The mechanical strength of the synchronous reluctance motor(SynRM)has always been a great challenge.This paper presents an analysis method for assessing stress equivalence and magnetic bridge stress interaction,along ...The mechanical strength of the synchronous reluctance motor(SynRM)has always been a great challenge.This paper presents an analysis method for assessing stress equivalence and magnetic bridge stress interaction,along with a multiobjective optimization approach.Considering the complex flux barrier structure and inevitable stress concentration at the bridge,the finite element model suitable for SynRM is established.Initially,a neural network structure with two inputs,one output,and three layers is established.Continuous functions are constructed to enhance accuracy.Additionally,the equivalent stress can be converted into a contour distribution of a three-dimensional stress graph.The contour line distribution illustrates the matching scheme for magnetic bridge lengths under equivalent stress.Moreover,the paper explores the analysis of magnetic bridge interaction stress.The optimization levels corresponding to the length of each magnetic bridge are defined,and each level is analyzed by the finite element method.The Taguchi method is used to determine the specific gravity of the stress source on each magnetic bridge.Based on this,a multiobjective optimization employing the Multiobjective Particle Swarm Optimization(MOPSO)technique is introduced.By taking the rotor magnetic bridge as the design parameter,ten optimization objectives including air-gap flux density,sinusoidal property,average torque,torque ripple,and mechanical stress are optimized.The relationship between the optimization objectives and the design parameters can be obtained based on the response surface method(RSM)to avoid too many experimental samples.The optimized model is compared with the initial model,and the optimized effect is verified.Finally,the temperature distribution of under rated working conditions is analyzed,providing support for addressing thermal stress as mentioned earlier.展开更多
Nanocomposite ZrCN films consisting of nanocrystalline ZrCN grains embedded in nitrogen-doped amorphous carbon film are deposited by filtered cathodic vacuum arc technology under different bias voltages ranging from 5...Nanocomposite ZrCN films consisting of nanocrystalline ZrCN grains embedded in nitrogen-doped amorphous carbon film are deposited by filtered cathodic vacuum arc technology under different bias voltages ranging from 50to 400 V.The influence of bias voltage on the characterization and the mechanical properties of the ZrCN films are investigated by x-ray diffraction,x-ray photoelectron spectroscopy,scanning electron microscopy,transmission electron microscopy,Raman spectroscopy and nano-indentation.The bias voltage has a subtle effect on the ZrCN grain size,which is around 9.5 nm and keeps almost constant.A slight increase of the bias voltage induces a relatively high sp^3 fraction about 40%in N-doped amorphous C films but leads to the graphitization of the films under a higher voltage.The best mechanical property of the ZrCN film with the hardness of 41 GPa is obtained under the bias voltage of 200 V,indicating the positive effect of slight increase of ion bombardment on the hardness of the films.展开更多
Radiative cooling is a passive thermal management strategy that leverages the natural ability of materials to dissipate heat through infrared radiation.It has significant implications for energy efficiency,climate ada...Radiative cooling is a passive thermal management strategy that leverages the natural ability of materials to dissipate heat through infrared radiation.It has significant implications for energy efficiency,climate adaptation,and sustainable technology development,with applications in personal thermal management,building temperature regulation,and aerospace engineering.However,radiative cooling performance is susceptible to environmental aging and special environmental conditions,limiting its applicability in extreme environments.Herein,a critical review of extreme environmental radiative cooling is presented,focusing on enhancing environmental durability and cooling efficiency.This review first introduces the design principles of heat exchange channels,which are tailored based on the thermal flow equilibrium to optimize radiative cooling capacity in various extreme environments.Subsequently,recent advancements in radiative cooling materials and micronano structures that align with these principles are systematically discussed,with a focus on their implementation in terrestrial dwelling environments,terrestrial extreme environments,aeronautical environments,and space environments.Moreover,this review evaluates the cooling effects and anti-environmental abilities of extreme radiative cooling devices.Lastly,key challenges hindering the development of radiative cooling devices for extreme environmental applications are outlined,and potential strategies to overcome these limitations are proposed,aiming to prompt their future commercialization.展开更多
基金supported by the National Natural Science Foundation of China under grant 52077122 and by the Taishan Industrial Experts Program.
