Digital Commons Network^™

Friction Stir Processing Of Magnesium Alloys, Gaurav Bhargava

Masters Theses

"Magnesium alloys have been fast catching up their attention in applications where both lightweight and exceptional strength is desired. But magnesium alloys suffer formability issues which limit their use to cast applications when designing complicated shapes. Friction stir processing (FSP) is technique for, imparting a fine-grained, homogeneous microstructure by which both strength and ductility can be enhanced. The results from the first part of present work showed that AZ31 alloy when employed the use of FSP, yielded significant strength and ductility gains but on the cost of anisotropy. The cause of anisotropy was investigated to be correlated to texture evolution …

Emi Chip-To-Tem Cell Coupling For A Microcontroller And Emi Coupling Resulting From Via Transition And Reference Plane Change, Hemant Bishnoi

Masters Theses

"The work presented in this thesis can be broadly categorized under two main headings, estimation of electromagnetic interference (EMI) performance and characterization of EMI performance.

A numerical model of capacitive coupling between two orthogonally crossing double stripline was developed earlier by Kenji Araki and Yoshio Kami at the University of Electro-Communications, Japan. Their model was shown to be accurate up to 3GHz. A verification of their numerical model with full wave simulations is presented here.

In another work done by Shaohua Li, dynamic currents in the power pins of a microcontroller were predicted by using an IC model. The ultimate …

Public-Private Partnerships In High Risk Transportation Projects, Kiran Rangarajan

Masters Theses

"This research examines Public-Private Partnerships (PPPs) between private firms and City of Chamois, Missouri to establish a ferry boat service across the Missouri River. The study illustrates the role of PPPs in managing high risk transportation projects for rural economic development. The research study was designed to accomplish three objectives. First, understand and study the high risk transportation industry which included analyzing other ferry services in and around the region, and identifying potential risks involved in a ferry boat project. Second, study various models of PPPs, identify the attributes of each model and select appropriate models based on local and …

Modeling Of Wear And Oxidation Behavior Of A Carbon/Carbon Multidisk Clutch, Shankar Nagaraj

Masters Theses

"Carbon/carbon composites are a family of advanced composite materials. They are the most advanced form of carbon and consist of a fiber, based on carbon precursors, embedded in a carbon matrix. They are extensively used in design of sliding contact systems such as clutches and brakes because of their low weight, excellent thermal and mechanical properties, chemical inertness and self lubricating capability. They retain their mechanical strength in inert atmospheres up to 2000° C. However, in oxidizing environments, C/C composites rapidly react with oxygen forming gaseous carbon oxides around 450° C.

In the present study a C/C composite clutch assembly …

Inclusion Modification In Steel Castings Using Automated Inclusion Analysis, Vintee Singh

Masters Theses

"The objective of this research is to study the effects of changing the melt and ladle practices (deoxidation, slag, refractory types, etc.) in steel foundries on the cleanliness and toughness of steel castings. This study used an automated inclusion analyzer ASPEX PICA-1020, which provides a rapid and accurate method for determining the composition, size, number, and spacing of the inclusions present in steel samples. The first step in this research was to complete a series of industrial tests to benchmark the current foundry ladle practices with respect to cleanliness of the cast steel. Trials were conducted at steel foundries using …

Development Of Extrusion On Demand For Ceramic Freeze-Form Extrusion Fabrication Processes, Parimal Sanjay Kulkarni

Masters Theses

"Freeze-form Extrusion Fabrication (FEF) is a Solid Freeform Fabrication method. It involves the deposition of a ceramic paste in a layer by layer manner to construct a three dimensional structure. The ceramic paste used in this process consists of a high solids loading of ceramic powder mixed with water and a nominal amount of an aqueous organic binder. These characteristics make the process environmentally friendly. Also the absence of dies or molds in the process makes it suitable for fabrication of materials like ceramics. In the past, parts have been fabricated with continuous extrusion of a ceramic paste. In FEF, …

An Analysis Of Lessons Learned And Best Practices From Fuel Cell Applications With An Emphasis On Hydrogen Technology, Clint Alex Cottrell

Masters Theses

"In its review of the Department of Energy's Research Development and Demonstration (RD&D) plan for hydrogen, the National Academies recommended a study of lessons learned from technologies developed for stationary fuel cell power systems. Thus, the motivation for this thesis is to study and identify the lessons learned and best practices from prior stationary fuel cell power programs. To understand how to prepare for this technology, this study conducted a thorough investigation of past stationary alternative power projects to assess the opportunities for future stationary power efforts, and how this information can be used to meet objectives for future fuel …

Application Of Ground Penetrating Radar (Gpr) For Bridge Deck Condition Assessment: Using A 1.5 Ghz Ground-Coupled Antenna, Amos Wamweya

