In this paper,we first establish a new fractional magnetohydrodynamic(MHD)coupled flow and heat transfer model for a generalized second-grade fluid.This coupled model consists of a fractional momentum equation and a h...In this paper,we first establish a new fractional magnetohydrodynamic(MHD)coupled flow and heat transfer model for a generalized second-grade fluid.This coupled model consists of a fractional momentum equation and a heat conduction equation with a generalized form of Fourier law.The second-order fractional backward difference formula is applied to the temporal discretization and the Legendre spectral method is used for the spatial discretization.The fully discrete scheme is proved to be stable and convergent with an accuracy of O(τ^(2)+N-r),whereτis the time step-size and N is the polynomial degree.To reduce the memory requirements and computational cost,a fast method is developed,which is based on a globally uniform approximation of the trapezoidal rule for integrals on the real line.The strict convergence of the numerical scheme with this fast method is proved.We present the results of several numerical experiments to verify the effectiveness of the proposed method.Finally,we simulate the unsteady fractional MHD flow and heat transfer of the generalized second-grade fluid through a porous medium.The effects of the relevant parameters on the velocity and temperature are presented and analyzed in detail.展开更多
Extensive land use will cause many environmental problems.It is an urgent task to improve land use efficiency and optimize land use patterns.In recent years,due to the flow decrease,the Guanzhong Basin in Shaanxi Prov...Extensive land use will cause many environmental problems.It is an urgent task to improve land use efficiency and optimize land use patterns.In recent years,due to the flow decrease,the Guanzhong Basin in Shaanxi Province is confronted with the problem of insufficient water resources reserve.Based on the Coupled Ground-Water and Surface-Water Flow Model(GSFLOW),this paper evaluates the response of water resources in the basin to changes in land use patterns,optimizes the land use pattern,improves the ecological and economic benefits,and the efficiency of various spatial development,providing a reference for ecological protection and high-quality development of the Yellow River Basin.The research shows that the land use pattern in the Guanzhong Basin should be further optimized.Under the condition of considering ecological and economic development,the percentage change of the optimum area of farmland,forest,grassland,water area,and urban area compared with the current land use area ratio is+2.3,+2.4,-6.1,+0.2,and+1.6,respectively.The economic and ecological value of land increases by14.1%and 3.1%,respectively,and the number of water resources can increase by 2.5%.展开更多
Heat exchanger systems(HXSs)or heat recovery steam generators(HRSGs)are commonly used in 100 kW to 50 MW combined cooling,heating,and power(CCHP)systems.Power flow coupling(PFC)is found in HXSs and is complex for rese...Heat exchanger systems(HXSs)or heat recovery steam generators(HRSGs)are commonly used in 100 kW to 50 MW combined cooling,heating,and power(CCHP)systems.Power flow coupling(PFC)is found in HXSs and is complex for researchers to quantify.This could possibly mislead the dispatch schedule and result in the inaccurate dispatch.PFC is caused by the inlet and outlet temperatures of each component,gas flow pressure variation,conductive medium flow rate,and atmosphere condition variation.In this paper,the expression of PFC is built by using quadratic functions to fit the non!inearit>of thermal dynamics.While fitting the model,the environmental condition needs prediction,which is calculated using phase space reconstruction(PSR)Kalman filter.In order to solve the complex quadratic dispatch model,a hybrid following electricity load(FEL)and following thermal load(FTL)mode for reducing the dimension of dispatch model,and a feasible zone analysis(FZA)method are proposed.As a result,the PFC problem of CCHP system is solved,and the dispatch cost,investment cost,and the maximum power requirements are optimized.In this paper,a case in Jinan,China is studied.The PFC model is proven to be more precise and accurate compared with traditional models.展开更多
基金supported by the Project of the National Key R&D Program(Grant No.2021YFA1000202)National Natural Science Foundation of China(Grant Nos.12120101001,12001326 and 12171283)+2 种基金Natural Science Foundation of Shandong Province(Grant Nos.ZR2021ZD03,ZR2020QA032 and ZR2019ZD42)China Postdoctoral Science Foundation(Grant Nos.BX20190191 and 2020M672038)the Startup Fund from Shandong University(Grant No.11140082063130)。
文摘In this paper,we first establish a new fractional magnetohydrodynamic(MHD)coupled flow and heat transfer model for a generalized second-grade fluid.This coupled model consists of a fractional momentum equation and a heat conduction equation with a generalized form of Fourier law.The second-order fractional backward difference formula is applied to the temporal discretization and the Legendre spectral method is used for the spatial discretization.The fully discrete scheme is proved to be stable and convergent with an accuracy of O(τ^(2)+N-r),whereτis the time step-size and N is the polynomial degree.To reduce the memory requirements and computational cost,a fast method is developed,which is based on a globally uniform approximation of the trapezoidal rule for integrals on the real line.The strict convergence of the numerical scheme with this fast method is proved.We present the results of several numerical experiments to verify the effectiveness of the proposed method.Finally,we simulate the unsteady fractional MHD flow and heat transfer of the generalized second-grade fluid through a porous medium.The effects of the relevant parameters on the velocity and temperature are presented and analyzed in detail.
基金jointly supported by the National Natural Science Foundation of China(41702280)the projects of the China Geology Survey(DD20221754 and DD20190333)。
文摘Extensive land use will cause many environmental problems.It is an urgent task to improve land use efficiency and optimize land use patterns.In recent years,due to the flow decrease,the Guanzhong Basin in Shaanxi Province is confronted with the problem of insufficient water resources reserve.Based on the Coupled Ground-Water and Surface-Water Flow Model(GSFLOW),this paper evaluates the response of water resources in the basin to changes in land use patterns,optimizes the land use pattern,improves the ecological and economic benefits,and the efficiency of various spatial development,providing a reference for ecological protection and high-quality development of the Yellow River Basin.The research shows that the land use pattern in the Guanzhong Basin should be further optimized.Under the condition of considering ecological and economic development,the percentage change of the optimum area of farmland,forest,grassland,water area,and urban area compared with the current land use area ratio is+2.3,+2.4,-6.1,+0.2,and+1.6,respectively.The economic and ecological value of land increases by14.1%and 3.1%,respectively,and the number of water resources can increase by 2.5%.
基金the National Natural Science Foundation of China(No.61733010).
文摘Heat exchanger systems(HXSs)or heat recovery steam generators(HRSGs)are commonly used in 100 kW to 50 MW combined cooling,heating,and power(CCHP)systems.Power flow coupling(PFC)is found in HXSs and is complex for researchers to quantify.This could possibly mislead the dispatch schedule and result in the inaccurate dispatch.PFC is caused by the inlet and outlet temperatures of each component,gas flow pressure variation,conductive medium flow rate,and atmosphere condition variation.In this paper,the expression of PFC is built by using quadratic functions to fit the non!inearit>of thermal dynamics.While fitting the model,the environmental condition needs prediction,which is calculated using phase space reconstruction(PSR)Kalman filter.In order to solve the complex quadratic dispatch model,a hybrid following electricity load(FEL)and following thermal load(FTL)mode for reducing the dimension of dispatch model,and a feasible zone analysis(FZA)method are proposed.As a result,the PFC problem of CCHP system is solved,and the dispatch cost,investment cost,and the maximum power requirements are optimized.In this paper,a case in Jinan,China is studied.The PFC model is proven to be more precise and accurate compared with traditional models.