本文旨在研究内蒙古牧区冬春季低质粗料供给条件下,补饲不同能氮比精料对羔羊生长性能及血清指标的影响。采取单因子试验设计选取(61±2)日龄健康、体重为(20.56±1.43)kg断奶的羔羊128只,公母各占1/2,分成4组,每组32个重复,每...本文旨在研究内蒙古牧区冬春季低质粗料供给条件下,补饲不同能氮比精料对羔羊生长性能及血清指标的影响。采取单因子试验设计选取(61±2)日龄健康、体重为(20.56±1.43)kg断奶的羔羊128只,公母各占1/2,分成4组,每组32个重复,每个重复1只羊,分别补饲消化能(DE)水平相近、粗蛋白质(CP)水平逐渐升高的4种颗粒精料,其能氮比(采用DE/CP)分别为90.03(Ⅰ组)、82.55(Ⅱ组)、73.25(Ⅲ组)、67.87 M J/kg(Ⅳ组)。试验期40 d。结果表明:1)Ⅲ组平均日增重分别高于Ⅳ组7.75%(P<0.01)、Ⅰ组4.94%(P<0.05)和Ⅱ组3.41%(P>0.05),且该组料重比最优。2)Ⅰ组羔羊末体高极显著低于其他组(P<0.01),其中Ⅱ、Ⅲ、Ⅳ组母羔末体高分别比Ⅰ组高3.68%、4.12%、4.44%(P<0.05);不同能氮比精料对不同性别羔羊的胸围增长、胸围增长率无显著影响(P>0.05)。3)血清尿素氮含量随着精料蛋白质水平增加而升高,Ⅳ组极显著高于Ⅰ、Ⅱ组(P<0.01);Ⅲ组羔羊血清中白细胞介素-6含量显著高于Ⅱ、Ⅳ组(P<0.05),免疫球蛋白M含量显著高于其他各组(P<0.05)。结果提示,牧区冬春季枯草期对羔羊及时补饲精料能够取得较好的生长效果,不同能氮比精料对牧区羔羊部分血清指标产生显著影响,补饲精料最适能氮比为73.25 MJ/kg。展开更多
We propose a nonlinear ultrasonic technique by using the mixed-frequency signals excited Lamb waves to conduct micro-crack detection in thin plate structures.Simulation models of three-dimensional(3D)aluminum plates a...We propose a nonlinear ultrasonic technique by using the mixed-frequency signals excited Lamb waves to conduct micro-crack detection in thin plate structures.Simulation models of three-dimensional(3D)aluminum plates and composite laminates are established by ABAQUS software,where the aluminum plate contains buried crack and composite laminates comprises cohesive element whose thickness is zero to simulate delamination damage.The interactions between the S0 mode Lamb wave and the buried micro-cracks of various dimensions are simulated by using the finite element method.Fourier frequency spectrum analysis is applied to the received time domain signal and fundamental frequency amplitudes,and sum and difference frequencies are extracted and simulated.Simulation results indicate that nonlinear Lamb waves have different sensitivities to various crack sizes.There is a positive correlation among crack length,height,and sum and difference frequency amplitudes for an aluminum plate,with both amplitudes decreasing as crack thickness increased,i.e.,nonlinear effect weakens as the micro-crack becomes thicker.The amplitudes of sum and difference frequency are positively correlated with the length and width of the zero-thickness cohesive element in the composite laminates.Furthermore,amplitude ratio change is investigated and it can be used as an effective tool to detect inner defects in thin 3D plates.展开更多
文摘本文旨在研究内蒙古牧区冬春季低质粗料供给条件下,补饲不同能氮比精料对羔羊生长性能及血清指标的影响。采取单因子试验设计选取(61±2)日龄健康、体重为(20.56±1.43)kg断奶的羔羊128只,公母各占1/2,分成4组,每组32个重复,每个重复1只羊,分别补饲消化能(DE)水平相近、粗蛋白质(CP)水平逐渐升高的4种颗粒精料,其能氮比(采用DE/CP)分别为90.03(Ⅰ组)、82.55(Ⅱ组)、73.25(Ⅲ组)、67.87 M J/kg(Ⅳ组)。试验期40 d。结果表明:1)Ⅲ组平均日增重分别高于Ⅳ组7.75%(P<0.01)、Ⅰ组4.94%(P<0.05)和Ⅱ组3.41%(P>0.05),且该组料重比最优。2)Ⅰ组羔羊末体高极显著低于其他组(P<0.01),其中Ⅱ、Ⅲ、Ⅳ组母羔末体高分别比Ⅰ组高3.68%、4.12%、4.44%(P<0.05);不同能氮比精料对不同性别羔羊的胸围增长、胸围增长率无显著影响(P>0.05)。3)血清尿素氮含量随着精料蛋白质水平增加而升高,Ⅳ组极显著高于Ⅰ、Ⅱ组(P<0.01);Ⅲ组羔羊血清中白细胞介素-6含量显著高于Ⅱ、Ⅳ组(P<0.05),免疫球蛋白M含量显著高于其他各组(P<0.05)。结果提示,牧区冬春季枯草期对羔羊及时补饲精料能够取得较好的生长效果,不同能氮比精料对牧区羔羊部分血清指标产生显著影响,补饲精料最适能氮比为73.25 MJ/kg。
基金Project supported by the National Natural Science Foundation of China(Grant Nos.61571222,61602235,and 11474160)the Six Talent Peaks Project of Jiangsu Province,China
文摘We propose a nonlinear ultrasonic technique by using the mixed-frequency signals excited Lamb waves to conduct micro-crack detection in thin plate structures.Simulation models of three-dimensional(3D)aluminum plates and composite laminates are established by ABAQUS software,where the aluminum plate contains buried crack and composite laminates comprises cohesive element whose thickness is zero to simulate delamination damage.The interactions between the S0 mode Lamb wave and the buried micro-cracks of various dimensions are simulated by using the finite element method.Fourier frequency spectrum analysis is applied to the received time domain signal and fundamental frequency amplitudes,and sum and difference frequencies are extracted and simulated.Simulation results indicate that nonlinear Lamb waves have different sensitivities to various crack sizes.There is a positive correlation among crack length,height,and sum and difference frequency amplitudes for an aluminum plate,with both amplitudes decreasing as crack thickness increased,i.e.,nonlinear effect weakens as the micro-crack becomes thicker.The amplitudes of sum and difference frequency are positively correlated with the length and width of the zero-thickness cohesive element in the composite laminates.Furthermore,amplitude ratio change is investigated and it can be used as an effective tool to detect inner defects in thin 3D plates.
