Mechanical Engineering Commons^™

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 …

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 …

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. …

Characterization And Tribological Behavior Of Diamond-Like Carbon And Nitrogen-Doped Diamond-Like Carbon Thin Films, Krishna Chaitanya Kadiyala

LSU Master's Theses

Diamond-like carbon (DLC) films have been extensively studied for more than two decades due to their highly attractive properties. These films exhibit unique mechanical, electrical and tribological behavior and thus, possess great potential for applications in tribology. However, the high level of internal stress developed and low thermal stability are the main drawbacks. Synthesis of nitrogen-doped DLC (N-DLC) offers the possibility of overcoming these drawbacks. In the present study, DLC and N-DLC films (with low N content) were deposited on Si substrates using a hybrid plasma-assisted CVD/PVD process. Film characterization in terms of microstructure, composition and chemical state of components …

Effect Of Keyswitch Design Of Desktop And Notebook Keyboards Related To Key Stiffness And Typing Force, Marcia J. Bufton, Richard W. Marklin, Mark L. Nagurka, Guy G. Simoneau

Mechanical Engineering Faculty Research and Publications

This study aimed to compare and analyse rubber-dome desktop, spring column desktop and notebook keyboards in terms of key stiffness and fingertip typing force. The spring-column keyboard resulted in the highest mean peak contact force (0.86N), followed by the rubber dome desktop (0.68N) and the notebook (0.59N). All these differences were statistically significant. Likewise, the spring-column keyboard registered the highest fingertip typing force and the notebook keyboard the lowest. A comparison of forces showed the notebook (rubber dome) keyboard had the highest fingertip-to-peak contact force ratio (overstrike force), and the spring-column generated the least excess force (as a ratio of …

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 …

Integrated Solar Energy And Absorption Cooling Model For Hvac (Heating, Ventilating, And Air Conditioning) Applications In Buildings, Sharizal Shaik Ahmedullah

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

The demands in production and associate costs at power generation through non renewable resources are increasing at an alarming rate. Solar energy is one of the renewable resource that has the potential to minimize this increase. Utilization of solar energy have been concentrated mainly on heating application. The use of solar energy in cooling systems in building would benefit greatly achieving the goal of non-renewable energy minimization.

The approaches of solar energy heating system research done by initiation such as University of Wisconsin at Madison and building heat flow model research conducted by Oklahoma State University can be used to …

The Girl Scout Climbing Wall Multidisciplinary Service-Learning Project, Margaret Pinnell, Corinne M. Daprano, Gabrielle Williamson

Mechanical and Aerospace Engineering Faculty Publications

The Girl Scout Wall (GS Wall) project was implemented in two classes at the University of Dayton (UD): a Mechanical and Aerospace Engineering (MAE) course, and a Health and Sports Science (HSS) course, and Sport Facility Management. The MAE course, Introduction to Materials, is a three-credit, third-year required course where students learn about the basic structure and properties of materials as well as the principles of material selection. The Sport Facility Management course is a three-semester hour, required HSS course where students are introduced to the processes of planning, constructing, equipping, maintaining, and managing sport facilities.

Comparison Of Combustion Sources And Measurement Techniques For Particulates Emitted From Engines And A Power Plant, Matthew F. Chandler

Masters Theses

"Sub-micron particulates emitted from various combustion sources have serious negative impacts on human health and the environment. It is essential to accurately characterize the physical properties of these particulates including size, shape, structure, and chemical composition in order to monitor, regulate, and model the various transport, toxic, optical, chemical, and deposition properties which dictate their harmful effects. This study consists of two related investigations involving the application of diagnostics methods to characterization and comparison of combustion generated particulate emissions from various sources. The first investigation includes the measurement of particulates emitted from a compression-ignition (diesel) engine using two independent measurement …

Emission Cross Sections For Neutral Xenon Impacted By Xe+ And Xe2+, Jason D. Sommerville

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

Ion impact emission cross sections for eleven transitions from the 5p⁵6p configuration to the 5p⁵6s configuration of neutral xenon occurring in the spectral region between 700 nm and 1000 nm have been measured experimentally. Collisions between both singly- and doublyionized xenon and neutral xenon have been studied. These cross sections are of primary use in the development of a spectrographic diagnostic for Hall effect thruster plasma. A detailed discussion of the experimental methods and the subsequent data reduction is included. The results are presented and the importance of these data for spectrographic emission models of Hall …

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 …

Test 1877: Challenger Mt 655b Diesel, Nebraska Tractor Test Lab

Nebraska Tractor Tests

No abstract provided.

