Open Access. Powered by Scholars. Published by Universities.®
- Keyword
-
- Space plasmas (2)
- 30-seconds-chair-stand (1)
- Acoustics (1)
- Aerodynamics (1)
- Agricultural systems--Mathematical models (1)
-
- Airplanes--Wings (1)
- Algal biofuels (1)
- Amorphous silicon (1)
- Animal flight (1)
- Anoxemia (1)
- Anti-Censorship (1)
- Antifungal (1)
- Astronomy (1)
- Astrophysics (1)
- Automated Test Generation (1)
- Automated detection (1)
- Autonomous Vehicle (1)
- Bio mechanical model (1)
- Biofuel (1)
- Biomass energy (1)
- Biotechnology (1)
- Bubbly Flows (1)
- Cancer (1)
- Cancer cells (1)
- Cell (1)
- Chandra x-ray observatory (US) (1)
- Chemical kinetics (1)
- Color in visual communication (1)
- Combustion chambers--Mathematical models (1)
- Combustion instabilities (1)
Articles 1 - 25 of 25
Full-Text Articles in Entire DC Network
Determining Relationships Between Organizational Unit Functioning (Teams And Working Groups) And Unit Performance In Government Scientific And Engineering Organizations, David A. Clark Pe
Determining Relationships Between Organizational Unit Functioning (Teams And Working Groups) And Unit Performance In Government Scientific And Engineering Organizations, David A. Clark Pe
Dissertations
For more than sixty years, following the extraordinary scientific and engineering accomplishments achieved during World War II, organizational unit research has been at the forefront of organizational research. What was once referred to as teams of scientists or engineers that delivered the atomic bomb, nuclear power, jet engines, space exploration, micro-computers, cellular communications and the internet has led to the modern incarnation of what are referred to as teams or working groups. The objective of this research was to investigate relationships between organizational functioning (teams and working groups) and organizational unit performance. To investigate these potential relationships, organizational functioning and …
Analytical Investigation Of Thermoacoustic Instabilities In Premixed Combustion Systems, Vijaya Krishna Rani
Analytical Investigation Of Thermoacoustic Instabilities In Premixed Combustion Systems, Vijaya Krishna Rani
Dissertations
The primary objective of this dissertation is to develop and investigate various analytical methods to predict thermoacoustic instabilities in premixed combustion systems. The analytical models derived as part of this study are of four main types: (1) Acoustically consistent, linear modal analysis method to predict the longitudinal and transverse combustion instabilities in a dump combustor; (2) Novel level set method for deriving flame surface-area response to incident acoustic fluctuations; (3) Novel approximate analytical solutions to acoustic waves in inhomogeneous media; and (4) Investigation of the limit-cycle behavior of nonlinear acoustic wave equation with combustion source term. The linear modal analysis …
Efficient Opencl-Based Particle-In-Cell Simulation Of Auroral Plasma Phenomena Within A Commodity Spatially Reconfigurable Computing Environment, Abedalmuhdi M. Almomany
Efficient Opencl-Based Particle-In-Cell Simulation Of Auroral Plasma Phenomena Within A Commodity Spatially Reconfigurable Computing Environment, Abedalmuhdi M. Almomany
Dissertations
The primary focus of this research has been to expand and validate a framework through which Field Programmable Gate Array (FPGA) technology can be effectively utilized to reduce both the execution time and the energy consumption attributes of Particle-in-Cell (PIC) based simulations of space plasmas as compared to traditional single-core central processing unit-based implementations. This framework utilizes the OpenCL standard in a manner that allows the physical model to be captured at a high level of abstraction and allows the FPGA synthesis/compilation tool to exploit a combination of task and data parallelism. This research introduces an optimized implementation of the …
A Phase Rule Approach To Critical Point Phenomena In Chemically Reacting Systems, Joshua R. Lang
A Phase Rule Approach To Critical Point Phenomena In Chemically Reacting Systems, Joshua R. Lang
Dissertations
The critical phenomena that is exhibited in single component systems such as the ferromagnet and the pure fluid have been shown to have analogs in certain multicomponent, chemically reacting mixtures. These phenomena present in both equilibrium and kinetics. By employing a version of the Gibbs phase rule that has been modified to account for chemical reactions, we provide a basis for classifying the critical effects observed in these multicomponent systems. We also show the predictive power of this classification system by comparison with experimental results.
