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Articles 1 - 30 of 35
Full-Text Articles in Engineering
Implementation Of A Software Defined Spread Spectrum Communication System, Mir Ali
Implementation Of A Software Defined Spread Spectrum Communication System, Mir Ali
Electronic Theses and Dissertations
The goal of this thesis is to develop a framework to prototype a software defined direct sequence spread spectrum transceiver that can be used as a node in an ad hoc network. We introduce the concept of a software radio, the current state of art, and GNU Radio and its concepts. We discuss in detail the design and development methods of GNU Radio and develop a flowgraph in Python to demonstrate the method of development. We present a mathematical analysis of (DSSS) modulation and demodulation schemes along with the transmitter and receiver design. We use this design to develop an …
Accelerating The Performance Of A Novel Meshless Method Based On Collocation With Radial Basis Functions By Employing A Graphical Processing Unit As A Parallel Coprocessor, Derek Owusu-Banson
Accelerating The Performance Of A Novel Meshless Method Based On Collocation With Radial Basis Functions By Employing A Graphical Processing Unit As A Parallel Coprocessor, Derek Owusu-Banson
Electronic Theses and Dissertations
In recent times, a variety of industries, applications and numerical methods including the meshless method have enjoyed a great deal of success by utilizing the graphical processing unit (GPU) as a parallel coprocessor. These benefits often include performance improvement over the previous implementations. Furthermore, applications running on graphics processors enjoy superior performance per dollar and performance per watt than implementations built exclusively on traditional central processing technologies. The GPU was originally designed for graphics acceleration but the modern GPU, known as the General Purpose Graphical Processing Unit (GPGPU) can be used for scientific and engineering calculations. The GPGPU consists of …
Artificial Impedance Surfaces And Wire Media For Absorption And Cloaking, Yashwanth Reddy Padooru
Artificial Impedance Surfaces And Wire Media For Absorption And Cloaking, Yashwanth Reddy Padooru
Electronic Theses and Dissertations
The main objective of this dissertation is to investigate the ability of utilizing artificial impedance surfaces and wire media for absorption and cloaking applications. The dissertation includes two parts which focus on the electromagnetic wave propagation in absorbers formed by stacked metasurfaces and structured wire media, and electromagnetic wave interaction with the cylindrical cloaking structures. In the first part, we propose a variety of physical systems that show multiband and wideband absorption properties in the microwave regime. For the multiband absorbers, we propose a simple analytical model to study the absorption properties. Further, using the same circuit model, the physical …
Characterizing The Acoustic Properties Of The Jet Lab At The National Center For Physical Acoustics, Joshua Anderson Lieblong
Characterizing The Acoustic Properties Of The Jet Lab At The National Center For Physical Acoustics, Joshua Anderson Lieblong
Electronic Theses and Dissertations
Aerodynamic noise has been a problem since the first use of the jet engine for military aircraft in World War II. For further uses of the jet engine to be possible, problems due to jet noise must be researched and addressed. Anechoic chambers were proposed as a testing facility for research in aerodynamic noise because of their supposed free-field characteristics. The international standard ISO 3745-1977 was introduced to determine whether the facilities could be considered anechoic, semi-anechoic, or neither. An experiment was designed to determine at what frequencies the National Center for Physical Acoustics' Jet Lab Facility is non-anechoic, semi-anechoic, …
Admicellar Polymerization Of Calcium Carbonate And Its Performance In Drilling Fluids, Poh Lee Cheah
Admicellar Polymerization Of Calcium Carbonate And Its Performance In Drilling Fluids, Poh Lee Cheah
Electronic Theses and Dissertations
Admicellar polymerization using sodium dodecylsulfate (SDS) template to form ultrafilm polystyrene on commercial calcium carbonate (CaCO3 ) of various particle sizes was studied. Adsorption isotherms of SDS decrease after the critical micelle concentration (CMC) of SDS was observed. This is explained by the phase behavior of SDS with calcium ion. The solubility product constants (Ksp) for calcium dodecylsulfate (Ca(DS) 2) were calculated as 1.55x10?9M3 at 30°C and 8.58x10?9M3 at 50°C. At SDS concentrations above the CMC, precipitation of Ca(DS)2 was governed by the critical ratio of calcium ion concentration bound onto anionic micelles which was 0.22 at 30°C and 0.20 …
