AlScN piezoelectric films prepared by AlSc alloy sputter targets are essential materials for 5G radio frequency filters.The thermophysical properties of AlSc alloy targets are closely related to their welding processe...AlScN piezoelectric films prepared by AlSc alloy sputter targets are essential materials for 5G radio frequency filters.The thermophysical properties of AlSc alloy targets are closely related to their welding processes and applications.Al-xSc alloys(x=5,10,15,20,25,at%)were prepared by vacuum induction melting,whose purity is mainly determined by the raw materials and the production process.The results reveal that as the Sc content increases from 5at%to 20at%,the volume fraction of the Al_(3)Sc phase in the alloy increases from 26.9%to 80.2%,and the average grain size of the Al_(3)Sc phase increases from 12.9μm to 67.7μm during this period.Additionally,both the coefficient of thermal expansion(CTE)and thermal conductivity(TC)of AlSc alloys exhibit a downward trend.Based on experimental data and first-principles calculations,the effective medium theory and the Turner model effectively predict the TC and CTE of Al-xSc alloys.The optimal characteristic parameter(k0)of the Turner model is determined to be 50.The model predictions align well with the experimental results.展开更多
This study investigates the effects of radiation force due to the rotational pitch motion of a wave energy device,which comprises a coaxial bottom-mounted cylindrical caisson in a two-layer fluid,along with a submerge...This study investigates the effects of radiation force due to the rotational pitch motion of a wave energy device,which comprises a coaxial bottom-mounted cylindrical caisson in a two-layer fluid,along with a submerged cylindrical buoy.The system is modeled as a two-layer fluid with infinite horizontal extent and finite depth.The radiation problem is analyzed in the context of linear water waves.The fluid domain is divided into outer and inner zones,and mathematical solutions for the pitch radiating potential are derived for the corresponding boundary valve problem in these zones using the separation of variables approach.Using the matching eigenfunction expansion method,the unknown coefficients in the analytical expression of the radiation potentials are evaluated.The resulting radiation potential is then used to compute the added mass and damping coefficients.Several numerical results for the added mass and damping coefficients are investigated for numerous parameters,particularly the effects of the cylinder radius,the draft of the submerged cylinder,and the density proportion between the two fluid layers across different frequency ranges.The major findings are presented and discussed.展开更多
This paper deals with the singular chemotaxis-Navier-Stokes system with indirect signal consumption n_(t)+u·▽v=△n-Х▽·(n/v▽u);v_(t)+u·▽v=△v-uw;w_(t)+u·▽w=△w-w+n;u_(t)+(u·▽)u=△u-▽P+...This paper deals with the singular chemotaxis-Navier-Stokes system with indirect signal consumption n_(t)+u·▽v=△n-Х▽·(n/v▽u);v_(t)+u·▽v=△v-uw;w_(t)+u·▽w=△w-w+n;u_(t)+(u·▽)u=△u-▽P+n▽Ф;▽·u=0,x∈Ω,t>0 in a bounded and smooth domainΩ⊂ℝ2 with no-flux/no-flux/no-flux/no-slip boundary conditions,whereΦ∈W2,∞(Ω).A recent literature[Dai F,Liu B.J Differential Equations,2023,369:115–155]has proved that for all reasonably regular initial data,the associated initial-boundary value problem possesses a global classical solution,but qualitative information on the behavior of solution has never been touched so far.In stark contrast to the positive effect of indirect signal consumption mechanism on the global solvability of system,the analysis of asymptotic behavior of solution to the system with indirect signal consumption is essentially complicated than that with direct signal consumption because the favorable coupled structure between cells and signal is broken down by the indirect signal consumption mechanism.The present study shows that the global classical solution exponentially stabilizes toward the corresponding spatially homogeneous equilibria under a smallness condition on the initial cell mass.In comparison to the previously known result concerning the uniform convergence of solution to the system with direct signal consumption,our result inter alia provides a more in-depth understanding on the asymptotic behavior of solution.展开更多
