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Physical Sciences and Mathematics Commons™

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2001

Series

Florida Institute of Technology

Articles 1 - 15 of 15

Full-Text Articles in Physical Sciences and Mathematics

Isotopic Composition Of Solar Energetic Particle Events Measured By Advanced Composition Explorer/Uleis, Joseph R. Dwyer, Glenn M. Mason, Joseph E. Mazur, Robert E. Gold, Stamatios M. Krimigis, Eberhard S. Möbius, Mark A. Popecki Dec 2001

Isotopic Composition Of Solar Energetic Particle Events Measured By Advanced Composition Explorer/Uleis, Joseph R. Dwyer, Glenn M. Mason, Joseph E. Mazur, Robert E. Gold, Stamatios M. Krimigis, Eberhard S. Möbius, Mark A. Popecki

Aerospace, Physics, and Space Science Faculty Publications

Since its 1997 August launch, the Ultra Low Energy Isotope Spectrometer (ULEIS) on board the Advanced Composition Explorer (ACE) has observed a large number of solar energetic particle (SEP) events in the 0.4-3 MeV nucleonˉ¹ range. These events show remarkable variability of both the elemental and isotopic compositions, with ²²Ne/²⁰Ne varying, from event to event, by up to a factor of 10, Fe/O by up to a factor of 100, and ³He/⁴He by up to a factor of 104. In this paper we present new measurements of the ²²Ne/²⁰Ne, ²⁶Mg/²⁴Mg, and ³He/⁴He ratios at ∼ 1 MeV nucleonˉ¹ and compare …

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The Vacuum Buffer, Voicu Popescu Nov 2001

The Vacuum Buffer, Voicu Popescu

Link Foundation Modeling, Simulation and Training Fellowship Reports

Image-based rendering (IBR) techniques have the potential of alleviating some of the bottlenecks of traditional geometry-based rendering such as modeling difficulty and prohibitive cost of photorealism. One of the most appealing IBR approaches uses images enhanced with per-pixel depth and creates new views by 3D warping (IBRW). Modeling a scene with depth images lets one automatically capture intricate details, which are hard to model conventionally. Also, rendering from such representations has the potential of being efficient since it seems that the number of samples that need to be warped is independent of the scene complexity and is just a fraction …

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Seawater Temperature Trends At Usa Tide Gauge Sites, George A. Maul, Andria M. Davis, Jeffrey W. Simmons Oct 2001

Seawater Temperature Trends At Usa Tide Gauge Sites, George A. Maul, Andria M. Davis, Jeffrey W. Simmons

Ocean Engineering and Marine Sciences Faculty Publications

Seawater temperatures have been measured at United States tide gauges throughout most of the 20th century. All available records have been digitized, and the longest 14 have been analyzed by linear least-square regression. The largest positive trend is from Boston MA (+3.6 ± 0.4°C per century), and the largest negative trend is at Charleston SC (-0.1 ± 0.3°C per century). No consistent latitudinal or eastcoast vs. west-coast patterns are discernable, but air temperature trends are typically greater than seawater changes.

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Acceleration Of ³He Nuclei At Interplanetary Shocks, Mihir I. Desai, Glenn M. Mason, Joseph R. Dwyer, Joseph E. Mazur, Charles W. Smith, Ruth M. Skoug May 2001

Acceleration Of ³He Nuclei At Interplanetary Shocks, Mihir I. Desai, Glenn M. Mason, Joseph R. Dwyer, Joseph E. Mazur, Charles W. Smith, Ruth M. Skoug

Aerospace, Physics, and Space Science Faculty Publications

We have surveyed the 0.5-2.0 MeV nucleonˉ¹ ion composition of 56 interplanetary (IP) shocks observed with the Ultra - Low-Energy Isotope Spectrometer on board the Advanced Composition Explorer from 1997 October 1 through 2000 November 30. Our results show the first ever measurement (25 cases) of ³He ions being accelerated at IP shocks. The ³He/⁴He ratio at the 25 shocks exhibited a wide range of values between 0.0014 and 0.24; the ratios were enhanced between factors of ∼3 and 600 over the solar wind value. During the survey period, the occurrence probability of ³He-rich shocks increased with rising solar activity …

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Relationship Between Durophagy And Feeding Biomechanics In Gray Triggerfish, Balistes Capriscus: Intraspecific Variation In Ecological Morphology, Christopher J. Durie, Ralph G. Turingan Jan 2001

Relationship Between Durophagy And Feeding Biomechanics In Gray Triggerfish, Balistes Capriscus: Intraspecific Variation In Ecological Morphology, Christopher J. Durie, Ralph G. Turingan

