Open Access. Powered by Scholars. Published by Universities.®
- Discipline
-
- Electrical and Computer Engineering (39)
- Physical Sciences and Mathematics (34)
- Civil and Environmental Engineering (28)
- Mechanical Engineering (27)
- Electrical and Electronics (23)
-
- Civil Engineering (21)
- Computer Sciences (20)
- Operations Research, Systems Engineering and Industrial Engineering (13)
- Electromagnetics and Photonics (12)
- Optics (12)
- Physics (12)
- Industrial Engineering (11)
- Materials Science and Engineering (10)
- Computer Engineering (7)
- Engineering Science and Materials (6)
- Environmental Engineering (6)
- Aerospace Engineering (3)
- Biomedical Engineering and Bioengineering (3)
- Chemical Engineering (2)
- Chemistry (2)
- Computer-Aided Engineering and Design (2)
- Aerodynamics and Fluid Mechanics (1)
- Biomedical (1)
- Biomedical Devices and Instrumentation (1)
- Communication Sciences and Disorders (1)
- Ecology and Evolutionary Biology (1)
- Engineering Mechanics (1)
- Life Sciences (1)
- Mechanics of Materials (1)
- Institution
- Keyword
-
- Daniel Felix Ritchie School of Engineering and Computer Science (12)
- Simulation (5)
- Machine learning (3)
- Nonlinear optics (3)
- Performance (3)
-
- Shape memory alloys (3)
- CATER (2)
- Computer Science (2)
- Damage Detection (2)
- Data Mining (2)
- Genetic Programming (2)
- Heat pipes (2)
- Human action recognition (2)
- Interdiffusion (2)
- LDMOS (2)
- Laser (2)
- Machine Learning (2)
- Monte Carlo Simulation (2)
- Nickel titanium alloys (2)
- Peer-to-peer (2)
- Percolation (2)
- Presence (2)
- QuikSCAT (2)
- Remote Sensing (2)
- Safety (2)
- SeaWinds (2)
- Severity (2)
- Solar energy (2)
- Structural Health Monitoring (2)
- Tides (2)
Articles 31 - 60 of 154
Full-Text Articles in Engineering
Unsupervised Building Detection From Irregularly Spaced Lidar And Aerial Imagery, Nicholas Shorter
Unsupervised Building Detection From Irregularly Spaced Lidar And Aerial Imagery, Nicholas Shorter
Electronic Theses and Dissertations
As more data sources containing 3-D information are becoming available, an increased interest in 3-D imaging has emerged. Among these is the 3-D reconstruction of buildings and other man-made structures. A necessary preprocessing step is the detection and isolation of individual buildings that subsequently can be reconstructed in 3-D using various methodologies. Applications for both building detection and reconstruction have commercial use for urban planning, network planning for mobile communication (cell phone tower placement), spatial analysis of air pollution and noise nuisances, microclimate investigations, geographical information systems, security services and change detection from areas affected by natural disasters. Building detection …
Unified Large And Small Signal State-Space Based Modeling And Symbolic Simulation For Pwm Converters, Ehab Shoubaki
Unified Large And Small Signal State-Space Based Modeling And Symbolic Simulation For Pwm Converters, Ehab Shoubaki
Electronic Theses and Dissertations
In this Dissertation, which concentrates on discrete modeling for control purposes of DC/DC converters and simulation through symbolic techniques. A Unified Discrete State-Space Model for power converters in CCM is presented. Two main approaches to arriving at the discrete model are used. The first approach involves an impulse function approximation of the duty cycle modulation of the converter switches, and this approach results in a small signal discrete model. The Second approach is direct and does not involve any approximation of the modulation, this approach yields both a large signal nonlinear discrete model and a linear small signal model. Harmonic …
Physical Properties Of Wave Scattering By Chiral Periodic Structure, Xiaomin Yang
Physical Properties Of Wave Scattering By Chiral Periodic Structure, Xiaomin Yang
Electronic Theses and Dissertations
Attention has been focused on electromagnetic chirality and its potential applications to microwave, millimeter wave and optical wave devices. In this work, wave propagation through a chiral periodic structure with arbitrary shape is investigated. Although perturbation theory and coupled-mode theory have been used to analyze chiral periodic structure, those are approximate methods and can only be used for low frequency applications. In this work, the rigorous mode-matching method is used to solve the problem. Staircase approximation is introduced to change the curved structure to a multilayer structure. The field solutions in the uniform air regions and unbounded air-chiral periodic array …
Control Of Nonh=Holonomic Systems, Hongliang Yuan
Control Of Nonh=Holonomic Systems, Hongliang Yuan
Electronic Theses and Dissertations
