- 标题
- 摘要
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- 实验方案
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[IEEE 2019 24th Microoptics Conference (MOC) - Toyama, Japan (2019.11.17-2019.11.20)] 2019 24th Microoptics Conference (MOC) - Fundamental Study of Saturation Output Power on Quantum Dot Semiconductor Optical Amplifier (SOA) under High Temperature (85 ?°C)
摘要： This paper proposed a new crossbeam ultrasonic motor, which was made of a cross-shaped metal frame and eight pieces of lead zirconate titanate ceramic plates with a size of 10 mm × 3 mm × 1 mm. Two cross-cone-shaped horns were machined at two ends of the crossbeam, and the tips of the horns served as the driving feet. Ellipse trajectories of the two driving feet were generated by superimposing two orthogonal ?rst bending vibrations with the same resonance frequency but a temporal shift of 90?. A Symmetric structure of the proposed ultrasonic motor solved the problem of mode frequencies degeneracy. A new method to excite these two bending vibrations was proposed. Finite-element method simulation was developed to obtain the vibration characteristics of the crossbeam motor. The new excitation method was compared with the traditional one, and it was found that the vibration amplitudes of the driving feet under the new excitation method were about three times that of the traditional one. At last, experiments were accomplished on a fabricated prototype. The two tested ?rst bending resonance frequencies agreed well with each other at ～40.5 kHz. Mechanical output performance of the prototype was tested; the maximum speed was ～64 r/min, and the maximum output torque was ～10.4 mN · m. This paper provides a new idea for an ultrasonic motor with a miniature structure and also a new excitation method for bending vibration.
关键词： vibration characteristic,Crossbeam,bending vibration,excitation method,ultrasonic motor
更新于2025-09-19 17:13:59
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Retrieval of Glass Fiber Post using Er:YAG Laser and Conventional Endodontic Ultrasonic Method: An In Vitro Study
摘要： Purpose: To compare the times and temperatures used to remove a glass fiber post from an endodontically-treated tooth using erbium-doped yttrium aluminum garnet (Er:YAG) compared to conventional endodontic ultrasonic method. Materials and Methods: Thirty four single-root human extracted teeth were endodontically treated ex vivo. The post space was prepared to 7 mm in depth and a 11.4 mm glass fiber post was cemented using composite resin cement. Specimens were kept in 100% humidity for 24 hours and then randomly assigned to Er:YAG laser or ultrasonic methods for post removal. The removal time was recorded. Specimens with a fractured post during the removal process were excluded. The temperature on the external surface of the root was measured at the coronal, middle, and apical third portions during the laser or ultrasonic applications from 1 to 10 minutes. Data were analyzed using one-tailed t-test and paired t-test (ɑ = 0.01) for the post removal time and temperature difference, respectively. The specimen surfaces were examined using scanning electron microscopy (SEM). Results: Fifteen specimens were tested in each group. Four specimens were fractured, 2 in the laser and 1 in ultrasonic group. One post was excluded because of laser tip damage. The average removal time were 98±46.1 seconds for Er:YAG laser and 538±215.6 seconds or ultrasonic groups with significant difference between the groups (p < 0.001). The temperature (°C) ranges measured from 1 to 10 minutes were [24.2°,27.3°] for laser and [33.0°, 38.0°] for ultrasonic in the cervical area, [22.1°,24.6°] for laser and [31.0°,34.6°] for ultrasonic in the middle area, and [24.4°,27.7°] for laser and [30.3°,34.1°] for ultrasonic in the apical area. There were significant differences between temperatures for each treatment (p < 0.001). SEM examination showed no visible damage caused by treatment with Er:YAG laser. Conclusions: Er:YAG laser can remove posts up to 5 times faster than ultrasonic removal method. The laser causes lower temperature increase at the root surface compared to the ultrasonic removal. Er:YAG may be considered as a viable alternative to sonication for post removal.
关键词： laser,Er:YAG,post and core,removal,ultrasonic
更新于2025-09-19 17:13:59
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Numerical simulation of laser-generated ultrasonic waves for identification of branched-breaking defects
摘要： In order to detect stress corrosion cracking (SCC) type defects, this paper uses the finite element method (FEM) to simulate the branched-breaking defects and use the laser-generated ultrasonic wave to detect the branched-breaking defects. The branched-breaking defects often influence the reflection and mode conversion of ultrasonic wave. When the branch surface defects are at the top of the slot, the maximum amplitude of the R-wave signal spectrum gradually increases as the angle of the branch defect decreases. However, when the branch surface defects are at the center of the slot, the Rayleigh wave (R-wave) has the same characteristics and the maximum amplitude of the R-wave signal spectrum are much lower than the branch defects are at the top of the slot. The proposed method may provide an useful way to identify and distinguish the branched-breaking defects.
