Online evolution of a phased array for ultrasonic imaging by a novel adaptive data acquisition method.

Ultrasonic imaging, using ultrasonic phased arrays, has an enormous impact in science, medicine and society and is a widely used modality in many application fields. The maximum amount of information which can be captured by an array is provided by the data acquisition method capturing the complete data set of signals from all possible combinations of ultrasonic generation and detection elements of a dense array. However, capturing this complete data set requires long data acquisition time, large number of array elements and transmit channels and produces a large volume of data.

Phased Array Ultrasonic Method for Robotic Preload Measurement in Offshore Wind Turbine Bolted Connections.

This paper presents a novel approach for preload measurement of bolted connections, specifically tailored for offshore wind applications. The proposed method combines robotics, Phased Array Ultrasonic Testing (PAUT), nonlinear acoustoelasticity, and Finite Element Analysis (FEA). Acceptable defects, below a pre-defined size, are shown to have an impact on preload measurement, and therefore conducting simultaneous defect detection and preload measurement is discussed in this paper.

A shear horizontal phased array steering excitation technique for remnant wall thickness quantification.

Precise wall loss quantification in pipe and plate structures is a critical and challenging task, especially in cases where direct access to the component is limited. Accurate knowledge of the remaining wall thickness allows for timely maintenance or replacement to avoid catastrophic failures. In this work, wall loss quantification is performed utilizing the cut-off frequency of mode SH1.

Automated Real-Time Eddy Current Array Inspection of Nuclear Assets.

Inspection of components with surface discontinuities is an area that volumetric Non-Destructive Testing (NDT) methods, such as ultrasonic and radiographic, struggle in detection and characterisation. This coupled with the industrial desire to detect surface-breaking defects of components at the point of manufacture and/or maintenance, to increase design lifetime and further embed sustainability in their business models, is driving the increased adoption of Eddy Current Testing (ECT). Moreover, as businesses move toward Industry 4.

A Novel Complete-Surface-Finding Algorithm for Online Surface Scanning with Limited View Sensors.

Robotised Non-Destructive Testing (NDT) has revolutionised the field, increasing the speed of repetitive scanning procedures and ability to reach hazardous environments. Application of robot-assisted NDT within specific industries such as remanufacturing and Aersopace, in which parts are regularly moulded and susceptible to non-critical deformation has however presented drawbacks. In these cases, digital models for robotic path planning are not always available or accurate.

Sensor-Enabled Multi-Robot System for Automated Welding and In-Process Ultrasonic NDE.

The growth of the automated welding sector and emerging technological requirements of Industry 4.0 have driven demand and research into intelligent sensor-enabled robotic systems. The higher production rates of automated welding have increased the need for fast, robotically deployed Non-Destructive Evaluation (NDE), replacing current time-consuming manually deployed inspection.

Design of 2D Sparse Array Transducers for Anomaly Detection in Medical Phantoms.

Aperiodic sparse 2D ultrasonic array configurations, including random array, log spiral array, and sunflower array, have been considered for their potential as conformable transducers able to image within a focal range of 30-80 mm, at an operating frequency of 2 MHz. Optimisation of the imaging performance of potential array patterns has been undertaken based on their simulated far field directivity functions. Two evaluation criteria, peak sidelobe level (PSL) and integrated sidelobe ratio (ISLR), are used to access the performance of each array configuration.

Determination of Bubble Size Distribution Using Ultrasound Array Imaging.

In this article, ultrasonic phased arrays are deployed as an imaging tool for industrial process analysis. Such arrays are typically used for sonar, medical diagnosis, and nondestructive testing; however, they have not yet been applied to industrial process analysis. The precise positioning of array elements and high frequencies possible with this technology mean that highly focused images can be generated, which cannot currently be achieved using ultrasound tomography.

Broadband 1-3 Piezoelectric Composite Transducer Design Using Sierpinski Gasket Fractal Geometry.

Wider operational bandwidth is an important requirement of an ultrasound transducer across many applications. In nature, it can be observed that several hearing organs possess a broad operating bandwidth by having a varying length scales structure. Moreover, conventional 1-3 piezoelectric composite transducers have been widely recognized for their wider bandwidth over their piezoelectric ceramic counterparts.

The detection of flaws in austenitic welds using the decomposition of the time-reversal operator.

The non-destructive testing of austenitic welds using ultrasound plays an important role in the assessment of the structural integrity of safety critical structures. The internal microstructure of these welds is highly scattering and can lead to the obscuration of defects when investigated by traditional imaging algorithms. This paper proposes an alternative objective method for the detection of flaws embedded in austenitic welds based on the singular value decomposition of the time-frequency domain response matrices.

Features in geometric receiver shapes modelling bat-like directivity patterns.

The directional properties of bat ears as receivers is a current area of interest in ultrasound research. This paper presents a new approach to analyse the relationship between morphological features and acoustical properties of the external ear of bat species. The beam pattern of Rousettus leschenaultii's right ear is measured and compared to that of receiver structures whose design is inspired by the bat ear itself and made of appropriate geometric shapes.

A model-based approach to crack sizing with ultrasonic arrays.

Ultrasonic phased array systems have become increasingly popular in the last 10 years as tools for flaw detection and characterization within the nondestructive testing industry. The existence and location of flaws can often be deduced via images generated from the data captured by these arrays. A factor common to these imaging techniques is the subjective thresholding required to estimate the size of the flaw.

Alignment of nanostructured tripeptide gels by directional ultrasonication.

