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Articles 1  30 of 1710
FullText Articles in Physics
EmbeddedAtomMethod Modeling Of AlkaliMetal/TransitionMetal Interfaces, Jake D. Christensen
EmbeddedAtomMethod Modeling Of AlkaliMetal/TransitionMetal Interfaces, Jake D. Christensen
All Graduate Theses and Dissertations
Understanding the thermal properties of materials is essential to using those materials for technological advancement which can benefit civilization. For example, it has been proposed that essential components of tokamaks, devices which perform fusion, be made out of tungsten with a thin layer of lithium on the surface. To that end, this thesis seeks to calculate the thermal properties of a layer of alkali atoms, like lithium and sodium, on tungsten and molybdenum substrates. We use an Embedded Atom Method (EAM) model to perform our calculations. This type of model has been widely used to describe the interaction between atoms ...
The Development And Use Of A Secondary Electron Yield Database For Spacecraft Charge Modeling, Phillip Lundgreen
The Development And Use Of A Secondary Electron Yield Database For Spacecraft Charge Modeling, Phillip Lundgreen
All Graduate Theses and Dissertations
Charge modeling of electronsolid interactions requires a detailed and accurate compilation of experimental data on which to base its physics and against which to test its predictions. Historically researchers used methods involving individual research or information taken from existing, vague, databases that were often found wanting. To streamline the charge modeling process, a collection of data has been assembled and categorized based upon surface morphology and contamination from various published sources and existing databases. The quality and quantity of the compilation vary widely with very little information offered with regards to surface conditions of various materials (contamination, morphology, etc. ...). Included ...
New Techniques For Holography From Supergravity, Oscar Varela
New Techniques For Holography From Supergravity, Oscar Varela
Funded Research Records
No abstract provided.
Hodographic Analysis Of Na Lidar Data To Measure Atmospheric Gravity Wave Parameters, Jeffrey Ormsby
Hodographic Analysis Of Na Lidar Data To Measure Atmospheric Gravity Wave Parameters, Jeffrey Ormsby
Physics Capstone Projects
The Utah State University Sodium lidar observatory, hosted in Science and Engineering Research building at Logan campus, measures the winds and temperature near the boundary of eddy diffusion dominated upper atmosphere between 80 and 110km, where various atmospheric internal waves, especially atmospheric gravity waves (buoyancy waves), play important roles in the dynamics and chemistry. In this study, using a hodographic algorithm, the lidar data were analyzed to extract critical parameters of these gravity waves detected in this region, such as horizontal propagating phase velocity and wavelength. Results were compared with the independent Advanced Atmospheric Temperature Mapper (AMTM) observations, colocated at ...
StormTime Equatorial Thermospheric Dynamics And Electrodynamics, Luis A. Navarro Dominguez
StormTime Equatorial Thermospheric Dynamics And Electrodynamics, Luis A. Navarro Dominguez
All Graduate Theses and Dissertations
We present the first complete study of the dynamics of the equatorial upper atmosphere (180350 km) during periods of strong magnetic activity driven by the Sun, which are generally referred as geomagnetic storms. These storms have the potential to considerably affect satellitebased communications and navigation systems among other severe technological challenges. We used large databases of two of the most important parameters at these altitudes, which are the velocities of the neutral and ionized gas (plasma) referred to as neutral winds and plasma drifts. These measurements were acquired in the Peruvian equatorial region by the Jicamarca radar and by a ...
Massive Graviton Spectra In Supergravity, Kevin Dimmitt
Massive Graviton Spectra In Supergravity, Kevin Dimmitt
All Graduate Theses and Dissertations
Development of a unified theory of physics would pave the way for new research and technology development for many years to come. Unfortunately, the two best current theories explaining nature, the Standard Model of particle physics and general relativity, do not seem to be compatible, requiring the development of more complicated models which contains both of these at their respective limits. Supergravities are one set of theories which may, at least in part, provide hints as to how it may be possible to unify physics into a single model.
This research project follows from a line of investigation which the ...
Design, Monitoring And Management Approaches For The RootZone In Microgravity, Scott B. Jones
Design, Monitoring And Management Approaches For The RootZone In Microgravity, Scott B. Jones
Funded Research Records
No abstract provided.
