The effect of drive laser wavelength on the growth of ablative Rayleigh–Taylor instability(ARTI)in inertial confinemen fusion(ICF)is studied with two-dimensional numerical simulations.The results show that in the pla...The effect of drive laser wavelength on the growth of ablative Rayleigh–Taylor instability(ARTI)in inertial confinemen fusion(ICF)is studied with two-dimensional numerical simulations.The results show that in the plasma acceleration phase,shorter wavelengths lead to more efficien coupling between the laser and the kinetic energy of the implosion fluid Under the condition that the laser energy coupled to the implosion flui is constant,the ARTI growth rate decreases as the laser wavelength moves toward the extreme ultraviolet band,reaching its minimum value near λ=65 nm,and when the laser wavelength continuously moves toward the X-ray band,the ARTI growth rate increases rapidly.It is found that the results deviate from the theoretical ARTI growth rate.As the laser intensity benchmark increases,the position of the minimum ARTI growth rate shifts toward shorter wavelengths.As the initial sinusoidal perturbation wavenumber decreases,the position of the minimum ARTI growth rate shifts toward longer wavelengths.We believe that the conclusions drawn from the present simulations and analysis will help provide a better understanding of the ICF process and improve the theory of ARTI growth.展开更多
利用反向Taylor杆撞击实验和数值模拟方法研究了30CrMnSiNi2A钢在高应变率冲击下的动态特性。首先,在Taylor杆冲击实验的基础上,采用Johnson-Cook本构模型和失效模型,对30CrMnSiNi2A钢的反向Taylor杆撞击进行了数值模拟,并将数值模拟结...利用反向Taylor杆撞击实验和数值模拟方法研究了30CrMnSiNi2A钢在高应变率冲击下的动态特性。首先,在Taylor杆冲击实验的基础上,采用Johnson-Cook本构模型和失效模型,对30CrMnSiNi2A钢的反向Taylor杆撞击进行了数值模拟,并将数值模拟结果与实验得到的杆件自由面速度曲线进行对比验证,两者吻合良好。然后,研究了不同长径比的30CrMnSiNi2A钢杆件对反向Taylor杆撞击实验中任意反射面激光干涉测速技术(velocity interferometer system for any reflector,VISAR)测试结果的影响,得到了适用于VISAR测试的Taylor杆长径比范围。最后,运用应力三轴度及损伤度分析了Taylor杆的断裂破坏机理和变形模式,得到了镦粗、蘑菇状变形、花瓣状开裂3种变形模式,并分析了杆件断裂破坏的原因。结果表明:Taylor杆撞击端中心破坏是由于材料受压引起,而撞击端边缘开裂是由于材料处于拉伸状态造成的,且断裂先从边缘开始。展开更多
Taylor Swift是美国著名创作歌手,擅长在歌词中运用隐喻,尤其在表达爱情主题时。爱情隐喻是认知语言学的重要研究课题。文章在认知语言学视域下以文本细读的方法考察Taylor Swift 11张录音室专辑(共194首歌曲)中的爱情隐喻,发现它们的...Taylor Swift是美国著名创作歌手,擅长在歌词中运用隐喻,尤其在表达爱情主题时。爱情隐喻是认知语言学的重要研究课题。文章在认知语言学视域下以文本细读的方法考察Taylor Swift 11张录音室专辑(共194首歌曲)中的爱情隐喻,发现它们的数量、频率逐年递增、源域类型不断拓展,反映了Taylor对爱情理解的不断深入和多元化。文章重点分析了“爱是战争/斗”“爱是旅程”“爱/恨是火”以及“爱是幽灵”等高频出现的爱情隐喻,相关研究发现可为英语学习者提供参考,也为我国的歌曲创作者提供了借鉴。展开更多
A composite anti-disturbance predictive control strategy employing a Multi-dimensional Taylor Network(MTN)is presented for unmanned systems subject to time-delay and multi-source disturbances.First,the multi-source di...A composite anti-disturbance predictive control strategy employing a Multi-dimensional Taylor Network(MTN)is presented for unmanned systems subject to time-delay and multi-source disturbances.First,the multi-source disturbances are addressed according to their specific characteristics as follows:(A)an MTN data-driven model,which is used for uncertainty description,is designed accompanied with the mechanism model to represent the unmanned systems;(B)an adaptive MTN filter is used to remove the influence of the internal disturbance;(C)an MTN disturbance observer is constructed to estimate and compensate for the influence of the external disturbance;(D)the Extended Kalman Filter(EKF)algorithm is utilized as the learning mechanism for MTNs.Second,to address the time-delay effect,a recursiveτstep-ahead MTN predictive model is designed utilizing recursive