Measurement of characteristic parameters of ultrasonic flaw detectors
In order to guarantee the liability and accuracy of ultrasonic flaw detectors, a system is developed for measuring the characteristics of ultrasonic flaw detectors. The parameters which evaluate the characteristics of the pulse excitation circuit include pulse amplitude voltage, pulse rise time, pulse duration, pulse repetition frequency, peak frequency, bandwidth and output impedance. The parameters which evaluate the characteristics of the amplifier circuit include cut-off frequency, pass band, dynamic range, input impedance and equivalent input noise. The parameters which evaluate the coupling characteristics of these two circuits include crosstalk and blocking time during transmission.
A universal attachment for standard ultrasonic flaw detectors and thickness gages
A brief analysis of facilities for nondestructive testing with the use of a contactless EMA method of exciting and detecting ultrasonic vibrations has been performed. A universal electromagnetic-acoustic (EMA) attachment for standard ultrasonic flaw detectors and thickness gages is described. The characteristics of the attachment and its main components—devices for generating radio signals, a generator of probe pulses, a preamplifier, a generator of biasing pulses, and EMA transducers—are presented. Examples of the use of this attachment are given.
Direct evidence for the single cell origin of mouse liver cell tumours.
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