We designed and investigated a passive synchronized mode-locked fiber laser.The device utilizes a dual-cavity structure driven by the nonlinear polarization rotation(NPR)mechanism.Stable mode-locking is attained by sy...We designed and investigated a passive synchronized mode-locked fiber laser.The device utilizes a dual-cavity structure driven by the nonlinear polarization rotation(NPR)mechanism.Stable mode-locking is attained by synergistically controlling gain,polarization state,and optical path length in two symmetric sub-cavities.Experiments proved that repetition rate of the sub-cavities can be adjusted via the time delay line(TDL)to achieve synchronized mode-locking.The system stably generates multi-wavelength pulses at a single repetition frequency,evidenced by multiple spectral peaks and equidistant pulse sequences.These findings facilitate the development of high-performance multi-wavelength ultrashort pulse sources,crucial for optical communications,spectral analysis,and remote sensing.展开更多
Lip synchronization serves as a core technology for enabling natural interactions in digital virtual humans.However,it faces challenges such as insufficient dynamic correspondence between speech and lip movements and ...Lip synchronization serves as a core technology for enabling natural interactions in digital virtual humans.However,it faces challenges such as insufficient dynamic correspondence between speech and lip movements and inadequate modeling of image details.To address these limitations,a comprehensively optimized lip synchronization framework extending the Wav2Lip architecture was proposed in this study.Firstly,based on the Wav2Lip model,a facial region extraction strategy using facial keypoints was designed,which effectively enhances the robustness of facial alignment during lip synchronization for digital virtual humans.Then,a cross-modal attention fusion module between visual and speech features was introduced to improve cross-modal information fusion,and a dynamic receptive field convolution module was developed in the generation branch to enhance the modeling performance of the lip region.Finally,experiments were conducted on the VFHQ dataset.The proposed method was compared with Wav2Lip,VideoRetalking,and DI-Net models,and its performance was evaluated using three metrics:LSE-C,CSIM,and FID.Experimental results showed that the proposed method achieves significant improvements in synchronization accuracy and image fidelity,providing an efficient and feasible solution for lip-synthesis tasks of digital virtual humans.展开更多
Projective synchronization problems of a drive system and a particular response network were investigated,where the drive system is an arbitrary system with n+1 dimensions;it may be a linear or nonlinear system,and ev...Projective synchronization problems of a drive system and a particular response network were investigated,where the drive system is an arbitrary system with n+1 dimensions;it may be a linear or nonlinear system,and even a chaotic or hyperchaotic system,the response network is complex system coupled by N nodes,and every node is showed by the approximately linear part of the drive system.Only controlling any one node of the response network by designed controller can achieve the projective synchronization.Some numerical examples were employed to verify the effectiveness and correctness of the designed controller.展开更多
Investigating the characteristics of synchronous electrical explosions of multiple exploding foil initiators(EFI)in the same circuit,a four-point series-connected EFI circuit utilizing flexible flat cables was designe...Investigating the characteristics of synchronous electrical explosions of multiple exploding foil initiators(EFI)in the same circuit,a four-point series-connected EFI circuit utilizing flexible flat cables was designed to analyze the electrical explosion characteristics.Loop current and terminal voltages of each EFI were recorded to characterize the multi-point series-connected EFI explosion.The effects of voltage,capacitance,and loop length on the response time,energy deposition,and energy utilization efficiency of the multi-point series-connected EFI were explored.Based on the FIRESET model,a mathematical model for the multi-point series-connected EFI explosion was developed,and the influence of initial resistivity on the peak voltage during electrical explosion was quantitatively analyzed.Results indicate that the primary factor influencing the response time is the conduction performance of the switch,while the synchronization deviation is minimally affected by variations in voltage and capacitance.At an inter-electrode spacing of 50 mm,within the voltage range of 1,500–3,000 V and capacitance range of 0.22–1.5μF,the minimum and maximum synchronization deviations of the four-point EFI were 2 ns and 11 ns,respectively.As input energy increases,the deposited energy of the EFI rises,but the overall energy utilization efficiency decreases.The computational results of the proposed model align well with the experimental data.Furthermore,higher initial resistivity in the series-connected circuit corresponds to a higher peak voltage during electrical explosion.This work elucidates the characteristics of multi-point series-connected EFI explosions,offering valuable insights for the design of multi-point EFI circuits.展开更多
