Digital Commons Network^™

Computational Investigation Of Plasma Actuator As An Active Flow Control Strategy Of Laminar Separation Bubbles, Justin Roger Aholt

Masters Theses

"A parametric computational study designed to examine the plausibility of an external body force generated by active means, such as a plasma actuator, as a means of controlling a Laminar Separation Bubble (LSB) over an airfoil at low Reynolds numbers was conducted. Computational Fluid Dynamics (CFD) was employed to characterize the effect that a body force, localized to a small region tangent to the airfoil surface, might have on an LSB. In this study, the effects of altering the strength and location of the "actuator" on the size and location of the LSB and on the aerodynamic performance of the …

Managing A Solar Sensor Array Project: Analyzing Insolation & Motivation, Beth A. Yount

Masters Theses

"The renewable power industry is rapidly growing today and is in need of much data to augment the advancement of the field. Photovoltaic technology, while making substantial improvement over the last 60 years, still has some significant hurdles to overcome. When shading, dust, or damaged cells reduce the power output of one panel, the traditional series-parallel configurations make it so every panel in series with that lower current panel, will also have its current lowered; this lowers the overall power output of the array significantly. Advancements in configurations and converters could change this phenomenon and dramatically increase a solar array's …

Numerical Comparison Of Thermal And Kinetic Modification Of Hydrogen And Oxygen, John Benjamin Gaither

Masters Theses

"This document describes a new modeling technique used to compare thermal and kinetic modification of hydrogen and oxygen gas. The thermal model uses an equilibrium thermodynamic analysis to determine the heat required for given mole fractions of molecular and dissociated products. A kinetic model is developed for a mono-energetic electron beam and a Maxwellian energy distribution. The kinetic model uses electron impact cross sections for excitation, dissociation, and ionization tabulated from available source data between 0-1000 eV. Cross sections are used to calculate forward reaction rates, electron penetration depths, and associated product concentrations for excited, dissociated, and ionized species. The …

3-Dimensional Computational Fluid Dynamics Modeling Of Solid Oxide Fuel Cell Using Different Fuels, Sachin Laxman Puthran

Masters Theses

"Solid oxide fuel cell (SOFC) technology has been of great interest over many years due to its flexibility in using different fuels for operation; including the fundamental fuel i.e. Hydrogen. Various computational and numerical models have been developed along with experimental work to evaluate the performance as well as to identify and overcome the problems faced in the development of SOFC's. In an attempt to achieve efficient operation with respect to design and combined thermal and electrochemical perspective, the main objective of the proposed study is to present a three-dimensional computational model, which will serve as a framework for the …

Analysis And Modeling Of Depth-Of-Cut During End Milling Of Deposited Material, Haythem Gaja

Masters Theses

"This study addresses depth-of-cut detection and tool-workpiece engagement using an acoustic emission monitoring system during milling machining for a deposited material. Online detection of depth-of-cut presents many technical difficulties. Researchers have used various types of sensors and methods to assess the depth-of-cut and surface errors. Due to the strong correlation between acoustic emission and cutting depth during the depth end milling process, it is useful to forecast the depth-of-cut from the acoustic emission signal. This work used regression analysis to model and detect the depth-of-cut. The experiments were carried out on a Fadal vertical 5-Axis computer numerical control machine using …

Quantifying Model Uncertainty Using Measurement Uncertainty Standards, Harsheel Rajesh Shah

Masters Theses

"Model uncertainty quantification is mainly concerned with the problem of determining whether the observed data is consistent with the model prediction. In real world, there is always a disagreement between a simulation model prediction and the reality that the model intends to represent. Our increased dependence on computer models emphasizes on model uncertainty which is present due to uncertainties in model parameters, lack of appropriate knowledge, assumptions and simplification of processes. In addition, when models predict multi-variate data, the experimental observation and model predictions are highly correlated. Thus, quantifying the uncertainty has a basic requirement of comparison between observation and …

