Digital Commons Network^™

Numerical Investigation Of Second-Law Characteristics Of Ramjet Throttling, Jonathan Albert Sheldon

Masters Theses

"A numerical study of a generic axisymmetric ramjet operating at conditions corresponding to flight Mach 3.0 and a standard altitude of 10 km is presented. The study includes both modeling of steady-state flowfields in the ramjet as well as transient throttling maneuvers in which the throttle is decreased or increased from maximum or minimum throttle positions. The results presented here focus on entropy generation and performance characteristics. Combustion-generated exothermic heat release is modeled using simple volumetric energy addition to the flow within a defined heat release zone. The study utilizes two levels of wall boundary modeling, corresponding respectively to inviscid …

Robust Evolutionary Algorithms, Brian Wesley Goldman

Masters Theses

"Evolutionary Algorithms (EAs) have shown great potential to solve complex real world problems, but their dependence on problem specific configuration in order to obtain high quality performance prevents EAs from achieving widespread use. While it is widely accepted that statically configuring an EA is already a complex problem, dynamic configuration of an EA is a combinatorially harder problem. Evidence provided here supports the claim that EAs achieve the best results when using dynamic configurations. By designing methods that automatically configure parts of an EA or by changing how EAs work to avoid configurable aspects, EAs can be made more robust, …

Investigation Of Drillstring Vibration Reduction Tools, Mohammed Fayez Al Dushaishi

Masters Theses

"Drilling related problems such as drillstring vibration is an important cause of premature failure of drillstring components and drilling inefficiency. The vibration of drillstring interferes with measurement collected while drilling. In severe cases, drillstring vibration will lead to wellbore instability that will result in an increase in the operation cost. In the late 1980's, a lot of studies and techniques were developed to mitigate drillstring vibration and downhole vibration measurements were introduced to the industry in two forms; real time measurements and memory devices measurements

A study of drillstring vibration of three different wells located in the Norwegian North Sea …

Maximum Power Point Tracking Control Of Hydrokinetic Turbine And Low-Speed High-Thrust Permanent Magnet Generator Design, Hailong Zhou

Masters Theses

"River-based hydrokinetic turbine power generation systems have been studied to introduce an effective energy flow control method. Hydrokinetic turbine systems share a lot of similarities with wind turbine systems in terms of physical principles of operation, electrical hardware, and variable speed capability for optimal energy extraction. A multipole permanent magnet synchronous generator is used to generate electric power because of its ability to reach high power density and high thrust at low speed. A 3-phase diode rectifier is used to convert AC power from the generator into DC power and a boost converter is used to implement energy flow control. …

Physiochemical Characteristics Contributing To The Cytotoxicity Of Transition Metal Oxides, Chi-Heng Wu

Masters Theses

"In the past ten years nanotechnology has not only evolved to play a prominent role in our economy but also increased the concern over potential adverse effects caused by nanomaterials to human health and the environment. Nanotoxicity is to understand the nature and origin of the toxicity imposed by nanomaterials. Studies from our laboratory have shown that nanoparticle induces oxidative stress, perturbs calcium homeostasis, alter gene expression, and produces pro-inflammatory responses. We also identified a trend of toxicity: TiO₂ < Cr₂O₃ < Fe₂O₃ < Mn₂O₃ < NiO < ZnO < CuO. We then asked a question: what are physiochemical factors of transition metal nanoparticles that contributed to this increasing cytotoxicity. In this thesis I investigated the correlation between physicochemical properties and toxicity of the transition metal oxides in the 4th Period of the Periodic Table of Elements. Particle size, BET surface area, point of zero charge, metal dissolution, and degree of surface adsorption of transition metal oxide nanoparticles were measured. There were no increasing trends in both particle size and specific surface area. The point of zero charge showed an increasing trend as TiO₂ < Cr₂O₃ < Fe₂O₃ < NiO < CuO = ZnO < Mn₂O₃. The number of available binding sites of nanoparticle showed an increasing trend as Cr₂O₃ > ZnO > CuO > NiO > Fe₂O₃ > Mn₂O₃ > TiO₂. The degree of adsorption on the surface of nanoparticles showed an increasing trend with atomic …

