An alternating current(AC)microgrid is a system that integrates renewable power,power converters,controllers and loads.Hierarchical control can manage the frequency of the microgrid to prevent imbalance and collapse o...An alternating current(AC)microgrid is a system that integrates renewable power,power converters,controllers and loads.Hierarchical control can manage the frequency of the microgrid to prevent imbalance and collapse of the system.The existing frequency control methods use traditional proportion integration(PI)controllers,which cannot adjust PI parameters in real-time to respond to the status changes of the system.Hierarchical control driven by fuzzy logic allows real-time adjustment of the PI parameters and the method used a two-layer control structure.The primary control used droop control to adjust power distribution,and fuzzy logic was used in the voltage loop of the primary control.The secondary control was added to make up for frequency deviation caused by droop control,and fuzzy logic was used in the secondary frequency control to deal with the dynamic change of frequency caused by the disturbances of loads.The proposed method was simulated in Matlab/Simulink.In the primary control,the proposed method reduced the total harmonic distortion(THD)of two cycles of the output voltage from 4.19%to 3.89%;in the secondary control,the proposed method reduced the frequency fluctuation of the system by about 0.03 Hz and 0.04 Hz when the load was increased and decreased,respectively.The results show that the proposed methods have a better effect on frequency maintenance and voltage control of the AC microgrid.展开更多
UV wavelength auto-tuned tuned output system is realized by the difference method. Controlled by the microprocessor, output wavelength auto- tracking is achieved.Besides, equipment self-checking auto-positioning and t...UV wavelength auto-tuned tuned output system is realized by the difference method. Controlled by the microprocessor, output wavelength auto- tracking is achieved.Besides, equipment self-checking auto-positioning and temperature correct are realized,The wavelength tuned output efficiency in the experiment is better than 97 %.展开更多
Subcellular localization and translation of messenger RNAs are essential for the regulation of neuronal development and synaptic function. As post-transcriptional regulators, microRNAs （miRNAs） have been emerging as...Subcellular localization and translation of messenger RNAs are essential for the regulation of neuronal development and synaptic function. As post-transcriptional regulators, microRNAs （miRNAs） have been emerging as central players in the development and maturation of the nervous system. Recent discoveries reveal the critical functions of miRNAs in the axon of neurons via multiple pathways of molecular regulation. Here, we introduce methods for isolating axonal miRNAs and review recent findings on the localization and function as well as regulatory mechanism of axonal miRNAs during axon development.展开更多
The cohort intelligence （CI） method has recently evolved as an optimization method based on artificial intelligence. We use the CI method for the first time to optimize the parameters of the fractional proportional-...The cohort intelligence （CI） method has recently evolved as an optimization method based on artificial intelligence. We use the CI method for the first time to optimize the parameters of the fractional proportional- integral-derivative （PID） controller. The performance of the CI method in designing the fractional PID controller was validated and compared with those of some other popular algorithms such as particle swarm optimization, the genetic algorithm, and the improved electromagnetic algorithm. The CI method yielded improved solutions in terms of the cost function, computing time, and function evaluations in comparison with the other three algorithms. In addition, the standard deviations of the CI method demonstrated the robustness of the proposed algorithm in solving control problems.展开更多
Three-dimensional （3D） copper foams have been formed by electrodeposition at different nitrogen pressures and examined by scanning electron microscopy. The results indicate that an increase in system pressure leads ...Three-dimensional （3D） copper foams have been formed by electrodeposition at different nitrogen pressures and examined by scanning electron microscopy. The results indicate that an increase in system pressure leads to a decrease of the pore size of the copper foam due to the suppressed coalescence of hydrogen bubbles, while the thickness of the copper foam increases with decreasing pressure. Also, the walls around the pores on the copper foam consist of copper dendrites, and the copper dendrites are made up of copper grains with sizes less than 1 l.tm. The average sizes of the copper grains decrease with increasing system pressure. It has been demonstrated that copper foams with controllable 3D structure formed by electrodeposition at different pressures are comparable to those obtained by electrodeposition at normal pressure in the presence of specific additives.展开更多
A widely tunable microwave photonic notch filter with adjustable bandwidth based on multi-wavelength fiber laser is proposed and demonstrated. The multi-wavelength fiber laser generates the multi-taps of the microwave...A widely tunable microwave photonic notch filter with adjustable bandwidth based on multi-wavelength fiber laser is proposed and demonstrated. The multi-wavelength fiber laser generates the multi-taps of the microwave photonic filter （MPF）. In order to obtain notch frequency response, a Fourier-domain optical processor （FD-OP） is introduced to con- trol the amplitude and phase of the optical carrier and phase modulation sidebands. By adjusting the polarization con- troller （PC）, different numbers of taps are got, such as 6, 8, 10 and 121 And the wavelength-spacing of the multi-wavelength laser is 0.4 nm. The bandwidth of the notch filter is changed by adjusting the number of taps and the corresponding bandwidths are 4.41 GHz, 3.30 GHz, 2.64 GHz and 2.19 GHz, respectively. With the additional phase shift introduced by FD-OP, the notch position is continuously ttmed in the whole free spectral range （FSR） of 27.94 GHz. The center frequency of the notch filter can be continuously tuned from 13.97 GHz to 41.91 GHz.展开更多
