Engineering Commons^™

A Study Of Wavelet-Based Noise Reduction Techniques In Mammograms, Varun Shah

Masters Theses

"Breast cancer is one of the most common cancers and claims over one thousand lives every day. Breast cancer turns fatal only when diagnosed in late stages, but can be cured when diagnosed in its early stages. Over the last two decades, Digital Mammography has served the diagnosis of breast cancer. It is a very powerful aid for early detection of breast cancer. However, the images produced by mammography typically contain a great amount noise from the inherent characteristics of the imaging system and the radiation involved. Shot noise or quantum noise is the most significant noise which emerges as …

Optimization Of Process Planning For Focused Ion Beam Machine In Nano-Manufacturing, Sushrut Shekhar Naik

Masters Theses

"The current revolution witnessed by nanotechnology is facing several challenges such as manufacturing of nano sized devices economically on a large scale. Focused ion beam (FIB) technology is one of the widely used approaches for nano-manufacturing due to its versatile nature. It provides accurate machining and process repeatability and has a range of applications. Major challenges for the current FIB process are the tradeoffs between quality, the processing time, and the long planning time. This research provides a pathway to eliminate the current problems facing nanotechnology. Using MATLAB and the Helios 600 FIB/SEM instrument available, modeling and analyses are carried …

Effects Of Coal Comminution In Relation To Waterjet And Selected Feed Properties, Yaqing Li

Masters Theses

"The necessity to develop a viable alternative to oil means that the development of coal-water fuels (CWF) has become increasingly important. However, the existing methods of comminution to prepare ultrafine particles for CWF are very inefficient. Consequently, a number of novel methods of comminution have been investigated in order to increase the efficiency of the process.

In this research, a new method of comminution using a high-pressure waterjet has been tested to produce ultrafine particle sizes necessary for efficient CWF process. To establish the fundamental performance of the waterjet mill, the influence of the operational pressure, standoff distance, feed size, …

Bond, Transfer Length, And Development Length Of Prestressing Strand In Self-Consolidating Concrete, Krista Beth Porterfield

Masters Theses

"Due to its economic advantages, the use of self-consolidating concrete (SCC) has increased rapidly in recent years. However, because SCC mixes typically have decreased amounts of coarse aggregate and high amounts of admixtures, industry members have expressed concerns that the bond of prestressing strand in SCC may be compromised. While the bond performance of prestressing strand in a new material such as SCC is an important topic requiring investigation, the results are only applicable if the research is completed on strands with similar bond quality as the strands used in the field. Therefore, the objectives of this research program were …

Laminate Dielectric And Foil Characterization For Signal Integrity On Printed Circuit Board, Aleksandr Yakubovich Gafarov

Masters Theses

"Accurate characterization of laminate dielectrics as substrates of printed circuit boards (PCB) over a wide frequency range (from tens megahertz to tens gigahertz) is important from a signal integrity (SI) point of view. Accurate knowledge of dielectric constants (DK) and dissipation factors (DF), or loss tangents, of laminate dielectrics, as well as loss in conductors, as functions of frequency over a wide frequency range, are needed to the designers of high-speed digital electronics.

An "in situ" wideband traveling-wave technique based on measuring S-parameters of the PCB test vehicles with auxiliary "through-reflect-line" (TRL) calibration patterns has been developed. This technique has …

Direct Shear Testing Of Fractured Rocks From Missouri Used To Evaluate Potential Fault Reactivation Induced By Carbon Dioxide Sequestration, Ishan Kumar

Masters Theses

"Geological storage projects of CO₂ are designed to maintain secure storage for thousands of years. Carbon Capture and Storage has been identified as one of the methods which is used to reduce global emission of CO₂ and achieve lower concentration of CO₂ in the atmosphere by capturing the CO₂ from the flue gases and storing it in underground formations. Potential leakage of injected CO₂ from the reservoir to the surface is caused by the reactivation of pre-existing faults and fractures which is caused by the change in the state of stresses and the pore pressure. To avoid damage to the …