Spacetime Groups, Ian M. Anderson, Charles G. Torre
Spacetime Groups, Ian M. Anderson, Charles G. Torre
All Physics Faculty Publications
A spacetime group is a connected 4dimensional Lie group G endowed with a left invariant Lorentz metric h and such that the connected component of the isometry group of h is G itself. The NewmanPenrose formalism is used to give an algebraic classification of spacetime groups, that is, we determine a complete list of inequivalent spacetime Lie algebras, which are pairs, (g, n), with g being a 4dimensional Lie algebra and n being a Lorentzian inner product on g. A full analysis of the equivalence problem for spacetime Lie algebras is given which leads to a completely algorithmic solution to ...
Fabrication Of Suspended Microbolometers On Soi Wafers, Isaac Maxfield
Fabrication Of Suspended Microbolometers On Soi Wafers, Isaac Maxfield
Physics Capstone Projects
A bolometer is a device to measure radiation energy by converting photon energy into heat on an isolated absorber. We plan to use carbonnanotube (CNT) based absorber to enhance the photon absorption. The absorber is a few microns in size and is suspended with micronsized bridges which also support metal lines for electrical measurements.
Synthesis Of Graphene By Liquid Precursors At Lower Temperatures, Clayton Hansen
Synthesis Of Graphene By Liquid Precursors At Lower Temperatures, Clayton Hansen
Physics Capstone Projects
Benzene, toluene, and xylene can be liquid precursors for graphene and carbon nanotube synthesis. However, the growth mechanisms can have greater variances for different carbon allotropes. In the case of graphene, Cu can be the catalyst for dehydrogenation and provides a weaklycoupled substrate for 2dimensional graphene nucleation and growth. In the case of carbon nanotubes, Fe nanoparticles are essential to catalyze the CC bonds breaking and dissolve carbon before the precipitation of a graphene cap over the catalyst particle where a tube forms. Controlling the precursor feed rate is crucial for a successful synthesis. In this research, we developed a ...
Waves Over Mcmurdo Station, Robert Johnson
Waves Over Mcmurdo Station, Robert Johnson
Physics Capstone Projects
Atmospheric gravity waves (GWs) are generated by gravity acting on weather systems effectively causing them to oscillate. These waves can then propagate upwards into the upper atmosphere, where they are observed as they pass through glowing layers of gas, called airglow, in the upper atmosphere at approximately 87 kilometers altitude. Using Physics and a little bit of chemistry we can observe the properties of these waves with special infrared cameras. Combining the data between images taken at the same time but with different filters, we can determine the temperature amplitudes of the waves, important for improving our understanding of their ...
Material Outgassing Kinetics: The Development Of A Testing Capability, Alex Kirkman
Material Outgassing Kinetics: The Development Of A Testing Capability, Alex Kirkman
Physics Capstone Projects
Contamination due to outgassing of materials can cause the degradation of critical hardware of a spacecraft. Using outgassing rates, kinetic expressions can be developed and used in models to predict the evolution of molecules and migration of contaminants for specific materials. These models could be used in the selection process of materials to help mitigate the amount of contamination of mission critical hardware for the expected life of the spacecraft. By using the ASTM E1559 test standard this can be achieved. This standard uses the quartz crystal microbalance (QCM) collection approach. A temperaturecontrolled effusion cell, containing the sample material, impinges ...
Determining The Phase Of The Diurnal, Solar Thermal Tidal Wave In The Upper Atmosphere Using Nighttime Na Lidar Measurements, Trevor Harshman
Determining The Phase Of The Diurnal, Solar Thermal Tidal Wave In The Upper Atmosphere Using Nighttime Na Lidar Measurements, Trevor Harshman
Physics Capstone Projects
Solar thermal tidal waves play a critical role in the dynamics of the mesosphere and thermosphere. Obtaining measurements of the diurnal tidal wave above 100 km is difficult. This could be solved using a physicsbased empirical model. To derive this model requires knowing the phase at different points along the tidal wave. In this study, I determine the phase at multiple points along the thermal diurnal tidal wave using measurements taken by a fluorescence lidar in the range of 80 to 100 km. A simple calculation of the phase based on the zeroes and extrema of the wave is demonstrated.
