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Analysis of Extended Fisher-Kolmogorov Equation in 2D Utilizing the Generalized Finite Difference Method with Supplementary Nodes
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作者 Bingrui Ju Wenxiang Sun +1 位作者 Wenzhen Qu Yan Gu 《Computer Modeling in Engineering & Sciences》 SCIE EI 2024年第10期267-280,共14页
In this study,we propose an efficient numerical framework to attain the solution of the extended Fisher-Kolmogorov(EFK)problem.The temporal derivative in the EFK equation is approximated by utilizing the Crank-Nicolso... In this study,we propose an efficient numerical framework to attain the solution of the extended Fisher-Kolmogorov(EFK)problem.The temporal derivative in the EFK equation is approximated by utilizing the Crank-Nicolson scheme.Following temporal discretization,the generalized finite difference method(GFDM)with supplementary nodes is utilized to address the nonlinear boundary value problems at each time node.These supplementary nodes are distributed along the boundary to match the number of boundary nodes.By incorporating supplementary nodes,the resulting nonlinear algebraic equations can effectively satisfy the governing equation and boundary conditions of the EFK equation.To demonstrate the efficacy of our approach,we present three numerical examples showcasing its performance in solving this nonlinear problem. 展开更多
关键词 Generalized finite difference method nonlinear extended Fisher-Kolmogorov equation Crank-Nicolson scheme
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Stability and accuracy of central difference method for real-time dynamic substructure testing considering mass participation coefficient
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作者 Zheng Lichang Xu Guoshan +3 位作者 Yang Ge Wang Zhen Yang Kaibo Zheng Zhenyun 《Earthquake Engineering and Engineering Vibration》 SCIE EI CSCD 2024年第3期625-636,共12页
For real-time dynamic substructure testing(RTDST),the influence of the inertia force of fluid specimens on the stability and accuracy of the integration algorithms has never been investigated.Therefore,this study prop... For real-time dynamic substructure testing(RTDST),the influence of the inertia force of fluid specimens on the stability and accuracy of the integration algorithms has never been investigated.Therefore,this study proposes to investigate the stability and accuracy of the central difference method(CDM)for RTDST considering the specimen mass participation coefficient.First,the theory of the CDM for RTDST is presented.Next,the stability and accuracy of the CDM for RTDST considering the specimen mass participation coefficient are investigated.Finally,numerical simulations and experimental tests are conducted for verifying the effectiveness of the method.The study indicates that the stability of the algorithm is affected by the mass participation coefficient of the specimen,and the stability limit first increases and then decreases as the mass participation coefficient increases.In most cases,the mass participation coefficient will increase the stability limit of the algorithm,but in specific circumstances,the algorithm may lose its stability.The stability and accuracy of the CDM considering the mass participation coefficient are verified by numerical simulations and experimental tests on a three-story frame structure with a tuned liquid damper. 展开更多
关键词 real-time dynamic substructure testing central difference method STABILITY mass participation coefficient tuned liquid damper
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Discussion on the application prospect of the transient electromagnetic method based on the dual launcher and mine advanced detection
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作者 Zhen Yang Huizhou Liu +5 位作者 Shengqing Wang Yu Cao Ya Dong Chenghu Niu Weiwen Song Guoxin Xie 《World Journal of Condensed Matter Physics》 CAS 2024年第1期21-33,共13页