Gray Gas Analysis Of Radiative Preheating Effects On Shock Induced Combustion, Pratibha Raghunandan

Masters Theses

"The use of detonations in combustors has been receiving increased attention in recent times. The presence of shock waves in such combustors invariably poses the existence of two domains that present different physics for the flow processes. The variation of upstream temperature due to radiative heating by the products of combustion was given particular attention in the present study. The modeling of heat transfer across a normal shock wave of negligible thickness was done by considering the reactants and the products of combustion to be in radiative equilibrium with each other. The quantification of emissivity of the products of combustion …

Multiple-Input Multiple-Output System On A Spinning Vehicle With Unknown Channel State Information, Aditya Muralidhar

Masters Theses

"This thesis work presents the investigations into the performance of a multiple-input multiple-output (MIMO) system with its transmitters on a spinning vehicle and no available channel state information (CSI) at the transmitter or the receiver. The linear least squares approach is used to estimate the channel and the estimation error is measured. The spinning is simulated based on a sample radiation pattern of a patch antenna. The antenna gains at different angles are obtained from this pattern and are used to model spinning. Spinning gives rise to a periodic component in the channel which can be estimated based on the …

3d Spatio-Temporal Analysis For Compressive Sensing In Magnetic Resonance Imaging Of The Murine Cardiac Cycle, Brice Aaron Hirst

Masters Theses

"This thesis consists of two major contributions, each of which has been prepared in a conference paper. These papers will be submitted for publication in the SPIE 2013 Medical Imaging Conference and the ASEE 2013 Annual Conference.

The first paper explores a three-dimensional compressive sensing (CS) technique for reducing measurement time in MR imaging of the murine (mouse) cardiac cycle. By randomly undersampling a single 2D slice of a mouse heart at regular time intervals as it expands and contracts through the stages of a heartbeat, a CS reconstruction algorithm can be made to exploit transform sparsity in time as …

Parametric Moment Closure For Non-Linear State Dependent Stochastic Systems, Ritesh Arora

Masters Theses

"This research highlights the use of moment closure approximation techniques to provide analytical approximations to nonlinear state dependent systems. Nonlinear systems are often difficult to solve and often approximated through the use of simulation. However, Moment Closure has the capability to derive an approximate solution by making a closed form solution out of open set of differential equations representing nonlinear system behavior in both transient and equilibrium state. It is this capability of approximating the closed form solution to complex systems that draws interest in the use of this method within systems engineering. This research further extends to the stability …

Effect Of Side Edge Distance And Concrete Materials On Corrosion In Precast Prestressed Concrete Panels, Dayi Zhang

Masters Theses

"This study involved the spalling problem found in some partial-depth precast prestressed bridge decks in the state of Missouri. Recently, panels of several bridges have exhibited corrosion of the prestressing steel tendons causing concrete spalling at the edges of panels. Some of the exposed tendons are corroded to the point of rupture. The effect of factors, namely concrete side edge distance and concrete material type, on steel corrosion in chloride-contaminated reinforced concrete was investigated in this study. Wet-dry cycle tests and accelerated corrosion tests were carried out on sixty-three specimens designed with three different side edge distances and three different …

Distributed And Collaborative Watermarking In Relational Data, Prakash Kumar

Masters Theses

"Watermarking relational data is an important topic in the field of copyright protection, given the increasing prevalence of piracy and illegal duplication of databases. While there exists solutions for watermarking relational data, the problems that arise due to multiple ownership (two or more) of databases have not been acknowledged. This research focuses on developing a novel watermarking scheme to counter the problems. The watermarking scheme proposed necessitates the owners of the database in consideration to come together to perform the watermarking process. The scheme can be applied to insert watermarks in both numerical and categorical data. The watermarking scheme is …

