Research

Jump to: Other

15 pages, 2023 KiB

Open AccessArticle

A Doherty Power Amplifier for Ultrasound Instrumentation

by Hojong Choi

Sensors 2023, 23(5), 2406; https://doi.org/10.3390/s23052406 - 21 Feb 2023

Cited by 5 | Viewed by 1852

The ultrasound instrumentation uses linear power amplifiers with low power efficiency, generating unwanted heat and resulting in the deterioration of the echo signal quality of measured targets. Therefore, this study aims to develop a power amplifier scheme to increase power efficiency while maintaining [...] Read more.

The ultrasound instrumentation uses linear power amplifiers with low power efficiency, generating unwanted heat and resulting in the deterioration of the echo signal quality of measured targets. Therefore, this study aims to develop a power amplifier scheme to increase power efficiency while maintaining appropriate echo signal quality. In communication systems, the Doherty power amplifier has shown relatively good power efficiency while producing high signal distortion. The same design scheme cannot be directly applied to ultrasound instrumentation. Therefore, the Doherty power amplifier needs to be re-designed. To verify the feasibility of the instrumentation, a Doherty power amplifier was designed to obtain high power efficiency. The measured gain, output 1-dB compression point, and power-added efficiency of the designed Doherty power amplifier were 33.71 dB, 35.71 dB_m, and 57.24% at 25 MHz, respectively. In addition, the performance of the developed amplifier was measured and tested using the ultrasound transducer through the pulse-echo responses. The output power with 25 MHz, 5-cycle, and 43.06 dB_m generated from the Doherty power amplifier was sent through the expander to the focused ultrasound transducer with 25 MHz and 0.5″ diameter. The detected signal was sent via a limiter. Afterwards, the signal was amplified by a 36.8 dB gain preamplifier, and then displayed in the oscilloscope. The measured peak-to-peak amplitude in the pulse-echo response with an ultrasound transducer was 0.9698 V. The data showed a comparable echo signal amplitude. Therefore, the designed Doherty power amplifier can improve the power efficiency used for medical ultrasound instrumentation. Full article

(This article belongs to the Special Issue Nondestructive Sensing and Imaging in Ultrasound)

► Show Figures

Figure 1

16 pages, 5352 KiB

Open AccessArticle

Ultrasonic Quality Assurance at Magnesia Shotcrete Sealing Structures

by Vera Lay, Ute Effner, Ernst Niederleithinger, Jennifer Arendt, Martin Hofmann and Wolfram Kudla

Sensors 2022, 22(22), 8717; https://doi.org/10.3390/s22228717 - 11 Nov 2022

Cited by 5 | Viewed by 1309 | Correction

Abstract

Engineered barriers are a key element to enable safe nuclear waste disposal. One method currently under research for their construction is magnesia concrete applied in a shotcrete procedure. In this study, the ultrasonic echo method is evaluated as a means for quality assurance. [...] Read more.

Engineered barriers are a key element to enable safe nuclear waste disposal. One method currently under research for their construction is magnesia concrete applied in a shotcrete procedure. In this study, the ultrasonic echo method is evaluated as a means for quality assurance. Imaging of internal structures (backwall, boreholes) and defects, such as delamination, has successfully been achieved in the shotcrete. Additionally, detailed information about the potential cause of selected reflectors are obtained by phase analysis. In several test blocks of various sizes, no consistent concrete section boundaries have been found by ultrasonic imaging, which was verified by subsequent drilling and complementary tests. An experiment with artificial defects imitating cracks, air-filled voids, and material with lower density has been challenging and shows the limitations of the current methods. Although significant defects, such as a large delamination, are reliably identified, several smaller defects are not identified. Generally, ultrasonic imaging provides a suitable base as a mean for quality assurance during and after the construction of sealing structures. However, further developments are required to enhance the reliability of the method and a full validation is still pending. Still, the method has potential to increase the safety of nuclear waste repositories. Full article

(This article belongs to the Special Issue Nondestructive Sensing and Imaging in Ultrasound)

► Show Figures

Figure 1

12 pages, 4318 KiB

Open AccessCommunication

Enhancement of Ultrasonic Transducer Bandwidth by Acoustic Impedance Gradient Matching Layer

by Ke Zhu, Jinpeng Ma, Xudong Qi, Bingzhong Shen, Yang Liu, Enwei Sun and Rui Zhang

Sensors 2022, 22(20), 8025; https://doi.org/10.3390/s22208025 - 20 Oct 2022

Cited by 8 | Viewed by 2392

Abstract

High-performance broadband ultrasound transducers provide superior imaging quality in biomedical ultrasound imaging. However, a matching design that perfectly transmits the acoustic energy between the active piezoelectric element and the target medium over the operating spectrum is still lacking. In this work, an anisotropic [...] Read more.

