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Application of pulse compression technique in metal materials cracks detection with LF-EMATs

NONDESTRUCTIVE TESTING AND EVALUATION 2023年第1期38卷 45-66页

作者： He, Min Shi, Wenze Lu, Chao Chen, Yao Zhao, Liping Dong, Dexiu Zeng, Guangdeng Nanchang Hangkong Univ Key Lab Nondestruct Testing Minist Educ Nanchang Jiangxi Peoples R China Gannan Normal Univ Key Lab Simulat & Numer Modeling Technol Jiangxi Ganzhou Peoples R China AECC Shenyang Liming Aeroengine Co LTD Prod Inspect & Testing Ctr Shenyang Peoples R China Xian Aerosp Composites Res Inst Testing & Anal Ctr Xian Peoples R China

To address the problem of low signal-to-noise ratio (SNR) and poor spatial resolution of cracks detection of the angled SV wave electromagnetic acoustic transducer (EMAT), pulse compression technique (PCT) and line-focusing technique are introduced into the angled SV wave EMAT. A finite element (FE) model of the line-focusing (LF) EMAT detection process based on the Barker code excitation was established, and the effects of the design parameters of magnet and meander-line coil (MLC) on the main lobe amplitude and width of the defect echo after pulse compression were analysed. The optimal combination of LF-EMAT design parameters and excitation parameters was obtained, and it was compared with the traditional angled SV wave EMAT and the tone-burst excitation method by experimental measurements. The results shows that compared with angled SV wave EMAT with tone-burst excitation, LF-EMAT can improve the SNR by 14.9 dB with no synchronous average and be processed by PCT. The SNR from LF-EMAT with PCT is10 dB at 1.5 mm lift-off, while the SNR of the angled SV wave EMAT with tone-burst excitation is less than 0 dB at 1 mm lift-off. When the Barker code PCT is applied to the LF-EMAT detection, we can achieve the purpose of increasing EMAT lift-off and reducing the synchronous averages to meet the demand of online, rapid, and high-temperature detection.

关键词： Line-Focusing EMAT Barker code pulse compression technique signal-to-noise ratio spatial resolution

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Raman Distributed Temperature Sensor Based on pulse compression technique Using Hybrid Modulation Method 12

Raman Distributed Temperature Sensor Based on Pulse Compress...

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Conference on Advanced Sensor Systems and Applications XII

作者： Zeng, Sida Fan, Xinyu He, Zuyuan Shanghai Jiao Tong Univ Dept Elect Engn State Key Lab Adv Opt Syst & Networks 800 Dongchuan Rd Shanghai 200240 Peoples R China Peng Cheng Lab Shenzhen 518055 Guangdong Peoples R China

ISBN: (纸本)9781510657090;9781510657083

In this paper, a novel distributed Raman distributed temperature sensing system based on pulse compression technique using hybrid modulation method is proposed. The structure of the new system and the corresponding modulation and demodulation methods are described. The system performance is verified by experiments. This scheme solves the inherent problem of mutual restrictions between spatial resolution and temperature resolution existed in conventional Raman distributed temperature sensing systems. Compared with other modulation schemes that do not use coding, the hybrid modulation method using in-pulse sweeping and inter-pulse coding can alleviate the transient effect, and reduce the peak power to avoid the influence of nonlinear effect, which improve the signal-to-noise ratio, and obtain a better performance.

关键词： Raman distributed temperature sensor pulse compression technique hybrid modulation method

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Feasibility Study of pulse compression technique to Improve Accuracy of Ultrasonic Temperature Estimation

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BIOMEDICAL ENGINEERING LETTERS 2016年第4期6卷 256-264页

作者： Lee, Su A. Jeong, Jong Seob Dongguk Univ Dept Med Biotechnol Seoul 04620 South Korea

Purpose In this work, we propose pulse compression technique using a chirp signal to improve accuracy of parameters including thermal expansion, propagation velocity of ultrasound, and calibration curve used for converting thermal strain data into its corresponding temperature in the therapeutic ultrasound. Methods The performance of the proposed method was experimentally demonstrated by in vitro experiments using an egg-white phantom and a sliced porcine liver. Measurement of thermal expansion and propagation velocity of ultrasound was done by transferring the specimen from a heating bath to a measuring bath per 5 degrees C temperature resolution. The calibration curve was implemented by combining the measured thermal expansion and propagation velocity of ultrasound. Results In two received signals from a phantom and a sliced porcine liver, the amplitudes of pulse compressed signals were about 35 and 12.5 times higher than sinusoidal signal, respectively. Therefore, core parameters including thermal expansion, propagation velocity of ultrasound, and calibration curve used for ultrasonic temperature estimation were more accurately obtained based on the high sensitivity of pulse compression technique. Conclusions Our study indicates that increasing the amplitude of the received signal is a critical factor in order to obtain more accurate parameters such as thermal expansion, propagation velocity of ultrasound, and calibration curve. The proposed method can be one of the potential ways to increase the sensitivity of the received signal and thus, the accuracy of temperature estimation using ultrasound can be more improved.

