Physical Sciences and Mathematics Commons^™

A Comparison Of Methods For Generating Bivariate Non-Normally Distributed Random Variables, Jaimee E. Stewart

UNF Graduate Theses and Dissertations

Many distributions of multivariate data in the real world follow a non-normal model with distributions being skewed and/or heavy tailed. In studies in which multivariate non-normal distributions are needed, it is important for simulations of those variables to provide data that is close to the desired parameters while also being fast and easy to perform. Three algorithms for generating multivariate non-normal distributions are reviewed for accuracy, speed and simplicity. They are the Fleishman Power Method, the Fifth-Order Polynomial Transformation Method, and the Generalized Lambda Distribution Method. Simulations were run in order to compare the three methods by how well they …

Electrostatic Discharge In Spacecraft Materials, Jennifer Albretsen Roth

All Physics Faculty Publications

Understanding the characteristics of electron beam bombardment that induce electrostatic discharge (ESD) of insulating materials is crucial to constructing an electrically stable spacecraft. A measurement system has been designed to determine the beam energy and charge flux densities at which typical spacecraft materials intended for the James Webb Space Telescope (JWST) undergo ESD. Because discharge events occur over time intervals ranging from nanoseconds to minutes, multiple detection methods were employed as charge was accumulated on a sample surface; these methods included monitoring of sample current and optical emissions from the sample surface. Each sample was also examined with optical microscopy …

Characterization Of Electrical Materials Properties Related To Spacecraft Charging, John R. Dennison

All Physics Faculty Publications

No abstract provided.

Symmetry Reduction Of Quasi-Free States, Charles G. Torre

All Physics Faculty Publications

Given a group-invariant quasi-free state on the algebra of canonical commutation relations (CCR), we show how group averaging techniques can be used to obtain a symmetry-reduced CCR algebra and reduced quasi-free state. When the group is compact, this method of symmetry reduction leads to standard results which can be obtained using other methods. When the group is noncompact, the group averaging prescription relies on technically favorable conditions which we delineate. As an example, we consider symmetry reduction of the usual vacuum state for a Klein–Gordon field on Minkowski spacetime by a noncompact subgroup of the Poincaré group consisting of a …

Core-Level Shifts At The Pt/W(110) Monolayer Bimetallic Interface, D. Mark Riffe, N. D. Shinn, B. Kim, K. J. Kim, T. H. Kang

All Physics Faculty Publications

We have measured W and Pt 4f7/2 core-level photoemission spectra from interfaces formed by ultrathin Pt layers on W(110), completing our core-level measurements of W(110)-based bimetallic interfaces involving the group-10 metals Ni, Pd, and Pt. With increasing Pt coverage the sequence of W spectra can be described using three interfacial core-level peaks with binding-energy (BE) shifts (compared to the bulk) of −0.220 ± 0.015, −0.060 ± 0.015, and +0.110 ± 0.010 eV. We assign these features to 1D, 2D pseudomorphic (ps), and 2D closed-packed (cp) Pt phases, respectively. For ~1 ps ML the Pt 4f7/2 BE is 71.40 ± 0.02 …

Detecting A Stochastic Gravitational-Wave Background: The Overlap Reduction Function, Lee Samuel Finn, Shane L. Larson, Joseph D. Romano

All Physics Faculty Publications

Detection of a gravitational-wave stochastic background via ground or space-based gravitational-wave detectors requires the cross correlation of the response of two or more independent detectors. The cross correlation involves a frequency-dependent factor—the so-called overlap reduction function or Hellings-Downs curve—that depends on the relative geometry of each detector pair, i.e., the detector separations and the relative orientation of their antenna patterns (beams). An incorrect formulation of this geometrical factor has appeared in the literature, leading to incorrect conclusions regarding the sensitivity of proposed detectors to a stochastic gravitational-wave background. To rectify these errors and as a reference for future work we …

Determinants Of Atmospheric Mercury Concentrations In Reno, Nevada, U.S.A., Seth N. Lyman, Mae Sexauer Gustin

USU Uintah Basin Faculty Publications

Concentrations of gaseous elemental mercury (GEM), gaseous oxidized mercury (GOM) and particulate-bound mercury (PBM) were measured along with ancillary variables 9 km east of downtown Reno, Nevada, U.S.A. from November 2006 through March 2009. Mean two-year (February 2007 through January 2009) GEM, GOM, and PBM concentrations were 2.0 ± 0.7 ng m− 3 (± standard deviation), 18 ± 22 pg m− 3, and 7 ± 7 pg m− 3, respectively. Data collected were compared with observations made at another location just north of the city at 169 m higher elevation. At both locations higher concentrations of GEM and PBM occurred …