High-performance broadband ultrasound transducers provide superior imaging quality in biomedical ultrasound imaging. However, a matching design that perfectly transmits the acoustic energy between the active piezoelectric element and the target medium over the operating spectrum is still lacking. In this work, an anisotropic gradient acoustic impedance composite material as the matching layer of an ultrasonic transducer was designed and fabricated; it is a non-uniform material with the continuous decline of acoustic impedance along the direction of ultrasonic propagation in a sub-wavelength range. This material provides a broadband window for ultrasonic propagation in a wide frequency range and achieves almost perfect sound energy transfer efficiency from the piezoelectric material to the target medium. Nano tungsten particles and epoxy resin were selected as filling and basic materials, respectively. Along the direction of ultrasonic propagation, the proportion of tungsten powder was carefully controlled to decrease gradually, following the natural exponential form in a very narrow thickness range. Using this new material as a matching layer with high-performance single crystals, the −6 dB bandwidth of the PMN-PT ultrasonic transducer could reach over 170%, and the insertion loss was only −20.3 dB. The transducer achieved a temporal signal close to a single wavelength, thus there is the potential to dramatically improve the resolution and imaging quality of the biomedical ultrasound imaging system. Full article

(This article belongs to the Special Issue Nondestructive Sensing and Imaging in Ultrasound)

► Show Figures

Figure 1

16 pages, 3443 KiB

Open AccessArticle

Comprehensive Testing of Sulfate Erosion Damage of Concrete Structures and Analysis of Silane Coating Protection Effect

by Dunwen Liu, Yinghua Jian, Yu Tang, Kunpeng Cao, Wanmao Zhang, Haofei Chen and Chun Gong

Sensors 2022, 22(20), 7991; https://doi.org/10.3390/s22207991 - 20 Oct 2022

Cited by 5 | Viewed by 1173

Abstract

In order to study the protection performance of silane coating on in-service concrete structures in a sulfate environment, we collect concrete samples in the field to simulate the concrete erosion process by accelerated erosion with wetting–drying cycles. We place the samples into protected, [...] Read more.

In order to study the protection performance of silane coating on in-service concrete structures in a sulfate environment, we collect concrete samples in the field to simulate the concrete erosion process by accelerated erosion with wetting–drying cycles. We place the samples into protected, exposed and control groups corresponding to a corrosive environment with silane protection, corrosive environment without protection and general environment for three different service conditions. A combination of ultrasonic velocimetry, CT (Computed Tomography) scan imaging, NMR (Nuclear Magnetic Resonance) pore structure analysis, strength testing and other methods are used to analyze the strength, ultrasonic wave velocity, pore structure and other characteristics of the specimens during sulfate erosion. Based on the test results, the protective effect of silane coating on concrete structures under sulfate attack is quantitatively analyzed, and an index for judging the damage rate of specimens is proposed to quantitatively analyze the protective effect of silane coating. The research results show that the damage of the concrete structure under silane protection in a sulfate-attack environment can be reduced by more than 50%; its integrity damage index and strength damage index are easily affected by the location of local defects, which leads to a decrease in the protection efficiency of the surface silane coating. Full article

(This article belongs to the Special Issue Nondestructive Sensing and Imaging in Ultrasound)

► Show Figures

Figure 1

15 pages, 4544 KiB

Open AccessArticle

Multi Spherical Wave Imaging Method Based on Ultrasonic Array

by Zhi-Ying Liu, Ping Zhang, Bi-Xing Zhang and Wen Wang

Sensors 2022, 22(18), 6800; https://doi.org/10.3390/s22186800 - 08 Sep 2022

Cited by 1 | Viewed by 1280

Abstract

The imaging range of traditional plane wave imaging is usually limited by the directivity of the plane wave. In this paper, a multi spherical wave imaging method based on an ultrasonic array is proposed, which radiates both compression and shear waves in a [...] Read more.

The imaging range of traditional plane wave imaging is usually limited by the directivity of the plane wave. In this paper, a multi spherical wave imaging method based on an ultrasonic array is proposed, which radiates both compression and shear waves in a solid medium to form the multi spherical wave. Firstly, excitation characteristics of the multi spherical wave are analyzed theoretically and the calculation method of echo delay of multi spherical wave imaging is derived. Multi spherical wave imaging is compared with conventional ultrasonic plane wave imaging by designing experiments. Compared with ultrasonic plane wave imaging, multi spherical wave imaging is not limited to the size of the transducer and can greatly improve the detection range. In addition, compared with the multi plane wave imaging method, the multi spherical wave imaging algorithm is relatively simple, fast, and has high application value. Full article

(This article belongs to the Special Issue Nondestructive Sensing and Imaging in Ultrasound)

► Show Figures

Figure 1

23 pages, 8316 KiB

Open AccessArticle

An Ultrasonic Tomography System for the Inspection of Columns in Architectural Heritage

by Sofía Aparicio Secanellas, Juan Carlos Liébana Gallego, Guillermo Anaya Catalán, Rodrigo Martín Navarro, Javier Ortega Heras, Miguel Ángel García Izquierdo, Margarita González Hernández and José Javier Anaya Velayos

Sensors 2022, 22(17), 6646; https://doi.org/10.3390/s22176646 - 02 Sep 2022

Cited by 6 | Viewed by 1785

Abstract

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 [...] Read more.