Studies Of Effective Color Combinations In Visualization, Sussan Einakian
Studies Of Effective Color Combinations In Visualization, Sussan Einakian
Dissertations
No abstract provided.
Gradient Coverslip (Gcvsl) : A Novel Way To Culture Cells Under Hypoxia, Brenda Smith Wright
Gradient Coverslip (Gcvsl) : A Novel Way To Culture Cells Under Hypoxia, Brenda Smith Wright
Dissertations
Solid tumors can have areas of hypoxia. Hypoxia is associated with changes in tumor cell metabolism, with radiation therapy resistance, with chemotherapy resistance, and with tumor aggressiveness. Yet most cell culture research and drug studies are based on cell lines grown in atmospheric oxygen (normoxia). Our hypothesis was that differences in protein levels, differences in mitochondrial morphology, and differences in killing of cells by drug compounds in normoxic and hypoxic conditions would be observed. Normoxic conditions were achieved by culturing cell lines in humidified incubators supplemented with 5% CO2. Hypoxic conditions were achieved by culturing cells in a culture chamber, …
Site Specific Isotopic Labeling Of Phenylalanine And Tyrosine : Application To Pth1, Bhargavi Ramaraju
Site Specific Isotopic Labeling Of Phenylalanine And Tyrosine : Application To Pth1, Bhargavi Ramaraju
Dissertations
Structural insight into biological macromolecules furthers understanding of function and provides a variety of information about cellular processes. Though NMR spectroscopy can be utilized to provide such insight, limitations, including size, are significant barriers. Site specific isotope labeling can be used to provide information on a variety of systems including large, slow tumbling systems and membrane proteins that are not amenable to study by traditional means. In effect, site specific isotope labeling increases the size barrier and thereby number of macromolecular systems able to be studied by NMR spectroscopy. Methyl labeling has been established as a leading method for site …
Synthesis Of Amphiphilic Pegylated Poly([Alpha]-Amino Acid) Tercopolymers And The Impact Of Molecular Architecture On Their Use As Gene And Drug Delivery Vectors, David J. Ulkoski
Synthesis Of Amphiphilic Pegylated Poly([Alpha]-Amino Acid) Tercopolymers And The Impact Of Molecular Architecture On Their Use As Gene And Drug Delivery Vectors, David J. Ulkoski
Dissertations
Poly(α-amino acid)s (PAAs) are a diverse class of polymers that can be synthesized or biologically derived. PAAs have been widely used for biomedical applications due to their biodegradability and biocompatibility. Living polymerization through ring opening polymerization of amino acid N-carboxyanhydrides using a nucleophilic initiator provides the potential to manipulate polymer architecture and physiochemical characteristics. In this study, we investigate the use of amphiphilic block and random PAA tercopolymer constructs that contain ionic and hydrophobic components. The amphiphilic character for each tercopolymer allows for the formation nanoparticles that can be used in gene and drug delivery. Each tercopolymer component provides a …
The Effect Of Personality Traits On Goal Orientation And Its Implication On Training And Development Of Scientists And Engineers, John D. Braswell
The Effect Of Personality Traits On Goal Orientation And Its Implication On Training And Development Of Scientists And Engineers, John D. Braswell
Dissertations
A key aspect of the engineering manager’s job is employee development. Research has shown that an individual’s goal orientation plays an important role in the development of occupational expertise development. This research examines the effects of personality traits on goal orientation and the implication on workforce training for engineers and scientists. A survey instrument was compiled based on a set of personality traits that have been hypothesized to relate to goal orientation. The survey was distributed in a federally-funded research and development laboratory in the aviation and aerospace industry. A total of 294 completed responses were received. Structural equation modeling …
Discrete Time Structured Models And Their Dynamics For Interactive Wild And Sterile Mosquitoes And Malaria Transmissions, Yang Li
Dissertations
