From relativistic linear Vlasov-Maxwell equations,the expressions of the startingcurrent and frequency deviation of a electrostatic gyromonotron with a field distribution sin k‖zare derived and the numerical calculat...From relativistic linear Vlasov-Maxwell equations,the expressions of the startingcurrent and frequency deviation of a electrostatic gyromonotron with a field distribution sin k‖zare derived and the numerical calculation is carried out.展开更多
The unsteady magnehydrodynamics （MHD） Couette flow of an electrically conducting fluid in a rotating system is investigated by taking the Hall and ion-slip currents into consideration. The derived fundamental equati...The unsteady magnehydrodynamics （MHD） Couette flow of an electrically conducting fluid in a rotating system is investigated by taking the Hall and ion-slip currents into consideration. The derived fundamental equations on the assumption of a small magnetic Reynolds number are solved analytically with the well-known Laplace transform technique. The unified closed-form expressions axe obtained for the velocity and the skin friction in the two different cases of the magnetic field being fixed to either the fluid or the moving plate. The effects of various parameters on the velocity and the skin friction axe discussed by graphs. The results reveal that the primary and secondary velocities increase with the Hall current. An increase in the ion-slip paxameter also leads to an increase in the primary velocity but a decrease in the secondary velocity. It is also shown that the combined effect of the rotation, Hall, and ion-slip parameters determines the contribution of the secondary motion in the fluid flow.展开更多
The unsteady MHD Couette flow of an incompressible viscous electrically conducting fluid between two infinite non- conducting horizontal porous plates under the boundary layer approximations has been studied with the ...The unsteady MHD Couette flow of an incompressible viscous electrically conducting fluid between two infinite non- conducting horizontal porous plates under the boundary layer approximations has been studied with the consideration of both Hall currents and ion-slip. An analytical solution of the governing equations describing the flow is obtained by the Laplace transform method. It is seen that the primary velocity decreases while the magnitude of secondary velocity increases with increase in Hall parameter. It is also seen that both the primary velocity and the magnitude of secondary velocity decrease with increase in ion-slip parameter. It is observed that a thin boundary layer is formed near the stationary plate for large values of squared Hartmann number and Reynolds number. The thickness of this boundary layer increases with increase in either Hall parameter or ion-slip parameter.展开更多
声学多普勒流速剖面仪(Acoustic Doppler Current Profiler,ADCP)是目前海洋、江河流速测量的最主要仪器之一。已有对于ADCP的安装偏差分析大多是针对其安装在船上后,基阵发生偏移的安装偏差。针对5个超声换能器集成为五波束Janus结构A...声学多普勒流速剖面仪(Acoustic Doppler Current Profiler,ADCP)是目前海洋、江河流速测量的最主要仪器之一。已有对于ADCP的安装偏差分析大多是针对其安装在船上后,基阵发生偏移的安装偏差。针对5个超声换能器集成为五波束Janus结构ADCP后,由于机械加工、安装工艺造成的安装偏差,提出将安装偏差分为安装位置偏差和安装角度偏差两部分进行研究。证明了在100 m探测距离内,毫米级安装位置偏差等效于10^(-3)~10^(-2)度级安装角度偏差,得出了安装角度偏差是安装偏差中最主要部分的结论。设计了基于回波延时测距搭配高精度姿态仪的安装偏差校准方法,并通过仿真分析了校准过程中不同因素对校准精度的影响,以针对不同校准精度需求选取不同的校准环境。结果表明该校准方法有一定实用价值,可以用来对超声换能器集成为五波束Janus结构后的安装偏差进行校准。展开更多
Accumulative damage during early stage of fatigue in AISI 321 steel was investigated by eddy current test, atomic force microscopy, X-ray diffraction and transmission electron microscopy. Surface slip, dislocation, an...Accumulative damage during early stage of fatigue in AISI 321 steel was investigated by eddy current test, atomic force microscopy, X-ray diffraction and transmission electron microscopy. Surface slip, dislocation, and strain-induced martensite were determined as the main damage types. Moreover, damage during the fatigue was found to be increased with the increasing fatigue cycles and load amplitude. The contribution of strain-induced martensite to the total eddy current amplitude （V） was enhanced with the increase in its volume fraction. Finally, a linear relationship between V I~, and the height of surface slip was established.展开更多
文中提出基于当前统计模型的鲁棒转换测量卡尔曼滤波算法(robust converted measurement Kalman filter based on current statistical,RCMKF_CS).通过跟踪门限分析,从理论上证明所提方法相较于HCMKF_CS更易解决量测含有闪烁噪声的水面...文中提出基于当前统计模型的鲁棒转换测量卡尔曼滤波算法(robust converted measurement Kalman filter based on current statistical,RCMKF_CS).通过跟踪门限分析,从理论上证明所提方法相较于HCMKF_CS更易解决量测含有闪烁噪声的水面机动目标跟踪问题.结果表明:在量测含有闪烁噪声时,该方法优于HCMKF_CS.并且,所提算法的计算花费少于HCMKF_CS.展开更多
文摘From relativistic linear Vlasov-Maxwell equations,the expressions of the startingcurrent and frequency deviation of a electrostatic gyromonotron with a field distribution sin k‖zare derived and the numerical calculation is carried out.
