The wheels have a considerable influence on the aerodynamic properties and can contribute up to 25%of the total drag on modern vehicles.In this study,the effect of the wheel spoke structure on the aerodynamic performa...The wheels have a considerable influence on the aerodynamic properties and can contribute up to 25%of the total drag on modern vehicles.In this study,the effect of the wheel spoke structure on the aerodynamic performance of the isolated wheel is investigated.Subsequently,the 35°Ahmed body with an optimized spoke structure is used to analyze the flow behavior and the mechanism of drag reduction.The Fluent software is employed for this investigation,with an inlet velocity of 40 m/s.The accuracy of the numerical study is validated by comparing it with experimental results obtained from the classical Ahmed model.To gain a clearer understanding of the effects of the wheel spoke parameters on the aerodynamics of both the wheel and Ahmedmodel,and five design variables are proposed:the fillet angleα,the inside arc radius R1,the outside radius R2,and the same length of the chord L1 and L2.These variables characterize the wheel spoke structure.The Optimal Latin Hypercube designmethod is utilized to conduct the experimental design.Based on the simulation results of various wheel spoke designs,the Kriging model and the adaptive simulated annealing algorithm is selected to optimize the design parameters.The objective is to achieve the best combination for maximum drag reduction.It is indicated that the optimized spoke structure resulted in amaximum drag reduction of 5.7%and 4.7%for the drag coefficient of the isolated wheel and Ahmed body,respectively.The drag reduction is primarily attributed to changes in the flow state around the wheel,which suppressed separation bubbles.Additionally,it influenced the boundary layer thickness around the car body and reduced the turbulent kinetic energy in the wake flow.These effects collectively contributed to the observed drag reduction.展开更多
目的探索Hub and Spoke教学法在助产课程教学中的应用效果,并对助产学学生对其的认知和态度进行分析。方法 2018年2月至2018年12月,将46名助产本科生作为主体,完成10份教学案例的设计。采用组建Hub and Spoke训练小组、进行课前理论讲...目的探索Hub and Spoke教学法在助产课程教学中的应用效果,并对助产学学生对其的认知和态度进行分析。方法 2018年2月至2018年12月,将46名助产本科生作为主体,完成10份教学案例的设计。采用组建Hub and Spoke训练小组、进行课前理论讲解、确定Hub and Spoke训练模式与目标、学员角色演练和自我总结、老师总结反馈的教学方法来进行授课。同时,采用自制量表以学生为主体进行Hub and Spoke教学法的效果评价,了解学生对Hub and Spoke教学法教学效果的评价。结果 56.52%的助产本科生知道也基本了解Hub and Spoke教学法。65.22%助产学生愿意使用Hub and Spoke教学法进行学习。多数助产本科生认为Hub and Spoke教学法的应用对其知识学习有不同程度的帮助。且助产本科生对Hub and Spoke教学法的自我评价得分较高。结论 Hub and Spoke教学模式可以作为很好的教学方法,能够帮助助产学学生提高临床技能应用和学习效果。展开更多
The 10-MeV Accelerator-Driven Subcritical(ADS)system Injector-I test stand at the Institute of High Energy Physics(IHEP)is a testing facility dedicated to demonstrating the feasibility of the spoke-based super-conduct...The 10-MeV Accelerator-Driven Subcritical(ADS)system Injector-I test stand at the Institute of High Energy Physics(IHEP)is a testing facility dedicated to demonstrating the feasibility of the spoke-based super-conducting(SC)linear accelerator(linac)for the ADS project in China.The injector adopted a four-vane copper structure radio frequency quadrupole(RFQ)with an output energy of 3.2 MeV and an SC section accommodating 14 β_(g)=0.12 single spoke cavities,14 SC solenoids,and 14 cold beam position monitors(BPMs).A 10-MeV pulsed beam with a beam current of 10 mA and a 2-mA continuous wave(CW)beam were successfully shooting through.The commissioning results confirmed the feasibility of using a 325-MHz spoke-type cavity for accelerating the proton beam in the low β and medium β sections.This paper describes the results achieved,the difficulties encountered,and the experiences obtained during commissioning.展开更多
Dual mechanical port machine（DMPM）, as a novel electromechanical energy conversion device, has attracted widespread attention. DMPM with spoke type permanent magnet arrangements（STPM-DMPM）, which is one of several...Dual mechanical port machine（DMPM）, as a novel electromechanical energy conversion device, has attracted widespread attention. DMPM with spoke type permanent magnet arrangements（STPM-DMPM）, which is one of several types of DMPM, has been of interest recently. The unique coupling characteristics of STPM-DMPM are beneficial to improving system performance, but these same characteristics increase the difficulties of control. Now there has been little research about the control of STPM-DMPM, and this has hindered its practical