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Tunable depth of focus of acoustical pupil masked Soret Zone Plate
摘要： In acoustical lenses both resolution and depth of focus are determined by diffraction and the smaller the lens aperture the worse the resolution and the greater the depth of focus. Diffraction-limited resolution has a Soret Zone Plate, but a long depth of focus has an axicon. Nevertheless, these are two different devices each of which requires its own independent design. In this paper we have shown that the transition from focusing to a diffraction limited spot to a quasi-diffraction free beam can be realized in the same focusing device without changing its topology. It has been shown that using a classical planar Soret Zone Plate lens made of a concentric array of circular aperiodical rings with an amplitude pupil mask placed closely to the surface of lens allows to form a quasi-Bessel beams under specific conditions, part of a diffracted wave collimates, producing an elongated focus. Experiments are performed in water tanks in order to verify the simulation results. Experimental verification shown that the depth of focus of a pupil-masked Soret Zone Plate increases 1.63 times and resolution increases 1.2 times (with minimal beam waist about of 0.67 of wavelength and depth of focus about 5.72 of wavelength). By dynamically controlling the size of the amplitude pupil mask, it is possible to quickly control the depth of focus of an acoustic lens.
关键词： ultrasonic lens,acoustic bessel beam,axicon
更新于2025-09-04 15:30:14
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[IEEE 2018 IEEE 13th Annual International Conference on Nano/Micro Engineered and Molecular Systems (NEMS) - Singapore, Singapore (2018.4.22-2018.4.26)] 2018 IEEE 13th Annual International Conference on Nano/Micro Engineered and Molecular Systems (NEMS) - From Nanostructured Piezoelectric Materials to Broadband Transducers for High Resolution Ultrasonic Imaging
摘要： One-dimensional (1D) piezoelectric nanotubes have been fabricated and integrated for producing high frequency nanotube array ultrasonic transducers for high resolution ultrasonic imaging. We find that the nanotube structural feature and the unique nanoconfinement-induced crystal and polarization orientation lead to outstanding piezoelectric material properties and the resulting superior transducer performance. The nanotube array ultrasonic transducers show a broad bandwidth of 126 % (-6 dB) at 108 MHz, with significantly improved sensitivity in comparison with conventional thin film transducers despite the size shrinkage. We further demonstrate high resolution scanning ultrasonic imaging and photoacoustic imaging using the obtained nanotube array transducers, exhibiting great application values.
关键词： piezoelectric nanotubes,high resolution imaging,ultrasonic transducers,photoacoustic imaging
更新于2025-09-04 15:30:14
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Rapid Determination of Mercury Speciation in Marine Products by Molecular Spectrometry
摘要： A method is developed for the determination of content of inorganic mercury, methylmercury, ethylmercury, and phenylmercury in marine products by molecular spectroscopy with microliquid extraction. Ultrasonic extraction pretreatment is performed, C18 column and rotary evaporator are used for concentrating eluent, and liquid chromatography–ultraviolet (UV) digestion molecular spectrometry is used for analysis. Detection conditions of various forms of mercury compounds are optimized, and the content and UV digestion conditions of each component in the mobile phase are compared through experiments. The standard recovery rate of experimental samples is generally in the range of 90–106%; measured results are satisfactory, and have less interference, which provides reliable technical support for speciation analysis of mercury in marine products.
关键词： Mercury,ultrasonic extraction,liquid chromatography–UV digestion
更新于2025-09-04 15:30:14
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[IEEE 2018 IEEE 7th Global Conference on Consumer Electronics (GCCE) - Nara, Japan (2018.10.9-2018.10.12)] 2018 IEEE 7th Global Conference on Consumer Electronics (GCCE) - Performance Evaluation of Flexible Electret Sensor Array for Ultrasonic Object Detection in Short Distance
摘要： Ultrasonic object detection in short distance could contribute the monitoring of human life activity and remote operation of home appliances. In this study, Ultrasonic sensor array using flexible electret elements were fabricated to detect objects in short distance. The reflection waves were clearly detected at short distance. The object (PVC pipe) detection was examined using the ultrasound generated by the ECS array. The estimated distance was good agreement with the true value though large errors were observed for the estimated angles because only three receivers were used for ECS array.
关键词： flexible sensor,electret,object detection,ultrasonic sensor,in-home activity recognition
更新于2025-09-04 15:30:14
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Regenerated fiber Bragg grating sensing system for ultrasonic detection in a 900 °C environment
摘要： Heat-resistant composites, such as ceramic matrix composites (CMCs) and heat-resistant carbon fiber reinforced plastics (CFRPs), are expected to be used for aircraft engine parts. The development of reliable heat-resistant composite materials requires the use of nondestructive test (NDT) techniques for evaluating the progression of damage during material testing at elevated temperatures. Furthermore, structural health monitoring (SHM) technologies that operate under harsh environments are expected to be realized for monitoring heat-resistant composite structures. To provide potential solutions for the establishment of such technologies, this research developed a heat-resistant ultrasonic sensor based on a regenerated fiber-optic Bragg grating (RFBG). First, we fabricated an RFBG by annealing a normal FBG sensor. Because the RFBG exhibits high heat resistance at temperatures of 1000 °C, the sensor achieved stable ultrasonic detection at an elevated temperature. In addition, we attempted to use a π-phase-shifted FBG (PSFBG) as the seed grating to construct an ultrasonic sensor with enhanced performance. As a result, the R(PS)FBG sensor possessed a very short effective gauge length and achieved a broad frequency response to ultrasonic waves with frequencies greater than 1.5 MHz. The broadband detectability enables the R(PS)FBG sensor to acquire an accurate response to ultrasonic waves. Hence, we believe the regenerated Bragg grating-based ultrasonic sensors can contribute to establishing an effective nondestructive evaluation method for composite materials, thereby enabling a structural health monitoring system for a composite-made structure operating under extreme high-temperature environments.
关键词： structural health monitoring (SHM),ultrasonic detection,nondestructive test (NDT),regenerated fiber-optic Bragg grating (RFBG),high-temperature environment,Heat-resistant composites
更新于2025-09-04 15:30:14