关键词： Laser,Branched-Breaking defects,Ultrasonic wave,The surface defect
更新于2025-09-19 17:13:59
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[IEEE 2019 IEEE 46th Photovoltaic Specialists Conference (PVSC) - Chicago, IL, USA (2019.6.16-2019.6.21)] 2019 IEEE 46th Photovoltaic Specialists Conference (PVSC) - Effects of CsF Post-deposition Treatment on Cu(In, Ga)Se <sub/>2</sub> Thin Films and Solar Cells
摘要： This paper proposed a new crossbeam ultrasonic motor, which was made of a cross-shaped metal frame and eight pieces of lead zirconate titanate ceramic plates with a size of 10 mm × 3 mm × 1 mm. Two cross-cone-shaped horns were machined at two ends of the crossbeam, and the tips of the horns served as the driving feet. Ellipse trajectories of the two driving feet were generated by superimposing two orthogonal ?rst bending vibrations with the same resonance frequency but a temporal shift of 90?. A Symmetric structure of the proposed ultrasonic motor solved the problem of mode frequencies degeneracy. A new method to excite these two bending vibrations was proposed. Finite-element method simulation was developed to obtain the vibration characteristics of the crossbeam motor. The new excitation method was compared with the traditional one, and it was found that the vibration amplitudes of the driving feet under the new excitation method were about three times that of the traditional one. At last, experiments were accomplished on a fabricated prototype. The two tested ?rst bending resonance frequencies agreed well with each other at ～40.5 kHz. Mechanical output performance of the prototype was tested; the maximum speed was ～64 r/min, and the maximum output torque was ～10.4 mN · m. This paper provides a new idea for an ultrasonic motor with a miniature structure and also a new excitation method for bending vibration.
关键词： bending vibration,Crossbeam,vibration characteristic.,ultrasonic motor,excitation method
更新于2025-09-19 17:13:59
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Facile large-scaled fabrication of graphene-like materials by ultrasonic assisted shear exfoliation method for enhanced performance on flexible supercapacitor applications
摘要： In this work, we have developed a rapid and simple approach for fabrication of graphene-like materials. It consisted of shearing commercial graphite in aqueous solution with the assistance of ultrasonication. The results showed that the graphene-like materials were successfully fabricated with not only similar flake structure of graphene, but also improved conductivity. For the applications of flexible supercapacitors, the as-prepared graphene-like materials showed better specific capacitance than commercial graphite as the working electrode. In addition, the rate capability of the flexible supercapacitor device is 80% and the capacitance retention reaches 90% after 10,000 cycles. The high flexibility of the as-fabricated graphene-like materials gives rise to high flexibility of all-solid-state supercapacitors, and the specific capacitance was not affected by bending state. The as-fabricated supercapacitor further demonstrated that it can drive the resistive pressure sensor and the voltage was stable at a fixed value under different values of pressure.
关键词： Graphene-like structure,Ultrasonic assisted shear exfoliation,Supercapacitor/resistive pressure sensor hybrids,Flexible supercapacitor
更新于2025-09-19 17:13:59
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Ultrahigh Resolution Pulsed Laser-Induced Photoacoustic Detection of Multi-Scale Damage in CFRP Composites
摘要： This paper presents a photoacoustic non-destructive evaluation (pNDE) system with an ultrahigh resolution for the detection of multi-scale damage in carbon fiber-reinforced plastic (CFRP) composites. The pNDE system consists of three main components: a picosecond pulsed laser-based ultrasonic actuator, an ultrasound receiver, and a data acquisition/computing subsystem. During the operation, high-frequency ultrasound is generated by pulsed laser and recorded by an ultrasound receiver. By implementing a two-dimensional back projection algorithm, pNDE images can be reconstructed from the recorded ultrasound signals to represent the embedded damage. Both potential macroscopic and microscopic damages, such as surface notches and delamination in CFRP, can be identified by examining the reconstructed pNDE images. Three ultrasonic presentation modes including A-scan, B-scan, and C-scan are employed to analyze the recorded signals for the representation of the detected micro-scale damage in two-dimensional and three-dimensional images with a high spatial resolution of up to 60 μm. Macro-scale delamination and transverse ply cracks are clearly visualized, identifying the edges of the damaged area. The results of the study demonstrate that the developed pNDE system provides a non-destructive and robust approach for multi-scale damage detection in composite materials.
关键词： composites,non-destructive testing,photoacoustic,multi-scale,ultrasonic representation,embedded damage
更新于2025-09-19 17:13:59
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Ultrasound-assisted electrodeposition of Fe-Ni film for OLED mask
摘要： Fe-Ni alloy is considered as the most suitable metal for OLED mask making due to its excellent properties. However, electrodeposited Fe-Ni ?lm is often companied with poor surface quality and thermal expansion. To get proper ?lm for masks making, experiments of electroforming Fe–Ni were performed with di?erent ultrasonic powers and current densities. Results show that Fe-Ni ?lm with smooth surface could be electrodeposited at high current density due to the reducing of internal stress of ?lm by ultrasonic power. The iron content, grain size, micro-hardness and Young’s modulus of ?lm all present an upward trend with ultrasonic power increases from 13 W to 93 W, and then a downward trend due to the intensively transient cavitation caused by higher ultrasonic power 120 W. With the ultrasonic power of 93 W and current density of 1 A/dm2, a good surface quality of Fe-Ni ?lms with 60.07 wt.% iron content, microhardness 351 HV, Young's modulus 167.5 GPa and CTE 3.38 × 10?6/℃ can be electrodeposited.
