Groundwater reservoir is a kind of important engineering, which can optimize water resources arran- gement by means of artificial regulation. Regulated water is the blood and value performance of groundwater reservoir...Groundwater reservoir is a kind of important engineering, which can optimize water resources arran- gement by means of artificial regulation. Regulated water is the blood and value performance of groundwater reservoir. To resolve the problem of real-time quantification of regulated water, the paper analyzed sources and compositions of regulated water in detail. Then, under the conditions of satisfying water demand inside research area, the paper analyzed quantity available and regulation coefficient of different regulated water and established a formula to calculate regulated water. At last, based on a pore groundwater reservoir in the middle reaches of the Yinma River, Jilin Province, the paper calculated regulated water with the formula and the result shows that the method is feasible. With some constraint conditions, the formula can be adopted in other similar areas.展开更多
An effective regulation of the magnetism and interface of ferromagnetic materials is not only of great scientific significance,but also has an urgent need in modern industry.In this work,by using the first-principles ...An effective regulation of the magnetism and interface of ferromagnetic materials is not only of great scientific significance,but also has an urgent need in modern industry.In this work,by using the first-principles calculations,we demonstrate an effective approach to achieve non-volatile electrical control of ferromagnets,which proves this idea in multiferroic heterostructures of ferromagnetic La TiO_(3)and ferroelectric Bi FeO_(3).The results show that the magnetic properties and two-dimensional electron gas concentrations of La TiO_(3)films can be controlled by changing the polarization directions of Bi FeO_(3).The destroyed symmetry being introduced by ferroelectric polarization of the system leads to the transfer and reconstruction of the Ti-3 d electrons,which is the fundamental reason for the changing of magnetic properties.This multiferroic heterostructures will pave the way for non-volatile electrical control of ferromagnets and have potential applications.展开更多
气候变化下台风风暴潮出现频次增加,形成的暴雨洪水对水库大坝安全产生极大威胁。由于部分地区实测流量资料缺少,基于雨量资料的随机模型与水文模型耦合模拟洪水过程线的研究亟待发展。针对现有小流域流量资料缺少问题,研究了基于降雨...气候变化下台风风暴潮出现频次增加,形成的暴雨洪水对水库大坝安全产生极大威胁。由于部分地区实测流量资料缺少,基于雨量资料的随机模型与水文模型耦合模拟洪水过程线的研究亟待发展。针对现有小流域流量资料缺少问题,研究了基于降雨随机模型与水文模型的Copula-LM-HMS耦联模型,来模拟入库洪水并计算水库大坝洪水漫顶风险率。该模型通过Copula函数与拉丁超立方-蒙特卡罗抽样(Latin Hypercube-Monte Carlo Simulation)生成流域多组7日降雨数据,并通过变倍比放大法缩放处理得到相应降雨序列,利用HEC-HMS水文模型模拟洪水过程线并结合调洪演算得到坝前最高水位,同时考虑风浪作用来模拟台风情景下的库水位变化情况,计算大坝洪水漫顶风险率,并分析不同组合条件对洪水漫顶风险率的影响。余姚市四明湖水库实例分析表明,构建的Copula-LM-HMS耦合模型计算得到的拦河坝在未来台风情境下无漫顶风险,自溃坝最小漫顶风险为0.22%,最大漫顶风险达到2.68%;洪水漫顶风险与降雨分布及起调水位有关,同时风浪作用对洪水漫顶风险影响较大。基于耦合模型进行中小流域洪水漫顶风险率计算,不仅能考虑降雨系列之间的相关性、流域地形特征与实际调洪规则,还可延长无流量资料地区水库大坝应对台风情境下洪水风险的预报期,为保证水库大坝应对未来气候变化影响下的运行安全提供参考。展开更多
The performance of lithium-sulfur batteries is deteriorated by the inferior conductivity of sulfur,the shuttle effect of lithium polysulfides(LiPSs),sluggish redox kinetics of polysulfide intermediates and serious vol...The performance of lithium-sulfur batteries is deteriorated by the inferior conductivity of sulfur,the shuttle effect of lithium polysulfides(LiPSs),sluggish redox kinetics of polysulfide intermediates and serious volumetric expansion of sulfur.To overcome these challenges,we report a versatile route to prepare multi-functional nanocomposites with tuable hierarchical structure via ammonium hydroxide(NH_(3)·H_(2) O)induced self-assembly.The versatility of the system has been demonstrated that the organization of the hierarchical structure can be regulated by adding different amounts of NH_(3)·H_(2) O,and WS_(2) and Co_(9)S_(8) with nitrogen-doped carbon