Studying the coupling coordination development of new energy vehicles(NEVs)and the ecological environment in China is helpful in promoting the development of NEVs in the country and is of great significance in promoti...Studying the coupling coordination development of new energy vehicles(NEVs)and the ecological environment in China is helpful in promoting the development of NEVs in the country and is of great significance in promoting high-quality development of new energy in China.This paper constructs an evaluation index system for the development of NEVs and the ecological environment.It uses game theory combining weighting model,particle swarm optimized projection tracking evaluation model,coupling coordination degree model,and machine learning algorithms to calculate and analyze the level of coupling coordination development of NEVs and the ecological environment in China from 2010 to 2021,and identifies the driving factors.The research results show that:(i)From 2010 to 2021,the development index of NEVs in China has steadily increased from 0.085 to 0.634,while the ecological environment level index significantly rose from 0.170 to 0.884,reflecting the continuous development of China in both NEVs and the ecological environment.(ii)From 2010 to 2012,the two systems—new energy vehicle(NEV)development and the ecological environment—were in a period of imbalance and decline.From 2013 to 2016,they underwent a transition period,and from 2017 to 2021,they entered a period of coordinated development showing a trend of benign and continuous improvement.By 2021,they reached a good level of coordination.(iii)Indicators such as the number of patents granted for NEVs,water consumption per unit of GDP,and energy consumption per unit of GDP are the main driving factors affecting the coupling coordination development of NEVs and the ecological environment in China.展开更多
Ferroelectric film materials have attracted significant interest due to their potential for harvesting various forms ofclean energy from natural environmental sources.However,the photoelectric performance of these mat...Ferroelectric film materials have attracted significant interest due to their potential for harvesting various forms ofclean energy from natural environmental sources.However,the photoelectric performance of these materials isfrequently constrained by heat generation during light absorption,resulting in significant thermal losses.Most offerroelectric films produce photocurrent and thermocurrent with opposite polarity,thus weakening the coupledphoto-thermoelectric output of the devices.Here we report on a LaNiO_(3)/BiMn_(2)O_(5)(BMO)/ITO ferroelectric film toproduce photocurrent and thermocurrent with the same polarity.The polarity of the photocurrent generated bythe BMO film is shown to be determined solely by the direction of spontaneous polarization,overcoming thedetrimental effect of Schottky barrier for energy harvesting in device.We propose a new strategy to enhance thecoupling factor,thereby offering valuable new insights for optimizing the utilization of ferroelectric materials inboth light and heat energy applications.展开更多
Both the complex geometrical morphology of rough-walled rock fractures and the nonlinearity of fluid flow contribute to resistance in fluid flow through rock fractures.The interactions of the shear-flow process furthe...Both the complex geometrical morphology of rough-walled rock fractures and the nonlinearity of fluid flow contribute to resistance in fluid flow through rock fractures.The interactions of the shear-flow process further complicate the characterisation of flow behaviours in rock fractures.In this study,an improved friction factor model involving both the effects of viscous and inertial forces is presented based on the Forchheimer equation.The model incorporates two key variables,i.e.Reynolds number and relative roughness,which reflect the effects of flow regimes and fracture roughness,respectively.The changes in geometrical parameters induced by shearing are considered,with the peak asperity height predicted through a correlation with post-peak roughness degradation.The hydraulic aperture during shearing is estimated using a suggested equation that accounts for the mobilised contact area ratio and variable aperture distribution.The parametric sensitivity analysis reveals that shear-induced changes in fracture geometry enhance the flow nonlinearity in rock fractures.The model performs well in predicting the friction factor based on two validation criteria.Then,the proposed friction factor model is incorporated into the three-dimensional distinct element code(3DEC)in the form of the Darcy-Weisbach equation.Coupled with the numerically implemented mechanical model and hydraulic aperture prediction model,numerical simulations of coupled shear-flow processes in single rock fractures are conducted.The simulation outcomes are validated through comparison with the experimental results,showing acceptable agreement and demonstrating that the numerical model is capable of accurately evaluating the hydro-mechanical coupling behaviour during the shearing of rock fractures.展开更多
Rural resilience,a core capability for addressing systemic risks and enabling sustainable development,is increasingly vital to promoting urban-rural integrated development and rural revitalization strategies.However,c...Rural resilience,a core capability for addressing systemic risks and enabling sustainable development,is increasingly vital to promoting urban-rural integrated development and rural revitalization strategies.However,current research lacks exploration of the collaborative mechanisms between rural economic resilience(RER)and rural social resilience(RSR)in ecologically vulnerable areas.Based on the practical context of rural sustainable development in such regions,this study investigates the interaction between RER and RSR from a resilience coordination perspective.In this paper,a rural resilience evaluation framework for collaborative development of economic and social resilience was established.By employing the coupling coordination degree model,obstacle degree model,and equilibrium entropy model,this paper examines the synergies,constraints,and potential of rural resilience subsystems in Jinchang City,Gansu Province,China,in 2020.The results reveal that:1)RER contributes to RSR by stabilizing the economy,enhancing community adaptability,and driving modernization.In turn,RSR strengthens RER by mitigating instability,building social capital,and fostering confidence—together forming a mutually reinforcing coupling mechanism.2)The rural economic and social resilience level in Jinchang City remains generally low with spatially clustered patterns,while the coupling coordination degree is at an intermediate level overall,with 62.59%of villages exhibiting unbalanced development between rural economic and social resilience.3)RER and RSR demonstrate synergistic degradation in ecologically vulnerable areas,where low-level rural economic and social resilience induce integrated systemic deterioration.4)Considering the unbalanced development of rural economic and social resilience in ecologically fragile areas,differentiated coordination pathways are proposed for three village typologies:RER-lagging villages,RSR-lagging villages,and villages where RER and RSR develop synchronously but lack effective coordination.These findings offer spatial governance strategies and practical guidance for enhancing rural resilience and advancing sustainable development in ecologically vulnerable regions.展开更多
