Engineering Commons^™

Renewable Energy Limits, Florida Solar Energy Center, Ross Mccluney

FSEC Energy Research Center®

"The more we get out of the world the less we leave, and in the long run we shall have to pay our debts at a time that may be very inconvenient for our own survival." - Norbert Wiener

Introduction: The world's energy and environmental crises are inextricably linked. The processes of extracting, processing, and burning fossil fuels generates copious pollution of air, water, and land. Fossil-fuel-derived energy lies at the heart of other environmental problems. Fossil energy powers the bulldozers clearing rainforests. It runs the tractors and other farm equipment of industrial agriculture, compacting and mineralizing soils thus increasing …

Interfacial Edge Crack Between Two Bonded Dissimilar Orthotropic Strips Under Antiplane Point Loading, Xiangfa Wu, Yuris A. Dzenis, Wen-Sheng Zou

Department of Engineering Mechanics: Faculty Publications

A closed-form solution is obtained for the interfacial edge crack between two bonded dissimilar orthotropic strips loaded by antiplane point loading in form of screw dislocation or line force. Conformal mapping and existing dislocation solutions are utilized for constructing the fundamental solution of the problem. The stress intensity factor (SIF) and the energy release rate(ERR) are obtained explicitly.

Modeling, Fabrication, And Optimization Of Niobium Cavities: Phase Ii Final Report, Robert A. Schill Jr., Mohamed Trabia, William Culbreth

Transmutation Sciences Materials (TRP)

Niobium cavities are important parts of the integrated NC/SC high-power linacs. Over the years, researchers in several countries have tested various cavity shapes. They concluded that elliptically shaped cells are the most appropriate shape for superconducting cavities. The need for very clean surfaces lead to the use of a buffered chemical polishing produce for surface cleaning to get good performance of the cavities. The second phase has resulted in an experimental setup of a fluid flow experiment with experimentation to be completed in the third year. Some of these results were presented at American Nuclear Society, Student Conference April 2-5, …

Robust Pi Controller Design Satisfying Gain And Phase Margin Constraints, Mark L. Nagurka, O. Yaniv

Mechanical Engineering Faculty Research and Publications

This paper presents a control design algorithm for determining PI-type controllers satisfying specifications on gain margin, phase margin, and an upper bound on the (complementary) sensitivity for a finite set of plants. Important properties of the algorithm are: (i) it can be applied to plants of any order including plants with delay, unstable plants, and plants given by measured data, (ii) it is efficient and fast, and as such can be used in near real-time to determine controller parameters (for on-line modification of the plant model including its uncertainty and/or the specifications), (iii) it can be used to identify the …

Design Of Predictive Controllers By Dynamic Programming And Neural Networks, Chen-Wen Yen, Mark L. Nagurka

Mechanical Engineering Faculty Research and Publications

This paper proposes a method for the design of predictive controllers for nonlinear systems. The method consists of two phases, a solution phase and a learning phase. In the solution phase, dynamic programming is applied to obtain a closed-loop control law. In the learning phase, neural networks are used to simulate the control law. This phase overcomes the "curse of dimensionality" problem that has often hindered the implementation of control laws generated by dynamic programming. Experimental results demonstrate the effectiveness of the method

Optically Transparent, Scratch-Resistant, Diamond-Like Carbon Coatings, Xiao-Ming He, Deok-Hyung Lee, Michael A. Nastasi, Kevin C. Walter, Michel G. Tuszewski

Department of Mechanical and Materials Engineering: Faculty Publications

A plasma-based method for the deposition of diamond-like carbon (DLC) coatings is described. The process uses a radio-frequency inductively coupled discharge to generate a plasma at relatively low gas pressures. The deposition process is environmentally friendly and scaleble to large areas, and components that have geometrically complicated surfaces can be processed. The method has been used to deposit abherent 100-400 nm thick DLC coatings on metals, glass, and polymers. These coatings are between three and four times harder than steel and are therefore scratch resistant, and transparent to visible light. Boron and silicon doping of the DLC coatings have produced …

