Existing buildings can be at a greater seismic risk due to non-conformance to current design codes and may require structural retrofitting to improve building performance.The performance of buildings is measured in te...Existing buildings can be at a greater seismic risk due to non-conformance to current design codes and may require structural retrofitting to improve building performance.The performance of buildings is measured in terms of immediate consequences due to direct damage,but the continuing impacts related to recovery are not considered in seismic retrofit assessment.This paper introduces a framework of retrofit selection based on the seismic resilience of deficient buildings retrofitted with the conventional mitigation approaches.The assembly-based methodology is considered for the seismic resilience assessment by compiling a nonlinear numerical model and a building performance model.The collapse fragility is developed from the capacity curve,and the resulting social,economic,and environmental consequences are determined.The seismic resilience of a building is assessed by developing a downtime assessment methodology incorporating sequence of repairs,impeding factors,and utility availability.Five functionality states are developed for the building functionality given investigated time interval,and a functionality curve for each retrofit is determined.It is concluded that seismic resilience can be used as a performance indicator to assess the continuing impacts of a hazard for the retrofit selection.展开更多
A method which is especially suitable for microcomputer calculation of the true orientation distribution function (ODF) according to the maximum-entropy estimate is proposed for hexagonal system polycrystalline materi...A method which is especially suitable for microcomputer calculation of the true orientation distribution function (ODF) according to the maximum-entropy estimate is proposed for hexagonal system polycrystalline materials with physical symmetry.The resultant computational software system has been also designed and first carried out in a microcomputer PANAFACOM-U1200 being on line with the X-ray diffractometer D/max-3A.The simu- lated calculation shows that the method is concisely pragmatic and easily popularized,while the results obtained are trust worthy.展开更多
<p> <span style="font-family:Verdana;">To address the drawbacks of the traditional Parker test in multivariate linear</span><span style="font-family:;" "=""> ...<p> <span style="font-family:Verdana;">To address the drawbacks of the traditional Parker test in multivariate linear</span><span style="font-family:;" "=""> </span><span style="font-family:Verdana;">models:</span><span style="font-family:;" "=""> </span><span style="font-family:Verdana;">the process is cumbersome and computationally intensive,</span><span style="font-family:;" "=""> </span><span style="font-family:Verdana;">we propose a new heteroscedasticity test.</span><span style="font-family:;" "=""> </span><span style="font-family:Verdana;">A new heteroskedasticity test is proposed using the fitted values of the samples as new explanatory variables, reconstructing the regression model, and giving a new heteroskedasticity test based on the significance test of the coefficients, it is also compared with the existing Parker test which is improved using the principal component idea. Numerical simulations and empirical analyses show that the improved Parker test with the fitted values of the samples proposed in this paper is superior.</span> </p>展开更多
To gain high efficiency for the simulation of the aerodynamic characteristics of the rotor in hover,body?fitted momentum source(BFMS)method is proposed.In this method,the actual blade geometry is represented by the si...To gain high efficiency for the simulation of the aerodynamic characteristics of the rotor in hover,body?fitted momentum source(BFMS)method is proposed.In this method,the actual blade geometry is represented by the single layer of volume grid surrounding the blade.Aiming at correctly simulating the aerodynamic characteristics of the discrete cells along the chordwise of blade airfoil section,a new distributed force model is proposed.For comparison,the RANS method with S?A turbulence model and the steady rotor momentum source(SRMS)method based on embedded grid systems are established,respectively.And the grid connecting methodology is improved to embed the blade into the background grids for the three methods.Then,simulations are performed for the hovering Caradonna?Tung rotor by these methods,and the calculated results are compared with the available experimental data.Moreover,the pressure distributions along the blade are compared with the conventional momentum source methods.It is demonstrated that the BFMS method can be employed as an effective approach to predict rotor aerodynamic characteristics with a low computational resource and reasonable accuracy.展开更多
By the discussion of the formula and properties of (4,4) parametric form rational approximation to function exp(q), the fourth order derivative one_step exponentially fitted method and the third order derivative hybri...By the discussion of the formula and properties of (4,4) parametric form rational approximation to function exp(q), the fourth order derivative one_step exponentially fitted method and the third order derivative hybrid one_step exponentially fitted method are presented, their order p satisfying 6≤p≤8. The necessary and sufficient conditions for the two methods to be A_ stable are given. Finally, for the fourth order derivative method, the error bound and the necessary and sufficient conditions for it to be median are discussed.展开更多
