of The Atmosphere, Yonghui Yu, Michael P. Hickey Ph.D.
Publications
A time-dependent and fully nonlinear numerical model is employed to solve the Navier-Stokes equations in two spatial dimensions and to describe the propagation of a Gaussian gravity wave packet generated in the troposphere. A Fourier spectral analysis is used to analyze the frequency power spectra of the wave packet, which propagates through and dwells within several thermal ducting regions. The frequency power spectra of the wave packet are derived at several discrete altitudes, which allow us to determine the evolution of the packet. This spectral analysis also clearly reveals the existence of a stratospheric duct, a mesospheric and lower thermospheric …
Internet Enabled Remote Driving Of A Combat Hybrid Electric Power System For Duty Cycle Measurement, Jarrett Goodell, Marc Compere, Wilford Smith, Mark Brudnak, Mike Pozolo, Et Al.
Internet Enabled Remote Driving Of A Combat Hybrid Electric Power System For Duty Cycle Measurement, Jarrett Goodell, Marc Compere, Wilford Smith, Mark Brudnak, Mike Pozolo, Et Al.
Publications
This paper describes a human-in-the-loop motion-based simulator interfaced to hybrid-electric power system hardware, both of which were used to measure the duty cycle of a combat vehicle in a virtual simulation environment. The project discussed is a greatly expanded follow-on to the experiment published in [1,7]. This paper is written in the context of [1,7] and therefore highlights the enhancements. The most prominent of these enhancements is the integration (in real-time) of the Power & Energy System Integration Lab (P&E SIL) with a motion base simulator by means of a “long haul” connection over the Internet (a geographical distance of …
Numerical Simulation Of Waves And Fronts In Inhomogeneous Solids, A. Berezovski, M. Berezovski, J. Engelbrecht, G. A. Maugin
Numerical Simulation Of Waves And Fronts In Inhomogeneous Solids, A. Berezovski, M. Berezovski, J. Engelbrecht, G. A. Maugin
Publications
Dynamic response of inhomogeneous materials exhibits new effects, which often do not exist in homogeneous media. It is quite natural that most of studies of wave and front propagation in inhomogeneous materials are associated with numerical simulations. To develop a numerical algorithm and to perform the numerical simulations of moving fronts we need to formulate a kinetic law of progress relating the driving force and the velocity of the discontinuity. The velocity of discontinuity is determined by means of the non-equilibrium jump relations at the front. The obtained numerical method generalizes the wave-propagation algorithm to the case of moving discontinuities …