Method For Producing Fluorinated Damond-Like Carbon Films, Marko J. Hakovirta, Michael Nastasi, Deok-Hyung Lee, Xiao-Ming He

Department of Mechanical and Materials Engineering: Faculty Publications

Fluorinated, diamond-like carbon (F-DLC) films are produced by a pulsed, glow-discharge plasma immersion ion processing procedure. The pulsed, glow-discharge plasma was generated at a pressure of 1 Pa from an acetylene (CH) and hexafluoroethane (CF) gas mixture, and the fluorinated, diamond-like carbon films were deposited on silicon <100>Substrates. The film hardness and wear resistance were found to be strongly dependent on the fluorine content incorporated into the coatings. The hardness of the F-DLC films was found to decrease considerably when the fluorine content in the coatings reached about 20%. The contact angle of water on the F-DLC coatings was found …

Paper On Measurement Of The Nanomechanical Properties Of Thin Films Using Afam Receives Recognition, Donna Hurley, Joseph A. Turner, Paul Rice, Joshua Wiehn

Department of Engineering Mechanics: Faculty Publications

NIST researchers are developing atomic force acoustic microscopy (AFAM) methods to quantitatively determine the elastic properties of thin films. The AFAM technique measures the frequencies of an atomic force microscope (AFM) cantilever’s first two flexural resonances while in contact with a material. The indentation modulus, M, of an unknown or test material can then be obtained by comparing the resonant spectra of the test material to those of a reference material. To examine metrology issues for this emerging technique, AFAM results have been compared with those obtained by other methods, such as instrumented indentation. The results show that better agreement …

Qualitative And Statistical Analysis Of The Florida Photovoltaic Rebate Program, Florida Solar Energy Center, Jennifer Szaro

FSEC Energy Research Center®

The Florida Photovoltaic (PV) Rebate Program, which began in March of 1999, has led to the installation of 52 utility interactive PV systems in seven electric utility service territories. The Program offered $4 per installed DC Watt to Florida electric consumers who installed grid-connected photovoltaic equipment in accordance with a series of quality control requirements developed and administered by the Florida Solar Energy Center. All rebated installations are currently being monitored in an effort to collect statistically significant reliability, performance and cost data on grid-connected PV systems. Funding for this program was provided through a one-time grant from the Florida …

System Interactions In Forced-Air Heating And Cooling Systems, Part I: Equipment Efficiency Factors, Florida Solar Energy Center, Lixing Gu

FSEC Energy Research Center®

ASHRAE Standard 152P (ASHRAE 2001) combines field measurements with calculations to quantify the efficiency of residential thermal distribution systems. To do this, it considers not only direct energy losses from the duct system, via conduction and air leakage, but also indirect effects that the duct system may have on the efficiency of the equipment or on the heating/cooling load. Although Standard 152P includes non-ducted thermal distribution systems in its scope, the subject matter of this paper is, however, restricted to ducted systems.

Investigation Of The Iced Flowfield Characteristics Related To The Stall Margin Instrumentation Used In Icing Conditions, Erik Pederson

Dissertations

The purpose of this dissertation is to investigate the relationship between the flowfield surrounding an iced airfoil and the stall margin instrumentation developed for use in icing conditions. The stall margin system indicates to the pilot the change in available lift due to ice accretions on the leading edge of an airfoil. This system displays the change in the form of a normalized lift coefficient. Four pressure ports are chosen to specifically maintain a constant calibration curve, for pressure versus normalized lift coefficient, regardless of ice shape. This allows these pressures to be used to determine the change in maximum …

Cooperative Path Planning For Timing Critical Missions, Timothy W. Mclain, Randal W. Beard

Faculty Publications

This paper presents a cooperative path planning approach for teams of vehicles operating under timing constraints. A cooperative control approach based on coordination variables and coordination functions is introduced and applied to cooperative timing problems. Three types of timing constraints are considered: simultaneous arrival, tight sequencing, and loose sequencing. Simulation results demonstrating the approach are presented.

