Those various cross-sectional vessels in trees transfer water to as high as 100 meters,but the traditional fabrication methods limit the manufacturing of those vessels,resulting in the non-availability of those bionic...Those various cross-sectional vessels in trees transfer water to as high as 100 meters,but the traditional fabrication methods limit the manufacturing of those vessels,resulting in the non-availability of those bionic microchannels.Herein,we fabricate those bionic microchannels with various cross-sections by employing projection micro-stereolithography(PμSL)based 3D printing technique.The circumradius of bionic microchannels(pentagonal,square,triangle,and five-pointed star)can be as small as 100μm with precisely fabricated sharp corners.What's more,those bionic microchannels demonstrate marvelous microfluidic performance with strong precursor effects enabled by their sharp corners.Most significantly,those special properties of our bionic microchannels enable them outstanding step lifting performance to transport water to tens of millimeters,though the water can only be transported to at most 20 mm for a single bionic microchannel.The mimicked transpiration based on the step lifting of water from bionic microchannels is also achieved.Those precisely fabricated,low-cost,various cross-sectional bionic microchannels promise applications as microfluidic chips,long-distance unpowered water transportation,step lifting,mimicked transpiration,and so on.展开更多
Spatial characteristic is an important indicator of remote sensor performance,and space-borne infrared hyperspectral sounder is the frontier of atmospheric vertical sounding technology.In this paper,the formation mech...Spatial characteristic is an important indicator of remote sensor performance,and space-borne infrared hyperspectral sounder is the frontier of atmospheric vertical sounding technology.In this paper,the formation mechanism of the vertical spatial characteristics involved in the space-borne infrared hyperspectral sounding data are analyzed in detail,which shows that the vertical spatial characteristics of sounding data depends not only on the spectral channels and their waveband coverage,but also the specific atmospheric parameter and its specific variation interested.The indicators of vertical spatial characteristics are defined and their mathematical models are established based on the mechanism analyses.These models are applied to the vertical spatial characteristic evaluation of atmospheric temperature sounding for FY-4A GIIRS,which is the first space-borne infrared hyperspectral atmospheric sounder in geostationary orbit.It is concluded that FY-4A GIIRS can sound the vertical temperature distribution in whole troposphere and lower stratosphere with height<35 km.This study can provide basic information to support the improvement of infrared hyperspectral sounder and the trace of vertical spatial characteristics of atmospheric inversion products.展开更多
The terminal settling velocity(TSV)calcula-tion of drops and other spherical objects in fluid medium is a classical problem,which has important application values in many fields such as the study of cloud and precipit...The terminal settling velocity(TSV)calcula-tion of drops and other spherical objects in fluid medium is a classical problem,which has important application values in many fields such as the study of cloud and precipitation processes,the evaluation of soil erosion,and the determination of fluid viscosity coefficient etc.In this paper,a new explicit approximation model of TSV is established,which combines the theoretical solution of N-S equation about fluid motion around spherical objects and the statistical regression of solution dimensionless coeffi-cients with measurement data.This new model can adapt to different values of drop parameters and medium parameters in a large range of Re.By this model,the relative and absolute calculation errors of TSV are in range of 3.42%+4.34%and 0.271 m/s-+0.128 m/s respec-tively for drop radius 0.005-2.9 mm.Their corresponding root mean square values are 1.77%and 0.084 rn/s respectively,which are much smaller than that of past theoretical and empirical models.展开更多
China is frequently affected by tropical cyclones in summer and autumn because its southern and eastern parts border low-latitude oceans.The track forecasting of tropical cyclones is a key issue in weather forecasting...China is frequently affected by tropical cyclones in summer and autumn because its southern and eastern parts border low-latitude oceans.The track forecasting of tropical cyclones is a key issue in weather forecasting.In daily operations,forecasters usually focus on the effects of environmental flow fields on tropical cyclones,such as the subtropical high pressure belt,the basic flow,the troughs and ridges in westerlies,the cross-equatorial flow,the equatorial convergence belt,and the polar front.However,these factors become less significant when the environmental fields are so weak that the steering flow does not play a vital role or we cannot accurately determine the evolution of the environment flow field.Meteorological satellite cloud imagery can fill the data gap of conventional observations and provide important clues for forecasting the status and development of tropical cyclones when they are included in day-to-day weather forecasting operations.In this study,using 'Muifa', 'Haikui' and other typhoons as examples,the effects of the cloud pattern and the large-scale environmental vapor fields,on the moving tracks of typhoons were analyzed based on satellite data.The results showed that the change of structures of typhoon spiral cloud bands and the turning of the typhoon path were taking on greater relevance,and at the same time the satellite water vapor images had obvious advantages in terms of indicating the large-scale environmental fields.A combination of satellite cloud imagery,observational data,and weather event analysis remains the most effective approach in the operational forecasting of typhoon moving tracks.展开更多