technology,aiming to mitigate the impact of time-delay,and the EKF algorithm is employed as its learning mechanism.Then,the MTN predictive control law is designed based on the quadratic performance index.By implementing the proposed composite controller to unmanned systems,simultaneous feedforward compensation and feedback suppression to the multi-source disturbances are conducted.Finally,the convergence of the MTN and the stability of the closed-loop system are established utilizing the Lyapunov theorem.Two exemplary applications of unmanned systems involving unmanned vehicle and rigid spacecraft are presented to validate the effectiveness of the proposed approach.展开更多
In this study,we numerically investigate the rise of a Taylor bubble in a vertically oscillating round tube.The results show that increasing the oscillation frequency and amplitude reduces the bubble rise velocity,whi...In this study,we numerically investigate the rise of a Taylor bubble in a vertically oscillating round tube.The results show that increasing the oscillation frequency and amplitude reduces the bubble rise velocity,which is consistent with previously reported experimental findings.Analysis of the flow in the annular film region indicates that the influence of tube wall oscillations is minimal.This suggests that the effect of tube oscillations is essentially equivalent to that of an oscillating piston above the bubble,leading to a similar mechanism for bubble deceleration.Using a theoretical formula from the literature,we demonstrate that at sufficiently high frequencies,the amplitude of the tube velocity oscillations becomes the sole control parameter affecting bubble deceleration.This study enhances our understanding of Taylor bubble behavior in mechanically oscillating environments and provides useful insights into the design of control strategies for Taylor bubble motion in vertical slug flows.展开更多
基金supported by the National Natural Science Foundation of China(NSFC)(Grant Nos.12074399,12204500,and 12004403)the Key Projects of the Intergovernmental International Scientifi and Technological Innovation Cooperation(Grant No.2021YFE0116700)+1 种基金the Shanghai Natural Science Foundation(Grant No.20ZR1464400)the Shanghai Sailing Program(Grant No.22YF1455300)。
文摘The effect of drive laser wavelength on the growth of ablative Rayleigh–Taylor instability(ARTI)in inertial confinemen fusion(ICF)is studied with two-dimensional numerical simulations.The results show that in the plasma acceleration phase,shorter wavelengths lead to more efficien coupling between the laser and the kinetic energy of the implosion fluid Under the condition that the laser energy coupled to the implosion flui is constant,the ARTI growth rate decreases as the laser wavelength moves toward the extreme ultraviolet band,reaching its minimum value near λ=65 nm,and when the laser wavelength continuously moves toward the X-ray band,the ARTI growth rate increases rapidly.It is found that the results deviate from the theoretical ARTI growth rate.As the laser intensity benchmark increases,the position of the minimum ARTI growth rate shifts toward shorter wavelengths.As the initial sinusoidal perturbation wavenumber decreases,the position of the minimum ARTI growth rate shifts toward longer wavelengths.We believe that the conclusions drawn from the present simulations and analysis will help provide a better understanding of the ICF process and improve the theory of ARTI growth.