The dual transmitter implements the equivalent anti-magnetic flux transient electromagnetic method, which can effectively reduce the scope of the transient electromagnetic detection blind area. However, this method is... The dual transmitter implements the equivalent anti-magnetic flux transient electromagnetic method, which can effectively reduce the scope of the transient electromagnetic detection blind area. However, this method is rarely reported in the detection of pipelines in urban geophysical exploration and the application of coal mines. Based on this, this paper realizes the equivalent anti-magnetic flux transient electromagnetic method based on the dual launcher. The suppression effect of this method on the blind area is analyzed by physical simulation. And the detection experiment of underground pipelines is carried out outdoors. The results show that the dual launcher can significantly reduce the turn-off time, thereby effectively reducing the impact of the blind area on the detection results, and the pipeline detection results verify the device’s effectiveness. Finally, based on the ground experimental results, the application prospect of mine advanced detection is discussed. Compared with other detection fields, the formation of blind areas is mainly caused by the equipment. If the dual launcher can be used to reduce the blind area, the accuracy of advanced detection can be improved more effectively. The above research results are of great significance for improving the detection accuracy of the underground transient electromagnetic method. 展开更多
关键词 A dual Launcher Physical Simulation Transient Electromagnetic method Mine Geophysical Prospecting Detection Blind Area Application Prospect
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Combined Estimation of Vehicle Dynamic State and Inertial Parameter for Electric Vehicles Based on Dual Central Difference Kalman Filter Method
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作者 Xianjian Jin Junpeng Yang +3 位作者 Liwei Xu Chongfeng Wei Zhaoran Wang Guodong Yin 《Chinese Journal of Mechanical Engineering》 SCIE EI CAS CSCD 2023年第4期339-354,共16页
Distributed drive electric vehicles(DDEVs)possess great advantages in the viewpoint of fuel consumption,environment protection and traffic mobility.Whereas the effects of inertial parameter variation in DDEV control s... Distributed drive electric vehicles(DDEVs)possess great advantages in the viewpoint of fuel consumption,environment protection and traffic mobility.Whereas the effects of inertial parameter variation in DDEV control system become much more pronounced due to the drastic reduction of vehicle weights and body size,and inertial parameter has seldom been tackled and systematically estimated.This paper presents a dual central difference Kalman filter(DCDKF)where two Kalman filters run in parallel to simultaneously estimate vehicle different dynamic states and inertial parameters,such as vehicle sideslip angle,vehicle mass,vehicle yaw moment of inertia,the distance from the front axle to centre of gravity.The proposed estimation method only integrates and utilizes real-time measurements of hub torque information and other in-vehicle sensors from standard DDEVs.The four-wheel nonlinear vehicle dynamics estimation model considering payload variations,Pacejka tire model,wheel and motor dynamics model is developed,the observability of the DCDKF observer is analysed and derived via Lie derivative and differential geometry theory.To address system nonlinearities in vehicle dynamics estimation,the DCDKF and dual extended Kalman filter(DEKF)are also investigated and compared.Simulation with various maneuvers are carried out to verify the effectiveness of the proposed method using Matlab/Simulink-CarsimR.The results show that the proposed DCDKF method can effectively estimate vehicle dynamic states and inertial parameters despite the existence of payload variations and variable driving conditions.This research provides a boot-strapping procedure which can performs optimal estimation to estimate simultaneously vehicle system state and inertial parameter with high accuracy and real-time ability. 展开更多
关键词 Distributed drive Electric vehicle State observation Inertial parameter dual central difference Kalman filter