Observations Of Speciated Atmospheric Mercury At Three Sites In Nevada: Evidence For A Free Tropospheric Source Of Reactive Gaseous Mercury, Peter Weiss-Penzias, Mae Sexauer Gustin, Seth Lyman

USU Uintah Basin Faculty Publications

Air mercury (Hg) speciation was measured for 11 weeks (June–August 2007) at three sites simultaneously in Nevada, USA. Mean reactive gaseous Hg (RGM) concentrations were elevated at all sites relative to those reported for locations not directly influenced by known point sources. RGM concentrations at all sites displayed a regular diel pattern and were positively correlated with ozone (O₃) and negatively correlated with elemental Hg (Hg0) and dew point temperature (Tdp). Superimposed on the diel changes were 2- to 7-day periods when RGM concentrations increased across all three sites, producing significant intersite correlations of RGM daily means (r …

Removal Of Nonconstant Daily Variation By Means Of Wavelet And Functional Data Analysis, I. Maslova, P. Kokoszka, Jan Josef Sojka, L. Zhu

All Physics Faculty Publications

We propose a novel approach based on wavelet and functional principal component analysis to produce a cleaner index of the intensity of the symmetric ring current. We use functional canonical correlations to show that the new approach more effectively extracts symmetric global features. The main result of our work is the construction of a new index, which is an improved version of the existing wavelet-based index (WISA) and the old Dst index, in which a constant daily variation is removed. Here, we address the fact that the daily component varies from day to day and construct a “cleaner” index by …

Bubble Behavior In Nucleate Boiling Experiment Aboard The Space Shuttle, Justin P. Koeln, Jeffrey C. Boulware, Heng Ban

All Physics Faculty Publications

Boiling dynamics in microgravity need to be better understood before heat transfer systems based on boiling mechanism can be developed for space applications. This paper presents the results of a nucleate boiling experiment aboard Space Shuttle Endeavor (STS- 108). The experiment utilized nickel-chromium resistance wire to boil water in microgravity, and the data was recorded with a CCD camera and six thermistors. This data was analyzed to determine the behavior of bubble formation, detachment from the heating wire, and travel in the water with effects of drag on bubble movement. Bubbles were observed to be ejected from the wire, travel …

Critical Level Interaction Of A Gravity Wave With Background Winds Driven By A Large-Scale Wave Perturbation, M. K. Ejiri, Michael J. Taylor, T. Nakamura, S. J. Franke

All Physics Faculty Publications

As part of the Maui-Mesosphere and Lower Thermosphere program, data from the Utah State University Mesospheric Temperature Mapper (MTM) and the University of Illinois Meteor Wind Radar (MWR) have been used to investigate wave-driven dynamical interactions in the upper mesosphere at low latitudes. On 29 June 2003, short-period (20 min) gravity waves (GWs) were imaged in the MTM in the near-infrared OH and O2 airglow emissions for most of the night from 0700 to 1500 UT. The GWs were observed to disappear rapidly in the O2 data (peak altitude: 94 km) around 1400 UT but remained evident in the lower …

Relevance Of Ground-Based Electron-Induced Electrostatic Discharge Measurements To Space Plasma Environments, Jennifer A. Roth, Ryan Hoffmann, John R. Dennison, Jonathon R. Tippetts

All Physics Faculty Publications

Electron-induced electrostatic discharge (ESD) can lead to severe spacecraft anomalies. It is crucial to the success of space missions that the likelihood of ESD occurrence is understood and mitigated. To aid in predicting ESD occurrence, a model for electric fields above and below the charge layer inside an electronirradiated dielectric material was developed. An instrumentation system was also designed to induce and detect ESD events. Because ESD events with a wide range of maximum current values can occur over a range of time intervals, multiple simultaneous detection methods were employed as charge was accumulated on a sample surface; these included …

Overview And Summary Of The Spread F Experiment (Spreadfex), D. C. Fritts, M. A. Abdu, B. R. Batista, I. S. Batista, P. P. Batista, R. Buritii, B. R. Clemesha, J. Comberiate, T. Dautermann, E. De Paula, B. J. Fechine, B. G. Fejer, D. Gobbi, J. Haase, F. Kalamabadi, B. Laughman, P. P. Lima, H. L. Liu, A. Medeiros, Pierre-Dominique Pautet, F. Sao Sabbas, J. H.A. Sobral, P. Stamus, H. Takahashi, Michael J. Taylor, S. L. Vadas, C. Wrasse

