Open Access. Powered by Scholars. Published by Universities.®

Physical Sciences and Mathematics Commons™

Open Access. Powered by Scholars. Published by Universities.®

PDF

Florida Institute of Technology

1998

Articles 1 - 18 of 18

Full-Text Articles in Physical Sciences and Mathematics

Time Series Energy Production In Smoothed Particle Hydrodynamics Accretion Disks: Superhumps In The Am Canum Venaticorum Stars, James C. Simpson, Matt A. Wood Oct 1998

Time Series Energy Production In Smoothed Particle Hydrodynamics Accretion Disks: Superhumps In The Am Canum Venaticorum Stars, James C. Simpson, Matt A. Wood

Aerospace, Physics, and Space Science Faculty Publications

The energy production time series of our purely hydrodynamic accretion disk simulations display remarkable similarities with the observed light curves of dwarf novae superhumps in general and the AM CVn stars in particular. The superhump period excess as a function of mass ratio agrees well with earlier theoretical and numerical results, and the amplitudes and relative phases of the harmonics in the power spectra agree well with the observations. The morphology of the mean pulse profile appears to be a useful predictor of system mass ratio. Our modified smoothed particle hydrodynamics code time symmetrizes the interparticle forces when individual time …

Go to article

The Design And Evaluation Of Distributed Graph-Theoretic Heuristics For Computing Pairwise Interactions Of Moving Entities, Darren R. Law Sep 1998

The Design And Evaluation Of Distributed Graph-Theoretic Heuristics For Computing Pairwise Interactions Of Moving Entities, Darren R. Law

Link Foundation Modeling, Simulation and Training Fellowship Reports

In recent years the focus of training simulations, particularly those in the defense domain, has been on increasing the number of simulated entities. This focus, coupled with the requirement for geographically distributed training sites, has led to increased interest in distributed simulation of the battlefield environment. The large efforts involved in the development of the DIS (Distributed Interactive Simulation) protocol and the HLA (High Level Architecture) have attempted to address these DoD (Department of Defense) requirements in several ways. The cost of con1puting the interactions between pairs of simulated entities frequently dominates system execution time. The difficulty of evaluating these …

Go to article

Vision-Based Tracking With Dynamic Structure Light, Mark A. Livingston Sep 1998

Vision-Based Tracking With Dynamic Structure Light, Mark A. Livingston

Link Foundation Modeling, Simulation and Training Fellowship Reports

The term virtual reality (VR) has been used in the popular press to describe systems that completely replace the user's view with computer graphics, a view of a synthetic world. Such systems allow building designers to visualize the "completed" building and potential problems in the design before construction. A VR system might allow scientists to view environments as large as galaxies or as small as atoms as if they were human-sized. The primary benefit in these cases would be to interact in more natural ways with objects that, due to their sizes, are usually beyond our reach. In academic literature, …

Go to article

A Wavelet-Based Approach To Dynamic Environments, Glenn A. Martin Sep 1998

A Wavelet-Based Approach To Dynamic Environments, Glenn A. Martin

Link Foundation Modeling, Simulation and Training Fellowship Reports

This paper demonstrates a new approach for terrain representation: multiresolution surfaces based on wavelets and the process of multiresolution analysis. Because they are based on mathematical surfaces, multiresolution surfaces gain the benefits of surfaces (more level of detail control, increased number of possible resolutions, easier updates of a dynamic terrain) that lead to fewer correlation errors both in non-networked and networked simulations. Furthermore, the power of multiple resolutions (at little added cost) reduces network transmission costs and provides a framework for the use of dynamic terrain in shared virtual worlds.

