The classification of thematic mapper imagery in areas with strong topographic variations has proven problematic in the past using a single classifier, due to the changing sun illumination geometry. This often results...The classification of thematic mapper imagery in areas with strong topographic variations has proven problematic in the past using a single classifier, due to the changing sun illumination geometry. This often results in the phenomena of identical object with dissimilar spectrum and different objects with similar spectrum. In this paper, an integrated classification method that combines a decision tree with slope data, tasseled cap transformation indices and maximum likelihood classifier is introduced, to find an optimal classification method for thematic mapper imagery of plain and highland terrains. A Landsat 7 ETM+ image acquired over Hangzhou Bay, in eastern China was used to test the method. The results indicate that the performance of the inte- grated classifier is acceptably good in comparison with that of the existing most widely used maximum likelihood classifier. The integrated classifier depends on hypsography (variation in topography) and the characteristics of ground truth objects (plant and soil). It can greatly reduce the influence of the homogeneous spectrum caused by topographic variation. This integrated classifier might potentially be one of the most accurate classifiers and valuable tool for land cover and land use mapping of plain and highland terrains.展开更多
Two primary solar-activity indicators- sunspot numbers （SNs） and sunspot areas （SAs） in the time interval from November 1874 to December 2012 - are used to determine the chaotic and fractal properties of solar act...Two primary solar-activity indicators- sunspot numbers （SNs） and sunspot areas （SAs） in the time interval from November 1874 to December 2012 - are used to determine the chaotic and fractal properties of solar activity. The results show that （1） the long-term solar activity is governed by a low-dimensional chaotic strange attractor, and its fractal motion shows a long-term persistence on large scales; （2） both the fractal dimension and maximal Lyapunov exponent of SAs are larger than those of SNs, implying that the dynamical system of SAs is more chaotic and complex than SNs; （3） the predictions of solar activity should only be done for short- to mid-term behaviors due to its intrinsic complexity; moreover, the predictability time of SAs is obviously smaller than that of SNs and previous results.展开更多
This paper introduces a new enhancement method for multi-spectral satellite remote sensing imagery,based on principal component analysis(PCA) and intensity-hue-saturation(IHS) transformations.The PCA and the IHS trans...This paper introduces a new enhancement method for multi-spectral satellite remote sensing imagery,based on principal component analysis(PCA) and intensity-hue-saturation(IHS) transformations.The PCA and the IHS transformations are used to separate the spatial information of the multi-spectral image into the first principal component and the intensity component,respectively.The enhanced image is obtained by replacing the intensity component of the IHS transformation with the first principal component of the PCA transformation,and undertaking the inverse IHS transformation.The objective of the proposed method is to make greater use of the spatial and spectral information contained in the original multi-spectral image.On the basis of the visual and statistical analysis results of the experimental study,we can conclude that the proposed method is an ideal new way for multi-spectral image quality enhancement with little color distortion.It has potential advantages in image mapping optimization,object recognition,and weak information sharpening.展开更多
CeO_(2) is one of the main catalysts for solid oxide fuel cell(SOFC).It is critical to find a green and costeffective fabrication method for CeO_(2) at scale.In this study,the CeO_(2) microspheres were prepared by one...CeO_(2) is one of the main catalysts for solid oxide fuel cell(SOFC).It is critical to find a green and costeffective fabrication method for CeO_(2) at scale.In this study,the CeO_(2) microspheres were prepared by one-step ultrasonic spray pyrolysis of cerium chloride solution at700℃.Scanning electron microscopy(SEM)and transmission electron microscopy(TEM)study demonstrate that the prepared CeO_(2) microspheres exhibit a particle size of0.01-1.08μm with a mean particle size of 0.23μm,and more than 94%of the particles have a diameter less than0.5μm.But the presence of residual Cl in the fabricated CeO_(2) microspheres blocks the active sites and leads to the significant degradation of SOFC performance.The formation mechanism and distribution of residual Cl in the fabricated CeO_(2) microspheres were systemic ally studied.The water washing method was shown to effectively reduce the residual Cl in the CeO_(2) microspheres.Overall,this work provides a clean manufacturing process for the preparation of SOFC electrode/electrolyte materials.展开更多
