Digital Commons Network^™

Mapping Groundwater Discharge Along Lake Margins Using Satellite And Uav Thermal Imagery, Kelsey A. Forward

Theses and Dissertations

Effective watershed management decisions depend on understanding groundwater-surface water interactions. Traditional hydrogeological investigations are invasive, time-consuming, and expensive; therefore, regions that lack accessibility or agency funding need other ways of evaluating groundwater-lake interactions. Heat has long been known to be an effective groundwater tracer. Groundwater is insulated from most solar radiation, and its temperature does not fluctuate greatly from the annual average air temperature year-round in higher latitudes. In contrast, lakes are directly exposed to solar radiation, and water temperature fluctuates greatly both seasonally and diurnally. The winter and summer seasons produce the greatest contrast between groundwater and surface water …

Impact Of Wetlands Loss On The Long-Term Flood Risks Of Devils Lake In A Changing Climate, Sergey Gulbin

Theses and Dissertations

Endorheic (terminal) lakes with no water outlets are sensitive indicators of changes in climate and land cover in the watershed. Since 1990 Devils Lake watershed in North Dakota experienced a dramatic change of local climate: wet phase. This change yielded in a 10-m water level rise in just two decades. The Lake’s water level increase caused flooding of adjacent areas, including towns, agriculture fields and houses of Native Americans, costing over $1 billion in mitigation.

While the climate change contribution to flooding has been established, the role of large scale land conversion to agriculture has not been researched. The purpose …

Precipitation Of Synthetic Dolomite At Low Tempearures With The Influence Of Microbes, Sreeram Jambulapati

Theses and Dissertations

New approaches in carbonate geochemistry are aiding geoscientists in

understanding dolomite formation. Dolomite is largely absent in modern depositional

environments but is present in ancient rocks. The current problem is the inability to

synthesize it under low-temperature conditions in the laboratory. Until recently

laboratory preparation of dolomite required elevated temperatures (<100oC) to overcome

kinetic barriers. One novel approach involves using bacteria to overcome the kinetic

barriers that have frustrated efforts to synthesize dolomite at near surface temperatures.

This study presents preliminary results of experiments in which three strains of bacteria

were used to inoculate a magnesium deficient amorphous calcium carbonate (Mg-ACC)

medium …

Outgassing Of Out-Of-Autoclave Composite Primary Structures For Small Satellites, Alastair Komus

Theses and Dissertations

Out-of-autoclave vacuum-bagged-only (VBO) processing is capable of producing lower cost composite primary structures for small satellites than autoclave processing. However, the outgassing performance of VBO structures in a vacuum environment has not been examined. Panels were manufactured from CYCOM 5320-1 and TC275-1 carbon fiber/epoxy prepreg using VBO processing. The humidity level, pre-cure dwell time, and cure cycle parameters were varied during manufacturing. The degree of cure and glass transition temperature were shown to increase with increasing oven temperature. Processing humidity levels and the length of pre-cure dwell times had no discernable effect on the total mass loss (TML) and collected …

Sensitivity Of Cross-Tropopause Convective Transport To Tropopause Definition, Emily Maddox

Theses and Dissertations

An idealized three-dimensional cloud-resolving model is used to investigate the sensitivity of cross-tropopause convective mass transport to tropopause definition. A ten-hour simulation is conducted to encompass the growth and decay cycle, with focus on irreversible transport above the tropopause. Six previously published tropopause definitions are evaluated. These definitions include specific values of altitude, World Meteorological Organization (WMO) temperature lapse rate, potential vorticity, stratospheric tracer concentration, static stability, and curvature of the Brunt-Vaisala Frequency. This investigation highlights the challenge of defining a tropopause during active deep convection, and demonstrates the need of clearly communicating calculation methods and threshold choices in the …

Detailed Analysis Of Convective Simulations From A Wrf Microphysics Ensemble, Joshua Markel

Theses and Dissertations

This study performed a detailed analysis of convective storms across the Contiguous United States from 77 case dates using a 4-member microphysics Weather Research and Forecasting (WRF) ensemble and Stage IV gauge-adjusted radar derived precipitation. Dates included the 2016 NOAA Spring Forecast Experiment (SFE) with the remainder from 2010-2012. Quantitative attributes of precipitation objects in both simulations and observations were diagnosed using the Method of Object-Based Diagnostic Evaluation Time-Domain (MODE-TD). The microphysics schemes tested were WSM6, Thompson, Morrison, and Milbrandt.

