Desalination by freezing/thawing method was a very important method to obtain fresh water from seawater.In this work,desalination by freezing/thawing method was conducted with initial sodium chloride of 3.5 wt% in con...Desalination by freezing/thawing method was a very important method to obtain fresh water from seawater.In this work,desalination by freezing/thawing method was conducted with initial sodium chloride of 3.5 wt% in consideration of stirring speed,freezing time and subcooling.The subcooling ranged from 1.2 K to 4 K.The optimum conditions for desalination in this work were stirring speed of 200 r·min^−1,freezing time of 120 min,and subcooling of 3 K.The results also showed that sodiumchloride cannot be effectively removed by once freezing/thawing process.The maximumremoval efficiency of sodiumchloride was 64.3%.Two major reasons resulting in the impurity of obtained melted water by freezing/thawing method were proposed.The first reason was the inevitable adhesion of salt solution to the surface of ice,which could be removed easily by distilled water flushing.The second reason was that salt solution was heterogeneously wrapped in the accumulated ice,which was difficult to be removed by distilled water flushing.The liquid flushing method was proposed to verify the conjecture,and the results were in accordance with the two reasons mentioned above.Additional method,such as multiple flushing liquid method,was suggested to be used during the freezing/thawing process for effectively removing sodium chloride,and obtaining fresh water.展开更多
This report draws on data from two articles published by the Center for Teacher Education Research of Beijing Normal University,namely,“Survey Report on the Status Quo of Online Teaching and Related Needs Among Eleme...This report draws on data from two articles published by the Center for Teacher Education Research of Beijing Normal University,namely,“Survey Report on the Status Quo of Online Teaching and Related Needs Among Elementary and Secondary Schools During COVID-19 Prevention and Control:Based on a Sample Survey on School Principals in China”and“Survey Report on the Status Quo of Online Teaching and Related Needs Among Elementary and Secondary School Teachers During COVID-19 Prevention and Control:Based on a Sample Survey on Teachers in China.”展开更多
基金supported by the National Natural Science Foundation of China(21908116)the Hunan Provincial Natural Science Foundation of China(2019JJ50567)+3 种基金the projects of the Education Department of Hunan Province(17A199)the Key Laboratory of Ocean Energy Utilization and Energy Conservation of Ministry of Education(LOEC-201809)Scientific Research Foundation of Xiangnan University for High-Level TalentsDevelopment and application of nonferrous metal functional materials team.
文摘Desalination by freezing/thawing method was a very important method to obtain fresh water from seawater.In this work,desalination by freezing/thawing method was conducted with initial sodium chloride of 3.5 wt% in consideration of stirring speed,freezing time and subcooling.The subcooling ranged from 1.2 K to 4 K.The optimum conditions for desalination in this work were stirring speed of 200 r·min^−1,freezing time of 120 min,and subcooling of 3 K.The results also showed that sodiumchloride cannot be effectively removed by once freezing/thawing process.The maximumremoval efficiency of sodiumchloride was 64.3%.Two major reasons resulting in the impurity of obtained melted water by freezing/thawing method were proposed.The first reason was the inevitable adhesion of salt solution to the surface of ice,which could be removed easily by distilled water flushing.The second reason was that salt solution was heterogeneously wrapped in the accumulated ice,which was difficult to be removed by distilled water flushing.The liquid flushing method was proposed to verify the conjecture,and the results were in accordance with the two reasons mentioned above.Additional method,such as multiple flushing liquid method,was suggested to be used during the freezing/thawing process for effectively removing sodium chloride,and obtaining fresh water.
基金Project“How to improve teacher preparation quality”supported by National Natural Science Foundation of China(71974016)Project“How to prepare a good teacher”funded the International Joint Research Project of Faculty of Education,Beijing Normal University(CER201905).
文摘This report draws on data from two articles published by the Center for Teacher Education Research of Beijing Normal University,namely,“Survey Report on the Status Quo of Online Teaching and Related Needs Among Elementary and Secondary Schools During COVID-19 Prevention and Control:Based on a Sample Survey on School Principals in China”and“Survey Report on the Status Quo of Online Teaching and Related Needs Among Elementary and Secondary School Teachers During COVID-19 Prevention and Control:Based on a Sample Survey on Teachers in China.”
