The effects of color centers＇ absorption on fibers and interferometric fiber optical gyroscopes（IFOGs） are studied in the paper. The irradiation induced attenuation（RIA） spectra of three types of polarization-mai...The effects of color centers＇ absorption on fibers and interferometric fiber optical gyroscopes（IFOGs） are studied in the paper. The irradiation induced attenuation（RIA） spectra of three types of polarization-maintaining fibers（PMFs）, i.e.,P-doped, Ge-doped, and pure silica, irradiated at 100 Gy and 1000 Gy are measured in a wavelength range from 1100 nm to1600 nm and decomposed according to the Gaussian model. The relationship of the color centers absorption intensity with radiation dose is investigated based on a power model. Furthermore, the effects of all color centers＇ absorption on RIA and mean wavelength shifts（MWS） at 1300 nm and 1550 nm are discussed respectively. Finally, the random walk coefficient（RWC） degradation induced from RIA and the scale factor error induced by MWS of the IFOG are simulated and tested at a wavelength of 1300 nm. This research will contribute to the applications of the fibers in radiation environments.展开更多
四川省宝兴县具有海拔高差悬殊、气候多样、动植物资源和森林资源丰富等特点,是世界自然遗产大熊猫栖息地和长江上游生态屏障的重要组成部分。基于2001—2020年MODIS遥感反演数据,采用Sen趋势分析、Mann-Kendall趋势显著性分析和重心转...四川省宝兴县具有海拔高差悬殊、气候多样、动植物资源和森林资源丰富等特点,是世界自然遗产大熊猫栖息地和长江上游生态屏障的重要组成部分。基于2001—2020年MODIS遥感反演数据,采用Sen趋势分析、Mann-Kendall趋势显著性分析和重心转移分析等方法,研究宝兴县植被净初级生产力(NPP)的空间分布特征表明:(1)宝兴县森林植被NPP整体呈上升趋势,其中常绿针叶林与落叶针叶林的NPP分别以5.7 g C·m^(2)·a和10.9 g C·m^(2)·a的速度增长。而常绿阔叶林植被NPP下降幅度尤为显著,平均减少19.0 g C·m^(2)·a,说明宝兴县森林生态系统碳汇能力总体增强;(2)宝兴县森林生态系统在过去20年内保持相对稳定,植被NPP高值区主要集中于南部和东南部山区,植被生态功能呈恢复态势,植被NPP空间重心整体稳定,仅在2012年前后出现显著偏移,但部分林型更替与生态干扰对局部区域功能仍具有重要影响宝兴县常绿阔叶林多年平均植被NPP最高;(3)宝兴县植被NPP空间格局演化稳定,具有高植被NPP区向南部山区集中,暖色区域扩展、低值区收缩等生态功能恢复趋势,说明研究期内植被生产力整体向好;植被NPP空间重心具有局部年份偏移,但整体年均位移小、路径波动有限等特点,表明该区域森林生态系统结构稳定性较强。研究结果对宝兴县混交林与优势针叶林的可持续经营、大熊猫栖息地恢复与重建,林分结构调整与功能精准提升,以及森林生态系统碳汇能力持续增强等具有重要意义。展开更多
基金supported by the Scientific Research Foundation for the Returned Overseas Chinese Scholars,State Education Ministry,China
文摘The effects of color centers＇ absorption on fibers and interferometric fiber optical gyroscopes（IFOGs） are studied in the paper. The irradiation induced attenuation（RIA） spectra of three types of polarization-maintaining fibers（PMFs）, i.e.,P-doped, Ge-doped, and pure silica, irradiated at 100 Gy and 1000 Gy are measured in a wavelength range from 1100 nm to1600 nm and decomposed according to the Gaussian model. The relationship of the color centers absorption intensity with radiation dose is investigated based on a power model. Furthermore, the effects of all color centers＇ absorption on RIA and mean wavelength shifts（MWS） at 1300 nm and 1550 nm are discussed respectively. Finally, the random walk coefficient（RWC） degradation induced from RIA and the scale factor error induced by MWS of the IFOG are simulated and tested at a wavelength of 1300 nm. This research will contribute to the applications of the fibers in radiation environments.
文摘四川省宝兴县具有海拔高差悬殊、气候多样、动植物资源和森林资源丰富等特点,是世界自然遗产大熊猫栖息地和长江上游生态屏障的重要组成部分。基于2001—2020年MODIS遥感反演数据,采用Sen趋势分析、Mann-Kendall趋势显著性分析和重心转移分析等方法,研究宝兴县植被净初级生产力(NPP)的空间分布特征表明:(1)宝兴县森林植被NPP整体呈上升趋势,其中常绿针叶林与落叶针叶林的NPP分别以5.7 g C·m^(2)·a和10.9 g C·m^(2)·a的速度增长。而常绿阔叶林植被NPP下降幅度尤为显著,平均减少19.0 g C·m^(2)·a,说明宝兴县森林生态系统碳汇能力总体增强;(2)宝兴县森林生态系统在过去20年内保持相对稳定,植被NPP高值区主要集中于南部和东南部山区,植被生态功能呈恢复态势,植被NPP空间重心整体稳定,仅在2012年前后出现显著偏移,但部分林型更替与生态干扰对局部区域功能仍具有重要影响宝兴县常绿阔叶林多年平均植被NPP最高;(3)宝兴县植被NPP空间格局演化稳定,具有高植被NPP区向南部山区集中,暖色区域扩展、低值区收缩等生态功能恢复趋势,说明研究期内植被生产力整体向好;植被NPP空间重心具有局部年份偏移,但整体年均位移小、路径波动有限等特点,表明该区域森林生态系统结构稳定性较强。研究结果对宝兴县混交林与优势针叶林的可持续经营、大熊猫栖息地恢复与重建,林分结构调整与功能精准提升,以及森林生态系统碳汇能力持续增强等具有重要意义。
