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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

Nízkoúrovňového měření ELF magnetických polí / Low-level measurement of ELF magnetic fields

Cích, Augustín January 2021 (has links)
This Master's thesis deals with design of sensor network for synchronised low-level recording of changes in magnetic part of Earth's field in ELF band in multiple places. The goal is acquisition of changes due to solar storm activity, while taking into account, that in research of geomagnetic effects connected with solar events is spectrum of interest broader and reach up to VLF, where a solution is often made of combination of receivers in ELF and VLF, a decision was made, after consulting with thesis supervisor and researchers, that device will be designed for ELF, but can be easily modified, by changing preamplifier, for using in higher frequency bands, creating a solid founding for further measurements and research in this field.
2

Model měření výšky hladiny / Model of Level Measurement

Pavliš, Michal January 2009 (has links)
This master's thesis is engaged in its theoretical part of the description and explanation principles and possibility how to the level measurement. There are clear up individual kinds and types of sensors to the level measurement. Further is described software and hardware which is employing to the measurement or control many systems and circuitry. A practical part consists in suggestion and self realization a model of level measurement including his controlling. Last but not least too creation partly instruction to attendance laboratory workspace and further creation several measuring and control software in the system named Control Web 6. Work is above all focusing on model approach of this problems needs for purposes laboratory teaching.
3

Redes neurais e support vector machines como técnicas de diagnósticos em medições industriais de nível por tecnologia tipo radar sem contato e apoio à decisão para a melhoria de sua aplicação / Neural networks and support vector machines as diagnosing tool for industrial level measurement through non-contacting radar type and support to the decision for its better application

Borg, Denis 02 December 2016 (has links)
O objetivo dessa tese é detectar e classificar problemas de medição de nível por princípio de radar de propagação de onda livre por meio de RNA (redes neurais artificiais) e SVM (support vector machines) aliados à tratamentos estatísticos. Um primeiro cenário com ambiente controlado foi montado para a obtenção de dados preliminares. Na sequência, outros três cenários empregaram dados industriais reais. Para tanto, algumas topologias de redes neurais em quatro cenários diferentes foram testadas e foi possível demonstrar o funcionamento eficiente da RNA com acertos de 100% para o primeiro cenário, 93,51% para o segundo, 99,75% para o terceiro e de 99,94% para o quarto cenário. Para esses mesmos quatro cenários, os resultados de classificação do SVM foram de 100%, 84,41%, 93,74% e de 96,40%. Os resultados obtidos demonstram que a técnica desenvolvida pode ser aplicada à cenários reais de medição de nível. Após a classificação dos problemas pela RNA ou SVM é recomendada a utilização de alguns dos ícones baseados na norma internacional NAMUR NE107 para reportar as diferentes classificações de problemas resultantes da aplicação das técnicas dessa tese. Propõe-se que essas técnicas sejam embarcadas em aplicativos computacionais de gerenciamento de ativos para melhorar a confiabilidade da medição, antecipar rotinas de manutenção dos instrumentos e aumentar a segurança da planta industrial através de reportes adequados aos usuários dos problemas de medição de nível e do mapeamento das fases do processo. / The aim of this Thesis is to detect and classify level measurement problems by free wave propagation radars using ANN (artificial neural network) and SVM (support vector machines) with statistical pre-processing data. In the first scenario, a controlled environment was build in order to get the preliminary data. In addition, three other scenarios with real industry data was considered. Therefore, some topologies of neural networks and SVM in four different scenarios were tested and it was demonstrated the efficiency of ANN to reach an accuracy rate of 100% for the first scenario, 93.51% for the second, 99.75% for third and 99.94% for the fourth scenario. For these same four scenarios, the results of SVM classification were 100%, 84.41%, 93.74% and 96.40%. After classifying the problems by ANN or SVM, it is recommended to use some of the icons following the international standard NAMUR NE107 to report the different classifications of problems within this thesis. It is proposed that these techniques be embedded in asset management environment to improve the reliability of level measurement, antecipate maintenance routines and improve plant safety through adequately reporting the classified problems and mapping stage of the process to the users.
4

