• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 9
  • 7
  • 7
  • 1
  • 1
  • 1
  • 1
  • Tagged with
  • 27
  • 27
  • 10
  • 8
  • 8
  • 7
  • 7
  • 3
  • 3
  • 3
  • 3
  • 3
  • 3
  • 3
  • 3
  • 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.
21

Stanovení přesnosti měření souřadnicového měřicího stroje Zeiss UPMC Carat / Determining the measurement accuracy of a coordinate measuring machine Zeiss UPMC Carat

Kiška, Roman January 2021 (has links)
The aim of this diploma thesis is to create a comprehensive study of measurement accuracy of coordinate measuring machine (hereinafter CMM) Zeiss UPMC 850 Carat S-ACC (hereinafter Zeiss Carat) for the needs of the national metrological institute in Brno in accordance with ČSN EN ISO / IEC 17025 and the follow-up system standards of the ČSN EN ISO 10360 series. Additionally, it includes the creation of instructions for the calculation of measurement uncertainty, which will be put into effect in an accredited calibration laboratory. The first part of the work focuses on the description of the current state of knowledge and the definition of basic concepts in the field of metrology and accurate measurements on CMM. The second part describes the Zeiss Carat measuring machine, identifies the individual contributors to the resulting measurement uncertainty and defines the methodology for their quantification. The last part deals with the evaluation of calibration data and the calculation of the expanded measurement uncertainty of the Zeiss Carat instrument, which is used to quantify its accuracy.
22

Avaliação volumétrica da face: validação do sistema de captação de imagem facial tridimensional pela tecnologia de luz estruturada, estudo em cadáver / Volumetric evaluation of the face: validation of the three-dimensional facial image capture system by structured light technology, cadaver study

Dornelles, Rodrigo de Faria Valle 30 January 2019 (has links)
A avaliação volumétrica da face é uma medida dimensional importante na avaliação pré-operatória, no planejamento e acompanhamento pós-operatório. Os sistemas de imagem tridimensional (3D) têm sido considerados uma ótima alternativa na mensuração linear, angular e volumétrica da face em comparação com as imagens bidimensionais (2D). Especificamente na área de atuação da Cirurgia Crânio-Maxilo-Facial, o uso da imagem em 3D na avaliação das malformações congênitas, sequelas de traumas, sequelas tumorais, planejamento de cirurgias ortognáticas, simulação de mudanças volumétricas, assimetrias faciais e outros, pode tornar o tratamento mais objetivo, rápido e potencializar os resultados. O objetivo deste projeto foi a avaliação da acurácia do cálculo volumétrico das partes moles da face a partir de malhas 3D de superfície, estudo em cadáver. Foram avaliados 09 cadáveres oriundos do Sistema de Verificação de Óbito da Capital - Universidade de São Paulo (SVO-USP). Foi incluído um expansor tecidual na região do terço médio de cada hemiface, que foi expandido progressivamente e, por meio de captação seriada de imagens tridimensionais da face com escâner de luz estruturada, foram obtidas malhas de superfície 3D a cada momento de expansão. As malhas 3D foram avaliadas quanto a variação volumétrica da região de inclusão do expansor com o uso de um software livre. O cálculo amostral supôs que as correlações encontradas apresentariam valores acima de 0,80. Para testes com poder de 80% e nível de significância de 5% seriam necessários, então, 18 hemifaces no estudo. Uma forte correlação foi observada entre todas as medições. Os gráficos de correlação linear evidenciaram um aumento linear positivo uniforme para os diferentes volumes virtuais avaliados em todas as 18 hemifaces estudadas. Todas as hemifaces não expandidas tiveram um delta significativamente menor em seções externas do cubo virtual medidas em comparação com seções externas do cubo virtual dos lados da face com expansor (P = 0,008). O grau excelente de correlação entre o volume expandido e o volume aferido virtualmente, evidenciou que obtenção de 144 malhas 3D (9 faces, 18 hemifaces, cada uma utilizada 2 vezes, uma com expansor e outra sem, totalizando 36 hemifaces estudadas com 4 malhas 3D para cada) foi uma amostra adequada para o estudo. O protocolo apresentado para o cálculo volumétrico da face com o processamento de imagem 3D assistido por computador e com a utilização de software livre em um estudo em cadáver, demonstrou versatilidade e acessibilidade, tendo sido comprovada a sua acurácia / The face volumetric evaluation is an important dimensional measure in the preoperative evaluation in planning and postoperative follow-up. 3D imaging systems have been considered a good alternative in linear and angular measurement of face compared to 2D images. Specifically, in Cranio-Maxillofacial Surgery area, the 3D imaging use in the evaluation of congenital malformations, trauma sequelae, tumor sequelae, orthognathic surgery planning, volumetric changes simulation, facial imbalances and others could turn the treatment more objective, faster and potentiate the results. This project objective was calculation volumetric accuracy evaluation of the soft face parts from 3D surface meshes cadaver study. We evaluated 9 cadavers from the Sistema de Verificação de Óbito da Capital - Universidade de São Paulo (SVO-USP). A tissue expander was included in each middle third hemiface region which was progressively expanded and by means of serial three-dimensional face images acquisition with light scanners surface 3D meshes structured were obtained at expansion each moment. The 3D meshes were evaluated for the expander inclusion region volumetric variation with free software use. The sample calculation assumed that the correlations found would have values above 0.80. Eighteen hemifaces would be necessary in the study for tests with a power of 80% and a level of significance of 5%. A strong correlation was observed between all measurements. The linear correlation graphs showed a positive consistent linear increase for different virtual volumes evaluated in all 18 hemifaces studied. All unexpanded hemifaces had a significantly lower delta in outer virtual cube measured sections compared to virtual cube on face sides with expander (P = 0.008) external sections. The excellent degree of correlation between the expanded volume and the virtually verified volume showed that obtaining 144 3D meshes (9 faces, 18 hemifaces, each one used 2 times, one with expander and one without, totaling 36 hemifaces studied with 4 3D meshes for each) was an adequate sample for the study. The protocol presented for face volumetric calculation with computer assisted 3D image processing and the free software use in a cadaver study demonstrated versatility and accessibility and its accuracy was proven
23

