Transforming urban spatial structures to promote green and low-carbon development is an effective strategy.Although prior studies have examined the impact of urban polycentricity on carbon emissions and economic devel...Transforming urban spatial structures to promote green and low-carbon development is an effective strategy.Although prior studies have examined the impact of urban polycentricity on carbon emissions and economic development,research on its role in the synergistic relationship between these factors regarding carbon emission efficiency is limited.Furthermore,existing literature often overlooks nonlinear effects and interactions with other urban variables.This paper analyzed data from 295 Chinese cities in 2020,calculating urban population polycentricity,population dispersion indices,and carbon emission efficiency.Utilizing local spatial autocorrelation tools,we reveal interactions among urban population polycentricity,dispersion,carbon emissions,and carbon emission efficiency.We then employ a gradient boosting decision tree model(GBDT)to explore nonlinear and synergistic effects of polycentric urbanization.Key findings include:1)polycentric urbanization in Chinese cities exhibits significant spatial differentiation characteristics.The Polycentricity index is relatively high in economically developed eastern coastal regions with an overall low level,carbon emissions are concentrated in industrialized north-central cities and some Yangtze River Delta hubs,and carbon emission efficiency is the highest in the Yangtze River Delta while relatively low in Northeast China;there are significant spatially heterogeneous interaction characteristics among population polycentricity,population dispersion,carbon emissions,and carbon emission efficiency.2)Urban population polycentricity contributes 9.42%to total carbon emissions and 6.24%to carbon emission efficiency.3)The polycentricity index has a nonlinear impact on carbon emissions and carbon emission efficiency:no significant effect when below 0.50 or above 0.55,increased carbon emissions in 0.50-0.53,and reduced carbon emissions with improved efficiency in 0.53-0.55.4)The polycentricity index has an interaction effect with other variables;specifically,when the polycentricity index is between 0.53 and 0.55,its interaction with urban gross domestic product(GDP),urban population,urban built-up area,green coverage rate in built-up areas,urban technological expenditure,and the proportion of the output value of the secondary industry will reduce carbon emissions and improve carbon emission efficiency.These findings enhance the understanding of urban spatial structures and carbon emissions,providing valuable insights for policymakers in developing green and low-carbon strategies.展开更多
The effects of the built environment factors on urban vitality have attracted wide attention in the urban planning fields in recent years,but few studies have considered the variables’relative importance and their no...The effects of the built environment factors on urban vitality have attracted wide attention in the urban planning fields in recent years,but few studies have considered the variables’relative importance and their nonlinear effects on urban vitality.Taking a Chinese metropolis—Hangzhou as a case study,this study applied the gradient boosting decision tree(GBDT)model to explore the nonlinear effects of the 5D factors of the urban built environment on urban social vitality and economic vitality and the importance of variables.The results show that the GBDT model has better goodness of fit than the traditional ordinary least squares(OLS)regression in the urban vitality models.The urban built environment plays an important role in affecting urban vitality,while built environment designs witness the most important effect.Specifically,the density of shopping facilities,medical facilities,and road networks are the most important factors affecting urban social vitality,while road network density,destination accessibility,and population density play the most important roles in affecting urban economic vitality.Finally,the urban built environment factors have nonlinear threshold effects on both urban economic and social vitality in Hangzhou,with differing nonlinear response patterns observed between social and economic dimensions.展开更多
In semiconductor precision packaging and other applications involving alignment of automated equipment,the nonlinear motion caused by structural characteristics and friction effects on torque-type rotating motion stag...In semiconductor precision packaging and other applications involving alignment of automated equipment,the nonlinear motion caused by structural characteristics and friction effects on torque-type rotating motion stages seriously affects output accuracy and stability.To solve this problem,the motion characteristics of a rotating stage and the mechanism by which friction nonlinearity influences accuracy are analyzed in detail.In addition,a compound control strategy based on a kinematic model and the Stribeck friction model is designed.A friction disturbance observer based on output position feedback is improved for simple parameter tuning.Finally,an experimental system is constructed to carry out validation tests,including identification of nonlinear characteristics and performance comparisons.The experimental results show that the linear tracking error of the torque-type rotating stage is less than 1.47µm after adoption of the proposed model-based composite control strategy,and the corresponding rotary angle deviation is less than 0.0153°.The linearity of output motion is increased to 97.59%and the error compensation effect is improved by 51.6%compared with the PID control method.The experimental results confirm that the analysis method adopted here and the proposed compensation strategy can effectively reduce frictional nonlinearity and improve motion accuracy.The proposed method can also be applied to other precision electromechanical systems.展开更多
A drag-free satellite is an important platform for space-borne gravitational wave(GW)observation.To achieve the high-precision control of a drag-free satellite in practical engineering,an accurate dynamic model is ess...A drag-free satellite is an important platform for space-borne gravitational wave(GW)observation.To achieve the high-precision control of a drag-free satellite in practical engineering,an accurate dynamic model is essential.This paper presents a nonlinear model of the electrostatic effect between a satellite and a test mass(TM),and designs a model predictive controller based on the drag-free satellite model with the nonlinear electrostatic effect.To determine the analytical form of the electrostatic effect,a comprehensive theoretical analysis is performed for gravitational reference sensors(GRSs).An electrostatic force and a torque are simulated with the displacement as a varying parameter through a commercial software.Then,the results are fitted to derive the nonlinear expressions of the electrostatic effect.The model predictive controllers based on the models with the nonlinear and linear electrostatic effects are designed in the capture mode.Finally,the control results are given to show the advantages of the nonlinear electrostatic effect.展开更多
