Ultrasonic Measurement of Concentration in Solutions by a Phase-Locked Loop Method

概要

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In this paper we propose a new ultrasonic technique for measuring the concentration of solutions by a phase-locked loop method. This technique has a very simple circuit system which treats only continuous sinusoidal waves. We verify experimentally its validity and usefulness using NaCl solutions as test specimens. The accurate measurement of concentration is limited by slight changes in time temperature because of the strong temperature dependence of ultrasonic velocity in the solutions. A temperature-compensation factor for NaCl solutions is derived from the equation for ultrasonic velocity in sea water. We designed a circuit compensating for this effect and added it to the measuring system. This measuring system with the compensation circuit was shown to yield accurate values independent of a temperature variation of ±1.3℃ around 25℃.
社団法人応用物理学会の論文
1997-05-30