Turbocharging is an efficient approach for addressing power reduction and oil consumption increase in aviation piston engines during high-altitude flights.However,a turbocharger significantly increases the complexity ...Turbocharging is an efficient approach for addressing power reduction and oil consumption increase in aviation piston engines during high-altitude flights.However,a turbocharger significantly increases the complexity of a power system,and its considerably complex matching relation with the engine results in a coupling of failure modes.Conventional analytical methods are hard to identify failure-inducing factors.Consequently,safety issues are becoming increasingly prominent.This study focuses on methods for identifying failure-inducing factors.A whole-machine system model is established and validated through experimentation.The response surface method is employed to further abstract the system simulation model to a surrogate model(average error:~3%)in order to reduce the computational cost while ensuring accuracy.On this basis,an improved Correspondence Analysis(CA)-Polar Angle(PA)-based Classification(PAC)is proposed to identify the key factors affecting the failure mode of turbochargers.This identification method is based on the row profile coordinates G varying with the numerical deviations of the key factors,and is capable of effectively identifying the key factors affecting the failure.In a validation example,this method identifies the diameter of the exhaust valve(e_(2))as the primary factor affecting the safety margin for each work boundary.展开更多
In order to compare the aviation network of mid-south,northwest and southwest of China to reveal the structure similarity and difference for providing quantitative evidence to construct regional aviation network and i...In order to compare the aviation network of mid-south,northwest and southwest of China to reveal the structure similarity and difference for providing quantitative evidence to construct regional aviation network and improve its structure,hierarchical index model of regional aviation network was established through dividing the aviation network into layers to research its structure characters.Data matrixes were defined to record the basic state of regional aviation network.Index matrixes were constructed to describe the quantitative features of regional aviation network.On the basis of these indexes,several structure indexes of all layers of aviation network were calculated to show the structure features of aviation network,such as ratio of passenger volume within the region with across the region,share rate of passenger volume among layers,ratio of average number of airline for each airport,ratio of average passenger volume for each airline and ratio of airline rate.According to the statistical data,similar structure of share rate of passenger volume among layers and average passenger volume for each airline in their regional aviation network was found after calculating.But on the side of ratio of passenger volume within the region with across the region,ratio of average number of airlines for each airport and ratio of airline rate were different.展开更多
In order to reveal the complex network feature of aviation network of China,probability distribution of node degree and clustering coefficient of aviation network of China was researched according to statistics data o...In order to reveal the complex network feature of aviation network of China,probability distribution of node degree and clustering coefficient of aviation network of China was researched according to statistics data of civil aviation of China.It was verified that node degree had power function probability distribution.Clustering coefficient of nodes with exponential function probability distribution was discovered.It was found that node degree and clustering coefficient had single peak nonlinear relationship.At the left side of the peak,there is no certain relationship between them.At the right side of the peak,clustering coefficient became smaller with the rise of node degree and there was negative exponential function relationship between them by regression analysis.展开更多
A brief concept study of a modular research aircraft with potential applications to Mars exploration is conducted.Considered are dimensional and mass constraints of a launch vehicle payload compartment,mission radius ...A brief concept study of a modular research aircraft with potential applications to Mars exploration is conducted.Considered are dimensional and mass constraints of a launch vehicle payload compartment,mission radius extension applying ground mobility and overall flight envelope extension using fixed-wing aerodynamics.Also,some lessons learned from NASA Mars Ingenuity flights are considered and addressed with few solutions.The modular system includes a fixed-wing design along with a number of smaller autonomous quadcopter UAVs,encapsulated inside a geodesic spherical support through a gimbal mechanism for ground mobility.Analyzed is the feasibility of allocating to these mini drones both scout and mapping tasks of complex terrain such as crater walls,canyons and cave systems that might hold key insights into the planet's geologic history.Once docked with the mothership fixed wing,the mini drones serve as a distributed propulsion system,for vertical take-off and landing and control,completely replacing control surfaces on the flying wing itself,its engine and landing gear.CFD and structural simulations have demonstrated the flight-ability in Mars conditions of a flying wing design along with scout drone prototypes with a pentagon-hexagon geodesic shell.Also demonstrated is the great flexibility of the suggested modular approach for various research applications and mission profiles on Mars and other planets or moons,improving overall reliability and mission radius.展开更多
