Self-Synchronous principle of vibrating machines in asymmetric system is studied, and a design method is put forward. Based on Hamilton’s principle, a stable difference of phase angle is obtained,and this design meth...Self-Synchronous principle of vibrating machines in asymmetric system is studied, and a design method is put forward. Based on Hamilton’s principle, a stable difference of phase angle is obtained,and this design method is proved correct.展开更多
This study proposes a novel multi-fractal spectrumbasedapproach to distinguish linear block codes from its selfsynchronousscrambled codes. Given that the linear block codeand self-synchronous scrambled linear block co...This study proposes a novel multi-fractal spectrumbasedapproach to distinguish linear block codes from its selfsynchronousscrambled codes. Given that the linear block codeand self-synchronous scrambled linear block code share the propertyof linear correlation, the existing linear correlation-basedidentification method is invalid for this case. This drawback can becircumvented by introducing a novel multi-fractal spectrum-basedmethod. Simulation results show that the new method has highrobustness and under the same conditions of bit error, the lowerthe code rate, the higher the recognition rate. Thus, the methodhas significant potential for future application in engineering.展开更多
An algorithm based on eigenanalysis technique and Walsh-Hadamard transform （WriT） is proposed. The algorithm contains two steps. Firstly, the received sequence is divided into temporal windows, and a covariance matr...An algorithm based on eigenanalysis technique and Walsh-Hadamard transform （WriT） is proposed. The algorithm contains two steps. Firstly, the received sequence is divided into temporal windows, and a covariance matrix is computed. The linear feedback shift register （LFSR） sequence is reconstructed from the first eigenvector of this matrix. Secondly, equations according to the recovered LFSR sequence are constructed, and the Walsh spectrum corresponding to the equations is computed. The feedback polynomial of LFSR is estimated from the Walsh spectrum. The validity of the algorithm is verified by the simulation result. Finally, case studies are presented to illustrate the performance of the blind reconstruction method.展开更多
Multi-motor vibratory transmission systems have been wide used in large vibratory machines, and four-motor linear vibratory machine is one typical equipment of them. Under non-forcible synchronization condition zero...Multi-motor vibratory transmission systems have been wide used in large vibratory machines, and four-motor linear vibratory machine is one typical equipment of them. Under non-forcible synchronization condition zero-phase synchronization of the machine is non-stationary and it-phase synchronization is stable. Under half-forcible synchronization condition in which only one motor is controlled being synchronous to another, only lag synchronization near zero-phase synchronization can be realized. Both of the characteristics have never been revealed with classical theory quantitatively. The problem is solved by means of establishing an electromechanical coupling mathematical model of the system and numerical analysis of the starting processes.展开更多
This paper studies self-synchronization and stability of a dual-motor driven vibration system with a two-stage vibration isolation frame. Oscillation amplitude of the material box large enough can be ensured on the vi...This paper studies self-synchronization and stability of a dual-motor driven vibration system with a two-stage vibration isolation frame. Oscillation amplitude of the material box large enough can be ensured on the vibration system in order to screen materials. Reduction of the dynamic load transmitted to the foundation can also be achieved for the vibration system. A Lagrange equation is used to set up the motion differential equations of the system, and a dimensionless coupled equation of the eccentric rotors is obtained using a method of modified average small parameter. According to the existence condition of zero solution in the dimensionless coupled equation of the eccentric rotors, the precondition for commencing self-synchronization motion is achieved.The stability condition of self-synchronization is obtained based on the Routh-Hurwitz criterion. The theoretical analysis is validated by simulations and experiments.展开更多
We present a self-synchronizing stream encryption scheme based on one-dimensional coupled map lattices which is introduced as a model with the essential features of spatiotemporal chaos, and of great complexity and di...We present a self-synchronizing stream encryption scheme based on one-dimensional coupled map lattices which is introduced as a model with the essential features of spatiotemporal chaos, and of great complexity and diffusion capability of the little disturbance in the initial condition. To evaluate the scheme, a series of statistical tests are employed, and the results show good random-look nature of the ciphertext. Furthermore, we apply our algorithm to encrypt a grey-scale image to show the key sensitivity.展开更多
The installed capacity of renewable energy generation has continued to grow rapidly in recent years along with the global energy transition towards a 100%renewable-based power system.At the same time,the grid-connecte...The installed capacity of renewable energy generation has continued to grow rapidly in recent years along with the global energy transition towards a 100%renewable-based power system.At the same time,the grid-connected large-scale renewable energy brings significant challenges to the safe and stable operation of the power system due to the loss of synchronous machines.Therefore,self-synchronous wind turbines have attracted wide attention from both academia and industry.However,the understanding of the physical operation mechanisms of self-synchronous wind turbines is not clear.In particular,the transient characteristics and dynamic processes of wind turbines are fuzzy in the presence of grid disturbances.Furthermore,it is difficult to design an adaptive fault ride-through(FRT)control strategy.Thus,a dual-mode switching FRT control strategy for self-synchronous wind turbines is developed.Two FRT control strategies are used.In one strategy,the amplitude and phase of the internal potential are directly calculated according to the voltage drop when a minor grid fault occurs.The other dual-mode switching control strategy in the presence of a deep grid fault includes three parts:vector control during the grid fault,fault recovery vector control,and self-synchronous control.The proposed control strategy can significantly mitigate transient overvoltage,overcurrent,and multifrequency oscillation,thereby resulting in enhanced transient stability.Finally,simulation results are provided to validate the proposed control strategy.展开更多
文摘Self-Synchronous principle of vibrating machines in asymmetric system is studied, and a design method is put forward. Based on Hamilton’s principle, a stable difference of phase angle is obtained,and this design method is proved correct.
