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
Controlling mass transportation using intrinsic mechanisms is a challenging topic in nanotechnology.Herein,we employ molecular dynamics simulations to investigate the mass transport inside carbon nanotubes(CNT)with te...Controlling mass transportation using intrinsic mechanisms is a challenging topic in nanotechnology.Herein,we employ molecular dynamics simulations to investigate the mass transport inside carbon nanotubes(CNT)with temperature gradients,specifically the effects of adding a static carbon hoop to the outside of a CNT on the transport of a nanomotor inside the CNT.We reveal that the underlying mechanism is the uneven potential energy created by the hoops,i.e.,the hoop outside the CNT forms potential energy barriers or wells that affect mass transport inside the CNT.This fundamental control of directional mass transportation may lead to promising routes for nanoscale actuation and energy conversion.展开更多
We study the friction properties of interlayer bonded bilayer graphene by simulating the movement of a slider on the surface of bilayer graphene using molecular dynamics.The results show that the presence of the inter...We study the friction properties of interlayer bonded bilayer graphene by simulating the movement of a slider on the surface of bilayer graphene using molecular dynamics.The results show that the presence of the interlayer covalent bonds due to the local sp^(3) hybridization of carbon atoms in the bilayer graphene seriously reduces the frictional coefficient of the bilayer graphene surface to 30%,depending on the coverage of interlayer sp^(3) bonds and normal loads.For a certain coverage of interlayer sp3bonds,when the normal load of the slider reaches a certain value,the surface of this interlayer bonded bilayer graphene will lose the friction reduction effect on the slider.Our findings provide guidance for the regulation and manipulation of the frictional properties of bilayer graphene surfaces through interlayer covalent bonds,which may be useful for applications of friction related graphene based nanodevices.展开更多
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。
基金Project supported by the Doctoral Fund of Yanshan University (Grant No.B919)the Program of Independent Research for Young Teachers of Yanshan University (Grant No.020000534)the S&T Program of Hebei Province of China (Grant No.QN2016123)。
文摘Controlling mass transportation using intrinsic mechanisms is a challenging topic in nanotechnology.Herein,we employ molecular dynamics simulations to investigate the mass transport inside carbon nanotubes(CNT)with temperature gradients,specifically the effects of adding a static carbon hoop to the outside of a CNT on the transport of a nanomotor inside the CNT.We reveal that the underlying mechanism is the uneven potential energy created by the hoops,i.e.,the hoop outside the CNT forms potential energy barriers or wells that affect mass transport inside the CNT.This fundamental control of directional mass transportation may lead to promising routes for nanoscale actuation and energy conversion.
基金supported by the Doctor Fund and the Program of independent Research for Young Teachers of Yanshan University (Grant Nos.B919 and 020000534)。
文摘We study the friction properties of interlayer bonded bilayer graphene by simulating the movement of a slider on the surface of bilayer graphene using molecular dynamics.The results show that the presence of the interlayer covalent bonds due to the local sp^(3) hybridization of carbon atoms in the bilayer graphene seriously reduces the frictional coefficient of the bilayer graphene surface to 30%,depending on the coverage of interlayer sp^(3) bonds and normal loads.For a certain coverage of interlayer sp3bonds,when the normal load of the slider reaches a certain value,the surface of this interlayer bonded bilayer graphene will lose the friction reduction effect on the slider.Our findings provide guidance for the regulation and manipulation of the frictional properties of bilayer graphene surfaces through interlayer covalent bonds,which may be useful for applications of friction related graphene based nanodevices.