Optimization Of Textual Affect Entity Relation Models, Ajith Cherukad Jose

Masters Theses

"Affective computing is a recent research area in computer science which deals with the design and development of systems that can recognize, interpret and process human affects/emotions. Various research projects in the past have focused on affect sensing and processing raw textual data. One such research effort conducted at the Oak Ridge National Laboratory (ORNL) has introduced an affect propagation algorithm which can generate affective relationships between entities contained in a given textual document. The algorithm depends upon a set of real-valued numeric parameters for which the best possible values are unknown. This thesis describes three different contributions to ORNL's …

Meloc - Memory And Location Optimized Caching For Mobile Ad Hoc Networks, Lekshmi Manian Chidambaram

Masters Theses

"The advancement of Mobile ad hoc networks (MANET) is tremendous in the field of social and military applications. Caching and Replication are the two common techniques used to improve data access efficiency in Mobile Ad hoc networks. Caching favors data access efficiency by bringing data closer to the source. Existing caching approaches are deficient in reducing the number of cache locations, thus reducing the number of copies, which is needed for many mission critical applications considering safety and security. Conversely, reducing the number of caches should not affect the efficiency of data access. We design an efficient broker based caching …

Simultaneous Measurement Of Temperature And Strain By Three-Section Phase-Shift Long Period Fiber Grating, Hongbiao Duan

Masters Theses

"Long period fiber gratings (LPFGs) have found many applications as sensors to measure strain, temperature, refractive index and other physical parameters. In various sensing applications, the cross-sensitivity between two parameters, especially the temperature cross-sensitivity, has been a major difficulty to achieve high accuracy measurement. One of the solutions is to develop LPFG sensors for simultaneous, multi-parameter measurements.

In this thesis, three-section phase-shift (PS) LPFGs were fabricated and investigated for simultaneous measurement of temperature and strain. Compared with a two-section PS-LPFG, a three-section PS-LPFG has two deeper resonance sub bands and a larger separation between the two bands. The strain, temperature …

Rapid Simulation Of The Statistical Variation Of Crosstalk In Cable Harness Bundles, Xiang Li

Masters Theses

"Accurate assessment of crosstalk problems in cable harnesses requires simulation methods that account for the statistical variation of harness parameters. Methods are proposed to determine the influence of the statistical variation in wire positions, the rate that wires change position (i.e. "twist"), harness height, harness density (i.e. how closely wires are packed) and circuit loads. Methods use a combination of simulation and probability theory. Simulations use the T-parameter method, a rapid simulation technique for harness bundles. Simulation time is further improved by using the mean and variance of crosstalk estimated for fixed harness parameter values to estimate the mean and …

Mutation Of The Hof1 Pest Domain Affects Cytokinesis In Budding Yeast, Katherine E. Stockstill

Masters Theses

"Cytokinesis is the division of a cell into two daughter cells. Cytokinesis failure results in polyploidy, which may contribute to tumorigenesis or cause cell death. The Saccharomyces cerevisiae protein Hof1, which is required for efficient cytokinesis, is phosphorylated during mitosis. The hypothesis that MEN (mitotic exit network) dependent phosphorylation regulates Hof1 degradation, triggering completion of cytokinesis was tested. Hof1 contains a PEST sequence, which is rich in proline, glutamic acid, serine, and threonine, and is believed to be involved in protein degradation. To test the hypothesis, we created two non-phosphorylatable mutants of the Hof1 PEST domain tagged with GFP. The …

Thermo-Physical Properties Measurement And Steel - Ceramic Shell Interactions In Investment Casting, Chirag Mahimkar

Masters Theses

"Investment casting is a process in which a ceramic shell is prepared on a wax or foam pattern. The wax is melted out or the foam is burnt out and the shell is sintered to have sufficient strength to withstand casting conditions. The investment casting process is very important as it produces near net shape castings which reduce the need for subsequent operations of castings like machining etc. Investment casting shells are subjected to a number of heating cycles during pattern removal, firing, preheating before pouring and finally during solidification. The thermo-physical properties of the shell play an important role …

Contrast Enhancement Of Digital Mammography Based On Multi-Scale Analysis, Muhammad Imran Khan Abir

