This paper presents an efficient and automated Overset Grid Assembly(OGA)method for the structured grid,and investigates high-order interpolation methods for inter-grid boundaries with the cell-centered finite differe...This paper presents an efficient and automated Overset Grid Assembly(OGA)method for the structured grid,and investigates high-order interpolation methods for inter-grid boundaries with the cell-centered finite difference method.Four enhancements are introduced:a hybrid holecutting approach integrates the efficiency of approximate hole-cutting and the accuracy and robustness of direct-cutting,effectively addressing challenges such as small gaps and thin cuts;an improved implicit hole boundary optimization method,incorporating quality comparison,can significantly reduce donor search workloads;an improved implicit interpolation cell cancellation algorithm minimizes overlap regions,particularly beneficial for high-order interpolation with large stencils;an algorithm for identifying and eliminating islands without using wall distances,effectively removes islands.The OGA results of a multi-element airfoil,a circular array of cylinders,multiple spheres,and a wing-pylon-store configuration indicate that the proposed method would be a suitable selection for multi-body problems,even in the presence of small gaps and thin geometries.Additionally,for high-order interpolation at inter-grid boundaries,this study presents an optimized interpolation method designed to minimize spectral property errors.Numerical results indicate that for periodic problems frequently crossing inter-grid boundaries,the optimized interpolation is more accurate than classical Lagrange interpolation and would be a suitable selection.展开更多
Due to the complex and dynamic nature of multi-phase interfaces,accurately capturing interface evolution remains one of the key challenges in multi-phase flow simulations,particularly in modeling bubble rising.In this...Due to the complex and dynamic nature of multi-phase interfaces,accurately capturing interface evolution remains one of the key challenges in multi-phase flow simulations,particularly in modeling bubble rising.In this study,a fully Lagrangian method is developed by using the Generalized Finite Difference(GFD)scheme,which we refer to as Finite Difference Particle Method(FDPM),and the Continuum Surface Force(CSF)model to simulate bubble dynamics.In this framework,the fluid is represented by particles,and all partial differential terms in the Navier–Stokes equations are discretized into symmetric linear systems using the GFD scheme.Notably,the interface curvature required by the CSF model is computed directly via the Laplacian of the color function,rather than through the divergence of the unit normal vector.The bubble relaxation cases with various density ratios(up to 1000)are tested,revealing that the pressure distributions inside and outside the bubbles generally agree with theoretical predictions.Finally,simulations of rising bubbles with a high density ratio(1:1000)and Reynolds number of 25 demonstrate that the time evolution of the bubble’s center of mass by FDPM is consistent with results obtained by the Smoothed Particle Hydrodynamics(SPH)and the Finite Element Method(FEM)approaches.展开更多
In this study,the frequency and vibration responses of a sandwich micro-beam are derived based on the modified couple stress theory(MCST).The face sheets are made of pure aluminum,and a magneto-rheological(MR)core is ...In this study,the frequency and vibration responses of a sandwich micro-beam are derived based on the modified couple stress theory(MCST).The face sheets are made of pure aluminum,and a magneto-rheological(MR)core is used to control vibrations.The displacement fields are assumed based on the classical beam theory(CBT)and modified classical beam theories.Based on Hamilton's principle,the governing equations of motion are obtained.To solve these temporal equations,the finite difference method(FDM)with an optimal number of nodes is applied.The effects of various parameters,including viscoelastic properties,magnetic fields,aspect ratio,core-to-face-sheet thickness ratio,MR materials,face sheets,and material length-scale parameters,on the frequency and vibrational response are investigated.In the literature,the effects of different parameters on the frequency response function(FRF)or vibration response are considered.The results obtained from the vibration response and FRF using the FDM show that the viscoelastic property of the MR core causes settling time in the vibration response and a decrease in the excitation frequency of the FRF.Increasing the magnetic field has a negligible effect on the excitation frequency in the FRF,but it increases the vibration response and settling time.The piezoelectric face sheets raise the FRF and suppress the vibration response of the MR sandwich micro-beam compared with the aluminum counterpart.展开更多
Against the backdrop of the digital economy becoming a core engine for highquality regional economic development and Shandong accelerating the construction of a digital province,this paper identifies the industrial li...Against the backdrop of the digital economy becoming a core engine for highquality regional economic development and Shandong accelerating the construction of a digital province,this paper identifies the industrial life cycle of Shandong’s digital economy from 2011 to 2025 using the Logistic model.An evaluation index system is established covering four dimensions:digital infrastructure,digital industrialization,industrial digitalization,and digital governance.With the entropy weight method,it measures the digital economy development level of 16 prefecture-level cities in Shandong from 2020 to 2024 and analyzes its temporal and spatial evolution.The results show that Shandong’s digital economy is in the early growth stage,with a saturation value of 1,3986.552 billion yuan and projected growth peak in 2027.All cities achieved steady development,while the gap between leading and lagging cities widened slightly with an obvious Matthew effect.A stable three-tier spatial pattern has formed,featuring a layout of stronger east,weaker west,faster south,slower north.Industrial digitalization and digital governance serve as core driving forces,and the growth driver has shifted from infrastructure to industrial integration and technological innovation.Corresponding policy suggestions are put forward to support the balanced and high-quality development of Shandong’s digital economy.展开更多