coating(denoted as WS_(2)@NC and Co_(9)S_(8)@NC)can be prepared by adding different precursor salts.When the as-prepared materials are applied for Li-S batteries,the WS_(2)@NC composite exhibits a reversible capacity of 1107.4 mAh g^(-1) at 0.1 C after 500 cycles and even 728.9 mAh g^(-1) at2 C for 1000 cycles,which is significantly better than the Co_(9)S_(8) counterpart and other reported WS_(2) sulfur hosts.Experimentally,the advantageous performance of WS_(2) could be attributed to its higher surface area and total pore volume,giving rise to the easier access to electrolyte and better ability to buffer the volume change during the charge/discharge process.Theoretically,the density function theory(DFT)calculation reveals that the as-prepared WS_(2) has a higher binding energy towards LiPSs as well as a lower energy barrier for Li^(+)diffusion on the surface than Co_(9)S_(8).More significantly,the density of states(DOS)analysis further confirms that the superior performance is mainly ascribed to the more prominent shifting and the more charge compensation from d band of W than Co,which increase electronic concentration and give more hybridization of d-p orbitals in the Fermi level of the adsorbed Li2 S4 to accelerate the lithium polysulfide interfacial redox and conversion dynamics in WS_(2).By proposing this mechanism,this work sheds new light on the understanding of catalytic conversion of lithium polysulfides at the atomic level and the strategy to develop advanced cathode materials for high-performance lithium-sulfur batteries.展开更多
基金Under the auspices of Scientific & Technological Development Project of Science & Technology Office, JilinProvince (No. 200104032)
文摘Groundwater reservoir is a kind of important engineering, which can optimize water resources arran- gement by means of artificial regulation. Regulated water is the blood and value performance of groundwater reservoir. To resolve the problem of real-time quantification of regulated water, the paper analyzed sources and compositions of regulated water in detail. Then, under the conditions of satisfying water demand inside research area, the paper analyzed quantity available and regulation coefficient of different regulated water and established a formula to calculate regulated water. At last, based on a pore groundwater reservoir in the middle reaches of the Yinma River, Jilin Province, the paper calculated regulated water with the formula and the result shows that the method is feasible. With some constraint conditions, the formula can be adopted in other similar areas.
基金the National Natural Science Foundation of China(Grant No.12047517)the International Cooperation Project of Science and Technology of Henan Province,China(Grant No.182102410096)+1 种基金the Natural Science Foundation of Henan Province,China(Grant No.202300410069)the China Postdoctoral Science Foundation(Grant Nos.2020M682274 and 2020TQ0089)。
文摘An effective regulation of the magnetism and interface of ferromagnetic materials is not only of great scientific significance,but also has an urgent need in modern industry.In this work,by using the first-principles calculations,we demonstrate an effective approach to achieve non-volatile electrical control of ferromagnets,which proves this idea in multiferroic heterostructures of ferromagnetic La TiO_(3)and ferroelectric Bi FeO_(3).The results show that the magnetic properties and two-dimensional electron gas concentrations of La TiO_(3)films can be controlled by changing the polarization directions of Bi FeO_(3).The destroyed symmetry being introduced by ferroelectric polarization of the system leads to the transfer and reconstruction of the Ti-3 d electrons,which is the fundamental reason for the changing of magnetic properties.This multiferroic heterostructures will pave the way for non-volatile electrical control of ferromagnets and have potential applications.
