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A new variable step-size LMS method and its application in DOA estimation of OFDMA signals 认领 引用 被引量：4
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作者 Zhao Yan Lin Li +4 位作者 Dong Wen Wang Hao Wu Zhentao Wang Xiaojun Chen Xiaoshu 《Journal of Southeast University(English Edition)》 EI CAS 2020年第2期145-151,共7页
To meet the requirements of quick positioning of mobile terminals from base stations(BSs)or third-party devices,as well as to improve the convergence speed and reduce the steady state maladjustment of the least mean s... To meet the requirements of quick positioning of mobile terminals from base stations(BSs)or third-party devices,as well as to improve the convergence speed and reduce the steady state maladjustment of the least mean square(LMS)method,a new logarithmic-sigmoid variable step-size LMS(LG-SVSLMS)was proposed and applied to estimate the direction of arrival(DOA)of orthogonal frequency division multiple access(OFDMA)signals.Based on the proposed LG-SVSLMS,a non-blind DOA estimation system for OFDMA signals was constructed.The proposed LG-SVSLMS adopts a new multi-parameter step-size update function which combines the sigmoid function and the logarithmic function.It controls the adjustment magnitude of step-size during the initial and steady state phases of the LMS method to achieve both a high convergence speed and low steady state maladjustment.Finally,simulation was conducted to verify the performance of the LG-SVSLMS.The simulation results show that the non-blind DOA estimation system based on the LG-SVSLMS can accurately estimate the DOA of the target signal in the scenario where interference signals from multi-source and multi-path fading signals arrive at the third-party devices asynchronously with the target signal,and the estimation deviation is within±3°.The non-blind DOA estimation for OFDMA signals with the proposed LG-SVSLMS is of great significance for the instant positioning technology of mobile terminals based on the adaptive antenna array. 展开更多
关键词 direction of arrival variable step-size least mean square orthogonal frequency division multiple access third-party devices
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Integrating just-in-time expansion primitives and an adaptive variable-step-size mechanism for feasible path planning of finite-wing UAVs 认领 引用
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作者 Hui GAO Yuhong JIA +2 位作者 Qingyang QIN Liwen XU Yaoming ZHOU 《Chinese Journal of Aeronautics》 SCIE EI CAS CSCD 2025年第12期376-403,共28页
Path planning is crucial for autonomous flight of fixed-wing Unmanned Aerial Vehicles(UAVs).However,due to the high-speed flight and complex control of fixed-wing UAVs,ensuring the feasibility and safety of planned pa... Path planning is crucial for autonomous flight of fixed-wing Unmanned Aerial Vehicles(UAVs).However,due to the high-speed flight and complex control of fixed-wing UAVs,ensuring the feasibility and safety of planned paths in complex environments is challenging.This paper proposes a feasible path planning algorithm named Closed-loop Radial Ray A*(CL-RaA*).The core components of the CL-RaA*include an adaptive variable-step-size path search and a just-in-time expansion primitive.The former enables fast path search in complex environments,while the latter ensures the feasibility of the generated paths.By integrating these two components and conducting safety checks on the trajectories to be expanded,the CL-RaA*can rapidly generate safe and feasible paths that satisfy the differential constraints that comprehensively consider the dynamics and control characteristics of six-degree-of-freedom fixed-wing UAVs.The final performance tests and simulation validations demonstrate that the CL-RaA*can generate safe and feasible paths in various environments.Compared to feasible path planning algorithms that use the rapidlyexploring random trees,the CL-RaA*not only ensures deterministic planning results in the same scenarios but also generates smoother feasible paths for fixed-wing UAVs more efficiently.In environments with dense grid obstacles,the feasible paths generated by the CL-RaA*are more conducive to UAV tracking compared to those planned using Dubins curves. 展开更多
关键词 Adaptive variable step size Differential constraint Feasible path planning Fixed-wing unmanned aerial vehicle(UAV) Just-in-time expansion primitive Path search
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Optimal variable step-size LMS model and algorithm with independence assumption 认领 引用 被引量：6
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作者 谷源涛 唐昆 +1 位作者 崔慧娟 杜文 《Science in China(Series F)》 2003年第6期409-419,共11页
To solve the contradiction between convergence rate and steady-state error in least mean square (LMS) algorithm, basing on independence assumption, this paper proposes and proves the optimal step-size theorem from the... To solve the contradiction between convergence rate and steady-state error in least mean square (LMS) algorithm, basing on independence assumption, this paper proposes and proves the optimal step-size theorem from the view of minimizing mean squared error (MSE). The theorem reveals the one-to-one mapping between the optimal step-size and MSE. Following the theorem, optimal variable step-size LMS (OVS-LMS) model, describing the theoretical bound of the convergence rate of LMS algorithm, is constructed. Then we discuss the selection of initial optimal step-size and updating of optimal step-size at the time of unknown system changing. At last an optimal step-size LMS algorithm is proposed and tested in various environments. Simulation results show the proposed algorithm is very close to the theoretical bound. 展开更多
关键词 LMS OVS-LMS variable step-size optimal step-size theorem.