In this paper,the necessary and sufficient conditions for generalone-step m ethods to be exponentially fitted atq0∈C aregiven.A classofm ultiderivative hybrid one-step m ethods of order at leasts+ 1 is constructed ...In this paper,the necessary and sufficient conditions for generalone-step m ethods to be exponentially fitted atq0∈C aregiven.A classofm ultiderivative hybrid one-step m ethods of order at leasts+ 1 is constructed w ith s+ 1 param eters,w here sis the order of derivative.The necessary and sufficient conditions for these m ethods to be A-stable and exponentially fitted is proved.Furtherm ore,a class ofA-stable 2 param eters hybrid one-step m ethods oforderatleast 8 are constructed,w hich use 4th order derivative.These m ethods are exponentially fitted atq0 if and only if its fitted function f(q) satisfies f(q0)= 0.Finally,an A-stable exponentially fitted m ethod oforder 8 is obtained.展开更多
Confidence bands in a Normal Q-Q Plot allow us to detect non-normality of a data set rigorously, and in such a way that the conclusion does not depend on the subjectivity of the observer of the graph. In the construct...Confidence bands in a Normal Q-Q Plot allow us to detect non-normality of a data set rigorously, and in such a way that the conclusion does not depend on the subjectivity of the observer of the graph. In the construction of the graph, it is usual to fit a straight line to the plotted points, which serves both to check the hypothesis of normality (linear configuration of the plotted points) and to produce estimates of the parameters of the distribution. We can opt for dif-ferent types of lines. In this paper, we study the influence of five types of fitted straight lines in a Normal Q-Q Plot used for construction the confidence bands based on the exact distribution of the order statistics.展开更多
Spherical indentations that rely on original date are analyzed with the physically correct mathematical formula and its integration that take into account the radius over depth changes upon penetration. Linear plots, ...Spherical indentations that rely on original date are analyzed with the physically correct mathematical formula and its integration that take into account the radius over depth changes upon penetration. Linear plots, phase-transition onsets, energies, and pressures are algebraically obtained for germanium, zinc-oxide and gallium-nitride. There are low pressure phase-transitions that correspond to, or are not resolved by hydrostatic anvil onset pressures. This enables the attribution of polymorph structures, by comparing with known structures from pulsed laser deposition or molecular beam epitaxy and twinning. The spherical indentation is the easiest way for the synthesis and further characterization of polymorphs, now available in pure form under diamond calotte and in contact with their corresponding less dense polymorph. The unprecedented results and new possibilities require loading curves from experimental data. These are now easily distinguished from data that are “fitted” to make them concur with widely used unphysical Johnson’s formula for spheres (“<span style="white-space:nowrap;"><em>P</em> = (4/3)<em>h</em><sup>3/2</sup><em>R</em><sup>1/2</sup><em>E</em><sup><span style="white-space:nowrap;">∗</span></sup></span>”) not taking care of the <em>R/h</em> variation. Its challenge is indispensable, because its use involves “fitting equations” for making the data concur. These faked reports (no “experimental” data) provide dangerous false moduli and theories. The fitted spherical indentation reports with radii ranging from 4 to 250 μm are identified for PDMS, GaAs, Al, Si, SiC, MgO, and Steel. The detailed analysis reveals characteristic features.展开更多
In this paper we discuss, an initial-boundary value problem of hyperbolic type with first derivative with respect to x. The asymptotic solution is constructed and its uniform validity is proved under weader compatibil...In this paper we discuss, an initial-boundary value problem of hyperbolic type with first derivative with respect to x. The asymptotic solution is constructed and its uniform validity is proved under weader compatibility conditions. Then we develop an exponentially fitted difference scheme and establish discrete energy inequality. Finally, we prove that the solution of difference problem uniformly converges to the solution of the original problem.展开更多
In this paper,the regularity and finite difference methods for the two-dimensional delay fractional equations are considered.The analytic solution is derived by eigenvalue expansions and Laplace transformation.However...In this paper,the regularity and finite difference methods for the two-dimensional delay fractional equations are considered.The analytic solution is derived by eigenvalue expansions and Laplace transformation.However,due to the derivative discontinuities resulting from the delay effect,the traditional L1-ADI scheme fails to achieve the optimal convergence order.To overcome this issue and improve the convergence order,a simple and cost-effective decomposition technique is introduced and a fitted L1-ADI scheme is proposed.The numerical tests are conducted to verify the theoretical result.展开更多
