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Articles 1171 - 1200 of 1237
Full-Text Articles in Engineering
Analyzing Relationships Between Lightning And Rain In Order To Improve Estimation Accuracy Of Rain , Justin Lapp
Analyzing Relationships Between Lightning And Rain In Order To Improve Estimation Accuracy Of Rain , Justin Lapp
All Theses
The remote estimation of rainfall rate R is essential for the aviation industry, agriculture, and food warning. Radar, the current means of R estimation, is not available in much of the world. In addition, this measurement involves a level of inaccuracy. Using lightning to detect rain is a relatively inexpensive alternative to radar systems and can be done from existing satellites. Previous research has revealed correlations between lightning and rain, suggesting either that it is possible to estimate R using lightning, or that it is possible to use it to correct for a portion of the radar inaccuracies. These correlations …
Approaches To Mitigate The Impact Of Dissolved Organic Matter On The Adsorption Of Synthetic Organic Contaminants By Activated Carbon, Abhishek Yadav
Approaches To Mitigate The Impact Of Dissolved Organic Matter On The Adsorption Of Synthetic Organic Contaminants By Activated Carbon, Abhishek Yadav
All Theses
The main objective of this study was to conduct a systematic investigation of various approaches to mitigate the competition of dissolved organic matter (DOM) on the adsorption of synthetic organic contaminants (SOCs) by activated carbons. TCE and atrazine were selected as the target SOCs because they are known to adsorb in different pore size regions. TCE adsorbs in the primary micropore region (i.e., <10 ) which is inaccessible to the majority of the DOM components, while atrazine adsorbs in the secondary micropore region (i.e., 10-20 ) which is partially accessible to some DOM components. The adsorbents used in this study consisted of four activated carbons (OLC, CRC, F400He, and HD4000ST) and one activated carbon fiber (ACF: ACF10). All sorbents were basic and hydrophobic in nature and represented a set of activated carbons with gradually widening pore size distribution, from the extremely microporous carbons (ACF10 and OLC) to carbons with some amount of mesopores (CRC and F400He) and finally a predominantly mesoporous (HD4000ST) carbon.
Isotherms were performed as single solute and after preloading with a dissolved organic matter (5 mg DOC/L and 20 mg DOC/L) for both TCE and atrazine and using the five activated carbons. Single solute isotherm results showed …
Fabrication And Characterization Of Cu/4h-Sic Schottky Diodes, Ruth Solomon
Fabrication And Characterization Of Cu/4h-Sic Schottky Diodes, Ruth Solomon
All Theses
Copper Schottky contacts to n-type 4H Silicon Carbide with nickel ohmic contacts were fabricated. The electrical and physical characteristics of these Schottky diodes were analyzed and the results are presented. I-V measurements revealed two sets of characteristics, one indicating nearly ideal Schottky behavior and the other exhibiting regions with two barrier heights. The reason for this observed phenomenon was studied and attributed to the in-homogeneity of the Silicon Carbide surface. The I-V and C-V characteristics were used to extract the electrical parameters, which include barrier height, ideality factor, reverse saturation current density, and doping concentration. The measured barrier height was …
Development Of A Microscopic Moirž Interferometry System, Jeremy Brougher
Development Of A Microscopic Moirž Interferometry System, Jeremy Brougher
All Theses
The human tooth is an amazing structure that is worthy of detailed research and analysis. For over half a century, various tests have been conducted to acquire more information about the structural and material properties of dentin, enamel, and the dentin-enamel junction. Unfortunately, variations still exist in the experimental results, even in the most recently collected data. The primary focus of the majority of material property testing on human teeth has been hardness testing utilizing indentation and nanoindentation analysis. However, several limitations still exist with the indentation technique. Thus, the moirŽ fringe analysis method, specifically microscopic moirŽ interferometry, has been …
Glycosaminoglycan Stabilization Reduces Tissue Buckling In Bioprosthetic Heart Valves, Sagar Shah
Glycosaminoglycan Stabilization Reduces Tissue Buckling In Bioprosthetic Heart Valves, Sagar Shah
All Theses
Currently, bioprosthetic heart valves are crosslinked with glutaraldehyde to prevent tissue degradation and to reduce tissue antigenicity. Glutaraldehyde forms stable crosslinks with collagen via a Schiff base reaction of the aldehyde with an amine group of the hydroxylysine/lysine in collagen. However, within a decade of implantation, 20-30% of these bioprostheses will become dysfunctional and over 50% will fail due to degeneration within 12-15 years post-operatively.
