Open Access. Powered by Scholars. Published by Universities.®

Engineering Science and Materials Commons

Open Access. Powered by Scholars. Published by Universities.®

University of Kentucky

Discipline
Keyword
Publication Year
Publication
Publication Type

Articles 1 - 14 of 14

Full-Text Articles in Engineering Science and Materials

Photocatalytic Activity: Experimental Features To Report In Heterogeneous Photocatalysis, Md. Ariful Hoque, Marcelo I. Guzman Oct 2018

Photocatalytic Activity: Experimental Features To Report In Heterogeneous Photocatalysis, Md. Ariful Hoque, Marcelo I. Guzman

Chemistry Faculty Publications

Heterogeneous photocatalysis is a prominent area of research with major applications in solar energy conversion, air pollution mitigation, and removal of contaminants from water. A large number of scientific papers related to the photocatalysis field and its environmental applications are published in different journals specializing in materials and nanomaterials. However, many problems exist in the conception of papers by authors unfamiliar with standard characterization methods of photocatalysts as well as with the procedures needed to determine photocatalytic activities based on the determination of “apparent quantum efficiencies” within a wavelength interval or “apparent quantum yields” in the case of using monochromatic ...


Design And Analysis Of A 3d-Printed, Thermoplastic Elastomer (Tpe) Spring Element For Use In Corrective Hand Orthotics, Kevin Thomas Richardson Jan 2018

Design And Analysis Of A 3d-Printed, Thermoplastic Elastomer (Tpe) Spring Element For Use In Corrective Hand Orthotics, Kevin Thomas Richardson

Theses and Dissertations--Mechanical Engineering

This thesis proposes an algorithm that determine the geometry of 3D-printed, custom-designed spring element bands made of thermoplastic elastomer (TPE) for use in a wearable orthotic device to aid in the physical therapy of a human hand exhibiting spasticity after stroke. Each finger of the hand is modeled as a mechanical system consisting of a triple-rod pendulum with nonlinear stiffness at each joint and forces applied at the attachment point of each flexor muscle. The system is assumed quasi-static, which leads to a torque balance between the flexor tendons in the hand, joint stiffness and the design force applied to ...


Band Offsets At The Interface Between Crystalline And Amorphous Silicon From First Principles, Karol Jarolimek, E. Hazrati, R. A. De Groot, D. A. De Wijs Jul 2017

Band Offsets At The Interface Between Crystalline And Amorphous Silicon From First Principles, Karol Jarolimek, E. Hazrati, R. A. De Groot, D. A. De Wijs

Center for Applied Energy Research Faculty Publications

The band offsets between crystalline and hydrogenated amorphous silicon (a−Si∶H) are key parameters governing the charge transport in modern silicon heterojunction solar cells. They are an important input for macroscopic simulators that are used to further optimize the solar cell. Past experimental studies, using x-ray photoelectron spectroscopy (XPS) and capacitance-voltage measurements, have yielded conflicting results on the band offset. Here, we present a computational study on the band offsets. It is based on atomistic models and density-functional theory (DFT). The amorphous part of the interface is obtained by relatively long DFT first-principles molecular-dynamics runs at an elevated temperature ...


Analytical Strip Method For Thin Cylindrical Shells, John T. Perkins Jan 2017

Analytical Strip Method For Thin Cylindrical Shells, John T. Perkins

Theses and Dissertations--Civil Engineering

The Analytical Strip Method (ASM) for the analysis of thin cylindrical shells is presented in this dissertation. The system of three governing differential equations for the cylindrical shell are reduced to a single eighth order partial differential equation (PDE) in terms of a potential function. The PDE is solved as a single series form of the potential function, from which the displacement and force quantities are determined. The solution is applicable to isotropic, generally orthotropic, and laminated shells. Cylinders may have simply supported edges, clamped edges, free edges, or edges supported by isotropic beams. The cylindrical shell can be stiffened ...


