An inverse problem for thermal diffusivity estimation with the photoacoustic spectroscopy

Ratamero, L A; Cella, N.; Neto, Antônio José da Silva

doi:10.1088/1742-6596/135/1/012086

Cited by 3 publications

(2 citation statements)

References 15 publications

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“…The development of simple systems for measuring this parameter is a matter of interest because of a commercial equipment as a differential scanning calorimeter is high cost and the analytical methods and calculations are restricted to initial conditions and temperature ranges; on the other hand, the thermal relaxation technique is one of the most simple and functional method [4], [5]. This Cable wall bushing method is based on the disturbance of the state of thermodynamic equilibrium by means of constant illumination of the sample suspended adiabatically, inside a vacuum chamber; the variation of the sample absolute temperature is measured as a function of time [6].…”

Section: The Fundamentals Of Heat Transfer Were Established Bymentioning

confidence: 99%

Specific heat measurement of organic and conventional coffee samples by thermal relaxation

2019

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The specific heat at constant pressure (Cp) is a necessary thermal parameter in the description of the heat transport in a material, related to the adaptation to changes of temperature, which is very important in the valuation and inspection of inputs for the construction, adhesives, insulators thermal and electronic devices. In this work, a thermal relaxation system with infrared thermometry was used to determine the Cp of green coffee beans, measuring the temperature of the material placed inside a vacuum chamber that reaches a pressure of 10-2 Torr. The sample was heated by radiation with laser light and the data was obtained by means of an acquisition card. The calibration of the system was made comparing the values obtained of Cp of Zinc, Tungsten, Titanium and Steel sheets with those reported and similarity was found. This method was used to measure the Cp of samples of organic and conventional coffee; these values were subjected to an analysis of variance and significant differences were found with a confidence level of 95 %. This technique could be used for the discrimination of organic coffee in the certification process.

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Section: The Fundamentals Of Heat Transfer Were Established Bymentioning

confidence: 99%

Specific heat measurement of organic and conventional coffee samples by thermal relaxation

2019

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“…Except for a few very simple problems, these inverse problems are formulated implicitly and written as optimization problems that try to minimize an objective function. The inherent illposedness of inverse problems typically requires the use of a regularization technique that implies in the addition of a regularization function to the original objective function, weighted by an unknown regularization parameter [6,7,[11][12][13]. Several heuristics that mimic natural behaviors have been proposed for the solution of optimization problems, particularly to cope with search spaces that present local minima.…”

Section: Introductionmentioning

confidence: 99%

A pre-regularization scheme for the reconstruction of a spatial dependent scattering albedo using a hybrid ant colony optimization implementation

Stephany

Becceneri

Souto

et al. 2010

Applied Mathematical Modelling

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a b s t r a c tThis work presents a regularization technique applied to an inverse radiative transfer problem formulated as a finite dimensional optimization problem and solved by a hybridization of the ant colony optimization (ACO) with the Levenberg-Marquardt method. It is considered a one-dimensional isotropically-scattering medium with finite optical thickness, space dependent scattering albedo and plane-parallel geometry. The direct radiative transfer problem models transmission of radiation through this medium by the linear version of the Boltzmann equation considering polar angle discretization and azimuthal symmetry. A discrete ordinates method combined with the finite difference method is employed to solve it. Reconstruction of the albedo profile is performed from the intensities of the polar-discretized emergent radiation acquired with external detectors, using a recently proposed regularization technique. Since smooth albedo profiles are expected, such information is used in a new generation of ants in order to perform a pre-selection of the ants. This scheme can be viewed as a kind of pre-regularization in face of the reconstructed profiles that are smooth and show good agreement with the exact solution. In addition, this scheme saves processing time as fewer candidate solutions (ants) are evaluated. Noiseless and noisy data of the emergent radiation intensities were employed in the reconstructions.

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Optical and Thermal Characterization of High Reflective Surface with Applications in Thermal-Solar Technology

Macías

Rincon

Lizama-Tzec

et al. 2014

Latin America Optics and Photonics Conference

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An inverse problem for thermal diffusivity estimation with the photoacoustic spectroscopy

Cited by 3 publications

References 15 publications

Specific heat measurement of organic and conventional coffee samples by thermal relaxation

Specific heat measurement of organic and conventional coffee samples by thermal relaxation

A pre-regularization scheme for the reconstruction of a spatial dependent scattering albedo using a hybrid ant colony optimization implementation

Optical and Thermal Characterization of High Reflective Surface with Applications in Thermal-Solar Technology

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