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An air-coupled ultrasonic sensor based on cascaded fibre Bragg grating and Fabry-Perot interference cavity
摘要： In this paper, we proposed and demonstrated experimentally an air-coupled fiber-optic ultrasonic sensor, based on cascaded fibre Bragg grating (FBG) and Fabry-Perot interference (FPI) cavity. Because of the modulation effect of FPI cavity, the sensor’s responses to ultrasonic wave (UW) have been improved. With side-band filtering technology-based intensity interrogation, the voltage responses of 1.2 V and 1.34 V to the continuous and pulse UW at 1 MHz respectively are obtained in air, and its SNR is about 37 dB. Further results of the directivity and stability of the sensor indicate that the sensor has the potential of imaging in air.
关键词： Fibre Bragg grating,Air-coupled,Ultrasonic sensor,Fibre-optic sensor
更新于2025-09-23 15:19:57
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Fully noncontact measurement of inner cracks in thick specimen with fiber-phased-array laser ultrasonic technique
摘要： To realize a fully noncontact ultrasonic testing method for inner cracks inspection in thick metal specimen, a phased array laser ultrasonic testing system with using a compact optic fiber array bundle and a laser interferometer is developed in this study. The focusing and steering of the shear wave and longitudinal wave generated with seven fiber-phased-array laser sources in thermoelastic regime is investigated by a numerical simulation and validated by the experiment. A non-contact measurement of the inner-surface cracks by both the angle-beam testing method and time-of-flight diffraction method with the fiber-phased-array laser ultrasonic technique have been studied.
关键词： Fiber bundle,Laser ultrasonic testing,Phased array,Inner cracks
更新于2025-09-23 15:19:57
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Fully Spray-Coated Triple-Cation Perovskite Solar Cells
摘要： We use ultrasonic spray-coating to sequentially deposit thin films of tin oxide, a triple-cation perovskite and spiro-OMeTAD, allowing us fabricate perovskite solar cells (PSCs) with a champion reverse scan power conversion efficiency (PCE) of 19.4% on small-area substrates. We show that the use of spray-deposition permits us to rapidly (>80 mm s?1) coat 25 mm × 75 mm substrates that were divided into a series of devices each with an active area of 15.4 mm2, yielding an average PCE of 10.3% and a peak PCE of 16.3%. By connecting seven 15.4 mm2 devices in parallel on a single substrate, we create a device having an effective active area of 1.08 cm2 and a PCE of 12.7%. This work demonstrates the possibility for spray-coating to fabricate high efficiency and low-cost perovskite solar cells at speed.
关键词： spray-coating,ultrasonic spray-coating,perovskite solar cells,scalable deposition,power conversion efficiency
更新于2025-09-23 15:19:57
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On the application of laser shock peening for retardation of surface fatigue cracks in laser beam-welded AA6056
摘要： The present study aims to investigate the extent to which the fatigue behaviour of laser beam-welded AA6056-T6 butt joints with an already existing crack can be improved through the application of laser shock peening. Ultrasonic testing was utilized for in situ (nondestructive) measurement of fatigue crack growth during the fatigue test. This procedure allowed the preparation of welded specimens with surface fatigue cracks with a depth of approximately 1.2 mm. The precracked specimens showed a 20% reduction in the fatigue limit compared with specimens without cracks in the as-welded condition. Through the application of laser shock peening on the surfaces of the precracked specimens, it was possible to recover the fatigue life to the level of the specimens tested in the as-welded condition. The results of this study show that laser shock peening is a very promising technique to recover the fatigue life of welded joints with surface cracks, which can be detected by nondestructive testing.
关键词： fatigue crack,aluminium alloys,laser beam welding,ultrasonic crack tip diffraction,residual stress,laser shock peening
更新于2025-09-23 15:19:57
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Comparative evaluation of low-level laser therapy and ultrasound heat therapy in reducing temporomandibular joint disorder pain
摘要： Background: Pain, limitations in opening, asymmetrical jaw movements, and temporomandibular joint (TMJ) sounds are the most common findings in temporomandibular joint disorders (TMDs), which causes excruciating pain, inflammation of the surrounding muscles, posterior fibers, and synovial fluid. This study aimed to evaluate and compare the effects of ultrasound heat therapy and low-level laser therapy (LLLT) in reducing TMD-related pain. Methods: This prospective study included 42 patients (age range, 25–45 years), who were divided into two groups of 21 patients each. All patients were prescribed a non-steroidal anti-inflammatory drug (NSAID) twice a day for 5 days for temporary relief of pain prior to the commencement of treatment. Patients were kept on a soft diet and asked to restrict mouth opening during the same period. Fifteen sessions of LLLT (Group A) or ultrasound therapy (Group B) were administered to the affected side. Results: Post-therapy, the mean visual analog scale score for group A and group B was 4.81 (2.01) and 6.19 (1.20), respectively; the difference was statistically significant and favoring the LLLT group. Similarly, the mean mouth opening for group A and group B was 3.99 (0.40) and 3.65 (0.41), respectively; the difference was statistically significant and favoring the LLLT group. Conclusion: Our study recommends LLLT for treating TMD-related pain with no underlying bony pathology.