Masters Theses

"A contrast enhancement algorithm is developed for digital mammograms aiming to assist radiologists in discerning early breast cancer easily. The algorithm is based on a Laplacian pyramid framework image processing technique. The mammogram is decomposed into three frequency sub-bands, low, mid, and high frequency sub-band images. The lower sub-band image contains very fine details and higher level contains coarser features. In this method contrast enhancement is achieved from high and mid sub-bands by decomposing the image based on multi-scale Laplacian pyramid and enhance contrast by image processing. Several mapping functions are applied on sub-band images based on experimental analysis. After …

Numerical Simulation Of Relative Permeability Modifier Effect On Oil And Water Production, Murad Mohammedahmed Abdulfarraj

Masters Theses

"Excess water production is one of the most prevalent operational problems that oil companies are facing. Polymers and polymer gels have been used widely to control excess water production for mature oilfields. It is well known that polymers/gels can reduce the permeability to water (Krw) much more than that to oil (Kro). This phenomenon is called disproportionate permeability reduction (DPR) and the polymers or gels that exhibit this behavior are called relative permeability modifier (RPM). When RPMs are placed in reservoir, reduced permeability to water can lead to decreased water production, and sometimes increased hydrocarbon production, therefore prolonging the useful …

Evaluating The Effectiveness Of Multi-Spectral Remote Sensing Data For Lithological Mapping In Arid Regions: A Quantitative Approach With Examples From The Makkah Neoproterozoic Region, Saudi Arabia, Nawwaf Awad Al Muntshry

Masters Theses

"This work quantitatively evaluates the effectiveness of multi-spectral remote sensing data for geological mapping in arid regions. For this, Landsat Thematic Mapper (TM) data covering part of the Neoproterozoic Arabian Shield around the Makkah region in Saudi Arabia are used. The Makkah region is dominated by a variety of layered and intrusive rocks covered by unconsolidated sediments. The Landsat TM data have six spectral bands in the visible and near infrared (VNIR) and shortwave infrared (SWIR) with thirty meters spatial resolution.

The Optimum Index Factor (OIF) has been computed to determine the best Red-Green-Blue (RGB) band combination emerging from the …

Calcium Wire Ladle Treatment To Improve Cleanliness Of Centrifugal Cast Steel, Edith Yolanda Martinez Silva

Masters Theses

"Centrifugal casting provides the opportunity of combining large centrifugal forces and directional solidification to reduce non-metallic inclusions in the cast steel product. Calcium treatment in the ladle has the potential of reducing and modifying non-metallic inclusions to achieve better machinability and mechanical properties. The objective of this research is to analyze the combined effects of calcium wire ladle treatment and centrifugal casting on the number, size, composition and morphology of non-metallic inclusions in centrifugally cast steel products.

All experiments were completed at an industrial foundry. The experiments involved feeding calcium wire into the ladle after argon oxygen decarburization (AOD) and …

Eyes Don't Lie: Understanding Users' First Impressions On Website Design Using Eye Tracking, Sirjana Dahal

Masters Theses

"Websites are becoming more prevalent these days. They need to create a favorable first impression on the users during initial exposure. After allocating their attention to stimuli, users form a cognitive representation of the visual information leading to first impression. Hence, first impression is important to evaluate the effectiveness of a website. This research tries to examine the amount of exposure time needed to form first impression; identify the web design factors that influence the formation of users' first impression; study the emotional responses of users on website design; and finally understand the relationship between first impression and eye movement. …

Production And Characterization Of Supported Palladium Nanoparticles On Multiwalled Carbon Nanotubes By Gamma Irradiation, Jessika Viviana Rojas Marin

Masters Theses

"Carbon nanotubes are being studied for a variety of applications due to their outstanding mechanical, chemical, electrical, and optical properties that make them interesting in different areas. Nowadays, different methods to modify the structure of the nanotubes are being developed in order to expand the application fields of such materials. In this work, palladium nanoparticles were directly produced and supported on multi-walled carbon nanotubes (MWCNT) by gamma irradiation. A solution with a 2:1 water-isopropanol ratio was prepared and mixed with palladium chloride as precursor of palladium ions. Radiolysis of water produces certain species that reduce the ions down to a …

