Studies on the second-harmonic generations in cubical quantum dots with applied electric field

The second-harmonic generation (SHG) coefficient for cubical quantum dots (CQDs) with the applied electric field is theoretically investigated. Using the compact density-matrix approach and the iterative method, we get the analytical expression of the SHG coefficient. And the numerical calculations for the typical GaAs/AlAs CQDs are presented. The results show that the SHG coefficient can reach the magnitude of 10⁻⁵ m/V, about two orders higher than that in spherical quantum dot system. More importantly, the SHG coefficient is not a monotonic function of the length L of CQDs as well as the applied field F. If we select suitable values of F and L, we will get a higher value of the SHG coefficient. In addition, the relaxation rate also affects the SHG coefficient obviously.     

Experimental investigation on resistance characteristics in micro/mini cylinder group

Friction factors associated with forced flow of de-ionized water over staggered and in-line micro/mini cylinder group plates with 3.5 mm width and 40 mm length, which are made of micro/mini cylinders with hydraulic diameter of 0.5 mm and the heights of 1.0 mm, 0.75 mm, 0.5 mm and 0.25 mm, respectively, have been experimentally investigated over Reynolds number ranging from 25 to 800. The flux and the pressure drop between the inlet and the outlet of micro/mini cylinder group are measured and the experimental results are compared with those of convectional correlations. The investigation shows the value of fRe is approximately the constant in micro/mini cylinder group plates when the flow is purely laminar state. Except test sections with 0.25 mm cylinder height, the values of fRe for other test sections increase when Re > 100, as the results of the appearance of vortex resistance, the enhancement of stream pulse and the acceleration of stream frequency. For test section with 0.25 mm cylinder height, the values of fRe rapidly and oscillatingly increase at Re > 150 due to the influence of the scale effect, tip clearance effect and the roughness effect on the cylinder surface and bottom of micro/mini cylinder group plates. The friction factor in a staggered array is much larger than that at in-line array for micro/mini cylinder group plates and the higher the cylinder height is, the lower the friction factor becomes.     

ELECTRONIC AND MAGNETIC PROPERTIES OF La_(0.7-x_Pr_xSr_(0.3)MnO_3

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