This study investigates the performance of dual curved-leg pontoon floating breakwaters in finite water depth under the assumption of linear wave theory. The analysis is carried out for four different models of curved...This study investigates the performance of dual curved-leg pontoon floating breakwaters in finite water depth under the assumption of linear wave theory. The analysis is carried out for four different models of curvedleg geometries, which are combinations of convex and concave shapes. The models are classified as follows. Model-1: Seaside and leeside face concave, Model-2: Seaside and leeside face convex, Model-3: Seaside face convex and leeside face concave, and Model-4: Seaside face concave and leeside face convex. The Boundary Element Method is utilized in order to find a solution to the associated boundary value problem. The numerical results are validated against existing analytical and experimental data. Further, the study examines the wave reflection, wave transmission, and the hydrodynamic forces acting on the structure for different values of waves and structural parameters. Overall, the different dual curved-leg pontoon breakwaters are more effective, reducing wave transmission by over 15% and increasing wave reflection by more than 5% compared to traditional models. The study shows that the wave reflected by Model 1 significantly increased and attenuated the wave transmission relative to other models. The study found that the height of the curved-leg of Model 1 plays a critical role in blocking waves and redirecting the flow. More precisely, the present analysis concludes that the hydrodynamic performance of Model-1 presents an optimized breakwater design that outperforms the proposed models.展开更多
This paper deals with numerical computation and analysis for the initial boundary problems of two dimensional(2D)Sobolev equations with piecewise continuous argument.Firstly,a two-level high-order compact difference m...This paper deals with numerical computation and analysis for the initial boundary problems of two dimensional(2D)Sobolev equations with piecewise continuous argument.Firstly,a two-level high-order compact difference method(HOCDM)with computational accuracy O(τ^(2)+h_(x)^(4)+h_(y)^(4))is suggested,whereτ,h_(x),h_(y) denote the temporal and spatial stepsizes of the method,respectively.In order to improve the temporal computational accuracy of this method,the Richardson extrapolation technique is used and thus a new two-level HOCDMis derived,which is proved to be convergent of order four both in time and space.Although the new two-level HOCDM has the higher computational accuracy in time than the previous one,it will bring a larger computational cost.To overcome this deficiency,a three-level HOCDM with computational accuracy O(τ^(4)+h_(x)^(4)+h_(y)^(4))is constructed.Finally,with a series of numerical experiments,the theoretical accuracy and computational efficiency of the above methods are further verified.展开更多
In this work, we first derive the one-point large deviations principle (LDP) for both the stochastic Cahn–Hilliard equation with small noise and its spatial finite difference method (FDM). Then, we focus on giving th...In this work, we first derive the one-point large deviations principle (LDP) for both the stochastic Cahn–Hilliard equation with small noise and its spatial finite difference method (FDM). Then, we focus on giving the convergence of the one-point large deviations rate function (LDRF) of the spatial FDM, which is about the asymptotical limit of a parametric variational problem. The main idea for proving the convergence of the LDRF of the spatial FDM is via the Γ-convergence of objective functions. This relies on the qualitative analysis of skeleton equations of the original equation and the numerical method. In order to overcome the difficulty that the drift coefficient is not one-sided Lipschitz continuous, we derive the equivalent characterization of the skeleton equation of the spatial FDM and the discrete interpolation inequality to obtain the uniform boundedness of the solution to the underlying skeleton equation. These play important roles in deriving the T-convergence of objective functions.展开更多