A method combining finite difference method(FDM)and k-means clustering algorithm which can determine the threshold of rock bridge generation is proposed.Jointed slope models with different joint coalescence coefficien...A method combining finite difference method(FDM)and k-means clustering algorithm which can determine the threshold of rock bridge generation is proposed.Jointed slope models with different joint coalescence coefficients(k)are constructed based on FDM.The rock bridge area was divided through k-means algorithm and the optimal number of clusters was determined by sum of squared errors(SSE)and elbow method.The influence of maximum principal stress and stress change rate as clustering indexes on the clustering results of rock bridges was compared by using Euclidean distance.The results show that using stress change rate as clustering index is more effective.When the joint coalescence coefficient is less than 0.6,there is no significant stress concentration in the middle area of adjacent joints,that is,no generation of rock bridge.In addition,the range of rock bridge is affected by the coalescence coefficient(k),the relative position of joints and the parameters of weak interlayer.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(τ2+hx4+hy4)is suggested,whereτ,hx,hy 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(τ4+hx4+hy4)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
Soft measurement based on data-driven models is an important method to predict key variables in process industry due to low latency demand and economics costs.However,data-driven models cannot provide accurate predict...Soft measurement based on data-driven models is an important method to predict key variables in process industry due to low latency demand and economics costs.However,data-driven models cannot provide accurate prediction on a noisy data set with a small number of samples.In response to the challenge of noisy data and lack of samples,several data-mechanism hybrid driven methods are proposed to improve key variables prediction performances on the basis of three data-driven models including random forest,extreme gradient boosting,and artificial neural network.Simultaneously,the effectiveness of hybrid driven methods proposed is validated via two cases including benzene-toluene-xylene distillation and steam methane reforming process,where data sets feature different sample sizes and noise intensity.The comparison results show that the hybrid driven methods can improve the prediction accuracy to a certain extent.The degree of improvement depends on the noise intensity,sample size,and data-driven model selected.Under conditions of noise intensity at 10%–20%and sample size ranging from 100 to 400 in this work,after adopting the hybrid driven methods,the coefficient of determination for random forest,extreme gradient boosting,and artificial neural network can be improved by 0.3%–5.2%,0.6%–17.7%,and 0.1%–36.2%compared to corresponding data driven models.展开更多
This study investigates the complex heat transfer dynamics inmultilayer bifacial photovoltaic(bPV)solar modules under spectrally resolved solar irradiation.A novel numericalmodel is developed to incorporate internal h...This study investigates the complex heat transfer dynamics inmultilayer bifacial photovoltaic(bPV)solar modules under spectrally resolved solar irradiation.A novel numericalmodel is developed to incorporate internal heat generation resulting from optical absorption,grounded in the physical equations governing light-matter interactions within the module’smultilayer structure.The model accounts for reflection and transmission at each interface between adjacent layers,as well as absorption within individual layers,using the wavelength-dependent dielectric properties of constituent materials.These properties are used to calculate the spectral reflectance,transmittance,and absorption coefficients,enabling precise quantification of internal heat sources from irradiance incidents on both the front and rear surfaces of the module.The study further examines the influence of irradiance reflection on thermal behavior,evaluates the thermal impact of various supporting materials placed beneath the module,and analyzes the role of albedo in modifying heat distribution.By incorporating spectrally resolved heat generation across each layer often simplified or omitted in conventional models,the proposed approach enhances physical accuracy.The transient heat equation is solved using a one-dimensional finite difference(FD)method to produce detailed temperature profiles under multiple operating scenarios,including Standard Test Conditions(STC),Bifacial Standard Test Conditions(BSTC),Normal Operating Cell Temperature(NOCT),and Bifacial NOCT(BNOCT).The results offer valuable insights into the interplay between optical and thermal phenomena in bifacial systems,informing the design and optimization of more efficient photovoltaic technologies.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
In response to the issue of fuzzy matching and association when optical observation data are matched with the orbital elements in a catalog database,this paper proposes a matching and association strategy based on the...In response to the issue of fuzzy matching and association when optical observation data are matched with the orbital elements in a catalog database,this paper proposes a matching and association strategy based on the arcsegment difference method.First,a matching error threshold is set to match the observation data with the known catalog database.Second,the matching results for the same day are sorted on the basis of target identity and observation residuals.Different matching error thresholds and arc-segment dynamic association thresholds are then applied to categorize the observation residuals of the same target across different arc-segments,yielding matching results under various thresholds.Finally,the orbital residual is computed through orbit determination(OD),and the positional error is derived by comparing the OD results with the orbit track from the catalog database.The appropriate matching error threshold is then selected on the basis of these results,leading to the final matching and association of the fuzzy correlation data.Experimental results showed that the correct matching rate for data arc-segments is 92.34% when the matching error threshold is set to 720″,with the arc-segment difference method processing the results of an average matching rate of 97.62% within 8 days.The remaining 5.28% of the fuzzy correlation data are correctly matched and associated,enabling identification of orbital maneuver targets through further processing and analysis.This method substantially enhances the efficiency and accuracy of space target cataloging,offering robust technical support for dynamic maintenance of the space target database.展开更多
To enhance the computational efficiency of spatio-temporally discretized phase-field models,we present a high-speed solver specifically designed for the Poisson equations,a component frequently used in the numerical c...To enhance the computational efficiency of spatio-temporally discretized phase-field models,we present a high-speed solver specifically designed for the Poisson equations,a component frequently used in the numerical computation of such models.This efficient solver employs algorithms based on discrete cosine transformations(DCT)or discrete sine transformations(DST)and is not restricted by any spatio-temporal schemes.Our proposed methodology is appropriate for a variety of phase-field models and is especially efficient when combined with flow field systems.Meanwhile,this study has conducted an extensive numerical comparison and found that employing DCT and DST techniques not only yields results comparable to those obtained via the Multigrid(MG)method,a conventional approach used in the resolution of the Poisson equations,but also enhances computational efficiency by over 90%.展开更多