Many real-world electrical and mechanical systems have velocity-dependent constraints in their dynamic models. For example, car-like robots, unmanned aerial vehicles, autonomous underwater vehicles and hopping robots, etc. Most of these systems can be transformed into a chained form, which is considered as a canonical form of these nonholonomic systems. Hence, study of chained systems ensure their wide applicability. This thesis studied the problem of continuous feed-back control of the chained systems while pursuing inverse optimality and exponential convergence rates, as well as the feed-back stabilization problem under input saturation constraints. These studies are based on global singularity-free state transformations and …
Delay Modeling And Long-Range Predictive Control Of Czochralski Growth Process, Dhaval Shah
Delay Modeling And Long-Range Predictive Control Of Czochralski Growth Process, Dhaval Shah
Electronic Theses and Dissertations
This work presents the Czochralski growth dynamics as time-varying delay based model, applied to the growth of La3Ga5.5Ta0.5O14 (LGT) piezoelectric crystals. The growth of high-quality large-diameter oxides by Czochralski technique requires the theoretical understanding and optimization of all relevant process parameters, growth conditions, and melts chemistry. Presently, proportional-integral- derivative (PID) type controllers are widely accepted for constant-diameter crystal growth by Czochralski. Such control systems, however, do not account for aspects such as the transportation delay of the heat from crucible wall to the crystal solidification front, heat radiated from the crucible wall above the melt surface, and varying melt level. …
Pulse Frequency Modulation Zcs Flyback Converter In Inverter Applications, Feng Tian
Pulse Frequency Modulation Zcs Flyback Converter In Inverter Applications, Feng Tian
Electronic Theses and Dissertations
Renewable energy source plays an important role in energy co-generation and distribution. A traditional solar-based inverter system has two stages cascaded, which has simpler controller but low efficiency. A new solar-based single-stage grid-connected inverter system can achieve higher efficiency by reducing the power semiconductor switching loss and output stable and synchronizing sinusoid current into the utility grid. In Chapter 1, the characteristic I-V and P-V curve of PV array has been illustrated. Based on prediction of the PV power capacity installed on the grid-connected and off-grid, the trends of grid-tied inverter for DG system have been analyzed. In Chapter 2, …
A Gis Safety Study And A County-Level Spatial Analysis Of Crashes In The State Of Florida, Ali Darwiche
A Gis Safety Study And A County-Level Spatial Analysis Of Crashes In The State Of Florida, Ali Darwiche
Electronic Theses and Dissertations
The research conducted in this thesis consists of a Geographic Information Systems (GIS) based safety study and a spatial analysis of vehicle crashes in the State of Florida. The GIS safety study is comprised of a County and Roadway Level GIS analysis of multilane corridors. The spatial analysis investigated the use of county-level vehicle crash models, taking spatial effects into account. The GIS safety study examines the locations of high trends of severe crashes (includes incapacitating and fatal crashes) on multilane corridors in the State of Florida at two levels, county level and roadway level. The GIS tool, which is …
Evaluating The Impact Of Oocea's Dynamic Message Signs (Dms) On Travelers' Experience Using Multinomial And Ordered Logit For The Post-Deployment Survey, Taylor Lochrane
Evaluating The Impact Of Oocea's Dynamic Message Signs (Dms) On Travelers' Experience Using Multinomial And Ordered Logit For The Post-Deployment Survey, Taylor Lochrane
Electronic Theses and Dissertations
The purpose of this thesis was to evaluate the impact of dynamic message signs (DMS) on the Orlando-Orange County Expressway Authority (OOCEA) toll road network using the Post-Deployment DMS Survey analysis. DMS are electronic traffic signs used on roadways to give travelers information about travel times, traffic congestion, accidents, disabled vehicles, AMBER alerts, and special events. The particular DMS referred to in this study are large rectangular signs installed over the travel lanes and these are not the portable trailer mount signs. The OOCEA has added twenty-nine fixed DMS to their toll road network from 2006-2008. At the time of …
A Gasoline Demand Model For The United States Light Vehicle Fleet, Diana Rey
A Gasoline Demand Model For The United States Light Vehicle Fleet, Diana Rey
Electronic Theses and Dissertations
