A match coefficient approach for damage imaging in structural components by ultrasonic synthetic aperture focus

Ultrasonic Synthetic Aperture Focus (SAF) techniques are commonly used to image structural defects. In this paper, a variation of SAF based on ideas borrowed from Matched Field Processing (MFP) is evaluated to reduce artifacts and sidelobes of the resulting images. In particular, instead of considering the full RF ultrasonic waveforms for the SAF time backpropagation, only selected features from the waveforms are utilized to form a “data vector” and a “replica” (expected) vector of MFP. These vectors are adaptive for the pair of transmitter-receiver and the focus point. The image is created as a matched filter between these two vectors. Experimental results are shown for an isotropic and homogenous metallic plate with simulated defects, probed by six piezoelectric patches used as receivers or transmitters

A novel method for validating multi-classifiers. A case study for ICF-based health status classification

In this paper, we propose a novel method for the validation of a multi-classification model according to the intended use and aim of a device for health status classification and the clinical needs of the practitioners involved

Usability assessment of an intraoperative planning software

Usability is a crucial aspect of medical device safety. The brand-new European Regulation requires the manufacturer to assess the usability of the new medical devices. In this study, we evaluate the usability of a new medical device intended to assist the intraoperative planning with the visualization of 3d patient-specific organ models. The usability study started from the early stage of the device design and iterated through an early formative, completed with desk-based activities, late formative, completed with a focus group, and summative phase, that comprised a user test, and questionnaire filling. The identified usability issues are mitigated, the safety of the device user interface is confirmed and the training contents are defined and confirmed. Additional information regarding the user experience is collected and analyzed to identify further improvements of the device

Current drive at plasma densities required for thermonuclear reactors

Progress in thermonuclear fusion energy research based on deuterium plasmas magnetically confined in toroidal tokamak devices requires the development of efficient current drive methods. Previous experiments have shown that plasma current can be driven effectively by externally launched radio frequency power coupled to lower hybrid plasma waves. However, at the high plasma densities required for fusion power plants, the coupled radio frequency power does not penetrate into the plasma core, possibly because of strong wave interactions with the plasma edge. Here we show experiments performed on FTU (Frascati Tokamak Upgrade) based on theoretical predictions that nonlinear interactions diminish when the peripheral plasma electron temperature is high, allowing significant wave penetration at high density. The results show that the coupled radio frequency power can penetrate into high-density plasmas due to weaker plasma edge effects, thus extending the effective range of lower hybrid current drive towards the domain relevant for fusion reactors

All you need is higher accuracy? On the quest for minimum acceptable accuracy for medical artificial intelligence

In this paper we will discuss the concept of the minimum level of accuracy an Artificial Intelligence system must exhibit in medical settings to be fit to its intended use and improve the daily practice of its intended users, the medical doctors. We will consider simple binary classification tasks in both diagnostic and prognostic ambit (like to discriminate between normal/abnormal case, and improvement/no improvement prospects). We will make the point that the common ways to determine this minimum acceptable accuracy are fraught with many conceptual and practical troubles. We will report about a small user study conducted to elicit the discriminative requirements from a sample of medical doctors, stratified both in general practitioners and specialists. Finally, we will present a simple nomogram by which to determine the minimum accuracy of a technological aid, once the human average performance and the desired level of accuracy are known. The nomogram is to be intended as a provocative simple tool to recognize that the technological tool is less important than a sound protocol in which to use it, responsibly and paying due attention to the role of the human decision makers

Ultrasonic guided wave imaging of plates containing defects and inclusions

This paper addresses the nondestructive testing of platelike structural components that are widely used in aerospace, marine, and civil structures. The objective is not only to detect and localize possible defects, but to reconstruct a picture of the plate in terms of weakened areas, considering cases with multiple defects of different depths. To do so, the minimum-variance distortionless response (MVDR) beamforming processor is applied, using a new set of weights, that improve the focus of the array by increasing the dynamic range and the spatial resolution of the image. These weights are based on the physics of the propagating Lamb modes, including the symmetric mode S0, the antisymmetric mode A0, and the shear horizontal mode SH0, taking advantage of their compounding too. The beamforming processor intensity enables to distinguish stiffer from weaker areas of the plate