Engineering Commons^™

Alloy Dissolution In Argon Stirred Steel, Darryl S. Webber

Doctoral Dissertations

"Alloying is required for the production of all steel products from small castings to large beams. Addition of large quantities of bulk alloys can result in alloy segregation and inconsistent alloy recovery. The objective of this research was to better understand alloy dissolution in liquid steel especially as it relates to Missouri S&Ts' patented continuous steelmaking process. A 45-kilogram capacity ladle with a single porous plug was used to evaluate the effect of four experimental factors on alloy dissolution: alloy species, alloy size or form, argon flow rate, and furnace tap temperature. Four alloys were tested experimentally including Class I …

Agent-Based Analysis And Mitigation Of Failure For Cyber-Physical Systems, Jing Lin

Doctoral Dissertations

"Techniques exist for assessment, modeling, and simulation of physical and cyber infrastructures, respectively; but such isolated analysis is incapable of fully capturing the interdependencies that occur when they intertwine to create a cyber-physical system (CPS). The first contribution of this doctoral research includes qualitative representation of the operation of a CPS in a single multi-agent model. Dependable operation of a CPS is contingent upon correct interpretation of data describing the state of the system. To this end, we propose agent-based semantic interpretation services that extract useful information from raw sensor data. We utilize the summary schemas model to reconcile differences …

Inherent And Model-Form Uncertainty Analysis For Cfd Simulation Of Synthetic Jet Actuators, Daoru Frank Han

Masters Theses

"A mixed aleatory (inherent) and epistemic (model-form) uncertainty quantification (UQ) analysis method was applied to a computational fluid dynamics (CFD) modeling problem of synthetic jet actuators. A test case, (Case 3, flow over a hump model with synthetic jet actuator control) from the CFDVAL2004 workshop was selected to apply the Second-Order Probability framework implemented with a stochastic response surface obtained from Quadrature-Based Non-Intrusive Polynomial Chaos (NIPC). Three uncertainty sources were considered: (1) epistemic uncertainty in turbulence model, (2) aleatory uncertainty in free stream velocity and (3) aleatory uncertainty in actuation frequency. Uncertainties in both long-time averaged and phase averaged quantities …

The Feasibility Of Using Bifidobacteria Bifidum (Atcc 700541) For The Production Of Prebiotic Oligosaccharides, Candice Marie Luehrs

Masters Theses

"Galactooligosaccharides (GOS) are prebiotics that are being used to influence intestinal microbiota towards health promoting, beneficial bacteria like bifidobacteria. Natural sources of GOS are not found in suitable levels to achieve the desired health effects so economically viable commercial production methods are important. Enzymatic conversion of lactose to GOS through transgalactosylation is a preferred method since the starting material is inexpensive and readily available. Enzymes used in batch production are purified from fungal or bacterial sources or remain in whole cells cultured for GOS production. Purified or unbound enzymes are single use whereas enzymes retained within whole cells can potentially …

Fabrication Of Sers Active Nanostructures By Femtosecond Laser Micromachining, Matthew Aaron Olson

Masters Theses

"This work investigated the surface-enhanced Raman scattering (SERS) enhancement of gold nanoparticles on femtosecond laser created nanostructures on a silicon wafer. The goal was to use the nanostructures to assemble the nanoparticles into three-dimensional aggregates and compare these enhancements to those of two dimensional aggregates. The SERS enhancement generated by the three-dimensional structures was on average 5 x 10⁴ with a high enhancement of 1.2 x 10⁵. The magnitude of this enhancement was on par with previous experiments that tested SERS enhancements on gold nanoparticles, but it did not show any significant enhancement caused by the three-dimensional nature of the …

Exploratory Study Of Barriers To Use Of Feigenbaum's Quality Cost Strategy Within Design Engineering Firms, David Patrick Loduca

Doctoral Dissertations

"It has been more than a half century since Armand Feigenbaum first conceived of the strategy for the manufacturing sector, yet quality costing strategies have not found a foothold among engineering firms. This study was aimed at constructing a set of theories that explains possible barriers to acceptance of the Feigenbaum strategy by analyzing attitudes and opinions of players in an actual engineering firm and the culture in which they work.

