Physical Sciences and Mathematics Commons^™

Seasonal Flow Rates Along The Lower Bear River, Ut, Todd Keniry, Dahlia Curiel, Dylan Anderson, Ayman Alafifi, David E. Rosenberg

Spring Runoff Conference

The goal of this research is to identify how flow on the Bear River in Cache Valley has changed over the last three years and how flow changes seasonally. Identifying flows is important to manage water resources along the Bear River. We collected and processed water pressure data every 30 minutes using HOBO transducers at two sites in Cache Valley (Morton, just downstream of highway 142, and Confluence which is located at the confluence of the Bear and Cub Rivers) south of the Idaho‐Utah border in 2015. We also measured flow and water stage up to three times per year …

Perspectives On The Distributions Of Esd Breakdowns For Spacecraft Charging Applications, Allen Andersen, Krysta Moser, Jr Dennison

Conference Proceedings

Electrostatic discharge (ESD) continues to pose significant risks to space missions despite decades of intense study. We emphasize here the advantages to spacecraft designers and modelers from considering the stochastic distributions of breakdown and how it can be affected by factors including spacecraft environment conditions, design geometries, material temperature, material purity, charging history, and appropriate timescales. Spacecraft charging models and spacecraft designs typically rely on tabulated values or ranges of breakdown strength, often based on cursory measurements with little or no experimental detail. Depending on the timescales and history of environmental and orbital changes or durations of specific missions, it …

Pea System Modeling And Signal Processing For Measurement Of Volume Charge Distributions In Thin Dielectric Films, Lee H. Pearson, Jr Dennison, Erick W. Griffiths, A C. Pearson

Conference Proceedings

This paper discusses an effort to develop advanced pulsed electroacoustic (PEA) measurement system capabilities that incorporate (1) improved signal processing tools for increased signal/noise ratios; and (2) integrated PEA modeling tools. In addition, we emphasize state-of-the-art system electronic components, integrated environmental controls, and sensor improvements required to achieve high spatial resolution while maintaining reasonable temporal resolution for both ambient and in vacuo measurements of thin dielectrics charged using electron beam injection, which are most applicable for spacecraft charging tests. PEA measurement systems provide an important tool to investigate the spatial extent and dynamic evolution of such embedded charge distributions in …

Temporal And Spatial Correlations In Electron-Induced Arcs Of Adjacent Dielectric Islands, Justin Christensen, Jr Dennison, Justin Dekany

Posters

This study investigates very short duration (<1ms) flashes caused by rapid discharge arcs from charged insulating epoxy “glue dots” to an underlying grounded substrate. There were 36 separate ~3 mm diameter hemispherical bisphenol/amine epoxy “glue dots” positioned around the conducting polymeric/carbon nanocomposite substrate edge exposed simultaneously to nearly identical electron fluxes. Most arcs are found to be random events which occur when built up charge produces an electric field large enough for electrostatic breakdown to occur. The possibility that a given arc might stimulate arcs in adjacent “glue dots” was investigated through coincidence correlation analysis. The dependence of such correlations with “glue dot” separation was also studied.

The data for this project were collected at Marshall Space Flight Center. The epoxy “glue dot” samples were mounted inside a high vacuum (<10^-4 Pa) chamber on a Black Kapton substrate attached to a large grounded metal plate, cooled with liquid nitrogen to ~120 K. An electron gun was used to bombard the sample with electrons of a known energy (12 to 40 keV) and flux density (0.3 to 5 nA/cm²), similar to what would be seen in a typical space environment. Light emitted from the samples was monitored with …

Dependence Of Electrostatic Field Strength On Voltage Ramp Rate For Spacecraft Materials, Krysta Moser, Allen Andersen, Jr Dennison

Posters

This work investigated the dependence of electrostatic field strength for spacecraft materials on voltage ramp rate, by applying an increasing electrostatic field until electrostatic breakdown (a permanent, catastrophic failure of a dielectric material) occurs. Enhanced understanding of prolonged exposure to high static electric fields (DC aging) of insulating materials based on expanded experimental studies is of critical to understand the physics of highly disordered insulating materials, as well as for applications in spacecraft charging, high voltage DC power transmission cables and switching, thin film dielectrics, and semiconductor devices and sensors. Electrostatic discharge (ESD) and the associated material breakdown at the …

Pea System Modeling And Signal Processing For Measurements Of Volume Charge Distributions In Thin Dielectric Films, Lee H. Pearson, Jr Dennison, Erick W. Griffiths, A. C. Pearson