Among all simulation case dates, compared to observations, the number of precipitation objects less than 90 km in length are …

Spacesuit Integrated Carbon Nanotube Dust Mitigation System For Lunar Exploration, Kavya Kamal Manyapu

Theses and Dissertations

Lunar dust proved to be troublesome during the Apollo missions. The lunar dust comprises of fine particles, with electric charges imparted by solar winds and ultraviolet radiation. As such, it adheres readily, and easily penetrates through smallest crevices into mechanisms. During Apollo missions, the powdery dust substantially degraded the performance of spacesuits by abrading suit fabric and clogging seals. Dust also degraded other critical equipment such as rovers, thermal control and optical surfaces, solar arrays, and was thus shown to be a major issue for surface operations. Even inside the lunar module, Apollo astronauts were exposed to this dust when …

Synthesis And Characterization Of Max Ceramics (Maxcers), Johnny Carl Nelson

Theses and Dissertations

This research has focused on the design and development of novel multifunctional MAX reinforced ceramics (MAXCERs). These MAXCERs were manufactured with 1-50 vol% ratios of ceramics to MAX phases. Chapter II reports on the synthesis and tribological behavior of Ti3SiC2 matrix composites by incorporating (1 and 6 vol%) Al2O3, (1 and 5 vol%) BN, and (1 and 5 vol%) B4C ceramic particulate additives in the matrix. All the composites were fabricated by pressureless sintering by using ~1 wt% Ni as a sintering agent at 1550 oC for 2 hours. SEM and XRD studies showed that Al2O3 is relatively inert in …

Failure Analysis Of Rotating Equipment Using Vibration Studies And Signal Processing Techniques, Ashkan Nejadpak

Theses and Dissertations

This thesis focuses on failure analysis of rotating machines based on vibration analysis and signal processing techniques. The main objectives are: identifying machine’s condition, determining the faults specific response, creating methods to correct the faults, and investigating available statistical analysis methods for automatic fault detection and classification. In vibration analysis, the accelerometer data is analyzed in time and frequency domain which will determine the machine’s condition by identifying the characteristic frequencies of the faults. These fault frequencies are specific for each type of machine’s faults. Therefore, they are referred to as faults’ signatures. The most common faults of the rotating …

Lightcurve Study Of V-Type Asteroids, Matt Nowinski

Theses and Dissertations

A massive impact event on (4) Vesta is believed to have created the Vesta family of asteroids (Asphaug, 1997). The rotational characteristics of the Vesta family provide important clues about this event, including its timing, the make-up of the resulting debris, the subsequent migration of members of the family into Earth-crossing orbits, and the deposition of the Howardite-Eucrite-Diogenite meteorites on the Earth’s surface. This study conducted lightcurve measurements of ten Vp-type asteroids, drawn from an asteroid taxonomy defined by Carvano et al. (2010) and based on the Sloan Digital Sky Survey (SDSS) Moving Object Catalogue (MOC4). These measurements identified a …

Optimal Control Of Induction Machines To Minimize Transient Energy Losses, Siby Jose Plathottam

Theses and Dissertations

Induction machines are electromechanical energy conversion devices comprised of a stator and a rotor. Torque is generated due to the interaction between the rotating magnetic field from the stator, and the current induced in the rotor conductors. Their speed and torque output can be precisely controlled by manipulating the magnitude, frequency, and phase of the three input sinusoidal voltage waveforms. Their ruggedness, low cost, and high efficiency have made them ubiquitous component of nearly every industrial application. Thus, even a small improvement in their energy efficient tend to give a large amount of electrical energy savings over the lifetime of …

An Investigation Of The Thermal Degradation Of Lignin, Sara Pourjafar

Theses and Dissertations

The goal of this research was to explore selected non-biological lignin decomposition reactions to determine if these reactions have the potential to generate fuel and chemical intermediates in a commercially feasible manner. Two different strategies were employed: 1) metal doped silica-alumina and γ-alumina catalytic decomposition reactions, and 2) base catalyzed sub- and supercritical water liquefaction.