Aplikace senzorů a digitalizace podle IEC 61850 v sítích a rozvodnách vysokého napětí / Application of Sensors and Digitalization Based on IEC 61850 in Medium Voltage Networks and Switchgears

Štefanka, Martin January 2016 (has links)
Vzduchem izolované vysokonapěťové rozváděče jsou nedílnou součástí energetického distribučního řetězce a to jak v průmyslovém, tak ve veřejném sektoru. Hlavní funkcí rozváděče je ochrana pracovního personálu, rozpojování/odpojování a spínání, izolování, měření proudů a napětí, chránění a ovládání zatížení a komunikace dat do řídících systémů. V každé z výše zmíněných funkcí probíhal technologický vývoj v průběhu posledních 40 let. Dnešní rozváděče jsou spolehlivé a elektrickému oblouku odolné zařízení, zoptimalizované téměř k fyzikálním limitům dielektrických, elektromagnetických a termodynamických polí. Vakuové vypínače zajišťují stálou a spolehlivou vypínací funkci. Taktéž v oblasti chránění, řízení a komunikace došlo k mnoha technologickým proměnám. Od elektromechanických relé přes zařízení založená na tranzistorech, později na jednoúčelových mikroprocesorech, až po dnešní multifunkční vysoce výkonná mikroprocesorová inteligentní elektronická zařízení. Pouze oblast měření proudů a napětí setrvala z technologického hlediska posledních 40 let beze změny. K dominujícím měřícím technologiím dneška stále ještě patří indukčně založené transformátory proudu a napětí. Byly sice provedeny některé pokusy k obměně technologie měření jako takové, nicméně bez dosažení úspěchu. Tato dizertační práce je zaměřena na poskytnutí nového náhledu na alternativní technologii měření v elektrických sítích a ve vzduchem izolovaných vysokonapěťových rozváděčích, kterou lze využít jak pro měření proudu, tak i napětí. Tato práce vysvětluje, proč Rogowského cívky, odporové a kapacitní děliče jsou tou správnou volbou a měly by být použity ve vysokonapěťových rozváděčích a podrobně analyzuje přesnost měření a jejich příslušné meze. Dále tato práce popisuje, že pro nasazování nových měřících technologií musí být postupováno systematicky. Senzory připojené k inteligentním elektronickým přístrojům a schopností komunikace založené na IEC 61850 spolu s vysokorychlostní komunikační sběrnicí Ethernetu vytvoří systém, který zjednoduší a sjednotí konstrukci rozváděčů a umožní oddělit aspekty projektování měření od studie zkratových selektivit. V práci je také uveden příklad, jak tento nový systém může přinést změny a zjednodušení do oblastí projektování a řízení. V této práci jsou popsány výsledky několikaletého úsilí při stanovení nových měřících a digitalizovaných přístupů ve vysokonapěťových rozváděčích pod autorovým vedením. Toto úsilí také vedlo k uvedení nového produktu – UniGear Digital - konceptu od ABB. Závěrečná část práce demonstruje praktické nasazení všech výsledků v této práci při skutečných aplikacích.
24

Caractérisation radioélectrique des satellites de télécommunications du futur / Radioelectric measurements of future telecommunication satellites

