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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.
41

Uncertainty Analysis Of Coordinate Measuring Machine (cmm) Measurements

Sozak, Ahmet 01 September 2007 (has links) (PDF)
In this thesis, the measurement uncertainty of Coordinate Measuring Machine (CMM) is analysed and software is designed to simulate this. Analysis begins with the inspection of the measurement process and structure of the CMMs. After that, error sources are defined with respect to their effects on the measurement and then an error model is constructed to compensate these effects. In other words, systematic part of geometric, kinematic and thermal errors are compensated with error modelling. Kinematic and geometric error model is specific for the structure of CMM under inspection. Also, a common orthogonal kinematic model is formed and with using the laser error data of the CMM and error maps of the machine volume is obtained. Afterwards, the models are compared with each other by taking the difference and ratio. The definition and compensation of the systematic errors leave the uncertainty of measurements for analysing. Measurement uncertainty consists of the uncompensated systematic errors and random errors. The other aim of the thesis is to quantify these uncertainties with using the different methods and to inspect the success of these methods. Uncertainty budgeting, comparison, statistical evaluation by designing an experiments and simulation methods are examined and applied to the CMM under inspection. In addition, Virtual CMM software is designed to simulate the task specific measurement uncertainty of circle, sphere and plane without using the repeated measurements. Finally, the performance of the software, highly depending on the mathematical modelling of machine volume, is tested by using actual measurements.
42

Multiphase flow measurement using gamma-based techniques

Arubi, Isaac Marcus Tesi 03 1900 (has links)
The oil and gas industry need for high performing and low cost multiphase meters is ever more justified given the rapid depletion of conventional oil reserves. This has led oil companies to develop smaller/marginal fields and reservoirs in remote locations and deep offshore, thereby placing great demands for compact and more cost effective soluti8ons of on-line continuous multiphase flow measurement. The pattern recognition approach for clamp-on multiphase measurement employed in this research study provides one means for meeting this need. Cont/d.
43

Load measurement error influence on friction factor calibration of pipe water distribution networks through do reverse transient method and genetic algorithm / A InfluÃncia de erros de mediÃÃo de carga na calibraÃÃo de fator de atrito em tubulaÃÃes de redes de distribuiÃÃo de Ãgua atravÃs do mÃtodo transiente inverso e algoritmo genÃtico

