Among other applications, the Grupo de Tratamiento de Señal (GTS) of the Universidad Politécnica de Valencia has traditionally researched in the field of non-destructive testing using ultrasounds. The GTS has developed sophisticated algorithms about processing signals for further detection and characterization in scattering materials.

The ultrasonic inspection process implies getting a register or signal using an ultrasound pulser-receiver equipment. This register is further processed in order to get information about the material. The compilation of characteristics can be done by computing temporary parameters and/or of frequency about the obtained registers. These parameters contain information related to physics properties of the materials and that will be finally susceptible of being used to classify and characterize the material.

The aim of this PhD thesis is to expand the set of parameters that this group has been using in a traditional way. The new parameters propose a change of perspective by using techniques based on a digital image processing. The thesis shows a collection of shape and geometric descriptors that will be applied to the images got from the time-frequency diagrams. Theses parameters will be applied with the parameters that were part of the traditional model, or modified versions of these ones, to the ultrasonic characterization of soft scattering materials.


The PhD thesis presents a common mathematical model for the materials that have been evaluated in this research. The ultrasonic register obtained from the ultrasonic inspection is then modeled in the frequency domain. With the purpose of carrying the spectral analysis of the ultrasonic signal, different methods are considered and studied, besides, different alternatives for the computation and improvement of the time-frequency diagrams are discussed.

A study about the frequently used parameter estimators in the frequency domain has been done. Moreover, we have proposed some modifications of these estimators from the digital image processing point of view. Besides, a suitable simulator for the mathematical model presented has been developed. The objective of the simulator is to perform a comparative between the conventional estimators and their corresponding modified and the checking of the effectiveness of the improvement proposals.

Finally, a study of shape and geometric descriptors proposed in this PhD thesis is realized and its utility to the characterization of different kinds of soft scattering materials is validated. It has been also proved the utility of the new set of proposed parameters so as to characterize these types of materials.