Engineering Commons^™

Quantifying The Desired Degree Of Supply Chain Flexibility, Poorna Marappa

Masters Theses

"The dynamic nature of today's market drives the need for flexibility in supply chains. The ever-growing need for and importance of flexibility in supply chains has motivated researchers to develop frameworks to achieve supply chain flexibility. Much of the research on supply chain flexibility focuses on drivers of the need for flexibility and classification of supply chain flexibility. Existing frameworks for determining the desired degree of flexibility in supply chains give an overview methodology; however, a comprehensive framework is absent. This research proposes a comprehensive framework to quantify the desired degree of flexibility in supply chains and accordingly determine its …

Application Of Multi-Modal Fusion Techniques For Corrosion Detection And Characterization In Aging Aircraft Components, Soumya De

Masters Theses

"The United States Air Force (USAF) recently estimated that corrosion maintenance costs exceed $800M per year. Given this, it is desirable to reduce the amount of "find it-fix it" corrosion maintenance activities. One method is to introduce a damage tolerance approach for corrosion detection. In order for this to become a reality, a comprehensive snapshot of corrosion present must be generated.

This thesis presents a data fusion process to perform uni- and multi-modal nondestructive testing and evaluation of corrosion under paint and in lap joints for volumetric characterization. The process for analyzing a given structure includes: 1) the acquisition of …

Formation Control Of Car-Like Mobile Robots, Shweta Annapurani Panimadai Ramaswamy

Masters Theses

"A traditional tracking and control design approach already available in literature is derived and discussed for a car-like mobile robot. It involves a decoupled design involving two separate algorithms, one for velocity control design and another for torque control design. Weak interactions among the algorithms and separate designs make the robot performance optimization and the formation stability difficult to achieve. So, a new tracking and control architecture wherein the conventional elements are replaced by a single component that performs all the functions and hence called the integrated tracking and control scheme is used"--Abstract, page iii.

Recovery Of Materials From Recycling Of Spent Furnace Linings, Phani Krishna Angara Raghavendra

Masters Theses

"The objective of this research study is to evaluate the technical feasibility of liberating metal entrapped in the spent melting furnace linings obtained from a non-ferrous metal producer and develop an economic technique to recycle all of the materials presently landfilled. Five to six million pounds of spent melting furnace linings are landfilled annually from this non-ferrous producer"--Abstract, page iii.

Densification, Microstructure, And Mechanical Properties Of Zirconium Diboride Based Ultra-High Temperature Ceramics, Sumin Zhu

Doctoral Dissertations

"The first part of this dissertation was aimed at studying the densification of ZrB₂ ceramics by pressureless sintering techniques. Various processes have been applied to coat ZrB₂ powders with polymer precursors, which were used to produce C after charring. After sintering at 1900⁰C, relative density increased of ~70% for uncoated ZrB₂ to >99% for ZrB₂ coated with at least 1.0 wt% C. Thermodynamic analysis suggested that C reacted with and removed oxide impurities (ZrO₂ and B₂O₃) that were present on the ZrB₂ particle surfaces, which promoted densification by minimizing grain coarsening"--Abstract, page iv.

Electromagnetic Modeling Of Distributed Coaxial Cable Crack Sensors In Reinforced Concrete Members, Mei Wang

Masters Theses

"Distributed crack sensors were recently developed with coaxial cables that are composed of inner and outer conductors as well as dielectric layer in between. These sensors were designed based on the change in topology of the cable outer conductor structure under strain effects. Various tests of reinforced concrete (RC) beams and columns indicated that the newly designed sensors are 10~50 times more sensitive than commercial cables to the longitudinal elongation applied on their cable structures. The spatial resolution of the sensors is approximately 50 mm. Limited numerical simulations with the transmission line theory and the finite difference time domain model …

A Systematic Approach To Project Portfolio Selection For Economic Development In Municipalities: A Case Study In Vienna, Missouri, Amanda Danielle Alpaugh

Masters Theses

"Economic development is essential for the survival of all municipalities in the United States. Economic growth, created through project implementation, brings new capital into municipalities by increasing the tax base. Smaller municipalities often struggle to implement projects that promote economic growth. These municipalities run into problems because they lack resources to hire an economic consultant and capabilities to independently complete the strategic planning process. This thesis describes an easy-to-use and easy-to-implement systematic ten-step approach to project portfolio selection for economic growth within smaller municipalities...The ten-step approach was employed in a case study performed in Vienna, Missouri. The case study involved …

Carbon Credits And Energy Subsidies In Economic Decision Making For Confined Animal Feedlot Operation Waste Treatment, Taresh Grover

