Engineering Commons^™

Video Coding For Bit Rates 64kbps And Below, Geoffrey N. Alagoda

Theses : Honours

With digital motion video for either transmission or storage, there always exists a trade-off between the data transmission rate and the picture quality. The lower the transmission bit-rate is made, the more the quality of the image tends to degrade. With usual transform coding schemes the degradation usually occurs when low bit-rates, that is less than about 64Kbps, are used. The resultant image tends to suffer visually from a ''blocking" effect. This thesis therefore, is based on the development of a different implementation scheme, for motion video compression or encoding, so as to support both low bit-rates, around 64Kbps or …

Robust Decentralised Variable Structure Control For Rigid Robotic Manipulators, Thasapalan Kuhan

Theses : Honours

In this thesis, the problem of robust variable structure control for non-linear rigid robotic manipulators is investigated. Robustness and convergence results are presented for variable structure control systems of robotic manipulators with bounded unknown disturbances, nonlinearities, dynamical couplings and parameter uncertainties. The major outcomes of the work described in this thesis are summarised as given below. The basic variable structure theory is surveyed, and some basic ideas such as sliding mode designs, robustness analysis and control1er design methods for linear or non-linear systems are reviewed. Three recent variable structure control schemes for robotic manipulators are discussed and compared to highlight …

Efficient Axis And Circle Detection Through Hough Transformation, Karissa E. Hobert

Presidential Scholars Theses (1990 – 2006)

Computer vision and human vision are quite different. While a person can look at an object and easily recognize it, a computer is does not understand the the objects it is seeing. Finding axes and circles in an image is an intermediate step in designing a machine with the ability to recognize shapes and objects. Through the utilization of contour and smoothed local symmetry information, the main axes of an image are determined and may be used to facilitate shape and object analysis. A Hough transform algorithm detects the most popular lines from a set of candidate axis points. This …

A Comparative Study Of The Perceived Educational Needs Of Iowa Merged Area Vii Manufacturers And Iowa Technical Educators, David D. Bradney

Dissertations and Theses @ UNI

This research was a descriptive pilot study that compared the perceptions of Iowa Merged Area VII manufacturers and Iowa technical educators regarding technical curricula, occupational skill certification, and drafting practices as these relate to Associate Degree programs in Mechanical Drafting and Design Technology. The problem was to determine what should be taught in two year technical curricula in Mechanical Drafting and Design Technology. The purpose of the study was to compare the perceived educational needs of Iowa Merged Area VII manufacturers and Iowa technical educators regarding the content of Mechanical Drafting and Design Technology curricula. The populations used for this …

Identification Of Success Factors In The Implementation Of Computer-Integrated Manufacturing, Dean Harold Jensen

Dissertations and Theses @ UNI

The review of recent literature showed a clear trend within the manufacturing sector toward the integration of design and production activities through increased application of the computer. The competitive advantages of computer integration were reported, as well as increased risk due to the amount of time and capital expended in system implementation. The identification of computer integrated manufacturing (CIM) success factors may reduce this risk.

Prior efforts to identify success factors for other areas of endeavor showed that success factors tended to vary with the four project phases, but were stable over time within a particular phase. More recently, empirical …

Compensation And Characterization Of Gallium Arsenide, Randy A. Roush

Electrical & Computer Engineering Theses & Dissertations

The properties of transition metals in gallium arsenide have been previously investigated extensively with respect to activation energies, but little effort has been made to correlate processing parameters with electronic characteristics. Diffusion of copper in gallium arsenide is of technological importance due to the development of GaAs:Cu bistable photoconductive devices. Several techniques are demonstrated in this work to develop and characterize compensated gallium arsenide wafers. The material is created by the thermal diffusion of copper into silicon-doped GaAs. Transition metals generally form deep and shallow acceptors in GaAs, and therefore compensation is possible by material processing such that the shallow …

Effects Of Specimen Size Reduction On The Transition Curve Of The Charpy V-Notch Impact Test, Lonnie Eugene Schubert

Masters Theses

"This study was undertaken to correlate the impact properties of ASTM standard full size Charpy V-notch impact specimens to the impact properties of subsize specimens. An ASTM A533-B quenched and tempered plate steel was examined. The fine grained martensitic material had a coarse prior austenite grain size, which resulted in a low upper shelf energy for this material. Three sizes of specimens were included. Specimens were irradiated in the TRIGA Reactor Facility operated by the U. S. Geological Survey in Denver, Colorado, to 1 x 10¹⁹ n/cm² (E > 1 MeV) at 150°C (302°F). Unirradiated and irradiated specimens were …

