Wedge Calibration

A third group of calibration procedures, the (3) direct (single step) [23-25] techniques avoids (many of) these problems. In particular, the so-called improved wedge-calibration method, in which a tip/cantilever is scanned across a calibration sample with two well-defined slopes (see Fig. 2.31), allows one to calculate the calibration factors with an error of ca. 5% [18]. 

In the wedge calibration method, a cantilever is scanned across a calibration sample with two well-defined slopes. The friction signal is recorded as a function of the applied load. At a given load L, friction and normal forces (normal force = load + adhesion A) depend on the direction of motion (Fig. 2.32). 

By solving the quadratic (2.10) for /.q, two mathematical solutions are provided (for any given load and adhesion). When substituted into (2.7) or (2.8), these yield correspondingly two values of the friction calibration factor a. As a must be identical for sloped and flat surfaces, we obtain /physical solution stands for /detailed description of the wedge calibration procedure can be found in [26, 27]. 

For measurements in liquid, an additional correction factor that corrects the effect of refraction must be considered. By multiplication with the factor naiiMiquid (n refractive index) one can conveniently rescale the values of lateral photodiode sensitivity obtained in air (6LAlr) employing, e.g., the improved wedge calibration method using a universal calibration specimen, to obtain the correct value for... 

In fig, 4 local corrosion by erosion is shown in a pipe with a bore of 100 mm behind a welding. In this case only the nominal wall thickness of the pipe is known (6.3 mm). To calibrate the obtained density changes into wall thickness changes a step wedge exposure with a nominal wall thickness of 13 mm (double wall penetration in the pipe exposure) and the same source / film system combination was used. From this a pcff = 1-30 1/cm can be expected which is used for the wall thickness estimation of the pipe image according to equation (4). 

The accuracy of the measurement of radon concentrations with bare track detectors was found to be unsatisfactory due mainly to the changes of the deposition rate of radon progeny onto the detector as a result of air turbulence. In this work, therefore, a method was developed which can correct the contributions of the deposition to the track densities by classifying the etched tracks according to their appearance, i.e. round or wedge shaped. Using this method, about 30% improvement in the error of measurements was achieved. The calibration coefficient ob tained by experiment was 0.00424 tracks/cm /h/(Bq/m ), which agreed well with the calculated value. Comparison was also made of the present method with other passive methods, charcoal and Terradex, as to their performance under the same atmosphere. 

A detailed analysis of the experimentally obtained polarization patterns allows to determine all susceptibility components of the LB films.16,49 The values of the susceptibility were calibrated using a quartz wedge ([Pg.558]

Fig. 115. Arrangements for printing intensity calibration strips on X-ray photographs. a. Sector wheel to give a stepped wedge. b. Cam to give a continuous wedge.

The Babinet compensator is a calibrated optical device comprising two wedge-shaped pieces of quartz arranged so that their optic axes, and the light path, are... 

Adapter, T type, 24/40 Adapters, hose connection with stopcocks, 24/40 joints, one inner, one outer Beaker, 30 mL Beaker, plastic, 400 mL Bottles, wash, 250 mL Card, calibration, polystyrene Cell, NaCl, sandwich Cell, NaCl, wedge Clamps, buret... 

FIGURE 5-38 Density calibration results for two wedge materials, polyetherimide and aluminum. A wedge correction function of 4% is determined. 

We performed calibration tests for three low-impedance wedge materials, polyetherimide, acrylic (Lucite), and polystyrene. Table 5-4 lists the liquids used for the calibration tests note that all of the liquids have similar densities but vary in viscosity. The calibration results are shown in Fig. 5-40, which reveals that Lucite is the best of the three as a wedge material for measuring viscosity. However, all of the measured viscosities are lower than their expected values. The discrepancies may be attributed to non-Newtonian fluid behavior, surface wetting, and poor sensitivity. 

FIGURE 5-40 Viscosity calibration data for various wedge materials. 

FIGURE 5-41 Viscosity calibration data in low-viscosity range-obtained with polyetherimide wedge and multiple reflection technique. 

Acceptance, monitoring and calibration of working and test equipment relevant to installation and quality control must be regulated in the QMM, for example the test parameters of the hot wedge welding machine such as roller pressure, hot wedge temperature, speed. Maintenance and inspection plans must be available and the actions taken must be recorded. The necessary calibration and inspection... 

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