The Experts below are selected from a list of 35391 Experts worldwide ranked by ideXlab platform

Pierre Rochette - One of the best experts on this subject based on the ideXlab platform.

  • Calibration of in situ magnetic susceptibility measurements
    Geophysical Journal International, 2004
    Co-Authors: Jérôme Gattacceca, Philippe Eisenlohr, Pierre Rochette
    Abstract:

    SUMMARY The aim of this work is to calibrate a magnetic susceptibility field probe (SM30) in order to allow measurement on natural boulders of any shape and size. This calibration was performed through measurements on pebbles of different shapes, sizes and lithologies. We model a correction Factor (Geometric Factor) that has to be applied to the SM30 measurement to obtain the real volume magnetic susceptibility of a sample of known volume. This Geometric Factor depends mostly on the volume of the sample, and to a lesser extent on its shape. We also present an original magnetic measurement scheme that provides, with three SM30 measurements at different distances, an estimation of the volume of a sample. By combining the two calibration models, it is possible to obtain the volume magnetic susceptibility of a natural sample with only three SM30 measurements, without requiring additional information such as sample volume. On the other hand, the calibration performed on a semi-infinite homogeneous body with variable measuring distance leads to a 2-D model of the SM30 response over its integration volume and allows the determination, with a sufficient number of discrete measurement at variable distance, of the thickness and susceptibility of the different layers of a composite body. Both types of calibration were successfully validated on natural or synthetic samples. Therefore the SM30 portable susceptometer appears to be a suitable instrument to perform in situ magnetic susceptibility measurement of individual boulders or to establish magnetic susceptibility profiles. In addition, the modest dimensions of the probe and the relative simplicity of the proposed measurement schemes should enable automation of the measurements that could find applications for robotic exploration of solid bodies of the solar system, for example.

  • GJI Geomagnetism, rock magnetism and palaeomagnetism Calibration of in situ magnetic susceptibility measurements
    2004
    Co-Authors: Jérôme Gattacceca, Philippe Eisenlohr, Pierre Rochette
    Abstract:

    SUMMARY The aim of this work is to calibrate a magnetic susceptibility field probe (SM30) in order to allow measurement on natural boulders of any shape and size. This calibration was performed through measurements on pebbles of different shapes, sizes and lithologies. We model a correction Factor (Geometric Factor) that has to be applied to the SM30 measurement to obtain the real volume magnetic susceptibility of a sample of known volume. This Geometric Factor depends mostly on the volume of the sample, and to a lesser extent on its shape. We also present an original magnetic measurement scheme that provides, with three SM30 measurements at different distances, an estimation of the volume of a sample. By combining the two calibration models, it is possible to obtain the volume magnetic susceptibility of a natural sample with only three SM30 measurements, without requiring additional information such as sample volume. On the other hand, the calibration performed on a semi-infinite homogeneous body with variable measuring distance leads to a 2-D model of the SM30 response over its integration volume and allows the determination, with a sufficient number of discrete measurement at variable distance, of the thickness and susceptibility of the different layers of a composite body. Both types of calibration were successfully validated on natural or synthetic samples. Therefore the SM30 portable susceptometer appears to be a suitable instrument to perform in situ magnetic susceptibility measurement of individual boulders or to establish magnetic susceptibility profiles. In addition, the modest dimensions of the probe and the relative simplicity of the proposed measurement schemes should enable automation of the measurements that could find applications for robotic exploration of solid bodies of the solar system, for example.

A C Cleland - One of the best experts on this subject based on the ideXlab platform.

  • prediction of freezing and thawing times for foods of two dimensional irregular shape by using a semi analytical Geometric Factor
    International Journal of Refrigeration-revue Internationale Du Froid, 1992
    Co-Authors: Md M Hossain, D J Cleland, A C Cleland
    Abstract:

    Abstract A new expression for a Geometric Factor for ellipsoid shapes is developed by applying semi-analytical solutions of phase-change problems with convective cooling at the surface. Testing against finite element predictions for prolate and oblate spheroids showed that the new formula is more accurate than any alternative shape Factor for practical ranges of conditions. By use of a model ellipsoid defined as having the same volume, characteristics dimension and smallest orthogonal cross-sectional area as the actual shape in conjunction with the proposed shape Factor, published experimental freezing and thawing times of three-dimensional irregular shapes are more accurately predicted that by any other shape Factor.

  • prediction of freezing and thawing times for foods of regular multi dimensional shape by using an analytically derived Geometric Factor
    International Journal of Refrigeration-revue Internationale Du Froid, 1992
    Co-Authors: Md M Hossain, D J Cleland, A C Cleland
    Abstract:

    Abstract Analytical solutions for transient heat conduction with phase change and general boundary conditions were used to calculate a Geometric Factor to take account of the effect of product geometry on freezing and thawing times for a number of regular two- and three-dimensional objects. These analytically derived formulae depend only on the Biot number and simple parameters that describe object shape. The accuracy of these formulae was demonstrated by comparisons with both large sets of experimental food freezing and thawing data and numerically calculated data. The performance of the new formulae was better than that of any previous ones and the formulae are simple to use.

Jérôme Gattacceca - One of the best experts on this subject based on the ideXlab platform.