Thermal And Photochemical Interaction Of Co2 With Biochar, Eneruvie Uyoyou Okinedo
Thermal And Photochemical Interaction Of Co2 With Biochar, Eneruvie Uyoyou Okinedo
Electronic Theses and Dissertations
With interest in the changes that may occur to the carbonaceous portion of biochar obtain through the pyrolysis of biomass, the simple interaction between CO2 and biochar with water or a mixture of water and ethanol as hydrogen donor resulted in three significant observations. These reactions were carried out thermally at 333K and photochemically by simulating energy from the with a xenon lamp. The photochemical reaction involving biochar, CO2 with water or a mixture of water and ethanol as hydrogen donor led to a decrease in oxygen content of the parent biochar material, as observed by an increase in the …
Virtual Worlds And Conservational Channel Evolution And Pollutant Transport Systems (Concepts), Chenchutta Denaye Jackson
Virtual Worlds And Conservational Channel Evolution And Pollutant Transport Systems (Concepts), Chenchutta Denaye Jackson
Electronic Theses and Dissertations
Many models exist that predict channel morphology. Channel morphology is defined as the change in geometric parameters of a river. Channel morphology is affected by many factors. Some of these factors are caused either by man or by nature. To combat the adverse effects that man and nature may cause to a water system, scientists and engineers develop stream rehabilitation plans. Stream rehabilitation as defined by Shields et al., states that "restoration is the return from a degraded ecosystem back to a close approximation of its remaining natural potential" [Shields et al., 2003]. Engineers construct plans that will restore streams …
Preprocessing Of Biomass Using Mechanical, Chemical And Microbial Techniques, Swetha Mahalaxmi
Preprocessing Of Biomass Using Mechanical, Chemical And Microbial Techniques, Swetha Mahalaxmi
Electronic Theses and Dissertations
Biomass-derived fuels have acquired a lot of attention recently due to increasing emphasis on energy independence, efforts to utilize abundance of green resources and mitigation of greenhouse gas emissions. Grasses, agricultural residues, animal residues and waste, used oils, etc., can be used as starting materials in the production of biofuels. Various preprocessing techniques used in the preprocessing of biomass, such as microbial preprocessing, mechanical preprocessing and chemical pretreatment, are used for enhancing the digestibility of biomass to sugars for ethanol production. In this work, studies were conducted to improve the microbial, chemical and mechanical preprocessing of switch grass by decreasing …
Bacterial And Sediment Transport In An Artificial Sand Bed Stream During Unsteady Flow, Mary Alexandra Mccaskill
Bacterial And Sediment Transport In An Artificial Sand Bed Stream During Unsteady Flow, Mary Alexandra Mccaskill
Electronic Theses and Dissertations
Storms cause a substantial increase in the fecal indicator bacteria (FIB) concentrations in stream water. Causes for this concentration increase include FIB-laden stormwater runoff and the release of bacteria from stream-bottom sediments. Studies were carried out to quantify this second cause of water quality impairment. Coliform bacteria are a group of FIB, indicate the presence of pathogenic microorganisms, and have been shown to be transported in streams far from their source areas, especially during storms. FIB transport is dependent on several factors including water velocity, size and transport rates of bed sediments, and the FIB concentration in bed sediment. The …
Smart Nanocoated Structure For Energy Harvesting At Low Frequency Vibration, Sudhanshu Sharma
Smart Nanocoated Structure For Energy Harvesting At Low Frequency Vibration, Sudhanshu Sharma
Electronic Theses and Dissertations
Increasing demands of energy which is cleaner and has an unlimited supply has led development in the field of energy harvesting. Piezoelectric materials can be used as a means of transforming ambient vibrations into electrical energy that can be stored and used to power other devices. With the recent surge of micro scale devices, piezoelectric power generation can provide a convenient alternative to traditional power sources. In this research, a piezoelectric power generator composite prototype was developed to maximize the power output of the system. A lead zirconate titanate (PZT) composite structure was formed and mounted on a cantilever bar …