VARIABLE STEP-SIZE IMPLICIT-EXPLICIT LINEAR MULTISTEP METHODS FOR TIME-DEPENDENT PARTIAL DIFFERENTIAL EQUATIONS 认领 引用 被引量：4
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作者 DongWang Steven J. Ruuth 《Journal of Computational Mathematics》 SCIE EI 2008年第6期838-855,共18页
Implicit-explicit （IMEX） linear multistep methods are popular techniques for solving partial differential equations （PDEs） with terms of different types. While fixed timestep versions of such schemes have been dev... Implicit-explicit （IMEX） linear multistep methods are popular techniques for solving partial differential equations （PDEs） with terms of different types. While fixed timestep versions of such schemes have been developed and studied, implicit-explicit schemes also naturally arise in general situations where the temporal smoothness of the solution changes. In this paper we consider easily implementable variable step-size implicit-explicit （VSIMEX） linear multistep methods for time-dependent PDEs. Families of order-p, pstep VSIMEX schemes are constructed and analyzed, where p ranges from 1 to 4. The corresponding schemes are simple to implement and have the property that they reduce to the classical IMEX schemes whenever constant time step-sizes are imposed. The methods are validated on the Burgers＇ equation. These results demonstrate that by varying the time step-size, VSIMEX methods can outperform their fixed time step counterparts while still maintaining good numerical behavior. 展开更多
关键词 Implicit-explicit （IMEX） linear multistep methods Variable step-size Zero-stability Burgers＇ equation.
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OptimizationDesign and Numerical Simulation of Variable Tube Diameter Heat Exchanger for Split Air Conditioning Indoor Unit 认领 引用 被引量：1
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作者 Zheming Cheng Xinping Ou Yang +2 位作者 Leren Tao Zihao Wang Ke Sun 《Frontiers in Heat and Mass Transfer》 EI CAS 2026年第1期288-313,共26页
Energy shortage has become one of themost concerning issues in the world today,and improving energy utilization efficiency is a key area of research for experts and scholars worldwide.Small-diameter heat exchangers of... Energy shortage has become one of themost concerning issues in the world today,and improving energy utilization efficiency is a key area of research for experts and scholars worldwide.Small-diameter heat exchangers offer advantages such as reduced material usage,lower refrigerant charge,and compact structure.However,they also face challenges,including increased refrigerant pressure drop and smaller heat transfer area inside the tubes.This paper combines the advantages and disadvantages of both small and large-diameter tubes and proposes a combined-diameter heat exchanger,consisting of large and small diameters,for use in the indoor units of split-type air conditioners.There are relatively few studies in this area.In this paper,A theoretical and numerical computation method is employed to establish a theoretical-numerical calculation model,and its reliability is verified through experiments.Using this model,the optimal combined diameters and flow path design for a combined-diameter heat exchanger using R32 as the working fluid are derived.The results show that the heat transfer performance of all combined diameter configurations improves by 2.79%to 8.26%compared to the baseline design,with the coefficient of performance(COP)increasing from 4.15 to 4.27~4.5.These designs can save copper material,but at the cost of an increase in pressure drop by 66.86%to 131.84%.The scheme IIIH,using R32,is the optimal combined-diameter and flow path configuration that balances both heat transfer performance and economic cost. 展开更多
关键词 Split air condition variable tube diameter enhanced heat transfer numerical simulation structural design optimization
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VARIABLE STEP-SIZE BDF3 METHOD FOR ALLEN-CAHN EQUATION 认领 引用
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作者 Minghua Chen Fan Yu +1 位作者 Qingdong Zhang Zhimin Zhang 《Journal of Computational Mathematics》 SCIE CSCD 2024年第5期1380-1406,共27页
In this work,we analyze the three-step backward differentiation formula(BDF3)method for solving the Allen-Cahn equation on variable grids.For BDF2 method,the discrete orthogonal convolution(DOC)kernels are positive,th... In this work,we analyze the three-step backward differentiation formula(BDF3)method for solving the Allen-Cahn equation on variable grids.For BDF2 method,the discrete orthogonal convolution(DOC)kernels are positive,the stability and convergence analysis are well established in[Liao and Zhang,Math.Comp.,90(2021),1207–1226]and[Chen,Yu,and Zhang,arXiv:2108.02910,2021].However,the numerical analysis for BDF3 method with variable steps seems to be highly nontrivial due to the additional degrees of freedom and the non-positivity of DOC kernels.By developing a novel spectral norm inequality,the unconditional stability and convergence are rigorously proved under the updated step ratio restriction rk:=τk/τk−1≤1.405 for BDF3 method.Finally,numerical experiments are performed to illustrate the theoretical results.To the best of our knowledge,this is the first theoretical analysis of variable steps BDF3 method for the Allen-Cahn equation. 展开更多