Eigenproperties Of Nonclassically Damped Dynamic Systems, Daniel Patrick Malone

Masters Theses

"This thesis develops perturbation series solutions for the eigenvalues and eigenvectors of nonclassically damped dynamic systems for the case where the unperturbed system has repeated eigenvalues. The case of repeated eigenvalues is much more complicated than the case of perturbing a system with distinct eigenvalues. Because of this difficulty, only a specific category of dynamic systems with repeated eigenvalues is addressed. Namely, only those systems that when perturbed have series solutions of the form of a power series. This category of systems can be easily identified by an a priori check developed in the application section of this thesis. The …

Nozzle Flow With Vibrational Nonequilibrium, John Gary Landry

Mathematics & Statistics Theses & Dissertations

Flow of nitrogen gas through a converging-diverging nozzle is simulated. The flow is modeled using the Navier-Stokes equations that have been modified for vibrational nonequilibrium. The energy equation is replaced by two equations. One equation accounts for energy effects due to the translational and rotational degrees of freedom, and the other accounts for the affects due to the vibrational degree of freedom. The energy equations are coupled by a relaxation time which measures the time required for the vibrational energy component to equilibrate with the translational and rotational energy components. An improved relaxation time is used in this thesis. The …

Impact Of Nuclear Rocket Engine Design On Control Strategies, John A. Lambright

Nuclear Engineering ETDs

In a nuclear thermal rocket engine, the propellant gas can be varied independent of the peak chamber temperature. Startup and shutdown times can be varied over a wide range due to this uncoupling of the energy source from the working fluid. Therefore, in the early stages of nuclear rocket engine development. a study of the impact of the engine design on control strategies and systems was conducted. In order to define what is required in terms of engine thrusting times. this study focused on the thrust requirements for a Reusable Orbital Transfer Vehicle (R0TV).

Three nuclear rocket designs were used …

Agglomarate Formation During Drying Of Fine Powders, Alok Maskara

Nuclear Engineering ETDs

The effect of capillary pressure, solubility, and surface chemistry on agglomeration of silica and titania particles during drying was studied. Three batches of silica particles with diameter between 15 and 500 nm as well as titania particles with nominal diameter of 30 nm were used. Drying rate was varied by using both tray drying and spray drying. Aprotic solvents ranging in surface tension from 18 dynes/cm (hexane) to 72 dynes/cm (water), and mixtures of water/propanol and water/butanol ranging in surface tension from 35 dynes/cm to 72 dynes/cm, were used to vary the surface tension of the solvent. Water between pH …

Will It Fly? A Computer-Based Aircraft Design Tool, Eric G. Woodfin

Honors Capstone Projects and Theses

No abstract provided.

Multicriteria Mission Route Planning Using A Parallel A* Search, Michael S. Gudaitis

Theses and Dissertations

The Mission Route Planning (MRP) Problem falls into the general class of multicriteria path search problems. Multiple criteria are evaluated to select an optimal aircraft mission route through a hostile environment. Criteria for distance travelled and radar exposure are combined into a single cost function for route evaluation. Radar calculations are performed dynamically. The A* search algorithm is applied to the MRP problem, and a parallel implementation is developed and tested. A unique combination of distributed OPEN lists with a global CLOSED list strategy produced fast execution times on the Paragon. Test cases for scenarios with 15 radars took less …

On Modeling Of A Mobile Multipath Fading Channel, Heng Xiao

Dissertations and Theses

Multipath fading is one of the major practical concerns in wireless communications. A multipath transmission takes place when a transmitted signal arrives at a receiver by two or more paths of different delay. Such multiple paths may be due to atmospheric reflection or refraction, or reflections from buildings or other objects. A multipath fading channel is usually modeled as a time-variant tapped delay system. RAKE receiver can be used to detect the signal from the multipath fading channel. However, the number of delay taps, the time delay of each path, and the tap weight for each delay path need to …

Methodology For Accurate Speedup Prediction, Aruna Chittor

Dissertations and Theses

The effective use of computational resources requires a good understanding of parallel architectures and algorithms. The effect of the parallel architecture and also the parallel application on the performance of the parallel systems becomes more complex with increasing numbers of processors. We will address this issue in this thesis, and develop a methodology to predict the overall execution time of a parallel application as a function of the system and problem size by combining simple analysis with a few experimental results. We show that runtimes and speedup can be predicted more accurately by analyzing the functional forms of the sequential …

Predicting Solute Transport In Natural Streams - A Stochastic Approach, Xueqing Zhou

Dissertations and Theses

The existing theories for predicting longitudinal dispersion in straight open channels have long been recognized as inadequate when applied to natural rivers. These theories tend to grossly underestimate dispersion in real streams since an important mixing mechanism due to nonuniform river cross-section variations is not explicitly taken into account. Recognizing the important role of stream irregularities on solute transport and the analytical difficulties of classical deterministic analysis, we develop a stochastic approach for analyzing solute transport in natural streams. Variations in river width and bed elevation are conveniently represented as one-dimensional random fields, characterized by their autocorrelation functions. Advection and …

