Monte Carlo(MC) simulations have been performed to refine the estimation of the correction-toscaling exponent ω in the 2D φ^(4)model,which belongs to one of the most fundamental universality classes.If corrections h...Monte Carlo(MC) simulations have been performed to refine the estimation of the correction-toscaling exponent ω in the 2D φ^(4)model,which belongs to one of the most fundamental universality classes.If corrections have the form ∝ L^(-ω),then we find ω=1.546(30) andω=1.509(14) as the best estimates.These are obtained from the finite-size scaling of the susceptibility data in the range of linear lattice sizes L ∈[128,2048] at the critical value of the Binder cumulant and from the scaling of the corresponding pseudocritical couplings within L∈[64,2048].These values agree with several other MC estimates at the assumption of the power-law corrections and are comparable with the known results of the ε-expansion.In addition,we have tested the consistency with the scaling corrections of the form ∝ L^(-4/3),∝L^(-4/3)In L and ∝L^(-4/3)/ln L,which might be expected from some considerations of the renormalization group and Coulomb gas model.The latter option is consistent with our MC data.Our MC results served as a basis for a critical reconsideration of some earlier theoretical conjectures and scaling assumptions.In particular,we have corrected and refined our previous analysis by grouping Feynman diagrams.The renewed analysis gives ω≈4-d-2η as some approximation for spatial dimensions d <4,or ω≈1.5 in two dimensions.展开更多
The authors introduce a new Large Eddy Simulation model in a channel, based on the projection on finite element spaces as filtering operation in its variationM form, for a given triangulation （Th）h〉0. The eddy visc...The authors introduce a new Large Eddy Simulation model in a channel, based on the projection on finite element spaces as filtering operation in its variationM form, for a given triangulation （Th）h〉0. The eddy viscosity is expressed in terms of the friction velocity in the boundary layer due to the wall, and is of a standard sub grid-model form outside the boundary layer. The mixing length scale is locally equal to the grid size. The computational domain is the channel without the linear sub-layer of the boundary layer. The no-slip boundary condition （or BC for short） is replaced by a Navier （BC） at the computational wall. Considering the steady state case, the authors show that the variational finite element model they have introduced, has a solution （Vh,Ph）h〉O that converges to a solution of the steady state Navier-Stokes equation with Navier BC.展开更多
In this work,we present and discuss some modifications,in the form of two-sided estimation(and also for arbitrary source functions instead of usual sign-conditions),of continuous and discrete maximum principles for th...In this work,we present and discuss some modifications,in the form of two-sided estimation(and also for arbitrary source functions instead of usual sign-conditions),of continuous and discrete maximum principles for the reactiondiffusion problems solved by the finite element and finite difference methods.展开更多
Vaccines have measurable efficacy obtained first from vaccine trials.However,vaccine efficacy(VE)is not a static measure and long-term population studies are needed to evaluate its performance and impact.COVID-19 vacc...Vaccines have measurable efficacy obtained first from vaccine trials.However,vaccine efficacy(VE)is not a static measure and long-term population studies are needed to evaluate its performance and impact.COVID-19 vaccines have been developed in record time and the currently licensed vaccines are extremely effective against severe disease with higher VE after the full immunization schedule.To assess the impact of the initial phase of the COVID-19 vaccination rollout programmes,we used an extended Susceptible-Hospitalized-Asymptomatic/mild-Recovered(SHAR)model.Vaccination models were proposed to evaluate different vaccine types:vaccine type 1 which protects against severe disease only but fails to block disease transmission,and vaccine type 2 which protects against both severe disease and infection.VE was assumed as reported by the vaccine trials incorporating the difference in efficacy between one and two doses of vaccine administration.We described the performance of the vaccine in reducing hospitalizations during a momentary scenario in the Basque Country,Spain.With a population in a mixed vaccination setting,our results have shown that reductions in hospitalized COVID-19 cases were observed five months after the vaccination rollout started,from May to June 2021.Specifically in June,a good agreement between modelling simulation and empirical data was well pronounced.展开更多
文摘Monte Carlo(MC) simulations have been performed to refine the estimation of the correction-toscaling exponent ω in the 2D φ^(4)model,which belongs to one of the most fundamental universality classes.If corrections have the form ∝ L^(-ω),then we find ω=1.546(30) andω=1.509(14) as the best estimates.These are obtained from the finite-size scaling of the susceptibility data in the range of linear lattice sizes L ∈[128,2048] at the critical value of the Binder cumulant and from the scaling of the corresponding pseudocritical couplings within L∈[64,2048].These values agree with several other MC estimates at the assumption of the power-law corrections and are comparable with the known results of the ε-expansion.In addition,we have tested the consistency with the scaling corrections of the form ∝ L^(-4/3),∝L^(-4/3)In L and ∝L^(-4/3)/ln L,which might be expected from some considerations of the renormalization group and Coulomb gas model.The latter option is consistent with our MC data.Our MC results served as a basis for a critical reconsideration of some earlier theoretical conjectures and scaling assumptions.In particular,we have corrected and refined our previous analysis by grouping Feynman diagrams.The renewed analysis gives ω≈4-d-2η as some approximation for spatial dimensions d <4,or ω≈1.5 in two dimensions.