Gylcosaminoglycans, a major constituent of valvular tissue, play an important role in maintaining a hydrated environment necessary for absorbing compressive loads, modulating shear stresses, and resisting tissue buckling. One of the disadvantages of glutaraldehyde crosslinking …
An Investigation Of Nonlinear Estimation And System Design For Mechatronic Systems, Tim Hughes
An Investigation Of Nonlinear Estimation And System Design For Mechatronic Systems, Tim Hughes
All Theses
This thesis is a collection of two projects in which the author was involved during his master's degree program. The first project involves the estimation of 3D Euclidean coordinates of features from 2D images. A 3D Euclidean position estimation strategy is developed for a static object using a single moving camera whose motion is known. This Euclidean depth estimator has a very simple mathematical structure and is easy to implement. Numerical simulations and experimental results using a mobile robot in an indoor environment are presented to illustrate the performance of the algorithm. The second section describes the design of a …
Design And Development Of An In-House Scanning Tunneling Microscope System, Esvar Subramanian
Design And Development Of An In-House Scanning Tunneling Microscope System, Esvar Subramanian
All Theses
ABSTRACT
The invention of Scanning Tunneling Microscope (STM) by Binnig and Rohrer in 1982 eliminated the use of optical lenses and replaced the conventional optical microscopes with a new class of microscopes called the Scanning Probe Microscopes (SPM). Because of their unique characteristics such as higher resolution and acquisition of nano level images without affecting the physical properties of the sample, they have found wide applications in a variety of scientific disciplines such as biology, material science and electrochemistry. After considerable advancements in instrumentation, the STM has evolved as a nanomanipulation and nanofabrication tool. It operates in two modes: constant …
Software Development For Mechatronics Systems: Simulation Of Multiple Uav Navigation And Device Driver Interface For The Q4 Data Acquisition Card, Ninad Pradhan
All Theses
Mechatronics systems are often a close interleaving of different aspects of hardware, software, control and mechanical design. Two such aspects are delved into in greater detail for this thesis, both related to software development.
Simulations are used to know the practical conditions under which a control design is effective. The system simulated in this case was a multiple vehicle system, where the vehicles navigated from source to a destination configuration avoiding two different kinds of obstacles.
