In the present study a new structural health monitoring (SHM) technique isproposed as well as a new damage index based on 2-D error statistics. The proposedtechnique combines the electromechanical impedance technique ...In the present study a new structural health monitoring (SHM) technique isproposed as well as a new damage index based on 2-D error statistics. The proposedtechnique combines the electromechanical impedance technique (EMI) which is based onthe use of piezoelectric Lead Zirconate Titanate (PZT) patches and Scanning LaserDoppler Vibrometry (SLDV) for damage detection purposes of concrete structures andearly age monitoring. Typically the EMI technique utilizes the direct and inversepiezoelectric effect of a PZT patch attached to a host structure via an impedance analyzerthat is used for both the actuation and sensing the response of the PZT-Host structuresystem. In the proposed technique the attached PZTs are actuated via a function generatorand the PZT-Host structure response is obtained by a Scanning Laser DopplerVibrometer. Spectrums of oscillation velocity of the surface of the attached PZTs verticalto the laser beam versus frequency are obtained and are evaluated for SHM purposes.This damage detection approach also includes the use of a damage index denoted asECAR (Ellipse to Circle Area Ratio) based on 2-D error statistics and is compared to theRoot Mean Square Deviation (RMSD) damage index commonly used in SHMapplications. Experimental results include ascending uniaxial compressive load ofconcrete cubic specimens, ascending three point bending of reinforced concrete beamspecimens and early age monitoring of concrete. Results illustrate the efficiency of theproposed technique in damage detection as well as early age monitoring as, in the firstcase, both severity and location of damage can be determined by examining the values ofdamage indices for each damaged state and in the early age monitoring case damageindices follow the strength gain curve.展开更多
Human temporal bone specimens are used in experiments to measure the sound transfer function of the middle ear.This standard method for the development of middle ear implants requires temporal bones that possess appro...Human temporal bone specimens are used in experiments to measure the sound transfer function of the middle ear.This standard method for the development of middle ear implants requires temporal bones that possess appropriate mechanical properties and structural stability and are free from pathological conditions.A laser Doppler vibrometer is commonly employed to measure the vibration of the stapes footplate.These experiments are typically conducted in the middle ear by leaving the inner ear intact,exposing the stapes footplate through the tympanic cavity,and directing the laser beam onto the footplate.However,previous studies have shown that the influence of inner ear impedance on the middle ear transfer function cannot be ignored,and any surgical manipulation may cause a change in inner ear pressure,resulting in instability in the middle ear transfer function.Therefore,this study aims to eliminate the influence of the inner ear and to establish a new experimental method in human temporal bone specimens that is more suitable for the study of sound conduction in middle ear implants.As a result,a range for middle ear transfer function was developed,which serves as a reference for assessing the conformity of temporal bone specimens to experimental standards,and the stability of this range was demonstrated under experimental conditions.展开更多
In the genus Panorpa （Insecta： Mecoptera）, also known as scorpionflies, pre- mating behavior includes repeated sequences of slow wing movements （waving, fanning, flagging） which are accompanied by rapid abdomen v...In the genus Panorpa （Insecta： Mecoptera）, also known as scorpionflies, pre- mating behavior includes repeated sequences of slow wing movements （waving, fanning, flagging） which are accompanied by rapid abdomen vibrations that generate substantial substrate-borne sound. It is still unknown whether wing patterns or vibratory signals contain information about species identity, sex and/or the quality of potential mating part- ners. Besides species-specific pheromones, these multimodal signals may be of particular importance for the maintenance of reproductive isolation in sympatrically occurring scor- pionfly species. Here, we analyzed phyologenetic relationships among, and the pattern of forewings as well as substrate-borne sound in 3 different sympatric Central-European scorpionfly species （P communis, P germanica, and P alpina）. Divergence time estimates, based on 879 bp of the mitochondrial COI gene, indicate longstanding separate evolu- tionary histories for the studied Panorpa species. Morphological analysis revealed that wing length as an indicator of body size increased in the following order： P alpina 〈 P. germanica 〈 P. communis. Individuals can be assigned to the correct species and sex with high accuracy just by evaluation of the number of dark spots and the proportion of wing pigmentation. Despite high variability of interpulse period at an individual level, across species analysis revealed a positive correlation of average interpulse period as well as mean signal amplitude with forewing length. These results suggest wing patterns, but less likely vibratory signals, to contain information about species identity. Furthermore, receivers may be able to estimate the body size of a signaler solely on the basis of substrate-borne sound.展开更多
We demonstrate a compact heterodyne Laser Doppler Vibrometer (LDV) based on the realization of optical frequency shift in the silicon nitride photonic integration platform (TriPleX). We theoretically study, and experi...We demonstrate a compact heterodyne Laser Doppler Vibrometer (LDV) based on the realization of optical frequency shift in the silicon nitride photonic integration platform (TriPleX). We theoretically study, and experimentally evaluate two different photonic integrated optical frequency shifters (OFSs), utilizing serrodyne and single- sideband (SSB) modulation. Both OFSs employ stress-optic modulators (SOMs) based on the non-resonant piezoelectrical actuation of lead zirconate titanate (PZT) thin- films, deposited on top of the silicon nitride waveguides with a wafer-scale process. To improve the modulation bandwidth of the SOMs we investigate a novel configuration of the electrodes used for the actuation, where both electrodes are placed on top of the PZT layer. Using this top-top electrode configuration we report frequency shift of 100 kHz and 2.5 MHz, and suppression ratio of the unwanted sidebands of 22.1 dB and 39 dB, using the serrodyne and the SSB OFS, respectively. The best performing SOM structure induces 0.25π peak-to-peak sinusoidal phase-shift with 156 mW power dissipation at 2.5 MHz. We use the SSB-OFS in our compact LDV system to demonstrate vibration measurements in the kHz regime. The system comprises a dual-polarization coherent detector built in the PolyBoard platform, utilizing hybrid integration of InP photodiodes (PDs). High quality LDV performance with measurement of vibration frequencies up to several hundreds of kHz and displacement resolution of 10 pm are supported with our system.展开更多
