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Chinese Physics B 2019年第7期28卷 286-292页

作者： Hui Zhang Hai-Yan Zhang Meng-Yun Xu Guo-Peng Fan Wen-Fa Zhu Xiao-Dong Chai Shanghai Institute for Advanced Communication and Data Science School of Communication and Information Engineering Shanghai University Shanghai 200444 China School of Urban Railway Transportation Shanghai University of Engineering Science Shanghai 201620 China

A method of combining Green’s function retrieval theory and ultrasonic array imaging using lamb waves is presented to solve near filed defects in thin aluminum *** defects are close to the ultrasonic phased array and satisfy the near field calculation *** field acoustic information of defects is obscured by the nonlinear effects of initial wave signal in a directly acquired response using the full matrix capture mode.A reconstructed full matrix of inter-element responses is produced from cross-correlation of directly received ultrasonic signals between sensor *** new matrix eliminates the nonlinear interference and restores the near-field defect *** topological imaging method that was developed in recent ultrasonic inspection is used for displaying the *** experiments are conducted on both thin aluminum plates containing two and four defects, *** results show that these defects are clearly identified when using a reconstructed full *** spatial resolution is equal to about one wavelength of the selectively excited mode and the identifiable defect is about one fifth of the ***, in a conventional directly captured image,the images of defects overlap together and cannot be *** proposed method reduces the background noise and allows for effective topological imaging of near field defects.

关键词： lamb waves topological imaging cross-correlation Green’s function

lamb wave sensors array for nonviscous liquid sensing

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Science China(Physics,Mechanics & Astronomy) 2006年第4期49卷 461-472页

作者： CHEN Zhijun HAN Tao JI Xiaojun GUO Huawei SHI Wenkang Department of Instrumentation Engineering Shanghai Jiao Tong University Shanghai 200240 China Department of Instrumentation Engineering Shanghai Jiao Tong University Shanghai 200240 China Department of Instrumentation Engineering Shanghai Jiao Tong University Shanghai 200240 China Department of Instrumentation Engineering Shanghai Jiao Tong University Shanghai 200240 China Department of Instrumentation Engineering Shanghai Jiao Tong University Shanghai 200240 China

The interdigital transducer (IDT) can excite lamb wave in a piezoelectric plate loading with a liquid layer, and the phase velocity of lamb wave is associated with the properties of the liquid layer. In this paper, the concept of effective permittivity is introduced to study the lamb wave's potential application in liquid sensing. Considering the measuring of ideal nonviscous liquid, the sensors array is designed to sense the density and the dielectric constant of the liquid layer simultaneously. Using LiNbO3 as piezoelectric material, in order to improve the sensors array sensitivity and the electro-mechanical coupling coefficient, the optimized results including plate thicknesses and cut orientations are presented by numerical simulation. These studies show that the lamb wave sensors array can be potential in liquid sensing.

关键词： lamb wave sensors array, density, dielectric constant, plate thickness, cut orientation.

A lamb wave signal reconstruction method for high-resolution damage imaging

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Chinese Journal of Aeronautics 2019年第5期32卷 1087-1099页

作者： Xiaopeng WANG Jian CAI Zhiquan ZHOU State Key Lab of Mechanics and Control of Mechanical Structures Nanjing University of Aeronautics and Astronautics

In lamb wave-based Structural Health Monitoring(SHM), a high-enough spatial resolution is highly required for lamb wave signals to ensure the resolution and accuracy of damage detection. However, besides the dispersion characteristic, the signal spatial resolution is also largely restricted by the space duration of excitation waveforms, i.e., the Initial Spatial Resolution(ISR)for the signals before travelling. To resolve the problem of inferior signal spatial resolution of lamb waves, a lamb Wave Signal Reconstruction(LWSR) method is presented and applied for highresolution damage imaging in this paper. In LWSR, not only a new linearly-dispersive signal is reconstructed from an original lamb wave signal, but also the group velocity at the central frequency is sufficiently decreased. Then, both dispersion compensation and ISR improvement can be realized to achieve a satisfying signal spatial resolution. After the frequency domain sensing model and spatial resolution of lamb wave signals are firstly analyzed, the basic idea and numerical realization of LWSR are discussed. Numerical simulations are also implemented to preliminarily validate LWSR. Subsequently, LWSR-based high-resolution damage imaging is developed. An experiment of adjacent multiple damage identification is finally conducted to demonstrate the efficiency of LWSR and LWSR-based imaging methods.