基金supported by the National Natural Science Foundation of China(61171170) the Natural Science Foundation of Anhui Province(1408085QF115)
文摘This study proposes a novel multi-fractal spectrumbasedapproach to distinguish linear block codes from its selfsynchronousscrambled codes. Given that the linear block codeand self-synchronous scrambled linear block code share the propertyof linear correlation, the existing linear correlation-basedidentification method is invalid for this case. This drawback can becircumvented by introducing a novel multi-fractal spectrum-basedmethod. Simulation results show that the new method has highrobustness and under the same conditions of bit error, the lowerthe code rate, the higher the recognition rate. Thus, the methodhas significant potential for future application in engineering.
基金supported by the National Natural Science Foundation of China(61072120)
文摘An algorithm based on eigenanalysis technique and Walsh-Hadamard transform （WriT） is proposed. The algorithm contains two steps. Firstly, the received sequence is divided into temporal windows, and a covariance matrix is computed. The linear feedback shift register （LFSR） sequence is reconstructed from the first eigenvector of this matrix. Secondly, equations according to the recovered LFSR sequence are constructed, and the Walsh spectrum corresponding to the equations is computed. The feedback polynomial of LFSR is estimated from the Walsh spectrum. The validity of the algorithm is verified by the simulation result. Finally, case studies are presented to illustrate the performance of the blind reconstruction method.
基金This project is supported by National Natural Science Foundation of China (No.59875010)
文摘Multi-motor vibratory transmission systems have been wide used in large vibratory machines, and four-motor linear vibratory machine is one typical equipment of them. Under non-forcible synchronization condition zero-phase synchronization of the machine is non-stationary and it-phase synchronization is stable. Under half-forcible synchronization condition in which only one motor is controlled being synchronous to another, only lag synchronization near zero-phase synchronization can be realized. Both of the characteristics have never been revealed with classical theory quantitatively. The problem is solved by means of establishing an electromechanical coupling mathematical model of the system and numerical analysis of the starting processes.
基金Project supported by the National Natural Science Foundation of China(No.51175071)the Fundamental Research Funds for the Central Universities(Nos.N120203001 and N130803001)the National Key Scientific Instrument and Equipment Development Projects(No.2013YQ474765)
文摘This paper studies self-synchronization and stability of a dual-motor driven vibration system with a two-stage vibration isolation frame. Oscillation amplitude of the material box large enough can be ensured on the vibration system in order to screen materials. Reduction of the dynamic load transmitted to the foundation can also be achieved for the vibration system. A Lagrange equation is used to set up the motion differential equations of the system, and a dimensionless coupled equation of the eccentric rotors is obtained using a method of modified average small parameter. According to the existence condition of zero solution in the dimensionless coupled equation of the eccentric rotors, the precondition for commencing self-synchronization motion is achieved.The stability condition of self-synchronization is obtained based on the Routh-Hurwitz criterion. The theoretical analysis is validated by simulations and experiments.
基金The project supported by National Natural Science Foundation of China under Grant Nos. 90203008 and 10547120 and the Doctoral Foundation of the Ministry of Education of China under Grant No. 2002055009
文摘We present a self-synchronizing stream encryption scheme based on one-dimensional coupled map lattices which is introduced as a model with the essential features of spatiotemporal chaos, and of great complexity and diffusion capability of the little disturbance in the initial condition. To evaluate the scheme, a series of statistical tests are employed, and the results show good random-look nature of the ciphertext. Furthermore, we apply our algorithm to encrypt a grey-scale image to show the key sensitivity.
基金supported in part by the National Natural Science Foundation of China (No.52007174)。
文摘The installed capacity of renewable energy generation has continued to grow rapidly in recent years along with the global energy transition towards a 100%renewable-based power system.At the same time,the grid-connected large-scale renewable energy brings significant challenges to the safe and stable operation of the power system due to the loss of synchronous machines.Therefore,self-synchronous wind turbines have attracted wide attention from both academia and industry.However,the understanding of the physical operation mechanisms of self-synchronous wind turbines is not clear.In particular,the transient characteristics and dynamic processes of wind turbines are fuzzy in the presence of grid disturbances.Furthermore,it is difficult to design an adaptive fault ride-through(FRT)control strategy.Thus,a dual-mode switching FRT control strategy for self-synchronous wind turbines is developed.Two FRT control strategies are used.In one strategy,the amplitude and phase of the internal potential are directly calculated according to the voltage drop when a minor grid fault occurs.The other dual-mode switching control strategy in the presence of a deep grid fault includes three parts:vector control during the grid fault,fault recovery vector control,and self-synchronous control.The proposed control strategy can significantly mitigate transient overvoltage,overcurrent,and multifrequency oscillation,thereby resulting in enhanced transient stability.Finally,simulation results are provided to validate the proposed control strategy.