Sputter Deposition Of Thin-Film Capacitors Onto Low Temperature Co-Fired Ceramic Substrates, Jack Murray

Masters Theses

"Single layer thin film capacitor structures were fabricated on the surface of low temperature co-fired ceramic (LTCC) substrates using sputter deposition. The capacitor structures had areas between ~10⁴ µm² to ~10⁶ µm² and featured ~200 nm Al or Pt electrodes with 150-1500 nm Al₂O₃ dielectric layers. Impedance analysis and current-voltage testing were carried out to determine the effect of electrode material and dielectric thickness upon capacitor performance. Capacitance values for devices with Al electrodes ranged from ~10 to ~700 pF, depending on capacitor area and dielectric thickness, and the fit to expected values was better than devices with Pt or …

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 …

Cooperative Power Control Approaches Towards Fair Radio Resource Allocation For Wireless Network, Liuju Wu

Masters Theses

"Performance optimization in wireless networks is a complex problem due to variability and dynamics in network topology and density, traffic patterns, mutual interference, channel uncertainties, etc. Opportunistic or selfish approaches may result in unbalanced allocation of channel capacity where particular links are overshadowed. This degrades overall network fairness and hinders a multi-hop communication by creating bottlenecks. A desired approach should allocate channel capacity proportionally to traffic priority in a cooperative manner. This work consists of two chapters that address the fairness share problem in wireless ad hoc, peer-to-peer networks and resource allocation within Cognitive Radio network. In the first paper, …

Fabrication Of Complex Ceramic Parts With Sacrificial Material Using Freeze-Form Extrusion Fabrication, Diego Armando Garcia MontañO

Masters Theses

"An additive manufacturing process called Freeze-form Extrusion Fabrication (FEF) was developed in this study to fabricate complex ceramic parts that require the use of sacrificial materials. The aqueous paste of alumina (Al₂O₃) was used as the main material, with solids loadings as high as 50 vol. % and water as the main liquid medium. Methyl cellulose, with a 10 vol. % solids loading and 90 vol. % water content, was used as the sacrificial material. The freeze-form extrusion machine has multiple extruders (extrusion devices) capable of fabricating parts from multiple materials without mixing them. The dynamic process of extruding alumina …

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 …

Generic Kinematic Simulation For Verification Of Laser Deposition Tool Paths, Sweta Dhaveji Chakravadhanula

Masters Theses

"The development of 3D visual simulation tool for machine simulation is a key approach in saving time and reducing cost. It is an important step before a manufacturing operation is performed on a part, as a tool to detect collision and validate the operation results. There are several kinds of manufacturing equipment being used and hence there is a need for the development of a generalized method to visually simulate a variety of machines. This paper presents the research conducted on describing machine configuration in a generic format which not only gives useful information, but can also be used as …

Computation Of Power Plane Pair Inductance, Measurement Of Multiple Switching Current Components And Switching Current Measurement For Multiple Ics With An Island Structure, Liang Li

Masters Theses

"The first part of the thesis presents the computation of power / ground plane pair inductance based on Partial Element Equivalent Circuit (PEEC) method in power distribution network (PDN) design. An efficient approach for the inductance computation is investigated. Speed-up techniques are employed include using the faster decay of mutual coupling due to the "differential" currents (same magnitude but opposite directions) in the two planes. Also, an approximate rectangular mesh reduction method is introduced which allows a local increase in mesh density.