Self-trapping excitons(STEs) emission in metal halides has been a matter of interest, correlating with the strength of electron-phonon coupling in the lattice, which are usually caused by ions with ns~2 electronic str...Self-trapping excitons(STEs) emission in metal halides has been a matter of interest, correlating with the strength of electron-phonon coupling in the lattice, which are usually caused by ions with ns~2 electronic structure. In this work, Sb^(3+)/Te^(4+)ions doped Zn-based halide single crystals(SCs) with two STEs emissions have been synthesized and the possibility of its anti-counterfeiting application was explored.Further, the relationship between the strength of electron-phonon coupling and photoluminescence quantum yields(PLQYs) for STEs in a series of metal halides has been studied. And the semi-empirical range of the Huang-Rhys factors(S) for metal halides with excellent photoluminescence(PL) property has been summarized. This work provides ideas for further research into the relationship between luminescence performance and electron-phonon coupling of metal halides, and also provides a reference for designing the metal halides with high PLQYs.展开更多
The accepted doping ion in Ti^(4+)-site of PbZr_(y)Ti_(1–y)O_(3)(PZT)-based piezoelectric ceramics is a well-known method to increase mechanical quality factor(Q_(m)),since the acceptor coupled by oxygen vacancy beco...The accepted doping ion in Ti^(4+)-site of PbZr_(y)Ti_(1–y)O_(3)(PZT)-based piezoelectric ceramics is a well-known method to increase mechanical quality factor(Q_(m)),since the acceptor coupled by oxygen vacancy becomes defect dipole,which prevents the domain rotation.In this field,a serious problem is that generally,Qm decreases as the temperature(T)increases,since the oxygen vacancies are decoupled from the defect dipoles.In this work,Q_(m) of Pb_(0.95)Sr_(0.05)(Zr_(0.53)Ti_(0.47))O_(3)(PSZT)ceramics doped by 0.40%Fe_(2)O_(3)(in mole)abnormally increases as T increases,of which the Qm and piezoelectric coefficient(d_(33))at room temperature and Curie temperature(TC)are 507,292 pC/N,and 345℃,respectively.The maximum Qm of 824 was achieved in the range of 120–160℃,which is 62.52%higher than that at room temperature,while the dynamic piezoelectric constant(d_(31))was just slightly decreased by 3.85%.X-ray diffraction(XRD)and piezoresponse force microscopy results show that the interplanar spacing and the fine domains form as temperature increases,and the thermally stimulated depolarization current shows that the defect dipoles are stable even the temperature up to 240℃.It can be deduced that the aggregation of oxygen vacancies near the fine domains and defect dipole can be stable up to 240℃,which pins domain rotation,resulting in the enhanced Q_(m) with the increasing temperature.These results give a potential path to design high Q_(m) at high temperature.展开更多
The Taihang Mountains in North China are an important carbon-water ecosystem service supply area.Understanding the coupling effect and influencing mechanisms of mountain carbon sequestration as well as water conservat...The Taihang Mountains in North China are an important carbon-water ecosystem service supply area.Understanding the coupling effect and influencing mechanisms of mountain carbon sequestration as well as water conservation is essential for regional eco-logical restoration and sustainable development.In this study,we utilized models such as the coupled coordination degree model,the random forest and Geodetector to analyze the spa-tio-temporal changes as well as driving factors of carbon sequestration-water conservation coupling coordination in the Taihang Mountains.The results show that:(1)From 1990 to 2020,the carbon sequestration and water conservation capacity of the Taihang Mountains exhibited a spatial pattern with higher values in the southeast and central regions,while lower values in the northwest region.(2)The average coupling coordination degree from 1990 to 2020 was O.23,which was overall low,with a fluctuating decreasing-rising-decreasing trend over time.The coupling coordination degree exhibited a pattern that is high in the middle and low in the periphery,with a fluctuating distribution that initially decreases and then increases with the increasing altitude.The overall trend of coupling coordination is degradation,with concen-trated degradation in the northwest mountainous regions.(3)Precipitation and soil texture were identified as the main driving factors influencing coupling coordination,with the interac-tion between precipitation and soil sand content showing the strongest explanatory power,while that among topography,vegetation and human activities had relatively low explanatory power.Therefore,enhanced protection and the continuous monitoring of vegetation and soil environments in the Taihang Mountains are essential,with particular emphasis on ecological restoration in areas experiencing a persistent degradation of carbon-water coupling.This study can provide assistance in monitoring and managing carbon sink and water resources in the mountains,meanwhile mitigating potential adverse impacts on human well-being.展开更多
In this paper,we present the applications of Boundary Element Method(BEM) to simulate the electro-mechanical coupling responses of Micro-Electro-Mechanical systems(MEMS). The algorithm is programmed in our research gr...In this paper,we present the applications of Boundary Element Method(BEM) to simulate the electro-mechanical coupling responses of Micro-Electro-Mechanical systems(MEMS). The algorithm is programmed in our research group based on BEM modeling for electrostatics and elastostatics.Good agreement is shown while the simulation results of the pull-in voltages are compared with the theoretical/experimental ones for some examples.展开更多
The model of a locally resonant (LR) epoxy/PZT-4 phononic crystal (PC)nanobeam with “spring-mass” resonators periodically attached to epoxy is proposed. The corresponding band structures are calculated by coupling E...The model of a locally resonant (LR) epoxy/PZT-4 phononic crystal (PC)nanobeam with “spring-mass” resonators periodically attached to epoxy is proposed. The corresponding band structures are calculated by coupling Euler beam theory, nonlocal piezoelectricity theory and plane wave expansion (PWE) method. Three complete band gaps with the widest total width less than 10GHz can be formed in the proposed nanobeam by comprehensively comparing the band structures of three kinds of LR PC nanobeams with resonators attached or not. Furthermore, influencing rules of the coupling fields between electricity and mechanics,“spring-mass” resonator, nonlocal effect and different geometric parameters on the first three band gaps are discussed and summarized. All the investigations are expected to be applied to realize the active control of vibration in the region of ultrahigh frequency.展开更多
A new calculation formula of THM coupling stress intensity factor was derived by the boundary collocation method, in which an additional constant stress function was successfully introduced for the cracked specimen wi...A new calculation formula of THM coupling stress intensity factor was derived by the boundary collocation method, in which an additional constant stress function was successfully introduced for the cracked specimen with hydraulic pressure applied on its crack surface. Based on the newly derived formula, THM coupling fracture modes （including tensile, shear and mixed fracture mode） can be predicted by a new fracture criterion of stress intensity factor ratio, where the maximum axial load was measured by self-designed THM coupling fracture test. SEM analyses of THM coupling fractured surface indicate that the higher the temperature and hydraulic pressure are and the lower the confining pressure is, the more easily the intergranular （tension） fracture occurs. The transgranular （shear） fracture occurs in the opposite case while the mixed-mode fracture occurs in the middle case. The tested THM coupling fracture mechanisms are in good agreement with the predicted THM coupling fracture modes, which can verify correction of the newly-derived THM coupling stress intensity factor formula.展开更多