A set of nonlinear Boussinesq equations with fully nonlinearity property is solved numerically in generalized coordinates,to develop a Boussinesq-type wave model in dealing with irregular computation boundaries in com...A set of nonlinear Boussinesq equations with fully nonlinearity property is solved numerically in generalized coordinates,to develop a Boussinesq-type wave model in dealing with irregular computation boundaries in complex nearshore regions and to facilitate the grid refinements in simulations.The governing equations expressed in contravariant components of velocity vectors under curvilinear coordinates are derived and a high order finite difference scheme on a staggered grid is employed for the numerical implementation.The developed model is used to simulate nearshore wave propagations under curvilinear coordinates,the numerical results are compared against analytical or experimental data with a good agreement.展开更多
In this paper, we study the local discontinuous Galerkin （LDG） method for one- dimensional singularly perturbed convection-diffusion problems by an exponentially fitted technique. We prove that the method is uniform...In this paper, we study the local discontinuous Galerkin （LDG） method for one- dimensional singularly perturbed convection-diffusion problems by an exponentially fitted technique. We prove that the method is uniformly first-order convergent in the energy norm with respect to the small diffusion parameter.展开更多
Gauss radial basis functions(GRBF)are frequently employed in data fitting and machine learning.Their linear independence property can theoretically guarantee the avoidance of data redundancy.In this paper,one of the m...Gauss radial basis functions(GRBF)are frequently employed in data fitting and machine learning.Their linear independence property can theoretically guarantee the avoidance of data redundancy.In this paper,one of the main contributions is proving this property using linear algebra instead of profound knowledge.This makes it easy to read and understand this fundamental fact.The proof of linear independence of a set of Gauss functions relies on the constructing method for one-dimensional space and on the deducing method for higher dimensions.Additionally,under the condition of preserving the same moments between the original function and interpolating function,both the interpolating existence and uniqueness are proven for GRBF in one-dimensional space.The final work demonstrates the application of the GRBF method to locate lunar olivine.By combining preprocessed data using GRBF with the removing envelope curve method,a program is created to find the position of lunar olivine based on spectrum data,and the numerical experiment shows that it is an effective scheme.展开更多
In [16], Stynes and O' Riordan(91) introduced a local exponentially fitted finite element (FE) scheme for a singularly perturbed two-point boundary value problem without turning-point. An E-uniform h(1/2)-order ac...In [16], Stynes and O' Riordan(91) introduced a local exponentially fitted finite element (FE) scheme for a singularly perturbed two-point boundary value problem without turning-point. An E-uniform h(1/2)-order accuracy was obtain for the epsilon-weighted energy norm. And this uniform order is known as an optimal one for global exponentially fitted FE schemes (see [6, 7, 12]). In present paper, this scheme is used to a parabolic singularly perturbed problem. After some subtle analysis, a uniformly in epsilon convergent order h\ln h\(1/2) + tau is achieved (h is the space step and tau is the time step), which sharpens the results in present literature. Furthermore, it implies that the accuracy order in [16] is actuallay h\ln h\(1/2) rather than h(1/2).展开更多
In this paper,we construct and analyze a Crank-Nicolson fitted finite volume scheme for pricing European options under regime-switching Kou’s jumpdiffusion model which is governed by a system of partial integro-diffe...In this paper,we construct and analyze a Crank-Nicolson fitted finite volume scheme for pricing European options under regime-switching Kou’s jumpdiffusion model which is governed by a system of partial integro-differential equations(PIDEs).We show that this scheme is consistent,stable and monotone as the mesh sizes in space and time approach zero,hence it ensures the convergence to the solution of continuous problem.Finally,numerical experiments are performed to demonstrate the efficiency,accuracy and robustness of the proposed method.展开更多
Background:Physical fitness is a key indicator of current and future health in children and adolescents.Evidence suggests that fitness levels have declined then stagnated in recent decades,but it remains unclear how t...Background:Physical fitness is a key indicator of current and future health in children and adolescents.Evidence suggests that fitness levels have declined then stagnated in recent decades,but it remains unclear how the coronavirus disease 2019(COVID-19)pandemic has impacted this trend.Methods:We conducted a systematic review and meta-analyses to assess pandemic-related changes in physical fitness among children and adolescents(0-19 years)in the World Health Organization European Region.Seven databases were searched up to February 28,2025 for studies reporting validated pre-and during/post-pandemic fitness measurements.Two reviewers