The first strategy was built upon previous research to explore metal doped silica-alumina and γ-alumina catalytic lignin decomposition reactions in a batch reactor system. Commercially available silica-alumina and γ-alumina catalysts were individually doped with 5 and 10 wt % of molybdenum or copper via a …

Design And Manufacture Of A Negative Index Metamaterial Using A Magnetized Photonic Crystal, Mohamed Zein Radwan

Theses and Dissertations

Negative index materials (NIM) are artificial structures in which the refractive index for light has a negative value over some frequency range. This does not occur in any known natural materials, and thus is only achievable with engineered structures known as metamaterials. Metamaterials demonstrating a negative refractive index for light usually consist of arrays of wires and cut-ring structures: such media are characterized by both the electrical permittivity and magnetic permeability being negative. My method for obtaining a NIM is different from previous attempts. I get the negative magnetic permeability from a ferrite material which is the host medium for …

Modeling The Interactions Between Turbulence And Radiation In Oxy-Combustion Flames, Md Ashiqur Rahman

Theses and Dissertations

In order to accurately estimate radiative heat transfer in turbulent combustion systems, one needs to take into account the non-linear interactions between the temporally fluctuating species and temperature variables and the radiation field. Simply employing time-averaged values of these variables in the radiation calculations to estimate absorption and emission (as is commonly done in the modeling community) can result in gross errors in the estimation of the radiative fluxes. Therefore, models that account for these Turbulence-Radiation Interactions (TRI) have been proposed in the literature to improve the fidelity of the radiative transfer calculations. TRI models accomplish this by computing appropriate …

Effects Of Non-Conventional Gas And Oil Production Activities On Local And Regional Fine Particles And Ground-Level Ozone, Swetha Mallula

Theses and Dissertations

Unconventional oil and gas production in North Dakota and Texas has been rising significantly since 2007 with the advances in hydraulic fracturing technology. The effects of unconventional oil and gas production on the environmental quality and public health, however, are not well understood. The goal of this study was to investigate the effects of unconventional energy production on two types of air pollutants (fine particles and ground-level ozone). We analyzed the air quality data from publicly accessible sources, focusing on two major oil producing states (North Dakota, Texas) and two control states (Minnesota and Connecticut). The specific objectives of this …

Enhanced Optical Wireless Channel For Indoor And Intravehicle Communications: Power Distribution And Signal To Noise Ratio Analysis, Rana Rageh Shaaban

Theses and Dissertations

Visible light communication—(VLC) provides wide bandwidth and high security

capabilities for free space optical communication. This thesis presents the key concepts,

underlying principles and practical applications of visible light communications. In

particular, this thesis focuses on the received power distribution pattern and signal to noise

ratio for line-of-sight indoor and vehicular applications. Several methods are used to

modify the SNR and power distribution levels. It is shown that in the absence of

obstruction, the optical footprint is nearly circular and offers a platform for large- scale

deployment in commercial environments, which is similar to micro and Pico cells.

By studying …

Outcrop Mapping Using Unmanned Aerial Systems And Modeling Of The Shannon Sandstone In The Powder River Basin, Emily Grace Sundell

Theses and Dissertations

Mapping steep outcrops by hand is dangerous, time consuming and gathering images parallel to a cliff face is difficult to nearly impossible. Wyoming has many extensive, steep, surface outcrops that in the subsurface are petroleum-producing formations. The Powder River Basin (PRB) of Wyoming has been a prolific producer of petroleum since the late 1800s, and with continual advances in technology production continues to increase. During the Cretaceous, the PRB was inundated by the Western Interior Seaway. Sand-clay sequences corresponding to transgressions and regressions were deposited and resulted in the Campanian Shannon Member of the Cody Formation. The Shannon Member thickens …

Performance Analysis Of Automatic Dependent Surveillance-Broadcast (Ads-B) And Breakdown Of Anomalies, Asma Tabassum

Theses and Dissertations

This thesis work analyzes the performance of Automatic Dependent Surveillance-Broadcast (ADS-B) data received from Grand Forks International Airport, detects anomalies in the data and quantifies the associated potential risk. This work also assesses severity associated anomalous data in Detect and Avoid (DAA) for Unmanned Aircraft System (UAS). The received data were raw and archived in GDL-90 format. A python module is developed to parse the raw data into readable data in a .csv file. The anomaly detection algorithm is based on Federal Aviation Administration's (FAA) ADS-B performance assessment report. An extensive study is carried out on two main types of …

A Survey Measuring The Efficacy Of Duty And Rest Guidelines In Business Aviation Operations, Timothy Wollmuth