Balma, Téegwendé Serge 29 January 2018 (has links)
Les paramètres radioélectriques des satellites sont actuellement mesurés directement, à l’aide d’une base compacte. Cependant, les li-mites de ces bases sont atteintes à cause de l’augmentation des dimensions des satellites, du nombre et de la complexité des antennes qu’ils comportent.Les techniques de champ proche constituent une solution prometteuse sous la forme de base pla-naire. Ces techniques consistent à mesurer le champ rayonné à proximité de la source pour en déduire, par traitement mathématique, le champ à grande distance.Ce travail de thèse porte sur l’adaptation des techniques de champ proche au test des satellites de télécommunications. La caractérisation du rayonnement des antennes par ces techniques estaujourd’hui largement utilisée. Toutefois, un développement théorique doit être complété et des méthodes de mesures proposées pour le test de l’ensemble des paramètres de la charge utile. Des difficultés spécifiques liées à la fonction du satellite (transpondeur) et à l’accès limité aux antennes et à l’électronique du satellite doivent être prise en compte dans la mise en oeuvre de ces méthodes de mesure.Enfin les mesures en champ proche sont affectées par plusieurs causes d’erreurs. L’identification des sources de ces erreurs et l’évaluation de leurs contributions au résultat final constituent une partie importante du travail de thèse. L’étude globale permet de dimensionner un système de mesure complet bénéficiant d’un bon niveau d’optimisation. / Nowadays, the radioelectric charac-teristics of satellites are directly measured by means of a com-pact range basis. However, the limits of these bases are affected by the growth of the satellite dimensions, in addition to the number and the complexity of the integrated an-tennas.On the other hand, near field techniques formed a promising solution under the planar range form. These techniques consist of measuring the radiated field near the source and accordingly deduce the far field by the means of mathemati-cal analysis.The purpose of this thesis is to adapt near field techniques for testing telecommunication satel-lites. In fact, these techniques are widelyused for antenna pattern measurements. However, a theoretical development has to be completed and measurement methods need to be proposed for testing all payload parameters. Unfortunately, specific difficulties related to the satellite function (transponder) and the limited access to antennas and satellite electronics have to be taken into account in the implementation of these measurement methodologies.Finally, the near field measurements are affected by many causes of errors. The identification of the error sources and the evaluation of their contribution to the final results constitute an important part of the thesis work. The global study allows dimensioning a complete measurement system with a good optimization.
25

Grafická reprezentace navigačních zpráv GNSS prototypu / GNSS navigation prototype messages visualization

Homolka, Martin January 2016 (has links)
The aim of this thesis is to graphically interpret navigation messages from a prototype of global navigation satellite system. The resulting application is implemented in Python programming language for Windows operating system and follows requests from researchers developing the prototype. Necessary terminology together with graphical user interface programming possibilities of object-oriented language Python is a base for theoretical background of this text. Practical part of this research describes a solution for receiving generated messages from the prototype as well as their storing and filtering into useful information. Further, the design of graphical user interface of the application for prototype interactions and other tools used for its configuration are included.
26

NOVÉ PRINCIPY CHARAKTERIZACE HRADLOVÝCH KAPACIT PRO SIGMA-DELTA MODULÁTORY / NEW PRINCIPLES OF GATE CAPACITANCE CHARACTERIZATION FOR SIGMA-DELTA MODULATORS

Sutorý, Tomáš January 2009 (has links)
This thesis deals with the utilization of new principles of characterization of gate capacitances for sigma-delta modulators. Sigma-delta modulators are the integral part of sigma-delta analog-to-digital converters. The proposed new method is characterized by high resolution and modest requirements for laboratory equipment. It allows characterizing capacitances whose values are within the range which is used in sigma-delta modulators. The thesis contains description of the new method, the analysis of measurement accuracy and experimental results.
27

Metodika zabezpečování optimální přesnosti měření v souladu s metrologickou konfirmací / The Optimal Accuracy of Measurement Assurance in Accordance with Metrological Confirmation

Frank, Petr January 2009 (has links)
This thesis deals with the evaluation of accuracy of measurement and achieving the required accuracy level. This includes global analysis of the uncertainty evaluation, the calibration interval design and the creation of confirmation system. Basis of this work is in identification of all possible problems, which may occur during evaluation of accuracy and achieving the required accuracy level. The analysis is followed by suggested solutions for identified problems. It means namely the selection of probability distribution in case of uncertainty type A, evaluation of degrees of freedom in case of uncertainty type B, nonlinear correlation of input values, evaluation of coverage factor, the choice of method for calibration interval design and the procedure for meeting all metrological confirmation requirements. The last part of the thesis is practical measurement and result evaluation in the field of surge protection devices. This chapter demonstrates conclusions from the syntactical part.

Page generated in 0.072 seconds