Detection and sizing of corrosion in pipelines and pressure vessels over large, partially accessible areas is of growing interest in the petrochemical industry. Low-frequency guided wave diffraction tomography is a potentially attractive technique to rapidly evaluate the thickness of large sections of partially accessible structures. Finite element simulations of a 64-element circular array on a plate show that when the scattering mechanism of the object to be reconstructed satisfies the Born approximation, the reconstruction of the thickness is accurate. However, the practical implementation is more challenging because the incident field is not known. This paper describes the baseline subtraction approach commonly used in structural health monitoring applications and proposes a new approach in which the measurement of the incident field is not required when using a circular array of transducers. Experimental results demonstrate that ultimately the scattering from the array of transducers is a major source of error in the tomographic reconstruction, but when there is no scattering from the array of transducers the reconstructions are very similar to the finite element simulations.
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http://dx.doi.org/10.1109/TUFFC.2010.1559 | DOI Listing |
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January 2025
Department of Mechanical Engineering, University of Bath, Bath, BA2 7AY, UK.
Bismuth-layered ferroelectric nanomaterials exhibit great potential for piezo-photocatalysis. However, a major challenge lies in the difficulty of recovering the catalytic powders, raising concerns regarding secondary pollution of water. In this work, a novel hierarchical porous ferroelectric ceramic containing {110} surface-exposed BiNdTiO (BIT-Nd) nanosheet arrays is grown on a porous ceramic matrix for efficient and recyclable piezo-photocatalysis.
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January 2025
College of Geodesy and Geomatics, Shandong University of Science and Technology, Qingdao 266590, China.
Underwater acoustic transducers need to expand the coverage of acoustic signals as much as possible in most ocean explorations, and the directivity indicators of transducers are difficult to change after the device is packaged, which makes the emergence angle of the underwater acoustic transducer limited in special operating environments, such as polar regions, submarine volcanoes, and cold springs. Taking advantage of the refractive characteristics of sound waves propagating in different media, the directivity indicators can be controlled by installing an acoustic lens outside the underwater acoustic transducer. To increase the detection range of an underwater acoustic transducer in a specific marine environment, a curvature-determining method for the diverging acoustic lens of an underwater acoustic transducer is proposed based on the acoustic ray tracing theory.
View Article and Find Full Text PDFMicromachines (Basel)
January 2025
College of Mechanical & Electrical Engineering, Central South University, Changsha 410083, China.
In the health monitoring and safety assessments of concrete structures, ultrasonic non-destructive testing (NDT) technology has become an indispensable tool due to its non-destructive nature, efficiency, and precision. However, when used in inspecting irregular concrete surfaces, traditional planar ultrasonic transducers often encounter energy loss and signal attenuation induced by poor interface coupling, which significantly reduces the accuracy and reliability of the test results. To address this problem, this article proposes a point-contact dry coupling ultrasonic transducer solution, which enables efficient acquisition of ultrasonic signals within concrete without the need for couplants.
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December 2024
State Key Laboratory of Precision Measurements Technology and Instrument, Tianjin University, Tianjin 300072, China.
Piezoelectric micromachined ultrasonic transducers (PMUTs) show considerable promise for application in ultrasound imaging, but the limited bandwidth of the traditional PMUTs largely affects the imaging quality. This paper focuses on how to arrange cells with different frequencies to maximize the bandwidth and proposes a multi-frequency PMUT (MF-PMUT) linear array. Seven cells with gradually changing frequencies are arranged in a monotonic trend to form a unit, and 32 units are distributed across four lines, forming one element.
View Article and Find Full Text PDFGenes (Basel)
January 2025
Department of Biology and Biotechnology 'L. Spallanzani', University of Pavia, via Ferrata 9, 27100 Pavia, Italy.
DNA damage response (DDR) contributes to seed quality by guarding genome integrity in the delicate phases of pre- and post-germination. As a key determinant of stress tolerance and resilience, DDR has notable implications on the wider scale of the agroecosystems challenged by harsh climatic events. The present review focuses on the existing and documented links that interconnect DDR efficiency with an array of molecular hallmarks with biochemical, molecular, and physiological valence within the seed metabolic networks.
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