A frequency domain analysis method based on the three-dimensional translating-pulsating （3DTP） source Green function is developed to investigate wave loads and free motions of two ships advancing on parallel course ...A frequency domain analysis method based on the three-dimensional translating-pulsating （3DTP） source Green function is developed to investigate wave loads and free motions of two ships advancing on parallel course in waves. Two experiments are carried out respectively to mea- sure the wave loads and the free motions for a pair of side-by- side arranged ship models advancing with an identical speed in head regular waves. For comparison, each model is also tested alone. Predictions obtained by the present solution are found in favorable agreement with the model tests and are more accurate than the traditional method based on the three dimensional pulsating （3DP） source Green function. Numer- ical resonances and peak shift can be found in the 3DP pre- dictions, which result from the wave energy trapped in the gap between two ships and the extremely inhomogeneous wave load distribution on each hull. However, they can be eliminated by 3DTP, in which the speed affects the free sur- face and most of the wave energy can be escaped from the gap. Both the experiment and the present prediction show that hydrodynamic interaction effects on wave loads and free motions are significant. The present solver may serve as a validated tool to predict wave loads and motions of two ves- sels under replenishment at sea, and may help to evaluate the hydrodynamic interaction effects on the ships safety in replenishment operation.展开更多
A cryogenic permanent magnet undulator prototype designed for Chinese High Energy Photon Source Test Facility(HEPSTF)at Institute of High Energy Physics is constructed and now commissioning.Motion precision of girders...A cryogenic permanent magnet undulator prototype designed for Chinese High Energy Photon Source Test Facility(HEPSTF)at Institute of High Energy Physics is constructed and now commissioning.Motion precision of girders is a significant parameter to guarantee gap error so as to avoid phase error and radiation intensity loss.In order to study and minimize girder parallelism errors,RADIA and SPECTRA are used to calculate qualified motion precision.Spring Modules and single motor closed-loop feedback are designed to compensate the errors.Magnetic field is finally tuned to reach specifications.Details of the study and analysis will be presented in this paper.展开更多
Purpose High Energy Photon Source(HEPS)has the characteristics of high energy and low emittance,which requires that the 1st natural frequency of the magnet support assembly should be better than 54 Hz and the moving r...Purpose High Energy Photon Source(HEPS)has the characteristics of high energy and low emittance,which requires that the 1st natural frequency of the magnet support assembly should be better than 54 Hz and the moving resolution of girder should be less than 5μm.The prototypes have been designed and fabricated to meet the requirements.Methods In the design process of the support system model,double-wedge adjusting mechanism and concrete plinth construction are adopted to meet the requirements of adjusting resolution and stability.The FEA and the dynamic stiffness testing technique are used to verify the rationality of the design model.The stability and motion performance tests are performed to verify that the prototype meets the design requirements.Results Experimental results showthat,in all cases,the lowest first-order natural frequency of the support system is 55Hz,the amplification between magnet and ground is less than 1.05 in the directions perpendicular to the beam,the moving resolution can reach 1μm,and the girder can be locked in place with an error of less than 5μm.Conclusion The prototype of HEPS support system meets the requirements of stability and motion performance.The girder body and wedge mechanism made with iron or steel have little influence on the stability of the support system.The accuracy of dynamic stiffness test and finite element simulation results is verified.Further test will be performed in the HEPS site to verify the performance.展开更多
基金supported by the National Natural Science Foundation of China(50879090)the Key Research Program of Hydrodynamics of China(9140A14030712JB11044)
文摘A frequency domain analysis method based on the three-dimensional translating-pulsating （3DTP） source Green function is developed to investigate wave loads and free motions of two ships advancing on parallel course in waves. Two experiments are carried out respectively to mea- sure the wave loads and the free motions for a pair of side-by- side arranged ship models advancing with an identical speed in head regular waves. For comparison, each model is also tested alone. Predictions obtained by the present solution are found in favorable agreement with the model tests and are more accurate than the traditional method based on the three dimensional pulsating （3DP） source Green function. Numer- ical resonances and peak shift can be found in the 3DP pre- dictions, which result from the wave energy trapped in the gap between two ships and the extremely inhomogeneous wave load distribution on each hull. However, they can be eliminated by 3DTP, in which the speed affects the free sur- face and most of the wave energy can be escaped from the gap. Both the experiment and the present prediction show that hydrodynamic interaction effects on wave loads and free motions are significant. The present solver may serve as a validated tool to predict wave loads and motions of two ves- sels under replenishment at sea, and may help to evaluate the hydrodynamic interaction effects on the ships safety in replenishment operation.
文摘A cryogenic permanent magnet undulator prototype designed for Chinese High Energy Photon Source Test Facility(HEPSTF)at Institute of High Energy Physics is constructed and now commissioning.Motion precision of girders is a significant parameter to guarantee gap error so as to avoid phase error and radiation intensity loss.In order to study and minimize girder parallelism errors,RADIA and SPECTRA are used to calculate qualified motion precision.Spring Modules and single motor closed-loop feedback are designed to compensate the errors.Magnetic field is finally tuned to reach specifications.Details of the study and analysis will be presented in this paper.
文摘Purpose High Energy Photon Source(HEPS)has the characteristics of high energy and low emittance,which requires that the 1st natural frequency of the magnet support assembly should be better than 54 Hz and the moving resolution of girder should be less than 5μm.The prototypes have been designed and fabricated to meet the requirements.Methods In the design process of the support system model,double-wedge adjusting mechanism and concrete plinth construction are adopted to meet the requirements of adjusting resolution and stability.The FEA and the dynamic stiffness testing technique are used to verify the rationality of the design model.The stability and motion performance tests are performed to verify that the prototype meets the design requirements.Results Experimental results showthat,in all cases,the lowest first-order natural frequency of the support system is 55Hz,the amplification between magnet and ground is less than 1.05 in the directions perpendicular to the beam,the moving resolution can reach 1μm,and the girder can be locked in place with an error of less than 5μm.Conclusion The prototype of HEPS support system meets the requirements of stability and motion performance.The girder body and wedge mechanism made with iron or steel have little influence on the stability of the support system.The accuracy of dynamic stiffness test and finite element simulation results is verified.Further test will be performed in the HEPS site to verify the performance.
