http://hdl.handle.net/1721.1/7818 2013-05-20T05:53:46Z http://hdl.handle.net/1721.1/75454 Design and fabrication of a MEMS-array pressure sensor system for passive underwater navigation inspired by the lateral line Hou, Stephen Ming-Chang, 1981- An object within a fluid flow generates local pressure variations that are unique and characteristic to the object's shape and size. For example, a three-dimensional object or a wall-like obstacle obstructs flow and creates sharp pressure gradients nearby. Similarly, unsteady flow contains vortical patterns with associated unique pressure signatures. Detection of obstacles, as well as identification of unsteady flow features, is required for autonomous undersea vehicle (AUV) navigation. An array of passive underwater pressure sensors, with their ability to An object within a fluid flow generates local pressure variations that are unique and characteristic to the object's shape and size. For example, a three-dimensional object or a wall-like obstacle obstructs flow and creates sharp pressure gradients nearby. Similarly, unsteady flow contains vortical patterns with associated unique pressure signatures. Detection of obstacles, as well as identification of unsteady flow features, is required for autonomous undersea vehicle (AUV) navigation. An array of passive underwater pressure sensors, with their ability to "touch at a distance" with minimal power consumption, would be able to resolve the pressure signatures of obstacles in the near field and the wake of objects in the intermediate field. As an additional benefit, with proper design, pressure sensors can also be used to sample acoustic signals as well. Fish already have a biological version of such a pressure sensor system, namely the lateral line organ, a spatially-distributed set of sensors over a fish's body that allows the fish to monitor its hydrodynamic environment, influenced by the external disturbances. Through its ability to resolve the pressure signature of objects, the fish obtains "hydrodynamic pictures". Inspired by the fish lateral line, this thesis describes the development of a high-density array of microelectromechanical systems (MEMS) pressure sensors built in KOH-etched silicon and HF-etched Pyrex wafers. A novel strain-gauge resistor design is discussed, and standard CMOS/MEMS fabrication techniques were used to build sensors based on the strain-gauge resistors and thin silicon diphragms. Measurements of the diaphragm deflection and strain-gauge resistance changes in response to changes in applied external pressure confirm that the devices can be reliably calibrated for use as pressure sensors to enable passive navigation by AUVs. A set of sensors with millimeter-scale spacing, 2.1 to 2.5 [mu]V/Pa sensitivity, sub-pascal pressure resolution, and -2000 Pa to 2000 Pa pressure range has been demonstrated. Finally, an integrated circuit for array processing and signal amplification and to be fabricated with the pressure sensors is proposed. Thesis (Elec. E.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2012.; 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 (p. 233-241). 2012-01-01T05:00:00Z http://hdl.handle.net/1721.1/71512 Defeating eavesdropping with quantum illumination Xu, Wenbang Quantum illumination is a paradigm for using entanglement to gain a performance advantage-in comparison with classical-state systems of the same optical power-over lossy, noisy channels that destroy entanglement. Previous work has shown how it can be used to defeat passive eavesdropping on a two-way Alice-to-Bob-to-Alice communication protocol, in which the eavesdropper, Eve, merely listens to Alice and Bob's transmissions. This thesis extends that work in several ways. First, it derives a lower bound on information advantage that Alice enjoys over Eve in the passive eavesdropping scenario. Next, it explores the performance of alternative practical receivers for Alice, as well as various high-order modulation formats for the passive eavesdropping case. Finally, this thesis extends previous analysis to consider how Alice and Bob can minimize their vulnerability to Eve's doing active eavesdropping, i.e., when she injects her own light into the channel. Thesis (Elec. E.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2012.; Cataloged from PDF version of thesis.; Includes bibliographical references (p. 77-79). 2012-01-01T05:00:00Z http://hdl.handle.net/1721.1/71275 Structured decomposition of adaptive applications Paluska, Justin Mazzola, 1981- We describe an approach to automate certain high-level implementation decisions in a pervasive application, allowing them to be postponed until run time. Our system enables a model in which an application programmer can specify the behavior of an adaptive application as a set of open-ended decision points. We formalize decision points as Goals, each of which may be satisfied by a set of scripts called Techniques. The set of Techniques vying to satisfy any Goal is additive and may be extended at runtime without needing to modify or remove any existing Techniques. Our system provides a framework in which Techniques may compete and interoperate at runtime in order to maintain an adaptive application. Technique development may be distributed and incremental, providing a path for the decentralized evolution of applications. Benchmarks show that our system imposes reasonable overhead during application startup and adaptation. Thesis (Elec. E. in Computer Science)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2012.; 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 (p. 57-58). 2012-01-01T05:00:00Z http://hdl.handle.net/1721.1/69772 Efficient silicon micro-reactors for thermophotovoltaic applications Araghchini, Mohammad Thermophotovoltaic (TPV) systems passively generate electricity from the combustion of fuel. Although TPV conversion systems have advantages, they suffer from low efficiency. This thesis investigates different ways to increase the efficiency of TPV systems. In particular the thesis details micro-fabrication of silicon micro-reactors, and twodimensional tungsten photonic crystals (2D W PhC) for high-temperature applications such as selective thermal emitters for TPV energy conversion. Interference lithography and reactive ion etching are used to produce large-area single-crystal tungsten 2D PhC's. The fabricated PhC consists of an array of cylindrical cavities with 800nm diameter, 1.2 pm depth, and 1.2 pm period. Extensive characterization and calibration of all micro-fabrication steps for both micro-reactors and 2D PhC's are presented. Experimentally-obtained thermal emission spectra of the 2D PhC structures match well with numerical predictions. Thesis (Elec.E.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2011.; Cataloged from PDF version of thesis.; Includes bibliographical references (p. 61-63). 2011-01-01T05:00:00Z