关键词 Variable step-size BDF3 method Allen-Cahn equation Spectral norm inequality Stability and convergence analysis
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GENERALIZING SUBDIFFUSIVE BLACK-SCHOLES MODEL BY VARIABLE EXPONENT:MODEL TRANSFORMATION AND NUMERICAL APPROXIMATION 认领 引用
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作者 Meihui ZHANG Yaxue LIU +2 位作者 Mengmeng LIU Wenlin QIU Xiangcheng ZHENG 《Acta Mathematica Scientia》 SCIE CSCD 2026年第2期993-1010,共18页
This work generalizes the subdiffusive Black-Scholes model by introducing the variable exponent in order to provide adequate descriptions for the option pricing,where the variable exponent may account for the variatio... This work generalizes the subdiffusive Black-Scholes model by introducing the variable exponent in order to provide adequate descriptions for the option pricing,where the variable exponent may account for the variation of the memory property.In addition to standard nonlinear-to-linear transformation,we apply a further spatial-temporal transformation to convert the model to a more tractable form in order to circumvent the difficulties caused by the"non-positive,non-monotonic"variable-exponent memory kernel.An interesting phenomenon is that the spatial transformation not only eliminates the advection term but naturally turns the original noncoercive spatial operator into a coercive one due to the specific structure of the Black-Scholes model,which thus avoids imposing constraints on coefficients.Then we perform numerical analysis for both the semi-discrete and fully discrete schemes to support numerical simulation.Numerical experiments are carried out to substantiate the theoretical results. 展开更多
关键词 Black-Scholes model subdiffusion variable exponent error estimate option pricing
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Analysis of bilateral constrained sliding contact problems with variable friction coefficients via a cumulative frictional dissipation approach 认领 引用
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作者 Ling Tao Ling Wang +3 位作者 Ning Hu Shaowei Tong Hong Wen Qingshui Qiu 《Theoretical & Applied Mechanics Letters》 EI CAS CSCD 2026年第2期104-114,共11页
This work investigates the bidirectional relationship between contact mechanics and frictional wear behavior in bilateral constrained sliding contact.An internal state variable representing the contact surface conditi... This work investigates the bidirectional relationship between contact mechanics and frictional wear behavior in bilateral constrained sliding contact.An internal state variable representing the contact surface condition is incorporated into the Coulomb friction law to account for wear phenomena.A contact detection method has been constructed to identify the positional relationship between two elements during contact,leveraging vectorrelated features of the vertices on the contact area between the slideway and the slider.A bipotential function for rigid bilateral constraints is formulated by introducing a stability factor.Combining the potential-Coulomb contact force model,a numerical algorithm is developed for variable friction contact problems on the basis of cumulative frictional dissipation and is initially implemented for rigid body bilateral contact problems.The algorithm is subsequently applied to bilateral constraint analysis in a sliding mechanism under both constant and variable friction conditions,and the influences of the wear and contact clearance factors are studied.The numerical results demonstrate consistency with energy conservation principles and dynamic laws,validating the effectiveness of the proposed algorithm.This work extends the applicability of the bipotential function approach and provides a theoretical foundation and analytical tools for optimizing bilateral nonideal contact structures and predicting equipment service life. 展开更多
关键词 Wear Bilateral constraint Bipotential function Variable friction Frictional dissipation
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Aerodynamic characteristics and dual load suppression/trim maintenance method of variable trailing-edge camber rotor 认领 引用
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作者 Xiayang ZHANG Chencheng GAO +1 位作者 Qijun ZHAO Kai ZHANG 《Chinese Journal of Aeronautics》 SCIE EI CAS CSCD 2026年第7期264-282,共19页