Post simulation, a system is implemented using hardware and tested using an experimental setup. Data Acquisition Boards such as the Quanser Q4 are used …
Viability, Functionality, And Genetic Assessment Of Cells After Laser Guidance, Tabitha Rosenbalm
Viability, Functionality, And Genetic Assessment Of Cells After Laser Guidance, Tabitha Rosenbalm
All Theses
We systematically vary the controllable laser parameters, namely, wavelength, intensity, and exposure time of the laser on single cells to clearly establish laser parameters that allow negligible cell damage with significant cellular position control. To accomplish this goal, embryonic day 7 (E7) chick forebrains neurons were cultured with control and test cells selected one hour after seeding to allow attachment, at which time test cells were subjected to the laser. Cells were imaged at 4, 12, 24, and 36 hours after laser exposure to evaluate viability and functionality by using the Live/Dead Viability Cytotoxicity Kit (Molecular Probes L3224) and measuring …
An Efficient Analysis Of Vertical Dipole Antennas Above A Lossy Half-Space , Yongfeng Huang
An Efficient Analysis Of Vertical Dipole Antennas Above A Lossy Half-Space , Yongfeng Huang
All Theses
The electromagnetic modeling of radiation by vertical dipole antennas above a lossy half-space has become an important subject due to many applications where these dipoles are involved. The modeling often encounters Sommerfeld-type integrals that are normally highly oscillatory with poor convergence. Recently, an efficient computation of the electric field radiated by an infinitesimal electric dipole above a lossy half-space has been reported, in which the Sommerfeld-type integrals are reduced to rapidly-converging integrals. Taking advantage of such efficiently-calculated electric field and using it as the Green's function, in this thesis, an electric field integral equation (EFIE) is formulated for the analysis …
Minimum Sample Size Needed To Construct Cushion Curves Based On The Stress-Energy Method, Patricia Marcondes
Minimum Sample Size Needed To Construct Cushion Curves Based On The Stress-Energy Method, Patricia Marcondes
All Theses
Cushion curves are graphical tools used by protective package designers to evaluate and choose foamed cushioning materials. Thousands of samples and hundreds of laboratory hours are needed to produce a full set of cushion curves according to the ASTM procedure D 1596. The stress-energy method considerably reduces the number of samples needed to construct cushion curves for closed-cell cushioning materials. Consequently the laboratory and data analysis time are reduced as well.
The stress-energy method was used to find the minimum sample size needed to construct cushion curves for closed-cell cushioning materials. A reference set of data collected for ARCEL Resin¨ …
Optimal Placement Of Metal Foils In Ultrasonic Consolidation Process, Raji Rexavier
Optimal Placement Of Metal Foils In Ultrasonic Consolidation Process, Raji Rexavier
All Theses
Ultrasonic Consolidation is a combination of additive and subtractive
manufacturing processes resulting in considerable material waste. This waste is a
function of the geometry of the part being manufactured and of the relative
placement of the layer with respect to the metal bands. Thus the waste may be
minimized by careful choice of the layer angle and offset from the original
position.
Previous work done in this field had developed an automated algorithm which
optimally places and orients the individual slices of the STL file of the artifact
being manufactured. However, the problem was solved on a 2-D scale and …
Linear And Non-Linear Control Of A Quadrotor Uav, Andrew Neff
Linear And Non-Linear Control Of A Quadrotor Uav, Andrew Neff
All Theses
This thesis describes two controllers designed specifically for a quadrotor helicopter unmanned aerial vehicle (UAV). A linear controller and a non-linear controller are discussed for use on the quadrotor helicopter using feedback that is obtained from microelectromechanical systems and GPS.
The linear controller is an orientation based PID controller that controls the angles of the quadrotor UAV. The controller was first simulated and the results displayed graphically using FlightGear. Experiments were conducted using this controller on a DraganFlyer X-Pro quadrotor helicopter to prove the proposed method used for closing the feedback loop.
