Engineering Commons^™

Growth And Properties Of Chemically Deposited Cds Thin Films, Edward A. Gluszak

Theses : Honours

Polycrystalline thin films of undoped CdS and In doped CdS (i.e. CdS:In) have been deposited by chemical bath on glass slides and high purity silicon wafers. The effect of different processing conditions (e.g. substrate temperature, doping and air annealing) on film growth, optical transmittance and electrical properties were correlated with the film microstrucutre. The mechanism of chemical bath deposition of CdS thin films from the ammonia-thiourea system is studied. The influence of reaction parameters (i.e. concentration of reactants and pH) on film growth were determined and modeled. Thin film growth is thermally activated with an energy ≈ 5 x 10 …

Effects Of Refrigeration And Cryogenic Treatments On Austempered Ductile Iron, Gerard R. Thiel

Dissertations and Theses @ UNI

Low temperature treatment, as a method of improving mechanical properties of metals, has been studied and used for well over 60 years. Until recently these treatments have been limited to hardness and wear improvements of high alloy irons and steels. The purpose of this research is to determine the effects of refrigeration and cryogenic treatments on the mechanical properties, including hardness and tensile strength of austempered ductile iron.

This research included the production of a high strength ductile iron of low alloy content capable of being used in either the as cast, conventionally heat treated or austempered condition. Refrigeration and …

Terminal Sliding Mode Control For Rigid Robotic Manipulators With Uncertain Dynamics, Nicola Ritter

Theses: Doctorates and Masters

This thesis presents two new adaptive control laws that use the terminal sliding mode technique for the tracking problem of rigid robotic manipulators with non-linearities, dynamic couplings and uncertain parameters. The first law provides a robust scheme which uses several properties of rigid robotic mauipulators and adaptively adjusts seven uncertain parameter bounds. The law ensures finite time error convergence to the system origin and is simple to implement The second law treats the manipulator as a partially known system. The known dynamics are used to build a nominal control law and the effects of unknown system dynamics arc compensated for …

Asynchronous Multiuser Decorrelating Detector For Awgn Channel, Ashwini A. Borkar

Theses

Decorrelating detector is one of the sub-optimum detectors for CDMA applications that generally has better performance than the conventional detector and is near-far resistant. Synchronous decorrelating detector employing DPSK modulation is considered and its simulation results are presented.

Attention is focussed on one-shot decorrelating detector for a two user case for asynchronous transmission, where each symbol interval is considered seperately. Initially the performance of the detector with exact estimation of the relative delay is analyzed and then the effect of inaccurate estimation on the probability of error is discussed.

A Comparison Of Measurement Reliability Between A Sonic Digitizer And A Tape Measure On A Complex Three-Dimensional Object, Diane Darlene (Wheeler) Schou

Dissertations and Theses @ UNI

Digitizers and scanners have begun to replace traditional devices for measuring three dimensional objects. However, there is a shortage of relevant research to compare digitizer tools with other measuring devices. The objective of this study was to compare the measurement reliability of a sonic digitizer to a traditional measuring tool, the tape measure, for measuring a complex, three-dimensional object. It was hypothesized that:

1. H₁ Data from measurements with the digitizer vary less than data from measurements with a tape measure at the 0.05 level of significance.
2. H₂ The data from eight complex surface measurements taken with a digitizer …

An Investigation On The Processing And Characterization Of (Thallium(0.5-X) Lead(0.5-X) Europium(2x)) Strontium(2-Y) Barium(Y) Calcium(2) Copper(3) Oxygen(Z) High-Temperature Superconductor To Determine The Optimum Barium Concentration And Study The Effects Of Doping Europium In Thallium And Lead Sites, Zifan Ju

Dissertations and Theses @ UNI

This research focused on (Tl_0.5-xPb_0.5-xEu_2x)Sr_2-y Ba_yCa₂Cu₃O_z compound to determine the optimum y (Barium concentration), and then studied the effects of doping Eu in Tl, Pb sites. Studies on optimum y give rise to a high quality superconducting material as a target material for sputter deposition of thin films for electronics applications. Studies on doping Europium (Eu) is a new investigation and might lead to better understanding of the structural properties of the superconductor.