Under investigation is the n-component nonlinear Schrödinger equation with higher-order effects,which describes the ultrashort pulses in the birefringent fiber.Based on the Lax pair,the eigenfunction and generali...Under investigation is the n-component nonlinear Schrödinger equation with higher-order effects,which describes the ultrashort pulses in the birefringent fiber.Based on the Lax pair,the eigenfunction and generalized Darboux transformation are derived.Next,we construct several novel higher-order localized waves and classified them into three categories:(i)higher-order rogue waves interacting with bright/antidark breathers,(ii)higher-order breather fission/fusion,(iii)higherorder breather interacting with soliton.Moreover,we explore the effects of parameters on the structure,collision process and energy distribution of localized waves and these characteristics are significantly different from previous ones.Finally,the dynamical properties of these solutions are discussed in detail.展开更多
Railway bridges are continuously loaded by railway trains;therefore, it is important to understand the nonlinear seismic response of the Vehicle-Bridge Interaction (VBI) system under strong earthquakes. For this purpo...Railway bridges are continuously loaded by railway trains;therefore, it is important to understand the nonlinear seismic response of the Vehicle-Bridge Interaction (VBI) system under strong earthquakes. For this purpose, the nonlinear behavior of the pier was introduced into the in-house VBI solvers. The nonlinear the seismic response of the VBI system was comprehensively evaluated using this model, and the effect of the vehicle dynamics on seismic performance of the bridge was identified. It was found that the seismic responses of most simply-supported bridges were reduced in the presence of railway trains due to the out-of-phase motion of the vehicle-bridge system. Meanwhile, the nonlinear behavior of the pier can reduce the vehicle’s seismic responses. Therefore, ignoring the nonlinear behavior of the pier during strong earthquakes can significantly overestimate the seismic response of the vehicle.展开更多
This paper presents an improved level set method for topology optimization of geometrically nonlinear structures accounting for the effect of thermo-mechanical couplings.It derives a new expression for element couplin...This paper presents an improved level set method for topology optimization of geometrically nonlinear structures accounting for the effect of thermo-mechanical couplings.It derives a new expression for element coupling stress resulting from the combination of mechanical and thermal loading,using geometric nonlinear finite element analysis.A topological model is then developed to minimize compliance while meeting displacement and frequency constraints to fulfill design requirements of structural members.Since the conventional Lagrange multiplier search method is unable to handle convergence instability arising from large deformation,a novel Lagrange multiplier search method is proposed.Additionally,the proposed method can be extended to multi-constrained geometrically nonlinear topology optimization,accommodating multiple physical field couplings.展开更多
In the near-infrared(NIR)spectroscopic data of complex sample systems,such as tobacco leaves,nonlinearity is fairly significant between the absorbance and concentration.This nonlinearity severely degrades the quantita...In the near-infrared(NIR)spectroscopic data of complex sample systems,such as tobacco leaves,nonlinearity is fairly significant between the absorbance and concentration.This nonlinearity severely degrades the quantitative results of traditional methods,such as partial least squares regression(PLS),which can be used to construct linear models.The problem was addressed in this study by using deep learning(DL).We employed three different DL models:a one-dimensional convolutional neural network(1D CNN),a deep neural network(DNN),and a stacked autoencoder with feedforward neural networks(SAE-FNNs).By carefully selecting and tuning the architectures and parameters of these models,we were able to find the most suitable model for dealing with such nonlinear relationships.Our experimental findings reveal that both the DNN and the SAE-FNN models excel in addressing the nonlinear issues of pectin concentration in tobacco,surpassing the performance of the classic linear model(PLS).Specifically,the DNN model stands out for its low average root mean squared error of prediction(RMSEP)value and small standard deviation(SD)of RMSEPs,leading to a tighter and more centered distribution of residuals in the prediction set.These DL models not only proficiently identify complex patterns within NIR data but also boast high prediction accuracy and fast implementation,demonstrating their effectiveness in analytical applications.展开更多
Nonlinear variations in the coordinate time series of global navigation satellite system(GNSS) reference stations are strongly correlated with surface displacements caused by environmental loading effects,including at...Nonlinear variations in the coordinate time series of global navigation satellite system(GNSS) reference stations are strongly correlated with surface displacements caused by environmental loading effects,including atmospheric, hydrological, and nontidal ocean loading. Continuous improvements in the accuracy of surface mass loading products, performance of Earth models, and precise data-processing technologies have significantly advanced research on the effects of environmental loading on nonlinear variations in GNSS coordinate time series. However, owing to theoretical limitations, the lack of high spatiotemporal resolution surface mass observations, and the coupling of GNSS technology-related systematic errors, environmental loading and nonlinear GNSS reference station displacements remain inconsistent. The applicability and capability of these loading products across different regions also require further evaluation. This paper outlines methods for modeling environmental loading, surface mass loading products, and service organizations. In addition, it summarizes recent advances in applying environmental loading to address nonlinear variations in global and regional GNSS coordinate time series. Moreover, the scientific questions of existing studies are summarized, and insights into future research directions are provided. The complex nonlinear motion of reference stations is a major factor limiting the accuracy of the current terrestrial reference frame. Further refining the environmental load modeling method, establishing a surface mass distribution model with high spatiotemporal resolution and reliability, exploring other environmental load factors such as ice sheet and artificial mass-change effects, and developing an optimal data-processing model and strategy for reprocessing global reference station data consistently could contribute to the development of a millimeter-level nonlinear motion model for GNSS reference stations with actual physical significance and provide theoretical support for establishing a terrestrial reference frame with 1 mm accuracy by 2050.展开更多
