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Preparatory Notes for ASNT NDT Level III Examination - Ultrasonic Testing, UT

Preparatory Notes for ASNT NDT Level III Examination - Ultrasonic Testing

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5.13.4 More Reading: What is Neper ?<br />

The Neper (unit symbol Np) is a logarithmic unit <strong>for</strong> ratios of measurements of<br />

physical field and power quantities, such as gain and loss of electronic<br />

signals. The unit's name is derived from the name of John Napier, the<br />

inventor of logarithms. As is the case <strong>for</strong> the decibel and Bel, the Neper is unit<br />

of the International System of Quantities (ISQ), but not part of the<br />

International System of Units (SI), but it is accepted <strong>for</strong> use alongside the SI.<br />

The Neper is a natural linear unit of relative difference, meaning in Neper<br />

(logarithmic units), relative differences add, rather than multiply. This property<br />

is shared with logarithmic units in other bases, such as the Bel.<br />

http://en.wikipedia.org/wiki/Neper

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