To investigate the unsteady aerodynamic characteristics of rotor with Variable TrailingEdge Camber(VTEC),an unsteady rotor flowfield simulation method is established based on the URANS equation by introducing a deform... To investigate the unsteady aerodynamic characteristics of rotor with Variable TrailingEdge Camber(VTEC),an unsteady rotor flowfield simulation method is established based on the URANS equation by introducing a deformable moving-embedded grid method.The influence mechanisms of variable-camber amplitude Am,frequency k,and phaseφ0 on the unsteady aerodynamic characteristics of rotor are analyzed thoroughly,and whereby a VTEC optimization method is proposed through cross-iteration of variable-camber parameters to achieve the dual objectives of hub load suppression and trim maintenance.The numerical experiments indicate that the k=3 harmonic plays a dominant role in controlling the fluctuation of vertical hub load,which corresponds to the three-bladed rotor.The feasibility of dual load suppressionrim maintenance of VTEC is demonstrated,in which the fluctuation amplitudes of hub loads increments exhibit quasi-linear relationships with Am for k=0-4 and the fluctuation phase of vertical hub load variation shifts synchronously with the adjustment of φ0 for k=2-4.The results demonstrate that the proposed load suppression method can effectively decrease the fundamental 3ev vertical hub load and simultaneously maintain the rotor trim state. 展开更多
关键词 Load suppression Rotor Trim maintenance Unsteady aerodynamic characteristics Variable trailing-edge camber
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Analytical solution for longitudinal seismic response of variable stiffness tunnel with isolation layers under shear waves 认领 引用
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作者 LIU Xiang YANG Jiao-jiao +3 位作者 LI Kui-chen LU Tong JIANG An-nan FANG Qian 《Journal of Central South University》 SCIE EI CAS CSCD 2026年第6期2844-2867,共24页
Seismic isolation design typically emphasizes transverse responses of tunnels,with comparatively limited research on longitudinal isolation responses.Previous analytical solutions for isolation response are inapplicab... Seismic isolation design typically emphasizes transverse responses of tunnels,with comparatively limited research on longitudinal isolation responses.Previous analytical solutions for isolation response are inapplicable to variable stiffness tunnels.To address research gaps,analytical solutions for longitudinal seismic responses of variable stiffness tunnels with isolation layers are proposed.The solution can be applied to engineering practice.The mechanical model of isolation layers is developed using the Kelvin model.The variable stiffness tunnel is simplified as two semi-infinite beams embedded in homogeneous and isotropic soil layers.Governing equations are solved using integral transformations and continuity conditions.Analytical expressions are obtained by introducing displacement phase angles to simulate traveling wave effects.The proposed analytical solutions are validated through comparisons with results from existing literature and verified using numerical simulations.Parametric sensitivity analyses are conducted to investigate effects of tunnels with and without an isolation layer,isolation layer thickness and elastic modulus,tunnel stiffness ratio,and wavelength and amplitude of shear waves on seismic responses of variable stiffness tunnels.Changes in stiffness have a more significant effect on internal forces than displacements.Additionally,isolation layer's thickness and elastic modulus can be optimized through our method to balance structural performance and economic efficiency. 展开更多
关键词 isolation layer variable stiffness tunnel analytical solution seismic response shear waves
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Seepage on 3D active earth pressure of unsaturated soils considering spatially variable hydraulic properties 认领 引用
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作者 Hui Chen Qihao Jiang +2 位作者 Dongming Zhang Yadong Xue Hongwei Huang 《Journal of Rock Mechanics and Geotechnical Engineering》 SCIE CSCD 2026年第5期3949-3965,共17页
Traditional active earth pressure evaluations considering seepage are typically deterministic,assuming uniform soil layers.However,soil hydraulic properties exhibit the obvious spatial variability due to geomorphologi... Traditional active earth pressure evaluations considering seepage are typically deterministic,assuming uniform soil layers.However,soil hydraulic properties exhibit the obvious spatial variability due to geomorphological processes or poor construction control.To address this,the random limit analysis method(RLAM)is employed to investigate the influence of spatial variability of saturated hydraulic conductivity on active earth pressure.To combine random field simulations with the limit analysis based evaluation method,this study discretizes the conventional three-dimensional(3D)rotational failure mechanism.Owing to the energy dissipation principle,the explicit expression of 3D active earth pressures can be derived.The proposed method's validity is demonstrated through comparisons with available analytical solutions,deterministic numerical calculations,and random finite difference method(RFDM).RLAM integrating with Monte Carlo simulations(MCS)in MATLAB,facilitates the probabilistic analysis of the active earth pressure to be evaluated.The findings indicate