The experiment was conducted in three steps as follows:

1. Optimizing the sample fabrication …

Application Of Laminated Ferrocement In Repairing R.C. Slabs And Beams, Yasser Sayed Korany

Archived Theses and Dissertations

No abstract provided.

An Approach To Just-In-Time Implementation In Discrete Parts Manufacturing, Phillip Gregory Shirey

Masters Theses

"Just-In-Time manufacturing is a philosophy that encourages waste reduction and the elimination of non-value-added activities. The processes affected include office and shop personnel. When successfully implemented, JIT accounts for improved production lead time cycles, reduced inventories, improved employee morale, reduced cost of goods, and continuous improvements of the total business process.

This thesis identifies real world problems many medium size U.S. manufacturing companies now face, and an approach to JIT implementation in discrete parts manufacturing. The approach includes developing strategies to motivate the employees and to implement the tools and techniques of JIT, Total Quality Management, ISO 9001, and MRP …

The Modeling Of Structural-Acoustic Interaction Using Coupled Fe/Be Method And Control Of Interior Acoustic Pressure Using Piezoelectric Actuators, Yucheng Shi

Mechanical & Aerospace Engineering Theses & Dissertations

A coupled finite element (FE) and boundary element (BE) approach is presented to model full coupled structural/acoustic/piezoelectric systems. The dual reciprocity boundary element method is used so that the natural frequencies and mode shapes of the coupled system can be obtained, and to extend this approach to time dependent problems. The boundary element method is applied to interior acoustic domains, and the results are very accurate when compared with limited exact solutions. Structural--acoustic problems are then analyzed with the coupled finite element/boundary element method, where the finite element method models the structural domain and the boundary element method models the …

Application Of Reanalysis Techniques For Pattern Design Of Spot Welds, Young San Kim

Mechanical & Aerospace Engineering Theses & Dissertations

Extensive benchmarking on competitive cars has shown that the durability of vehicles, assembly-induced variations, and assembly cost are directly related to the quality and number of spot welds. On most luxury cars, approximately 4,500 to 5,000 spot welds are found. On less expensive cars, the range is from 3,500 to 4,500. These cars usually inherit more noise, rattles, squeaks, and other quality-related problems. These problems have motivated the search for a new capability to systematically place welds in the most critical areas, with a minimum number of welds for car bodies, while satisfying all performance requirements (e.g., stiffness, stress distribution, …

Numerical Simulation Of Complex, Three-Dimensional, Turbulent-Free Jets, Robert V. Wilson

Mechanical & Aerospace Engineering Theses & Dissertations

Three-dimensional, incompressible turbulent jets with rectangular and elliptical cross-section are simulated with a finite-difference numerical method. The full Navier-Stokes equations are solved at low Reynoids numbers, whereas at high Reynolds numbers filtered forms of the equations are solved along with a sub-grid scale model to approximate the effects of the unresolved scales. A 2-N storage, third-order Runge-Kutta scheme is used for temporal discretization and a fourth-order compact scheme is used for spatial discretization. Although such methods are widely used in the simulation of compressible flows, the lack of an evolution equation for pressure or density presents particular difficulty in incompressible …

Dynamic Scale Genetic Algorithm: An Enhanced Genetic Search For Discrete Optimization, Bela Dange Joshi

Engineering Management & Systems Engineering Theses & Dissertations

The minimization of operations and support resources of reusable launch vehicles is a complex task, involving discrete optimization and the simulation domain. Genetic algorithms, offering a robust search strategy suitable for integer variables and the simulation domain, can be applied to minimize these resources. This research developed an enhanced genetic algorithm for problems with a linear objective function, the most common class of discrete optimization problems. The dynamic scale genetic algorithm developed here incorporates concepts of implicit enumeration to enhance search. This is achieved by utilizing problem specific information to refine the solution space over successive generations. The utility of …

Optical Fiber Fourier Transform Infrared Evanescent Wave Absorption Spectroscopy Of Aluminum Hydroxide And Natural Corrosion, Juock S. Namkung