Masters Theses

"Released waste into the environment has always had a societal cost. Current issues with swine waste suggest that improved treatment is needed as agricultural production has become more industry-like and also as we now globally value the mitigation of global warming. The current need for and the economic support of advanced waste treatment has converged for animal agriculture, and now improved waste treatment is possible with concurrent economic benefit through alternative energy and carbon emissions. Recent changes have resulted in renewal of interest in anaerobic digestion (AD) technology with methane capture and energy production. An economic model was constructed to …

A Coarse-Grain Molecular Dynamics Study Of The Nanotribological Properties Of Nanoparticle Solutions, Ramesh Chembeti

Masters Theses

"In this study, solutions of alkanethiol-capped nanoparticles in alkane are examined using molecular dynamics simulations for their nanotribological potential based on the hypothesis that fluid molecules of very different sizes may interrupt each other's layering tendency to result in less layered or non-layered configurations and provide better lubrication for nanodevices. An effective nanoparticle-nanoparticle pair potential based on previous atomistic approach is used and the temperature and parallel pressure are controlled in place of chemical potential for defining thermodynamic state. When compressed, the confined nanoparticle-containing alkane films generate reduced oscillations in perpendicular forces and smoother expansion in lateral dimensions, indicating lesser …

Application Of Statcom For Improved Dynamic Performance Of Wind Farms In A Power Grid, Aditya P. Jayam

Masters Theses

"This thesis investigates the use of a Static Synchronous Compensator (STATCOM) along with wind farms for the purpose of stabilizing the grid voltage after grid-side disturbances such as a three phase short circuit fault, temporary trip of a wind turbine and sudden load changes. The strategy focuses on a fundamental grid operational requirement to maintain proper voltages at the point of common coupling by regulating voltage. The DC voltage at individual wind turbine (WT) inverters is also stabilized to facilitate continuous operation of wind turbines during disturbances"--Abstract, page iii.

Sorting Automated Concept Generator Results Based On Manufacture And Assembly Concerns, Kerry Ryan Poppa

Masters Theses

"Early in the design process, it is desirable to produce a large number of potential solutions. Completely exploring a problem's solution space is an unreasonable expectation for an unaided designer or design team. Computational tools have emerged to help designers more fully explore possible solutions. These automated concept generators use knowledge from existing designs and the desired functionality of the new product to suggest solutions. Existing automated concept generation methods produce many candidate solutions, but produce unmanageably large sets of solutions. Techniques are needed to organize the set of concepts into smaller groups, more easily parsed by the human designer. …

Synthesis Of Iron Oxide Nanoparticles In A Counterflow Diffusion Flame Reactor, Hector Enrique Ruiz

Masters Theses

"A Counterflow Diffusion Flame (CDF) reactor was used to produce iron oxide nanoparticles. The experimental work was performed to study synthesis conditions and characterize the iron oxide nanoparticles. The parameters studied are those that control the flame structure, namely, gas flow rates and vacuum; other parameters include the precursor volume flow rate, and the relative location and temperature of the collecting probe inside the flame. Hexagonal nanoparticles were the most commonly observed shape. Hexagonal-shaped nanoparticles are mainly formed under stoichiometric conditions and with a high temperature profile in the flame. Cubic nanoparticles were also observed. The main parameter for the …

Application Of Product Family Design For Engineered Systems In Changing Market Space, Mohit Goswami

Masters Theses

"The focus of this paper is on the design of an engineered system for a changing market space. Due to the dynamic nature of the customer requirements, the specification of product offerings in a particular market may change. Manufacturers need to strategically design their product portfolio in such a way that their profitability is maximized, while deploying the right number of platforms necessary for deriving product variants. Depending on the system architecture, subsystems can be classified into one of the two types: scalar subsystems and modular subsystems. Each subsystem is defined by various parameters, performance criteria, and physical compatibility constraints. …

Performance Of Fire-Damaged Prestressed Concrete Bridges, Wendy Leann Moore

Masters Theses

"The purpose of this experimental program was to develop and analyze the effects of fire damage on prestressed concrete bridges. Flexural strength and serviceability of the bridge were measured by inputting fire damaged data into a parametric study spreadsheet consisting of a typical 3-span continuous prestressed concrete bridge. Data was obtained by exposing two types of specimens to different levels of elevated temperatures and then cooling them at room temperature to simulate fire damage. The two specimen types were prestressing strands which were tested in tension and concrete blocks with a single prestressing strand embedded in the center, which were …

Enabling Wind Turbine Generators To Participate In Power Grid Frequency Regulation For Enhanced Stability, Hongtao Ma

Doctoral Dissertations

"This dissertation focuses on wind farm frequency regulation capability to maintain the grid frequency stability. Wind plant power controllers are designed and tested for participation in grid frequency restoration. The small signal stability on sub-optimal operating points is analyzed and a de-loaded operating point is proposed.

