Mechanical Engineering Commons^™

Nonparametric Estimation Of Derivatives With Applications, Benjamin Hall

University of Kentucky Doctoral Dissertations

We review several nonparametric regression techniques and discuss their various strengths and weaknesses with an emphasis on derivative estimation and confidence band creation. We develop a generalized C(p) criterion for tuning parameter selection when interest lies in estimating one or more derivatives and the estimator is both linear in the observed responses and self-consistent. We propose a method for constructing simultaneous confidence bands for the mean response and one or more derivatives, where simultaneous now refers both to values of the covariate and to all derivatives under consideration. In addition we generalize the simultaneous confidence bands to account for heteroscedastic …

Laminar-Turbulent Transition For Attached And Separated Flow, Qian Zhang

University of Kentucky Doctoral Dissertations

A major challenge in the design of turbomachinery components for aircraft gas turbine engines is high cycle fatigue failures due to flutter. Of particular concern is the subsonic/transonic stall flutter boundary which occurs at part speed near the stall line. At these operating conditions the incidence angle is large and the relative Mach number is high subsonic or transonic. Viscous effects dominate for high incidence angles.

In order to predict the flutter phenomena, accurate calculation of the steady and unsteady aerodynamic loading on the turbomachinery airfoils is necessary. The development of unsteady aerodynamic models to predict the unsteady forces and …

Engineering Sport Safety: A Study Of Equestrian Cross Country Eventing, Katherine M. Kahmann

University of Kentucky Master's Theses

The sport of equestrian cross country eventing has seen many serious and even fatal injuries due to rotational horse falls in recent years. The sport originally consisted of horse and rider teams jumping stationary, wood fences. However, in a move towards increasing safety for horses and riders, frangible and deformable safety devices have been emerging in the field. This thesis provides an overview of safety designs that are currently available and those that are on the horizon. Also, a path-finder method of evaluating and developing safety fence designs was outlined and applied to two distinct designs, a hinged gate and …

Interfacial Thermal Conductivity Using Multiwall Carbon Nanotubes, Carissa Don Russell

University of Kentucky Master's Theses

Shrinking volume, coupled with higher performance, microprocessors and integrated circuits have led to serious heat dissipation issues. In an effort to mitigate the excessive amounts of waste heat and ensure electronic survivability, heat sinks and spreaders are incorporated into heat generating device structures. This inevitability creates a thermal pathway through an interface. Thermal interfaces can possess serious thermal resistances for heat conduction. The introduction of a thermal interface material (TIM) can drastically increase the thermal performance of the component. Exceptional thermal properties of multiwall carbon nanotubes (MWCNTs) have spurred interest in their use as TIMs. MWCNTs inherently grow in vertically-oriented, …

Transitional Flow Prediction Of A Compressor Airfoil, Vivek Hariharan

University of Kentucky Master's Theses

The steady flow aerodynamics of a cascade of compressor airfoils is computed using a two-dimensional thin layer Navier-Stokes flow solver. The Dhawan and Narasimha transition model and Mayle‟s transition length model were implemented in this flow solver so that transition from laminar to turbulent flow could be included in the computations. A method to speed up the convergence of the fully turbulent calculations has been introduced. In addition, the effect of turbulence production formulations and including streamline curvature correction in the Spalart-Allmaras turbulence model on the transition calculations is studied. These transitional calculations are correlated with the low and high …

Characterization Of Defects In Metal Sheets Via Infrared Thermography, Marc Anthony Harik

University of Kentucky Master's Theses

Defects in Aluminum, Stainless steel and galvanized steel sheets are studied in reflection mode infrared thermography. The effect of material properties, surface finish, heating intensity, heater emission spectra, pixel size and defect size are studied. Contrast is governed by heat quality, emissivity and defect geometry—which follows a logarithmic trend. The diameter detected via infrared thermography is found to be at least 30% larger than the measured diameter and sub-pixel defects can be detected. The use of gradient and Laplacian of temperature is introduced as a means of increasing defect contrast and mitigating heater variation.