基金National Natural Science Foundation of China(No.62303107)Fundamental Research Funds for the Central Universities,China(Nos.2232022G-09 and 2232021D-38)Shanghai Sailing Program,China(No.21YF1400100)。
文摘An alternating current(AC)microgrid is a system that integrates renewable power,power converters,controllers and loads.Hierarchical control can manage the frequency of the microgrid to prevent imbalance and collapse of the system.The existing frequency control methods use traditional proportion integration(PI)controllers,which cannot adjust PI parameters in real-time to respond to the status changes of the system.Hierarchical control driven by fuzzy logic allows real-time adjustment of the PI parameters and the method used a two-layer control structure.The primary control used droop control to adjust power distribution,and fuzzy logic was used in the voltage loop of the primary control.The secondary control was added to make up for frequency deviation caused by droop control,and fuzzy logic was used in the secondary frequency control to deal with the dynamic change of frequency caused by the disturbances of loads.The proposed method was simulated in Matlab/Simulink.In the primary control,the proposed method reduced the total harmonic distortion(THD)of two cycles of the output voltage from 4.19%to 3.89%;in the secondary control,the proposed method reduced the frequency fluctuation of the system by about 0.03 Hz and 0.04 Hz when the load was increased and decreased,respectively.The results show that the proposed methods have a better effect on frequency maintenance and voltage control of the AC microgrid.
文摘UV wavelength auto-tuned tuned output system is realized by the difference method. Controlled by the microprocessor, output wavelength auto- tracking is achieved.Besides, equipment self-checking auto-positioning and temperature correct are realized,The wavelength tuned output efficiency in the experiment is better than 97 %.
文摘Subcellular localization and translation of messenger RNAs are essential for the regulation of neuronal development and synaptic function. As post-transcriptional regulators, microRNAs （miRNAs） have been emerging as central players in the development and maturation of the nervous system. Recent discoveries reveal the critical functions of miRNAs in the axon of neurons via multiple pathways of molecular regulation. Here, we introduce methods for isolating axonal miRNAs and review recent findings on the localization and function as well as regulatory mechanism of axonal miRNAs during axon development.
文摘The cohort intelligence （CI） method has recently evolved as an optimization method based on artificial intelligence. We use the CI method for the first time to optimize the parameters of the fractional proportional- integral-derivative （PID） controller. The performance of the CI method in designing the fractional PID controller was validated and compared with those of some other popular algorithms such as particle swarm optimization, the genetic algorithm, and the improved electromagnetic algorithm. The CI method yielded improved solutions in terms of the cost function, computing time, and function evaluations in comparison with the other three algorithms. In addition, the standard deviations of the CI method demonstrated the robustness of the proposed algorithm in solving control problems.
基金supported by the National Natural Science Foundation of China (20776004)the Program for New Century Excellent Talents in University (NCET-08-0710)
文摘Three-dimensional （3D） copper foams have been formed by electrodeposition at different nitrogen pressures and examined by scanning electron microscopy. The results indicate that an increase in system pressure leads to a decrease of the pore size of the copper foam due to the suppressed coalescence of hydrogen bubbles, while the thickness of the copper foam increases with decreasing pressure. Also, the walls around the pores on the copper foam consist of copper dendrites, and the copper dendrites are made up of copper grains with sizes less than 1 l.tm. The average sizes of the copper grains decrease with increasing system pressure. It has been demonstrated that copper foams with controllable 3D structure formed by electrodeposition at different pressures are comparable to those obtained by electrodeposition at normal pressure in the presence of specific additives.
基金supported by the National Natural Science Foundation of China(No.11444001)the Municipal Natural Science Foundation of Tianjin in China(No.14JCYBJC16500)
文摘A widely tunable microwave photonic notch filter with adjustable bandwidth based on multi-wavelength fiber laser is proposed and demonstrated. The multi-wavelength fiber laser generates the multi-taps of the microwave photonic filter （MPF）. In order to obtain notch frequency response, a Fourier-domain optical processor （FD-OP） is introduced to con- trol the amplitude and phase of the optical carrier and phase modulation sidebands. By adjusting the polarization con- troller （PC）, different numbers of taps are got, such as 6, 8, 10 and 121 And the wavelength-spacing of the multi-wavelength laser is 0.4 nm. The bandwidth of the notch filter is changed by adjusting the number of taps and the corresponding bandwidths are 4.41 GHz, 3.30 GHz, 2.64 GHz and 2.19 GHz, respectively. With the additional phase shift introduced by FD-OP, the notch position is continuously ttmed in the whole free spectral range （FSR） of 27.94 GHz. The center frequency of the notch filter can be continuously tuned from 13.97 GHz to 41.91 GHz.