independently performed screening,data extraction,risk-of-bias assessment(Risk Of Bias In Non-randomized Studies-of Exposure)(ROBINS-E),and certainty grading(Grading of Recommendations,Assessment,Development and Evaluation)(GRADE).Random-effects meta-analyses yielded standardized mean differences(SMDs)with 95%confidence intervals(95%CIs).Subgroup analyses examined sex,age,year,and national restriction severity(Oxford Stringency Index).Results:Thirty-two studies comprising 270,179 participants and 1,519,386 fitness measurements from 17 European countries were included.Cardiorespiratory fitness declined significantly during the pandemic,especially in 2021,with reductions in endurance(SMD=-0.43;95%CI:-0.61 to-0.25)and speed(SMD=-0.29;95%CI:-0.61 to 0.03).While speed returned to baseline by 2023,endurance remained below pre-pandemic levels(SMD=-0.10;95%CI:-0.12 to-0.08).Girls and adolescents were disproportionately affected.In contrast to cardiorespiratory fitness,muscular fitness remained largely unchanged.Stricter national regulations were associated with greater declines in cardiorespiratory fitness.Conclusion:COVID-19 pandemic restrictions were associated with a marked decline in cardiorespiratory fitness in European children and adolescents,with levels not recovered by 2023.These findings call for urgent,targeted public health interventions to improve physical fitness and prevent long-term health consequences.展开更多
A new sixth-order Runge-Kutta type method is developed for the numericalintegration of the radial Schrodinger equation and of the coupled differential equa-tions of the Schrodinger type. The formula developed contains...A new sixth-order Runge-Kutta type method is developed for the numericalintegration of the radial Schrodinger equation and of the coupled differential equa-tions of the Schrodinger type. The formula developed contains certain free pa-rameters which allows it to be fitted automatically to exponential functions. Wegive a comparative error analysis with other sixth order exponentially fitted meth-ods. The theoretical and numerical results indicate that the new method is moreaccurate than the other exponentially fitted methods.展开更多
In this paper,a modified boundary fitted coordinate method is presented.The transformation equations are solved by finite analytic method.The control equations after trans- formation are solved by splitting operator m...In this paper,a modified boundary fitted coordinate method is presented.The transformation equations are solved by finite analytic method.The control equations after trans- formation are solved by splitting operator method.The results of calculation consist well with experiments.展开更多
Background:Midlife lifestyle factors,including physical activity,are associated with late-life brain health,yet the role of aerobic exercise on structural brain health in early and mid-adulthood remains poorly underst...Background:Midlife lifestyle factors,including physical activity,are associated with late-life brain health,yet the role of aerobic exercise on structural brain health in early and mid-adulthood remains poorly understood.This study aimed to examine the effect of aerobic exercise on structural brain age and to explore potential mediators.Methods:In a single-blind,12-month randomized clinical trial,130 healthy participants aged 26-58 years were randomized into a moderate-to-vigorous intensity aerobic exercise group or a usual-care control group.The exercise group attended two supervised 60-min sessions per week in a laboratory setting plus engaged in home-based exercise to achieve 150 min of exercise per week.Brain-predicted age difference(brain-PAD)and cardiorespiratory fitness(CRF)were assessed at baseline and 12 months.Both intention-to-treat(ITT)and completers analyses(including participants who completed post-intervention assessments)were performed.Results:The 130 participants(67.7%female)had an age of 41.28±9.93 years(mean±SD).At baseline,higher CRF(peak oxygen uptake,VO_(2peak))was associated with smaller brain-PAD(β=-0.309,p=0.012).After the intervention,the exercise group showed a decrease in brainPAD(estimated mean difference(EMD)=-0.60;95%confidence interval(95%CI):-1.15 to-0.04;p=0.034)compared to the control group(EMD=0.35;95%CI:-0.21 to 0.92;p=0.217);time×group interaction(between-group difference(BGD)=-0.95;95%CI:-1.72 to-0.17;p=0.019).VO2peak improved in the exercise group(EMD=1.60;95%CI:0.29-2.90;p=0.017)compared to the control group(EMD=-0.78;95%CI:-2.17 to 0.60;p=0.265);time×group interaction(BGD=2.38;95%CI:0.52-4.25;p=0.015).Body composition,blood pressure,and brain-derived neurotrophic factor levels were unaffected.None of the proposed pathways statistically mediated the effect of exercise on brain-PAD.The results from completers were similar.Conclusion:Engaging in 12 months of moderate-to-vigorous exercise reduced brain-PAD in early-to-midlife adults.The pathways by which these effects occur remain unknown.展开更多