文摘气候变化下台风风暴潮出现频次增加,形成的暴雨洪水对水库大坝安全产生极大威胁。由于部分地区实测流量资料缺少,基于雨量资料的随机模型与水文模型耦合模拟洪水过程线的研究亟待发展。针对现有小流域流量资料缺少问题,研究了基于降雨随机模型与水文模型的Copula-LM-HMS耦联模型,来模拟入库洪水并计算水库大坝洪水漫顶风险率。该模型通过Copula函数与拉丁超立方-蒙特卡罗抽样(Latin Hypercube-Monte Carlo Simulation)生成流域多组7日降雨数据,并通过变倍比放大法缩放处理得到相应降雨序列,利用HEC-HMS水文模型模拟洪水过程线并结合调洪演算得到坝前最高水位,同时考虑风浪作用来模拟台风情景下的库水位变化情况,计算大坝洪水漫顶风险率,并分析不同组合条件对洪水漫顶风险率的影响。余姚市四明湖水库实例分析表明,构建的Copula-LM-HMS耦合模型计算得到的拦河坝在未来台风情境下无漫顶风险,自溃坝最小漫顶风险为0.22%,最大漫顶风险达到2.68%;洪水漫顶风险与降雨分布及起调水位有关,同时风浪作用对洪水漫顶风险影响较大。基于耦合模型进行中小流域洪水漫顶风险率计算,不仅能考虑降雨系列之间的相关性、流域地形特征与实际调洪规则,还可延长无流量资料地区水库大坝应对台风情境下洪水风险的预报期,为保证水库大坝应对未来气候变化影响下的运行安全提供参考。
基金financially supported by National Key Research and Development Program(2018YFB1502503)Fundamental Research Funds for the Central Universities(ZYGX2019J030)Sichuan Science and Technology Program(2020YJ0299)。
文摘The performance of lithium-sulfur batteries is deteriorated by the inferior conductivity of sulfur,the shuttle effect of lithium polysulfides(LiPSs),sluggish redox kinetics of polysulfide intermediates and serious volumetric expansion of sulfur.To overcome these challenges,we report a versatile route to prepare multi-functional nanocomposites with tuable hierarchical structure via ammonium hydroxide(NH_(3)·H_(2) O)induced self-assembly.The versatility of the system has been demonstrated that the organization of the hierarchical structure can be regulated by adding different amounts of NH_(3)·H_(2) O,and WS_(2) and Co_(9)S_(8) with nitrogen-doped carbon coating(denoted as WS_(2)@NC and Co_(9)S_(8)@NC)can be prepared by adding different precursor salts.When the as-prepared materials are applied for Li-S batteries,the WS_(2)@NC composite exhibits a reversible capacity of 1107.4 mAh g^(-1) at 0.1 C after 500 cycles and even 728.9 mAh g^(-1) at2 C for 1000 cycles,which is significantly better than the Co_(9)S_(8) counterpart and other reported WS_(2) sulfur hosts.Experimentally,the advantageous performance of WS_(2) could be attributed to its higher surface area and total pore volume,giving rise to the easier access to electrolyte and better ability to buffer the volume change during the charge/discharge process.Theoretically,the density function theory(DFT)calculation reveals that the as-prepared WS_(2) has a higher binding energy towards LiPSs as well as a lower energy barrier for Li^(+)diffusion on the surface than Co_(9)S_(8).More significantly,the density of states(DOS)analysis further confirms that the superior performance is mainly ascribed to the more prominent shifting and the more charge compensation from d band of W than Co,which increase electronic concentration and give more hybridization of d-p orbitals in the Fermi level of the adsorbed Li2 S4 to accelerate the lithium polysulfide interfacial redox and conversion dynamics in WS_(2).By proposing this mechanism,this work sheds new light on the understanding of catalytic conversion of lithium polysulfides at the atomic level and the strategy to develop advanced cathode materials for high-performance lithium-sulfur batteries.