When the size of a magneto-electro-elastic cylindrical shell (MEECS) is reduced to micro-/nano-scale, the size-dependent flexomagnetic effect (FME) and flexoelectric effect (FEE) significantly influence their multi-ph...When the size of a magneto-electro-elastic cylindrical shell (MEECS) is reduced to micro-/nano-scale, the size-dependent flexomagnetic effect (FME) and flexoelectric effect (FEE) significantly influence their multi-physical coupling behaviors. To investigate these effects on the post-buckling behaviors of an MEECS, a nonlinear post-buckling model is developed based on the higher-order shear deformation theory (HSDT) and magneto-electro-elastic (MEE) constitutive relations with the FME and FEE. The equilibrium path and the corresponding shell deformations are obtained with a set of newly developed generalized displacement functions within the framework of the Galerkin approach. These displacement functions are established based on the trigonometric series expansions, which accurately satisfy the clamped boundary conditions (BCs). The effects of geometry, flexomagnetic/flexoelectric coefficients, and external electromagnetic fields on the post-buckling behaviors of an MEECS with the FME and FEE are analyzed. Numerical results indicate that the FME decreases the upper critical load of an MEECS, whereas the FEE exhibits an opposite effect by increasing it.展开更多
In this paper,we consider the maximal positive definite solution of the nonlinear matrix equation.By using the idea of Algorithm 2.1 in ZHANG(2013),a new inversion-free method with a stepsize parameter is proposed to ...In this paper,we consider the maximal positive definite solution of the nonlinear matrix equation.By using the idea of Algorithm 2.1 in ZHANG(2013),a new inversion-free method with a stepsize parameter is proposed to obtain the maximal positive definite solution of nonlinear matrix equation X+A^(*)X|^(-α)A=Q with the case 0<α≤1.Based on this method,a new iterative algorithm is developed,and its convergence proof is given.Finally,two numerical examples are provided to show the effectiveness of the proposed method.展开更多
The in-flight heating process of cerium dioxide(CeO_(2))powders was investigated through experiments and numerical simulations.In the experiment,CeO_(2)powder(average size of 30μm)was injected into radio-frequency(RF...The in-flight heating process of cerium dioxide(CeO_(2))powders was investigated through experiments and numerical simulations.In the experiment,CeO_(2)powder(average size of 30μm)was injected into radio-frequency(RF)argon plasma,and the temperatures were measured using a DPV-2000 monitor.A model combining the electromagnetism,thermal flow,and heat transfer characteristics of powder during in-flight heating in argon plasma was proposed.The melting processes of CeO_(2)powders of different diameters,with and without thermal resistance effect,were investigated.Results show that the heating process of CeO_(2)powder particles consists of three main stages,one of which is relevant to a dimensionless parameter known as the Biot number.When the Biot value≥0.1,thermal resistance increases significantly,especially for the larger powders.The predicted temperature of the particles at the outlet(1800–2880 K)is in good agreement with the experimental result.展开更多
This study explores the complex dynamics of unsteady convective flow in micropolar nanofluids over a rough conical surface, with a focus on the effects of triple diffusive transport and Arrhenius activation energy. Th...This study explores the complex dynamics of unsteady convective flow in micropolar nanofluids over a rough conical surface, with a focus on the effects of triple diffusive transport and Arrhenius activation energy. The primary objective is to understand the interplay among nonlinear convection, micro-rotation effects, and species diffusion under the influence of thermal and electromagnetic forces. The analysis is motivated by practical applications of cryogenic fluids, specifically liquid hydrogen and liquid nitrogen,where precise control of heat and mass transport is critical. The conical surface roughness is mathematically modeled as a high-frequency, small-amplitude sinusoidal waveform.To address the non-similar nature of the boundary-layer equations, Mangler's transformations are employed, followed by the implementation of a finite difference scheme for numerical solutions. The methodology further integrates a machine learning-based neural network to predict the skin friction under the influence of roughness-induced perturbations, ensuring computational efficiency and improved generalization. The study yields several novel findings. Notably, the presence of surface roughness introduces the wavelike modulations in the local skin friction coefficient. It is also observed that nonlinear convective interactions, enhanced by temperature gradients and vortex viscosity parameters, significantly intensify near-wall velocity gradients. Moreover, key physical quantities are correlated with governing parameters using power-law relationships, providing generalized predictive models. The validation of the numerical results is achieved through consistency checks with the existing limiting solutions and convergence analysis, ensuring the reliability of the proposed computational framework.展开更多
Rechargeable Zn/Sn-air batteries have received considerable attention as promising energy storage devices.However,the electrochemical performance of these batteries is significantly constrained by the sluggish electro...Rechargeable Zn/Sn-air batteries have received considerable attention as promising energy storage devices.However,the electrochemical performance of these batteries is significantly constrained by the sluggish electrocatalytic reaction kinetics at the cathode.The integration of light energy into Zn/Sn-air batteries is a promising strategy for enhancing their performance.However,the photothermal and photoelectric effects generate heat in the battery under prolonged solar irradiation,leading to air cathode instability.This paper presents the first design and synthesis of Ni_(2)-1,5-diamino-4,8-dihydroxyanthraquinone(Ni_(2)DDA),an electronically conductiveπ-d conjugated metal-organic framework(MOF).Ni_(2)DDA exhibits both photoelectric and photothermal effects,with an optical band gap of~1.14 eV.Under illumination,Ni_(2)DDA achieves excellent oxygen evolution reaction performance(with an overpotential of 245 mV vs.reversible hydrogen electrode at 10 mA cm^(−2))and photothermal stability.These properties result from the synergy between the photoelectric and photothermal effects of Ni_(2)DDA.Upon integration into Zn/Sn-air batteries,Ni_(2)DDA ensures excellent cycling stability under light and exhibits remarkable performance in high-temperature environments up to 80℃.This study experimentally confirms the stable operation of photo-assisted Zn/Sn-air batteries under high-temperature conditions for the first time and provides novel insights into the application of electronically conductive MOFs in photoelectrocatalysis and photothermal catalysis.展开更多
