The magnetic field generated in the air gap of the cage asynchronous machine and the harmonics of the magnetomotive forces creating that magnetic field,as well as the synchronous parasitic torques,radial magnetic forc...The magnetic field generated in the air gap of the cage asynchronous machine and the harmonics of the magnetomotive forces creating that magnetic field,as well as the synchronous parasitic torques,radial magnetic forces have been discussed in great detail in the literature,but always separately,for a long time.However,systematization of the phenomenon still awaits.Therefore,it is worth summarizing the completeness of the phenomena in a single study–with a new approach at the same time-in order to reveal the relationships between them.The role of rotor slot number is emphasized much more than before.New formulas derived for both synchronous torques and radial magnetic forces are used for further investigation.It will be shown that both phenomena in subject must be treated together.Formulas will be provided to take into account attenuation.Design guide will be provided to avoid dangerous rotor slot numbers.It will be shown that the generation of synchronous torques and radial magnetic forces do not depend–in this new approach-on the slot combination,but on the rotor slot number itself.展开更多
The purpose of this study is to measure the forces and torques produced in the drilling process of a non-homogenous material （bone）. An automated 5 DoF CataLyst-5 robot is used during the drilling process and it is ...The purpose of this study is to measure the forces and torques produced in the drilling process of a non-homogenous material （bone）. An automated 5 DoF CataLyst-5 robot is used during the drilling process and it is integrated to a 6 DoF force-torque sensor. A force-torque controller which is built in the Matlab Simulink environment is employed to control the drilling process of the bone. Different feed rate is used during the experimental process of the bone drilling operation. The sensor is calibrated to measure the tri-axial direction of the resultant forces and torques. The profiles of the forces and torques obtained are non-linear due to the diversity of the bone density. The profiles generated also indicated fluctuation in the interface layers of the bone.展开更多
Utilizing Eliassen′s concepts, the forcing of the isentropic azimuthally-averaged mass-weighted radial-vertical circulation by diabatic heating and torques within an extratropical cyclone and a typhoon was studied th...Utilizing Eliassen′s concepts, the forcing of the isentropic azimuthally-averaged mass-weighted radial-vertical circulation by diabatic heating and torques within an extratropical cyclone and a typhoon was studied through numerical simulations based on the linear diagnostic equation derived previously. The structure of the forcing associated with diabatic heating and torques was determined from quasi-Lagrangian diagnostic analyses of actual case studies. The two cyclones studied were the Ohio extratropical cyclone of 25-27 January 1978 and typhoon Nancy of 18-23 September 1979. The Ohio cyclone, which formed over the Gulf Coast and moved through Ohio and eastern Michigan, was one of the most intense storms with blizzard conditions to ever occur in this region. Typhoon Nancy which occurred over the South China Sea during the FGGE year was selected since relatively high quality assimilated data were available. Within the Ohio cyclone, the dominant internal processes forcing the mean circulation with embedded relatively strong hydrodynamic stability were the pressure torque associated with baroclinic (asymmetric) structure and the horizontal eddy angular momentum transport associated with the typical S-shaped thermal and wind structures of self-development. Within typhoon Nancy, the dominant internal process forcing the mean circulation with embedded weak hydrodynamic stability was the latent heat release. This analysis shows that the simulated azimuthally-averaged mass-weighted radial motions within these two cyclones agree quite well with the “observed”azimuthally-averaged mass-weighted radial motions. This isentropic numerical study also provides insight into the relatively important internal forcing processes and the trade off between forcing and stability within both extratropical and tropical cyclones.展开更多
The growing demand for artificial intelligence and complex computing has underscored the urgent need for advanced data storage technologies.Spin-orbit torque(SOT)has emerged as a leading candidate for high-speed,high-...The growing demand for artificial intelligence and complex computing has underscored the urgent need for advanced data storage technologies.Spin-orbit torque(SOT)has emerged as a leading candidate for high-speed,high-density magnetic random-access memory due to its ultrafast switching speed and low power consumption.This review systematically explores the generation and switching mechanisms of electron-mediated torques(including both conventional SOTs and orbital torques)and magnon-mediated torques.We discuss key materials that enable these effects:heavy metals,topological insulators,low-crystal-symmetry materials,non-collinear antiferromagnets,and altermagnets for conventional SOTs;3d,4d,and 5d transition metals for orbital torques;and antiferromagnetic insulator Ni O-and multiferroic Bi Fe O_(3)-based sandwich structures for magnon torques.We emphasize that although key components of SOT devices have been demonstrated,numerous promising materials and critical questions regarding their underlying mechanisms remain to be explored.Therefore,this field represents a dynamic and rapidly evolving frontier in spintronics,offering significant potential for advancing next-generation information storage and computational technologies.展开更多
The undeformed chip thickness and grinding force are key parameters for revealing the material removal mechanism in the grinding process.However,they are difficult to be well expressed due to the ununiformed protrusio...The undeformed chip thickness and grinding force are key parameters for revealing the material removal mechanism in the grinding process.However,they are difficult to be well expressed due to the ununiformed protrusion height and random position distribution of abrasive grains on the abrasive wheel surface.This study investigated the distribution of undeformed chip thickness and grinding force considering the non-uniform characteristics of abrasive wheel in the grinding of K4002 nickel-based superalloy.First,a novel grinding force model was established through a kinematic-geometric analysis and a grain-workpiece contact analysis.Then,a series of grinding experiments were conducted for verifying the model.The results indicate that the distribution of undeformed chip thickness is highly consistent with the Gaussian distribution formula.The increase in the grinding depth mainly leads to an increase in the average value of Gaussian distribution.On the contrary,the increase in the workpiece infeed speed or the decrease in the grinding speed mainly increases the standard deviation of Gaussian distribution.The average and maximum errors of the grinding force model are 4.9%and 14.6%respectively,indicating that the model is of high predication accuracy.展开更多