The study presents a comprehensive coupled thermo-bio-chemo-hydraulic(T-BCH)modeling framework for stabilizing soils using microbially induced calcite precipitation(MICP).The numerical model considers relevant multiph...The study presents a comprehensive coupled thermo-bio-chemo-hydraulic(T-BCH)modeling framework for stabilizing soils using microbially induced calcite precipitation(MICP).The numerical model considers relevant multiphysics involved in MICP,such as bacterial ureolytic activities,biochemical reactions,multiphase and multicomponent transport,and alteration of the porosity and permeability.The model incorporates multiphysical coupling effects through well-established constitutive relations that connect parameters and variables from different physical fields.It was implemented in the open-source finite element code OpenGeoSys(OGS),and a semi-staggered solution strategy was designed to solve the couplings,allowing for flexible model settings.Therefore,the developed model can be easily adapted to simulate MICP applications in different scenarios.The numerical model was employed to analyze the effect of various factors,including temperature,injection strategies,and application scales.Besides,a TBCH modeling study was conducted on the laboratory-scale domain to analyze the effects of temperature on urease activity and precipitated calcium carbonate.To understand the scale dependency of MICP treatment,a large-scale heterogeneous domain was subjected to variable biochemical injection strategies.The simulations conducted at the field-scale guided the selection of an injection strategy to achieve the desired type and amount of precipitation.Additionally,the study emphasized the potential of numerical models as reliable tools for optimizing future developments in field-scale MICP treatment.The present study demonstrates the potential of this numerical framework for designing and optimizing the MICP applications in laboratory-,prototype-,and field-scale scenarios.展开更多
Using a transient thermoreflectance （TTR） technique, several Au films with different thicknesses on glass and SiC substrates are measured for thermal characterization of metMlic nano-films, including the electron ph...Using a transient thermoreflectance （TTR） technique, several Au films with different thicknesses on glass and SiC substrates are measured for thermal characterization of metMlic nano-films, including the electron phonon coupling factor G, interfazial thermal resistance R, and thermal conductivity Ks of the substrate. The rear heating-front detecting （RF） method is used to ensure the femtosecond temporal resolution. An intense laser beam is focused on the rear surface to heat the film, and another weak laser beam is focused on the very spot of the front surface to detect the change in the electron temperature. By varying the optical path delay between the two beams, a complete electron temperature profile can be scanned. Different from the normally used single-layer model, the double-layer model involving interfaciM thermal resistance is studied here. The electron temperature cooling profile can be affected by the electron energy transfer into the substrate or the electron-phonon interactions in the metallic films. For multiple-target optimization, the genetic algorithm （GA） is used to obtain both G and R. The experimental result gives a deep understanding of the mechanism of ultra-fast heat transfer in metals.展开更多
The coupling model of major influence factors such state affecting the chloride diffusion process in concrete is as environmental relative humidity, load-induced crack and stress discussed. The probability distributio...The coupling model of major influence factors such state affecting the chloride diffusion process in concrete is as environmental relative humidity, load-induced crack and stress discussed. The probability distributions of the critical chloride concentration Cc, the chloride diffusion coefficient D, and the surface chloride concentration Cs were determined based on the collected natural exposure data. And the estimation of probability of corrosion initiation considering the coupling effects of influence factors is presented. It is found that the relative humidity and curing time are the most effective factors affecting the probability of corrosion initiation before and after 10 years of exposure time. At the same exposure time, the influence of load-induced crack and stress state on the probability of corrosion initiation is obvious, in which the effect of crack is the most one展开更多
The transmission of transverse vibrational energy of a vertically rigid beam plate coupled structure is analyzed to get the theoretical results of coupling loss factor(CLF), a very important parameter in statistical ...The transmission of transverse vibrational energy of a vertically rigid beam plate coupled structure is analyzed to get the theoretical results of coupling loss factor(CLF), a very important parameter in statistical energy analysis(SEA). The modal analysis method is used to discuss the vibration energy of the typical model, as well as the power flow between the two subsystems. Furthermore, the resolution to the coupling loss factor is also derived and compared with the measured values. The analytical results of the coupling loss factor agree with the measured ones fully, this new resolution is significant for the application of SEA.展开更多
Within the linear framework,the Modal Electromechanical Coupling Factor(MEMCF)is an important indicator to quantify the dynamic conversion of mechanical energy and electrical energy of piezoelectric structures.It is a...Within the linear framework,the Modal Electromechanical Coupling Factor(MEMCF)is an important indicator to quantify the dynamic conversion of mechanical energy and electrical energy of piezoelectric structures.It is also an important tool to guide the piezoelectric damping design of linear structures.Advanced aircraft often fly in maneuvers,and the variable working conditions induce drastic changes in the load level on structures.Geometric and contact nonlinearities of thin-walled structures and joint structures are often activated.To achieve a good vibration reduction effect covering all working conditions,one cannot directly use linear electromechanical coupling theory to instruct the piezoelectric damping design for nonlinear structures.Therefore,this paper defines the Nonlinear Modal Electromechanical Coupling Factor(NMEMCF)and proposes the corresponding numerical method for the first time to quantitatively evaluate the electromechanical coupling capability of nonlinear piezoelectric structures.Three candidate definitions of the NMEMCF are given,including two frequency definitions and one energy definition.The energy definition is the most promising one.It is not only applicable to both conservative and dissipative nonlinear structures but also compatible with the linear MEMCF.In addition,based on the energy formula,the NMEMCF can be obtained by only performing one nonlinear modal analysis in the open-circuit state.The analytical findings and the numerical tool are validated against two piezoelectric structures with different types of nonlinearities.A strong correlation among the NMEMCF,geometric parameters,and energy dissipation is observed.The results confirm that the proposed NMEMCF captures the physics of the electromechanical coupling phenomenon associated with nonlinear piezoelectric structures and can be used as an essential design indicator of piezoelectric damping,especially for variable working conditions.展开更多