Sustainable Resource Utilization In Manufacturing Of Printed Circuit Board Assembly: Exergy Analysis Of The Process, Subramaniam Saiganesh

University of Kentucky Master's Theses

Engineering for sustainable development requires prudent utilization of resources under economic, environmental and societal constraints. Resource utilization must follow a holistic approach. This brings in a need for comprehensive metrics which are simple, standard and universal. Thermodynamics may offer a metric that focuses on both quality and quantity of energy resources which may carry information to be combined with other metrics. This metric may be a thermodynamic property called exergy or available energy, which provides a better insight into resource use in both energy and non-energy producing systems. This thesis is devoted to a study of the exergy concept in …

Characterization Of Ni-Rich Nitihf Based High Temperature Shape Memory Alloys, Gurdish S. Ded

University of Kentucky Master's Theses

Among the potential high temperature shape memory alloys, due to its low cost, medium ductility and high work output NiTiHf seems to be the most promising HTSMA for a wide range of applications in the 100-250ºC. A detailed investigation into the shape memory properties and transformation behavior for the Ni-rich HTSMA with the compositions of Ni_45.3Cu₅Ti_29.7Hf₂₀, Ni_50.3Ti_29.7Hf₂₀ and Ni_45.3Pd₅Ti_29.7Hf₂₀ was carried out. It is possible to form Ni-rich precipitates in Ni-rich NiTiHf alloys and tailor the TTs by heat treatments …

Numerical Modeling Of The Dynamic Response Of A Multi-Bilinear-Spring Support System, Trey D. Gilliam

University of Kentucky Master's Theses

The Alpha Magnetic Spectrometer is an International Space Station Experiment that features a unique nonlinear support system with no previous flight heritage. The experiment consists of multiple straps with piecewise-linear stiffness curves that support a cryogenic magnet in three-dimensional space inside of a vacuum chamber. The stiffness curves for each strap are essentially bilinear and switch between two distinct slopes at a specified displacement. This highly nonlinear support system poses many questions in regards to feasible computational methods of analysis and possible response behavior. This thesis develops a numerical model for a multi-bilinear-spring support system motivated by the Alpha Magnetic …

Near-Field Radiative Transfer: Thermal Radiation, Thermophotovoltaic Power Generation And Optical Characterization, Mathieu Francoeur

University of Kentucky Doctoral Dissertations

This dissertation focuses on near-field radiative transfer, which can be defined as the discipline concerned with energy transfer via electromagnetic waves at sub-wavelength distances. Three specific subjects related to this discipline are investigated, namely nearfield thermal radiation, nanoscale-gap thermophotovoltaic (nano-TPV) power generation and optical characterization. An algorithm for the solution of near-field thermal radiation problems in one-dimensional layered media is developed, and several tests are performed showing the accuracy, consistency and versatility of the procedure. The possibility of tuning near-field radiative heat transfer via thin films supporting surface phononpolaritons (SPhPs) in the infrared is afterwards investigated via the computation of …

Device And Methods For Atomizing Fluids, Vedanth Srinivasan, Abraham J. Salazar, Kozo Saito, Richard Alloo, Sakakibara Masahito

Mechanical Engineering Faculty Patents

One embodiment of the invention is directed to an apparatus for atomizing a fluid. This apparatus includes an atomizing nozzle assembly. The atomizing nozzle assembly includes: a spray applicator enclosure having a fluid entry zone, a flow shape profiler region, a transducer, and a cavitation enhancer module, wherein the cavitation enhancer module includes a residence modulation zone and the residence modulation zone includes a backward facing step region. The apparatus is configured such that fluid can enter the fluid entry zone to the nozzle profiler, the transducer and the cavitation enhancer module. Other embodiments relate to methods for atomizing fluids.