Posters

This paper discusses an effort to develop advanced pulsed electroacoustic (PEA) measurement system capabilities that incorporate state-of-the-art hardware and improved signal processing and modeling to characterize embedded charge distributions in thin dielectric films. Objectives in developing this system include: (1) improved spatial resolution, while maintaining reasonable temporal resolution; (2) improved signal processing tools for increased signal/noise ratios; (3) integrated PEA modeling tools; and (4) integrated environmental controls. We emphasize system improvements required to achieve high spatial resolution for in vacuo measurements of thin dielectrics charged using electron beam injection, which are most applicable for spacecraft charging tests. PEA measurement systems …

Synergistic Models Of Electron Emission And Transport Measurements Of Disordered Sio2, Jr Dennison, Jodie Corbridge Gillespie, Allen Andersen, Amberly Evans Jensen, Gregory Wilson, Justin Dekany, Alec M. Sim, Ryan Hoffmann

Posters

A critical component in the prediction and mitigation of spacecraft charging issues is an accurate model of the charging, transport and electron emission properties of a broad array of materials used in the construction of spacecraft. The increased sensitivity, longer-duration missions, and ventures into more demanding environments only serve to heighten this need. One important way for the spacecraft charging community to address this issue is to expand the role of more fundamental materials physics. This includes the development of unifying theoretical models of the charge transport equations based on the creation, distribution, and occupancy of defect densities of states. …

Effects Of Voltage Ramp Rates On Electrostatic Field Strength In Highly Disordered Insulating Materials, Krysta Moser, Allen Andersen, Jr Dennison

Posters

At high enough electrostatic fields or after long exposure times, insulators can break down, causing large current flow through the material: this breakdown is called electrostatic discharge (ESD). ESD is a permanent, catastrophic failure of a dielectric material: what was an insulator is now essentially a conductor. Previous tests done by the USU Materials Physics Group (MPG) using our ESD custom vacuum chamber have found that, for the polymeric materials biaxially oriented polypropylene (BOPP), polyimide (PI), and low density polyethylene (LDPE), the electrostatic field strength at breakdown depends on the ramp rate of voltage applied across some materials, but possibly …

Absolute Electron Emission Calibration: Round Robin Tests Of Au And Polyimide, Jr Dennison, Justin Christensen, Clint Thomson, Neal Nickles, Robert E. Davies, Mohamed Belhaj, Kazuhiro Toyoda, Arifur R. Khan, Kazutaka Kawasaki, Shunsuke Inoue, Isabel Montero, Maria E. Davila, Leandro Olano

Posters

Accurate determination of the absolute electron yields of conducting and insulating materials are essential for models of spacecraft charging and related processes involving charge accumulation and emission due to electron beams and plasmas. Apparatus using low-fluence pulsed electron beam sources and various methods to minimize charge accumulation have been developed at facilities around the world. This study presents a round robin comparison of such tests performed in CSIC at Instituto de Ciencia de Materiales de Madrid, LaSeine at Kyushu Institute of Technology, DESSE at ONEREA, and the Space Environment Effects Materials (SEEM) test facility at Utah State University. The primary …

Predictive Formula For Electron Range Over A Large Span Of Energies, Anne C. Starley, Gregory Wilson, Lisa Montierth Phillipps, Jr Dennison

Posters

An empirical model developed by the Materials Research Group that predicts the approximate electron penetration depth—or range—of some common materials has been extended to predict the range for a broad assortment of other materials. The electron range of a material is the maximum distance electrons can travel through a material, before losing all of their incident kinetic energy. The original model used the Continuous-Slow-Down-Approximation for energy deposition in a material to develop a composite analytical formula which estimated the range from 10 MeV with an uncertainty of v, which describes the effective number of valence electrons. N_V was empirically …

Perspectives On The Distributions Of Esd Breakdowns For Spacecraft Charging Applications, Allen Andersen, Krysta Moser, Jr Dennison

Presentations

Electrostatic discharge (ESD) continues to pose significant risks to space missions despite decades of intense study. We emphasize here the advantages to spacecraft designers and modelers from considering the stochastic distributions of breakdown and how it can be affected by factors including spacecraft environment conditions, design geometries, material temperature, material purity, charging history, and appropriate timescales. Spacecraft charging models and spacecraft designs typically rely on tabulated values or ranges of breakdown strength, often based on cursory measurements with little or no experimental detail. Depending on the timescales and history of environmental and orbital changes or durations of specific missions, it …

