Thesis (M.A.)--University of Delaware, 2007. / Principal faculty advisor: Robert Warren, School of Urban Affairs & Public Policy. Includes bibliographical references.

Thesis (M.S. in Computer Science)--Naval Postgraduate School, September 2002. / Thesis advisor(s): Bert Lundy, Mike Tatom. Includes bibliographical references (p. 85-89). Also available online.

Thesis (Ph. D.)--University of Washington, 1997. / Vita. Includes bibliographical references (leaves [115]-117).

Thesis (Ph.D.)--University of Delaware, 2010. / Principal faculty advisor: Gonzalo Arce, Dept. of Electrical & Computer Engineering. Includes bibliographical references.

Thesis (M.S.)--West Virginia University, 2007. / Title from document title page. Document formatted into pages; contains viii, 114 p. : ill. (some col.). Includes abstract. Includes bibliographical references (p. 84).

In this dissertation, adaptive predictive feedback control is used to suppress plate vibrations. The adaptive predictive controller consists of an on-line identification technique coupled with a control scheme. Various system identification techniques are investigated and implemented including batch least squares, projection algorithm, and recursive least squares. The control algorithms used include Generalized Predictive Control and Deadbeat Predictive Control. This dissertation combines system identification and control to regulate broadband disturbances in modally-dense structures. As it is assumed that the system to be regulated is unknown or time varying, the control schemes presented in this work have the ability to identify and regulate a plant with only an initial estimate of the system order. In addition, theoretical development and experimental results presented in this work confirm the fact that an adaptive controller operating in the presence of disturbances will automatically incorporate an internal noise model of the disturbance perturbing the plant if the system model order is chosen sufficiently large. It is also shown that the adaptive controller has the ability to track changes in the disturbance spectrum as well as track a time varying plant under certain conditions. This work presents a broadband multi-input multi-output control scheme which utilizes both the DSP processor and the PC processor in order to handle the computational demand of broadband regulation of a modally-dense plant. Also, the system identification technique and the control algorithm may be combined to produce a direct adaptive control scheme which estimates the control parameters directly from input and output data. Experimental results for various control techniques are presented using an acoustic plant, a rectangular plate with clamped boundary conditions, and a time varying plate. / Ph. D.

An analysis of waveforms, power spectral density and array responses was performed using geophones and broadband seismometers, co-deployed as part of a geologically motivated study. Broadband seismometers record excellent waveforms but, due to cost and deployment effort, wavefields are usually spatially aliased above ~0.1 Hz. Industry rapidly deploys many thousands of inexpensive, passive geophones to record full, unaliased seismic wavefields; however, waveform quality is limited below the instrument's natural frequency of ≥2 Hz. In 2012, coincident passive and controlled-source seismic surveys were deployed to investigate tectonics in Idaho and Oregon. Broadband stations were deployed at quiet sites every 15 km, taking experienced professionals >1 person-days per station. Fifty 4.5 Hz geophones and "Texan" seismographs at 200-m spacing were deployed per person-day by inexperienced students. Geophone data were continuously recorded for 3 nights and 1 day, while broadband seismometers were deployed for ~2 years. The spectral and array responses of these real deployments were compared. For a M7.7 teleseismic event, the broadband seismometer and geophone recorded nearly identical waveforms down to <0.03 Hz (32 s) and matching power spectral density down to 0.02 Hz (50 s). For quiet ambient noise, the waveforms strongly correlate down to <0.25 Hz (4 s) and the power spectral density match to the low-frequency side of the microseismic peak at ~0.15 Hz (~7 s). By deploying a much larger number of geophones, waveforms can be stacked to reduce instrument self-noise and beamforming can be used to identify wavefield azimuth and apparent velocity. Geophones can be an effective tool in ambient noise seismology down to ~7 seconds and can be used to record large seismic events effectively down to tens of seconds, well below the natural frequency of the instruments. A well-designed deployment of broadbands and geophones can enable full wavefield studies from long period to short period. Scientific and societal applications that could benefit from the improved unaliased wavefield bandwidth include local to regional seismicity, strong ground motion, magma migration, nuclear source discrimination, and crustal studies. / Master of Science / An analysis of seismic responses was performed using common seismology sensors, codeployed as part of a geologically motivated study. Broadband seismometers record seismic activity extremely well, however, due to cost and deployment effort, are less effective above ~0.1 Hz. Industry rapidly deploys many thousands of inexpensive, geophones, to record effectively above ~2 Hz; however, quality of the signal is limited below 2 Hz. In 2012, coincident seismic surveys were deployed to investigate earth structures in Idaho and Oregon. Broadband stations were deployed at every 15 km, taking experienced professionals >1 person-days per station. Fifty geophones and “Texan” seismographs at 200-m spacing were deployed per person-day by inexperienced students. Geophone data were continuously recorded for 3 nights and 1 day, while broadband seismometers were deployed for ~2 years. The seismic responses of these real deployments were compared. For a M7.7 earthquake, the broadband seismometer and geophone recorded nearly identical waveforms down to <0.03 Hz (32 s) and had similar characteristics down to 0.02 Hz (50 s). For low energy seismic signal, the waveforms were comparable down to <0.25 Hz (4 s) and had similar characteristics at ~0.15 Hz (~7 s). By deploying a much larger number of geophones, waveforms can be added together to improve signal quality and determine where the seismic source is located. Geophones can be an effective tool for low energy seismic signal down to ~7 seconds in period and can be used to record large seismic events effectively down to tens of seconds in period. A well-designed deployment of broadbands and geophones can enable full seismic studies from low and high frequencies which would have many scientific and societal benefits.

