Digital Commons Network^™

Fuzzy Adaptive Resonance Theory: Applications And Extensions, Clayton Parker Smith

Masters Theses

"Adaptive Resonance Theory, ART, is a powerful clustering tool for learning arbitrary patterns in a self-organizing manner. In this research, two papers are presented that examine the extensibility and applications of ART. The first paper examines a means to boost ART performance by assigning each cluster a vigilance value, instead of a single value for the whole ART module. A Particle Swarm Optimization technique is used to search for desirable vigilance values. In the second paper, it is shown how ART, and clustering in general, can be a useful tool in preprocessing time series data. Clustering quantization attempts to meaningfully …

Development Of A Stochastic Model For Performance Characterization Of A Pv/Vrb Microgrid, Kayla M. Speidel

Masters Theses

"Photovoltaic (PV) Microgrids have been proven to be a useful technology in providing an environmentally friendly source of energy when compared to the use of fossil fuels. Accurately characterizing the performance of a microgrid system would ensure that the system is appropriately sized to meet electrical loads without a heavy reliance on diesel generators. A microgrid that is sized properly will reduce the cost of diesel fuel, while also reducing the risk of wasting money on an oversized system. A deterministic model which was created to characterize the performance of PV microgrids based on percent of time generator running was …

Compressed Sensing Techniques For Radial Ultra-Short Echo Time (Ute) Magnetic Resonance Imaging, Xiahan Yang

Masters Theses

"This thesis proposes two techniques, namely Compressed Sensing (CS) and self-gating, for pre-clinical (CMRI) to reduce scan time and RF exposure to mouse heart, simply experimental procedures, and improve imaging quality. The proposed CS technique reduces the number of radial trajectories in Ultra-short Echo Time (UTE) CMRI scans on a 7 Tesla MRI machine to acquire 13% to 38% of the fully sampled k-space data. To reconstruct the image, the Non-Uniform Fast Fourier Transform (NUFFT) is utilized in each iteration of the l1-norm optimization algorithm of the CS to reduce error and aliasing. Experimental results with a phantom and a …

Co₂ Miscible Flooding Application And Screening Criteria, Mingfei Yin

Masters Theses

"Field experience has shown that CO₂ miscible flooding is an effective method to improve oil recovery, but only with proper reservoir candidate selection and optimal project design. This paper discusses both CO₂ miscible and immiscible flooding mechanisms and offers some guidelines for flooding operations. New developments in MMP determination are also introduced.

This research is based on a summary of field data from 134 CO₂ projects in the U.S. Several numerical methods have been applied for data cleaning. After cleaning, data from 128 projects have been analyzed and correlated. Carbonate reservoirs and sandstone reservoirs are the two …

Generation And Validation Of Optimal Topologies For Solid Freeform Fabrication, Purnajyoti Bhaumik

Masters Theses

"The study of fabricating topologically optimized parts is presented hereafter. The mapping of topology optimization results for Standard Tessellation Language (STL) writing would enable the solid freeform fabrication of lightweight mechanisms. Aerospace leaders such as NASA, Boeing, Airbus, European Aeronautic Defense And Space Company (EADS), and GE Aero invest in topology optimization research for the production of lightweight materials. Certain concepts such as microstructural homogenization, discretization, and mapping are reviewed and presented in the context of topology optimization. Future biomedical applications of solid freeform fabrication such as organ printing stand to save millions of lives through the robust development of …

A Novel Entropy Production Based Full-Chip Tsv Fatigue Analysis, Tianchen Wang

Masters Theses

"Through-silicon vias (TSVs) are subject to thermal fatigue due to stress over time, no matter how small the stress is. Existing works on TSV fatigue all rely on measurement-based parameters to estimate the lifetime, and cannot consider detailed thermal profiles. In this paper, we propose a new method for TSV fatigue prediction using entropy production during thermal cycles. By combining thermodynamics and mechanics laws, the fatigue process can be quantitatively evaluated with detailed thermal profiles. Experimental results show that interestingly, the landing pad possesses the most easy-to-fail region, which generates up to 50% more entropy compared with the TSV body. …