Temporal And Spatial Correlations In Electron-Induced Arcs Of Adjacent Dielectric Islands, Justin Christensen, Jr Dennison, Justin Dekany

Presentations

This study investigates very short duration (

The data for this project were collected at Marshall Space Flight Center. The epoxy “glue dot” samples were mounted inside a high vacuum (<10^-4 Pa) chamber on a Black Kapton substrate attached to a large grounded metal plate, cooled with liquid nitrogen to ~120 K. An electron gun was used to bombard the sample with electrons of a known energy (12 to 40 keV) and flux density (0.3 to 5 nA/cm²), similar to what would be seen in a typical space environment. Light emitted from the samples was monitored with …

Absolute Electron Emission Calibration: Round Robin Tests Of Au And Polyimide, Jr Dennison, Justin Christensen, Justin Dekany, Clint Thomson, Neal Nickles, Robert E. Davies, Mohamed Belhai, Kazuhiro Toyoda, Arifur R. Khan, Kazutaka Kawasaki, Shunsuke Inoue, Isabel Montero, Maria E. Davila, Leandro Olano

Presentations

Accurate determination of the absolute electron yields of conducting and insulating materials are essential for models of spacecraft charging and related processes involving charge accumulation and emission due to electron beams and plasmas. Apparatus using low-fluence pulsed electron beam sources and various methods to minimize charge accumulation have been developed at facilities around the world. This study presents a round robin comparison of such tests performed in CSIC at Instituto de Ciencia de Materiales de Madrid, LaSeine at Kyushu Institute of Technology, DESSE at ONEREA, and the Space Environment Effects Materials (SEEM) test facility at Utah State University. The primary …

Validation Of Enhanced Electron Yield Measurements Of Low-Conductivity, High-Yield Materials, Justin Christensen, Gregory Wilson, Jr Dennison

Presentations

Materials exposed to electron bombardment can charge positively or negatively, depending on the number of electrons ejected from the material. This electron emission is the main mechanism which drives spacecraft charging, which can induce electrostatic breakdown of insulators and damage pertinent electrical, optical, and mechanical components. The electron yield (ratio of emitted to incident electrons) is an intrinsic property which characterizes how a material will charge under these types of conditions. However electron yield of insulators is very difficult to measure because measurement causes charge buildup.

To measure the intrinsic yield (yield of uncharged material) of insulators new methods have …

Pea System Modeling And Signal Processing For Measurement Of Volume Charge Distributions In Thin Dielectric Films, Lee H. Pearson, Jr Dennison, Erick W. Griffiths, A. C. Pearson

Presentations

This paper discusses an effort to develop advanced pulsed electroacoustic (PEA) measurement system capabilities that incorporate state-of-the-art hardware and improved signal processing and modeling to characterize embedded charge distributions in thin dielectric films. Objectives in developing this system include: (1) improved spatial resolution, while maintaining reasonable temporal resolution; (2) improved signal processing tools for increased signal/noise ratios; (3) integrated PEA modeling tools; and (4) integrated environmental controls. We emphasize system improvements required to achieve high spatial resolution for in vacuo measurements of thin dielectrics charged using electron beam injection, which are most applicable for spacecraft charging tests. PEA measurement systems …

Dependence Of Electrostatic Field Strength On Voltage Ramp Rate For Spacecraft Materials, Krysta Moser, Allen Andersen, Jr Dennison

Presentations

This work investigated the dependence of electrostatic field strength for spacecraft materials on voltage ramp rate, by applying an increasing electrostatic field until electrostatic breakdown (a permanent, catastrophic failure of a dielectric material) occurs. Enhanced understanding of prolonged exposure to high static electric fields (DC aging) of insulating materials based on expanded experimental studies is of critical to understand the physics of highly disordered insulating materials, as well as for applications in spacecraft charging, high voltage DC power transmission cables and switching, thin film dielectrics, and semiconductor devices and sensors. Electrostatic discharge (ESD) and the associated material breakdown at the …

Quantum Computing Vs. Conventional Computing: Near-Term Solution Is Smart Distributed Systems, Seyed M.H. Mansourbeigi, Stephen W. Clyde

Computer Science Student Research

Are we getting to the end of Moore's law????? Moore's law which is held for 50 years tells computer power doubling every 18 months may begin to expire in the next 10 or so years. Imagine you buy a computer having the same power as the last year and the year before last year. Would you buy a new computer? Or upgrade? The present computer model is CPU with I/O's and combination of logical gates, and software which controls these I/O's based on finite automata and Turing machine. Basically the above hard-ware software model manipulates the 0 and 1 bits.