Germany aims to achieve a national climate-neutral energy system by 2045.The residential sector still accounts for 29%of end energy consumption,with 74%attributed to the direct use of fossil fuels for heating and hot ...Germany aims to achieve a national climate-neutral energy system by 2045.The residential sector still accounts for 29%of end energy consumption,with 74%attributed to the direct use of fossil fuels for heating and hot water.In order to reduce fossil energy use in the household sector,great efforts are being made to design new energy concepts that expand the use of renewable energies to supply electricity andheat.Onepossibility is toconvertparts of the natural gas grid to a hydrogen-based gas grid to deliver and store energy for urban quarters of buildings,especially with older building stock where electrification of heat via heat pumps is difficult due to technical,acoustical,and economic reasons.A comprehensive dataset was generated by a bottom-up analysis with open governmental and statistical data to determine regional building types regarding energy demand,solar potential,and existing grid infrastructure.The buildings’connections to the electricity,gas,and district heating networks are considered.From this,a representative sample dataset was chosen as input for a newly developed energy system model based on energy flow simulation.The model simulates the interaction of hydrogen generation(HG)(from excess solar energy by electrolysis),storage in a metal-hydride storage(MHS)tank,and hydrogen use in a connected fuel cell(FC),forming a local PVPtGtHP(Photovoltaic Power-to-Gas-to-Heat-and-Power)network.Next to the seasonal hydrogen storage path(HSP),a battery will complete the system to forma hybrid energy storage system(HESS).Paired with seasonal time series for PV power,electricity and heat demand,and a model for connection to grid infrastructure,the simulation of different hydrogen applications and MHS placements aims to analyze operating times and energy share of the systems’equipment and existing infrastructure.The method to obtain the data set together with the simulationmodel presented can be used by energy planners for cities,communities,and building developers to analyze the potentials of a quarter or region and plan a transition towards a more energy-efficient and sustainable energy system.展开更多
This study explores the magnetohydrodynamic(MHD)boundary layer flow of a water-based Boger nanofluid over a stretching sheet,with particular focus on the influences of nanoparticle diameter,nanolayer effects,and therm...This study explores the magnetohydrodynamic(MHD)boundary layer flow of a water-based Boger nanofluid over a stretching sheet,with particular focus on the influences of nanoparticle diameter,nanolayer effects,and thermal radiation.The primary aim is to examine how variations in nanoparticle size and nanolayer thickness affect the hydrothermal behavior of the nanofluid.The model also incorporates the contributions of viscous dissipation and Joule heating within the heat transfer equation.The governing momentum and energy equations are converted into dimensionless partial differential equations(PDEs)using appropriate similarity variables and are numerically solved using the finite element method(FEM)implemented in MATLAB.Extensive validation of this method confirms its reliability and accuracy in numerical solutions.The findings reveal that increasing the diameter of copper nanoparticles significantly enhances the velocity profile,with a more pronounced effect observed at wider inter-particle spacings.A higher solvent volume fraction leads to decreased velocity and temperature distributions,while a greater relaxation time ratio improves velocity and temperature profiles due to the increased elastic response of the fluid.Moreover,enhancements in the magnetic parameter,thermal radiation,and Eckert number lead to an elevation in temperature profiles.Furthermore,higher nanolayer thickness reduces the temperature profile,whereas particle radius yields the opposite outcome.展开更多
This study analyzes Brazilian stromatolites in Lagoa Salgada,serving as analogs for pre-salt rocks in the Santos and Campos basins.Despite their excellent petrophysical properties,such as high porosity and permeabilit...This study analyzes Brazilian stromatolites in Lagoa Salgada,serving as analogs for pre-salt rocks in the Santos and Campos basins.Despite their excellent petrophysical properties,such as high porosity and permeability,these reservoirs present challenges in fluid flow modeling and simulation.The research investigates various factors influencing the development of carbonate reservoirs,including diagenetic processes employing several techniques,such as microcomputed tomography(micro-CT)and digital rock physics(DRP),to study petrophysical and geological characteristics.Additionally,through numerical simulations,the properties of fluid flow in different microfacies of stromatolites are estimated,with particular emphasis on understanding and highlighting changes in the direction of fluid flow in the three characterized microfacies.These findings offer crucial insights into optimizing oil and gas exploration and production techniques in carbonate reservoirs,providing a comprehensive understanding of the dynamics of fluid transport in porous media,especially in terms of directional changes within stromatolites.展开更多