Go to article

Software Tools For Solid Freeform Fabrication, Robert Franceschini Sep 1998

Software Tools For Solid Freeform Fabrication, Robert Franceschini

Link Foundation Modeling, Simulation and Training Fellowship Reports

A structured design methodology played a key role in the VLSI (Very Large Scale Integration) revolution. In this methodology, the design is abstracted at different levels (viz. system, function, logic, circuit, and layout) taking into account concerns relevant to a particular level of abstraction. This allows development of CAD tools that can describe, synthesize, and simulate the design at high levels of abstraction independent of the details of the lower levels. In recent years, many researchers have observed that the lessons learned from the "VLSI experience" could be profitably applied to new classes of manufacturing processes called SFF (Solid Freeform …

Go to article

Imaging Derivative Spectroscopy For Vegetation Dysfunction Assessments, Charles R. Bostater Sep 1998

Imaging Derivative Spectroscopy For Vegetation Dysfunction Assessments, Charles R. Bostater

Ocean Engineering and Marine Sciences Faculty Publications

The practical application of current airborne and future satellite or space station based high spectral resolution (hyperspectral) imagery to vegetative canopies (sparse or dense) and resulting derived bio-physical variables will depend upon our ability to rapidly apply scientifically based algorithms. Key to these rapid assessments is the selection ofthe best or optimal channels or bands for detection of plant stress or dysfunction. Previous work '2,3,4,5 has demonstrated the potential of utilizing high spectral resolution optical signatures for detecting plant stress related to the vegetation's moisture within the leaf structure. Future algorithms and techniques need to discriminate plant species as well …

Go to article

Specific Absorption And Backscatter Coefficient Signatures In Southeastern Atlantic Coastal Waters, Charles R. Bostater Sep 1998

Specific Absorption And Backscatter Coefficient Signatures In Southeastern Atlantic Coastal Waters, Charles R. Bostater

Ocean Engineering and Marine Sciences Faculty Publications

Measurements of natural water samples in the field and laboratory of hyperspectral signatures of total absorption and reflectance were obtained using long pathlength absorption systems (50 cm pathlength). Water was sampled in Indian River Lagoon, Banana River and Port Canaveral, Fl. Stations were also occupied in near coastal waters out to the edge ofthe Gulf Stream in the vicinity of Kennedy Space Center, Fl. and estuarine waters along Port Royal Sound and along the Beaufort River tidal area in South Carolina. The measurements were utilized to calculate natural water specific absorption, total backscatter and specific backscatter optical signatures. The resulting …

Go to article

Broadband Optical Observations Of Bl Lacertae During The 1997 Outburst, Terry D. Oswalt, Daniel Marshall, Tim Robishaw Jun 1998

Broadband Optical Observations Of Bl Lacertae During The 1997 Outburst, Terry D. Oswalt, Daniel Marshall, Tim Robishaw

Aerospace, Physics, and Space Science Faculty Publications

We present BVRI observations of BL Lacertae during its recent outburst. These observations, made during a 3 month period, cover a significant portion of the optical flare. The reduced data are displayed as light curves and broadband spectra. Changes in the spectral index are analyzed, and the results are compared with previous BL Lac observations. We find that the variations are simultaneous in the optical bands, but the higher frequency bands show a higher amplitude of variability. The spectral index is variable during the active period, and there is marginal evidence that the spectrum flattens as the source gets brighter.

Go to article

White Dwarf Cosmochronometry. I. Monte Carlo Simulations Of Proper-Motion And Magnitude-Limited Samples Using Schmidt's 1/Vmax Estimator, Matt A. Wood, Terry D. Oswalt Apr 1998

White Dwarf Cosmochronometry. I. Monte Carlo Simulations Of Proper-Motion And Magnitude-Limited Samples Using Schmidt's 1/Vmax Estimator, Matt A. Wood, Terry D. Oswalt

Aerospace, Physics, and Space Science Faculty Publications

Observationally, white dwarf stars are a remarkably homogeneous class with a minimum observed Teff ∼ 4000 K. Theoretically, the physics that determines their cooling timescales is relatively more straightforward than that which determines main-sequence evolutionary timescales. As a result, the white dwarf luminosity function has for the last decade been used as a probe of the age and star formation rate of the Galactic disk, providing an estimated local disk age of ∼ 10 Gyr with estimated total uncertainties of roughly 20%. A long-standing criticism of the technique is that the reality of the reported downturn in the luminosity function …

