Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Aeronautics and Astronautics, 2007. / This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections. / Includes bibliographical references (leaves 67-70). / Electrospray propulsion devices with externally wetted architectures have shown favorable performance. The design of microfabricated silicon thrusters and their feed systems requires an understanding of propellant flow over a silicon surface. This research explores the parameters that affect wettability of externally wetted microfabricated silicon electrospray thruster arrays and how varied wetting surface treatments affect thruster performance. Silicon samples with various black silicon treatments were fabricated and optimal black silicon etch parameters were determined by measuring the samples wettability. Silicon wettability was analyzed by producing samples with various black silicon treatments and then measuring contact angle, measuring surface roughness, imaging surface geometry, calculating spreading rates, and performing treated thruster current output tests. Two propellants, 1-ethyl-3-methyl-imidazolium tetraflouroborate (EMI-BF4) and 1-ethyl-3-methyl-imidazolium bis(triflouromethyl-sulfonyl)amide (EMI-IM), were used in contact angle measurements and spreading rate experiments. A model describing the spread of a small drop of EMI-BF4 and EMI-IM over roughened silicon substrates is presented. / (cont.) Models which describe the spread of small, non-reactive drops over perfectly smooth substrates predicts a 1/5th power dependence of spreading area with time. Experimental spreading data of EMI-BF4 loosely supported this theory showing an average of 1/3rd power dependence of spread area with time. A model of propellant spreading is proposed here suggesting that viscous spreading reaches an equilibrium with constant radius and provides a capillary pressure source for porous flow through the black silicon surface for the remainder of the spreading. This theory is compared with experimental data of EMI-BF.K and EMI-IM propellant spread over roughened silicon. Future work in propellant supply to a thruster surface is discussed. Theoretical and experimental areas of study are proposed to understand physical flow mechanisms involved in electrospray thrusters. / by Tanya Cruz Garza. / S.M.

Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Aeronautics and Astronautics, 1993. / Includes bibliographical references (leaves 57-60). / by Soomyung Yoo. / M.S.

Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Aeronautics and Astronautics, 2001. / Includes bibliographical references (p. 143-146). / by Alissa Naomi Clawson. / S.M.

Thesis: Ph. D., Massachusetts Institute of Technology, Department of Aeronautics and Astronautics, 2016. / This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections. / Cataloged from student-submitted PDF version of thesis. / Includes bibliographical references (pages 139-146). / Many of today's critical infrastructures are organized in the form of networks, which are dependent on one another. A particular example is the power grid and the communication network used to control the grid. While this dependence is beneficial during normal operation, as it allows for more efficient operation, it can be harmful when the networks are under stress. Indeed, in such interdependent network infrastructures, a cascade of failures may occur where power failures can lead to communication failures, which, in turn, lead to cascading power failures. Therefore, it is necessary to develop proper models and analytical tools to asses the robustness of interdependent networks to failures. In this thesis, we develop such models with emphasis on interdependent power grids and communication networks. Initially, we focus on the abstract modeling of interdependent networks. In particular, we propose a new model for interdependent networks with known topologies, define and analyze metrics for assessing the robustness of such networks to cascading failures, and propose algorithms for robust design of interdependent networks. Next, we focus on the interactions between power grids and communication and control networks. We model the cascading failures in the power grid using the power flow equations, and use the communication network to implement a control policy in the power grid which mitigates cascading failures in interdependent networks. Using this model, we show that the interdependent power grids are more robust than isolated ones. Finally, we model the impact of communication loss on the performance of power grids under two different control scenarios. The first one is the emergency control mechanism where failures in the power grid should be monitored and mitigated by the control center. In this case, we investigate the impact of simultaneous communication failures on the performance of such control mechanisms. In particular, we propose new emergency control schemes for partial communication networks, and investigate the network parameters that are most effective in causing the cascade of failures from communication networks to the power grid. The second control mechanism is distributed frequency control in power grids. We show that the optimal solution will not be achieved under communication link failures. We propose a novel control mechanism that uses the power dynamics instead of direct information from the communication network, and show that it achieves the optimal solution and is globally asymptotically stable. We also analyze the impact of discrete-time communication on the performance of distributed frequency control. We show that the convergence time increases as the time interval between two messages increases, and propose a new algorithm that uses the dynamics of the power grid to decrease the convergence time. / by Marzieh Parandehgheibi. / Ph. D.

Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Aeronautics and Astronautics, 1995. / Includes bibliographical references (p. [239]-250). / by Michael David Violet. / M.S.

Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Aeronautics and Astronautics, 1995. / Includes bibliographical references (p. 237-246). / by Robie I. Samanta Roy. / Ph.D.

Massachusetts Institute of Technology. Dept. of Aeronautics and Astronautics. Thesis. 1970. Sc.D. / MICROFICHE COPY ALSO AVAILABLE IN AERONAUTICS LIBRARY. / Vita. / Bibliography: p. 143-145. / Sc.D.

Massachusetts Institute of Technology. Dept. of Aeronautics and Astronautics. Thesis. 1967. Sc.D. / MICROFICHE COPY ALSO AVAILABLE IN AERONAUTICS LIBRARY. / Vita. / Bibliography: p. 120-122. / Sc.D.

Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Aeronautics and Astronautics, 1989. / Includes bibliographical references (leaves 86-87). / by Stephane Lucien Mondoloni. / M.S.

Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Aeronautics and Astronautics, 1990. / Includes bibliographical references (leaves 183-188). / by Narendra Venugopal Bhat. / M.S.