Based on some assumptions, the dynamic analysis model of anchorage system is established. The dynamic governing equation is expressed as finite difference format and programmed by using MATLAB language. Compared with ...Based on some assumptions, the dynamic analysis model of anchorage system is established. The dynamic governing equation is expressed as finite difference format and programmed by using MATLAB language. Compared with theoretical method, the finite difference method has been verified to be feasible by a case study. It is found that under seismic loading, the dynamic response of anchorage system is synchronously fluctuated with the seismic vibration. The change of displacement amplitude of material points is slight, and comparatively speaking, the displacement amplitude of the outside point is a little larger than that of the inside point, which shows amplification effect of surface. While the axial force amplitude transforms considerably from the inside to the outside. It increases first and reaches the peak value in the intersection between the anchoring section and free section, then decreases slowly in the free section. When considering damping effect of anchorage system, the finite difference method can reflect the time attenuation characteristic better, and the calculating result would be safer and more reasonable than the dynamic steady-state theoretical method. What is more, the finite difference method can be applied to the dynamic response analysis of harmonic and seismic random vibration for all kinds of anchor, and hence has a broad application prospect.展开更多
By using asymptotic method,we verify the existence on the slowly growing solutions to second order difference equations discussed by Ishizaki-Yanagihara’s Wiman-Valiron method and Ishizaki-Wen’s binomial series meth...By using asymptotic method,we verify the existence on the slowly growing solutions to second order difference equations discussed by Ishizaki-Yanagihara’s Wiman-Valiron method and Ishizaki-Wen’s binomial series method.The classical problem on finding conditions on the polynomial coefficients Pj(z)(j=0,1,2)and F(z)to guarantee that all nontrivial solutions of complex second order difference equation P2(z)f(z+2)+P1(z)f(z+1)+P0(z)f(z)=F(z)has slowly growing solutions with order 1/2 is detected.展开更多
A fast explicit finite difference method (FEFDM),derived from the differential equations of one-dimensional steady pipe flow,was presented for calculation of wellhead injection pressure.Recalculation with a traditiona...A fast explicit finite difference method (FEFDM),derived from the differential equations of one-dimensional steady pipe flow,was presented for calculation of wellhead injection pressure.Recalculation with a traditional numerical method of the same equations corroborates well the reliability and rate of FEFDM.Moreover,a flow rate estimate method was developed for the project whose injection rate has not been clearly determined.A wellhead pressure regime determined by this method was successfully applied to the trial injection operations in Shihezi formation of Shenhua CCS Project,which is a good practice verification of FEFDM.At last,this method was used to evaluate the effect of friction and acceleration terms on the flow equation on the wellhead pressure.The result shows that for deep wellbore,the friction term can be omitted when flow rate is low and in a wide range of velocity the acceleration term can always be deleted.It is also shown that with flow rate increasing,the friction term can no longer be neglected.展开更多
Thermal stress simulation can provide a scientific reference to eliminate defects such as crack,residual stress centralization and deformation etc.,caused by thermal stress during casting solidification.To study the t...Thermal stress simulation can provide a scientific reference to eliminate defects such as crack,residual stress centralization and deformation etc.,caused by thermal stress during casting solidification.To study the thermal stress distribution during casting process,a unilateral thermal-stress coupling model was employed to simulate 3D casting stress using Finite Difference Method(FDM),namely all the traditional thermal-elastic-plastic equations are numerically and differentially discrete.A FDM/FDM numerical simulation system was developed to analyze temperature and stress fields during casting solidification process.Two practical verifications were carried out,and the results from simulation basically coincided with practical cases.The results indicated that the FDM/FDM stress simulation system can be used to simulate the formation of residual stress,and to predict the occurrence of hot tearing.Because heat transfer and stress analysis are all based on FDM,they can use the same FD model,which can avoid the matching process between different models,and hence reduce temperature-load transferring errors.This approach makes the simulation of fluid flow,heat transfer and stress analysis unify into one single model.展开更多
A new compact finite difference-Fourier spectral hybrid method for solving the three dimensional incompressible Navier-Stokes equations is developed in the present paper. The fifth-order upwind compact finite differen...A new compact finite difference-Fourier spectral hybrid method for solving the three dimensional incompressible Navier-Stokes equations is developed in the present paper. The fifth-order upwind compact finite difference schemes for the nonlinear convection terms in the physical space, and the sixth-order center compact schemes for the derivatives in spectral space are described, respectively. The fourth-order compact schemes in a single nine-point cell for solving the Helmholtz equations satisfied by the velocities and pressure in spectral space is derived and its preconditioned conjugate gradient iteration method is studied. The treatment of pressure boundary conditions and the three dimensional non-reflecting outflow boundary conditions are presented. Application to the vortex dislocation evolution in a three dimensional wake is also reported.展开更多