  • Calibration of in situ magnetic susceptibility measurements
    Geophysical Journal International, 2004
    Co-Authors: Jérôme Gattacceca, Philippe Eisenlohr, Pierre Rochette
    Abstract:

    SUMMARY The aim of this work is to calibrate a magnetic susceptibility field probe (SM30) in order to allow measurement on natural boulders of any shape and size. This calibration was performed through measurements on pebbles of different shapes, sizes and lithologies. We model a correction Factor (Geometric Factor) that has to be applied to the SM30 measurement to obtain the real volume magnetic susceptibility of a sample of known volume. This Geometric Factor depends mostly on the volume of the sample, and to a lesser extent on its shape. We also present an original magnetic measurement scheme that provides, with three SM30 measurements at different distances, an estimation of the volume of a sample. By combining the two calibration models, it is possible to obtain the volume magnetic susceptibility of a natural sample with only three SM30 measurements, without requiring additional information such as sample volume. On the other hand, the calibration performed on a semi-infinite homogeneous body with variable measuring distance leads to a 2-D model of the SM30 response over its integration volume and allows the determination, with a sufficient number of discrete measurement at variable distance, of the thickness and susceptibility of the different layers of a composite body. Both types of calibration were successfully validated on natural or synthetic samples. Therefore the SM30 portable susceptometer appears to be a suitable instrument to perform in situ magnetic susceptibility measurement of individual boulders or to establish magnetic susceptibility profiles. In addition, the modest dimensions of the probe and the relative simplicity of the proposed measurement schemes should enable automation of the measurements that could find applications for robotic exploration of solid bodies of the solar system, for example.

  • GJI Geomagnetism, rock magnetism and palaeomagnetism Calibration of in situ magnetic susceptibility measurements
    2004
    Co-Authors: Jérôme Gattacceca, Philippe Eisenlohr, Pierre Rochette
    Abstract:

    SUMMARY The aim of this work is to calibrate a magnetic susceptibility field probe (SM30) in order to allow measurement on natural boulders of any shape and size. This calibration was performed through measurements on pebbles of different shapes, sizes and lithologies. We model a correction Factor (Geometric Factor) that has to be applied to the SM30 measurement to obtain the real volume magnetic susceptibility of a sample of known volume. This Geometric Factor depends mostly on the volume of the sample, and to a lesser extent on its shape. We also present an original magnetic measurement scheme that provides, with three SM30 measurements at different distances, an estimation of the volume of a sample. By combining the two calibration models, it is possible to obtain the volume magnetic susceptibility of a natural sample with only three SM30 measurements, without requiring additional information such as sample volume. On the other hand, the calibration performed on a semi-infinite homogeneous body with variable measuring distance leads to a 2-D model of the SM30 response over its integration volume and allows the determination, with a sufficient number of discrete measurement at variable distance, of the thickness and susceptibility of the different layers of a composite body. Both types of calibration were successfully validated on natural or synthetic samples. Therefore the SM30 portable susceptometer appears to be a suitable instrument to perform in situ magnetic susceptibility measurement of individual boulders or to establish magnetic susceptibility profiles. In addition, the modest dimensions of the probe and the relative simplicity of the proposed measurement schemes should enable automation of the measurements that could find applications for robotic exploration of solid bodies of the solar system, for example.

W. Allegretto - One of the best experts on this subject based on the ideXlab platform.

  • Geometric Factor for Hall mobility characterization using the van der Pauw dual configuration
    IEEE Transactions on Electron Devices, 1993
    Co-Authors: Arokia Nathan, W. Allegretto
    Abstract:

    A Geometric Factor applicable to a wide range of device geometries of the van der Pauw dual configuration is presented. Such a configuration allows a direct retrieval of the Hall mobility in a single measurement of the magnetic-field-induced imbalance in output current. In view of scaling considerations, the Geometric Factor is characterized simply in terms of device aspect ratio (L/W) and relative electrode separation (d/W). The Geometric Factor, which is based on numerical computations, overcomes the limitations inherent in the existing form that has been analytically obtained for an infinitesimally small electrode separation. Hence, it is now possible to design practical device geometries which readily lend themselves to in situ measurement and characterization of the material or process in question, without being constrained by photolithography limitations. >

Md M Hossain - One of the best experts on this subject based on the ideXlab platform.

  • prediction of freezing and thawing times for foods of two dimensional irregular shape by using a semi analytical Geometric Factor
    International Journal of Refrigeration-revue Internationale Du Froid, 1992
    Co-Authors: Md M Hossain, D J Cleland, A C Cleland
    Abstract:

    Abstract A new expression for a Geometric Factor for ellipsoid shapes is developed by applying semi-analytical solutions of phase-change problems with convective cooling at the surface. Testing against finite element predictions for prolate and oblate spheroids showed that the new formula is more accurate than any alternative shape Factor for practical ranges of conditions. By use of a model ellipsoid defined as having the same volume, characteristics dimension and smallest orthogonal cross-sectional area as the actual shape in conjunction with the proposed shape Factor, published experimental freezing and thawing times of three-dimensional irregular shapes are more accurately predicted that by any other shape Factor.

  • prediction of freezing and thawing times for foods of regular multi dimensional shape by using an analytically derived Geometric Factor
    International Journal of Refrigeration-revue Internationale Du Froid, 1992
    Co-Authors: Md M Hossain, D J Cleland, A C Cleland
    Abstract:

    Abstract Analytical solutions for transient heat conduction with phase change and general boundary conditions were used to calculate a Geometric Factor to take account of the effect of product geometry on freezing and thawing times for a number of regular two- and three-dimensional objects. These analytically derived formulae depend only on the Biot number and simple parameters that describe object shape. The accuracy of these formulae was demonstrated by comparisons with both large sets of experimental food freezing and thawing data and numerically calculated data. The performance of the new formulae was better than that of any previous ones and the formulae are simple to use.