Theses and Dissertations

Despite improved understanding of fatigue, reduced cognitive ability continues to contribute to aviation accidents (Drury, Ferguson, & Thomas, 2012; Noy et al., 2011). A comprehensive fatigue study on business aviation (BA) operations in the US has not been published since "Crew Factors in Flight Operations XIII: A Survey of Fatigue Factors in Corporate/Executive Aviation Operations" (Rosekind, Co, Gregory, & Miller, 2000). This study, modeled after the Rosekind survey and conducted in collaboration with the National Business Aviation Association (NBAA), updated the baseline for fatigue in BA, qualitatively examined fatigue perceptions in BA, and examined the efficacy of the “Flight Safety …

Study Of Pore-Dependent Petroleum Fluid Properties In Tight Shale Plays: Bakken Formation, Agustinus Zandy

Theses and Dissertations

In 2013, the United States Geological Survey (USGS) released an estimate of 7.38 billion barrels of oil held within the Bakken Formation, one of the most significant discoveries. However, the Bakken Formation, a tight shale play, is also known for its ultra-low permeability and nano-scale pore size (1 – 100 nm). A nano-scale pore size can impact the petroleum fluid properties when compared to its bulk properties. This study utilized a theory-based analytical method and compares the results with those from experiments conducted under the simulated conditions.

Peng-Robinson Equation of State (PR-EOS) was modified to calculate the critical properties of …

A Radioelement Analysis Of The Northern Black Hills, South Dakota, U.S.A., Dylan Wade Young

Theses and Dissertations

The uranium, thorium, and potassium contents from 736 samples, within a 15-km radius of the Homestake Gold Mine and Sanford Underground Research Facility in the Northern Black Hills indicate the geoneutrino background may be higher than average for the continental crust. The radioactive element contents of igneous, metamorphic, and sedimentary rocks were determined by gamma ray spectrometry. Many rocks show hydrothermal and metamorphic alteration within the last ten Ma of the Tertiary period. Young alkali rich igneous rocks, such as rhyolite, phonolite and other volcanic rocks, have lower than average Th:U ratios. The radioelement content of 215 igneous rocks were …

A Study Of Scattering From Snow Embedded With Non-Spherical Shapes Of Scatterers With Relaxed Hierarchical Equivalent Source Algorithm (Rhesa), Chan Fai Lum, Fu Xin, Hong Tat Ewe, Li (Lijun) Jun Jiang

Electrical and Computer Engineering Faculty Research & Creative Works

Remote sensing has been used widely in studying the earth terrain such as snow or sea ice due to its fast, convenient and long-term monitoring capabilities. SAR images acquired could be used to analyze the condition of snow, snow water equivalent (SWE), surface roughness and others. Theoretical models have also been developed to understand how microwave interacts with the snow medium and the scatterers embedded inside the medium. Conventionally, spherical shape of scatterers is commonly used to represent the ice particles embedded inside snow where the actual shape of scatterers can vary. This paper is to present a theoretical model …

Decentralized Fault Diagnosis And Prognosis Scheme For Interconnected Nonlinear Discrete-Time Systems, Hasan Ferdowsi, Jagannathan Sarangapani

Electrical and Computer Engineering Faculty Research & Creative Works

This paper deals with the design of a decentralized fault diagnosis and prognosis scheme for interconnected nonlinear discrete-time systems which are modelled as the interconnection of several subsystems. For each subsystem, a local fault detector (LFD) is designed based on the dynamic model of the local subsystem and the local states. Each LFD consists of an observer with an online neural network (NN)-based approximator. The online NN approximators only use local measurements as their inputs, and are always turned on and continuously learn the interconnection as well as possible fault function. A fault is detected by comparing the output of …

Vehicle Base Station, Emad William Saad, J. L. Vian, Matthew A. Vavrina, J. A. Nisbett, Donald C. Wunsch

Electrical and Computer Engineering Faculty Research & Creative Works

A system to load and unload material from a vehicle comprises a vehicle base station and an assembly to autonomously load and unload material from the vehicle.

