1,721,079 research outputs found
A Resampling Technique to Improve the Accuracy of Temperature Signals Acquired by A/D converter Units
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Evaluation of Reliable Confidence Bounds for Sensor Calibration Curves
No full textWhen calibrating a sensor, the evaluation of the uncertainty of the estimated function is at least as
important as the numeric values of the function itself. The calibration process usually involves a least-squares
fitting, performed, for example for a thermocouple, by comparing some voltage readings with corresponding
temperatures from a reference thermometer. The aim of this work is to encourage the use of improved algorithms,
based on an extended minimization criterion, which can overcome some limitations of the classic method
The Role of Adsorption and Phase Change Phenomena in the Thermophysical Characterization of Moist Porous Materials
No full textPhase change phenomena in moist porous media with low liquid content, the typical condition of a porous body at ambient conditions and far from the contact of liquid water, are controlled by the shape of the adsorption isotherms
and by the effective liquid-vapor thermodynamic condition within the pores.
Usually, heat and mass transfer models are developed under the assumption of thermal and hygrometric equilibrium. This gives rise to an expression of the
evaporation source that is too complex in view of the dynamic identification of thermophysical and transport properties of a porous material. In this study,
the hypothesis of hygrometric equilibrium is dropped. The phase change rate is considered proportional to the amount of local nonequilibrium through an
appropriate delay coefficient. This approach leads to a simple representation of the process and makes manageable the formulation of a coupled heat and mass
transfer inverse problem. A comparison with a first group of experiments performed with an open-pore light insulating material (expanded perlite board)
confirms the suitability of the proposed approach. However, the analysis shows that, for this material, phase change occurs not far from the hygrometric equilibrium
Kalman Smoothing Technique Applied to the Inverse Heat Conduction Problem
No full textThe time-dependent surface heat flux at one boundary of a one-dimensional system is reconstructed by using the Kalman smoothing technique, given the initial temperature
distribution and the time-temperature history at an interior location. The study makes a parametric investigation and analyzes the behavior of two finite-difference schemes. The
numerical results show the very good peiformance of the proposed technique, which provides a comprehensive way for using future temperature measurements. Although in this study attention is devoted to the one-dimensional linear problem, the algorithm can be generalized
for the stochastic nonlinear multidimensional case
Un modello per il trasporto di Massa e di Energia nei Processi di Essiccazione dei Materiali Porosi
No full textInfluenza delle Condizioni Iniziali sulla Stima di Proprietà Termofisiche di Materiali con Tecniche in Transitorio
No full textInfluence of Sensor Calibration Uncertainty in the Inverse Heat Conduction Problem (IHCP)
No full textIn the inverse heat conduction problem (IHCP) of finding the temperature-dependent thermophysical properties of materials, the evaluation of the confidence region of the
unknown functions is at least as important as the numeric values of the function itself. The uncertainty of the reconstructed properties arises from various disturbances affecting the measurement instrumentation and from an imprecise mathematical description of the experiment. The aim of this work is to consider, besides the effect of random noises
superposed onto the signals, the bias arising from the calibration of the sensors. By
conceiving the calibration process as an integral part of the experiment it is possible to
quantify the effect of the above bias and to obtain better estimates and correct confidence
regians for the reconstructed properties
Lumped and Distributed Parameter Models in the Solution of Steady and Transient Heat Conduction Problems
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