The United States is the world's largest oil consumer demanding about twenty five percent of the total world oil production. Whenever there are difficulties to supply the increasing quantities of oil demanded by the market, the price of oil escalates leading to what is known as oil price spikes or oil price shocks. The last oil price shock which was the longest sustained oil price run up in history, began its course in year 2004, and ended in 2008. This last oil price shock initiated recognizable changes in transportation dynamics: transit operators realized that commuters switched to transit as a …
Macroscopic Traffic Safety Analysis Based On Trip Generation Characteristics, Chowdhury Siddiqui
Macroscopic Traffic Safety Analysis Based On Trip Generation Characteristics, Chowdhury Siddiqui
Electronic Theses and Dissertations
Recent research has shown that incorporating roadway safety in transportation planning has been considered one of the active approaches to improve safety. Aggregate level analysis for predicting crash frequencies had been contemplated to be an important step in this process. As seen from the previous studies various categories of predictors at macro level (census blocks, traffic analysis zones, census tracts, wards, counties and states) have been exhausted to find appropriate correlation with crashes. This study contributes to this ongoing macro level road safety research by investigating various trip productions and attractions along with roadway characteristics within traffic analysis zones (TAZs) …
Work Zone Effects On Performance Of A Toll Plaza, Jingyu Liu
Work Zone Effects On Performance Of A Toll Plaza, Jingyu Liu
Electronic Theses and Dissertations
No-lane closure workzone is typical during the construction of open road tolling lanes of a toll plaza. The influence of no-lane closure on toll plazas' performance is unknown because very few studies have been conducted to address this topic. The open road tolling (ORT) has become the new trend of operating an efficient toll plaza. So, the upgrading of a toll plaza from gated E-pass to open road E-pass has become common. The better the toll plaza authority knows about the influence of this construction and congestion effects, the better it can serve the costumers. This project mainly deals with …
Safety Improvements On Multilane Arterials A Before And After Evaluation Using The Empirical Bayes Method, Prem Chand Devarasetty
Safety Improvements On Multilane Arterials A Before And After Evaluation Using The Empirical Bayes Method, Prem Chand Devarasetty
Electronic Theses and Dissertations
This study examines the safety effects of the improvements made on multi-lane arterials. The improvements were divided into two categories 1) corridor level improvements, and 2) intersection improvements. Empirical Bayes method, which is one of the most accepted approaches for conducting before-after evaluations, has been used to assess the safety effects of the improvement projects. Safety effects are estimated not only in terms of all crashes but also rear-end (most common type) as well as severe crashes (crashes involving incapacitating and/or fatal injuries) and also angle crashes for intersection improvements. The Safety Performance Functions (SPFs) used in this study are …
Determining Emissions From Landfills And Creating Odor Buffer Distances, Nicholas Guarrieloo
Determining Emissions From Landfills And Creating Odor Buffer Distances, Nicholas Guarrieloo
Electronic Theses and Dissertations
With population growing every year, more and more people are looking for places to live. This can lead to construction of houses near and around landfills. As homes get closer to landfills, the odors these landfills produce become more of a problem, and lead to an increase in odor complaints. Modeling these odors and recommending odor buffer distances will help determine limits on how close to landfills new homes should be allowed. This should help reduce future odor complaints. To solve this problem one must accurately estimate odorous gas emissions from the landfill. Often odors can be indicated by methane …
Nutrient And Pathogen Removal In A Subsurface Upflow Wetland System Using Green Sorption Media, Zhemin Xuan
Nutrient And Pathogen Removal In A Subsurface Upflow Wetland System Using Green Sorption Media, Zhemin Xuan
Electronic Theses and Dissertations
Due to environmental health and nutrient impact concerns, the conventional on-site sewage collection, treatment, and disposal systems are no longer able to meet the nutrient reduction requirements for wastewater effluent and may represent a large fraction of pollutant loads. The loads include not only nitrogen (N) and phosphorus (P), but also pathogens such as fecal coliform and E. coli which indicate the presence of other disease-causing bacteria flowing into aquatic system that adversely affect public health. A subsurface upflow wetland, which is an effective small-scale wastewater treatment system with low energy and maintenance requirements and operational costs, fits the current …
