Engineering Commons^™

Comparison Of Optimization Methodologies For Sustained-Yield Groundwater Pumping Planning In East Shore Area, Utah, Shu Takahashi

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Combined simulation and optimization models, which are helpful for long-term groundwater planning of complex nonlinear aquifer systems, are developed using alternative modelling approaches. The models incorporate a representation of steady-state, quasi-three-dimensional head response to pumping within an optimization. An embedding model which describes exactly the nonlinear flow of an unconfined aquifer is presented. In contrast with the embedding models presented in the Utah State University Ground Water Model, it directly achieves the optimal solution without a "cycling." To address the nonlinearity of the flow system, response matrix models couple superposition with the cycling procedure. Their linear influence coefficients are generated …

Wing Rock Prediction Method For A High Performance Fighter Aircraft, Robert C. Nolan Ii

Theses and Dissertations

This study is a limited investigation of the nonlinear aircraft behavior known as wing rock. An eight state F-15 model is analyzed using bifurcation theory. The wing rock onset point is identified and small perturbation analysis is used to linearize the equations of motion about this point. The eigenstructure of the model is analyzed and is used to identify the stability modes involved in this motion. A procedure is developed to predict wing rock onset and frequency and the critical stability derivatives involved in this motion are identified. The developed procedure is applied to existing F-4J data and a flight …

Identifying Quality Function Deployment's Variables, Outcomes, Their Relationships, And Guidelines For Practitioners In The American Automotive Industry, Geoffrey Paul Gilmore

Dissertations and Theses

American industry is about nine to 12 years behind in utilizing a new product development and introduction process known as Quality Function Deployment (Q.F.D.). American industry must learn to compete internationally; the American automotive industry alone directly and indirectly employs millions of workers and has billions of dollars in annual sales and profits at stake.

With the cooperation of one American automotive company research has been conducted on Q.F.D. The research objectives were to identify: what variables affect Q.F.D., what are the outcomes from Q.F.D., what relationships exist between Q.F.D. variables and outcomes, and what guidelines may be offered to …

Effect Of Intruder Vertical Rate On Pilot Perception Of Separation On A Cockpit Traffic Display, Bryan H. Rooney

Master's Theses - Daytona Beach

The purpose of this study was to determine the effect of intruder vertical rate on pilots’ perception of aircraft separation as viewed on a cockpit traffic display. A group of 20 student pilots from Embry-Riddle Aeronautical University participated as subjects. SuperCard® software and a Macintosh II® personal computer were employed to generate the simulation of a cockpit display of traffic information. Each pilot monitored 84 scenarios in which they had to perceive how far away a single intruder would pass over or under their own aircraft. The pilots’ decision time, vertical and horizontal distance at decision time and percentage of …

A General Three Dimensional All Quadrilateral Surface Mesh Generation Algorithm, Roger Cass

Theses and Dissertations

Among the available all-quadrilateral mesh generation algorithms progressive-front offers the best quality and robustness. The paving algorithm is a progressive-front technique that generates a two dimensional mesh of all quadrilaterals on planar surfaces. The technique is particularly suited to meshing irregular boundaries with interior holes. This thesis presents an extension of the paving algorithm to generalized three dimensional surfaces. The major problems in three-dimensional surface mesh generation are projection of nodes, calculation of interior angles, and connection of mesh fronts. The solutions to these problems are presented. This work is part of the ongoing CUBIT project at Sandia Labs. The …

Determination Of The Parameter Limits For Artificial Non-Random Microwave Signal Detection, Irvin Lee Burough

Master's Theses - Daytona Beach

The Doppler shift of small bandwidth (several Hertz) microwave signals makes identification of spectral features difficult; the Doppler individual bandwidth shift can be a factor of hundreds or thousands of times greater than the bandwidth. A computer model supplied by the National Aeronautics and Space Administration's (NASA) Search for Extra-Terrestrial Intelligence (SETI) project, which can simulate radio frequency interference (RFI) and a buried ETI signal, will determine the limits of the signal-to-noise ratio (SNR) and false alarm threshold for identification of the signal after Doppler shifting. By running the model on a MicroVAX II computer, it will be possible to …

Computational Simulation Of Flow Through Elbows In The Approach Piping Systems To A Headbox, Kasinathan Ramanathan

Masters Theses

The successful operation of the wet end in a paper machine is highly dependent on the approach piping system. Sheet basis weight stability and ease of making wet end adjustments are greatly impaired by improperly designed approach piping systems. Most problems in headbox approach piping occur when the flow splits, combines, and passes through elbows.