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High-Order Bound-Preserving Finite Difference Methods for Multispecies and Multireaction Detonations 被引量:1
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作者 Jie Du Yang Yang 《Communications on Applied Mathematics and Computation》 2023年第1期31-63,共33页
In this paper,we apply high-order finite difference(FD)schemes for multispecies and multireaction detonations(MMD).In MMD,the density and pressure are positive and the mass fraction of the ith species in the chemical ... In this paper,we apply high-order finite difference(FD)schemes for multispecies and multireaction detonations(MMD).In MMD,the density and pressure are positive and the mass fraction of the ith species in the chemical reaction,say zi,is between 0 and 1,withΣz_(i)=1.Due to the lack of maximum-principle,most of the previous bound-preserving technique cannot be applied directly.To preserve those bounds,we will use the positivity-preserving technique to all the zi'is and enforceΣz_(i)=1 by constructing conservative schemes,thanks to conservative time integrations and consistent numerical fluxes in the system.Moreover,detonation is an extreme singular mode of flame propagation in premixed gas,and the model contains a significant stiff source.It is well known that for hyperbolic equations with stiff source,the transition points in the numerical approximations near the shocks may trigger spurious shock speed,leading to wrong shock position.Intuitively,the high-order weighted essentially non-oscillatory(WENO)scheme,which can suppress oscillations near the discontinuities,would be a good choice for spatial discretization.However,with the nonlinear weights,the numerical fluxes are no longer“consistent”,leading to nonconservative numerical schemes and the bound-preserving technique does not work.Numerical experiments demonstrate that,without further numerical techniques such as subcell resolutions,the conservative FD method with linear weights can yield better numerical approximations than the nonconservative WENO scheme. 展开更多
关键词 Weighted essentially non-oscillatory scheme Finite difference method Stiff source DETONATIONS Bound-preserving CONSERVATIVE
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Efficient Finite Difference/Spectral Method for the Time Fractional Ito Equation Using Fast Fourier Transform Technic
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作者 Dakang Cen Zhibo Wang Seakweng Vong 《Communications on Applied Mathematics and Computation》 EI 2023年第4期1591-1600,共10页
A finite difference/spectral scheme is proposed for the time fractional Ito equation.The mass conservation and stability of the numerical solution are deduced by the energy method in the L^(2)norm form.To reduce the c... A finite difference/spectral scheme is proposed for the time fractional Ito equation.The mass conservation and stability of the numerical solution are deduced by the energy method in the L^(2)norm form.To reduce the computation costs,the fast Fourier transform technic is applied to a pair of equivalent coupled differential equations.The effectiveness of the proposed algorithm is verified by the first numerical example.The mass conservation property and stability statement are confirmed by two other numerical examples. 展开更多
关键词 Time fractional Ito equation Finite difference method Spectral method STABILITY
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Numerical Study by Imposing the Finite Difference Method for Unsteady Casson Fluid Flow with Heat Flux
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作者 Ali H. Tedjani 《Journal of Applied Mathematics and Physics》 2023年第12期3826-3839,共14页
