A band structure composed of a square array of parallel steel tube with narrow slits is presented.The propagation characteristic of acoustic waves in this structure is investigated theoretically by the finite element method. In particular the acoustic-solid coupling is taken into account for accurate results. The transmission coefficients of the band system with different angles of the square tubes and slits width are calculated. A large continuous band gap at a low frequency range in a compound structure is obtained due to the interaction of peaks and gaps fordifferent Structural parameters.

Based on the material properties of AlGaInP LED, this paper proposes an approach for predicting the junction temperature. The junction temperature of AlGaInP LED predicted from this study agrees with the available experimental data. The junction temperature increases with increasing the injection current and substrate thickness of LED.