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学者姓名：吕炎
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Abstract ：
Residue is one of the main factors affecting the reliability of sealed electronic equipment. The traditional particle collision noise detection (PIND) method is only suitable for the detection of the presence or absence of residues, but the particle size identification of the residue is important for tracking the source of production and improving the process. In this paper, the endpoint detection algorithm based on spectrum variance is used to extract the residual pulse signal, which is beneficial to the concentration of characteristic quantities. Fisher's discriminant method was used to conduct dimensionality reduction processing and clustering analysis of characteristic parameters, and BP neural network was used to realize the classification of residual particle size, and the recognition accuracy could reach 93.75%.
Keyword ：
Endpoint detection Endpoint detection Residue Residue BP neural network BP neural network Fisher's discriminant Fisher's discriminant Particle impact noise detection Particle impact noise detection
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| GB/T 7714 | Chu Kun , Lv Yan , Gong Yu et al. Research on particle size identification method of residue in sealed electronic devices [C] . 2019 : 917-922 . |
| MLA | Chu Kun et al. "Research on particle size identification method of residue in sealed electronic devices" . (2019) : 917-922 . |
| APA | Chu Kun , Lv Yan , Gong Yu , Song Guorong , Ren Zhichao , He Cunfu . Research on particle size identification method of residue in sealed electronic devices . (2019) : 917-922 . |
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Abstract ：
Cavity method is widely used in microwave measurement of electromagnetic properties. In this paper, a new double-ridged cavity method is proposed, which can enhance the operational frequency bandwidth. Building on the perturbation theory, the measurement equations required for permittivity and permeability extraction are developed. And for obtaining the electromagnetic properties more accurately, a calibration method is introduced to calibrate the shape factors. The proposed method is first simulated using the High Frequency Structure Simulator (HFSS) to demonstrate the linear relationship between the resonant parameters and the electromagnetic properties. Thereafter, a series of standard samples are also tested and verified by using the numerical simulator. For comparison the reference data, the calibration method can obviously improve the accuracy of electromagnetic parameters, especially the imag part error of complex permeability, which is reduced from more than 60% to about 4%.
Keyword ：
double-ridged cavity double-ridged cavity shape factor shape factor electromagnetic properties electromagnetic properties calibration method calibration method
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| GB/T 7714 | Lee Yungchun , Zhang Binpeng , Lv Yan et al. Characterization of electromagnetic properties by simulations using the double-ridged cavity [C] . 2019 : 274-278 . |
| MLA | Lee Yungchun et al. "Characterization of electromagnetic properties by simulations using the double-ridged cavity" . (2019) : 274-278 . |
| APA | Lee Yungchun , Zhang Binpeng , Lv Yan , Song Guorong , He Cunfu . Characterization of electromagnetic properties by simulations using the double-ridged cavity . (2019) : 274-278 . |
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Abstract ：
Air-coupled ultrasonic testing technology, possessing the characteristics of non-contact and non-destruction, is widely used in nondestructive detection for materials. An air-based line-focus air-coupled ultrasonic transducer was designed and fabricated according to the measurement of crystalline silicon solar cells. Compared to the ultrasonic transducer based on the traditional polymer matrix, the air-based line-focus air-coupled ultrasonic transducer adopted the 3D printing method to hollow out the polymer matrix frame, which will further reduce the acoustic impedance of piezoelectric composites. The center frequency of the transducer is about 150 kHz, and the focus radius is 20 mm, aperture is 28 mm. The generating and receiving performance of the transducer was measured. An crack detection experiment was implemented on a monocrystalline solar cell by air-coupled Lamb waves. The crack can be located by analyzing the amplitude of the received signals, furthermore, a correlation analysis was performed to extract the characteristics of the cracks. © 2018, Editorial Office of Acta Materiae Compositae Sinica. All right reserved.