Plume Dispersion Modeling Of Chlorine Gas Released Due To Ballistic Attack On Chlorine-Carrying Railway Tanker, Anna Claire Chapman
Plume Dispersion Modeling Of Chlorine Gas Released Due To Ballistic Attack On Chlorine-Carrying Railway Tanker, Anna Claire Chapman
Electronic Theses and Dissertations
Hazardous dense gases such as chlorine are often transported throughout the United States in their liquid form in pressurized railway tankers. These tankers can hold up to 90 tons of liquid chlorine. A high-powered, ballistic attack on a chlorine-carrying tanker could cause devastating outcomes for the surrounding population and environment. This particular terrorist attack was modeled and analyzed by varying a large number of weather parameters and by varying terrain in order to provide specific concentration data at different distances from the source. Data was compiled to provide first responders with a reliable reference for such an emergency so that …
Processes Involving Acid Gas Solubility In Room Temperature Ionic Liquids (Rtils), Fadekemi E. Osideinde
Processes Involving Acid Gas Solubility In Room Temperature Ionic Liquids (Rtils), Fadekemi E. Osideinde
Electronic Theses and Dissertations
The literature contains a number of thermodynamic studies involving the solubility of acid gases in RTILs. This thesis looks at using these studies in the context of two processes: membrane separation and absorption refrigeration cycles. The first part of this study investigated the separation of a mixed dry gas feed of CO2/CH4 by four Stabilized Ionic Liquid Membranes (SILMs); 1-Ethyl-3-methlyimidazolium dicyanamide, [emim][DCA], 1-ethyl-3-methylimidazolium thiocyanate, [emim][SCN], 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide, [emim][Tf2N] and 1-Butyl-3-methylimidazolium nitrate, [bmim][NO 3]. The selectivities and permeances for the CO2/CH 4 feed were measured in all four SILMs at various partial pressures of CO2 in the feed and at two …
Using Eye Tracking And Attention Maps In Computer Science Education, Austin Pernell
Using Eye Tracking And Attention Maps In Computer Science Education, Austin Pernell
Electronic Theses and Dissertations
Eye tracking has been used for many different areas of study where a user's eye movements are considered the most important information available. Before eye tracking was possible, the only way that information could be obtained was to ask the user where they looked and what caught their attention. Now, with the rise of eye tracking cameras, this data can be captured, stored, and processed in a meaningful way. These cameras aren't perfectly accurate however and there is still some interpretation that must be applied to more accurately represent the true gaze path of the user. This paper establishes some …
A Comparative Study Of Segmented Tungsten Rod Penetration Into A Thick Steel Target Plate, Michael Bryant Presnell
A Comparative Study Of Segmented Tungsten Rod Penetration Into A Thick Steel Target Plate, Michael Bryant Presnell
Electronic Theses and Dissertations
This thesis presents results from computational simulations of tungsten alloy segmented rod projectiles (SRP) penetrating an RHA semi-infinite target plate at high velocities. Penetration experimental data show improved penetration efficiency by the segmented projectiles when compared to monolithic (single solid rod) projectiles. For SRP with an aspect ratio (L/D) = 1/8, a loss in penetration efficiency was seen upon successive segment impacts. A numerical simulation impacting tungsten heavy alloy against RHA 4340 steel was performed using the Lagrangian finite element code EPIC 2006. The impact configuration that was modeled consisted of eight successive collinear impacts of discs measured 2mm in …
Experimental And Numerical Analysis Of Nano-Enhanced Polymer Coated Steel Plates Subjected To Ballistic Loading, Miles Coleman Fowler
Experimental And Numerical Analysis Of Nano-Enhanced Polymer Coated Steel Plates Subjected To Ballistic Loading, Miles Coleman Fowler
Electronic Theses and Dissertations