Mosquito-borne diseases, including malaria, transmitted between human beings by blood-feeding mosquitoes, have been big concerns for the public health. No vaccines are available. An effective way to prevent such diseases is to control the amount of mosquitoes. The Sterile Insect Technique (SIT) is indeed a method of biological control. Mathematical models have proven useful in gaining insights into challenging questions in population dynamics and epidemiology. The objectives in this dissertation is to formulate new models for interactive wild and sterile mosquitoes so that the dynamics are relatively simpler and mathematically more tractable, but the fundamental model features are snatched. Instead …
Searching For Prompt Gamma Ray Signals Around Gravitational Wave Triggers, Eric Burns
Searching For Prompt Gamma Ray Signals Around Gravitational Wave Triggers, Eric Burns
Dissertations
One of the next great discoveries in astrophysics will be the first detection of an event in both gravitational waves and photons. I investigate the most promising event for a joint detection: the merging of a neutron star with another neutron star or a black hole, thought to produce short gamma ray bursts. We investigate the possibility of sub-populations of short gamma-ray bursts by comparing the bursts observed by the Swift Burst Alert Telescope and the Fermi Gamma-ray Burst Monitor. We find no evidence that these instruments are observing different short gamma-ray bursts, allowing us to use the Swift redshift …
Novel Antifungal Properties Of High Mannose Binding Lectins With Particular Emphasis On Scytovirin And Cryptococcus, Tyler Hays Jones
Novel Antifungal Properties Of High Mannose Binding Lectins With Particular Emphasis On Scytovirin And Cryptococcus, Tyler Hays Jones
Dissertations
Fungal pathogens represent a growing concern in human health, and the advancement of new therapeutic options is essential. The encapsulated basidiomycotic yeast Cryptococcus causes severe meningoencephalitis and cryptococcosis results in over 600,000 deaths a year. The prevalence of cryptococcal infection is increasing, driving the need for new and improved treatments. Scytovirin is a high mannose binding lectin from the cyanobacterium Scytonema varium. Originally pursued as an antiviral, herein is reported novel antifungal activity with detailed characterization of activity against Cryptococcus. Scytovirin specifically binds Man4, the D3 arm of Man9, a carbohydrate moiety found on cryptococcal glycoproteins. Localization of Scytovirin in …
Multi-Resolution Data Structures For Spherically Mapped Point Data, Robert William Youngren
Multi-Resolution Data Structures For Spherically Mapped Point Data, Robert William Youngren
Dissertations
Data describing entities or objects whose locations may be treated as points on the surface of a sphere are said to be spherically mapped. A number of data structures specifically designed to store and access spherically mapped data have been developed. One of them, Hierarchical Equal Area iso-Latitude Pixelization (HEALPix), has been successfully used for numerous applications, notably including organizing and analyzing cosmic microwave background data. However, for applications involving relatively sparse spherically mapped point datasets, HEALPix has some drawbacks, including inefficient memory requirements due to fixed resolution, overwriting of data for closely proximate points, and return of spurious points …
A Model Based Framework For Mobility Assessment Of Older Adults Using Wearable Systems, Priyanka Madhushri
A Model Based Framework For Mobility Assessment Of Older Adults Using Wearable Systems, Priyanka Madhushri
Dissertations
Assessment of mobility in older adults is important for early detection and prevention of falls. The Timed Up and Go (TUG) and the 30 Second Chair Stand (30SCS) tests are recom-mended and routinely used for assessing overall mobility, but they provide a single parameter to quantify mobility. These tests are still subjective and prone to errors. Therefore, we need cost effective new diagnostic procedures that provide more detailed assessment parameters related to fall risks. Modern smartphones enable the development of new mobile health (mHealth) appli-cations by integrating inertial and environmental sensors along with the increasing data pro-cessing and communication capabilities. …
Difference Frequency Response Of A Small Scattering Object Under Dual Frequency Millimeter Wave Illumination, Robert A. Smith
Difference Frequency Response Of A Small Scattering Object Under Dual Frequency Millimeter Wave Illumination, Robert A. Smith
Dissertations