Rail weld irregularities are one of the primary excitation sources for vehicle-track interaction dynamics in modern high-speed railways.They can cause significant wheel-rail dynamic interactions,leading to wheel-rail ...Rail weld irregularities are one of the primary excitation sources for vehicle-track interaction dynamics in modern high-speed railways.They can cause significant wheel-rail dynamic interactions,leading to wheel-rail noise,component damage,and deterioration.Few researchers have employed the vehicle-track interaction dynamic model to study the dynamic interactions between wheel and rail induced by rail weld geometry irregularities.However,the cosine wave model used to simulate rail weld irregularities mainly focuses on the maximum value and neglects the geometric shape.In this study,novel theoretical models were developed for three categories of rail weld irregularities,based on measurements of the high-speed railway from Beijing to Shanghai.The vertical dynamic forces in the time and frequency domains were compared under different running speeds.These forces generated by the rail weld irregularities that were measured and modeled,respectively,were compared to validate the accuracy of the proposed model.Finally,based on the numerical study,the impact force due to rail weld irrregularity is modeled using an Artificial Neural Network(ANN),and the optimum combination of parameters for this model is found.The results showed that the proposed model provided a more accurate wheel/rail dynamic evaluation caused by rail weld irregularities than that established in the literature.The ANN model used in this paper can effectively predict the impact force due to rail weld irrregularity while reducing the computation time.展开更多
The purpose of this article is to provide,from the perspective of deformable solid mechanics,a correct justification for the expressions of all forces acting on the surface of a ferromagnetic material in a magnetic fi...The purpose of this article is to provide,from the perspective of deformable solid mechanics,a correct justification for the expressions of all forces acting on the surface of a ferromagnetic material in a magnetic field,initiated only by this field.It is shown that the moment of force applied to any closed body surface S,corresponding to the asymmetric part TAof the stress tensor T(denoted as the force pA),balances the mass magnetic moment Lmagacting in the volume V bounded by the surface S.The emergence of the asymmetric part TAof the stress tensor arises as a consequence of a special case within the moment theory of elasticity,the use of which is necessary for accurately describing the behavior of a ferromagnetic material in a magnetic field.The force pa acts in a plane tangential to the surface S at any point,while,in addition to this force,the normal force pn also acts on the body surface.It is shown in the article that the latter force arises as a result of a jump in the normal component of the magnetic field strength appearing at the body surface,and its expression is defined by the mass' s(ponderomotive) magnetic forces Fmag.Usually,this force is introduced based on the Maxwell stress tensor,which is used in the classical electromagnetism to represent the interaction between electromagnetic forces and mechanical momentum.However,as we believe and justify this in the article,such an approach is unacceptable in deformable solid mechanics.展开更多
Driven by technological innovation and the innovative allocation of production factors,new quality productive forces(NQPFs)are a key breakthrough and core element propelling China’s transition from a major agricultur...Driven by technological innovation and the innovative allocation of production factors,new quality productive forces(NQPFs)are a key breakthrough and core element propelling China’s transition from a major agricultural country to an advanced agricultural nation.At its core,agricultural modernization represents a frontier shift in agricultural development-a dynamic evolution of productive forces across technological forms,farmer demographics,industrial structures,and urban-rural relations.NQPFs drive the high-quality,integrated development of agricultural modernization through agricultural technological innovation,green and low-carbon practices,and the enhancement of all production factors.As NQPFs evolve and agricultural modernization advances,we must address constraints stemming from gaps in technology,models,resources,and talent.Furthermore,we must foster deep integration among industry,research,and education to develop new pathways for industrial upgrading,promote green and efficient agricultural development,and bridge existing technological gaps.These collective efforts are crucial for accelerating the high-quality development of agricultural modernization.展开更多
Toroidal torques,generated by the resonant magnetic perturbation(RMP)and acting on the plasma column,are numerically systematically investigated for an ITER baseline scenario.The neoclassical toroidal viscosity(NTV),i...Toroidal torques,generated by the resonant magnetic perturbation(RMP)and acting on the plasma column,are numerically systematically investigated for an ITER baseline scenario.The neoclassical toroidal viscosity(NTV),in particular the resonant portion,is found to provide the dominant contribution to the total toroidal torque under the slow plasma flow regime in ITER.While the electromagnetic torque always opposes the plasma flow,the toroidal torque associated with the Reynolds stress enhances the plasma flow independent of the flow direction.A peculiar double-peak structure for the net NTV torque is robustly computed for ITER,as the toroidal rotation frequency is scanned near the zero value.This structure is found to be ultimately due to a non-monotonic behavior of the wave-particle resonance integral(over the particle pitch angle)in the superbanana plateau NTV regime in ITER.These findings are qualitatively insensitive to variations of a range of factors including the wall resistivity,the plasma pedestal flow and the assumed frequency of the rotating RMP field.展开更多
Nature is really powerful!Big earthquakes can make tall buildings and even whole mountains fall down.At Niagara Falls,waterfalls like crazy,filling 50 Olympic-sized pools in a minute!We know about storms like hurrican...Nature is really powerful!Big earthquakes can make tall buildings and even whole mountains fall down.At Niagara Falls,waterfalls like crazy,filling 50 Olympic-sized pools in a minute!We know about storms like hurricanes and blizzards.But there are many other strange things nature can do that might surprise you!展开更多