application. Based on a mathematical model of STPM-DMPM, the coupling characteristics and the merits and demerits of such devices are analyzed as applied to a hybrid system. The control strategies for improving the disadvantages and for utilizing the advantage of coupling are researched. In order to weaken the interaction effect of torque outputs in the inner motor and the outer motor that results from coupling in STPM-DMPM, a decoupling control method based on equivalent current control is proposed, and independent torque control for the inner motor and outer motor is achieved. In order to solve address the problem of adequately utilization of coupling, minimizing the overall copper loss of the inner motor and the outer motor of STPM-DMPM is taken as the optimization objective for optimal control, and the purpose of utilizing the coupling adequately and reasonably is achieved. The verification tests of the proposed decoupling control and optimal control strategies are carried out on a prototype STPM-DMPM, and the experimental results show that the interaction effect of torque outputs in the inner motor and the outer motor can be markedly weakened through use of the control method. The overall copper loss of the inner motor and the outer motor can be markedly reduced through use of the optimal control method, while the power output remains unchanged. A breakthrough in the control problem of STPM-DMPM is accomplished by combining the control methods. Good performance in the control of STPM-DMPM will enhance its practicality, particularly as applied to hybrid systems.展开更多
Minister Huang Yicheng briefly reviewedat the press release held on March 14 thatafter 4 decades development since 1949,espe-cially in the recent 10 years of practising thereform and open policy,the energy industry in...Minister Huang Yicheng briefly reviewedat the press release held on March 14 thatafter 4 decades development since 1949,espe-cially in the recent 10 years of practising thereform and open policy,the energy industry inChina has been advancing by leaps and bounds.The total primary energy production by the yearof 1989 reached 1 billion tons of standard coalwhich were 43.5 times of that in the year of 1949with an annual average growth rate of 9.9%,ranking among the major energy producing statesin the world.As of the end of 1989.the output ofrun-of-mine coal amounted to 1.04 billion tons,32.5 times that of 1949 or at an average rate of9.1%.Out of which.600 million tons of miningcapability were increased during the period展开更多
Olusegun Obasanjo,former President of Nigeria:In an era of globalization,understanding and cooperation is a bridge for better relations among countries.Countries should further develop non-governmental exchanges to pr...Olusegun Obasanjo,former President of Nigeria:In an era of globalization,understanding and cooperation is a bridge for better relations among countries.Countries should further develop non-governmental exchanges to promote understanding and cooperation.This year’s Dialogue has a clear theme and a broad and global participation of foreign representatives展开更多
Considerable changes have taken place in commercial passenger air transport since the enactment of the 1978 Airline Deregulation Act in the US and the deregulation of airline networks that has occurred elsewhere. The ...Considerable changes have taken place in commercial passenger air transport since the enactment of the 1978 Airline Deregulation Act in the US and the deregulation of airline networks that has occurred elsewhere. The commercial and operational freedoms have led most of the larger carriers to develop hub-and-spoke networks, within which certain cities or metropolitan areas emerge as key nodes possessing tremendous advantages over other locations in the air transport system. This paper examines the nature of hub-and-spoke operations in air transportation services, and the benefits that accrue to a city or geographical region that is host to an airline hub. In particular, it looks into linkages between the air service hub and local economic development. Four potential types of impact of airports on the regional economy are defined and discussed. As an example, the assessment of the economic impacts of Cincinnati-Northern Kentucky International Airport (CVG), a major Delta Airlines hub, is introduced.展开更多
基金funding of the National Natural Science Foundation of China (Nos.52072156,51605198)Postdoctoral Foundation of China (2020M682269).