System Identification Of A Pasteurisation Process: A Comparison Of Direct And Indirect Methods, Niel Canty

Theses

The primary focus of this research is to identify a linear model for a direct steam injection (DSI) pasteurisation process which is a component of a large-scale pilot evaporation process widely used in the dairy industry. The pasteurisation process has been identified as a key component of the evaporation process. The author believes that no previously published work has focused on identifying models for a DSI pasteurisation process which makes this work an original contribution to the area. The pasteurisation process can be modelled as a single-input, single-output (SISO) process with a measurable disturbance. Thus two transfer functions were required …

Rapid Prototyping Of Microfluidic Packages, Michael Pepper

Electronic Theses and Dissertations

In the area of MEMS there exists a tremendous need for communication between the micro-device and the macro world. A standard protocol or at least multiple standards would be of great use. Electrical connections have been standardized for many uses and configurations by the integrated circuit industry. Standardization in the IC industry has created a marketplace for digital devices unprecedented. In addition to the number of "off the shelf" products available, there exists the possibility for consumers to mix and match many devices from many different manufacturers. This research proposes some similar solutions as those for integrated circuits for fluid …

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.

Reducing Energy Costs By Optimizing Controller Tuning, Aidan O'Dwyer

Conference papers

The proportional integral derivative (PID) controller is the most dominant form of automatic controller in industrial use today. With this technique, it is necessary to adjust the controller parameters according to the nature of the process. This tailoring of controller to process is known as controller tuning. Controller tuning is easily and effectively performed using tuning rules (i.e. formulae for controller tuning, based on process information). Such tuning rules allow the easy set up of controllers to achieve optimum performance at commissioning. Importantly, they allow ease of re-commissioning if the characteristics of the process change. The paper outlines the results …

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.

Modeling And Fabrication Of A Microthermocouple Array, Adam Cygan

LSU Master's Theses

Cryobiology is the study of how living cells and tissues respond to freezing and exposure to subzero temperatures. Studies in this field are aimed toward improving methods of cryosurgery as well as the storage of cells and tissues. For example, one area of research is to link the biophysical cellular dehydration and intracellular ice formation in cells during tissue freezing to cell viability and mechanical properties after thawing. There is currently a method for measuring dehydration in cells as part of a tissue, but not an adequate method for measuring intracellular ice formation in tissues. A prototype device that would …

Heat/Mass Transfer In Rotating, Smooth, High Aspect-Ratio (4:1) Coolant Channels With Curved Walls, Eashwar Sethuraman

LSU Master's Theses

The thesis presents an experimental study of heat/mass transfer coefficient in 4:1 aspect ratio smooth channels with non-uniform cross-sections. Curved leading and trailing edges are studied, for two curvatures of 9.06 m-1 (0.23 in-1) and 15.11 m-1 (0.384 in-1) and for two different curvature configurations. One configuration has curved walls with curvature corresponding to the blade profile (positive curvature on both leading and trailing walls), and the other configuration has leading and trailing walls that curve inwards into the coolant passage (negative curvature on the leading surface and positive curvature on the trailing surface). The experiments are conducted in a …

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 …

A Constitutive Model Of The Human Vocal Fold Cover For Fundamental Frequency Regulation, Kai Zhang, Thomas Siegmund, Roger W. Chan

School of Mechanical Engineering Faculty Publications

No abstract provided.

Investigation Into The Behavior Of Bolted Joints, Steven M. Page

Browse all Theses and Dissertations

Models to capture the physics of jointed structures have been proposed for over 40 years. These models approximate the behavior of the joint under carefully developed operating conditions. When these conditions change, the model has to be changed. Recent developments in numeric codes like finite elements have created interest in incorporating joint models into the design process but joint models need to represent the joined structure over a broader operating range. This work investigates the dynamic response of a structure with a joint. Isolation of a few dominant effects may give way to a model able to capture a broader …

Computational Study Of Ring-Cusp Magnet Configurations That Provide Maximum Electron Confinement, Taiwo A. Ogunjobi

Browse all Theses and Dissertations

Enhancing the confinement of primary electrons within the plasma in a discharge chamber of an ion thruster improves plasma ionization and consequently the thruster's performance. This work computationally calculates the location, position, and orientation of the permanent magnets that provide a ring-cusp magnetic field that maximizes electron confinement in an axi-symmetric cylindrical aluminum-wall discharge chamber. Small samarium cobalt magnets are circumferentially arranged in a ring around the front, side, or back wall of the chamber. The generated ring-cusp magnetic field for any specified magnet configuration is calculated using MAXWELL2D, a two dimensional electromagnetic field simulation computer code. For various magnet …