The Effects Of The Proposed Larger Aircraft On Airport Capacity In The United States, Kerwin S. Mckenzie

Master's Theses - Daytona Beach

The problem of c is one that has been around for some time. With air travel projected to increase into the year 2000, Airbus Industrie, Boeing Corporation and McDonnell Douglas are making plans or are in the process of building large transports. Airbus has built the A340/A330 and is planning the now named A3XX, a 600 plus seater. Boeing is currently flying the 747-400 which holds up to 570 passengers. In addition, Boeing rolled out the 777 in June 1994, which holds up to 550 passengers. Douglas is planning the MD-12 with a 700 plus passenger load. The purpose of …

Airport Security Checkpoint Screener: An Analytical Study Of Job Retention And Attrition Factors, Norman Mark St. Laurent

Master's Theses - Daytona Beach

The proposed research seeks to identify the factors contributing to job retention and job attrition in terms of why an airport security checkpoint screener would try or want to stay on the job or leave the job. By identifying the causes of employee satisfaction and dissatisfaction, and by understanding the integral components of employee turnover can develop appropriate interventions that curb existing retention problems (exceeding 70% annually in most facilities). Aside from the obvious costs affiliated with recruiting, selecting, and training replacement employees, there is likely to be a detrimental impact on the effectiveness of airline passenger screening when a …

Airbus A320/321 Quick Change Market Analysis - A Case Study, Till Christian Mommsen

Master's Theses - Daytona Beach

The purpose of this thesis is to evaluate and compare the Boeing B737 QC to the Airbus A320/321 QC aircraft, and to determine their relative market within a sample airline. The technical design of the two Airbus aircraft in a mixed QC operation were considered with respect to the requirements of a particular airline. Direct operating costs and payload range data for all three aircraft were calculated.

To evaluate the competitiveness of the A320/321 QC under actual conditions, a linear programming fleet planning model was developed that considers more than the direct operating costs of a particular aircraft. The cost …

Survey And Implementation Of Commercial Manual Controllers For A Generic Telerobotics Architecture, Thomas E. Deeter

Theses and Dissertations

The purpose of this study is to determine an input device for the Air Force's generic telerobotics architecture for large aircraft maintenance and repair. One area of concern is the human to machine interface, more specifically, which manual controller should be used for the specified tasks in this architecture. We mailed a survey to 68 companies in order to compile a list of possible input devices that the telerobotics architecture could use. 32 companies responded which gave me enough data to generate a list that described the physical traits of the input devices. We then divided the required tasks into …

Multiclassifier Fusion Of An Ultrasonic Lip Reader In Automatic Speech Recognition, David L. Jennnings

Theses and Dissertations

This thesis investigates the use of two active ultrasonic devices in collecting lip information for performing and enhancing automatic speech recognition. The two devices explored are called the 'Ultrasonic Mike' and the 'Lip Lock Loop.' The devices are tested in a speaker dependent isolated word recognition task with a vocabulary consisting of the spoken digits from zero to nine. Two automatic lip readers are designed and tested based on the output of the ultrasonic devices. The automatic lip readers use template matching and dynamic time warping to determine the best candidate for a given test utterance. The automatic lip readers …

Electro-Hydrostatic Actuator Controller Design Using Quantitative Feedback Theory, Ki Ho Kang

Theses and Dissertations

The Electro-Hydrostatic Actuator (EllA) technology offers a higher degree of combat survivability and easier maintainability of the aircraft flight control system, because all the components necessary to operate the actuator are collocated with the actuator. Quantitative Feedback Theory (QFT) is used to design a control system for the EHA. The impact of parameter variations, sensor noise, and flight conditions are explicitly considered in the design process. The solution utilizes a two loop QFT feedback structure. The inner loop structure stabilizes the motor's angular velocity and decreases the outer loop's uncertainty. The outer loop structure controls the RAM piston's position to …

Fatigue Behavior Of A Cross-Ply Metal Matrix Composite At Elevated Temperature Under Strain Controlled Mode, Leon B. Dennis

Theses and Dissertations

This research extends the existing knowledge of cross-ply metal matrix composites (MMC) to include fatigue behavior under strain-controlled fully reversed loading. This study investigated fatigue life, failure modes and damage mechanisms of the SCS-6-Ti-15-3, [O-9O]_2s, MMC. The laminate was subjected to fully reversed fatigue at elevated temperature (427° C) at various strain levels. Stress, strain and modulus data were analyzed to characterize the macro-mechanical behavior of the composite. Microscopy and fractography were accomplished to identify and characterize the damage mechanisms at the microscopic level. Failure modes varied according to the maximum applied strain level showing either mixed mode …