The second part presents a measurement-based data-processing approach to obtain parameters of multiple current components through a bulk …

Effects Of High Volume Fly Ash And Powder Activators On Plastic And Hardened Concrete Properties, Drew Alexander Davis

Masters Theses

This study was performed to examine the effects of high volumes of Class C fly ash modified by powder activators upon the plastic and hardened properties of concrete. In a companion study, five Missouri area cements and five Class C fly ashes were examined for incompatibilities, with the most and least reactive combinations being scaled up to full scale concrete testing. Two baseline concrete mixtures were examined, the only difference in mixtures being the sources of portland cement and fly ash. Fly ash replacement was examined at 50% and 70% replacement (by total cementitious mass). Three powder activators were used …

A Feasibility Analysis Of Retrofitting Existing Roadway Lighting Infrastructure With Led Technology, Sean Michael Schmidt

Masters Theses

LED technology has advanced towards use in high intensity lighting purposes. LED luminaires have a significantly longer expected lifetime than traditional high-intensity discharge lighting systems. Due to these recent improvements in LED technology, there is a growing need for a comprehensive method to analyze the applicability of LED luminaires for use on major routes and roadways. This research investigates the acceptability of LED luminaires for use on major roadways through a feasibility analysis using data collected at various LED street light testing sites. Nine distinct LED luminaires were analyzed in field testing. The field data was then analyzed and compared …

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 …

Module-Level Power Converters For Parallel Connected Photovoltaic Arrays, Zachary Scott Johnson

Masters Theses

"A new solar technology with the capability to increase array-level power production is introduced by using simple integrated power converters that connect directly to photovoltaic (PV) panels is investigated. The power converters proposed here are full-bridge DC-DC converters with high voltage gain that operate with an open-loop control scheme. The outputs of these converters could then be directly connected to a grid-tie converter eliminating the need to connect panels in series to achieve the appropriate voltage. With a high-efficiency converter, the total system efficiency would increase even though one panel in the array may be compromised. The simulation results show …

Finite Element Analysis Of Blade-Formation Interactions In Excavation, Osei Brown

Masters Theses

"The efficiency and costs of mining operations greatly depend on the efficient design and use of excavators. The performance of these capital-intensive excavators requires thorough understanding of the physical and design factors that affect the formation-cutting tool interaction process. The current body of knowledge, based on experimental and analytical methods, provides limited understanding of these factors, which limits the accurate design and performance of excavators. The soil constitutive equations used in most of the available finite element (FE) models also fail to adequately capture the elastic and plastic behaviors of soil formations. This research initiative uses FE techniques to model …

5-Axis Tool Path Generation With Collision Detection For Finish Machining Of Freeform Surfaces, Jomy Francis

Masters Theses

"Research in the field of Tool path generation for freeform surfaces has been done intensively in the past. However, the main challenge that still exists is the computational efficiency related to the tool path generation. Tool path generation for freeform surface involves instantaneous calculation of new tool orientations which does not collide with the neighboring surfaces. Since the collision check of tool and neighboring surface is done repetitively at every instant of the tool, the calculations at every instant are to be computationally as easy as possible.

This thesis is composed of one paper. Paper I presents a novel extension …

Laboratory Implementations Of Pmsm Drive In Hybrid Electric Vehicles Applications, Amir E. Saad

Masters Theses

"Field Programmable Gate Arrays (FPGAs) are one of the today's most successful technologies for developing systems that require real time operation and providing additional flexibility to the designer. This research is focused on developing a control board for a permanent magnet synchronous machine (PMSM) using an FPGA module. The board is configured for individual use of an FPGA, digital signal processor (DSP) or in combination to control the PMSM by generating the required Pulse Width Modulator (PWM) to the inverter in order to drive and control the speed of the PMSM. Since, the exact rotor position and speed are required …

Formation Of Amyloid Fibrils By Diblock Peptides, Kunal Mukesh Naik

Masters Theses

"The objective of this study was to identify and then synthesize a series of peptides which were able to form fibrils rich in ß-sheet structure and to study the effect of the presence of surfaces on their formation. We decided to focus our experimental work on a family of peptides containing one "beta-sheet forming amino acid" and one 'alpha-helix forming amino acid'. This selection covers a wide range of hydrophillicites and charges and, by avoiding highly hydrophobic amino acids we can assure that the diblock peptides are soluble in a wide range of concentrations and solvent conditions. Three different diblocks …