文摘The unsteady magnehydrodynamics （MHD） Couette flow of an electrically conducting fluid in a rotating system is investigated by taking the Hall and ion-slip currents into consideration. The derived fundamental equations on the assumption of a small magnetic Reynolds number are solved analytically with the well-known Laplace transform technique. The unified closed-form expressions axe obtained for the velocity and the skin friction in the two different cases of the magnetic field being fixed to either the fluid or the moving plate. The effects of various parameters on the velocity and the skin friction axe discussed by graphs. The results reveal that the primary and secondary velocities increase with the Hall current. An increase in the ion-slip paxameter also leads to an increase in the primary velocity but a decrease in the secondary velocity. It is also shown that the combined effect of the rotation, Hall, and ion-slip parameters determines the contribution of the secondary motion in the fluid flow.
文摘The unsteady MHD Couette flow of an incompressible viscous electrically conducting fluid between two infinite non- conducting horizontal porous plates under the boundary layer approximations has been studied with the consideration of both Hall currents and ion-slip. An analytical solution of the governing equations describing the flow is obtained by the Laplace transform method. It is seen that the primary velocity decreases while the magnitude of secondary velocity increases with increase in Hall parameter. It is also seen that both the primary velocity and the magnitude of secondary velocity decrease with increase in ion-slip parameter. It is observed that a thin boundary layer is formed near the stationary plate for large values of squared Hartmann number and Reynolds number. The thickness of this boundary layer increases with increase in either Hall parameter or ion-slip parameter.
文摘声学多普勒流速剖面仪(Acoustic Doppler Current Profiler,ADCP)是目前海洋、江河流速测量的最主要仪器之一。已有对于ADCP的安装偏差分析大多是针对其安装在船上后,基阵发生偏移的安装偏差。针对5个超声换能器集成为五波束Janus结构ADCP后,由于机械加工、安装工艺造成的安装偏差,提出将安装偏差分为安装位置偏差和安装角度偏差两部分进行研究。证明了在100 m探测距离内,毫米级安装位置偏差等效于10^(-3)~10^(-2)度级安装角度偏差,得出了安装角度偏差是安装偏差中最主要部分的结论。设计了基于回波延时测距搭配高精度姿态仪的安装偏差校准方法,并通过仿真分析了校准过程中不同因素对校准精度的影响,以针对不同校准精度需求选取不同的校准环境。结果表明该校准方法有一定实用价值,可以用来对超声换能器集成为五波束Janus结构后的安装偏差进行校准。
文摘Accumulative damage during early stage of fatigue in AISI 321 steel was investigated by eddy current test, atomic force microscopy, X-ray diffraction and transmission electron microscopy. Surface slip, dislocation, and strain-induced martensite were determined as the main damage types. Moreover, damage during the fatigue was found to be increased with the increasing fatigue cycles and load amplitude. The contribution of strain-induced martensite to the total eddy current amplitude （V） was enhanced with the increase in its volume fraction. Finally, a linear relationship between V I~, and the height of surface slip was established.
文摘文中提出基于当前统计模型的鲁棒转换测量卡尔曼滤波算法(robust converted measurement Kalman filter based on current statistical,RCMKF_CS).通过跟踪门限分析,从理论上证明所提方法相较于HCMKF_CS更易解决量测含有闪烁噪声的水面机动目标跟踪问题.结果表明:在量测含有闪烁噪声时,该方法优于HCMKF_CS.并且,所提算法的计算花费少于HCMKF_CS.
