Global ETD Search

11	Mortuary practices and territoriality : archaic hunter-gatherers of southern Texas and the Loma Sandia Site (41LK28) / Taylor, A. J. January 1998 (has links) Thesis (Ph. D.)--University of Texas at Austin, 1998. / Vita. Includes bibliographical references (leaves 164-198). Available also in a digital version from Dissertation Abstracts.
12	Design and Finite Element Modeling of a MEMS‐scale Aluminum Nitride (AlN) EnergyHarvester with Meander Spring Feature Zula, Daniel Peter 28 August 2019 (has links) No description available. Electrical Engineering
13	Seamless Level 2 / Level 3 Probabilistic Risk Assessment Using Dynamic Event Tree Analysis Osborn, Douglas M. 29 August 2013 (has links) No description available. Nuclear Engineering Probabilistic Risk Assessment Dynamic PRA MELCOR MACCS MACCS2 Dynamic Event Tree DET Uncertainty Nuclear SOARCA Severe Reactor Accident Station Blackout SBO Sandia National Laboratories Nuclear Regulatory Commission NRC SNL
14	Transient And Distributed Algorithms To Improve Islanding Detection Capability Of Inverter Based Distributed Generation Al Hosani, Mohamed 01 January 2013 (has links) Recently, a lot of research work has been dedicated toward enhancing performance, reliability and integrity of distributed energy resources that are integrated into distribution networks. The problem of islanding detection and islanding prevention (i.e. anti-islanding) has stimulated a lot of research due to its role in severely compromising the safety of working personnel and resulting in equipment damages. Various Islanding Detection Methods (IDMs) have been developed within the last ten years in anticipation of the tremendous increase in the penetration of Distributed Generation (DG) in distribution system. This work proposes new IDMs that rely on transient and distributed behaviors to improve integrity and performance of DGs while maintaining multi-DG islanding detection capability. In this thesis, the following questions have been addressed: How to utilize the transient behavior arising from an islanding condition to improve detectability and robust performance of IDMs in a distributive manner? How to reduce the negative stability impact of the well-known Sandia Frequency Shift (SFS) IDM while maintaining its islanding detection capability? How to incorporate the perturbations provided by each of DGs in such a way that the negative interference of different IDMs is minimized without the need of any type of communication among the different DGs? It is shown that the proposed techniques are local, scalable and robust against different loading conditions and topology changes. Also, the proposed techniques can successfully distinguish an islanding condition from other disturbances that may occur in power system networks. This work improves the efficiency, reliability and safety of integrated DGs, which presents a necessary advance toward making electric power grids a smart grid. Algorithms amplitude estimation distributed algorithm distributed energy resources distributed generation dynamic estimator inverter based distributed generation islanding islanding detection methods non detection zone non linear observer over/under frequency protection over/under voltage protection point of common coupling quality factor sandia frequency shift scheduled perturbation stiffness transient response Electrical and Computer Engineering Electrical and Electronics Engineering
15	Development and assessment of CFD models including a supplemental program code for analyzing buoyancy-driven flows through BWR fuel assemblies in SFP complete LOCA scenarios Artnak, Edward Joseph 31 January 2013 (has links) This work seeks to illustrate the potential benefits afforded by implementing aspects of fluid dynamics, especially the latest computational fluid dynamics (CFD) modeling approach, through numerical experimentation and the traditional discipline of physical experimentation to improve the calibration of the severe reactor accident analysis code, MELCOR, in one of several spent fuel pool (SFP) complete loss-of-coolant accident (LOCA) scenarios. While the scope of experimental work performed by Sandia National Laboratories (SNL) extends well beyond that which is reasonably addressed by our allotted resources and computational time in accordance with initial project allocations to complete the report, these simulated case trials produced a significant array of supplementary high-fidelity solutions and hydraulic flow-field data in support of SNL research objectives. Results contained herein show FLUENT CFD model representations of a 9x9 BWR fuel assembly in conditions corresponding to a complete loss-of-coolant accident scenario. In addition to the CFD model developments, a MATLAB based control-volume model was constructed to independently assess the 9x9 BWR fuel assembly under similar accident scenarios. The data produced from this work show that FLUENT CFD models are capable of resolving complex flow fields within a BWR fuel assembly in the realm of buoyancy-induced mass flow rates and that characteristic hydraulic parameters from such CFD simulations (or physical experiments) are reasonably employed in corresponding constitutive correlations for developing simplified numerical models of comparable solution accuracy. / text CFD CFD Model Buoyancy driven flow Buoyancy flow FLUENT FLUENT CFD SNL Sandia National Laboratories SFP LOCA Spent fuel pool loss of coolant accident SFP loss of coolant BWR fuel assembly CAD Model SolidWorks SFP Model SFP BWR fuel assembly NRC MATLAB MATLAB SFP Model 9x9 BWR fuel assembly MELCOR MELCOR SFP 250 million cells Hydraulic flow loss Loss coefficients Buoyancy flows MELCOR calibration Pressure loss BWR pressure loss SFP airflow SNL fuel assembly

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