Since the entry into force of the International Convention on liability and compensation for oil spill damage, there have been many discussions on the improvement of this regime. Based on the existing tworegimes, the ...Since the entry into force of the International Convention on liability and compensation for oil spill damage, there have been many discussions on the improvement of this regime. Based on the existing tworegimes, the writer tried to analysis the advantages of the new regimes and foresee the trends of the international regime of liability and compensation for oil pollution damage.展开更多
In order to investigate the joint torque-based Cartesian impedance control strategies and the influence of compensations for friction, an experimental study on the identification of friction parameters, friction compe...In order to investigate the joint torque-based Cartesian impedance control strategies and the influence of compensations for friction, an experimental study on the identification of friction parameters, friction compensation and the Cartesian impedance control are developed for the harmonic drive robot, by using the sensors available in the joint itself. Different from the conventional Cartesian impedance control schemes which are mostly based on the robot end force/torque information, five joint torque-based Cartesian impedance control schemes are considered, including the force-based schemes in Cartesian/joint space, the position-based schemes in Cartesian/joint space and the stiffness control. Four of them are verified by corresponding experiments with/without friction compensations. By comparison, it is found that the force-based impedance control strategy is more suitable than the position-based one for the robot based on joint torque feedback and the friction has even a positive effect on Cartesian impedance control stability.展开更多
The existing kinematic parameter calibration method cannot further improve the absolute positioning accuracy of the robot due to the uncertainty of positioning error caused by robot joint backlash.In view of this prob...The existing kinematic parameter calibration method cannot further improve the absolute positioning accuracy of the robot due to the uncertainty of positioning error caused by robot joint backlash.In view of this problem,a closed‑loop feedback accuracy compensation method for robot joints was proposed.Firstly,a Chebyshev polynomial error estimation model was established which took geometric error and non‑geometric error into account.In addition,the absolute linear grating scale was installed at each joint of the robot and the positioning error of the robot end was mapped to the joint angle.And the joint angle corrected value was obtained.Furthermore,the closed‑loop feedback of robot joints was established to realize the online correction of the positioning error.Finally,an experiment on the KUKA KR210 industrial robot was conducted to demonstrate the effectiveness of the method.The result shows that the maximum absolute positioning error of the robot is reduced by 75%from 0.76 mm to 0.19 mm.This method can compensate the robot joint backlash effectively and further improve the absolute positioning accuracy of the robot.展开更多
A system of jointly transferring time signals with a rate of 1 pulse per second （PPS） and frequency signals of 10 MHz via a dense wavelength division multiplex-based （DWDM） fiber is demonstrated in this paper. The...A system of jointly transferring time signals with a rate of 1 pulse per second （PPS） and frequency signals of 10 MHz via a dense wavelength division multiplex-based （DWDM） fiber is demonstrated in this paper. The noises of the fiber links are suppressed and compensated for by a controlled fiber delay line. A method of calibrating and characterizing time is described. The 1PPS is synchronized by feed-forward calibrating the fiber delays precisely. The system is experimen- tally examined via a 110 km spooled fiber in laboratory. The frequency stabilities of the user end with compensation are 1.8x 10-14 at 1 s and 2.0x 10-17 at 104 s average time. The calculated uncertainty of time synchronization is 13.1 ps, whereas the direct measurement of the uncertainty is 12 ps. Next, the frequency and 1PPS are transferred via a metropoli- tan area optical fiber network from one central site to two remote sites with distances of 14 km and 110 km. The frequency stabilities of 14 km link reach 3.0x 10-14 averaged in 1 s and 1.4x 10-17 in 104 s respectively; and the stabilities of 110 km link are 8.3 x 10-14 and 1.7 x 10-17, respectively. The accuracies of synchronization are estimated to be 12.3 ps for the 14 km link and 13.1 ps for the 110 km link, respectively.展开更多
Aiming at the inaccurate transmission estimation problem of dark channel prior image dehazing algorithm in the sudden change area of depth of field and sky area,a dehazing algorithm using adaptive dark channel fusion ...Aiming at the inaccurate transmission estimation problem of dark channel prior image dehazing algorithm in the sudden change area of depth of field and sky area,a dehazing algorithm using adaptive dark channel fusion and sky compensation is proposed.Firstly,according to the characteristics of minimum filtering of large window scale and small window scale in the dark channel prior,the fused dark channel is obtained by weighted fusion of the approximate depth of field relationship,thus obtaining the primary transmission.Secondly,use the down-sampling to optimize the primary transmission combined with gray scale image of haze image by fast joint bilateral filtering,then restore the original image size by up-sampling,and the compensation of the Gaussian function is used in the sky area to obtain corrected transmission.Finally,the improved atmospheric light is combined with atmospheric scattering model to recover haze-free image.Experimental results show that the algorithm can recover a large amount of detailed information of the image,obtain high visibility,and effectively eliminate the halo effect.At the same time,it has a better recovery effect on bright areas such as the sky area.展开更多
In this paper, we proposed a novel method of joint phase noise estimate (JPNE) for PDM-M-QAM (M = 4, 16, 32, 64, …) transmission systems, and established the theoretical model to illustrate the operation mechanism. T...In this paper, we proposed a novel method of joint phase noise estimate (JPNE) for PDM-M-QAM (M = 4, 16, 32, 64, …) transmission systems, and established the theoretical model to illustrate the operation mechanism. The simulation of laser phase noise and fiber nonlinearity compensation based on the proposed JPNE method had also been demonstrated. For 112 Gb/s PDM-4QAM transmission system, the simulation results had showed that the optimum launch power increased from -4 dBm to at least 0 dBm compared with the condition of no phase noise compensation in reach of all simulation distances.展开更多
文摘Since the entry into force of the International Convention on liability and compensation for oil spill damage, there have been many discussions on the improvement of this regime. Based on the existing tworegimes, the writer tried to analysis the advantages of the new regimes and foresee the trends of the international regime of liability and compensation for oil pollution damage.