In modelling elastic wave propagation in a porous medium, when the ratio between the fluid viscosity and the medium permeability is comparatively large, the stiffness problem of Blot's poroelastic equations will be e...In modelling elastic wave propagation in a porous medium, when the ratio between the fluid viscosity and the medium permeability is comparatively large, the stiffness problem of Blot's poroelastic equations will be encountered. In the paper, a partition method is developed to solve the stiffness problem with a staggered high-order finite-difference. The method splits the Biot equations into two systems. One is stiff, and solved analytically, the other is nonstiff, and solved numerically by using a high-order staggered-grid finite-difference scheme. The time step is determined by the staggered finite-difference algorithm in solving the nonstiff equations, thus a coarse time step may be employed. Therefore, the computation efficiency and computational stability are improved greatly. Also a perfect by matched layer technology is used in the split method as absorbing boundary conditions. The numerical results are compared with the analytical results and those obtained from the conventional staggered-grid finite-difference method in a homogeneous model, respectively. They are in good agreement with each other. Finally, a slightly more complex model is investigated and compared with related equivalent model to illustrate the good performance of the staggered-grid finite-difference scheme in the partition method.展开更多
Factory-level data from 23 provinces and some national statistical data in cement manufacturing industry and socio-economies in 2012 are used to analyze the spatial distribution of exergy use for China's cement manuf...Factory-level data from 23 provinces and some national statistical data in cement manufacturing industry and socio-economies in 2012 are used to analyze the spatial distribution of exergy use for China's cement manufacturing industry by the Extended Exergy Accounting method. This method takes full account of the inclusion of energy and raw material supply and other external factors (capital, labor and environment) into a comprehensive resource cost assessment. The extended exergy consumption and its intensity quantitatively at the provincial levels of cement production were calculated and then the agglomeration level of exergy use at the regional level was also evaluated. Based on this analysis, their spatial difference in size and efficiency of exergy use at the provincial level were identified. Moreover, their regional characteristics were revealed. Some important results could be drawn as follows. First, the invisible social cost accounted for 1/10 of the total exergy use in cement manufacturing industry, while the energy element shared about 9/10. Second, the gross distribution of exergy use in China's cement manufacturing industry was mainly concentrated in the eastern region like Anhui and Shandong provinces, and in the western region like Sichuan province. In terms of exergy use, the coal and electricity were the highest of energy costs in the eastern region, whereas the cost of capital, labor and external environmental factors highlighted the invisible social cost for cement production in the central and western regions to some extent. Third, the efficiency distribution of exergy use in China's cement manufacturing industry illustrated an incremental feature from west to east, especially for the energy, labor and capital efficiencies. An evaluation on the environmental efficiency indicated that provinces or regions like Tibet, Xinjiang, Inner Mongolia and Shanxi have undertaken much higher environmental costs. Fourth, the 23 provinces could be classified into eight groups by the Euclidean distance model using the gross and efficiency results of exergy use. Fifth, the high industry concentration degree is the main driving factor of exergy efficiency improvement for cement manufacturing industry in China.展开更多
An explicit finite element-finite difference method for analyzing the effects of two-dimensional visco-elastic localtopography on earthquake ground motion is prOPosed in this paper. In the method, at first, the finite...An explicit finite element-finite difference method for analyzing the effects of two-dimensional visco-elastic localtopography on earthquake ground motion is prOPosed in this paper. In the method, at first, the finite elementdiscrete model is formed by using the artificial boundary and finite element method, and the dynamic equationsof local nodes in the discrete model are obtained according to the theory of the special finite element method similar to the finite difference method, and then the explicit step-by-step integration formulas are presented by usingthe explicit difference method for solving the visco-elastic dynamic equation and Generalized Multi-transmittingBoundary. The method has the advantages of saving computing time and computer memory space, and it is suitable for any case of topography and has high computing accuracy and good computing stability.展开更多
The ground penetrating radar(GPR)forward simulation all aims at the singular and regular models,such as sandwich model,round cavity,square cavity,and so on,which are comparably simple.But as to the forward of curl int...The ground penetrating radar(GPR)forward simulation all aims at the singular and regular models,such as sandwich model,round cavity,square cavity,and so on,which are comparably simple.But as to the forward of curl interface underground or“v”figure complex model,it is difficult to realize.So it is important to forward the complex geoelectricity model.This paper takes two Maxwell’s vorticity equations as departure point,makes use of the principles of Yee’s space grid model theory and the basic principle finite difference time domain method,and deduces a GPR forward system of equation of two dimensional spaces.The Mur super absorbed boundary condition is adopted to solve the super strong reflection on the interceptive boundary when there is the forward simulation.And a self-made program is used to process forward simulation to two typical geoelectricity model.展开更多
基金supported by the Foundation of State Key Laboratory of Aerodynamics of China(No.SKLA-2024-KFKT-1-008)the National Natural Science Foundation of China(No.91952203)。
摘要This paper presents an efficient and automated Overset Grid Assembly(OGA)method for the structured grid,and investigates high-order interpolation methods for inter-grid boundaries with the cell-centered finite difference method.Four enhancements are introduced:a hybrid holecutting approach integrates the efficiency of approximate hole-cutting and the accuracy and robustness of direct-cutting,effectively addressing challenges such as small gaps and thin cuts;an improved implicit hole boundary optimization method,incorporating quality comparison,can significantly reduce donor search workloads;an improved implicit interpolation cell cancellation algorithm minimizes overlap regions,particularly beneficial for high-order interpolation with large stencils;an algorithm for identifying and eliminating islands without using wall distances,effectively removes islands.The OGA results of a multi-element airfoil,a circular array of cylinders,multiple spheres,and a wing-pylon-store configuration indicate that the proposed method would be a suitable selection for multi-body problems,even in the presence of small gaps and thin geometries.Additionally,for high-order interpolation at inter-grid boundaries,this study presents an optimized interpolation method designed to minimize spectral property errors.Numerical results indicate that for periodic problems frequently crossing inter-grid boundaries,the optimized interpolation is more accurate than classical Lagrange interpolation and would be a suitable selection.