Modeled after the Feigenbaum approach and tailored to the business model of engineering and architectural firms, a system was developed to classify and record costs of quality. A local …

Advanced Composites Using Non-Autoclave Processes: Manufacturing And Characterization, V. G. K. Menta

Doctoral Dissertations

"The objective of the present study is to develop non-autoclave processes to manufacture high performance composites for aerospace applications. In Paper 1, vacuum assisted resin transfer molding (VARTM) process was developed for elevated temperature composites. Use of VARTM process for fabricating high temperature resins presents unique challenges such as high porosity and low fiber volume contents. Two different vacuum bagging methods: Seeman Composite Resin Infusion Molding Process (SCRIMP) and Double Vacuum Bagging Infusion (DVBI) process were evaluated. Flow simulation tool was used to predict key flow parameters needed for the successful infusion. In Paper 2, honeycomb sandwich panels were manufactured …

Sandwich Structures With Advanced Facings, Cody H. Nguyen

Doctoral Dissertations

"The purpose of this research is to investigate potential advantages of two innovative designs of sandwich panels. The first design involves sandwich panels with a piece-wise thickness of the facings aiming at two possible outcomes: (I) improved the structural response, i.e. strength and stiffness, without increasing the weight of the structure or (2) reduction in the weight of the structure without a detriment to its structural response. The analysis is conducted analytically using the first-order shear deformation theory and numerically by the finite element analysis of conventional and stepped-wise sandwich panels. The applicability of the first-order shear deformation theory to …

Electrodeposition Of Metallic Gas Diffusion Layers For Use In Pem Fuel Cells, Gargi Tandra

Masters Theses

"This work developed a novel method of using Electrodeposition techniques to fabricate metallic gas diffusion layers (GDLs) for application in proton exchange membrane fuel cells. These GDLs improve the electrical and thermal conductivity of the fuel cells, and their straight, noncircular pores remove water efficiently. The Electrodeposition technique used here relies on a sacrificial copper anode and an aluminum sheet 50 µm thick acts as a cathode. Unlike the other laboratory based methods available for the fabrication of metallic GDLs, this method is simple and cost effective. With controlled deposition parameters and a chemical lift-off process that corrodes the aluminum …

Optimized Testing And Logic Mapping Methodology For Caen-Based Nano-Circuits, Sambhav Kundaikar

Masters Theses

"Nanotechnology has been shown to have the potential to replace the existing CMOS technology in the race to maintain the Moore's Law increases in IC complexity. This work considers the Chemically Assembled Electronic Nanotechnology (CAEN), which fabricates nanofabric using a low cost self-assembly and self-alignment chemical process and provides very high density. However, the main disadvantage of this technology is the inherently high defect rate that hinders the efforts to commercialize such systems. Existing testing and design techniques, for example for FPGAs, are ill suited since they typically assume vary low defect rates.

This thesis is comprised of two papers. …

Workforce Planning Models For Semiconductor Manufacturing: Assembly-Test Operations, Shrikant Jarugumilli

Doctoral Dissertations

"We present a framework that integrates strategic and operational workforce planning models. Since these models provide decisions for planning horizons with different lengths, the formulation and solution strategy should ensure that the flow of information between these models is both appropriate and consistent.

The single-shift workforce planning problem is formulated as a two-phase goal program. In the first phase, the model allocates the workers to machine groups and identifies the shortage of workers (referred to as gap) followed by the second phase, in which certain constraints are relaxed and the workers are reallocated to the machine groups in order to …

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

Masters Theses

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

Creating A Sustainable Transportation Workforce: Identifying Skills, Abilities And Knowledge For Future Transportation Workforce, Sandhya Gopalakrishnan

Masters Theses

"The recruitment and retention of a transportation workforce capable of adapting to the requirements of emerging sustainable technologies is an important concern for engineering managers in transportation. Although there is an increasing demand for transportation professionals to fill positions stemming from retirement or created by innovations in sustainable transportation systems, the supply is decreasing. The objective of this research was to fill the gap between the supply and demand of skilled workforce by presenting a life-cycle framework for recruiting and retaining the transportation workforce as part of succession planning efforts funded by the U.S. Department of Transportation's Transportation Education Development …

Memristor Based Lookup Table - Novel Testing And Reconfiguration Techniques, Veeresh Anilkumar Hongal

Masters Theses

"Nanotechnology is soon predicted to replace the CMOS technology, as current CMOS lithographic techniques will become void for complex IC designs with smaller feature size, and are hence incapable of keeping up with Moore's law. The devices in nanotechnology are fabricated using bottom up self-assembly. Memristor is one promising nanotech device which can replace the transistor used as a switch or memory device as it is just half the size and uses only fraction of the energy. This work considers Memristor Look Up Table (MLUT) design, which is a building block for asynchronous FPGAs built with memristors. In spite of …

Mesh Optimization Of Finite Element Models Of Wellbore Stress Analysis, Ming-Yen Lee