Electrical & Computer Engineering Theses & Dissertations

A new technique for continuous, real-time, in-situ detection of natural corrosion of aluminum alloys is presented. The technique is a generalized version of attenuated total reflectance (ATR) spectroscopy, that combines optical fibers and a Michelson interferometer spectrometer to make evanescent wave absorption measurements. Aluminum hydroxide is one of the major corrosion products of aluminum. Absorption spectra of powdered samples of aluminum corrosion, in the spectral region around three micrometers have been studied and compared with the spectra from pure powdered aluminum hydroxide. A chalcogenide optical fiber was used as an attenuated total reflectance (ATR) optical element. The same samples were …

A Simulation Environment For Cdma Wireless Communication Systems In Awgn Channels, Muzaffer Kanaan

Theses

The goal of this work is the development of a, wireless communication system simulator. The simulator has been developed primarily to aid in the studies of Code Division Multiple Access (CDMA) digital cellular systems. We begin by introducing the fundamentals of spread spectrum communications and the motivation for this work. We then take a detailed look at CDMA systems and their structure. We then verify the accuracy of the simulator by using it to simulate some familiar system scenarios. We end this work by presenting conclusions and suggestions for further work.

Flash Adc Using 2Μm Cmos P-Well Technology : Design And Test, Joseph E. Levinson

Theses

This thesis describes the design, implementation and test for a new CMOS analog-to-digital converter IC chip. In designing the analog-to-digital converter in this thesis a radically different comparator design that is only available with CMOS logic. The design utilizes a single CMOS inverter as an ultra-high gain amplifier. This approach reduces the circuit dependence upon matching of the transistors similar to the traditional method. This new design requires less area since the comparator utilizes fewer transistors.

Flash analog-to-digital converters use 2" - 1 comparators to do a single conversion where n is the number of bits used. These comparators are …

A New Device For Performing Simultaneous Sterno-Thoracic Cardiopulmonary Resuscitation (Sst-Cpr), Deepak S. Gupta

Theses and Dissertations

There are two different physiological mechanisms that cause blood to circulate around the human body during cardiopulmonary resuscitation. The "cardiac pump" generates blood flow by squeezing blood out of the heart as the sternum is depressed. The "thoracic pump" generates flow by forcing blood out of the heart and the great vessels as the intrathoracic pressure rises due to chest compression.

To date, all CPR techniques try to circulate blood during cardiac arrest by exploiting elite; the cardiac pump or the thoracic pump mechanism of blood flow. No mechanical CPR device thus far invented has tried to exploit both mechanisms …

Minimization Of Sum-Of-Conditional-Decoders Structures With Applications In Finite Machine Epld Design And Machine Learning, Sanof Mohamedsadakathulla

Dissertations and Theses

In order to achieve superior speed in sequencer designs over competing PLD devices, Cypress brought to market an innovative architecture, CY7C361. This architecture introduced a new kind of universal logic gate, the CONDITION DECODER (CDEC). Because there are only 32 macrocells in the chip, saving only one CDEC gate can be quite important (the well-known "fit/no-fit problem"). A problem that is related to the fitting problem of the Cypress CY7C361 chip is the SOC Minimization. Due to the limited low number of macrocells in CY7C361, a high quality logic minimization to reduce the number of macrocells is very important. The …

Personality As It Relates To Performance Among Primary Flight Students At Embry-Riddle Aeronautical University, Caroline F. Farmer

Master's Theses - Daytona Beach

The purpose of this study was to evaluate the relationship of primary flight students' performance as it relates to personality. Previous research has provided the basis for the relationship between what an individual accomplishes and personality traits. The individual performance of 30 students were evaluated by two different techniques during an observer flight. One was an evaluation form developed by the researcher and the other, the flight instructor's (P.I.C.) evaluation. The performance data gathered by the researcher was collected in order to provide a secondary set of performance data in case there was no discriminability amongst the flight instructor's evaluation. …

Design Modification And Optimization Of The Interior Ballistics For An Existing Naval Gun System., Gregory Allen Dennison

