This article presents an original method of B/A measurement with a single plane transducer used in pulse-echo mode. To determine the best conditions of measurement, we use an ideal model with a new solution for the second harmonic. We take into account the phenomena of attenuation and diffraction. Experiments validate simulations in the case of comparative method measurement. Then we present a device to improve the detection of the second harmonic. Thus measurement of the B/A parameter of ethanol and glycerol validates this device and we also show the possibility of its use in nonlinear imaging with a weak excitation.

Pulse-echo measurement of nonlinear B/A parameter

Non-metallic articles are sensitized for deposition of adherent metal from electroless metal solutions in contact therewith by treatment with a first medium including a compound or combination of compounds containing an element which in one of its states is catalytically active to electroless metal deposition thereby adsorbing on the surface in situ the element(s) and/or compound(s); thereafter treating the surface with a second medium to decrease the solubility of the compound or combination of compounds and/or simultaneously removing the excess; and simultaneously or subsequently, if necessary, treating the surface with one or more agents to transfer said element(s) into a catalytically-active state.

A behavioural description with VHDL-AMS of a piezo-ceramic ultrasound transducer based on the Redwood's model.

Piezoelectric materials are commonly used in many applications. Different approaches were developped to predict the piezoelectric transducer behaviour. Among them, the resolution of piezoelectric equations by numerical methods is currently used. Another method is based on the equivalent electrical circuit simulation : Pspice or VHDL-AMS tools. This paper proposes a comparison between VHDL-AMS and Pspice models for a pulse echo ultrasonic system. The simulation is based on the Redwood model and its parameters are deduced from the transducer acoustical characteristics. The electrical behaviour of the proposed model is in very good agreement with the real system behaviour.

Comparison between VHDL-AMS and PSPICE modeling of ultrasound measurement system for biological medium

We present an implementation of the nonlinear propagation in an ultrasonic measurement modelling with VHDL-AMS–IEEE-1046-1999 language. The system is dedicated to nonlinear mediums characterization by a compared method measurement. Usual modelling of ultrasonic transducers are based on electrical analogy and are not simulated in the global measurement environment. The ultrasonic transducer modelling proposed is simulated with the nonlinear acoustic load and electronic excitation. The nonlinear B/A parameter is used to characterize medium with a comparative method. The measurement cell is composed of two piezoelectric ceramic transducers which are implemented with the Redwood’s electric scheme. The analyzed medium is placed between the transducers and modeled to take into account the nonlinear propagation with the B/A parameter. The usual transmission line model has been modified to take into account the nonlinear propagation for a one dimensional wave. Results obtained with simulation of mediums characterization with (blood, milk, liver and human fat tissue) showed good a modeling in agreement between modelling and experimental measurement, also a maximum error of about 12.5%.

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M. Nadi

Papers

Modelling and simulation of ultrasound non linearities measurement for biological mediums