Theoretical And Experimental Studies Of The Field-Induced Phenomena In Flowing Suspensions, Nikolai Markarian

Dissertations

The present work describes results of experimental and theoretical studies of the behavior of dilute suspensions subject to high gradient AC electric fields. When a spatially non-uniform electric field is applied to a suspension, in which the particles and the suspending fluid have different dielectric permittivities andlor conductivities, the particles migrate towards the regions of high or low electric field strengths depending on the sign of their polarization. This phenomenon, referred to as dielectrophoresis, has found numerous applications for the control and manipulation of the particle motions.

Presented in Chapter 3 are the results of studying the field -induced motion …

Experimental Study Of Ignition Of Mechanical Alloy And Pure Metal Powders, Ruslan Mudryy

Theses

Mechanical alloys of Al Mg, AI Zr, Al Ti, Al Li, Al C, Al Mg H, B Mg, B Al, and B Ti were produced and tested for possible applications as high energy density additives to fuels, propellants, explosives, and incendiaries. These new materials are metastable, supersaturated, nanocrystalline solid solutions that include a base metal as a solvent and another component (metal or gas, e.g. hydrogen) as a solute. Phase changes occurring in such materials during ignition and combustion are expected to significantly affect both ignition and bum rates. This experimental program focused on the characterization of ignition kinetics of …

Addition Of A Chain-Cell Search Method And A Van Der Waals Force Model To A Particle Dynamics Code, Michael J. Sweetman

Theses

This project studies the implementation of a computational time saving technique and adds an additional force model into a discrete element method simulation code. Both aspects of the project are focused on increasing the versatility of an existing particle dynamics code by increasing the execution speed and available force models for simulation.

The first portion of the project consisted of adding a function to the collision detection mechanism to hash the particles into a spatial grid. This hashing function allows a search for near neighbor particles to be restricted to the space immediately adjacent to the particle of interest, thereby …

Direct Simulation Of Electrorheological Suspensions Subjected To Pressure Driven Flow And Spatially Non-Uniform Electric Field, Arun Thankamony John Kadaksham

Theses

A numerical method based on the distributed Lagrange Multiplier method is developed for direct simulation of electrorheological (ER) suspensions subjected to pressure driven flows and spatially non-uniform electric fields. The flow inside particle boundaries is constrained to be rigid body motion by the distributed Lagrange multiplier method and the point-dipole approximation is used to model the electrostatic forces acting on the polarized particles. Simulations show that the particles move to the regions of high electric field when the value of β, the Clausius-Mossotti factor is positive and they move to the regions of low electric field when the value of …

Analysis Of Random Packing Of Uniform Spheres Using The Monte Carlo Simulation Method, Sai S. Tulluri

Theses

The study of random packing of spheres has had a long history. It particularly interests many researchers because randomly packed hard spheres exhibit some features of the properties of simple liquid, e.g. the packing density and the radial distribution. Many researchers have studied random packing both experimentally and also by using computer simulation.

Monte Carlo simulation method was used to generate random loose packing of hard spheres. Packing characteristics like packing density, radial distribution function, co-ordination, angular distribution and fabric tensor have been computed for this packing system.

The packing density for a system of 8000 particles with a diameter …

Discrete Element Simulation And Nonlinear Dynamic Analysis Of Particles In A Simple Lattice Structure, Liam E. Buckley

Theses

The study of particles interacting in lattice structures allows for insight into the complex interactions of granular flow, and the adaptation of such structures to mechanical apparatuses to handle the separation of bulk particulate matter. Applying methods of computer analysis to the interactions taking place within the particle-lattice system provides a particle level methodology to the study of the phenomenon taking place, as well as a stepping stone for future design of related devices.

