Search

Purpose: The primary purpose of the study is to reconstruct the bladder based on the tomographic measurements obtained. Depending on the type of tomography used, two approaches are presented. Methods: In the first presented case, the measurements were collected using ultrasonic tomography, while in the second one, they were gathered with electrical impedance tomography. Deterministic methods and machine learning algorithms, such as Elastic Net, Least Angle Regression, and a Neural Network, were used to obtain the bladder reconstruction. Results: The bladder's position and size can be recognized based on the tomographic measurements of the UST and EIT. Both methods allow for its effective reconstruction. Discussion: The research results are satisfactory, but their effectiveness is debatable. Future studies will focus on comparing and optimizing both solutions regarding reconstruction time.

The article discusses the design of advanced embedded algorithms that aim to manage and control the measurement process using the Electrical Impedance Tomography and Ultrasonic Tomography methods. The project aims to develop solutions that optimize the performance of embedded devices that must operate on limited resources such as memory, computing power, or bandwidth. Minimizing energy consumption is an important aspect, especially for battery-powered devices. Algorithms must also be adapted to specific hardware constraints, such as low RAM or CPU limitations, which require complex engineering and optimization. Additionally, the project assumes the implementation of algorithms that consider security aspects, which is crucial in protecting data processed and transmitted by the device. It also requires the development of effective communication methods between the embedded device and other systems, including appropriate communication protocols.

Summary The main goal of the work was to develop a method for the fusion of images from two different measurement techniques. A project has been designed to integrate electrical impedance tomography (EIT) and ultrasonic tomography (UST) data. The next stage was to analyze the correlation between the EIT results and the occurrence of lower urinary tract dysfunctions and establish boundary parameters for visualization and segmentation. Additionally, the relationships between UST data and the dysfunctions were examined, which also required defining parameters for segmentation. The work also involves establishing standards and methods for the arrangement of measurement electrodes, which is crucial for the precision of both techniques. The proposed approach and results constitute an essential step towards implementing more advanced diagnostic tools to improve patient's quality of life by diagnosing lower urinary tract dysfunctions faster and more precisely.

The Greek marble statue of the Auriga of Mozia Island, in Sicily, is the most important artwork displayed at the Whitaker Foundation Archaeological Museum. It underwent geophysical investigations twice, in 2012 and 2021, to assess the marble's degradation. The 2012 investigation prepared the statue for transfer to the Paul Getty Museum in New York and repositioning on an anti-seismic pedestal. The 2021 investigation evaluated potential new damage before another transfer. Both investigations utilized 3D ultrasonic tomography (UST) to detect degraded marble areas and ground-penetrating radar (GPR) to identify internal discontinuities, such as fractures or lesions, and locate metal pins that were previously inserted to reassemble the statue and its pedestal. Results from the UST indicate an average marble velocity of approximately 4700 m/s, suggesting good mechanical strength, with some areas showing lower velocities (~3000 m/s) within the material's variability range. The GPR profiles demonstrated internal signal homogeneity, excluding internal fracture surfaces or lesions, and confirmed the presence of metallic pins. This study highlights the effectiveness of integrating UST and GPR for non-invasive diagnostics of marble sculptures, providing detailed insights into the marble's condition and identifying hidden defects or damage. [ABSTRACT FROM AUTHOR]

Background and purpose: Dynamic methods (non-destructive) tests is based on creating stress without failure in the samples and save time and costs for evaluating mechanical properties. Knots or the encapsulated branches are the most important factor in the grading of wood. Therefore, the objectives of this research are: detection of knots by non-destructive methods, measuring the dynamic modulus of elasticity of beech log using stress waves, and the effect of knot size on the speed of stress waves subsequently, and the value of dynamic modulus of elasticity. Materials and methods: The studied area was Shafarood series 11, which is located in the southern part of the Shafarood watershed, starts at an altitude of 500 meters and continues up to an altitude of 1650 meters. From this area, five beech trees were cut and divided into three equal parts of three meters by cross cutting, and according to the size of the knots, the properties of density, stress waves velocity and subsequently, the dynamic modulus of elasticity were measured. From the tangential image of the external indicator and the radial image of the internal indicator and using the Digimizer image4 software, the characteristics of each knot such as the diameter and angle of the knot were measured. For non-destructive detection of beech tree knot, ultrasonic tomography, stress wave velocity and CT scan methods were used. In the stress waves velocity method, a Fakopp microsecond timer device was used to measure the time of stress waves. In the radiographic method and to prepare CT scan images, a digital ground column device with two detectors made in France belonging to a medical clinic was used. To measure the density, 30 cylindrical stems with knots of small, medium and large classes were used, and according to the relationship between density and stress wave velocity, the value of dynamic elasticity modulus was calculated and evaluated. The diameter of the knot along the length of the stem, the density and the dynamic modulus of elasticity of the beech tree stem were measured. To analyze the data at the 95% confidence level, the one-way anova test was used, and to determine the normality of the data and the homogeneity of the variance, the Kalmograph Smirnov and Leven tests were used. To compare the means, Tukey's test was used by using SPSS software. Results: In the detection of beech tree knot with the three mentioned non-destructive methods, the results show the existence of limitations in each method. The ultrasonic tomography is not able to detect knots inside the beech tree trunk and the stress wave method also does not detect very small knots. The accuracy of the CT scan method in detecting the knot is high, but the cost of its detection is high. According to the growth stages of the beech tree, factors such as growth speed, branch encapsulation speed and natural pruning are different. The origin of the branch is pith of the stem. As a result, the number and size of the created knots are different along the tree. Therefore, most of the small knots are created in the main trunk of the tree. The diameter of the knot has also increased with the increase in the height of the stem. The knot has increased the density. The density results have shown that the samples with large, medium and small knots have significant differences. Considering that the ultrasonic tomography method is based on the reduction of density, it is not able to detect the knot. But in the radiography method, the parts with higher density are seen in light color and the parts with lower density are seen in darker color. The size of the knot is effective on reducing the speed of stress waves and thus reducing the dynamic modulus of elasticity of wood. In comparison with the samples without knots, the samples with small, medium and large knots reduce the modulus of elasticity by 20%, 50% and 70% respectively. Conclusion: In general, among the non-destructive methods, only the CT scan method is able to detect small knots and evaluate the clear wood and defects. In comparison with the control sample (without knots), increasing the size of the knot, the value of the density increases and the stress wave velocity decreases Subsequently, the dynamic elasticity modulus of the samples decreases. [ABSTRACT FROM AUTHOR]