The Haoping 40 m radio telescope at the National Time Service Center,Chinese Academy of Sciences was built in 2014 and is primarily used to observe navigation satellites and pulsars.Since the first successful very lon...The Haoping 40 m radio telescope at the National Time Service Center,Chinese Academy of Sciences was built in 2014 and is primarily used to observe navigation satellites and pulsars.Since the first successful very long baseline interferometry(VLBI)observation of L-band radio source fringes in 2022,ten observations have been made so far.The stations involved in the observations include the Haoping 40 m radio telescope(Haoping),the Tianma 65 m radio telescope(Tianma),the Nanshan 26 m radio telescope(Urumqi),the Guizhou 500 m radio telescope(FAST),the Jilin 13 m radio telescope(Jilin),the Effelsberg 100 m radio telescope(Effelsberg),the Onsala 25 m radio telescope(Onsala),and the Chiang Mai 40 m radio telescope(Chiang Mai).This paper presents details on the specifications of the Haoping 40 m radio telescope,as well as the design of the VLBI experiment,the observation process,and the data processing.We also discuss the analysis of the fringe results involving the Haoping 40 m radio telescope,using Distributed FX Correlator to obtain excellent results.We confirm that the telescope is capable of participating in VLBI observations and performing specific data processing tasks.It can therefore play a greater role in future VLBI observations.展开更多
基金Supported by Chinese National Engineering Research Centre(CNERC)for Steel Construction(Hong Kong Branch)at the Hong Kong Polytechnic University under Project No.P0013864Programme Code BBV9)。
文摘Existing buildings can be at a greater seismic risk due to non-conformance to current design codes and may require structural retrofitting to improve building performance.The performance of buildings is measured in terms of immediate consequences due to direct damage,but the continuing impacts related to recovery are not considered in seismic retrofit assessment.This paper introduces a framework of retrofit selection based on the seismic resilience of deficient buildings retrofitted with the conventional mitigation approaches.The assembly-based methodology is considered for the seismic resilience assessment by compiling a nonlinear numerical model and a building performance model.The collapse fragility is developed from the capacity curve,and the resulting social,economic,and environmental consequences are determined.The seismic resilience of a building is assessed by developing a downtime assessment methodology incorporating sequence of repairs,impeding factors,and utility availability.Five functionality states are developed for the building functionality given investigated time interval,and a functionality curve for each retrofit is determined.It is concluded that seismic resilience can be used as a performance indicator to assess the continuing impacts of a hazard for the retrofit selection.
文摘A method which is especially suitable for microcomputer calculation of the true orientation distribution function (ODF) according to the maximum-entropy estimate is proposed for hexagonal system polycrystalline materials with physical symmetry.The resultant computational software system has been also designed and first carried out in a microcomputer PANAFACOM-U1200 being on line with the X-ray diffractometer D/max-3A.The simu- lated calculation shows that the method is concisely pragmatic and easily popularized,while the results obtained are trust worthy.
文摘<p> <span style="font-family:Verdana;">To address the drawbacks of the traditional Parker test in multivariate linear</span><span style="font-family:;" "=""> </span><span style="font-family:Verdana;">models:</span><span style="font-family:;" "=""> </span><span style="font-family:Verdana;">the process is cumbersome and computationally intensive,</span><span style="font-family:;" "=""> </span><span style="font-family:Verdana;">we propose a new heteroscedasticity test.</span><span style="font-family:;" "=""> </span><span style="font-family:Verdana;">A new heteroskedasticity test is proposed using the fitted values of the samples as new explanatory variables, reconstructing the regression model, and giving a new heteroskedasticity test based on the significance test of the coefficients, it is also compared with the existing Parker test which is improved using the principal component idea. Numerical simulations and empirical analyses show that the improved Parker test with the fitted values of the samples proposed in this paper is superior.</span> </p>
基金supported by the Qian Xuesen Innovation Foud of China Aerospace Science and Technolygy Corporation
文摘To gain high efficiency for the simulation of the aerodynamic characteristics of the rotor in hover,body?fitted momentum source(BFMS)method is proposed.In this method,the actual blade geometry is represented by the single layer of volume grid surrounding the blade.Aiming at correctly simulating the aerodynamic characteristics of the discrete cells along the chordwise of blade airfoil section,a new distributed force model is proposed.For comparison,the RANS method with S?A turbulence model and the steady rotor momentum source(SRMS)method based on embedded grid systems are established,respectively.And the grid connecting methodology is improved to embed the blade into the background grids for the three methods.Then,simulations are performed for the hovering Caradonna?Tung rotor by these methods,and the calculated results are compared with the available experimental data.Moreover,the pressure distributions along the blade are compared with the conventional momentum source methods.It is demonstrated that the BFMS method can be employed as an effective approach to predict rotor aerodynamic characteristics with a low computational resource and reasonable accuracy.