A two prong approach is presented to the study of such particle-lattice systems. The first approach is composed of adapting an existing discrete element computer code …

Ultrasonic Flowmeters In Determination Of Correlation Functions Of Velocity And Ultrasound Wave Fluctuations In Grid-Generated Turbulence, Tatiana A. Andreeva, William W. Durgin

Office of the Provost Scholarship

The paper is devoted to the experimental investigation of the statistical characteristics of the grid-generated turbulence produced in a wind tunnel. Ultrasonic time-of-flight method using dual transducers is utilized to develop a methodology for determination of the correlation functions of turbulent velocity and sound speed fluctuations. The ultrasonic flowmeter equation is considered in the form that includes effects of turbulent velocity and sound speed fluctuations. The influence of temperature inhomogeneities on ultrasonic wave propagation is investigated using a set of experiments with a heated grid. Utilization of high-speed digital data acquisition cards and LabView software for the experiments allows collecting …

Comparison Study Of Cooling Fins And Chills Effectiveness In Aluminum Sand Mold Casting, Vladimir E. Kouznetsov

Graduate Research Papers

Besides proper design of gating and risering systems, there are several methods used to control and modify solidification behavior of cast alloys. Within these methods, the most widely used are local cooling aids employing cooling fins (thin segments attached to problematic areas of casting) or external chills (metal inserts placed into mold walls to accelerate heat withdrawing from potential hot spot). The later helps to promote directional solidification when traditional methods are not possible to use due to limitations related to the casting design. Despite relatively wide application in aluminum foundries, there are no specific recommendations on cooling aids parameters …

Designing Active Smart Features To Provide Nesting Forces In Exactly Constrained Assemblies, Eric Pearce

Theses and Dissertations

Ever since the design and manufacture of products moved from the craftsman era where individual craftsman designed and manufactured the entire product, to the mass production era, where skilled laborers were crafting interchangeable parts or in some cases single features on interchangeable parts, variation in assemblies has been a major concern to designers, manufacturers, and in a more subtle way, customers. Variation, in the end, affects quality, performance and the cost of products. One particular type of design that is particularly robust to variation is an exactly constrained design.

Several researchers have recently explored the topic of exact constraint design. …

Microstructure Sensitive Design Of An Orthotropic Plate Subjected To Tensile Load, Brent L. Adams, Mark Lyons, Joshua R. Houskamp, Surya R. Kalidindi

Faculty Publications

Financial support for this work was provided by the Army Research Office, Proposal No. 42566-MS, Dr. David Stepp, Program Director and Army Research Lab, Dr. Scott Schoenfeld, Point of Contact. Microstructure Sensitive Design (MSD) is a newly developed mathematical framework that facilitates rigorous solutions to inverse problems in microstructure design of materials. In this paper, this methodology is applied to an orthotropic thin plate containing a circular hole subjected to an in-plane uniaxial tensile load. The primary design objective is to maximize the load carrying capacity of the plate while avoiding plastic deformation in the plate. Making use of the …

Universal Mounting Bracket For Laser Targeting And Feedback System, Richard J. Kelin Ii

Patents (University of Northern Iowa)

A support bracket for mounting a device such as a laser targeting and feedback system to a spray gun. The bracket includes a bolt having a threaded end, a first collar disposed on the bolt opposite the threaded end and a second collar threadably engaged with the threaded end of the bolt. A compressible member is disposed on the bolt between the collars. Opposite the compressible member, a support arm used to support the device is attached to the second collar. The bracket is engageable with a portion of the spray gun body and is engaged therewith by deflecting the …

Using Satellite Imagery To Evaluate The Impact Of Urban Forest On Summertime Residential Electricity Consumption In Terre Haute, Indiana, Usa, James R. Boulton

All-Inclusive List of Electronic Theses and Dissertations

Urban areas are horne to a large portion of the population of the United States and also a significant portion ofthe nation's forest resource. This urban forest contributes to the richness of the urban lifestyle in many ways, including aesthetic improvements, cleaning and protecting air, land, and water resources, and reducing the urban heat island effect. This thesis studies the degree to which energy reduction attributable to the urban forest can be determined using remotely sensed data. Results showed a slight inverse relationship between urban forest density and energy usage, meaning that as the density of trees increases there is …

