An accurate and fast three-step self-calibrating generalized phase-shifting interferomertry(SGPSI) is proposed. In this approach, two new phase-shifting signals are constructed by the difference interferograms normali...An accurate and fast three-step self-calibrating generalized phase-shifting interferomertry(SGPSI) is proposed. In this approach, two new phase-shifting signals are constructed by the difference interferograms normalization and noise suppressing, then the unknown phase shift between the two difference phase-shifting signals is estimated quickly through searching the minimum coefficient of variation of the modulation amplitude, a limited number of pixels are selected to participate in the search process to further save time, and finally the phase is reconstructed through the searched phase shift. Through the reconstruction of phase map by the simulation and experiment, and the comparison with several mature algorithms, the good performance of the proposed algorithm is proved, and it eliminates the limitation of requiring more than three phase-shifting interferograms for high-precision SGPSI. We expect this method to be widely used in the future.展开更多
基于移相加占空比控制策略的三有源桥TAB(triple active bridge)DC-DC变换器具有效率高和软开关范围可扩展等优点,但其小信号建模过程复杂、闭环控制环路参数整定困难。针对该问题,提出1种TAB工作在移相加占空比控制下的全阶连续广义状...基于移相加占空比控制策略的三有源桥TAB(triple active bridge)DC-DC变换器具有效率高和软开关范围可扩展等优点,但其小信号建模过程复杂、闭环控制环路参数整定困难。针对该问题,提出1种TAB工作在移相加占空比控制下的全阶连续广义状态平均建模和PI控制器设计方法。首先,分析TAB的运行原理和Y型等效结构;然后,结合移相加占空比控制的特点和交流方波源等效方法,推导出TAB的广义状态空间平均模型;接着,在推得模型的基础上求得输入到输出的传递函数,设计出PI控制器参数。最后,结合数字仿真及样机实验验证了所提方法的正确性及有效性。展开更多
We present a theoretical investigation of the multiphoton resonance dynamics in the high-order-harmonic generation(HHG)process driven by a strong driving continuous wave(CW)field along with a weak control harmonic fie...We present a theoretical investigation of the multiphoton resonance dynamics in the high-order-harmonic generation(HHG)process driven by a strong driving continuous wave(CW)field along with a weak control harmonic field.The Floquet theorem is employed to provide a nonperturbative and exact treatment of the interaction between a quantum system and the combined laser field.Multiple multiphoton-transition paths for the harmonic emission are coherently summed.The phase information about paths can be extracted via the Fourier transform analysis of the harmonic signals which oscillate as a function of the relative phase between driving and control fields.Phase jumps are observed when sweeping across the resonance by varying the frequency or intensity of the driving field.The phase variation as a function of driving frequency at a fixed intensity and as a function of the intensity at a fixed driving frequency allows us to determine the intensity dependence of the transition energy of quantum systems.展开更多
为了抑制机车四象限脉冲整流器在网侧产生的高频谐波,防止车网发生高次谐波共振,提出一种基于二阶广义积分器锁相环SOGI-PLL(second-order generalized integral phase-locked loop)载波移相控制策略。将锁相环输出的电网相位作为同步...为了抑制机车四象限脉冲整流器在网侧产生的高频谐波,防止车网发生高次谐波共振,提出一种基于二阶广义积分器锁相环SOGI-PLL(second-order generalized integral phase-locked loop)载波移相控制策略。将锁相环输出的电网相位作为同步基准信号,针对网压频率异常波动,快速同步校正PWM载波周期,保证了各单元之间移相角的准确性,获得最优谐波对消效果。同时,该策略对电网谐波和幅值异常跳变不敏感,具有良好的抗干扰性和自适应性。最后通过半实物仿真和地面联调试验,验证了该策略的可行性和对谐波抑制的有效性。展开更多
A new method of fabricating multiple-phase-shifts fiber Bragg grating by CGHsis proposed . The authors present an example of such CGH by which a section multiple-phase-shiftefiber Bragg grating with twoπ/2 phase shif...A new method of fabricating multiple-phase-shifts fiber Bragg grating by CGHsis proposed . The authors present an example of such CGH by which a section multiple-phase-shiftefiber Bragg grating with twoπ/2 phase shifts and grating length L = 21.2 μm was produced. Theauthors describe the production process and finally give an example of a reconstructed fiber gratingwith two phase-shifts.展开更多
基金Project supported by the National Natural Science Foundation of China (Grant No. 61905039)Jilin Scientific and Technological Development Program, China (Grant No. 20190701018GH)+1 种基金Education Department of Jilin Province, China (Grant No. JJKH20190691KJ)State Key Laboratory of Applied Optics.
