Orientation compensation method

The just described compensation method for the parasitic birefringence of windows and polarizing prisms is also useful with respect to the parasitic birefringence created by reflections from the cylinder walls. As has been pointed out, the disturbance caused by the windows is compensated at its maximum. This means, as the test fluid possesses an extinction angle of 45°, that the extinction positions of the window birefringence are oriented parallel and perpendicular to the direction of flow (i.e. the... 

As expected, results in Fig. 15.3 show that significant fiber orientation is only achieved when the matrix is anisotropic. Similar conclusions can be drawn from birefringence measurements (made by the compensation method, using a Berek compensator) on composite films, as shown in Fig. 15.4. The birefringence is a measure of the degree of order of the matrix and therefore the good agreement between these data and those obtained from SALS (S) reveal the excellent compatibility between the matrix and the fibers, which results from a similarity between the chemical structure of both components of the composites. 

In order for a seismometer to measure true vertical and north-south, east-west horizontal motion, the verticality error due to the as-drilled borehole must be compensated for along with the north-south orientation. The methods of north-south orientation will be discussed in a later section (see section Water Egress ), with this section focusing on leveling. Since a downhole seismometer cannot be leveled manually because it is down a borehole or posthole, downhole seismometers have automatic leveling mechanisms that can adjust the sensing elements or axes to measure true vertical and horizontal motion. 

Method D. Compensating delays are introduced during the composite pulse R, whenever magnetization on an invariant trajectory is oriented along the z axis, that is, after (or during) one or several square pulses (Griesinger et al., 1988 Kerssebaum, 1990 Cavanagh and Ranee, 1992). 

Fig. 19. Plot of birefringence as measured by the compensator technique against the orientation function as measured by the sonic method. Values in parenthesis represent theoretical values for Nylon 66, cellulose, and polypropylene from top to bottom respectively...

Besides body-orientated and process engineering methods it is possible to minimise laminations, and therefore avoid defects caused by these, by optimising the design and operation of the extruder. In practice it is, however, proven time and again that bodies with a minimum tendency towards laminations are a prerequisite in the avoidance of laminations and the associated defects. Or expressed another way even the best extruder design cannot fully compensate the effects of an unfavourable body composition highly susceptible to laminations. 

In solids there are two general methods used for the determination of An. One is the transmission method while the other is a compensator technique. Each has advantages and disadvantages and thus the method chosen depends highly on the experimental circumstances as well as on the material itself. It is worth pointing out that the above discussion applies to both uniaxially and biaxially oriented systems. Two other methods not to be discussed here are interference microscopy and refractometry. ... 

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