Chronic obstructive pulmonary disease(COPD)is a complex condition marked by considerable interindividual heterogeneity.Comorbidities exacerbate this variability,worsening disease severity and reducing health-related q...Chronic obstructive pulmonary disease(COPD)is a complex condition marked by considerable interindividual heterogeneity.Comorbidities exacerbate this variability,worsening disease severity and reducing health-related quality of life(HRQoL).Despite the high prevalence of COPD in China,COPD patient clusters remain poorly characterized.This study aimed to identify and validate clusters of Chinese patients with COPD,characterized primarily by comorbidity profiles,using cluster analysis.This cross-sectional,multicenter cohort study used data from the Chinese Enjoying Breathing Program(2020–2023).HRQoL was measured using the EuroQol five dimension(EQ-5D).Dimension reduction was performed via multiple correspondence analysis on 31 variables,including indicators of 27 comorbidities and four sociodemographic or health-related characteristics.Unsupervised machine learning algorithms,K-means++,and hierarchical clustering identified distinct clusters.Robustness was assessed using random forest classification.Logistic regression evaluated the association between cluster membership and EQ-5D outcomes.Among 11145 patients,59.4%had comorbidities.Four clusters emerged:young male smokers,biomass-exposed females,respiratory comorbidity,and elderly multimorbid.The last two clusters had notably lower HRQoL.Cluster analysis identified four clinically meaningful COPD patient clusters based on comorbidities and risk profiles,each with distinct HRQoL outcomes.These findings support targeted public health interventions and integrated care strategies for COPD management.展开更多
Boundary recovery is one of the main obstacles in applying the Delaunay criterion to mesh generation. A stan- dard resolution is to add Steiner points directly at the intersection positions between missing boundaries ...Boundary recovery is one of the main obstacles in applying the Delaunay criterion to mesh generation. A stan- dard resolution is to add Steiner points directly at the intersection positions between missing boundaries and triangulations. We redesign the algorithm with the aid of some new concepts, data structures and operations, which make its implementation routine. Furthermore, all possible intersection cases and their solutions are presented, some of which are seldom discussed in the litera- ture. Finally, numerical results are presented to evaluate the performance of the new algorithm.展开更多
In this paper, we propose a globally convergent Polak-Ribiere-Polyak (PRP) conjugate gradient method for nonconvex minimization of differentiable functions by employing an Armijo-type line search which is simpler and ...In this paper, we propose a globally convergent Polak-Ribiere-Polyak (PRP) conjugate gradient method for nonconvex minimization of differentiable functions by employing an Armijo-type line search which is simpler and less demanding than those defined in [4,10]. A favorite property of this method is that we can choose the initial stepsize as the one-dimensional minimizer of a quadratic modelΦ(t):= f(xk)+tgkTdk+(1/2) t2dkTQkdk, where Qk is a positive definite matrix that carries some second order information of the objective function f. So, this line search may make the stepsize tk more easily accepted. Preliminary numerical results show that this method is efficient.展开更多
We have yet to develop a fundamental understanding of the molecular complexities of human spermatozoa.This encompasses the unique packaging and structure of the sperm genome along with their paternally derived RNAs in...We have yet to develop a fundamental understanding of the molecular complexities of human spermatozoa.This encompasses the unique packaging and structure of the sperm genome along with their paternally derived RNAs in preparation for their delivery to the egg.The diversity of these transcripts is vast,including several anti-sense mol- ecules resembling known regulatory micro-RNAs.The field is still grasping with its delivery to the oocyte at fertiliza- tion and possible significance.It remains tempting to analogize them to maternally-derived transcripts active in early embryo patterning.Irrespective of their role in the embryo,their use as a means to assess male factor infertility is promising.展开更多
