The present study is an investigation of the properties of poly(vinyl alcohol),which would be a better contact lens mate- rial than conventional HEMA in some ways.A transparent PVA hydrogel was prepared from a PVA sol...The present study is an investigation of the properties of poly(vinyl alcohol),which would be a better contact lens mate- rial than conventional HEMA in some ways.A transparent PVA hydrogel was prepared from a PVA solution in a mixed solvent consisting of water and a water-miscible organic solvent,DMSO,by the freezing-thawing method.The water content,visible light transmittance,mechanical and swelling properties of the hydrogels were evaluated as a function of PVA concentration and number of freeze-thaw cycles.The results show that the properties of PVA hydrogels depend on the polymer concentration,the number of freeze-thaw cycles and the addition of the organic solvent.展开更多
Using a microwave radiative transfer （MWRT） model with microwave brightness temperatures （TBs） observed from the Tropical Rainfall Measuring Mission （TRMM） Microwave Imager （TMI）, an indirect approach evaluate...Using a microwave radiative transfer （MWRT） model with microwave brightness temperatures （TBs） observed from the Tropical Rainfall Measuring Mission （TRMM） Microwave Imager （TMI）, an indirect approach evaluated hydrometeors generated from the Weather Research and Forecasting （WRY） model in the process of CHABA typhoon in August 2004. This study compares the simulated TBs generated from the microwave radioactive transfer model connected to the WRF model with the observed TBs derived from TMI and analyzes the differences between these TBs. The results indicate that the WRF model underestimates the amount and area of liquid and ice hydrometeors inside the typhoon center. The results also indicate relatively better agreement between the simulated and the observed TBs in the vertical polarization than in the horizontal polarization.展开更多
The mechanical properties of outwash deposits which are taken as unconsolidated geo-materials with the characteristics of non-uniformity, heterogeneity and multiphase have attracted much attention in engineering. Acco...The mechanical properties of outwash deposits which are taken as unconsolidated geo-materials with the characteristics of non-uniformity, heterogeneity and multiphase have attracted much attention in engineering. According to the results of laboratory direct shear test on the remolded samples, the soil particle parameters of numerical model based on in-situ particle size cumulative curves and 3D granular discrete element method were determined. Then, numerical experiments on different lithology, stone content and gradation composition were conducted. The results show that it is not a flat surface but a shear band that yields in the sample. The curve of particle velocity vs distance from the designed shear surface of test model that is taken as a datum plane in the vertical section of sample shows in "S" shape. The shear disturbance area is about twice the maximum diameter of stone blocks. The greater the stiffness of stone is, the rougher the shear surface is. The shear strength of outwash deposits is largely controlled by lithology and stone content, and the bite force between stone blocks is the root reason of larger friction angle. It is also shown that strain hardening and low shear dilatancy occur under high confining pressure as well as possibility of shear shrinkage. But it is easy to behave shear dilatation and strain softening under low confining pressure. The relationship between particle frictional coefficient and stone content presents an approximately quadratic parabola increase. The strain energy first increases and then drops with the increase of frictional energy. The cohesion increases with soil stiffness increasing but decreases with stone stiffness increasing. Numerical results are consistent with the laboratory test results of remolded samples, which indicate that this method can be a beneficial supplement to determine the parameters of engineering deposit bodies.展开更多
基金Projects 50575106 supported by the National Natural Science Foundation of ChinaBG2007046 by the High Technology Project of Jiangsu Province
文摘The present study is an investigation of the properties of poly(vinyl alcohol),which would be a better contact lens mate- rial than conventional HEMA in some ways.A transparent PVA hydrogel was prepared from a PVA solution in a mixed solvent consisting of water and a water-miscible organic solvent,DMSO,by the freezing-thawing method.The water content,visible light transmittance,mechanical and swelling properties of the hydrogels were evaluated as a function of PVA concentration and number of freeze-thaw cycles.The results show that the properties of PVA hydrogels depend on the polymer concentration,the number of freeze-thaw cycles and the addition of the organic solvent.
基金supported by the Knowledge Innovation Program of the Chinese Academy of Sciences (Grant Nos. KZCX2-YW-Q11-04 and KZCX2-EW-QN507)the National Basic Research Program of China (973 Program,Grant No. 2010CB428601)the National Natural Science Foundation of China (Grant Nos. 40730950 and 41075041)
文摘Using a microwave radiative transfer （MWRT） model with microwave brightness temperatures （TBs） observed from the Tropical Rainfall Measuring Mission （TRMM） Microwave Imager （TMI）, an indirect approach evaluated hydrometeors generated from the Weather Research and Forecasting （WRY） model in the process of CHABA typhoon in August 2004. This study compares the simulated TBs generated from the microwave radioactive transfer model connected to the WRF model with the observed TBs derived from TMI and analyzes the differences between these TBs. The results indicate that the WRF model underestimates the amount and area of liquid and ice hydrometeors inside the typhoon center. The results also indicate relatively better agreement between the simulated and the observed TBs in the vertical polarization than in the horizontal polarization.
基金Project(2011CB013504) supported by the National Basic Research Program of ChinaProjects(50911130366, 11172090) supported by the National Natural Science Foundation of ChinaProject supported by Central University Basic Research Special Fund, China
文摘The mechanical properties of outwash deposits which are taken as unconsolidated geo-materials with the characteristics of non-uniformity, heterogeneity and multiphase have attracted much attention in engineering. According to the results of laboratory direct shear test on the remolded samples, the soil particle parameters of numerical model based on in-situ particle size cumulative curves and 3D granular discrete element method were determined. Then, numerical experiments on different lithology, stone content and gradation composition were conducted. The results show that it is not a flat surface but a shear band that yields in the sample. The curve of particle velocity vs distance from the designed shear surface of test model that is taken as a datum plane in the vertical section of sample shows in "S" shape. The shear disturbance area is about twice the maximum diameter of stone blocks. The greater the stiffness of stone is, the rougher the shear surface is. The shear strength of outwash deposits is largely controlled by lithology and stone content, and the bite force between stone blocks is the root reason of larger friction angle. It is also shown that strain hardening and low shear dilatancy occur under high confining pressure as well as possibility of shear shrinkage. But it is easy to behave shear dilatation and strain softening under low confining pressure. The relationship between particle frictional coefficient and stone content presents an approximately quadratic parabola increase. The strain energy first increases and then drops with the increase of frictional energy. The cohesion increases with soil stiffness increasing but decreases with stone stiffness increasing. Numerical results are consistent with the laboratory test results of remolded samples, which indicate that this method can be a beneficial supplement to determine the parameters of engineering deposit bodies.