The article considers the impact of forestry machines on the soil of the cutting areas and presents the results of the impact of harvesters of different classes(middlesmall,middle and heavy)and configurations of wheel...The article considers the impact of forestry machines on the soil of the cutting areas and presents the results of the impact of harvesters of different classes(middlesmall,middle and heavy)and configurations of wheeled equipment and additional equipment on the soil of the cutting areas in the conditions of Kronoberg County(South of Sweden).Methods to reduce negative impact of wheeled harvesters on the soil of forests are proposed.The aim of the research is to assess the effect of the structural parameters of the wheel harvesters of different class on the soil of the cutting areas.Wheeled harvesters were loaded with 60 kN force.The results of experimental studies of the impact of wheeled harvesters on the forest soil are presented.Recommendations on the possibility of testing the results of research in the conditions of the rental base of the Western part of the North-Western Federal District of the Russian Federation are given.展开更多
In the context of the continuous advancement of teaching reform,the optimization of the curriculum evaluation system has become a key issue in the field of education.This study focuses on the course of educational psy...In the context of the continuous advancement of teaching reform,the optimization of the curriculum evaluation system has become a key issue in the field of education.This study focuses on the course of educational psychology,using the final examination papers and scores of the 2022 Physical Education Major and 2024 Early Childhood Education Major undergraduate students at Yunnan Technology and Business University as samples.Basic statistical analysis methods are employed to conduct an in-depth investigation.The results show that the overall difficulty of the exam papers is moderate(0.7),with acceptable reliability(0.78)and good validity(0.7-0.8).However,the failure rate among students reaches 21.3%,reflecting learning difficulties.There is no significant difference in scores between students from different majors,attributed to the same teaching conditions and equal emphasis on the course by both majors.This study provides data support for the teaching of educational psychology courses,assisting teachers in improving their teaching based on the results,meeting the demands of teaching reform for precise teaching evaluation and quality enhancement,and promoting the development of educational psychology course teaching.展开更多
Wastewater plays a crucial role in deteriorating water quality and can significantly affect human health and ecosystems if discharged without proper treatment.Among available treatment methods,adsorption is often cons...Wastewater plays a crucial role in deteriorating water quality and can significantly affect human health and ecosystems if discharged without proper treatment.Among available treatment methods,adsorption is often considered an effective,relatively inexpensive,and environmentally friendly purification technique,but its efficiency depends on the sorbents used.The use of low-cost biosorbents with high adsorption capacity is widely studied.These include various biomaterials such as microalgae,cyanobacteria,fungi,and plant materials.The utilization of different biosorbents derived from plant waste,such as Paulownia wood,aspen,hickory,Ziziphus bark,peach tree shavings,as well as grasses such as red fescue and reed,and Sargassum algae in natural and modified forms,is a crucial research direction.Such studies highlight the potential to address waste issues by repurposing it as biosorbents.Several studies have examined the ability of different biosorbents to treat wastewater and suggested that the physicochemical properties of the material's surface,such as specific surface area,pore size,and pore volume,play a decisive role in adsorption capacity.A quantitative analysis of plant-based biosorbents will significantly aid in developing water treatment systems and achieving optimal adsorption through modifications of their physicochemical properties.Furthermore,the analysis will help understand the relative importance of each physicochemical property in determining adsorption capacity,thereby contributing to the implementation of treatment methods targeting specific pollutants.展开更多
To overcome the challenges of limited experimental data and improve the accuracy of empirical formulas,we propose a low-cycle fatigue(LCF)life prediction model for nickel-based superalloys using a data augmentation me...To overcome the challenges of limited experimental data and improve the accuracy of empirical formulas,we propose a low-cycle fatigue(LCF)life prediction model for nickel-based superalloys using a data augmentation method.This method utilizes a variational autoencoder(VAE)to generate low-cycle fatigue data and form an augmented dataset.The Pearson correlation coefficient(PCC)is employed to verify the similarity of feature distributions between the original and augmented datasets.Six machine learning models,namely random forest(RF),artificial neural network(ANN),support vector machine(SVM),gradient-boosted decision tree(GBDT),eXtreme Gradient Boosting(XGBoost),and Categorical Boosting(CatBoost),are utilized to predict the LCF life of nickel-based superalloys.Results indicate that the proposed data augmentation method based on VAE can effectively expand the dataset,and the mean absolute error(MAE),root mean square error(RMSE),and R-squared(R^(2))values achieved using the CatBoost model,with respective values of 0.0242,0.0391,and 0.9538,are superior to those of the other models.The proposed method reduces the cost and time associated with LCF experiments and accurately establishes the relationship between fatigue characteristics and LCF life of nickel-based superalloys.展开更多
It has been known that the lack of excellent corrosion resistance is the key problem restricting the wide application of Mg−Li alloys.Based on a quantity of literature about corrosion behavior of Mg−Li alloys,this rev...It has been known that the lack of excellent corrosion resistance is the key problem restricting the wide application of Mg−Li alloys.Based on a quantity of literature about corrosion behavior of Mg−Li alloys,this review elaborates the factors affecting the corrosion behavior of Mg−Li alloys and the processing methods for improving corrosion resistance.The corrosion characteristics of Mg−Li alloys are described firstly.Then,it is explained that the grain size,orientation,second phase,and surface film strongly influence corrosion performance,which can be tailored by alloying,plastic deformation,and heat treatment.Further in-depth discussion about the corrosion mechanisms for Mg−Li alloys was also presented.Finally,important points of improving corrosion resistance are suggested.展开更多
