In order to investigate the influence of length and compression directions upon behaviour of parallel bamboo strand lumber(PBSL)specimens,240 axial compression tests have been performed.With three similar one differen...In order to investigate the influence of length and compression directions upon behaviour of parallel bamboo strand lumber(PBSL)specimens,240 axial compression tests have been performed.With three similar one different typical failure modes,the mechanical performance for PBSL specimens under compression parallel to grain and perpendicular to grain are different as a whole.From the point of the characteristic values,the compression strength parallel to grain is 2.1 times of the compression strength perpendicular to grain.The elastic modulus for compression parallel to grain is 3.64 times of the compression strength perpendicular to grain.While the compression ratios along two compression directions are equal to each other.The bigger Poisson ratios for one typical side surface is 3.93 times of that for another typical side surface for PBSL specimens under compression perpendicular to grain,and the bigger value is equal to that for PBSL specimens under compression parallel to grain.Length can influence the mechanical properties of the PBSL specimens.The size 50 mm×50 mm×100 mm should be good choice for the standard or code to measure the compression strength.PBSL materials have better ductility under compression parallel to grain than that under compression perpendicular to grain.Stress-strain relationship models were proposed for PBSL specimens under compression parallel to grain and perpendicular to grain,respectively.These proposed models gave a good agreement with the test results.展开更多
In order to investigate the basic mechanical properties and stress strain relationship model for bamboo scrimber manufactured based on a new technique,a large quantities of experiments have been carried out.Based on t...In order to investigate the basic mechanical properties and stress strain relationship model for bamboo scrimber manufactured based on a new technique,a large quantities of experiments have been carried out.Based on the analysis of the test results,the following conclusions can be drawn.Two main typical failure modes were classified for bamboo scrimber specimens both under tension parallel to grain and tension perpendicular to grain.Brittle failure happened for all tensile tests.The slope values for the elastic stages have bigger discreteness compared with those for the specimens under tensile parallel to grain.The failure modes for bamboo scrimber specimens under compression parallel to grain could be divided into four.Only one main failure mode happened both for the bending specimens and the shear specimens.With the COV values of 28.64 and 25.72 respectively,the values for the strength and elastic modulus under tensile perpendicular to grain have the largest discreteness for bamboo scrimber.From the point of CHV values,the relationship among the mechanical parameters for bamboo scrimber were proposed based on the test results.Compared with other green building materials,bamboo scrimber manufactured based on a new technique has better mechanical performance and could be used in construction area.Three stress strain relationship models which are four-linear model,quadratic function model,and cubic function model were proposed for bamboo scrimber specimens manufactured based on a new technique.The latter two models gives better prediction for stress strain relationship in elastic plastic stage.展开更多
Sedimentary bacterial and eukaryotic communities are major components of the aquatic ecosystem.Revealing the linkages between their community structure and interactions is crucial to understand the diversity and funct...Sedimentary bacterial and eukaryotic communities are major components of the aquatic ecosystem.Revealing the linkages between their community structure and interactions is crucial to understand the diversity and functions of aquatic and soil ecosystems.However,how their diversity and assembly contribute to their interactions on time scale is unclear.This study examined sedimentary bacterial and eukaryotic communities in shrimp culture ponds at different culture stages.The most abundant bacteria were Proteobacteria(38.27%),whereas the most abundant eukaryotes were Chytridiomycota(27.48%).Bacterial and eukaryotic diversities were correlated(P<0.05),implying the strong interactions between bacteria and eukaryotes.Results showed that the bacterial and eukaryotic communities became increasingly similar on a local scale along with the shrimp culture.Only the eukaryotic community significantly increased in similarity along with the shrimp culture(P<0.05),suggesting that the sedimentary eukaryotic community structure is sensitive under shrimp culture.Co-occurrence network modeling indicated that positive microbial interactions were dominant.The homogeneous selection was the major driver of community assembly.Bacterial diversity negatively correlated with operational taxonomic units and positive links in networks(P<0.05),whereas eukaryotic diversities positively correlated with positive links in networks(P<0.05).This study broadens our knowledge about sedimentary microbial diversity,community assembly,and interaction patterns on time scale,providing a reference for the sustainable management in aquaculture production.展开更多
基金supported by the Natural Science Foundation of Jiang-su Province(No.BK20181402)the National Natural Science Foundation of China(51878354)+3 种基金National Key R&D Program of China,the Open Fund Project from Key Laboratory of Concrete and Pre-stressed Concrete Structure of Ministry of Education(Southeast university)the China Postdoctoral Science Foundation(2015M580382)Jiangsu Postdoctoral Science Foundation Project(1501037A)Qing Lan Project,and a Project Funded by the Priority Academic Program Development of Jiangsu Higher Education Institutions.
