摘要 :
COMS\GOCI (Geostationary Ocean Color Imager) is the first geostationary ocean color satellite in the world launched by South Korea in June 2010, which includes eight bands from the visible to the infrared band. GOCI aerosol optica...
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COMS\GOCI (Geostationary Ocean Color Imager) is the first geostationary ocean color satellite in the world launched by South Korea in June 2010, which includes eight bands from the visible to the infrared band. GOCI aerosol optical thickness (AOT) at 555nm was retrieved by atmospheric radiative transfer model based on two-stream approximation algorithm. Due to GOCI without near infrared band and has a high solar elevation angle, solar zenith angle must be recalibrated to solve the earth system albedo, and the surface reflectance solved by quack atmospheric correction and recalculated backward scatter coefficient. Evaluation of GOCI\AOT with AERONET measurements showed that the average error becomes 0.107 from the original 0.393, that means GOCI aerosol optical thickness can be more accurately with the advanced two-stream approximation. Taking the eastern China in 3 and 4 December 2013 for example, comparing the GOCIVAOT at 555nm, MODIS\AOT retrievals at 550nm, NPP\AOT at 550nm and AERONET data products indicated that: take the AERONET data as reference, the error of three kinds of satellite data can be ordered as following: MODIS\AOT＞ GOCI\AOT＞ NPP\AOT and the GOCI-MODIS shows a bias of 0.02917 with the GOCI-NPP. GOCI\AOT is 0.05714 generally bigger than that of MODIS\AOT. NPP-GOCI deviation is 0.10253. The deficiency of MODIS is its low spatial resolution and the high concentration of AOT will be mistaken for a cloud area. However, GOCI can well reflect the concentration and distribution of aerosols. Therefore, GOGI can provide real-time dynamic monitoring on China Eastern atmospheric environment and the accurate time event information of haze for each process can be obtained. Finally, applied GOCI to the "8.12 Tianjin bombings" and to monitor the migration and dispersion of pollutant.
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摘要 :
COMS\GOCI (Geostationary Ocean Color Imager) is the first geostationary ocean color satellite in the world launched by South Korea in June 2010, which includes eight bands from the visible to the infrared band. GOCI aerosol optica...
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COMS\GOCI (Geostationary Ocean Color Imager) is the first geostationary ocean color satellite in the world launched by South Korea in June 2010, which includes eight bands from the visible to the infrared band. GOCI aerosol optical thickness (AOT) at 555nm was retrieved by atmospheric radiative transfer model based on two-stream approximation algorithm. Due to GOCI without near infrared band and has a high solar elevation angle, solar zenith angle must be recalibrated to solve the earth system albedo, and the surface reflectance solved by quack atmospheric correction and recalculated backward scatter coefficient. Evaluation of GOCI\AOT with AERONET measurements showed that the average error becomes 0.107 from the original 0.393, that means GOCI aerosol optical thickness can be more accurately with the advanced two-stream approximation. Taking the eastern China in 3 and 4 December 2013 for example, comparing the GOCIVAOT at 555nm, MODIS\AOT retrievals at 550nm, NPP\AOT at 550nm and AERONET data products indicated that: take the AERONET data as reference, the error of three kinds of satellite data can be ordered as following: MODIS\AOT＞ GOCI\AOT＞ NPP\AOT and the GOCI-MODIS shows a bias of 0.02917 with the GOCI-NPP. GOCI\AOT is 0.05714 generally bigger than that of MODIS\AOT. NPP-GOCI deviation is 0.10253. The deficiency of MODIS is its low spatial resolution and the high concentration of AOT will be mistaken for a cloud area. However, GOCI can well reflect the concentration and distribution of aerosols. Therefore, GOGI can provide real-time dynamic monitoring on China Eastern atmospheric environment and the accurate time event information of haze for each process can be obtained. Finally, applied GOCI to the "8.12 Tianjin bombings" and to monitor the migration and dispersion of pollutant.
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Solid Oxide Fuel Cells (SOFCs) consisting of durable ceramic components can be considered nowadays as the most promising fuel cell systems for alternative sources of energy due to their high electrical conversion efficiency, super...
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Solid Oxide Fuel Cells (SOFCs) consisting of durable ceramic components can be considered nowadays as the most promising fuel cell systems for alternative sources of energy due to their high electrical conversion efficiency, superior environmental performance, and fuel flexibility. In comparison to conventional SOFCs, micro tubular SOFCs have many advantages such as high resistance to thermal shock and higher power densities reaching 0.3 W cm-1 at 550°C. Recent improvements of the mechanical and electrochemical properties at reduced operating temperatures allows the use of cost-effective materials for interconnects and balance of plant.
