Lamb波具有较强的抗干扰能力,被广泛应用于碳纤维增强树脂(Carbon Fiber Reinforced Polymer,CFRP)结构健康监测中。采用汉宁窗形式的窄带Lamb波激励完整CFRP板与含内置损伤的损伤CFRP板,通过比较PZT压电片采集到的健康信号与损伤信号...Lamb波具有较强的抗干扰能力,被广泛应用于碳纤维增强树脂(Carbon Fiber Reinforced Polymer,CFRP)结构健康监测中。采用汉宁窗形式的窄带Lamb波激励完整CFRP板与含内置损伤的损伤CFRP板,通过比较PZT压电片采集到的健康信号与损伤信号之间的信号差异系数,根据改进的损伤概率重建算法(Reconstruction Algorithm for the Probabilistic Inspection of Damage,RAPID)实现CFRP结构的内部损伤成像。得到以下结论:建立CFRP板Lamb波有限元模型对内置损伤的大小和区域进行定位,并根据CFRP板Lamb波结构健康监测试验平台验证有限元模型的正确性;提出一种阈值化改进RAPID算法,对损伤板的内置损伤大小和轮廓进行准确预测,预测结果最大误差仅为6.56%;随着结构内置损伤孔厚度的增加,结构损伤信号与健康信号的差异越发明显,预测损伤参数与实际损伤参数的最小误差仅为5.20 mm。展开更多
In this paper,we theoretically study the Lamb wave in a multilayered piezoelectric semiconductor(PSC)plate,where each layer is an n-type PSC with the symmetry of transverse isotropy.Based on the extended Stroh formali...In this paper,we theoretically study the Lamb wave in a multilayered piezoelectric semiconductor(PSC)plate,where each layer is an n-type PSC with the symmetry of transverse isotropy.Based on the extended Stroh formalism and dual-variable and position(DVP)method,the general solution of the coupled fields for the Lamb wave is derived,and then the dispersion equation is obtained by the application of the boundary conditions.First,the influence of semiconducting properties on the dispersion behavior of the Lamb wave in a single-layer PSC plate is analyzed.Then,the propagation characteristics of the Lamb wave in a sandwich plate are investigated in detail.The numerical results show that the wave speed and attenuation depend on the stacking sequence,layer thickness,and initial carrier density,the Lamb wave can propagate without a cut-off frequency in both the homogeneous and multilayer PSC plates due to the semiconducting properties,and the Lamb wave without attenuation can be achieved by carefully selecting the semiconductor property in the upper and lower layers.These new features could be very helpful as theoretical guidance for the design and performance optimization of PSC devices.展开更多
Background Dietary protein level and amino acid(AA)balance are crucial determinants of animal health and productivity.Supplementing rumen-protected AAs in low-protein diets was considered as an efficient strategy to i...Background Dietary protein level and amino acid(AA)balance are crucial determinants of animal health and productivity.Supplementing rumen-protected AAs in low-protein diets was considered as an efficient strategy to improve the growth performance of ruminants.The colon serves as a crucial conduit for nutrient metabolism during rumen-protected methionine(RPMet)and rumen-protected lysine(RPLys)supplementation,however,it has been challenging to clarify which specific microbiota and their metabolites play a pivotal role in this process.Here,we applied metagenomic and metabolomic approaches to compare the characteristic microbiome and metabolic strategies in the colon of lambs fed a control diet(CON),a low-protein diet(LP)or a LP diet supplemented with RPMet and RPLys(LR).Results The LP treatment decreased the average daily weight gain(ADG)in lambs,while the LR treatment tended to elicit a remission in ADG.The butyrate molar concentration was greater(P<0.05),while acetate molar concentration(P<0.05)was lower for lambs fed the LP and LR diets compared to those fed the CON diet.Moreover,the LP treatment remarkably decreased total AA concentration(P<0.05),while LR treatment showed an improvement in the concentrations of methionine,lysine,leucine,glutamate,and tryptophan.Metagenomic insights proved that the microbial metabolic potentials referring to biosynthesis of volatile fatty acids(VFAs)and AAs in the colon were remarkably altered by three dietary treatments.Metagenomic binning identified distinct microbial markers for the CON group(Alistipes spp.,Phocaeicola spp.,and Ruminococcus spp.),LP group(Fibrobacter spp.,Prevotella spp.,Ruminococcus spp.,and Escherichia coli),and LR group(Akkermansia muciniphila and RUG099 spp.).Conclusions Our findings suggest that RPMet and RPLys supplementation to the low-protein diet could enhance the microbial biosynthesis of butyrate and amino acids,enriche the beneficial bacteria in the colon,and thereby improve the growth performance of lambs.展开更多