Post Treatment Alternatives For Stabilizing Desalinated Water, Susaye Douglas
Post Treatment Alternatives For Stabilizing Desalinated Water, Susaye Douglas
Electronic Theses and Dissertations
The use of brackish water and seawater desalination for augmenting potable water supplies has focused primarily on pre-treatment, process optimization, energy efficiency, and concentrate management. Much less has been documented regarding the impact of post-treatment requirements with respect to distribution system. The goals of this study were to review current literature on post-treatment of permeate water, use survey questionnaires to gather information on post-treatment water quality characteristics, gather operation information, review general capital and maintenance cost, and identify appropriate "lessons learned" with regards to post-treatment from water purveyors participating in the Project. A workshop was organized where experts from across …
The Design And Development Of An Additive Fabrication Process And Material Selection Tool, Andrew Palmer
The Design And Development Of An Additive Fabrication Process And Material Selection Tool, Andrew Palmer
Electronic Theses and Dissertations
In the Manufacturing Industry there is a subset of technologies referred to as Rapid Technologies which are those technologies that create the ability to compress the time to market for new products under development . Of this subset, Additive Fabrication (AF), or more commonly known as Rapid Prototyping (RP), acquires much attention due to its unique and futuristic approach to the production of physical parts directly from 3D CAD data, CT or MRI scans, or data from laser scanning systems by utilizing various techniques to consecutively generate cross-sectional layers of a given thickness upon the previous layer to form 3D …
Formation Of Lyotropic Liquid Crystals Through The Self-Assembly Of Bile Acid Building Blocks, Karan Tamhane
Formation Of Lyotropic Liquid Crystals Through The Self-Assembly Of Bile Acid Building Blocks, Karan Tamhane
Electronic Theses and Dissertations
Liquid crystalline materials (LCMs) have gained much popularity over the past century. The thermotropic forms of these materials have been extensively studied and employed in a range of innovative applications. The lyotropic liquid crystal systems that have been studied in the past have often been formed by the organization of natural and synthetic small molecules in solutions. In this study, we use self-assembled supramolecular structures as building blocks to fabricate lyotropic liquid crystals. We investigate the self-assembly of a naturally occurring bile acid called lithocholic acid (LCA), to form supramolecular fibrous and tubular structures in basic aqueous solutions. We control …
Characterization And Aqueous Colloidal Processing Of Tungsten Nano-Powders, Zhengtao Yang
Characterization And Aqueous Colloidal Processing Of Tungsten Nano-Powders, Zhengtao Yang
Electronic Theses and Dissertations
Extensive attention has been paid to consolidate nanoparticles into nanocrystalline components that possess better properties than their coarse-grained counterparts. Nanocrystalline monolithic tungsten (W) has been envisaged to possess better properties than coarse-grained tungsten and to improve the performance of many military components. Commercially available nano-W powders were characterized via X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), Auger electron spectroscopy (AES) and Brunauer, Emmett, and Teller (BET) measurement. While the bulk of nano-W powders consisted of bcc-W as confirmed by XRD and TEM, much of their surface consisted of WO3 with traces of …
Flow Visualization In Microfluidic Expansion And Mixing, Ehsan Yakhshi-Tafti
Flow Visualization In Microfluidic Expansion And Mixing, Ehsan Yakhshi-Tafti
Electronic Theses and Dissertations
Micro particle image velocimetry (microPIV) is a non-intrusive tool for visualizing flow in micron-scale conduits. Using this investigative instrument, two experimental studies were performed to understand flow behaviors in microfluidic channels - a sudden expansion step flow and laminar velocity profile variation in diffusion driven mixing. First, flow in a backward facing step feature (1:5 expansion ratio) in a microchannel was taken as the subject of microPIV flow visualization. The onset and development of a recirculation flow was studied as a function of flow rate. This flow pattern was further used to investigate two major parameters affecting microPIV measurements; the …
Sintering Additives For Nanocrystalline Titania And Processing Of Porous Bone Tissue Engineering Scaffolds, Arun Menon
