acase@tulane.edu / In the present study a few approaches are developed for theoretical investigation of vibrational energy propagation in highly ordered polymers and linear atomic chains. Density matrix formalism applied to explain the transition between ballistic and diffusive regimes in polymers, the diffusive and ballistic regimes of energy transport are described in terms of asymptotic limits of exact solution of Liouville-Bloch equation. Energy bands theory is developed for oligomeric structures such as perfluoroalkane and alkane compounds, as an example, practical application for understanding experimental data for alkane is discussed. Also, purely electronic torsional mode in linear atomic chains, such as cumulene, is considered. The speed of up to 1000~km/s for electronic sound is predicted, the spectrum of quanta (torsitons) of torsional electronic mode in cumulene is obtained. / 1 / Arkady Kurnosov

Studying the vibrational energy transfer pathways and dynamics in molecules is important for different areas of chemical research, with the range of potential applications in nanotechnology, organic chemistry and biochemistry. Two transport regimes, ballistic and diffusive, are recognized for the transport in molecules; while the latter is typically slow the former can be fast and efficient. The diffusive transport regime was observed in numerous compounds, whereas there are only a few cases where the ballistic transport has been suggested in molecules. The subject of this dissertation is to identify the factors influencing the ballistic transport, including the molecular chain organization, thermodynamic conditions and end-group functionalities. The research involves several types of oligomeric chains, such as polyethyleneglycol, perfluoroalkane, and alkane chains. The experiments were performed using the relaxation-assisted two-dimensional infrared spectroscopy method, which permits measuring the energy transport time between two vibrating groups. The transport via all three chain types was found to occur with a constant speed, although different speeds were found in different chain types. The fastest speed of 14.4 Å/ps was found in linear alkanes, the slowest, 3.9 Å/ps, in perfluoroalkanes. The difference in the transport speed was attributed to involvement of different chain optical bands. The temperature dependence of the transport speed and efficiency in perfluoroalkanes demonstrated that the ballistic transport, dominating at low temperatures, is switched to the diffusive transport at elevated temperatures; the observation was supported by the theoretical modeling. The energy transport in several compounds lacking periodic structure was found to occur with an effective speed of 1.2-1.4 Å/ps, which approximately matches the speed of passing one bond-length per mean lifetime of the excited vibrational mode (1 ps). This speed was found to be 3-10 fold smaller than the transport speed via oligomeric chains. Moreover both regimes, diffusive and ballistic, were distinguished within the same compound: the transport was ballistic via the chain and diffusive within the bulky end group. The two transport times were found additive, confirming the ballistic nature of the through-chain transport. This study develops a detailed picture of energy transport in molecules and provides new opportunities for designing molecular and nanoscale materials with tailored energy transport properties, potentially useful for making novel elements for molecular electronics. / 1 / Natalia I. Rubtcova

Thesis--School of Advanced Airpower Studies, Maxwell Air Force Base, Ala., 1997-98. / Title from title screen (viewed Oct. 28, 2003). "September 1999." Includes bibliographical references.

Thesis [M.H. Miklaski]-(M.S. in Systems Technology) and (M.S. in Software Engineering)--Naval Postgraduate School, December 2003. Thesis [J.D. Babbitt]-(M.S. in Computer Science)--Naval Postgraduate School, December 2003. / Thesis advisor(s): Man-Tak Shing, James Bret Michael. Includes bibliographical references (p. 287-289). Also available online.

No description available.

Thesis (Ph. D.)--Virginia Polytechnic Institute and State University, 1992. / Abstract. Includes bibliographical references (leaves 73-74). Also available via the Internet.

Thesis (M.S. in Mechanical Engineering)--Naval Postgraduate School, September 2009. / Thesis Advisor(s): Chandrasekhara, Muguru. "September 2009." Author(s) subject terms: Missile Aerodynamics, Missile DATCOM, Missilelab, SA-2 Missile. Description based on title screen as viewed on Nov. 5, 2009. Includes bibliographical references (p. 57-58). Also available in print.

Thesis (M.S. in Electrical Engineering and M.S. in Systems Engineering)--Naval Postgraduate School, 2004. / Title from title screen (viewed June 20, 2005). "September 2004." Includes bibliographical references (p. 139-140). Also issued in paper format.

Thesis (M.A. in Security Studies (Civil-Military Relations)--Naval Postgraduate School, Sept. 2004. / Thesis Advisor(s): Harold A. Trinkunas. Includes bibliographical references (p. 87-88). Also available online.

With the increasing number of small Uncrewed Aerial Systems (sUAS) in the airspace, the need for robust Detect and Avoid (DAA) technologies is clear. This is especially true when considering the potential for non-cooperative aircraft with unknown intent. Many UAS use high resolution cameras to perform omnidirectional scans of their nearby airspace to localize traffic. These scans can be quite computationally expensive and often necessitate the use of costly and heavy hardware components. Ground-based solutions such as centralized, stationary towers are often expensive, difficult to proliferate, and have the disadvantage of not being onboard the aircraft and as such not always local to the airspace conflict. A feasibility exploration of acoustic detection and localization of non-cooperative aircraft using a low-cost microphone array, computationally inexpensive beamforming algorithms, and filtering techniques, is performed. The cost of the system is minimized by utilizing widely proliferated microphone hardware originally designed for short-range voice detection, as well as a small Uncrewed Aerial Systems (sUAS) from a developmental kit. Lastly, an exploration is conducted to maximize the detection range of the microphone system. A comparison of filtering techniques to try to filter sUAS self-noise is compared to alternative methods such as a ballistic sampling period where the motors of the sUAS are momentarily turned off to reduce noise. A final recommendation of a multi-sensor suite of microphones, cameras, along with other potential sensors, is determined. / Master of Science / As the number of drones increases throughout many industries, safe usage becomes very important. Industries such as search and rescue, infrastructure surveying, package delivery, and more, all have novel uses for drones that could change the way those industries operate. It is easy to imagine the benefit of same-day shipping with package-carrying drones, the quick location of a missing person by a search and rescue drone, and so on. However, obstacles such as buildings, trees, and other air traffic pose an obvious risk. Current methods to detect other aircraft often rely on cameras onboard the aircraft to spot nearby traffic. Other methods include using centralized stations on the ground to relay information about positioning between cooperating aircraft. These technologies provide functionality, but often can be expensive, heavy, require computers with large processing power, or assume the cooperation of the aircraft. An analysis of audio based detection of nearby drones is conducted. The microphones used were originally intended for use in home applications as a voice assistant. Programming techniques were used to listen and identify the sound of a nearby drone. Depending on the location of the drone, its sound would arrive to the microphones in unique time delays, providing a method of estimating the drone's position. Testing was performed on the ground and in the air to analyze the distance at which this microphone group could find a drone. Ultimately, a recommendation for the inclusion of microphones in a suite of sensors was made.