Browsing by Author "Lira, Ignacio"

Now showing 1 - 4 of 4
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    Assessing the Uncertainty in Transient Heat Conduction Within Large Plates, Long Cylinders, and Spheres
    (TAYLOR & FRANCIS INC, 2012) Lira, Ignacio; Campo, Antonio
    Relevant quantities in transient heat conduction within solids include the temperature distribution and the total energy released up to a given time. Expressions for these quantities are well known in the case of large plates, long cylinders, and spheres initially at a uniform temperature and subject to convective boundary conditions. Because the heat transfer coefficient usually is not known accurately, it is of interest to assess how the uncertainty associated with its estimated value propagates into the uncertainties of the local temperatures inside these three bodies and of the total energy released from them. In this paper a calculation procedure in agreement with current international recommendations is developed for this purpose.
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    Coverage intervals according to MARLAP, Bayesian statistics and the new ISO 11929 for ionising radiation measurements
    (PERGAMON-ELSEVIER SCIENCE LTD, 2012) Grientschnig, Dieter; Lira, Ignacio
    The coverage intervals stipulated by ISO 11929 (2010) for estimating the uncertainty from ionising radiation measurements of replicate samples are compared with those of MARLAP (= Multi-Agency Radiological Laboratory Analytical Protocols Manual) and of Bayesian statistics. The latter two intervals agree well despite their different concepts. Whereas for either of them the ratio of the length of the coverage interval and MARLAP's standard uncertainty grows when the number of samples decreases, no such growth arises for the interval mandated by ISO 11929 (2010). It may therefore be too short (e.g. for three samples by a factor of approximately 2). (C) 2011 Elsevier Ltd. All rights reserved.
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    Motion of a red blood cell in interference field
    (ELSEVIER, 2009) Alfredo Viera, Luis; Lira, Ignacio; Soto, Leopoldo; Pavez, Cristian
    The motion of a red blood cell suspended in blood plasma in a two-beam plane interference Held was studied experimentally. A cw Argon Ion laser was used. A model is proposed to describe the observed motion. The model is based on a balance between the optical gradient force and the drag force, and yields the location of the cell as a function of time, starting from a stationary position at an arbitrary distance from a dark fringe until becoming trapped at the center of the closest bright fringe. it is suggested that the discrepancy between the predictions of the model and the observed motion is attributable to the influence of the wall close to which the cell flows. (C) 2008 Elsevier B.V. All rights reserved.
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    Non-informative priors in GUM Supplement 1
    (ELSEVIER SCI LTD, 2011) Lira, Ignacio; Grientschnig, Dieter
    Supplement 1 to the 'Guide to the Expression of Uncertainty in Measurement' (GUM S1) proposes a Monte Carlo method for the propagation of the probability density functions (PDFs) assigned to the input quantities that are related to an output quantity through a measurement model. Guidance is provided in GUM Si for assigning PDFs to the input quantities for which data but no prior knowledge are available. The procedure relies on Bayes' theorem and on the use of appropriate non-informative priors. An inconsistency in the choice of such priors is pointed out. (C) 2011 Elsevier Ltd. All rights reserved.