文摘Lamb波具有较强的抗干扰能力,被广泛应用于碳纤维增强树脂(Carbon Fiber Reinforced Polymer,CFRP)结构健康监测中。采用汉宁窗形式的窄带Lamb波激励完整CFRP板与含内置损伤的损伤CFRP板,通过比较PZT压电片采集到的健康信号与损伤信号之间的信号差异系数,根据改进的损伤概率重建算法(Reconstruction Algorithm for the Probabilistic Inspection of Damage,RAPID)实现CFRP结构的内部损伤成像。得到以下结论:建立CFRP板Lamb波有限元模型对内置损伤的大小和区域进行定位,并根据CFRP板Lamb波结构健康监测试验平台验证有限元模型的正确性;提出一种阈值化改进RAPID算法,对损伤板的内置损伤大小和轮廓进行准确预测,预测结果最大误差仅为6.56%;随着结构内置损伤孔厚度的增加,结构损伤信号与健康信号的差异越发明显,预测损伤参数与实际损伤参数的最小误差仅为5.20 mm。
基金Project supported by the National Natural Science Foundation of China(Nos.U21A20430 and 12302202)the Hebei Natural Science Foundation of China(No.A2023210040)+1 种基金the Science and Technology Project of Hebei Education Department of China(No.BJ2025005)the Hebei Provincial Department of Human Resources and Social Security of China(No.C20220324)。
文摘In this paper,we theoretically study the Lamb wave in a multilayered piezoelectric semiconductor(PSC)plate,where each layer is an n-type PSC with the symmetry of transverse isotropy.Based on the extended Stroh formalism and dual-variable and position(DVP)method,the general solution of the coupled fields for the Lamb wave is derived,and then the dispersion equation is obtained by the application of the boundary conditions.First,the influence of semiconducting properties on the dispersion behavior of the Lamb wave in a single-layer PSC plate is analyzed.Then,the propagation characteristics of the Lamb wave in a sandwich plate are investigated in detail.The numerical results show that the wave speed and attenuation depend on the stacking sequence,layer thickness,and initial carrier density,the Lamb wave can propagate without a cut-off frequency in both the homogeneous and multilayer PSC plates due to the semiconducting properties,and the Lamb wave without attenuation can be achieved by carefully selecting the semiconductor property in the upper and lower layers.These new features could be very helpful as theoretical guidance for the design and performance optimization of PSC devices.
基金jointly supported by the International Partnership Program of Chinese Academy of Sciences(161343KYSB20200015)Guangxi Provincial Natural Science Foundation of China(2023GXNSFAA026107)+1 种基金the Science and Technology Innovation Program of Hunan Province(2022RC1158)Youth Innovation Promotion Association CAS(2023382)。
文摘Background Dietary protein level and amino acid(AA)balance are crucial determinants of animal health and productivity.Supplementing rumen-protected AAs in low-protein diets was considered as an efficient strategy to improve the growth performance of ruminants.The colon serves as a crucial conduit for nutrient metabolism during rumen-protected methionine(RPMet)and rumen-protected lysine(RPLys)supplementation,however,it has been challenging to clarify which specific microbiota and their metabolites play a pivotal role in this process.Here,we applied metagenomic and metabolomic approaches to compare the characteristic microbiome and metabolic strategies in the colon of lambs fed a control diet(CON),a low-protein diet(LP)or a LP diet supplemented with RPMet and RPLys(LR).Results The LP treatment decreased the average daily weight gain(ADG)in lambs,while the LR treatment tended to elicit a remission in ADG.The butyrate molar concentration was greater(P<0.05),while acetate molar concentration(P<0.05)was lower for lambs fed the LP and LR diets compared to those fed the CON diet.Moreover,the LP treatment remarkably decreased total AA concentration(P<0.05),while LR treatment showed an improvement in the concentrations of methionine,lysine,leucine,glutamate,and tryptophan.Metagenomic insights proved that the microbial metabolic potentials referring to biosynthesis of volatile fatty acids(VFAs)and AAs in the colon were remarkably altered by three dietary treatments.Metagenomic binning identified distinct microbial markers for the CON group(Alistipes spp.,Phocaeicola spp.,and Ruminococcus spp.),LP group(Fibrobacter spp.,Prevotella spp.,Ruminococcus spp.,and Escherichia coli),and LR group(Akkermansia muciniphila and RUG099 spp.).Conclusions Our findings suggest that RPMet and RPLys supplementation to the low-protein diet could enhance the microbial biosynthesis of butyrate and amino acids,enriche the beneficial bacteria in the colon,and thereby improve the growth performance of lambs.
