We demonstrate the transmission of a microwave frequency signal at 10 GHz over a 112-km urban fiber link based on a novel simple-architecture electronic phase compensation system.The key element of the system is the l...We demonstrate the transmission of a microwave frequency signal at 10 GHz over a 112-km urban fiber link based on a novel simple-architecture electronic phase compensation system.The key element of the system is the low noise frequency divider by 4 to differentiate the frequency of the forward signal from that of the backward one,thus suppressing the effect of Brillouin backscattering and parasitic reflection along the link.In terms of overlapping Allan deviation,the frequency transfer instability of 4.2×10-15 at 1-s integration time and 1.6×10-18 at one-day integration time was achieved.In addition,its sensitivity to the polarization mode dispersion in fiber is analyzed by comparing the results with and without laser polarization scrambling.Generally,with simplicity and robustness,the system can offer great potentials in constructing cascaded frequency transfer system and facilitate the building of fiber-based microwave transfer network.展开更多
为了节省棉花打顶用工,达到轻简化栽培目的。通过以中熟陆地棉品系豫宛199为材料,在豫南植棉区进行新型化学打顶剂打顶试验,研究打顶剂不同喷施时间、不同剂量对棉花顶端控制及产量的影响。结果表明:两个喷施时期的3种剂量均可控制棉花...为了节省棉花打顶用工,达到轻简化栽培目的。通过以中熟陆地棉品系豫宛199为材料,在豫南植棉区进行新型化学打顶剂打顶试验,研究打顶剂不同喷施时间、不同剂量对棉花顶端控制及产量的影响。结果表明:两个喷施时期的3种剂量均可控制棉花顶端生长速度和增加籽棉产量,8月3日喷施的对棉花顶端控制效果好于8月8日,株高新增量随剂量的升高而降低,果枝数新增量剂量之间差异不明显,籽棉产量以处理3比人工打顶对照增产显著。对于豫南植棉区的中熟棉,在8月3日使用新型化学打顶剂750 m L/hm2进行打顶可以有效抑制棉花顶部生长,控制效果接近人工打顶。展开更多
基金National Natural Science Foundation of China(Grant Nos.61825505,91536217,and 61127901).
文摘We demonstrate the transmission of a microwave frequency signal at 10 GHz over a 112-km urban fiber link based on a novel simple-architecture electronic phase compensation system.The key element of the system is the low noise frequency divider by 4 to differentiate the frequency of the forward signal from that of the backward one,thus suppressing the effect of Brillouin backscattering and parasitic reflection along the link.In terms of overlapping Allan deviation,the frequency transfer instability of 4.2×10-15 at 1-s integration time and 1.6×10-18 at one-day integration time was achieved.In addition,its sensitivity to the polarization mode dispersion in fiber is analyzed by comparing the results with and without laser polarization scrambling.Generally,with simplicity and robustness,the system can offer great potentials in constructing cascaded frequency transfer system and facilitate the building of fiber-based microwave transfer network.
文摘为了节省棉花打顶用工,达到轻简化栽培目的。通过以中熟陆地棉品系豫宛199为材料,在豫南植棉区进行新型化学打顶剂打顶试验,研究打顶剂不同喷施时间、不同剂量对棉花顶端控制及产量的影响。结果表明:两个喷施时期的3种剂量均可控制棉花顶端生长速度和增加籽棉产量,8月3日喷施的对棉花顶端控制效果好于8月8日,株高新增量随剂量的升高而降低,果枝数新增量剂量之间差异不明显,籽棉产量以处理3比人工打顶对照增产显著。对于豫南植棉区的中熟棉,在8月3日使用新型化学打顶剂750 m L/hm2进行打顶可以有效抑制棉花顶部生长,控制效果接近人工打顶。