The recovery of iron and enrichment of rare earths from Bayan Obo railings were investigated using Coal Ca（OH） 2 NaOH roasting followed by magnetic separation. The influences of roasting temperature, roasting time, ...The recovery of iron and enrichment of rare earths from Bayan Obo railings were investigated using Coal Ca（OH） 2 NaOH roasting followed by magnetic separation. The influences of roasting temperature, roasting time, coal content, milling time, Ca（OH）2 dosage and NaOH dosage on the iron and rare earths recovery were explored. The results showed that the magnetic concentrate containing 70.01 wt. % Fe with the iron recovery of 94.34G and the tailings of magnetic separation containing 11.46 wt. % rare earth oxides （REO） with the REO recovery of 98. 19% were obtained under the optimum conditions （i. e. , roasting temperature of 650℃, roasting time of 60 min, coal content of 2.0%, milling time of 5 min, and NaOH dosage of 2.0%）. The Ca（OH）2 dosage had no effect on the separation of iron and rare earths. According to the mineralogical and morphologic analysis, the iron and rare earths of Bayan Obo tailings could be utilized in subsequent ironmaking process and hydrometallurgy process.展开更多
V48Fe12Ti15Cr25 alloy was prepared using vacuum arc melting and was subsequently annealed for 10 h at 1273 K.The effects of annealing on the hydrogen storage properties and microstructure of the V48Fe12Ti15Cr25 alloys...V48Fe12Ti15Cr25 alloy was prepared using vacuum arc melting and was subsequently annealed for 10 h at 1273 K.The effects of annealing on the hydrogen storage properties and microstructure of the V48Fe12Ti15Cr25 alloys were investigated.The results indicated that the alloy consisted of main body-centered cubic,Ti-rich,and TiFe phases.After annealing,the kinetic properties of the alloy were improved but its hydrogen storage capacity was slightly reduced.The kinetic mechanisms of the hydrogen absorption and desorption of the alloys were studied.The dehydrogenation enthalpy of the alloy was decreased by 2.57 kJ/mol after annealing.Differential scanning calorimetry indicated that the hydride decomposition temperature of the annealed alloy was decreased.The hydrogen desorption activation energies of the as-cast and annealed alloys were calculated to be 79.41 and 71.25 kJ/mol,respectively.The results illustrated that annealing was a beneficial method of improving the kinetic and thermodynamic properties of the hydrogen absorption/desorption of the alloy.展开更多
文摘The classification of thematic mapper imagery in areas with strong topographic variations has proven problematic in the past using a single classifier, due to the changing sun illumination geometry. This often results in the phenomena of identical object with dissimilar spectrum and different objects with similar spectrum. In this paper, an integrated classification method that combines a decision tree with slope data, tasseled cap transformation indices and maximum likelihood classifier is introduced, to find an optimal classification method for thematic mapper imagery of plain and highland terrains. A Landsat 7 ETM+ image acquired over Hangzhou Bay, in eastern China was used to test the method. The results indicate that the performance of the inte- grated classifier is acceptably good in comparison with that of the existing most widely used maximum likelihood classifier. The integrated classifier depends on hypsography (variation in topography) and the characteristics of ground truth objects (plant and soil). It can greatly reduce the influence of the homogeneous spectrum caused by topographic variation. This integrated classifier might potentially be one of the most accurate classifiers and valuable tool for land cover and land use mapping of plain and highland terrains.
基金Supported by the National Natural Science Foundation of China
文摘Two primary solar-activity indicators- sunspot numbers （SNs） and sunspot areas （SAs） in the time interval from November 1874 to December 2012 - are used to determine the chaotic and fractal properties of solar activity. The results show that （1） the long-term solar activity is governed by a low-dimensional chaotic strange attractor, and its fractal motion shows a long-term persistence on large scales; （2） both the fractal dimension and maximal Lyapunov exponent of SAs are larger than those of SNs, implying that the dynamical system of SAs is more chaotic and complex than SNs; （3） the predictions of solar activity should only be done for short- to mid-term behaviors due to its intrinsic complexity; moreover, the predictability time of SAs is obviously smaller than that of SNs and previous results.