关键词： Ultrasound based thermometry pulse compression technique Thermal strain imaging Thermal expansion Propagation velocity Calibration curve

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Experimental evaluation of effects of absorption layer on parametric ultrasound

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JAPANESE JOURNAL OF APPLIED PHYSICS 2023年第SJ期62卷 SJ1027-SJ1027页

作者： Nomura, Hideyuki Imaizumi, Takuma Univ Electrocommun Grad Sch Informat & Engn Chofu Tokyo 1828585 Japan

This study investigated the effects of absorption attenuation on parametric ultrasound (US) for application to low-frequency (LF) US measurement and imaging. The effects of an absorption layer on the sound field and pulsed wave of parametric US at several hundred kilohertz in water were experimentally evaluated via a comparison with LF US directly radiated from a transmitter. The results indicate that the variations of the shape and amplitude of the parametric US field and waveform due to the insertion of an absorber were more significant than those for LF US at the same frequency. However, these effects can be mitigated when an absorber is inserted at a far distance from a transmitter. These results suggest that for the application of parametric US in measurement and imaging, a low-absorption medium must be inserted between a transmitter and absorbing material to be evaluated in order to grow secondary waves sufficiently.

关键词： Low-frequency ultrasound parametric acoustic array parametric sound field pulsed ultrasound wave peak signal-to-noise ratio pulse compression technique absorption attenuation

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An Electromagnetic Sensor Prototype to Assist Visually Impaired and Blind People in Autonomous Walking

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IEEE SENSORS JOURNAL 2018年第6期18卷 2568-2576页

作者： Cardillo, Emanuele Di Mattia, Valentina Manfredi, Giovanni Russo, Paola De Leo, Alfredo Caddemi, Alina Cerri, Graziano Univ Messina Dept Engn I-98166 Messina Italy Univ Politecn Marche Dept Informat Engn I-60131 Ancona Italy Univ Politecn Marche Dept Informat Engn I-60121 Ancona Italy SONDRA Dept Electromagnetism & Radar F-91192 Gif Sur Yvette France

The feasibility of an electromagnetic sensor to assist the autonomous walking of visually impaired and blind users is demonstrated in this paper. It is known that the people affected by visual diseases usually walk assisted by some supports, among which the white cane is the most common. Our idea consists in applying a microwave radar on the traditional white cane making aware the user about the presence of an obstacle in a wider and safer range. Compared to the already existing electronic travel aids devices, the proposed system exhibits better performance, noise tolerance, and reduced dimensions. In the following, the latest developments of this research activity are presented, with special concern for the miniaturization of circuit board and antennas. A laboratory prototype has been designed and realized and the first test results of obstacle detection are hereby shown to demonstrate the effectiveness of the system.

关键词： Electronic travel aids visually impaired assistance autonomous walking short-range radar pulse compression technique

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Comparison of Additive and Multiplicative Complementary Sequences for Navigation and Flight Control Systems 5

Comparison of Additive and Multiplicative Complementary Sequ...

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5th IEEE International Conference on Methods and Systems of Navigation and Motion Control (MSNMC)

作者： Holubnychyi, A. G. Konakhovych, G. F. Taranenko, A. G. Gabrousenko, Ye. I. Natl Aviat Univ Dept Telecommun Syst Kiev Ukraine Natl Aviat Univ Dept Elect Devices & Syst Kiev Ukraine

ISBN: (纸本)9781538658703

Navigation and flight control systems often use pulse compression techniques combined with the matched filtering approach as the main signal processing scheme. Golay complementary sequences are well known signal constructions for the pulse compression technique, which are additive complementary sequences in terms of the nature of their signal processing. The similar multiplicative complementary sequences also exsist. The comparison of additive and multiplicative complementary sequences is given in the paper.

关键词： Golay complementary sequences pulse compression technique navigation system flight control

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Free Space Antenna Factor Computation Using Time Domain Gating and Deconvolution Filter for Site Validation of Fully Anechoic Rooms

Free Space Antenna Factor Computation Using Time Domain Gati...

