No description available.

No description available.

No description available.

No description available.

No description available.

No description available.

A new technique to de-Dopplerize microphone signals from moving sources of sound is derived. Currently available time domain de-Dopplerization techniques require oversampling and interpolation of the microphone time data. In contrast, the technique presented in this dissertation performs the de-Dopplerization entirely in the frequency domain eliminating the need for oversampling and interpolation of the microphone data. As a consequence, the new de-Dopplerization technique is computationally more efficient. The new de-Dopplerization technique is then implemented into a frequency domain beamforming algorithm to locate moving sources of sound. The mathematical formulation for the implementation of the new de-Dopplerization technique is presented for sources moving along a linear trajectory and for sources moving along a circular trajectory, i.e. rotating sources. The resulting frequency domain beamforming method to locate moving sound sources is then validated using numerical simulations for various source configurations (e.g. emission angle, emission frequency, and source velocity), and different processing parameters (e.g. time window length). Numerical datasets for sources with linear motion as well as for rotating sources were simulated. For comparison purposes, selected datasets were also processed using traditional time domain beamforming. The results from the numerical simulations show that the frequency domain beamforming method is at least 10 times faster than the traditional time domain beamforming method with the same performance. Furthermore, the results show that as the number of microphones and/or grid points increase, the processing time for the traditional time domain beamforming method increases at a rate 20 times larger than the rate of increase in processing time of the new frequency domain beamforming method. / Ph. D.

Conventional streamlined autonomous underwater vehicles (AUVs) with a single thruster and stern planes are typically trimmed to be somewhat buoyant or heavy in water. To maintain depth, they must generate a constant hydrodynamic force which requires that they swim at a constant pitch angle. Although tail fins are the typical mechanism for generating this control moment, they become ineffective at low speeds. To enable an existing AUV to travel at lower speeds, one may easily incorporate a modular moving mass actuator. In some cases, it may also be advantageous to include a fixed wing. The equations of motion and equilibrium conditions to regulate depth are derived, and the effectiveness and low-speed efficiency of a fixed wing is evaluated. The effect of the vertical offset of the moving mass is analyzed to establish the relation between the control angle and the moving mass linear position. A description of the design of a one degree of freedom moving mass actuator module and preliminary experiments using the Virginia Tech Miniature AUV is provided. Data is presented for a series of fixed MMA position experiments as well as a dynamic position test. The results illustrate the effectiveness of a moving mass actuator at generating low-speed control moments. With the collected data, parameter identification is performed to get an estimate of the hydrodynamic parameters. / Master of Science

"A significant work of architecture is never the product of a single individual. It is always a collaboration with history and tradition, with the silent wisdom of the discipline of architecture. An architect who understands the essence of his craft accepts his role as a builder of a tradition, and he places his work in the context of this continuum with combined humility and pride." Juhani Pallasmaa. / Master of Architecture

Society's increased use of network applications, such as email, social networking, and web browsing, creates a massive amount of information floating around in cyber space. An attacker can collect this information to build a profile of where people go, what their interests are, and even what they are saying to each other. For certain government and corporate entities, the exposure of this information could risk national security or loss of capital. This work identifies vulnerabilities in the way the Internet Protocol version 6 (IPv6) forms addresses. These vulnerabilities provide attackers with the ability to track a node's physical location, correlate network traffic with specific users, and even launch attacks against users' systems. A Moving Target IPv6 Defense (MT6D) that rotates through dynamically obscured network addresses while maintaining existing connections was developed to prevent these addressing vulnerabilities.MT6D is resistant to the IPv6 addressing vulnerabilities since addresses are not tied to host identities and continuously change. MT6D leverages the immense address space of IPv6 to provide an environment that is infeasible to search efficiently. Address obscuration in MT6D occurs throughout ongoing sessions to provide continued anonymity, confidentiality, and security to communicating hosts. Rotating addresses mid-session prevents an attacker from determining that the same two hosts are communicating. The dynamic addresses also force an attacker to repeatedly reacquire the target node before he or she can launch a successful attack. A proof of concept was developed that demonstrates the feasibility of MT6D and its ability to seamlessly bind new IPv6 addresses. Also demonstrated is MT6D's ability to rotate addresses mid-session without dropping or renegotiating sessions.This work makes three contributions to the state-of-the-art IPv6 research. First, it fully explores the security vulnerabilities associated with IPv6 address formation and demonstrates them on a production IPv6 network. Second, it provides a method for dynamically rotating network addresses that defeats these vulnerabilities. Finally, a functioning prototype is presented that proves how network addresses can be dynamically rotated without losing established network connections. If IPv6 is to be globally deployed, it must not provide additional attack vectors that expose user information. / Ph. D.