Methods And Devices For Cryopreservation Of Biological Cells And Tissues, Dayong Gao, Gary Van Zant, Xiangdong Cui

Mechanical Engineering Faculty Patents

Novel methods, compositions, and devices for achieving optimal cooling of living cells during cryopreservation are disclosed. In one aspect, the method comprises gradually cooling the cell to a first predetermined temperature, followed by rapidly cooling the cell to a second predetermined temperature. In another aspect, a device is described for achieving a desired cooling rate for a cell, comprising a first container for holding a cell, a second container for holding the first container, and optionally a frame for holding the first container in a spaced apart relationship with the second container. The method of the invention comprises placing cells …

Lectures In Elementary Fluid Dynamics: Physics, Mathematics And Applications, James M. Mcdonough

Mechanical Engineering Textbook Gallery

From Chapter 1:

It takes little more than a brief look around for us to recognize that fluid dynamics is one of the most important of all areas of physics—life as we know it would not exist without fluids, and without the behavior that fluids exhibit.

It is the goal of these lecture notes to help students in this process of gaining an understanding of, and an appreciation for, fluid motion—what can be done with it, what it might do to you, how to analyze and predict it.

An Algorithm To Solve The Associative Parallel Machine Scheduling Problem, Mohannad Abdelrahman Shuaib

University of Kentucky Master's Theses

Effective production scheduling is essential for improved performance. Scheduling strategies for various shop configurations and performance criteria have been widely studied. Scheduling in parallel machines (PM) is one among the many scheduling problems that has received considerable attention in the literature. An even more complex scheduling problem arises when there are several PM families and jobs are capable of being processed in more than one such family. This research addresses such a situation, which is defined as an Associative Parallel Machine scheduling (APMS) problem. This research presents the SAPT-II algorithm that solves a highly constrained APMS problem with the objective …

An Evaluation Of The Traveling Wave Ultrasonic Motor For Force Feedback Applications, Nishant Venkatesan

University of Kentucky Master's Theses

The traveling wave ultrasonic motor is considered for use in haptic devices where a certain input-output relation is desired between the applied force and the resulting motion. Historically, DC motors have been the standard choice for this purpose. Owing to its unique characteristics, the ultrasonic motors have been considered an attractive alternative. However, there are some limitations when using the ultrasonic motor for force-feedback applications. In particular, direct torque control is difficult, and the motor can only supply torque in the direction of motion. To accommodate these limitations we developed an indirect control approach. The experimental results demonstrate that the …

Nanomechanical Characterizations Of High Temperature Polymer Matrix Composite Resin: Pmr-15 Polyimide, David C. Jones

University of Kentucky Master's Theses

High Temperature Polymer Matrix Composites (HTPMCs) are widely used by the aerospace industry today because of their high specific strengths, light weight, and the ability to custom tailor their mechanical properties to individual applications. Because of the harsh environmental conditions these materials experience during service use, these composite structures are susceptible to a high rate of thermo-oxidative degradation that ultimately causes premature failure in service. The current knowledge base is lacking in the fundamental spatial variability of the constituent materials upon aging, which precludes composite developers from predicting lifetime mechanical properties of the composites in use. The current study summarizes …

Manufacture, Characterization, And Application Of Multiwall Carbon Nanotube Composite Crylonitrile-Butadiene-Styrene, Daniel Ray Bortz

University of Kentucky Master's Theses

Carbon nanotubes have been studied for nearly two decades and their amazing properties continue to spur intense investigation in the area of polymer composites. In terms of potential commercialization, mutiwall carbon nanotubes (MWCNTs) are currently the most prevalent and economically viable form of nanotubes. Uncovering innovative means to take full advantage of their properties remains a fundamental issue. In this thesis, viability of their use to reinforce polymeric systems is reported. Acrylonitrilebutadiene- styrene (ABS) was used as the host matrix. MWCNTs were introduced to the ABS matrix via melt compounding. The resulting composite was thoroughly rheologically, thermally, and mechanically characterized. …

Visualization And Characterization Of Ultrasonic Cavitating Atomizer And Other Automotive Paint Sprayers Using Infrared Thermography, Nelson Kudzo Akafuah

