The objective of this study is to improve the performance of semi-empirical radar backscatter models, which are mainly used in microwave remote sensing (Oh 1992, Oh 2004 and Dubois). The study is based on satellite an...The objective of this study is to improve the performance of semi-empirical radar backscatter models, which are mainly used in microwave remote sensing (Oh 1992, Oh 2004 and Dubois). The study is based on satellite and ground data collected on bare soil surfaces during the Multispectral Crop Monitoring experimental campaign of the CESBIO laboratory in 2010 over an agricultural region in southwestern France. The dataset covers a wide range of soil (viewing top soil moisture, surface roughness and texture) and satellite (at different frequencies: X-, C- and L-bands, and different incidence angles: 24.3° to 53.3°) configurations. The proposed methodology consists in identifying and correcting the residues of the models, depending on the surface properties (roughness, moisture, texture) and/or sensor characteristics (frequency, incidence angle). Finally, one model has been retained for each frequency domain. Results show that the enhancements of the models significantly increase the simulation performances. The coefficient of correlation increases of 23% in mean and the simulation errors (RMSE) are reduced to below 2 dB (at the X and C-bands) and to 1 dB at the L-band, compared to the initial models. At the X- and C-bands, the best performances of the modified models are provided by Dubois, whereas Oh 2004 is more suitable for the L-band (r is equal to 0.69, 0.65 and 0.85). Moreover, the modified models of Oh 1992 and 2004 and Dubois, developed in this study, offer a wider domain of validity than the initial formalism and increase the capabilities of retrieving the backscattering signal in view of applications of such approaches to stronglycontrasted agricultural surface states.展开更多
随着光通信技术的发展,各种现有的单模光纤已不能满足宽带光传输密集波分复用(DWDM)系统传输的要求,S C L三波段传输新型单模光纤是在1460～1625nm的波长范围内具有足够大的色散以抑制四波混频效应、交叉相位调制等非线性效应,又使色散...随着光通信技术的发展,各种现有的单模光纤已不能满足宽带光传输密集波分复用(DWDM)系统传输的要求,S C L三波段传输新型单模光纤是在1460～1625nm的波长范围内具有足够大的色散以抑制四波混频效应、交叉相位调制等非线性效应,又使色散及斜率尽可能低,从而使色散管理成本降到最低的新型单模光纤.我们设计和计算了这种新型的光纤的结构并对其性能参数进行了分析和讨论.展开更多
以奥地利黑麦(S eca le cerea le L.)为试验材料,通过G iem sa C-分带对其进行了细胞学鉴定、染色体核型与C-带分析。结果表明,奥地利黑麦体细胞染色体为14条,花粉母细胞减数分裂中期Ⅰ染色体形成7个二价体,其核型公式为2n=2x=14=10m+2s...以奥地利黑麦(S eca le cerea le L.)为试验材料,通过G iem sa C-分带对其进行了细胞学鉴定、染色体核型与C-带分析。结果表明,奥地利黑麦体细胞染色体为14条,花粉母细胞减数分裂中期Ⅰ染色体形成7个二价体,其核型公式为2n=2x=14=10m+2sm+2m(SAT)。通过C-分带将奥地利黑麦1R^7R的7条染色体区分开来,其C-带带型公式为2n=14=2C+I+T+2C+T+4I+T+2C+I+T++2T+2ST。奥地利黑麦除2R和4R长臂近端部约1/4处有带且7R无中间带外,其余带型与黑麦标准C-分带带型基本一致。展开更多
文摘The objective of this study is to improve the performance of semi-empirical radar backscatter models, which are mainly used in microwave remote sensing (Oh 1992, Oh 2004 and Dubois). The study is based on satellite and ground data collected on bare soil surfaces during the Multispectral Crop Monitoring experimental campaign of the CESBIO laboratory in 2010 over an agricultural region in southwestern France. The dataset covers a wide range of soil (viewing top soil moisture, surface roughness and texture) and satellite (at different frequencies: X-, C- and L-bands, and different incidence angles: 24.3° to 53.3°) configurations. The proposed methodology consists in identifying and correcting the residues of the models, depending on the surface properties (roughness, moisture, texture) and/or sensor characteristics (frequency, incidence angle). Finally, one model has been retained for each frequency domain. Results show that the enhancements of the models significantly increase the simulation performances. The coefficient of correlation increases of 23% in mean and the simulation errors (RMSE) are reduced to below 2 dB (at the X and C-bands) and to 1 dB at the L-band, compared to the initial models. At the X- and C-bands, the best performances of the modified models are provided by Dubois, whereas Oh 2004 is more suitable for the L-band (r is equal to 0.69, 0.65 and 0.85). Moreover, the modified models of Oh 1992 and 2004 and Dubois, developed in this study, offer a wider domain of validity than the initial formalism and increase the capabilities of retrieving the backscattering signal in view of applications of such approaches to stronglycontrasted agricultural surface states.
文摘随着光通信技术的发展,各种现有的单模光纤已不能满足宽带光传输密集波分复用(DWDM)系统传输的要求,S C L三波段传输新型单模光纤是在1460～1625nm的波长范围内具有足够大的色散以抑制四波混频效应、交叉相位调制等非线性效应,又使色散及斜率尽可能低,从而使色散管理成本降到最低的新型单模光纤.我们设计和计算了这种新型的光纤的结构并对其性能参数进行了分析和讨论.
文摘以奥地利黑麦(S eca le cerea le L.)为试验材料,通过G iem sa C-分带对其进行了细胞学鉴定、染色体核型与C-带分析。结果表明,奥地利黑麦体细胞染色体为14条,花粉母细胞减数分裂中期Ⅰ染色体形成7个二价体,其核型公式为2n=2x=14=10m+2sm+2m(SAT)。通过C-分带将奥地利黑麦1R^7R的7条染色体区分开来,其C-带带型公式为2n=14=2C+I+T+2C+T+4I+T+2C+I+T++2T+2ST。奥地利黑麦除2R和4R长臂近端部约1/4处有带且7R无中间带外,其余带型与黑麦标准C-分带带型基本一致。