ModelBased Properties Of Earth's Protective Shield: Relating UtBased Dependencies Of The Open/Closed Boundary, Cutoff Latitude, And LShell Parameter With Polar Cap Absorption Events, David A. Smith
All Graduate Theses and Dissertations
High frequency radio continues to be an important communications medium. For example, commercial airlines use high frequency radios as their primary communications mode during transpolar crossings. It has been estimated that over 7000 transpolar flights occur each year. Unfortunately, during geomagnetic storms high frequency communications can become unreliable, especially near Earth's Polar Regions.
Space weather forecasters are burdened with the responsibility of predicting how radio signals might be affected during geomagnetic storms and passing that important information on to commercial airlines, allowing them to adjust flight plans accordingly. Such adjustments can be costly, but are necessary to ensure safety ...
Clustering And Classifying Geophysical Rock Properties Of The San Andreas Fault, Jared Bryan
Clustering And Classifying Geophysical Rock Properties Of The San Andreas Fault, Jared Bryan
Physics Capstone Projects
Borehole geophysical data provide important in situ observations for identifying and characterizing geologic and structural features in the subsurface. We perform an unsupervised classification of geophysical logs from the Sand Andreas Fault Observatory at Depth (SAFOD) borehole in order to define intervals of distinct geophysical properties. We focus on borehole geophysical data collected during Phase 3 drilling operations from 3.03.3 km measured depth, which encompasses the active trace of the San Andreas Fault. We use dimensionality reduction to increase the interpretability of the retrieved clusters, and we compare the performance of distance and densitybased clustering techniques. Kmeans clustering ...
Optical Relaxation Of Defects In Kapton Caused By Irradiation, Ashlan Keeler Swainston
Optical Relaxation Of Defects In Kapton Caused By Irradiation, Ashlan Keeler Swainston
Physics Capstone Projects
Radiation can create atomicscale defect states in polymers, leading to changes in their optical, electrical and mechanical properties. Recent studies of polymers have shown that these defect states are sensitive to oxygen or air exposure. It is believed that air cause the number of defect states to decrease and the polymers to revert to their original states. However, the time scale of this regression is not known. This experiment quantified the time that it takes one polymer to recover and the extent of said recovery; polymide (PI). In order to study the regression, optical transmission data were taken using a ...
Understanding Noether’S Theorem By Visualizing The Lagrangian, Seth Moser
Understanding Noether’S Theorem By Visualizing The Lagrangian, Seth Moser
Physics Capstone Projects
By approaching Lagrangian mechanics from a graphical perspective the implications of Noether’s Theorem can be made easier to understand. Plotting the Lagrangian for classical single particle systems for one coordinate onto a positionvelocity phase space along with the corresponding equations of motion can demonstrate how a system is invariant under continuous transforms in that coordinate. This invariance can be shown to be associated with a quantity in the system that’s conserved via Noether’s Theorem. The relationship between the symmetry of the system and conserved quantities can then be extended to fields. Invariance in this case is extended ...
Determing The Chaotic Nature Of Periodic Orbits, Bo Johnson
Determing The Chaotic Nature Of Periodic Orbits, Bo Johnson
Physics Capstone Projects
The determination of the longterm behavior of periodic orbits is considered. Different numerical techniques, including the Lyapunov Exponent, the Smaller Alignment Index, and the Generalized Alignment Index are used. Because of the discontinuous nature of the system under consideration, these methods are found to be insufficient and a more simplistic approach is utilized. The simplistic approach determines longterm behavior up to 500 periods of an orbit. It is found that inphase periodic modes result in the largest amount of stable modes. Future work will look at the common characteristics of the inphase modes to better understand why they are more ...
Giving Students A Better Understanding Of The Concepts Behind The Coriolis Force, Ridge Cole
Giving Students A Better Understanding Of The Concepts Behind The Coriolis Force, Ridge Cole
Physics Capstone Projects
The Coriolis force is a physical phenomenon that has proven difficult for students to understand for centuries. While the mathematical approach to teaching this phenomenon is well known and outlined, the concepts behind this force have proven to be very elusive to students. Through the use of modern technology and new ways of presenting these concepts, we hope to give students a clear understanding of the Coriolis force in the future.
Stormtime Longitudinal Variability In The IonosphereThermosphere System, Ludger Scherliess
Stormtime Longitudinal Variability In The IonosphereThermosphere System, Ludger Scherliess
Funded Research Records
No abstract provided.