文摘The wheels have a considerable influence on the aerodynamic properties and can contribute up to 25%of the total drag on modern vehicles.In this study,the effect of the wheel spoke structure on the aerodynamic performance of the isolated wheel is investigated.Subsequently,the 35°Ahmed body with an optimized spoke structure is used to analyze the flow behavior and the mechanism of drag reduction.The Fluent software is employed for this investigation,with an inlet velocity of 40 m/s.The accuracy of the numerical study is validated by comparing it with experimental results obtained from the classical Ahmed model.To gain a clearer understanding of the effects of the wheel spoke parameters on the aerodynamics of both the wheel and Ahmedmodel,and five design variables are proposed:the fillet angleα,the inside arc radius R1,the outside radius R2,and the same length of the chord L1 and L2.These variables characterize the wheel spoke structure.The Optimal Latin Hypercube designmethod is utilized to conduct the experimental design.Based on the simulation results of various wheel spoke designs,the Kriging model and the adaptive simulated annealing algorithm is selected to optimize the design parameters.The objective is to achieve the best combination for maximum drag reduction.It is indicated that the optimized spoke structure resulted in amaximum drag reduction of 5.7%and 4.7%for the drag coefficient of the isolated wheel and Ahmed body,respectively.The drag reduction is primarily attributed to changes in the flow state around the wheel,which suppressed separation bubbles.Additionally,it influenced the boundary layer thickness around the car body and reduced the turbulent kinetic energy in the wake flow.These effects collectively contributed to the observed drag reduction.
文摘目的探索Hub and Spoke教学法在助产课程教学中的应用效果,并对助产学学生对其的认知和态度进行分析。方法 2018年2月至2018年12月,将46名助产本科生作为主体,完成10份教学案例的设计。采用组建Hub and Spoke训练小组、进行课前理论讲解、确定Hub and Spoke训练模式与目标、学员角色演练和自我总结、老师总结反馈的教学方法来进行授课。同时,采用自制量表以学生为主体进行Hub and Spoke教学法的效果评价,了解学生对Hub and Spoke教学法教学效果的评价。结果 56.52%的助产本科生知道也基本了解Hub and Spoke教学法。65.22%助产学生愿意使用Hub and Spoke教学法进行学习。多数助产本科生认为Hub and Spoke教学法的应用对其知识学习有不同程度的帮助。且助产本科生对Hub and Spoke教学法的自我评价得分较高。结论 Hub and Spoke教学模式可以作为很好的教学方法,能够帮助助产学学生提高临床技能应用和学习效果。
基金This work was supported by Strategic Priority Research Program of the Chinese Academy of Sciences(No.XDA03030201)the Key Laboratory of Particle Acceleration Physics and Technology Autonomous Foundation of CAS China(No.JSQ2017ZZ01).
文摘The 10-MeV Accelerator-Driven Subcritical(ADS)system Injector-I test stand at the Institute of High Energy Physics(IHEP)is a testing facility dedicated to demonstrating the feasibility of the spoke-based super-conducting(SC)linear accelerator(linac)for the ADS project in China.The injector adopted a four-vane copper structure radio frequency quadrupole(RFQ)with an output energy of 3.2 MeV and an SC section accommodating 14 β_(g)=0.12 single spoke cavities,14 SC solenoids,and 14 cold beam position monitors(BPMs).A 10-MeV pulsed beam with a beam current of 10 mA and a 2-mA continuous wave(CW)beam were successfully shooting through.The commissioning results confirmed the feasibility of using a 325-MHz spoke-type cavity for accelerating the proton beam in the low β and medium β sections.This paper describes the results achieved,the difficulties encountered,and the experiences obtained during commissioning.