This paper presents an efficient meshless method for analyzing cracked piezoelectric structures subjected to mechanical and electrical loading. In this method, an element free Galerkin （EFG） formulation, an enriched...This paper presents an efficient meshless method for analyzing cracked piezoelectric structures subjected to mechanical and electrical loading. In this method, an element free Galerkin （EFG） formulation, an enriched basic function and some special shape functions that contain discontinuous derivatives are employed. Based on the moving least squares （MLS） interpolation approach, the EFG method is one of the promising methods for dealing with problems involving progressive crack growth. Since the method is meshless and no element connectivity data are needed, the burdensome remeshing procedure required in the conventional finite element method （FEM） is avoided. The numerical results show that the proposed method can yield an accurate near-tip stress field in an infinite piezoelectric plate containing an interior hole. In another example studying a ceramic multilayer actuator, the proposed model was found to be accurate in the simulation of stress and electric field concentrations arround the abrupt end of an internal electrode.展开更多
Combined with the parameters of the production process of a steel factory, numerical simulations for a new ladle from preheating to turnover are conducted using the finite element analysis system software （ANSYS）. T...Combined with the parameters of the production process of a steel factory, numerical simulations for a new ladle from preheating to turnover are conducted using the finite element analysis system software （ANSYS）. The measured data proved that the simulated results are reliable. The effects of preheating time, thermal cycling times, and empty package time on steel temperature are calculated, an ideal preheating time is provided, besides, based on the analysis of a single factor and use the nonlinear analysis method, a steel temperature compensating model with di- versified coupling factors is proposed, with the largest error of the present coupling model at 1. 462 ~C, and the er- rors between actual and target steel temperature in tundish after the model is applied to practical production are basi- cally controlled within -4-6 ~C, which can meet the accuracy of the manufacturer and has a practical guiding significance for the production in steelmaking workshops.展开更多
We have investigated the transverse mode pattern and the optical field confinement factor of gallium nitride （GaN） laser diodes （LDs） theoretically. For the particular LD structure, composed of approximate 4 μm t...We have investigated the transverse mode pattern and the optical field confinement factor of gallium nitride （GaN） laser diodes （LDs） theoretically. For the particular LD structure, composed of approximate 4 μm thick n-GaN substrate layer, the maximum optical confinement factor was found to be corresponding to the 5^th order transverse mode, the so-called lasing mode. Moreover, the value of the maximum confinement factor varies periodically when increasing the n-side GaN layer thickness, which simultaneously changes and increases the oscillation mode order of the GaN LD caused by the effects of mode coupling. The effects of the thickness and the average composition of Al in the AlGaN/GaN superlat.tice on the optical confinement factor are also presented. Finally, the mode coupling and optimization of the layers in the GaN-based LD are discussed.展开更多
In order to accurately simulate the diffusion of chloride ion in the existing concrete bridge and acquire the precise chloride ion concentration at given time, a cellular automata （CA）-based model is proposed. The p...In order to accurately simulate the diffusion of chloride ion in the existing concrete bridge and acquire the precise chloride ion concentration at given time, a cellular automata （CA）-based model is proposed. The process of chloride ion diffusion is analyzed by the CA-based method and a nonlinear solution of the Fick＇s second law is obtained. Considering the impact of various factors such as stress states, temporal and spatial variability of diffusion parameters and water-cement ratio on the process of chloride ion diffusion, the model of chloride ion diffusion under multi-factor coupling actions is presented. A chloride ion penetrating experiment reported in the literature is used to prove the effectiveness and reasonability of the present method, and a T-type beam is taken as an illustrative example to analyze the process of chloride ion diffusion in practical application. The results indicate that CA-based method can simulate the diffusion of chloride ion in the concrete structures with acceptable precision.展开更多
Heavy-equipment airdrop is a highly risky procedure that has a complicated system due to the secluded and complex nature of factors＇ coupling. As a result, it is difficult to study the modeling and safety simulation ...Heavy-equipment airdrop is a highly risky procedure that has a complicated system due to the secluded and complex nature of factors＇ coupling. As a result, it is difficult to study the modeling and safety simulation of this system. The dynamic model of the heavy-equipment airdrop is based on the Lagrange analytical mechanics, which has all the degrees of freedom and can accurately pinpoint the real-time coordinates and attitude of the carrier with its cargo. Unfavorable conditions accounted in the factors＇ models, including aircraft malfunctions and adverse environments, are established from a man-machine-environment perspective. Subsequently, a virtual simulation system for the safety research of the multi-factor coupling heavy-equipment airdrop is developed through MATLAB/Simulink, C language and Flightgear software. To verify the veracity of the theory, the verification model is built based on dynamic software ADAMS. Finally, the emulation is put to the test with the input of realistic accident variables to ascertain its feasibility and validity of this method.展开更多
基金Supported by the Postgraduate Research&Practice Innovation Program of Jiangsu Province(KYCX24_0102)the China Scholarship Council Program(202406190114)。
文摘Studying the coupling coordination development of new energy vehicles(NEVs)and the ecological environment in China is helpful in promoting the development of NEVs in the country and is of great significance in promoting high-quality development of new energy in China.This paper constructs an evaluation index system for the development of NEVs and the ecological environment.It uses game theory combining weighting model,particle swarm optimized projection tracking evaluation model,coupling coordination degree model,and machine learning algorithms to calculate and analyze the level of coupling coordination development of NEVs and the ecological environment in China from 2010 to 2021,and identifies the driving factors.The research results show that:(i)From 2010 to 2021,the development index of NEVs in China has steadily increased from 0.085 to 0.634,while the ecological environment level index significantly rose from 0.170 to 0.884,reflecting the continuous development of China in both NEVs and the ecological environment.(ii)From 2010 to 2012,the two systems—new energy vehicle(NEV)development and the ecological environment—were in a period of imbalance and decline.From 2013 to 2016,they underwent a transition period,and from 2017 to 2021,they entered a period of coordinated development showing a trend of benign and continuous improvement.By 2021,they reached a good level of coordination.(iii)Indicators such as the number of patents granted for NEVs,water consumption per unit of GDP,and energy consumption per unit of GDP are the main driving factors affecting the coupling coordination development of NEVs and the ecological environment in China.