University of Kentucky Doctoral Dissertations

The disintegration of a liquid jet emerging from a nozzle has been under investigation for several decades. A direct consequence of the liquid jet disintegration process is droplet formation. The breakup of a liquid jet into discrete droplets can be brought about by the use of a diverse forcing mechanism. Cavitation has been thought to assist the atomization process. Previous experimental studies, however, have dealt with cavitation as a secondary phenomenon assisting the primary atomization mechanism. In this dissertation, the role of the energy created by the collapse of cavitation bubbles, together with the liquid pressure perturbation is explicitly configured …

Detailed Surface Analysis Of Lip Seal Elastomers Ran Against Shafts Manufactured With Triangular Cavities, Vetrivel Kanakasabai

University of Kentucky Master's Theses

Previous experimental and theoretical results indicate that the keys to successful radial lip seals are the surface characteristics of the shaft and the microasperity pattern that develops due to wear on the elastomer. In this study, the lip seal was tested against five different patterns of shaft surface: plain stainless steel, triangular cavities oriented towards air, triangular cavities oriented towards oil, triangular cavities leading and triangular cavities lagging. Using Zygo optical profilometer and scanning electron microscope, a thorough surface characterization of the micro-asperities and microcavities is done on the lip seal elastomer. Correlation coefficients were calculated between the surface parameters …

Applications Of Computational Fluid Dynamics To Planetary Atmospheres, Xiaolong Deng

University of Kentucky Doctoral Dissertations

Computational Fluid Dynamics (CFD) has been applied to many areas. As one of the most important fluids, the atmosphere is closely related to people’s life. Studying the atmospheres on other planets can help people understand the Earth’s atmosphere and the climate and weather phenomena in it. Because of the complexity of a planetary atmosphere and the limitation of observations, applying CFD to the study of planetary atmospheres is becoming more and more popular. This kind of CFD simulations will also help people design the mission to the extra planets.

In this dissertation, through CFD simulations, we studied the three important …

Production Sequencing And Stability Analysis Of A Just-In-Time System With Sequence Dependent Setups, John Thomas Henninger

University of Kentucky Doctoral Dissertations

Just-In-Time (JIT) production systems is a popular area for researchers but real-world issues such as sequence dependent setups are often overlooked. This research investigates an approach for determining stability and an approach for mixed product sequencing in production systems with sequence dependent setups and buffer thresholds which signal replenishment of a given buffer. Production systems in this research operate under JIT pull production principles by producing only when demand exists and idle when no demand exists.

In the first approach, an iterative method is presented to determine stability for a multi-product production system that operates with replenishment signals and may …

Lectures On Computational Numerical Analysis Of Partial Differential Equations, James M. Mcdonough

Mechanical Engineering Textbook Gallery

From Chapter 1:

The purpose of these lectures is to present a set of straightforward numerical methods with applicability to essentially any problem associated with a partial differential equation (PDE) or system of PDEs independent of type, spatial dimension or form of nonlinearity.

A Precision Instrument For Research Into Nanolithographic Techniques Using Field-Emitted Electron Beams, King-Fu Hii

University of Kentucky Doctoral Dissertations

Nanomanufacturing is an active research area in academia and industry due to the ever-growing demands for precision surface modifications of thin films or substrates with nanoscale features. Conventional lithographic techniques face many challenges as they approach their fundamental limits. Consequently, new nanomanufacturing tools, fabrication techniques, and precision instruments are being explored and developed to meet these challenges. It has been hypothesized that direct-write nanolithography might be achieved by using a field-emitted electron beam for nanomachining. This dissertation moves this research one step closer by developing a precision instrument that can enable the integration of direct-write nanolithography by a field-emitted electron …

Fabrication And Characterization Of Molecular Spintronics Devices, Pawan Tyagi

University of Kentucky Doctoral Dissertations

Fabrication of molecular spin devices with ferromagnetic electrodes coupled with a high spin molecule is an important challenge. This doctoral study concentrated on realizing a novel molecular spin device by the bridging of magnetic molecules between two ferromagnetic metal layers of a ferromagnetic-insulator-ferromagnetic tunnel junction on its exposed pattern edges. At the exposed sides, distance between the two metal electrodes is equal to the insulator film thickness; insulator film thickness can be precisely controlled to match the length of a target molecule. Photolithography and thin-film deposition were utilized to produce a series of tunnel junctions based on molecular electrodes of …