Recent years have witnessed a booming of the industry of civil Unmanned Aircraft System(UAS).As an emerging industry,the UAS industry has been attracting great attention from governments of all countries and the aviat...Recent years have witnessed a booming of the industry of civil Unmanned Aircraft System(UAS).As an emerging industry,the UAS industry has been attracting great attention from governments of all countries and the aviation industry.UAS are highly digitalized,informationized,and intelligent;therefore,their integration into the national airspace system has become an important trend in the development of civil aviation.However,the complexity of UAS operation poses great challenges to the traditional aviation regulatory system and technical means.How to prevent collisions between UASs and between UAS and manned aircraft to achieve safe and efficient operation in the integrated operating airspace has become a common challenge for industry and academia around the world.In recent years,the international community has carried out a great amount of work and experiments in the air traffic management of UAS and some of the key technologies.This paper attempts to make a review of the UAS separation management and key technologies in collision avoidance in the integrated airspace,mainly focusing on the current situation of UAS Traffic Management(UTM),safety separation standards,detection system,collision risk prediction,collision avoidance,safety risk assessment,etc.,as well as an analysis of the bottlenecks that the current researches encountered and their development trends,so as to provide some insights and references for further research in this regard.Finally,this paper makes a further summary of some of the research highlights and challenges.展开更多
Calcium phosphate(CaP) coatings were prepared on Mg–8Li–2Ca magnesium alloy by micro-arc oxidation(MAO) in an alkaline Na_3PO_4–Ca[C_3H_7O_6P] base solution at the different applied voltages. Scanning electron micr...Calcium phosphate(CaP) coatings were prepared on Mg–8Li–2Ca magnesium alloy by micro-arc oxidation(MAO) in an alkaline Na_3PO_4–Ca[C_3H_7O_6P] base solution at the different applied voltages. Scanning electron microscope and X-ray diffraction were employed to characterize the microstructure and phase composition of the coatings, respectively. The corrosion resistance of the coatings was assessed by potential dynamic polarization curves, electrochemical impedance spectroscopy and hydrogen evolution experiment in simulated body fluids solution. The friction and wear properties were evaluated by friction and wear testing machine. The results demonstrate that the coating surface is porous and mainly composed of MgO, Ca_5(PO_4)_3(OH) and CaH_2P_2O_5. With the increase in voltage, the corrosion resistance and wear resistance of the MAO coating are both enhanced. The corrosion current density of the MAO coating decreases about two orders of the magnitude compared to the substrate. Additionally, wear and corrosion mechanisms are discussed.展开更多
The original free vortex wake model was used for numerical investigation.Calculation of the aerodynamic characteristics in hover and vertical descent modes in the range of vertical descent speed of 0–30 m/s including...The original free vortex wake model was used for numerical investigation.Calculation of the aerodynamic characteristics in hover and vertical descent modes in the range of vertical descent speed of 0–30 m/s including the Vortex Ring State(VRS)area was performed.The calculations were carried out under the condition of variable blade pitch angle values providing a fixed timeaverage thrust value.Visualization data of free vortex wake shapes,flow structures,and velocity fields were obtained and analyzed.The time-dependences of the rotor’s thrust and torque coefficients were obtained and analyzed.The obtained data allows determining the boundaries of the VRS area by various criteria such as rotor thrust and torque pulsations,growth of rotor power consumption relative to the hover,growth of rotor induced velocities relative to the hover,and growth of the required rotor blade pitch angles values.The results of the study are compared with experimental and calculated data of other authors and can significantly supplement the available results of experimental and computational studies in this area.展开更多
Several methods dealing with the moist adiabatic process are described in this paper. They are based on static energy conservation, pseudo-equivalent potential temperature conservation, the strict pseudo- adiabati...Several methods dealing with the moist adiabatic process are described in this paper. They are based on static energy conservation, pseudo-equivalent potential temperature conservation, the strict pseudo- adiabatic equation, and the reversible moist adiabatic process, respectively. Convective energy parame- ters, which are closely related to the moist adiabatic process and which re?ect the gravitational e?ects of condensed liquid water, are reintroduced or de?ned, including MCAPE [Modi?ed-CAPE (convective avail- able potential energy)], DCAPE (Downdraft-CAPE), and MDCAPE (Modi?ed-Downdraft-CAPE). Two real case analyses with special attention given to condensed liquid water show that the selection of moist adiabatic process does a?ect the calculated results of CAPE and the gravitational e?ects of condensed liq- uid water are not negligible in severe storms. Intercomparisons of these methods show that static energy conservation is consistent with pseudo-equivalent potential temperature conservation not only in physical properties but also in calculated results, and both are good approximations to the strict pseudo-adiabatic equation. The lapse rate linked with the reversible moist adiabatic process is relatively smaller than that linked with other moist adiabatic processes, especially when considering solidi?cation of liquid water in the reversible adiabatic process.展开更多