Redes neurais e support vector machines como técnicas de diagnósticos em medições industriais de nível por tecnologia tipo radar sem contato e apoio à decisão para a melhoria de sua aplicação / Neural networks and support vector machines as diagnosing tool for industrial level measurement through non-contacting radar type and support to the decision for its better application

Denis Borg 02 December 2016 (has links)
O objetivo dessa tese é detectar e classificar problemas de medição de nível por princípio de radar de propagação de onda livre por meio de RNA (redes neurais artificiais) e SVM (support vector machines) aliados à tratamentos estatísticos. Um primeiro cenário com ambiente controlado foi montado para a obtenção de dados preliminares. Na sequência, outros três cenários empregaram dados industriais reais. Para tanto, algumas topologias de redes neurais em quatro cenários diferentes foram testadas e foi possível demonstrar o funcionamento eficiente da RNA com acertos de 100% para o primeiro cenário, 93,51% para o segundo, 99,75% para o terceiro e de 99,94% para o quarto cenário. Para esses mesmos quatro cenários, os resultados de classificação do SVM foram de 100%, 84,41%, 93,74% e de 96,40%. Os resultados obtidos demonstram que a técnica desenvolvida pode ser aplicada à cenários reais de medição de nível. Após a classificação dos problemas pela RNA ou SVM é recomendada a utilização de alguns dos ícones baseados na norma internacional NAMUR NE107 para reportar as diferentes classificações de problemas resultantes da aplicação das técnicas dessa tese. Propõe-se que essas técnicas sejam embarcadas em aplicativos computacionais de gerenciamento de ativos para melhorar a confiabilidade da medição, antecipar rotinas de manutenção dos instrumentos e aumentar a segurança da planta industrial através de reportes adequados aos usuários dos problemas de medição de nível e do mapeamento das fases do processo. / The aim of this Thesis is to detect and classify level measurement problems by free wave propagation radars using ANN (artificial neural network) and SVM (support vector machines) with statistical pre-processing data. In the first scenario, a controlled environment was build in order to get the preliminary data. In addition, three other scenarios with real industry data was considered. Therefore, some topologies of neural networks and SVM in four different scenarios were tested and it was demonstrated the efficiency of ANN to reach an accuracy rate of 100% for the first scenario, 93.51% for the second, 99.75% for third and 99.94% for the fourth scenario. For these same four scenarios, the results of SVM classification were 100%, 84.41%, 93.74% and 96.40%. After classifying the problems by ANN or SVM, it is recommended to use some of the icons following the international standard NAMUR NE107 to report the different classifications of problems within this thesis. It is proposed that these techniques be embedded in asset management environment to improve the reliability of level measurement, antecipate maintenance routines and improve plant safety through adequately reporting the classified problems and mapping stage of the process to the users.
5

Permanenta klätterväxlar – en undersökning : Denna rapport innehåller intervjuer, litteraturstudie samt en fältundersökning med ljudnivåmätning