BÃrbara Cristina Alves da Costa 10 November 2014 (has links)
O estudo de redes hidrÃulicas para fins de operaÃÃo ou anÃlise de viabilidade para ampliaÃÃo ou recuperaÃÃo das mesmas à iniciado pela calibraÃÃo, neste contexto, entendida como identificaÃÃo de parÃmetros tais como: fator de atrito, rugosidade e diÃmetro. O MÃtodo Transiente Inverso em conjunto com Algoritmo genÃtico se mostra eficiente nessa tarefa. O referido mÃtodo emprega o MÃtodo das CaracterÃsticas na soluÃÃo das equaÃÃes de movimento para escoamento transiente em tubos de redes e a otimizaÃÃo das soluÃÃes à baseada na Teoria Evolutiva e avaliada por uma funÃÃo objetivo, que neste estudo à o somatÃrio do mÃdulo da diferenÃa entre as cargas medidas e calculadas pelo modelo para cada conjunto de soluÃÃes. Considerando que o objetivo do desenvolvimento de modelos matemÃticos para a calibraÃÃo de redes hipotÃticas à a utilizaÃÃo dos mesmos em redes reais, e que nessas, a coleta de dados de carga està sujeita a erros de mediÃÃo, seja devido a defeitos nos equipamentos seja por condiÃÃes ambiente desfavorÃveis ou outros efeitos aleatÃrios e tendo em vista a relevÃncia dos fatores de atrito nas tubulaÃÃes, pela sua relaÃÃo com perdas de carga que devem ser controladas para um Ãtimo funcionamento de redes, garantindo um abastecimento contÃnuo em quantidade e condiÃÃes de funcionamento adequados, este trabalho propÃe-se a verificar a interferÃncia da presenÃa de erros de mediÃÃo de carga transiente na identificaÃÃo dos fatores de atrito em duas redes hidrÃulicas hipotÃticas. As mesmas sÃo de portes diferentes com relaÃÃo ao nÃmero de anÃis, nÃs e tubos. Ambas sÃo alimentadas por um reservatÃrio cada. As condiÃÃes transientes sÃo atribuÃdas a uma manobra de vÃlvula instalada em um dos nÃs de cada rede. A coleta de dados de carga à restrita a 20% dos nÃs de cada rede, sendo que um deles à o nà onde se encontra a vÃlvula. O tempo de observaÃÃo do transiente hidrÃulico à restrito ao tempo da manobra de vÃlvula, 20s, e ocorre em intervalos de 0,1s, resultando em 200 registros de carga. A condiÃÃo permanente das redes à inicialmente desconhecida o conhecimento acerca da mesma à restrito a carga nos reservatÃrios e demandas nos nÃs, bem como diÃmetros dos tubos, os fatores de atrito sÃo inicialmente estipulados. A determinaÃÃo das condiÃÃes permanente e transiente bem como a identificaÃÃo dos fatores de atrito à realizada com a utilizaÃÃo de um modelo hidrÃulico e geram cargas transientes que sÃo consideradas convencionalmente verdadeiras, essas entÃo recebem incrementos de diversos erros sistemÃticos e aleatÃrios, que geram novas cargas e essas sÃo consideradas coletadas com erros de mediÃÃo. A partir dessas novas cargas sÃo realizadas identificaÃÃes de fatores de atrito, os quais sÃo comparados com os que foram obtidos considerando um caso ideal de cargas sem erros de mediÃÃo. A referida comparaÃÃo à realizada atravÃs do Erro MÃdio Relativo e da FunÃÃo Objetivo Ãtima. Os resultados encontrados demonstram que os erros de mediÃÃo interferem na identificaÃÃo dos fatores de atrito apesar de nÃo ser possÃvel delinear uma relaÃÃo entre os mesmos. / The study of hydraulic networks for operation purposes or viability analysis for extension or renovation of the same is started the calibration in this context understood as identification parameters, such as friction coefficient, surface roughness and diameter. The Transient Inverse Method in conjunction with genetic algorithm is efficient in this task shows. This method employs the method of characteristics in the solution of the equations of motion for transient flow in networks of pipes and the optimization of solutions is based on Evolutionary Theory and evaluated by an objective function, which in this study is the sum of the difference between the module loads measured and calculated by the model for each set of solutions. Whereas the objective of the development of mathematical models for calibration hypothetical networks is their use in real networks, and that these, the collection of payload data is subject to measurement errors, is due to defects in the equipment or by conditions unfavorable environment or other random effects and taking into account the relevance of friction factors in pipelines, by their relationship to head losses that must be controlled to a great operation of networks, ensuring a continuous supply in quantity and appropriate operating conditions, this work is proposed to verify the influence of the presence of transient load measurement errors in the identification of friction factors in two hypothetical hydraulic networks. They are of different sizes with the number of rings, knots and tubes. Both are each fed by a reservoir. The transient conditions are assigned to a valve maneuver installed in one of the nodes of each network. The load data collection is restricted to 20% of the nodes in each network, one of which is the node where the valve is located. The hydraulic transient observation time is restricted to the valve maneuver time, 20s, and occurs at intervals of 0.1s, resulting in 200 charge records. The permanent condition of networks is initially unknown knowledge about the same is restricted to load in the reservoirs and demands on us as well as pipe diameter, the friction factors are initially stipulated. The determination of the permanent and transient conditions and the identification of the friction factors is performed using a hydraulic model and generate transient loads which are conventionally considered true, then these various steps of receiving systematic and random errors, which generate new burdens and these are considered collected with measurement errors. From these new loads are carried IDs friction factors, which are compared with those obtained considering an ideal case with no measurement errors loads. This comparison is performed using the mean relative error and function great goal. The results show that measurement errors in the identification of interfering friction factors although not possible to draw a relationship between them.
44

Caractérisation des propriétés électromagnétiques des matériaux magnétiquement doux : application aux roues polaires de machine à griffes / Characterization of the electromagnetic properties of soft magnetic materials : application to a claw pole rotor

Arbenz, Laure 18 March 2016 (has links)
La construction électrique reposant en grande partie sur l’utilisation des propriétés électromagnétiques du fer et de ses alliages, les concepteurs ont besoin d’une connaissance précise de ces propriétés. Les caractéristiques des matériaux magnétiques doux, typiquement celles de l’acier des roues polaires d'une machine à griffes, peuvent être notablement impactées par les procédés de fabrication. Celles-ci doivent alors être caractérisées directement sur la pièce finale. Dans ce travail, on propose une méthode de mesure non destructive combinant une démarche opératoire et la simulation par éléments finis afin de caractériser la conductivité électrique locale des roues polaires. Afin d’adapter les paramètres expérimentaux à la géométrie de la pièce considérée, et à l’aide d’un diagramme 5M (ou diagramme d'Ishikawa), une démarche d’optimisation de la méthode est entreprise. Puis l’incertitude de mesure est déterminée à l’aide de deux démarches différentes. Cette méthode est ensuite exploitée pour mener une étude sur une population de roues polaires extraites de la chaîne de production. Dans un second temps, la méthode est étendue pour la mesure de perméabilité incrémentale. Des essais sur tôles épaisses ont permis de valider l’approche proposée à l'aide du même type de capteur. Par ailleurs, une étude complémentaire par éléments finis 3D a permis de mettre en évidence les limites de l'approche analytique, notamment lorsque la perméabilité de la plaque et son épaisseur deviennent trop importantes. Finalement, cette méthode est appliquée au cas des roues polaire, dans le cadre d’une approche qualitative, en vue d’une application de type contrôle qualité. / Electrical energy conversion devices are based on the use of electromagnetic properties of iron and its alloys. Therefore, an accurate knowledge of these properties is required for the designers. The characteristics of the soft magnetic materials, typically those of a claw pole rotor, can be significantly impacted by the manufacturing processes. Consequently, these properties must be characterized directly on the manufactured magnetic piece. In this work, a non-destructive measurement method combining an operative approach and the finite element simulation is proposed to characterize the local electrical conductivity of the claw pole rotor. The choice of the experimental parameters associated to the claw pole rotor geometry is optimized using the Ishikawa diagram. Then, the measurement uncertainty is determined using two different approaches. This method is applied to perform a study on a population of claw pole rotors issued from the manufacturing chain. Secondly, the method is extended to incremental permeability measurement. Tests on thick sheets were realized to validate the proposed approach with the same type of sensor. Moreover, a complementary study in 3D finite element has emphasized the limitations of the analytical approach, especially when the permeability of the plate and its thickness become significant. Finally, this method is applied to the case of claw pole rotors through a qualitative approach for a quality control application.
45