This article investigates the radial electromagnetic force,vibration,and noise phenomenon in a low-speed,hightorque density spoke-type permanent magnet synchronous machine(ST-PMSM)designed with assisted poles having s...This article investigates the radial electromagnetic force,vibration,and noise phenomenon in a low-speed,hightorque density spoke-type permanent magnet synchronous machine(ST-PMSM)designed with assisted poles having symmetric and asymmetric topologies.Firstly,an analytical expression for the machine radial electromagnetic force(REMF)is derived to quickly estimate the REMF characteristics for the ST-PMSM with assisted poles having symmetric and asymmetric topologies.The 2D-Fourier decomposition method is applied to investigate the radial electromagnetic force harmonics(REMFHs).Secondly,Finite element(FE)models are designed for the machine structural analysis.Subsequently,the FE models and modal analysis are explored for different design cases of the analyzed machine.Lastly,vibration and noise behavior are investigated using an FE approach for the machine designs under symmetric and asymmetric assisted poles topologies.The findings indicate an increase in the richness of REMFHs,alongside a decrease in both the fundamental frequency and the lowest non-zero order of REMF,attributed to the presence of asymmetric assisted poles.Consequently,it is investigated that while considering the vibration and noise response in STPMSMs designed with asymmetric assisted poles topologies,it is essential to thoroughly account for induced non-zero low-order harmonics and their optimization for better vibration and noise performance.展开更多
Higher vocational colleges are important institutions for cultivating skilled talents.With the development of new-quality productive forces,these colleges need to meet the requirements of digital transformation and im...Higher vocational colleges are important institutions for cultivating skilled talents.With the development of new-quality productive forces,these colleges need to meet the requirements of digital transformation and improve the effectiveness of talent cultivation.In the process of higher vocational education,it is essential to emphasize teaching innovation and enhance the level of digital teaching.From the perspective of new-quality productive forces,this paper analyzes the new requirements put forward for higher vocational education and proposes specific digital transformation strategies.The purpose is to improve the effectiveness of talent cultivation and accumulate experience for the subsequent digital transformation of higher vocational education.展开更多
In the realm of slope monitoring and reinforcement,traditional prestressing anchor cables are extensively used.However,these conventional methods often face limitations when applied to loess slopes,such as potential i...In the realm of slope monitoring and reinforcement,traditional prestressing anchor cables are extensively used.However,these conventional methods often face limitations when applied to loess slopes,such as potential issues with stress concentration and insufficient adaptability to the unique mechanical properties of loess,which may lead to challenges in ensuring long-term stability and effective reinforcement.Negative Poisson's ratio(NPR)anchor cables with constant resistance have emerged as a promising alternative,which can better match the engineering demands of loess slopes by providing more uniform stress distribution and adaptive deformation characteristics.The NPR cable's ability to maintain a constant resistance during deformation offers a distinct advantage over traditional methods as it can more effectively accommodate the complex and variable conditions of loess slopes.To investigate the anchoring performance of NPR cables in loess slope,the stress characteristics of NPR cable in loess medium were simulated and analysed by ABAQUS finite element software.First,static and general quasi-static analysis methods were used to simulate the NPR cable under static tensile conditions.The consistency of the simulated constant resistance deformation characteristics with experimental results found in the literature was verified.Second,the interaction model between the NPR cable coupled with the loess medium was established.Its constant resistance was calculated to be about 24.08%larger than that of NPR anchor cable while its plastic deformation was reduced by about 37.14%.The compressive stress on the contact surface between NPR cable and loess was concentrated near the free end of the sleeve,which indicated that the loess was prone to severe damage at the free end.The research results reveal the typical shear failure mechanism of NPR cable in loess medium,which provides an important theoretical basis for prevention of landslides and monitoring of loess slopes.展开更多
The theory of new quality productive forces provides a foundational framework for cultivating pre-service English teachers.There is a high degree of consistency between the development of new quality productive forces...The theory of new quality productive forces provides a foundational framework for cultivating pre-service English teachers.There is a high degree of consistency between the development of new quality productive forces and the cultivation of pre-service English teachers.The development of new quality productive forces has put forward new requirements for the cultivation of pre-service English teachers,while the cultivation of pre-service English teachers will also promote the development of new quality productive forces and provide talent support for it.Currently,the cultivation of pre-service English teachers faces numerous challenges,which requires strengthening top-level program design,reconstructing the curriculum system,expanding cultivation fields for pre-service English teachers,improving the digital literacy of pre-service English teachers,deepening international exchanges and cooperation,and building an evidence-based evaluation system as a guarantee to achieve new breakthroughs in the cultivation of pre-service English teachers and promote the development of new quality productive forces.展开更多