Multi-Attribute Optimization Based On Conjoint Analysis, Hemanth K. Amarchinta

Browse all Theses and Dissertations

Over the last thirty years, there were tremendous advances in multidisciplinary design optimization in reducing computational cost, developing algorithms for efficient sensitivity analysis in reaching an optimum. Most of these efforts assumed a single objective (attribute) function and a multitude of constraints. Very little work has been done in including the designer's preferences as part of the optimization scheme and in addressing the ability to handle multiple attributes simultaneously. This need to develop a systematic method for including designer's preferences is the main focus of this research work. The concept of modeling preferences among multi-attribute alternatives is prevalent in consumer …

Using In-Situ Error Tracking For Mode Selection In Proper Orthogonal Decomposition Reduced Order Modelling, Michael Richard Maddux

Browse all Theses and Dissertations

Proper Orthogonal Decomposition (POD) provides a method of analyzing data and/or creating a Reduced Order Model (ROM). In this thesis, POD is used to create a ROM comprised of basis functions onto which the governing equations of a Computational Fluid Dynamics (CFD) problem are projected via Galerkin's method. The model is of reduced order since the basis functions span a space smaller than the space from which they were created. A full order simulation called the training period is conducted first to obtain data to be used for creating the ROM using POD. The dominant characteristics are extracted from the …

E(Fg)2: A New Fixed-Grid Shape Optimization Method, Florin Bobaru Ph.D., Srinivas Rachakonda

Department of Engineering Mechanics: Faculty Publications

We propose a shape optimization method over a fixed grid. Nodes at the intersection with the fixed grid lines track the domain’s boundary. These “floating” boundary nodes are the only ones that can move/appear/disappear in the optimization process. The element-free Galerkin (EFG) method, used for the analysis problem, provides a simple way to create these nodes. The fixed grid (FG) defines integration cells for EFG method. We project the physical domain onto the FG and numerical integration is performed over partially cut cells. The integration procedure converges quadratically. The performance of the method is shown with examples from shape optimization …

Optimization Of Multilayer Wear-Resistant Thin Films Using Finite Element Analysis On Stiff And Compliant Substrates, R. K. Lakkaraju, Florin Bobaru, S. L. Rohde

Department of Engineering Mechanics: Faculty Publications

Extensive research has been carried out by researchers on the growth and characterization of multilayer protective coatings, but the design of these coatings still remains largely empirical. In this regard, recent progress has been made in developing a design approach for optimizing a multilayer coating structure before deposition, which would help save time and material. In pursuit of an optimal design, finite element analysis using a plane strain Hertzian contact model was developed to investigate the stress/ strain behavior within the layers of the system. The present study looks to find the optimal thicknesses of individual layers in a multilayer …

A Model For Predicting The Evolution Of Multiple Cracks On Multiple Length Scales In Viscoelastic Composites, David H. Allen, C. R. Searcy

Department of Engineering Mechanics: Faculty Publications

A model is presented herein for predicting the evolution of numerous cracks on multiple length scales, the objective of such a model being to develop the capability to predict failure of structural components to perform their intended tasks. Such a capability would then be useful as a predictive tool for designing structural components so as not to fail, but rather to succeed in performing their intended tasks. The model developed herein is somewhat involved, being based in continuum mechanics and thermodynamics, but is nevertheless expected to be cost effective (wherever sufficient accuracy permits) when compared to more costly experimental means …

Efficient Inverted Polymer Solar Cells, G. Li, C.-W. Chu, V. Shrotriya, Jinsong Huang, Y. Yang

Department of Mechanical and Materials Engineering: Faculty Publications

We investigate the effect of interfacial buffer layers—vanadium oxide (V₂O₅) and cesium carbonate (Cs₂CO₃)—on the performance of polymer solar cells based on regioregular poly-(3-hexylthiophene) and [6,6]-phenyl C₆₀ butyric acid methyl ester blend. The polarity of solar cells can be controlled by the relative positions of these two interfacial layers. Efficient inverted polymer solar cells were fabricated with the structure of indium tin oxide (ITO)/Cs₂CO₃/polymer blend/vanadium oxide (V₂O₅)/aluminum (Al). Short-circuit current of 8.42 mA/cm2, open-circuit voltage of 0.56 V, and power conversion efficiency of …