Developing the technique of Acoustic travel time TOMography (ATOM) for monitoring the indoor air temperature and airflow measurements represents a significant breakthrough for modern buildings especially those prioritizing thermal comfort. While conventional measurement methods are limited to individual measuring points, ATOM technique can measure the climatic parameters' distribution across the entire room with high spatial resolution utilizing sound velocity measurements along various propagation sound paths. This research outlines the ongoing development of the ATOM technique for simultaneous measuring the indoor air temperature and airflow velocity at the Department of Building Physics at the Bauhaus‐University Weimar. It presents both the challenges confronted and the solutions developed in establishing a straightforward measuring system that can optimally fulfil the requirements of the indoor climate projects. [ABSTRACT FROM AUTHOR]

Non-invasive techniques, such as close-range photogrammetry (CRP) and 3D ultrasonic tomography complemented with optical and scanning electron microscopy and mercury porosimetry, were applied to characterize the carbonate rock samples of the Calcari di Cagliari formation. The integrated approach started with the computation of high-resolution 3D models of the carbonate samples using the CRP technique to produce 3D high-resolution models texturized both with natural colors and intensity. Starting from the 3D models from previous techniques, a 3D ultrasonic tomography on each rock sample was accurately planned and carried out in order to detect the elastic properties of such rocks and relate them to textural heterogeneity or internal defects. The results indicate that the relationship between longitudinal velocity and rock properties is complex even in the same carbonate formation. Understanding the relationship between the geomatic and geophysical responses in the investigated rock properties, such as textural characteristics and especially structure and geometry of pores, type of pores, tortuosity and cementing material, is important for many practical applications and especially in the diagnostic process of the conservation state of monumental structures. The integration of the above non-invasive techniques complemented by petrographical–petrophysical data proved to be a powerful method to associate each lithotype with a different susceptibility to degradation. The results presented in this paper demonstrate that the proposed integrated use of complementary methodologies would guarantee the reproducibility of the measurements both at the laboratory and field scale for the monitoring in time of the rock condition while giving a useful contribution in making decisions on an appropriate remedial strategy. [ABSTRACT FROM AUTHOR]

This paper presents the design and development of a high-resolution 3D ultrasound imaging system based on a 1 × 256 piezoelectric ring array, achieving an accuracy of 0.1 mm in both ascending and descending modes. The system achieves an imaging spatial resolution of approximately 0.78 mm. A 256 × 32 cylindrical sensor array and a digital phantom of breast tissue were constructed using the k-Wave toolbox. The signal is acquired layer by layer using 3D acoustic time-domain simulation, resulting in the collection of data from each of the 32 layers. The 1 × 256 ring array moves on a vertical trajectory from the chest wall to the nipple at a constant speed. A data set was collected at intervals of 1.5 mm, resulting in a total of 32 data sets. Surface rendering and volume rendering algorithms were used to reconstruct 3D ultrasound images from the volume data obtained via simulation so that the smallest simulated reconstructed lesion had a diameter of 0.3 mm. The reconstructed three-dimensional image derived from the experimental data exhibits the contour of the breast model along with its internal mass. Reconstructable dimensions can be achieved up to approximately 0.78 mm. The feasibility of applying the system to 3D breast ultrasound imaging has been demonstrated, demonstrating its attributes of resolution, precision, and exceptional efficiency. [ABSTRACT FROM AUTHOR]

The Greek marble statue of the Auriga of Mozia Island, in Sicily, is the most important artwork displayed at the Whitaker Foundation Archaeological Museum. It underwent geophysical investigations twice, in 2012 and 2021, to assess the marble’s degradation. The 2012 investigation prepared the statue for transfer to the Paul Getty Museum in New York and repositioning on an anti-seismic pedestal. The 2021 investigation evaluated potential new damage before another transfer. Both investigations utilized 3D ultrasonic tomography (UST) to detect degraded marble areas and ground-penetrating radar (GPR) to identify internal discontinuities, such as fractures or lesions, and locate metal pins that were previously inserted to reassemble the statue and its pedestal. Results from the UST indicate an average marble velocity of approximately 4700 m/s, suggesting good mechanical strength, with some areas showing lower velocities (~3000 m/s) within the material’s variability range. The GPR profiles demonstrated internal signal homogeneity, excluding internal fracture surfaces or lesions, and confirmed the presence of metallic pins. This study highlights the effectiveness of integrating UST and GPR for non-invasive diagnostics of marble sculptures, providing detailed insights into the marble’s condition and identifying hidden defects or damage.