Optimal Techno-Economic Sizing Of Wind/Solar/Battery Hybrid Microgrid System Using The Forever Power Method, Sami Hamed Alalwani

Masters Theses

"Advancement in power electronics, energy storage, control, and renewable energy sources has led to the use of integrated renewable energy sources in islanded microgrids (MG). Also, the uses of integrated renewable energy sources have become more technically applicable, more economically feasible, and more environmentally friendly than conventional sources. As a result, electrification of rural villages using renewable energy technologies has started to become widely adopted around the world. Since generating power from renewable energy sources is highly intermittent and difficult to predict, the use of proper energy storage technology is important to eliminate mismatches between the load demand and generation. …

A Valuation Model For Two-Stage Contract Negotiations Over Multiple Interdependent Issues, Nnaemeka U. Amaeshi

Masters Theses

"Most real-world negotiation scenarios involve multiple interdependent issues over which the negotiating parties will seek an agreement. Simultaneous negotiation over multiple interdependent issues is an especially challenging problem because utility functions of negotiating agents are typically nonlinear and difficult to analyze. Also, negotiations often happen under circumstances of incomplete information, where either party has either little or inaccurate information about the preferences or utilities of the other party. Consequently, negotiations may go over multiple rounds until a mutually acceptable agreement is reached. The objective of this research is to create a quantitative model of decision-making that helps one negotiating party …

Evaluation Of Nickel-Titanium Oxide-Niobium Pentoxide Metal Ceramic Composite As Interconnect For Solid Oxide Fuel Cell, Abhijith Budur

Masters Theses

"With increasing importance for clean energy, fuel cells have gained great significance in recent decades. Solid oxide fuel cells are easy to transport due to presence of solid electrolyte and also have requisite electrical properties,but have been obstructed by their limitation to be used at only temperatures greater than 600⁰C and less than 800⁰C. To construct a stack of cells, materials that are good electrical conductors and having necessary mechanical strengths at that temperatures are being considered as interconnects between the cells. Evaluation of Nickel-Titanium dioxide-Niobium pentoxide (NTN) as interconnect and comparison to Stainless Steel 441 alloy has been made …

Cappack Devices For Enhanced Qnmr Measurements In 1H Nmr Spectroscopy, Lingyu Chi

Masters Theses

"Quantitative NMR analyses can be improved by adding well-defined external references for measuring sample properties on absolute scales. Special Capillary-tube Package (CapPack) devices were invented that provide in situ information (e.g., temperature, pH, pressure, integration, chemical shift, lock, etc.) about a sample with spectral imprimaturs. A new microscale glass-sealing technique produced CapPack devices that can survive high temperatures and pressures in harsh environments. Two CapPack devices are discussed: (1) Gradient CapPack-- a device for examining the irradiation bandwidth of solvent-suppression pulse sequences; (2) T₁ CapPack - a device for examining the T₁ robustness of solvent-suppression pulse sequences. A …

Thermodynamic And Chemical Kinetic Coupled Modeling For The Determination Of Cyclic Combustion Phasing In Hcci Engines, Krishawn Michele Goodwin

Masters Theses

"Homogeneous charge compression ignition (HCCI) is a low temperature combustion mode that contains great potential for decreasing emissions while increasing efficiency in internal combustion engines. The limitation is in that it is inherently difficult to control based on the lack of an external combustion trigger. This thesis outlines the potential of using the combustion residual species of carbon monoxide as a method of controlling the location of combustion by using data from a computer model. The model is a nonlinear five-state thermodynamic model that is coupled with a skeletal chemical kinetic model for PRF96. The model computes the amount of …

The Dynamic Behavior Of A Solid State Transformer (Sst) During Recloser Operation In Distribution Systems, Fahd Amin Hariri