that the present method not only incorporates the spatial variability of hydraulic properties,but also enhances the computational efficiency of calculating active earth pressures compared to the RFDM.Based on extensive uncertainty analyses,this study proposes a system reliability evaluation method for semi-gravity retaining walls,accounting for the spatial variability of saturated hydraulic conductivity.The results reveal that under different random field design scenarios,all decay curves of system failure probabilities for a semi-gravity retaining wall intersect within a specific range,referred to herein as the“turning region”.Furthermore,as the normalized horizontal autocorrelation distance,anisotropic ratio and coefficient of variation increase,the effective influence zone of the wall design index on system failure probability gradually expands,offering valuable guidance for the design and construction of semi-gravity retaining walls. 展开更多
关键词 Active earth pressure Saturated hydraulic conductivity Random field Spatial variability Retaining wall
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Analytical solutions on dynamic response of a thin-walled curved beam subjected to two-axle moving load with variable speed 认领 引用
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作者 Xiaoyong Lv Liupeng Li +1 位作者 Zhiwu Yu Peng Liu 《Acta Mechanica Sinica》 SCIE EI CAS CSCD 2026年第2期237-251,共15页
This paper proposes the analytical solutions involving damping effects for the dynamic response of a simply supported thin-walled curved beam under uniformly variable two-axle moving loads in four directions:vertical,... This paper proposes the analytical solutions involving damping effects for the dynamic response of a simply supported thin-walled curved beam under uniformly variable two-axle moving loads in four directions:vertical,torsional,radial,and axial.The warping stiffness and damping of the thin-walled beam were comprehensively considered in the vibration control equations.Unlike traditional one-axle load cases,this study employs a more realistic two-axle vehicle load model.Based on the modal superposition method,the control vibration equations for thin-walled curved beams in-plane and out-ofplane under variable speed moving loads were solved using a combination of the Fourier sine transform method,the Galerkin method,and the Laplace transform method.Analytical solutions for the dynamic responses were derived in integral form,facilitating direct numerical computation.The proposed computational method’s effectiveness and accuracy were validated against published research.Subsequently,the dynamic responses of the thin-walled curved beam under one-axle and two-axle moving load models were compared,and the effects of initial load velocity,load acceleration,and center angle of the curved beam on the dynamic responses were investigated through extensive parameter research.The research results provide valuable insights into the structural behavior of thin-walled curved beams under the moving loading with variable speed. 展开更多
关键词 Thin-walled curved beam Dynamic response Variable speed Two-axle moving load Analytical solution
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Mechanical responses of super-large-span variable cross-section tunnels in weak surrounding rock:A case study and the application of a novel constitutive model 认领 引用
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作者 CAO Wenxin ZHAO Wen +5 位作者 LIU Keqi SHAO Binghua BAI Qian ZHANG Yongfeng LU Bo WANG Yantao 《Journal of Mountain Science》 SCIE CSCD 2026年第6期2835-2855,共21页
Super-large-span and variable cross-section tunnels have proliferated in urban expressway systems across China.However,the deformation behavior and load distribution mechanisms in super-large and variable cross-sectio... Super-large-span and variable cross-section tunnels have proliferated in urban expressway systems across China.However,the deformation behavior and load distribution mechanisms in super-large and variable cross-section tunnels remain inadequately understood.This study systematically analyzed the mechanical response characteristics of super-large-span and variable cross-section tunnels in weak surrounding rock based on extensive field monitoring data.Mechanical tests were conducted to reveal the strain-softening characteristics of weak surrounding rock,and the nonlinear evolution of strength parameters was summarized.Through secondary development,a novel constitutive model based on the Hoek-Brown strength criterion was proposed and successfully implemented in FLAC3D.Furthermore,numerical simulations were conducted using an improved constitutive model.These simulations investigated the evolution of deformation and internal forces within the support system,accounting for the coupled effects of multiple factors.The research shows that the rock pillar compensates for the insufficient stiffness of temporary middle diaphragms.However,it also alters the mechanical behavior of the steel frame system,which leads to significant stress concentrations at the arch shoulders.Additionally,the"asymmetrical loading effect"commonly observed at variable cross-sections substantially impacts the support system within these span transition zones. 展开更多
