Objectives, experimental theory-oriented

With the reference block method the distance law of a model reflector is established experimentally prior to each ultrasonic test. The reference reflectors, mostly bore holes, are drilled into the reference block at different distances, e.g. ASME block. Prior to the test, the reference reflectors are scanned, and their maximised echo amplitudes are marked on the screen of the flaw detector. Finally all amplitude points are connected by a curve. This Distance Amplitude Curve (DAC) serves as the registration level and exactly shows the amplitude-over-distance behaviour" of the reference reflector for the probe in use. Also the individual characteristics of the material are automatically considered. However, this curve may only be applied for defect evaluation, in case the reference block and the test object are made of the same material and have undergone the same heat treatment. As with the DGS-Method, the value of any defect evaluation does not consider the shape and orientation of the defect. The reference block method is safe and easy to apply, and the operator need not to have a deep understanding about the theory of distance laws. 

Mathematics plays a less dominant role in chemistry. Mostly mathematics has entered chemistry via physics. Physics-based quantum chemistry is so widely accepted as a theoretical device in chemistry that the term quantum chemistry is almost a synonym for theoretical chemistry. In general, quantum chemistry is used to generate numbers that can be compared with numerical values of experimental results concerning discrete molecular objects. Like the other physics-oriented theories in chemistry, quantum chemistry is not a true chemical theory, since it can not be used for the direct solution of chemical problems, but it provides physical data of molecules that may be used indirectly to interpret and to predict the chemical properties and behaviour of molecular systems. 

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