Masters Theses

"Electrical power systems are continuously facing increasing electrical power demand in the last years to meet the requirements of modern life style. In order to satisfy such needs electricity authorities are taking appropriate measures to enhance the performance of power networks. One of the solutions to meet the customer's demands for energy was the trend to use the renewable energy. The increasing use of renewable energy and other distributed generation sources made the electrical grid more complex. Many researches have been carried out to find out solutions to overcome this complexity. One of these researches -- which was on a …

Day Of The Week Effect In Returns And Volatility Of The S&P 500 Sector Indices, Juan Liu

Masters Theses

"Previous studies have shown that returns associated with the stock market or foreign exchange's futures show variations across the day of the week. On such study, that employs a modified GARCH model for estimation, shows that returns associated with the S&P 500 stock index is highest on Wednesday and lowest returns on Monday. The same study shows that volatility is highest on Fridays and lowest on Wednesdays. In this study we investigate if this day-of-the-week effect on returns and volatility is present in the different sectors that constitute the S&P 500 index. The data set used provides daily returns from …

The Development Of Near Field Probing Systems For Emc Near Field Visualization And Emi Source Localization, Hui He

Masters Theses

"The objectives of this research are to visualize the frequency dependent electromagnetic field distribution for electromagnetic compatibility (EMC) applications and the radiating source reconstruction on complex shaped electronic systems. This is achieved by combining near field probing with a system for automatically recording the probe position and orientation. Due to the complexity of the shape of the electronic systems of interest, and for utilizing the expertise of the user, the probe will be moved manually not robotically. Concurrently, the local near field will be recorded, associated with the location and displayed at near real time on the captured 3D geometry …

Optimum Acquisition And Processing Parameters For Multichannel Analysis Of Surface Waves Using 3d Electrical Resistivity Tomography As Control, Uchenna Chibuzo Nwafor

Masters Theses

"Multichannel Analysis of Surface Waves (MASW) and Electrical Resistivity Tomography (ERT) data were acquired in the Newburg, Missouri with the goal of determining optimum MASW acquisition parameters. Users of the MASW tool generally state that greater geophone intervals and greater shot-to-receiver offsets provide for more accurate results. The objective was to determine if this "rule of thumb" applies in karst terrain.

ERT data were acquired along four traverses with eighty-four (84) electrodes at five feet spacing with SuperSting R8 Resistivity System using dipole- dipole array. The data were processed using Earth Imager to generate 2-D resistivity inversion and thereafter, Voxler …

Comparative Study Of Three Types Of Inverters Based On The Output Total Harmonic Distortion, Paterrson Thomas

Masters Theses

"In this thesis, three cases of power electronic inverters are taken into consideration to analyze their performance in terms of total harmonic distortion in their output voltage and output current. Firstly, a single H-bridge inverter is simulated. Staircase switching technique is used to generate the gating pulses for the switches. Only one switch is made to toggle for every half cycle. The fundamental harmonic component of the desired output voltage is considered to be 120 V. Secondly, the same topology is used with a Bipolar PWM gating technique. The switching frequency of the carrier wave is 33*60 Hz. Thirdly, a …

Freeze-Form Extrusion Fabrication Of Boron Carbide, Aaron Scott Thornton

Masters Theses

"Boron carbide is a safe, alternative to beryllium as a material for aerospace structures since it is also light-weight and exhibits high strength. This paper discusses a study of the Freeze-form Extrusion Fabrication (FEF) process to fabricate parts from boron carbide. Process parameters and hardware were modified to fabricate boron carbide specimens free of printed defects. Four-point bending tests were performed to measure the flexural strength of fabricated specimens. Observations of the presence of voids caused by ice crystals in fabricated parts led to further development and characterization of the boron carbide paste used with the FEF process. Additives were …

Common Path Pessimism Removal In Static Timing Analysis, Chunyu Wang

Masters Theses

"Static timing analysis is a key process to guarantee timing closure for modern IC designs. However, additional pessimism can significantly increase the difficulty to achieve timing closure. Common path pessimism removal (CPPR) is a prevalent step to achieve accurate timing signoff. To speed up the existing exhaustive exploration on all paths in a design, this thesis introduces a fast multi-threading timing analysis for removing common path pessimism based on block-based static timing analysis. Experimental results show that the proposed method has faster runtime in removing excess pessimism from clock paths."--Abstract, page iii.