We demonstrate an in situ ultrasonic approach to influence self-assembly across the supramolecular to micron length scales, showing enhancement of supramolecular interactions, chirality and orientation, which depends on the peptide sequence and solvent environment. This is the first successful demonstration of using oscillating pressure waves to generate anisotropic organo- and hydrogels consisting of oriented tripeptides structures.

A fractional Fourier transform analysis of the scattering of ultrasonic waves.

Many safety critical structures, such as those found in nuclear plants, oil pipelines and in the aerospace industry, rely on key components that are constructed from heterogeneous materials. Ultrasonic non-destructive testing (NDT) uses high-frequency mechanical waves to inspect these parts, ensuring they operate reliably without compromising their integrity. It is possible to employ mathematical models to develop a deeper understanding of the acquired ultrasonic data and enhance defect imaging algorithms.

Computationally efficient solution of Snell's law of refraction.

An algorithm for an efficient parallel implementation of Snell's law of refraction, applicable to planar interfaces, is found by algebraic manipulation. The algorithm is tailored for general-purpose graphics processing unit (GP-GPU)-type processors. Numerical singularity in the solution is addressed.

Application of conformal map theory for design of 2-D ultrasonic array structure for NDT imaging application: a feasibility study.

Two-dimensional ultrasonic phased arrays are becoming increasingly popular in nondestructive evaluation (NDE). Sparse array element configurations are required to fully exploit the potential benefits of 2-D phased arrays. This paper applies the conformal mapping technique as a means of designing sparse 2-D array layouts for NDE applications.

Review of high-power ultrasound-industrial applications and measurement methods.

Applications involving high-power ultrasound are expanding rapidly as ultrasonic intensification opportunities are identified in new fields. This is facilitated through new technological developments and an evolution of current systems to tackle challenging problems. It is therefore important to continually update both the scientific and commercial communities on current system performance and limitations.

A beam based method for target localization: inspiration from bats' directivity and binaural reception for ultrasonic sonar.

The process of echolocation is accomplished by bats partly using the beam profiles associated with their ear shapes that allow for discrimination between different echo directions. Indeed, knowledge of the emitted signal characteristic and measurement of the echo travel time from a target make it possible to compensate for attenuation due to distance, and to focus on filtering through the receivers' beam profiles by comparing received echoes to the original signal at all frequencies in the spectrum of interest. From this basis, a beam profile method to localize a target in three-dimensional space for an ultrasonic sensor system equipped with an emitter and two receivers is presented.

An investigation of acoustic beam patterns for the sonar localization problem using a beam based method.

Target localization can be accomplished through an ultrasonic sonar system equipped with an emitter and two receivers. Time of flight of the sonar echoes allows the calculation of the distance of the target. The orientation can be estimated from knowledge of the beam pattern of the receivers and the ratio, in the frequency domain, between the emitted and the received signals after compensation for distance effects and air absorption.

Simulation and measurement of nonlinear behavior in a high-power test cell.

High-power ultrasound has many diverse uses in process applications in industries ranging from food to pharmaceutical. Because cavitation is frequently a desirable effect within many high-power, low-frequency systems, these systems are commonly expected to feature highly nonlinear acoustic propagation because of the high input levels employed. This generation of harmonics significantly alters the field profile compared with that of a linear system, making accurate field modeling difficult.

A theoretical investigation of chirp insonification of ultrasound contrast agents.

A theoretical investigation of second harmonic imaging of an Ultrasound Contrast Agent (UCA) under chirp insonification is considered. By solving the UCA's dynamical equation analytically, the effect that the chirp signal parameters and the UCA shell parameters have on the amplitude of the second harmonic frequency are examined. This allows optimal parameter values to be identified which maximise the UCA's second harmonic response.

Flexible ultrasonic transducers incorporating piezoelectric fibres.

It is possible to produce a high-performance, flexible 1-3 connectivity piezoelectric ceramic composite with conventional methods but the process is difficult and time-consuming. Extensive finite element modeling was used to design a piezocomposite structure which incorporated randomly positioned piezoceramic fibers in a polymer matrix. Simple manufacturing techniques were developed which resulted in the production of large numbers of fully populated fiber composites that offered performance comparable with a conventional 1-3 piezocomposite.

Theoretical analysis of ultrasonic vibration spectra from multiple particle-plate impacts.

Many industrial processes involve particles in a carrier fluid, and it is often of interest to monitor the size of these particles noninvasively. The aim of this paper is to develop a theoretical model of multiple particle-wall impact vibrations that can be used to recover the particle size from experimental data. These vibrations have been measured by an ultrasonic transducer attached to the exterior of a vessel containing a stirred-particle-laden fluid.

Estimating particle concentration using passive ultrasonic measurement of impact vibrations.

A method of obtaining particle size and concentration information, from ultrasonic transducer measurements of particle-wall interactions in a particle laden fluid, is presented. A mathematical model of the flexural vibrations of the vessel wall due to the particle impact is constructed. The key component of this model is the derivation of an analytic expression for the impact force amplitude.

Noninvasive field measurement of low-frequency ultrasonic transducers operating in sealed vessels.

This paper describes a noninvasive technique utilizing the acousto-optic effect, laser interferometry, and tomographic principles that have been implemented to measure the acoustic fields generated by low-frequency ultrasonic transducers operating into sealed, water-loaded vessels commonly used in industrial processing applications. A customized scanning frame, incorporating both linear and rotational stages, has been developed to facilitate manipulation of the laser head and vessel under evaluation. First, transmitted pressure profiles in air are predicted from surface displacement data acquired directly by laser measurement of the vibrating aperture.