This article presents an investigation into the flow and heat transfer characteristics of an impermeable stretching sheet subjected to Magnetohydrodynamic Casson fluid. The study considers the influence of slip veloci... This article presents an investigation into the flow and heat transfer characteristics of an impermeable stretching sheet subjected to Magnetohydrodynamic Casson fluid. The study considers the influence of slip velocity, thermal radiation conditions, and heat flux. The investigation is conducted employing a robust numerical method that accounts for the impact of thermal radiation. This category of fluid is apt for characterizing the movement of blood within an industrial artery, where the flow can be regulated by a material designed to manage it. The resolution of the ensuing system of ordinary differential equations (ODEs), representing the described problem, is accomplished through the application of the finite difference method. The examination of flow and heat transfer characteristics, including aspects such as unsteadiness, radiation parameter, slip velocity, Casson parameter, and Prandtl number, is explored and visually presented through tables and graphs to illustrate their impact. On the stretching sheet, calculations, and descriptions of the local skin-friction coefficient and the local Nusselt number are conducted. In conclusion, the findings indicate that the proposed method serves as a straightforward and efficient tool for exploring the solutions of fluid models of this kind. 展开更多
关键词 Casson Model Unsteady Stretching Sheet Variable Heat Flux MHD Slip Impacts Thermal Radiation Finite difference method
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按病种付费对中医优势病种住院费用的影响研究——基于PSM-DID法 被引量:1
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作者 岳铭坤 李凯 +3 位作者 黄娜 李青峰 杨土保 周良荣 《卫生经济研究》 北大核心 2024年第3期62-64,共3页
目的:分析按病种付费对中医优势病种住院费用的影响,为中医按病种付费改革提供参考。方法:采用某中医医院实施按病种付费的高位肛瘘患者住院费用数据,经倾向得分匹配法(PSM)匹配后,进行双重差分(DID)回归分析,探讨按病种付费对中医优势... 目的:分析按病种付费对中医优势病种住院费用的影响,为中医按病种付费改革提供参考。方法:采用某中医医院实施按病种付费的高位肛瘘患者住院费用数据,经倾向得分匹配法(PSM)匹配后,进行双重差分(DID)回归分析,探讨按病种付费对中医优势病种住院费用的影响。结果:实施按病种付费后,高位肛瘘患者住院总费用下降了1067.63元、自付费用下降了656.66元、住院天数缩短了5.54天、西药费增长了406.55元、中成药费下降了126.80元。结论:在中医优势病种按病种付费过程中,应加强医保监督,持续完善、更新中医信息系统,扩大按病种付费的中医优势病种范围,突出中医临床路径优势,促进中医药传承创新发展。 展开更多
关键词 按病种付费 中医优势病种 住院费用 双重差分 倾向得分匹配法
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Comparison of fish communities using environmental DNA metabarcoding and capture methods in a plateau Erhai Lake,China
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作者 Hong CHEN Wanchao HE +4 位作者 Fenge YANG Li LIAO Chengjie YIN Yushun CHEN Longgen GUO 《Journal of Oceanology and Limnology》 SCIE CAS CSCD 2024年第5期1597-1608,共12页
Environmental DNA(eDNA)has been used as an important tool for fish diversity analysis,which can greatly solve the problems in traditional survey methodology.However,little work has been done on the actual monitoring a... Environmental DNA(eDNA)has been used as an important tool for fish diversity analysis,which can greatly solve the problems in traditional survey methodology.However,little work has been done on the actual monitoring accuracy of eDNA.In this study,we analyzed the current status of fish resources in Erhai Lake in Yunnan,SW China,by dividing the lake into three sectors according to habitat differences,and compared the results of eDNA and traditional capture methods to investigate the shortcomings of the current analysis of eDNA results.A total of 27 fish species were detected by eDNA and traditional capture methods,including 20 and 19 fish species,respectively,and additional differences in fish composition between the two methods.The alpha diversity showed higher fish abundance and lower fish diversity by eDNA method compared to the traditional capture method,demonstrating that eDNA was not superior for use in fish diversity analysis.Fish community similarity analysis showed that community differences were generally significant for eDNA(P<0.05).RDA analysis indicated that environmental factors did not significantly affect fish communities monitored by the eDNA method.However,water temperature,aquatic plants,and water depth had significant(P<0.05)effects on fish communities in the traditional capture method,suggesting that eDNA results are insensitive to the effects of environmental factors.Our results illustrate the effectiveness of eDNA in fish identification and the issues in quantification compared to traditional capture methods.Therefore,combining eDNA with traditional methods is a more effective method for analyzing eDNA metabarcoding,following which the protocols of both quantitative methods can be designed to explore the regularity of eDNA quantification. 展开更多