Electronic Theses and Dissertations

This thesis determines the physical, chemical and thermodynamic properties of an advanced solid propellant that can be used in the proposed upgrade of the Navy's 5-inch, Mark 45 gun system to achieve a muzzle energy of 14.928x16^6 ft-lbf (20.24 mega Joules(MJ)) firing a proposed 110 pound Precision Guided Munition (PGM). This energy level corresponds to an 95% increase over the current system that uses Navy Cool, or NACO, solid propellant and a 70 pound projectile. The propellant properties were parameterized using the interior ballistics simulation code known as Interior Ballistics of High Velocity Guns - 2 (IBHVG2), version 505D. The …

A Finite Element Analysis Of The Forward Rod Extrusion Process With An Emphasis On Die Profile Optimization, Mahmoud Mohamed Nagui Shatla

Archived Theses and Dissertations

No abstract provided.

Binary Gas Mixture Analysis With An Interdigitated Gate Electrode Field Effect Transistor (Igefet) Microsensor, John M. Wiseman

Theses and Dissertations

Single component and binary gas mixtures of nitrogen dioxide (NO2) and ammonia (NH3) were analyzed with a microsensor composed of an array of interdigitated Gate Electrode Field Effect Transistor (IGEFET) sensor elements coated with copper-, nickel-, and cobalt-phthalocyanine thin films. Improvements in the IGEFET microsensor design and operation facilitated simultaneous measurement of ihe direct current (DC) and alternating current (AC) electrical response of the metal-substituted phthalocyanine (MPc) films to challenge gas exposure. A finite-difference model of the interdigitated gate electrode (IGE) structure confirmed the fundamental operation of the IGEFET microsensor. Principal component analysis (PCA) and multilinear regression were applied to …

Investigation Of Residual Strength And Fatigue Life Of Unstiffened Aluminum Panels With Multiple Site Damage, Mark C. Cherry

Theses and Dissertations

Multiple Site Damage MSD is the occurrence of small fatigue cracks at several sites within aircraft structures. This is important since it may lower the residual strength and fatigue life of the structure beyond what can be predicted using the damage tolerance technique based on a single crack, currently in use to design aircraft structures. This study investigated the effects of MSD on unstiffined panels. MSD usually occurs at rivet holes, or other stress concentration locations within an aircraft structure. This study simulated rivet holes with MSD, by using holes of constant diameter with small cracks, evenly spaced across the …

A Systems Engineering Approach To Aircraft Kinetic Kill Countermeasures Technology: Development Of An Active Aircraft Defense System For The C/Kc-135 Aircraft, Mark C. Cherry, Bruce R. Dewitt, Christopher G. Dusseault, Joel J. Hagan, Brian S. Peterson

Theses and Dissertations

Modern Surface to Air Missiles (SAMs) present a significant threat to today's military and civilian aircraft. Current countermeasure systems such as flares and chaff rely on decoying the missile threat and do not provide adequate protection against advanced computerized missiles (Schaffer, 1993:1). An aircraft defense system that actively seeks out and defeats an incoming missile by placing a physical barrier in the missile's path offers a promising alternative to current countermeasures technology. This thesis reports the preliminary design of an active aircraft defense system for the protection of the C/KC-135 aircraft from SAMs. The developed system utilizes a kinetic kill …

Thermo-Mechanical Fatigue Behavior Of Cross-Ply Ceramic Matrix Composite Under Tension-Tension Loading, Dana G. Allen

Theses and Dissertations

The purpose of this study was to investigate the combined effect of cyclic temperature and loading on the fatigue life of a ceramic matrix composite with a cross ply lay-up. The material used in this study was a potassium borosilicate glass (BSG) doped magnesium aluminosilicate (MAS) cordierite matrix reinforced with Nicalon (silicon carbide, SiC) fibers in a [0/90]_4s lay-up. Thermomechanical fatigue (TMF) tests were performed with a period of 180 seconds/cycle, or 0.00556 Hz, and a triangular wave-form. The temperature was cycled between 566°C and l093°C, and the stress levels varied between 60 MPa and 145 MPa. All tests …

Application Of Mixed-Norm Optimal Control To A Multi-Objective Active Suspension Problem, John B. Allison