KLENCOVLJEVIC, Goran, Shuvo Khan, MD January 2020 (has links)
Swedish railway network is old, it is in need for maintenance and there is an ever-increasing volume oftraffic on todays railroads. Special trackwork component has taken increased abuse, leading to a stop intrain traffic and many delays occur, especially during the winter season. The most sensitive parts of therailway network are turnout frogs and they require the most maintenance and cause delays. Therefore, TheSwedish Transport Administration is planning to investigate and introduce a new type av railwayswitches, called flange bearing technology. Flange bearing frogs and diamonds are already in use in USand there are already benefits in both reduced maintenance and increased life expectancy and possiblyreduced noise level.Therefore, this bachelor thesis is investigating flange bearing technology with an accent on sound levelmeasurement. It is studied how flange bearing frogs works and how they differ from conventional treadbearing frogs. In addition, there is a field study with sound level measurement and interviews withemployees at The Swedish Transport Administration. Furthermore, it is investigated how flange bearingtechnology is used in US. This bachelor thesis is limited to a field research with sound level measurement,interviews, and a theoretical description of railway switches. Field study is located at a flange bearingfrog, station Globen-Gullmarsplan in Stockholm. This flange bearing frog is used as a connection betweenthe tram railway and the metro railway.Flange bearing technology has a simpler design compared to conventional tread bearing frogs. This simpledesign can provide benefits by reducing vertical dynamic loads. Flange bearing means that unsupportedflangeway gap is eliminated from the running surface of the frog. For that reason, there is no speedreduction on the main track. Conventional tread bearing frogs have unsupported flangeway gap thatwheels must cross.Field study at Globen-Gullmarsplan was carried out with the help of a sound level meter and it wasperformed eight measurements at both flange bearing frog and conventional tread bearing frog. This studyshows that flange bearing frogs causes less noise than conventional tread bearing frog. Interviews showsthat The Swedish transport Administration is working to reduce noise interference from rail traffic andthat flange bearing technology can be a good solution for achieving lower noise level. However, moreresearch is required about maintenance, comfort, cost, and life expectancy of flange bearing technology.
6

Estudo de modelo hidrodinâmico unidimensional aplicado a um trecho de canal do Córrego do Gregório em São Carlos, SP / One-dimensional study of hydrodynamic model applied to a channel stretch of stream of Gregório in São Carlos, SP

Almeida, Rodrigo Martins de 09 October 2013 (has links)
O presente trabalho reporta o esforço empenhado para relacionar nível d\'água e vazão, fazendo uso exclusivamente de medições de nível, em campo, durante a passagem de ondas de cheia através de um trecho de canal prismático situado no perímetro urbano da cidade de São Carlos, SP denominado Córrego do Gregório. Montagens para coleta de dados em campo foram testadas e foi utilizada a modelagem hidrodinâmica 1-D para a resolução das equações de Saint-Venant, através do método implícito de quatro pontos de Preissmann. Apesar do potencial do método, já apontado por alguns autores, o presente trabalho reporta dificuldades na realização de medições e também problemas na modelagem de trecho de canal com características muito particulares. Várias análises foram realizadas tais como a verificação do número de passos de tempo necessário para minimização dos efeitos da condição inicial imposta (IQ1), a verificação da celeridade de uma onda de cheia analisando os picos dos eventos e assim determinar o coeficiente de cisalhamento de Manning proposto por Aricò, Nasello e Tucciarelli (2009) e o método implícito na resolução das equações de SV proposto por Jin, Coran e Cook (2004), que funciona como um filtro baseado no número de Froude (condição do tipo de escoamento) também foi testado. Durante o evento do dia 23/03/2013 foi estimado as velocidades em campo. Para cada um dos 12 eventos registrados foi realizado uma simulação utilizando o modelo hidrodinâmico e o melhor resultado foi utilizado em uma segunda simulação para comparar as lâminas d\'água observadas e calculadas. Ao analisar o quanto os valores de erros máximos absolutos (ERMAX1 e ERMAX2) representam em relação ao máximo registro obtido no evento, em porcentagem, têm-se eventos com 3,6% até valores absurdos de 27,1%. Assim, trata-se de um trabalho teórico-experimental que oferece subsídios importantes para futuros trabalhos nessa direção. / This work reports the committed effort to relate water level and flow, using exclusively field measurements of level, during the passage of flood waves through a prismatic channel stretch located on the surroundings of São Carlos - SP called stream of Gregório. Assembles for data gathering in the field were tested and it was used 1-D hydrodynamic modeling for solving equations of Saint-Venant, through the four points Preissmann implicit method. Despite the potential of this method, as pointed out by some authors, this study reports difficulties in performing measurements and to model a channel stretch with very particular characteristics. Several analyzes were performed such as checking the number of time steps needed for minimizing the effects of the initial condition imposed (IQ1), verifying the celerity of a full wave analyzing the peaks of events and so to be able to determine the Manning friction coefficient proposed by Arico et al. (2009) and the implicit method to solve the S-V equations proposed by Jin, Coran e Cook (2004), which acts as a filter based on the Froude number (condition-type flow), was also tested. During the event of the day 23/03/2013 was estimated speeds in the field. For each of the 12 recorded events a simulation was made using a hydrodynamic model and the best result was used in a simulation to compare the second water depths observed and calculated. By analyzing how the values of maximum absolute errors (ERMAX1 and ERMAX2) account for the highest recording obtained at the event, in percentage, have been events with 3.6% until absurd values from 27.1%. So, it is a theoretical-experimental that offers important information for future work in this direction.
7