Stall Precursor Study Of High Frequency Data For Three High Speed, Swept Compressor Rotors, James F. Anderton

Theses and Dissertations

The frequency spectra of three single stage, high speed compressor rotors were derived and analyzed from experimental data. The compressor rotors included straight, backward-swept, and forward-swept blade designs. Data was acquired from four pressure transducers located on the compressor casing and arranged axially between locations 40% of blade chord upstream of the rotor face to just over the leading edge of the blades. Each rotor was throttled to stall at two constant speeds between 90% and 100% of design speed. Data digitization at 20 kHz revealed multiples of the rotor frequency up to and beyond a dominant blade passing frequency. …

Characterization Of Fatigue Behavior Of 2-D Woven Fabric Reinforced Ceramic Matrix Composite At Elevated Temperature, Daniel J. Groner

Theses and Dissertations

This study investigated the fatigue behavior and associated damage mechanisms in notched and unnotched enhanced Sic-SiC ceramic matrix composite specimens at 1100°C. Stiffness degradation, strain variation, and hysteresis were evaluated to characterize material behavior. Microscopic examination was performed to characterize damage mechanisms. During high cycle-low stress fatigue tests, far less fiber-matrix interface debond was evident than in low cycle-high stress fatigue tests. Notched specimens exhibited minimal stress concentration during monotonic tensile testing and minimal notch sensitivity during fatigue testing. Damage mechanisms were also similar to unnotched.

Compressible Turbulence Measurements In A Supersonic Boundary Layer Including Favorable Pressure Gradient Effects, Raymond S. Miller

Theses and Dissertations

The effect of a favorable pressure gradient on the turbulent flow structure in a Mach 2.9 boundary layer (R_e/m approx. 1.5 x 10⁷) is investigated experimentally. Conventional flow and hot film measurements of turbulent fluctuation properties have been made upstream of and along an expansion ramp. Upstream measurements were taken in a zero pressure gradient boundary layer 44 cm from the nozzle throat in a 6.35 cm square test section. Measurements are obtained in the boundary layer, above the expansion ramp, 71.5 cm from the nozzle throat. Mean flow and turbulent flow characteristics are measured in …

An Investigation And Improvement Of Electrorheological (Er) Fluid Technology, Adil F. Dalal

Masters Theses

The purpose of this research was to investigate and overcome the limitations of Electrorheological (ER) fluids and to introduce this advanced technology at WMU. Electrorheological (ER) Fluids are a special class of fluids, which exhibit a reversible, infinitely variable phase transition from a liquid to a solid/semi-plastic state, in the presence of an electric field.

ER fluids can provide a unique solution to the problems of vibration isolation of systems. The applications are currently limited due to the high voltage requirements, electric power related heating and limited research into wear/abrasive characteristics of ER fluids.

A specially designed and constructed "electro-viscosimeter" …

A Heuristic Procedure For Designing A Cellular Manufacturing System While Minimizing Makespan, Panduranga Badam

Masters Theses

This study is the first of its kind in Group Technology (GT) literature and successfully demonstrates the application of the simulation technique to analyze different alternatives for machine and part grouping problem.

This study considers several aspects such as processing time, sequence of operations, alternative routing, setup time and dynamic shop condition for machine-part grouping. The heuristic developed aims to reduce intercellular moves, setup time and makespan time of parts. It also enables the decision markers to evaluate performance measures and to choose the best alternative at every step of the machine grouping process. Two examples have been used to …

The Effects Of Non-Uniform Blade Geometries On Cascade And Turbine Stage Performance, Hiroyuki Maeda

Masters Theses

It is known that in-service turbomachinery blades do not have uniform shapes. There are small differences due to blade erosion, manufacturing tolerances, or faulty installation. These differences can be in the size, shape, or relative angles of the blade. In an effort to predict losses resulting from changes in blade thickness and/or blade angles, a two-part investigation has been conducted. A two-dimensional unsteady Navier-Stokes flow analysis has been used to perform numerical experiments.

First, simulations were performed for an isolated cascade. One of the two stators was scaled and/or rotated. Results of the numerical simulations show that increasing the blade …

Design Of A Miniature Hydraulic Power Unit, Ryan D. Bruneau

Honors Theses

The need for a newly designed miniature hydraulic power unit has received the attention of Parker-Hannifin Hydraulic Pump/Motor Division. The current power unit is no longer marketable due to the associated costs and its relative size. As a result, a miniature hydraulic power unit has been designed, the culmination to the engineering curriculum at Western Michigan University. In order to increase the overall marketability and to reduce production costs, a transparent plastic reservoir has been incorporated into the design. An appropriate polymer has been chosen to meet the design requirements and finite element analysis has been used to verify the …