Assessment Of Potential Impacts To Surface And Subsurface Water Bodies Due To Longwall Mining, Christopher R. Newman, Zacharias Agioutantis, Gabriel Boede Jimenez Leon Jan 2017

Assessment Of Potential Impacts To Surface And Subsurface Water Bodies Due To Longwall Mining, Christopher R. Newman, Zacharias Agioutantis, Gabriel Boede Jimenez Leon

Mining Engineering Faculty Publications

Ground movements due to longwall mining operations have the potential to damage the hydrological balance within as well as outside the mine permit area in the form of increased surface ponding and changes to hydrogeological properties. Recently, the Office of Surface Mining, Reclamation and Enforcement (OSMRE) in the USA, has completed a public comment period on a newly proposed rule for the protection of streams and groundwater from adverse impacts of surface and underground mining operations (80 FR 44435). With increased community and regulatory focus on mining operations and their potential to adversely affect streams and groundwater, now there is ...


Spray Printing Of Organic Semiconducting Single Crystals, Grigorios-Panagiotis Rigas, Marcia M. Payne, John E. Anthony, Peter N. Horton, Fernando A. Castro, Maxim Shkunov Nov 2016

Spray Printing Of Organic Semiconducting Single Crystals, Grigorios-Panagiotis Rigas, Marcia M. Payne, John E. Anthony, Peter N. Horton, Fernando A. Castro, Maxim Shkunov

Chemistry Faculty Publications

Single-crystal semiconductors have been at the forefront of scientific interest for more than 70 years, serving as the backbone of electronic devices. Inorganic single crystals are typically grown from a melt using time-consuming and energy-intensive processes. Organic semiconductor single crystals, however, can be grown using solution-based methods at room temperature in air, opening up the possibility of large-scale production of inexpensive electronics targeting applications ranging from field-effect transistors and light-emitting diodes to medical X-ray detectors. Here we demonstrate a low-cost, scalable spray-printing process to fabricate high-quality organic single crystals, based on various semiconducting small molecules on virtually any substrate by ...


First-Principles Studies Of Structure-Property Relationships: Enabling Design Of Functional Materials, Qunfei Zhou Jan 2016

First-Principles Studies Of Structure-Property Relationships: Enabling Design Of Functional Materials, Qunfei Zhou

Theses and Dissertations--Chemical and Materials Engineering

First-principles calculations based on quantum mechanics have been proved to be powerful for accurately regenerating experimental results, uncovering underlying myths of experimental phenomena, and accelerating the design of innovative materials. This work has been motivated by the demand to design next-generation thermionic emitting cathodes and techniques to allow for synthesis of photo-responsive polymers on complex surfaces with controlled thickness and patterns. For Os-coated tungsten thermionic dispenser cathodes, we used first-principles methods to explore the bulk and surface properties of W-Os alloys in order to explain the previously observed experimental phenomena that thermionic emission varies significantly with W-Os alloy composition. Meanwhile ...


Microindentation Of Bi57in26sn17 Lead-Free Alloy, Ruiting Zhao Jan 2015

Microindentation Of Bi57in26sn17 Lead-Free Alloy, Ruiting Zhao

Theses and Dissertations--Chemical and Materials Engineering

There is great need to understand the mechanical properties of lead-free alloys—an alternative of lead-based alloys—to address the environmental problems associated with the use of lead-based materials in microelectronics. In this work, the microstructures of Bi57In26Sn17 lead-free alloy were examined using Optical Microscopy and Energy Dispersive X-ray Spectroscopy analysis. The micro-indentation technique was used to study the mechanical properties of Bi57In26Sn17 lead-free alloy. The experimental results of the hardness and contact modulus were presented and discussed. Local creep during the indentation was observed from the load-displacement curves. The Vickers hardness (HV) increases with the decrease of the indentation ...


High Temperature Flow Solver For Aerothermodynamics Problems, Huaibao Zhang Jan 2015

High Temperature Flow Solver For Aerothermodynamics Problems, Huaibao Zhang

Theses and Dissertations--Mechanical Engineering

A weakly ionized hypersonic flow solver for the simulation of reentry flow is firstly developed at the University of Kentucky. This code is the fluid dynamics module of known as Kentucky Aerothermodynamics and Thermal Response System (KATS). The solver uses a second-order finite volume approach to solve the laminar Navier– Stokes equations, species mass conservation and energy balance equations for flow in chemical and thermal non-equilibrium state, and a fully implicit first-order backward Euler method for the time integration. The hypersonic flow solver is then extended to account for very low Mach number flow using the preconditioning and switch of ...