Masters Theses

"Numerical modeling methods such as the widely used finite element method provide an excellent opportunity to analyze the wellbore state of stress for a variety of applications such as wellbore integrity, wellbore design or hydraulic fracturing. However, numerical modeling methods introduce errors by nature and may not precisely match the analytical solution if the meshing of the numerical model is not carefully taken care of. This study presents a parametric study of the meshing parameters mesh density, element type, and model size for 2-dimensional and 3-dimensional vertical wellbore models under three different types of boundary conditions, and a guideline for …

A Neural Network Based Approach For Path Planning On Costmap, Songjie Chen

Masters Theses

"In this thesis, a path planning method using a three-level hierarchical system model is proposed. In the top level of the hierarchy, the given location points to visit are taken as waypoints. The waypoint navigation process is formulated as a traveling salesman problem (TSP). The Lin-Kernighan algorithm is used to solve the TSP and transfer the solution to the lower level of the hierarchy. In the middle level, the path is represented by a grid-based costmap. A novel modified Grossberg neural network is designed to solve the point-to-point path planning. The bottom level of the hierarchy smoothens the path with …

Design, Analysis, And Optimization Of Composite Structures For Aerospace Applications, Tyler Jason Keil

Masters Theses

"This thesis contains three papers that focus on composites that pertain to a variety of structures commonly found in the aerospace industry. The first paper presents an investigation of the stowage and deployment strength of a thin carbon fiber-reinforced polymer shell capable of being rolled and stowed in a tight rolled configuration. The intent of this structure is for use as a segment of a larger deployable reflective aperture. This study involved finite element analysis of several laminates, coupon-level and full-scale prototype testing, which provided a much needed insight and benchmark of composite shells used in this manner.

The second …

Pressed Powdered Titanium And Aluminum Conical Shaped Charge Penetration Of Geological Targets, Dominique John Nolan

Masters Theses

"Conical Shaped Charge penetration into rock is dependent on the physical characteristics of the rock itself and the design and composition of the shaped charge conducting the work. This study looks at the effects of a non-typical conical shaped charge and its penetration into four different rock targets. The shaped charge is made of a liner, which is not a typical solid but instead is a pressed powdered metallic compound of Titanium (Ti) and Aluminum (AI).

The study presents the raw data from testing against rock targets that range in density, uniaxial compressive strength (UCS), tensile strength, hardness scales, and …

Design Of A Conditioner For Smoothing Wind Turbine Output Power, Murali Bottu

Masters Theses

"As a result of wind speed intermittency, wind turbine output power can be highly variable. The large variability in output power can adversely impact local loads that are sensitive to pulsating power. To mitigate large swings in power, the wind turbine output power can be smoothed by using a small energy buffer. A power conditioner is proposed to smooth the wind power output by utilizing the energy of an ultracapacitor. The conditioner is based on a single phase voltage source inverter (VSI) connected between the grid interconnection point and the ultracapacitor. The shunt VSI injects or absorbs active power from …

Installation And Performance Evaluation Of Coaxial Cable Sensors For Crack And Corrosion Detection, Iana Muchaidze

Masters Theses

"Even under service loads, reinforced concrete (RC) structures can develop cracks that result in excessive deflection of the structures and provide passages for moisture to corrode steel reinforcement. It is thus critical to develop a simple, cost-effective tool for real-time crack monitoring and associated corrosion detection that may affect the engineering maintenance of RC structures. The objectives of this study include: (1) to develop a die-cut manufacturing process of coaxial cables with spiral outer conductors, (2) to quantify the sensing properties of a miniaturized topology-based crack sensor, (3) to investigate the effectiveness of various sensor installation procedures in RC applications, …

Towards On-Line Voltage Stability Assessment Using Synchrophasors, Himanshu Subandhu Hirlekar

Masters Theses

"Voltage instability has become a growing concern in the operation of power systems in recent years. The reason is that power systems all over are being operated with reduced margins because of increased demand exacerbated by a general reluctance to invest in improvement of the electric grid infrastructure. Until recently it was difficult to predict voltage instability in the on-line environment. However, advances in technology has made possible the on-line monitoring and assessment of voltage stability. Synchrophasors is a relatively new technology in the field of power systems which allows system operators to monitor the system conditions at specific measurement …

Field Programmable Gate Array Based Multiple Input Multiple Output Transmitter, Richa Shekhar

Masters Theses

"MIMO is an advanced antenna technology compared to Single Input Single output (SISO), Multiple Input Single Output (MISO), and Single Input Multiple Output (SIMO) and is used to obtain high data rate in the system. Multiple-Input Multiple-Output (MIMO) systems have at least two transmitting antennas, each generating unique signals. However some applications may require three, four, or more transmitting devices to achieve the desired system performance. This thesis describes a comparison between different approaches like the microcontroller, ASICs and the FPGA available in the market for baseband signal generation. It also describes the design of a scalable MIMO transmitter, based …

