A direct comparison of urban and rural surface energy balances, as well as a variety of other variables including incoming shortwave/longwave radiation and aerosol optical depth, is conducted for the Beijing metropoli...A direct comparison of urban and rural surface energy balances, as well as a variety of other variables including incoming shortwave/longwave radiation and aerosol optical depth, is conducted for the Beijing metropolitan area. The results indicate that, overall, the urban area receives a smaller amount of incoming shortwave radiation but a larger amount of incoming longwave radiation. However, comparisons in the aerosol optical depth and cloud fraction at the two locations suggest that neither aerosol optical depth nor cloud fraction alone can explain the difference in the incoming shortwave radiation. The urban–rural differences in the incoming longwave radiation are unlikely to be caused by the presence of more abundant greenhouse gases over the urban area, as suggested by some previous studies, given that water vapor is the most dominant greenhouse gas and precipitable water is found to be less in urban areas. The higher incoming longwave radiation observed over the urban area is mostly likely due to the higher temperatures of the ambient air. The urban area is also found to always produce higher sensible heat fluxes and lower latent heat fluxes in the growing season. Furthermore, the urban area is associated with a larger amount of available energy（the sum of sensible and latent heat fluxes） than the rural area, except in May and October when evapotranspiration in the rural area significantly exceeds that in the urban area. This study provides observational evidence of urban–rural contrasts in relevant energy-balance components that plausibly arise from urban–rural differences in atmospheric and land-surface conditions.展开更多
In this paper,we aim to propose a novel and effective iris segmentation method that is robust to uneven light intensity and different kinds of noises such as occlusion by light spots,eyelashes,eyelids,specta-cle-frame...In this paper,we aim to propose a novel and effective iris segmentation method that is robust to uneven light intensity and different kinds of noises such as occlusion by light spots,eyelashes,eyelids,specta-cle-frame,etc.Unlike previous methods,the proposed method makes full use of gray intensities of the iris image.Inspired by the matting algorithm,a premier assumption is made that the foreground and background images of the iris image are both locally smooth.According to the RST algorithm,trimaps are built to provide priori in-formation.Under the assumption and priori,the optimal alpha matte can be obtained by least square loss function.A series of effective post processing methods are applied to the alpha image to obtain a more precise iris seg-mentation.The experiment on CASIA-iris-thousand database shows that the proposed method achieves a much better performance than conventional methods.Our experimental results achieve 20.5%and 26.4%,more than the well-known integro-differential operator and edge detection combined with Hough transform on iris seg-mentation rate respectively.The stability and validity of the proposed method is further demonstrated through the complementary experiments on the challenging iris images.展开更多
In order to research how the size of the ink flow channel is affected by the interaction of adjacent ink areas,according to the method of fluid-solid interaction,this paper analyzes the size of the ink flow channel of...In order to research how the size of the ink flow channel is affected by the interaction of adjacent ink areas,according to the method of fluid-solid interaction,this paper analyzes the size of the ink flow channel of two ink rollers' rotation.Firstly,this paper simulates the situation of only one ink area.Secondly,this paper simulates the situation of five adjacent ink areas.Then,through comparing the simulation results of two above situations,it' s obvious that the interaction of adjacent ink areas has big effects on the ink pressure and the size of ink flow channel.At last,this paper gets the main factor that affects the size of ink flow channel in the different situations.展开更多
基金supported by the National Key Basic Research Program (Grant Nos. 2010CB428502 and 2012CB417203)the National Natural Science Foundation of China (Grant Nos. 41405018 and 41275022)+2 种基金the China Meteorological Administration (Grant No. GYHY201006024)the CAS Strategic Priority Research Program (Grant No. XDA05110101)the support of the State Key Laboratory of Atmospheric Boundary Layer Physics and Atmospheric Chemistry, Institute of Atmospheric Physics, Chinese Academy of Sciences (Grant No. LAPC-KF-2009-02)
文摘A direct comparison of urban and rural surface energy balances, as well as a variety of other variables including incoming shortwave/longwave radiation and aerosol optical depth, is conducted for the Beijing metropolitan area. The results indicate that, overall, the urban area receives a smaller amount of incoming shortwave radiation but a larger amount of incoming longwave radiation. However, comparisons in the aerosol optical depth and cloud fraction at the two locations suggest that neither aerosol optical depth nor cloud fraction alone can explain the difference in the incoming shortwave radiation. The urban–rural differences in the incoming longwave radiation are unlikely to be caused by the presence of more abundant greenhouse gases over the urban area, as suggested by some previous studies, given that water vapor is the most dominant greenhouse gas and precipitable water is found to be less in urban areas. The higher incoming longwave radiation observed over the urban area is mostly likely due to the higher temperatures of the ambient air. The urban area is also found to always produce higher sensible heat fluxes and lower latent heat fluxes in the growing season. Furthermore, the urban area is associated with a larger amount of available energy（the sum of sensible and latent heat fluxes） than the rural area, except in May and October when evapotranspiration in the rural area significantly exceeds that in the urban area. This study provides observational evidence of urban–rural contrasts in relevant energy-balance components that plausibly arise from urban–rural differences in atmospheric and land-surface conditions.
文摘In this paper,we aim to propose a novel and effective iris segmentation method that is robust to uneven light intensity and different kinds of noises such as occlusion by light spots,eyelashes,eyelids,specta-cle-frame,etc.Unlike previous methods,the proposed method makes full use of gray intensities of the iris image.Inspired by the matting algorithm,a premier assumption is made that the foreground and background images of the iris image are both locally smooth.According to the RST algorithm,trimaps are built to provide priori in-formation.Under the assumption and priori,the optimal alpha matte can be obtained by least square loss function.A series of effective post processing methods are applied to the alpha image to obtain a more precise iris seg-mentation.The experiment on CASIA-iris-thousand database shows that the proposed method achieves a much better performance than conventional methods.Our experimental results achieve 20.5%and 26.4%,more than the well-known integro-differential operator and edge detection combined with Hough transform on iris seg-mentation rate respectively.The stability and validity of the proposed method is further demonstrated through the complementary experiments on the challenging iris images.
基金Supported by the National Natural Science Foundation of China(No.51105009)the National Science and Technology Support Program(No.2012BAF13B05)
文摘In order to research how the size of the ink flow channel is affected by the interaction of adjacent ink areas,according to the method of fluid-solid interaction,this paper analyzes the size of the ink flow channel of two ink rollers' rotation.Firstly,this paper simulates the situation of only one ink area.Secondly,this paper simulates the situation of five adjacent ink areas.Then,through comparing the simulation results of two above situations,it' s obvious that the interaction of adjacent ink areas has big effects on the ink pressure and the size of ink flow channel.At last,this paper gets the main factor that affects the size of ink flow channel in the different situations.