关键词： Damage imaging Dispersion compensation High resolution lamb waves Signal reconstruction

Decomposition of the Two Lowest lamb modes in a Bonded Plate

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Chinese Physics Letters 2003年第7期20卷 1084-1087页

作者：王小民廉国选李明轩 InstituteofAcoustics ChineseAcademyofSciencesBeijing100080

Based on the expression of the dispersion equation of lamb waves in an adhesive two-layered plate presented in our previous paper [Chin. Phys. Lett. 18(2001)1483], the two lowest lamb modes, the symmetric mode S_0 and the antisymmetric mode A_0 are successfully decomposed in the low-frequency regime. Relations between the rigidity of the bond and the velocity of the two lamb modes are found, which lay a foundation for the estimation of the bond rigidity of the adhesive plate. The influence of the variations of the bond rigidity in terms of the stiffness constants K_N and K_T of the spring model on the velocity of the two lamb modes is discussed and numerically evaluated. Numerical results indicate that the deterioration of the bond rigidity causes the phase velocity decrease for lamb modes of the two lowest order, thus having a possibility for the evaluation of the bonding state of the adhesive plate by using ultrasonic wave velocity measurement.

关键词： stiffness lamb speed Velocimetry Speed measurement phase velocity Lowest

Multiphysics simulation method of lamb wavepropagation with piezoelectric transducers under load condition

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Chinese Journal of Aeronautics 2019年第5期32卷 1071-1086页

作者： Lei QIU Xixi YAN Xiaodong LIN Shenfang YUAN Research Center of Structural Health Monitoring and Prognosis State Key Lab of Mechanics and Control of Mechanical Structures Nanjing University of Aeronautics and Astronautics

lamb Wave(LW) simulation under time-varying conditions is an effective and low cost way to study the problem of the low reliability of the structural health monitoring methods based on the LW and Piezoelectric Transducer(PT). In this paper, a multiphysics simulation method of the LW propagation with the PTs under load condition is proposed. With this method, two key mechanisms of the load influence on the LW propagation are considered and coupled with each other. The first mechanism is the acoustoelastic effect which is the main reason of the LW velocity change. The second key mechanism is the load influence on piezoelectric materials, which results in a change of the amplitude. Based on the computational platform of the COMSOL Multiphysics, a multiphysics simulation model of the LW propagation with the PTs under load condition is established. The simulation model includes two physical phenomena. The first one is called solid mechanics, which is used to simulate the acoustoelastic effect being combined with the hyperelastic material properties of the structure in which the LW propagates. The second one is called electromechanical coupling, which considers the simulation of the piezoelectric effect of the PTs for the LW excitation and sensing. To simulate the load influence on piezoelectric materials, a non-linear numerical model of the relationship between the load and the piezoelectric coefficient d31 is established based on an experiment of the load influence on the LW. The simulation results under uniaxial tensile load condition are obtained and are compared with the data obtained from the experiment. It shows that the variations of the phase velocity and amplitude of the LW obtained from the simulation model match the experimental results well.

关键词： Acoustoelastic effect lamb wave Multiphysics simulation Piezoelectric coefficient Structural health monitoring Time-varying condition

Effects of lairage after transport on post mortem muscle glycolysis, protein phosphorylation and lamb meat quality

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Journal of Integrative Agriculture 2018年第10期17卷 2336-2344页

作者： LI Xin XIA An-qi CHEN Li-juan DU Man-ting CHEN Li KANG Ning ZHANG De-quan Institute of Food Science and Technology Chinese Academy of Agricultural Sciences/Key Laboratory of Agro-Products Processing Ministry of Agriculture