为了考察水产品中二甲苯麝香和酮麝香的残留量，建立了水产品中痕量二甲苯麝香和酮麝香测定的多重吸附同步净化（MASP）-气相色谱-质谱联用法（GC-MS）。以乙腈高速匀浆提取样品，应用 MASP 方法对样品同时进行提取、盐析和净化，并采用...为了考察水产品中二甲苯麝香和酮麝香的残留量，建立了水产品中痕量二甲苯麝香和酮麝香测定的多重吸附同步净化（MASP）-气相色谱-质谱联用法（GC-MS）。以乙腈高速匀浆提取样品，应用 MASP 方法对样品同时进行提取、盐析和净化，并采用 GC-MS 在选择离子监测（ SIM）模式下测定水产品中的痕量二甲苯麝香和酮麝香，以基质匹配标准溶液外标法定量。选用 DB-5 MS 石英毛细管柱（30 m×0.25 mm×0.25μm），采用电子轰击电离源，二甲苯麝香的选择监测离子为 m / z 282、297、265，酮麝香为 m / z 279、294、191。结果表明：在优化条件下，二甲苯麝香和酮麝香在1～100μg / kg 范围内线性良好，相关系数不低于0.999，检出限（S / N =3）为0.30μg / kg。明虾、花蛤和鳗鱼空白样品中1.0、2.0、10.0μg / kg 3个添加水平下二甲苯麝香和酮麝香的加标回收率为79％～104％，相对标准偏差（RSD）为1.6％～13.3％。本方法具有操作简便、快速、准确的特点，可用于水产品中痕量二甲苯麝香和酮麝香的日常检测。展开更多
The thrust hydraulic system of the prototype shield machine with pressure and flow compound control scheme was introduced. The experimental system integrated with proportional valves for study was designed. Dynamics m...The thrust hydraulic system of the prototype shield machine with pressure and flow compound control scheme was introduced. The experimental system integrated with proportional valves for study was designed. Dynamics modeling of multi-cylinder thrust system and synchronous control design were accomplished. The simulation of the synchronization motion control system was completed in AMESim and Matlab/Simulink software environments. The experiment was conducted by means of master/slave PID with dead band compensating flow and conventional PID regulating pressure. The experimental results show that the proposed thrust hydraulic system and its control strategy can meet the requirements of tunneling in motion and posture control for the shield machine, keeping the non-synchronous error within ±3 mm.展开更多
A sliding mode and active disturbance rejection control(SM-ADRC)was employed to regulate the speed of a permanent magnet synchronous motor(PMSM).The major advantages of the proposed control scheme are that it can main...A sliding mode and active disturbance rejection control(SM-ADRC)was employed to regulate the speed of a permanent magnet synchronous motor(PMSM).The major advantages of the proposed control scheme are that it can maintain the original features of ADRC and make the parameters of ADRC transition smoothly.The proposed control scheme also ensures speed control accuracy and improves the robustness and anti-load disturbance ability of the system.Moreover,through the analysis of a d-axis current output equation,a novel current-loop SM-ADRC is presented to improve the system’s dynamic performance and inner ability of anti-load disturbance.Results of a simulation and experiments show that the improved sliding-mode ADRC system has the advantages of fast response,small overshoot,small steady-state error,wide speed range and high control accuracy.It shows that the system has strong anti-interference ability to reduce the influence of variations in rotational inertia,load and internal parameters.展开更多
The distributed-power electric multiple units(EMUs)are widely used in high-speed railway.Due to the structural characteristic of mutual-coupled power units in EMUs,each power unit is set as an agent.Combining with the...The distributed-power electric multiple units(EMUs)are widely used in high-speed railway.Due to the structural characteristic of mutual-coupled power units in EMUs,each power unit is set as an agent.Combining with the traction/brake characteristic curve and running data of EMUs,a subtractive clustering method and pattern classification algorithm are adopted to set up a multi-model set for every agent.Then,the multi-agent model is established according to the multi-agent network topology and mutual-coupled constraint relations.Finally,we adopt a smooth start switching control strategy and a multi-agent distributed coordination control algorithm to ensure the synchronous speed tracking control of each agent.Simulation results on the actual CRH380A running data show the effectiveness of the proposed approach.展开更多
A complete method of synchronization technology of bistatic radar using global position system （GPS） is presented. The pulse per second signal （1PPS） is elaborately modified to increase the time synchronization pr...A complete method of synchronization technology of bistatic radar using global position system （GPS） is presented. The pulse per second signal （1PPS） is elaborately modified to increase the time synchronization precision and keep loop locking. A very high time synchronization precision is achieved. Using the modified 1PPS to discipline the local OCXO, the reference frequency signal achieves both high long term stability （LTS） and short term stability （STS） properties. An algorithm, named phase abrupt change CFAR is presented to restrain the 1PPS phase abrupt change and keep loop locking. The experimental results indicate that this time and frequency synchronization method is effective and the time synchronization precision of the synchronization system can be improved from ±100 ns to ±25 ns. In addition, the phase noise is improved to 20 dB.展开更多