The State Of The Region: Hampton Roads 2017, James V. Koch, Robert Mcnab, Vinod Agarwal, Barbara Blake-Gonzalez, Kelly Brown, Chris Colburn, Vicky Curtis, Steve Daniel, Chip Filer, Elizabeth Janik, Timothy M. Komarek, Lead Hampton Roads Class Of 2017, Feng Lian, Sharon Lomax, Janet Molinaro, Ziniya Zahedi

Economics Faculty Books

This is Old Dominion University's 18th annual State of the Region report. While it represents the work of many people connected in various ways to the university, the report does not constitute an official viewpoint of Old Dominion, or its president, John R. Broderick. The report maintains the goal of stimulating thought and discussion that ultimately will make Hampton Roads an even better place to live. We are proud of our regions many successes, but realize that it is possible to improve our performance. In order to do so, we must have accurate information about "where we are" and a …

A Collimated Surface-Wave-Excited High-Impedance Surface Leaky-Wave Antenna, Zi Long Ma, Chi Hou Chan, Kung Bo Ng, Li (Lijun) Jun Jiang

Electrical and Computer Engineering Faculty Research & Creative Works

This letter presents a novel high-impedance surface (HIS)-based leaky-wave antenna excited by collimated surface wave (SW). The proposed antenna consists of two identical SW launchers (SWLs) and an HIS structure. Regarding the SWL, it is based on an offset-fed parabolic reflector. By using the substrate-integrated waveguide technique, the reflector system is integrated in the planar substrate. For the HIS, it is formed by a periodically arranged rectangular microstrip patch array. The proposed SWL can generate collimated SW with the propagation mode. With the perturbation of the HIS, the guided SW can be transformed to m = -1 space-harmonic-mode leaky wave. …

Low Frequency Behavior Of Cvd Graphene From Dc To 40 Ghz, Rong Wang, Salahuddin Raju, Mansun Chan, Li (Lijun) Jun Jiang

Electrical and Computer Engineering Faculty Research & Creative Works

Electromagnetic behaviour of chemical vapor deposition (CVD) graphene at low frequencies is still a mystery. No conclusion is made from the experimental point of views. We systematically investigate the electromagnetic response of graphene at microwave frequencies, which are from direct current (DC) to 40 GHz. Both a coplanar transmission line embedded with different-sized graphene flakes of 48 x 48 and 48 x 240 μm2 and a microwave termination based on the graphene sheet of 6 x 6mm2 are manufactured through standard microfabrication procedures. We conclude that CVD graphene behaves as a frequency-independent surface resistance at the microwave frequencies, which is …

The Error Control Of Mixed-Form Fast Multipole Algorithm Based On The High-Order Multipole Rotation, Ling Ling Meng, Xiaoyan Y.Z. Xiong, Tian Xia, Li (Lijun) Jun Jiang

Electrical and Computer Engineering Faculty Research & Creative Works

In this letter, the mixed-form fast multipole algorithm (MF-FMA) with feasible error controllability is implemented through high-order multipole rotation that can make the translation matrices very sparse. The saving of both storage and CPU time makes it attainable to increase the number of harmonics in the middle frequency regime, thus shifting up the transition region of MF-FMA. Consequently, the broadband accuracy of the MF-FMA can be improved significantly.

Volterra Series-Based Time-Domain Macromodeling Of Nonlinear Circuits, Xiaoyan Y.Z. Xiong, Li (Lijun) Jun Jiang, Jose E. Schutt-Aine, Weng Cho Chew

Electrical and Computer Engineering Faculty Research & Creative Works

Volterra series (VS) representation is a powerful mathematical model for nonlinear circuits. However, the difficulties in determining higher order Volterra kernels limited its broader applications. In this paper, a systematic approach that enables a convenient extraction of Volterra kernels from X-parameters is presented. A concise and general representation of the output response due to arbitrary number of input tones is given. The relationship between Volterra kernels and X-parameters is explicitly formulated. An efficient frequency sweep scheme and an output frequency indexing scheme are provided. The least square linear regression method is employed to separate different orders of Volterra kernels at …

City On A Hill: The Democratic Promise Of Higher Education, Rachel F. Moran

Faculty Scholarship

When we think about the democratic promise of higher education, we often think of public universities. Consider, for example, the civic-minded reflections of Gordon Davies, the former Chancellor of the University of Virginia, who concluded in 1997 that “[e]ducation is not a trivial business, a private good, or a discretionary expenditure. It is a deeply ethical undertaking at which we must succeed if we are to survive as a free people.” This lofty vision has since been undermined by persistent cuts in funding for state universities across the nation. In 2007, James Duderstadt, the former president of the University of …