In this work, the potential of an active-skin is demonstrated for the reduction of broadband acoustic radiation from a vibrating structure. A simplified representation of the active-skin, employing acoustic monopoles as secondary sources, is explored as a precursor to the more complicated analyses of the device. Many design issues are addressed at this stage, taking advantage of the simplicity of this model. Numerical Methods, such as the Finite Element Method (FEM), are employed in the development of both structural and acoustic models for the active-skin. These modeling techniques are also employed for the primary structure, a simply-supported steel plate. The obtained models of the plate are validated using both theoretical and experimental comparisons. Experimental results are also used to verify the structural and acoustic models of the active-skin. Integration of these models into the control simulation provides a methodology for investigating the control characteristics of the active-skin. Two different skin configurations are investigated. The first employs the active-skin as a partial covering of a steel plate, while in the second configuration the active-skin completely covers a clamped aluminum plate. In each case, experimental results are presented, in which microphones are used as error sensors, for validation of the analytical active-skin model. The model is then used to investigate the effect of Structural Acoustic Sensing (SAS) on the control performance as an alternative to microphone error sensing. The adaptive feedforward Filtered-x Least-Mean-Square (LMS) algorithm is employed for both analytical and experimental control simulations showing the utility of such an active-skin in the control of structure-borne sound. A summary of the analytical and experimental findings is given and conclusions are drawn from these findings regarding the potential for the active-skin in the broadband attenuation of structurally radiated sound. / Master of Science

This thesis describes simulation models for Local Multipoint Distribution Service (LMDS) systems, and uses simulation to examine the performance of two different multiple access schemes and two different duplexing schemes. LMDS is a broadband wireless point-to-multipoint access network that aims to improve network access capacity for end-users by solving the "last mile" problem. This study involves building a parameterized simulation model for symmetric LMDS systems and comparing performance of the systems for different multiple access and duplexing schemes. The report describes the LMDS system and briefly discusses other broadband access networks. Objectives of this study are discussed and methodology is chosen. The simulation model design is explained. Further, the experimental design is discussed. The simulation results are presented and discussed, and conclusions are drawn. The multiple access schemes under study are Time Division Multiple Access (TDMA), and Frequency Division Multiple Access (FDMA). The duplexing schemes under study are Time Division Duplexing (TDD), and Frequency Division Duplexing (FDD). For the system under study, it was observed that TDMA results in lower end-to-end (ETE) delay per packet, but higher jitter, than FDMA. In addition, TDD results in lower ETE delay per packet than FDD. Specifically, TDMA in conjunction with TDD was found to result in lowest ETE delay per packet among the configurations under study. In addition, FDMA in conjunction with FDD was found to result in lowest jitter among the configurations under study. / Master of Science

This paper examines the effect of high-speed broadband expansion on the rural population and number of rural workplaces in Sweden in the years 2009 and 2014. Previous studies conducted on the subject have found positive correlations between broadband expansion and economic growth. However, most previous studies have been focused on urban areas and the transition from no broadband to basic broadband. This study focuses on the shift from basic broadband to high-speed access in rural areas in all 290 municipalities of Sweden. This paper uses cross-sectional data to perform OLS regressions to test the effect that an expansion of high-speed broadband has on rural population and rural workplaces. An accessibility measure is constructed to control for different access that each municipality has to the rest of the population as well as to control for spatial dependencies. The results of this paper show that there is a significant correlation between high-speed broadband expansion and the number of rural workplaces.