The following is a summary of research for a portion of the project titled Nano-Enhanced and Bio-Inspired Composite Materials for Mitigation and Protection of TIH Railcars and Stationary Tanks Against High Power Impact. This research investigated several nano-enhanced polymers for their suitability in high-speed impact protection applications. The polymers were tested mechanically to find ideal nano-particle additive percentages then coated onto steel substrates. These coated substrates were impacted using 0.50-caliber projectiles in order to find the ballistic limit (V50) for each combination. Computer modeling in ANSYS AUTODYN was undertaken to calculate a numerical ballistic limit for each plate configuration. The …
Analysis Of Wavelet Based Alternatives For Ofdm, Tassniem Rashed
Analysis Of Wavelet Based Alternatives For Ofdm, Tassniem Rashed
Electronic Theses and Dissertations
The objective of this thesis is to analyze wavelet based alternatives for orthogonal frequency division multiplexing (OFDM) and find whether a better system performance is achieved when compared to the discrete Fourier transform (DFT)-based OFDM. We analyze DFT, discrete wavelet transform (DWT), and dual tree complex wavelet transform (DT-CWT) based systems in an additive white Gaussian noise (AWGN) channel. The analysis is verified by Monte Carlo simulation. The results in the thesis indicate that the bit error probability (BEP) performance is the same for all types of systems. This confirms some results presented in the literature but differs from others. …
Advanced Design Methodologies And Novel Applications Of Reflectarray Antennas, Payam Nayeri
Advanced Design Methodologies And Novel Applications Of Reflectarray Antennas, Payam Nayeri
Electronic Theses and Dissertations
Reflectarray antennas combine the numerous advantages of printed antenna arrays and reflector antennas and create a hybrid high-gain antenna with a low-profile, low-mass, and diversified radiation performance. Reflectarrays are now emerging as the new generation of high-gain antennas for long-distance communications. In this dissertation, some advanced concepts demonstrating novel features of reflectarray antennas are presented. • First, various approaches for radiation analysis of reflectarray antennas are described and implemented. Numerical results are then presented for a variety of systems and the advantages, limitations, and accuracy of these approaches are discussed and compared with each other. • A broadband technique by …
A Fractal Analysis Of The Detection Of Glucose Molecules On Biosensor Surfaces, Lokesh Taneja
A Fractal Analysis Of The Detection Of Glucose Molecules On Biosensor Surfaces, Lokesh Taneja
Electronic Theses and Dissertations
A fractal analysis for the binding and dissociation of glucose molecules to different biosensor surfaces is presented. The sensors contain immobilized glucose oxidase enzymes that have an affinity for the glucose molecules in solution. Data for different modified biosensors is modeled and analyzed, and a single, dual or triple-fractal analysis is applied where adequate. The binding and dissociation kinetics coefficient where applicable are calculated for each of models along with the fractal dimensions. When both binding and dissociation phases are present, the affinity, K of the receptor to the glucose molecule is calculated and its variation with the fractal dimension …
Finite Element Modeling Of Seismic Wave Propagation In Earthen Embankments, Binyam Tadese
Finite Element Modeling Of Seismic Wave Propagation In Earthen Embankments, Binyam Tadese
Electronic Theses and Dissertations
The detection of internal seepage zones in embankments (dams and levees) by geophysical seismic techniques such as seismic refraction is limited by a number of factors. Some factors are associated with inversion and smoothing problems during processing, while others are associated with the natural characteristics of embankments and seepage anomalies. In this research, changes in the seismic response associated with: embankment soil compositions and moisture, characteristics of the seepage zone, presence of water in the reservoir, and shape of embankment was studied via 2D and 3D finite element (FE) embankment models. Artificial reflections from external boundaries and numerical dispersion were …
Inspection Of Earthen Embankment Dams Using Time Lapse Electrical Resistivity Tomography, Jared Stewart Case
Inspection Of Earthen Embankment Dams Using Time Lapse Electrical Resistivity Tomography, Jared Stewart Case
Electronic Theses and Dissertations
According to the National Inventory of Dams (NID), the number of dams across the United States is approximately 85,000. Many of these dams are more than 50 years old and need vast attention to ensure their safety. It is difficult to obtain a full assessment of the dam just by visual inspections alone. This is because many problems associated with dam failure occur internally, which makes it difficult to be observed by the dam inspectors. Examples of these flaws are piping and seepage (flow of water through or around dam walls). It is in this area where geophysical methods can …
