基于全球定位系统的多路径反射(GPS-MR)测量技术的潮位监测已经成为验潮站监测的有效补充,但较少学者利用GPS-MR反演潮位进行潮汐调和分析和预报。为了验证GPS-MR潮位预报的可能性,利用美国大陆板块边缘观测组织(PBO)提供的GPS信噪比数...基于全球定位系统的多路径反射(GPS-MR)测量技术的潮位监测已经成为验潮站监测的有效补充,但较少学者利用GPS-MR反演潮位进行潮汐调和分析和预报。为了验证GPS-MR潮位预报的可能性,利用美国大陆板块边缘观测组织(PBO)提供的GPS信噪比数据进行潮位反演,将该反演结果重采样为等间隔潮位序列,利用该潮位序列计算各分潮的调和常数,并进行潮汐预报。通过与美国海洋与大气局(NOAA)提供的实测验潮数据进行对比,结果表明:GPS-MR反演潮位与验潮站实测潮位具有一致性,相关系数为0.94,均方根误差为0.16 m;经样条函数拟合后的1 h GPS-MR潮位序列预测结果同采用验潮站潮位进行预测结果精度相当,同验潮站实测潮位的均方根误差为0.14 m,相关系数为0.97。可见,利用GPS-MR技术进行潮位监测和预报是可行的。展开更多
积雪在全球水循环中扮演着重要角色,同时高精度雪深资料也是气候研究的基础数据。目前陆基GPS-R(Global Position System Reflectometry)遥感技术监测地表积雪厚度已成为热点研究之一,其可用来弥补常规测量手段的时空分辨率不足等缺陷...积雪在全球水循环中扮演着重要角色,同时高精度雪深资料也是气候研究的基础数据。目前陆基GPS-R(Global Position System Reflectometry)遥感技术监测地表积雪厚度已成为热点研究之一,其可用来弥补常规测量手段的时空分辨率不足等缺陷。针对测量区域、数据筛选以及有无积雪的信噪比与雪深变化的定量关系等问题,文章结合瑞典KIRU跟踪站的GPS L1C/A观测数据和Lomb-Scargle谱分析法,求解了各单颗卫星的雪深估测值,并计算每日的雪深均值。基于此,反演了连续6个月的逐日雪深序列,最后将其与实测雪深进行多角度的对比分析。结果表明,GPS L1C/A可适用于反演监测地表雪深数据,反演值与实测值之间的整体趋势具有弱偏差和强相关。其中,两者的相关系数为0.96,均方根误差仅4.5 cm,说明陆基CORS测站在一定程度上可拓展GNSS在陆地遥感领域的应用范围。展开更多
针对大地测量型GNSS接收机获取的信噪比(Signal to Noise Ratio,SNR)观测值存在趋势项分离不佳和信号叠加干涉的问题,融合自适应噪声完备集合鲁棒局部均值分解方法对原始SNR信号进行分解,有效分离SNR观测值中的趋势项并提取相应的潮位信...针对大地测量型GNSS接收机获取的信噪比(Signal to Noise Ratio,SNR)观测值存在趋势项分离不佳和信号叠加干涉的问题,融合自适应噪声完备集合鲁棒局部均值分解方法对原始SNR信号进行分解,有效分离SNR观测值中的趋势项并提取相应的潮位信号,以布设在美国华盛顿州星期五海港岸边的SC02测站为例,利用实测数据反演潮位变化并与传统的低阶多项式拟合方法进行对比分析。结果表明,融合CERLMDAN方法的反演结果的均方根误差(Root Mean Square Error,RMSE)、相关系数分别为0.56 m和0.97,相比于传统方法的反演精度提升了33.7%。展开更多
Bi12O17Br2and Bi4O5Br2visible‐light driven photocatalysts,were respectively fabricated by hydrothermal and room‐temperature deposition methods with the use of BiBr3and NaOH as precursors.Both Bi12O17Br2and Bi4O5Br2w...Bi12O17Br2and Bi4O5Br2visible‐light driven photocatalysts,were respectively fabricated by hydrothermal and room‐temperature deposition methods with the use of BiBr3and NaOH as precursors.Both Bi12O17Br2and Bi4O5Br2were composed of irregular nanosheets.The Bi4O5Br2nanosheets exhibited high and stable visible‐light photocatalytic efficiency for ppb‐level NO removal.The performance of Bi4O5Br2was markedly higher than that of the Bi12O17Br2nanosheets.The hydroxyl radical(?OH)was determined to be the main reactive oxygen species for the photo‐degradation processes of both Bi12O17Br2and Bi4O5Br2.However,in situ diffuse reflectance infrared Fourier transform spectroscopy analysis revealed that Bi12O17Br2and Bi4O5Br2featured different conversion pathways for visible light driven photocatalytic NO oxidation.The excellent photocatalytic activity of Bi4O5Br2resulted from a high surface area and large pore volumes,which facilitated the transport of reactants and intermediate products,and provided more active sites for photochemical reaction.Furthermore,the Bi4O5Br2nanosheets produced more?OH and presented stronger valence band holeoxidation.In addition,the oxygen atoms of NO could insert into oxygen‐vacancies of Bi4O5Br2,whichprovided more active sites for the reaction.This work gives insight into the photocatalytic pollutant‐degradation mechanism of bismuth oxyhalide.展开更多