Design And Implementation Of Low Complexity Wake-Up Receiver For Underwater Acoustic Sensor Networks, Ming Yue

Masters Theses

"This thesis designs a low-complexity dual Pseudorandom Noise (PN) scheme for identity (ID) detection and coarse frame synchronization. The two PN sequences for a node are identical and are separated by a specified length of gap which serves as the ID of different sensor nodes. The dual PN sequences are short in length but are capable of combating severe underwater acoustic (UWA) multipath fading channels that exhibit time varying impulse responses up to 100 taps. The receiver ID detection is implemented on a microcontroller MSP430F5529 by calculating the correlation between the two segments of the PN sequence with the specified …

Formation And Evolution Of Spinel In Aluminum Killed Calcium Treated Linepipe Steels, Obinna Adaba

Masters Theses

"Magnesium aluminate (Spinel) inclusions have been observed to cause hook crack in line pipe steels. These inclusions are typically formed during liquid steel processing at the ladle metallurgy furnace (LMF) and subsequently modified by calcium to form less harmful liquid inclusions. Unfortunately, spinel inclusions are still sometimes observed in samples taken from the tundish and coil after calcium treatment.

The formation and evolution of spinel inclusions during liquid steel processing at two industrial mini mills was investigated by analysis of lollipop samples taken at different stages of the steelmaking process. The effect of reoxidation on the formation of spinels after …

Analysis And Comparison Of Two High-Gain Interleaved Coupled-Inductor Boost Converters, Venkat Sai Prasad Gouribhatla

Masters Theses

"The main objective of this thesis is to compare and analyze two different high-gain dc-dc power electronic converters based on coupled inductors and capacitor-diode multiplier cells. The idea of these converters is to integrate the solar energy with a 400V DC microgrid. DC microgrids are more efficient, less expensive, and more reliable compared to AC microgrids. They also favor the integration of renewable energy sources. With the growing need for the utilization of more renewable sources of energy, photovoltaic panels have become one of the trending technologies which convert the energy from the sun to a useable electrical power. But …

Chemical Quantification With Ubiquitous Optoelectronic Devices, Altamash Mukhtar Fakki

Masters Theses

"Optical sensing in medical diagnosis and chemical analysis using optoelectronic devices is a growing technology since it offers many advantages including real time analysis, remote sensing capability and low cost approach. This thesis demonstrates that an optical sensing platform utilizing optical mouse, the ubiquitous optoelectronic computer peripheral, can be used in quantitative oxygen and pH analysis.

Work in the first paper includes the use of optical mice for fluorescence intensity imaging of commercial oxygen patch. This involves gray color intensity analysis of filtered images to determine the gaseous oxygen level.

In the second paper, the optical mice is used to …

A Gaussian Mixture Model For Automated Vesicle Fusion Detection And Classification, Haohan Li

Masters Theses

"Accurately detecting and classifying vesicle-plasma membrane fusion events in fluorescence microscopy, is of primary interest for studying biological activities in a close proximity to the plasma membrane. In this paper, we present a novel Gaussian mixture model for automated identification of vesicle-plasma membrane fusion and partial fusion events in total internal reflection fluorescence microscopy image sequences. Image patches of fusion event candidates are detected in individual images and linked over consecutive frames. A Gaussian mixture model is fit on each image patch of the patch sequence with outliers rejected for robust Gaussian fitting. The estimated parameters of Gaussian functions over …

Determination Of Setting Times By Shear Wave Velocity Evolution In Fresh Mortar Using Bender Element Method, Jianfeng Zhu

Masters Theses

This study aims at using modified bender element (BE) method to monitor the shear wave velocity (V_s) of mortar at early-age and determine initial and final setting times with the V_s method. Modifications of the traditional BE method have been made to overcome the aggressive cementitious environment and eliminate electromagnetic coupling. BE has been successfully employed in mortar samples with and without admixtures to evaluate the evolution of V_s during the early age (first 24 hrs) of hydration. An energy approach method of determining the first arrival time of S-wave has been proposed. Pulse wave velocity …