Ocean Engineering and Marine Sciences Faculty Publications

The relationship between oral jaw biomechanics and consumption of hard prey was compared between Gulf of Mexico (Gulf) and Atlantic Ocean (Atlantic) populations of gray triggerfish (Balistes capriscus) to examine intraspecific ecomorphological variation between these fish. Gut content analysis revealed that Atlantic fish fed more on hard-shelled invertebrates, such as crabs and sea urchins, than Gulf conspecifics. Difference in the relative magnitude of durophagy between Gulf and Atlantic triggerfish was associated with intraspecific differences in key biomechanical properties of the prey-capture and processing mechanism. The more durophagous Atlantic B. capriscus had more massive jaw bones and muscles than Gulf fish. …

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Existence Criteria For Singular Initial Value Problems With Sign Changing Nonlinearities, Ravi P. Agarwal, Donal O'Regan, V. Lakshmikantham Jan 2001

Existence Criteria For Singular Initial Value Problems With Sign Changing Nonlinearities, Ravi P. Agarwal, Donal O'Regan, V. Lakshmikantham

Mathematics and System Engineering Faculty Publications

A general existence theory is presented for initial value problems where our nonlinearity may be singular in its dependent variable and may also change sign.

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Computer Graphics Optique: Optical Superposition Of Projected Computer Graphics, Aditi Majumder Jan 2001

Computer Graphics Optique: Optical Superposition Of Projected Computer Graphics, Aditi Majumder

Link Foundation Modeling, Simulation and Training Fellowship Reports

We present some ideas and demonstrations for a hybrid projector-based rendering and display technique we call Computer Graphics Optique. Instead of partially overlapping projected images to achieve a wide-area display, we completely overlap projected images on top of each other to achieve the addition of light and color in an "optical composition buffer''. The idea is to use the optical composition to replace some analytical computation, to increase rendering speed, gain flexibility, intensity range, and intensity resolution. Where projector-based displays are appropriate, potential uses include the optical realization of certain effects normally requiring a digital accumulation buffer, the optical composition …

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Enhancing Training And Presence In Virtual Environments Using Passive Haptics, Brent E. Insko Jan 2001

Enhancing Training And Presence In Virtual Environments Using Passive Haptics, Brent E. Insko

Link Foundation Modeling, Simulation and Training Fellowship Reports

One of the worst virtual environment experiences is to virtually contact something and feel nothing. Visual-haptic sensory conflicts are normally dominated by visual perception. Therefore, augmenting a high-fidelity visual virtual environment with low-fidelity haptic objects, called passive haptics, should markedly improve both sense of presence and task training effectiveness. Testing these hypotheses, I found adding a 1.5 inch physical ledge to a visual-cliff virtual environment increased participants' sense of presence as measured by subjective questionnaires, observed participant behaviors, and physiological responses. I next examined memory model creation and training effectiveness for a navigation task in a virtual environment with and …

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Multiband Microvariability Observations Of Bl Lacertae During The Outburst Of 1997, Sandra D. Clements, Michael T. Carini Jan 2001

Multiband Microvariability Observations Of Bl Lacertae During The Outburst Of 1997, Sandra D. Clements, Michael T. Carini

Aerospace, Physics, and Space Science Faculty Publications

BL Lac was observed in the V and R bands on 11 nights in 1997 July during a major optical outburst. It varied continuously, exhibiting nightly variations ranging from 0.1 to 0.6 mag. Over the course of the 11 nights, BL Lac was seen to vary by 1.8 R magnitudes. Color variations were also observed, with BL Lac becoming bluer as it brightened. The influence of variable seeing conditions on the observed variations was investigated. No correlation was found between the observed microvariability and the local seeing conditions.

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On The Origin Of Reverse Polarity Tcrs, Mark B. Moldwin, Michael R. Collier, James A. Slavin, Adam Szabo Jan 2001

On The Origin Of Reverse Polarity Tcrs, Mark B. Moldwin, Michael R. Collier, James A. Slavin, Adam Szabo

Aerospace, Physics, and Space Science Faculty Publications

Reverse polarity, or South-then-North (SN) bipolar, traveling compression regions (SN TCRs) are often observed in the Earth's magnetotail lobes. These events have been interpreted as either slowly earthward propagating "proto-plasmoids" during extremely quiet geomagnetic conditions, or due to pressure pulses in the solar wind or magnetosheath compressing the magnetotail. This study presents a survey of 21 IMP 8 observations of SN TCRs and the corresponding solar wind pressure conditions as measured by WIND. We found that solar wind or magnetosheath pressure pulses nicely explain most (17), though not all, of the SN TCR observations. Therefore, it appears that both explanations …

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Tracking Of Moving Objects In Scenery Using Subspace Projection Using Independent Component Analysis, Brian J. Noe, Fredric M. Ham Jan 2001

Tracking Of Moving Objects In Scenery Using Subspace Projection Using Independent Component Analysis, Brian J. Noe, Fredric M. Ham