Masters Theses

"This study is a GPR-based assessment of three bridge decks, two with a hot bituminous wearing surface and one with a bare concrete slab. The primary objectives of this study were: 1) to assess the integrity of the three bridge decks using a 1.5 GHz ground-coupled GPR antenna, and 2) to evaluate the utility of the 1.5 GHz ground-coupled antenna for bridge deck investigations. Core control (chloride ion concentration data and core integrity data) and visual inspection were used as interpretive constraint. The acquired GPR data were interpreted, and two plan view maps were generated. One depicts the magnitude of …

Adapting Management Strategies To Enter New Global Markets, Karuna Vineetha Vemulapalli

Masters Theses

"With globalization spreading its roots into every country, people from various countries are working together, and will be trying to understand the cultural differences between the organizations in different nations. Effective management of the cultural differences will be an important and competitive advantage. Keeping in mind the different perceptions of the term “Management” by varying cultures, namely United States and India, this research will be focused on understanding and managing these differences.

The proposed research will deal with concepts of cultural diversity, economic differences, intercultural and organizational differences between the two countries. Understanding why some factors like motivation, responsibility, and …

Fatigue Of Friction Stir Welded Lap Joints With Sealants, Kenneth Doering

Masters Theses

"A lack of understanding of corrosion fatigue in friction stir welded aluminum joints prevents friction stir welding from being implemented in aerospace applications. Fatigue testing reveals a 60-75% reduction in the fatigue life of friction stir welded aluminum lap joints immersed in 3.5% NaCl solution (corrosion fatigue) compared with that of lap joints tested in ambient air. The loss in fatigue life is attributed to accelerated fatigue cracking due to hydrogen environment embrittlement. Two polymer sealant candidates are investigated: silicone rubber and nylon-11. Both sealant candidates can be applied prior to welding and seal the faying surface gaps in lap …

Design Hazard Analysis, And System Level Testing Of A University Propulsion System For Spacecraft Application, Joseph R. Siebert

Masters Theses

"The Missouri Science and Technology Satellite (M-SAT) design team on the campus of the Missouri University of Science and Technology has developed a pair of satellites to perform an autonomous formation flight mission. To enable the mission, a unique cold gas propulsion system was developed which utilizes the refrigerant R-134a as propellant. This thesis details the design process and considerations which led to the propulsion system as integrated into the satellite for the Flight Competition Review of the NS4 competition. The design process described flowed from the mission requirements and program restrictions down through component-level requirements and resulted in a …

Continuous Control Of Lunar Orbits Via Electric Propulsion, Sunil Aggarwal

Masters Theses

"To find definite answers for the presence of water on the poles of Moon, to facilitate selection of future lunar landing sites and aid in construction of architectural bases, to assist proper lunar resource utilization and to improve lunar gravity models there is a great interest and need for highly accurate, reliable and efficient lunar surface mapping and communication. This thesis is intended to aid in proper selection of orbits for future lunar missions by demonstrating the impact of using electric propulsion on the search space of feasible and useful lunar orbits. The requirements for future lunar mapping and communication …

Localization Of Nodes In Wired And Wireless Networks, Hindu Kothapalli

Masters Theses

"This thesis focuses on the implementation of algorithms for localization of nodes in wired and wireless networks. The thesis is organized into two papers. The first paper presents the localization algorithms based on time of arrival (TOA) and time difference of arrival (TDOA) techniques for computer networks such as the Internet by using round-trip-time (RTT) measurements obtained from known positions of the gateway nodes. The RTT values provide an approximate measure of distance between the gateway nodes and an unknown node. The least squares technique is then used to obtain an estimated position of the unknown node. The second paper …

Modeling And Simulation Of Electrochemical Magneto Hydro Dynamics, Debamoy Sen

Masters Theses

"This thesis focuses on how the electrochemical magneto hydro dynamic problem is solved through numerical simulation for a two dimensional millielectrode electrochemical cell and a three dimensional microelectrode array cell. Electrochemical processes are enhanced by magnetic fields through the introduction of body forces such as Lorentz force. Through modeling and numerical simulations, experimental results can be integrated with theory. Such simulations will aid in the prediction of mass transfer limited currents and visualization of flow profiles in an electrochemical cell. The numerical solution of the equation system is made possible by the finite volume method used in the FLUENT Computational …

Development Of A One Dimensional Subsurface Contaminant Transport Model With Stochastic Applications, Benjamin Waldon Johnson

Masters Theses

"Contaminant source release history is a necessary element of contaminant mass transport simulation in the saturated zone. The source release history is unknown at many sites, and many inverse models have been developed to define finite release histories. To define a likely domain of three source history parameters, a mass balancebased one dimensional approach is developed and tested by discretizing the spatial domain into bands. By incorporating the approach in a spreadsheet model, observed data is represented by both variable length and constant length bands of analysis. Each representation of observed data was tested to determine the most appropriate band …

On-Line Depth Measurement Of Micro-Scale Laser Drilled Holes, Rock Allen Powell

Masters Theses

"A micron-precision micro-hole depth detection scheme has been developed which utilizes a confocal structure and a photomultiplier tube as a photodetector. This scheme is experimentally confirmed to posses an accuracy of greater than 95% for micro-holes on the order of one-hundred microns in diameter and tens of microns in depth and could be easily be integrated for the control of industrial and research oriented laser micro-machining process"--Abstract, page iii.

