单一脂肪酸的相变温度普遍较高且易泄漏,不能满足其作为相变材料对夏季建筑空调能耗调节的需求。本工作基于真实溶剂类导体屏蔽模型(conductor-like screening model for real solvents,COSMO-RS),采用COSMOthermX软件对7种中链脂肪酸...单一脂肪酸的相变温度普遍较高且易泄漏,不能满足其作为相变材料对夏季建筑空调能耗调节的需求。本工作基于真实溶剂类导体屏蔽模型(conductor-like screening model for real solvents,COSMO-RS),采用COSMOthermX软件对7种中链脂肪酸和10种长链脂肪酸两两组合的136种二元低共熔脂肪酸进行设计计算,筛选预测其共熔温度与摩尔比。进而将最优组合作为芯材,三聚氰胺-尿素-甲醛树脂(MUF)为壁材,通过原位聚合法制备相变微胶囊,系统地探讨不同工艺条件(芯壁比、反应温度、反应时间和反应转速等)对该微胶囊热物理性能的影响。结果表明:COSMO-RS模型可以直观地判断材料氢键供体(hydrogen bond donor,HBD)与受体(hydrogen bond acceptor,HBA)之间的关系,最优组合月桂酸(lauric acid,LA)与肉豆蔻酸(myristic acid,MA)摩尔比为0.66∶0.34的LA-MA(LM)理论共熔温度(33.25℃)与实验结果(33.1℃)相似度达98.08%;在芯壁比2∶1、反应时间3 h、反应温度80℃、搅拌转速200 r/min的条件下,MUF对芯材LM的包覆效率为61.37%,较好地解决了泄漏问题,对降低建筑空调制冷能耗具有潜在的应用价值。展开更多
Most forest fires in the Margalla Hills are related to human activities and socioeconomic factors are essential to assess their likelihood of occurrence.This study considers both environmental(altitude,precipitation,f...Most forest fires in the Margalla Hills are related to human activities and socioeconomic factors are essential to assess their likelihood of occurrence.This study considers both environmental(altitude,precipitation,forest type,terrain and humidity index)and socioeconomic(population density,distance from roads and urban areas)factors to analyze how human behavior affects the risk of forest fires.Maximum entropy(Maxent)modelling and random forest(RF)machine learning methods were used to predict the probability and spatial diffusion patterns of forest fires in the Margalla Hills.The receiver operating characteristic(ROC)curve and the area under the ROC curve(AUC)were used to compare the models.We studied the fire history from 1990 to 2019 to establish the relationship between the probability of forest fire and environmental and socioeconomic changes.Using Maxent,the AUC fire probability values for the 1999 s,2009 s,and 2019 s were 0.532,0.569,and 0.518,respectively;using RF,they were 0.782,0.825,and 0.789,respectively.Fires were mainly distributed in urban areas and their probability of occurrence was related to accessibility and human behaviour/activity.AUC principles for validation were greater in the random forest models than in the Maxent models.Our results can be used to establish preventive measures to reduce risks of forest fires by considering socio-economic and environmental conditions.展开更多
文摘单一脂肪酸的相变温度普遍较高且易泄漏,不能满足其作为相变材料对夏季建筑空调能耗调节的需求。本工作基于真实溶剂类导体屏蔽模型(conductor-like screening model for real solvents,COSMO-RS),采用COSMOthermX软件对7种中链脂肪酸和10种长链脂肪酸两两组合的136种二元低共熔脂肪酸进行设计计算,筛选预测其共熔温度与摩尔比。进而将最优组合作为芯材,三聚氰胺-尿素-甲醛树脂(MUF)为壁材,通过原位聚合法制备相变微胶囊,系统地探讨不同工艺条件(芯壁比、反应温度、反应时间和反应转速等)对该微胶囊热物理性能的影响。结果表明:COSMO-RS模型可以直观地判断材料氢键供体(hydrogen bond donor,HBD)与受体(hydrogen bond acceptor,HBA)之间的关系,最优组合月桂酸(lauric acid,LA)与肉豆蔻酸(myristic acid,MA)摩尔比为0.66∶0.34的LA-MA(LM)理论共熔温度(33.25℃)与实验结果(33.1℃)相似度达98.08%;在芯壁比2∶1、反应时间3 h、反应温度80℃、搅拌转速200 r/min的条件下,MUF对芯材LM的包覆效率为61.37%,较好地解决了泄漏问题,对降低建筑空调制冷能耗具有潜在的应用价值。
基金supported by the National Key Research and Development Program of China(Grant No.2019YFE0127700)。
文摘Most forest fires in the Margalla Hills are related to human activities and socioeconomic factors are essential to assess their likelihood of occurrence.This study considers both environmental(altitude,precipitation,forest type,terrain and humidity index)and socioeconomic(population density,distance from roads and urban areas)factors to analyze how human behavior affects the risk of forest fires.Maximum entropy(Maxent)modelling and random forest(RF)machine learning methods were used to predict the probability and spatial diffusion patterns of forest fires in the Margalla Hills.The receiver operating characteristic(ROC)curve and the area under the ROC curve(AUC)were used to compare the models.We studied the fire history from 1990 to 2019 to establish the relationship between the probability of forest fire and environmental and socioeconomic changes.Using Maxent,the AUC fire probability values for the 1999 s,2009 s,and 2019 s were 0.532,0.569,and 0.518,respectively;using RF,they were 0.782,0.825,and 0.789,respectively.Fires were mainly distributed in urban areas and their probability of occurrence was related to accessibility and human behaviour/activity.AUC principles for validation were greater in the random forest models than in the Maxent models.Our results can be used to establish preventive measures to reduce risks of forest fires by considering socio-economic and environmental conditions.
