Wedges

Contrast Sensitivity For monitoring purposes, a step wedge is to be used that consists of the same material as the workpiece. In addition, IQIs according to EN 462-1 or EN 462-2 - DIN wire penetrameters or step-hole IQIs - can be applied to ensure a comparability with radiography. 

F. 1 Conparison of the characteristic grey scale transmission of a) the IP scanner BAS2000 and b) the film scanner NOT Scan n(DBA Systems) for a step wedge exposure. 

Fig. 2 shows the response of a C2 film system on a step wedge (wall thickness range 2. .. 18 mm) exposed with a X-ray tube at 160 kV. For the exposure withy-rays (Irl92 or Co60) corresponding linear relationships are obtained. From this linear relationship it is followed, that the influence of the scattered radiation and the energy dependence of the absorption coefficient can be considered by an effective absorption coefficientPcff in equation (1). 

Fig.2 Film response of a Cl film system on a step wedge of St 35 and a 160 kV X-ray tube...

Fig.3 User interfaee for wall thickness evaluation based on density variations on a step wedge, the nominal wall thickness was set to 15 mm...

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 properties of the piezocomposite material mentioned above offer special benefits when the transducer is coupled to a material of low acoustic impedance. This especially applies to probes having plastic delay lines or wedges and to immersion and medical probes. These probes with piezocomposite elements can be designed to have not only a high sensitivity but also at the same time an excellent resolution and, in addition, the effort required for the probe s mechanical damping can be reduced. 

The Champ-Sons model has been developed to quantitatively predict the field radiated by water- or solid wedge- eoupled transdueers into solids. It is required to deal with interfaces of complex geometry, arbitrary transducers and arbitrary excitation pulses. It aims at computing the time-dependent waveform of various acoustical quantities (displacement, velocity, traction, velocity potential) radiated at a (possibly large) number of field-points inside a solid medium. 

Shoe Delay. Defines the shoe, or wedge, delay, in tenths of microseconds, of the prohe being used. This control is used to adjust the zero point of time interval measurement to correspond to the instant that the ultrasound pulse enters the test piece. 

For exciting the surface waves the traditional method of transforming of the longitudinal wave by the plastic wedge is used. The scheme of surface waves excitation is shown in fig. 1. In particular, it is ascertained that the intensity of the excitation of the surface wave is determined by the position of the extreme point of the exit of the acoustic beam relatively to the front meniscus of the contact liquid. The investigations have shown, that under the... 

A shear wave transducer with the height H, and the width W on the wedge and at the angle a, transmitted shear waves, at the frequency f and perpendicular to the paper. The limited plane SH Waves were transmitted to the test surface. The height H of the transducer was considered by dividing it into N pieces. On the test surface in the areafW XHl), the transducer vibrated perpendicular to the paper where Hl=H/cos , the... 

The echo directivity was influenced by the test frequency, the angle of refraction (the velocity in the wedge and the incident angle), and the height of the transducer. 

It was pointed out in Section XIII-4A that if the contact angle between a solid particle and two liquid phases is finite, a stable position for the particle is at the liquid-liquid interface. Coalescence is inhibited because it takes work to displace the particle from the interface. In addition, one can account for the type of emulsion that is formed, 0/W or W/O, simply in terms of the contact angle value. As illustrated in Fig. XIV-7, the bulk of the particle will lie in that liquid that most nearly wets it, and by what seems to be a correct application of the early oriented wedge" principle (see Ref. 48), this liquid should then constitute the outer phase. Furthermore, the action of surfactants should be predictable in terms of their effect on the contact angle. This was, indeed, found to be the case in a study by Schulman and Leja [49] on the stabilization of emulsions by barium sulfate. 

The stereochemistry is usually expressed in structure diagrams by wedged and hashed bonds. A wedge indicates that the substituent is in ont of a reference plane and a hashed bond indicates that the substituent is pointing away om the viewer (behind the reference plane). This projection is applied both to tetrahe-... 

A molecule editor can draw a chemical structure and save it, for example as a Molfile. Although it is possible to include stereochemical properties in the drawing as wedges and hashed bonds, or even to assign a stereocenter/stereogroup with its identifiers R/S or E/Z), the connection table of the Molfile only represents the constitution (topology) of the molecule. 

Similarly the stereobonds" can be defined and added to the bond list in the fourth column of the CT. A single bond acquires the value of 0 if it is not a "stereobond, 1 for np (a wedged bond). 4 for either up or down, and 6 for down (a basbed bond), The cisjtrans or E[Z configuration of a double bond is determined by the x,y.2 coordinates of the atom block if the value is 0, Tf it is 3, the double bond is either cis or tmns. In the bond block of our example (Figure 2-76), the stereocenter is set to 1 (up) at atom 6 (row 6, column 4 in the bond block), whereas the configurations of the double bonds are determined by the x,y coordinates of the atom block. 

To code the configuration of a molecule various methods are described in Section 2.8. In particular, the use of wedge symbols clearly demonstrates the value added if stereodescriptors are included in the chemical structure information. The inclusion of stereochemical information gives a more realistic view of the actual spatial arrangement of the atoms of the molecule imder consideration, and can therefore be regarded as between the 2D (topological) and the 3D representation of a chemical structure. 

The apparatus to use is seen in figure 13 which consists of a burette, thermometer, Erlenmeyer flask and a two-holed rubber stopper that has a small V-shaped wedge cut out of one side of the rubber stopper to allow the inside contents to vent. 31.5g of orangy-red fuming nitric acid (see chemicals section) is poured into the Erlenmeyer flask and the rubber stopper with its burette and thermometer is placed on to the... 

Methane is a tetrahedral molecule its four hydrogens occupy the corners of a tetra hedron with carbon at its center We often show three dimensionality m structural for mulas by using a solid wedge ) to depict a bond projecting from the paper toward you and a dashed wedge (i 111 ) for one receding away from you A simple line (—)... 

We 11 begin with cis and trans 1 4 dimethylcyclohexane A conventional method uses wedge and dash descriptions to represent cis and trans stereoisomers m cyclic systems... 

Wedge and dash drawings fail to show conformation and it s important to remember that the rings of cis and trans 1 2 dimethylcyclohexane exist m a chair conformation This... 

As represented in the wedge and dash drawing at the top of this table the molecule is already appro priately oriented Hydrogen is the lowest ranked atom attached to the chirality center and points away from us... 

Lei s relurn fo bromochlorofluoromelhane as a simple example of a chiral mole cule The Iwo enanliomers of BrClFCH are shown as ball and slick models as wedge and dash drawings and as Fischer projections m Figure 7 6 Fischer projeclions are always generated Ihe same way Ihe molecule is oriented so lhal Ihe verlical bonds al Ihe chiralily center are directed away from you and Ihe horizonlal bonds poinl toward you A projeclion of Ihe bonds onto Ihe page is a cross The chiralily center lies al Ihe center of Ihe cross bul is nol explicilly shown... 

FIGURE 7 6 Ball and spoke models [left) wedge and dash drawings [center) and Fischer projections [right) of the R and S enan tiomers of bromochloro fluoromethane... 

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