Estudo de modelo hidrodinâmico unidimensional aplicado a um trecho de canal do Córrego do Gregório em São Carlos, SP / One-dimensional study of hydrodynamic model applied to a channel stretch of stream of Gregório in São Carlos, SP

Rodrigo Martins de Almeida 09 October 2013 (has links)
O presente trabalho reporta o esforço empenhado para relacionar nível d\'água e vazão, fazendo uso exclusivamente de medições de nível, em campo, durante a passagem de ondas de cheia através de um trecho de canal prismático situado no perímetro urbano da cidade de São Carlos, SP denominado Córrego do Gregório. Montagens para coleta de dados em campo foram testadas e foi utilizada a modelagem hidrodinâmica 1-D para a resolução das equações de Saint-Venant, através do método implícito de quatro pontos de Preissmann. Apesar do potencial do método, já apontado por alguns autores, o presente trabalho reporta dificuldades na realização de medições e também problemas na modelagem de trecho de canal com características muito particulares. Várias análises foram realizadas tais como a verificação do número de passos de tempo necessário para minimização dos efeitos da condição inicial imposta (IQ1), a verificação da celeridade de uma onda de cheia analisando os picos dos eventos e assim determinar o coeficiente de cisalhamento de Manning proposto por Aricò, Nasello e Tucciarelli (2009) e o método implícito na resolução das equações de SV proposto por Jin, Coran e Cook (2004), que funciona como um filtro baseado no número de Froude (condição do tipo de escoamento) também foi testado. Durante o evento do dia 23/03/2013 foi estimado as velocidades em campo. Para cada um dos 12 eventos registrados foi realizado uma simulação utilizando o modelo hidrodinâmico e o melhor resultado foi utilizado em uma segunda simulação para comparar as lâminas d\'água observadas e calculadas. Ao analisar o quanto os valores de erros máximos absolutos (ERMAX1 e ERMAX2) representam em relação ao máximo registro obtido no evento, em porcentagem, têm-se eventos com 3,6% até valores absurdos de 27,1%. Assim, trata-se de um trabalho teórico-experimental que oferece subsídios importantes para futuros trabalhos nessa direção. / This work reports the committed effort to relate water level and flow, using exclusively field measurements of level, during the passage of flood waves through a prismatic channel stretch located on the surroundings of São Carlos - SP called stream of Gregório. Assembles for data gathering in the field were tested and it was used 1-D hydrodynamic modeling for solving equations of Saint-Venant, through the four points Preissmann implicit method. Despite the potential of this method, as pointed out by some authors, this study reports difficulties in performing measurements and to model a channel stretch with very particular characteristics. Several analyzes were performed such as checking the number of time steps needed for minimizing the effects of the initial condition imposed (IQ1), verifying the celerity of a full wave analyzing the peaks of events and so to be able to determine the Manning friction coefficient proposed by Arico et al. (2009) and the implicit method to solve the S-V equations proposed by Jin, Coran e Cook (2004), which acts as a filter based on the Froude number (condition-type flow), was also tested. During the event of the day 23/03/2013 was estimated speeds in the field. For each of the 12 recorded events a simulation was made using a hydrodynamic model and the best result was used in a simulation to compare the second water depths observed and calculated. By analyzing how the values of maximum absolute errors (ERMAX1 and ERMAX2) account for the highest recording obtained at the event, in percentage, have been events with 3.6% until absurd values from 27.1%. So, it is a theoretical-experimental that offers important information for future work in this direction.
8