关键词 environmental DNA traditional capture method fish communities habitat differences Erhai Lake
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Scattering of Water Waves by Dual Symmetric Inclined Floating Porous Barriers Using the DBEM
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作者 WANG Li-xian DENG Yan-wen +1 位作者 YE Yang-sha DENG Zheng-zhi 《China Ocean Engineering》 SCIE EI CSCD 2024年第1期156-168,共13页
The scattering of normally incident water waves by two surface-piercing inclined perforated barriers in water with a uniform finite depth is investigated within the framework of linear water wave theory.Considering th... The scattering of normally incident water waves by two surface-piercing inclined perforated barriers in water with a uniform finite depth is investigated within the framework of linear water wave theory.Considering that thin barriers are zero-thickness,a novel numerical method involving the the coupling of the dual boundary element method(DBEM)with damping layers is applied.In order to effectively damp out the reflected waves,two damping layers,instead of pseudoboundaries are implemented near the two side boundaries of the computational domain.Thus,the modified linearized free surface boundary conditions are formulated and used for solving both the ordinary boundary integral equation as well as the hypersingular boundary integral equation for degenerate boundaries.The newly developed numerical method is validated against analytical methods using the matched eigenfunction expansion method for the special case of two vertical barriers or the inclined angle to the vertical being zero.The influence of the length of the two damping layers has been discussed.Moreover,these findings are also validated against previous results for several cases.After validation,the numerical results for the reflection coefficient,transmission coefficient and dissipation coefficient are obtained by varying the inclination angle and porosity-effect parameter.The effects of both the inclination angle and the porosity on the amplitudes of wave forces acting on both the front and rear barriers are also investigated.It is found that the effect of the inclination angle mainly shifts the location of the extremal values of the reflection and the transmission coefficients.Additionally,a moderate value of the porosity-parameter is quite effective at dissipating wave energy and mitigating the wave loads on dual barriers. 展开更多
关键词 dual boundary element method inclined perforated floating breakwater reflection coefficient transmission coefficient damping layer
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Finite Difference-Peridynamic Differential Operator for Solving Transient Heat Conduction Problems
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作者 Chunlei Ruan Cengceng Dong +2 位作者 Zeyue Zhang Boyu Chen Zhijun Liu 《Computer Modeling in Engineering & Sciences》 SCIE EI 2024年第9期2707-2728,共22页
Transient heat conduction problems widely exist in engineering.In previous work on the peridynamic differential operator(PDDO)method for solving such problems,both time and spatial derivatives were discretized using t... Transient heat conduction problems widely exist in engineering.In previous work on the peridynamic differential operator(PDDO)method for solving such problems,both time and spatial derivatives were discretized using the PDDO method,resulting in increased complexity and programming difficulty.In this work,the forward difference formula,the backward difference formula,and the centered difference formula are used to discretize the time derivative,while the PDDO method is used to discretize the spatial derivative.Three new schemes for solving transient heat conduction equations have been developed,namely,the forward-in-time and PDDO in space(FT-PDDO)scheme,the backward-in-time and PDDO in space(BT-PDDO)scheme,and the central-in-time and PDDO in space(CT-PDDO)scheme.The stability and convergence of these