The containment liner plate (CLP) is a thin layer of carbon steel material applied as a base for concrete structures protecting nuclear material. The structural health monitoring of the CLP is critical to ensure the safety of nuclear power plants. Hidden defects in the CLP can be identified utilizing ultrasonic tomographic imaging techniques such as the reconstruction algorithm for the probabilistic inspection of damage (RAPID) methodology. However, Lamb waves have a multimodal dispersion feature, which makes the selection of a single mode more difficult. Thus, sensitivity analysis was utilized since it allows for the determination of each mode's level of sensitivity as a function of frequency; the S0 mode was chosen after examining the sensitivity. Even though proper Lamb wave mode was selected, the tomographic image had blurred zones. Blurring reduces the precision of an ultrasonic image and makes it more difficult to distinguish the dimensions of the flaw. To enhance the tomographic image of the CLP, deep learning architecture such as U-Net was utilized for the segmentation of the experimental ultrasonic tomographic image, which includes an encoder and decoder part for better visualization of the tomographic image. Nevertheless, collecting enough ultrasonic images to train the U-Net model was not economically feasible, and only a small number of the CLP specimens can be tested. Thus, it was necessary to utilize transfer learning and get the values of the parameters from a pre-trained model with a much larger dataset as a starting point for a new task, rather than training a new model from scratch. Through these deep learning approaches, we were able to eliminate the blurred section of the ultrasonic tomography, leading to images with clear edges of defects and no blurred zones. [ABSTRACT FROM AUTHOR]

High early strength (HES) concrete pavements are commonly opened to traffic within the first 24 h after construction, making early-opening decisions critical for pavement quality and traffic operations. Currently, most state departments of transportation rely on compressive strength testing for early-opening decision making. However, there laboratory tests are labor intensive, costly and not always representative of field strength development. In this study, non-destructive testing (maturity and ultrasonic tomography) was explored for faster and reliable in-situ strength estimations. An experimental section constructed using HES concrete was routinely monitored using compressive testing, maturity, and ultrasonic tomography in the first 24 h after construction. The shear wave velocity, measured using ultrasonic tomography, was able to capture the strength-gain variability within a single slab and between different slabs due to the ability to monitor several locations in a short period of time. Maturity results were consistently conservative in the first 24 h of monitoring. Results show that both maturity testing and ultrasonic tomography are able to replace or add to conventional strength testing for HES concrete pavements to facilitate making the opening decision within the first 24 h. Ultrasonic tomography proved more beneficial as a result of the device's portability, increased speed of testing, and accurate estimations of HES concrete strength for the entire pavement length.

To date, increasing the speed of producing results in the form of images of defects in test objects remains an urgent problem for industrial ultrasonic tomography using post-processing of matrix antenna arrays data. One of the approaches aimed at solving this problem is the use of sparse matrix AAs. In this paper, we consider the combined application of sparse matrix transducers operating in pitch and catch mode and the post-processing algorithm that is based on the use of calculations in the frequency domain. This algorithm is based on the use of nonuniform fast Fourier transform. The effectiveness of the considered approach is confirmed experimentally. [ABSTRACT FROM AUTHOR]

Ultrasonic process tomography obtains the distribution of the two-phase flow based on ultrasound propagation in different fluids, thus is valuable to industrial monitoring and measurement. Ultrasonic process tomography can do a non-intrusively exploration of the multi-phase flow hydrodynamics. In this paper, a dual-mode ultrasonic process tomography is presented that fuses by reflection-mode tomography and time-of-flight ultrasonic tomography. In this method, a 32-digit array of ultrasonic sensors have been used for flow measurement. The two-phase flow rate that involves liquid and gas phases, have been calculated through a simple algebraic algorithm with obtained data from sensors. Simulation results depict that the measurement technique is independent of the fluid flow pattern and the system error also has been decreased. The invention of the article is about a simple algebraic method for image reconstruction which a special case is not considered in it and simultaneously, the image reconstruction error has been reduced. The relative error of the reconstructed images is presented by MATLAB simulation and it is much lower than the conventional methods. For a gas bubble with ultrasonic wave reflection time from its surface, the simulation results depict the SIE factor is less than 2%.