Experimental Investigation Of Transonic Shock Oscillations On Naca 0018 At Incidence, Christopher Allen Farrell
Experimental Investigation Of Transonic Shock Oscillations On Naca 0018 At Incidence, Christopher Allen Farrell
Electronic Theses and Dissertations
A NACA 0018 airfoil model with a 3-inch chord was mounted into the trisonic wind tunnel at the National Center for Physical Acoustics at the University of Mississippi. Tunnel runs were conducted with the angle of incidence increasing from 0 degrees to 6 degrees at 1 degree increments, while the Mach number was held steady at 0.73. High-speed schlieren images were recorded at a sample rate of 4,000 Hz. A Matlab code was developed to display the spatial power spectral density distribution in the region of the shock. This code calculated the frequency spectrum at regular points along the range …
Synthesis And Evaluation Of Naturally Occuring Halogenated Bipyrroles In A Relevant Marine Species, Fundulus Heteroclitus, Kimberly Sheree Foster
Synthesis And Evaluation Of Naturally Occuring Halogenated Bipyrroles In A Relevant Marine Species, Fundulus Heteroclitus, Kimberly Sheree Foster
Electronic Theses and Dissertations
Halogenated dimethyl-2-2'-bipyrroles (HDBPs) have recently been discovered in seabird eggs and have been shown to bioaccumulate in trophic organisms. HDBPs are suspected to be biogenic in nature, derived from evidence of marine natural products that are persistent in the environment and widespread in the Pacific and Atlantic Ocean. The HDBPs exhibit chlorinated and brominated substitution patterns that closely resemble anthropogenic pollutants like the polychlorinated biphenyls (PCBs), polybrominated biphenyls (PBBs), and polybrominated diphenyl ethers (PBDEs). Environmental health concerns exists regarding these naturally occurring HDBPs because several of these analogs were shown to induce the cytochrome P4501A (CYP1A) gene through activation of …
Distributed Space-Time Message Relaying For Uncoded/Coded Wireless Cooperative Communications, Peng Huo
Distributed Space-Time Message Relaying For Uncoded/Coded Wireless Cooperative Communications, Peng Huo
Electronic Theses and Dissertations
During wireless communications, nodes can overhear other transmissions through the wireless medium, suggested by the broadcast nature of plane wave propagation, and may help to provide extra observations of the source signals to the destination. Modern research in wireless communications pays more attention to these extra observations which were formerly neglected within networks. Cooperative communication processes this abundant information existing at the surrounding nodes and retransmits towards the destination in various forms to create spatial and/or coding diversity, thereby to obtain higher throughput and reliability. The aim of this work is to design cooperative communication systems with distributed space-time block …
Homogenization Of Structured Metasurfaces And Uniaxial Wire Medium Metamaterials For Microwave Applications, Chandra Sekhar Reddy Kaipa
Homogenization Of Structured Metasurfaces And Uniaxial Wire Medium Metamaterials For Microwave Applications, Chandra Sekhar Reddy Kaipa
Electronic Theses and Dissertations
In recent years, the study of electromagnetic wave interaction with artificial media has been the subject of intense research interest due to their extraordinary properties such as negative refraction, partial focusing, enhanced transmission, and spatial filtering, among others. Artificial media are crystals of various periodic metallic inclusions with dimensions of the order of ?/10 - ?/4. When compared to natural materials, the inclusions are, thus, not as small in terms of the wavelength, even in the optical band. Therefore, one should expect the electrodynamics of these media to be inherently non-local, characterized by strong spatial dispersion effects. The dissertation includes …
Reconfigurable Wideband Circularly Polarized Microstrip Patch Antenna For Wireless Applications, Ahmed Khidre
Reconfigurable Wideband Circularly Polarized Microstrip Patch Antenna For Wireless Applications, Ahmed Khidre
Electronic Theses and Dissertations