Forward Converter For Solar Power Applications, Nickolas Arthur Mcfowland

Masters Theses

"Most solar arrays used today are connected in series and have tremendous power losses in partially shaded conditions. This document explores photovoltaic arrays in a parallel connection to reduce the power losses in other solar cell connected applications. The two main issues with any photovoltaic arrays are solar modules being shaded and the efficiency of the power converters used within the solar array. This thesis concentrates on alleviating these problems with the development of a two phase dc to dc forward converter with a snubber circuit as well as connecting a solar array in parallel to increase the performance in …

Behavior Of Staged Externally Bonded Carbon Fiber Reinforced Polymer Sheets For Improved Ductility, Laura Marie Rathe

Masters Theses

"Fiber reinforced polymers (FRP) has become increasingly used for the retrofit of aging structures for increased lifespans and for the rapid repair of damaged structures. It has many advantageous such as ease in rapid installation, high strength-to-weight ratio, and corrosion resistance. The main disadvantage of the material is brittle behavior with little warning of impending failures. The main objective of this study is to develop a new system of FRP that exhibits a more ductile behavior. To achieve this objective, separate sheets of FRP were applied at various staged levels and thus engaged at different loads. Ductile behavior was evaluated …

Field Coupled Electrostatic Discharge Sensitivity Database, Zhen Li

Masters Theses

"Electrostatic Discharge (ESD) can disrupt the performance of an electronic system, like an MP3 player either by injected currents or by transient fields. It is possible to predict at least the approximate transient field levels inside a system, but it is difficult to determine the response of ICs subjected to these fields, as no IC specific data is available, and as it is often too involved to measure the sensitivity of every IC possibly used in a product. As deterministic solutions are difficult to achieve, a statistical approach has been selected in this research. The goal of this database for …

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 …

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 …

Design And Development Of Ionic Liquid Dual-Mode Spacecraft Propellants, Steven P. Berg

Masters Theses

"Energetic ionic liquids capable of dual-mode chemical monopropellant or bipropellant and electric electrospray rocket propulsion are investigated. Following an extensive literature review, ionic liquids [Bmim][dca], [Bmim][NO₃], and [Emim][EtSO₄] are selected for study since their physical properties align well with the current state-of-the-art in chemical and electrospray propellants. Simulations show that these liquids will not be useful for monopropellant propulsion due to the prediction of solid carbon formation in the exhaust and performance 13-23% below that of hydrazine. Considering these ionic liquids as a fuel component in a binary monopropellant mixture with hydroxyl ammonium nitrate shows 1-4% improved specific impulse over …

Numerical Investigation Of Plasma Actuator Configurations For Flow Separation Control At Multiple Angles Of Attack, Thomas Kelsey West Iv

Masters Theses

"The primary objective of the study presented in this thesis was to analyze the effectiveness of aerodynamic plasma actuators as a means of active flow control over a low speed airfoil at multiple angles of attack each corresponding to two different flow separation mechanisms (i.e., laminar separation bubble and turbulent flow separation at stall conditions). Detailed parametric studies based on steady and unsteady Navier-Stokes simulations, modified to include the body force term created by the plasma actuator, were performed for a NACA 0012 airfoil at a chord Reynolds number of 10⁵. In particular, parametric studies were performed to investigate the …

Ultrasonic Communications System For Health Monitoring Of Hydrokinetic Turbine Blades, Andrew James Heckman

Masters Theses

"A health monitoring approach is investigated for hydrokinetic turbine blade applications. In-service monitoring is critical due to the difficult environment for blade inspection and the cost of inspection downtime. Composite blade designs provide a medium for embedding sensors into the blades for in-situ health monitoring. The major challenge with in-situ health monitoring is transmission of sensor signals from the remote rotating reference frame of the blade to the system monitoring station. In the presented work, a novel system for relaying in-situ blade health measurements in hydrokinetic systems is described and demonstrated. An ultrasonic communication system is used to transmit health …