检索结果-内蒙古大学图书馆

Experiment study of long pulse eddy current / eddy current pulse-compression thermography detection on large area with low-frequency and low-current

引用

MEASUREMENT 2025年 243卷

作者： Xiao, Xiang-Tao Xia, Jie Tang, Song Kong, Chunyan Zhang, Liang Xihua Univ Sch Mech Engn Chengdu 610039 Peoples R China Southwest Petr Univ Sch Mech Engn Chengdu 610500 Peoples R China

Eddy current pulsed thermography (ECPT) excited by high-frequency and high-current is at risk of causing irreparable damage to the detection object. Furthermore, using a high-current excitation pattern in flammable and explosive environments is strictly prohibited. To cope with that limitation, long pulse eddy current thermography (LPECT) and eddy current pulse-compression thermography (ECPuCT), which work in weakened excitation conditions, are two reasonable technologies. The LPECT experiment in low-frequency (50 Hz) excitation shows that subsurface defects are detected when the current is 8.3 A. Compared with LPECT, the experiment results of 13-bit barker-coded ECPuCT show the possibility of further reducing the excitation current and improving the defect detection signal-noise ratio (SNR). With a two-coil magnetic core inductor, defects whose aspect ratio is over 6 in a large area are effectively detected by ECPuCT. That confirms LPECT and ECPuCT are suited for high-risk environments, such as the petrochemical field.

关键词： Eddy current thermography Large area pulse-compression Two-coil magnetic core inductor Low-frequency and low-current

来源：评论

学校读者我要写书评

暂无评论

Optimization of the pulse-compression technique applied to the infrared thermography nondestructive evaluation

引用

NDT & E INTERNATIONAL 2017年 87卷 100-110页

作者： Silipigni, Giuseppe Burrascano, Pietro Hutchins, David A. Laureti, Stefano Petrucci, Roberto Senni, Luca Torre, Luigi Ricci, Marco Univ Perugia Dipartimento Ingn Polo Sci Didatt Terni Str Pentima 4 I-05100 Terni Italy Univ Warwick Sch Engn Lib Rd Coventry CV4 7AL W Midlands England Univ Perugia Dipartimento Ingn Civile & Ambientale Polo Sci Didatt Terni Str Pentima 4 I-05100 Terni Italy Univ Calabria Dipartimento Ingn Informat Modellist Elettron & S Via Pietro Bucci I-87036 Arcavacata Di Rende CS Italy

pulse-compression infrared thermography is an emerging nondestructive testing and evaluation technique. An analysis of the main issues hampering the full exploitation of this technique is presented from both theoretical and experimental point of view and various strategies are introduced to overcome these problems and optimize the defect detection performance. A comparison between conventional pulse-compression thermography procedures and the proposed one is reported, using an LED modulated with a Barker sequence as coded excitation, and a carbon fibre composite benchmark sample containing artificial defects at different depths. The experimental results show that the suggested signal processing procedure assures a higher SNR and hence an improved defect detection capability. In addition, a time-analysis of such signals allows the correlation between the depth of defects and heat diffusion time to be more clearly identified.

关键词： Nondestructive evaluation Thermography Coded excitation pulse-compression Barker codes

来源：评论

学校读者我要写书评

暂无评论

Comparison of optimisation strategies for the improvement of depth detection capability of pulse-compression Thermography

引用

QUANTITATIVE INFRARED THERMOGRAPHY JOURNAL 2020年第1期17卷 26-39页

作者： Malekmohammadi, H. Laureti, S. Burrascano, P. Ricci, M. Univ Perugia Dept Engn Str Pentima 4 I-05100 Terni TR Italy Univ Calabria Dept Informat Modeling Elect & Syst Engn Arcavacata Di Rende CS Italy