The nonlinear response of electromagnetically illuminated objects has been an area of interest for communication systems and remote sensing techniques. Previous work focused on generation of second and higher order harmonics under single frequency excitation for the effects on interference to communication systems. Limited analysis and experiments looked at multiple frequency excitations for utilization in remote sensing applications. The analyses modeled the nonlinear feature of the scattering object as a simple diode component under normal operating conditions. The analytical results were consistent with harmonic and intermodulation product techniques under assumptions utilized in the analyses. All of these studies and experiments …
Vertex-Based Distinguishing Collections, J. Louis Sewell
Vertex-Based Distinguishing Collections, J. Louis Sewell
Dissertations
This work introduces vertex-based distinguishing collections that generalize locating-dominating sets and other well-studied sets related to sensor placement in a graph. A graph is an ordered pair G = (V, E), where V is an arbitrary set and E is a set of unordered pairs of elements of V. Graphical sensor placement problems are concerned with selecting or recognizing a subset of vertices X ⊆ V such that X has certain sensing or location-distinguishing properties. For example, a locating-dominating set of G is a set of vertices X ⊆ V such that: every vertex not in X shares an edge …
The Effects Of Wing Flexibility On The Flight Performance And Stability Of Flapping Wing Micro Air Vehicles, James Edward Bluman
The Effects Of Wing Flexibility On The Flight Performance And Stability Of Flapping Wing Micro Air Vehicles, James Edward Bluman
Dissertations
Insect wings are flexible. However, the influence of wing flexibility on the flight dynamics of insects and flapping wing micro air vehicles is unknown. Most studies in the literature consider rigid wings and conclude that the hover equilibrium is unstable. This dissertation shows that a flapping wing flyer with flexible wings exhibits stable natural modes of the open loop system in hover, never reported before. The free-flight insect flight dynamics is modeled for both flexible and rigid wings. Wing mass and inertia are included in the nonlinear equations of motion. The flapping wing aerodynamics are modeled using a quasi-steady model, …
Quantum Dot Photoluminescent Dynamics And Exciton-Plasmon Coupling In The Presence Of Dielectrics, Metal Oxides, And Metallic Nanoparticles, Waylin J. Wing
Quantum Dot Photoluminescent Dynamics And Exciton-Plasmon Coupling In The Presence Of Dielectrics, Metal Oxides, And Metallic Nanoparticles, Waylin J. Wing
Dissertations
Nanomaterials such as quantum dots (QDs) and metallic nanoparticles (MNPs) play an important role in physics and engineering, especially for applications such as next-generation display devices or computer processors. When used simultaneously, QDs and MNPs can couple together through a mechanism called exciton-plasmon coupling. This dipole-dipole coupling yields increased control over the optical properties of the combined system, such as enhanced emission, polarization selectively, and directionality of light. In this dissertation, a new method by which to increase the strength of exciton-plasmon coupling is presented which can boost the emission efficiency of QDs beyond the currently known plasmonic channels. This …
Observational Analysis Of Transient And Coherent Structures In Space Plasmas, Jinlei Zheng
Observational Analysis Of Transient And Coherent Structures In Space Plasmas, Jinlei Zheng
Dissertations
In this dissertation, we developed a new automated small-scale magnetic flux rope detection algorithm based on the Grad-Shafranov (GS) reconstruction technique. The GS reconstruction technique is a tool to reconstruct the two and a half dimensional magnetic field and plasma structures based on in-situ spacecraft measurements in space plasmas. We applied this detection algorithm to the Wind spacecraft measurements during 1996 ~ 2016, covering two solar cycles, and successfully detected a total number of 74,241 small-scale magnetic flux rope events with durations from 9 to 361 minutes. This large number of small-scale magnetic flux ropes has not been discovered by …
Shocking Features In Merging Galaxy Clusters, Sarthak Dasadia
Shocking Features In Merging Galaxy Clusters, Sarthak Dasadia
Dissertations
Shocks are the most important sources of heating in galaxy clusters. Despite their rarity, they have been studied extensively on individual scales. However, a systematic sample study is necessary to recognize any general pattern in merger shocks. With this goal, we constructed a Sample of Chandra ClustErs with Robust Shocks (SoCCERS) to study shock properties, the related merger phenomena, and particle acceleration. The sample includes 16 galaxy clusters where shocks are robustly detected with the Chandra X-ray data, from the surface brightness jumps and the changes on thermodynamic properties. The sample can be further divided into two categories: with or …
