Systems Engineering and Multidisciplinary Design Optimization Commons^™

A Decision Support Model For Establishing A Plastics Recycling Program, Deven M. Dalcher

Theses and Dissertations

This research focuses on the development of a decision support model for the establishment of a plastics recycling program. The decision support model focuses on identifying the end-product uses and material specifications first. Once the end-product specifications have been identified, the recycling program can be designed. The model will provide solid waste managers an effective decision-making tool to evaluate the economic feasibility of establishing a plastics recycling program.

A Systems Engineering Approach To Environmental Risk Management: A Case Study Of Depleted Uranium At Test Area C-64, Eglin Air Force Base, Florida, Charles M. Carter, Kristina M. Fortmann, Stephen W. Hill, Robert M. Latin, Edward J. Masterson, Joseph A. Roh, Sujay R. Setlur

Theses and Dissertations

Environmental restoration is an area of concern in an environmentally conscious world. Much effort is required to clean up the environment and promote environmentally sound methods for managing current land use. In light of the public consciousness with the latter topic, the United States Air Force must also take an active role in addressing these environmental issues with respect to current and future USAF base land use. This thesis uses the systems engineering technique to assess human health risks and to evaluate risk management options with respect to depleted uranium contamination in the sampled region of Test Area (TA) C-64 …

Design And Implementation Of Fuzzy Logic Controllers. Thesis Final Report, 27 July 1992 - 1 January 1993, Osama A. Abihana, Oscar R. Gonzalez

Electrical & Computer Engineering Faculty Publications

The main objectives of our research are to present a self-contained overview of fuzzy sets and fuzzy logic, develop a methodology for control system design using fuzzy logic controllers, and to design and implement a fuzzy logic controller for a real system. We first present the fundamental concepts of fuzzy sets and fuzzy logic. Fuzzy sets and basic fuzzy operations are defined. In addition, for control systems, it is important to understand the concepts of linguistic values, term sets, fuzzy rule base, inference methods, and defuzzification methods. Second, we introduce a four-step fuzzy logic control system design procedure. The design …

Theoretical Results Supporting The Use Of Passive Damping As Augmentation To The Active Control Of Flexible Structures, Joseph Vincent Harrell

Mechanical & Aerospace Engineering Theses & Dissertations

One challenge of modern control technology is how to control a flexible structure with accuracy, speed, and economy of effort. Controlling a structure with many degrees of freedom by purely active means implies the implementation of inordinate sensors and actuators and creates the need for numerous calculations that must be done instantly. Experiments have shown that practical structures under active control alone can suffer instabilities due to modal vibrations beyond the bandwidth of the active controller. Furthermore, if there is a high degree of model uncertainty, instabilities can be produced by inputs of modal vibrations not occurring in the system …

A Top-Down Performance Analysis Of A Pegasus-Based Space Strike System, Douglas E. Collins

Theses and Dissertations

The feasibility of using Pegasus launch vehicle as a conventional weapons platform is examined. Using a top-down approach, the analysis addresses the fundamental question of whether such a system should be considered for development. The measures of effectiveness considered are delivery range, probability of destroying the target, and responsiveness. Each of the measures is assessed at its top-level and analyzed only to the level of detail needed to address the fundamental question. The study indicates that attaining a high probability of destroying the target requires extremely precise control over the burnout conditions and that the system must be on constant …

Maximum Likelihood Estimation For Distributed Parameter Models Of Large Beam-Like Structures, Ji Yao Shen

Mechanical & Aerospace Engineering Theses & Dissertations

Proposed large space structures have many characteristics that give an advantage to modeling their structural dynamics by a set of partial differential equations (PDE's). By far, the most effort put forth in studying system identification and control to date has been based on finite element models. Despite its acceptability, such lumped parameter models have inevitable deficiencies primarily because of their complexity. Both approaches are complementary and each should be used where it is most effective. But the fact is that the distributed parameter approach has not been developed to the level of maturity as for the lumped parameter approach.