Categorization And Experimental Evaluation Of Anchorage Systems For Fiber-Reinforced Polymer Laminates Bonded To Reinforced Concrete Structures, Stephen V. Grelle

Masters Theses

"While externally-bonded fiber-reinforced polymer (FRP) composites are commonly used for the strengthening of structurally deficient reinforced concrete (RC) members, the topic of anchoring FRP to concrete to achieve higher design strengths has not been addressed. Many innovative systems have been developed to anchor FRP to concrete, but the research involving these anchorage systems is not centralized and is therefore difficult to access. Additionally, systematic testing procedures for evaluating the strength of an anchorage system have not been widely used. To aid in the organization of anchorage system research and facilitate a better understanding of anchorage system behavior, a categorization system …

Development And Testing Of Chemically-Based Self-Consolidating Concrete, Mark Daniel Ezzell

Masters Theses

"Self-consolidating concrete (SCC) possesses several characteristics that can benefit the concrete construction industry including accelerated construction, a reduction in labor and equipment, and a reduction in construction noise through eliminating or reducing the need to vibrate the concrete. However, SCC has some potential downsides. These problems can usually be attributed to higher paste content, higher fines content, rounder aggregate, and higher water to cement (w/c) ratios used to increase the flow of the concrete. The goal of this research project was to develop a SCC that had improved material properties through the use of chemical admixtures instead of modifications to …

Integration Of Model-Based Systems Engineering And Virtual Engineering Tools For Detailed Design, Akshay Kande

Masters Theses

"Design and development of a system can be viewed as a process of transferring and transforming data using a set of tools that form the system's development environment. Conversion of the systems engineering data into useful information is one of the prime objectives of the tools used in the process. With complex systems, the objective is further augmented with a need to represent the information in an accessible and comprehensible manner. The importance of representation is easily understood in light of the fact that the stakeholder's ability to make prompt and appropriate decisions is directly related to his understanding of …

Design Of A Current Probe For Measuring Ball-Grid-Array Packaged Devices, Tianqi Li

Masters Theses

"A current probe to measure BGA ball currents via magnetic induction has been designed. The probe is manufactured on a 4 layer flex circuit and has been validated by full wave simulations and measurements. The feature size of the probe is very tiny that it almost pushes the limit of flex-circuit technology. Several critical manufacturing problems were happened, and they have been solved now. The probe allows measuring currents of a 1 mm pitch BGA ball directly. Its operating frequency stretched from tens of MHz up to 3GHz. The BGA probe's mutual inductance is approximately 11 pH, and with amplifiers …

Effect Of Initial Conditions On Molecular Mixing In A High Schmidt-Number Rayleigh-Taylor Mixing Layer, Lakshmi Ayyappa Raghu Mutnuri

Masters Theses

"Characterizing molecular mixing in Rayleigh-Taylor instability (RTI) driven flows where the density and velocity fields are coupled is essential for developing exacting predictive models. Sensitivity of the Rayleigh Taylor mixing layer to initial conditions is a topic that is being explored extensively in interests of accurate turbulent mix model development and its direct consequence in various applications like design of inertial confinement fuel capsule and atmospheric modeling. As part of the current work, an experimental investigation of the effect of initial conditions on molecular mixing in a low Atwood number(~7.5 x 10⁻⁴), high Schmidt number(~1000), RTI driven mixing layer is …

Effect Of Nickel On Castability Of Chromium Molybdenum Steel & The Dynamic Fracture Toughness Of Hy-130, Abhilash Dash

Masters Theses

"The fill lengths of Ni alloyed Cr-Mo steels obtained from fluidity studies (Paper 1) varied linearly with superheat. A 5% Ni steel showed a maximum fill length compared to other steels tested. Ni decreased the liquidus, solidus, and dendritic coherency temperature, but it did not have any significant effect on volume fraction (0.27-0.31) of the solid phase at the dendrite coherency point. The filling time obtained experimentally at 150 C⁰ superheat for 5% Ni steel (HY 130) was close to 1.4 s. For similar conditions, the predicted fill time using a Magmasoft model was close to 1.9 s. Modeling results …