All Physics Faculty Publications

We provide here an overview of, and a summary of results arising from, an extensive experimental campaign (the Spread F Experiment, or SpreadFEx) performed from September to November 2005, with primary measurements in Brazil. The motivation was to define the potential role of neutral atmosphere dynamics, specifically gravity wave motions propagating upward from the lower atmosphere, in seeding Rayleigh-Taylor instability (RTI) and plasma bubbles extending to higher altitudes. Campaign measurements focused on the Brazilian sector and included ground-based optical, radar, digisonde, and GPS measurements at a number of fixed and temporary sites. Related data on convection and plasma bubble structures …

A Frequency Agile, Distributed Sensor System To Address Space Weather Effects Upon Ionospherically Dependent Systems, D. D. Rice, J. V. Eccles, Jan Josef Sojka, J. W. Raitt, J. Brady, R. D. Hunsucker

All Physics Faculty Publications

The outstanding problem faced by operational systems that utilize the ionosphere is that ionospheric weather variability is comparable to the ionospheric climate variability. However, the number of simultaneous measurements is orders of magnitude too few to resolve the weather scales that are impacting systems. We describe a prototype distributed array of affordable passive radio beacon monitors combined with a central data repository and a data-model analysis system called the Frequency-Agile Distributed Sensor System (FADSS). By monitoring signals from terrestrial VLF/HF radio beacons the FADSS tracks changes in the D, E, or F regions and makes appropriate modifications to the ionospheric …

Thin Wire Nucleate Boiling Of Water In Sustained Microgravity, Justin P. Koeln, Heng Ban, John R. Dennison

All Physics Faculty Publications

The advancement of small satellite technology relies on the development of effective thermal management systems that can be made smaller, safer, and more robust. This paper presents the results and analysis of a nucleate boiling experiment in sustained microgravity aboard the Space Shuttle Endeavor (STS-108). Bubble growth and departure were observed from a single and a braid of three 0.16 mm diameter and 80 mm long nickel-chromium resistive wires. Analysis showed that the braided wire provides a unique surface configuration to enhance the onset of boiling. The braid of wires was also observed to produce several bubble explosions; this is …

Field Demonstration Of Simultaneous Wind And Temperaturemeasurements From 5to50 Km With A Na Double-Edge Magneto-Optic Filter In A Multi-Frequency Doppler Lidar, W. Huang, X. Chu, Johannes Wiig, Bo Tan, Chihoko Yamashita, Tao Yuan, J. Yue, S. D. Harrell, C. Y. She, B. P. Williams, J. S. Friedman, R. M. Hardesty

All Physics Faculty Publications

We report the first (to our knowledge) field demonstration of simultaneous wind and temperature measurements with a Na double-edge magneto-optic filter implemented in the receiver of a three-frequency Na Doppler lidar. Reliable winds and temperatures were obtained in the altitude range of 10-45 km with 1 km resolution and 60 min integration under the conditions of 0.4 W lidar power and 75 cm telescope aperture. This edge filter with a multi-frequency lidar concept can be applied to other direct-detection Doppler lidars for profiling both wind and temperature simultaneously from the lower to the upper atmosphere.

Storm-Time Density Enhancements In The Middle Latitude Dayside Ionosphere, R. A. Heelis, Jan Josef Sojka, M. David, Robert W. Schunk

All Physics Faculty Publications

Enhancements of the total electron content (TEC) in the middle-latitude dayside ionosphere have often been observed during geomagnetic storms. The enhancements can be as large as a factor of 2 or more, and many sightings of such structures have occurred over the United States. Here we investigate the effectiveness of an expanded convection electric field as a mechanism for producing such ionospheric enhancements. As a test case, we examine the storm period of 5–7 November 2001, for which observations from the DMSP F13 are used to drive the Time Dependent Ionospheric Model (TDIM). Our findings indicate that at favorable universal …

Engineering Tool For Temperature, Electric Field And Dose Rate Dependence Of High Resistivity Spacecraft Materials, John R. Dennison, Alec Sim, Jerilyn Brunson, Steven Hart, Jodie Gillespie, Justin Dekany, Charles Sim, Dan Arnfield

