Engineering Commons^™

Development Of The Academic Performance-Commitment Matrix (Apcm): Understanding The Effects Of Motivation And An Engineering Mathematics Curricular Intervention On Student Self-Efficacy And Success In Engineering, Anthony Bourne

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The latest push to encourage workforce growth in science, technology, engineering and math (STEM) disciplines has generated varying results. Overall, demand for STEM graduates is outpacing the numbers available. This has motivated a wide range of proposed solutions to increase the number of people trained to work in these fields. While a focus on college recruitment in these areas is a necessity for increasing numbers of STEM graduates, the expanding variety of students admitted to university programs in STEM disciplines creates a new series of issues in higher education. Most prominently, retention and graduation rates are low in STEM disciplines. …

Influence Of Curved Geometries On The Fatigue Life Of Laser Peened Components, Anoop Vasu

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Generating compressive residual stresses at the critical stress locations can prevent or delay structural component failure. Laser peening is a well-known method for inducing compressive residual stresses. The plastic deformation created by the planar shock waves near the surface regions is the major cause for the generation of compressive residual stresses. Apart from the planar waves, release waves at the border of impact are generated that act against the plastic deformation created by planar waves. This decrease of plastic deformation reduces the compressive residual stress generated near the surface regions of peened components. Laser peening of curved geometries creates compressive …

Computational Design And Characterization Of Silicene Nanostructures For Electrical And Thermal Transport Applications, Tim H. Osborn

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Novel silicene-based nanomaterials are designed and characterized by first principle computer simulations to assess the effects of adsorptions and defects on stability, electronic, and thermal properties. To explore quantum thermal transport in nanostructures a general purpose code based on Green's function formalism is developed.

Specifically, we explore the energetics, temperature dependent dynamics, phonon frequencies, and electronic structure associated with lithium chemisorption on silicene. Our results predict the stability of completely lithiated silicene sheets (silicel) in which lithium atoms adsorb on the atom-down sites on both sides of the silicene sheet. Upon complete lithiation, the band structure of silicene is transformed …

Full Wave Electromagnetic Simulations Of Terahertz Wire Grid Polarizers And Infrared Plasmonic Wire Gratings, John Cetnar

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This dissertation is a study of the interaction of terahertz (THz) and long-wave infrared (LWIR) radiation with various periodic sub-wavelength metallic structures in free-space and on dielectric substrates. There are many new and useful applications for both THz and LWIR radiation. Unfortunately, heavy attenuation by the Earth's atmosphere and low output power from THz sources combine to make THz radiation weak and difficult to detect. LWIR is not as prone to atmospheric attenuation as THz radiation. Nevertheless, the detection of LWIR can be improved upon by strengthening the coupling between incoming radiation and LWIR detector systems.

Light passing through periodic …

Design Of Thermal Structures Using Topology Optimization, Joshua D. Deaton

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The design of structures subjected to elevated temperature environments has long been an important area of study in the aerospace industry. This is especially true in the modern day, where new problems related to embedded engine aircraft and high temperature exhaust-washed structures present new structural design challenges not found in past applications. In this work, the response of a class of thermal structures whose responses are characterized by significant amounts of restrained expansion, to which exhaust-washed structures belong, are studied. To address the complex design challenges that become evident in these investigations, structural topology optimization is applied due to its …

Modern Statistical Methods And Uncertainty Quantification For Evaluating Reliability Of Nondestructive Evaluation Systems, Jeremy Scott Knopp

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The reliability of Nondestructive Evaluation (NDE) is an important input for risk analysis for sustainment of aging infrastructure. Reliability has typically been quantified via probability of detection (POD) studies. There are three problems with POD modeling methodologies provided in the most recent guidance on the subject:

1) Current models do not estimate the extremes of a POD curve very well because of the assumption that the POD curve approaches zero as flaw size goes to zero, and the POD curve approaches one as the flaw size goes to infinity.

2) The existing 2-parameter logit/probit models can be misused since there …

Novel Devices And Components For Thz Systems, John Raymond Middendorf

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Since the first demonstration of the generation of terahertz (THz) pulses from photoconductive (PC) antennas, research has pushed toward the development of smaller, cost efficient, and faster THz systems. This dissertation presents the work accomplished in order to realize these more practical terahertz (THz) photoconductive (PC) systems.

First, this work will present a novel ErAs:GaAs photoconductive switch used to make a THz source excited by 1550 nm laser pulses. It will be shown that the excitation process taking place in the material relies on extrinsic (rather than intrinsic) photoconductivity. Then, several experiments will be presented that aim to improve the …

Hierarchical Porous Structures Functionalized With Silver Nanoparticles: Adaptation For Antibacterial Applications, Anil Kumar Karumuri

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For a large number of applications involving surface interactions, there is an ever growing demand for materials with high specific surface area (surface area to volume ratio). Porous materials and nanomaterials offer higher specific surface area (SSA) each with their respective advantages and disadvantages. This research program is focused on bringing the two approaches together to create truly "hierarchical" materials that combine advantages of both while minimizing their disadvantages. In this study, various carbon based porous geometries were fabricated by grafting carbon nanotubes (CNT) onto highly porous reticulated carbon foams. These structures were further modified by functionalizing metal nanoparticles such …

Imperfect Situation Analysis: Representing The Role Of Error And Uncertainty In Modeling, Simulation And Analysis, Victor Eaton Middleton

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Much of traditional modeling, simulation and analysis (MS&A) is supported by engineering models - deterministic, Newtonian physics-based representations of closed systems. Such approaches are not well-suited to represent the intricacies of human behavior. This research advocates and seeks to articulate the concept of a more human- centric approach to MS& A, one that better represents decision-making and other cognitive aspects of human behavior as well as it does physical activity.

It starts with a view of individuals and groups as complex adaptive systems, which are best represented using agent-based modeling. Representation of human behavior through intelligent agents incorporates models of …

Non-Equilibrium Models For High Temperature Gas Flows, Daniil Andrienko

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A multi-physical approach is developed for non-equilibrium high enthalpy flows to cover a wide range of interdisciplinary studies. Compressible Navier-Stokes equations are coupled with the chemical model and equation of energy conservation for internal degrees of freedom. The model is capable of accounting for the non-equilibrium dissociation and thermal radiation heat transfer in gas flows. The methodology covers a range of problems from the combustion in subsonic counter-flowing jets to the hypersonic re-entry flows. The present approach attempts to validate the finite rate chemistry mechanisms by modeling the diffusive non-premixed flame of hydrogen at a very low Mach number. The …

Improving Learning Outcomes In Ee2010l Using Ni Mydaq In An Inverted Lab, Ryan F.A. Hamilton

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E 2010L Circuit Analysis Lab is an introductory course in analog circuits for students majoring in Electrical Engineering, Engineering Physics, Mechanical Engineering, Materials Science, and Computer Engineering at Wright State University. Prior to conversion to the semester calendar, from the quarter calendar, the course was known as EE 302 Circuit Analysis I Lab. In the terms since the semester conversion it has been noticed the percentage of students receiving grades of D (poor), F (failed), W (withdrawn), K (withdrawal in first two weeks), or X (unofficial withdrawal) has increased from the rate in the previous iteration of the course

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