Incorporating asymmetric quadratic and cubic stiffnesses into a time-delayed Duffing oscillator provides a more accurate representation of practical systems,where the resulting nonlinearities critically influence subh...Incorporating asymmetric quadratic and cubic stiffnesses into a time-delayed Duffing oscillator provides a more accurate representation of practical systems,where the resulting nonlinearities critically influence subharmonic resonance phenomena,yet comprehensive investigations remain limited.This study employs the generalized harmonic balance(HB)method to conduct an analytical investigation of the subharmonic resonance behavior in asymmetric stiffness nonlinear systems with time delay.To further examine the switching behavior between primary and subharmonic resonances,a numerical continuation approach combining the shooting method and the parameter continuation algorithm is developed.The analytical and numerical continuation solutions are validated through direct numerical integration.Subsequently,the switching behavior and associated bifurcation points are analyzed by means of the numerical continuation results in conjunction with the Floquet theory.Finally,the effects of delay parameters on the existence range of subharmonic responses are discussed in detail,and the influence of initial conditions on system dynamics is explored with basin of attraction plots.This work establishes a comprehensive framework for the analytical and numerical study on time-delayed nonlinear systems with asymmetric stiffness,providing valuable theoretical insights into the stability management of such dynamic systems.展开更多
圆筒型浮式生产储卸油装置(Floating Production Storage and Offloading,FPSO)垂荡运动较大,易引发摇摆运动失稳,影响油气生产安全。针对圆筒型FPSO垂荡与纵摇间的强耦合关系,建立两自由度非线性耦合运动方程,基于摄动法推导方程的近...圆筒型浮式生产储卸油装置(Floating Production Storage and Offloading,FPSO)垂荡运动较大,易引发摇摆运动失稳,影响油气生产安全。针对圆筒型FPSO垂荡与纵摇间的强耦合关系,建立两自由度非线性耦合运动方程,基于摄动法推导方程的近似解析解,研究涌浪作用下圆筒型FPSO垂荡-纵摇耦合运动响应及稳定性。结果表明:当涌浪周期远离圆筒型FPSO垂荡固有周期时,圆筒型FPSO具有良好的运动稳定性;在垂荡与纵摇固有周期接近1∶2关系的情况下,同时当长周期涌浪频率接近圆筒型FPSO垂荡固有频率时,圆筒型FPSO的垂荡和纵摇由线性强迫运动转变为1/2亚谐运动,垂荡位移幅值与波浪幅值呈非线性关系,纵摇出现较大运动响应;当圆筒型FPSO发生内共振运动时,增加垂荡阻尼可消耗垂荡共振时的能量,降低垂荡运动幅值,增加纵摇阻尼可降低纵摇运动幅值,但同时会增大引起垂荡能量向纵摇渗透所需的最小垂荡运动幅值,使波浪能量集中于垂荡模态,导致垂荡运动幅值增大。展开更多
基于电子科技大学与中国电子科技集团第十三研究所自主联合设计的肖特基二极管研制宽带360~440 GHz分谐波混频器。详细描述二极管建模,以模拟在极高频复杂电磁环境中由于二极管结构引入的相关寄生效应.在软件HFSS与ADS中,通过场与路结...基于电子科技大学与中国电子科技集团第十三研究所自主联合设计的肖特基二极管研制宽带360~440 GHz分谐波混频器。详细描述二极管建模,以模拟在极高频复杂电磁环境中由于二极管结构引入的相关寄生效应.在软件HFSS与ADS中,通过场与路结合的方法对分谐波混频器进行优化.实测结果显示在本振信号为210 GHz本振功率6 d Bm的驱动下,在406 GHz可得到最小变频损耗9.99 d B,在380~430 GHz范围内,变频损耗小于15 d B,在360~440 GHz范围内,变频损耗小于19 d B.展开更多
基金Project supported by the National Natural Science Foundation of China(Nos.U24B2062,520754285247051087)+1 种基金the Two-chain Fusion High-end Machine Tool Project of Shaanxi Province of China(No.2021LLRh-01-02)the Youth Fund of the National Natural Science Foundation of China(No.52205281)。
文摘Incorporating asymmetric quadratic and cubic stiffnesses into a time-delayed Duffing oscillator provides a more accurate representation of practical systems,where the resulting nonlinearities critically influence subharmonic resonance phenomena,yet comprehensive investigations remain limited.This study employs the generalized harmonic balance(HB)method to conduct an analytical investigation of the subharmonic resonance behavior in asymmetric stiffness nonlinear systems with time delay.To further examine the switching behavior between primary and subharmonic resonances,a numerical continuation approach combining the shooting method and the parameter continuation algorithm is developed.The analytical and numerical continuation solutions are validated through direct numerical integration.Subsequently,the switching behavior and associated bifurcation points are analyzed by means of the numerical continuation results in conjunction with the Floquet theory.Finally,the effects of delay parameters on the existence range of subharmonic responses are discussed in detail,and the influence of initial conditions on system dynamics is explored with basin of attraction plots.This work establishes a comprehensive framework for the analytical and numerical study on time-delayed nonlinear systems with asymmetric stiffness,providing valuable theoretical insights into the stability management of such dynamic systems.
文摘圆筒型浮式生产储卸油装置(Floating Production Storage and Offloading,FPSO)垂荡运动较大,易引发摇摆运动失稳,影响油气生产安全。针对圆筒型FPSO垂荡与纵摇间的强耦合关系,建立两自由度非线性耦合运动方程,基于摄动法推导方程的近似解析解,研究涌浪作用下圆筒型FPSO垂荡-纵摇耦合运动响应及稳定性。结果表明:当涌浪周期远离圆筒型FPSO垂荡固有周期时,圆筒型FPSO具有良好的运动稳定性;在垂荡与纵摇固有周期接近1∶2关系的情况下,同时当长周期涌浪频率接近圆筒型FPSO垂荡固有频率时,圆筒型FPSO的垂荡和纵摇由线性强迫运动转变为1/2亚谐运动,垂荡位移幅值与波浪幅值呈非线性关系,纵摇出现较大运动响应;当圆筒型FPSO发生内共振运动时,增加垂荡阻尼可消耗垂荡共振时的能量,降低垂荡运动幅值,增加纵摇阻尼可降低纵摇运动幅值,但同时会增大引起垂荡能量向纵摇渗透所需的最小垂荡运动幅值,使波浪能量集中于垂荡模态,导致垂荡运动幅值增大。
文摘基于电子科技大学与中国电子科技集团第十三研究所自主联合设计的肖特基二极管研制宽带360~440 GHz分谐波混频器。详细描述二极管建模,以模拟在极高频复杂电磁环境中由于二极管结构引入的相关寄生效应.在软件HFSS与ADS中,通过场与路结合的方法对分谐波混频器进行优化.实测结果显示在本振信号为210 GHz本振功率6 d Bm的驱动下,在406 GHz可得到最小变频损耗9.99 d B,在380~430 GHz范围内,变频损耗小于15 d B,在360~440 GHz范围内,变频损耗小于19 d B.