Go to article

Asteroseismology Of A Star Cooled By Neutrino Emission: The Pulsating Pre-White Dwarf Pg 0122 + 200, Marlea Sean O'Brien, Matt A. Wood Mar 1998

Asteroseismology Of A Star Cooled By Neutrino Emission: The Pulsating Pre-White Dwarf Pg 0122 + 200, Marlea Sean O'Brien, Matt A. Wood

Aerospace, Physics, and Space Science Faculty Publications

Observation of g-rnode pulsations in the variable pre-white dwarf (GW Virginis) stars provides a unique means to probe their interiors and to study the late stages of stellar evolution. Multisite campaigns have in several cases proved highly successful in decoding pre-white dwarf light curves. Three previous attempts to untangle the pulsation spectrum of the coolest GW Virginis star, PG 0122+200, confirmed the existence of multiple g-modes but left the fundamental period spacing and therefore the star's mass and luminosity in doubt. We present an analysis based on new observations of PG 0122+200 obtained during a Whole Earth Telescope (WET) campaign …

Go to article

Understanding The Cool Da White Dwarf Pulsator, G29-38, Scot J. Kleinman, Matt A. Wood Mar 1998

Understanding The Cool Da White Dwarf Pulsator, G29-38, Scot J. Kleinman, Matt A. Wood

Aerospace, Physics, and Space Science Faculty Publications

The white dwarfs are promising laboratories for the study of cosmochronology and stellar evolution. Through observations of the pulsating white dwarfs, we can measure their internal structures and compositions, critical to understanding post-main-sequence evolution, along with their cooling rates, which will allow us to calibrate their ages directly. The most important set of white dwarf variables to measure are the oldest of the pulsators, the cool DA variables (DAVs), which have not been explored previously through asteroseismology due to their complexity and instability. Through a time-series photometry data set spanning 10 yr, we explore the pulsation spectrum of the cool …

Go to article

Passive Margin Sedimentation On Costa Rica's North Caribbean Coastal Plain, Rio Colorado, Randall W. Parkinson, Jorge Cortés, Percy Denyer Jan 1998

Passive Margin Sedimentation On Costa Rica's North Caribbean Coastal Plain, Rio Colorado, Randall W. Parkinson, Jorge Cortés, Percy Denyer

Ocean Engineering and Marine Sciences Faculty Publications

Geomorphic, sedimentologic, and stratigraphic data obtained from the north Caribbean region of Costa Rica suggests Rio Colorado is a wave-dominated delta which has formed along a passive continental margin. This coastal setting is significantly different from the south Caribbean and Pacific coastlines, which display geomorphic and lithologic features indicative of seismically active continental margins. The distinct aseismic history and passive margin geomorphology of the north Caribbean coastal plain appears to be controlled by the presence of tectonic features (i.e., East Nicoya Fracture Zone) which decouple the region from adjacent, tectonically active areas. Although the data collected during this pilot study, …

Go to article

On Intensities Of Modulated Cox Measures, Jewgeni H. Dshalalow Jan 1998

On Intensities Of Modulated Cox Measures, Jewgeni H. Dshalalow

Mathematics and System Engineering Faculty Publications

In this paper we introduce and study functionals of the intensities of random measures modulated by a stochastic process ξ, which occur in applications to stochastic models and telecommunications. Modulation of a random measure by ξ is specified for marked Cox measures. Particular cases of modulation by ξ as semi-Markov and semiregenerative processes enabled us to obtain explicit formulas for the named intensities. Examples in queueing (systems with state dependent parameters, Little's and Campbell's formulas) demonstrate the use of the results.

Go to article

Variational Lyapunov Method And Stability Theory, V. Lakshmikantham, Xinzhi Liu, S. G. Leela Jan 1998

Variational Lyapunov Method And Stability Theory, V. Lakshmikantham, Xinzhi Liu, S. G. Leela

Mathematics and System Engineering Faculty Publications

By unifying the method of variation of parameters and Lyapunov's second method, we develop a fruitful technique which we call variational Lyapunov method. We then consider the stability theory in this new framework showing the advantage of this unification.

