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One major problem in the design of ultrasonic transducers results from a huge impedance mismatch between piezoelectric ceramics and the loading medium (e.g. gaseous, liquid, and biological media). Solving this problem requires the use of a matching layer (or layers). Optimal selection of materials functioning as matching layers for piezoelectric transducers used in transmitting and receiving ultrasound waves strictly depends on the type of the medium receiving the ultrasound energy. Several methods allow optimal selection of materials used as matching layers. When using a single matching layer, its impedance can be calculated on the basis of the Chebyshev, DeSilets or Souquet criteria. In the general case, the typically applied methods use an analogy to a transmission line in order to calculate the transmission coefficient T. This paper presents an extension of transmission coefficient calculations with additional regard to the attenuation coefficients of particular layers. The transmission coefficient T is optimised on the basis of a genetic algorithm method. The obtained results indicate a significant divergence between the classical calculation methods and the genetic algorithm method. [ABSTRACT FROM AUTHOR]

This paper addresses the problem related to the interpretation of the results of actual snowfall measurements performed with two different configurations of the compensation methods for changeable climatic conditions. The paper also presents the operating principle of an ultrasound sensor for monitoring snow layer (on the air-side). In particular, the paper includes a graphic representation of the results of measurements performed in measurement stations located in Poland and at Spitsbergen. The two compensation methods (temperature and parametric) were tested for their effectiveness in different, changeable climatic conditions. The measurement results confirm that the applied compensation methods are useful in minimizing the measurement error for snow layer thickness measured on the air-side. [ABSTRACT FROM AUTHOR]

In this paper, a method for estimating snow pressure reflection coefficient based on non-contact ultrasound examination is described. A constant frequency and air-coupled ultrasound pulses were used in this study, which incorporates a parametric method for reflected energy estimation. The experimental part was carried out in situ in the Antarctic, where the snow parameters were measured along with meteorological data. The proposed method represents a promising alternative for estimating the snow-water equivalent, since it uses a parametric approach, which does not require measurements of absolute values for acoustic pressure. [ABSTRACT FROM AUTHOR]