The objective of this study was to investigate the effect of lairage after transport on post mortem muscle glycolysis,protein phosphorylation and lamb meat *** preslaughter animal treatments,transport for 3 h and lairage for 0 h（T3L0）and transport for 3 h and then lairage for 12 h（T3L12）,were compared with a control treatment of 0 h transport and 0 h *** obtained showed that preslaughter transport had a significant effect on lamb meat *** from lambs of the T3L0 treatment showed higher（P=0.026）pH24 h and higher（P=0.021）pH48 h values,but lower（P〈0.001）drip loss and lower（P〈0.05）glycolytic potential at 0 h post mortem than those of the T3L12 and control *** samples of the T3L0 group showed higher（P=0.046）shear force and lower（P=0.005）b＊ value than those of the T3L12 *** glycogen concentration at 0,2,4 h post mortem were lower（P〈0.05）in the T3L0 group than in *** significant difference（P〉0.05）in most meat quality parameters was determined between the T3L12 group and control,showing lairage for 12 h allowed lambs to recover from the effects of transport for 3 h and resulted in similar meat quality characteristics compared to no *** after transport did not affect most meat quality indices in comparison with control,but increased the meat drip loss and b＊value of lambs possibly through decreasing glycogen concentration and glycolytic potential.

关键词： lamb transport lairage meat quality glycolytic metabolite protein phosphorylation

Transcriptomic analysis reveals the molecular mechanisms of rumen wall morphological and functional development induced by different solid diet introduction in a lamb model

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Journal of Animal Science and Biotechnology 2021年第3期12卷 1169-1183页

作者： Daming Sun Yuyang Yin Changzheng Guo Lixiang Liu Shengyong Mao Weiyun Zhu Junhua Liu Jiangsu Key Laboratory of Gastrointestinal Nutrition and Animal Health Laboratory of Gastrointestinal MicrobiologyCollege of Animal Science and TechnologyNanjing Agricultural UniversityNanjing 210095Jiangsu ProvinceChina National Center for International Research on Animal Gut Nutrition Nanjing Agricultural UniversityNanjing 210095China National Experimental Teaching Demonstration Center of Animal Science Nanjing Agricultural UniversityNanjing 210095China Huzhou Academy of Agricultural Sciences Huzhou 313000China

Background:This study aimed to elucidate the molecular mechanisms of solid diet introduction initiating the cellular growth and maturation of rumen tissues and characterize the shared and unique biological processes upon different solid diet ***:Twenty-four Hu lambs were randomly allocated to three groups fed following diets:goat milk powder only(M,n=8),goat milk powder+alfalfa hay(MH,n=8),and goat milk powder+concentrate starter(MC,n=8).At 42 days of age,the lambs were *** fluid sample was collected for analysis of concentration of volatile fatty acid(VFA)and microbial crude protein(MCP).The sample of the rumen wall from the ventral sac was collected for analysis of rumen papilla morphology and ***:Compared with the M group,MH and MC group had a higher concentration of VFA,MCP,rumen weight,and rumen papilla *** transcriptomic results of rumen wall showed that there were 312 shared differentially expressed genes(DEGs)between in“MH vs.M”and“MC vs.M”,and 232 or 796 unique DEGs observed in“MH vs.M”or“MC vs.M”,*** shared DEGs were most enriched in VFA absorption and metabolism,such as peroxisome proliferator-activated receptor(PPAR)signaling pathway,butanoate metabolism,and synthesis and degradation of ketone ***,a weighted gene co-expression network analysis identified M16(2,052 genes)and M18(579 genes)modules were positively correlated with VFA and rumen wall *** M16 module was mainly related to metabolism pathway,while the M18 module was mainly associated with signaling ***,hay specifically depressed expression of genes involved in cytokine production,immune response,and immunocyte activation,and concentrate starter mainly altered nutrient transport and metabolism,especially ion transport,amino acid,and fatty acid ***:The energy production during VFA metabolism may drive the rumen wall development *** hay introduction facilitated est

关键词： Concentrate Hay lamb Rumen development Transcriptome

Numerical simulation and experimental detection of leaky lamb waves induced by pulse laser at air-solid interfaces

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Science China(Physics,Mechanics & Astronomy) 2008年第6期51卷 607-616页

作者： ZHAO Yan SHEN ZhongHua LU Jian NI XiaoWu School of Science Nanjing University of Science&TechnologyNanjing 210094China

Based on the thermoelastic mechanism of laser ultrasonic, the problems of the thermal conduction and the coupling between the motion of solid and fluid are solved by using the finite element method. And then the transient waveforms of leaky lamb waves induced by pulse laser action on the air-aluminum interface are obtained. Experimental signals of laser-induced leaky lamb waves at the air-alu- minum interface are detected by applying an our-developed detector, based on the light deflection principle. The dispersion and attenuation properties of leaky lamb waves are analyzed through the phase spectral analysis.