A coupling fluid-structure method with a combination of viscous wake model（VWM）,computational fluid dynamics（CFD） and comprehensive structural dynamics（CSD） modules is developed in this paper for rotor unsteady ...A coupling fluid-structure method with a combination of viscous wake model（VWM）,computational fluid dynamics（CFD） and comprehensive structural dynamics（CSD） modules is developed in this paper for rotor unsteady airload prediction. The hybrid VWM/CFD solver is employed to model the nonlinear aerodynamic phenomena and complicated rotor wake dynamics;the moderate deflection beam theory is implemented to predict the blade structural deformation; the loose coupling strategy based on the ‘delt method＇ is used to couple the fluid and structure solvers.Several cases of Helishape 7A rotor are performed first to investigate the effect of elastic deformation on airloads. Then, two challenging forward flight conditions of UH-60 A helicopter rotor are investigated, and the simulated results of wake geometry, chordwise pressure distribution and sectional normal force show excellent agreement with available test data; a comparison with traditional CFD/CSD method is also presented to illustrate the efficiency of the developed method.展开更多
Carbonate was added to the silicate system electrolyte to improve the corrosion resistance of the plasma electrolytic oxidation coating on Mg-9Li-3Al(wt%,LA93)alloy.The influences of carbonate on the morphology,struct...Carbonate was added to the silicate system electrolyte to improve the corrosion resistance of the plasma electrolytic oxidation coating on Mg-9Li-3Al(wt%,LA93)alloy.The influences of carbonate on the morphology,structure,and phase composition of the coating were investigated by scanning electron microscopy,energy dispersive spectrometry,X-ray diffraction,and X-ray photoelectron spectroscopy.The corrosion resistance of the coating was evaluated by electrochemical experiment,hydrogen evolution,and immersion test.The results showed that the addition of carbonate resulted in a denser coating with increased hardness,and the corrosion-resistant Li_(2)CO_(3) phase was formed.Electrochemical experiments showed that compared with the coating without carbonate,the corrosion potential of the carbonate coating positively shifted(24 mV),and the corrosion current density was reduced by approximately an order of magnitude.The coating with carbonate addition possessed a high corrosion resistance and long-term protection capability.展开更多
Laser micro cladding deposition manufacturing(Ll CDM) is a newly developed rapid manufacturing method for metals.The Ll CDM technology adopts a novel powder feeding method based on alternating friction and inertia for...Laser micro cladding deposition manufacturing(Ll CDM) is a newly developed rapid manufacturing method for metals.The Ll CDM technology adopts a novel powder feeding method based on alternating friction and inertia force, and this powder feeding method can effectively improve the accuracy and orientation of the powder injection, resulting in a smaller molten pool size and a higher cooling rate of liquid metal.Therefore, the components fabricated by Ll CDM could obtain the finer microstructures and the improved mechanical properties.It is found that the components fabricated by Ll CDM are fully dense free of cracks or pores and exhibit columnar prior b grains with a finer acicular a0 phase microstructure.The microhardness(HV0.2) of the thin-wall component is HV 400–HV 500 in the majority part of the cross section and can reach about HV 850 in the top region.The ultimate tensile strength(UTS) and elongation show insignificant dependence on the testing directions of the tensilespecimens.The UTS is between 1,002 and 1,100 MPa, and the elongation is between 10.0 % and 14.7 %.展开更多
Aiming at addressing the problem of manoeuvring decision-making in UAV air combat,this study establishes a one-to-one air combat model,defines missile attack areas,and uses the non-deterministic policy Soft-Actor-Crit...Aiming at addressing the problem of manoeuvring decision-making in UAV air combat,this study establishes a one-to-one air combat model,defines missile attack areas,and uses the non-deterministic policy Soft-Actor-Critic(SAC)algorithm in deep reinforcement learning to construct a decision model to realize the manoeuvring process.At the same time,the complexity of the proposed algorithm is calculated,and the stability of the closed-loop system of air combat decision-making controlled by neural network is analysed by the Lyapunov function.This study defines the UAV air combat process as a gaming process and proposes a Parallel Self-Play training SAC algorithm(PSP-SAC)to improve the generalisation performance of UAV control decisions.Simulation results have shown that the proposed algorithm can realize sample sharing and policy sharing in multiple combat environments and can significantly improve the generalisation ability of the model compared to independent training.展开更多
基金supported by the Innovation Team of Complex System Safety and Airworthiness of Aeroengine from the Co-Innovation Center for Advanced Aeroengine of Chinafunded by the National Natural Science Foundation of China and the Civil Aviation Administration of China(No.U1833109)。
文摘Turbocharging is an efficient approach for addressing power reduction and oil consumption increase in aviation piston engines during high-altitude flights.However,a turbocharger significantly increases the complexity of a power system,and its considerably complex matching relation with the engine results in a coupling of failure modes.Conventional analytical methods are hard to identify failure-inducing factors.Consequently,safety issues are becoming increasingly prominent.This study focuses on methods for identifying failure-inducing factors.A whole-machine system model is established and validated through experimentation.The response surface method is employed to further abstract the system simulation model to a surrogate model(average error:~3%)in order to reduce the computational cost while ensuring accuracy.On this basis,an improved Correspondence Analysis(CA)-Polar Angle(PA)-based Classification(PAC)is proposed to identify the key factors affecting the failure mode of turbochargers.This identification method is based on the row profile coordinates G varying with the numerical deviations of the key factors,and is capable of effectively identifying the key factors affecting the failure.In a validation example,this method identifies the diameter of the exhaust valve(e_(2))as the primary factor affecting the safety margin for each work boundary.