High early strength (HES) concrete pavements are commonly opened to traffic within the first 24 h after construction, making early-opening decisions critical for pavement quality and traffic operations. Currently, most state departments of transportation rely on compressive strength testing for early-opening decision making. However, there laboratory tests are labor intensive, costly and not always representative of field strength development. In this study, non-destructive testing (maturity and ultrasonic tomography) was explored for faster and reliable in-situ strength estimations. An experimental section constructed using HES concrete was routinely monitored using compressive testing, maturity, and ultrasonic tomography in the first 24 h after construction. The shear wave velocity, measured using ultrasonic tomography, was able to capture the strength-gain variability within a single slab and between different slabs due to the ability to monitor several locations in a short period of time. Maturity results were consistently conservative in the first 24 h of monitoring. Results show that both maturity testing and ultrasonic tomography are able to replace or add to conventional strength testing for HES concrete pavements to facilitate making the opening decision within the first 24 h. Ultrasonic tomography proved more beneficial as a result of the device's portability, increased speed of testing, and accurate estimations of HES concrete strength for the entire pavement length. [ABSTRACT FROM AUTHOR]

Copyright of Chinese Medical Equipment Journal is the property of Chinese Medical Equipment Journal Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

This paper presents the design and development of a high-resolution 3D ultrasound imaging system based on a 1 × 256 piezoelectric ring array, achieving an accuracy of 0.1 mm in both ascending and descending modes. The system achieves an imaging spatial resolution of approximately 0.78 mm. A 256 × 32 cylindrical sensor array and a digital phantom of breast tissue were constructed using the k-Wave toolbox. The signal is acquired layer by layer using 3D acoustic time-domain simulation, resulting in the collection of data from each of the 32 layers. The 1 × 256 ring array moves on a vertical trajectory from the chest wall to the nipple at a constant speed. A data set was collected at intervals of 1.5 mm, resulting in a total of 32 data sets. Surface rendering and volume rendering algorithms were used to reconstruct 3D ultrasound images from the volume data obtained via simulation so that the smallest simulated reconstructed lesion had a diameter of 0.3 mm. The reconstructed three-dimensional image derived from the experimental data exhibits the contour of the breast model along with its internal mass. Reconstructable dimensions can be achieved up to approximately 0.78 mm. The feasibility of applying the system to 3D breast ultrasound imaging has been demonstrated, demonstrating its attributes of resolution, precision, and exceptional efficiency.

The renovation project of the historic Branciforte Palace (16th–17th century) in Palermo (Italy) was owned by the Banco di Sicilia Foundation, with the aim for it to become a multi‐purpose centre for the promotion of exhibitions and cultural events. In the context of the restoration work, a multi‐methodological and non‐invasive geophysical study has been carried out. The seismic characterization of the foundation soils was obtained by means of joint interpretations of a vertical seismic profile (VSP), multichannel analysis of surface waves (MASW) and horizontal to vertical spectral ratio (HVSR) microtremor analysis. The mutually constrained inversion of seismic surveys carried out with different techniques made it possible to obtain a robust interpretation of the foundation soils. Moreover, indoor geophysical surveys have been carried out to identify critical issues in the state of conservation of the floors and wall structures. In particular ground penetrating radar (GPR) profiles and an electrical resistivity tomography (ERT) have been carried out on the floor of the stable of the Palace, to evaluate in detail the state of consolidation of the foundation soil, in correspondence of a double row of marble columns, some of which were affected by differential subsidence. The joint interpretation allowed to generate a three‐dimensional (3D) model of the foundation's subsoil, highlighting the irregular surface of the foundation rock and to identify the main structural voids responsible for subsidence. Furthermore, some supporting columns have been investigated by means of ultrasonic tomography (UST) to verify their state of degradation. Finally, infrared thermography (IRT) images of the internal and external walls and of the vaults highlighted differences in the type of masonry and in the state of the plaster. [ABSTRACT FROM AUTHOR]

Ultrasonic Shear Wave Tomography (USWT) is recommended as a modern non-destructive method that uses ultrasonic shear waves to detect objects, interfaces, and anomalies in the structure. The entire structure can be analyzed quickly and economically without destruction of any structural element. Thus, ultrasonic transition properties can be visualized in three dimensions by means of this method. In this work, results of experimental studies conducted on the effect of frequency on the analysis of the concrete by USWT are explained. The test device used in experimental studies has 24 transducers and its operating frequency range is 25-250 kHz. 50x50x22 cm sized three concrete specimens were produced in the laboratory for the experiments. Different materials were embedded in the concrete specimens to represent reinforcement and defects. Experiments were carried out at four different frequency values (25-50-100-200 kHz) on each specimen. The tomographic crosssections obtained at each frequency value were studied. The reinforcement and defects obtained in tomography sections were tried to match the known properties of placed objects in the concrete specimens. According to the results obtained in this study the accuracy of the results obtained depending on the frequency value varies according to the characteristics of the defect. The materials placed in the specimens tested at 25 kHz and 50 kHz values were determined with high accuracy whereas the values of 100 kHz and 200 kHz were only satisfactory to determine the specimen sizes, in other words, the boundaries of the concrete element. [ABSTRACT FROM AUTHOR]

In the continuous casting process, argon gas is injected into the tundish to homogenize the molten steel and remove the undesired inclusion. Furthermore, the molten steel flow is controlled by applying a magnetic field to the mold. The inclusion of argon gas as the molten steel flows into the mold can lead to product defects. Therefore, it is essential to predict the motion of the bubble in liquid metals under influence of the magnetic field, and further investigations are required for the liquid-metal two-phase flows. However, measurement techniques which can be applicable to opaque fluids such as liquid meat are limited. The authors have developed a high-speed ultrasonic tomography for measuring bubbles motion and investigated the behavior of continuously released bubbles motion in gallium alloy under influence of a horizontal magnetic field. The ultrasonic tomography measurements were carried out with 500 frames per second. It was shown that as the magnetic field strength increases, the variation of the bubble passing position in the measurement cross-section becomes smaller. Furthermore, it was confirmed that the distribution changed slightly depending on the direction of the applied magnetic field and that the bubbles tended to distribute in the direction perpendicular to the magnetic field. This trend changes depending on the difference in the gas flow rate. It is thought that the greater the influence of the wake, the more pronounced the anisotropy of the distribution. [ABSTRACT FROM AUTHOR]

