为捋清沿黄九省(区)水资源利用效率(water resource utilization efficiency,WRUE)的现状,明晰水资源利用效率的影响因素,助力该地区水资源的高效利用,基于全局超效率模型(global super efficiency slack based model,SBM)、层次分析法(...为捋清沿黄九省(区)水资源利用效率(water resource utilization efficiency,WRUE)的现状,明晰水资源利用效率的影响因素,助力该地区水资源的高效利用,基于全局超效率模型(global super efficiency slack based model,SBM)、层次分析法(analytical hierarchy process,AHP)和Tobit模型,从农业、工业、生活、生态和综合5个方面对水资源利用效率的变化情况和影响因素进行分析,结果表明:沿黄九省(区)农业、工业、生活、生态和综合水资源利用效率在2003−2022年的均值分别为0.417、0.511、0.635、0.465和0.506,总体均呈上升趋势。黄河中下游省(区)的农业、工业、生活和综合水资源利用效率高于上游省(区),黄河上游省(区)的生态水资源利用效率略高于中下游省(区)。人均GDP、第三产业产值占比、R&D经费投入强度与综合水资源利用效率呈正相关,人均水资源量、人口城镇化率、农业工业用水占比与其呈负相关。对沿黄九省(区)提出如下发展建议:优化产业结构和用水结构;加强水资源禀赋较好地区和城镇化水平较高地区的节水管控;沿黄西部省(区)加强与节水相关的科技创新。展开更多
水面无人艇是海上有人/无人协同作战体系中重要的一环,对装备的保障性、可维修性要求较高,因此亟需建立与其装备体系相匹配的装备保障体系。为解决水面无人艇的保障体系设计问题,应用基于模型的系统工程(Model Based System Engineering...水面无人艇是海上有人/无人协同作战体系中重要的一环,对装备的保障性、可维修性要求较高,因此亟需建立与其装备体系相匹配的装备保障体系。为解决水面无人艇的保障体系设计问题,应用基于模型的系统工程(Model Based System Engineering,MBSE)方法,面向典型应用场景构建水面无人艇装备保障体系的多视图模型,并给出水面无人艇装备保障体系在仿真推演过程中的关键要素和基本流程,初步构建可靠性-能力-效能综合评估指标体系,实现了“作战任务-保障任务-保障能力需求-保障体系结构”的闭环验证,为水面无人艇装备体系和装备保障体系的协同设计和高效运用提供参考。展开更多
该文针对传感器网络中无线链路的不稳定性问题,基于r邻居图模型提出一种具有稳定链路的鲁棒可调拓扑控制算法RAWSL(Robust Adjustable with Steady Links)。算法以接收信号强度阈值作为链路判断条件,有效地避免了网络中不稳定链路存在...该文针对传感器网络中无线链路的不稳定性问题,基于r邻居图模型提出一种具有稳定链路的鲁棒可调拓扑控制算法RAWSL(Robust Adjustable with Steady Links)。算法以接收信号强度阈值作为链路判断条件,有效地避免了网络中不稳定链路存在的可能性,并能够通过调整参数r取值满足不同网络的需求。实验结果表明,RAWSL算法不仅能够确保全网络的连通,还具有鲁棒性高和时延较低的特点。展开更多
KAg_(3)Te_(2)with a layered crystal structure has been predicted to be a possible topological insulator.Through electrical transport measurements,we revealed its semiconducting behavior with a narrow band gap of~0.4 e...KAg_(3)Te_(2)with a layered crystal structure has been predicted to be a possible topological insulator.Through electrical transport measurements,we revealed its semiconducting behavior with a narrow band gap of~0.4 eV and p-type character.The infrared transmission spectra of single crystals yielded an optical band gap of~0.3 eV.Angle-resolved photoemission spectroscopy reveals a bulk energy gap at the Brillouin zone center,with no observable surface state,suggesting that KAg_(3)Te_(2)is a topological trivial narrow-gap semiconductor.The experimentally determined effective mass of the holes in KAg_(3)Te_(2)is very small(~0.12 me).The valence band maximum is quasi-two-dimensional,while the conduction band minimum is fully three-dimensional.Such intriguing dimensional anisotropy can be attributed to the distinct orbital contributions from K,Ag,and Te atoms to the respective bands.展开更多
文摘水面无人艇是海上有人/无人协同作战体系中重要的一环,对装备的保障性、可维修性要求较高,因此亟需建立与其装备体系相匹配的装备保障体系。为解决水面无人艇的保障体系设计问题,应用基于模型的系统工程(Model Based System Engineering,MBSE)方法,面向典型应用场景构建水面无人艇装备保障体系的多视图模型,并给出水面无人艇装备保障体系在仿真推演过程中的关键要素和基本流程,初步构建可靠性-能力-效能综合评估指标体系,实现了“作战任务-保障任务-保障能力需求-保障体系结构”的闭环验证,为水面无人艇装备体系和装备保障体系的协同设计和高效运用提供参考。
文摘该文针对传感器网络中无线链路的不稳定性问题,基于r邻居图模型提出一种具有稳定链路的鲁棒可调拓扑控制算法RAWSL(Robust Adjustable with Steady Links)。算法以接收信号强度阈值作为链路判断条件,有效地避免了网络中不稳定链路存在的可能性,并能够通过调整参数r取值满足不同网络的需求。实验结果表明,RAWSL算法不仅能够确保全网络的连通,还具有鲁棒性高和时延较低的特点。
基金Project supported by the National Key Research and Development Program of China and the National Natural Science Foundation of China.
文摘KAg_(3)Te_(2)with a layered crystal structure has been predicted to be a possible topological insulator.Through electrical transport measurements,we revealed its semiconducting behavior with a narrow band gap of~0.4 eV and p-type character.The infrared transmission spectra of single crystals yielded an optical band gap of~0.3 eV.Angle-resolved photoemission spectroscopy reveals a bulk energy gap at the Brillouin zone center,with no observable surface state,suggesting that KAg_(3)Te_(2)is a topological trivial narrow-gap semiconductor.The experimentally determined effective mass of the holes in KAg_(3)Te_(2)is very small(~0.12 me).The valence band maximum is quasi-two-dimensional,while the conduction band minimum is fully three-dimensional.Such intriguing dimensional anisotropy can be attributed to the distinct orbital contributions from K,Ag,and Te atoms to the respective bands.
