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Asteroid Surfaces: The Importance of Cohesive Forces
Title
Asteroid Surfaces: The Importance of Cohesive Forces.
Creator
Jardine, Keanna, Dove, Adrienne, Tetard, Laurene, Britt, Daniel, University of Central Florida
Abstract / Description
Adhesive forces play a significant role on airless bodies due to their weak gravities. Investigating adhesion at the surface of asteroids and their constituent components is vital to understanding their formation and evolution. Previous research has been done to understand the interaction of micron-sized spheres to planar surfaces and sphere-to-sphere interactions, which have been used to develop models of asteroid surfaces. Our investigation experimentally investigates adhesion through...
Show moreAdhesive forces play a significant role on airless bodies due to their weak gravities. Investigating adhesion at the surface of asteroids and their constituent components is vital to understanding their formation and evolution. Previous research has been done to understand the interaction of micron-sized spheres to planar surfaces and sphere-to-sphere interactions, which have been used to develop models of asteroid surfaces. Our investigation experimentally investigates adhesion through atomic force microscopy (AFM) measurements between JSC-1 simulant particles and several AFM tips, including a typical pyramidal gold tip and microspheres of sizes 2 (&)#181;m and 15 (&)#181;m. The samples of JSC-1 consist of three size ranges: (<) 45 (&)#181;m, 75-125 (&)#181;m, and 125-250 (&)#181;m. For each sample we looked at the magnitude and distribution of the measured adhesive forces. Results show that the pyramidal tip produced larger forces than the spherical tips generally, and the sample that produced larger forces and a larger distribution of those force was the smaller, more powder-like sample with sizes (<)45 (&)#181;m.
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Date Issued
2018
Identifier
CFE0007755, ucf:52377
Format
Document (PDF)
PURL
http://purl.flvc.org/ucf/fd/CFE0007755
The Relativistic Harmonic Oscillator and the Generalization of Lewis' Invariant
Title
The Relativistic Harmonic Oscillator and the Generalization of Lewis' Invariant.
Creator
Reinhart, Daniel, Shivamoggi, Bhimsen, Kokoouline, Viatcheslav, Dove, Adrienne, University of Central Florida
Abstract / Description
In this thesis, we determine an asymptotic solution for the one dimensional relativistic harmonicoscillator using multiple scale analysis and relate the resulting invariant to Lewis' invariant. Wethen generalize the equations leading to Lewis' invariant so they are relativistically correct. Nextwe attempt to find an asymptotic solution for the general equations by making simplifying assumptionson the parameter characterizing the adiabatic nature of the system. The first term inthe series for...
Show moreIn this thesis, we determine an asymptotic solution for the one dimensional relativistic harmonicoscillator using multiple scale analysis and relate the resulting invariant to Lewis' invariant. Wethen generalize the equations leading to Lewis' invariant so they are relativistically correct. Nextwe attempt to find an asymptotic solution for the general equations by making simplifying assumptionson the parameter characterizing the adiabatic nature of the system. The first term inthe series for Lewis' invariant corresponds to the adiabatic invariant for systems whose frequencyvaries slowly. For the relativistic case we find a new conserved quantity and seek to explore itsinterpretation.iii
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Date Issued
2019
Identifier
CFE0007712, ucf:52434
Format
Document (PDF)
PURL
http://purl.flvc.org/ucf/fd/CFE0007712
Vanadium Oxide Microbolometers with Patterned Gold Black or Plasmonic Resonant Absorbers
Title
Vanadium Oxide Microbolometers with Patterned Gold Black or Plasmonic Resonant Absorbers.
Creator
Smith, Evan, Peale, Robert, Khondaker, Saiful, Dove, Adrienne, Boreman, Glenn, University of Central Florida
Abstract / Description
High sensitivity uncooled microbolometers are necessary to meet the needs of the next generation of infrared detectors, which seek low power consumption and production cost without sacrificing performance. Presented here is the design, fabrication, and characterization of a microbolometer with responsivity enhanced by novel highly absorptive coatings. The device utilizes a gold-doped vanadium oxide film in a standard air bridge design. Performance estimations are calculated from current...
Show moreHigh sensitivity uncooled microbolometers are necessary to meet the needs of the next generation of infrared detectors, which seek low power consumption and production cost without sacrificing performance. Presented here is the design, fabrication, and characterization of a microbolometer with responsivity enhanced by novel highly absorptive coatings. The device utilizes a gold-doped vanadium oxide film in a standard air bridge design. Performance estimations are calculated from current theory, and efforts to maximize signal to noise ratio are shown and evaluated. Most notably, presented are the experimental results and analysis from the integration of two different absorptive coatings: a patterned gold black film and a plasmonic resonant structure.Infrared-absorbing gold black was selectively patterned onto the active surfaces of the detector. Patterning by metal lift-off relies on protection of the fragile gold black with an evaporated oxide, which preserves gold black's near unity absorptance. This patterned gold black also survives the dry-etch removal of the sacrificial polyimide used to fabricate the air-bridge bolometers. Infrared responsivity is improved 70% for mid-wave IR and 22% for long-wave IR. The increase in the thermal time constant caused by the additional mass of gold black is a modest 15%. However, this film is sensitive to thermal processing; experimental results indicate a decrease in absorptance upon device heating.Sub-wavelength resonant structures designed for long-wave infrared (LWIR) absorption have also been investigated. Dispersion of the dielectric refractive index provides for multiple overlapping resonances that span the 8-12 ?m LWIR wavelength band, a broader range than can be achieved using the usual resonance quarter-wave cavity engineered into the air-bridge structures. Experimental measurements show an increase in responsivity of 96% for mid-wave IR and 48% for long-wave IR, while thermal response time only increases by 16% due to the increased heat capacity. The resonant structures are not as susceptible to thermal processing as are the gold black films. This work suggests that plasmonic resonant structures can be an ideal method to improve detector performance for microbolometers.
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Date Issued
2015
Identifier
CFE0006004, ucf:51026
Format
Document (PDF)
PURL
http://purl.flvc.org/ucf/fd/CFE0006004