Search-Based Automated Robustness Testing Of Autonomous Vehicle Control Software, Kevin Michael Betts
Search-Based Automated Robustness Testing Of Autonomous Vehicle Control Software, Kevin Michael Betts
Dissertations
Autonomous systems must successfully operate in complex time-varying spatial environments even when dealing with system faults that may occur during a mission. Consequently, evaluating the robustness, or ability to operate correctly under unexpected conditions, of autonomous vehicle control software is an increasingly important issue in software testing. New methods to automatically generate test cases for robustness testing of autonomous vehicle control software in closed-loop simulation are needed. Search-based testing techniques were used to automatically generate test cases, consisting of initial conditions and fault occurrence times, intended to challenge the control software more than test cases generated using current methods. Two …
Assimilation Of Coupled Microwave/Thermal Infrared Soil Moisture Profiles Into A Crop Modeling System, Vikalp Mishra
Assimilation Of Coupled Microwave/Thermal Infrared Soil Moisture Profiles Into A Crop Modeling System, Vikalp Mishra
Dissertations
The main focus of this study is to utilize Microwave (MW) and Thermal Infrared (TIR) based satellite derived soil moisture (SM) estimates within a robust, state-of-the-art crop model for obtaining gridded, high spatio-temporal estimates of crop yield and water stress, particularly during drought conditions. The study is unique in many aspects: primarily, it integrates MW and TIR based techniques to provide SM estimation from the surface (0-5 cm) downward to the rooting depth (2 m); further, for the first time, the Principle of Maximum Entropy (POME)-derived SM profiles were developed to drive a gridded crop model. This study allowed us …
Moving Target Defense Based On Mobile Ipv6, Vahid Heydari
Moving Target Defense Based On Mobile Ipv6, Vahid Heydari
Dissertations
Remote cyber attacks can be started from unlimited distance. These remote attacks include special actions which allow attackers to compromise remote systems. During the first step of attacks, reconnaissance step, attackers attempt to gather information about their intended target(s). For network-based systems, figuring out the IP address(es) of the target(s) is critical to the success of the attack. The use of static IP addresses leaves the target vulnerable in two ways. First, they are discoverable. Second, after accessing the target, the attacker can maintain this access for a long time. So an effective defense is a mechanism to change the …
Novel Methods In Harvest Of Microalgae And Extraction Of Lipids From Dilute Microalgal Suspension For Biofuel, Chen Zhang
Dissertations
A method of using organic solvent (hexane, 1-butanol, ethyl acetate) to harvest freshwater microalgae Nannochloropsis sp. by tuning microalgal cell surface hydrophobicity with low pH was reported. Harvesting experiments were performed with culture suspension of 60 mL with biomass concentration of 0.35 g/L and 0.85 g/L. Due to cell surface hydrophobicity, microalgal cells attach to the organic solvent and water interphase after separation. Suspension pH of 3 resulted in the highest harvesting efficiency (92-99%) depending on the organic solvent with processing time of 3 min. This method is efficient, cost-effective and eco-friendly as the supernatant can be reused as growth …
A Numerical Investigation Of Heat Transfer And Fluid Structures In The Wake Of A Single Confined Bubble, John R. Willard
A Numerical Investigation Of Heat Transfer And Fluid Structures In The Wake Of A Single Confined Bubble, John R. Willard
Dissertations
Presented here is a numerical investigation of a single highly confined bubble moving through a millimeter scale channel without phase change. The underlying flow is laminar and is driven by a pressure gradient, characteristic of a horizontal channel flow. The bubble is confined in the vertical direction, between a heated upper plate and a lower adiabatic surface. The simulation is accomplished in ANSYS Fluent using the Volume of Fluid method to determine the phase boundary. A Lagrangian formulation of the numerical domain is used to simulate a channel of arbitrary length. The dimensions of the channel are 1.25mm in the …