Inventering av olika mätare för Stuguns vattenkraftverk

Söder, Peter January 2017 (has links)
Det finns många sensormetoder för vattennivåmätning ute på marknaden idag. Målet för forskningsstudien är att presentera och jämföra några av de mätningsmetoder som finns på marknaden för nivåmätning. I studien jämförs modellerna för trycksensorer, flytsensorer, ultraljudssensor och elektromagnetisk sensor för att sedan se vilken sensor som passar bäst för just mätningar av vattennivåer. Genom, datainsamlingen från sök motorerna Google scholar och Mittuniversitetets egen databas Primo har fakta samlats. Informationen har sedan bearbetas och jämförts mot behoven från Vattenfall som ska göra tre sensorbyten på vattenkraftverket i Stugun. Resultatet av studien visade slutsatsen att utifrån kravspecifikationerna Vattenfall gav så var en trycksensor det bästa alternativet för Stugun. Studien gjorde så att Vattenfall köpte in tre stycken Waterpilot FMX21, 22 mm som sedan sattes på plats och kalibrerades. / There are many sensor methods for water level measurement on the market today. The aim of the research study is to present and compare some of the measurement methods available on the market for level measurement. In the study, the models for pressure sensors, flow sensors, ultrasonic sensors and electromagnetic sensors are compared to see which sensor is most suitable for precise measurements of water levels. Through the data collection from the search engines Google scholar and Mid University of Sweden own database Primo, facts have been gathered. The information has since been processed and compared to the needs of Vattenfall, which will do three sensor changes at the Stugun hydropower plant. The result of the study showed that according to the requirement specifications of Vattenfall, a pressure sensor was the best alternative for Stugun. The study resulted in Vattenfall purchasing three Waterpilot FMX21, 22 mm, which were then put in place and calibrated.
9

Mesure d’impédance acoustique pour la caractérisation des cycles limites de moteurs thermoacoustiques / Acoustic impedance measurement to caracterize thermoacoustic engines limit cycles

Zorgnotti, Valentin 18 January 2019 (has links)
Ce manuscrit de doctorat propose une méthode expérimentale pour la caractérisation du cycle limite acoustique atteint par les auto-oscillations générées dans un moteur thermoacoustique.Pour cela, un capteur d'impédance fort niveau est développé dans le but de mesurer l'impédance d'entrée d'un noyau thermoacoustique en fonction de la puissance de chauffage fournie, de la fréquence et de l'amplitude du forçage acoustique.L'utilisation de ces mesures permet de prédire avec succès la génération spontanée d'auto-oscillations ainsi que leur saturation jusqu'à un régime établi, pour différentes charges attachées au noyau.Les mesures ainsi obtenues sont comparées à un modèle établi sur la base de la théorie linéaire de la thermoacoustique, couplé un modèle thermique simplifié, menant à une meilleure compréhension des processus physiques responsables de la saturation des oscillations acoustiques.La procédure expérimentale décrite dans ce manuscrit permet aussi de proposer une méthode d'optimisation du couplage entre la charge et le noyau de manière à maximiser l'efficacité potentielle de la conversion d'énergie thermoacoustique.Finalement, une méthode expérimentale est décrite et permet l'étude de la stabilité des cycles limites, ou plus généralement de l'évolution lente de l'amplitude des auto-oscillations acoustiques, dans le cas où le moteur thermoacoustique est configuré de manière à donner lieu à un régime de déclenchements et arrêts périodiques. / This manuscript deals with the experimental characterization of the acoustic limit cycle reached by self-sustained oscillations generated in thermoacoustic engines.A specially designed, high amplitude, acoustic impedance sensor was developed to perform measurements of the input impedance of a thermoacoustic core, as a function of the heating power supplied to the device, of the frequency, and of the amplitude of acoustic forcing.Those measurements can then be used to predict the spontaneous generation of acoustic oscillations and their saturation up to a certain steady-state.Those predictions were successful for various acoustic loads connected to the thermoacoustic core.Moreover, the measurements of acoustic impedance as a function of the amplitude of acoustic oscillations are compared to a model based on the linear thermoacoustic theory, and this comparaison provides insights into the processes controlling the saturation of acoustic oscillations.The experimental procedure described in this manuscript also leads to a pratical way of optimizing the coupling between the thermoacoustic core and the load, in the way that the potential efficiency of thermoacoustic energy conversion is maximized.Finally, an experimental method is described and allows to study the stability of limit cycles, i.e. the temporal evolution of the self-oscillation amplitude, in the case of a system that is able to give rise to a spontaneous periodic \textit{trigg and stop} behavior.
10