A more general form of projective synchronization, so called linear generalized synchronization （LGS） is proposed, which includes the generalized projective synchronization （GPS） and the hybrid projective synchron...A more general form of projective synchronization, so called linear generalized synchronization （LGS） is proposed, which includes the generalized projective synchronization （GPS） and the hybrid projective synchronization （HPS） as its special cases, Based on the adaptive technique and Lyapunov stability theory, a general method for achieving the LGS between two chaotic or hyperehaotic systems with uncertain parameters in any scaling matrix is presented. Some numerical simulations are provided to show the effectiveness and feasibility of the proposed synchronization method.展开更多
A simple control structure in servo system is occasionally needed for simple industrial application which precise and high control performance is not exessively important so that the cost production can be reduced eff...A simple control structure in servo system is occasionally needed for simple industrial application which precise and high control performance is not exessively important so that the cost production can be reduced efficiently. Simplified vector control, which has simple control structure, is utilized as the permanent magnet synchronous motor control algorithm and genetic algorithm is used to tune three PI controllers used in simplified vector control. The control performance is obtained from simulation and investigated to verify the feasibility of the algorithm to be applied in the real application. Simulation results show that the speed and torque responses of the system in both continuous time and discrete time can achieve good performances. Furthermore, simplified vector control combined with genetic algorithm has a similar perfofmance with conventional field oriented control algorithm and possible to be realized into the real simple application in the future.展开更多
A new concept of banana vibrating screen which has the same effect as traditional banana vibrating screen in a new way was put forward.The dynamic model of vibrating screen was established and its working principle wa...A new concept of banana vibrating screen which has the same effect as traditional banana vibrating screen in a new way was put forward.The dynamic model of vibrating screen was established and its working principle was analyzed when the action line of the exciting force did not act through the centroid of screen box.Moreover,the dynamic differential equations of centroid and screen surface were obtained.The motions of centroid and screen surface were simulated with actual parameters of the design example in Matlab/Simulink.The results show that not only the amplitude has a significant decrease from 9.38 to 4.10 mm,but also the throwing index and vibrating direction angle have a significant decrease from 10.49 to 4.59,and from 58.10° to 33.29°,respectively,along the screen surface,which indicates that motion characteristics of vibrating screen are consistent with those of traditional banana vibrating screen only by means of a single angle of screen surface.What's more,such banana vibrating screen of variable linear trajectory with greater processing capacity could be obtained by adjusting the relative position of force center and the centroid of screen box properly.展开更多
Time synchronization is a critical middleware service of wireless sensor networks. Researchers have already proposed some time synchronization algorithms. However, due to the demands for various synchronization precis...Time synchronization is a critical middleware service of wireless sensor networks. Researchers have already proposed some time synchronization algorithms. However, due to the demands for various synchronization precision, existing time synchronization algorithms often need to be adapted. So it is necessary to evaluate these adapted algorithms before use. Software simulation is a valid and quick way to do it. In this paper, we present a time synchronization simulator, Simsync, for wireless sensor networks. We decompose the packet delay into 6 delay components and model them separately. The frequency of crystal oscillator is modeled as Gaussian. To testify its effectiveness, we simulate the reference broadcast synchronization algorithm (RBS) and the timing-sync synchronization algorithm (TPSN) on Simsync. Simulated results are also presented and analyzed.展开更多
Micro-satellite cluster enables a whole new class of missions for communications, remote sensing, and scientific research for both civilian and military purposes. Synchronizing the time of the satellites in a cluster ...Micro-satellite cluster enables a whole new class of missions for communications, remote sensing, and scientific research for both civilian and military purposes. Synchronizing the time of the satellites in a cluster is important for both cluster sensing capabilities and its autonomous operating. However, the existing time synchronization methods are not suitable for microsatellite cluster, because it requires too many human interventions and occupies too much ground control resource. Although, data post-process may realize the equivalent time synchronization, it requires processing time and powerful computing ability on the ground, which cannot be implemented by cluster itself. In order to autonomously establish and maintain the time benchmark in a cluster, we propose a compact time difference compensation system（TDCS）, which is a kind of time control loop that dynamically adjusts the satellite reference frequency according to the time difference. Consequently, the time synchronization in the cluster can be autonomously achieved on-orbit by synchronizing the clock of other satellites to a chosen one＇s. The experimental result shows that the standard deviation of time synchronization is about 102 ps when the carrier to noise ratio（CNR） is 95 d BHz, and the standard deviation of corresponding frequency difference is approximately0.36 Hz.展开更多