基金supported by the National Natural Science Foundation of China(grant no.52072041)the Beijing Natural Science Foundation(grant no.JQ21007).
文摘Ferroelectric film materials have attracted significant interest due to their potential for harvesting various forms ofclean energy from natural environmental sources.However,the photoelectric performance of these materials isfrequently constrained by heat generation during light absorption,resulting in significant thermal losses.Most offerroelectric films produce photocurrent and thermocurrent with opposite polarity,thus weakening the coupledphoto-thermoelectric output of the devices.Here we report on a LaNiO_(3)/BiMn_(2)O_(5)(BMO)/ITO ferroelectric film toproduce photocurrent and thermocurrent with the same polarity.The polarity of the photocurrent generated bythe BMO film is shown to be determined solely by the direction of spontaneous polarization,overcoming thedetrimental effect of Schottky barrier for energy harvesting in device.We propose a new strategy to enhance thecoupling factor,thereby offering valuable new insights for optimizing the utilization of ferroelectric materials inboth light and heat energy applications.
基金supported by the China Scholarship Council(CSC)(Grant No.202006060033).
文摘Both the complex geometrical morphology of rough-walled rock fractures and the nonlinearity of fluid flow contribute to resistance in fluid flow through rock fractures.The interactions of the shear-flow process further complicate the characterisation of flow behaviours in rock fractures.In this study,an improved friction factor model involving both the effects of viscous and inertial forces is presented based on the Forchheimer equation.The model incorporates two key variables,i.e.Reynolds number and relative roughness,which reflect the effects of flow regimes and fracture roughness,respectively.The changes in geometrical parameters induced by shearing are considered,with the peak asperity height predicted through a correlation with post-peak roughness degradation.The hydraulic aperture during shearing is estimated using a suggested equation that accounts for the mobilised contact area ratio and variable aperture distribution.The parametric sensitivity analysis reveals that shear-induced changes in fracture geometry enhance the flow nonlinearity in rock fractures.The model performs well in predicting the friction factor based on two validation criteria.Then,the proposed friction factor model is incorporated into the three-dimensional distinct element code(3DEC)in the form of the Darcy-Weisbach equation.Coupled with the numerically implemented mechanical model and hydraulic aperture prediction model,numerical simulations of coupled shear-flow processes in single rock fractures are conducted.The simulation outcomes are validated through comparison with the experimental results,showing acceptable agreement and demonstrating that the numerical model is capable of accurately evaluating the hydro-mechanical coupling behaviour during the shearing of rock fractures.
基金Under the auspices of National Natural Science Foundation of China(No.42271222)Natural Science Foundation of Gansu Province(No.22JR5RA130)。
文摘Rural resilience,a core capability for addressing systemic risks and enabling sustainable development,is increasingly vital to promoting urban-rural integrated development and rural revitalization strategies.However,current research lacks exploration of the collaborative mechanisms between rural economic resilience(RER)and rural social resilience(RSR)in ecologically vulnerable areas.Based on the practical context of rural sustainable development in such regions,this study investigates the interaction between RER and RSR from a resilience coordination perspective.In this paper,a rural resilience evaluation framework for collaborative development of economic and social resilience was established.By employing the coupling coordination degree model,obstacle degree model,and equilibrium entropy model,this paper examines the synergies,constraints,and potential of rural resilience subsystems in Jinchang City,Gansu Province,China,in 2020.The results reveal that:1)RER contributes to RSR by stabilizing the economy,enhancing community adaptability,and driving modernization.In turn,RSR strengthens RER by mitigating instability,building social capital,and fostering confidence—together forming a mutually reinforcing coupling mechanism.2)The rural economic and social resilience level in Jinchang City remains generally low with spatially clustered patterns,while the coupling coordination degree is at an intermediate level overall,with 62.59%of villages exhibiting unbalanced development between rural economic and social resilience.3)RER and RSR demonstrate synergistic degradation in ecologically vulnerable areas,where low-level rural economic and social resilience induce integrated systemic deterioration.4)Considering the unbalanced development of rural economic and social resilience in ecologically fragile areas,differentiated coordination pathways are proposed for three village typologies:RER-lagging villages,RSR-lagging villages,and villages where RER and RSR develop synchronously but lack effective coordination.These findings offer spatial governance strategies and practical guidance for enhancing rural resilience and advancing sustainable development in ecologically vulnerable regions.