Theses and Dissertations

Mixed norm optimal control synthesis is used to solve a multiobjective suspension problem. The objective is to develop a controller for an active suspension system onboard a tractor semitrailer vehicle. The problem is first approached by using H₂ and H∞ optimization. It is shown that by combining both techniques into one mixed norm optimization method, it is possible to exploit the strengths of each norm to provide superior performance. Two H₂/H∞ designs were completed. One design concentrated on optimal performance at one design condition. The second design concentrated on providing the best performance possible at a medium …

Numerical Simulation Of Supersonic Turbulent Boundary Layer Flow Under The Influence Of Mild Pressure Gradients, Eric T. Fick

Theses and Dissertations

Mach 2.9 boundary layer flow (R_e/m ≈ 1.75x10⁷) under the influence of mild pressure gradients is studied numerically. Baldwin-Lomax and k - ω turbulence models are incorporated into a cell centered finite volume flow solver and the results are compared with hot wire anemometry and Laser Doppler Velocimetry (LDV) measurements obtained for the same geometries in the AFIT Mach 2.9 wind tunnel. Agreement between the present simulations obtained with the k - ω turbulence model and experimental velocity profiles is excellent in all test sections. Nondimensional turbulent shear stress predictions closely match experimental data in the …

Validation Of The Articulated Total Body Model Data Set Describing The Large Advanced Dynamic Anthropomorphic Manikin, Joel J. Hagan

Theses and Dissertations

Recent cut-backs in Department of Defense spending have presented a need to augment full-scale ejection seat testing with computer simulation. To this end, the U.S. Air Force's Armstrong Laboratory has developed a data set describing the Advanced Dynamic Anthropomorphic Manikin (ADAM) for use in conjunction with the Articulated Total Body (ATB) model for the purpose of simulating the dynamics of the ADAM during sled track ejections. The purpose of this thesis is to validate the ADAM data set by graphically comparing ADAM joint angular displacements calculated by the ATB model with those measured during ejection seat sled track tests. The …

Experimental Investigation Of A Supersonic Turbulent Boundary Layer With Adverse Pressure Gradient, Chad S. Hale

Theses and Dissertations

Laser Doppler Velocimetry (LDV) measurements were made to quantify the effect of adverse pressure gradient on the compressible turbulent flow structure in a Mach 2.9 boundary layer (Re/m= 1.75 x 10⁷). Measurements included profiles of 2-D mean velocities, turbulence intensities, Reynolds shear stresses, intermittency, flatness and skewness. In addition, mean strain rates were also measured. The boundary layer measurements were acquired for both flat plate and compression ramp models. LDV measurements were made at two locations on the compression ramp model at 68 cm and 71 cm downstream of the nozzle throat. At these locations, Β …

Stress/Strain Ratio Effects On Fatigue Response Of A Scs-6/Ti-15-3 Metal Matrix Composite At Elevated Temperature, Sean C. Jackson

Theses and Dissertations

This study investigated the fatigue life and damage mechanisms of a [0]₈, SCS-6/Ti-15-3, metal matrix composite at 427°C for three different stress/strain ratios, R = -1, 0 and 0.5. Fatigue life and damage mechanism comparisons were made for the varying R ratios and between the load and strain control modes. Fatigue life comparisons show that on a maximum stress/strain basis as R is increased fatigue life increases while on a stress/strain range basis as R increases fatigue life decreases. Similar damage mechanisms were found between the R = -1 and R = 0 tests conducted at the same …

Vehicle Thermal Control With A Variable Area Inlet, Thomas R. Layne

Theses and Dissertations

This study developed a variable area inlet and controller that regulated the temperature of an electrical component with ram air. The intent of the variable area inlet was to reduce vehicle drag by eliminating inefficiencies associated with component cooling and fixed area inlets. These inefficiencies arise from vehicles moving at varying speeds through varying air temperatures. The hardware model consisted of an electrical component mounted inside a right-circular cylindrical duct. The variable area inlet, mounted in the front of the duct, consisted of a butterfly valve that was actuated by a stepper controller acted on the feedback signal of a …