基金Supported by National Hi-tech Research and Development Program of China (863 Program,Grant No.2011AA11A238)
文摘Dual mechanical port machine（DMPM）, as a novel electromechanical energy conversion device, has attracted widespread attention. DMPM with spoke type permanent magnet arrangements（STPM-DMPM）, which is one of several types of DMPM, has been of interest recently. The unique coupling characteristics of STPM-DMPM are beneficial to improving system performance, but these same characteristics increase the difficulties of control. Now there has been little research about the control of STPM-DMPM, and this has hindered its practical application. Based on a mathematical model of STPM-DMPM, the coupling characteristics and the merits and demerits of such devices are analyzed as applied to a hybrid system. The control strategies for improving the disadvantages and for utilizing the advantage of coupling are researched. In order to weaken the interaction effect of torque outputs in the inner motor and the outer motor that results from coupling in STPM-DMPM, a decoupling control method based on equivalent current control is proposed, and independent torque control for the inner motor and outer motor is achieved. In order to solve address the problem of adequately utilization of coupling, minimizing the overall copper loss of the inner motor and the outer motor of STPM-DMPM is taken as the optimization objective for optimal control, and the purpose of utilizing the coupling adequately and reasonably is achieved. The verification tests of the proposed decoupling control and optimal control strategies are carried out on a prototype STPM-DMPM, and the experimental results show that the interaction effect of torque outputs in the inner motor and the outer motor can be markedly weakened through use of the control method. The overall copper loss of the inner motor and the outer motor can be markedly reduced through use of the optimal control method, while the power output remains unchanged. A breakthrough in the control problem of STPM-DMPM is accomplished by combining the control methods. Good performance in the control of STPM-DMPM will enhance its practicality, particularly as applied to hybrid systems.
文摘Minister Huang Yicheng briefly reviewedat the press release held on March 14 thatafter 4 decades development since 1949,espe-cially in the recent 10 years of practising thereform and open policy,the energy industry inChina has been advancing by leaps and bounds.The total primary energy production by the yearof 1989 reached 1 billion tons of standard coalwhich were 43.5 times of that in the year of 1949with an annual average growth rate of 9.9%,ranking among the major energy producing statesin the world.As of the end of 1989.the output ofrun-of-mine coal amounted to 1.04 billion tons,32.5 times that of 1949 or at an average rate of9.1%.Out of which.600 million tons of miningcapability were increased during the period
文摘Olusegun Obasanjo,former President of Nigeria:In an era of globalization,understanding and cooperation is a bridge for better relations among countries.Countries should further develop non-governmental exchanges to promote understanding and cooperation.This year’s Dialogue has a clear theme and a broad and global participation of foreign representatives
基金Under the auspices of Intramural Research Incentive Grant from the Office of the Senior Vice President for Research atUniversity of Louisville
文摘Considerable changes have taken place in commercial passenger air transport since the enactment of the 1978 Airline Deregulation Act in the US and the deregulation of airline networks that has occurred elsewhere. The commercial and operational freedoms have led most of the larger carriers to develop hub-and-spoke networks, within which certain cities or metropolitan areas emerge as key nodes possessing tremendous advantages over other locations in the air transport system. This paper examines the nature of hub-and-spoke operations in air transportation services, and the benefits that accrue to a city or geographical region that is host to an airline hub. In particular, it looks into linkages between the air service hub and local economic development. Four potential types of impact of airports on the regional economy are defined and discussed. As an example, the assessment of the economic impacts of Cincinnati-Northern Kentucky International Airport (CVG), a major Delta Airlines hub, is introduced.