Currently,driven by the accelerated iteration of digital technologies such as big data,cloud computing,and artificial intelligence,the digital economy has become a crucial engine for generating new quality productive ...Currently,driven by the accelerated iteration of digital technologies such as big data,cloud computing,and artificial intelligence,the digital economy has become a crucial engine for generating new quality productive forces and promoting industrial upgrading.Building on a systematic review of the theoretical evolution and measurement methods of the digital economy and new quality productive forces,this paper outlines their enabling mechanisms,industrial synergy pathways,and policy practices,and summarizes regional disparities and spatial spillover effects.The main findings are as follows:First,the digital economy reshapes the traditional factor structure and significantly enhances total factor productivity through the permeation of data elements and technological innovation;Second,driven jointly by the consumer internet and the industrial internet,it optimizes supply–demand matching and service models while reducing operating costs and improving production efficiency;Third,policy environments and institutional coordination amplify the enabling effects,as evidenced notably in national big-data pilot zones and the“East Data West Computing”initiative.Looking ahead,empirical research should deepen the exploration of micro-level mechanisms and dynamic panel analyses,construct a measurement system of new quality productive forces that spans macro,meso,and micro scales,and investigate pathways for regional collaborative governance and green digital integration to address the complex challenges of the new era.展开更多
Digital technology is a pivotal factor in developing new quality productive forces in agriculture and building digital villages.Using digital technology as a foundation to explore viable methods for these forces is an...Digital technology is a pivotal factor in developing new quality productive forces in agriculture and building digital villages.Using digital technology as a foundation to explore viable methods for these forces is an imperative for realizing rural revitalization and fostering circular agricultural development.This paper outlines the theoretical logic of how new quality productive forces empower digital village construction,focusing on accelerating smart village initiatives,promoting rural digital production,and developing unique local resources.Based on the practical challenges currently facing digital village development,it formulates several countermeasures.These include stimulating rural industrial endogenous motivation through urban-rural industrial integration,implementing actions to enhance rural digital governance,building a contingent of rural digital talent,and improving rural digital infrastructure.The aim is to provide insights for better leveraging the dynamic role of new quality productive forces in promoting digital village construction.展开更多
From the perspective of new productive forces,the general technology curriculum in senior high schools should not only cultivate students’technical knowledge and practical abilities but also focus on the development ...From the perspective of new productive forces,the general technology curriculum in senior high schools should not only cultivate students’technical knowledge and practical abilities but also focus on the development of innovative thinking to meet the demand for interdisciplinary talents in the future society.Based on the chapter“Common Conception Methods”in the Jiangsu Education Edition of Technology and Design 1,this paper explores the implementation path of the general technology curriculum,focusing on the optimization strategies in four aspects:Project-based learning(PBL),strengthening technical practice,STEAM interdisciplinary integration,and a diversified.evaluation system It also analyzes the application of divergent thinking(brainstorming)and reverse thinking in the curriculum through cases.The research shows that optimizing teaching methods and enhancing practical links can effectively stimulate students’creativity and teamwork ability,improve the effectiveness of curriculum implementation,and provide strong support for the cultivation of future technical innovation talents.展开更多
Digital-intelligent technologies represent the advanced direction of new quality productive forces and are becoming a driving force for the digital transformation and high-quality development of the cultural industry....Digital-intelligent technologies represent the advanced direction of new quality productive forces and are becoming a driving force for the digital transformation and high-quality development of the cultural industry.Empowered by new quality productive forces,the digital cultural industry has demonstrated diverse characteristics,including the innovation of cultural production subjects,the intelligentization of production tools,the digitization of production objects,the systematization of production methods,and the diversification of production factors.Leveraging technologies such as AIGC,virtual-physical integration,and DAOs based on Web 3.0,the digital cultural industry has established an innovative paradigm,fostering a new method of AIGC production in the digital cultural industry,a new business format of virtual-physical integration,and a new collaborative ecosystem characterized by co-creation,co-building,and co-governance.Meanwhile,the innovative paradigm of the digital cultural industry also faces a series of new challenges,such as the adaptability issues with AIGC algorithm models,creative bottlenecks,and content quality control problems.Additionally,there are obstacles like the immaturity of international development channels for new business formats,the lack of cultural connotations in creative products,and the lag of the digital-intelligent governance of the industry ecosystem behind digital practices.In light of this,there is an urgent need to establish an optimization mechanism for the high-quality development of digital cultural industries driven by new quality productive forces.This includes optimizing the content production mechanism for AIGC-led high-quality innovation in the digital cultural industry;improving the leapfrog development mechanism for new digital cultural business formats through global-regional collaboration;and enhancing the accurate,high-quality governance mechanism for the digital cultural industry that is aligned with the goals of Chinese modernization.展开更多
文摘The magnetic field generated in the air gap of the cage asynchronous machine and the harmonics of the magnetomotive forces creating that magnetic field,as well as the synchronous parasitic torques,radial magnetic forces have been discussed in great detail in the literature,but always separately,for a long time.However,systematization of the phenomenon still awaits.Therefore,it is worth summarizing the completeness of the phenomena in a single study–with a new approach at the same time-in order to reveal the relationships between them.The role of rotor slot number is emphasized much more than before.New formulas derived for both synchronous torques and radial magnetic forces are used for further investigation.It will be shown that both phenomena in subject must be treated together.Formulas will be provided to take into account attenuation.Design guide will be provided to avoid dangerous rotor slot numbers.It will be shown that the generation of synchronous torques and radial magnetic forces do not depend–in this new approach-on the slot combination,but on the rotor slot number itself.