基金the Science Technology Foundation of Ministry of Machine_ Buildin
文摘By the discussion of the formula and properties of (4,4) parametric form rational approximation to function exp(q), the fourth order derivative one_step exponentially fitted method and the third order derivative hybrid one_step exponentially fitted method are presented, their order p satisfying 6≤p≤8. The necessary and sufficient conditions for the two methods to be A_ stable are given. Finally, for the fourth order derivative method, the error bound and the necessary and sufficient conditions for it to be median are discussed.
文摘In this paper,the necessary and sufficient conditions for generalone-step m ethods to be exponentially fitted atq0∈C aregiven.A classofm ultiderivative hybrid one-step m ethods of order at leasts+ 1 is constructed w ith s+ 1 param eters,w here sis the order of derivative.The necessary and sufficient conditions for these m ethods to be A-stable and exponentially fitted is proved.Furtherm ore,a class ofA-stable 2 param eters hybrid one-step m ethods oforderatleast 8 are constructed,w hich use 4th order derivative.These m ethods are exponentially fitted atq0 if and only if its fitted function f(q) satisfies f(q0)= 0.Finally,an A-stable exponentially fitted m ethod oforder 8 is obtained.
文摘Confidence bands in a Normal Q-Q Plot allow us to detect non-normality of a data set rigorously, and in such a way that the conclusion does not depend on the subjectivity of the observer of the graph. In the construction of the graph, it is usual to fit a straight line to the plotted points, which serves both to check the hypothesis of normality (linear configuration of the plotted points) and to produce estimates of the parameters of the distribution. We can opt for dif-ferent types of lines. In this paper, we study the influence of five types of fitted straight lines in a Normal Q-Q Plot used for construction the confidence bands based on the exact distribution of the order statistics.
文摘Spherical indentations that rely on original date are analyzed with the physically correct mathematical formula and its integration that take into account the radius over depth changes upon penetration. Linear plots, phase-transition onsets, energies, and pressures are algebraically obtained for germanium, zinc-oxide and gallium-nitride. There are low pressure phase-transitions that correspond to, or are not resolved by hydrostatic anvil onset pressures. This enables the attribution of polymorph structures, by comparing with known structures from pulsed laser deposition or molecular beam epitaxy and twinning. The spherical indentation is the easiest way for the synthesis and further characterization of polymorphs, now available in pure form under diamond calotte and in contact with their corresponding less dense polymorph. The unprecedented results and new possibilities require loading curves from experimental data. These are now easily distinguished from data that are “fitted” to make them concur with widely used unphysical Johnson’s formula for spheres (“<span style="white-space:nowrap;"><em>P</em> = (4/3)<em>h</em><sup>3/2</sup><em>R</em><sup>1/2</sup><em>E</em><sup><span style="white-space:nowrap;">∗</span></sup></span>”) not taking care of the <em>R/h</em> variation. Its challenge is indispensable, because its use involves “fitting equations” for making the data concur. These faked reports (no “experimental” data) provide dangerous false moduli and theories. The fitted spherical indentation reports with radii ranging from 4 to 250 μm are identified for PDMS, GaAs, Al, Si, SiC, MgO, and Steel. The detailed analysis reveals characteristic features.
文摘In this paper we discuss, an initial-boundary value problem of hyperbolic type with first derivative with respect to x. The asymptotic solution is constructed and its uniform validity is proved under weader compatibility conditions. Then we develop an exponentially fitted difference scheme and establish discrete energy inequality. Finally, we prove that the solution of difference problem uniformly converges to the solution of the original problem.
基金supported by University of Macao(File nos.MYRG2020-00035-FST,MYRG2022-00076-FST,MYRG2022-00262-FST).
文摘In this paper,the regularity and finite difference methods for the two-dimensional delay fractional equations are considered.The analytic solution is derived by eigenvalue expansions and Laplace transformation.However,due to the derivative discontinuities resulting from the delay effect,the traditional L1-ADI scheme fails to achieve the optimal convergence order.To overcome this issue and improve the convergence order,a simple and cost-effective decomposition technique is introduced and a fitted L1-ADI scheme is proposed.The numerical tests are conducted to verify the theoretical result.
基金Project supported by the National Natural Science Foundation of China (Grant Nos.51009018,51079024)the Founds for Creative Research Groups of China (Grant No.50921001)+1 种基金the Key Laboratory of Coastal Disaster and Defence,Ministry of Education,Hohai University (Grant No.200803)the State Key Laboratory of Coastal and Offshore Engineering,Dalian University of Technology (Grant No.LP1105)
文摘A set of nonlinear Boussinesq equations with fully nonlinearity property is solved numerically in generalized coordinates,to develop a Boussinesq-type wave model in dealing with irregular computation boundaries in complex nearshore regions and to facilitate the grid refinements in simulations.The governing equations expressed in contravariant components of velocity vectors under curvilinear coordinates are derived and a high order finite difference scheme on a staggered grid is employed for the numerical implementation.The developed model is used to simulate nearshore wave propagations under curvilinear coordinates,the numerical results are compared against analytical or experimental data with a good agreement.