基金funded by National Natural Science Foundation of China(Nos.12474441 and 51809208).
摘要Due to the complex and dynamic nature of multi-phase interfaces,accurately capturing interface evolution remains one of the key challenges in multi-phase flow simulations,particularly in modeling bubble rising.In this study,a fully Lagrangian method is developed by using the Generalized Finite Difference(GFD)scheme,which we refer to as Finite Difference Particle Method(FDPM),and the Continuum Surface Force(CSF)model to simulate bubble dynamics.In this framework,the fluid is represented by particles,and all partial differential terms in the Navier–Stokes equations are discretized into symmetric linear systems using the GFD scheme.Notably,the interface curvature required by the CSF model is computed directly via the Laplacian of the color function,rather than through the divergence of the unit normal vector.The bubble relaxation cases with various density ratios(up to 1000)are tested,revealing that the pressure distributions inside and outside the bubbles generally agree with theoretical predictions.Finally,simulations of rising bubbles with a high density ratio(1:1000)and Reynolds number of 25 demonstrate that the time evolution of the bubble’s center of mass by FDPM is consistent with results obtained by the Smoothed Particle Hydrodynamics(SPH)and the Finite Element Method(FEM)approaches.
基金the Iranian Nanotechnology Development Committee for supporting this researchthe University of Kashan under Grant No.1392194/7funded by the University of Kashan。
摘要In this study,the frequency and vibration responses of a sandwich micro-beam are derived based on the modified couple stress theory(MCST).The face sheets are made of pure aluminum,and a magneto-rheological(MR)core is used to control vibrations.The displacement fields are assumed based on the classical beam theory(CBT)and modified classical beam theories.Based on Hamilton's principle,the governing equations of motion are obtained.To solve these temporal equations,the finite difference method(FDM)with an optimal number of nodes is applied.The effects of various parameters,including viscoelastic properties,magnetic fields,aspect ratio,core-to-face-sheet thickness ratio,MR materials,face sheets,and material length-scale parameters,on the frequency and vibrational response are investigated.In the literature,the effects of different parameters on the frequency response function(FRF)or vibration response are considered.The results obtained from the vibration response and FRF using the FDM show that the viscoelastic property of the MR core causes settling time in the vibration response and a decrease in the excitation frequency of the FRF.Increasing the magnetic field has a negligible effect on the excitation frequency in the FRF,but it increases the vibration response and settling time.The piezoelectric face sheets raise the FRF and suppress the vibration response of the MR sandwich micro-beam compared with the aluminum counterpart.
摘要Against the backdrop of the digital economy becoming a core engine for highquality regional economic development and Shandong accelerating the construction of a digital province,this paper identifies the industrial life cycle of Shandong’s digital economy from 2011 to 2025 using the Logistic model.An evaluation index system is established covering four dimensions:digital infrastructure,digital industrialization,industrial digitalization,and digital governance.With the entropy weight method,it measures the digital economy development level of 16 prefecture-level cities in Shandong from 2020 to 2024 and analyzes its temporal and spatial evolution.The results show that Shandong’s digital economy is in the early growth stage,with a saturation value of 1,3986.552 billion yuan and projected growth peak in 2027.All cities achieved steady development,while the gap between leading and lagging cities widened slightly with an obvious Matthew effect.A stable three-tier spatial pattern has formed,featuring a layout of stronger east,weaker west,faster south,slower north.Industrial digitalization and digital governance serve as core driving forces,and the growth driver has shifted from infrastructure to industrial integration and technological innovation.Corresponding policy suggestions are put forward to support the balanced and high-quality development of Shandong’s digital economy.