文摘We designed and investigated a passive synchronized mode-locked fiber laser.The device utilizes a dual-cavity structure driven by the nonlinear polarization rotation(NPR)mechanism.Stable mode-locking is attained by synergistically controlling gain,polarization state,and optical path length in two symmetric sub-cavities.Experiments proved that repetition rate of the sub-cavities can be adjusted via the time delay line(TDL)to achieve synchronized mode-locking.The system stably generates multi-wavelength pulses at a single repetition frequency,evidenced by multiple spectral peaks and equidistant pulse sequences.These findings facilitate the development of high-performance multi-wavelength ultrashort pulse sources,crucial for optical communications,spectral analysis,and remote sensing.
文摘Lip synchronization serves as a core technology for enabling natural interactions in digital virtual humans.However,it faces challenges such as insufficient dynamic correspondence between speech and lip movements and inadequate modeling of image details.To address these limitations,a comprehensively optimized lip synchronization framework extending the Wav2Lip architecture was proposed in this study.Firstly,based on the Wav2Lip model,a facial region extraction strategy using facial keypoints was designed,which effectively enhances the robustness of facial alignment during lip synchronization for digital virtual humans.Then,a cross-modal attention fusion module between visual and speech features was introduced to improve cross-modal information fusion,and a dynamic receptive field convolution module was developed in the generation branch to enhance the modeling performance of the lip region.Finally,experiments were conducted on the VFHQ dataset.The proposed method was compared with Wav2Lip,VideoRetalking,and DI-Net models,and its performance was evaluated using three metrics:LSE-C,CSIM,and FID.Experimental results showed that the proposed method achieves significant improvements in synchronization accuracy and image fidelity,providing an efficient and feasible solution for lip-synthesis tasks of digital virtual humans.
基金Supported by the National Natural Science Foundation of China (11161027)。
文摘Projective synchronization problems of a drive system and a particular response network were investigated,where the drive system is an arbitrary system with n+1 dimensions;it may be a linear or nonlinear system,and even a chaotic or hyperchaotic system,the response network is complex system coupled by N nodes,and every node is showed by the approximately linear part of the drive system.Only controlling any one node of the response network by designed controller can achieve the projective synchronization.Some numerical examples were employed to verify the effectiveness and correctness of the designed controller.
文摘Investigating the characteristics of synchronous electrical explosions of multiple exploding foil initiators(EFI)in the same circuit,a four-point series-connected EFI circuit utilizing flexible flat cables was designed to analyze the electrical explosion characteristics.Loop current and terminal voltages of each EFI were recorded to characterize the multi-point series-connected EFI explosion.The effects of voltage,capacitance,and loop length on the response time,energy deposition,and energy utilization efficiency of the multi-point series-connected EFI were explored.Based on the FIRESET model,a mathematical model for the multi-point series-connected EFI explosion was developed,and the influence of initial resistivity on the peak voltage during electrical explosion was quantitatively analyzed.Results indicate that the primary factor influencing the response time is the conduction performance of the switch,while the synchronization deviation is minimally affected by variations in voltage and capacitance.At an inter-electrode spacing of 50 mm,within the voltage range of 1,500–3,000 V and capacitance range of 0.22–1.5μF,the minimum and maximum synchronization deviations of the four-point EFI were 2 ns and 11 ns,respectively.As input energy increases,the deposited energy of the EFI rises,but the overall energy utilization efficiency decreases.The computational results of the proposed model align well with the experimental data.Furthermore,higher initial resistivity in the series-connected circuit corresponds to a higher peak voltage during electrical explosion.This work elucidates the characteristics of multi-point series-connected EFI explosions,offering valuable insights for the design of multi-point EFI circuits.