In this thesis, developments of rectangular microstrip patch antenna to have circular polarization agility with wideband performance, for wireless applications are presented. First, a new technique to achieve circularly polarized (CP) probe feed single-layer microstrip patch antenna with wideband characteristics is proposed. The antenna is a modified form of the popular E-shaped patch, used to broaden the impedance bandwidth of a basic rectangular patch antenna. This is established by letting the two parallel slots of the E-patch unequal. Thus, by introducing asymmetry two orthogonal currents on the patch are excited and circularly polarized fields are realized. The proposed technique exhibits …
Admicellar Polymerization To Compatibilize Calcium Carbonate With Oil-Based Drilling Mud, Olugbenga Samuel Ojo
Admicellar Polymerization To Compatibilize Calcium Carbonate With Oil-Based Drilling Mud, Olugbenga Samuel Ojo
Electronic Theses and Dissertations
Weighting agents like calcium carbonate (CC) are added to drilling mud to improve mud properties and performance during oil and gas drilling operations. Oil-based mud (OBM), a more preferred drilling mud, being hydrophobic is particularly non-compatible with hydrophilic CC. This work explored an economically viable admicellar polymerization technique to surface-modify the high energy hydrophilic CC surface to a low energy hydrophobic surface by polymerizing organic styrene monomer within an admicelle of nonionic surfactant Triton X-100 adsorbed on the CC surface. BET N2 particle size analysis, Soxhlet extraction of the coated polymer, Fourier transform infrared-attenuated total reflectance (FTIR-ATR) spectra analysis, and …
Implementation Of Multiple-Instance Learning In Drug Activity Prediction, Gang Fu
Implementation Of Multiple-Instance Learning In Drug Activity Prediction, Gang Fu
Electronic Theses and Dissertations
In the context of drug discovery and development, much effort has been exerted to determine which conformers of a given molecule are responsible for the observed biological activity. In this work we aimed to predict bioactive conformers using a variant of supervised learning, named multiple-instance learning. A single molecule, treated as a bag of conformers, is biologically active if and only if at least one of its conformers, treated as an instance, is responsible for the observed bioactivity; and a molecule is inactive if none of its conformers is responsible for the observed bioactivity. The implementation requires instance-based embedding, and …
Numerical Evaluation Of Different Retrofitting Techniques Of New Orleans Floodwalls And Implementation Of Advanced Constitutive Model In Flac3d, Sudarshan Adhikari
Numerical Evaluation Of Different Retrofitting Techniques Of New Orleans Floodwalls And Implementation Of Advanced Constitutive Model In Flac3d, Sudarshan Adhikari
Electronic Theses and Dissertations
The objective of this study was to re-examine some but the crucial established failure mechanism, and also to establish other failure mechanisms of the floodwalls due to hurricanes in New Orleans so that the necessary retrofitting techniques could be sought out. Depending on the failure mechanisms, two of the proposed retrofitting techniques such as "structural cap" to maintain integrity by tying adjacent panels of I-type floodwalls, and "bentonite apron" to self seal gaps that occur between the floodwall and foundation soil were chosen, for which their performances had to be evaluated. This dissertation documents all the numerical analysis conducted to …
Geospatial Assessment Of Sustainable Built Infrastructure Assets And Flood Disaster Protection, Alper Durmus
Geospatial Assessment Of Sustainable Built Infrastructure Assets And Flood Disaster Protection, Alper Durmus
Electronic Theses and Dissertations
This research was initiated with a review and synthesis of infrastructure related to city and urban growth, built infrastructure to meet transportation needs and travel demand, and role of mass transit in reducing adverse impacts on the environment and greenhouse gas emissions. Floods are the most frequently occurring natural disaster in the world, which so far claimed millions of lives and resulted in billion-dollar economic costs. Built infrastructure assets in urban and rural areas are not spared from floods' aftermath. A major motivation for this thesis was the 2011 megaflood disaster of Thailand which devastated the green campus of Asian …
Determination Of Cutoff Frequencies Of Simple Waveguides Using Finite Difference Method, Sridhar Kolagani
Determination Of Cutoff Frequencies Of Simple Waveguides Using Finite Difference Method, Sridhar Kolagani
Electronic Theses and Dissertations
No abstract provided.