This paper aims to explore and quantify the nonlinear vibration response of tri-directional functionally graded sandwich(3D-FGSW)plates partially supported by a Pasternak foundation(PF)subjected to blast loading(BL).A...This paper aims to explore and quantify the nonlinear vibration response of tri-directional functionally graded sandwich(3D-FGSW)plates partially supported by a Pasternak foundation(PF)subjected to blast loading(BL).A key objective is to develop a computationally efficient finite element framework capable of accurately capturing the complex behavior of 3D-FGSW plates.The studied configuration features a two-dimensional functionally graded material(2D-FGM)core between two threedimensional functionally graded material(3D-FGM)face layers.Nonlinear geometric effects,including mid-plane stretching,are modeled using von K arm an-type assumptions,and the governing equations are formulated via Hamilton's principle within an improved first-order shear deformation theory(iFSDT).The accuracy and computational efficiency of the proposed method are validated through comparison with existing benchmark solutions.Subsequently,a comprehensive parametric study is carried out to examine the effects of geometric dimensions,material properties,foundation sizes,and boundary conditions(BCs)on the nonlinear vibration of 3D-FGSW plates.The findings of this work are expected to provide valuable insights for the design and manufacturing of advanced sandwich structures subjected to BL.展开更多
The bipartite containment control problem for heterogeneous nonlinear multi-agent systems(HNMASs)within multi-group networks under signed digraphs is investigated,where the first-order and second-order nonlinear dynam...The bipartite containment control problem for heterogeneous nonlinear multi-agent systems(HNMASs)within multi-group networks under signed digraphs is investigated,where the first-order and second-order nonlinear dynamic agents belong to distinct groups.Interactions are cooperative-antagonistic within each group and sign-in-degree balanced across the inter-groups.Firstly,a state feedback control protocol is designed to ensure that the trajectories of followers in diverse groups can converge to distinct convex hulls formed by their corresponding leaders,respectively.As an extension,the bipartite control problem with time-variant formation for the multi-agent system(MAS)is also considered,and a corresponding control protocol with formation compensation vectors is given.Finally,in view of Lyapunov stability theory and matrix inequality,the sufficient conditions for realizing the bipartite containment control are obtained,and several simulations are provided to verify the validity of the above methods.展开更多
Beam-tracking simulations have been extensively utilized in the study of collective beam instabilities in circular accelerators.Traditionally,many simulation codes have relied on central processing unit(CPU)-based met...Beam-tracking simulations have been extensively utilized in the study of collective beam instabilities in circular accelerators.Traditionally,many simulation codes have relied on central processing unit(CPU)-based methods,tracking on a single CPU core,or parallelizing the computation across multiple cores via the message passing interface(MPI).Although these approaches work well for single-bunch tracking,scaling them to multiple bunches significantly increases the computational load,which often necessitates the use of a dedicated multi-CPU cluster.To address this challenge,alternative methods leveraging General-Purpose computing on Graphics Processing Units(GPGPU)have been proposed,enabling tracking studies on a standalone desktop personal computer(PC).However,frequent CPU-GPU interactions,including data transfers and synchronization operations during tracking,can introduce communication overheads,potentially reducing the overall effectiveness of GPU-based computations.In this study,we propose a novel approach that eliminates this overhead by performing the entire tracking simulation process exclusively on the GPU,thereby enabling the simultaneous processing of all bunches and their macro-particles.Specifically,we introduce MBTRACK2-CUDA,a Compute Unified Device Architecture(CUDA)ported version of MBTRACK2,which facilitates efficient tracking of single-and multi-bunch collective effects by leveraging the full GPU-resident computation.展开更多
The dried fruit of Forsythia suspensa(Oleaceae),also known as Forsythia,is a traditional Chinese medicinal herb known for its heat-clearing and detoxifying properties.It is used to disperse nodules,reduce swelling,rem...The dried fruit of Forsythia suspensa(Oleaceae),also known as Forsythia,is a traditional Chinese medicinal herb known for its heat-clearing and detoxifying properties.It is used to disperse nodules,reduce swelling,remove toxins,clear heat,and alleviate wind-heat syndromes.It also has hepatoprotective,anti-inflammatory,antiviral,antibacterial,anticancer,antioxidant,antiaging,and anti-obesity effects,as well as potential therapeutic effects on Alzheimer’s disease and diabetic nephropathy.It is used to treat scrofula,mastitis,wind-heat common cold,and other ailments.The review summarizes the chemical constituents and pharmacological effects of F.suspensa,aiming to provide a scientific foundation for its future development,research,and clinical utilization.展开更多
Kagome magnets are of growing interest due to their topological electronic structures and unconventional magnetic behavior.Here,we report on the anomalous Hall effect(AHE)in the kagome ferromagnet MgMn_(6)Sn_(6),which...Kagome magnets are of growing interest due to their topological electronic structures and unconventional magnetic behavior.Here,we report on the anomalous Hall effect(AHE)in the kagome ferromagnet MgMn_(6)Sn_(6),which has a Curie temperature of~290 K and an in-plane easy magnetization axis.Magnetotransport measurements show a positive magnetoresistance(MR)below 50 K,which becomes negative at higher temperatures.An intrinsic anomalous Hall conductivity of 114 S·cm^(-1)is observed in MgMn_(6)Sn_(6) single crystals,consistent with ab initio calculations.Moreover,theoretical predictions indicate that shifting the Fermi level(EF)upward by~70 meV could enhance the AHE to~528 S·cm^(-1).These results position MgMn_(6)Sn_(6) as a promising and tunable platform for exploring topological magnetism and related electronic phenomena.展开更多
The goal of this paper is to investigate the long-time dynamics of solutions to a Kirchhoff type suspension bridge equation with nonlinear damping and memory term.For this problem we establish the well-posedness and e...The goal of this paper is to investigate the long-time dynamics of solutions to a Kirchhoff type suspension bridge equation with nonlinear damping and memory term.For this problem we establish the well-posedness and existence of uniform attractor under some suitable assumptions on the nonlinear term g(u),the nonlinear damping f(u_(t))and the external force h(x,t).Specifically,the asymptotic compactness of the semigroup is verified by the energy reconstruction method.展开更多
基金Under the auspices of National Natural Science Foundation of China(No.42571300)。