Centroidal Voronoi tessellations(CVTs) have become a useful tool in many applications ranging from geometric modeling,image and data analysis,and numerical partial differential equations,to problems in physics,astroph...Centroidal Voronoi tessellations(CVTs) have become a useful tool in many applications ranging from geometric modeling,image and data analysis,and numerical partial differential equations,to problems in physics,astrophysics,chemistry,and biology. In this paper,we briefly review the CVT concept and a few of its generalizations and well-known properties.We then present an overview of recent advances in both mathematical and computational studies and in practical applications of CVTs.Whenever possible,we point out some outstanding issues that still need investigating.展开更多
基金National Key Research and Development Program of China(2022YFB3504402,2023YFB3610101)。
文摘AlScN piezoelectric films prepared by AlSc alloy sputter targets are essential materials for 5G radio frequency filters.The thermophysical properties of AlSc alloy targets are closely related to their welding processes and applications.Al-xSc alloys(x=5,10,15,20,25,at%)were prepared by vacuum induction melting,whose purity is mainly determined by the raw materials and the production process.The results reveal that as the Sc content increases from 5at%to 20at%,the volume fraction of the Al_(3)Sc phase in the alloy increases from 26.9%to 80.2%,and the average grain size of the Al_(3)Sc phase increases from 12.9μm to 67.7μm during this period.Additionally,both the coefficient of thermal expansion(CTE)and thermal conductivity(TC)of AlSc alloys exhibit a downward trend.Based on experimental data and first-principles calculations,the effective medium theory and the Turner model effectively predict the TC and CTE of Al-xSc alloys.The optimal characteristic parameter(k0)of the Turner model is determined to be 50.The model predictions align well with the experimental results.
基金supported by MHRD as researcher C.K.Neog received the MHRD Institute GATE scholarship from Govt.of India.
文摘This study investigates the effects of radiation force due to the rotational pitch motion of a wave energy device,which comprises a coaxial bottom-mounted cylindrical caisson in a two-layer fluid,along with a submerged cylindrical buoy.The system is modeled as a two-layer fluid with infinite horizontal extent and finite depth.The radiation problem is analyzed in the context of linear water waves.The fluid domain is divided into outer and inner zones,and mathematical solutions for the pitch radiating potential are derived for the corresponding boundary valve problem in these zones using the separation of variables approach.Using the matching eigenfunction expansion method,the unknown coefficients in the analytical expression of the radiation potentials are evaluated.The resulting radiation potential is then used to compute the added mass and damping coefficients.Several numerical results for the added mass and damping coefficients are investigated for numerous parameters,particularly the effects of the cylinder radius,the draft of the submerged cylinder,and the density proportion between the two fluid layers across different frequency ranges.The major findings are presented and discussed.
文摘This paper deals with the singular chemotaxis-Navier-Stokes system with indirect signal consumption n_(t)+u·▽v=△n-Х▽·(n/v▽u);v_(t)+u·▽v=△v-uw;w_(t)+u·▽w=△w-w+n;u_(t)+(u·▽)u=△u-▽P+n▽Ф;▽·u=0,x∈Ω,t>0 in a bounded and smooth domainΩ⊂ℝ2 with no-flux/no-flux/no-flux/no-slip boundary conditions,whereΦ∈W2,∞(Ω).A recent literature[Dai F,Liu B.J Differential Equations,2023,369:115–155]has proved that for all reasonably regular initial data,the associated initial-boundary value problem possesses a global classical solution,but qualitative information on the behavior of solution has never been touched so far.In stark contrast to the positive effect of indirect signal consumption mechanism on the global solvability of system,the analysis of asymptotic behavior of solution to the system with indirect signal consumption is essentially complicated than that with direct signal consumption because the favorable coupled structure between cells and signal is broken down by the indirect signal consumption mechanism.The present study shows that the global classical solution exponentially stabilizes toward the corresponding spatially homogeneous equilibria under a smallness condition on the initial cell mass.In comparison to the previously known result concerning the uniform convergence of solution to the system with direct signal consumption,our result inter alia provides a more in-depth understanding on the asymptotic behavior of solution.
