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Direct Cooled Ceramic Substrate For Thermal Control Of Automotive Power Electronics, Kirk Townsend Lowe

Doctoral Dissertations

As electric vehicle technology develops, manufacturers would like to move toward hotter coolants for power electronic components to reduce system level costs. Thus, unique designs of inverter designs were sought to enable operation with 105°C coolant. The proposed solution in this research incorporated flow channels into the ceramic layer of the direct-bonded copper substrate typically found in power electronic packages. The focus of this research details the design and analysis of the direct cooled ceramic substrate from the perspective of its thermal performance and innovative packaging concept.

The research was directed to pursue alumina as the substrate ceramic because of …

Computational Investigations Of Characteristic Performance Improvements For Subkilogram Laser Micropropulsion, Richard Joel Thompson

Masters Theses

Experimental investigations have evaluated the feasibility of using laser-driven plasma microthrusters for small-thrust, high-specific-impulse space maneuvers, particularly for micro- and nanosatellite missions. Recent work made use of the Mach2 hydromagnetics code for the construction of an adequate computational model of the micro-thruster opera- tion. This thesis expounds on this previous work by extending the computational modeling capabilities, allowing for the determination of plasma plume properties and characteristic performance assessment of the microthruster; this allows for further computational investi- gation of the performance improvements achieved by new design considerations. Two par- ticular design changes are implemented and measured: (i) the simulation …

Unique Characteristics Of Liquid Metal Extended Meniscus Evaporation, Joseph Brown Tipton, Jr.

Doctoral Dissertations

The research in this dissertation addresses the steady evaporation of a capillary pore with a liquid metal working fluid. First, the interline region of an extended meniscus thin film is considered for the unique physical case of a liquid metal. A new thin film evaporation model is presented that captures the unsimplified dispersion force along with an electronic disjoining pressure component that is unique to liquid metals. The resulting nonlinear 4th-order ODE is solved using an implicit orthogonal collocation technique along with the Levenberg-Marquardt method. Results show that the electronic component of the disjoining pressure should be considered when modeling …

Production And Optimization Of Continuous Roving-Like Utsi Pitch Based Carbon Fiber Composites, Matthew P. Duran

Masters Theses

UTSI has developed a new low-cost jet-dry-spin method for the production of mesophase pitch-based carbon fibers. The objective of this preliminary study is to optimize the production of the UTSI carbon fiber composites and to better understand the surface texture between the fiber and matrix material. Several fabrication techniques were studied with varied preparation conditions to determine the effects on apparent density, electrical resistivity, tensile and flexural properties. Various polymeric resins and hardeners were used to demonstrate the versatility of the application of UTSI carbon fibers. During these investigations various analysis techniques including Scanning Electron Microscopy (SEM), x-ray diffraction, and …

A Shooting Algorithm For Complex Immunodominance Control Problems, Xiaopeng Zhao, R Yang, M Zhang

Faculty Publications and Other Works -- Mechanical, Aerospace and Biomedical Engineering

Although T cells are able to recognize a wide variety of target peptides, they are often strongly focused on a few of the peptides and leave the rest of them unattended. This phenomenon of strongly biased immune response is known as immunodominance. Mathematically, an immunodominance problem can be formulated using optimal control principles as a two-point boundary-value problem. The solution of this problem is challenging especially when the control variables are bounded. In this work, we develop a numerical algorithm based on the shooting technique for bounded optimal control problems. The algorithm is applied to a group of immunodominance problems. …