文摘Transforming urban spatial structures to promote green and low-carbon development is an effective strategy.Although prior studies have examined the impact of urban polycentricity on carbon emissions and economic development,research on its role in the synergistic relationship between these factors regarding carbon emission efficiency is limited.Furthermore,existing literature often overlooks nonlinear effects and interactions with other urban variables.This paper analyzed data from 295 Chinese cities in 2020,calculating urban population polycentricity,population dispersion indices,and carbon emission efficiency.Utilizing local spatial autocorrelation tools,we reveal interactions among urban population polycentricity,dispersion,carbon emissions,and carbon emission efficiency.We then employ a gradient boosting decision tree model(GBDT)to explore nonlinear and synergistic effects of polycentric urbanization.Key findings include:1)polycentric urbanization in Chinese cities exhibits significant spatial differentiation characteristics.The Polycentricity index is relatively high in economically developed eastern coastal regions with an overall low level,carbon emissions are concentrated in industrialized north-central cities and some Yangtze River Delta hubs,and carbon emission efficiency is the highest in the Yangtze River Delta while relatively low in Northeast China;there are significant spatially heterogeneous interaction characteristics among population polycentricity,population dispersion,carbon emissions,and carbon emission efficiency.2)Urban population polycentricity contributes 9.42%to total carbon emissions and 6.24%to carbon emission efficiency.3)The polycentricity index has a nonlinear impact on carbon emissions and carbon emission efficiency:no significant effect when below 0.50 or above 0.55,increased carbon emissions in 0.50-0.53,and reduced carbon emissions with improved efficiency in 0.53-0.55.4)The polycentricity index has an interaction effect with other variables;specifically,when the polycentricity index is between 0.53 and 0.55,its interaction with urban gross domestic product(GDP),urban population,urban built-up area,green coverage rate in built-up areas,urban technological expenditure,and the proportion of the output value of the secondary industry will reduce carbon emissions and improve carbon emission efficiency.These findings enhance the understanding of urban spatial structures and carbon emissions,providing valuable insights for policymakers in developing green and low-carbon strategies.
基金National Social Science Foundation of China,No.20FJLB025National Natural Science Foundation of China,No.42471207,No.42471203Zhejiang Province Philosophy and Social Science Planning,Zhijiang Youth Special Project,24ZJQN118Y。
文摘The effects of the built environment factors on urban vitality have attracted wide attention in the urban planning fields in recent years,but few studies have considered the variables’relative importance and their nonlinear effects on urban vitality.Taking a Chinese metropolis—Hangzhou as a case study,this study applied the gradient boosting decision tree(GBDT)model to explore the nonlinear effects of the 5D factors of the urban built environment on urban social vitality and economic vitality and the importance of variables.The results show that the GBDT model has better goodness of fit than the traditional ordinary least squares(OLS)regression in the urban vitality models.The urban built environment plays an important role in affecting urban vitality,while built environment designs witness the most important effect.Specifically,the density of shopping facilities,medical facilities,and road networks are the most important factors affecting urban social vitality,while road network density,destination accessibility,and population density play the most important roles in affecting urban economic vitality.Finally,the urban built environment factors have nonlinear threshold effects on both urban economic and social vitality in Hangzhou,with differing nonlinear response patterns observed between social and economic dimensions.
基金funded by the European Union’s Horizon 2020 Research and Innovation Program under the Marie Sklodowska-Curie Grant Agreement(Grant No.101026104)by the National Natural Science Foundation of China(Grant No.U20A6004)in part by the State Key Laboratory of Precision Electronics Manufacturing Technology and Equipment(Grant No.JMDZ202314).
文摘In semiconductor precision packaging and other applications involving alignment of automated equipment,the nonlinear motion caused by structural characteristics and friction effects on torque-type rotating motion stages seriously affects output accuracy and stability.To solve this problem,the motion characteristics of a rotating stage and the mechanism by which friction nonlinearity influences accuracy are analyzed in detail.In addition,a compound control strategy based on a kinematic model and the Stribeck friction model is designed.A friction disturbance observer based on output position feedback is improved for simple parameter tuning.Finally,an experimental system is constructed to carry out validation tests,including identification of nonlinear characteristics and performance comparisons.The experimental results show that the linear tracking error of the torque-type rotating stage is less than 1.47µm after adoption of the proposed model-based composite control strategy,and the corresponding rotary angle deviation is less than 0.0153°.The linearity of output motion is increased to 97.59%and the error compensation effect is improved by 51.6%compared with the PID control method.The experimental results confirm that the analysis method adopted here and the proposed compensation strategy can effectively reduce frictional nonlinearity and improve motion accuracy.The proposed method can also be applied to other precision electromechanical systems.
基金supported by the National Key Research and Development Program of China(No.2022YFC2204800)the National Natural Science Foundation of China(No.W2433004)the Jiangsu Funding Program for Excellent Postdoctoral Talent of China(No.2024ZB114)。
文摘A drag-free satellite is an important platform for space-borne gravitational wave(GW)observation.To achieve the high-precision control of a drag-free satellite in practical engineering,an accurate dynamic model is essential.This paper presents a nonlinear model of the electrostatic effect between a satellite and a test mass(TM),and designs a model predictive controller based on the drag-free satellite model with the nonlinear electrostatic effect.To determine the analytical form of the electrostatic effect,a comprehensive theoretical analysis is performed for gravitational reference sensors(GRSs).An electrostatic force and a torque are simulated with the displacement as a varying parameter through a commercial software.Then,the results are fitted to derive the nonlinear expressions of the electrostatic effect.The model predictive controllers based on the models with the nonlinear and linear electrostatic effects are designed in the capture mode.Finally,the control results are given to show the advantages of the nonlinear electrostatic effect.