schemes are analyzed using the Fourier method and Taylor’s theorem.Results show that the FT-PDDO scheme is conditionally stable,whereas the BT-PDDO and CT-PDDO schemes are unconditionally stable.The stability conditions for the FT-PDDO scheme are less stringent than those of the explicit finite element method and explicit finite difference method.The convergence rate in space for these three methods is two.These constructed schemes are applied to solve one-dimensional and two-dimensional transient heat conduction problems.The accuracy and validity of the schemes are verified by comparison with analytical solutions. 展开更多
关键词 Peridynamic differential operator finite difference method STABILITY transient heat conduction problem
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Stability and Time-Step Constraints of Implicit-Explicit Runge-Kutta Methods for the Linearized Korteweg-de Vries Equation
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作者 Joseph Hunter Zheng Sun Yulong Xing 《Communications on Applied Mathematics and Computation》 EI 2024年第1期658-687,共30页
This paper provides a study on the stability and time-step constraints of solving the linearized Korteweg-de Vries(KdV)equation,using implicit-explicit(IMEX)Runge-Kutta(RK)time integration methods combined with either... This paper provides a study on the stability and time-step constraints of solving the linearized Korteweg-de Vries(KdV)equation,using implicit-explicit(IMEX)Runge-Kutta(RK)time integration methods combined with either finite difference(FD)or local discontinuous Galerkin(DG)spatial discretization.We analyze the stability of the fully discrete scheme,on a uniform mesh with periodic boundary conditions,using the Fourier method.For the linearized KdV equation,the IMEX schemes are stable under the standard Courant-Friedrichs-Lewy(CFL)conditionτ≤λh.Here,λis the CFL number,τis the time-step size,and h is the spatial mesh size.We study several IMEX schemes and characterize their CFL number as a function ofθ=d/h^(2)with d being the dispersion coefficient,which leads to several interesting observations.We also investigate the asymptotic behaviors of the CFL number for sufficiently refined meshes and derive the necessary conditions for the asymptotic stability of the IMEX-RK methods.Some numerical experiments are provided in the paper to illustrate the performance of IMEX methods under different time-step constraints. 展开更多
关键词 Linearized Korteweg-de Vries(KdV)equation Implicit-explicit(IMEX)Runge-Kutta(RK)method STABILITY Courant-Friedrichs-Lewy(CFL)condition Finite difference(FD)method Local discontinuous Galerkin(DG)method
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A Hybrid ESA-CCD Method for Variable-Order Time-Fractional Diffusion Equations
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作者 Xiaoxue Lu Chunhua Zhang +1 位作者 Huiling Xue Bowen Zhong 《Journal of Applied Mathematics and Physics》 2024年第9期3053-3065,共13页
In this paper, we study the solutions for variable-order time-fractional diffusion equations. A three-point combined compact difference (CCD) method is used to discretize the spatial variables to achieve sixth-order a... In this paper, we study the solutions for variable-order time-fractional diffusion equations. A three-point combined compact difference (CCD) method is used to discretize the spatial variables to achieve sixth-order accuracy, while the exponential-sum-approximation (ESA) is used to approximate the variable-order Caputo fractional derivative in the temporal direction, and a novel spatial sixth-order hybrid ESA-CCD method is implemented successfully. Finally, the accuracy of the proposed method is verified by numerical experiments. 展开更多
关键词 Variable-Order Caputo Fractional Derivative Combined Compact difference method Exponential-Sum-Approximation
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自贸试验区对产业结构升级的影响——基于SDID的验证
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作者 罗舟 《湖南大学学报(社会科学版)》 CSSCI 北大核心 2024年第4期75-82,共8页