Economic bridge management requires accurate information about the condition of bridges in the network. Nondestructive evaluation (NDE) has shown high potential in providing accurate condition assessment and, through periodic surveys, development of accurate deterioration, predictive, and life-cycle cost models. To achieve wide adoption by transportation agencies, further advances should be made that would lead to the accuracy of NDE-based condition assessment, reduced costs and traffic interruptions, and minimized risk to transportation workers. The paper discusses the following areas of improvement: increased speed and safety of data collection through the use of robotic systems, and improved data interpretation through visualization and joint analysis of data collected by multiple NDE technologies. [ABSTRACT FROM AUTHOR]

The critical (design) parameters to be controlled for concrete pavements construction, in addition to the concrete strength, are slab`s thicknesses and doweled bars position at contraction joints, as they affect hugely structural performance, and, if not properly built may cause early ruptures. Construction compliance of such parameters is nowadays assessed through nondestructive techniques (NDT), such as ultrasonic low-frequency waves. Alignments of inserted doweled bars at contraction joints are analyzed herein for actual slabs as well as how thickness affects such position. Tests were carried out over an airport hangar apron after it has been built. Twenty-five concrete slabs were assessed using ultrasonic tomography allowing to verify disconformities of thicknesses and bars vertical and horizontal misalignments, with fair accuracy on measuring deviation angles of bars.

A new versatile and geometrically reconfigurable ultrasonic tomography system (UTS) has been designed to inspect and obtain information about the internal structure and inner damage of columns in heritage buildings. This nondestructive system is considered innovative because it aims to overcome common limitations of existing systems. Tomographic inspections are typically carried out manually and are thus limited to small portions of construction elements. The proposed UTS allows the automatization of the inspection and the generation of numerous tomographic slices along the height of the column. It is valid for multiple types of columns and materials. In the present work, the system was tested on two limestone columns of the north façade of the Convent of Carmo in Lisbon, Portugal. The UTS is composed of a mechanical and an electronic system. The mechanical system consists of four linear motion subsystems mounted in a square setup. A transducer is placed on each of the axes, acting as emitter or receiver of the ultrasonic signals. The mechanical system also includes a guide system to adapt the inspections to the complex geometry of the columns. The electronic system allows the control and the synchronization of the movements and the emission/reception configuration of the four ultrasonic transducers. [ABSTRACT FROM AUTHOR]

A new versatile and geometrically reconfigurable ultrasonic tomography system (UTS) has been designed to inspect and obtain information about the internal structure and inner damage of columns in heritage buildings. This nondestructive system is considered innovative because it aims to overcome common limitations of existing systems. Tomographic inspections are typically carried out manually and are thus limited to small portions of construction elements. The proposed UTS allows the automatization of the inspection and the generation of numerous tomographic slices along the height of the column. It is valid for multiple types of columns and materials. In the present work, the system was tested on two limestone columns of the north façade of the Convent of Carmo in Lisbon, Portugal. The UTS is composed of a mechanical and an electronic system. The mechanical system consists of four linear motion subsystems mounted in a square setup. A transducer is placed on each of the axes, acting as emitter or receiver of the ultrasonic signals. The mechanical system also includes a guide system to adapt the inspections to the complex geometry of the columns. The electronic system allows the control and the synchronization of the movements and the emission/reception configuration of the four ultrasonic transducers.

Aiming at the natural defects of shale prefabrication, ultrasonic tomography technology was used to locate them and thus to realize the visualization of defects. The shale was prefabricated with 3 cylindrical defects with a diameter of 10mm. An ultrasonic tester was used to test the shale with known defect areas. The experimental results show that most of the wave velocities are concentrated between 3 000~5 000 m/s, and a few wave velocities are within 2 000 m/s, and these points are just the areas marked by the pre-made defect network. Then, the absolute effective area ratios of the three defects are further calculated through calculations to be 0.165, 0.221, and 0.198, which more effectively illustrates the accuracy of the experimental results. Therefore, in the non-destructive testing of large-scale shale, the position and size range of fractures can be accurately located using ultrasonic tomography algorithms based on the measured wave velocity parameters and image visualization analysis. [ABSTRACT FROM AUTHOR]

Oil-water biphasic medium widely existed in mining and transportation process of petroleum industry, where visualized measurement processes vital importance in production increase, state monitoring and fault prognosis. Ultrasonic Tomography (UT) is a non-invasive and non-radioactive sensing modality in industrial Process Tomography, which is demonstrated as a competitive monitoring technique with great potential. However, facing the refraction effect of Ultrasound wave at oil-water interfaces, the accuracy of reconstruction algorithm is with large error and serious artifacts. To address the issue, a modified ray-tracing image reconstruction algorithm is proposed. The amplitude attenuation during ultrasound propagation in nonhomogeneous medium is quantitatively modeled to form absolute UT model. With ray tracing strategy applied and improved, the nonlinear refraction effect is characterized in the form of iterative update of sensitivity matrix, followed by which the sound speed mapping transfers reconstructed attenuation images to sound speed distribution for ray tracing computation. Numerical tests indicate that the proposed method significantly improves reconstruction accuracy through projection-based, regularization-based and algebraic-based inverse algorithms, which demonstrate its benefits in conducting oil-water biphasic medium imaging.