Aerospace, Physics, and Space Science Faculty Publications

A system is developed for tracking moving objects though natural scenery. A technique is presented for performing change detection on imagery to determine the difference between two images or a sequence of images. Form there an algorithm is presented to detect the presence of a new object and/or the deletion of objects. Then the application of a Variable Structure Interacting Multiple Model tracking filter is presented. The method of performing change detection is based upon the concept of image subspace projection. A set of basis image maps are formed when combined with a mixing matrix can recreate the original image. …

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Computer Graphics Optique: Optical Superposition Of Projected Computer Graphics, Aditi Majumder Jan 2001

Computer Graphics Optique: Optical Superposition Of Projected Computer Graphics, Aditi Majumder

Link Foundation Modeling, Simulation and Training Fellowship Reports

We present some ideas and demonstrations for a hybrid projector-based rendering and display technique we call Computer Graphics Optique. Instead of partially overlapping projected images to achieve a wide-area display, we completely overlap projected images on top of each other to achieve the addition of light and color in an "optical composition buffer''. The idea is to use the optical composition to replace some analytical computation, to increase rendering speed, gain flexibility, intensity range, and intensity resolution. Where projector-based displays are appropriate, potential uses include the optical realization of certain effects normally requiring a digital accumulation buffer, the optical composition …

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Automated Alignment By Hybrid Video And 3-D Video Moiré With Both Conventional And Parallel Processing, Barbara Garita, Hector Gutierrez, Ildiko Laszlo, Joel H. Blatt Jan 2001

Automated Alignment By Hybrid Video And 3-D Video Moiré With Both Conventional And Parallel Processing, Barbara Garita, Hector Gutierrez, Ildiko Laszlo, Joel H. Blatt

Aerospace, Physics, and Space Science Faculty Publications

A problem common to automated assembly in manufacturing or in automated docking of spacecraft is angular and lateral alignment of components. A hybrid video system utilizing both conventional imaging and 3-D video moiré has been developed to automatically align a test target with three translational and two rotational degrees of freedom. Alignment was demonstrated via computer controlled translation and rotation stages. The video moiré system is operated in an error map mode, in which a structurally illuminated reference surface is used to chromakey the image of an identical structurally illuminated alignment target. The output is a moiré image generated by …

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White Dwarfs In Common Proper Motion Binary Systems: Mass Distribution And Kinematics, Nicole M. Silvestri, Terry D. Oswalt, Matt A. Wood, Jonathan Allyn Smith, Iain Neill Reid, Edward M. Sión Jan 2001

White Dwarfs In Common Proper Motion Binary Systems: Mass Distribution And Kinematics, Nicole M. Silvestri, Terry D. Oswalt, Matt A. Wood, Jonathan Allyn Smith, Iain Neill Reid, Edward M. Sión

Aerospace, Physics, and Space Science Faculty Publications

We present the mass distribution, gravitational redshifts, radial velocities, and space motions of white dwarf stars in common proper motion binary systems. The mass distribution we derive for the 41 DA white dwarfs in this study has a mean of 0.68 ± 0.04 M⊙. This distribution has a slightly higher mean and larger dispersion than most previous white dwarf studies. We hypothesize that this is due to a higher fraction of cool (average Teff ~ 10,000 K), hence old, white dwarfs in our sample. Our results indicate that samples made up of predominantly cool, old white dwarf stars tend to …

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Evidence Of Different Magnetotail Responses To Small Solar Wind Pressure Pulses Depending On Imf Bz Polarity, Mark B. Moldwin, S. S. Mayerberger, Hamid K. Rassoul, Michael R. Collier, Ronald P. Lepping, James A. Slavin, Adam Szabo Jan 2001

Evidence Of Different Magnetotail Responses To Small Solar Wind Pressure Pulses Depending On Imf Bz Polarity, Mark B. Moldwin, S. S. Mayerberger, Hamid K. Rassoul, Michael R. Collier, Ronald P. Lepping, James A. Slavin, Adam Szabo

Aerospace, Physics, and Space Science Faculty Publications

The response of the magnetotail to small flux rope associated pressure pulses depends on the IMF Bz polarity. Clear and large amplitude magnetotail reverse polarity South-then-North traveling compression regions (SN TCRs) are observed when the pressure pulse is associated with the northward IMF interval of the flux rope. These tail signatures correspond to small-scale (<10 minute duration) pulses of the solar wind dynamic pressure located in front of and within the small-scale flux ropes. Pressure pulses associated with IMF Bz southward are either absent or give rise to smaller amplitude compressions and less systematic lobe Bz rotations. These results suggest that the orientation of the IMF Bz plays a critical role in modulating the magnetotail response to solar wind dynamic pressure pulses.

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