Engineering Commons^™

Developing A Sensing System For The Measurement Of Oxygen Concentration In Liquid Pb-Bi Eutectic, Yingtao Jiang, Bingmei Fu

Transmutation Sciences Materials (TRP)

The research objectives of this project were as follows:

• To generate calibration curves of voltage versus oxygen concentration for the YSZ oxygen sensor system under various temperatures in liquid LBE.
• To determine the sensor characteristics of the YSZ sensor system.
• To determine oxygen dissolving rates in LBE under different temperatures in vitro.
• To study the effects of unwanted electrical conductivity, contributed by the mobility of the electrons at high temperatures, for more accurate oxygen measurement.
• To study alternative and promising oxygen measuring methods.

Flow Simulation For Optimized Performance Of Displacement Pumps Manufactured By Engineered Machined Products, Jordan D. Bilyeu

Dissertations, Master's Theses and Master's Reports - Open

No abstract provided.

Fluidic Oscillator Design For Water Removal Enhancement In A Pem Fuel Cell, Sheng Han Tseng

Dissertations, Master's Theses and Master's Reports - Open

This research initiative was triggered by the problems of water management of Polymer Electrolyte Membrane Fuel Cell (PEMFC). In low temperature fuel cells such as PEMFC, some of the water produced after the chemical reaction remains in its liquid state. Excess water produced by the fuel cell must be removed from the system to avoid flooding of the gas diffusion layers (GDL). The GDL is responsible for the transport of reactant gas to the active sites and remove the water produced from the sites. If the GDL is flooded, the supply gas will not be able to reach the reactive …

A Mass-Spring-Damper Model Of A Bouncing Ball, Mark L. Nagurka, Shuguang Huang

Mechanical Engineering Faculty Research and Publications

The mechanical properties of a vertically dropped ball, represented by an equivalent mass-spring-damper model, are shown to be related to impact parameters. In particular, the paper develops relationships connecting the mass, stiffness and damping of a linear ball model to the coefficient of restitution and the contact time of the ball with the surface during one bounce. The paper also shows that the ball model parameters are functions of quantities readily determined in an experiment: (i) the height from which the ball is dropped from rest, (ii) the number of bounces, and (iii) the time elapsing between dropping the ball …

Robust Design And Model Validation Of Nonlinear Compliant, Michael S. Baker, Larry Howell, Jonathan W. Walker

Faculty Publications

Although the use of compliance or elastic flexibility in microelectromechanical systems (MEMS) helps eliminate friction, wear, and backlash, compliant MEMS are known to be sensitive to variations in material properties and feature geometry, resulting in large uncertainties in performance. This paper proposes an approach for design stage uncertainty analysis, model validation, and robust optimization of nonlinear MEMS to account for critical process uncertainties including residual stress, layer thicknesses, edge bias, and material stiffness. A fully compliant bistable micromechanism (FCBM) is used as an example, demonstrating that the approach can be used to handle complex devices involving nonlinear finite element models. …

Techniques In The Design Of Thermomechanical Microactuators, Larry L. Howell, Timothy W. Mclain, Michael S. Baker, Christian D. Lott

Faculty Publications

The purpose of this chapter is to provide fundamental background for the design of thermomechanical microactuators. Actuation has been a particularly challenging aspect of microsystem development. Many actuation approaches used at the macro level, such as hydraulics, pneumatics, electric motors, internal combustion engines and turbines, are either too difficult to fabricate at the micro level or do not work well at that scale. Electrostatic attraction is one approach that has been widely used for actuation of microsystems; however, electrostatic actuators tend to have high voltage requirements and low output force capabilities. While electrostatic actuation is suitable for many applications, some …

New Ultra-Lightweight Stiff Panels For Space Apertures, Jonathan T. Black

University of Kentucky Doctoral Dissertations

Stiff, ultra-lightweight thermal-formed polyimide panels considered in this dissertation are examples of next generation gossamer structures that resolve some of the technology barriers of previous, membrane-dominated gossamer designs while maintaining their low mass and low stowage volume characteristics. The research involved statically and dynamically characterizing and modeling several of these panels to develop validated computer models which can be used to determine the effects of changing manufacturing parameters and scalability. Static characterization showed substantial local nonlinear behavior that was replicated by new physics-based finite element models, and global linear bending behavior that was modeled using classical shell finite elements incorporating …