基金supported by the National Natural Science Foundation of China(No.42277175)Guangxi Emergency Management Department 2024 Innovation and Technology Research Project,China(No.2024GXYJ006)+2 种基金Hunan Provincial Department of Natural Resources Geological Exploration Project,China(No.2023ZRBSHZ056)The First National Natural Disaster Comprehensive Risk Survey in Hunan Province,China(No.2022-70)Guizhou Provincial Major Scientific and Technological Program,China(No.2023-425).
摘要A method combining finite difference method(FDM)and k-means clustering algorithm which can determine the threshold of rock bridge generation is proposed.Jointed slope models with different joint coalescence coefficients(k)are constructed based on FDM.The rock bridge area was divided through k-means algorithm and the optimal number of clusters was determined by sum of squared errors(SSE)and elbow method.The influence of maximum principal stress and stress change rate as clustering indexes on the clustering results of rock bridges was compared by using Euclidean distance.The results show that using stress change rate as clustering index is more effective.When the joint coalescence coefficient is less than 0.6,there is no significant stress concentration in the middle area of adjacent joints,that is,no generation of rock bridge.In addition,the range of rock bridge is affected by the coalescence coefficient(k),the relative position of joints and the parameters of weak interlayer.
摘要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(τ2+hx4+hy4)is suggested,whereτ,hx,hy 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(τ4+hx4+hy4)is constructed.Finally,with a series of numerical experiments,the theoretical accuracy and computational efficiency of the above methods are further verified.
基金support provided by the National Natural Science Foundation of China(Grant Nos.22408040,62394344)China Postdoctoral Support Program(Grant No.GZC20230354)+2 种基金China Postdoctoral Science Foundation(Grant Nos.2023M740489,2025T180320)Liaoning Province Key Research and Development‘Unveiling and Commanding’Project(Grant No.2023JH1/10400087)Dalian Key Research and Development‘Unveiling and Commanding’Project(Grant No.2023JB11GX005).
摘要Soft measurement based on data-driven models is an important method to predict key variables in process industry due to low latency demand and economics costs.However,data-driven models cannot provide accurate prediction on a noisy data set with a small number of samples.In response to the challenge of noisy data and lack of samples,several data-mechanism hybrid driven methods are proposed to improve key variables prediction performances on the basis of three data-driven models including random forest,extreme gradient boosting,and artificial neural network.Simultaneously,the effectiveness of hybrid driven methods proposed is validated via two cases including benzene-toluene-xylene distillation and steam methane reforming process,where data sets feature different sample sizes and noise intensity.The comparison results show that the hybrid driven methods can improve the prediction accuracy to a certain extent.The degree of improvement depends on the noise intensity,sample size,and data-driven model selected.Under conditions of noise intensity at 10%–20%and sample size ranging from 100 to 400 in this work,after adopting the hybrid driven methods,the coefficient of determination for random forest,extreme gradient boosting,and artificial neural network can be improved by 0.3%–5.2%,0.6%–17.7%,and 0.1%–36.2%compared to corresponding data driven models.
摘要This study investigates the complex heat transfer dynamics inmultilayer bifacial photovoltaic(bPV)solar modules under spectrally resolved solar irradiation.A novel numericalmodel is developed to incorporate internal heat generation resulting from optical absorption,grounded in the physical equations governing light-matter interactions within the module’smultilayer structure.The model accounts for reflection and transmission at each interface between adjacent layers,as well as absorption within individual layers,using the wavelength-dependent dielectric properties of constituent materials.These properties are used to calculate the spectral reflectance,transmittance,and absorption coefficients,enabling precise quantification of internal heat sources from irradiance incidents on both the front and rear surfaces of the module.The study further examines the influence of irradiance reflection on thermal behavior,evaluates the thermal impact of various supporting materials placed beneath the module,and analyzes the role of albedo in modifying heat distribution.By incorporating spectrally resolved heat generation across each layer often simplified or omitted in conventional models,the proposed approach enhances physical accuracy.The transient heat equation is solved using a one-dimensional finite difference(FD)method to produce detailed temperature profiles under multiple operating scenarios,including Standard Test Conditions(STC),Bifacial Standard Test Conditions(BSTC),Normal Operating Cell Temperature(NOCT),and Bifacial NOCT(BNOCT).The results offer valuable insights into the interplay between optical and thermal phenomena in bifacial systems,informing the design and optimization of more efficient photovoltaic technologies.
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).
摘要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 National Natural Science Foundation of China(12273080).
摘要In response to the issue of fuzzy matching and association when optical observation data are matched with the orbital elements in a catalog database,this paper proposes a matching and association strategy based on the arcsegment difference method.First,a matching error threshold is set to match the observation data with the known catalog database.Second,the matching results for the same day are sorted on the basis of target identity and observation residuals.Different matching error thresholds and arc-segment dynamic association thresholds are then applied to categorize the observation residuals of the same target across different arc-segments,yielding matching results under various thresholds.Finally,the orbital residual is computed through orbit determination(OD),and the positional error is derived by comparing the OD results with the orbit track from the catalog database.The appropriate matching error threshold is then selected on the basis of these results,leading to the final matching and association of the fuzzy correlation data.Experimental results showed that the correct matching rate for data arc-segments is 92.34% when the matching error threshold is set to 720″,with the arc-segment difference method processing the results of an average matching rate of 97.62% within 8 days.The remaining 5.28% of the fuzzy correlation data are correctly matched and associated,enabling identification of orbital maneuver targets through further processing and analysis.This method substantially enhances the efficiency and accuracy of space target cataloging,offering robust technical support for dynamic maintenance of the space target database.