Elbows create cross flows, flow separation, and eddies, and play an important role in the uniform and stable delivery of the pulp into the headbox. The effect due to an elbow lasts for a considerable distance downstream of the elbow and is severe when two …

The Indentation Of Foam Pattern Surfaces By Coordinate Measuring Machine Probes, Sanjay Nenawati

Masters Theses

When coordinate measuring machines are used to measure the complex shapes of foam patterns, the spherical probe tips indent into the soft surface of the pattern. Such indentation represents a measurement error since the indicated dimension will not be the same as the actual dimension. To determine the magnitude of error, the depth of probe tip indentation into PMMA and EPS foam surface (i.e., elastic indentation) was measured as a function of time, applied load, and foam density. The residual indentation after the removal of the load (i.e., plastic indentation) was also studied.

The depth of elastic indentation increased with …

On Planar Routing Of Multi-Terminal Nets In Vlsi Physical Design, Jahangir A. Hashmi

Masters Theses

In this thesis, we study two problems related to the physical design of VLSI circuits. One problem is related to the VLSI global routing and the other is related to the detailed routing in a bounded region.

We consider the routing of multiple multi-terminal nets on a single layer. We suggest a new approach for this problem. Our approach is based on simultaneously finding a forest of k non-intersecting spanning trees. We present an O(n^3) algorithm for finding two spanning trees corresponding to two nets on a single layer.

We also study the problem of finding a minimum Steiner tree …

Optimization Of Sodium Carbonate-Sodium Hydroxide Pulping Of Wheat Straw For Corrugating Medium Production, Irmak Yayin

Masters Theses

This study's primary objective was to present sodium carbonate pulping as an alternative to soda or lime pulping of wheat straw for corrugating medium production. If sodium carbonate pulping is comparable with soda pulping in terms of strength properties, it could be the preference of choice because the recovery of sodium carbonate is simpler requiring less capital investment. The two strength properties that were optimized with respect to total chemical charge, cooking time, and sodium hydroxide fraction in the cooking liquor were Concora crush resistance and STFI compressive strength. These are the two most important strength properties for the end …

Using Computerized Cinematography To Develop A Predictive Model Relating Muscle Stress And Wrist Movement, Joseph M. Kaczmar

Honors Theses

Workers in many jobs are required to perform the same tasks day after day. As a result of this repetitious work, many employees are developing what is know as Cumulative Trauma Disorders (CTD). There has been much research done on ways to prevent these disorders. Cumulative Trauma Disorders involving the wrist are of special concern. Repetitive motions and awkward positions of the wrist are a major cause of CTD's in the wrist. One such factor dealing with the posture is the angle between the hand and the forearm. In order to help limit the affects of CTD's of the wrist, …

Formant Estimation From Dctc's Using A Feedforward Neural Network, Shubhangi U. Kelkar

Electrical & Computer Engineering Theses & Dissertations

Formants are the natural frequencies of the human vocal tract. Existing methods for estimating formants from speech signals are computationally complex and subject to errors for certain type of speech sounds. This thesis describes a method for estimating vowel formant frequencies from Discrete Cosine Transform Coefficients (DCTC's), a form of cepstral coefficients, using a feedforward neural network with back-propagation training. Experimental results are based on a large multispeaker data base. The results are obtained for both a linear transformation and a feedforward neural network with a nonlinear hidden layer. In general, the neural network transformation is superior to the linear …