Active Flow Control Of Low Pressure Turbine Blade Separation Using Plasma Actuators, Karthik Ramakumar

University of Kentucky Master's Theses

The current study examines plasma actuators as flow control devices. The actuators are placed on a turbine blade profile in a 2D turbine cascade for separation flow control. The configuration involves copper strips separated by a layer of dielectric material, across which an AC electric potential in the range of 5 kHz and 5 kV is applied. The efficiency of the actuator is monitored by measuring power input and flow control effectiveness. Preliminary observations are performed for a quiescent case on a flat plate profile to analyze the average and instantaneous velocities generated by the actuator for varied input parameters, …

Unsymmetrical And Symmetrical Sparse Iterative Algorithm With Multiple Right-Hand-Sides Strategies, D. T. Nguyen, A. P. Honrao, G. Hou, O. Akan, O. Baysal

Civil & Environmental Engineering Faculty Publications

Unified unsymmetrical and symmetrical iterative solvers for handling multiple right-hand-side vectors are examined in this work. Efficient computer implementation strategies (to reduce computational time and in-core memory requirements) are proposed. In-core, out-of-core, linear, multiple right hand side (RHS) vectors, non-linear, symmetrical, and unsymmetrical capabilities of the developed software are demonstrated by solving variety of problems selected form different engineering disciplines. Results indicate that the developed algorithm and software is reliable and efficient.

Heat Transfer And Chemical Processes In Chemical Vapor Deposition Reactor For Synthesis Of Carbon Nanotubes, Wahed Rezk Wasel

University of Kentucky Doctoral Dissertations

A small-scale model of a CVD reactor was built. Axial and radial of major species concentrations and temperature profiles were obtained with a micro gas chromatograph and a fine thermocouple. Those temperature and species concentrations revealed detailed thermal and chemical structures of the CVD reactor.

The concentrations of argon plus hydrogen, methane, and C₂H_x (C₂H₂ + C₂H₄ + C₂H₆) resulting from xylene decomposition were measured along the CVD at different temperatures. Ferrocene was added to xylene to investigate the effect of a catalyst on composition profiles. The …

A Numerical Acoustic Fluid-Structure Simulation Of Therapeutic Ultrasound Angioplasty, Graham Gavin, Finbar Dolan, M.S J. Hashmi, Garrett Mcguinness

Conference Papers

INTRODUCTION Therapeutic ultrasound angioplasty is the delivery of high amplitude ultrasonic displacements to the distal-tip of small diameter wire waveguides with the goal of disrupting atherosclerotic plaques. This is a minimally invasive procedure that may have potential' in the treatment of complicated chronic total occlusions. The disruption of plaque is due to direct contact ablation and also cavitation, pressure waves and acoustic streaming in the fluid surrounding the vibrating waveguide distal-tip [1]. Cavitation appears to play a major role and some authors have suggested that plaque ablation is only evident above the cavitation threshold [2]. Makin and Everbach [3] performed …

A Numerical Acoustic Fluid-Structure Model Of A Therapeutic Ultrasound Angioplasty Device, Graham Gavin, M.S. J. Hashmi, Finbar Dolan, Garrett Mcguinness

Conference Papers

Ultrasonic angioplasty involves the use of ultrasonic vibrations delivered to the distal-tip of small diameter wire waveguides and is an emerging technology the may have potential use in the treatment of complicated atherosclerotic plaques during cardiovascular surgery. Complicated plaques, including chronic total occlusions and calcified lesions, seriously reduce success rates during standard intervention involving guidewire access, followed by balloon dilation or stent delivery. The large amplitude (0-150 μm) wire waveguide distal-tip displacements in the low-frequency ultrasonic (18-45 kHz) range have been shown to disrupt plaque material by direct contact ablation and cavitation, acoustic streaming and pressure wave components in adjacent …

The Tromped, An In-Flight Exercise Device To Prevent Flight Related Deep Vein Thrombosis, Carolyn Collins, David Kennedy, Thomas Corrigan, Stephen Jerrams

Conference Papers

Medical and Engineering research studies have shown the potential risks of long haul flight travel and methods of preventing it occurring. The risk of serious health problems or even death is known to arise from lack of venous movement and increased coagulation (clotting) of the blood. These factors contribute to the development of deep vein thrombosis (DVT) and this is more likely to occur in situations where people are seated for long periods during travel on land or in air. Currently long haul airlines have yet to be seen to introduce physical preventative measures against this syndrome.