文摘The purpose of this study is to measure the forces and torques produced in the drilling process of a non-homogenous material （bone）. An automated 5 DoF CataLyst-5 robot is used during the drilling process and it is integrated to a 6 DoF force-torque sensor. A force-torque controller which is built in the Matlab Simulink environment is employed to control the drilling process of the bone. Different feed rate is used during the experimental process of the bone drilling operation. The sensor is calibrated to measure the tri-axial direction of the resultant forces and torques. The profiles of the forces and torques obtained are non-linear due to the diversity of the bone density. The profiles generated also indicated fluctuation in the interface layers of the bone.
文摘Utilizing Eliassen′s concepts, the forcing of the isentropic azimuthally-averaged mass-weighted radial-vertical circulation by diabatic heating and torques within an extratropical cyclone and a typhoon was studied through numerical simulations based on the linear diagnostic equation derived previously. The structure of the forcing associated with diabatic heating and torques was determined from quasi-Lagrangian diagnostic analyses of actual case studies. The two cyclones studied were the Ohio extratropical cyclone of 25-27 January 1978 and typhoon Nancy of 18-23 September 1979. The Ohio cyclone, which formed over the Gulf Coast and moved through Ohio and eastern Michigan, was one of the most intense storms with blizzard conditions to ever occur in this region. Typhoon Nancy which occurred over the South China Sea during the FGGE year was selected since relatively high quality assimilated data were available. Within the Ohio cyclone, the dominant internal processes forcing the mean circulation with embedded relatively strong hydrodynamic stability were the pressure torque associated with baroclinic (asymmetric) structure and the horizontal eddy angular momentum transport associated with the typical S-shaped thermal and wind structures of self-development. Within typhoon Nancy, the dominant internal process forcing the mean circulation with embedded weak hydrodynamic stability was the latent heat release. This analysis shows that the simulated azimuthally-averaged mass-weighted radial motions within these two cyclones agree quite well with the “observed”azimuthally-averaged mass-weighted radial motions. This isentropic numerical study also provides insight into the relatively important internal forcing processes and the trade off between forcing and stability within both extratropical and tropical cyclones.
基金supported by the National Natural Science Foundation of China(Grant Nos.U24A6002,12174237(X.X.),52471253(F.W.),12404091(J.L.),52171183(Z.Q.))the support from the National Key Research and Development Program of China(Grant No.2022YFB3505301)+4 种基金the support from the Fund Program for the Scientific Activities of Selected Returned Overseas Professionals in Shanxi Province(Grant No.20240019)Central Government’s Special Fund for Local Science and Technology Development(Grant No.YDZJSX2024D058)the support from the Basic Research Plan of Shanxi Province(Grant No.202403021212016)the support from the Fundamental Research Program of Shanxi Province(Grant No.202403021222252)the Higher Education Science and Technology Innovation Plan Project of Shanxi(Grant No.2024L146)。
文摘The growing demand for artificial intelligence and complex computing has underscored the urgent need for advanced data storage technologies.Spin-orbit torque(SOT)has emerged as a leading candidate for high-speed,high-density magnetic random-access memory due to its ultrafast switching speed and low power consumption.This review systematically explores the generation and switching mechanisms of electron-mediated torques(including both conventional SOTs and orbital torques)and magnon-mediated torques.We discuss key materials that enable these effects:heavy metals,topological insulators,low-crystal-symmetry materials,non-collinear antiferromagnets,and altermagnets for conventional SOTs;3d,4d,and 5d transition metals for orbital torques;and antiferromagnetic insulator Ni O-and multiferroic Bi Fe O_(3)-based sandwich structures for magnon torques.We emphasize that although key components of SOT devices have been demonstrated,numerous promising materials and critical questions regarding their underlying mechanisms remain to be explored.Therefore,this field represents a dynamic and rapidly evolving frontier in spintronics,offering significant potential for advancing next-generation information storage and computational technologies.
基金financially supported by the National Natural Science Foundation of China(Nos.92160301,92060203,52175415 and 52205475)the Science Center for Gas Turbine Project(Nos.P2022-AB-Ⅳ-002-001 and P2023-B-Ⅳ-003-001)+3 种基金the Jiangsu Key Laboratory of Precision and Micro-Manufacturing Technology(No.JSKL2223K01)the Natural Science Foundation of Jiangsu Province(No.BK20210295)the Superior Postdoctoral Project of Jiangsu Province(No.2022ZB215)the Henan Science and Technology Public Relations Project(No.212102210445).