基金supported by Vellore Institute of Technology,Vellore,under a SEED grant(Sanction Order No.SG20230081)。
文摘This study investigates the performance of dual curved-leg pontoon floating breakwaters in finite water depth under the assumption of linear wave theory. The analysis is carried out for four different models of curvedleg geometries, which are combinations of convex and concave shapes. The models are classified as follows. Model-1: Seaside and leeside face concave, Model-2: Seaside and leeside face convex, Model-3: Seaside face convex and leeside face concave, and Model-4: Seaside face concave and leeside face convex. The Boundary Element Method is utilized in order to find a solution to the associated boundary value problem. The numerical results are validated against existing analytical and experimental data. Further, the study examines the wave reflection, wave transmission, and the hydrodynamic forces acting on the structure for different values of waves and structural parameters. Overall, the different dual curved-leg pontoon breakwaters are more effective, reducing wave transmission by over 15% and increasing wave reflection by more than 5% compared to traditional models. The study shows that the wave reflected by Model 1 significantly increased and attenuated the wave transmission relative to other models. The study found that the height of the curved-leg of Model 1 plays a critical role in blocking waves and redirecting the flow. More precisely, the present analysis concludes that the hydrodynamic performance of Model-1 presents an optimized breakwater design that outperforms the proposed models.
文摘This paper deals with numerical computation and analysis for the initial boundary problems of two dimensional(2D)Sobolev equations with piecewise continuous argument.Firstly,a two-level high-order compact difference method(HOCDM)with computational accuracy O(τ^(2)+h_(x)^(4)+h_(y)^(4))is suggested,whereτ,h_(x),h_(y) denote the temporal and spatial stepsizes of the method,respectively.In order to improve the temporal computational accuracy of this method,the Richardson extrapolation technique is used and thus a new two-level HOCDMis derived,which is proved to be convergent of order four both in time and space.Although the new two-level HOCDM has the higher computational accuracy in time than the previous one,it will bring a larger computational cost.To overcome this deficiency,a three-level HOCDM with computational accuracy O(τ^(4)+h_(x)^(4)+h_(y)^(4))is constructed.Finally,with a series of numerical experiments,the theoretical accuracy and computational efficiency of the above methods are further verified.
基金supported by the National Natural Science Foundation of China(12201228,12171047)the Fundamental Research Funds for the Central Universities(3034011102)supported by National Key R&D Program of China(2020YFA0713701).
文摘In this work, we first derive the one-point large deviations principle (LDP) for both the stochastic Cahn–Hilliard equation with small noise and its spatial finite difference method (FDM). Then, we focus on giving the convergence of the one-point large deviations rate function (LDRF) of the spatial FDM, which is about the asymptotical limit of a parametric variational problem. The main idea for proving the convergence of the LDRF of the spatial FDM is via the Γ-convergence of objective functions. This relies on the qualitative analysis of skeleton equations of the original equation and the numerical method. In order to overcome the difficulty that the drift coefficient is not one-sided Lipschitz continuous, we derive the equivalent characterization of the skeleton equation of the spatial FDM and the discrete interpolation inequality to obtain the uniform boundedness of the solution to the underlying skeleton equation. These play important roles in deriving the T-convergence of objective functions.
基金supported by the German Federal Ministry for Economic Affairs and Climate Action[BMWK SimBench-Sektor project,grant number 03EI1058C].
文摘Germany aims to achieve a national climate-neutral energy system by 2045.The residential sector still accounts for 29%of end energy consumption,with 74%attributed to the direct use of fossil fuels for heating and hot water.In order to reduce fossil energy use in the household sector,great efforts are being made to design new energy concepts that expand the use of renewable energies to supply electricity andheat.Onepossibility is toconvertparts of the natural gas grid to a hydrogen-based gas grid to deliver and store energy for urban quarters of buildings,especially with older building stock where electrification of heat via heat pumps is difficult due to technical,acoustical,and economic reasons.A comprehensive dataset was generated by a bottom-up analysis with open governmental and statistical data to determine regional building types regarding energy demand,solar potential,and existing grid infrastructure.The buildings’connections to the electricity,gas,and district heating networks are considered.From this,a representative sample dataset was chosen as input for a newly developed energy system model based on energy flow simulation.The model simulates the interaction of hydrogen generation(HG)(from excess solar energy by electrolysis),storage in a metal-hydride storage(MHS)tank,and hydrogen use in a connected fuel cell(FC),forming a local PVPtGtHP(Photovoltaic Power-to-Gas-to-Heat-and-Power)network.Next to the seasonal hydrogen storage path(HSP),a battery will complete the system to forma hybrid energy storage system(HESS).Paired with seasonal time series for PV power,electricity and heat demand,and a model for connection to grid infrastructure,the simulation of different hydrogen applications and MHS placements aims to analyze operating times and energy share of the systems’equipment and existing infrastructure.The method to obtain the data set together with the simulationmodel presented can be used by energy planners for cities,communities,and building developers to analyze the potentials of a quarter or region and plan a transition towards a more energy-efficient and sustainable energy system.