The non-linear controller is developed using Lyapunov stability …
Isomap Tracking With Particle Filter, Nikhil Rane
Isomap Tracking With Particle Filter, Nikhil Rane
All Theses
The problem of tracking an object in an image sequence involves challenges like translation, rotation, scaling, varying ambient light and occlusions. A model of an object is built off-line by making a training set with images of the object with different poses. A dimensionality reduction technique is used to capture the variations in the training images. This gives a low-dimensional representation of the data. Isometric feature mapping is the dimensionality reduction technique used to capture the true degrees of freedom in the data. Once the data is reduced to low-dimensions it forms a part of the state-vector of the object. …
Analysis Of Ride Quality Of Tractor Semi-Trailers, Christopher Spivey
Analysis Of Ride Quality Of Tractor Semi-Trailers, Christopher Spivey
All Theses
This thesis develops parameter variation techniques for calculating the set of vehicle parameters that result in the best ride comfort for the driver. The model is a fifteen degree-of-freedom (15 DOF) tractor semi-trailer vertical dynamic ride model. The modeling and simulation techniques used in this thesis are extensions of the research performed by Trangsrud and Vaduri. Features of the model include suspension characteristics for (a) each of the five axles (tractor steer axle, two tractor drive axles, and two trailer axles), (b) tires, (c) a flexible engine mount, (d) the tractor cab, (e) the driver's seat, and (f) a fifth …
Characterization Of The Ibc Technologies Superlig¨ 620 Solid Phase Extraction Resin With Applications For Automated Process Monitoring, John Clements
Characterization Of The Ibc Technologies Superlig¨ 620 Solid Phase Extraction Resin With Applications For Automated Process Monitoring, John Clements
All Theses
Characterization of the IBC Advanced Technologies SuperLig¨ 620 solid phase extraction resin was performed in order to develop an automated strontium-90 process monitor. The main focus was on strontium separation from barium, with the goal of developing an automated separation process for strontium-90 in Hanford high-level tank wastes. High-level waste tanks contain significant cesium-137 activities, of which barium daughters are of great concern as interferences to strontium quantification. A number of complexants were studied in a series of batch distribution coefficient experiments, as SuperLig¨ 620 was not previously known to elute strontium in typical mineral acids. The optimal separation was …
Real Time Prognostic Strategies Application To Gas Turbines, Rajat Sekhon
Real Time Prognostic Strategies Application To Gas Turbines, Rajat Sekhon
All Theses
Gas turbines are increasingly deployed throughout the world to provide electrical and mechanical power in consumer and industrial sectors. The efficiency of these complex multi-domain systems is dependant on the turbine's design, established operating envelope, environmental conditions, and maintenance schedule. A real-time health management strategy can enhance overall plant reliability through the continual monitoring of transient and steady-state system operations. The availability of sensory information for control system needs often allow diagnostic/prognostic algorithms to be executed in a parallel fashion which warn of impending system degradations. Specifically, prognostic strategies estimate the future plant behavior which leads to minimized maintenance costs …
Evaluation Of Different Contra-Flow Strategies For Hurricane Evacuation In Charleston, South Carolina, Liz Stephen
Evaluation Of Different Contra-Flow Strategies For Hurricane Evacuation In Charleston, South Carolina, Liz Stephen
All Theses
The number of category four and five hurricanes has nearly doubled over the past decade. Charleston, the second most populous city in South Carolina, is located on a very low peninsula, making it susceptible to floods during hurricanes and storm surges. In the event of a hurricane, the population at-risk must be evacuated to safety as quickly as possible. The Interstate system is the primary mode to evacuate at-risk population out of Charleston. Effective traffic management strategies are needed to manage the significant increase in demand on highways during the evacuation and contra-flowing traffic has been applied as a strategy …
Design Of A Controller For A Precision Positioning Machine, Joshua Tarbutton
Design Of A Controller For A Precision Positioning Machine, Joshua Tarbutton
All Theses
System identification was used to build an accurate model of a high-precision measurement system. The model built by system identification was compared to modeling by first laws and showed extremely similar results. Pole-placement control design based on the identified system was used to place the systems' dominant poles. The necessary gains to achieve the desired system response were determined by using the identified model and knowledge of the controller structure. The performance of the model-based controller was compared to actual data of the system and showed that control based on the identified model can be used to accurately control the …
Temperature Control Of An Air Shower, Vedik Bobba
Temperature Control Of An Air Shower, Vedik Bobba
All Theses
Accuracy and repeatability in measurement is a primary concern in improving and maintaining the quality of a product in an industry. In the case of coordinate measuring machines, these factors are affected due to the ambient conditions. Specifically, change in temperature affects machine geometry and causes positioning errors. As a result, temperature and humidity control inside the housing has become an important and integrated concern of measuring machine. This research concentrates on the modeling, design, control and validation of an air shower to meet a 20 ± 0.1 ¼C specification.