Human Reliability Analysis In The Performance Of Advanced Cardiac Life Support Tasks, Lucia Veronica Rosas

Theses and Dissertations - UTB/UTPA

Error reduction in the performance of medical emergency situations is an area of great concern in today's society. This is specially the case when the situation involves a cardiac arrhythmia. These situations are generally categorized as Advanced Cardiac Life Support (ACLS) events. The American Heart Association provides the proper procedures that practitioners of ACLS should follow to provide care to patients presenting heart arrhythmia problems. These situations occur inside and outside the hospital, outside the hospital being the most critical ones considering the limitation of equipment and availability of qualified care. Errors made by the practitioners of ACLS in this …

Thermoacoustic Refrigerator, Nathan A. Hammond

Undergraduate Honors Capstone Projects

Thermoacoustic refrigerators have typically been designed to cool an isolated working fluid, necessitating a heat exchanging device to draw heat from the outside target fluid into the cooled working fluid. For example, a thermoacoustic refrigerator designed to chill air might utilize argon as an isolated working fluid, necessitating a heat exchanger to draw heat from the air to the argon. A second heat exchanger would be required to draw heat from the argon to a cold sink.

A design team at Utah State University has created a thermoacoustic refrigerator which uses air at atmospheric pressure as its working fluid. By …

Analysis Of Lifting Performance Capacity Through An Integrated Learning Curve Model, Jose Roel Flores

Theses and Dissertations - UTB/UTPA

Physical fitness specific to job demands is necessary for jobs that require moderate or heavy effort. Fitness training is needed not just when a new job is learned but also when an individual has been away from the job for a few weeks and returns to perform the task. The basic problem is to have a good understanding of the dynamics of performance capacities to establish training and retraining regimes to prevent overexertion. To obtain this, a better understanding of the behavior of performance capacity over time is necessary. A performance capacity training regimen was designed for tasks that required …

Expert System Development For Hard Disk Drive Failure Analysis, Fernando Rodriguez Rosas

Theses and Dissertations - UTB/UTPA

The Computer's Hard Disk Drive is a complex high technology device, diagnosis of a failure is difficult even using sophisticated test equipments. These Drives are expensive and returning a new one when it fails within the warranty period is not an option. The failed drive must be tested and repaired. In the repair process the analysis and diagnosis of the failures is a key point in the process where decisions regarding the repair process that the failed Drive will follow. Therefore, there is a requirement to perform an effective analysis and provide an accurate diagnosis. The standard system utilized for …

Analysis Of Performance Capacity Of Hand Grip Through An Integrated Learning Curve Model, Miguel Torres

Theses and Dissertations - UTB/UTPA

There are few activities or work task in the manufacturing industry that does not involve grip strength. That is why it is in the best interest of the manufacturing industry to have an understanding of the optimum grip strength gain capacity over time that would lead to better performance, accuracy and most of all prevent hand grip related injuries. For that reason, this thesis was concentrated in discovering a possible basic working model for estimating grip strength over time for a specific grip strength activity. The first step was to observe the trend characteristics of the strength gain data over …

Development Of New Heat Sink Technology For High-Density Microprocessors, Pedro Lopez Jr.

Theses and Dissertations - UTB/UTPA

This study investigates the performance of existing heat sinks and compares it with two heat-exchanger prototypes: aluminum-foam heat sink and PCM (phase-change material)-filled heat sink. Kapton flexible heaters are used to replicate the heat produced by a computer's CPU (central processing unit). A number of thermocouples are connected between the heater and the heat sink being used to measure the component's temperature. The thermocouples are also connected to a data acquisition card to collect the data using a LabVIEW program. The values obtained are compared to data published in literature to validate the experiments and the setup. This setup is …