文摘The undeformed chip thickness and grinding force are key parameters for revealing the material removal mechanism in the grinding process.However,they are difficult to be well expressed due to the ununiformed protrusion height and random position distribution of abrasive grains on the abrasive wheel surface.This study investigated the distribution of undeformed chip thickness and grinding force considering the non-uniform characteristics of abrasive wheel in the grinding of K4002 nickel-based superalloy.First,a novel grinding force model was established through a kinematic-geometric analysis and a grain-workpiece contact analysis.Then,a series of grinding experiments were conducted for verifying the model.The results indicate that the distribution of undeformed chip thickness is highly consistent with the Gaussian distribution formula.The increase in the grinding depth mainly leads to an increase in the average value of Gaussian distribution.On the contrary,the increase in the workpiece infeed speed or the decrease in the grinding speed mainly increases the standard deviation of Gaussian distribution.The average and maximum errors of the grinding force model are 4.9%and 14.6%respectively,indicating that the model is of high predication accuracy.
基金supported by Natural Science Foundation of China(52178441)the Scientific Research Projects of the China Academy of Railway Sciences Co.,Ltd.(Grant No.2022YJ043).
文摘Rail weld irregularities are one of the primary excitation sources for vehicle-track interaction dynamics in modern high-speed railways.They can cause significant wheel-rail dynamic interactions,leading to wheel-rail noise,component damage,and deterioration.Few researchers have employed the vehicle-track interaction dynamic model to study the dynamic interactions between wheel and rail induced by rail weld geometry irregularities.However,the cosine wave model used to simulate rail weld irregularities mainly focuses on the maximum value and neglects the geometric shape.In this study,novel theoretical models were developed for three categories of rail weld irregularities,based on measurements of the high-speed railway from Beijing to Shanghai.The vertical dynamic forces in the time and frequency domains were compared under different running speeds.These forces generated by the rail weld irregularities that were measured and modeled,respectively,were compared to validate the accuracy of the proposed model.Finally,based on the numerical study,the impact force due to rail weld irrregularity is modeled using an Artificial Neural Network(ANN),and the optimum combination of parameters for this model is found.The results showed that the proposed model provided a more accurate wheel/rail dynamic evaluation caused by rail weld irregularities than that established in the literature.The ANN model used in this paper can effectively predict the impact force due to rail weld irrregularity while reducing the computation time.
基金supported by the Ministry of Science and Higher Education of the Russian Federation(No.075-15-2024-535)。
文摘The purpose of this article is to provide,from the perspective of deformable solid mechanics,a correct justification for the expressions of all forces acting on the surface of a ferromagnetic material in a magnetic field,initiated only by this field.It is shown that the moment of force applied to any closed body surface S,corresponding to the asymmetric part TAof the stress tensor T(denoted as the force pA),balances the mass magnetic moment Lmagacting in the volume V bounded by the surface S.The emergence of the asymmetric part TAof the stress tensor arises as a consequence of a special case within the moment theory of elasticity,the use of which is necessary for accurately describing the behavior of a ferromagnetic material in a magnetic field.The force pa acts in a plane tangential to the surface S at any point,while,in addition to this force,the normal force pn also acts on the body surface.It is shown in the article that the latter force arises as a result of a jump in the normal component of the magnetic field strength appearing at the body surface,and its expression is defined by the mass' s(ponderomotive) magnetic forces Fmag.Usually,this force is introduced based on the Maxwell stress tensor,which is used in the classical electromagnetism to represent the interaction between electromagnetic forces and mechanical momentum.However,as we believe and justify this in the article,such an approach is unacceptable in deformable solid mechanics.
基金funded by grants from the General Project of the National Social Science Fund:“Research on the Interactive Mechanism of Migrant Workers Returning to Their Hometowns for Entrepreneurship and Rural Revitalization in the Major Labor Export Provinces”(20BJY136)General Project of Sichuan Provincial Philosophy and Social Science Fund:“The Era Significance,Growth Constraints,and Path Optimization of the New Agricultural Laborers from the Perspective of the New Quality Productive Forces”(SCJJ24ND065)Key Project of the Sichuan Academy of Social Sciences:“The Era Significance,Current Concerns,and Action Prospects of the New Agricultural Laborers from the Perspective of the New Quality Productive Forces”(24XD02).
文摘Driven by technological innovation and the innovative allocation of production factors,new quality productive forces(NQPFs)are a key breakthrough and core element propelling China’s transition from a major agricultural country to an advanced agricultural nation.At its core,agricultural modernization represents a frontier shift in agricultural development-a dynamic evolution of productive forces across technological forms,farmer demographics,industrial structures,and urban-rural relations.NQPFs drive the high-quality,integrated development of agricultural modernization through agricultural technological innovation,green and low-carbon practices,and the enhancement of all production factors.As NQPFs evolve and agricultural modernization advances,we must address constraints stemming from gaps in technology,models,resources,and talent.Furthermore,we must foster deep integration among industry,research,and education to develop new pathways for industrial upgrading,promote green and efficient agricultural development,and bridge existing technological gaps.These collective efforts are crucial for accelerating the high-quality development of agricultural modernization.
