EVALUATION OF S-WAVE AMPLIFICATION SPECTRUM USING MICROTREMORS

To evaluate the site effects above the engineering base rock with an S-wave velocity of 300m/s, microtremor measurements on the ground surface were conducted in Maizuru, Japan. An estimation method of S-wave amplification spectrum using the microtremor H/V spectral ratio was applied at the ground surface, estimating S-wave amplification spectrum without any ground information based on the microtremor measurement results. It was found that the evaluation of S-wave amplification spectrum needs a revision on the microtremor H/V spectral ratio, using some coefficients on the microtopography classification and the shape of the microtremor H/V spectral ratio.

Monte Carlo Calculations of Amplification Spectrum for GaN THz Transit-time Resonance Maser

We report Monte Carlo calculations of the amplification spectrum of microwave generation in bulk GaN and its dependence on applied electric fields, doping level, lattice temperature, etc. The amplification is shown to occur in a wide frequency range of 0.05 to 3 THz with an optimal generation efficiency of about 1 ∼ 2%.