基金supported by the National Natural Science Foundation of China(52006056)the Experiments for Space Exploration Program and the Qian Xuesen Laboratory,China Academy of Space Technology(TKTSPY-2020-01-04)+2 种基金the Key-Area Research and Development Program of Guangdong Province(2020B090923003)partly supported by Natural Science Foundation of Hunan through Grant No.2020JJ3012Natural Research Institute for Family Planning。
文摘Those various cross-sectional vessels in trees transfer water to as high as 100 meters,but the traditional fabrication methods limit the manufacturing of those vessels,resulting in the non-availability of those bionic microchannels.Herein,we fabricate those bionic microchannels with various cross-sections by employing projection micro-stereolithography(PμSL)based 3D printing technique.The circumradius of bionic microchannels(pentagonal,square,triangle,and five-pointed star)can be as small as 100μm with precisely fabricated sharp corners.What's more,those bionic microchannels demonstrate marvelous microfluidic performance with strong precursor effects enabled by their sharp corners.Most significantly,those special properties of our bionic microchannels enable them outstanding step lifting performance to transport water to tens of millimeters,though the water can only be transported to at most 20 mm for a single bionic microchannel.The mimicked transpiration based on the step lifting of water from bionic microchannels is also achieved.Those precisely fabricated,low-cost,various cross-sectional bionic microchannels promise applications as microfluidic chips,long-distance unpowered water transportation,step lifting,mimicked transpiration,and so on.
文摘Spatial characteristic is an important indicator of remote sensor performance,and space-borne infrared hyperspectral sounder is the frontier of atmospheric vertical sounding technology.In this paper,the formation mechanism of the vertical spatial characteristics involved in the space-borne infrared hyperspectral sounding data are analyzed in detail,which shows that the vertical spatial characteristics of sounding data depends not only on the spectral channels and their waveband coverage,but also the specific atmospheric parameter and its specific variation interested.The indicators of vertical spatial characteristics are defined and their mathematical models are established based on the mechanism analyses.These models are applied to the vertical spatial characteristic evaluation of atmospheric temperature sounding for FY-4A GIIRS,which is the first space-borne infrared hyperspectral atmospheric sounder in geostationary orbit.It is concluded that FY-4A GIIRS can sound the vertical temperature distribution in whole troposphere and lower stratosphere with height<35 km.This study can provide basic information to support the improvement of infrared hyperspectral sounder and the trace of vertical spatial characteristics of atmospheric inversion products.
文摘The terminal settling velocity(TSV)calcula-tion of drops and other spherical objects in fluid medium is a classical problem,which has important application values in many fields such as the study of cloud and precipitation processes,the evaluation of soil erosion,and the determination of fluid viscosity coefficient etc.In this paper,a new explicit approximation model of TSV is established,which combines the theoretical solution of N-S equation about fluid motion around spherical objects and the statistical regression of solution dimensionless coeffi-cients with measurement data.This new model can adapt to different values of drop parameters and medium parameters in a large range of Re.By this model,the relative and absolute calculation errors of TSV are in range of 3.42%+4.34%and 0.271 m/s-+0.128 m/s respec-tively for drop radius 0.005-2.9 mm.Their corresponding root mean square values are 1.77%and 0.084 rn/s respectively,which are much smaller than that of past theoretical and empirical models.
文摘China is frequently affected by tropical cyclones in summer and autumn because its southern and eastern parts border low-latitude oceans.The track forecasting of tropical cyclones is a key issue in weather forecasting.In daily operations,forecasters usually focus on the effects of environmental flow fields on tropical cyclones,such as the subtropical high pressure belt,the basic flow,the troughs and ridges in westerlies,the cross-equatorial flow,the equatorial convergence belt,and the polar front.However,these factors become less significant when the environmental fields are so weak that the steering flow does not play a vital role or we cannot accurately determine the evolution of the environment flow field.Meteorological satellite cloud imagery can fill the data gap of conventional observations and provide important clues for forecasting the status and development of tropical cyclones when they are included in day-to-day weather forecasting operations.In this study,using 'Muifa', 'Haikui' and other typhoons as examples,the effects of the cloud pattern and the large-scale environmental vapor fields,on the moving tracks of typhoons were analyzed based on satellite data.The results showed that the change of structures of typhoon spiral cloud bands and the turning of the typhoon path were taking on greater relevance,and at the same time the satellite water vapor images had obvious advantages in terms of indicating the large-scale environmental fields.A combination of satellite cloud imagery,observational data,and weather event analysis remains the most effective approach in the operational forecasting of typhoon moving tracks.