基金funded by National Natural Science Foundation of China(NSFC)(Nos.12075053,11505021 and 11975068)by National Key R&D Program of China(No.2022YFE 03060002)+1 种基金by Fundamental Research Funds for the Central Universities(No.2232024G-10)supported by the U.S.DoE Office of Science(No.DE-FG02–95ER54309)。
文摘Toroidal torques,generated by the resonant magnetic perturbation(RMP)and acting on the plasma column,are numerically systematically investigated for an ITER baseline scenario.The neoclassical toroidal viscosity(NTV),in particular the resonant portion,is found to provide the dominant contribution to the total toroidal torque under the slow plasma flow regime in ITER.While the electromagnetic torque always opposes the plasma flow,the toroidal torque associated with the Reynolds stress enhances the plasma flow independent of the flow direction.A peculiar double-peak structure for the net NTV torque is robustly computed for ITER,as the toroidal rotation frequency is scanned near the zero value.This structure is found to be ultimately due to a non-monotonic behavior of the wave-particle resonance integral(over the particle pitch angle)in the superbanana plateau NTV regime in ITER.These findings are qualitatively insensitive to variations of a range of factors including the wall resistivity,the plasma pedestal flow and the assumed frequency of the rotating RMP field.
文摘Nature is really powerful!Big earthquakes can make tall buildings and even whole mountains fall down.At Niagara Falls,waterfalls like crazy,filling 50 Olympic-sized pools in a minute!We know about storms like hurricanes and blizzards.But there are many other strange things nature can do that might surprise you!
基金supported by the National Key Research and Developmen Program of China(2022YFB3403100)。
文摘This article investigates the radial electromagnetic force,vibration,and noise phenomenon in a low-speed,hightorque density spoke-type permanent magnet synchronous machine(ST-PMSM)designed with assisted poles having symmetric and asymmetric topologies.Firstly,an analytical expression for the machine radial electromagnetic force(REMF)is derived to quickly estimate the REMF characteristics for the ST-PMSM with assisted poles having symmetric and asymmetric topologies.The 2D-Fourier decomposition method is applied to investigate the radial electromagnetic force harmonics(REMFHs).Secondly,Finite element(FE)models are designed for the machine structural analysis.Subsequently,the FE models and modal analysis are explored for different design cases of the analyzed machine.Lastly,vibration and noise behavior are investigated using an FE approach for the machine designs under symmetric and asymmetric assisted poles topologies.The findings indicate an increase in the richness of REMFHs,alongside a decrease in both the fundamental frequency and the lowest non-zero order of REMF,attributed to the presence of asymmetric assisted poles.Consequently,it is investigated that while considering the vibration and noise response in STPMSMs designed with asymmetric assisted poles topologies,it is essential to thoroughly account for induced non-zero low-order harmonics and their optimization for better vibration and noise performance.
基金Research on High-Quality Development Pathways for Vocational Human Resource Management Programs in Higher Vocational Education under the Perspective of Modernization(Project No.:SGYJG2024B02)。
文摘Higher vocational colleges are important institutions for cultivating skilled talents.With the development of new-quality productive forces,these colleges need to meet the requirements of digital transformation and improve the effectiveness of talent cultivation.In the process of higher vocational education,it is essential to emphasize teaching innovation and enhance the level of digital teaching.From the perspective of new-quality productive forces,this paper analyzes the new requirements put forward for higher vocational education and proposes specific digital transformation strategies.The purpose is to improve the effectiveness of talent cultivation and accumulate experience for the subsequent digital transformation of higher vocational education.
基金the State Key Laboratory of Deep Geotechnical Mechanics and Underground Engineering(SKLGDUEK2124)of China University of Mining and Technology(Beijing)for its support for this research。
文摘In the realm of slope monitoring and reinforcement,traditional prestressing anchor cables are extensively used.However,these conventional methods often face limitations when applied to loess slopes,such as potential issues with stress concentration and insufficient adaptability to the unique mechanical properties of loess,which may lead to challenges in ensuring long-term stability and effective reinforcement.Negative Poisson's ratio(NPR)anchor cables with constant resistance have emerged as a promising alternative,which can better match the engineering demands of loess slopes by providing more uniform stress distribution and adaptive deformation characteristics.The NPR cable's ability to maintain a constant resistance during deformation offers a distinct advantage over traditional methods as it can more effectively accommodate the complex and variable conditions of loess slopes.To investigate the anchoring performance of NPR cables in loess slope,the stress characteristics of NPR cable in loess medium were simulated and analysed by ABAQUS finite element software.First,static and general quasi-static analysis methods were used to simulate the NPR cable under static tensile conditions.The consistency of the simulated constant resistance deformation characteristics with experimental results found in the literature was verified.Second,the interaction model between the NPR cable coupled with the loess medium was established.Its constant resistance was calculated to be about 24.08%larger than that of NPR anchor cable while its plastic deformation was reduced by about 37.14%.The compressive stress on the contact surface between NPR cable and loess was concentrated near the free end of the sleeve,which indicated that the loess was prone to severe damage at the free end.The research results reveal the typical shear failure mechanism of NPR cable in loess medium,which provides an important theoretical basis for prevention of landslides and monitoring of loess slopes.
基金supported by the National Education Sciences Planning Program of China through the National Office for Education Sciences Planning(Grant No.DIA220376).