A prototype design …

The Role And Future Of Nanotechnology In Research, Industry And Education, David Kennedy

Conference Papers

Major developments in Nanotechnology have taken place across the world
over the last few years. From a humble beginning, Ireland inc. became a leader in the Microelectronics industry and now has to face the challenge of developing a strategic plan to maintain its lead position in the nano field which in most cases will supersede the micro phase. Most countries are taking a similar path of development all be it alone or in collaboration with other countries. This process is expensive and requires market drivers and experts to lead and deliver demands from the industries of the future. The approach …

Neural Network Approach For Obstacle Avoidance In 3-D Environments For Uavs, Vivek Yadav, Xiaohua Wang, S. N. Balakrishnan

Mechanical and Aerospace Engineering Faculty Research & Creative Works

In this paper a controller design is proposed to get obstacle free trajectories in a three dimensional urban environment for unmanned air vehicles (UAVs). The controller has a two-layer architecture. In the upper layer, vision-inspired Grossberg neural network is proposed to get the shortest distance paths. In the bottom layer, a model predictive control (MPC) based controller is used to obtain dynamically feasible trajectories. Simulation results are presented for to demonstrate the potential of the approach.

Plasma Modeling For Ultrashort Laser Ablation Of Dielectrics, Lan Jiang, Hai-Lung Tsai

Mechanical and Aerospace Engineering Faculty Research & Creative Works

In ultrashort pulse (<10 ps) laser ablation of dielectrics, affected materials are first transformed into absorbing plasma with metallic properties and, then, the subsequent laser-plasma interaction causes material removals. For ultrashort-pulse laser ablation of dielectrics, this study proposes a model using the Fokker-Planck equation for electron density distribution, a plasma model for the optical properties of ionized dielectrics, and quantum treatments for electron heating and relaxation time. The free electron density distribution of the plasma within the pulse duration is then used to determine the ablation crater shape. The predicted threshold fluences and ablation depths for barium aluminum borosilicate and fused silica are in agreement with published experimental data. It is found that the significantly varying optical properties in time and space are the key factors determining the ablation crater shape. The effects of fluence and pulse duration are also studied.

Dynamic Re-Optimization Of A Spacecraft Attitude Controller In The Presence Of Uncertainties, Nishant Unnikrishnan, S. N. Balakrishnan, Radhakant Padhi

Mechanical and Aerospace Engineering Faculty Research & Creative Works

Online trained neural networks have become popular in recent years in the design of robust and adaptive controllers for dynamic systems with uncertainties due to their universal function approximation capabilities. This paper discusses a technique that dynamically reoptimizes a Single Network Adaptive Critic (SNAC) based optimal controller in the presence of unmodeled plant uncertainties. The SNAC based optimal controller designed for the nominal plant model no more retains optimality in the presence of uncertainties/unmodeled dynamics that may creep up in the system equations during operation. This calls for a strategy to re-optimize the existing SNAC controller with respect to the …

Neural Network Control Of Spark Ignition Engines With High Egr Levels, A. Singh, Brian C. Kaul, J. A. Drallmeier, Jagannathan Sarangapani, Jonathan B. Vance

Mechanical and Aerospace Engineering Faculty Research & Creative Works

Research has shown substantial reductions in the oxides of nitrogen (NOx) concentrations by using 10% to 25% exhaust gas recirculation (EGR) in spark ignition (SI) engines [1]. However under high EGR levels the engine exhibits strong cyclic dispersion in heat release which may lead to instability and unsatisfactory performance. A suite of neural network (NN)-based output feedback controllers with and without reinforcement learning is developed to control the SI engine at high levels of EGR even when the engine dynamics are unknown by using fuel as the control input. A separate control loop was designed for controlling EGR levels. The …

Effects Of Welding Current In Gas Metal Arc Welding, Junling Hu, Tai Lung Tsai

Mechanical and Aerospace Engineering Faculty Research & Creative Works

In gas metal arc welding (GMAW), current is one of the most important factors affecting the mode of metal transfer, weld pool dynamics and subsequently the weld quality. in this paper, the comprehensive model recently developed by the authors was used to study the effects of different current levels on the droplet formation, plasma generation, metal transfer, and weld pool dynamics in GMA welding. Two welding currents were studied, including one low current and one high current. at each current level, the transient temperature and velocity distributions of the arc plasma and the molten metal, and the shapes of the …

