964 resultados para George Laplace
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Scan von Monochrom-Mikroform
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Scan von Monochrom-Mikroform
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Alte Signatur: Art.Ff. 528
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Bertha Badt
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N.
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Every x-ray attenuation curve inherently contains all the information necessary to extract the complete energy spectrum of a beam. To date, attempts to obtain accurate spectral information from attenuation data have been inadequate.^ This investigation presents a mathematical pair model, grounded in physical reality by the Laplace Transformation, to describe the attenuation of a photon beam and the corresponding bremsstrahlung spectral distribution. In addition the Laplace model has been mathematically extended to include characteristic radiation in a physically meaningful way. A method to determine the fraction of characteristic radiation in any diagnostic x-ray beam was introduced for use with the extended model.^ This work has examined the reconstructive capability of the Laplace pair model for a photon beam range of from 50 kVp to 25 MV, using both theoretical and experimental methods.^ In the diagnostic region, excellent agreement between a wide variety of experimental spectra and those reconstructed with the Laplace model was obtained when the atomic composition of the attenuators was accurately known. The model successfully reproduced a 2 MV spectrum but demonstrated difficulty in accurately reconstructing orthovoltage and 6 MV spectra. The 25 MV spectrum was successfully reconstructed although poor agreement with the spectrum obtained by Levy was found.^ The analysis of errors, performed with diagnostic energy data, demonstrated the relative insensitivity of the model to typical experimental errors and confirmed that the model can be successfully used to theoretically derive accurate spectral information from experimental attenuation data. ^
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David Kaufmann
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David Kaufmann
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David Kaufmann
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Michael Graupe
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Bertha Badt
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u.a.: Bedauern über die Nichtbenutzung der von Schopenhauer vorgeschlagenen Korrekturen; kosmogonische Hypothese; Forschungen von Johann Heinrich Lambert; Laplacesche Kosmogonie; die Entstehung der Himmelskörper nach Pierre Simon Marquis de Laplace; Anfrage nach einem Autograph von Kant; Zusendung eines angeblichen Autographen Kants durch den Geheimen Justizrat Fischenich in Berlin 1821; Brief von Johann Wolfgang von Goethe;
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D.Johann Andreas Danzens
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Signatur des Originals: S 36/F02097