Strategies For Determining Electron Yield Material Parameters For Spacecraft Charge Modeling, Phil Lundgreen, J. R. Dennison
Strategies For Determining Electron Yield Material Parameters For Spacecraft Charge Modeling, Phil Lundgreen, J. R. Dennison
All Physics Faculty Publications
Accurate modeling of spacecraft charging is essential to mitigate well‐known and all‐too‐common deleterious and costly effects on spacecraft resulting from charging induced by interactions with the space plasma environment. This paper addresses how limited availability of electron emission and transport properties of spacecraft materials—in particular, secondary electron yields—and the wide ranges measured for such properties pose a critical issue for modeling spacecraft charging. It describes a materials charging database for electron emission properties under development, which facilitates more accurate spacecraft charge modeling when used in concert with the strategies outlined herein. These data and techniques ...
The Development And Validation Of A 'FluxCorrected Transport' Based Solution Methodology For The Plasmasphere Refilling Problem Following Geomagnetic Storms, Kausik Chatterjee, Robert W. Schunk
The Development And Validation Of A 'FluxCorrected Transport' Based Solution Methodology For The Plasmasphere Refilling Problem Following Geomagnetic Storms, Kausik Chatterjee, Robert W. Schunk
All Physics Faculty Publications
The refilling of the plasmasphere following geomagnetic storms remains one of the longstanding and interesting problems in ionospheremagnetosphere coupling research. The objective of this paper is the formulation and development of a onedimensional (1D) refilling model using the fluxcorrected transport method, a numerical method that is extremely wellsuited to handling problems with shocks and discontinuities. In this paper, the developed methodology has been validated against exact, analytical benchmarks, and extremely good agreement has been obtained between these analytical benchmarks and numerical results. The ultimate objective of this research is the development of a threedimensional (3D) multiion model for ionospheremagnetosphere coupling ...
Periodic Bouncing Modes For Two Uniformly Magnetized Spheres. I. Trajectories, Boyd F. Edwards, Bo A. Johnson, John M. Edwards
Periodic Bouncing Modes For Two Uniformly Magnetized Spheres. I. Trajectories, Boyd F. Edwards, Bo A. Johnson, John M. Edwards
All Physics Faculty Publications
We consider a uniformly magnetized sphere that moves without friction in a plane in response to the field of a second, identical, fixed sphere, making elastic hardsphere collisions with this sphere. We seek periodic solutions to the associated nonlinear equations of motion. We find closedform mathematical solutions for smallamplitude modes and use these to characterize and validate our largeamplitude modes, which we find numerically. Our RungeKutta integration approach allows us to find 1243 distinct periodic modes with the free sphere located initially at its stable equilibrium position. Each of these modes bifurcates from the finiteamplitude radial bouncing mode with infinitesimalamplitude ...
Periodic Bouncing Modes For Two Uniformly Magnetized Spheres. Ii. Scaling, Boyd F. Edwards, Bo A. Johnson, John M. Edwards
Periodic Bouncing Modes For Two Uniformly Magnetized Spheres. Ii. Scaling, Boyd F. Edwards, Bo A. Johnson, John M. Edwards
All Physics Faculty Publications
A uniformly magnetized sphere moves without friction in a plane in response to the field of a second, identical, fixed sphere and makes elastic hardsphere collisions with this sphere. Numerical simulations of the threshold energies and periods of periodic finiteamplitude nonlinear bouncing modes agree with smallamplitude closedform mathematical results, which are used to identify scaling parameters that govern the entire amplitude range, including powerlaw scaling at large amplitudes. Scaling parameters are combinations of the bouncing number, the rocking number, the phase, and numerical factors. Discontinuities in the scaling functions are found when viewing the threshold energy and period as separate ...