An Integrated Framework For Applying Lean Manufacturing And Other Strategies In Mass Customization Environments, Gregory Brandon Stump

University of Kentucky Master's Theses

Manufacturing organizations are facing fragmented markets and increased demand of variety from consumers. As a result, many of these firms have adopted mass customization manufacturing strategies in an effort to offer their customers the freedom of choice while maintaining operational efficiency. Lean manufacturing strategies have also seen heavy use in manufacturing environments. This study investigates the possibilities of integrating lean manufacturing principles and practices into mass customization environments in order to improve system performance. The feasibility of other manufacturing strategies such as agility, Quick Response Manufacturing and the Theory of Constraints assisting in the application of lean manufacturing for mass …

Performance Optimization Of A Structured Cfd Code - Ghost On Commodity Cluster Architectures, Pavan K. Kristipati

University of Kentucky Master's Theses

This thesis focuses on optimizing the performance of an in-house, structured, 2D CFD code – GHOST, on commodity cluster architectures. The basic philosophy of the work is to optimize the cache usage of the code by implementing efficient coding techniques without changing the underlying numerical algorithm. Various optimization techniques that were implemented and the resulting changes in performance have been presented. Two techniques, external and internal blocking that were implemented earlier to tune the performance of this code have been reviewed. What follows is further tuning effort in order to circumvent the problems associated with using the blocking techniques. Later, …

Elastic-Plastic Indentation Deformation In Homogeneous And Layered Materials: Finite Element Analysis, Siva Naga Venkata Ravi Kiran Kurapati

University of Kentucky Master's Theses

The complex phenomenon of indentation deformation is studied using finite element analysis for both homogeneous and layered materials. For the homogeneous materials, the elastic-plastic deformation at large indentation depth is studied. The variation of the load-displacement curves as well as the variation of the energy ratio with the applied indentation depth for different strain hardening indices is presented. The power law relation between the indentation load and depth for shallow indentation becomes invalid for deep indentation. The ratio of plastic energy to total mechanical work is a linear function of the ratio of residual indentation depth and maximum indentation depth. …

An Investigation Of Size Effects On Thin Sheet Formability For Microforming Applications, Nasr Abdelrahman Shuaib

University of Kentucky Doctoral Dissertations

The increasing demand for powerful miniaturized products for all industrial applications has prompted the industry to develop new and innovative manufacturing processes to fabricate miniature parts. One of the major challenges facing the industry is the dynamic market which requires continuous improvements in design and fabrication techniques. This means providing products with complex features while sustaining high functionality. As a result, microfabrication has gained a wide interest as the technology of the future, where tabletop machine systems exist. Microforming processes have the capability of achieving mass production while minimizing material waste. Microforming techniques can produce net-shape products with intricacy in …

Investigation Of Blast Mitigation Properties Of Carbon And Polyurethane Based Foams, Bradley E. Toon

University of Kentucky Master's Theses

Solid foams have been studied for years for their ability to mitigate damage from sudden impact. Small explosive attacks threaten to damage or destroy key structures in some parts of the world. A newly developed material, carbon foam, may offer the ability to mitigate the effects of such blasts. This project investigates the energy absorbing properties of carbon and polyurethane based foams in dynamic compression to illustrate their viability to protect concrete structures from the damaging effects of pressure waves from a small blast. Cellular solid mechanics fundamentals and a survey of the microscopic cellular structure of each type of …

Lectures In Computational Fluid Dynamics Of Incompressible Flow: Mathematics, Algorithms And Implementations, James M. Mcdonough

Mechanical Engineering Textbook Gallery

From Prologue:

The present lecture notes are written to emphasize the mathematics of the Navier–Stokes (N.–S.) equations of incompressible flow and the algorithms that have been developed over the past 30 years for solving them.