Coaxial Cable Bragg Grating, Jie Huang

Masters Theses

"In order to ensure the continued safe and reliable operation of various civil structures, such as dams, bridges, and buildings, in situ strain monitoring is of great importance, especially for structures that may experience large strains. A new coaxial cable Bragg grating (CCBG) is developed as a strain sensor and the sensor's capacity for large range strain measurement is demonstrated for the first time. The sensor device is comprised of regularly spaced periodic discontinuities along a coaxial cable. The discontinuities are fabricated using a computer numerical controlled (CNC) machine to drill holes in the cable. Each discontinuity generates a weak …

Microstructure And Mechanical Properties Of Silicon Carbide-Titanium Diboride Ceramic Composites, Derek Scott King

Masters Theses

"The microstructure, hardness, fracture toughness, Young's modulus, strength and Weibull modulus of silicon carbide-titanium diboride (SiC-TiB₂) ceramics were studied. First, SiC-TiB₂ ceramics with 15 vol.% TiB₂ particles were processed using two green processing methods, spray drying (ST) and ball milling (SiC-15TiB₂). In addition, SiC-TiB2 ceramics with TiB₂ contents ranging from 0 to 100 vol.% were produced to determine a TiB₂ content that produced the best combination of mechanical properties. From spray drying, segregation of the TiB₂ particles in ST led to a granule-like microstructure and spontaneous microcracking in the final ceramic. In ceramics containing 20 and 40 vol.% TiB₂, the …

A Novel Cantilever For Bi-Harmonic Atomic Force Microscopy, Muthukumaran Loganathan

Masters Theses

"Tapping mode (TM) AFM is a popularly used AFM technique in which an oscillating sharp tip mounted on a micro cantilever is used to probe the surface of interest with nanoscale resolution by making intermittent (tapping) contact with the surface. Any change in surface profile affects the tip amplitude, and is detectable only if it results in an amplitude change that is significant enough to be measured by the laser detector. Hence, it is desirable to have a micro cantilever that is sensitive to surface changes so as to provide sharper images and better surface resolution.

In the first part …

Design Of A Vortex Induced Vibration Based Marine Hydro-Kinetic Energy System, Varun Michael Lobo

Masters Theses

"Hydrokinetic energy harvesting based on vortex induced vibration (VIV) of a bluff body is discussed. VIV is defined as the vibration incurred on a bluff body due to an external fluid flowing over it. These vibrations are the results of boundary layer separation from the surface of the body. An optimized VIV generator has been developed, that utilizes a non-contact type linear magnetic device for generation of energy. The cylinder was chosen such that at the mass ratio (m*) was always lower than the critical mass (m*_critical= 0.52). The studies were based on two complementary …

Transient Growth And Instability Control Using Iteration-Varying Filter Ilc In Flexible Dual Flywheel System, Tong Mu

Masters Theses

"In the field of precision motion control, many industrial systems have flexible modes. This is especially true for very high performance nanopositioning systems where traditional bearing systems are replaced with flexible structures in order to eliminate sliding friction. The precision motion control is difficult in flexible systems because the rapid phase transition around the resonant frequency must be accurately modeled in order to actively control the resonant motion. In order to experimentally study the effectiveness of various control algorithms on flexible systems, a dual-flywheel flexible system is constructed. The mechatronics system design strategy is presented in this thesis. The control …

Integration Of Multiple Vision Systems And Toolbox Development, Rohit Vijay Bapat

Masters Theses

"Depending on the required coverage, multiple cameras with different fields of view, positions and orientations can be employed to form a motion tracking system. Correctly and efficiently designing and setting up a multi-camera vision system presents a technical challenge. This thesis describes the development and application of a toolbox that can help the user to design a multi-camera vision system. Using the parameters of cameras, including their positions and orientations, the toolbox can calculate the volume covered by the system and generate its visualization for a given tracking area. The cameras can be repositioned and reoriented using toolbox to generate …