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IEEE International Symposium on Electromagnetic Compatibility and Signal/Power Integrity (EMCSI)

作者： Adhyapak, Anoop Chen, Zhong Shimada, Kazuo ETS Lindgren Inc 1301 Arrow Point Dr Cedar Pk TX 78613 USA ETS Lindgren Japan Inc 4-2-6 Kohinata Tokyo Japan

ISBN: (纸本)9781538622315

An alternative method to compute the free space antenna factor using time domain transformation and deconvolution filter for pulse compression is proposed. The deconvolution filter helps in compressing the time domain pulse to distinguish the direct wave from the reflected wave and help evaluate the free space antenna factor for site validation of fully anechoic rooms. The antenna pair of ETS-Lindgren Model 3110C and 3180C antennas, simulated with NEC, is subjected to the proposed method with deconvolution filter and Wiener filter. The proposed method is implemented over the measured results of the antenna pair and used for the site validation of a fully anechoic room, based on the simulation results. The Free Space Normalized Site Attenuation Results comply with the 4 dB specification.

关键词： Free space antenna factor pulse compression technique time domain transformation

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A Real-time Monitoring technique for Local Plasticity in Metals Based on Lamb Waves and a Directional Actuator/Sensor Set

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CMC-COMPUTERS MATERIALS & CONTINUA 2014年第1期40卷 1-20页

作者： Liu, Y. L. Hu, N. Xu, H. Ning, H. Wu, L. K. Chiba Univ Dept Mech Engn Chiba Japan Chongqing Univ Coll Aerosp Engn Chongqing 630044 Peoples R China Beijing Univ Chem Technol Mech & Elect Engn Inst Beijing 100029 Peoples R China

A real-time monitoring technique for local plasticity using Lamb waves was developed. Tensile test of a thin aluminum plate with a circular hole where high stress concentration was induced was conducted to verify this technique. During the tensile test, a series of wave signals passing through the local plastic region were collected using a directional actuator/sensor set to monitor plasticity evolution. A pulse compression technique was used to process the wave signals. With the increase of tensile stress in the specimen, the amplitude changes of S-0 and A(0) modes were obtained and the difference of Lamb wave signals was further evaluated using a proposed signal index I calculated by wavelet analysis. Combined with the numerical stress analysis of the tensile specimen, the influence of the plasticity on the amplitudes of S-0 and A(0) wave modes was analyzed. As the plastic zone grows gradually, the wave amplitudes and I of S-0 and A(0) wave modes show their different change tendencies compared with those in elastic stage. The amplitude change is more sensitive to mild plasticity than that of I, while the change of I caused by severe plasticity is more obvious than the amplitude change.

关键词： Lamb waves local plasticity pulse compression technique wavelet analysis

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A 24-GHz CMOS UWB Radar Transmitter With Compressed pulses

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IEEE TRANSACTIONS ON MICROWAVE THEORY AND techniqueS 2012年第4期60卷 1117-1125页

作者： Yang, Jaemo Pyo, Gitae Kim, Choul-Young Hong, Songcheol Korea Adv Inst Sci & Technol Dept Elect Engn Taejon 305701 South Korea Chungnam Natl Univ Dept Elect Engn Taejon 305764 South Korea

A fully integrated 24-GHz CMOS ultra-wideband (UWB) radar transmitter for short-range automotive application is presented. For high-range resolution and improved signal-to-noise ratio, a pulse compression technique using binary phase code is adopted. Design issues of UWB radar transmitter are investigated based on fundamental pulse theory. A pulse former, which operates as a switch to generate a pulse modulated carrier signal and a bi-phase modulator for pulse compression, is proposed. The proposed transmitter achieves 4-GHz output signal bandwidth, which means a minimum range resolution of 7.5 cm, and the total dc power dissipation is 63 mW.

关键词： Automotive radar binary phase modulation CMOS compressed pulse pulse compression technique ultra-wideband (UWB) UWB radar transmitter

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Comment on 'multi-range-resolution radar using sideband spectrum energy'

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IET RADAR SONAR AND NAVIGATION 2007年第3期1卷 248-248页

作者： Levanon, Nadav Tel Aviv Univ Tel Aviv Israel

No abstract available

关键词： radar signal processing frequency response mismatched filter multi-range-resolution radar radar receivers signal-to-noise ratio Filters and other networks power spectral density matched filter receiver sideband spectrum energy matched filters Radar equipment, systems and applications sidelobe frequency Signal processing and detection transmitted waveform pulse compression technique spectral mainlobe

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