Characterization Of Trailing Line Vortices, Karla M. Mossi

Mechanical & Aerospace Engineering Theses & Dissertations

Mean velocity surveys were taken for axial or trailing line vortices produced behind a bi-wing vortex generator in a low-speed wind tunnel. Data were taken primarily with a seven-hole probe at a speed of 30m/s; but vortex steadiness was studied using smoke flow visualization over a speed range between 10 and 40 m/s. Various generator center body configurations were studied, with particular interest directed toward how a centerline jet and an asymmetric, unsteady circumferential flow influenced the mean velocity profiles. This study found that a centerline jet did not produce a well-behaved two-cell vortex over the parametric range available in …

Eigenvalue Reanalysis Techniques Using Msc/Nastran, Christopher B. Barton

Mechanical & Aerospace Engineering Theses & Dissertations

Reanalysis is a numerical analysis technique that uses results from the total analysis of a design to compute the new response at a reduced computational cost. While there are many techniques available for reanalysis, the first order perturbation technique is investigated in this study. Because of its wide use in industry, NASTRAN finite element analysis software is used for total analysis, and as a basis for error. Since error seems rather unpredictable for this technique, it is sought, in this thesis, to find a reliable index for error so that a designer can know when the technique can be trusted. …

Preliminary Structural Design Of A Lunar Transfer Vehicle Aerobrake, Lance B. Bush

Mechanical & Aerospace Engineering Theses & Dissertations

An aerobrake concept for a Lunar transfer vehicle was weight optimized through the use of the Taguchi design method, structural finite element analyses and structural sizing routines. Six design parameters were chosen to represent the aerobrake structural configuration. The design parameters included honeycomb core thickness, diameter-to-depth ratio, shape, material, number of concentric ring frames, and number of radial frames. Each parameter was assigned three levels. The minimum weight aerobrake configuration resulting from the study was approximately half the weight of the average of all twenty seven experimental configurations. The parameters having the most significant impact on the aerobrake structural weight …

Modal Analysis Of Gyroscopically Coupled Sound-Structure Interaction Problems, Vijay B. Bokil

Mechanical & Aerospace Engineering Theses & Dissertations

In many practical situations we encounter sound-structure interaction between the fluid in a cavity and the flexible wall on the boundary. The aircraft cabin interacting with its fuselage and double-leaf partition walls interacting with the enclosed cavity are some of the typical examples. The vibratory behavior of the structure and the acoustical pressure inside the cavity are affected by this interaction.

In most of the cases, the governing differential equations for the coupled system can be shown to involve gyroscopic coupling. A special method has been applied to decouple the equations in terms of pairs of generalized coordinates and the …

Transfer Function Models And Control Of A Flexible Structure Using Piezoelectric Laminates, Joseph A. Colvin

Mechanical & Aerospace Engineering Theses & Dissertations

The development of piezoelectric polymer films has generated a great deal of excitement in the structural controls community because they are lightweight, durable, distributed in nature and have broad band frequency characteristics. The flurry of research inspired by piezoelectric films has primarily been dedicated to using them as distributed sensors, and to a lesser extent, as distributed actuators.

Active damping of structural vibrations using piezoelectric polymer films as sensors and actuators has primarily been directed toward taking advantage of their distributed nature and employing various types of distributed control theory. This approach does not easily yield insight into the dynamics …

Development Of A Model Updating Technique For Controls-Structures Integrated Design Optimization, Angela Georges

Mechanical & Aerospace Engineering Theses & Dissertations

A model updating technique is developed with the intent of providing an efficient means of improving the accuracy of the modelling of the vibrational qualities of a large, flexible structure as it undergoes an integrated controls-structures design optimization. The proposed technique utilizes eigenvalue/eigenvector sensitivity information, two different model reduction methods which assign weights of importance to the vibrational modes of the structure, and modal switching based upon the modal weights determined by the model reduction methods. Issues associated with the numerical implementation of the proposed technique, such as discontinuities induced by modal switching, are also addressed.

