Time scale of measurement

In the main. Priest s account meshes with the one given in this chapter. In particular, he relativizes the primary/secondary distinction to a level of description. However, there are some differences in emphasis and at least one important substantive difference between his and my accounts. First, he writes that "registering with an observer is caused (in part) by dispositional properties (or propensities) to be understood in terms of structure at the quantum level (Priest, 1989, p. 36 emphasis added). This suggests Priest is operating with a (passive) observer who simply records the quantum dispositional properties. But on the account I have offered, the structure at the quantum level, while necessary, is not sufficient by itself to account for the appearances. It is the quantum level structure plus the time scale of measurement that provides the relevant account of the properties. The same quantum system will have markedly different properties in different measuring situations. To be sure. Priest writes "in part" in the preceding quote, so perhaps the difference here would disappear if he were to spell out the partial nature of his claim. 

In DLTS, as we shall see, the time scales of measurement are typically much shorter (10- 300 msec) and fixed over the entire spectrum. Thus weak effects due to hopping conduction and leakage may be discriminated against more readily. Indeed, it will probably be possible to study these alternative kinds of equilibrating mechanisms by comparing TSCAP with DLTS methods. 

Temperature and other environmental factors affect the mechanical behavior. Thus, polymers can show all features of a glassy brittle solid, an elastic rubber, or a viscous liquid depending on the temperature and time scale of measurements. At low temperatures or high frequencies, a polymeric... 

It is clear that viscoelasticity is basically a relaxation phenomenon. The relaxation time often characterizes the behavior of the material. In comparison to the time scale of measurement, if the relaxation time is long, the material behaves as an elastic solid. If the relaxation time is very short, the material behaves as a viscous liquid. Only when the relaxation time is comparable to the time scale of measurement is the material viscoelastic. 

The voluminous literature on correlation of ultimate properties with polymer structure cannot be adequately treated here there are many excellent reviews. However, certain aspects of the ultimate properties and their dependence on the time scale of measurement and on temperature are closely allied to viscoelastic properties in small deformations, and these will be briefly discussed. 

There has been a great deal of work on elastic and dielectric properties of polymers. An important characteristic of elastic and dielectric properties of polymers is that relaxational phenomena take place with change of temperature and frequmtey (or time scale)of measurement. Therefore, the clastic and dielectric constants determined by dynamic measurements arc represented by com ricx quantities as c s c + fd and c c — ie. ... 

Equilibrium Macroscopic state of a system for which the properties are constant over the time scale of measurements and independent of the starting time of the measurements. 

The hardness of a crystal depends on its temperature, crystalline orientation, the time scale of measurement, and possibly the defect content. The hardness of cBN is shown in Figs. 23 and 24 (10,100,148-151). Although cBN is the second hardest material after diamond, its hardness (Hk 4000) appears to be only half of that of diamond (Hk 8000) and is close to the hardness of SiC and B4C (Hk 3000). Thus, cBN crystals can be polished rather easily with diamond powders. 

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