Under the micro-scale condition,feature size of the channel is one of the main factors influencing the fluid flow characteristics. In printing process,ink thickness in the extrusion zone formed by two ink rollers may ...Under the micro-scale condition,feature size of the channel is one of the main factors influencing the fluid flow characteristics. In printing process,ink thickness in the extrusion zone formed by two ink rollers may reach micron scale. Compared with macroscopic fluid,the velocity field and the pressure field of fluid may change when the feature size of fluid channel reaches micron scale. In order to control printing quality,it is necessary to research the influence of feature size on ink flow characteristics in micro scale. This paper analyzes it in theory,and then numerical simulation of an ink flow model with different feature sizes is carried out in no slip condition. The influence of the feature size on the ink flow characteristics and the wall shear force are obtained. Besides,the ink flow model with different feature sizes is simulated numerically in slip condition,and the influence of feature size on ink flow characteristics is obtained. Finally,by comparing and analyzing the above results,it can be concluded that both the ink velocity and pressure at the inlet of the extrusion zone are inversely proportional to the feature sizes whether in slip condition or not. And the ink velocity in slip condition is larger than that without slip,the pressure at the inlet of the extrusion zone is less than that in no slip condition. Within the micro-scale range,the ink velocity difference between the two conditions cannot be ignored. Therefore,it is necessary to consider slip when analyzing the influence of feature size of micro-scale channel on ink flow characteristics.展开更多
Water overexploitation in the Lerma-Chapala Watershed, located in central Mexico, is linked to the development of a strong federal hydrocracy with the mission to capture as much water as possible in order to satisfy s...Water overexploitation in the Lerma-Chapala Watershed, located in central Mexico, is linked to the development of a strong federal hydrocracy with the mission to capture as much water as possible in order to satisfy social and political demands through the construction of dams and irrigation systems. The reduction in freshwater quantity and the deterioration of water quality are the outcome of industrial inflows, agriculture and urban untreated wastewater. This study has been leaded to determine hydrological, water quality, seed bioassays and the lake fisheries＇ decreases throughout its historical tendencies （1980-2004） in relation to changes in water levels. Hydrological data and water samples for chemical analysis, inorganic nutrients and seed bioassay, were taken from 10 sites alongside the river and two sites from Lake Chapala in years 2005 and 2009, the WQINsF （National Sanitation Foundation Water Quality Index） was estimated. The dissolved oxygen along the river was from anoxic （0.4） to 7 mg/L and the lake had 6.75 mg/L to 7.36 mg/L; the river had highest nutrients variations, Ntot and Ptot 1 mg/L to 〉 10 mg/L. The lake had few physicochemical variations and the lowest nutrient concentrations; WQINsF （water quality index） in the river-lake system showed very bad-bad quality and contamination in river, bad quality-light contamination in lake. Seed bioassays showed inhibition of root elongation and declining fisheries when low water levels were presented. Chapala Lake had better physicochemical and limnological conditions because of the wind action and water column mixing; in contrast the river, high hidrological variations caused by water administration in middle basin.展开更多
High-quality graphene coating was directly grown on stainless steel meshes via chemical vapor deposition process,during which the morphology of the stainless steel was transformed rugged.When the graphene-coated stain...High-quality graphene coating was directly grown on stainless steel meshes via chemical vapor deposition process,during which the morphology of the stainless steel was transformed rugged.When the graphene-coated stainless steel meshes were applied as current collectors of supercapacitors,the changes of the appearance and the graphene coating improved the contact between stainless steel meshes and the active materials,thus benefiting the performance of the supercapacitors.Furthermore,this simple method can be used to prepare the enhanced current collectors for other energy storage devices.展开更多
基金Supported by the National Natural Science Foundation of China(No.51675010)the Science and Technology Plan Project of Beijing Education Commission(No.KM201710005015)
文摘Under the micro-scale condition,feature size of the channel is one of the main factors influencing the fluid flow characteristics. In printing process,ink thickness in the extrusion zone formed by two ink rollers may reach micron scale. Compared with macroscopic fluid,the velocity field and the pressure field of fluid may change when the feature size of fluid channel reaches micron scale. In order to control printing quality,it is necessary to research the influence of feature size on ink flow characteristics in micro scale. This paper analyzes it in theory,and then numerical simulation of an ink flow model with different feature sizes is carried out in no slip condition. The influence of the feature size on the ink flow characteristics and the wall shear force are obtained. Besides,the ink flow model with different feature sizes is simulated numerically in slip condition,and the influence of feature size on ink flow characteristics is obtained. Finally,by comparing and analyzing the above results,it can be concluded that both the ink velocity and pressure at the inlet of the extrusion zone are inversely proportional to the feature sizes whether in slip condition or not. And the ink velocity in slip condition is larger than that without slip,the pressure at the inlet of the extrusion zone is less than that in no slip condition. Within the micro-scale range,the ink velocity difference between the two conditions cannot be ignored. Therefore,it is necessary to consider slip when analyzing the influence of feature size of micro-scale channel on ink flow characteristics.
文摘Water overexploitation in the Lerma-Chapala Watershed, located in central Mexico, is linked to the development of a strong federal hydrocracy with the mission to capture as much water as possible in order to satisfy social and political demands through the construction of dams and irrigation systems. The reduction in freshwater quantity and the deterioration of water quality are the outcome of industrial inflows, agriculture and urban untreated wastewater. This study has been leaded to determine hydrological, water quality, seed bioassays and the lake fisheries＇ decreases throughout its historical tendencies （1980-2004） in relation to changes in water levels. Hydrological data and water samples for chemical analysis, inorganic nutrients and seed bioassay, were taken from 10 sites alongside the river and two sites from Lake Chapala in years 2005 and 2009, the WQINsF （National Sanitation Foundation Water Quality Index） was estimated. The dissolved oxygen along the river was from anoxic （0.4） to 7 mg/L and the lake had 6.75 mg/L to 7.36 mg/L; the river had highest nutrients variations, Ntot and Ptot 1 mg/L to 〉 10 mg/L. The lake had few physicochemical variations and the lowest nutrient concentrations; WQINsF （water quality index） in the river-lake system showed very bad-bad quality and contamination in river, bad quality-light contamination in lake. Seed bioassays showed inhibition of root elongation and declining fisheries when low water levels were presented. Chapala Lake had better physicochemical and limnological conditions because of the wind action and water column mixing; in contrast the river, high hidrological variations caused by water administration in middle basin.
基金supported by the National Natural Science Foundation of China(Grant Nos.20973044,21173057,21103030)the Ministry of Science and Technology of China(Grant Nos.2012CB933400,2012CB-933403)
文摘High-quality graphene coating was directly grown on stainless steel meshes via chemical vapor deposition process,during which the morphology of the stainless steel was transformed rugged.When the graphene-coated stainless steel meshes were applied as current collectors of supercapacitors,the changes of the appearance and the graphene coating improved the contact between stainless steel meshes and the active materials,thus benefiting the performance of the supercapacitors.Furthermore,this simple method can be used to prepare the enhanced current collectors for other energy storage devices.
