Equation (18) is also the Fourier Transform when the argument is rotated 90 degrees in the complex plane, and written in terms of the frequency (ratio), s = i^ = icotc, where co is the frequency of the input forcing function. The amplitude and phase angle of J as a function of frequency ratio are similar to that of the two-block system of Appendix A, as shown in Figure A-2. These transform calculations were carried out using library procedures of the Mathcad software (1989), which was found to be more convenient than an analytical inverse of equations (15-17) or a completely numerical integration of the timedependent equations. Figure 5 shows typical periodic solutions with period x = 1, where the dashed line is for the "top" at x = 0, and the solid curves are for the base at x = 1. It is seen that at the top, near the highest heat input flux, the temperature response to the largely square-wave forcing function is characteristically first order, whereas at the base the oscillation amplitude is considerably attenuated, and exhibiting
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