基金Project supported by the National Natural Science Foundation of China(Grant No.12271096)the Natural Science Foundation of Fujian Province(Grant No.2021J01302)。
文摘Under investigation is the n-component nonlinear Schrödinger equation with higher-order effects,which describes the ultrashort pulses in the birefringent fiber.Based on the Lax pair,the eigenfunction and generalized Darboux transformation are derived.Next,we construct several novel higher-order localized waves and classified them into three categories:(i)higher-order rogue waves interacting with bright/antidark breathers,(ii)higher-order breather fission/fusion,(iii)higherorder breather interacting with soliton.Moreover,we explore the effects of parameters on the structure,collision process and energy distribution of localized waves and these characteristics are significantly different from previous ones.Finally,the dynamical properties of these solutions are discussed in detail.
基金supported by the National Natural Science Foundation of China(Grant No.51678490)the Natural Science Foundation of Sichuan Province(Grant No.2024NSFSC0161).
文摘Railway bridges are continuously loaded by railway trains;therefore, it is important to understand the nonlinear seismic response of the Vehicle-Bridge Interaction (VBI) system under strong earthquakes. For this purpose, the nonlinear behavior of the pier was introduced into the in-house VBI solvers. The nonlinear the seismic response of the VBI system was comprehensively evaluated using this model, and the effect of the vehicle dynamics on seismic performance of the bridge was identified. It was found that the seismic responses of most simply-supported bridges were reduced in the presence of railway trains due to the out-of-phase motion of the vehicle-bridge system. Meanwhile, the nonlinear behavior of the pier can reduce the vehicle’s seismic responses. Therefore, ignoring the nonlinear behavior of the pier during strong earthquakes can significantly overestimate the seismic response of the vehicle.
基金supported by grants from the National Natural Science Foundation of China (51478130)the Guangzhou Municipal Education Bureau’s Scientific Research Project, China (2024312217)+1 种基金the China Scholarship Council (201808440070)the 111 Project of China (D21021).
文摘This paper presents an improved level set method for topology optimization of geometrically nonlinear structures accounting for the effect of thermo-mechanical couplings.It derives a new expression for element coupling stress resulting from the combination of mechanical and thermal loading,using geometric nonlinear finite element analysis.A topological model is then developed to minimize compliance while meeting displacement and frequency constraints to fulfill design requirements of structural members.Since the conventional Lagrange multiplier search method is unable to handle convergence instability arising from large deformation,a novel Lagrange multiplier search method is proposed.Additionally,the proposed method can be extended to multi-constrained geometrically nonlinear topology optimization,accommodating multiple physical field couplings.
基金supported by a joint project with SINOPEC(Dalian)Research Institute of Petroleum and Petrochemicals Co.,Ltd.(Contract No.323061).
文摘In the near-infrared(NIR)spectroscopic data of complex sample systems,such as tobacco leaves,nonlinearity is fairly significant between the absorbance and concentration.This nonlinearity severely degrades the quantitative results of traditional methods,such as partial least squares regression(PLS),which can be used to construct linear models.The problem was addressed in this study by using deep learning(DL).We employed three different DL models:a one-dimensional convolutional neural network(1D CNN),a deep neural network(DNN),and a stacked autoencoder with feedforward neural networks(SAE-FNNs).By carefully selecting and tuning the architectures and parameters of these models,we were able to find the most suitable model for dealing with such nonlinear relationships.Our experimental findings reveal that both the DNN and the SAE-FNN models excel in addressing the nonlinear issues of pectin concentration in tobacco,surpassing the performance of the classic linear model(PLS).Specifically,the DNN model stands out for its low average root mean squared error of prediction(RMSEP)value and small standard deviation(SD)of RMSEPs,leading to a tighter and more centered distribution of residuals in the prediction set.These DL models not only proficiently identify complex patterns within NIR data but also boast high prediction accuracy and fast implementation,demonstrating their effectiveness in analytical applications.
基金supported by the Basic Science Center Project of the National Natural Science Foundation of China(42388102)the National Natural Science Foundation of China(42174030)+2 种基金the Special Fund of Hubei Luojia Laboratory(220100020)the Major Science and Technology Program for Hubei Province(2022AAA002)the Fundamental Research Funds for the Central Universities of China(2042022dx0001 and 2042023kfyq01)。
文摘Nonlinear variations in the coordinate time series of global navigation satellite system(GNSS) reference stations are strongly correlated with surface displacements caused by environmental loading effects,including atmospheric, hydrological, and nontidal ocean loading. Continuous improvements in the accuracy of surface mass loading products, performance of Earth models, and precise data-processing technologies have significantly advanced research on the effects of environmental loading on nonlinear variations in GNSS coordinate time series. However, owing to theoretical limitations, the lack of high spatiotemporal resolution surface mass observations, and the coupling of GNSS technology-related systematic errors, environmental loading and nonlinear GNSS reference station displacements remain inconsistent. The applicability and capability of these loading products across different regions also require further evaluation. This paper outlines methods for modeling environmental loading, surface mass loading products, and service organizations. In addition, it summarizes recent advances in applying environmental loading to address nonlinear variations in global and regional GNSS coordinate time series. Moreover, the scientific questions of existing studies are summarized, and insights into future research directions are provided. The complex nonlinear motion of reference stations is a major factor limiting the accuracy of the current terrestrial reference frame. Further refining the environmental load modeling method, establishing a surface mass distribution model with high spatiotemporal resolution and reliability, exploring other environmental load factors such as ice sheet and artificial mass-change effects, and developing an optimal data-processing model and strategy for reprocessing global reference station data consistently could contribute to the development of a millimeter-level nonlinear motion model for GNSS reference stations with actual physical significance and provide theoretical support for establishing a terrestrial reference frame with 1 mm accuracy by 2050.