文摘为了考察水产品中二甲苯麝香和酮麝香的残留量，建立了水产品中痕量二甲苯麝香和酮麝香测定的多重吸附同步净化（MASP）-气相色谱-质谱联用法（GC-MS）。以乙腈高速匀浆提取样品，应用 MASP 方法对样品同时进行提取、盐析和净化，并采用 GC-MS 在选择离子监测（ SIM）模式下测定水产品中的痕量二甲苯麝香和酮麝香，以基质匹配标准溶液外标法定量。选用 DB-5 MS 石英毛细管柱（30 m×0.25 mm×0.25μm），采用电子轰击电离源，二甲苯麝香的选择监测离子为 m / z 282、297、265，酮麝香为 m / z 279、294、191。结果表明：在优化条件下，二甲苯麝香和酮麝香在1～100μg / kg 范围内线性良好，相关系数不低于0.999，检出限（S / N =3）为0.30μg / kg。明虾、花蛤和鳗鱼空白样品中1.0、2.0、10.0μg / kg 3个添加水平下二甲苯麝香和酮麝香的加标回收率为79％～104％，相对标准偏差（RSD）为1.6％～13.3％。本方法具有操作简便、快速、准确的特点，可用于水产品中痕量二甲苯麝香和酮麝香的日常检测。
基金Project(50425518) supported by National Outstanding Youth Foundation of China Project(2007CB714004) supported by National Basic Research Program of China
文摘The thrust hydraulic system of the prototype shield machine with pressure and flow compound control scheme was introduced. The experimental system integrated with proportional valves for study was designed. Dynamics modeling of multi-cylinder thrust system and synchronous control design were accomplished. The simulation of the synchronization motion control system was completed in AMESim and Matlab/Simulink software environments. The experiment was conducted by means of master/slave PID with dead band compensating flow and conventional PID regulating pressure. The experimental results show that the proposed thrust hydraulic system and its control strategy can meet the requirements of tunneling in motion and posture control for the shield machine, keeping the non-synchronous error within ±3 mm.
基金Project(2011AA11A10102) supported by the High-tech Research and Development Program of China
文摘A sliding mode and active disturbance rejection control(SM-ADRC)was employed to regulate the speed of a permanent magnet synchronous motor(PMSM).The major advantages of the proposed control scheme are that it can maintain the original features of ADRC and make the parameters of ADRC transition smoothly.The proposed control scheme also ensures speed control accuracy and improves the robustness and anti-load disturbance ability of the system.Moreover,through the analysis of a d-axis current output equation,a novel current-loop SM-ADRC is presented to improve the system’s dynamic performance and inner ability of anti-load disturbance.Results of a simulation and experiments show that the improved sliding-mode ADRC system has the advantages of fast response,small overshoot,small steady-state error,wide speed range and high control accuracy.It shows that the system has strong anti-interference ability to reduce the influence of variations in rotational inertia,load and internal parameters.
基金Supported by National Natural Science Foundation of China(61164013,U1334211,51174091)the Key Program of China Ministry of Railway(2011Z002-D)Natural Science Foundation of Jiangxi Province(20122BAB201021)
文摘The distributed-power electric multiple units(EMUs)are widely used in high-speed railway.Due to the structural characteristic of mutual-coupled power units in EMUs,each power unit is set as an agent.Combining with the traction/brake characteristic curve and running data of EMUs,a subtractive clustering method and pattern classification algorithm are adopted to set up a multi-model set for every agent.Then,the multi-agent model is established according to the multi-agent network topology and mutual-coupled constraint relations.Finally,we adopt a smooth start switching control strategy and a multi-agent distributed coordination control algorithm to ensure the synchronous speed tracking control of each agent.Simulation results on the actual CRH380A running data show the effectiveness of the proposed approach.
基金the National Ministry Innovation Foundation (7130302)
文摘A complete method of synchronization technology of bistatic radar using global position system （GPS） is presented. The pulse per second signal （1PPS） is elaborately modified to increase the time synchronization precision and keep loop locking. A very high time synchronization precision is achieved. Using the modified 1PPS to discipline the local OCXO, the reference frequency signal achieves both high long term stability （LTS） and short term stability （STS） properties. An algorithm, named phase abrupt change CFAR is presented to restrain the 1PPS phase abrupt change and keep loop locking. The experimental results indicate that this time and frequency synchronization method is effective and the time synchronization precision of the synchronization system can be improved from ±100 ns to ±25 ns. In addition, the phase noise is improved to 20 dB.
