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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Unbiased Filtered Rayleigh Scattering Measurement Model for Aerodynamic Flows

Warner, Evan Patrick 17 December 2024 (has links)
The filtered Rayleigh scattering (FRS) optical diagnostic has become an attractive technique for advanced aerodynamic measurements. The appeal of FRS is that it can simultaneously quantify density, temperature, and vector velocity. Additionally, it is entirely non-intrusive to the flow since the technique leverages how laser light scatters off of molecules naturally present in the gas. Acquired FRS data considered herein is in the form of a frequency spectrum. To process this data, a measurement model for the FRS spectrum is used, where inputs to this model are the flow field quantities of interest and the output is a representative FRS spectrum. An iterative procedure on these quantities is performed until the model spectrum matches the measured spectrum. However, as observed in certain applications of this technique, there is a range of measurement configurations where the standard methods to model this spectrum do not agree with measured spectra, even at known flow conditions. This disagreement causes large bias uncertainties in determined flow field quantities. This work leverages a data-driven approach to diagnose this disagreement by utilizing an extensive FRS database. Data analysis indicates that the widely used Tenti S6 model for the Rayleigh scattering lineshape is invalid in certain operating regions. A new Rayleigh lineshape modeling methodology, the Cabannes model, is introduced that vastly improves the agreement between measured and modeled FRS signals. Analysis of the Cabannes model indicates that one only needs to use this modeling methodology for FRS and not laser Rayleigh scattering (LRS). This improved measurement model can be used to mitigate bias uncertainties, and, in turn, improve the reliability of the FRS optical instrument. / Doctor of Philosophy / The filtered Rayleigh scattering (FRS) laser-based measurement technique has become an attractive tool for aerodynamic measurements. Leveraging the theory of Rayleigh scattering, measuring how laser light scatters off of air molecules can be used to determine the temperature, density, and velocity of the air. A specific combination of temperature, density, and velocity results in a unique, measured FRS signal. A computational model of this FRS signal is then used to go from FRS signal to those three quantities of interest. However, as observed by certain applications of this technique, there is a certain range of measurement cases where the standard methods to model this signal do not agree with measured signals at known values for temperature, density, and velocity of the air. This disagreement between modeled and measured signals causes large errors, and, therefore, decreases the reliability of this measurement for those cases. This work analyzes an extensive FRS database to determine the source of this disagreement. The conclusion from this data analysis is that the widely used computational model in the community is not correct for certain applications of this FRS measurement. A new method to model FRS signals is proposed in this work, which vastly improves the agreement between measured and modeled signals. This improved computational model can be used to remove the large errors seen in this FRS measurement system that were previously caused by modeling errors. This, in turn, will improve the reliability of this technique across the whole application space of applied aerodynamic measurements.
2

Uplatnění energie obnovitelných zdrojů v budovách / The application of renewable energy in buildings

Panovec, Jan January 2015 (has links)
The aim of this diploma thesis is to understand the functioning of heating and cooling systems in an administrative building built in passive standard using a renewable energy source. The thesis includes theoretical findings of heat pumps and designing the heating systems. The experimental part contains an analysis of working of heating and cooling systems in selected rooms in assigned building, which includes an experimental measurement of selected quantities and a thermographic measurement. In the last part of the thesis a comparison of measured and simulated values using simulation software was done.
3

Metodologia para estimação de estado trifásica em sistemas de distribuição incorporando medidas SCADA, virtuais, pseudo-medidas e medidas fasoriais sincronizadas / Three-phase distribution system state estimation methodology incorporating SCADA, virtual, pseudo-measurements and synchronized phasor measurements