Motivated …

High Heat Flux Cooling For Spacecraft Electronics, Louis C. Chow, John E. Leland

Office for Research Publications and Presentations

An experimental investigation of flow boiling in a curved channel has been performed to ascertain its value in electronics cooling applications. Results have been obtained for flow velocities of 1 to 5 m/s and subcooling of 0.5 to 40 K. These results were compared to those of straight channel under identical velocity and subcooling conditions. The critical heat flux of the curved channel was found to be greater than that of the straight channel. In some cases the increase was found to be marginal, however. An unexplained temperature shift in the nucleate boiling regime was experienced during some experiments. Because …

Multidisciplinary Modeling And Design Of A Space Structure, Brian K. Cassiday, Lawrence L. Gatchet, John T. Tester, Stephen O. Gaines Ii, Mario N. Moya

Theses and Dissertations

A method is needed to simultaneously integrate several engineering disciplines into one complete model to determine the performance of the system as a whole during the design development. System engineering methodologies are particularly suited to this problem. These methods provide a structured approach to problem formulation and system parameter identification. Bond graphs are also well suited as bond graphs model power flow and energy relationships within subsystems, a characteristic inherent to all dynamic systems. The intent of this research was to demonstrate the use of concurrent engineering theory to systematically model a large flexible space structure involving several engineering disciplines. …

An Aluminum Salvage Station For The External Tank (Asset), James N. Haislip Jr., William C. Raynes Jr., David L. Van Matte, Roger E. Linscott, Michael A. Skinner

Theses and Dissertations

The external tank is currently the only non-reusable portion of the National Space Transportation System. The tank has 98% of the energy required to be placed in orbit at the point it is jettisoned. The purpose of this study is to develop techniques which would transform this throw-away item into a source of construction material at low earth orbit. A simulation is developed to verify the reduction timelines and peak power requirements for manual and automated reduction. The required tools to accomplish the tasks of initial cutting, product transport, spray on foam insulation removal, and product storage are developed. A …

Multi-Input Multi-Output Flight Control System Design For The Yf-16 Using Nonlinear Qft And Pilot Compensation, Russell B. Miller

Theses and Dissertations

Nonlinear Quantitative Feedback Theory (QFT) and pilot compensation techniques are used to design a 2x2 flight control system for the YF-16 aircraft over a large range of plant uncertainty. The design is based on numerical input- output time histories generated with a FORTRAN implemented nonlinear simulation of the YF-16. The first step of the design process is the generation of a set of equivalent linear time-invariant (LTI) plant models to represent the actual nonlinear plant. It has been proven that the solution to the equivalent plant problem is guaranteed to solve the original nonlinear problem. Standard QFT techniques are then …

Eigensensitivity Analysis For Space Structures With Applications In Design Optimization, Sean Patrick Kenny

Mechanical & Aerospace Engineering Theses & Dissertations

Eigensensitivity analysis is concerned with the rates of changes of eigenvalues and eigenvectors with respect to design variables. Eigensolutions of space structures are found to display four distinct characteristics, three of which are related to various types of repeated eigenvalues. This study will address three cases of the real symmetric structural eigenvalue problem. The three cases that will be considered are: distinct eigenvalues, repeated eigenvalues with distinct first eigenvalue derivatives, and repeated eigenvalues with infinitely repeating eigenvalue derivatives. Analytic formulations for eigenvalue/ vector derivatives will be presented for each of the three cases. The directional differentiability of eigenvalues for the …

Optimized Engine Out Procedures To Extend The Range Of Jet Transport Airplanes, Miltos Miltiadous

Master's Theses - Daytona Beach

The purpose of this study was to develop optimum engine-out procedures for the Boeing 747 and 767 on extended flights that will increase the range of the aircraft in case of engine failure. Theory suggests that an optimum amount of bank angle that will minimize drag resulting from asymmetric thrust in a multiengine airplane experiencing an engine failure, can be determined. By banking the airplane into the operative engines by that optimum bank angle, the range of the airplane can be improved significantly. Wind tunnel tests of both a Boeing 747 and a 767 model were performed to determine experimentally …

Continuous Digital Simulation Of The Second-Order Slowly Varying Wave Drift Force, Bohdan W. Oppenheim, P. A. Wilson

Systems Engineering Faculty Works

A discussion is given on practical aspects of digital representation in time of the slowly oscillatory second-order wave drift force from a known force spectrum. The emphasis is placed on the computational efficiency and on the suitability of the simulation to a numerical integration of an equation of motion using a variable integration step size, where the force acts as the excitation of motion. The effect of approximating the original spectrum by a white spectrum is discussed. A sensitivity analysis is made to the range of frequencies of the spectra. The force time record is obtained by first generating at …