基金supported by the financial aid from the National Natural Science Foundation of China (No. 22271273)International Partnership Program of Chinese Academy of Sciences (No. 121522KYSB20190022)。
文摘Self-trapping excitons(STEs) emission in metal halides has been a matter of interest, correlating with the strength of electron-phonon coupling in the lattice, which are usually caused by ions with ns~2 electronic structure. In this work, Sb^(3+)/Te^(4+)ions doped Zn-based halide single crystals(SCs) with two STEs emissions have been synthesized and the possibility of its anti-counterfeiting application was explored.Further, the relationship between the strength of electron-phonon coupling and photoluminescence quantum yields(PLQYs) for STEs in a series of metal halides has been studied. And the semi-empirical range of the Huang-Rhys factors(S) for metal halides with excellent photoluminescence(PL) property has been summarized. This work provides ideas for further research into the relationship between luminescence performance and electron-phonon coupling of metal halides, and also provides a reference for designing the metal halides with high PLQYs.
基金National Natural Science Foundation of China(U2241242)National Key R&D Program of China(2023YFB3812000,2021YFA0716502)。
文摘The accepted doping ion in Ti^(4+)-site of PbZr_(y)Ti_(1–y)O_(3)(PZT)-based piezoelectric ceramics is a well-known method to increase mechanical quality factor(Q_(m)),since the acceptor coupled by oxygen vacancy becomes defect dipole,which prevents the domain rotation.In this field,a serious problem is that generally,Qm decreases as the temperature(T)increases,since the oxygen vacancies are decoupled from the defect dipoles.In this work,Q_(m) of Pb_(0.95)Sr_(0.05)(Zr_(0.53)Ti_(0.47))O_(3)(PSZT)ceramics doped by 0.40%Fe_(2)O_(3)(in mole)abnormally increases as T increases,of which the Qm and piezoelectric coefficient(d_(33))at room temperature and Curie temperature(TC)are 507,292 pC/N,and 345℃,respectively.The maximum Qm of 824 was achieved in the range of 120–160℃,which is 62.52%higher than that at room temperature,while the dynamic piezoelectric constant(d_(31))was just slightly decreased by 3.85%.X-ray diffraction(XRD)and piezoresponse force microscopy results show that the interplanar spacing and the fine domains form as temperature increases,and the thermally stimulated depolarization current shows that the defect dipoles are stable even the temperature up to 240℃.It can be deduced that the aggregation of oxygen vacancies near the fine domains and defect dipole can be stable up to 240℃,which pins domain rotation,resulting in the enhanced Q_(m) with the increasing temperature.These results give a potential path to design high Q_(m) at high temperature.
基金Special Program for Survey of National Basic Scientific and Technological Resources,No.2021FY00802。
文摘The Taihang Mountains in North China are an important carbon-water ecosystem service supply area.Understanding the coupling effect and influencing mechanisms of mountain carbon sequestration as well as water conservation is essential for regional eco-logical restoration and sustainable development.In this study,we utilized models such as the coupled coordination degree model,the random forest and Geodetector to analyze the spa-tio-temporal changes as well as driving factors of carbon sequestration-water conservation coupling coordination in the Taihang Mountains.The results show that:(1)From 1990 to 2020,the carbon sequestration and water conservation capacity of the Taihang Mountains exhibited a spatial pattern with higher values in the southeast and central regions,while lower values in the northwest region.(2)The average coupling coordination degree from 1990 to 2020 was O.23,which was overall low,with a fluctuating decreasing-rising-decreasing trend over time.The coupling coordination degree exhibited a pattern that is high in the middle and low in the periphery,with a fluctuating distribution that initially decreases and then increases with the increasing altitude.The overall trend of coupling coordination is degradation,with concen-trated degradation in the northwest mountainous regions.(3)Precipitation and soil texture were identified as the main driving factors influencing coupling coordination,with the interac-tion between precipitation and soil sand content showing the strongest explanatory power,while that among topography,vegetation and human activities had relatively low explanatory power.Therefore,enhanced protection and the continuous monitoring of vegetation and soil environments in the Taihang Mountains are essential,with particular emphasis on ecological restoration in areas experiencing a persistent degradation of carbon-water coupling.This study can provide assistance in monitoring and managing carbon sink and water resources in the mountains,meanwhile mitigating potential adverse impacts on human well-being.
基金The project supported by the 973 Program (G1999033108)the National Natural Science Foundation of China (10125211)
文摘In this paper,we present the applications of Boundary Element Method(BEM) to simulate the electro-mechanical coupling responses of Micro-Electro-Mechanical systems(MEMS). The algorithm is programmed in our research group based on BEM modeling for electrostatics and elastostatics.Good agreement is shown while the simulation results of the pull-in voltages are compared with the theoretical/experimental ones for some examples.
基金supported by the National Natural Science Foundation of China(51979130,11847009)the Young Elite Scientists Sponsorship Program by CAST(2022QNRC001)+1 种基金the Natural Science Foundation of Jiangsu Higher Education Institutions of China(22KJB580005)the Postgraduate Research&Practice Innovation Program of Jiangsu Province(SJCX221961)。
文摘The model of a locally resonant (LR) epoxy/PZT-4 phononic crystal (PC)nanobeam with “spring-mass” resonators periodically attached to epoxy is proposed. The corresponding band structures are calculated by coupling Euler beam theory, nonlocal piezoelectricity theory and plane wave expansion (PWE) method. Three complete band gaps with the widest total width less than 10GHz can be formed in the proposed nanobeam by comprehensively comparing the band structures of three kinds of LR PC nanobeams with resonators attached or not. Furthermore, influencing rules of the coupling fields between electricity and mechanics,“spring-mass” resonator, nonlocal effect and different geometric parameters on the first three band gaps are discussed and summarized. All the investigations are expected to be applied to realize the active control of vibration in the region of ultrahigh frequency.
