Recent Advances in Machine Learning Applied to Ultrasound Imaging

Machine learning (ML) methods are pervading an increasing number of fields of application because of their capacity to effectively solve a wide variety of challenging problems. The employment of ML techniques in ultrasound imaging applications started several years ago but the scientific interest in this issue has increased exponentially in the last few years. The present work reviews the most recent (2019 onwards) implementations of machine learning techniques for two of the most popular ultrasound imaging fields, medical diagnostics and non-destructive evaluation. The former, which covers the major part of the review, was analyzed by classifying studies according to the human organ investigated and the methodology (e.g., detection, segmentation, and/or classification) adopted, while for the latter, some solutions to the detection/classification of material defects or particular patterns are reported. Finally, the main merits of machine learning that emerged from the study analysis are summarized and discussed. © 2022 by the authors. Licensee MDPI, Basel, Switzerland

Rapid and reliable MALDI-TOF mass spectrometry identification of Candida non-albicans isolates from bloodstream infections

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Modellazione di ceramiche piezoelettriche circolari ed applicazioni

Dottorato di ricerca in ingegneria elettronica. 11. ciclo. Coordinatore F. P. CalifanoConsiglio Nazionale delle Ricerche - Biblioteca Centrale - P.le Aldo Moro, 7, Rome; Biblioteca Nazionale Centrale - P.za Cavalleggeri, 1, Florence / CNR - Consiglio Nazionale delle RichercheSIGLEITItal

A new recognition procedure for palmprint features extraction from ultrasound images

In this work, an improved palmprint recognition system based on 3D ultrasound images is proposed and experimentally validated. The system exploits an ultrasound gel pad as coupling medium, which results much more practical and non-invasive in real applications than water. An ad hoc recognition procedure has been derived; it uses as input a 2D image of the palmprint at a fixed under skin depth and extracts main features exploing the Frost filter and a series of morphological operations. The recognition system has been preliminarily evaluated through verification experiments carried out on an ad hoc established database composed of 75 samples from 17 different volunteers

Design and Experimental Characterization of a Multifrequency Flexural Ultrasonic Actuator

In this work, a multifrequency flexural ultrasonic actuator is proposed, designed, and experimentally characterized. The actuator is composed of a Langevin transducer and of a displacement amplifier. The displacement amplifier is able to transform the almost flat axial displacement provided by the Langevin transducer at its back end into a flexural deformation that produces the maximum axial displacement at the center of its front end. Design and analysis of the actuator have been performed by using finite element method software. In analogy to classical power actuators that use sectional concentrators, the design criterion that has been followed was to design the Langevin transducer and the flexural amplifier separately at the same working frequency. As opposed to sectional concentrators, the flexural amplifier has several design parameters that allow a wide flexibility in the design. The flexural amplifier has been designed to produce a very high displacement amplification. It has also been designed in such a way that the whole actuator has 2 close working frequencies (17.4 kHz and 19.2 kHz), with similar flexural deformations of the front surface. A first prototype of the actuator has been manufactured and experimentally characterized to validate the numerical analysis

High power ultrasonic actuators based on the langevin transducer: classical configurations and recent designs

This chapter is dedicated to the ultrasonic actuators based on the Langevin transducer. The basic theory and the design criterions of the Langevin transducer alone and joined to the most popular ultrasonic concentrators are firstly presented. A recent design, which is based on a flexural displacement amplifier, is then presented and detailed analyzed

3-D Ultrasound Palmprint Recognition System Based on Principal Lines Extracted at Several Under Skin Depths

In recent years, several palmprint recognition procedures that use 3-D information on the palm surface have been proposed in order to overcome some limitations of 2-D palmprint. However, 3-D optical images provide information on the external skin surface only. Ultrasound waves have the capability to penetrate into human tissue and, therefore, can provide new kinds of 3-D information from acquired palmprints. In this paper, a 3-D ultrasound palmprint recognition system that accounts for principal line depth is proposed. It exploits several 2-D palmprints, extracted at different under skin depths with a classic procedure, opportunely combined to achieve a 3-D template. An ad hoc matching criterion is then defined in order to account for line depth information when comparing 3-D templates. Experiments of both verification and identification, performed on a homemade database, have shown that the 3-D recognition procedure exhibits very good recognition rates. The proposed 3-D technique also benefits from other advantages of ultrasound, including not being sensitive to many kinds of surface contaminations and its capability to detect liveness during the acquisition phase, which makes it very difficult to counterfeit

3D Palmprint Recognition Through Ultrasound Imaging

Biometric recognition systems based on 3D information of palmprint have been experimented with in the last years. Optical technology is the most widely used, but it provides information on the external surface only. Ultrasound, instead, allows obtaining information that accounts for principal lines depth. In this work, a 3D palmprint recognition system, based on images acquired through an Ultrasound system by using water or gel as a coupling medium between the probe and hand, is proposed and tested. In both cases, a 3D template that contains information on the depth of principal lines is generated by combining 2D templates obtained from images extracted at various under-skin depths. The performances of the system have been evaluated through verification and identification experiments on home-made databases of 633 water samples and 423 gel samples, respectively. For both cases, the 3D method reports better results than the 2D one. Furthermore, the recognition capability of the proposed system is comparable with that of the best optical system reported in the literature

A High Power Travelling Wave Ultrasonic Motor

In the present work, a traveling wave ultrasonic motor (TWUSM) is proposed. It is composed of an annular-shaped stator and two cone-shaped rotors that are pressed in contact to the borders of the inner surface of the stator. A rotating traveling wave has been generated in the stator by using as vibration generators two bolted Langevin transducers (BLT) opportunely shifted in space and in time. The vibrational behavior of the stator as well as the traveling wave generation has been simulated with the finite-element method (FEM) software. A prototype of the motoIn the present work, a traveling wave ultrasonic motor (TWUSM) is proposed. It is composed of an annular-shaped stator and two cone-shaped rotors that are pressed in contact to the borders of the inner surface of the stator. A rotating traveling wave has been generated in the stator by using as vibration generators two bolted Langevin transducers (BLT) opportunely shifted in space and in time. The vibrational behavior of the stator as well as the traveling wave generation has been simulated with the finite-element method (FEM) software. A prototype of the motor has been manufactured and experimentally characterized. It exhibits a static torque of about 0.8 Nm and a maximum angular speed of about 300 rpm. Possible variations of the present design aimed to increase output torque or minimize encumbrance are described and discussed.r has been manufactured and experimentally characterized. It exhibits a static torque of about 0.8 Nm and a maximum angular speed of about 300 rpm. Possible variations of the present design aimed to increase output torque or minimize encumbrance are described and discussed