A SemiKinetic Model Of Plasmasphere Refilling Following Geomagnetic Storms And Comparison With Hydrodynamic Results, Kausik Chatterjee, Robert W. Schunk
A SemiKinetic Model Of Plasmasphere Refilling Following Geomagnetic Storms And Comparison With Hydrodynamic Results, Kausik Chatterjee, Robert W. Schunk
All Physics Faculty Publications
The objective of this paper is the development of a kinetic model for plasmasphere refilling following geomagnetic storms. The kinetic model is based on the ‘particleincell’ method, a method based on the simulation of particle motion and thus wellsuited to high altitude, lowdensity regimes, where the plasma transport equations are not valid. The model was validated with exact, analytical benchmarks, which are provided in this paper. The refilling results obtained from the kinetic model were then compared with results from a recently developed hydrodynamic solution methodology based on the ‘fluxcorrected transport’ (FCT) method, and the limitations of hydrodynamic modeling for ...
Exploratory Measurements Of Large Winds And Shears In The Lower Thermosphere And Their Variability Using An Enhanced Sodium Lidar, Tao Yuan
Funded Research Records
No abstract provided.
Model‐Based Properties Of The Dayside Open/Closed Boundary: Is There A Ut‐Dependent Variation?, David A. Smith, Jan J. Sojka
Model‐Based Properties Of The Dayside Open/Closed Boundary: Is There A Ut‐Dependent Variation?, David A. Smith, Jan J. Sojka
All Physics Faculty Publications
The open‐closed boundary (OCB) defines a region of significant transformation in Earth's protective magnetic shield. Principle among these changes is the transition of magnetic field lines from having two foot points, one in each hemisphere, to one foot point at Earth, the other mapping to the solar wind. Charged particles in the solar wind are able to follow these open field lines into Earth's upper atmosphere. The OCB also defines the polar cap boundary. Being able to identify and track the OCB allows study of several components of the geomagnetic system. Among them are the electrodynamics of ...
Decomposing The Hamiltonian Of Quantum Circuits Using Machine Learning, Jordan Burns, Yih Sung, Colby Wight
Decomposing The Hamiltonian Of Quantum Circuits Using Machine Learning, Jordan Burns, Yih Sung, Colby Wight
Physics Capstone Projects
Quantum computing is one of the most promising techniques for simulating physical systems that cannot be simulated on classical computers[1]. A significant drawback of this approach is the inherent difficulty in designing circuits that can represent these systems on quantum computers. Every quantum circuit is built out of small components called quantum gates. Each of these gates manipulate the quantum system in a specific way. When used in combination, a finite subset of these gates, the set of universal gates, can be used to construct any possible quantum circuit[2].
Halving Iso(7) Supergravity, Adolfo Guarino, Javier Tarrío, Oscar Varela
Halving Iso(7) Supergravity, Adolfo Guarino, Javier Tarrío, Oscar Varela
All Physics Faculty Publications
Halfmaximal, N = 4, sectors of D = 4 N = 8 supergravity with a dyonic ISO(7) gauging are investigated. We focus on a halfmaximal sector including three vector multiplets, that arises as a certain SO(3)_{R}invariant sector of the full theory. We discuss the embedding of this sector into the largest halfmaximal sector of the N = 8 supergravity retaining six vector multiplets. We also provide its canonical N = 4 formulation and show that, from this perspective, our model leads in its own right to a new explicit gauging of N = 4 supergravity. Finally, expressions for the restricted duality hierarchy ...
Melissa: System Description And Spectral Features Of Pre And PostMidnight FRegion Echoes, Fabiano S. Rodrigues, Weijia Zhan, Marco A. Milla, Bela G. Fejer, Eurico R. De Paula, Acacio C. Neto, Angela M. Santos, Inez S. Batista
Melissa: System Description And Spectral Features Of Pre And PostMidnight FRegion Echoes, Fabiano S. Rodrigues, Weijia Zhan, Marco A. Milla, Bela G. Fejer, Eurico R. De Paula, Acacio C. Neto, Angela M. Santos, Inez S. Batista
All Physics Faculty Publications
Most of the low‐latitude ionospheric radar observations in South America come from the Jicamarca Radio Observatory, located in the western longitude sector (∼75°W). The deployment of the 30 MHz FAPESP‐Clemson‐INPE (FCI) coherent backscatter radar in the magnetic equatorial site of São Luis, Brazil, in 2001 allowed observations to be made in the eastern sector (∼45°W). However, despite being operational for several years (2001–2012), FCI only made observations during daytime and pre‐midnight hours, with a few exceptions. Here, we describe an upgraded system that replaced the FCI radar and present results of full‐night ...