Sintering Additives For Nanocrystalline Titania And Processing Of Porous Bone Tissue Engineering Scaffolds, Arun Menon
Electronic Theses and Dissertations
Titania (Titanium dioxide, TiO2) has been researched as a promising biomaterial due to its excellent biocompatibility. However, the main limitation of titania is its poor mechanical properties which limit its use in many load-bearing applications. In this thesis report, the properties of titania were improved by doping with small quantities of MgO, ZnO and SiO2 as sintering additives. Nanocrystalline powder was selected, as it possesses outstanding properties over conventional coarse-grained powders due to reduced grain size. Nanocrystalline anatase powder of size 5-15 nm was synthesized via a simple sol-gel technique. Small quantities of dopants were introduced into pure titania powder, …
Characterization Of A Hydrogen-Based Synthetic Fuel In A Shock Tube, Troy Flaherty
Characterization Of A Hydrogen-Based Synthetic Fuel In A Shock Tube, Troy Flaherty
Electronic Theses and Dissertations
Shock-tube experiments were performed with syngas mixtures near atmospheric pressure with varying equivalence ratios behind reflected shock waves. Pressure and hydroxyl radical (OH*) emission traces were recorded and used to calculate ignition delay time for a single mixture at equivalence ratios of [phi ]=0.4, 0.7, 1.0, and 2.0 over a range of temperatures from 913-1803 K. The syngas mixture was tested at full concentration as well as with 98% dilution in Argon. The full concentration mixtures were used to compare ignition delay time measurements with the theoretical calculations obtained through the use of chemical kinetics modeling using the Davis et …
Percolation Study Of Nano-Composite Conductivity Using Monte Carlo Simulationpercolation, Jing Bai
Percolation Study Of Nano-Composite Conductivity Using Monte Carlo Simulationpercolation, Jing Bai
Electronic Theses and Dissertations
A Monte Carlo model is developed for predicting electrical conductivity of carbon nanofiber composite materials. The conductive nanofibers are models as both 2D and 3D network of finite sites that are randomly distributed. The percolation behavior of the network is studied using the Monte Carlo method, which leads to the determination of the percolation threshold. The effect of the nanofiber aspect ratio on the critical nanofiber volume rate is investigated in the current model, each of the nanofibers needs five independent geometrical parameters (i.e., three coordinates in space and two orientation angles) for its identification. There are three controlling parameters …
Structural Analysis And Active Vibration Control Of Tetraform Space Frame For Use In Micro-Scale Machining, Kevin Knipe
Structural Analysis And Active Vibration Control Of Tetraform Space Frame For Use In Micro-Scale Machining, Kevin Knipe
Electronic Theses and Dissertations
This research thesis aims to achieve the structural analysis and active vibration damping of the Tetraform machining structure. The Tetraform is a space frame made up of four equilateral triangles with spherical masses at the four vertices. This frame was originally developed for grinding of optical lenses and is now being adapted for use in micro-precision milling. The Tetraform is beneficial to the milling process due to its exceptionally high dynamic stiffness characteristics, which increases the machining stability and allows for higher material removal rates and accuracy. However, there are still some modes of vibration that are critical to the …
Stress Intensity Factor Dependence Of Hg-Al Liquid Metal Embrittlement, Scott Keller
Stress Intensity Factor Dependence Of Hg-Al Liquid Metal Embrittlement, Scott Keller
Electronic Theses and Dissertations
When high strength aluminum alloys are subjected to liquid metals, physical and chemical reactions ensue resulting in what is known as liquid metal embrittlement (LME). A subset of environmentally-assisted cracking, LME is exhibited when a liquid metal, e.g. Hg or Ga, comes into intimate contact with a solid metal having significant susceptibility. As mechanical loads are applied, the interaction between the two metals results in a reduction in the flow properties of the solid metal. Several theories have been proposed to identify the underlying microstructural failure mechanism; however, none have been widely accepted, as failures can typically incorporate features common …
The Effect Of Heat Transfer Coefficient On High Aspect Ratio Channel Accompanied By Varying Rib Aspect Ratio, An Le
Electronic Theses and Dissertations