在解析合成双重差分法(SDID)的基本思想与相关特性基础上,构造产业结构升级指数,从区域异质性视角研究了自贸试验区对产业结构升级的影响,并利用双重差分法(DID)进行稳健性检验,强化了研究结论的可靠性。基于研究结果,提出要以制度创新... 在解析合成双重差分法(SDID)的基本思想与相关特性基础上,构造产业结构升级指数,从区域异质性视角研究了自贸试验区对产业结构升级的影响,并利用双重差分法(DID)进行稳健性检验,强化了研究结论的可靠性。基于研究结果,提出要以制度创新为抓手,通过“以改革促开放,以开放倒逼改革”,加快培育国际产业竞争新优势;要立足地区优势与特色,进一步优化区域产业分工,实现差异化发展;要深化区域战略融合,通过内外联动与战略协同强化产业发展韧性。 展开更多
关键词 自贸试验区 产业结构 合成双重差分法 区域异质性
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双循环背景下全国统一大市场建设对贸易成本的影响效应研究——基于双重差分法(DID)的检验
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作者 黄蕊 沈妍 姚保帅 《中国商论》 2024年第10期12-16,共5页
当前,经济转型迈向新时代,双循环发展成为我国应对国际挑战的关键。在此背景下,全国统一大市场建设作为双循环战略的核心,成为深化内循环经济的关键一步。本文以双循环背景下全国统一大市场建设对贸易成本的影响为主题,利用2010—2021... 当前,经济转型迈向新时代,双循环发展成为我国应对国际挑战的关键。在此背景下,全国统一大市场建设作为双循环战略的核心,成为深化内循环经济的关键一步。本文以双循环背景下全国统一大市场建设对贸易成本的影响为主题,利用2010—2021年的面板数据综合测度各地区贸易成本,并采用双重差分(DID)模型进行分析,旨在深入研究全国统一大市场建设对地区贸易成本的实质性影响。本文通过构建双重差分(DID)模型,具体关注生产成本、物流成本、信息流通效率和资金流动灵活性等方面的变化,依据模型估计结果,全国统一大市场建设对减少地区贸易成本有着显著的影响效应,且具有稳健性,这不仅有助于全面理解全国统一大市场建设对我国贸易成本的影响机制,还将为政策制定提供科学依据,为双循环战略的有效实施、经济高质量发展提供具体策略建议,以供参考。 展开更多
关键词 双循环格局 全国统一大市场建设 双重差分(did)模型 地区贸易成本 信息流通效率
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中央环保督察对城市空气质量改善的政策效用评估——基于DID双重差分法分析
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作者 张珺 《佛山科学技术学院学报(自然科学版)》 CAS 2024年第4期57-63,共7页
使用2012-2022年中国220个地级市的PM2.5、PM10、NO_(2)、SO_(2),的年均浓度值作为被解释变量,以是否为污染防治重点城市划分试验组与对照组,利用双重差分法检验中央环保督察对城市空气质量的影响,并通过倾向得分匹配检验分析结果的稳... 使用2012-2022年中国220个地级市的PM2.5、PM10、NO_(2)、SO_(2),的年均浓度值作为被解释变量,以是否为污染防治重点城市划分试验组与对照组,利用双重差分法检验中央环保督察对城市空气质量的影响,并通过倾向得分匹配检验分析结果的稳定性。研究发现:中央环保督察可以显著降低污染防治重点城市的PM10、SO_(2)和PM2.5的年均排放浓度,减少各项污染物排放量,改善城市空气质量。建议因地制宜开展环境治理工作,同时根据每个城市的实际情况确定督察工作的重点,对不同地区确定不同的空气环境治理目标。 展开更多
关键词 中央环保督察 空气质量 双重差分
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Integrated interpretation of dual frequency induced polarization measurement based on wavelet analysis and metal factor methods 被引量:2
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作者 韩世礼 张术根 +2 位作者 柳建新 胡厚继 张文山 《Transactions of Nonferrous Metals Society of China》 SCIE EI CAS CSCD 2013年第5期1465-1471,共7页
In mineral exploration, the apparent resistivity and apparent frequency (or apparent polarizability) parameters of induced polarization method are commonly utilized to describe the induced polarization anomaly. When... In mineral exploration, the apparent resistivity and apparent frequency (or apparent polarizability) parameters of induced polarization method are commonly utilized to describe the induced polarization anomaly. When the target geology structure is significantly complicated, these parameters would fail to reflect the nature of the anomaly source, and wrong conclusions may be obtained. A wavelet approach and a metal factor method were used to comprehensively interpret the induced polarization anomaly of complex geologic bodies in the Adi Bladia mine. Db5 wavelet basis was used to conduct two-scale decomposition and reconstruction, which effectively suppress the noise interference of greenschist facies regional metamorphism and magma intrusion, making energy concentrated and boundary problem unobservable. On the basis of that, the ore-induced anomaly was effectively extracted by the metal factor method. 展开更多
关键词 dual frequency induced polarization method wavelet analysis metal factor Arabian-Nubian shield volcanogenic massive sulfide deposit
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Improved finite difference method for pressure distribution of aerostatic bearing 被引量:4
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作者 郑书飞 蒋书运 《Journal of Southeast University(English Edition)》 EI CAS 2009年第4期501-505,共5页
An improved finite difference method (FDM)is described to solve existing problems such as low efficiency and poor convergence performance in the traditional method adopted to derive the pressure distribution of aero... An improved finite difference method (FDM)is described to solve existing problems such as low efficiency and poor convergence performance in the traditional method adopted to derive the pressure distribution of aerostatic bearings. A detailed theoretical analysis of the pressure distribution of the orifice-compensated aerostatic journal bearing is presented. The nonlinear dimensionless Reynolds equation of the