Experimental Comparison Study Of The Response Of Polycarbonate And Laminated Glass Blast Resistant Glazing Systems To Blast Loading, Joshua Calnan Jan 2013

Experimental Comparison Study Of The Response Of Polycarbonate And Laminated Glass Blast Resistant Glazing Systems To Blast Loading, Joshua Calnan

Theses and Dissertations--Mining Engineering

This thesis recounts the experimental study of the dynamic response of polycarbonate blast resistant glazing systems to explosive loading through the use of triaxial load cells, pressure sensors, and a laser displacement gauge. This instrumentation captured the response of the glazing systems to blast loading over three phases of testing. The first phase of testing characterizes the load distribution around the perimeter and the second phase examines the repeatability of the results. The final phase of testing pushes the samples to failure. The results are then compared to HazL, a commonly used blast resistant glazing system analysis software tool. The ...


Active Optimal Control Strategies For Increasing The Efficiency Of Photovoltaic Cells, Sharif Aljoaba Jan 2013

Active Optimal Control Strategies For Increasing The Efficiency Of Photovoltaic Cells, Sharif Aljoaba

Theses and Dissertations--Electrical and Computer Engineering

Energy consumption has increased drastically during the last century. Currently, the worldwide energy consumption is about 17.4 TW and is predicted to reach 25 TW by 2035. Solar energy has emerged as one of the potential renewable energy sources. Since its first physical recognition in 1887 by Adams and Day till nowadays, research in solar energy is continuously developing. This has lead to many achievements and milestones that introduced it as one of the most reliable and sustainable energy sources. Recently, the International Energy Agency declared that solar energy is predicted to be one of the major electricity production ...


Finite Element Analysis Of The Contact Deformation Of Piezoelectric Materials, Ming Liu Jan 2012

Finite Element Analysis Of The Contact Deformation Of Piezoelectric Materials, Ming Liu

Theses and Dissertations--Chemical and Materials Engineering

Piezoelectric materials in the forms of both bulk and thin-film have been widely used as actuators and sensors due to their electromechanical coupling. The characterization of piezoelectric materials plays an important role in determining device performance and reliability. Instrumented indentation is a promising method for probing mechanical as well as electrical properties of piezoelectric materials.

The use of instrumented indentation to characterize the properties of piezoelectric materials requires analytical relations. Finite element methods are used to analyze the indentation of piezoelectric materials under different mechanical and electrical boundary conditions.

For indentation of a piezoelectric half space, a three-dimensional finite element ...


Nanostructured Arrays For Sensing And Energy Storage Applications, Raghu Mangu Jan 2011

Nanostructured Arrays For Sensing And Energy Storage Applications, Raghu Mangu

University of Kentucky Doctoral Dissertations

Vertically aligned multi walled carbon nanotube (MWCNT) arrays fabricated by xylene pyrolysis in anodized aluminum oxide (AAO) templates without the use of a catalyst, were integrated into a resistive sensor design. The steady state sensitivities as high as 5% and 10% for 100 ppm of NH3 and NO2 respectively at a flow rate of 750 sccm were observed. A study was undertaken to elucidate (i) the dependence of sensitivity on the thickness of amorphous carbon layers, (ii) the effect of UV light on gas desorption characteristics and (iii) the dependence of room temperature sensitivity on different NH3 ...


Monitoring The Dynamics Of Scaled Vehicles Using A Sonic Digitizer, Michael J. Bader, Larry G. Wells, Linus R. Walton Jan 1996

Monitoring The Dynamics Of Scaled Vehicles Using A Sonic Digitizer, Michael J. Bader, Larry G. Wells, Linus R. Walton

Biosystems and Agricultural Engineering Faculty Publications

Certain dynamic stability characteristics of an alternate method of mounting a front-end loader to a farm tractor were compared to those of a conventionally mounted front-end loader operating on a specified terrain. One objective of the study was to determine if the alternate method of mounting a front-end loader resulted in better stability characteristics and, in turn, safer operation than a conventional front-end loader. Another objective was to determine if a three-dimensional sonic digitizer could monitor the motion of the scale model tractor-loader systems accurately enough to perform a comparison between the systems. This article describes the second objective of ...