Heat transfer and pressure data were performed and reported on two different rigs. The first rig has an aspect ratio of (19:1) with two different inlet conditions and the second rig is composed of two different aspect ratio channels, (1:8) and (1:4). Rib turbulators were used as a flow disruptor scheme to enhance the heat transfer and friction factor. Rib aspect ratios ranging from (1:1) to (1:5) rib-height-to-width ratio were used. The first channel rib-width-to-pitch (Wr/P) ratio was kept at 1/2 where flow was kept at relatively low Reynolds numbers, between 3000 and 13000. Results from the current tests showed …
Tertiary Creep Damage Modeling Of A Transversely Isotropic Ni-Based Superalloy, Calvin Stewart
Tertiary Creep Damage Modeling Of A Transversely Isotropic Ni-Based Superalloy, Calvin Stewart
Electronic Theses and Dissertations
Anisotropic tertiary creep damage formulations have become an increasingly important prediction technique for high temperature components due to drives in the gas turbine industry for increased combustion chamber exit pressures, temperature, and the use of anisotropic materials such as metal matrix composites and directionally-solidified (DS) Ni-base superalloys. Typically, isotropic creep damage formulations are implemented for simple cases involving a uniaxial state of stress; however, these formulations can be further developed for multiaxial states of stress where materials are found to exhibit induced anisotropy. In addition, anisotropic materials necessitate a fully-developed creep strain tensor. This thesis describes the development of a …
Water Vapor And Carbon Dioxide Species Measurement In Narrow Channels, Derek Lambe
Water Vapor And Carbon Dioxide Species Measurement In Narrow Channels, Derek Lambe
Electronic Theses and Dissertations
A novel method has been implemented for measuring the concentration of gas species, water vapor and carbon dioxide, within a narrow channel flow field non-invasively using tunable diode laser absorption spectroscopy (TDLAS) in conjunction with a laser modulated at a high frequency [Wavelength Modulation Spectroscopy (WMS)] tuned to the ro-vibrational transition of the species. This technique measures the absorption profile which is a strong function of the species concentration across short path lengths and small time spans, as in PEM fuel cells during high load cycles. This method has been verified in a transparent circular flow 12 cm path length …
Vectorpad: A Tool For Visualizing Vector Operations, Jared Bott
Vectorpad: A Tool For Visualizing Vector Operations, Jared Bott
Electronic Theses and Dissertations
Visualization of three-dimensional vector operations can be very helpful in understanding vector mathematics. However, creating these visualizations using traditional WIMP interfaces can be a troublesome exercise. In this thesis, we present VectorPad, a pen-based application for three-dimensional vector mathematics visualization. VectorPad allows users to define vectors and perform mathematical operations upon them through the recognition of handwritten mathematics. The VectorPad user interface consists of a sketching area, where the user can write vector definitions and other mathematics, and a 3D graph for visualization. After recognition, vectors are visualized dynamically on the graph, which can be manipulated by the user. A …
New Computational Approaches For Multiple Rna Alignment And Rna Search, Daniel Deblasio
New Computational Approaches For Multiple Rna Alignment And Rna Search, Daniel Deblasio
Electronic Theses and Dissertations
In this thesis we explore the the theory and history behind RNA alignment. Normal sequence alignments as studied by computer scientists can be completed in O(n2) time in the naive case. The process involves taking two input sequences and finding the list of edits that can transform one sequence into the other. This process is applied to biology in many forms, such as the creation of multiple alignments and the search of genomic sequences. When you take into account the RNA sequence structure the problem becomes even harder. Multiple RNA structure alignment is particularly challenging because covarying mutations make sequence …
A Statistical Approach To View Synthesis, Phillip Berkowitz
A Statistical Approach To View Synthesis, Phillip Berkowitz
Electronic Theses and Dissertations
View Synthesis is the challenging problem of predicting a new view or pose of an object given an exemplar view or set of views. This thesis presents a novel approach for the problem of view synthesis. The proposed method uses global features rather than local geometry to achieve an effect similar to that of the well known view morphing method . While previous approaches to the view synthesis problem have shown impressive results, they are highly dependent on being able to solve for epipolar geometry and therefore have a very precise correspondence between reference images. In cases where this is …