Transmission Fluctuation Correlation Spectrometry: Characterization of Particle Suspensions and Flow StructuresXiaoai Guo
Taschenbuch
Nowadays, the study of the properties of particulate systems is becoming increasingly important and necessary in numerous processes involving the production, handling and processing of particles, so as to improve the efficiency of these systems and to permit their control. Particle size and concentration affect the properties of a particulate system in many important ways, such as the taste of food and the colour of pigments. In [1], many methods are introduced to measure particle size. The choice of methods depends on the particle properties and the situations of the real applications. For example, optical methods, such as light scattering, absorption, transmission or extinction, have the distinct advantage that the measurements can be made without disturbing suspensions and sometimes the tests can be carried out in a form which lends itself to automatic recording and remote-control techniques. This makes possible nondestructive and nonintrusive process control and product qualitymeasurement. In traditional extinction measurements, when a light beam falls upon a particle suspension, the attenuation of the light intensity can be described with Bouguer-Lambert-Beer's law ( B L B L) [2-3]. Over the recent two decades, dynamic extinction measurements have been developed further by many researchers [4-18]. Among them, Gregory [4] measured the mean particle size and concentration from the turbidity fluctuations. Wessely et al. [5-6] determined the particle size distribution ( P S D) by varying the beam size. Based on the statistical characteristics of the transmission fluctuations in flowing particle suspensions, Riebel's research group [7-18] developed a new method called transmission fluctuation spectrometry ( T F S) for particle size analysis by means of a non-linear operation on the transmission fluctuations T, e. g. , logarithm of transmission (ln T), expectancy of the transmission square ( E T S).
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