Soil salinity is one of the serious environmental problems ravaging the soils of arid and semi-arid region, thereby affecting crop productivity, livestock, increase level of poverty and land degradation. Hyperspectral...Soil salinity is one of the serious environmental problems ravaging the soils of arid and semi-arid region, thereby affecting crop productivity, livestock, increase level of poverty and land degradation. Hyperspectral remote sensing is one of the important techniques to monitor, analyze and estimate the extent and severity of soil salt at regional to local scale. In this study we develop a model for the detection of salt-affected soils in arid and semi-arid regions and in our case it’s Ghannouch, Gabes. We used fourteen spectral indices and six spectral bands extracted from the Hyperion data. Linear Spectral Unmixing technique (LSU) was used in this study to improve the correlation between electrical conductivity and spectral indices and then improve the prediction of soil salinity as well as the reliability of the model. To build the model a multiple linear regression analysis was applied using the best correlated indices. The standard error of the estimate is about 1.57 mS/cm. The results of this study show that hyperion data is accurate and suitable for differentiating between categories of salt affected soils. The generated model can be used for management strategies in the future.展开更多
This paper is an attempt to introduce the role of earth observation technology and a type of digital earth processing in mineral resources exploration and assessment.The sub-pixel distribution and quantity of alterati...This paper is an attempt to introduce the role of earth observation technology and a type of digital earth processing in mineral resources exploration and assessment.The sub-pixel distribution and quantity of alteration minerals were mapped using linear spectral unmixing(LSU)and mixture tuned matched filtering(MTMF)algorithms in the Sarduiyeh area,SE Kerman,Iran,using the visible-near infrared(VNIR)and short wave infrared(SWIR)bands of the Advanced Spaceborne Thermal Emission and Reflection Radiometer(ASTER)instrument and the results were compared to evaluate the efficiency of methods.Three groups of alteration minerals were identified:(1)pyrophylite-alunite(2)sericite-kaolinite,and(3)chlorite-calcite-epidote.Results showed that high abundances within pixels were successfully corresponded to the alteration zones.In addition,a number of unreported altered areas were identified.Field observations and X-ray diffraction(XRD)analysis of field samples confirmed the dominant mineral phases identified remotely.Results of LSU and MTMF were generally similar with overall accuracy of 82.9 and 90.24%,respectively.It is concluded that LSU and MTMF are suitable for sub-pixel mapping of alteration minerals and when the purpose is identification of particular targets,rather than all the elements in the scene,the MTMF algorithm could be proposed.展开更多
Understanding the mechanisms and spatial correlations of crystallographic symmetry breaking in ferroelectric materials is essential to tuning their functional properties.While optical second harmonic generation(SHG)ha...Understanding the mechanisms and spatial correlations of crystallographic symmetry breaking in ferroelectric materials is essential to tuning their functional properties.While optical second harmonic generation(SHG)has long been utilized in ferroelectric studies,its capability for probing complex polar materials has yet to be fully realized.Here,we develop a SHG spectral imaging method implemented on a home-designed laser-scanning SHG microscope,and demonstrate its application for a model system of(K,Na)NbO3 single crystals.Supervised model fitting analysis produces comprehensive information about the polarization vector orientations and relative fractions of constituent domain variants as well as their thermal evolution across the polymorphic phase transitions.Multiple domains and phases are clearly delineated at different temperatures,suggesting the phase competitions in(K,Na)NbO3.Besides,we show that unsupervised matrix decomposition analysis can quickly and faithfully reveal domain configurations without a priori knowledge about specific material systems.The SHG spectral imaging method can be readily extended to other ferroelectric materials with potentials to be further enhanced.展开更多
文摘Soil salinity is one of the serious environmental problems ravaging the soils of arid and semi-arid region, thereby affecting crop productivity, livestock, increase level of poverty and land degradation. Hyperspectral remote sensing is one of the important techniques to monitor, analyze and estimate the extent and severity of soil salt at regional to local scale. In this study we develop a model for the detection of salt-affected soils in arid and semi-arid regions and in our case it’s Ghannouch, Gabes. We used fourteen spectral indices and six spectral bands extracted from the Hyperion data. Linear Spectral Unmixing technique (LSU) was used in this study to improve the correlation between electrical conductivity and spectral indices and then improve the prediction of soil salinity as well as the reliability of the model. To build the model a multiple linear regression analysis was applied using the best correlated indices. The standard error of the estimate is about 1.57 mS/cm. The results of this study show that hyperion data is accurate and suitable for differentiating between categories of salt affected soils. The generated model can be used for management strategies in the future.
文摘This paper is an attempt to introduce the role of earth observation technology and a type of digital earth processing in mineral resources exploration and assessment.The sub-pixel distribution and quantity of alteration minerals were mapped using linear spectral unmixing(LSU)and mixture tuned matched filtering(MTMF)algorithms in the Sarduiyeh area,SE Kerman,Iran,using the visible-near infrared(VNIR)and short wave infrared(SWIR)bands of the Advanced Spaceborne Thermal Emission and Reflection Radiometer(ASTER)instrument and the results were compared to evaluate the efficiency of methods.Three groups of alteration minerals were identified:(1)pyrophylite-alunite(2)sericite-kaolinite,and(3)chlorite-calcite-epidote.Results showed that high abundances within pixels were successfully corresponded to the alteration zones.In addition,a number of unreported altered areas were identified.Field observations and X-ray diffraction(XRD)analysis of field samples confirmed the dominant mineral phases identified remotely.Results of LSU and MTMF were generally similar with overall accuracy of 82.9 and 90.24%,respectively.It is concluded that LSU and MTMF are suitable for sub-pixel mapping of alteration minerals and when the purpose is identification of particular targets,rather than all the elements in the scene,the MTMF algorithm could be proposed.
基金supported by National Natural Science Foundation of China(NSFC)under Grants No.52073155 and No.52150092the National Key Basic Research Program of China under Grant No.2020YFA0309100,and by the Project for Introduced Innovation Team in Jinan(2020GXRC037).
文摘Understanding the mechanisms and spatial correlations of crystallographic symmetry breaking in ferroelectric materials is essential to tuning their functional properties.While optical second harmonic generation(SHG)has long been utilized in ferroelectric studies,its capability for probing complex polar materials has yet to be fully realized.Here,we develop a SHG spectral imaging method implemented on a home-designed laser-scanning SHG microscope,and demonstrate its application for a model system of(K,Na)NbO3 single crystals.Supervised model fitting analysis produces comprehensive information about the polarization vector orientations and relative fractions of constituent domain variants as well as their thermal evolution across the polymorphic phase transitions.Multiple domains and phases are clearly delineated at different temperatures,suggesting the phase competitions in(K,Na)NbO3.Besides,we show that unsupervised matrix decomposition analysis can quickly and faithfully reveal domain configurations without a priori knowledge about specific material systems.The SHG spectral imaging method can be readily extended to other ferroelectric materials with potentials to be further enhanced.