文摘In the present study a new structural health monitoring (SHM) technique isproposed as well as a new damage index based on 2-D error statistics. The proposedtechnique combines the electromechanical impedance technique (EMI) which is based onthe use of piezoelectric Lead Zirconate Titanate (PZT) patches and Scanning LaserDoppler Vibrometry (SLDV) for damage detection purposes of concrete structures andearly age monitoring. Typically the EMI technique utilizes the direct and inversepiezoelectric effect of a PZT patch attached to a host structure via an impedance analyzerthat is used for both the actuation and sensing the response of the PZT-Host structuresystem. In the proposed technique the attached PZTs are actuated via a function generatorand the PZT-Host structure response is obtained by a Scanning Laser DopplerVibrometer. Spectrums of oscillation velocity of the surface of the attached PZTs verticalto the laser beam versus frequency are obtained and are evaluated for SHM purposes.This damage detection approach also includes the use of a damage index denoted asECAR (Ellipse to Circle Area Ratio) based on 2-D error statistics and is compared to theRoot Mean Square Deviation (RMSD) damage index commonly used in SHMapplications. Experimental results include ascending uniaxial compressive load ofconcrete cubic specimens, ascending three point bending of reinforced concrete beamspecimens and early age monitoring of concrete. Results illustrate the efficiency of theproposed technique in damage detection as well as early age monitoring as, in the firstcase, both severity and location of damage can be determined by examining the values ofdamage indices for each damaged state and in the early age monitoring case damageindices follow the strength gain curve.
文摘Human temporal bone specimens are used in experiments to measure the sound transfer function of the middle ear.This standard method for the development of middle ear implants requires temporal bones that possess appropriate mechanical properties and structural stability and are free from pathological conditions.A laser Doppler vibrometer is commonly employed to measure the vibration of the stapes footplate.These experiments are typically conducted in the middle ear by leaving the inner ear intact,exposing the stapes footplate through the tympanic cavity,and directing the laser beam onto the footplate.However,previous studies have shown that the influence of inner ear impedance on the middle ear transfer function cannot be ignored,and any surgical manipulation may cause a change in inner ear pressure,resulting in instability in the middle ear transfer function.Therefore,this study aims to eliminate the influence of the inner ear and to establish a new experimental method in human temporal bone specimens that is more suitable for the study of sound conduction in middle ear implants.As a result,a range for middle ear transfer function was developed,which serves as a reference for assessing the conformity of temporal bone specimens to experimental standards,and the stability of this range was demonstrated under experimental conditions.
文摘In the genus Panorpa （Insecta： Mecoptera）, also known as scorpionflies, pre- mating behavior includes repeated sequences of slow wing movements （waving, fanning, flagging） which are accompanied by rapid abdomen vibrations that generate substantial substrate-borne sound. It is still unknown whether wing patterns or vibratory signals contain information about species identity, sex and/or the quality of potential mating part- ners. Besides species-specific pheromones, these multimodal signals may be of particular importance for the maintenance of reproductive isolation in sympatrically occurring scor- pionfly species. Here, we analyzed phyologenetic relationships among, and the pattern of forewings as well as substrate-borne sound in 3 different sympatric Central-European scorpionfly species （P communis, P germanica, and P alpina）. Divergence time estimates, based on 879 bp of the mitochondrial COI gene, indicate longstanding separate evolu- tionary histories for the studied Panorpa species. Morphological analysis revealed that wing length as an indicator of body size increased in the following order： P alpina 〈 P. germanica 〈 P. communis. Individuals can be assigned to the correct species and sex with high accuracy just by evaluation of the number of dark spots and the proportion of wing pigmentation. Despite high variability of interpulse period at an individual level, across species analysis revealed a positive correlation of average interpulse period as well as mean signal amplitude with forewing length. These results suggest wing patterns, but less likely vibratory signals, to contain information about species identity. Furthermore, receivers may be able to estimate the body size of a signaler solely on the basis of substrate-borne sound.
基金EU Horizon 2020 research and innovation program under grant agreement 3PEAT(Contract No.780502).
文摘We demonstrate a compact heterodyne Laser Doppler Vibrometer (LDV) based on the realization of optical frequency shift in the silicon nitride photonic integration platform (TriPleX). We theoretically study, and experimentally evaluate two different photonic integrated optical frequency shifters (OFSs), utilizing serrodyne and single- sideband (SSB) modulation. Both OFSs employ stress-optic modulators (SOMs) based on the non-resonant piezoelectrical actuation of lead zirconate titanate (PZT) thin- films, deposited on top of the silicon nitride waveguides with a wafer-scale process. To improve the modulation bandwidth of the SOMs we investigate a novel configuration of the electrodes used for the actuation, where both electrodes are placed on top of the PZT layer. Using this top-top electrode configuration we report frequency shift of 100 kHz and 2.5 MHz, and suppression ratio of the unwanted sidebands of 22.1 dB and 39 dB, using the serrodyne and the SSB OFS, respectively. The best performing SOM structure induces 0.25π peak-to-peak sinusoidal phase-shift with 156 mW power dissipation at 2.5 MHz. We use the SSB-OFS in our compact LDV system to demonstrate vibration measurements in the kHz regime. The system comprises a dual-polarization coherent detector built in the PolyBoard platform, utilizing hybrid integration of InP photodiodes (PDs). High quality LDV performance with measurement of vibration frequencies up to several hundreds of kHz and displacement resolution of 10 pm are supported with our system.