The proposed model updating …

Neural Network Based Vowel Articulation Training Aid For The Deaf, Andrew E. Beck

Electrical & Computer Engineering Theses & Dissertations

Teaching the hearing-impaired to speak is both a challenging and rewarding task. Computer-based training aids are valuable teaching tools and complement the speech therapist in the speech training process. We have developed a computer based vowel articulation training aid designed to provide visual feedback for vowel production to the hearing-impaired user. This system transforms speech spectra from a multi-dimensional acoustic space to a two-dimensional phonetic space which is displayed on a computer monitor. The system signal processing includes feature extraction designed to mimic the properties of the human ear, and a transformation to a two-dimensional display space. The dimensionality transformation …

Shape Sensitivity Analysis And Optimization Of Skeletal Structures And Geometrically Nonlinear Solids, Ching-Hung Chuang

Mechanical & Aerospace Engineering Theses & Dissertations

Formulations and computational schemes for shape design sensitivity analysis and optimization have been developed for both skeletal structures and geometrically nonlinear elastic solids. The continuum approach, which is based on the weak variational form of the governing differential equation and the concept of the material derivative, plays a central role in such a development.

In the first part of this work, the eigenvalue and eigenvector sensitivity equations for skeletal structures are derived with respect to configuration variables of joint and support locations. This derivation is done by the domain method as well as the boundary method. The discrete approach for …

A Computational Aerodynamic Design Optimization Method Using Sensitivity Analysis, Mohamed E. Eleshaky

Mechanical & Aerospace Engineering Theses & Dissertations

A new and efficient procedure for aerodynamic shape optimization is presented. The salient lineaments of this procedure are: (1) using a discrete sensitivity analysis approach to determine analytically the aerodynamic sensitivity coefficients; (2) obtaining the flowfield solution either by a computational fluid dynamics (CFD) analysis or, alternatively, by a flowfield extrapolation method which is based on a truncated Taylor's series; (3) defining the aerodynamic shape in such a way that it is not restricted to any class of surfaces and the optimizer automatically shapes the aerodynamic configuration to any arbitrary geometry; and (4) requiring no expertise other than that needed …

Control Of Low-Speed Turbulent Separated Flow Over A Backward-Facing Ramp, John C. Lin

Mechanical & Aerospace Engineering Theses & Dissertations

The relative performance and flow phenomena associated with several devices for controlling turbulent separated flow were investigated at low speeds. Relative performance of the devices was examined for flow over a curved, backward-facing ramp in a wind tunnel, and the flow phenomena were examined in a water tunnel using dye-flow visualization. Surface static pressure measurements and oil-flow visualization results from the wind tunnel tests indicated that transverse grooves, longitudinal grooves, submerged vortex generators, vortex generator jets (VGJ’s), Viets’ fluidic flappers, elongated arches +a + a (positive angle of attack), and large-eddy breakup devices (LEBU’s) +a + a placed near the …

Unsteady Euler And Navier-Stokes Computations Around Oscillating Delta Wing Including Dynamics, Ahmed Abd-El-Bar Ahmed Salman

Mechanical & Aerospace Engineering Theses & Dissertations

Unsteady flows around rigid or flexible delta wings with and without oscillating leading-edge flaps are considered. These unsteady flow problems are categorized under two classes of problems. In the first class, the wing motion is prescribed a priori and in the second class, the wing motion is obtained as a part of the solution. The formulation of the first class includes either the unsteady Euler or unsteady Navier-Stokes equations for the fluid dynamics and the unsteady linearized Navier-displacement (ND) equations for the grid deformation.

The problem of unsteady transonic flow past a bicircular-arc airfoil undergoing prescribed thickening-thinning oscillation is studied …

Hierarchical Flux-Based Thermal-Structural Finite Element Analysis Method, Sandra P. Polesky

Mechanical & Aerospace Engineering Theses & Dissertations

A hierarchical flux-based finite element method is developed for both one- and two-dimensional thermal-structural analyses. Derivation of the finite element equations is presented. The resulting finite element matrices associated with the flux-based formulation are evaluated in closed-form. The hierarchical finite elements include additional degrees of freedom in the approximation of the element variable distributions by the use of nodeless variables. The nodeless variables offer increased solution accuracy without the need for defining actual nodes and rediscretizing the finite element model. Thermal and structural responses obtained using the hierarchical flux-based method are compared with results obtained from a conventional linear finite …