基金supported by the Fundamental Research Funds for the Central Universities(Grant No.D5000230061)the Guangdong Basic and Applied Basic Research Foundation(Grant No.2025A1515011192).
文摘This study explores the magnetohydrodynamic(MHD)boundary layer flow of a water-based Boger nanofluid over a stretching sheet,with particular focus on the influences of nanoparticle diameter,nanolayer effects,and thermal radiation.The primary aim is to examine how variations in nanoparticle size and nanolayer thickness affect the hydrothermal behavior of the nanofluid.The model also incorporates the contributions of viscous dissipation and Joule heating within the heat transfer equation.The governing momentum and energy equations are converted into dimensionless partial differential equations(PDEs)using appropriate similarity variables and are numerically solved using the finite element method(FEM)implemented in MATLAB.Extensive validation of this method confirms its reliability and accuracy in numerical solutions.The findings reveal that increasing the diameter of copper nanoparticles significantly enhances the velocity profile,with a more pronounced effect observed at wider inter-particle spacings.A higher solvent volume fraction leads to decreased velocity and temperature distributions,while a greater relaxation time ratio improves velocity and temperature profiles due to the increased elastic response of the fluid.Moreover,enhancements in the magnetic parameter,thermal radiation,and Eckert number lead to an elevation in temperature profiles.Furthermore,higher nanolayer thickness reduces the temperature profile,whereas particle radius yields the opposite outcome.
基金the Coordenacao de Aperfeicoamento de Pessoal de Nivel Superior of the Ministry of Education(CAPES/MEC/BRAZIL)-Finance Code 001,Equinor Energy of Brazil Company(Project No.4600025270)the Brazilian National Agency of Petroleum,Gas,and Biofuels(ANP),and Petrobras(Project No.46000579151)+1 种基金INCT/Petroleum Geophysics for financial supportthe National Council for Scientific and Technological Development (CNPq) for their Research Grants of Productivity in Technological Development and Innovation-DT II (313522/2019-7 and 313746/ 2019-2)
文摘This study analyzes Brazilian stromatolites in Lagoa Salgada,serving as analogs for pre-salt rocks in the Santos and Campos basins.Despite their excellent petrophysical properties,such as high porosity and permeability,these reservoirs present challenges in fluid flow modeling and simulation.The research investigates various factors influencing the development of carbonate reservoirs,including diagenetic processes employing several techniques,such as microcomputed tomography(micro-CT)and digital rock physics(DRP),to study petrophysical and geological characteristics.Additionally,through numerical simulations,the properties of fluid flow in different microfacies of stromatolites are estimated,with particular emphasis on understanding and highlighting changes in the direction of fluid flow in the three characterized microfacies.These findings offer crucial insights into optimizing oil and gas exploration and production techniques in carbonate reservoirs,providing a comprehensive understanding of the dynamics of fluid transport in porous media,especially in terms of directional changes within stromatolites.
基金supported by the Ministry of Science and Tech-nology of the People’s Republic of China(2023ZD0506000)the CAMS Innovation Fund for Medical Sciences(ClFMS,2023-I2M-2-001)the Non-profit Central Research Institute Fund of Chinese Academy of Medical Sciences(2022-ZHCH330-01).The statements made and views expressed are solely the responsibility of the authors.