文摘The mechanical strength of the synchronous reluctance motor(SynRM)has always been a great challenge.This paper presents an analysis method for assessing stress equivalence and magnetic bridge stress interaction,along with a multiobjective optimization approach.Considering the complex flux barrier structure and inevitable stress concentration at the bridge,the finite element model suitable for SynRM is established.Initially,a neural network structure with two inputs,one output,and three layers is established.Continuous functions are constructed to enhance accuracy.Additionally,the equivalent stress can be converted into a contour distribution of a three-dimensional stress graph.The contour line distribution illustrates the matching scheme for magnetic bridge lengths under equivalent stress.Moreover,the paper explores the analysis of magnetic bridge interaction stress.The optimization levels corresponding to the length of each magnetic bridge are defined,and each level is analyzed by the finite element method.The Taguchi method is used to determine the specific gravity of the stress source on each magnetic bridge.Based on this,a multiobjective optimization employing the Multiobjective Particle Swarm Optimization(MOPSO)technique is introduced.By taking the rotor magnetic bridge as the design parameter,ten optimization objectives including air-gap flux density,sinusoidal property,average torque,torque ripple,and mechanical stress are optimized.The relationship between the optimization objectives and the design parameters can be obtained based on the response surface method(RSM)to avoid too many experimental samples.The optimized model is compared with the initial model,and the optimized effect is verified.Finally,the temperature distribution of under rated working conditions is analyzed,providing support for addressing thermal stress as mentioned earlier.
基金Supported by the National Natural Science Foundation of China under Grant No 51171028
文摘Nanocomposite ZrCN films consisting of nanocrystalline ZrCN grains embedded in nitrogen-doped amorphous carbon film are deposited by filtered cathodic vacuum arc technology under different bias voltages ranging from 50to 400 V.The influence of bias voltage on the characterization and the mechanical properties of the ZrCN films are investigated by x-ray diffraction,x-ray photoelectron spectroscopy,scanning electron microscopy,transmission electron microscopy,Raman spectroscopy and nano-indentation.The bias voltage has a subtle effect on the ZrCN grain size,which is around 9.5 nm and keeps almost constant.A slight increase of the bias voltage induces a relatively high sp^3 fraction about 40%in N-doped amorphous C films but leads to the graphitization of the films under a higher voltage.The best mechanical property of the ZrCN film with the hardness of 41 GPa is obtained under the bias voltage of 200 V,indicating the positive effect of slight increase of ion bombardment on the hardness of the films.
基金supported by the National Natural Science Foundation of China(52172120)Shanghai Science and Technology Development Funds(No.24CL2900500).
文摘Radiative cooling is a passive thermal management strategy that leverages the natural ability of materials to dissipate heat through infrared radiation.It has significant implications for energy efficiency,climate adaptation,and sustainable technology development,with applications in personal thermal management,building temperature regulation,and aerospace engineering.However,radiative cooling performance is susceptible to environmental aging and special environmental conditions,limiting its applicability in extreme environments.Herein,a critical review of extreme environmental radiative cooling is presented,focusing on enhancing environmental durability and cooling efficiency.This review first introduces the design principles of heat exchange channels,which are tailored based on the thermal flow equilibrium to optimize radiative cooling capacity in various extreme environments.Subsequently,recent advancements in radiative cooling materials and micronano structures that align with these principles are systematically discussed,with a focus on their implementation in terrestrial dwelling environments,terrestrial extreme environments,aeronautical environments,and space environments.Moreover,this review evaluates the cooling effects and anti-environmental abilities of extreme radiative cooling devices.Lastly,key challenges hindering the development of radiative cooling devices for extreme environmental applications are outlined,and potential strategies to overcome these limitations are proposed,aiming to prompt their future commercialization.