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Modulation transfer function (MTF) quantitatively characterizes the quality of the optical imaging system. On the basis of the ISO12233:2017 standard, a method for fitting super-sampled edge spread function (ESF) with three Fermi ...
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Modulation transfer function (MTF) quantitatively characterizes the quality of the optical imaging system. On the basis of the ISO12233:2017 standard, a method for fitting super-sampled edge spread function (ESF) with three Fermi functions based on dynamic initial values is proposed, and the Canny algorithm with automatic threshold is used to detect the edge line. The proposed method dynamically adjusts the initial parameter values of the three Fermi functions obtained by the empirical formula, and uses the least squares method to fit the super-sampled ESF data. Compared with the ISO12233:2017 standard, the proposed method greatly reduces the influence of noise, which is mainly reflected in edge detection and the super-sampled ESF obtained from the projection of the image data. Simulation experiments are conducted on images with different blur and noise levels. The results show that compared with the method of empirical formula to get the initial fitting value, the proposed method is superior to the former in accuracy and scope of application. The experimental setup of MTF is established, and the same conclusion is obtained in actual measurement.
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摘要 :
Modulation transfer function (MTF) quantitatively characterizes the quality of the optical imaging system. On the basis of the ISO12233:2017 standard, a method for fitting super-sampled edge spread function (ESF) with three Fermi ...
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Modulation transfer function (MTF) quantitatively characterizes the quality of the optical imaging system. On the basis of the ISO12233:2017 standard, a method for fitting super-sampled edge spread function (ESF) with three Fermi functions based on dynamic initial values is proposed, and the Canny algorithm with automatic threshold is used to detect the edge line. The proposed method dynamically adjusts the initial parameter values of the three Fermi functions obtained by the empirical formula, and uses the least squares method to fit the super-sampled ESF data. Compared with the ISO12233:2017 standard, the proposed method greatly reduces the influence of noise, which is mainly reflected in edge detection and the super-sampled ESF obtained from the projection of the image data. Simulation experiments are conducted on images with different blur and noise levels. The results show that compared with the method of empirical formula to get the initial fitting value, the proposed method is superior to the former in accuracy and scope of application. The experimental setup of MTF is established, and the same conclusion is obtained in actual measurement.
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In order to analyze the effect of physical geographic factors on vegetation change in arid and semi-arid ecosystems, assess the relative role of individual physical geographic factors and the interaction between factors on vegetat...
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In order to analyze the effect of physical geographic factors on vegetation change in arid and semi-arid ecosystems, assess the relative role of individual physical geographic factors and the interaction between factors on vegetation changes quantitatively, this study takes the Xinjiang area as an example, uses the GIS spatial analysis technology and Geographical Detector model based on the analysis of variance to analysis the influence of physical geographic factors on the vegetation quantitatively. First of all, the spatial-temporal variations of vegetation in Xinjiang area over the last 30 years were analyzed using 1982-2011 GIMMS NDVI3g data as the indicator of vegetation activity. Secondly, the effects of mean annual precipitation, mean annual temperature, sunshine duration, mean annual wind velocity, DEM, slope and aspect, soil type and vegetation type were selected as potential physical geographic factors. Finally, the influence of physical geographic factors on vegetation change in Xinjiang area was analyzed using the Geographical Detector model. The results show that: (1) the annual coverage of vegetation in Xinjiang area was gradually increasing in 1982-2011 years (linear rate 0.0017/a, P=0.000). (2) the area of vegetation improvement was greater than the area of vegetation degradation. The area of vegetation improvement was mainly distributed in the northern part of the Tianshan Mountains and the Tarim Watershed, the vegetation degradation region was mainly distributed in the southern and Northeast part of Xinjiang. (3) precipitation, soil and vegetation types had the greatest influence on NDVI, followed by temperature, sunshine duration and DEM, and the other factors had little effect. (4) DEM enhanced the effect of soil type on NDVI, and sunshine duration and DEM enhanced all the effect of temperature on NDVI. So, sunshine duration and DEM can be used as the auxiliary indicator in the vegetation growth monitoring. Our results brought new insights on the monitoring of vegetation dynamic and could provide a basic reference for the local inhabitants and policy-makers to restore degraded arid and semi-arid ecosystems.
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摘要 :
In order to analyze the effect of physical geographic factors on vegetation change in arid and semi-arid ecosystems, assess the relative role of individual physical geographic factors and the interaction between factors on vegetat...