Fault Detection And Prediction With Application To Rotating Machinery, Gary R. Halligan

Masters Theses

"In this thesis, the detection and prediction of faults in rotating machinery is undertaken and presented in two papers. In the first paper, Principal Component Analysis (PCA), a well known data-driven dimension reduction technique, is applied to data for normal operation and four fault conditions from a one-half horsepower centrifugal water pump. Fault isolation in this scheme is done by observing the location of the data points in the Principal Component domain, and the time to failure (TTF) is calculated by applying statistical regression on the resulting PC scores. The application of the proposed scheme demonstrated that PCA was able …

Feasibility Of A Human Performance Model In Consequence Management, Kashmeera Ghosh

Masters Theses

"Human civilization has always encountered unpredictable disasters as a result of natural events. Now it also faces the disasters caused by terrorist attacks. Governments must have consequence management plans in place to protect public health and safety, restore essential services, and provide emergency relief to affected businesses and individuals. Human performance models predict outcomes in complex dynamic situations. Such models can simulate disaster management procedures under varying circumstances. This work applies human performance modeling in a terrorist situation and evaluates possible uses of such models by first responders in practical consequence management applications. It includes a case study of an …

Development Of An Electronic Governor System For A Small Spark Ignition Engine, Donald Ray Hibler

Masters Theses

"The use of electronic controls on engines has been widespread and has now reached the small utility engine. The evolution from carburetion to electronic fuel injection has presented opportunity to implement additional controls with the intent to improve engine control and performance. In this study, an electronic governor system is developed for use on a small twin cylinder utility engine. This system is to replace an existing mechanical governor system, and it should have the potential as a production based solution that integrates with an existing fuel injection system. It must improve the speed droop characteristics over the current mechanical …

Communication Models For Monitoring And Mobility Verification In Mission Critical Wireless Networks, Maheswaran Thiagarajan

Masters Theses

"Recent technological advances have seen wireless sensor networks emerge as an interesting research topic because of its ability to realize mission critical applications like in military or wildfire detection. The first part of the thesis focuses on the development of a novel communication scheme referred here as a distributed wireless critical information-aware maintenance network (DWCIMN), which is presented for preventive maintenance of network-centric dynamic systems. The proposed communication scheme addresses quality of service (QoS) issues by using a combination of a head-of-the-line queuing scheme, efficient bandwidth allocation, weight-based backoff mechanism, and a distributed power control scheme. A thorough analysis of …

The Corrosion Of Ni₃Si Alloys In Sulfuric Acid, Christopher Marc Larson

Masters Theses

"Hydrogen production from water, the world's most renewable natural resource, can provide an economical and sustainable form of energy for the future. One means to achieve this is with a nuclear reactor-based sulfur-iodine (S-I) thermochemical cycle. Currently there are few materials available, other than precious metals like gold and platinum, that possess the corrosion resistance and mechanical properties required for the sulfuric acid decomposition loop of the S-I process. However, alloys based on Ni₃Si show promise to be a more affordable, corrosion resistant materials option for this technology. In this study, the corrosion behavior of NiSi₂₂ and NiSi₂₀(Nb,Ti)₃ alloys in …

Reliability-Based Design With System Reliability And Design Improvement, Gagandeep Singh Saini

Masters Theses

"This thesis focuses on developing a methodology for accurately estimating series system probability of failure. Existing methods for series system based design optimization are not that accurate because they assign reliability to each failure mode; as a result complete system reliability goes down. According to method proposed in this work, the user will assign required system reliability at the start and then optimizer will apportion reliability to every failure mode in order to meet required system reliability level. Detlevson second order upper bounds are used to estimate system probability of failure. Several examples have been shown to verify the results …

A Renewable Energy Feasibility Study To Power A Water Supply Pump In Sacala Las Lomas, Guatemala, William Anthony Granich