文摘In order to compare the aviation network of mid-south,northwest and southwest of China to reveal the structure similarity and difference for providing quantitative evidence to construct regional aviation network and improve its structure,hierarchical index model of regional aviation network was established through dividing the aviation network into layers to research its structure characters.Data matrixes were defined to record the basic state of regional aviation network.Index matrixes were constructed to describe the quantitative features of regional aviation network.On the basis of these indexes,several structure indexes of all layers of aviation network were calculated to show the structure features of aviation network,such as ratio of passenger volume within the region with across the region,share rate of passenger volume among layers,ratio of average number of airline for each airport,ratio of average passenger volume for each airline and ratio of airline rate.According to the statistical data,similar structure of share rate of passenger volume among layers and average passenger volume for each airline in their regional aviation network was found after calculating.But on the side of ratio of passenger volume within the region with across the region,ratio of average number of airlines for each airport and ratio of airline rate were different.
文摘In order to reveal the complex network feature of aviation network of China,probability distribution of node degree and clustering coefficient of aviation network of China was researched according to statistics data of civil aviation of China.It was verified that node degree had power function probability distribution.Clustering coefficient of nodes with exponential function probability distribution was discovered.It was found that node degree and clustering coefficient had single peak nonlinear relationship.At the left side of the peak,there is no certain relationship between them.At the right side of the peak,clustering coefficient became smaller with the rise of node degree and there was negative exponential function relationship between them by regression analysis.
基金funded by the Russian Science Foundation(No.22–49-02047)。
文摘A brief concept study of a modular research aircraft with potential applications to Mars exploration is conducted.Considered are dimensional and mass constraints of a launch vehicle payload compartment,mission radius extension applying ground mobility and overall flight envelope extension using fixed-wing aerodynamics.Also,some lessons learned from NASA Mars Ingenuity flights are considered and addressed with few solutions.The modular system includes a fixed-wing design along with a number of smaller autonomous quadcopter UAVs,encapsulated inside a geodesic spherical support through a gimbal mechanism for ground mobility.Analyzed is the feasibility of allocating to these mini drones both scout and mapping tasks of complex terrain such as crater walls,canyons and cave systems that might hold key insights into the planet's geologic history.Once docked with the mothership fixed wing,the mini drones serve as a distributed propulsion system,for vertical take-off and landing and control,completely replacing control surfaces on the flying wing itself,its engine and landing gear.CFD and structural simulations have demonstrated the flight-ability in Mars conditions of a flying wing design along with scout drone prototypes with a pentagon-hexagon geodesic shell.Also demonstrated is the great flexibility of the suggested modular approach for various research applications and mission profiles on Mars and other planets or moons,improving overall reliability and mission radius.
文摘The article considers the impact of forestry machines on the soil of the cutting areas and presents the results of the impact of harvesters of different classes(middlesmall,middle and heavy)and configurations of wheeled equipment and additional equipment on the soil of the cutting areas in the conditions of Kronoberg County(South of Sweden).Methods to reduce negative impact of wheeled harvesters on the soil of forests are proposed.The aim of the research is to assess the effect of the structural parameters of the wheel harvesters of different class on the soil of the cutting areas.Wheeled harvesters were loaded with 60 kN force.The results of experimental studies of the impact of wheeled harvesters on the forest soil are presented.Recommendations on the possibility of testing the results of research in the conditions of the rental base of the Western part of the North-Western Federal District of the Russian Federation are given.