Developing A Novel Methodolgy And Testbed For Fatigue Analysis Of Metal Specimens, Sai Aravind Palepu

Masters Theses

"A prototype of fatigue testing machine was built to determine the fatigue strength of materials. Proposed testing prototype was displacement controlled magnetic type bend fatigue testing machine. Designed prototype was tuned to operate at or near resonance of the specimen in order to amplify excitation displacement. Low maintenance i.e. zero wear of the parts was achieved, there were no moving components in the prototype machine. Crucial components used to build were: DC power supply, solenoid, Arduino UNO, supports and laser displacement sensor. DC source used to pass current through solenoid producing magnetic field; mosfet and Arduino generated square waves of …

Development Of Two Color Imaging Pyrometer For Studying Thermal History Of Laser Metal Deposition, Niroop Matta

Masters Theses

"The laser aided manufacturing process is a process in which parts are built by adding material into the melt pool created by a laser. This process involves a complex thermal history which is important in determining the quality of the parts built. The objective of this study is to develop a high resolution two color imaging pyrometer which can measure the temperature of an object without the dependence of spectral emissivity of the material at an economical price. An 8.8 MP CMOS sensor is used as an imaging sensor. The visible spectrum of light is used for temperature measurement. The …

A Force Feedback Haptic Interface For Atomic Force Microscopy, Abdulmohsen Alabdulmuhsin

Masters Theses

"Integrating a force feedback haptic device with atomic force microscopy (AFM) improves the capability to investigate and manipulate the objects on a micro- and nanoscale surface. The haptic device provides the researcher with a sense of touch and movement by changing the position of the stylus or amount of force on it. The developed system's concept is to provide the user a sense and feel and control of the AFM probe at the nanoscale. By positing the haptic stylus, the user generates reference to commands to the AFM probe. In turn, forces experienced by the probe are communicated to the …

Active - Passive Spent Fuel Interrogation Using Neutrons And Photons, Tayfun Akyurek

Doctoral Dissertations

“This dissertation consists of three main parts. The first part is devoted to the comprehensive dead-time calculations with different detectors and conditions using different dead-time models as well as computer simulations. The minimum time that must separate two detectable events is called the counting system’s dead-time. If events take place during the system’s dead-time, they will not be recorded and will be lost. Such lost information is very important in many applications including high-intensity spectroscopy and nuclear spent fuel interrogations. The second part, a multitude of fission products identified as candidates have been scrutinized for their suitability of burnup analysis …

Cormem Digital Reasoning Architecture Using Cmos Technology, Indira Priyadarshini Dugganapally

Doctoral Dissertations

”This dissertation describes the application of a multi-level, memory-based approach for building digital circuits. To reflect the alternative approach, the basic science is termed digital reasoning and the specific CorMem technology is based on recent patents. CMOS transistors are used in a non-traditional way for multi-level operations and memory manipulation. The combination of multi-level architectures and matrix algebra principles can create flexible, modular systems using standard fabrication methods and can avoid many of the limitations of other multi-valued logic approaches.

Quaternary, memory-based systems are developed to implement logic-gate-type functions, digital adder circuits, a complete arithmetic and logic unit (ALU), quaternary-to-binary …

The Bitcoin Blockchain As Financial Market Infrastructure: A Consideration Of Operational Risk, Angela Walch

Faculty Articles

“Blockchain” is the word on the street these days, with every significant financial institution experimenting with this new technology. Many say that this remarkable innovation could radically transform our financial system, eliminating the costs and inefficiencies that plague our existing financial infrastructures. Venture capital investments are pouring into blockchain startups, which are scrambling to disrupt the “quadrillion” dollar markets represented by existing financial market infrastructures. A debate rages over whether public, “permissionless” blockchains (like Bitcoin’s) or private, “permissioned” blockchains are more desirable.

Amidst this flurry of innovation and investment, this paper inquires into the suitability of the Bitcoin blockchain to …