关键词： laser ultrasonic leaky lamb wave air-solid interface finite element method light deflection

Detection of Amines in lamb Spoilage by Optical Waveguide Sensor Based on Bromophenol Blue-Silicon Composite Film

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Chemical Research in Chinese Universities 2019年第2期35卷 193-199页

作者： KOXMAK Sayyara YIMAMUMAIMAITI Tajiguli ABDUKEREMU Hannikezi NIZAMIDIN Patima YIMIT Abliz College of Chemistry and Chemical Engineering Xinjiang UniversityUrumqi 830046P.R.China State Key Laboratory of Analytical Chemistry for Life Science Collaborative Innovation of Chemistry for Life ScienceSchool of Chemistry and Chemical EngineeringNanjing UniversityNanjing 210093P.R.China

We herein report the development of a bromophenol blue(BPB)-silicone composite film/K^+-exchange glass optical waveguide(OWG)sensor for the detection of amines produced during the spoilage of *** optical and structural properties of the sensitive thin film were studied by ultra violet-visible(UV-Vis)spectroscopy,and the light source of the OWG detecting system was *** sensing measurements showed that the sensor exhibited a good selectivity,higli sensitivity,and short response-recovery time towards volatile amine gases in the 0.00117一11.72 mg/g *** as-prepared optical waveguide device was subsequently applied in the determination of gases(namely trimethylamine,dimethylamine,and ammonia)emitted from the lamb samples(5g)stored at room temperature(25℃)and in a refrigerator(5℃)for 0—4 d,and the total volatile basic nitrogen(TVB-N)contents were detected by UV-Vis spectroscopy,and the results were compared witli those obtained using our *** was found that the sensing element was capable of detecting mixed gases produced by the decomposition of lamb samples in a refrigerator for 0.5 h,where the TVB-N content was lower than 35μg/g.

关键词： Optical waveguide sensor Composite film Amine gas lamb freslmess detection

Research on Morlet Wavelet Based lamb Wave Spatial Sampling Signal Optimization Method

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Journal of Shanghai Jiaotong university(Science) 2018年第S1期23卷 62-69页

作者： LIU Bin LIU Tingzhang MENG Fanqin School of Mechatronic Engineering and Automation Shanghai University Shanghai 200444 China Department of Military Supply and Fuel Air Force Logistics College Xuzhou 221006 Jiangsu China

In recent years, lamb wave and piezoelectric transducers(PZTs) array based wavenumber filtering technique for damage estimation has been gradually studied. Compared with the time domain and frequency domain analysis of the lamb wave signals, the wavenumber domain analysis is an effective approach to distinguish wave propagating direction and wave modes. However, the spatial resolution sampled by the PZTs is lower than that sampled by scanning laser Doppler vibrometer. As for the diameter of the PZT, it cannot be very small. In this paper, a new lamb wave spatial sampling signal optimization method based on Morlet wavelet is ***, the frequency band parameter of the Morlet mother wavelet function is calculated by the lamb wave excitation signal. Then, the sum of squared errors between the lamb wave spatial sampling signal and the Morlet wavelet function fitting waveform at each scale factor and time factor is calculated. Finally, the scale factor and time factor corresponding to the least sum of squared errors can be judged to be the best match scale factor and time factor respectively, and the Morlet wavelet function fitting waveform in that scale factor and time factor can be seen as the optimized lamb wave spatial sampling signal. The validation experiment performed on a glass fiber epoxy composite plate shows that the proposed method can improve the spatial resolution and length of the lamb wave spatial sampling signal, and the sum of squared errors of this method is no more than 0.2.

关键词： structural health monitoring lamb wave spatial sampling Morlet wavelet