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991.
A new SPICE subcircuit model for power p-i-n diodes is proposed in this paper. The model is based on a moment-matching approximation of the ambipolar diffusion equation. It is shown that both the quasistatic model and the lumped charge model can be obtained as ion-order moment-matching approximations while new and more accurate models can be obtained from higher-order solutions. The proposed model takes into account emitter recombination in the highly doped end regions, conductivity modulation in the base and the moving-boundaries effect during reverse-recovery, showing good convergence properties and fast simulation times. Comparisons between the results of the SPICE model and both numerical device simulations and experimental results are presented 相似文献
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T.J.L. McComb A.B. Rimmer M.L.B. Rodgers K.E. Turver A.F. Vickers 《Cold Regions Science and Technology》1992,20(3)
A mathematical model for predicting the temperature in a homogeneous layer of dry snow is presented. The model, which is physically based, is capable of predicting diurnal temperature behaviour at the snow surface and at any depth within a snow layer given the variation in a limited set of meteorological parameters over that period. A sensitivity analysis is performed to determine the important parameters in the prediction of snow surface temperatures. These are found to be consistent with simple physical reasoning. 相似文献
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We synthesized new composite particles for hydrogen storage on the basis of an idea of “particle designing”. As starting materials, powders of Mg and YNi2 were selected. Fine composite particles containing mainly Mg2Ni could be designed by repetitive hydriding and dehydriding cycles at 673 K. In the synthesis process of the composite particles, the following two points were found to be essential for this technique. The first point is that, after being activated by the sequential processes of hydrogenation, amorphization and disproportionation, YNi2 reacts effectively with Mg. The second point is that evaporated Mg, which occurs during dehydriding, adheres to the surface of the activated YNi2 and accelerates a diffusion reaction to form Mg2Ni at the interface. In these composite particles, Mg2NiH4 is formed, even at 373 K, under a hydrogen pressure of 5 MPa. 相似文献
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It is demonstrated that glassy carbon powder can be thermochemically activated. During activation, a film with open pores is created on the glassy carbon particles. This film has a large internal surface area, which is accessible to liquids and gases. A simple model for the evolution of the internal surface area in glassy carbon powder during thermochemical gas-phase oxidation is also presented and compared with experimental data. Experimental results are in qualitative agreement with the model. We found that a sharp particle size distribution is desirable with regard to potential technical applications. 相似文献