基金Supported by Shanxi Province Natural Science Research(202203021212249)Special/Youth Foundation of Taiyuan University of Technology(2022QN101)+3 种基金National Natural Science Foundation of China(12301556)Research Project Supported by Shanxi Scholarship Council of China(2021-029)International Cooperation Base and Platform Project of Shanxi Province(202104041101019)Basic Research Plan of Shanxi Province(202203021211129)。
摘要To enhance the computational efficiency of spatio-temporally discretized phase-field models,we present a high-speed solver specifically designed for the Poisson equations,a component frequently used in the numerical computation of such models.This efficient solver employs algorithms based on discrete cosine transformations(DCT)or discrete sine transformations(DST)and is not restricted by any spatio-temporal schemes.Our proposed methodology is appropriate for a variety of phase-field models and is especially efficient when combined with flow field systems.Meanwhile,this study has conducted an extensive numerical comparison and found that employing DCT and DST techniques not only yields results comparable to those obtained via the Multigrid(MG)method,a conventional approach used in the resolution of the Poisson equations,but also enhances computational efficiency by over 90%.
基金Projects(51308273,41372307,41272326) supported by the National Natural Science Foundation of ChinaProjects(2010(A)06-b) supported by Science and Technology Fund of Yunan Provincial Communication Department,China
摘要Based on some assumptions, the dynamic analysis model of anchorage system is established. The dynamic governing equation is expressed as finite difference format and programmed by using MATLAB language. Compared with theoretical method, the finite difference method has been verified to be feasible by a case study. It is found that under seismic loading, the dynamic response of anchorage system is synchronously fluctuated with the seismic vibration. The change of displacement amplitude of material points is slight, and comparatively speaking, the displacement amplitude of the outside point is a little larger than that of the inside point, which shows amplification effect of surface. While the axial force amplitude transforms considerably from the inside to the outside. It increases first and reaches the peak value in the intersection between the anchoring section and free section, then decreases slowly in the free section. When considering damping effect of anchorage system, the finite difference method can reflect the time attenuation characteristic better, and the calculating result would be safer and more reasonable than the dynamic steady-state theoretical method. What is more, the finite difference method can be applied to the dynamic response analysis of harmonic and seismic random vibration for all kinds of anchor, and hence has a broad application prospect.
摘要By using asymptotic method,we verify the existence on the slowly growing solutions to second order difference equations discussed by Ishizaki-Yanagihara’s Wiman-Valiron method and Ishizaki-Wen’s binomial series method.The classical problem on finding conditions on the polynomial coefficients Pj(z)(j=0,1,2)and F(z)to guarantee that all nontrivial solutions of complex second order difference equation P2(z)f(z+2)+P1(z)f(z+1)+P0(z)f(z)=F(z)has slowly growing solutions with order 1/2 is detected.
基金Project(Z110803)supported by the State Key Laboratory of Geomechanics and Geotechnical Engineering,ChinaProject(2008AA062303)supported by the National High Technology Research and Development Program of China
摘要A fast explicit finite difference method (FEFDM),derived from the differential equations of one-dimensional steady pipe flow,was presented for calculation of wellhead injection pressure.Recalculation with a traditional numerical method of the same equations corroborates well the reliability and rate of FEFDM.Moreover,a flow rate estimate method was developed for the project whose injection rate has not been clearly determined.A wellhead pressure regime determined by this method was successfully applied to the trial injection operations in Shihezi formation of Shenhua CCS Project,which is a good practice verification of FEFDM.At last,this method was used to evaluate the effect of friction and acceleration terms on the flow equation on the wellhead pressure.The result shows that for deep wellbore,the friction term can be omitted when flow rate is low and in a wide range of velocity the acceleration term can always be deleted.It is also shown that with flow rate increasing,the friction term can no longer be neglected.
基金supported by the National Natural Science Foundation of China (No.50805056)New Century Excellent Talents in University (No.NCET-09-0396)the Scientific Research Foundation for the Returned Overseas Chinese Scholars,Ministry of Education (2009)
摘要Thermal stress simulation can provide a scientific reference to eliminate defects such as crack,residual stress centralization and deformation etc.,caused by thermal stress during casting solidification.To study the thermal stress distribution during casting process,a unilateral thermal-stress coupling model was employed to simulate 3D casting stress using Finite Difference Method(FDM),namely all the traditional thermal-elastic-plastic equations are numerically and differentially discrete.A FDM/FDM numerical simulation system was developed to analyze temperature and stress fields during casting solidification process.Two practical verifications were carried out,and the results from simulation basically coincided with practical cases.The results indicated that the FDM/FDM stress simulation system can be used to simulate the formation of residual stress,and to predict the occurrence of hot tearing.Because heat transfer and stress analysis are all based on FDM,they can use the same FD model,which can avoid the matching process between different models,and hence reduce temperature-load transferring errors.This approach makes the simulation of fluid flow,heat transfer and stress analysis unify into one single model.
