1984 年 40 巻 12 号 p. 805-813
The comlexity of vibration in acoustic vibrating systems and its measures have been studied by introducing and modifying the concept of entropy. Here, entropy H and energy-entropy product K by our definition are found to be naturally derived from thermodynamic entropy, from the thermodynamic point of view. Consequently, four measures of efficiency (i. e. , η, κ, γ, δ) are deductively obtained, and are applied to string and rectangular plate vibrations excited randomly. It is now essential to deal with thermodynamic adaptability and with relationships between complexity of vibration and thermodynamic work against fields around vibrating objects. Therefore we analyze (as a consideration), using all the above measures along with the concepts of essergy and exergie efficiency, experimental data from R. M. Fand et al. , meauring thermoacoustic vibration of a heated aluminum beam inserted in stationary sound fields consisting of plane waves. Throughout the present paper the mode theory is employed as a theoretical means of analyzing vibrations. The results show that the efficiencies in string and plate vibrations increase as the driving frequency increases, and that more complex vibrations tend to produce more thermodynamic work. Furthermore, it is concluded that γ is a technological measure because of comprising Shanon'S redundancy as a special case, and that thermodynamically well matched measures are K and κ.