文摘In the context of the continuous advancement of teaching reform,the optimization of the curriculum evaluation system has become a key issue in the field of education.This study focuses on the course of educational psychology,using the final examination papers and scores of the 2022 Physical Education Major and 2024 Early Childhood Education Major undergraduate students at Yunnan Technology and Business University as samples.Basic statistical analysis methods are employed to conduct an in-depth investigation.The results show that the overall difficulty of the exam papers is moderate(0.7),with acceptable reliability(0.78)and good validity(0.7-0.8).However,the failure rate among students reaches 21.3%,reflecting learning difficulties.There is no significant difference in scores between students from different majors,attributed to the same teaching conditions and equal emphasis on the course by both majors.This study provides data support for the teaching of educational psychology courses,assisting teachers in improving their teaching based on the results,meeting the demands of teaching reform for precise teaching evaluation and quality enhancement,and promoting the development of educational psychology course teaching.
文摘Wastewater plays a crucial role in deteriorating water quality and can significantly affect human health and ecosystems if discharged without proper treatment.Among available treatment methods,adsorption is often considered an effective,relatively inexpensive,and environmentally friendly purification technique,but its efficiency depends on the sorbents used.The use of low-cost biosorbents with high adsorption capacity is widely studied.These include various biomaterials such as microalgae,cyanobacteria,fungi,and plant materials.The utilization of different biosorbents derived from plant waste,such as Paulownia wood,aspen,hickory,Ziziphus bark,peach tree shavings,as well as grasses such as red fescue and reed,and Sargassum algae in natural and modified forms,is a crucial research direction.Such studies highlight the potential to address waste issues by repurposing it as biosorbents.Several studies have examined the ability of different biosorbents to treat wastewater and suggested that the physicochemical properties of the material's surface,such as specific surface area,pore size,and pore volume,play a decisive role in adsorption capacity.A quantitative analysis of plant-based biosorbents will significantly aid in developing water treatment systems and achieving optimal adsorption through modifications of their physicochemical properties.Furthermore,the analysis will help understand the relative importance of each physicochemical property in determining adsorption capacity,thereby contributing to the implementation of treatment methods targeting specific pollutants.
基金Financial support from the Fundamental Research Funds for the Central Universities(ZJ2022-003,JG2022-27,J2020-060,and J2021-060)Sichuan Province Engineering Technology Research Center of General Aircraft Maintenance(GAMRC2021YB08)the Young Scientists Fund of the National Natural Science Foundation of China(No.52105417)is acknowledged.
文摘To overcome the challenges of limited experimental data and improve the accuracy of empirical formulas,we propose a low-cycle fatigue(LCF)life prediction model for nickel-based superalloys using a data augmentation method.This method utilizes a variational autoencoder(VAE)to generate low-cycle fatigue data and form an augmented dataset.The Pearson correlation coefficient(PCC)is employed to verify the similarity of feature distributions between the original and augmented datasets.Six machine learning models,namely random forest(RF),artificial neural network(ANN),support vector machine(SVM),gradient-boosted decision tree(GBDT),eXtreme Gradient Boosting(XGBoost),and Categorical Boosting(CatBoost),are utilized to predict the LCF life of nickel-based superalloys.Results indicate that the proposed data augmentation method based on VAE can effectively expand the dataset,and the mean absolute error(MAE),root mean square error(RMSE),and R-squared(R^(2))values achieved using the CatBoost model,with respective values of 0.0242,0.0391,and 0.9538,are superior to those of the other models.The proposed method reduces the cost and time associated with LCF experiments and accurately establishes the relationship between fatigue characteristics and LCF life of nickel-based superalloys.
基金financial supports from the Natural Science Foundation of China (Nos. 51771060, 51871068, 51971071, 52011530025)the Domain Foundation of Equipment Advance Research of the 13th Fiveyear Plan, China (No. 61409220118)+2 种基金the National Key Research and Development Program, China (No. 2021YFE0103200)the Zhejiang Province Key Research and Development Program, China (No. 2021C01086)the Open Foundation of Key Laboratory of Superlight Materials & Surface Technology of Ministry of Education, China (No. HEU10202104)。
文摘It has been known that the lack of excellent corrosion resistance is the key problem restricting the wide application of Mg−Li alloys.Based on a quantity of literature about corrosion behavior of Mg−Li alloys,this review elaborates the factors affecting the corrosion behavior of Mg−Li alloys and the processing methods for improving corrosion resistance.The corrosion characteristics of Mg−Li alloys are described firstly.Then,it is explained that the grain size,orientation,second phase,and surface film strongly influence corrosion performance,which can be tailored by alloying,plastic deformation,and heat treatment.Further in-depth discussion about the corrosion mechanisms for Mg−Li alloys was also presented.Finally,important points of improving corrosion resistance are suggested.
