Background:Grasslands provide a wide range of ecosystem services(ESs).However,there is currently no method for easily diagnosing the level of ESs produced.Our aim was to develop ES indicators based on botanical survey...Background:Grasslands provide a wide range of ecosystem services(ESs).However,there is currently no method for easily diagnosing the level of ESs produced.Our aim was to develop ES indicators based on botanical surveys,which are readily available data and integrative of grassland spatiotemporal variability.Methods:Based on academic knowledge and expertise,we identified several simple vegetation criteria that we aggregated using a multicriteria analysis tool to construct indicators of the level of ESs provided by grasslands.In this study,the indicators were calculated from over 2000 botanical surveys spread over a wide biogeographical gradient.Results:Analyses of correlation between the various indicators show that“forage supply”and“diversity conservation”were not correlated.“Forage availability”and“nitrogen availability for the vegetation”were positively linked together and negatively linked to the robustness of the plant community to extreme events.A temporal approach highlights that the“biodiversity conservation”score decreased from 1970 to 2010 and that“nitrogen availability for the vegetation”was lower in 1970 and 1980 than in 2000 and 2010.Conclusions:These results show that our aggregation method based on a large data set of botanical surveys could be appropriate for studying temporal dynamics of ESs.展开更多
The study of vesicles,capsules and red blood cells(RBCs)under flow is a field of active research,belonging to the general problematic of fluid/structure interactions.Here,we are interested in modeling vesicles,capsule...The study of vesicles,capsules and red blood cells(RBCs)under flow is a field of active research,belonging to the general problematic of fluid/structure interactions.Here,we are interested in modeling vesicles,capsules and RBCs using a boundary integral formulation,and focus on exact singularity subtractions of the kernel of the integral equations in 3D.In order to increase the precision of singular and near-singular integration,we propose here a refinement procedure in the vicinity of the pole of the Green-Oseen kernel.The refinement is performed homogeneously everywhere on the source surface in order to reuse the additional quadrature nodes when calculating boundary integrals in multiple target points.We also introduce a multi-level look-up algorithm in order to select the additional quadrature nodes in vicinity of the pole of the Green-Oseen kernel.The expected convergence rate of the proposed algorithm is of order δ(1/N^(2))while the computational complexity is of order δ(N^(2) lnN),where N is the number of degrees of freedom used for surface discretization.Several numerical tests are presented to demonstrate the convergence and the efficiency of the method.展开更多
文摘Background:Grasslands provide a wide range of ecosystem services(ESs).However,there is currently no method for easily diagnosing the level of ESs produced.Our aim was to develop ES indicators based on botanical surveys,which are readily available data and integrative of grassland spatiotemporal variability.Methods:Based on academic knowledge and expertise,we identified several simple vegetation criteria that we aggregated using a multicriteria analysis tool to construct indicators of the level of ESs provided by grasslands.In this study,the indicators were calculated from over 2000 botanical surveys spread over a wide biogeographical gradient.Results:Analyses of correlation between the various indicators show that“forage supply”and“diversity conservation”were not correlated.“Forage availability”and“nitrogen availability for the vegetation”were positively linked together and negatively linked to the robustness of the plant community to extreme events.A temporal approach highlights that the“biodiversity conservation”score decreased from 1970 to 2010 and that“nitrogen availability for the vegetation”was lower in 1970 and 1980 than in 2000 and 2010.Conclusions:These results show that our aggregation method based on a large data set of botanical surveys could be appropriate for studying temporal dynamics of ESs.
文摘The study of vesicles,capsules and red blood cells(RBCs)under flow is a field of active research,belonging to the general problematic of fluid/structure interactions.Here,we are interested in modeling vesicles,capsules and RBCs using a boundary integral formulation,and focus on exact singularity subtractions of the kernel of the integral equations in 3D.In order to increase the precision of singular and near-singular integration,we propose here a refinement procedure in the vicinity of the pole of the Green-Oseen kernel.The refinement is performed homogeneously everywhere on the source surface in order to reuse the additional quadrature nodes when calculating boundary integrals in multiple target points.We also introduce a multi-level look-up algorithm in order to select the additional quadrature nodes in vicinity of the pole of the Green-Oseen kernel.The expected convergence rate of the proposed algorithm is of order δ(1/N^(2))while the computational complexity is of order δ(N^(2) lnN),where N is the number of degrees of freedom used for surface discretization.Several numerical tests are presented to demonstrate the convergence and the efficiency of the method.
