Browsing by Author "Lira Canguilhem, Ignacio"

Now showing 1 - 20 of 22
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    A Formalism for Expressing the Probability Density Functions of Interrelated Quantities
    (2013) Lira Canguilhem, Ignacio; Grientschnig, D.
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    Analysis of Key Comparisons Incorporating Knowledge About Bias
    (2012) Lira Canguilhem, Ignacio; Chunovkina, Anna; Elster, Clemens; Woger, Wolfgang
    A method is proposed for analyzing key comparison data. It is based on the assumption that each laboratory participating in the comparison exercise obtains independent and consistent estimates of the measurand and that, in addition, each laboratory provides an estimate of the quantity that collects all systematic effects that the laboratory took into account. The unknown value of the latter quantity, subtracted from its estimate, is defined as the laboratory's bias. The uncertainties associated with the estimates of the measurand and with the vanishing biases' estimates are also assumed to be reported. In this paper, we show that the information provided in this way may be of help for judging the performances of the laboratories in their correction of systematic effects. This is done by developing formulas for the final (consensus) estimates and uncertainties of the measurand and of the biases. Formulas for the final estimates and uncertainties of the pairwise differences between the biases are also developed. An example involving simulated key comparison data makes apparent the benefits of the proposed approach.
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    Bayesian treatment of results from radioanalytical measurements. Effect of prior information modification in the final value of the activity
    (2019) Barrera, M.; Lira Canguilhem, Ignacio; Sánchez-Sánchez, M.; Suarez-Llorens, A
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    CED: a new method for high speed stepping motor driving
    (IEEE, 1997) Vadell Rivera, Jaime Ernesto; Lira Canguilhem, Ignacio; Dixon Rojas, Juan
    Stepper motors are indexing devices widely used today in microcomputer controlled machines because of their low cost, simplicity, accuracy and repeatability. Even though their speed is presently adequate for many purposes, there is still some room for improving this parameter. In this article, the authors propose a new electrical driving method especially designed for small stepper motors, fed with unidirectional currents. The method is called "controlled energy discharge" (CED) and is based on changing the time response constant of the current due to winding inductance by the addition of a charged capacitor. The theory of the method, its implementation and performance comparisons with traditional control schemes are presented. From these comparisons, the authors' proposal appears to be an excellent alternative for driving stepping motors.
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    Combining inconsistent data
    (IEEE, 2007) Lira Canguilhem, Ignacio
    At present, the most widely used procedure for finding the value of a quantity from data obtained by different observers involves calculating the inverse-variance weighted mean of the observers' estimates. This method produces reasonable results if the data are consistent. However, in many cases a consistency test reveals the possible existence of outliers that nevertheless have to be included in the evaluation task. In this paper the Bayesian understanding of probability is used to treat this problem. It is first shown that the weighted mean method results from the assumption that the observers' biases are identically zero. If the data do not support this assumption, other evaluation methods are needed. Three such methods are then derived, application of which is discussed through a simulated example.
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    Combining Probability Distributions by Multiplication in Metrology : A Viable Method?
    (2014) Grientschnig, D.; Lira Canguilhem, Ignacio
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    Dealing with prior knowledge about the measurand
    (2016) Lira Canguilhem, Ignacio
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    Dimensional analysis made simple
    (2013) Lira Canguilhem, Ignacio
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    Electronic speckle pattern interferometry analysis of tensile tests of semihard copper sheets
    (2001) Vial Edwards, Cristián; Lira Canguilhem, Ignacio; Martínez, A.; Münzenmayer Schuller, Marcelo Andrés
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    Error-in-variables models in calibration
    (2017) Lira Canguilhem, Ignacio; Grientschnig, D.
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    Evaluation of the uncertainty in the measurement of nanoparticle size by dynamic light scattering
    (2020) Goldschmidt, G.; Hotza, D.; Plentz, F.; Camarano, D.; Lira Canguilhem, Ignacio
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    Introducing scale analysis by way of a pendulum.
    (2007) Lira Canguilhem, Ignacio
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    Medición interferométrica del perfil de temperatura en torno a un alambre sometido a convección natural
    (2009) Alvarez Paredes, Félix Armando; Lira Canguilhem, Ignacio; Pontificia Universidad Católica de Chile. Escuela de Ingeniería
    El presente trabajo se basa en la hipótesis de que por medio de la interferometría electrónica, se pueden estimar los perfiles de temperatura en la capa límite generados por la transferencia de calor por convección natural alrededor de un cilindro calentado, a través del cálculo del índice de refracción. La tesis presenta la teoría óptica en la que se basa este trabajo y los métodos usados para procesar la información recogida de la experimentación. Además se describe un procedimiento teórico para estimar los perfiles de temperatura, alternativo al método experimental. El experimento consistió en un montaje óptico llamado interferómetro de Mach-Zehnder el cual utiliza una fuente de luz láser para generar patrones de interferencia, provocados por la diferencia de camino óptico de la luz en el interferómetro. El objeto de fase sobre el cual se estimarán los gradientes de temperatura será un alambre vertical calentado mediante un diferencial de voltaje. La información será captada por una cámara CCD a través de interferogramas que captan la intensidad de la luz a la salida del interferómetro. Esta información es procesada para obtener el índice de refracción alrededor del alambre y, posteriormente, el perfil de temperatura. Las mediciones de los perfiles de temperatura se realizaron en cuatro alturas de la base del alambre, de manera de poder visualizar el comportamiento a lo largo del alambre. Los datos obtenidos se compararon con las mediciones hechas mediante un termopar en el mismo experimento y finalmente a través de un modelo teórico.
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    Monte Carlo Evaluation of the Uncertainty in a Calibrated Instrument
    (IEEE, 2019) Lira Canguilhem, Ignacio
    A Monte Carlo procedure is presented for computing the joint state-of-knowledge probability distribution to be assigned to the parameters of a calibration function. The procedure is fully in line with the approach in Supplement 1 to the Guide to the Expression of Uncertainty in Measurement. It consists of propagating the joint probability distribution of the calibration quantities through the mathematical model of the measurement by which the parameters are defined. Usually this model is derived from a least-squares adjustment procedure. When the instrument is in use, we desire to obtain the probability distribution for the stimulus that corresponds to an indicated response. This goal can be accomplished by propagating the distributions for the parameters of the calibration curve, together with the distribution of the indicated response.
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    Scales of free convection around a vertical cylinder.
    (2008) Lira Canguilhem, Ignacio
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    Strain localization analysis by a combination of the Espi with a Bulge test
    (2007) Montay, Guillaume; Guelorget, Bruno; Lira Canguilhem, Ignacio; Tourneix, Marie; François, Manuel; Vial Edwards, Cristián; Gdoutos, E. E.
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    The Cosine Error: A Bayesian Procedure for Treating a Non-repetitive Systematic Effect
    (2016) Lira Canguilhem, Ignacio; Grientschnig, Dieter