In the first paper, a new frequency regulation scheme is developed for the wind turbine/generator/converter trio that will provide the capability to participate in restoring frequency in a way similar to the droop response of conventional generators. Output active power adjustment can be realized by both converter and pitch angle control in addition to …

Geological Sequestration Of Carbon Dioxide By Hydrous Carbonate Formation In Steelmaking Slag, C. Hank Rawlins

Doctoral Dissertations

"The formation of carbonate solids from the alkaline earth oxide phases in steelmaking slag was investigated in dry and aqueous conditions as a vehicle for carbon dioxide sequestration. The goal of this research was to determine the process conditions that would increase the kinetics of the carbonate formation process under hydrous conditions, enabling direct removal of carbon dioxide from steelmaking offgas"--Abstract, page iv.

Methodology And Process To Accompany A Virtual Geotechnical Database For The St. Louis Metropolitan Area, Katherine Leigh Onstad

Masters Theses

"The St. Louis metropolitan (STL) area, which spans Missouri and Illinois, currently has no overarching organization of geospatial data (geodata). The two states have their own geodata, using their own individual standards. The development of a virtual geotechnical database (VGDB) encompassing the entire STL area on both sides of the Mississippi River is a solution to the data sharing and standardization problem of this area. The VGDB integrates geodata from disparate sources into a geographic information systems (GIS) database accessible via the internet. The creation of the STL area VGDB consisted of three parts: 1) compiling the geodata; 2) formatting …

Design And Optimization Of Abrasive Slurry Feed System, Control Circuit And Jet Drilling Tool For Mining Applications,, Pradeep Nambiath

Doctoral Dissertations

"This dissertation focused on an investigation of small diameter hole drilling using abrasive slurry jet (ASJ) technology. The existing ASJ feed systems were reviewed and found inadequate to satisfy the requirements of an ASJ drill. A novel feed system was designed which improved on existing systems by resolving problems with the inability to perform stop/start operations and ensure precise metering of abrasive feed. This system met standards of consistency and evenness of feed required for machining aircraft component parts for Air Force Research Laboratory (AFRL). Theoretical and experimental analysis of the power of an ASJ stream yielded valuable design information …

Imaging In Karst Terrain Using Electrical Resistivity Tomography, Iana Muchaidze

Masters Theses

"The Missouri Department of Transportation (MoDOT) plans to construct a new intersection between highway 60 and highway 65 to alleviate traffic congestion during peak flow periods. This construction site, which is referred to as the Route 60/65 study site in this thesis, is located on the southeastern side of Springfield, Greene County, Missouri. Bedrock in the study area (Burlington-Keokuk Limestone) is characterized by karstic features such as loosing streams, underground caves, and sinkholes. Prior to the commencement of construction, MoDOT conducted a study of the subsurface conditions in the Route 60/65 study site. The main objective was to identify features, …

Sensitivity Analysis Of Relative Worth In Empirical And Simulation-Based Qfd Matrices, Robins Mathai Kalapurackal

Masters Theses

"Quality Function Deployment (QFD) is one of the most popular design tools used in product development. One of the objectives of QFD is to map customer requirements to product requirements and calculate their relative worth. A product requirement with a large relative worth indicates that it is an important product requirement in satisfying customer requirements. QFD applications use various rating scales in quantifying the degree of mapping from customer requirements to product requirements and various worth calculation methods to calculate the relative worth. The purpose of this paper is to study the sensitivity of relative worth when different rating scales …

Friction Stir Form Welding Of Aluminum Structures, Kamini Ashokkumar Gupta

Masters Theses

"The objective of this work was to demonstrate the applicability of friction stir welding (FSW) technology in the automotive industry. Increasing fuel prices, stringent safety and emission norms are continuously striving automakers to make lightweight, fuel efficient vehicles. Automotive engineers are researching for alternate materials in order to meet weight savings targets. Use of aluminum in place of steel in a car has been increasing for making lightweight vehicles. Conventional welding and spot welding are used as preferred joining methods by the automotive industry. However, if aluminum is used in place of steel alternate joining methods are to be researched. …

Laboratory Analysis Of Small Strain Moduli In Compacted Silts, David M. Weidinger

Masters Theses

"Soil compaction quality control accounts for a significant portion of geotechnical practice. Often the performance of a roadway can be directly linked to the quality of the compacted subgrade. A poor subgrade can result in weak areas in the road causing excessive deflections at the surface, ultimately leading to a pot hole or uneven surface and an unpleasant ride for the travelers. Vehicles passing over a section of highway causes small strains in the founding soil. These strains accumulate over time. A better understanding of how the compacted soil responds at small strains could shed light on improving the quality …

A Separation Criterion And Non-Intrusive Thickness Measurement Technique For Shear-Driven Films, Mark A. Friedrich