文摘The theory of new quality productive forces provides a foundational framework for cultivating pre-service English teachers.There is a high degree of consistency between the development of new quality productive forces and the cultivation of pre-service English teachers.The development of new quality productive forces has put forward new requirements for the cultivation of pre-service English teachers,while the cultivation of pre-service English teachers will also promote the development of new quality productive forces and provide talent support for it.Currently,the cultivation of pre-service English teachers faces numerous challenges,which requires strengthening top-level program design,reconstructing the curriculum system,expanding cultivation fields for pre-service English teachers,improving the digital literacy of pre-service English teachers,deepening international exchanges and cooperation,and building an evidence-based evaluation system as a guarantee to achieve new breakthroughs in the cultivation of pre-service English teachers and promote the development of new quality productive forces.
文摘Currently,driven by the accelerated iteration of digital technologies such as big data,cloud computing,and artificial intelligence,the digital economy has become a crucial engine for generating new quality productive forces and promoting industrial upgrading.Building on a systematic review of the theoretical evolution and measurement methods of the digital economy and new quality productive forces,this paper outlines their enabling mechanisms,industrial synergy pathways,and policy practices,and summarizes regional disparities and spatial spillover effects.The main findings are as follows:First,the digital economy reshapes the traditional factor structure and significantly enhances total factor productivity through the permeation of data elements and technological innovation;Second,driven jointly by the consumer internet and the industrial internet,it optimizes supply–demand matching and service models while reducing operating costs and improving production efficiency;Third,policy environments and institutional coordination amplify the enabling effects,as evidenced notably in national big-data pilot zones and the“East Data West Computing”initiative.Looking ahead,empirical research should deepen the exploration of micro-level mechanisms and dynamic panel analyses,construct a measurement system of new quality productive forces that spans macro,meso,and micro scales,and investigate pathways for regional collaborative governance and green digital integration to address the complex challenges of the new era.
基金Supported by the National Social Science Foundation Project"Research on the Theoretical Logic and Practical Path of the Cultural Mission of Ideological and Political Education in the New Era"(20XKS022).
文摘Digital technology is a pivotal factor in developing new quality productive forces in agriculture and building digital villages.Using digital technology as a foundation to explore viable methods for these forces is an imperative for realizing rural revitalization and fostering circular agricultural development.This paper outlines the theoretical logic of how new quality productive forces empower digital village construction,focusing on accelerating smart village initiatives,promoting rural digital production,and developing unique local resources.Based on the practical challenges currently facing digital village development,it formulates several countermeasures.These include stimulating rural industrial endogenous motivation through urban-rural industrial integration,implementing actions to enhance rural digital governance,building a contingent of rural digital talent,and improving rural digital infrastructure.The aim is to provide insights for better leveraging the dynamic role of new quality productive forces in promoting digital village construction.
文摘From the perspective of new productive forces,the general technology curriculum in senior high schools should not only cultivate students’technical knowledge and practical abilities but also focus on the development of innovative thinking to meet the demand for interdisciplinary talents in the future society.Based on the chapter“Common Conception Methods”in the Jiangsu Education Edition of Technology and Design 1,this paper explores the implementation path of the general technology curriculum,focusing on the optimization strategies in four aspects:Project-based learning(PBL),strengthening technical practice,STEAM interdisciplinary integration,and a diversified.evaluation system It also analyzes the application of divergent thinking(brainstorming)and reverse thinking in the curriculum through cases.The research shows that optimizing teaching methods and enhancing practical links can effectively stimulate students’creativity and teamwork ability,improve the effectiveness of curriculum implementation,and provide strong support for the cultivation of future technical innovation talents.
基金funded by Research on Policy Design and Implementation Path for High-Quality Development of Digital Cultural Industry(23&ZD087),a major project of the National Social Science Foundation of China.
文摘Digital-intelligent technologies represent the advanced direction of new quality productive forces and are becoming a driving force for the digital transformation and high-quality development of the cultural industry.Empowered by new quality productive forces,the digital cultural industry has demonstrated diverse characteristics,including the innovation of cultural production subjects,the intelligentization of production tools,the digitization of production objects,the systematization of production methods,and the diversification of production factors.Leveraging technologies such as AIGC,virtual-physical integration,and DAOs based on Web 3.0,the digital cultural industry has established an innovative paradigm,fostering a new method of AIGC production in the digital cultural industry,a new business format of virtual-physical integration,and a new collaborative ecosystem characterized by co-creation,co-building,and co-governance.Meanwhile,the innovative paradigm of the digital cultural industry also faces a series of new challenges,such as the adaptability issues with AIGC algorithm models,creative bottlenecks,and content quality control problems.Additionally,there are obstacles like the immaturity of international development channels for new business formats,the lack of cultural connotations in creative products,and the lag of the digital-intelligent governance of the industry ecosystem behind digital practices.In light of this,there is an urgent need to establish an optimization mechanism for the high-quality development of digital cultural industries driven by new quality productive forces.This includes optimizing the content production mechanism for AIGC-led high-quality innovation in the digital cultural industry;improving the leapfrog development mechanism for new digital cultural business formats through global-regional collaboration;and enhancing the accurate,high-quality governance mechanism for the digital cultural industry that is aligned with the goals of Chinese modernization.