文摘利用反向Taylor杆撞击实验和数值模拟方法研究了30CrMnSiNi2A钢在高应变率冲击下的动态特性。首先,在Taylor杆冲击实验的基础上,采用Johnson-Cook本构模型和失效模型,对30CrMnSiNi2A钢的反向Taylor杆撞击进行了数值模拟,并将数值模拟结果与实验得到的杆件自由面速度曲线进行对比验证,两者吻合良好。然后,研究了不同长径比的30CrMnSiNi2A钢杆件对反向Taylor杆撞击实验中任意反射面激光干涉测速技术(velocity interferometer system for any reflector,VISAR)测试结果的影响,得到了适用于VISAR测试的Taylor杆长径比范围。最后,运用应力三轴度及损伤度分析了Taylor杆的断裂破坏机理和变形模式,得到了镦粗、蘑菇状变形、花瓣状开裂3种变形模式,并分析了杆件断裂破坏的原因。结果表明:Taylor杆撞击端中心破坏是由于材料受压引起,而撞击端边缘开裂是由于材料处于拉伸状态造成的,且断裂先从边缘开始。
文摘Taylor Swift是美国著名创作歌手,擅长在歌词中运用隐喻,尤其在表达爱情主题时。爱情隐喻是认知语言学的重要研究课题。文章在认知语言学视域下以文本细读的方法考察Taylor Swift 11张录音室专辑(共194首歌曲)中的爱情隐喻,发现它们的数量、频率逐年递增、源域类型不断拓展,反映了Taylor对爱情理解的不断深入和多元化。文章重点分析了“爱是战争/斗”“爱是旅程”“爱/恨是火”以及“爱是幽灵”等高频出现的爱情隐喻,相关研究发现可为英语学习者提供参考,也为我国的歌曲创作者提供了借鉴。
基金co-supported by the National Key R&D Program of China(No.2023YFB4704400)the Zhejiang Provincial Natural Science Foundation of China(No.LQ24F030012)the National Natural Science Foundation of China General Project(No.62373033)。
文摘A composite anti-disturbance predictive control strategy employing a Multi-dimensional Taylor Network(MTN)is presented for unmanned systems subject to time-delay and multi-source disturbances.First,the multi-source disturbances are addressed according to their specific characteristics as follows:(A)an MTN data-driven model,which is used for uncertainty description,is designed accompanied with the mechanism model to represent the unmanned systems;(B)an adaptive MTN filter is used to remove the influence of the internal disturbance;(C)an MTN disturbance observer is constructed to estimate and compensate for the influence of the external disturbance;(D)the Extended Kalman Filter(EKF)algorithm is utilized as the learning mechanism for MTNs.Second,to address the time-delay effect,a recursiveτstep-ahead MTN predictive model is designed utilizing recursive technology,aiming to mitigate the impact of time-delay,and the EKF algorithm is employed as its learning mechanism.Then,the MTN predictive control law is designed based on the quadratic performance index.By implementing the proposed composite controller to unmanned systems,simultaneous feedforward compensation and feedback suppression to the multi-source disturbances are conducted.Finally,the convergence of the MTN and the stability of the closed-loop system are established utilizing the Lyapunov theorem.Two exemplary applications of unmanned systems involving unmanned vehicle and rigid spacecraft are presented to validate the effectiveness of the proposed approach.
基金supported by the National Natural Science Foundation of China(Grant No.12202441).
文摘In this study,we numerically investigate the rise of a Taylor bubble in a vertically oscillating round tube.The results show that increasing the oscillation frequency and amplitude reduces the bubble rise velocity,which is consistent with previously reported experimental findings.Analysis of the flow in the annular film region indicates that the influence of tube wall oscillations is minimal.This suggests that the effect of tube oscillations is essentially equivalent to that of an oscillating piston above the bubble,leading to a similar mechanism for bubble deceleration.Using a theoretical formula from the literature,we demonstrate that at sufficiently high frequencies,the amplitude of the tube velocity oscillations becomes the sole control parameter affecting bubble deceleration.This study enhances our understanding of Taylor bubble behavior in mechanically oscillating environments and provides useful insights into the design of control strategies for Taylor bubble motion in vertical slug flows.