文摘This paper introduces a new enhancement method for multi-spectral satellite remote sensing imagery,based on principal component analysis(PCA) and intensity-hue-saturation(IHS) transformations.The PCA and the IHS transformations are used to separate the spatial information of the multi-spectral image into the first principal component and the intensity component,respectively.The enhanced image is obtained by replacing the intensity component of the IHS transformation with the first principal component of the PCA transformation,and undertaking the inverse IHS transformation.The objective of the proposed method is to make greater use of the spatial and spectral information contained in the original multi-spectral image.On the basis of the visual and statistical analysis results of the experimental study,we can conclude that the proposed method is an ideal new way for multi-spectral image quality enhancement with little color distortion.It has potential advantages in image mapping optimization,object recognition,and weak information sharpening.
基金financially supported by the National Key R&D Program of China(No.2018YFB1502600)the National Natural Science Foundation of China(Nos.51922042 and 51872098)+1 种基金China Postdoctoral Science Foundation(No.2019M652888)the Sino-Singapore International Joint Research Institute(SSIJRI),China。
文摘CeO_(2) is one of the main catalysts for solid oxide fuel cell(SOFC).It is critical to find a green and costeffective fabrication method for CeO_(2) at scale.In this study,the CeO_(2) microspheres were prepared by one-step ultrasonic spray pyrolysis of cerium chloride solution at700℃.Scanning electron microscopy(SEM)and transmission electron microscopy(TEM)study demonstrate that the prepared CeO_(2) microspheres exhibit a particle size of0.01-1.08μm with a mean particle size of 0.23μm,and more than 94%of the particles have a diameter less than0.5μm.But the presence of residual Cl in the fabricated CeO_(2) microspheres blocks the active sites and leads to the significant degradation of SOFC performance.The formation mechanism and distribution of residual Cl in the fabricated CeO_(2) microspheres were systemic ally studied.The water washing method was shown to effectively reduce the residual Cl in the CeO_(2) microspheres.Overall,this work provides a clean manufacturing process for the preparation of SOFC electrode/electrolyte materials.
基金supports by the National Key Basic Research Program of China (No.2012CBA01205)
文摘The recovery of iron and enrichment of rare earths from Bayan Obo railings were investigated using Coal Ca（OH） 2 NaOH roasting followed by magnetic separation. The influences of roasting temperature, roasting time, coal content, milling time, Ca（OH）2 dosage and NaOH dosage on the iron and rare earths recovery were explored. The results showed that the magnetic concentrate containing 70.01 wt. % Fe with the iron recovery of 94.34G and the tailings of magnetic separation containing 11.46 wt. % rare earth oxides （REO） with the REO recovery of 98. 19% were obtained under the optimum conditions （i. e. , roasting temperature of 650℃, roasting time of 60 min, coal content of 2.0%, milling time of 5 min, and NaOH dosage of 2.0%）. The Ca（OH）2 dosage had no effect on the separation of iron and rare earths. According to the mineralogical and morphologic analysis, the iron and rare earths of Bayan Obo tailings could be utilized in subsequent ironmaking process and hydrometallurgy process.
基金National Natural Science Foundation of China(Grant No.51901105)Natural Science Foundation of Inner Mongolia,China(Grant Nos.2018LH05010,2019BS05005,and 2017BS0507).
文摘V48Fe12Ti15Cr25 alloy was prepared using vacuum arc melting and was subsequently annealed for 10 h at 1273 K.The effects of annealing on the hydrogen storage properties and microstructure of the V48Fe12Ti15Cr25 alloys were investigated.The results indicated that the alloy consisted of main body-centered cubic,Ti-rich,and TiFe phases.After annealing,the kinetic properties of the alloy were improved but its hydrogen storage capacity was slightly reduced.The kinetic mechanisms of the hydrogen absorption and desorption of the alloys were studied.The dehydrogenation enthalpy of the alloy was decreased by 2.57 kJ/mol after annealing.Differential scanning calorimetry indicated that the hydride decomposition temperature of the annealed alloy was decreased.The hydrogen desorption activation energies of the as-cast and annealed alloys were calculated to be 79.41 and 71.25 kJ/mol,respectively.The results illustrated that annealing was a beneficial method of improving the kinetic and thermodynamic properties of the hydrogen absorption/desorption of the alloy.