文摘基于全球定位系统的多路径反射(GPS-MR)测量技术的潮位监测已经成为验潮站监测的有效补充,但较少学者利用GPS-MR反演潮位进行潮汐调和分析和预报。为了验证GPS-MR潮位预报的可能性,利用美国大陆板块边缘观测组织(PBO)提供的GPS信噪比数据进行潮位反演,将该反演结果重采样为等间隔潮位序列,利用该潮位序列计算各分潮的调和常数,并进行潮汐预报。通过与美国海洋与大气局(NOAA)提供的实测验潮数据进行对比,结果表明:GPS-MR反演潮位与验潮站实测潮位具有一致性,相关系数为0.94,均方根误差为0.16 m;经样条函数拟合后的1 h GPS-MR潮位序列预测结果同采用验潮站潮位进行预测结果精度相当,同验潮站实测潮位的均方根误差为0.14 m,相关系数为0.97。可见,利用GPS-MR技术进行潮位监测和预报是可行的。
文摘积雪在全球水循环中扮演着重要角色,同时高精度雪深资料也是气候研究的基础数据。目前陆基GPS-R(Global Position System Reflectometry)遥感技术监测地表积雪厚度已成为热点研究之一,其可用来弥补常规测量手段的时空分辨率不足等缺陷。针对测量区域、数据筛选以及有无积雪的信噪比与雪深变化的定量关系等问题,文章结合瑞典KIRU跟踪站的GPS L1C/A观测数据和Lomb-Scargle谱分析法,求解了各单颗卫星的雪深估测值,并计算每日的雪深均值。基于此,反演了连续6个月的逐日雪深序列,最后将其与实测雪深进行多角度的对比分析。结果表明,GPS L1C/A可适用于反演监测地表雪深数据,反演值与实测值之间的整体趋势具有弱偏差和强相关。其中,两者的相关系数为0.96,均方根误差仅4.5 cm,说明陆基CORS测站在一定程度上可拓展GNSS在陆地遥感领域的应用范围。
文摘针对大地测量型GNSS接收机获取的信噪比(Signal to Noise Ratio,SNR)观测值存在趋势项分离不佳和信号叠加干涉的问题,融合自适应噪声完备集合鲁棒局部均值分解方法对原始SNR信号进行分解,有效分离SNR观测值中的趋势项并提取相应的潮位信号,以布设在美国华盛顿州星期五海港岸边的SC02测站为例,利用实测数据反演潮位变化并与传统的低阶多项式拟合方法进行对比分析。结果表明,融合CERLMDAN方法的反演结果的均方根误差(Root Mean Square Error,RMSE)、相关系数分别为0.56 m和0.97,相比于传统方法的反演精度提升了33.7%。
基金supported by the National Natural Science Foundation of China(51708078,21576034)Chongqing Postdoctoral Science Foundation funded project(Xm2016027)the Innovative Research Team of Chongqing(CXTDG201602014,CXTDX201601016)~~
文摘Bi12O17Br2and Bi4O5Br2visible‐light driven photocatalysts,were respectively fabricated by hydrothermal and room‐temperature deposition methods with the use of BiBr3and NaOH as precursors.Both Bi12O17Br2and Bi4O5Br2were composed of irregular nanosheets.The Bi4O5Br2nanosheets exhibited high and stable visible‐light photocatalytic efficiency for ppb‐level NO removal.The performance of Bi4O5Br2was markedly higher than that of the Bi12O17Br2nanosheets.The hydroxyl radical(?OH)was determined to be the main reactive oxygen species for the photo‐degradation processes of both Bi12O17Br2and Bi4O5Br2.However,in situ diffuse reflectance infrared Fourier transform spectroscopy analysis revealed that Bi12O17Br2and Bi4O5Br2featured different conversion pathways for visible light driven photocatalytic NO oxidation.The excellent photocatalytic activity of Bi4O5Br2resulted from a high surface area and large pore volumes,which facilitated the transport of reactants and intermediate products,and provided more active sites for photochemical reaction.Furthermore,the Bi4O5Br2nanosheets produced more?OH and presented stronger valence band holeoxidation.In addition,the oxygen atoms of NO could insert into oxygen‐vacancies of Bi4O5Br2,whichprovided more active sites for the reaction.This work gives insight into the photocatalytic pollutant‐degradation mechanism of bismuth oxyhalide.
