Propagator measurement

One example of a relatively new technique for the non-invasive, non-destructive characterization of network structures involves pulse-propagation measurements [288,289]. In this technique, the delay Af in a pulse passing through the network is used to obtain information on the network structure, for example, the chain length between cross-links or between entanglements. The technique is illustrated schematically in Figure 12 [282]. 

Sibulkin M, Lee CK. Flame propagation measurements and energy feedback analysis for burning cylinders. Combust. Sci. Technol. 1974 9 137-147. 

Further extensions of chemical mapping within a fixed bed lie in quantifying mass transfer between the intra-pellet and inter-pellet pore space. One approach to measuring mass transfer processes is to use displacement propagator measurements (see Section II.C). The data acquired for the esterification reaction described previously are shown in Fig. 31. In this propagator measurement, the total propagator measured for the system has been separated into two... 

A phase-locked loop is a bit of a hybrid of the oscillator circuit and the propagation measurement system discussed in the previous two sections. The instrumentation setup, shown in Figure 6.14 (page 374), closely resembles that used for propagation measurements. The phase is locked, or rather maintained at a constant value, in the following manner initially, before any perturbation occurs, the phase difference between the two IDTs of the AW device is recorded when a perturbation affects this phase difference, the frequency of the signal from the source is adjusted to return the phase to its initial value. In this way, the source frequency is constantly retuned to the extent dictated by the perturbation, and the phase difference between the two transducers remains locked. ... 

Acoustic (sound propagation) measurements in materials, rather than merely conventional types of mechanical tests, played an important role in developing UH. 

Rates of flame propagation measured in O2 atmosphere under different experimental conditions on a poly(methyl methacrylate) rod specimen... 

A Alomainy, Y Hao, C G Parini and P S Hall, Comparison between two different antennas for UWB onbody propagation measurements , IEEE Amentias and Wireless Propagation Letters, 2005 4 31-34. 

BR and silicone rubber (SI) by measuring the crack-tip position and EE intensity simultaneously. The former was done by using a video recorder with the camera imaging the region where the crack was propagating. Measurements of the crack position vs. time from each frame (1/60 second) allowed calculation of to values up to 20 cm/s. At a... 

Another example of a relatively new technique for the noninvasive, nondestructive characterization of network structures involves ultrasound pulse-propagation measurements. The goal here is the rapid determi-... 

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