Factoring Attitudes Towards Conflict Risk Into Selection Of Protected Areas For Conservation, Edd Hammill, A. I. Tulloch, H. P. Possingham, N. Strange, K. A. Wilson

Watershed Sciences Faculty Publications

The high incidence of armed conflicts in biodiverse regions poses significant challenges in achieving international conservation targets. Because attitudes towards risk vary, we assessed different strategies for protected area planning that reflected alternative attitudes towards the risk of armed conflicts. We find that ignoring conflict risk will deliver the lowest return on investment. Opting to completely avoid conflict-prone areas offers limited improvements and could lead to species receiving no protection. Accounting for conflict by protecting additional areas to offset the impacts of armed conflicts would not only increase the return on investment (an effect that is enhanced when high-risk areas …

Developing A Safe Test System For High-Energy Electron Flux Environments Testing, Heather Tippets

Posters

In order to predict and mitigate adverse environmental effects prone to spacecraft in orbit about earth, a versatile pre-launch test capability for assessment and verification of small satellites, systems, and components was developed by Utah State University’s Materials Physics Group. To further diversify this project, a 100 mCi strontium-90 beta radiation source (0.5 MeV – 2.5 MeV) was exploited to simulate high energy electron flux characteristic of geostationary orbit. Various samples including in-the-loop hardware, spacecraft materials, optical components, and solar arrays will be irradiated to gain a better understanding how these materials and electronics break down in space environments. For …

Polar Cap Patches And The Tongue Of Ionization: A Survey Of Gps Tec Maps From 2009 To 2015, Michael David, Jan Josef Sojka, A. J. Coster

All Physics Faculty Publications

The source and structuring mechanisms for F region density patches have been subjects of speculation and debate for many years. We have made a survey of mappings of total electron content (TEC) between the years 2009 and 2015 from the web‐based Madrigal data server in order to determine when patches and/or a tongue of ionization (TOI) have been present in the Northern Hemisphere polar cap; we find that there is a UT and seasonal dependence that follows a specific pattern. This finding sheds considerable light upon the old question of the source of polar cap patches, since it virtually eliminates …

Hydrogen Bonded And Stacked Geometries Of The Temozolomide Dimer, Okuma Emile Kasende, Jules Tshishimbi Muya, Vincent De Paul Nzuwah-Nziko, Steve Scheiner

Chemistry and Biochemistry Faculty Publications

Dispersion-corrected Density Functional Theory (DFT) and MP2 quantum chemical methods are used to examine homodimers of temozolomide (TMZ). Of the twelve dimer configurations found to be minima, the antarafacial stacked dimer is the most favored, lower in energy than coplanar dimers which are stabilized by H-bonds. The comparison between B3LYP and B3LYP-D binding energies points to dispersion as a primary factor in stabilizing the stacked geometries. CO(π)→CO(π*)charge transfers between amide groups in the global minimum are identified by NBO, as well as a pair of weak CH∙∙N H-bonds. AIM analysis of the electron density provides an alternative description which includes …

Expression Profiles Of Mirna Subsets Distinguish Human Colorectal Carcinoma And Normal Colonic Mucosa, Daniel F. Pellatt, John R. Stevens, Roger K. Wolff, Lila E. Mullany, Jennifer S. Herrick, Wade Samowitz, Martha L. Slattery

Mathematics and Statistics Faculty Publications

OBJECTIVES: MicroRNAs (miRNAs) are small, non-protein-coding RNA molecules that are commonly dysregulated in colorectal tumors. The objective of this study was to identify smaller subsets of highly predictive miRNAs.

METHODS: Data come from population-based studies of colorectal cancer conducted in Utah and the Kaiser Permanente Medical Care Program. Tissue samples were available for 1,953 individuals, of which 1,894 had carcinoma tissue and 1,599 had normal mucosa available for statistical analysis. Agilent Human miRNA Microarray V.19.0 was used to generate miRNA expression profiles; validation of expression levels was carried out using quantitative PCR. We used random forest analysis and verified findings …

Electron Parallel Closures For Various Ion Charge Numbers, Jeong-Young Ji, Sang-Kyeum Kim, Eric D. Held, Yong-Su Na

All Physics Faculty Publications

Electron parallel closures for the ion charge number Z = 1 [J.-Y. Ji and E. D. Held, Phys. Plasmas 21, 122116 (2014)] are extended for 1 ≤ Z ≤ 10. Parameters are computed for various Z with the same form of the Z = 1 kernels adopted. The parameters are smoothly varying in Z and hence can be used to interpolate parameters and closures for noninteger, effective ion charge numbers.

