Master of Science

<p>With continuing advances in technology, the market for vehicle navigation systems is expected to grow over the next several years. The systems engineering process is applied to ensure that an effective system is developed. After the need is established, four methods of implementing a vehicle navigation system are described. A system employing differential GPS to determine the location of the vehicle is chosen to be the most feasible approach. Based on this choice, the operational requirements and maintenance concept are defined. Possible design approaches are then discussed. A terrestrial radio link is selected over a satellite link to transmit the differential corrections to users. Finally, an analysis is performed to estimate the number of reference stations that will be required to implement the system. The results can be used as a guideline to determine the potential cost of providing a differential GPS service.</p> / Master of Science

Master of Science

<p>The subject matter of this project and report is the application of systems engineering principles to this country's fiscal and monetary policies. The project demonstrates the use of systems engineering principles in the analysis of the current economic problems and in the formulation of possible solutions to these problems. A basic overview of current fiscal and monetary systems provides a foundation for understanding the problems and possible solution approaches.</p> <p> Many systems engineering tools and techniques are useful in solving the nation's economic problems. Systems analyses, including verbal modeling, causal diagramming, and simulation modeling are capable of finding the root causes of current economic difficulties. The principles of life-cycle cost analysis are excellent tools for improving the federal budgetary process. Multiattribute decision analysis methods are invaluable when prioritizing competing projects. Benefit-cost analyses ensure that a given project yields benefits that are worth the cost to the taxpayers. Functional analyses and decision making techniques are useful in eliminating waste from federal agencies, and they ensure critical resources are employed in the most productive manner. Mathematical modeling techniques are used to project the results of proposed fiscal and monetary policies.</p> / Master of Science

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<p>An educational system called GeoSim is being developed at Virginia Tech; its purpose is to simulate processes related to several geographical subjects. The software consists of six different modules; one of these modules is designed to simulate a field trip for orienteering and position finding. This module uses a database of captured images to pan and zoom from one location to another. However, the original images have overlapping areas which does not allow simulating a continuous panoramic view. To fix this problem a cropping tool was designed and implemented with Intel DVI ActionMedia boards to support the orienteering module of project GeoSim. The tool allows cropping of overlapped areas in the images. In addition, the tool allows the user to minimize differences in intensity and colors between neighboring images. The cropping, color, and intensity values obtained from manipulating images are saved in an ASCII file where they can be read and used in the orienteering module. The images used are captured and stored on the hard disk from a videodisc, with 512x480 resolution and 16 bits per pixel DVI compressed format.</p> / Master of Science

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No description available.

Three types of problems in nonlinear dynamics are studied. First, we use a complex-variable invariant-manifold approach to determine the nonlinear normal modes of weakly nonlinear discrete systems with one-to-one and three-to-one internal resonances. Cubic geometric nonlinearities are considered. The system under investigation possesses similar nonlinear normal modes for the case of One-to-one internal resonance and nonsimilar nonlinear normal modes for the case of three-to-one internal resonance. In contrast with the case of no internal resonance, the number of nonlinear normal modes may be more than the number of linear normal modes. Bifurcations of the calculated nonlinear normal modes are investigated. For continuous systems without internal resonances, we consider a cantilever beam and compare two approaches for the determination of its nonlinear planar modes. In the first approach, the governing partial-differential system is discretized using the linear mode shapes and then the nonlinear mode shapes are determined from the discretized system. In the second approach, the boundary-value problem is treated directly by using the method of multiple scales. The results show that both approaches yield the same nonlinear modes because the discretization is performed using a complete set of basis functions, namely, the linear mode shapes. Second, we study the nonlinear response of multi-degree-of-freedom systems with repeated natural frequencies to various parametric resonances. The linear part of the system has a nonsemisimple one-to-one resonance. The character of the stability and various types of bifurcation are analyzed. The results are applied to the flutter of a simply supported panel in a supersonic airstream. In which case, the nonlinear ordinary differential equations governing the modulation of the amplitudes and phases of the excited modes are derived and used to calculate the equilibrium solutions and their stability and hence to identify the excitation parameters that suppress flutter and those that lead to complex motions. A combination of a shooting technique and Floquet theory is used to calculate limit cycles and their stability. The numerical results indicate the existence of a sequence of period-doubling bifurcations that culminates in chaos. The complex motions are characterized by using phase planes, power spectra, Lyapunov exponents, and dimensions. Moreover, bifurcation analyses in the case of fundamental parametric resonance reveal that the addition of quadratic nonlinearities change qualitatively as well as quantitatively the response of systems with cubic nonlinearities. The quadratic nonlinearities change the pitchfork bifurcation to a transcritical bifurcation. Cyclic-fold bifurcations, Hopf bifurcations of the nontrivial constant solutions, and period-doubling sequences leading to chaos are induced by these quadratic terms. The effects of quadratic nonlinearities for the case of principal parametric resonance are discussed. Third, we investigate the transfer of energy from high- to low-frequency modes. The method of averaging is used to analyze the response of a two-degree-of-freedom system with widely spaced modal frequencies and cubic nonlinearities to a principal parametric resonance of the high-frequency mode. The conditions under which energy can be transferred from high- to low-frequency modes, as observed in the experiments, are determined. The interactions between the widely separated modes result in various bifurcations, the coexistence of multiple attractors, and chaotic attractors. The results show that damping may be destabilizing. The analytical results are validated by numerically solving the original system. / Ph. D.

Public administration is struggling with its identity at a time when cultural events would indicate that it has failed to do its job. However, the chaos of the current context of society marks an evolutionary window for both public administration and the American culture. Public administration can either decide to make one more adaptation to the historical dialectics of economic dialogue, or it can choose to embrace a new identity -- one more in line with its democratic and constitutional roots. However, to demand that public administration become more aware of its democratic responsibilities, also requires that public administration be given a new voice with which to speak -- one different from the management paradigm within which it has spoken in this century. What is called the Ontology of Neo-Darwinism has created a consciousness among public administrators which limits what they feel they can do and what they can talk about to the boundaries of that consciousness. In particular, the consciousness has come to appear like a state which can not be exceeded, despite its undemocratic tendencies, because of limitations which are perceived to define the nature of human relationships. It is proposed here that an Evolutionary ontology is more appropriate for the tasks of public administration. It is an ontology which views relationship and responsibility as the basis of human process, rather than fear and blame. The philosophical roots of the Ontology of Neo-Darwinism are described and the Evolutionary ontology defined. / Ph. D.