关键词： Fe-Ni ?lm,Electroforming,Young's modulus,Ultrasonic power,Thermal expansion
更新于2025-09-19 17:13:59
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Bifacial IFO/(n+pp+)Cz-Si/ITO solar cells with full-area Al-alloyed BSF and Ag-free multi-wire metallization suitable for low-concentration systems
摘要： Bifacial solar cells have received considerable attention due to the potential to achieve higher energy yield compared to monofacial cells. However, in bifacial cells, p+-Si layers are usually produced by boron diffusion, which makes such cells more expensive compared to monofacial cells with a full-area screen-printed Al-alloyed Al-p+ back-surface-field (BSF). Recently, we have demonstrated proof-of-concept that bifacial cells, which, in addition, are also suitable for application in low-concentration systems (3–6 suns), can be produced from commercially available, standard monofacial SiNx/(n+pp+)Cz-Si/Al structures with full-area Al-p+-BSF. For this purpose, the residual Al paste was removed and a number of solar cells were prepared differing in the sheet resistance of the Al-p+-BSF (Rp+), which was varied from 14 Ω/sq to 123 Ω/sq by thinning the Al-p+ layer using one-sided etch-back process. Thinning of the Al-p+-BSF significantly improved the efficiency under 1-sun front/rear-side illumination: from 16.0%/7.5% (at Rp+ = 14 Ω/sq) to 17.5%/11.2% (at Rp+ = 81 Ω/sq). The equivalent efficiency at 1-sun front illumination and 20/50% albedo of 1-sun illumination increased from 17.7%/20.1% (at Rp+ = 14 Ω/sq) to 19.9%/23.5% (at Rp+ = 81 Ω/sq). In this paper, we present the results of systematic study of the developed bifacial cells. Thinning-induced changes in the properties of the cells are analyzed in detail. The critical aspects which might explain the performance of the developed cells are addressed. In addition, bifacial cells are compared with standard monofacial cells fabricated using the precursor of the same batch.
关键词： Ultrasonic spray pyrolysis,Transparent conductive oxide,Ag-cost reduction,Bifacial concentrator silicon solar cell,Multi-wire metallization,Al-alloyed BSF
更新于2025-09-19 17:13:59
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Monitoring the evolution of stiffness during ultraviolet curing of a vinyl ester resin with quasi-normal air-coupled ultrasonic spectroscopy
摘要： In this paper, quasi-normal air-coupled ultrasonic (ACUS) spectroscopy has been applied to monitor the ultraviolet (UV) curing of a vinyl ester resin. The technique is useful for measuring, with a fast single measurement, compression properties since the beginning of curing and shear properties after the gel point. Data analysis must consider the temperature variation of the system, the air and the support plate, induced by the exothermic nature of curing. Additionally, the evolution of the degree of conversion, measured with a direct current sensor, is done to estimate the variation of thickness of the resin due to the shrinkage and to correlate the mechanical properties with the curing process. Finally, the relationship between the degree of conversion and Young’s modulus of a vinyl ester resin during UV curing has been successfully characterized for degrees of conversion higher than the 65%.
关键词： Air-Coupled Ultrasonic,Characterization,UV cure
更新于2025-09-16 10:30:52
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Effect of Ultrasonic Nanocrystal Surface Modification on the Microstructure and Martensitic Transformation of Selective Laser Melted Nitinol
摘要： Nitinol has significant potential for biomedical and actuating-sensing devices, thanks to its functional properties. The use of selective laser melting (SLM) with Nitinol powder can promote novel applications aimed to produce 3D complex parts with integrated functional performances. As the final step of the production route, finishing processing needs to be investigated both for the optimization of the surface morphology and the limit alteration of the Nitinol functional properties. In this work, the effect of an advanced method of surface modification, ultrasonic nanocrystal surface modification (UNSM), on the martensitic transformation and microstructure of SLM built Ni50.8Ti49.2 (at.%) was investigated. Scanning electron microscopy, X-ray diffraction, and differential scanning calorimetry indicated that the UNSM process can generate stress-induced martensite, at least partially suppressing the martensitic transformation. The microhardness profile indicates that the UNSM process can affect the mechanical properties of the SLMed Nitinol sample in a range of up to approximately 750 μm in depth from the upper surface, while electron backscatter diffraction analysis highlighted that the initial austenitic phase was modified within a depth below 200 μm from the UNSMed surface.
关键词： NiTi,ultrasonic nano-crystal surface modification,EBSD,XRD,selective laser melting,microstructure
更新于2025-09-16 10:30:52