Optimization Of Cryopreservation Protocols For Cardiovascular Tissue, Jianfei Hu

Theses and Dissertations in Biomedical Sciences

The purpose of this research was to determine the effects of cryopreservation on the physical, biochemical and cellular aspects of heart valve tissue. The present study demonstrated that radiolabeled proline accumulation provides a quantitative estimate of total cellular metabolic viability. Radiolabeled inulin was demonstrated to be a useful marker for extracellular tissue space. Assessment of metabolic viability of the cellular population of leaflet tissue as a function of procurement and processing revealed that proline accumulation declined with increasing warm and cold ischemic times. Amphotericin B and streptomycin were toxic to the cells. Cefoxitin, lincomycin, polymyxin B, vancomycin and penicillin had …

Materially Nonlinear Finite Element Analyses Of Trusses And Slab-On-Grade Problems, Moayyad Moh'd Al-Nasra

Civil & Environmental Engineering Theses & Dissertations

The overall approach is to employ the finite-element method along with specified material models to account for material nonlinearity. This study includes two different applications: truss structures and slabs-on-grade.

Procedures for materially nonlinear analysis of truss structures, which apply for both determinate and indeterminate cases are proposed. The proposed procedures are simple and can handle a variety of different stress-strain functions, and the applied load does not have to be incremental. Proposed procedures results are verified with the output of NASTRAN.

A finite-element model for slab-on-grade is introduced. The concrete slab is represented by eight-node brick elements, and the joints …

Inelastic Stability Of Nonproportionally Loaded Steel Sway Beam-Columns And Space Frames, Saleh Ali Eidan

Civil & Environmental Engineering Theses & Dissertations

A comprehensive study of the inelastic stability of steel beam-columns and frames subjected to nonproportional loads is conducted. A set of materially nonlinear differential equations of equilibrium for planar and biaxially loaded beam-columns are first formulated including sidesway. The analysis includes the effect of flexible connections, and initial imperfections in the form of member crookedness and residual stresses. Also, hollow rectangular sections are adopted for the study. First, an iterative numerical solution procedure is formulated for sway beam-columns utilizing central finite-differences with second-order truncation errors. Next, using the beam-column analysis, an inelastic frame analysis procedure is formulated by a conversion …

Comparison Of Synchronization Techniques For The Afit Direct Sequence Spread Spectrum System, Edward A. Bednar

Theses and Dissertations

The purpose of this study is to analyze and evaluate the performance of several code synchronization methods that could be used in the Air Force Institute of Technology's (AFIT) Direct-Sequence Spread Spectrum (DSSS) communication system. These methods include the sliding correlator, transmitted reference, sequential estimation, and three types of matched filters. The matched filters are the baseband matched filter, delay line matched filter, and the convolver. The criteria used for the evaluation of these synchronization methods are theoretical synchronization times and probability of bit-error. Advantages and disadvantages of each synchronization method are described and a method is recommended to be …

Strategic Deterrence In The Post-Start Era, David C. Mccormick

Theses and Dissertations

With the Soviet Union's fall there have been widespread calls for drastic reductions in the United States military's strategic nuclear forces. Although a major threat to the United States has been greatly reduced, the number of strategic targets will not decrease as rapidly as the number of available weapons. This research considers how the United States should think about strategic forces in the rapidly changing world order of the 1990s. An extensive literature review of deterrence concepts and conventional weapons capabilities is conducted with special attention paid to the role that precision guided munitions played in the 1991 Persian Gulf …

Mapping Programs To Parallel Architectures In The Real World, Dezheng Tang

Dissertations and Theses

Mapping an application program to a parallel architecture can be described as a multidimensional optimization problem. To simplify the problem, we divide the overall mapping process into three sequential substeps: partitioning, allocating, and scheduling, with each step using a few details of the program and architecture description. Due to the difficulty in accurately describing the program and architecture and the fact that each substep uses incomplete information, inaccuracy is pervasive in the real-world mapping process. We hypothesize that the inaccuracy and the use of suboptimal, heuristic mapping methods may greatly affect the mapping or submapping performance and lead to a …