Abstract The authors are trying to develop an ultrasonic CT technique for concrete structures. As the first step of its development, we study how the ultrasonic waves propagate in concrete structures and pose a problem to develop ultrasonic CT, applying which we give a non-destructive inspection technique for concrete cover by application of the idea of the ultrasonic CT. The authors claim that this study gives the foundation of the theory of ultrasonic CT for concrete structures.

Abstract Ultrasonic tomography (UT) is a non-invasive multiphase flow detection technique. In ultrasonic transmission tomography, reconstruction images are derived from a direct wave signal transmitted through the materials in the sensing area. The maximum values of the received direct wave from the reference pattern and the measured pattern are normally used to reconstruct the images. The speed of sound in the pipe wall and the materials in the sensing area affect the received signal. This in turn affects image quality—especially when the arrival time of the direct wave propagated through the sensing area is close to the arrival time of the direct wave propagated through the pipe wall. Here, we describe a novel shielding structure for ultrasonic transmission tomography. The relative variation ratio (RVR) is defined and used to evaluate the validity of the shielding structure. Larger RVR values imply better signal resolution and better signal suppression. A simplified mode is discussed including the influence of the shielding structure’s design parameters on the received direct wave. The optimized shielding structure size was determined. A comparison of the results between the normal pipe and the shielding pipe indicated that the RVR increased from 57.25 to 91.27%. This proves that the shielding structure can suppress the effect of the signal from the pipe wall on received direct wave signals.

In ultrasonic tomography that employs the technique of digital focusing with an antenna (DFA), the problem of increasing the inspection performance is inextricably linked with the problem of increasing the speed of producing synthesized images. This problem can be effectively solved by concurrently using several approaches aimed at increasing the image production speed. In the framework of this paper, we consider the algorithm of nonuniform fast Fourier transform (NUFFT). The NUFFT can be used in the existing computationally efficient spatiotemporal processing algorithms with calculations in the frequency domain and is capable of correctly reconstructing synthesized images with sparse and non-uniform antenna arrays (AAs). The experimental data obtained indicate the ability of the NUFFT-based algorithm to restore synthesized images with high resolution. [ABSTRACT FROM AUTHOR]

The exact measurement of multiphase flow is an important and essential task in the oil and petrochemical related industries. Several methods have already been proposed in this field. In the existing methods, flow rate measurement depends on the fluid flow pattern. Flow pattern recognition requiring calibration has created instability in such systems. In this paper, a imple and reliable method is proposed which is based on ultrasonic tomography. It is free from calibration and instability problems that existing methods have. The obtained data from a 32-digit array of ultrasonic sensors have been used and the two-phase flow rate including liquid and gas phases have been calculated through a simple algebraic algorithm. Simulation results show that while applying this method the measurement technique is independent from the fluid flow pattern and the system error is decreased. For the proposed algorithm, the average amount of the spatial imaging error (SIE) for a bubble at different positions inside the pipe is about 5%. [ABSTRACT FROM AUTHOR]

A coustic travel time TOM ography (ATOM) is a remote measuring technique that uses sound velocity to monitor indoor air temperature distribution. The sound velocity can be derived experimentally from the travel times estimation along the sound propagation paths with known lengths. Previous works often deal with the ATOM measurements within the audible range (20 Hz − 20 kHz) based on the travel times of early reflections up to third-order reflections. In this study, the focus is shifted from the audible to the ultrasonic range. Ultrasonic tomography, when compared to the audible range, offers greater practicality for air temperature monitoring in real-world scenarios such as office environments. A major advantage is that the room's occupants remain undisturbed by the signal transmission during measurements. Moreover, the smaller dimensions of ultrasound sensors allow for more precise positioning of the sound sources and receivers in the room compared to conventional audible sensors. On the other hand, the strong directivity of the ultrasonic sound sources presents new challenges such as reducing the number of early reflections. This study evaluates the performance of the ATOM measuring system in the ultrasonic frequency range by reconstructing indoor temperature under several thermal conditions. Accordingly, four ultrasonic sound sources and one receiver are mounted within a climate chamber. The main contributions of the developed setup involve enhancing signal-to-noise ratios (SNR) for individual travel times and taking advantage of early reflections to ensure a suitable number of travel times crucial for tomography reconstruction while utilizing a minimal number of transducers. The measurement outcomes demonstrate a 5 dB enhancement in SNR for the ultrasonic measurement configuration compared to the audible measurements. Moreover, the superiority of the activated high-pass filter of the utilized preamplifier in handling temperature measurements is demonstrated. An average root mean square error of 0.31 K reveals the applicability of the ATOM-measuring system for high-resolution monitoring of air temperature distribution in the ultrasonic range. • The developed ultrasonic travel time tomography setup proved high-resolution indoor air temperature monitoring. • Early reflections were utilized as sound propagation paths, innovatively combining room acoustics with tomography technique. • The phase shifts compensating method was employed to enhance the accuracy of travel time measurements. • The preamplifier's activated high-pass filter demonstrated its superior ability to handle temperature measurements. [ABSTRACT FROM AUTHOR]