Keyword ：
Crack detection Crack detection Ultrasonic testing Ultrasonic testing Piezoelectric transducers Piezoelectric transducers Transducers Transducers Airports Airports 3D printers 3D printers Testing Testing Piezoelectric materials Piezoelectric materials Polymer matrix composites Polymer matrix composites Military bases Military bases Ultrasonic waves Ultrasonic waves Solar cells Solar cells Nanocrystalline materials Nanocrystalline materials Piezoelectricity Piezoelectricity Ultrasonic transducers Ultrasonic transducers Surface waves Surface waves Acoustic impedance Acoustic impedance
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| GB/T 7714 | He, Cunfu , Li, Yongkun , Lv, Yan et al. Design and application of line-focus air-coupled ultrasonic transducer based on air-based piezoelectric composites [J]. | Acta Materiae Compositae Sinica , 2018 , 35 (3) : 653-660 . |
| MLA | He, Cunfu et al. "Design and application of line-focus air-coupled ultrasonic transducer based on air-based piezoelectric composites" . | Acta Materiae Compositae Sinica 35 . 3 (2018) : 653-660 . |
| APA | He, Cunfu , Li, Yongkun , Lv, Yan , Liu, Xiucheng , Wu, Bin . Design and application of line-focus air-coupled ultrasonic transducer based on air-based piezoelectric composites . | Acta Materiae Compositae Sinica , 2018 , 35 (3) , 653-660 . |
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Abstract ：
Aiming at the surface defect detection of the thick-walled pipe, a PZT based the flexible comb Rayleigh wave transducer was proposed. Firstly, the finite element simulation was carried out to optimize the parameters of element interval, element width, element number and element length. The influence of the element number and the element length on the directivity of the transducer was studied. The tailing of the Rayleigh wave signal was suppressed by optimizing the backing materials and the backing thickness. Secondly, a new type of flexible comb Rayleigh wave transducer was developed according to simulation results. The characteristic of the transducer was tested, and experimental results agreed well with the simulation. According to the simulation and optimization, the tailing of the Rayleigh wave were shrinked and the exciration energy was concentrated, with the element interval of λR (λR equals the Rayleigh wavelength), the element width of λR/2, and the number of elements of 5. The experimental result showed that the comb Rayleigh wave transducers possessed good directivity and capability of examination of the surface defects of thick walled pipes. © 2017, Science Press. All right reserved.
Keyword ：
Surface defects Surface defects Finite element method Finite element method Rayleigh waves Rayleigh waves Transducers Transducers
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| GB/T 7714 | He, Cunfu , Zhao, Huamin , Lv, Yan et al. New type of flexible comb Rayleigh wave sensor based on the PZT [J]. | Chinese Journal of Scientific Instrument , 2017 , 38 (7) : 1675-1682 . |
| MLA | He, Cunfu et al. "New type of flexible comb Rayleigh wave sensor based on the PZT" . | Chinese Journal of Scientific Instrument 38 . 7 (2017) : 1675-1682 . |
| APA | He, Cunfu , Zhao, Huamin , Lv, Yan , Zheng, Mingfang . New type of flexible comb Rayleigh wave sensor based on the PZT . | Chinese Journal of Scientific Instrument , 2017 , 38 (7) , 1675-1682 . |
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Abstract ：
This paper gives an overview of the development and application of guided waves technique for NDT&E in recent 30 years. Firstly, the fundamental concepts of guided waves propagation and their characteristics are explained, and the mechanical loading principles and mode selection principles for guided wave excitation is analyzed thoroughly. Secondly, the transducer excitation method and its apparatus for ultrasonic guided waves are introduced, then the features and applications are discussed among different excitation methods. Thirdly, ultrasonic guided wave applications in plates, tubes and composite materials are described, meanwhile, the time reversal and the phased array method are introduced to improve the capability of defect detection. Finally, the challenges and opportunities in of guided ultrasonic waves in future are outlined. © 2016, Science Press. All right reserved.
Keyword ：
Nondestructive examination Nondestructive examination Ultrasonic testing Ultrasonic testing Glass ceramics Glass ceramics Antenna phased arrays Antenna phased arrays Guided electromagnetic wave propagation Guided electromagnetic wave propagation Dispersion (waves) Dispersion (waves) Defects Defects Ultrasonic waves Ultrasonic waves
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| GB/T 7714 | He, Cunfu , Zheng, Mingfang , Lv, Yan et al. Development, applications and challenges in ultrasonic guided waves testing technology [J]. | Chinese Journal of Scientific Instrument , 2016 , 37 (8) : 1713-1735 . |
| MLA | He, Cunfu et al. "Development, applications and challenges in ultrasonic guided waves testing technology" . | Chinese Journal of Scientific Instrument 37 . 8 (2016) : 1713-1735 . |
| APA | He, Cunfu , Zheng, Mingfang , Lv, Yan , Deng, Peng , Zhao, Huamin , Liu, Xiucheng et al. Development, applications and challenges in ultrasonic guided waves testing technology . | Chinese Journal of Scientific Instrument , 2016 , 37 (8) , 1713-1735 . |
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