aerostatic journal bearing is solved by the finite difference method. Based on the principle of flow equilibrium, a new iterative algorithm named the variable step size successive approximation method is presented to adjust the pressure at the orifice in the iterative process and enhance the efficiency and convergence performance of the algorithm. A general program is developed to analyze the pressure distribution of the aerostatic journal bearing by Matlab tool. The results show that the improved finite difference method is highly effective, reliable, stable, and convergent. Even when very thin gas film thicknesses (less than 2 Win)are considered, the improved calculation method still yields a result and converges fast. 展开更多
关键词 aerostatic bearing: pressure distribution: Reynolds equation: finite difference method variable step size
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New exact solutions for free vibrations of rectangular thin plates by symplectic dual method 被引量:12
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作者 Y. Xing B. Liu The Solid Mechanics Research Center, Beihang University, 100083 Beijing, China 《Acta Mechanica Sinica》 SCIE EI CAS CSCD 2009年第2期265-270,共6页
The separation of variables is employed to solve Hamiltonian dual form of eigenvalue problem for transverse free vibrations of thin plates, and formulation of the natural mode in closed form is performed. The closed-f... The separation of variables is employed to solve Hamiltonian dual form of eigenvalue problem for transverse free vibrations of thin plates, and formulation of the natural mode in closed form is performed. The closed-form natural mode satisfies the governing equation of the eigenvalue problem of thin plate exactly and is applicable for any types of boundary conditions. With all combinations of simplysupported (S) and clamped (C) boundary conditions applied to the natural mode, the mode shapes are obtained uniquely and two eigenvalue equations are derived with respect to two spatial coordinates, with the aid of which the normal modes and frequencies are solved exactly. It was believed that the exact eigensolutions for cases SSCC, SCCC and CCCC were unable to be obtained, however, they are successfully found in this paper. Comparisons between the present results and the FEM results validate the present exact solutions, which can thus be taken as the benchmark for verifying different approximate approaches. 展开更多
关键词 Classical theory of thin plate FREQUENCY Free vibrations Symplectic dual method Exact solution
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Abnormal variation of magnetic properties with Ce content in(PrNdCe)_2Fe_(14)B sintered magnets prepared by dual alloy method 被引量:4
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作者 张雪峰 兰剑亭 +4 位作者 李柱柏 刘艳丽 张乐乐 李永峰 赵倩 《Chinese Physics B》 SCIE EI CAS CSCD 2016年第5期352-356,共5页
Resource-saving(PrNdCe)_2Fe_(14)B sintered magnets with nominal composition(PrNd)_(15-x)Ce_xFe_(77)B_8(x=0–10)were prepared using a dual alloy method by mixing(PrNd)_5Ce_(10)Fe_(77)B_8 with(PrNd)_... Resource-saving(PrNdCe)_2Fe_(14)B sintered magnets with nominal composition(PrNd)_(15-x)Ce_xFe_(77)B_8(x=0–10)were prepared using a dual alloy method by mixing(PrNd)_5Ce_(10)Fe_(77)B_8 with(PrNd)_(15)Fe_(77)B_8 powders. For Ce atomic percent of 1% and 2%, coercivity decreases dramatically. With further increase of Ce atomic percent, the coercivity increases, peaks at 6.38 kOe in(PrNd)_(11)Ce_4Fe_(77)B_8, and then declines gradually. The abnormal dependence of coercivity is likely related to the inhomogeneity of rare earth chemical composition in the intergranular phase, where Pr Nd concentration is strongly dependent on the additive amount of(PrNd)_5Ce_(10)Fe_(77)B_8 powders. In addition, for Ce atomic percent of 8%,7%, and 6% the coercivity is higher than that of magnets prepared by the conventional method, which shows the advantage of the dual alloy method in preparing high abundant rare earth magnets. 展开更多
关键词 permanent magnets Ce element dual alloy method COERCIVITY
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