All Physics Faculty Publications

An engineering tool has been developed to predict the equilibrium conductivity of common spacecraft insulating materials as a function of electric field, temperature, and adsorbed dose rate based on parameterized, analytic functions derived from physics-based theories. The USU Resistivity Calculator Engineering Tool calculates the total conductivity as the sum of three independent conductivity mechanisms: a thermally activated hopping conductivity, a variable range hopping conductivity, and a radiation induced conductivity using a total of nine independent fitting parameters determined from fits to an extensive data set taken by the Utah State University Materials Physics Group. It also provides a fit for …

Observations Of Ionospheric Heating During The Passage Of Solar Coronal Hole Fast Streams, Jan Josef Sojka, R. L. Mcpherron, A. P. Van Eyken, M. J. Nicolis, C. J. Heinselman, J. D. Kelley

All Physics Faculty Publications

Using ionospheric temperature measurements made continuously by the Poker Flat Incoherent Scatter Radar (PFISR) and EISCAT Svalbard Radar (ESR) during the International Polar Year (IPY), we provide evidence for directly driven ionospheric heating associated with the solar wind corotating interaction region (CIR). Both ESR and PFISR operated almost continuously during the IPY, which began on 1 March 2007. During this period 55 CIR events occurred and when ISR observations were available during these events ionospheric heating was observed. This study is the first comprehensive observation of ionospheric heating by CIRs demonstrated through case study comparisons and statistically over the 1-year …

The Spread F Experiment (Spreadfex): Overview And Summary Of The Spread F Experiment (Spreadfex), D. C. Fritts, M. A. Abdu, B. R. Batista, I. S. Batista, P. P. Batista, R. Buriti, B. R. Clemesha, T. Dautermann, E. De Paula, B. J. Fechine, B. G. Fejer, D. Gobbi, J. Haase, F. Kamalabadi, B. Luughman, P. P. Lima, H. L. Liu, A. F. Medeiros, P. D. Pautet, D. M. Riggin, F. São Sabbas, J. H.A. Sobral, P. Stamus, H. Takahashi, Michael J. Taylor, S. L. Vadas, C. Wrasse

All Physics Faculty Publications

The Spread F Experiment, or SpreadFEx, was performed from September to November 2005 to define the potential role of neutral atmosphere dynamics, primarily gravity waves propagating upward from the lower atmosphere, in seeding equatorial spread F (ESF) and plasma bubbles extending to higher altitudes. A description of the SpreadFEx campaign motivations, goals, instrumentation, and structure, and an overview of the results presented in this special issue, are provided by Fritts et al. (2008a). The various analyses of neutral atmosphere and ionosphere dynamics and structure described in this special issue provide enticing evidence of gravity waves arising from deep convection in …

Plasmasphere And Upper Ionosphere Contributions And Corrections During The Assimilation Of Gps Slant Tec, D. C. Thompson, L. Scherliess, Jan Josef Sojka, Robert W. Schunk

All Physics Faculty Publications

Total electron content (TEC) measurements from ground stations to Global Positioning System (GPS) satellites provide a rich source of information about the Earth's ionosphere. These data comprise a significant part of the typical data set used by various data ingestion and assimilation models of the ionosphere. For example, the Utah State University (USU) Global Assimilation of Ionospheric Measurements (GAIM) data assimilation model uses slant TEC, along with various other types of data, to obtain a global reconstruction of the ionosphere. There are presently two different USU GAIM models: the Gauss‐Markov Kalman Filter (GAIM‐GM), which is operational at the NASA Community …

Characterizing The Lower Ionosphere With A Space - Weather - Aware Receiver Matrix, D. D. Rice, R. D. Hunsucker, J. V. Eccles, Jan Josef Sojka, J. W. Raitt, J. J. Brady

All Physics Faculty Publications

Current ionospheric models are very good at specifying regular diurnal and seasonal variations of the E and F regions of the ionosphere. Less is known about the behavior of the D region, although progress has recently been made with models such as the Data-Driven D-Region (DDDR). However, significant departures from modeled behaviors are observed even during solar minimum conditions, due to complex ionospheric weather effects arising from both solar activity above and terrestrial atmospheric perturbations below. The D-region perturbations directly affect VLF communications, and also affect daytime absorption of frequencies from LF through HF. Perturbations in the E and F …

Engineering Tool For Temperature, Electric Field And Dose Rate Dependence Of High Resistivity Spacecraft Materials, Jr Dennison, Steven Hart, Jodie Corbridge Gillespie, Justin Dekany, Charles Sim, Dan Arnfield