Method Of Improving Weld Quality, P.-C. Wang, Hai-Lung Tsai, R. J. Menassa

Mechanical and Aerospace Engineering Faculty Research & Creative Works

A method of improving weld quality between aluminum members by slowing the rate of solidification of a molten weld trough into solidified material. Upper and lower aluminum members are positioned together in contact between facing surfaces thereof to expose a first outer surface of the upper aluminum member to laser irradiation. A welding laser beam is moved in a path over the first outer surface, wherein the welding laser beam has an energy and width to progressively melt a trough of molten metal to a depth through the upper aluminum member and into the lower aluminum member. The molten metal …

An Internet Based Intelligent Argumentation System For Collaborative Engineering Design, Xiaoqing Frank Liu, Samir Raorane, Man Zheng, Ming-Chuan Leu

Computer Science Faculty Research & Creative Works

Modern product design is a very complicated process which involves groups of designers, manufacturers, suppliers, and customer representatives. Conflicts are unavoidable in collaboration among multiple stakeholders, who have different objectives, requirements, and priorities. Unfortunately, current web-based collaborative engineering design systems do not support collaborative conflict resolution. In this paper, we will develop an intelligent computational argumentation model to enable management of a large scale argumentation network, and resolution of conflicts based on argumentation from many participants. A web-based intelligent argumentation tool is developed as a part of a web-based collaborative engineering design system based on the above model to resolve …

Neural Network-Based Output Feedback Controller For Lean Operation Of Spark Ignition Engines, Brian C. Kaul, Jagannathan Sarangapani, J. A. Drallmeier, Jonathan B. Vance, Pingan He

Electrical and Computer Engineering Faculty Research & Creative Works

Spark ignition (SI) engines running at very lean conditions demonstrate significant nonlinear behavior by exhibiting cycle-to-cycle dispersion of heat release even though such operation can significantly reduce NOx emissions and improve fuel efficiency by as much as 5-10%. A suite of neural network (NN) controller without and with reinforcement learning employing output feedback has shown ability to reduce the nonlinear cyclic dispersion observed under lean operating conditions. The neural network controllers consists of three NN: a) A NN observer to estimate the states of the engine such as total fuel and air; b) a second NN for generating virtual input; …

An Experimental Investigation Of Guided Wave Propagation In Corrugated Plates Showing Stop Bands And Pass Bands, Tribikram Kundu, Sourav Banerjee, Kumar V. Jata

Faculty Publications

Nonplanar surfaces are often encountered in engineering structures. In aerospace structures, periodically corrugated boundaries are formed by friction-stir-welding. In civil engineering structures, rebars used in reinforced concrete beams and slabs have periodic surface. Periodic structures are also being used to create desired acoustic band gaps. For health monitoring of these structures, a good understanding of the elastic wave propagation through such periodic structures is necessary. Although a number of research papers on the wave propagation in periodic structures are available in the literature, no one experimentally investigated the guided wave propagation through plates with periodic boundaries and compared the experimental …

Elastic Wave Propagation In Sinusoidally Corrugated Waveguides, Sourav Banerjee, Tribikram Kundu

Faculty Publications

The ultrasonicwave propagation in sinusoidally corrugated waveguides is studied in this paper. Periodically corrugated waveguides are gaining popularity in the field of vibration control and for designing structures with desired acoustic band gaps. Currently only numerical method (Boundary Element Method or Finite Element Method) based packages (e.g., PZFlex) are in principle capable of modeling ultrasonic fields in complex structures with rapid change of curvatures at the interfaces and boundaries but no analyses have been reported. However, the packages are very CPU intensive; it requires a huge amount of computation memory and time for its execution. In this paper a new …

Uv-Liga Micro-Fabrication Of Inertia Type Electrostatic Transducers And Their Application, Seok Jae Jeong