In pulse-compression Thermography, the impulse response of the Sample Under Test is retrieved pixelwise by applying a proper matched filter on the set of acquired thermal images obtained by stimulating the system with a heat source amplitude - modulated by a proper coded signal. Linear frequency-modulated chirp signals and binary codes are the most employed coded excitations, and to improve the detection capability of the technique, a non-linear frequency-modulated chirp signal can be used to deliver more energy to the sample in a frequency range of interest. In this work, we report the application of an exponential chirp to modulate the heating source and we compare it with a standard linear chirp excitation. To do a fair comparison, various windowing functions have been applied on the matched filters to reduce range side lobes, thus enhancing the retrieved impulse response quality. It is shown that the combined use of an exponential chirp and an appropriate matched filter obtained by exploiting the Reactance Transform window provides a faithful reconstruction of the sample impulse response and an enhanced signal-to-noise ratio with respect to the use of linear chirp. This has been demonstrated on a 3D-printed polymethyl methacrylate (PMMA) sample containing 16 flat-bottom holes of different depths.

关键词： pulse-compression thermography windowing matched filter 3D-printed PMMA

来源：评论

学校读者我要写书评

暂无评论

The use of pulse-compression thermography for detecting defects in paintings

引用

NDT & E INTERNATIONAL 2018年 98卷 147-154页

作者： Laureti, S. Sfarra, S. Malekmohammadi, H. Burrascano, P. Hutchins, D. A. Senni, L. Silipigni, G. Maldague, X. P. V. Ricci, M. Univ Perugia Polo Sci Didattico Terni Dept Engn Str Pentirna 4 Terni Italy Univ Aquila Dept Ind & Informat Engn & Econ Piazzale E Pontieri 1 I-67100 Laquila AQ Italy Univ Warwick Sch Engn Lib Rd Coventry CV4 7AL W Midlands England Laval Univ Dept Elect & Comp Engn 1065 Av Med Quebec City PQ G1V 0A6 Canada Univ Calabria Dept Informat Modeling Elect & Syst Engn Via Pietro Bucci I-87036 Arcavacata Di Rende Italy

Interest in the conservation of paintings grows year by year. Their periodic inspection is essential for their conservation over the time. Thermographic non-destructive inspection is one technique useful for paintings, but it is essential to be able to detect buried defects while minimising the level of thermal stimulus. This paper describes a pulse-compression infrared thermography technique whereby defect detection is optimized while minimising the rise in temperature. To accomplish this task, LED lamps driven by a coded waveform based on a linear frequency modulated chirp signal have been used on paintings on both a wooden panel and a canvas layer. These specimens contained artificially fabricated defects. Although the physical condition of each painting was different, the experimental results show that the proposed signal processing procedure is able to detect defects using a low temperature contrast.

关键词： Thermography Coded excitation pulse-compression Paintings

来源：评论

学校读者我要写书评

暂无评论

A 4-GS/s 80-dB DR Current-Domain Analog Frontend for Phase-Coded pulse-compression Direct Time-of-Flight Automotive Lidar

引用

IEEE JOURNAL OF SOLID-STATE CIRCUITS 2020年第12期55卷 3131-3145页

作者： Kashmiri, Mahdi Behroozpour, Behnam Petkov, Vladimir P. Wojciechowski, Kenneth E. Lang, Christoph Robert Bosch Res & Technol Ctr North Amer Sunnyvale CA 94085 USA SiLC Technol Inc Monrovia CA 91016 USA

A 4-GS/s current-domain analog front end (CurAFE) for phase-coded pulse-compression direct time- offlight (dTOF) automotive Lidar has been realized in 130-nm CMOS. The permissible eye-safe laser energy is transmitted in the form of a burst of optical sub-pulses. The burst embeds a phase coding designed to have an auto-correlation function with a maximum peak-to-sidelobe ratio. The optical reflection of this burst, reflected from a target, is then detected by an avalanche photodiode (APD). The APD's output current drives the CurAFE, whose 4-GS/s single-bit output is processed by a digital matched filter for pulse-compression and TOF estimation through cross correlation. The 200-MHz bandwidth frontend detects bursts with bitrates up to 200 Mb/s (5-ns sub-pulsewidth) and is designed for >80-dB DR without saturation and 5-pA/root Hz input-referred noise. A current-feedback dc servo loop at its input cancels the background-light-induced detector current. Compared to state-of-the-art single-pulse Lidars, operating with peak optical transmit powers similar to 50 W, this work achieves an inaccuracy of 0.225 m (1 sigma) over 60-m range at >10x lower peak transmit power of similar to 3.5 W.