文摘In order to investigate the influence of length and compression directions upon behaviour of parallel bamboo strand lumber(PBSL)specimens,240 axial compression tests have been performed.With three similar one different typical failure modes,the mechanical performance for PBSL specimens under compression parallel to grain and perpendicular to grain are different as a whole.From the point of the characteristic values,the compression strength parallel to grain is 2.1 times of the compression strength perpendicular to grain.The elastic modulus for compression parallel to grain is 3.64 times of the compression strength perpendicular to grain.While the compression ratios along two compression directions are equal to each other.The bigger Poisson ratios for one typical side surface is 3.93 times of that for another typical side surface for PBSL specimens under compression perpendicular to grain,and the bigger value is equal to that for PBSL specimens under compression parallel to grain.Length can influence the mechanical properties of the PBSL specimens.The size 50 mm×50 mm×100 mm should be good choice for the standard or code to measure the compression strength.PBSL materials have better ductility under compression parallel to grain than that under compression perpendicular to grain.Stress-strain relationship models were proposed for PBSL specimens under compression parallel to grain and perpendicular to grain,respectively.These proposed models gave a good agreement with the test results.
基金supported by the National Natural Science Foundation of China(51878354)the Natural Science Foundation of Jiang-su Province(No.BK20181402)+1 种基金Six Peak High-level Talents Project of Jiangsu Provincea Project Funded by the Priority Academic Program Development of Jiangsu Higher Education Institutions.
文摘In order to investigate the basic mechanical properties and stress strain relationship model for bamboo scrimber manufactured based on a new technique,a large quantities of experiments have been carried out.Based on the analysis of the test results,the following conclusions can be drawn.Two main typical failure modes were classified for bamboo scrimber specimens both under tension parallel to grain and tension perpendicular to grain.Brittle failure happened for all tensile tests.The slope values for the elastic stages have bigger discreteness compared with those for the specimens under tensile parallel to grain.The failure modes for bamboo scrimber specimens under compression parallel to grain could be divided into four.Only one main failure mode happened both for the bending specimens and the shear specimens.With the COV values of 28.64 and 25.72 respectively,the values for the strength and elastic modulus under tensile perpendicular to grain have the largest discreteness for bamboo scrimber.From the point of CHV values,the relationship among the mechanical parameters for bamboo scrimber were proposed based on the test results.Compared with other green building materials,bamboo scrimber manufactured based on a new technique has better mechanical performance and could be used in construction area.Three stress strain relationship models which are four-linear model,quadratic function model,and cubic function model were proposed for bamboo scrimber specimens manufactured based on a new technique.The latter two models gives better prediction for stress strain relationship in elastic plastic stage.
基金This work was financially supported by the China Agriculture Research System(CARS-48)China-ASEAN Maritime Cooperation Fund,China-ASEAN Center for Joint Research and Promotion of Marine Aquaculture Technology+3 种基金Guangdong MEPP Fund(NO.GDOE(2019)A21)Key Research and Development Projects in Guangdong Province(2020B0202010009)Guangzhou Science Technology and Innovation Commission Project(201510010071)Guangdong Ocean and Fishery Bureau Project(20164200042090023).
文摘Sedimentary bacterial and eukaryotic communities are major components of the aquatic ecosystem.Revealing the linkages between their community structure and interactions is crucial to understand the diversity and functions of aquatic and soil ecosystems.However,how their diversity and assembly contribute to their interactions on time scale is unclear.This study examined sedimentary bacterial and eukaryotic communities in shrimp culture ponds at different culture stages.The most abundant bacteria were Proteobacteria(38.27%),whereas the most abundant eukaryotes were Chytridiomycota(27.48%).Bacterial and eukaryotic diversities were correlated(P<0.05),implying the strong interactions between bacteria and eukaryotes.Results showed that the bacterial and eukaryotic communities became increasingly similar on a local scale along with the shrimp culture.Only the eukaryotic community significantly increased in similarity along with the shrimp culture(P<0.05),suggesting that the sedimentary eukaryotic community structure is sensitive under shrimp culture.Co-occurrence network modeling indicated that positive microbial interactions were dominant.The homogeneous selection was the major driver of community assembly.Bacterial diversity negatively correlated with operational taxonomic units and positive links in networks(P<0.05),whereas eukaryotic diversities positively correlated with positive links in networks(P<0.05).This study broadens our knowledge about sedimentary microbial diversity,community assembly,and interaction patterns on time scale,providing a reference for the sustainable management in aquaculture production.