Masters Theses

"A clean and sufficient source of drinking water can be a challenge to develop in the rural highlands of Guatemala. Installing a submersible pump in a groundwater well can provide a source of water that is free of contamination and yields sufficient water throughout the year. Submersible pumps are typically powered from grid-power; however, an alternative energy source may be considered. An evaluation of the renewable energy resources has been conducted in Sacala las Lomas de San Martin Jilotepeque, Chimaltenango, Guatemala (Sacala). The drilling of a deep groundwater well has been proposed in Sacala to supply the community with sufficient, …

Development And Evaluation Of An Effective Process For The Recovery Of Oil And Detoxification Of Meal From Jatropha Curcas, Sarthak Gaur

Masters Theses

"There has been significant research on biofuels to ensure national security and economic stability of the US. Jatropha curcas, a hardy plant, holds tremendous potential as a biodiesel source and cattle feed-stock largely due to its high triglyceride and crude protein content. However, its viable economic utilization is limited due to the presence of important toxic compounds, phorbol esters. A novel and efficient process has been developed that obtains high yields of jatropha oil and detoxifies the defatted (oil free) jatropha meal. Principles of solid-liquid extraction were utilized to detoxify the meal and then liquid chromatography was employed to analyze …

Hydrogen Applications For Lambert - St. Louis International Airport, Mathew Thomas

Masters Theses

"Today, major airports are facing challenges related to pollution, energy efficiency, and safety and security. Hydrogen and fuel cell technologies, regarded as one of the key energy solutions of the 21st century are more energy efficient and reliable than conventional systems and have the potential to diminish these challenges. These technologies can also play a significant role in reducing the noise, air, and water pollution and enhancing energy security. This paper presents the design of a set of hydrogen technologies and systems that are commercially available and are ready for practical, real-world use. The hydrogen applications selected for Lambert-St. Louis …

Control Aspects Of A Double-Input Buckboost Power Electronic Converter, Deepak Somayajula

Masters Theses

"Systems in which two or more energy sources combine to supply power to a common load are called hybrid energy systems. Applications of these systems have grown due to their flexibility and reliability. Hybrid energy systems have been successfully implemented in hybrid electric vehicles and wind-solar systems where two or more energy sources share the same load. Double-input (DI) dc-dc power electronic converters (DIPECs) have been gaining popularity in hybrid energy systems due to their reduced component count and control simplicity. In addition, employing DIPECs increases the reliability, stability, and flexibility of the system. In this thesis, a small-signal model …

A Mobile Water Disinfection Unit Powered By Renewable Energy Systems, Matthew Vitello

Masters Theses

"The current method of disinfection of water used by the United States Army requires a significant amount of mobilization and demobilization time as well as being energy intensive. In an effort to improve small unit mobility a need for a light-weight, low maintenance, highly mobile disinfection system has arisen. In addition to the potential military use, a system of this type could provide a safe drinking water product during the aftermath of natural or man-made disasters, reducing the burden on emergency management services. A prototype system was developed that is self-powered, has low maintenance requirements, and can be stored for …

Automatic Detection Of White Areas In Dermoscopy Images, Ankur Dilip Dalal

Masters Theses

"This thesis presents an algorithm for automatically segmenting the white areas in dermoscopy images. The algorithm includes preprocessing of images, plotting the histogram (RGB) and calculating the average and standard deviation values (RGB) of the lesion. A threshold value for each color plane is determined using these parameters and white areas are automatically segmented. Various image features such as decile percentages and globule features are extracted and given to a neural network. The proposed algorithm has produced a maximum diagnostic accuracy of 94.67% and, when the lesions which touch the image border are removed from the set, the diagnostic accuracy …

Friction Stir Processing Of Laser Metal Deposited Ti-6al-4v, Romy Francis

Masters Theses

"Laser metal deposition (LMD) can form near net shaped components for aerospace applications. Ti-6Al-4V is a widely used aerospace alloy and fabrication of this alloy using LMD is gaining popularity. Improved mechanical properties are always a requirement in aerospace alloys and research is constantly being conducted to improve the properties of components formed from this alloy. Friction Stir Processing (FSP) in the past has been used as a method to change the surface properties of materials through microstructural modifications. The changes in properties can include hardness, corrosion resistance, fatigue strength, etc. The first section of this thesis is based on …

Zigbee-Enabled Structural Health Monitoring Using The Smartbrick System, Tyler Harms

Masters Theses

"This thesis describes the design, testing, and proposed extended field test of a wireless sensor network based on the SmartBrick, a structural health monitoring (SHM) device developed at Missouri S&T. The SmartBrick serves as the base station for the network, which utilizes additional sensor nodes to monitor the structure. Each node measures a range of environmental and structural phenomena, including vibration, tilt, humidity, and strain. The nodes use Zigbee short-range communication to transmit their data to the base station, which in turn uses the GSM cellular network to provide long-range communication capability and support for remote control.

Unlike many SHM …