基金The National Natural Science Foundation of China(No.60675045)the National High Technology Research and Development Program of China (863Program) (No.2006AA04Z255)
文摘In order to investigate the joint torque-based Cartesian impedance control strategies and the influence of compensations for friction, an experimental study on the identification of friction parameters, friction compensation and the Cartesian impedance control are developed for the harmonic drive robot, by using the sensors available in the joint itself. Different from the conventional Cartesian impedance control schemes which are mostly based on the robot end force/torque information, five joint torque-based Cartesian impedance control schemes are considered, including the force-based schemes in Cartesian/joint space, the position-based schemes in Cartesian/joint space and the stiffness control. Four of them are verified by corresponding experiments with/without friction compensations. By comparison, it is found that the force-based impedance control strategy is more suitable than the position-based one for the robot based on joint torque feedback and the friction has even a positive effect on Cartesian impedance control stability.
基金supported by the National Natural Science Foundation of China(Nos.51875287, 52075250)the Special Fund for Transformation of Scientific,and Technological Achievements of Jiangsu Province(No.BA2018053)
文摘The existing kinematic parameter calibration method cannot further improve the absolute positioning accuracy of the robot due to the uncertainty of positioning error caused by robot joint backlash.In view of this problem,a closed‑loop feedback accuracy compensation method for robot joints was proposed.Firstly,a Chebyshev polynomial error estimation model was established which took geometric error and non‑geometric error into account.In addition,the absolute linear grating scale was installed at each joint of the robot and the positioning error of the robot end was mapped to the joint angle.And the joint angle corrected value was obtained.Furthermore,the closed‑loop feedback of robot joints was established to realize the online correction of the positioning error.Finally,an experiment on the KUKA KR210 industrial robot was conducted to demonstrate the effectiveness of the method.The result shows that the maximum absolute positioning error of the robot is reduced by 75%from 0.76 mm to 0.19 mm.This method can compensate the robot joint backlash effectively and further improve the absolute positioning accuracy of the robot.
基金supported by the National Natural Science Foundation of China(Grant No.61405227)
文摘A system of jointly transferring time signals with a rate of 1 pulse per second （PPS） and frequency signals of 10 MHz via a dense wavelength division multiplex-based （DWDM） fiber is demonstrated in this paper. The noises of the fiber links are suppressed and compensated for by a controlled fiber delay line. A method of calibrating and characterizing time is described. The 1PPS is synchronized by feed-forward calibrating the fiber delays precisely. The system is experimen- tally examined via a 110 km spooled fiber in laboratory. The frequency stabilities of the user end with compensation are 1.8x 10-14 at 1 s and 2.0x 10-17 at 104 s average time. The calculated uncertainty of time synchronization is 13.1 ps, whereas the direct measurement of the uncertainty is 12 ps. Next, the frequency and 1PPS are transferred via a metropoli- tan area optical fiber network from one central site to two remote sites with distances of 14 km and 110 km. The frequency stabilities of 14 km link reach 3.0x 10-14 averaged in 1 s and 1.4x 10-17 in 104 s respectively; and the stabilities of 110 km link are 8.3 x 10-14 and 1.7 x 10-17, respectively. The accuracies of synchronization are estimated to be 12.3 ps for the 14 km link and 13.1 ps for the 110 km link, respectively.
基金National Natural Science Foundation of China(No.61561030)Natural Science Foundation of Science and Technology Department of Gansu Province(No.1310RJZA050)Basic Research Projects Supported by Operating Expenses of Finance Department of Gansu Province(No.214138)。
文摘Aiming at the inaccurate transmission estimation problem of dark channel prior image dehazing algorithm in the sudden change area of depth of field and sky area,a dehazing algorithm using adaptive dark channel fusion and sky compensation is proposed.Firstly,according to the characteristics of minimum filtering of large window scale and small window scale in the dark channel prior,the fused dark channel is obtained by weighted fusion of the approximate depth of field relationship,thus obtaining the primary transmission.Secondly,use the down-sampling to optimize the primary transmission combined with gray scale image of haze image by fast joint bilateral filtering,then restore the original image size by up-sampling,and the compensation of the Gaussian function is used in the sky area to obtain corrected transmission.Finally,the improved atmospheric light is combined with atmospheric scattering model to recover haze-free image.Experimental results show that the algorithm can recover a large amount of detailed information of the image,obtain high visibility,and effectively eliminate the halo effect.At the same time,it has a better recovery effect on bright areas such as the sky area.
文摘In this paper, we proposed a novel method of joint phase noise estimate (JPNE) for PDM-M-QAM (M = 4, 16, 32, 64, …) transmission systems, and established the theoretical model to illustrate the operation mechanism. The simulation of laser phase noise and fiber nonlinearity compensation based on the proposed JPNE method had also been demonstrated. For 112 Gb/s PDM-4QAM transmission system, the simulation results had showed that the optimum launch power increased from -4 dBm to at least 0 dBm compared with the condition of no phase noise compensation in reach of all simulation distances.