Conference Proceedings

An engineering tool has been developed to predict the equilibrium resistivity of common spacecraft insulating materials as a function of electric field (Ε), temperature (T), and adsorbed dose rate (Ď) based on parameterized, analytic functions used to model an extensive data set taken by the Utah State University Materials Physics Group. The ranges of E, T and Ď measured in the experiments were designed to cover as much of the ranges typically encountered in space environments as possible: (i) the typical electric field range was from 10⁴ V-m^-1 to 10⁷ V-m^-1 or from <0.1% up to between 30% to 90%of the electrostatic breakdown field strength; (ii) temperature was measured and modeled over a typical range of 150 K to 330 K (within limits noted below); and the adsorbed dose rate was measured and modeled over a range of 10^-5 Gray …

Measurement Of Charging And Discharging Of High Resistivity Materials Spacecraft Materials By Electron Beams, Ryan Hoffmann, Joshua L. Hodges, Jesse Hayes, Jr Dennison

Conference Proceedings

New instrumentation has been developed for in situ measurements of the electron beam- induced surface voltage of high resistivity spacecraft materials in an existing ultra-high vacuum electron emission analysis chamber. Design details, calibration and characterization measurements of the system are presented, showing sensitivity to a range of surface voltages from12000 V, with resolution surface, using a paddle attached to a vacuum compatible stepper motor mounted within a hemispherical grid retarding field analyzer. These electrodes formed one end of a floating charge transfer probe that enabled measurements to be made by a standard electrostatic field probe external to the vacuum chamber. …

Temperature Dependence Of Radiation Induced Conductivity In Insulators, Jr Dennison, Jodie Corbridge Gillespie, Joshua Hodges, Ryan C. Hoffman, J Abott, Steven Hart, Alan W. Hunt

Journal Articles

We report on measurements of Radiation Induced Conductivity (RIC) of thin film Low Density Polyethylene (LDPE) samples. RIC occurs when incident ionizing radiation deposits energy in a material and excites electrons into conduction states. RIC is calculated as the difference in sample conductivity under an incident flux and “dark current” conductivity under no incident radiation.

The primary focus of this study is the temperature dependence of the steady state RIC over a wide range of absorbed dose rates, from cryogenic temperatures to well above room temperature. The measured RIC values are compared to theoretical predictions of dose rate and temperature …

Resources - Thinking Small: Nano Small, David Stricker

Publications

The article provides information on the "Nanooze" magazine publication. It notes the significance of nanotechnology to the development of latest innovations that come from materials at smallest dimensions or at the nanoscale levels. It presents resources published within the publication that explore the emerging issues in nanotechnology.

Space Research Projects For The International Space Station, Kyle Hodgson, Jr Dennison

Posters

No abstract provided.

Development Of A Cubesat Pico-Satellite, Phillip Anderson, Jan Sojka

Posters

The CubeSat Project was developed by California Polytechnic State University (CalPoly) and Stanford University in order to provide launch opportunities to universities previously unable to afford access to space. Today, it provides low-cost launch opportunities to students, government, and business. The CubeSat program is able to provide these low-cost launch opportunities by defining a common form factor and design guidelines. All satellites conforming to the regulations are able to be deployed from a standard, flight-proven deployment system called a PPOD. by adhering to the prescribed form factor and safety requirements, necessary documents and export licenses and more easily obtained. CalPoly …

Microgravity Experiments For The Iss, Justin Koeln, Jan Sojka

Posters

The Get Away Special (GAS) team is a microgravity research team know for leading Utah State University to impressive distinction of flying more experiments in space than any other university in the world. The following experiments were designed by the GAS team after receiving the opportunity to develop and experiment to be performed by a Space Flight Participant aboard the International Space Station (ISS).

Photoelectric Charging By Ultraviolet Light Of A Lunar Dust Simulant In A Microgravity Environment, Troy Munro, Andrew Fassmann, Jr Dennison

Posters

A microgravity experiment to test the electrostatic behavior of a lunar dust simulant being charged through the photoelectric effect will expand understanding of the charging characteristics of dust particles and may lead to a possible mitigation solution. With a design based upon Robert Milikan's oil-drop experiment, this experiment is designed to observe the interactions of a lunar dust simulant without the conflicting effects of a dominant gravitational force. The dust particles will be charged by means of a lamp capable of photon energies necessary to emit electrons by the photoelectric effect. In the presence of an axial electric field, the …