Fantin, Camila dos Anjos 28 November 2016 (has links)
Este trabalho propõe o desenvolvimento e implantação, em computador, de uma metodologia para tratamento de diversas etapas do processo de estimação de estado em Sistemas de Distribuição (SDs), que possibilite um tratamento adequado para as particularidades dos SDs no contexto atual (com poucas medidas disponíveis) e futuro (contando com mais medidas SCADA, com as Medidas Fasoriais Sincronizadas (MFSs) e com as avançadas infra-estruturas de medição), ou seja, que possibilite: análise de sistemas desbalanceados e desequilibrados, com ramais monofásicos, bifásicos e trifásicos; o tratamento de sistemas radiais e malhados sem perda de precisão; uma modelagem adequada dos componentes dos SDs, considerando as várias possibilidades de conexão dos transformadores e dos reguladores de tensão; o tratamento de diversos tipos de medidas (medidas convencionais obtidas pelo sistema SCADA, medidas virtuais, pseudo-medidas de carga e de dados históricos e MFSs), ponderando-as de acordo com as respectivas precisões. A metodologia proposta baseia-se no método dos mínimos quadrados ponderados, trabalha no nível dos alimentadores e compreende os seguintes quatro estágios: Estágio 1 geração de pseudo-medidas de carga; Estágio 2 - análise e restauração de observabilidade e identificação de medidas críticas; Estágio 3 - estimação de estado propriamente dita; e Estágio 4 - processamento de erros grosseiros. Tendo em vista as respostas coerentes das diversas simulações realizadas com os alimentadores de teste trifásicos de 4 e 34 barras do IEEE, demonstra-se satisfatoriamente a performance da metodologia proposta. / This thesis proposes a multi-phase unbalanced distribution system (DS) state estimation methodology based on the weighted least squares technique, which allows: load pseudo-measurement modeling; observability analysis and restoration by selecting the required pseudo-measurements (load pseudo-measurements and/or historical measurement data); identication of critical measurements; state estimation; and, nally, gross errors processing. The proposed methodology intends to be a practical tool able to be applied to a variety of DSs, considering latest and future realities. Therefore, the proposed methodology has the following features: (i) includes all realistic DS modeling details, such as, various types of transformer and voltage regulator connections, the presence of single, two and three-phase circuits, as well as the possibility of both the mutual coupling between phases and the shunt susceptance; (ii) treat three-phase networks with high resistance/reactance ratios in a unied framework; and (iii) process measurements with very distinct qualities, some of them are real-time measurements provided by Supervisory Control Data Acquisition (SCADA) systems, Advanced Metering Infrastructure (AMI), Phasor Measurement Units (PMUs), other are virtual measurements (information provided by the buses of zero power injection) and also the pseudo-measurements (load pseudo-measurements, load proles and historical measurement data). Several simulations results (with IEEE 34 and 4 node test feeders) have demonstrated satisfactory performance of the proposed methodology.
4

Metodologia para estimação de estado trifásica em sistemas de distribuição incorporando medidas SCADA, virtuais, pseudo-medidas e medidas fasoriais sincronizadas / Three-phase distribution system state estimation methodology incorporating SCADA, virtual, pseudo-measurements and synchronized phasor measurements

Camila dos Anjos Fantin 28 November 2016 (has links)
Este trabalho propõe o desenvolvimento e implantação, em computador, de uma metodologia para tratamento de diversas etapas do processo de estimação de estado em Sistemas de Distribuição (SDs), que possibilite um tratamento adequado para as particularidades dos SDs no contexto atual (com poucas medidas disponíveis) e futuro (contando com mais medidas SCADA, com as Medidas Fasoriais Sincronizadas (MFSs) e com as avançadas infra-estruturas de medição), ou seja, que possibilite: análise de sistemas desbalanceados e desequilibrados, com ramais monofásicos, bifásicos e trifásicos; o tratamento de sistemas radiais e malhados sem perda de precisão; uma modelagem adequada dos componentes dos SDs, considerando as várias possibilidades de conexão dos transformadores e dos reguladores de tensão; o tratamento de diversos tipos de medidas (medidas convencionais obtidas pelo sistema SCADA, medidas virtuais, pseudo-medidas de carga e de dados históricos e MFSs), ponderando-as de acordo com as respectivas precisões. A metodologia proposta baseia-se no método dos mínimos quadrados ponderados, trabalha no nível dos alimentadores e compreende os seguintes quatro estágios: Estágio 1 geração de pseudo-medidas de carga; Estágio 2 - análise e restauração de observabilidade e identificação de medidas críticas; Estágio 3 - estimação de estado propriamente dita; e Estágio 4 - processamento de erros grosseiros. Tendo em vista as respostas coerentes das diversas simulações realizadas com os alimentadores de teste trifásicos de 4 e 34 barras do IEEE, demonstra-se satisfatoriamente a performance da metodologia proposta. / This thesis proposes a multi-phase unbalanced distribution system (DS) state estimation methodology based on the weighted least squares technique, which allows: load pseudo-measurement modeling; observability analysis and restoration by selecting the required pseudo-measurements (load pseudo-measurements and/or historical measurement data); identication of critical measurements; state estimation; and, nally, gross errors processing. The proposed methodology intends to be a practical tool able to be applied to a variety of DSs, considering latest and future realities. Therefore, the proposed methodology has the following features: (i) includes all realistic DS modeling details, such as, various types of transformer and voltage regulator connections, the presence of single, two and three-phase circuits, as well as the possibility of both the mutual coupling between phases and the shunt susceptance; (ii) treat three-phase networks with high resistance/reactance ratios in a unied framework; and (iii) process measurements with very distinct qualities, some of them are real-time measurements provided by Supervisory Control Data Acquisition (SCADA) systems, Advanced Metering Infrastructure (AMI), Phasor Measurement Units (PMUs), other are virtual measurements (information provided by the buses of zero power injection) and also the pseudo-measurements (load pseudo-measurements, load proles and historical measurement data). Several simulations results (with IEEE 34 and 4 node test feeders) have demonstrated satisfactory performance of the proposed methodology.

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