关键词 Weak surrounding rock Super-large-span tunnel Variable cross-sections Field monitoring Mechanical tests Secondary development
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A Fast Algorithm for Matrix-Variable Triconvex Optimization With Application to Blind Image Deblurring 认领 引用
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作者 Songchuan Zhang Liqing Huang +1 位作者 Youshen Xia Jun Wang 《IEEE/CAA Journal of Automatica Sinica》 SCIE EI CSCD 2026年第5期1184-1206,共23页
Matrix-variable triconvex optimization is a significant generalization of vector-variable triconvex or biconvex optimization and has been found to have popular applications.To reduce computation time and storage requi... Matrix-variable triconvex optimization is a significant generalization of vector-variable triconvex or biconvex optimization and has been found to have popular applications.To reduce computation time and storage requirements,this paper presents a matrix-form iterative method for quickly solving matrix-variable constrained triconvex optimization problems.The proposed method is based on a matrix-form alternating projection iteration scheme in the form of matrix state spaces,where an efficient line search strategy is adopted by exploiting the optimality conditions of the problem for a larger step length.Compared with the existing vector-form alternating projection gradient method,the proposed method reduces storage requirements and computational cost,and thus is more computationally efficient.Each sequence generated by the proposed method is guaranteed to be globally convergent to a partial optimum under mild conditions.Finally,the proposed method is effectively applied to blind image deblurring problems.Computed results show that the proposed algorithm is superior to related iterative algorithms in terms of computation time and solution quality. 展开更多
关键词 Blind image deblurring global convergence matrixform iterative method matrix variable multiconvex optimization
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Intelligent Fault Diagnosis of Rolling Bearing With Variable Speed Based on ASTFrFT and Time-Frequency BoTNet Model 认领 引用
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作者 Jie Ma Jun Wei Xinyu Wang 《IEEE/CAA Journal of Automatica Sinica》 SCIE EI CSCD 2026年第7期1761-1763,共3页
Dear Editor,This letter presents an intelligent fault diagnosis method for variable speed rolling bearings based on the adaptive short-time fractional Fourier transform(ASTFrFT)and the time-frequency BoTNet(TFB)to add... Dear Editor,This letter presents an intelligent fault diagnosis method for variable speed rolling bearings based on the adaptive short-time fractional Fourier transform(ASTFrFT)and the time-frequency BoTNet(TFB)to address the challenge of extracting fault characteristics of rolling bearings under variable speed conditions and the poor classification of classical deep learning models.Firstly,to address the limitations of FrFT in time-varying signal processing,the physical mechanism of traditional STFT is extended into the FrFT domain by minimizing fuzzy entropy values to construct the order matrix. 展开更多
关键词 variable speed rolling bearings time frequency botnet rolling bearings deep learning modelsfirstlyto variable speed adaptive short time fractional fourier transform extracting fault characteristics intelligent fault diagnosis
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Progress in local-variable-based transition-turbulence models for subsonic and transonic boundary layers 认领 引用
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作者 Jiakuan XU Xi JIANG +3 位作者 Yutian WANG Ningjuan DONG Lei QIAO Junqiang BAI 《Chinese Journal of Aeronautics》 SCIE EI CAS CSCD 2026年第4期26-53,共28页
The accurate prediction of boundary layer transition represents a persistent and extensively studied challenge in fluid mechanics and aircraft aerodynamic design.It is well recognized that,due to the limitations in co... The accurate prediction of boundary layer transition represents a persistent and extensively studied challenge in fluid mechanics and aircraft aerodynamic design.It is well recognized that,due to the limitations in computational efficiency and shape complexity,high-resolution numerical simulation techniques and classical stability theory are hard to be applied in the numerical simulation and optimization of complex aircraft designs.The classical correlation-based Langtry and Menter model and laminar kinetic energy model,incorporating stability analysis results,offer efficient solution strategies under the Reynolds-averaged Navier-Stokes framework.Nonetheless,these models rely heavily on the range of available experimental data,which significantly restricts their applicability.Therefore,the Amplification Factor Transport(AFT)transition model anchored in linear