The present research aims to assess the reliability of Ultrasonic Tomography (UT) of void detection in post-tensioning ducts due to inappropriate execution of grouting. The methodology is based on the construction of the Probability of Detection (PoD) curves for this specific non-destructive technique, by relating the probability of success to identify a specified ungrouted region. The PoD curves are built on data collected during a testing campaign in the laboratory, under fully known grouting conditions. Six walls containing prestressing strands and bars in metallic and plastic ducts with simulated voids of different sizes were designed and executed. Both water-filled (infiltration) and empty voids (ungrouted region) were simulated. The classical frequentist and Bayesian approaches are used to derive the PoD curves. Since the available experimental data are limited, the Bayesian approach provides more reliable data and is, thus, proposed as the best alternative. It is finally concluded that the minimum size of the voids in metallic ducts that UT can detect with 95% confidence and 90% probability, is around 30 cm and this value will be used in future inspection campaigns in posttensioned bridges. • The inspection of post-tensioned (PT) bridges is a complex issue, non-destructive techniques should be employed. • Ultrasonic Tomography (UT) is a non-destructive technique employed in the investigation of defects in PT ducts. • A possible way to assess the reliability of the UT is by the Probability of Detection (PoD) model. [ABSTRACT FROM AUTHOR]

Abstract In recent years, due to the destructive and unproductive character of pavement specimen extraction, pavement maintenance technology intensified the use of non-destructive techniques for pavement evaluation which resulted in the development of several devices and evaluation methods. This paper describes the use of technology based on low frequency ultrasonic tomography for evaluation of concrete pavement parameters. The equipment was applied in three experimental sections with different concrete pavements built at the University of Sao Paulo campus. The ultrasonic signal processing is given. The results analysis enables the efficient and reliable identification of thickness and reinforcement position within the concrete slab. Construction problems were evidenced in one of experimental sections with thickness deficiencies and reinforcement in a position below projected. Furthermore, the use of a novel concrete quality indicator was correlated with the presence of transverse cracks and alkali-silica reaction within the sections.

In the lightweight material industries, the current focus is on fiber-reinforced plastics, in particular on carbon fiber-reinforced plastics (CFRPs), since they offer higher relative specific tensile strength and stiffness as well as reduced weight compared to conventional metallic materials. Currently, the quality assurance of manufactured CFRP components represents a major challenge for CFRP manufacturers. Voids are generated during the infusion process of CFRPs, which in turn reduce the mechanical performance of CFRPs. This article presents the possibility to detect the distribution of voids across the surface of CFRPs by using a non-destructive testing method, the so-called sampling phased array ultrasound technology. Two types of CFRPs with six carbon layers in the same direction are fabricated by means of a vacuum-assisted resin infusion process. Voids in CFRPs are generated using a foaming agent during the impregnation process. The C-scan images produced through the sampling phased array technology are subsequently analyzed by the optical image analysis software in order to determine the amount of voids for each type of manufactured CFRP. [ABSTRACT FROM AUTHOR]

This study focuses on developing the algorithms for solving 3D inverse problems of ultrasound tomography using GPU clusters and general-purpose supercomputers. The computing capabilities of these supercomputer architectures in application to wave tomography are compared via numerical simulations. Parallel gradient-based iterative algorithms designed to solve coefficient inverse problems for the wave equation are proposed. We show that layer-by-layer wave tomography can be efficiently performed using both CPU- and GPU-based supercomputers. Solving 3D coefficient inverse problems is much more computationally expensive. A general-purpose (CPU-based) system capable of reconstructing 3D images should be equipped with either a sufficient number of memory access channels or a large number of computing cores with large cache memory and high-speed communication network. Such a system would be very large and expensive. Therefore, the most promising solution is to develop dedicated GPU-based supercomputers. From the applications perspective, this study focuses on problems of developing ultrasound tomography devices for breast cancer diagnosis. Computer simulations show that a GPU cluster capable of performing 3D image reconstruction within reasonable time fits in a single rack and can be incorporated into medical ultrasound tomography facilities. • Efficient parallel algorithms for 3D ultrasonic tomography are proposed. • The problem is formulated as a coefficient inverse problem for the wave equation. • Algorithms are implemented on GPU and CPU-based supercomputers. [ABSTRACT FROM AUTHOR]

An efficient domain decomposition method and its parallel implementation for the solution of the Helmholtz equation in three-dimensional layered media are considered. A modified trilinear finite element discretization scheme is applied to the equation system leading to fourth-order phase accuracy and thereby reducing the pollution error considerably. The resulting linear system is solved with the GMRES method using a multiplicative nonoverlapping domain decomposition preconditioner with layers defining the subdomains. This right preconditioner is constructed by embedding each layer into a rectangular domain and by employing a fast direct solver. Due to the construction of the preconditioner the iterations can be reduced to a subspace corresponding to the interfaces between the layers. Numerical experiments with several test cases demonstrate the effectiveness and scalability of the proposed method and ability to solve large-scale problems with up to billions of unknowns. [ABSTRACT FROM AUTHOR]