Nejistoty měření dynamické viskozity / Uncertainties of measurements of the dynamic viscosity

Januš, Petr January 2012 (has links)
The thesis is deal with measuring the temperature dependence of dynamic viscosity and the calculation of measurement uncertainties. The thesis writes up the physical nature of viscosity and rheological properties. Next it is write up an overview of possible methods for measuring viscosity of liquids and overview of methods for measuring the density of liquids. An important chapter is the statistical evaluation of measured data represented mainly measurement uncertainties. In the practical part of the work is done workplace for measure the temperature dependence of dynamic viscosity. It is used two methods of measuring viscosity of liquids and two samples of liquids. Finally is done statistical evaluations of measurement. Based on the calculated measurement uncertainty measurement methods are compared.
46

Kalibrace závaží a vah / Calibration of weights and balances

Vojtová, Klára January 2013 (has links)
In the introductory chapter of this work is caught organizational structure of the national metrology system in the Czech Republic and its links to international organizations. There is indicated the basic terminology of metrology, particularly in the area of classification instruments. The following sections approaching the issue of measurement uncertainties, their classification, sources of uncertainty determined by the type A and B, their specifics and calculation. The above linked area already dealing with themselves calibrations, first of all calibration weights, classification of weights according accuracy classes, established procedures, and finally determining uncertainty in calibration weights. Then, immediately followed by a chapter dealing with calibration balances, performed tests and measurement uncertainties. The main part is of course directed towards the application of acquired knowledge to practical examples, thus performing the calibration weight class F2 using a high-precision weights, both in the premises of the Technical University in Brno, both in the laboratory weighing the Czech Metrological Institute. Further calibration was performed school balances Ohaus Explorer EX224.
47

Nejistoty interferometrických měření / Uncertainties in interferometric measurements

Kočí, Radek January 2014 (has links)
This diploma thesis deals with uncertainties of interferometric measurements and methods for their evaluation. In the theoretical part of the thesis, are described interferometers and interferometric measurement techniques. Furthermore, there is presented process of determining the measurement uncertainty using methods GUM and Monte Carlo. In the practical part of the thesis, there are these two methods are used for qualification of measurement uncertainty calculated for the specific interferometer.
48

ANALÝZA ZPŮSOBILOSTI VÝROBNÍHO STROJE PŘI VÝROBĚ AUTOBUSŮ / ANALYZIS OF THE PROCESSING MACHINE CAPABILITY IN BUS PRODUCTION

Gregor, Jaroslav January 2008 (has links)
The diploma thesis deals with an analysis of the processing machine capability in bus production. The goal is to evaluate the capability of the CNC laser processing machine in conditions of Iveco Czech Republic, Ltd., Vysoke Myto. In the theoretical part, the thesis studies measurements and capability of the processing machine; the practical part describes the present state of production and suggests a solution of the assigned task.
49

Výpočet emisní hodnoty při měření akustického tlaku a výkonu / Calculation of emission value in measurement of acoustic pressure and capacity

Málek, Michal January 2008 (has links)
The conceptions in acoustics. The description of the methods measurement of the noise mechanical equipment. The express the uncertainty of measurement. The analyse and determination basic emission values of acoustic pressure and power. The summary of results and programming of the calculation basic emission values acoustic pressure and power for fine implementation measurement.
50

Analýza kontroly klopného momentu axiálního táhla řízení / Analysis verification monostable moment longitudinal steering linkage

Novotný, Petr January 2010 (has links)
Work smoothing - out evaluation accuracy of measurement monostable moment steering linkage by the help of special machine. Evaluates individual characteristics accuracy, especially uncertainty metering.

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