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In order to analyze the effect of physical geographic factors on vegetation change in arid and semi-arid ecosystems, assess the relative role of individual physical geographic factors and the interaction between factors on vegetation changes quantitatively, this study takes the Xinjiang area as an example, uses the GIS spatial analysis technology and Geographical Detector model based on the analysis of variance to analysis the influence of physical geographic factors on the vegetation quantitatively. First of all, the spatial-temporal variations of vegetation in Xinjiang area over the last 30 years were analyzed using 1982-2011 GIMMS NDVI3g data as the indicator of vegetation activity. Secondly, the effects of mean annual precipitation, mean annual temperature, sunshine duration, mean annual wind velocity, DEM, slope and aspect, soil type and vegetation type were selected as potential physical geographic factors. Finally, the influence of physical geographic factors on vegetation change in Xinjiang area was analyzed using the Geographical Detector model. The results show that: (1) the annual coverage of vegetation in Xinjiang area was gradually increasing in 1982-2011 years (linear rate 0.0017/a, P=0.000). (2) the area of vegetation improvement was greater than the area of vegetation degradation. The area of vegetation improvement was mainly distributed in the northern part of the Tianshan Mountains and the Tarim Watershed, the vegetation degradation region was mainly distributed in the southern and Northeast part of Xinjiang. (3) precipitation, soil and vegetation types had the greatest influence on NDVI, followed by temperature, sunshine duration and DEM, and the other factors had little effect. (4) DEM enhanced the effect of soil type on NDVI, and sunshine duration and DEM enhanced all the effect of temperature on NDVI. So, sunshine duration and DEM can be used as the auxiliary indicator in the vegetation growth monitoring. Our results brought new insights on the monitoring of vegetation dynamic and could provide a basic reference for the local inhabitants and policy-makers to restore degraded arid and semi-arid ecosystems.
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This paper mostly introduced the developing course in embankment risk exploration of dikes in lower reaches of Yellow River, principally introduced research of embankment risk detection for dikes, and instances of engineering appl...
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This paper mostly introduced the developing course in embankment risk exploration of dikes in lower reaches of Yellow River, principally introduced research of embankment risk detection for dikes, and instances of engineering application. According to characteristic of dikes in Yellow River, the idea of developing exploration and monitoring the changes of interior quality of engineering are brought forward with geophysical technology.
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Field investigation was carried out during 4, April, 2001 to 15, April, 2001 around Zhoushan Fishing Ground. The surface nutrient and suspended sediment (SS) concentration exhibit remarkable features. Most striking are that all da...
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Field investigation was carried out during 4, April, 2001 to 15, April, 2001 around Zhoushan Fishing Ground. The surface nutrient and suspended sediment (SS) concentration exhibit remarkable features. Most striking are that all data show very high values at the end member Changjiang Diluted Water (CDW), decrease abruptly at the onset of mixing of Taiwan Warm Current. The frontal zone is mainly located near 123°E, which is supported powerfully by NOAA sea surface temperature (SST) image. Total phosphorus (TP) concentration is affected profoundly with SS concentration, for robust relationship between total particulate (TPP) and TP is observed in most stations (R~2=0.9073, n=10). Positive correlation between in-situ concentration of TP and SS are found. The experimental regression equation is represented as C_(TP)=0.0195~*C_(SS)+0.5266, R~2=0.5645(n=32). NO_3~- is the main form of DIN, of more than 82% in DIN, exhibits considerable conservative feature. Although lack of in-situ CDOM measurement, good relationship was established between in-situ DIN concentration with near real time SeaWiFS ACD data: C_(DIN)=135.1351~*C_(ACD)-6.0, R~2=0.7514 (n=15). The two empirical regression algorithms were utilized for inversing TP and DIN concentration from SeaWiFS SS and ACD. The algorithms were adopted to evaluate the impaction of terrestrial pollutant input to the area by CDW.
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A simple and fast multi-channel filtering algorithm is presented in the paper for texture segmentation. This algorithm requires only a small number of channels and automatically determines the channel parameters by analysis of the...
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A simple and fast multi-channel filtering algorithm is presented in the paper for texture segmentation. This algorithm requires only a small number of channels and automatically determines the channel parameters by analysis of the Fourier power spectrum. Also it does not need a priori knowledge about the type and number of textures occurring in the input images. We can gain categories number by the square-error plot of different clusters. It does not involve any human intervention. The algorithm is tested extensively with a variety of Brodatz's textures and real textures. The segmentation results validate the practicability of this algorithm.
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