stability theory foundations was derived from the findings of Coder and Maughmer and has since been adopted for transition prediction across a variety of complex geometries.This model not only incorporates the analytical foundation of linear stability theory,but also predicts the maximum envelope N value through a transport equation.It enables all non-local variables to be solved locally,ensuring compatibility with massively parallel computational fluid dynamics solvers.This paper systematically introduces the modeling concepts and key variable solution strategies of the currently prevalent transition-turbulence models based on local variables.It emphasizes the evolution of AFT transition frameworks,highlighting their progression from applications in the transition from 2D to 3D compressible boundary layer Tollmien-Schlichting waves,together with the formation of stationary crossflow vortices.In conclusion,this paper addresses the remaining challenges of the amplification factor transport transition model and explores potential directions for its future development. 展开更多
关键词 Boundary layer transition Computational fluid dynamics Linear stability theory Local variable Transition-turbulence model
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A data-and expert-driven framework for establishing land cover-related essential variables for SDG monitoring and assessment 认领 引用
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作者 Hao Wu Ping Zhang +6 位作者 Jun Chen Songnian Li Jing Li Shu Peng Dongyang Hou Jun Zhang Hao Chen 《Geography and Sustainability》 CSCD 2026年第1期236-246,共11页
Sustained and spatially explicit monitoring of the United Nations 2030 Agenda for Sustainable Development is critical for effectively tracking progress toward the global Sustainable Development Goals(SDGs).Although la... Sustained and spatially explicit monitoring of the United Nations 2030 Agenda for Sustainable Development is critical for effectively tracking progress toward the global Sustainable Development Goals(SDGs).Although land cover information has long been recognized as an essential component for monitoring SDGs,a standardized scientific framework for identifying and prioritizing land cover related essential variables does not exist.Therefore,we propose a novel expert-and data-driven framework for identifying,refining,and selecting a priority list of Essential Land cover-related Variables for SDGs(ELcV4SDGs).This framework integrates methods including expert knowledge-based analysis,clustering of variables with similar attributes,and quantified index calculation to establish the priority list.Applying the framework to 15 specific SDG indicators,we found that the ELcV4SDGs priority list comprises three main categories,type and structure,pattern and intensity,and process and evolution of land cover,which are further divided into 19 subcategories and ultimately encompass 50 general variables.The ELcV4SDGs will support detailed spatial monitoring and enhance their scientific applications for SDG monitoring and assessment,thereby guiding future SDG priority actions and informing decision-making to advance the 2030 SDGs agenda at local,national,and global levels. 展开更多
关键词 Essential variable Land cover SDG Spatial monitoring and assessment Interactive analysis Refinement and selection
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Mapping the Panorama of Enterprise Digital Transformation:An LLM-Driven Variable Relational Network Perspective 认领 引用
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作者 Zhichao Ba Yujie Zhang +1 位作者 Biao Zhang Gang Li 《Journal of Data and Information Science》 CSCD 2026年第2期10-35,共26页
Purpose:While the imperative of enterprise digital transformation(EDT)has been widely acknowledged,a systematic understanding of its intricate network of antecedents and consequences remains fragmented.This study prop... Purpose:While the imperative of enterprise digital transformation(EDT)has been widely acknowledged,a systematic understanding of its intricate network of antecedents and consequences remains fragmented.This study proposes a novel knowledge representation framework that leverages large language models(LLMs)to construct a variable relational network(VRN),offering a panoramic,micro-level perspective on EDT.Design/methodology/approach:We extract five types of variable relationships from a vast corpus of academic publications on EDT to generate the VRN.Subsequently,we apply network topology analysis to uncover the temporal and regional characteristics of the VRN.Its hierarchical structure is then analyzed through K-shell decomposition.Findings:Our results show that,over the past two decades,the scale of the VRN has experienced rapid growth,driven collectively by multi-layered external factors such as the rapid advancement of digital technologies,and its internal connections have become increasingly tighter.Regional comparisons of the VRN reveal that different economies,shaped by institutional theories,exhibit distinct transformation paradigms while