基金co-supported by the National Natural Science Foundation of China(Nos.U1933130,U1533119 and 71731001)the Major Project of Technological Innovation,China(No.2018AAA0100800)。
文摘Recent years have witnessed a booming of the industry of civil Unmanned Aircraft System(UAS).As an emerging industry,the UAS industry has been attracting great attention from governments of all countries and the aviation industry.UAS are highly digitalized,informationized,and intelligent;therefore,their integration into the national airspace system has become an important trend in the development of civil aviation.However,the complexity of UAS operation poses great challenges to the traditional aviation regulatory system and technical means.How to prevent collisions between UASs and between UAS and manned aircraft to achieve safe and efficient operation in the integrated operating airspace has become a common challenge for industry and academia around the world.In recent years,the international community has carried out a great amount of work and experiments in the air traffic management of UAS and some of the key technologies.This paper attempts to make a review of the UAS separation management and key technologies in collision avoidance in the integrated airspace,mainly focusing on the current situation of UAS Traffic Management(UTM),safety separation standards,detection system,collision risk prediction,collision avoidance,safety risk assessment,etc.,as well as an analysis of the bottlenecks that the current researches encountered and their development trends,so as to provide some insights and references for further research in this regard.Finally,this paper makes a further summary of some of the research highlights and challenges.
基金supported by the National Natural Science Foundation of China(Nos.51671063,51771060 and51871068)the Key Laboratory of Lightweight and high strength structural materials of Jiangxi Province(No.20171BCD40003)+4 种基金the Research Fund for the Doctoral Program of Higher Education(No.20132304110006)Heilongjiang Province Natural Science Foundation(No.ZD2017010)the Fundamental Research Funds for the Central Universities(No.HEUCFG201834)the Harbin City Application Technology Research and Development Project(Nos.2015RQXXJ001 and 2017RAQXJ032)the Science and Technology Innovation Project(No.009-031-001)
文摘Calcium phosphate(CaP) coatings were prepared on Mg–8Li–2Ca magnesium alloy by micro-arc oxidation(MAO) in an alkaline Na_3PO_4–Ca[C_3H_7O_6P] base solution at the different applied voltages. Scanning electron microscope and X-ray diffraction were employed to characterize the microstructure and phase composition of the coatings, respectively. The corrosion resistance of the coatings was assessed by potential dynamic polarization curves, electrochemical impedance spectroscopy and hydrogen evolution experiment in simulated body fluids solution. The friction and wear properties were evaluated by friction and wear testing machine. The results demonstrate that the coating surface is porous and mainly composed of MgO, Ca_5(PO_4)_3(OH) and CaH_2P_2O_5. With the increase in voltage, the corrosion resistance and wear resistance of the MAO coating are both enhanced. The corrosion current density of the MAO coating decreases about two orders of the magnitude compared to the substrate. Additionally, wear and corrosion mechanisms are discussed.
基金Project supported by the National High-Tech R&D Program(863 Program)of China(No.2014AA0415011)the Research Fund for the Doctoral Program of Higher Education of China(No.2014QD02S)+1 种基金the Research Fund for the Doctoral Program of Higher Education of China(No.2013QD03S)the Fundamental Research Funds for the Central Universities(No.3122015C015),China
文摘The original free vortex wake model was used for numerical investigation.Calculation of the aerodynamic characteristics in hover and vertical descent modes in the range of vertical descent speed of 0–30 m/s including the Vortex Ring State(VRS)area was performed.The calculations were carried out under the condition of variable blade pitch angle values providing a fixed timeaverage thrust value.Visualization data of free vortex wake shapes,flow structures,and velocity fields were obtained and analyzed.The time-dependences of the rotor’s thrust and torque coefficients were obtained and analyzed.The obtained data allows determining the boundaries of the VRS area by various criteria such as rotor thrust and torque pulsations,growth of rotor power consumption relative to the hover,growth of rotor induced velocities relative to the hover,and growth of the required rotor blade pitch angles values.The results of the study are compared with experimental and calculated data of other authors and can significantly supplement the available results of experimental and computational studies in this area.
基金the National Natural Science Fourdation of China under Grant Nos.40375016 , 40428002 InnovationProject of the Chinese Academy of Sciences under Grant No.KZCX-SW-213.
文摘Several methods dealing with the moist adiabatic process are described in this paper. They are based on static energy conservation, pseudo-equivalent potential temperature conservation, the strict pseudo- adiabatic equation, and the reversible moist adiabatic process, respectively. Convective energy parame- ters, which are closely related to the moist adiabatic process and which re?ect the gravitational e?ects of condensed liquid water, are reintroduced or de?ned, including MCAPE [Modi?ed-CAPE (convective avail- able potential energy)], DCAPE (Downdraft-CAPE), and MDCAPE (Modi?ed-Downdraft-CAPE). Two real case analyses with special attention given to condensed liquid water show that the selection of moist adiabatic process does a?ect the calculated results of CAPE and the gravitational e?ects of condensed liq- uid water are not negligible in severe storms. Intercomparisons of these methods show that static energy conservation is consistent with pseudo-equivalent potential temperature conservation not only in physical properties but also in calculated results, and both are good approximations to the strict pseudo-adiabatic equation. The lapse rate linked with the reversible moist adiabatic process is relatively smaller than that linked with other moist adiabatic processes, especially when considering solidi?cation of liquid water in the reversible adiabatic process.