基金the National Natural Science Foundation of China (60574045 10661006).
文摘A more general form of projective synchronization, so called linear generalized synchronization （LGS） is proposed, which includes the generalized projective synchronization （GPS） and the hybrid projective synchronization （HPS） as its special cases, Based on the adaptive technique and Lyapunov stability theory, a general method for achieving the LGS between two chaotic or hyperehaotic systems with uncertain parameters in any scaling matrix is presented. Some numerical simulations are provided to show the effectiveness and feasibility of the proposed synchronization method.
文摘A simple control structure in servo system is occasionally needed for simple industrial application which precise and high control performance is not exessively important so that the cost production can be reduced efficiently. Simplified vector control, which has simple control structure, is utilized as the permanent magnet synchronous motor control algorithm and genetic algorithm is used to tune three PI controllers used in simplified vector control. The control performance is obtained from simulation and investigated to verify the feasibility of the algorithm to be applied in the real application. Simulation results show that the speed and torque responses of the system in both continuous time and discrete time can achieve good performances. Furthermore, simplified vector control combined with genetic algorithm has a similar perfofmance with conventional field oriented control algorithm and possible to be realized into the real simple application in the future.
基金Projects(50574091, 50774084) supported by the National Natural Science Foundation of ChinaProject(50921001) supported by the Innovative Research Group Science Foundation,ChinaProject supported by Jiangsu Scientific Researching Fund Project ("333" Project),China
文摘A new concept of banana vibrating screen which has the same effect as traditional banana vibrating screen in a new way was put forward.The dynamic model of vibrating screen was established and its working principle was analyzed when the action line of the exciting force did not act through the centroid of screen box.Moreover,the dynamic differential equations of centroid and screen surface were obtained.The motions of centroid and screen surface were simulated with actual parameters of the design example in Matlab/Simulink.The results show that not only the amplitude has a significant decrease from 9.38 to 4.10 mm,but also the throwing index and vibrating direction angle have a significant decrease from 10.49 to 4.59,and from 58.10° to 33.29°,respectively,along the screen surface,which indicates that motion characteristics of vibrating screen are consistent with those of traditional banana vibrating screen only by means of a single angle of screen surface.What's more,such banana vibrating screen of variable linear trajectory with greater processing capacity could be obtained by adjusting the relative position of force center and the centroid of screen box properly.
基金Supported in part by National Basic Research Program of P. R. China(2005CB321604) in part by National Natural Science Foundation of P. R. China (90207002)
文摘Time synchronization is a critical middleware service of wireless sensor networks. Researchers have already proposed some time synchronization algorithms. However, due to the demands for various synchronization precision, existing time synchronization algorithms often need to be adapted. So it is necessary to evaluate these adapted algorithms before use. Software simulation is a valid and quick way to do it. In this paper, we present a time synchronization simulator, Simsync, for wireless sensor networks. We decompose the packet delay into 6 delay components and model them separately. The frequency of crystal oscillator is modeled as Gaussian. To testify its effectiveness, we simulate the reference broadcast synchronization algorithm (RBS) and the timing-sync synchronization algorithm (TPSN) on Simsync. Simulated results are also presented and analyzed.
基金supported by the National Natural Science Foundation of China(61401389)the Joint Fund of the Ministry of Education of China(6141A02033310)
文摘Micro-satellite cluster enables a whole new class of missions for communications, remote sensing, and scientific research for both civilian and military purposes. Synchronizing the time of the satellites in a cluster is important for both cluster sensing capabilities and its autonomous operating. However, the existing time synchronization methods are not suitable for microsatellite cluster, because it requires too many human interventions and occupies too much ground control resource. Although, data post-process may realize the equivalent time synchronization, it requires processing time and powerful computing ability on the ground, which cannot be implemented by cluster itself. In order to autonomously establish and maintain the time benchmark in a cluster, we propose a compact time difference compensation system（TDCS）, which is a kind of time control loop that dynamically adjusts the satellite reference frequency according to the time difference. Consequently, the time synchronization in the cluster can be autonomously achieved on-orbit by synchronizing the clock of other satellites to a chosen one＇s. The experimental result shows that the standard deviation of time synchronization is about 102 ps when the carrier to noise ratio（CNR） is 95 d BHz, and the standard deviation of corresponding frequency difference is approximately0.36 Hz.