LSU Doctoral Dissertations

This dissertation discusses the design, working principles, static & dynamic analysis and simulation, mechanics of material, applied MEMS technology, micro-fabrication, and experimental testing of two types of micro-transducers: micro-power relay and micro-accelerometer. Several possible design concepts were proposed, and the advantages and disadvantages of electrostatic working principles were also discussed. Transducers presented in this research used electrostatic force as a driving force in the micro-relay and capacitance as a sensing parameter in the micro-accelerometer. There was an analogy between the micro-relay and the micro-accelerometer in their theoretical approach and fabrication processes. The proposed micro-transducers (micro-relay and micro-accelerometer) were fabricated using …

Effect Of Bulk Flow Modulations On A Normal Jet In Crossflow At A Mean Blowing Ratio Of 0.25, Jeremiah Oertling

LSU Master's Theses

An experimental wind tunnel has been designed, built, outfitted with automated hot wire anemometry and laser sheet imagery systems methods of instrumentation and tested with the purpose of performing scientific research on the control and stabilization of a jet issuing 90 degrees into a crossflow. After the design and system characterizations were performed, the system was employed as a experimental platform to conduct an investigation of bulk flow modulation of a jet in crossflow. The Mean Blowing ratio investigated was set at 0.25, and the effect of duty cycle, peak to peak blowing ratio and frequency of excitation are investigated. …

Theory Of Curvature-Dependent Disjoining Pressure And Its Application To Liquid Films, Jin Zhang

LSU Doctoral Dissertations

A liquid film of thickness h < 100 nm is subject to additional intermolecular forces, which are collectively called disjoining pressure Pi. Since Pi dominates at small film thicknesses, it determines the stability and wettability of thin films. Current theory for uniform films gives Pi = Pi(h). It becomes unbounded as h -> 0. We present a theory of curvature-dependent disjoining pressure. The new Pi depends on the curvature hxx, slope hx, and h. When this theory is implemented for Lennard-Jones liquid films, the new Pi is bounded as h -> 0. We show that this Pi captures three regimes of drop behavior (complete wetting, partial wetting, and pseudo partial wetting) without altering the signs of the long and short-range interactions. We also find that a drop with a uniform film is linearly stable, whereas a drop without a uniform film is unstable. Evaporating thin films is …

Accelerating Micro-Scale Pcr (Polymerase Chain Reactor) For Modular Lab-On-A-Chip System, Pin-Chuan Chen

LSU Master's Theses

The polymerase chain reaction (PCR) is a powerful technique used to exponentially amplify specific DNA sequences of interest through repetitive temperature cycling. The temperatures used in PCR are typically 90°C - 94°C for denaturation, 50°C - 70°C for renaturation, and 70°C - 75°C for extension. The double-stranded helix of nucleotides, carrying the genetic information, is separated during denaturation, reacts with chemical primers during renaturation, and becomes a complete, replica, double-stranded DNA helix structure during extension. The primary drawback of current commercial benchtop PCR machine is its cycle time due to its large thermal capacitance, and micro PCR is under developing …

Study Of Particle Growth And Breakdown In Single Size Gamma Prime Distribution And High Temperature Creep In In738lc Nickel Superalloy, Arvind Kumar Dwarapureddy

LSU Master's Theses

IN738LC, a nickel based superalloy has wide applications in the gas turbine engines because of its ability to retain its strength at high temperatures involved. The stability of the γ' Ni₃Al (Ti, Nb) precipitate microstructure which gives the alloy its strength is very important. After an initial annealing at 1200°C for 4 hours and water quenching, a uniform distribution of single size (70nm) γ' fine precipitates is obtained. Growth of the γ' particles, their size and distribution are studied after subsequent annealing heat treatments, conducted at different temperatures for different time periods. The average precipitate size data of …

Mesoscale Predictions For The Dynamic Compaction Of Explosively-Coated Aluminum Micro-Particles, Michael Wayne Crochet

LSU Master's Theses

Conventional granular explosives are widely used in aerospace and defense-related industries. Powdered metals are often mixed with high explosives to enhance detonation. The effectiveness of these mixtures is limited by the slow burning of the metal relative to the explosive and their sensitivity to mechanical loading. Granular energetic composites, composed of an aluminum core coated with a layer of the high explosive RDX (C₃H₆N₆O₆), may be a high-performance alternative to conventional explosives because of a higher metal combustion rate and lower impact sensitivity. Though the technology required to manufacture granular energetic composites …