Go to article

Effects Of Submergence On Embryonic Survival And Developmental Rate Of The Florida Applesnail, Pomacea Paludosa: Implications For Egg Predation And Marsh Management, Richard L. Turner Jan 1998

Effects Of Submergence On Embryonic Survival And Developmental Rate Of The Florida Applesnail, Pomacea Paludosa: Implications For Egg Predation And Marsh Management, Richard L. Turner

Ocean Engineering and Marine Sciences Faculty Publications

Aerial deposition of egg clutches by the aquatic Florida applesnail is believed to have evolved in response to aquatic egg predators. Adaptation to aerial conditions might, however, have rendered embryos intolerant of submergence, a potential occurrence in natural and managed marshes, rivers, and lakes. In this study, eggs were submerged in water for various durations in the laboratory to assess their ability to survive flooding; and clutches of known ages were submerged for several days in the field to determine if aquatic predators might decrease survival below levels expected to occur due to flooding alone. Submergence of clutches slowed embryonic …

Go to article

Mach-Zehnder Interferometer Fringe Projector For Variable Resolution Video Moire, Phillip C. Kalmanson, August Schutte, Chris L. Hart, Joel H. Blatt Jan 1998

Mach-Zehnder Interferometer Fringe Projector For Variable Resolution Video Moire, Phillip C. Kalmanson, August Schutte, Chris L. Hart, Joel H. Blatt

Aerospace, Physics, and Space Science Faculty Publications

A Mach-Zehnder based variable resolution fringe projection system has been built for 3-D video moini machine vision. This system uses the three main advantages of the Mach-Zehnder - 1) There is no optical feedback to the laser source, 2) The interfemmeter can accept two different laser wavelengths simultaneously, and 3) The interferometer produces two orthngonal output beams. The lack of optical feedback makes the Mach-Zehnder especially attractive for use with high power laser diode sources which are sensitive to optical feedback. When the two input ports axe used with two different wavelength lasers, the target can be illuminated by simultaneous …

Go to article

Steps Toward Determination Of The Size And Structure Of The Broad-Line Region In Active Galactic Nuclei. Xii. Ground-Based Monitoring Of 3c 390.3, Matthias Dietrich, T. D. Oswalt, Jun Tao Jan 1998

Steps Toward Determination Of The Size And Structure Of The Broad-Line Region In Active Galactic Nuclei. Xii. Ground-Based Monitoring Of 3c 390.3, Matthias Dietrich, T. D. Oswalt, Jun Tao

Aerospace, Physics, and Space Science Faculty Publications

Results of a ground-based optical monitoring campaign on 3C 390.3 in 1994-1995 are presented. The broadband fluxes (B, V, R, and I), the spectrophotometric optical continuum flux Fλ(5177 Å), and the integrated emission-line fluxes of Hα, Hβ, Hγ, He II λ15876, and He II A4686 all show a nearly monotonic increase with episodes of milder short-term variations superposed. The amplitude of the continuum variations increases with decreasing wavelength (4400-9000 Å). The optical continuum variations follow the variations in the ultraviolet and X-ray with time delays, measured from the centroids of the cross-correlation functions, typically around 5 days, but with uncertainties …

Go to article

Multicolor Fringe Projection System With Enhanced 3-D Reconstruction Of Surfaces, Bernard S. Gilbert, Joel H. Blatt Jan 1998

Multicolor Fringe Projection System With Enhanced 3-D Reconstruction Of Surfaces, Bernard S. Gilbert, Joel H. Blatt

Aerospace, Physics, and Space Science Faculty Publications

Most optical topology systems use a single wavelength laser for projection, using a swept spot, a moving line, or a projected grating. In a typical projected grating system, the gratings are shifted and a series of images are used to recover the 3-D shape of the target. When the series of images is analyzed in the normal phase shift manner, the resulting 2-D phase map typically has phase unwrapping problems due to noise and Nyquist limits. Surfaces with large vertical discontinuities present the biggest problem in 3-D shape recovery. This paper looks at simultaneously projecting multiple wavelengths onto a surface …

Go to article