A new calculational ansatz for the quantum problem of a hydrogenlike atom in a nonresonant superintense laser field is presented. It is shown that the ground-state energy scales down from the field-free value by the ratio of the Bohr radius to the electron oscillation amplitude in the laser field.
We have carried out photoacoustic measurements of the thermal diffusivity on samples of laboratory produced chemically bleached wood pulps, as well as on samples of several commercially available papers. Our results for bleached pulps indicate that the thermal diffusivity is correlated to each of the chemical bleaching controlling parameters (the kappa number, viscosity and brightness) measured during distinct phases of the bleaching processes. Also, the values of the thermal diffusivities for the commercial papers were found to be adequate for their end uses. It turned out that photoacoustic measurements can be a valuable research laboratory and/or industrial plant tool for comparing and controlling the properties of pulp and paper and for evaluating the effects of processing parameters upon these properties.
We have developed a numerical procedure to study the transient behaviour of the temperature distribution in a solid heated by short powerful laser pulses. It is based on a three-dimensional model of the laser heating problem in which the temperature-dependent coupling between the laser pulse and the sample, and the temperature-dependent thermal characteristics of the sample, are fully accounted for. Our model calculations of temperature distributions, or any derived thermal profiles, in any space or time variables, resorted to a formulation that we developed in the form of an interactive program, based on the finite differences method, under an approach that explored the successive over-relaxation iteration procedure. Specific results are presented and discussed from the point of view of an application of the model to metals heated with a pulsed Nd:YAG laser.
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