Radiation Safety Design For High Energy Electron Flux Environments Testing, Heather Tippets

Senior Theses and Projects

No abstract provided.

Developing A Safe Test System For High-Energy Electron Flux Environments Testing, Heather Tippets

Senior Theses and Projects

In order to predict and mitigate adverse environmental effects on spacecraft in orbit about Earth, a versatile pre-launch test capability for assessment and verification of small satellites, systems, and components was developed by Utah State University’s Materials Physics Group. To further diversify this project, a 100 mCi Sr-90 beta radiation source (0.5 MeV – 2.5 MeV) is exploited to simulate the high energy electron flux of geostationary orbit. Various samples including in-the-loop hardware, spacecraft materials, optical components, and solar arrays are irradiated to gain a better understanding of how these materials and electronics break down in space environments. For employee …

Unsupervised Saliency Estimation Based On Robust Hypotheses, Fei Xu, Min Xian, H. D. Cheng, Jianrui Ding, Yingtao Zhang

Computer Science Faculty and Staff Publications

Visual saliency estimation based on optimization models is gaining increasing popularity recently. In this paper, we formulate saliency estimation as a quadratic program (QP) problem based on robust hypotheses. First, we propose an adaptive center-based bias hypothesis to replace the most common image center-based center-bias. It calculates the weighted center by utilizing local contrast which is much more robust when the objects are far away from the image center. Second, we model smoothness term on saliency statistics of each color. It forces the pixels with similar colors to have similar saliency statistics. The proposed smoothness term is more robust than …

Large-Amplitude Mesospheric Response To An Orographic Wave Generated Over The Southern Ocean Auckland Islands (50.7°S) During The Deepwave Project, Pierre-Dominique Pautet, Michael J. Taylor, D. C. Fritts, K. Bossert, B. P. Williams, D. Broutman, J. Ma, S. D. Eckermann, J. D. Doyle

All Physics Faculty Publications

The Deep Propagating Gravity Wave Experiment (DEEPWAVE) project was conducted over New Zealand and the surrounding regions during June and July 2014, to more fully understand the generation, propagation, and effects of atmospheric gravity waves. A large suite of instruments collected data from the ground to the upper atmosphere (~100 km), with several new remote-sensing instruments operating on board the NSF Gulfstream V (GV) research aircraft, which was the central measurement platform of the project. On 14 July, during one of the research flights (research flight 23), a spectacular event was observed as the GV flew in the lee of …

Catalysis Of The Aza-Diels-Alder Reaction By Hydrogen And Halogen Bonds, Vincent De Paul Nzuwah-Nziko, Steve Scheiner

Chemistry and Biochemistry Faculty Publications

The combination of H2C=NH and cis-1,3-butadiene to form a six-membered ring was examined by quantum calculations. The energy barrier for this reaction is substantially lowered by the introduction of an imidazolium catalyst with either a H or halogen (X) atom in the 2-position, which acts via a H or halogen bond to the N atom of the imine, respectively. X=I has the largest effect, and Cl the smallest; Br and H are roughly equivalent. The catalyst retards the formation of the incipient N-C bond from imine to diene while simultaneously accelerating the C-C bond formation. The energy of the π* …

Degradation Effects Of Ionizing Radiation On Commercially Available Spacecraft Components, Alex Souvall

Senior Theses and Projects

No abstract provided.

Opinion: Why Protect Nature? Rethinking Values And The Environment, Kai M. A. Chan, Patricia Balvanera, Karina Benessaiah, Mollie Chapman, Sandra Díaz, Erik Gómez-Baggethun, Rachelle Gould, Neil Hannahs, Kurt Jax, Sarah Klain, Gary W. Luck, Berta Martin-Lopez, Barbara Muraca, Bryan Norton, Konrad Ott, Et Al.

Environment and Society Faculty Publications

A cornerstone of environmental policy is the debate over protecting nature for humans’ sake (instrumental values) or for nature’s (intrinsic values) (1). We propose that focusing only on instrumental or intrinsic values may fail to resonate with views on personal and collective well-being, or “what is right,” with regard to nature and the environment. Without complementary attention to other ways that value is expressed and realized by people, such a focus may inadvertently promote worldviews at odds with fair and desirable futures. It is time to engage seriously with a third class of values, one with diverse roots and current …