文摘Chronic obstructive pulmonary disease(COPD)is a complex condition marked by considerable interindividual heterogeneity.Comorbidities exacerbate this variability,worsening disease severity and reducing health-related quality of life(HRQoL).Despite the high prevalence of COPD in China,COPD patient clusters remain poorly characterized.This study aimed to identify and validate clusters of Chinese patients with COPD,characterized primarily by comorbidity profiles,using cluster analysis.This cross-sectional,multicenter cohort study used data from the Chinese Enjoying Breathing Program(2020–2023).HRQoL was measured using the EuroQol five dimension(EQ-5D).Dimension reduction was performed via multiple correspondence analysis on 31 variables,including indicators of 27 comorbidities and four sociodemographic or health-related characteristics.Unsupervised machine learning algorithms,K-means++,and hierarchical clustering identified distinct clusters.Robustness was assessed using random forest classification.Logistic regression evaluated the association between cluster membership and EQ-5D outcomes.Among 11145 patients,59.4%had comorbidities.Four clusters emerged:young male smokers,biomass-exposed females,respiratory comorbidity,and elderly multimorbid.The last two clusters had notably lower HRQoL.Cluster analysis identified four clinically meaningful COPD patient clusters based on comorbidities and risk profiles,each with distinct HRQoL outcomes.These findings support targeted public health interventions and integrated care strategies for COPD management.
基金Project (No. 60225009) supported by the National Natural ScienceFoundation of China through the National Science Fund for Distin-guished Young Scholars
文摘Boundary recovery is one of the main obstacles in applying the Delaunay criterion to mesh generation. A stan- dard resolution is to add Steiner points directly at the intersection positions between missing boundaries and triangulations. We redesign the algorithm with the aid of some new concepts, data structures and operations, which make its implementation routine. Furthermore, all possible intersection cases and their solutions are presented, some of which are seldom discussed in the litera- ture. Finally, numerical results are presented to evaluate the performance of the new algorithm.
基金This work is supported by the Chinese NSF grants 60475042 Guangxi NSF grants 0542043the Foundation of Advanced Research Center of Zhongshan University and Hong Kong
文摘In this paper, we propose a globally convergent Polak-Ribiere-Polyak (PRP) conjugate gradient method for nonconvex minimization of differentiable functions by employing an Armijo-type line search which is simpler and less demanding than those defined in [4,10]. A favorite property of this method is that we can choose the initial stepsize as the one-dimensional minimizer of a quadratic modelΦ(t):= f(xk)+tgkTdk+(1/2) t2dkTQkdk, where Qk is a positive definite matrix that carries some second order information of the objective function f. So, this line search may make the stepsize tk more easily accepted. Preliminary numerical results show that this method is efficient.
文摘We have yet to develop a fundamental understanding of the molecular complexities of human spermatozoa.This encompasses the unique packaging and structure of the sperm genome along with their paternally derived RNAs in preparation for their delivery to the egg.The diversity of these transcripts is vast,including several anti-sense mol- ecules resembling known regulatory micro-RNAs.The field is still grasping with its delivery to the oocyte at fertiliza- tion and possible significance.It remains tempting to analogize them to maternally-derived transcripts active in early embryo patterning.Irrespective of their role in the embryo,their use as a means to assess male factor infertility is promising.
基金supported by the US Department of Energy Office of Science Climate Change Prediction Program through grant numbers DE-FG02-07ER64431 and DE-FG02-07ER64432the US National Science Foundation under grant numbers DMS-0609575 and DMS-0913491
文摘Centroidal Voronoi tessellations(CVTs) have become a useful tool in many applications ranging from geometric modeling,image and data analysis,and numerical partial differential equations,to problems in physics,astrophysics,chemistry,and biology. In this paper,we briefly review the CVT concept and a few of its generalizations and well-known properties.We then present an overview of recent advances in both mathematical and computational studies and in practical applications of CVTs.Whenever possible,we point out some outstanding issues that still need investigating.
