4a, indicating the arrival of the first core at the UT1 location.
It is noted that only the first core (PC) but not the second core (ABS) reached the UT1 location in the presented experimental conditions.
To investigate further the correlation between the ultrasonic signals observed with the UT1 and the molding cycle, the amplitude values of the [L.
2] echo measured by the UT1 and UT2 with respect to the process time were obtained.
Every time the discrepancy between TAI and UT1
becomes too big, the International Earth Rotation and Reference Systems Service (IERS) jumps into action and announces a "leap second" - usually several months in advance.
The white line circles in the figure indicate the areas corresponding to the probing end areas of UT1 and UT2 on the opposite side of the patterns.
Figure 7 shows a typical result of acquired signals with UT1 during one cycle of molding.
When the polymer arrived at the UT1 location and contacted its probing end at a process time of around 3 sec, the amplitude of the [L.
Figure 9 shows the contact times obtained by UT1 (open circles) and UT2 (closed circles) with respect to the holding pressure.