Comparison Of Matrix Pencil And Prony Analysis For Estimating Electromechanical Modes In Noisy Signals For Power System Applications, Lisa L. Grant

Masters Theses

"As modern power systems continue to grow and evolve, accurate system stability analysis and oscillation control become increasingly important to guarantee system security. Network instability due to power system oscillations caused by the natural modes of the system is becoming a common occurrence. Modal analysis techniques can estimate the eigenvalues of large nonlinear systems from their dynamics responses. The extracted modal information can be applied to detect low frequency oscillations and assess stability margins for power system monitoring and preventive control. Modal information is also useful for low-frequency oscillation damping controller design. This thesis examines two techniques for modal identification …

Assess Commercialization Feasibility Of Algae-Based Bio-Fuel With Dashboard And Scorecard Technologies, Madhur Chopra

Masters Theses

"The growing energy depleting energy supplies and increasing environmental pollution has motivated researchers across the globe to look for alternative energy sources. Various energy sources have been identified but none of them have the capability of realistically replacing the fossil fuels and meeting the current demand. Algae based bio-fuels give some hope but producing them at large scale is a challenge which needs to be overcome.

The underlying objective of this research project is two folds. Firstly, the project aims to assist with the commercialization of algae based bio-fuels by developing Dashboard based and Balanced Scorecard based monitoring prototypes. The …

Airline Revenue Management Using A Semi-Markov Critic Algorithm, Ketaki Dilip Kulkarni

Masters Theses

"This thesis presents a novel semi-Markov actor-critic algorithm to solve the airline revenue management (ARM) problem. The ARM problem has been the subject of much research since the deregulation of the airline industry in 1978. Various heuristics and numeric techniques have been developed and continue to be developed for solving this problem, but the search for more efficient techniques is still ongoing. This work focuses on the single-leg ARM problem modeled as a semi-Markov decision problem (SMDP). For Markov decision problems that suffer from the curses of dimensionality and modeling, it is difficult to obtain solutions with classical dynamic programming. …

Geological And Geomorphological Evolution Of The Egyptian Nile Between Aswan And Kom Ombo: A Remote Sensing And Field Study Approach, Leslie Lansbery

Masters Theses

"This work uses field and remote sensing studies to examine structural controls of the Egyptian Nile between Aswan and Kom Ombo (referred here to as AKN). This segment of the Egyptian Nile incises through Cretaceous Nubian sandstone and Precambrian crystalline rocks separated by a shallowly-dipping to theN unconformity. It was only 0.8 Ma that the Egyptian Nile connected to the rest of the sub-Sahara Africa drainage system. Prior to this time, the Egyptian Nile evolved independently through 8 phases: Pre-Eonile (Ma), Eonile (6.0-5. 4 Ma), Gulf Phase (5.4-3.3 Ma), Paleonile Phase (3.3-1.8 Ma), Desert Phase (1.8-0.8 Ma), Prenile Phase (0.8-0.4 …

Experimental Investigation Of Cutting Forces, Temperature And Surface Roughness In End-Milling Of Hastelloy C-2000, Ryan Matthews

Masters Theses

"This thesis presents the results of experimental investigation of the effects of cutting parameters (spindle speed, feed per tooth, axial depth of cut and radial depth of cut) on the three components of cutting forces (F_x, F_y, F_z), workpiece temperature and surface roughness in end-milling of Hastelloy C-2000 alloy using design of experiments (DOE) and response surface methodology (RSM). End-milling experiments were conducted using 0.5 inch diameter end-mill on Cincinnati Milacron Sabre 750 vertical machining center using water based flood coolant. An inscribed central composite design of experiment was used to study the four …

Exploring Join Caching In Programming Codes To Reduce Runtime Execution, Swetha Surapaneni

Masters Theses

"This thesis describes an approach to reduce the runtime of a large program by exploring object querying and query caching in programming codes. Some object-oriented languages allow the programmers to express queries explicitly in the code, which are optimized using the query optimization techniques from the database domain. In this regard, Java Query Language (JQL) has been developed that allows object querying and performs the query optimization and query caching at runtime. The problem that has been addressed in this thesis is how to reduce the runtime of a large program during the single execution by employing an efficient cache …