Application of Cooperative Learning and Flipped Classrooms in University Basketball Courses in China

This study investigates the application of the teaching model combining cooperative learning and flipped classrooms in university basketball courses in China.By analyzing the advantages and disadvantages of the traditional basketball teaching model and students’satisfaction with the course,the necessity of implementing cooperative learning and flipped classrooms is proposed.The study planned in detail the implementation strategies before class,in the classroom,and after class,and compared them with the control group through an experimental design.The experimental results showed that the new teaching mode demonstrated significant advantages in terms of learning outcomes,student satisfaction,and teacher evaluation.This study provides a valuable reference for the future reform of the physical education curriculum.

Godunov-type solutions for gas-liquid two-phase transient flows with gas release effects

The gas-liquid two-phase homogenous flow has been extensively investigated without the effect of gas release.However,the dissolved gas will release when internal water pressure drops below saturation pressure during hydraulic transients.This results in inaccuracy or even invalidity of the existing model for homogenous flows,especially for the reproduction of two-phase mass transfer processes.To address this problem,this paper couples the gas release model with conservation equations of homogenous flows,which are numerically solved by the second-order Godunov-type scheme(GTS).Specifically,a virtual-cell method is adopted at system boundaries to achieve the same second-order accuracy as interior cells,which is realized by the monotonic upwind scheme for conservation laws(MUSCL-Hancock scheme).Simulated pressure curves by the proposed model are compared with a series of analytical,numerical and experimental results.It indicates that the proposed model with gas release effects reproduces actual pressure responses most accurately,with minimum relative error and root mean squared error compared with experimental data.Moreover,the gas release leads to dynamic synchronous fluctuations of void fraction,wave speed and pressure head,including the opposite trends of void fraction and pressure,and higher void fraction leading to greater wave speed depression.Furthermore,sensitivity analysis is concluded with recommended Courant number,and different gas release effects in different initial void fractions.Present research increases the basic understanding of two-phase mass transfer processes and their implications for hydraulic transients.

Effect of Cooling Rates in Coiling Process on Microstructures and Mechanical Properties in Al-Bearing Hot-Rolled TRIP Steel

In this study, the effect of cooling rates on microstructures and mechanical properties in a Al-bearing hot-rolled transformation- induced plasticity steel was investigated. The experiments were carried out using hot simulation machine and hot rolling mill, where the samples were cooled at different cooling rates. The results showed that with the increase in cooling rates, film-like retained austenite gradually disappeared and only blocky retained austenite was retained at higher cooling rates. The volume fraction of retained austenite was 9-11% at cooling rates of 0.05-1 ℃/s and 4-6% at cooling rates of 5-10 ℃/s. In addition, martensite/austenite island was observed because of the heterogeneous carbon distribution. The samples cooled at 0.05℃/s and 0.5 ℃/s exhibited excellent mechanical properties, with tensile strengths of 712 MPa and 726 MPa, total elongations of 42% and 36% and strength and ductility balances of 29.91 GPa% and 26.15 GPa%, respectively. During plastic deformation, the instantaneous work hardening exponent of the sample cooled at 0.05 ℃/s increased continuously until it reached the maximum value, while the instantaneous work hardening exponent of the sample cooled at 0.5℃/s remained stable.

Effect of deformation parameters in unrecrystallization range on microstructural characteristics in Al-bearing hot-rolled TRIP steel

The scanning electron microscope,transmission electron microscope,optical microscope,X-ray diffraction and hardness tests were used to investigate the effect of deformation parameters in unrecrystallization range on microstructural characteristics in Al-bearing hot-rolled transformation-induced plasticity steel.The thermomechanical-controlled processing was carried out with thermomechanical simulation machine,and the samples were compressed to compression strains of 0,0.15,0.25 and 0.35 at compression temperatures of 850,900 and 950°C.The results showed that the volume fraction of polygonal ferrite increased with the increasing compression strain,while the volume fraction of retained austenite reached the maximum value at compression strain of 0.25.The volume fraction of polygonal ferrite decreased with the increasing compression temperature,whereas the volume fraction of retained austenite possessed the maximum value at compression temperature of 850°C.Some granular retained austenite was present in uncompressed samples,and some pearlite appeared at large compression strain,while the hardness of the samples exhibited the similar variation tendency to the volume fraction of retained austenite.

Design of equipment interlocking control system for LEAF

Background LEAF is a heavy ion experimental facility with low energy,high intensity and high charge state.It belongs to the strong current linear accelerator,and its maximum beam power can reach 10 kW.High-power beams can pose a great risk of damaging field devices in continuous beam mode due to high-power beam bombardment.In order to ensure the safe operation of field devices and key equipment,an interlocking control system for LEAF is designed by using the control board of FPGA and PLC controller.Methods The FPGA-based interlock system mainly implements the real-time monitoring of the arc fault signals from the RFQ cavity,a few fast fault signals from LLRF system and beam diagnostic system.When a valid fault signal is detected,the system will send its protection instruction to the chopper power supply to cut off the beam rapidly.The PLC-based interlock system mainly handles the fault state detection and safety operation of field devices with a slower protective action,and the action time is in a millisecond range.Results The protective action time of the FPGA interlock system has been achieved within 10μs.This system adopts two sets of control and protection logic,which are implemented in the control board of FPGA and the PLC controller.It can ensure the safety of the core devices through the double-redundant beam-cutting actions if the key equipment fails or the beam parameters are abnormal.Conclusion The complete system has a simple structure.The redundant technique is used in the design of the control protection logic and data transmission path.This provides a reliable safety measure for beam commissioning and physical experiment of the LEAF facility.

Design of LEAF control system

Background LEAF is a complicated and integrated facility,which includes several different subsystems.In order to realize the remote control of field equipment and meet the requirements of the beam commissioning,a LEAF control system has been designed.The developed control system includes the following sub-systems:timing systems,data archiving systems,personnel safety systems,and machine protection systems.Methods The control system for LEAF is developed using the EPICS software toolset and the distributed control architec-ture.This is designed in a three-layer structure.At the equipment layer,the control of the low-level equipment is mainly done by various industrial controllers,including programmable logic controllers,controllers for serial devices,and motion controllers based on EtherCAT fieldbus.At the middle layer,the Ethernet switches are used to implement a Gigabit local area network.At the operation layer,high-level application software has been developed for the beam commissioning and the operation of the accelerator.Results The designed system can realize remote monitoring and control of field devices,provide synchronous timing and machine protection for key equipment,and automatically archive historical data for on-site running equipment.Conclusion The complete system has a clear structure and stable operation and has been successfully applied to beam commissioning and operation of the LEAF facility.

Control system design for ion source of HIMM

Background The control system for ion source is based on distributed architecture.The hardware structure,working principle,interlock design and graphics interface design are introduced and stated in this paper.Purpose To improve the accuracy and usability of the electron cyclotron resonance ion source with advanced design for HIMM.Methods The data acquisition system is based on PLC and FPGA integrated circuit.Interlock protection is designed for vacuum system,power supplies system and cooling water system.Results The control system is tested with C5+ion beam,where fast reaction time and high-precision data processing during beam tuning have verified the stability and maintainability of the control system.Conclusion The latest results and the reliable long-term operation of the accelerator demonstrate that the performance has been continually improved with the development of the optimized control system.