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. Full article

(This article belongs to the Special Issue Nondestructive Sensing and Imaging in Ultrasound)

► Show Figures

Figure 1

12 pages, 3497 KiB

Open AccessArticle

Non-Contact Shear Wave Generation and Detection Using High Frequency Air-Coupled Focused Transducer and Fiber Optic Based Sagnac Interferometer for Mechanical Characterization

by Gui Chen and Jinjun Xia

Sensors 2022, 22(15), 5824; https://doi.org/10.3390/s22155824 - 04 Aug 2022

Viewed by 1424

Abstract

In shear wave-based material mechanical characterization, the transmit/receiver transducer is generally in contact with the material through a coupling medium. In many applications, especially in biological tissue-related characterization, the application of the coupling medium and the contact method are not ideal, sometimes even [...] Read more.

In shear wave-based material mechanical characterization, the transmit/receiver transducer is generally in contact with the material through a coupling medium. In many applications, especially in biological tissue-related characterization, the application of the coupling medium and the contact method are not ideal, sometimes even unacceptable, due to contamination or stress response concerns. To avoid contact, we developed a 1 MHz air-coupled focused PZT transducer as a moderate pressure generator that could induce a shear wave in soft material and a fiber optic-based Sagnac system for the detection of the propagating shear wave. A calibration indicated that the fabricated air-coupled focused PZT transducer could generate pressure above 1 KPa within its focal range. This pressure is three to five times as much as the pressure generated by a 1 MHz air-coupled transducer currently available on the market. The integrated system was demonstrated through shear wave generation by the fabricated air-coupled PZT transducer and shear wave detection by the fiber optic Sagnac system in a nylon membrane. The results demonstrated the capability of the integrated system in non-contact material mechanical characterization, such as in material modulus measurement. Full article

(This article belongs to the Special Issue Nondestructive Sensing and Imaging in Ultrasound)

► Show Figures

Graphical abstract

16 pages, 18986 KiB

Open AccessArticle

Effects of Thermal Gradients in High-Temperature Ultrasonic Non-Destructive Tests

by Juliano Scholz Slongo, Jefferson Gund, Thiago Alberto Rigo Passarin, Daniel Rodrigues Pipa, Júlio Endress Ramos, Lucia Valeria Arruda and Flávio Neves Junior

Sensors 2022, 22(7), 2799; https://doi.org/10.3390/s22072799 - 06 Apr 2022

Cited by 6 | Viewed by 2166

Abstract

Ultrasonic inspection techniques and non-destructive tests are widely applied in evaluating products and equipment in the oil, petrochemical, steel, naval, and energy industries. These methods are well established and efficient for inspection procedures at room temperature. However, errors can be observed in the [...] Read more.

Ultrasonic inspection techniques and non-destructive tests are widely applied in evaluating products and equipment in the oil, petrochemical, steel, naval, and energy industries. These methods are well established and efficient for inspection procedures at room temperature. However, errors can be observed in the positioning and sizing of the flaws when such techniques are used during inspection procedures under high working temperatures. In such situations, the temperature gradients generate acoustic anisotropy and consequently distortion of the ultrasonic beams. Failure to consider such distortions in ultrasonic signals can result, in extreme situations, in mistaken decision making by inspectors and professionals responsible for guaranteeing product quality or the integrity of the evaluated equipment. In this scenario, this work presents a mathematical tool capable of mitigating positioning errors through the correction of focal laws. For the development of the tool, ray tracing concepts are used, as well as a model of heat propagation in solids and an experimentally defined linear approximation of dependence between sound speed and temperature. Using the focal law correction tool, the relative firing delays of the active elements are calculated considering the temperature gradients along the sonic path, and the results demonstrate a reduction of more than

68 %

in the error of flaw positioning. Full article

(This article belongs to the Special Issue Nondestructive Sensing and Imaging in Ultrasound)

► Show Figures

Figure 1

Other

Jump to: Research

3 pages, 1860 KiB

Open AccessCorrection

Correction: Lay et al. Ultrasonic Quality Assurance at Magnesia Shotcrete Sealing Structures. Sensors 2022, 22, 8717

by Vera Lay, Ute Effner, Ernst Niederleithinger, Jennifer Arendt, Martin Hofmann and Wolfram Kudla

Sensors 2023, 23(18), 7966; https://doi.org/10.3390/s23187966 - 19 Sep 2023

Viewed by 421

Abstract

The authors wish to correct the following errors in the original paper [...] Full article

(This article belongs to the Special Issue Nondestructive Sensing and Imaging in Ultrasound)

Journal Menu

Journal Browser

Nondestructive Sensing and Imaging in Ultrasound

Share This Special Issue

Special Issue Editors

Special Issue Information

Keywords

Published Papers (9 papers)

Research

Other

Further Information

Guidelines

MDPI Initiatives

Follow MDPI