Vehicle Path Verification Using Wireless Sensor Networks, Gerry W. Howser

Masters Theses

"Path Verification is a problem where a verifier would like to determine how closely a vehicle actually traversed a path that it claims to have traversed. This problem has critical significances in terms of vehicle mobility. Mobile nodes can be patrols officers or cab drivers, while respective verifiers can be police dispatchers or cab operators. In this paper, we design a sensor network assisted technique for vehicle path verification. In our design, a number of static wireless sensors placed in road segments will serve as witnesses and certify vehicles as they move. Post movement, these witness certificates will be utilized …

A Digitally Implemented Practical Photovoltaic Simulator With A Double Current Mode Controller, Jie Ang Zhao

Masters Theses

"This thesis presents a microcontroller- and DC-DC converter-based photovoltaic (PV) simulator which emulates the output characteristic of a PV module. The current-voltage (IV) characteristic of a PV module is implemented as a look-up-table that generates an output reference current based on a measured output voltage. The control mechanism is based on a double current mode controller that consists of a predictive current mode controller and a proportional-integral (PI) controller arranged in an inner loop and outer loop configuration. The PI controller is designed based on classical phase margin and gain margin criteria to ensure system stability. The performance of the …

Investigation Of Geosteering In Non-Trivial Geological Settings, Anuroop Pandey

Masters Theses

"The well placement technology has advanced to a stage where we can explore small tolerance targets such as thin reservoirs. Well placement with geosteering, which is the real time adjustment of the well path based on the geological responses to place and maintain the well within the best part of the reservoir, is the technology that has made this progress possible. Geosteering however can get very complex with the increasing heterogeneities of the formations and there is no fixed methodology to devise a steering strategy in such complex geological settings. To accommodate this challenge, we investigated three methods to verify …

Path Planning For General Mazes, Grant Gilbert Arthur Rivera

Masters Theses

Path planning is used in, but not limited to robotics, telemetry, aerospace, and medical applications. The goal of the path planning is to identify a route from an origination point to a destination point while avoiding obstacles. This path might not always be the shortest in distance as time, terrain, speed limits, and many other factors can affect the optimality of the path. However, in this thesis, the length, computational time, and the smoothness of the path are the only constraints that will be considered with the length of the path being the most important. There are a variety of …

Reliability Evaluation Of Distribution Systems Containing Renewable Distributed Generations, Abdulaziz Abddullah Alkuhayli

Masters Theses

Reliability evaluation of distribution networks, including islanded microgrid cases, is presented. The Monte Carlo simulation algorithm is applied to a test network. The network includes three types of distributed energy resources solar photovoltaic (PV), wind turbine (WT) and gas turbine (GT). These distributed generators contribute to supply part of the load during grid-connected mode, but supply the entire load during islanded microgrid operation. PV and WT stochastic models have been used to simulate the randomness of these resources. This study shows that the implementation of distributed generations can improve the reliability of the distribution networks.

Stochastic Model For Solar Sensor Array Data, Faris Alfaris

Masters Theses

Statistical approaches are often used in time series analysis, for example, to predict the future trend of a time series. Trend forecasting can be applied in many time related parameters such as: solar radiation, generation of electricity and other variables related to time series to improve the efficiency and to set the design requirements. Since the design of any solar energy system requires knowledge of the availability of solar radiation data at the location of interest. Therefore, this research seeks the application of a statistical model to fit the solar radiation time series and predict the future values. There are …

Force Sensing Of An Asymmetric Dielectric Barrier Discharge Using Mechanical Resonators, Mark Dawson Emanuel

Masters Theses

"Dielectric barrier discharge (DBD) plasma actuators are of great interest in flow control research and application. DBD plasma actuators are low-cost, lightweight, high voltage devices that have the capability of generating small amounts of thrust on the order of a few tenths of a gram. The thrust is created by rapidly pulsing plasma discharges which correlate to the frequency of the applied alternating current waveform, in the low kilohertz range.