基金supported by the National Natural Science Foundation of China (No. 11302103)
文摘A coupling fluid-structure method with a combination of viscous wake model（VWM）,computational fluid dynamics（CFD） and comprehensive structural dynamics（CSD） modules is developed in this paper for rotor unsteady airload prediction. The hybrid VWM/CFD solver is employed to model the nonlinear aerodynamic phenomena and complicated rotor wake dynamics;the moderate deflection beam theory is implemented to predict the blade structural deformation; the loose coupling strategy based on the ‘delt method＇ is used to couple the fluid and structure solvers.Several cases of Helishape 7A rotor are performed first to investigate the effect of elastic deformation on airloads. Then, two challenging forward flight conditions of UH-60 A helicopter rotor are investigated, and the simulated results of wake geometry, chordwise pressure distribution and sectional normal force show excellent agreement with available test data; a comparison with traditional CFD/CSD method is also presented to illustrate the efficiency of the developed method.
基金the Natural Science Foundation of China (Nos.51771060,51871068,51971071,and 52011530025)the Domain Foundation of Equipment Advance Research of 13th Five-year Plan,China(No.61409220118)+1 种基金the Zhejiang Province Key Research and Development Program,China (No.2021C01086)the Open Foundation of Key Laboratory of Superlight Materials&Surface Technology of Ministry of Education,China (No.HEU10202104)
文摘Carbonate was added to the silicate system electrolyte to improve the corrosion resistance of the plasma electrolytic oxidation coating on Mg-9Li-3Al(wt%,LA93)alloy.The influences of carbonate on the morphology,structure,and phase composition of the coating were investigated by scanning electron microscopy,energy dispersive spectrometry,X-ray diffraction,and X-ray photoelectron spectroscopy.The corrosion resistance of the coating was evaluated by electrochemical experiment,hydrogen evolution,and immersion test.The results showed that the addition of carbonate resulted in a denser coating with increased hardness,and the corrosion-resistant Li_(2)CO_(3) phase was formed.Electrochemical experiments showed that compared with the coating without carbonate,the corrosion potential of the carbonate coating positively shifted(24 mV),and the corrosion current density was reduced by approximately an order of magnitude.The coating with carbonate addition possessed a high corrosion resistance and long-term protection capability.
基金financially supported by the National Natural Science Foundation of China (No. 50975152)
文摘Laser micro cladding deposition manufacturing(Ll CDM) is a newly developed rapid manufacturing method for metals.The Ll CDM technology adopts a novel powder feeding method based on alternating friction and inertia force, and this powder feeding method can effectively improve the accuracy and orientation of the powder injection, resulting in a smaller molten pool size and a higher cooling rate of liquid metal.Therefore, the components fabricated by Ll CDM could obtain the finer microstructures and the improved mechanical properties.It is found that the components fabricated by Ll CDM are fully dense free of cracks or pores and exhibit columnar prior b grains with a finer acicular a0 phase microstructure.The microhardness(HV0.2) of the thin-wall component is HV 400–HV 500 in the majority part of the cross section and can reach about HV 850 in the top region.The ultimate tensile strength(UTS) and elongation show insignificant dependence on the testing directions of the tensilespecimens.The UTS is between 1,002 and 1,100 MPa, and the elongation is between 10.0 % and 14.7 %.
基金National Natural Science Foundation of China,Grant/Award Number:62003267Fundamental Research Funds for the Central Universities,Grant/Award Number:G2022KY0602+1 种基金Technology on Electromagnetic Space Operations and Applications Laboratory,Grant/Award Number:2022ZX0090Key Core Technology Research Plan of Xi'an,Grant/Award Number:21RGZN0016。
文摘Aiming at addressing the problem of manoeuvring decision-making in UAV air combat,this study establishes a one-to-one air combat model,defines missile attack areas,and uses the non-deterministic policy Soft-Actor-Critic(SAC)algorithm in deep reinforcement learning to construct a decision model to realize the manoeuvring process.At the same time,the complexity of the proposed algorithm is calculated,and the stability of the closed-loop system of air combat decision-making controlled by neural network is analysed by the Lyapunov function.This study defines the UAV air combat process as a gaming process and proposes a Parallel Self-Play training SAC algorithm(PSP-SAC)to improve the generalisation performance of UAV control decisions.Simulation results have shown that the proposed algorithm can realize sample sharing and policy sharing in multiple combat environments and can significantly improve the generalisation ability of the model compared to independent training.