The optimum performance of the control of temperature of air …
Attestation-Based Remote Biometric Authentication, Thomas Polon
Attestation-Based Remote Biometric Authentication, Thomas Polon
All Theses
Migration from password and token-based authentication in distributed systems requires fundamental changes to the authentication process. A person's biometric data is not a secret, which presents a fundamental difference with other authentication methods. Matching a sample with a database template is secondary to establishing trust in the integrity of the sample. The process is similar to establishing a chain of custody for judicial evidence. In computer systems this is accomplished using attestation architectures. In this paper, a design for a secure remote biometric login system based on an attestation architecture is analyzed. The system uses a commercially available Trusted Platform …
Soar Checkers - An Intelligent Checkers Playing Agent In Soar, Jithu Menon
Soar Checkers - An Intelligent Checkers Playing Agent In Soar, Jithu Menon
All Theses
The classic board game of checkers is ideally suited for research in AI game-playing programs or agents. The objective behind Soar Checkers is to investigate if it is possible to create an agent-based game playing system that would beat novices with ease and at least challenge advanced novice to intermediate-level players by designing a rules-based expert system whose knowledge base consists of nothing more than the rules of checkers, and a set of guidelines for game-play based on good strategy. Soar was chosen as the platform for building this agent because it came built-in with features that facilitate creating rules-based …
Energy Absorption Of Sine Wave Beams Subjected To Axial Impact Loading, Robert Smith
Energy Absorption Of Sine Wave Beams Subjected To Axial Impact Loading, Robert Smith
All Theses
Energy absorbers ideally remove kinetic energy efficiently and reliably while minimizing force magnitudes felt on the moving body. Until now, energy absorber design has concentrated on thin-walled prismatic tubes and tapered tubes. Sine wave beams (SWB) have been previously investigated as energy absorbers under lateral impacting situations only. This thesis investigates the energy absorption of the SWB under axial impact. FE models simulated the energy absorbing response of the SWB. Parametric analyses were performed using the structure's thickness, the web amplitude, and the period number of the web. The SWB's performance is evaluated and then compared to the prismatic structures. …
Extrapolation Of Time And Frequency Responses Of Resonant Antennas Using Damped Sinusoids And Orthogonal Polynomials, James Frye
All Theses
An extrapolation technique is presented which reduces the computational demands of obtaining a wide-band electromagnetic response from a resonant antenna using traditional computational methods. It has been shown that a wide-band response can be extrapolated by fitting early-time and low-frequency data as a summation of orthogonal polynomials. However, because the polynomials provide compact time support, representation of long time responses intrinsic to resonant structures in practice proves inefficient and can lead to numerical instabilities. This thesis outlines incorporating damped sinusoids to efficiently and reliably extrapolate time and frequency responses of resonant antennas due to a wide-band source. A genetic algorithm …
Modeling Requirements Propagation To Generate Solutions For Minimizing Mass, Thulasiram Ezhilan
Modeling Requirements Propagation To Generate Solutions For Minimizing Mass, Thulasiram Ezhilan
All Theses
This thesis investigates the issue of weight reduction in moderately complex systems by addressing how to cascade the requirements to the individual components. Though mass can be reduced using different techniques such as material substitution or structural optimization; a systematic method for allocating mass as a function of requirements is necessary to provide novel alternate solutions that enable reduction of mass of the system while satisfying the requirements and tests governing them. Such a method can be developed by exploring different aspects of achieving weight reduction through change propagation in the parameters/elements governing the system. Though efforts have been made …
Machinability And Microstructure Stability During The Machining Of Pure Copper And Titanium Processed By Equal Channel Angular Pressing, Mason Morehead
