Principles of measurement

Springer Series in Wood Science Methods in Lignin Chemistry (Edited by S.Y. Lin and C.W. Dence) 

The relationship between the energy absorbed (AE) in an electronic transition and the frequency (v) or wavelength (A) of radiation producing the transition is 

Depending on the units in which concentration c and path length b are expressed, the constant k can be e, Ejcm, or D as defined in Table 5.1.1. 

For lignin model compounds and lignin samples of known molecular weight, c is expressed in moles per liter. When the path length (b) is in centimeters, the Beer-Lambert equation becomes 

The term c (in 1 mol- cm-1) is known as the molar absorptivity. The intensity of an absorption band in the ultraviolet spectrum is usually expressed as molar absorptivity at the maximum, emax or log emax. However, the molecular 

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Acronym Full name Principle of measurement Key information... 

The permeability relative to a pure liquid, usually water, may be determined with the help of different devices that operate on the principle of measurement of filtrate volume obtained over a definite time interval at known pressure drop and filtration area. The permeability is usually expressed in terms of the hydraulic resistance of the filter medium. This value is found from ... 

PRINCIPLE OF MEASUREMENT, M MULTIPLE, S SINGLE, P POINT, R RINETIC WAVE LENGTH, F-FILTER, M MONOCHROMETER, G GRATING... 

In this section we will describe the physical principles of measurements for gravimeters of the first group. It is our pleasure to note that Prof. W. Torge gave very extensive and detailed description of both types of gravimeters that greatly helped us to prepare this and the next sections. 

Independent reference methods - one organization Two or more independent reference methods, each based on an entirely conceptually different principle of measurement, independent in theory and experimental procedure, applied in replicate, within a single organization, of the highest reputational quality, by two or more expert analysts, working independently. The methods used can, naturally, include definitive methods, and the results should be corroborated by a third or additional, independently different, accurately characterized, well established, thoroughly validated, definitive, reference, or other methods. 

The on-line viscosimeters currently available are adaptations of the classical dilute solution capillary viscosimeters. They work on the principle of measuring the pressure drop across a capillary with a differential pressure transducer. The pressure drop can be related to the reduced or inherent viscosity of the sample via Poiseuille s law.84 Intrinsic viscosity is determined using the equation ... 

On the other hand, reproducibility is the closeness of the agreement between the results of measurements of the same measurand carried out under changed conditions of measurement . The changed conditions include principle of measurement, method of measurement, observer, measuring instrument, reference standards, location, conditions of use, and time. Such variable conditions are typical for interlaboratory studies (laboratory intercomparisons). 

The abstract principle of measurement is multiplication of a continuous function by a comb function... 

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