Masters Theses

"The behavior of a shear-driven thin liquid film at a sharp expanding corner is of interest in many engineering applications. However, details of the interaction between inertial, surface tension, and gravitational forces at the corner that result in partial or complete separation of the film from the surface are not clear. The focus of this study was to develop a criterion to predict the onset of shear-driven film separation from the surface at an expanding corner as well as to develop a film thickness measurement technique that could be used to obtain an average film thickness for input into the …

Asynchronous Nanowire Crossbar Architecture For Manufacturability, Modularity And Robustness, Ravi Bonam

Masters Theses

"This thesis spotlights the dawn of a promising new nanowire crossbar architecture, the Asynchronous crossbar architecture, in the form of three different articles. It combines the reduced size of the nanowire crossbar architecture with the clock-free nature of Null Conventional Logic, which are the primary advantages. The first paper explains the proposed architecture with illustrations, including the design of an optimized full adder. This architecture has an elementary structure termed as a Programmable Gate Macro Block (PGMB) which is analogous to a threshold gate in NCL. The other two papers concentrate on mapping and placement techniques which are important due …

Development And Validation Of A Microcontroller Emissions Model, Shaohua Li

Masters Theses

"A model of the power delivery network of a microcontroller was developed to predict the radiated and conducted emissions from the integrated circuit (IC). A SPICE model of the power delivery network, similar to the ICEM model, was developed for a microcontroller running a typical program and used to predict the noise voltage between the power and return planes of a printed circuit board (PCB).

Fault Propagation Timing Analysis To Aid In The Selection Of Sensors Fro Health Management Systems, Jeremy Johnson

Masters Theses

"Sensor data is processed to assess performance and health of complex systems. Proper sensor selection, placement, and implementation are critical to build an effective health management system. For complex systems in which the timely assessment of the health is desired to avoid expensive consequences of failure, sensor placement is vital. The ability to identify a critical failure early is completely dependent on sensor location within the fault propagation path. A strategy for assessing a sensor suite with respect to timely critical failure detection is presented in this thesis. To illustrate the strategy, Fault Propagation Timing Analysis (FPTA) will be performed …

Human Systems Integration: Training And Education Needs Analysis, Hao Zhang

Masters Theses

"Over the past decade, the military (both US and foreign) has developed a wide range of tools, techniques, and technologies for integrating human factors into systems engineering. Human Systems Integration (HSI) came forth as a new multidisciplinary field of study composed of several basic areas including Human Factors Engineering, System Safety, Health Hazards, Personnel Survivability, Manpower, Personnel, Training, and Habitability. An online survey was designed to examine education and training in HSI. 19 HSI experts responded to the survey. The feedback showed that there is a lack of high qualified practitioners in HSI. Many HSI practitioners are lacking of required …

Autothermal Non-Catalytic Reformation Of Jet Fuel In A Supercritical Water Medium, Jason W. Picou

Masters Theses

"The non-catalytic reformation of jet fuel using supercritical water was studied in a specially designed 0.4-L Haynes Alloy 230 tubular reactor. Experiments were performed at a constant pressure of 24.1 MPa, a temperature of 770°C, and at a constant water-to fuel ratio of fifteen-to-one by mass with various space times and oxygen flow rates. The experiments were conducted with and without air flow so as to examine the effects of the concurrent partial oxidation on the overall reformation process. The reactor effluent gas consisted of hydrogen, nitrogen, carbon dioxide, carbon monoxide, methane and ethane. Increasing space time increases the extent …

Evaluation Of Su8 And Ruthenium Oxide Materials For Microfluidic Devices, Margaret Theresa Audrain

Masters Theses

"This thesis investigates two materials, SU8 photoresist and RuO₂, for possible incorporation into a self-calibrating microfluidic biosensor. The negative, epoxy based photoresist SU8 has been widely used in the fabrication of micro-electro-mechanical systems (MEMS) devices. This is due to its many desirable features that make it a suitable material for a wide variety of MEMS applications. The effects cross-linking (exposure dose) and bonding time have on bond strength and plasma modification of the SU8 surface were investigated as well as the bond strength of etched SU8. It was shown that adhesive bonding was an effective method of bonding, with bond …

Femtosecond Laser Micro-Structuring Of Silicon Wafer In Water Confinement, Songping Wu

Masters Theses

"This thesis investigates the use of femtosecond laser induced surface morphology on silicon wafer surface in water confinement. Unlike irradiation of silicon surfaces in the air, there are no laser induced periodic structures, but irregular roughness is formed when the silicon wafer is ablated under water. Interestingly, a particular parameter combination enables a smooth surface, which can improve the surface quality of micro-machining products. This thesis first investigates the single ablation and multi-pulse ablation processes in order to study the effects of laser parameters on ablation morphology, as well as the basic physics and mechanism of the laser-material interaction process …