基金Project supported by the National Natural Science Foundation of China (No. 12472064)。
文摘When the size of a magneto-electro-elastic cylindrical shell (MEECS) is reduced to micro-/nano-scale, the size-dependent flexomagnetic effect (FME) and flexoelectric effect (FEE) significantly influence their multi-physical coupling behaviors. To investigate these effects on the post-buckling behaviors of an MEECS, a nonlinear post-buckling model is developed based on the higher-order shear deformation theory (HSDT) and magneto-electro-elastic (MEE) constitutive relations with the FME and FEE. The equilibrium path and the corresponding shell deformations are obtained with a set of newly developed generalized displacement functions within the framework of the Galerkin approach. These displacement functions are established based on the trigonometric series expansions, which accurately satisfy the clamped boundary conditions (BCs). The effects of geometry, flexomagnetic/flexoelectric coefficients, and external electromagnetic fields on the post-buckling behaviors of an MEECS with the FME and FEE are analyzed. Numerical results indicate that the FME decreases the upper critical load of an MEECS, whereas the FEE exhibits an opposite effect by increasing it.
基金Supported in part by Natural Science Foundation of Guangxi(2023GXNSFAA026246)in part by the Central Government's Guide to Local Science and Technology Development Fund(GuikeZY23055044)in part by the National Natural Science Foundation of China(62363003)。
文摘In this paper,we consider the maximal positive definite solution of the nonlinear matrix equation.By using the idea of Algorithm 2.1 in ZHANG(2013),a new inversion-free method with a stepsize parameter is proposed to obtain the maximal positive definite solution of nonlinear matrix equation X+A^(*)X|^(-α)A=Q with the case 0<α≤1.Based on this method,a new iterative algorithm is developed,and its convergence proof is given.Finally,two numerical examples are provided to show the effectiveness of the proposed method.
基金National Natural Science Foundation of China(11875039)Shanxi Scholarship Council of China(2023-033)+2 种基金Fundamental Research Program of Shanxi Province(202303021221071)China Baowu Low Carbon Metallurgical Innovation Foundation(2022)2023 Anhui Major Industrial Innovation Plan Project。
文摘The in-flight heating process of cerium dioxide(CeO_(2))powders was investigated through experiments and numerical simulations.In the experiment,CeO_(2)powder(average size of 30μm)was injected into radio-frequency(RF)argon plasma,and the temperatures were measured using a DPV-2000 monitor.A model combining the electromagnetism,thermal flow,and heat transfer characteristics of powder during in-flight heating in argon plasma was proposed.The melting processes of CeO_(2)powders of different diameters,with and without thermal resistance effect,were investigated.Results show that the heating process of CeO_(2)powder particles consists of three main stages,one of which is relevant to a dimensionless parameter known as the Biot number.When the Biot value≥0.1,thermal resistance increases significantly,especially for the larger powders.The predicted temperature of the particles at the outlet(1800–2880 K)is in good agreement with the experimental result.
基金the Deanship of Research and Graduate Studies at King Khalid University for funding this work through Large Research Project under grant number RGP2/111/46
文摘This study explores the complex dynamics of unsteady convective flow in micropolar nanofluids over a rough conical surface, with a focus on the effects of triple diffusive transport and Arrhenius activation energy. The primary objective is to understand the interplay among nonlinear convection, micro-rotation effects, and species diffusion under the influence of thermal and electromagnetic forces. The analysis is motivated by practical applications of cryogenic fluids, specifically liquid hydrogen and liquid nitrogen,where precise control of heat and mass transport is critical. The conical surface roughness is mathematically modeled as a high-frequency, small-amplitude sinusoidal waveform.To address the non-similar nature of the boundary-layer equations, Mangler's transformations are employed, followed by the implementation of a finite difference scheme for numerical solutions. The methodology further integrates a machine learning-based neural network to predict the skin friction under the influence of roughness-induced perturbations, ensuring computational efficiency and improved generalization. The study yields several novel findings. Notably, the presence of surface roughness introduces the wavelike modulations in the local skin friction coefficient. It is also observed that nonlinear convective interactions, enhanced by temperature gradients and vortex viscosity parameters, significantly intensify near-wall velocity gradients. Moreover, key physical quantities are correlated with governing parameters using power-law relationships, providing generalized predictive models. The validation of the numerical results is achieved through consistency checks with the existing limiting solutions and convergence analysis, ensuring the reliability of the proposed computational framework.
基金supported by the National Natural Science Foundation of China(No.62464010)Spring City Plan-Special Program for Young Talents(K202005007)+2 种基金Yunnan Talents Support Plan for Young Talents(XDYC-QNRC-2022-0482)Yunnan Local Colleges Applied Basic Research Projects(202101BA070001-138)Frontier Research Team of Kunming University 2023.
文摘Rechargeable Zn/Sn-air batteries have received considerable attention as promising energy storage devices.However,the electrochemical performance of these batteries is significantly constrained by the sluggish electrocatalytic reaction kinetics at the cathode.The integration of light energy into Zn/Sn-air batteries is a promising strategy for enhancing their performance.However,the photothermal and photoelectric effects generate heat in the battery under prolonged solar irradiation,leading to air cathode instability.This paper presents the first design and synthesis of Ni_(2)-1,5-diamino-4,8-dihydroxyanthraquinone(Ni_(2)DDA),an electronically conductiveπ-d conjugated metal-organic framework(MOF).Ni_(2)DDA exhibits both photoelectric and photothermal effects,with an optical band gap of~1.14 eV.Under illumination,Ni_(2)DDA achieves excellent oxygen evolution reaction performance(with an overpotential of 245 mV vs.reversible hydrogen electrode at 10 mA cm^(−2))and photothermal stability.These properties result from the synergy between the photoelectric and photothermal effects of Ni_(2)DDA.Upon integration into Zn/Sn-air batteries,Ni_(2)DDA ensures excellent cycling stability under light and exhibits remarkable performance in high-temperature environments up to 80℃.This study experimentally confirms the stable operation of photo-assisted Zn/Sn-air batteries under high-temperature conditions for the first time and provides novel insights into the application of electronically conductive MOFs in photoelectrocatalysis and photothermal catalysis.