基金Project(11072269)supported by the National Natural Science Foundation of ChinaProject(20090162110066)supported by the Research Fund for the Doctoral Program of Higher Education of China
文摘A new calculation formula of THM coupling stress intensity factor was derived by the boundary collocation method, in which an additional constant stress function was successfully introduced for the cracked specimen with hydraulic pressure applied on its crack surface. Based on the newly derived formula, THM coupling fracture modes （including tensile, shear and mixed fracture mode） can be predicted by a new fracture criterion of stress intensity factor ratio, where the maximum axial load was measured by self-designed THM coupling fracture test. SEM analyses of THM coupling fractured surface indicate that the higher the temperature and hydraulic pressure are and the lower the confining pressure is, the more easily the intergranular （tension） fracture occurs. The transgranular （shear） fracture occurs in the opposite case while the mixed-mode fracture occurs in the middle case. The tested THM coupling fracture mechanisms are in good agreement with the predicted THM coupling fracture modes, which can verify correction of the newly-derived THM coupling stress intensity factor formula.
基金support from the OpenGeoSys communitypartially funded by the Prime Minister Research Fellowship,Ministry of Education,Government of India with the project number SB21221901CEPMRF008347.
文摘The study presents a comprehensive coupled thermo-bio-chemo-hydraulic(T-BCH)modeling framework for stabilizing soils using microbially induced calcite precipitation(MICP).The numerical model considers relevant multiphysics involved in MICP,such as bacterial ureolytic activities,biochemical reactions,multiphase and multicomponent transport,and alteration of the porosity and permeability.The model incorporates multiphysical coupling effects through well-established constitutive relations that connect parameters and variables from different physical fields.It was implemented in the open-source finite element code OpenGeoSys(OGS),and a semi-staggered solution strategy was designed to solve the couplings,allowing for flexible model settings.Therefore,the developed model can be easily adapted to simulate MICP applications in different scenarios.The numerical model was employed to analyze the effect of various factors,including temperature,injection strategies,and application scales.Besides,a TBCH modeling study was conducted on the laboratory-scale domain to analyze the effects of temperature on urease activity and precipitated calcium carbonate.To understand the scale dependency of MICP treatment,a large-scale heterogeneous domain was subjected to variable biochemical injection strategies.The simulations conducted at the field-scale guided the selection of an injection strategy to achieve the desired type and amount of precipitation.Additionally,the study emphasized the potential of numerical models as reliable tools for optimizing future developments in field-scale MICP treatment.The present study demonstrates the potential of this numerical framework for designing and optimizing the MICP applications in laboratory-,prototype-,and field-scale scenarios.
基金supported by the National Natural Science Foundation of China (Grant Nos. 50730006,50976053,and 50906042)
文摘Using a transient thermoreflectance （TTR） technique, several Au films with different thicknesses on glass and SiC substrates are measured for thermal characterization of metMlic nano-films, including the electron phonon coupling factor G, interfazial thermal resistance R, and thermal conductivity Ks of the substrate. The rear heating-front detecting （RF） method is used to ensure the femtosecond temporal resolution. An intense laser beam is focused on the rear surface to heat the film, and another weak laser beam is focused on the very spot of the front surface to detect the change in the electron temperature. By varying the optical path delay between the two beams, a complete electron temperature profile can be scanned. Different from the normally used single-layer model, the double-layer model involving interfaciM thermal resistance is studied here. The electron temperature cooling profile can be affected by the electron energy transfer into the substrate or the electron-phonon interactions in the metallic films. For multiple-target optimization, the genetic algorithm （GA） is used to obtain both G and R. The experimental result gives a deep understanding of the mechanism of ultra-fast heat transfer in metals.
基金Project(50925829) supported by the National Science Fund for Distinguished Young Scholars of ChinaProject(50908148) supported by the National Natural Science Foundation of ChinaProjects(2009-K4-23,2010-11-33) supported by the Research of Ministry of Housing and Urban Rural Development of China
文摘The coupling model of major influence factors such state affecting the chloride diffusion process in concrete is as environmental relative humidity, load-induced crack and stress discussed. The probability distributions of the critical chloride concentration Cc, the chloride diffusion coefficient D, and the surface chloride concentration Cs were determined based on the collected natural exposure data. And the estimation of probability of corrosion initiation considering the coupling effects of influence factors is presented. It is found that the relative humidity and curing time are the most effective factors affecting the probability of corrosion initiation before and after 10 years of exposure time. At the same exposure time, the influence of load-induced crack and stress state on the probability of corrosion initiation is obvious, in which the effect of crack is the most one
文摘The transmission of transverse vibrational energy of a vertically rigid beam plate coupled structure is analyzed to get the theoretical results of coupling loss factor(CLF), a very important parameter in statistical energy analysis(SEA). The modal analysis method is used to discuss the vibration energy of the typical model, as well as the power flow between the two subsystems. Furthermore, the resolution to the coupling loss factor is also derived and compared with the measured values. The analytical results of the coupling loss factor agree with the measured ones fully, this new resolution is significant for the application of SEA.