3. Workshop "Meßtechnik für stationäre und transiente Mehrphasenströmungen", 14. Oktober 1999 in Rossendorf

Prasser, Horst-Michael 31 March 2010 (has links) (PDF)
Am 14. Oktober 1999 wurde in Rossendorf die dritte Veranstaltung in einer Serie von Workshops über Meßtechnik für stationäre und transiente Mehrphasenströmungen durchgeführt. Dieses Jahr kann auf auf 11 interessante Vorträge zurückgeblickt werden. Besonders hervorzuheben sind die beiden Hauptvorträge, die von Herrn Professor Hetsroni aus Haifa und Herrn Dr. Sengpiel aus Karlsruhe gehalten wurden. Erneut lag ein wichtiger Schwerpunkt auf Meßverfahren, die räumliche Verteilungen von Phasenanteilen und Geschwindigkeiten sowie die Größe von Partikeln bzw. Blasen der dispersen Phase zugänglich machen. So wurde über einen dreidimensional arbeitenden Röntgentomographen, ein Verfahren zur Messung von Geschwindigkeitsprofilen mit Gittersensoren und eine Methode zur simultanen Messung von Blasengrößen sowie Feldern von Gas- und Flüssigkeitsgeschwindigkeit mit einer optischen Partikelverfolgungstechnik vorgetragen. Daneben wurden interessante Entwicklungen auf dem Gebiet der lokalen Sonden vorgestellt, wie z.B. eine Elektrodiffusionssonde. Neue meßtechnische Ansätze waren ebenfalls vertreten; hervorzuheben ist der Versuch, die Methode der optischen Tomographie für die Untersuchung von Zweiphasenströmungen nutzbar zu machen. Der Tagungsband enthält die folgenden Beiträge: S. John, R. Wilfer, N. Räbiger, Universität Bremen, Messung hydrodynamischer Parameter in Mehrphasenströmungen bei hohen Dispersphasengehalten mit Hilfe der Elektrodiffusionsmeßtechnik E. Krepper, A. Aszodi, Forschungszentrum Rossendorf, Temperatur- und Dampfgehaltsverteilungen bei Sieden in seitlich beheizten Tanks D. Hoppe, Forschungszentrum Rossendorf, Ein akustisches Resonanzverfahren zur Klassifizierung von Füllständen W. Sengpiel, V. Heinzel, M. Simon, Forschungszentrum Karlsruhe, Messungen der Eigenschaften von kontinuierlicher und disperser Phase in Luft-Wasser-Blasenströmungen R. Eschrich, VDI, Die Probestromentnahme zur Bestimmung der dispersen Phase einer Zweiphasenströmung U. Hampel, TU Dresden, Optische Tomographie O. Borchers, C. Busch, G. Eigenberger, Universität Stuttgart, Analyse der Hydrodynamik in Blasenströmungen mit einer Bildverarbeitungsmethode C. Zippe, Forschungszentrum Rossendorf, Beobachtung der Wechselwirkung von Blasen mit Gittersensoren mit einer Hochgeschwindigkeits-Videokamera H.-M. Prasser, Forschungszentrum Rossendorf, Geschwindigkeits- und Durchflußmessung mit Gittersensoren

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