The conventional techniques of manufacturing large-size structures in a very large plate pose severe challenges in making microstructures. In contrast, semiconductor process that employs lithographic processes to form micro scale features is limited in its wafer size. In ordre to modify the defeat of shadow mask. This thesis propose to use TMAH anisotropic wet etching process and 2D- joining technique to fabricate silicon shadow mask. The potential of this technique would be significant for a very large plate beyond a wafer size with microstructures, and provides a new approach with a high replication and potentially low cost. In the numerical analysis, this study uses the finite element software, ANSYS, to simulate shadow mask with different size, material, and temperature displacement situation. The results shows the feasibility of silicon shadow mask used in the thermal evaporation process. It indicates that this design could have smoother pattern and reduce the limitation of Organic Light-Emitting Diode resolution.

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Thesis (Ph. D.)--University of Hong Kong, 1989.

Thesis (Ph. D. in Mechanical Engineering)--Naval Postgraduate School, June 2003. / Dissertation supervisor: Ashok Gopinath. Includes bibliographical references (p. 162-164). Also available online.

The first part of this thesis is devoted to a regularity criterion for solutions of the Incompressible Navier-Stokes equations in terms of regularity of the solutions along the streamlines. More precisely, we prove that we can ensure the full regularity of a given suitable weak solution provided we have good control on the second derivative of the velocity along the direction of the streamlines of the fluid. In the second part of this thesis, we will show that the global regularity of a suitable weak solution u for the incompressible Navier-Stokes equations holds under the condition that [mathematical equation] is integrable in space time variables. / text

As technological advances throughout the field of satellite geodesy improve the accuracy of satellite measurements, numerical methods and algorithms must be able to keep pace. This becomes increasingly important for high precision applications, such as high degree/order gravity field recovery. Currently, the Gravity Recovery and Climate Experiment's (GRACE) dual one-way microwave ranging system can determine changes in inter-satellite range to a precision of a few microns; however, with the advent of laser measurement systems nanometer precision ranging is a realistic possibility. With this increase in measurement accuracy, a reevaluation of the accuracy inherent in the numerical integration algorithms is necessary. This study attempts to quantify and minimize these numerical errors in an effort to improve the accuracy of modeling and propagation of various orbital perturbations; helping to provide further insight into the behavior and evolution of the Earth's gravity field from the more capable gravity missions in the future. The numerical integration errors are examined for a variety of satellite accelerations. The propagation of orbits similar to those of the GRACE satellites using a gravitational model that assumes the Earth is a perfect sphere show integration errors, using double precision numerical representations, on the order of 1 micron in inter-satellite range and 0.1 nanometers per second in inter-satellite range-rate. In addition, when the Earth's gravitational field is formulated in spherical harmonics these numerical integration errors begin to contaminate signals to due harmonics approximately above degree 220, for an orbit at GRACE altitudes. Also, when examining the effect of mass anomalies on the Earth's surface, simulated as point masses, it is apparent that numerical integration methods are easily capable of resolving point mass anomalies as small as 0.05 gigatonnes. Finally, a numerical integration procedure is determined to accurately simulate the effect of numerous, small step accelerations applied to the satellite's center of mass due to misalignment and misfiring of the attitude thrusters. Future studies can then use this procedure as a metric to evaluate the accuracy and effectiveness of an accelerometer in reproducing these non-gravitational forces and how these errors might affect gravity field recovery. / text

In this dissertation, we study a free boundary problem obtained as a limit as [epsilon omplies 0] to the following regularizing family of semilinear equations [Delta]u = [Beta subscript epsilon](u)F([gradient]u), where [Beta subscript epsilon] approximates the Dirac delta in the origin and F is a Lipschitz function bounded away from 0 and infinity. The least supersolution approach is used to construct solutions satisfying geometric properties of the level surfaces that are uniform. This allows to prove that the free boundary of the limit has the "right" weak geometry, in the measure theoretical sense. By the construction of some barriers with curvature, the classification of global profiles for the blow-up analysis is carried out and the limit function is proven to be a viscosity and pointwise solution (a.e) to a free boundary problem. Finally, the free boundary is proven to be a C[superscript 1, alpha] surface around H[superscript n-1] a.e. point.

Binary black hole mergers are the strongest expected producers of graviational radiation in the universe. Ground-based and proposed space-based gravitational wave detectors will benefit from simulations modeling the mergers and extracting the resulting gravitational waveforms. Producing templates of waveforms will both aid the likelihood of detection and the estimation of parameters (mass ratio, spin, etc.). openGR is modular, open framework development to carry out simulations of binary black hole mergers. While designed with the two-body problem in mind, openGR will evolve most general spacetimes. This work overviews the capabilities of openGR and the corresponding physics involved. openGR supports both excision and puncture methods. When excising the black hole, to date we have used only the weakly hyperbolic ADM formulation of the Einstein’s equations. As expected from a weakly hyperbolic system, instabilites arise and crash the code when simulating even just a single boosted black hole in Kerr-Schild coordinates. In contrast, successful mergers of two black holes have been achieved using the puncture method. We demonstrate such a simulation in Ch 8. In this case, we make use of a BSSN formulation of Einstein’s equations (a strongly hyperbolic system). / text

published_or_final_version / Mathematics / Master / Master of Philosophy

published_or_final_version / Mechanical Engineering / Master / Master of Philosophy