文摘In this paper, we study the local discontinuous Galerkin （LDG） method for one- dimensional singularly perturbed convection-diffusion problems by an exponentially fitted technique. We prove that the method is uniformly first-order convergent in the energy norm with respect to the small diffusion parameter.
基金Supported by the National Basic Research Program of China(2012CB025904)Zhengzhou Shengda University of Economics,Business and Management(SD-YB2025085)。
文摘Gauss radial basis functions(GRBF)are frequently employed in data fitting and machine learning.Their linear independence property can theoretically guarantee the avoidance of data redundancy.In this paper,one of the main contributions is proving this property using linear algebra instead of profound knowledge.This makes it easy to read and understand this fundamental fact.The proof of linear independence of a set of Gauss functions relies on the constructing method for one-dimensional space and on the deducing method for higher dimensions.Additionally,under the condition of preserving the same moments between the original function and interpolating function,both the interpolating existence and uniqueness are proven for GRBF in one-dimensional space.The final work demonstrates the application of the GRBF method to locate lunar olivine.By combining preprocessed data using GRBF with the removing envelope curve method,a program is created to find the position of lunar olivine based on spectrum data,and the numerical experiment shows that it is an effective scheme.
文摘In [16], Stynes and O' Riordan(91) introduced a local exponentially fitted finite element (FE) scheme for a singularly perturbed two-point boundary value problem without turning-point. An E-uniform h(1/2)-order accuracy was obtain for the epsilon-weighted energy norm. And this uniform order is known as an optimal one for global exponentially fitted FE schemes (see [6, 7, 12]). In present paper, this scheme is used to a parabolic singularly perturbed problem. After some subtle analysis, a uniformly in epsilon convergent order h\ln h\(1/2) + tau is achieved (h is the space step and tau is the time step), which sharpens the results in present literature. Furthermore, it implies that the accuracy order in [16] is actuallay h\ln h\(1/2) rather than h(1/2).
基金supported by the National Natural Science Foundation of China(Nos.11971354,and 11701221)the Special Basic Cooperative Research Programs of Yunnan Provincial Undergraduate Universities’Association(No.2019FH001-079)the Fundamental Research Funds for the Central Universities(No.22120210555).
文摘In this paper,we construct and analyze a Crank-Nicolson fitted finite volume scheme for pricing European options under regime-switching Kou’s jumpdiffusion model which is governed by a system of partial integro-differential equations(PIDEs).We show that this scheme is consistent,stable and monotone as the mesh sizes in space and time approach zero,hence it ensures the convergence to the solution of continuous problem.Finally,numerical experiments are performed to demonstrate the efficiency,accuracy and robustness of the proposed method.
文摘Background:Physical fitness is a key indicator of current and future health in children and adolescents.Evidence suggests that fitness levels have declined then stagnated in recent decades,but it remains unclear how the coronavirus disease 2019(COVID-19)pandemic has impacted this trend.Methods:We conducted a systematic review and meta-analyses to assess pandemic-related changes in physical fitness among children and adolescents(0-19 years)in the World Health Organization European Region.Seven databases were searched up to February 28,2025 for studies reporting validated pre-and during/post-pandemic fitness measurements.Two reviewers independently performed screening,data extraction,risk-of-bias assessment(Risk Of Bias In Non-randomized Studies-of Exposure)(ROBINS-E),and certainty grading(Grading of Recommendations,Assessment,Development and Evaluation)(GRADE).Random-effects meta-analyses yielded standardized mean differences(SMDs)with 95%confidence intervals(95%CIs).Subgroup analyses examined sex,age,year,and national restriction severity(Oxford Stringency Index).Results:Thirty-two studies comprising 270,179 participants and 1,519,386 fitness measurements from 17 European countries were included.Cardiorespiratory fitness declined significantly during the pandemic,especially in 2021,with reductions in endurance(SMD=-0.43;95%CI:-0.61 to-0.25)and speed(SMD=-0.29;95%CI:-0.61 to 0.03).While speed returned to baseline by 2023,endurance remained below pre-pandemic levels(SMD=-0.10;95%CI:-0.12 to-0.08).Girls and adolescents were disproportionately affected.In contrast to cardiorespiratory fitness,muscular fitness remained largely unchanged.Stricter national regulations were associated with greater declines in cardiorespiratory fitness.Conclusion:COVID-19 pandemic restrictions were associated with a marked decline in cardiorespiratory fitness in European children and adolescents,with levels not recovered by 2023.These findings call for urgent,targeted public health interventions to improve physical fitness and prevent long-term health consequences.