Plasma actuators experience a reactant force generated by the pulsed plasma charging and then expelling air away from the charged surface. This force fluctuates with time as the plasma is …

Automatic Detection Of Annular-Granular Patterns In Melanoma In Situ Dermoscopy Images, Parivash Hajiyani

Masters Theses

"Early detection of malignant melanoma greatly benefits patients, as the overall success is dependent on finding these melanomas before they reach the invasive stage. Dermoscopy is a non-invasive skin imaging technique that studies have shown can improve the diagnostic accuracy of dermatologists by as much as 30% over clinical examination. In this project machine vision and image analysis techniques are used to detect annular granular areas in dermoscopy images automatically. The proposed algorithm utilizes the luminance ratio between annular and granular areas within the darkest 30% of the lesion. All points whose luminance value are less than 30% of the …

Advanced Moisture Modeling Of Polymer Composites, Nathan Robert Roe

Masters Theses

"Composite materials absorb moisture from the environment and over time this moisture absorption affects the mechanical performance of the material. In order to determine the long-term moisture effects on the component, representative parts must be tested after having been exposed to an accelerated moisture-conditioning environment. This accelerated environment simulates the worst-case exposure conditions that a part might experience. Currently accepted methodologies for analyzing the time required to condition specimens are limited, only allowing simple geometry and an assumption that diffusivity rates are independent of the flow path or direction. Therefore, a more advanced finite element method is desired. In the …

Under Pressure: A Psychophysiological Analysis Of The Effect Of Temporal Constraints On Information Processing And Decision Making, Nagaratna Krishna Sneha Pochinapeddi

Masters Theses

"In recent times, decision making under time pressure has become more common than ever and hence, it has become a hot topic for behavioral researchers. This research studies the effects of temporal constraints on users' decision quality and decision strategy. The paper primarily addresses two research questions: (i) Does time pressure affect decision quality? (ii) Does time pressure affect decision strategy? The decision accuracy and decision strategy of the participants were measured for three time-pressure conditions namely, No time pressure, Reasonable time pressure and Extreme time pressure. Research results from the past revealed that, Cognitive style is also observed to …

Enabling Frequency And Voltage Regulation In Microgrids Using Wind Power Plants, Anshuman Shrikant Vaidya

Masters Theses

"Renewable energy sources, like wind can be used to augment the grid-friendly services in the form of additional active and reactive power for control of frequency and voltage regulation. Currently, wind power systems are operated in simple energy supply mode and are not utilized to participate in ancillary power services. With the increase in the installed wind power capacity, limited conventional generation and increasing interest in microgrids, the necessity to implement regulation support from wind energy becomes critical. This thesis focuses on the effect of enabling frequency and voltage regulation capability in wind power plants in a microgrid environment. This …

Dynamic Model-Based Systems Engineering Using Xml Metadata Interchange, Dustin Scott Nottage

Masters Theses

"Designing systems presents an engineer with numerous design choices based on multiple conditions and constraints. Base camp planning must take into account the number of soldiers, the permanency of the base, the location of the base, etc. To help alleviate the complexity of constructing a base camp, a model-based systems engineering approach is used. This method creates and integrates models for all of the facilities that can make a base camp, as well as interactions between facilities and required utilities for each. The goal is to have a camp design, and then solve a system of equations to solve for …

Palynomorph And Palynofacies Assemblages Of Neutral-Alkaline And Acid Lakes South Of Norseman, Southern Western Australia, Lutfia Grabel

Masters Theses

"The Yilgarn Craton in Western Australia hosts hundreds of shallow ephemeral hypersaline lakes, the majority of which have acid to neutral pH values. As part of a multidisciplinary study of the evolution of hypersalinity and acidity in the region, three drill cores were studied for their palynofacies and palynomorph contents in order to characterize palynofloral response to environmental changes. Drill cores from two acid lakes, Prado Lake (PL1-09 and PL2-09) and Twin Lake West (TLW1-09), and the neutral-alkaline Gastropod Lake (GLE1-09) south of Norseman recovered Miocene to Holocene sediments of the Revenge and Polar Bear formations. Transmitted light microscopy was …