striving toward common goals.K-shell analysis uncovers a clear hierarchical structure,distinguishing peripheral,intermediate,and core variables,with these layers corresponding to varying degrees of strategic significance and transformation maturity.Research limitations:The study’s limitations primarily concern the accuracy of the VRN,which depends on the LLM’s extraction performance and its potential for hallucinations,which may introduce noise into the network topology.Practical implications:The VRN and its network topology structure serve as a diagnostic tool for strategic decisionmaking,enterprises and policymakers can also use these insights to design targeted support programs.Originality/value:This study contributes a data-driven,LLM-assisted framework for mapping the evolving and multidimensional landscape of enterprise digital transformation,thereby validating and extending the theoretical boundaries of EDT. 展开更多
关键词 enterprise digital transformation scientific hypothesis large language models variable relational network hierarchical structure
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Continuous variable cross-section recycled extrusion of Ti–6Al–4V alloy: microstructure evolution, deformation mechanism and refinement mechanism 认领 引用
19
作者 Ying-Ying Liu Jun-Yi Zhang +7 位作者 Fang-Lin Wu Wen-Rui Ma Ze Wu Jia-Yi Li Jiang-Bo Zhai Shi-Feng Liu Wen Wang Kuai-She Wang 《Journal of Iron and Steel Research International》 SCIE EI CSCD 2026年第2期398-411,共14页
Continuous variable cross-section recycled extrusion(CVCE)is an advanced technique of severe plastic deformation.Ti–6Al–4V alloy was deformed with different processing parameters by CVCE,and then the microstructure ... Continuous variable cross-section recycled extrusion(CVCE)is an advanced technique of severe plastic deformation.Ti–6Al–4V alloy was deformed with different processing parameters by CVCE,and then the microstructure characterization,refinement mechanism and deformation mechanism were investigated simultaneously.The results demonstrate that the average size of grain is refined from 14 to 2.78μm as Ti–6Al–4V alloy is deformed at 800℃ with a speed of 2 mm/s over 6 passes,and the microstructure is equiaxed and distributed homogeneously along the radial direction.Furthermore,in the process of CVCE,basal slip(0001)is transformed to prismatic slip(100)system and pyramidal slip(112)system,with a reduction in low angle grain boundaries from 69.6%to 61.2%.Moreover,the grain refinement mechanism of CVCE is dislocation multiplication and cross-slip migration within the grain at the initial stage of deformation,which results in the formation of substructures and micro-shear bands as well as grain refinement.In addition,the nucleation and growth of dynamic recrystallization grains are beneficial to eliminating the dislocations,subgrain boundaries and other defects in the matrix,which finally results in the grains refinement. 展开更多
关键词 Ti-6Al-4V alloy Continuous variable cross-section recycled extrusion Microstructure Deformation mechanism Refinement mechanism
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A TimeXer-Based Numerical Forecast Correction Model Optimized by an Exogenous-Variable Attention Mechanism 认领 引用
20
作者 Yongmei Zhang Tianxin Zhang Linghua Tian 《Computers, Materials & Continua》 SCIE EI 2026年第3期1770-1785,共16页
Marine forecasting is critical for navigation safety and disaster prevention.However,traditional ocean numerical forecasting models are often limited by substantial errors and inadequate capture of temporal-spatial fe... Marine forecasting is critical for navigation safety and disaster prevention.However,traditional ocean numerical forecasting models are often limited by substantial errors and inadequate capture of temporal-spatial features.To address the limitations,the paper proposes a TimeXer-based numerical forecast correction model optimized by an exogenous-variable attention mechanism.The model treats target forecast values as internal variables,and incorporates historical temporal-spatial data and seven-day numerical forecast results from traditional models as external variables based on the embedding strategy of TimeXer.Using a self-attention structure,the model captures correlations between exogenous variables and target sequences,explores intrinsic multi-dimensional relationships,and subsequently corrects endogenous variables with the mined exogenous features.The model’s performance is evaluated using metrics including MSE(Mean Squared Error),MAE(Mean Absolute Error),RMSE(Root Mean Square Error),MAPE(Mean Absolute Percentage Error),MSPE(Mean Square Percentage Error),and computational time,with TimeXer and PatchTST models serving as benchmarks.Experiment results show that the proposed model achieves lower errors and higher correction accuracy for both one-day and seven-day forecasts. 展开更多
关键词 TimeXer model exogenous variable attention mechanism sea surface temperature temporal-spatial features forecast correction
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