文摘A new sixth-order Runge-Kutta type method is developed for the numericalintegration of the radial Schrodinger equation and of the coupled differential equa-tions of the Schrodinger type. The formula developed contains certain free pa-rameters which allows it to be fitted automatically to exponential functions. Wegive a comparative error analysis with other sixth order exponentially fitted meth-ods. The theoretical and numerical results indicate that the new method is moreaccurate than the other exponentially fitted methods.
文摘In this paper,a modified boundary fitted coordinate method is presented.The transformation equations are solved by finite analytic method.The control equations after trans- formation are solved by splitting operator method.The results of calculation consist well with experiments.
基金funded by the National Institutes of Health and the National Heart,Lung,and Blood Institute(P01HL040962)。
文摘Background:Midlife lifestyle factors,including physical activity,are associated with late-life brain health,yet the role of aerobic exercise on structural brain health in early and mid-adulthood remains poorly understood.This study aimed to examine the effect of aerobic exercise on structural brain age and to explore potential mediators.Methods:In a single-blind,12-month randomized clinical trial,130 healthy participants aged 26-58 years were randomized into a moderate-to-vigorous intensity aerobic exercise group or a usual-care control group.The exercise group attended two supervised 60-min sessions per week in a laboratory setting plus engaged in home-based exercise to achieve 150 min of exercise per week.Brain-predicted age difference(brain-PAD)and cardiorespiratory fitness(CRF)were assessed at baseline and 12 months.Both intention-to-treat(ITT)and completers analyses(including participants who completed post-intervention assessments)were performed.Results:The 130 participants(67.7%female)had an age of 41.28±9.93 years(mean±SD).At baseline,higher CRF(peak oxygen uptake,VO_(2peak))was associated with smaller brain-PAD(β=-0.309,p=0.012).After the intervention,the exercise group showed a decrease in brainPAD(estimated mean difference(EMD)=-0.60;95%confidence interval(95%CI):-1.15 to-0.04;p=0.034)compared to the control group(EMD=0.35;95%CI:-0.21 to 0.92;p=0.217);time×group interaction(between-group difference(BGD)=-0.95;95%CI:-1.72 to-0.17;p=0.019).VO2peak improved in the exercise group(EMD=1.60;95%CI:0.29-2.90;p=0.017)compared to the control group(EMD=-0.78;95%CI:-2.17 to 0.60;p=0.265);time×group interaction(BGD=2.38;95%CI:0.52-4.25;p=0.015).Body composition,blood pressure,and brain-derived neurotrophic factor levels were unaffected.None of the proposed pathways statistically mediated the effect of exercise on brain-PAD.The results from completers were similar.Conclusion:Engaging in 12 months of moderate-to-vigorous exercise reduced brain-PAD in early-to-midlife adults.The pathways by which these effects occur remain unknown.
基金supported by the National Science and Technology Major Project(E152KJ1201)the Natural Science Basic Research Program of Shaanxi(2024JC-YBQN-0036)+1 种基金the National Natural Science Foundation of China(42030105 and 11973046)the National SKA Program of China(2020SKA0120200).
文摘The Haoping 40 m radio telescope at the National Time Service Center,Chinese Academy of Sciences was built in 2014 and is primarily used to observe navigation satellites and pulsars.Since the first successful very long baseline interferometry(VLBI)observation of L-band radio source fringes in 2022,ten observations have been made so far.The stations involved in the observations include the Haoping 40 m radio telescope(Haoping),the Tianma 65 m radio telescope(Tianma),the Nanshan 26 m radio telescope(Urumqi),the Guizhou 500 m radio telescope(FAST),the Jilin 13 m radio telescope(Jilin),the Effelsberg 100 m radio telescope(Effelsberg),the Onsala 25 m radio telescope(Onsala),and the Chiang Mai 40 m radio telescope(Chiang Mai).This paper presents details on the specifications of the Haoping 40 m radio telescope,as well as the design of the VLBI experiment,the observation process,and the data processing.We also discuss the analysis of the fringe results involving the Haoping 40 m radio telescope,using Distributed FX Correlator to obtain excellent results.We confirm that the telescope is capable of participating in VLBI observations and performing specific data processing tasks.It can therefore play a greater role in future VLBI observations.