基金funded by Major Projects of Aero-Engines and Gas Turbines(J2019-Ⅳ-0023-0091 and J2019-Ⅳ-0005-0073)Aeronautical Science Foundation of China(2019ZB051002)+1 种基金China Postdoctoral Science Foundation(2021M700326)Advanced Jet Propulsion Creativity Center(Projects HKCX2020-02-013,HKCX2020-02-016 and HKCX2022-01009)。
文摘Within the linear framework,the Modal Electromechanical Coupling Factor(MEMCF)is an important indicator to quantify the dynamic conversion of mechanical energy and electrical energy of piezoelectric structures.It is also an important tool to guide the piezoelectric damping design of linear structures.Advanced aircraft often fly in maneuvers,and the variable working conditions induce drastic changes in the load level on structures.Geometric and contact nonlinearities of thin-walled structures and joint structures are often activated.To achieve a good vibration reduction effect covering all working conditions,one cannot directly use linear electromechanical coupling theory to instruct the piezoelectric damping design for nonlinear structures.Therefore,this paper defines the Nonlinear Modal Electromechanical Coupling Factor(NMEMCF)and proposes the corresponding numerical method for the first time to quantitatively evaluate the electromechanical coupling capability of nonlinear piezoelectric structures.Three candidate definitions of the NMEMCF are given,including two frequency definitions and one energy definition.The energy definition is the most promising one.It is not only applicable to both conservative and dissipative nonlinear structures but also compatible with the linear MEMCF.In addition,based on the energy formula,the NMEMCF can be obtained by only performing one nonlinear modal analysis in the open-circuit state.The analytical findings and the numerical tool are validated against two piezoelectric structures with different types of nonlinearities.A strong correlation among the NMEMCF,geometric parameters,and energy dissipation is observed.The results confirm that the proposed NMEMCF captures the physics of the electromechanical coupling phenomenon associated with nonlinear piezoelectric structures and can be used as an essential design indicator of piezoelectric damping,especially for variable working conditions.
基金supported by the National Natural Science Foundation of China(10025209,10132010,and 90208002)the Research Grants Council of the Hong Kong Special Administrative Region,China(HKU 7203/03E).
文摘This paper presents an efficient meshless method for analyzing cracked piezoelectric structures subjected to mechanical and electrical loading. In this method, an element free Galerkin （EFG） formulation, an enriched basic function and some special shape functions that contain discontinuous derivatives are employed. Based on the moving least squares （MLS） interpolation approach, the EFG method is one of the promising methods for dealing with problems involving progressive crack growth. Since the method is meshless and no element connectivity data are needed, the burdensome remeshing procedure required in the conventional finite element method （FEM） is avoided. The numerical results show that the proposed method can yield an accurate near-tip stress field in an infinite piezoelectric plate containing an interior hole. In another example studying a ceramic multilayer actuator, the proposed model was found to be accurate in the simulation of stress and electric field concentrations arround the abrupt end of an internal electrode.
基金Item Sponsored by Technology Supporting Program During the 11th Five-Year Plan Period(BAE03A07)
文摘Combined with the parameters of the production process of a steel factory, numerical simulations for a new ladle from preheating to turnover are conducted using the finite element analysis system software （ANSYS）. The measured data proved that the simulated results are reliable. The effects of preheating time, thermal cycling times, and empty package time on steel temperature are calculated, an ideal preheating time is provided, besides, based on the analysis of a single factor and use the nonlinear analysis method, a steel temperature compensating model with di- versified coupling factors is proposed, with the largest error of the present coupling model at 1. 462 ~C, and the er- rors between actual and target steel temperature in tundish after the model is applied to practical production are basi- cally controlled within -4-6 ~C, which can meet the accuracy of the manufacturer and has a practical guiding significance for the production in steelmaking workshops.
基金Project supported by the Wang Faculty Fellowship at Peking University,Beijing,China,2006-2007 through California State University (CSU) International Programs USAthe National Basic Research Program of China (Grant No 2007CB307004)+1 种基金the National High Technology Research and Development Program of China (Grant No 2006AA03A113)the National Natural Science Foundation of China (Grant Nos 60276034,60577030 and 60607003)
文摘We have investigated the transverse mode pattern and the optical field confinement factor of gallium nitride （GaN） laser diodes （LDs） theoretically. For the particular LD structure, composed of approximate 4 μm thick n-GaN substrate layer, the maximum optical confinement factor was found to be corresponding to the 5^th order transverse mode, the so-called lasing mode. Moreover, the value of the maximum confinement factor varies periodically when increasing the n-side GaN layer thickness, which simultaneously changes and increases the oscillation mode order of the GaN LD caused by the effects of mode coupling. The effects of the thickness and the average composition of Al in the AlGaN/GaN superlat.tice on the optical confinement factor are also presented. Finally, the mode coupling and optimization of the layers in the GaN-based LD are discussed.
基金the National Natural Science Foundation of China (No.51178305)Key Projects in the Science & Technology Pillar Program of Tianjin (No.11ZCKFSF00300)
文摘In order to accurately simulate the diffusion of chloride ion in the existing concrete bridge and acquire the precise chloride ion concentration at given time, a cellular automata （CA）-based model is proposed. The process of chloride ion diffusion is analyzed by the CA-based method and a nonlinear solution of the Fick＇s second law is obtained. Considering the impact of various factors such as stress states, temporal and spatial variability of diffusion parameters and water-cement ratio on the process of chloride ion diffusion, the model of chloride ion diffusion under multi-factor coupling actions is presented. A chloride ion penetrating experiment reported in the literature is used to prove the effectiveness and reasonability of the present method, and a T-type beam is taken as an illustrative example to analyze the process of chloride ion diffusion in practical application. The results indicate that CA-based method can simulate the diffusion of chloride ion in the concrete structures with acceptable precision.
基金co-supported by the National Natural Science Foundation of China (Nos. 61374145 and U1333131)
文摘Heavy-equipment airdrop is a highly risky procedure that has a complicated system due to the secluded and complex nature of factors＇ coupling. As a result, it is difficult to study the modeling and safety simulation of this system. The dynamic model of the heavy-equipment airdrop is based on the Lagrange analytical mechanics, which has all the degrees of freedom and can accurately pinpoint the real-time coordinates and attitude of the carrier with its cargo. Unfavorable conditions accounted in the factors＇ models, including aircraft malfunctions and adverse environments, are established from a man-machine-environment perspective. Subsequently, a virtual simulation system for the safety research of the multi-factor coupling heavy-equipment airdrop is developed through MATLAB/Simulink, C language and Flightgear software. To verify the veracity of the theory, the verification model is built based on dynamic software ADAMS. Finally, the emulation is put to the test with the input of realistic accident variables to ascertain its feasibility and validity of this method.