Machinability And Microstructure Stability During The Machining Of Pure Copper And Titanium Processed By Equal Channel Angular Pressing, Mason Morehead
All Theses
For ultrafine grained materials (containing microstructures of 100-300 nm) to be manufactured and used in industry, machining research is needed to form and shape these materials into their final dimensions. Because of their high internal energy, UFG materials are known to have microstructures which are susceptible to undesirable changes at low temperatures. In this study, pure ultrafine grained copper and titanium as well as their respective coarse grained (CG) counterparts were tested for their relative machinability and microstructure stability through lathe turning. To evaluate the machinability cutting forces, tool wear, chip morphology, and surface roughness were studied using different cutting …
A Study Of Induced Drag And Spanwise Lift Distribution For Three-Dimensional Inviscid Flow Over A Wing, Scott Monsch
A Study Of Induced Drag And Spanwise Lift Distribution For Three-Dimensional Inviscid Flow Over A Wing, Scott Monsch
All Theses
Numerical results for an untwisted, finite rectangular wing (NACA 0012, AR = 6.7) using no flap deflections are compared against theoretical lifting line predictions. The numerical approach used an Euler-based computational fluid dynamic (CFD) solver. A span-wise lift distribution was extracted from the CFD solution. The comparison between the predicted numerical and lifting-line span-wise lift distributions shows good agreement with a maximum deviation of only 2.4% over the wing span.
The induced drag was extracted from the downstream wake using a wake integral technique referred to as Trefftz plane analysis. The predictions for induced drag based on surface integration, wake …
On The Effects Of Estimation Error And Jitter In Ultra-Wideband Communication , Greta Grizzard
On The Effects Of Estimation Error And Jitter In Ultra-Wideband Communication , Greta Grizzard
All Theses
The opening of the 3.6 - 10.1 GHz frequency spectrum below the 'noise-floor' by the FCC in 2002 has made possible the prospect of reusing this frequency spectrum through ultra-wideband (UWB) communication. In this thesis, we compare the performance of several UWB systems in the presence of estimation error and jitter. We then develop two alternative decision schemes to combat the effect of jitter in the UWB system. Numerical results show that one of the schemes provides significantly better performance in the presence of severe jitter than maximal ratio combining and minimal degradation of performance if jitter is not present. …
Effects Of Ionizing Radiaton On Diaphyseal Cortical Bone, Neil Travis
Effects Of Ionizing Radiaton On Diaphyseal Cortical Bone, Neil Travis
All Theses
Radiation exposure is experienced in both radiotherapy and exploratory space missions. As cancer treatments improve and astronauts aim to explore beyond low earth, radiation's effects on bone must be clearly understood. Nine-week old female C57BL/6 mice were evaluated for cortical bone changes by mechanical testing, micro-computed tomography, quantitative histomorphometry, percent mineralization and micro-hardness indentation. Study one, Multi-Type study, mice received a 2 Gray (Gy) gamma, proton, iron and carbon whole body radiation dose and sacrificed 110 days post-exposure. Study two, High-Dose study, mice received a 7 Gy gamma radiation whole body dose and sacrificed 14 days post-exposure. Neither study revealed …
Study Of Structure Development During Melt Spinning Of Isotactic Polypropylene Fibers Using Raman Spectroscopy And Wide Angle X-Ray Diffraction Simultaneously , Dushyanth Pandana
Study Of Structure Development During Melt Spinning Of Isotactic Polypropylene Fibers Using Raman Spectroscopy And Wide Angle X-Ray Diffraction Simultaneously , Dushyanth Pandana
All Theses
ABSTRACT
Isotactic polypropylene (iPP) fibers have a wide variety of applications. Specific end-use applications require specific properties, which are dependent on the polymer morphology produced during processing. Therefore, the final properties of a material are dependent on the processing parameters. iPP fibers are produced mainly by melt spinning. The important processing parameters in the melt spinning process include, the extrusion temperatures, the throughput and shear rates, the rate of cooling, and the feed and draw roll take-up velocities. An understanding of how the morphology develops along the spinline, and the effect of processing parameters on the morphology is crucial in …