关键词： Analog frontend (AFE) auto-zero avalanche photodiode (APD) cross correlation current domain laser lidar matched filter phase code photodetector pulse-compression self-calibration time-interleaved analog-to-digital converter (ADC)

来源：评论

学校读者我要写书评

暂无评论

New features for delamination depth evaluation in carbon fiber reinforced plastic materials using eddy current pulse-compression thermography

引用

NDT & E INTERNATIONAL 2019年 102卷 264-273页

作者： Yi, Q. Tian, G. Y. Malekmohammadi, H. Zhu, J. Laureti, S. Ricci, M. Newcastle Univ Dept Elect & Elect Engn Newcastle Upon Tyne NE1 7RU Tyne & Wear England Univ Perugia Dept Engn Polo Sci Didatt Terni Str Pentima 4 I-05100 Terni Italy Univ Calabria Dept Informat Modeling Elect & Syst Engn I-87036 Arcavacata Di Rende Italy

The growing application of composite materials in aerospace leads to the urgent need of non-destructive testing and evaluation (NDT&E) techniques capable of detecting defects such as impact damage and delamination possibly existing in those materials. Eddy current pulsed thermography is an emerging non-destructive testing (NDT) technique capable of detecting such defects. However, characterization of delamination within composite materials is difficult to be achieved by a single pulse excitation, especially in carbon fiber reinforced plastic materials as the extraction of thermal diffusion in such multi-layered structures is challenging. To cope with this problem of signal-to-noise ratio, this paper proposes the eddy current pulse-compression thermography (ECPuCT), combining the Barker code modulated eddy current excitation and pulse-compression technique to enhance the capability of characterizing delamination on carbon fiber reinforced plastic materials. Additionally, a thermal pattern enhanced method based on kernel principal component analysis technique is used to locate the delaminated areas. Two features, including a newly proposed crossing point of impulse responses related to defective and non-defective areas and skewness of impulse responses are investigated for delamination depth evaluation. Results show that delamination can be detected within depths ranging from 0.46 mm to 2.30 mm and both the proposed features have a monotonic relationship with delamination depths.

关键词： pulse-compression Eddy current pulsed thermography Feature extraction Carbon fiber reinforced plastic Delamination depth Barker code

来源：评论

学校读者我要写书评

暂无评论

Effects of FM linearity of linear FM signals on pulse-compression performance

Effects of FM linearity of linear FM signals on pulse-compre...

引用

CIE International Conference on Radar

作者： Hu, Shibing Wang, Xuegang Si, Qiang Univ Elect Sci & Technol China Coll Elect Engn Chengdu 610054 Peoples R China

ISBN: (纸本)9780780395824

The linear FM signals are being widely used in modern radar systems. But the FM linearity of such signals is one of the important factors that affect the quality of signals generated by linear FM waveform generation systems. The models of several types of frequency deviation function are made in this paper. And the effects of different kinds of FM linearity on the pulse-compression performance of output signals are investigated in detail. The computer simulation results are presented and prove the conclusions. All of the conclusions obtained by theoretical analyses and computer simulations provide important theoretical bases and experiential references for the parameters selection, performance evaluation and performance optimization of the engineering implementation of ultra wideband linear FM signal generators.

关键词： linear FM signal FM linearity frequency deviation function matched-filter pulse-compression

来源：评论

学校读者我要写书评

暂无评论

Experimental demonstration of pulse-compression ghost imaging via coherent detection

Experimental demonstration of pulse-compression ghost imagin...