基金Project supported by the Spanish Government and European Union FEDER Grant(No.MTM200907719)
文摘The authors introduce a new Large Eddy Simulation model in a channel, based on the projection on finite element spaces as filtering operation in its variationM form, for a given triangulation （Th）h〉0. The eddy viscosity is expressed in terms of the friction velocity in the boundary layer due to the wall, and is of a standard sub grid-model form outside the boundary layer. The mixing length scale is locally equal to the grid size. The computational domain is the channel without the linear sub-layer of the boundary layer. The no-slip boundary condition （or BC for short） is replaced by a Navier （BC） at the computational wall. Considering the steady state case, the authors show that the variational finite element model they have introduced, has a solution （Vh,Ph）h〉O that converges to a solution of the steady state Navier-Stokes equation with Navier BC.
基金The first author was supported by Hungarian National Research Fund OTKA No.K67819the second author was partially supported by Hungarian National Research Fund OTKA No.K67819the first and the third authors were supported by Jedlik project “ReCoMend”2008-2011。
文摘In this work,we present and discuss some modifications,in the form of two-sided estimation(and also for arbitrary source functions instead of usual sign-conditions),of continuous and discrete maximum principles for the reactiondiffusion problems solved by the finite element and finite difference methods.
基金funding from the European Union's Horizon 2020 research and innovation programme under the Marie Skłodowska-Curie grant agreement No 792494supported by the Basque Government through the(BMTF)“Mathematical Modeling Applied to Health”Project,BERC 2022e2025 program+1 种基金the Spanish Ministry of Sciences,Innovation and Universities:BCAM Severo Ochoa accreditation CEX2021-001142-S/MICIN/AEI/10.13039/501100011033the(BIOEF)Fundacion Vasca de Innovacion e Investigacion Sanitaria through the EITB Marathon 2021 call,project reference BIO21/COV/001.
文摘Vaccines have measurable efficacy obtained first from vaccine trials.However,vaccine efficacy(VE)is not a static measure and long-term population studies are needed to evaluate its performance and impact.COVID-19 vaccines have been developed in record time and the currently licensed vaccines are extremely effective against severe disease with higher VE after the full immunization schedule.To assess the impact of the initial phase of the COVID-19 vaccination rollout programmes,we used an extended Susceptible-Hospitalized-Asymptomatic/mild-Recovered(SHAR)model.Vaccination models were proposed to evaluate different vaccine types:vaccine type 1 which protects against severe disease only but fails to block disease transmission,and vaccine type 2 which protects against both severe disease and infection.VE was assumed as reported by the vaccine trials incorporating the difference in efficacy between one and two doses of vaccine administration.We described the performance of the vaccine in reducing hospitalizations during a momentary scenario in the Basque Country,Spain.With a population in a mixed vaccination setting,our results have shown that reductions in hospitalized COVID-19 cases were observed five months after the vaccination rollout started,from May to June 2021.Specifically in June,a good agreement between modelling simulation and empirical data was well pronounced.