文摘An accurate and fast three-step self-calibrating generalized phase-shifting interferomertry(SGPSI) is proposed. In this approach, two new phase-shifting signals are constructed by the difference interferograms normalization and noise suppressing, then the unknown phase shift between the two difference phase-shifting signals is estimated quickly through searching the minimum coefficient of variation of the modulation amplitude, a limited number of pixels are selected to participate in the search process to further save time, and finally the phase is reconstructed through the searched phase shift. Through the reconstruction of phase map by the simulation and experiment, and the comparison with several mature algorithms, the good performance of the proposed algorithm is proved, and it eliminates the limitation of requiring more than three phase-shifting interferograms for high-precision SGPSI. We expect this method to be widely used in the future.
文摘基于移相加占空比控制策略的三有源桥TAB(triple active bridge)DC-DC变换器具有效率高和软开关范围可扩展等优点,但其小信号建模过程复杂、闭环控制环路参数整定困难。针对该问题,提出1种TAB工作在移相加占空比控制下的全阶连续广义状态平均建模和PI控制器设计方法。首先,分析TAB的运行原理和Y型等效结构;然后,结合移相加占空比控制的特点和交流方波源等效方法,推导出TAB的广义状态空间平均模型;接着,在推得模型的基础上求得输入到输出的传递函数,设计出PI控制器参数。最后,结合数字仿真及样机实验验证了所提方法的正确性及有效性。
基金Project supported by the National Natural Science Foundation of China(Grant Nos.11504288,11534008,and 91536115)the Fundamental Research Funds for the Central Universities of China.
文摘We present a theoretical investigation of the multiphoton resonance dynamics in the high-order-harmonic generation(HHG)process driven by a strong driving continuous wave(CW)field along with a weak control harmonic field.The Floquet theorem is employed to provide a nonperturbative and exact treatment of the interaction between a quantum system and the combined laser field.Multiple multiphoton-transition paths for the harmonic emission are coherently summed.The phase information about paths can be extracted via the Fourier transform analysis of the harmonic signals which oscillate as a function of the relative phase between driving and control fields.Phase jumps are observed when sweeping across the resonance by varying the frequency or intensity of the driving field.The phase variation as a function of driving frequency at a fixed intensity and as a function of the intensity at a fixed driving frequency allows us to determine the intensity dependence of the transition energy of quantum systems.
文摘为了抑制机车四象限脉冲整流器在网侧产生的高频谐波,防止车网发生高次谐波共振,提出一种基于二阶广义积分器锁相环SOGI-PLL(second-order generalized integral phase-locked loop)载波移相控制策略。将锁相环输出的电网相位作为同步基准信号,针对网压频率异常波动,快速同步校正PWM载波周期,保证了各单元之间移相角的准确性,获得最优谐波对消效果。同时,该策略对电网谐波和幅值异常跳变不敏感,具有良好的抗干扰性和自适应性。最后通过半实物仿真和地面联调试验,验证了该策略的可行性和对谐波抑制的有效性。
文摘A new method of fabricating multiple-phase-shifts fiber Bragg grating by CGHsis proposed . The authors present an example of such CGH by which a section multiple-phase-shiftefiber Bragg grating with twoπ/2 phase shifts and grating length L = 21.2 μm was produced. Theauthors describe the production process and finally give an example of a reconstructed fiber gratingwith two phase-shifts.