关键词： Ultrasonic Therapy,Temporomandibular Joint Disorders,Low-Level Laser Therapy
更新于2025-09-23 15:19:57
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Design of Acoustical Bessel-Like Beam Formation by a Pupil Masked Soret Zone Plate Lens
摘要： The image performance of acoustic and ultrasound sensors depends on several fundamental parameters such as depth of focus or lateral resolution. There are currently two different types of acoustic diffractive lenses: those that form a diffraction-limited spot with a shallow depth of focus (zone plates) and lenses that form an extended focus (quasi-Bessel beams). In this paper, we investigate a pupil-masked Soret zone plate, which allows the tunability of a normalized angular spectrum. It is shown that the depth of focus and the lateral resolution can be modified, without changing the lens structure, by choosing the size of the pupil mask. This effect is based on the transformation of spherically-converging waves into quasi-conical waves, due to the apodization of the central part of the zone plate. The theoretical analysis is verified with both numerical simulations and experimental measurements. A Soret zone plate immersed in water with D/2F = 2.5 and F = 4.5λ changes its depth of focus from 2.84λ to 5.9λ and the lateral resolution increases from 0.81λ to 0.64λ at a frequency of 250 kHz, by modifying the pupil mask dimensions of the Soret zone plate.
关键词： soret zone plate,ultrasonic lens,apodization
更新于2025-09-19 17:15:36
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Study on the Mechanism of Ultrasonic Power Measurement Sensor based on Pyroelectric Effect
摘要： PVDF pyroelectric sensor has been widely applied in many fields, such as intruder alarm. Nowadays, this sensor shows a potential for ultrasonic power measurement. However, the transformation mechanism between the acoustic and pyroelectric signals has not been particularly studied until now. In this paper, a physical model was introduced for theoretical study of the mechanism of energy transformations. In addition, a simulation program based on finite-element analysis method was built up for analyzing the ultrasound propagation characteristics and the temperature rise on the PVDF, as well it predicted the waveform and amplitude of the generated pyroelectric signal. Besides that, a PVDF pyroelectric sensor was fabricated and used for acoustic power measurement experiment. Finally, the experiment and simulation results were compared, confirming that the physical model is suitable for pyroelectric sensor characteristics analysis. It can also provide useful suggestions for the design and fabrication of PVDF pyroelectric sensors with high sensitivity.
关键词： ultrasonic power,PVDF,finite-element analysis,pyroelectric sensor
更新于2025-09-19 17:15:36
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[IEEE 2018 IEEE SENSORS - New Delhi, India (2018.10.28-2018.10.31)] 2018 IEEE SENSORS - Design and Fabrication of a Piezoelectric Micromachined Ultrasonic Transducer Array Based on Ceramic PZT
摘要： This paper presents a piezoelectric micromachined ultrasonic transducer (pMUT) array fabricated using high-piezoelectric-coefficient ceramic PZT wafers. A new process for polishing ceramic PZT layers down to 5 μm has been developed and applied for manufacturing high-sensitivity pMUTs. A 2 MHz working pMUT array (8×8 elements) based on ceramic PZT has been designed, modeled, fabricated and characterized.
关键词： pMUT,piezoelectric transducers,ultrasonic,micromachined transducers,ceramic PZT
更新于2025-09-19 17:15:36
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[IEEE 2018 IEEE SENSORS - New Delhi, India (2018.10.28-2018.10.31)] 2018 IEEE SENSORS - A Miniature Fiber-Optic Photoacoustic Probe Coated with MoS<inf>2</inf>-PDMS for Water Level and Oil-Water Interface Detection*
摘要： We demonstrate a miniature broadband (~13.3 MHz) fiber-tip photoacoustic probe with ~68.32-μm thick MoS2-polydimethylsiloxane (PDMS) composite for accurate measurement of water and oil-water interface levels. The composite was applied to the tip of a double-clad fiber with an outer diameter of 125 μm using dip coating. The propagation time of an ultrasonic wave generated by a 5-ns pulsed laser excitation in liquids was extracted to determine water level or silicone oil-water interface in a glass tube. An excellent goodness of fit (R2≈0.996) was achieved with a high accuracy of ~1.5 μm in the tested water-level range of 0-218 μm. Then the proposed technique exhibited an average relative error of 0.68% for the oil-water interface detection, along with a good fitting coefficient of 98.7% in the range of 0-8 mm. The presented photoacoustic probe therefore shows a great potential in compact accurate liquid level monitoring.
关键词： photoacoustic probe,2D nanomaterials,optical fiber tip,ultrasonic liquid level measurement
更新于2025-09-19 17:15:36
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[IEEE 2018 IEEE International Symposium on the Physical and Failure Analysis of Integrated Circuits (IPFA) - Singapore (2018.7.16-2018.7.19)] 2018 IEEE International Symposium on the Physical and Failure Analysis of Integrated Circuits (IPFA) - High Sensitivity Ultrasonic Inspection Technique Using Pulse Compression Method
摘要： We developed an ultrasonic inspection technique using a pulse compression method for detecting bonding defects with interfaces of stacked wafers. This technique can detect the minute echoes reflected from the bonding interfaces by computing the correlation function between transmitted and received signals. We designed a measurement condition for pulse compression with a transmitted signal and took an ultrasonic measurement of a 3-layer stacked sample. We compared the defect detection sensitivity of the pulse compression method with the ultrasonic inspection using pulse waves. The experimental results showed that the noise of an ultrasonic image was reduced and minute defects could be detected by applying developed method.
关键词： multi-layer staked sample,Correlation function,Defect detection,Ultrasonic inspection,Pulse compression
更新于2025-09-19 17:15:36