文摘This paper aims to explore and quantify the nonlinear vibration response of tri-directional functionally graded sandwich(3D-FGSW)plates partially supported by a Pasternak foundation(PF)subjected to blast loading(BL).A key objective is to develop a computationally efficient finite element framework capable of accurately capturing the complex behavior of 3D-FGSW plates.The studied configuration features a two-dimensional functionally graded material(2D-FGM)core between two threedimensional functionally graded material(3D-FGM)face layers.Nonlinear geometric effects,including mid-plane stretching,are modeled using von K arm an-type assumptions,and the governing equations are formulated via Hamilton's principle within an improved first-order shear deformation theory(iFSDT).The accuracy and computational efficiency of the proposed method are validated through comparison with existing benchmark solutions.Subsequently,a comprehensive parametric study is carried out to examine the effects of geometric dimensions,material properties,foundation sizes,and boundary conditions(BCs)on the nonlinear vibration of 3D-FGSW plates.The findings of this work are expected to provide valuable insights for the design and manufacturing of advanced sandwich structures subjected to BL.
基金National Natural Science Foundation of China(No.12071370)。
文摘The bipartite containment control problem for heterogeneous nonlinear multi-agent systems(HNMASs)within multi-group networks under signed digraphs is investigated,where the first-order and second-order nonlinear dynamic agents belong to distinct groups.Interactions are cooperative-antagonistic within each group and sign-in-degree balanced across the inter-groups.Firstly,a state feedback control protocol is designed to ensure that the trajectories of followers in diverse groups can converge to distinct convex hulls formed by their corresponding leaders,respectively.As an extension,the bipartite control problem with time-variant formation for the multi-agent system(MAS)is also considered,and a corresponding control protocol with formation compensation vectors is given.Finally,in view of Lyapunov stability theory and matrix inequality,the sufficient conditions for realizing the bipartite containment control are obtained,and several simulations are provided to verify the validity of the above methods.
基金supported by the National Research Foundation of Korea(NRF)funded by the Ministry of Science and ICT(MSIT)(No.RS-2022-00143178)the Ministry of Education(MOE)(Nos.2022R1A6A3A13053896 and 2022R1F1A1074616),Republic of Korea.
文摘Beam-tracking simulations have been extensively utilized in the study of collective beam instabilities in circular accelerators.Traditionally,many simulation codes have relied on central processing unit(CPU)-based methods,tracking on a single CPU core,or parallelizing the computation across multiple cores via the message passing interface(MPI).Although these approaches work well for single-bunch tracking,scaling them to multiple bunches significantly increases the computational load,which often necessitates the use of a dedicated multi-CPU cluster.To address this challenge,alternative methods leveraging General-Purpose computing on Graphics Processing Units(GPGPU)have been proposed,enabling tracking studies on a standalone desktop personal computer(PC).However,frequent CPU-GPU interactions,including data transfers and synchronization operations during tracking,can introduce communication overheads,potentially reducing the overall effectiveness of GPU-based computations.In this study,we propose a novel approach that eliminates this overhead by performing the entire tracking simulation process exclusively on the GPU,thereby enabling the simultaneous processing of all bunches and their macro-particles.Specifically,we introduce MBTRACK2-CUDA,a Compute Unified Device Architecture(CUDA)ported version of MBTRACK2,which facilitates efficient tracking of single-and multi-bunch collective effects by leveraging the full GPU-resident computation.
文摘The dried fruit of Forsythia suspensa(Oleaceae),also known as Forsythia,is a traditional Chinese medicinal herb known for its heat-clearing and detoxifying properties.It is used to disperse nodules,reduce swelling,remove toxins,clear heat,and alleviate wind-heat syndromes.It also has hepatoprotective,anti-inflammatory,antiviral,antibacterial,anticancer,antioxidant,antiaging,and anti-obesity effects,as well as potential therapeutic effects on Alzheimer’s disease and diabetic nephropathy.It is used to treat scrofula,mastitis,wind-heat common cold,and other ailments.The review summarizes the chemical constituents and pharmacological effects of F.suspensa,aiming to provide a scientific foundation for its future development,research,and clinical utilization.
基金Project supported by the National Natural Science Foundation of China(Grant No.12204347)National Key Research and Development Program of China(Grant No.2022YFA1402600)the Fund from Beijing National Laboratory for Condensed Matter Physics(Grant No.2023BNLCMPKF011)。
文摘Kagome magnets are of growing interest due to their topological electronic structures and unconventional magnetic behavior.Here,we report on the anomalous Hall effect(AHE)in the kagome ferromagnet MgMn_(6)Sn_(6),which has a Curie temperature of~290 K and an in-plane easy magnetization axis.Magnetotransport measurements show a positive magnetoresistance(MR)below 50 K,which becomes negative at higher temperatures.An intrinsic anomalous Hall conductivity of 114 S·cm^(-1)is observed in MgMn_(6)Sn_(6) single crystals,consistent with ab initio calculations.Moreover,theoretical predictions indicate that shifting the Fermi level(EF)upward by~70 meV could enhance the AHE to~528 S·cm^(-1).These results position MgMn_(6)Sn_(6) as a promising and tunable platform for exploring topological magnetism and related electronic phenomena.
基金Supported by the National Natural Science Foundation of China(Grant Nos.11961059,1210502)the University Innovation Project of Gansu Province(Grant No.2023B-062)the Gansu Province Basic Research Innovation Group Project(Grant No.23JRRA684).
文摘The goal of this paper is to investigate the long-time dynamics of solutions to a Kirchhoff type suspension bridge equation with nonlinear damping and memory term.For this problem we establish the well-posedness and existence of uniform attractor under some suitable assumptions on the nonlinear term g(u),the nonlinear damping f(u_(t))and the external force h(x,t).Specifically,the asymptotic compactness of the semigroup is verified by the energy reconstruction method.