基金the National Natural Science Foundation of China
摘要A new compact finite difference-Fourier spectral hybrid method for solving the three dimensional incompressible Navier-Stokes equations is developed in the present paper. The fifth-order upwind compact finite difference schemes for the nonlinear convection terms in the physical space, and the sixth-order center compact schemes for the derivatives in spectral space are described, respectively. The fourth-order compact schemes in a single nine-point cell for solving the Helmholtz equations satisfied by the velocities and pressure in spectral space is derived and its preconditioned conjugate gradient iteration method is studied. The treatment of pressure boundary conditions and the three dimensional non-reflecting outflow boundary conditions are presented. Application to the vortex dislocation evolution in a three dimensional wake is also reported.
基金Project supported by the "100 Talents Project" of the Chinese Academy of Sciences and the Major Program of the National Natural Science Foundation of China (Grant No 10534040).
摘要In modelling elastic wave propagation in a porous medium, when the ratio between the fluid viscosity and the medium permeability is comparatively large, the stiffness problem of Blot's poroelastic equations will be encountered. In the paper, a partition method is developed to solve the stiffness problem with a staggered high-order finite-difference. The method splits the Biot equations into two systems. One is stiff, and solved analytically, the other is nonstiff, and solved numerically by using a high-order staggered-grid finite-difference scheme. The time step is determined by the staggered finite-difference algorithm in solving the nonstiff equations, thus a coarse time step may be employed. Therefore, the computation efficiency and computational stability are improved greatly. Also a perfect by matched layer technology is used in the split method as absorbing boundary conditions. The numerical results are compared with the analytical results and those obtained from the conventional staggered-grid finite-difference method in a homogeneous model, respectively. They are in good agreement with each other. Finally, a slightly more complex model is investigated and compared with related equivalent model to illustrate the good performance of the staggered-grid finite-difference scheme in the partition method.
基金Strategic Priority Research Program of the Chinese Academy of Sciences, No.XDA05010400 National Natural Science Foundation of China, No.41271547, No.41401644
摘要Factory-level data from 23 provinces and some national statistical data in cement manufacturing industry and socio-economies in 2012 are used to analyze the spatial distribution of exergy use for China's cement manufacturing industry by the Extended Exergy Accounting method. This method takes full account of the inclusion of energy and raw material supply and other external factors (capital, labor and environment) into a comprehensive resource cost assessment. The extended exergy consumption and its intensity quantitatively at the provincial levels of cement production were calculated and then the agglomeration level of exergy use at the regional level was also evaluated. Based on this analysis, their spatial difference in size and efficiency of exergy use at the provincial level were identified. Moreover, their regional characteristics were revealed. Some important results could be drawn as follows. First, the invisible social cost accounted for 1/10 of the total exergy use in cement manufacturing industry, while the energy element shared about 9/10. Second, the gross distribution of exergy use in China's cement manufacturing industry was mainly concentrated in the eastern region like Anhui and Shandong provinces, and in the western region like Sichuan province. In terms of exergy use, the coal and electricity were the highest of energy costs in the eastern region, whereas the cost of capital, labor and external environmental factors highlighted the invisible social cost for cement production in the central and western regions to some extent. Third, the efficiency distribution of exergy use in China's cement manufacturing industry illustrated an incremental feature from west to east, especially for the energy, labor and capital efficiencies. An evaluation on the environmental efficiency indicated that provinces or regions like Tibet, Xinjiang, Inner Mongolia and Shanxi have undertaken much higher environmental costs. Fourth, the 23 provinces could be classified into eight groups by the Euclidean distance model using the gross and efficiency results of exergy use. Fifth, the high industry concentration degree is the main driving factor of exergy efficiency improvement for cement manufacturing industry in China.
摘要An explicit finite element-finite difference method for analyzing the effects of two-dimensional visco-elastic localtopography on earthquake ground motion is prOPosed in this paper. In the method, at first, the finite elementdiscrete model is formed by using the artificial boundary and finite element method, and the dynamic equationsof local nodes in the discrete model are obtained according to the theory of the special finite element method similar to the finite difference method, and then the explicit step-by-step integration formulas are presented by usingthe explicit difference method for solving the visco-elastic dynamic equation and Generalized Multi-transmittingBoundary. The method has the advantages of saving computing time and computer memory space, and it is suitable for any case of topography and has high computing accuracy and good computing stability.
基金Project(50099620)supported by the National Natural Science Foundation of China
摘要The ground penetrating radar(GPR)forward simulation all aims at the singular and regular models,such as sandwich model,round cavity,square cavity,and so on,which are comparably simple.But as to the forward of curl interface underground or“v”figure complex model,it is difficult to realize.So it is important to forward the complex geoelectricity model.This paper takes two Maxwell’s vorticity equations as departure point,makes use of the principles of Yee’s space grid model theory and the basic principle finite difference time domain method,and deduces a GPR forward system of equation of two dimensional spaces.The Mur super absorbed boundary condition is adopted to solve the super strong reflection on the interceptive boundary when there is the forward simulation.And a self-made program is used to process forward simulation to two typical geoelectricity model.