Quantifying The Carbon Footprint Of Lean Waste, Kristen Donovan Balinski

Masters Theses

"The objective of this paper is to provide a method of quantifying lean wastes in terms of carbon dioxide emissions by using value stream mapping. Lean manufacturing, a process based on waste identification and reduction, is a growing trend in industry and a proven method of lowering costs. The environmental impact of these wastes can be quantified by identifying the metrics associated with them, and using existing reports to convert those metrics into measurements of carbon dioxide. Growing environmental concerns are prompting federal government regulation of greenhouse gas or carbon dioxide emissions, as seen in the American Clean Energy and …

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

Masters Theses

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

Thermomechanics Of Curves In Space, Pavan Krishna Kanchi

Masters Theses

"Several biological molecules are known to form helices and coiled structures, such as DNA, collagen, bacterial flagella, and proteins. The backbones of such molecules may be modeled as a curve in three dimensions. A variational problem for the functional of the total free energy required to perturb moving curves in space is considered. The total energy of a curve in three dimensions is minimized y with a general intensive energy, which is a function of position, and the invariants, curvature and torsion. Three types of moduli are identified: stretching, bending and torsional moduli. As a result, three independent force balances …

A Method For Calibration Of Speed-Flow Curves In Hcm 2010 And Determination Of Highway Capacity, Seyed Hadii Khazraee Khoshroozi

Masters Theses

"This study proposes a method for calibration of speed-flow curves in a format suggested by the Highway Capacity Manual (HCM) 2010 and applies it to two sites in Missouri: a work zone on I-44 around Pacific, and a basic freeway segment on I-270 in St. Louis. The three-regime model proposed is based on the two-regime (free-flow and transition) uncongested relationship suggested by the HCM 2010, complemented with a third regime representing congested conditions. Further, this study proposes a systematic approach based on regression analysis to determine capacity i.e., the break-point (intersection) between the transition and congested regimes. The proposed method …

Development Of Lower Cost Imaging Systems For Laser Metal Deposition Process, Shyam Barua

Masters Theses

"Laser Metal Deposition (LMD) has been used as an additive manufacturing process in industries such as aerospace and die castings. LMD is especially useful in repair applications involving die repair. However, it is still not used widely in industry due to variations in the quality of parts. There are multiple interactions between various factors which influence the quality of deposit.

There exists a need for defect detection systems to detect any changes in the deposition quality during deposition. On demand detection enables adjustment in process parameters and minimization of rework cost.

Vision systems have been used extensively in the industry …

Shale Gas Rock Characterization And 3d Submicron Pore Network Reconstruction, Malek Elgmati

Masters Theses

"Determining shale gas petrophysical properties is the cornerstone to any reservoir-management practice. Hitherto, conventional core analyses are inadequate to attain the petrophysical properties of shale gas at submicron-scale. This study combines interdisciplinary techniques from material science, petrophysics, and geochemistry to characterize different shale gas samples from North America including Utica, Haynesville and Fayetteville shale gas plays. Submicron pore structure, clay mineralogy, wettability and organic matter maturation were investigated to evaluate the petrophysical properties of shale gas rocks and to determine the impact of organic and inorganic matters on wettability alteration for different fracturing fluids on shale gas rocks.

High pressure …

Femtosecond Laser Micromachining Of Microstructures For Sensing And Detection, Yukun Han

Doctoral Dissertations

"This thesis focuses on the fabrication and analysis of miniature functional devices that can be used for different sensing and detection applications. As the first step, the surface characteristics and morphology of the micro/nano structures on substrates (fused silica and silicon) fabricated in water and in air by femtosecond laser were investigated. Based on this study, three micro devices have been designed and fabricated by femtosecond laser, and they were analyzed for optical and chemical sensing and detections. The three micro devices are: 1) an optical Fabry-Perot interferometer in optical fiber (made from fused silica) with smooth cavity surfaces. The …

Characterization Of Shielding Effectiveness For Metallic Enclosures, Nicholas Bennett Mentesana

Masters Theses

"This topic discusses and verifies an equation for estimating the shielding effectiveness of metallic enclosures through the use of numerical simulations. Using ideas from Bethe's "Theory of Diffraction by Small Holes", a previous student from the Missouri S&T Electromagnetic Compatibility Laboratory developed an equation that would yield an envelope prediction for the worst-case EMI from an aperture array backed by an over-moded cavity. Min Li (PhDEE '99) used results from measurements, simulations, and physics-based equations to formulate a simple equation that would predict these EMI levels. The main purpose of this thesis is to revisit this work and determine when …