引用

Applied Optics and Photonics China (AOPC) Conference - Optical Sensing and Imaging Technology

作者： Pan, Long Deng, Chenjin Gong, Wenlin Han, Shensheng Chinese Acad Sci Shanghai Inst Opt & Fine Mech Key Lab Quantum Opt Shanghai 201800 Peoples R China Univ Chinese Acad Sci Beijing 100049 Peoples R China Univ Chinese Acad Sci Hangzhou Inst Adv Study Hangzhou 310024 Peoples R China

ISBN: (纸本)9781510639560

By combing the technique of coherent detection with ghost imaging, we establish an experimental system for pulse-compression ghost imaging via coherent detection. The results have experimentally demonstrated for the first time the feasibility of ghost imaging via coherent detection. More importantly, it shows that even when echo power is only 5 pW, which is lower than three orders of magnitude compared with previous ghost imaging via photon intensity detection, an image with a spatial resolution of 0.8 mm can be obtained for the proposed method.

关键词： Ghost Imaging Coherent Detection pulse-compression Chirped-amplitude Modulation

来源：评论

学校读者我要写书评

暂无评论

Long-range coherent lidar based on pulse-compression 7

Long-range coherent lidar based on pulse-compression

引用

7th Symposium on Novel Photoelectronic Detection Technology and Applications

作者： Yang, Jing Zhao, Bin Liu, Bo Chinese Acad Sci Inst Opt & Elect Key Lab Sci & Technol Space Optoelect Precis Meas CAS Chengdu 610209 Peoples R China Univ Chinese Acad Sci Beijing 10049 Beijing Peoples R China

ISBN: (数字)9781510643628

ISBN: (纸本)9781510643628

A low-peak chirp-modulated long-pulse signal can be compressed into a high-peak narrow pulse by using pulse-compression, thereby improving the sensitivity and resolution of lidar. In this paper, we optimized a pulse-compression lidar system to greatly improve the detection range. We take absolute scheme to process I\Q signals when signal-to-noise ratio (SNR) is smaller than 1. The voltage amplitude resolution of oscilloscope is improved to increase SNR. With these important improvements, the system can measure a building about 5.725 km away. We explore and demonstrate the long-range performance of this system in detail. The standard deviation of one single measurement is 1.82 m and reduces to 0.69 m after 10 accumulations

关键词： chirp modulation pulse-compression lidar coherent

来源：评论

学校读者我要写书评

暂无评论

Distributed Fiber Birefringence Measurement Using pulse-compressionФ-OTDR

引用

Photonic Sensors 2021年第4期11卷 402-410页

作者： Yongxiang CHEN Yun FU Ji XIONG Zinan WANG Key Lab of Optical Fiber Sensing&Communications University of Electronic ScienceTechnology of ChinaChengdu 611731China

In this paper,a novel birefringence measurement method through the Rayleigh backscattered lightwave within single-mode fiber is proposed,using a single chirped-pulse with arbitrary state of *** analysis is carried out in detail,then pulse-compression phase-sensitive optical time domain reflectometry(PC-O-OTDR)with polarization-diverse coherent detection is employed to verify this method.A 2 km spun single-mode fiber is tested with 8.6cm spatial resolution,and the average birefringence of the fiber under test is measured as 0.234rad/m,which is consistent with previous literatures about single-mode ***,the relationship between the measured birefringence and the spatial resolution is also studied for the first time,and the results show that spatial resolution is crucial for fiber birefringence measurement.

关键词： Birefringence Rayleigh scattering pulse-compression phase-sensitive optical time-domain reflectometiy coherent detection polarization-diverse receiver

来源：评论

学校读者我要写书评

暂无评论

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

请选择保存的检索档案：

请选择收藏分类：

通借通还

建议与咨询 留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

请选择保存的检索档案： 新增检索档案 确定 取消

请选择收藏分类： 新增自定义分类 确定 取消

通借通还

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

请选择保存的检索档案：

请选择收藏分类：