The energy released during earthquake rupture is partly radiated as seismic waves and mostly dissipated by frictional heating on the fault interface and by off‐fault fracturing of surrounding host rock. Quantification of these individual components is crucial to understand the physics of rupture. We use a quasi‐static rock fracture experiment combined with a novel seismic tomography method to quantify the contribution of off‐fault fracturing to the energy budget of a rupture and find that this contribution is around 3% of the total energy budget and 10% of the fracture energy Gc. The off‐fault dissipated energy changes the physical properties of the rock at the early stages of rupture, illustrated by the 50% drop in elastic moduli of the rock near the fault, and thus is expected to greatly influence later stages of rupture and slip. These constraints are a unique benchmark for calibration of dynamic rupture models. Key Points: We obtain a time‐resolved 3‐D seismic velocity structure during quasi‐static rupture in graniteAround the fault, P wave velocity drops by 25% and elastic constants by 50%Off‐fault dissipated energy is 3% of the total rupture energy budget and 10% of the fracture energy [ABSTRACT FROM AUTHOR]

To ensure the high speed of composing synthesized images with matrix antenna arrays, industrial ultrasonic-tomography systems require computationally efficient spatiotemporal signal-processing algorithms. FFT-based algorithms with calculations in the frequency domain are of great interest in this connection. At the same time, the algorithms must output high-quality results under various conditions of ultrasonic tomography. In ultrasonic tomography of multilayered structures, the nonparallelism and, in the limiting case, curvilinearity of the boundaries of layers in the test object relative to the scanning plane is one of the factors seriously reducing the algorithm efficiency. In this article, we propose an algorithm for calculating three-dimensional tomographic images in the frequency domain using matrix phased arrays with compensation for the tilt of the test object relative to the scanning plane when using an immersion acoustic-contact technique. The effectiveness of the proposed method has been confirmed experimentally. [ABSTRACT FROM AUTHOR]

The article is devoted to developing methods of ultrasonic tomography for nondestructive testing. The inverse problem of reconstructing velocity sections is treated as a nonlinear coefficient inverse problem for a scalar wave equation. Effective iterative methods for solving this problem using supercomputers have been developed. These methods use direct formulas for computing the gradient of a residual functional between the computed wave field and the field experimentally measured on detectors. The effectiveness of the algorithms was tested on real experimental data. The first experiments were carried out on dedicated solid-state samples in the simplest arrangement, with the signals recorded by standard ultrasonic antenna arrays at a frequency of 5 MHz. It is shown that using the developed tomographic methods with reflection and transmission schemes in a real experiment, it is possible not only to detect the boundaries of reflectors, but also to determine the velocity sections inside the reflectors. [ABSTRACT FROM AUTHOR]

Structural analysis of marble statues, carried out by non-invasive and in situ methods, is crucial to define the state of conservation of the artworks and to identify the deterioration phenomena that can affect them. In this work, we combined in situ non-destructive techniques, ultrasonic tomography (US), ultraviolet-induced visible fluorescence (UV-IF) and X-ray fluorescence (XRF) to study the bass-relief 'Madonna con Bambino' (Gorizia, Italy). The US revealed the presence of some metallic pivots, associated with areas of high sound velocity; moreover, a more degraded area has been identified in the lower part of the bass-relief. The acquired UV-IF image confirmed the presence of surface degradation, allowing a preliminary evaluation of the extension of a fracture, from surface to bulk. In addition, the different materials (both original and/or integrations) that compose the studied surface have been identified. The XRF has contributed to define the nature of the inorganic materials applied during undocumented previous restoration works on the surface as filler for lacunae. [ABSTRACT FROM AUTHOR]

X-ray tomography and magnetic resonance imaging (MRI) are excellent techniques for non-destructive or non-invasive inspections, however, they have shotcomings including the expensive cost in both the devices themselves and their protection facilities, the harmful side effects of the X-rays to human bodies and to the environment. In view of this argument, it is necessary to develop new, inexpensive, safe and reliable tomographic techniques, especially in medical imaging and non-destructive inspections. There are new tomographic techniques under development such as optical tomography, photo-acoustic tomography, ultrasonic tomography and so on, from which we take ultrasonic tomography as the topic in this paper. We introduce a review of the known ultrasonic tomographic techniques and discuss their future development. [ABSTRACT FROM AUTHOR]

ObjectivesWe propose an automatic breast mass detection algorithm in three-dimensional (3D) ultrasound (US) images using the Hough transform technique.MethodsOne hundred twenty-five cropped images containing 68 benign and 60 malignant masses are acquired with clinical diagnosis by an experienced radiologist. The 3D US images are masked, subsampled, contrast-adjusted, and median-filtered as preprocessing steps before the Hough transform is used. Thereafter, we perform 3D Hough transform to detect spherical hyperplanes in 3D US breast image volumes, generate Hough spheres, and sort them in the order of votes. In order to reduce the number of the false positives in the breast mass detection algorithm, the Hough sphere with a mean or grey level value of the centroid higher than the mean of the 3D US image is excluded, and the remaining Hough sphere is converted into a circumscribing parallelepiped cube as breast mass lesion candidates. Finally, we examine whether or not the generated Hough cubes were overlapping each other geometrically, and the resulting Hough cubes are suggested as detected breast mass candidates.ResultsAn automatic breast mass detection algorithm is applied with mass detection sensitivity of 96.1% at 0.84 false positives per case, quite comparable to the results in previous research, and we note that in the case of malignant breast mass detection, every malignant mass is detected with false positives per case at a rate of 0.62.ConclusionsThe breast mass detection efficiency of our algorithm is assessed by performing a ROC analysis.