黄河上游是流域主要产水区和径流年际调蓄区,其水情预报水平是决定全流域水资源利用与水安全保障的关键,为使理论研究更好地支撑工作实践,系统梳理黄河上游水情预报现状:一是基于CiteSpace软件,对1983-2024年中国知网(CNKI)和Web of Sci...黄河上游是流域主要产水区和径流年际调蓄区,其水情预报水平是决定全流域水资源利用与水安全保障的关键,为使理论研究更好地支撑工作实践,系统梳理黄河上游水情预报现状:一是基于CiteSpace软件,对1983-2024年中国知网(CNKI)和Web of Science(WoS)国内外数据库有关黄河上游水情预报的研究工作进行文献计量分析;二是梳理物理机理、数据驱动和物理-数据耦合3类预报模型在黄河上游的研究进展情况;三是总结黄河上游洪水预报与中长期径流预报两大业务的工作现状。在此基础上,从业务需求和变化形势出发,指出未来工作重点方向。结果表明:现有研究多集中于唐乃亥以上地区,对唐乃亥至兰州区间预报关注不足;研究方法以物理机理和数据驱动模型为主,耦合模型占比不足4%;尽管数据驱动模型表现满意,但耦合模型因其能够兼顾物理过程可解释与海量数据挖掘优势,表现出更大的发展潜力;未来应加强多源数据融合、径流驱动机制、超长期径流预报、工程场景变化等研究,进一步强化黄河上游水情预报对决策管理的支撑能力。展开更多
Background Although it is generally acknowledged that patients with ruptured abdominal aortic aneurysm （rAAA） obtain the greatest benefit from endovascular repair （EVAR）, convincing evidence on the medium-long ter...Background Although it is generally acknowledged that patients with ruptured abdominal aortic aneurysm （rAAA） obtain the greatest benefit from endovascular repair （EVAR）, convincing evidence on the medium-long term effect is lacking. The aim of this study was to compare and summarize published results of rAAA that underwent EVAR with open surgical repair （OSR）. Methods A search of publicly published literature was performed. Based on an inclusion and exclusion criteria, a systematic meta-analysis was undertaken to compare patient characteristics, complications, short term mortality and medium-long term outcomes. A random-effects model was used to pool the data and calculate pooled odds ratios and weighted mean differences. A quantitative method was used to analyze the differences between these two methods. Results A search of the published literature showed that fourteen English language papers comprising totally 1213 patients with rAAA （435 EVAR and 778 OSR） would be suitable for this study. Furthermore, 13 Chinese studies were included, including 267 patients with rAAA totally, among which 238 patients received operation. The endovascular method was associated with more respiratory diseases before treatment （OR=1.81, P=0.01）, while there are more patients with hemodynamic instability before treatment in OSR group （OR=1.53, P=0.031）. Mean blood transfusion was 1328 ml for EVAR and 2809 ml for OSR （weighted mean difference （WMD） 1500 ml, P=0.014）. The endovascular method was associated with a shorter stay in intensive care （WMD 2.34 days, P 〈0.001） and a shorter total post- operative stay （WMD 6.27 days, P 〈0.001）. The pooled post-operative complication rate of respiratory system and visceral ischemia seldom occurred in the EVAR group （OR=0.48, P 〈0.001 and OR=0.28, P=0.043, respectively）. The pooled 30-day mortality was 25.7% for EVAR and 39.6% for OSR, and the odds ratio was 0.53 （95% confidence interval （CI） 0.41-0.70, P 〈0.001）. There was not, however, any significant reduction in the medium-long all-cause mortality rate （HR=1.13, P=0.381） and re-intervention rate （OR= 2.19, ,~=-0.243） following EVAR. In EVAR group, nevertheless, incidence of type I endoleak was significantly lower than type II endoleak （OR=0.33, P=0.039） at late follow-up period. Conclusions On the basis of this systematic review, rAAA EVAR results in less blood use for transfusion, shorter operation time, shorter intensive care unit and hospital stays, and lower 30-day mortality. However, in the medium-long term, it is not associated with a reduction in all-cause mortality.展开更多
为了尽力消除市场力的影响,探讨电力中长期市场的机制设计问题.针对原Vickrey-Clarke-Groves(VCG)机制在双侧竞价时预算不平衡的缺陷,提出了一种基于参考价出清的VCG(reference price clearing based VickreyClarke-Groves,RPCBV)机制....为了尽力消除市场力的影响,探讨电力中长期市场的机制设计问题.针对原Vickrey-Clarke-Groves(VCG)机制在双侧竞价时预算不平衡的缺陷,提出了一种基于参考价出清的VCG(reference price clearing based VickreyClarke-Groves,RPCBV)机制.证明了RPCBV机制满足个体理性、激励相容性和(正)预算平衡性;且在大数据和重复竞价情况下,当成员报价和参考价选取分别满足适当要求和规则时,其损失的社会福利是有限或可控的.此外,RPCBV机制的计算量相比于原VCG机制减少了近一半.数值仿真表明RPCBV机制对于电力中长期市场的双侧竞价是有效的和可实施的,且进一步阐释了该交易机制的内涵和应用.展开更多
为研究中长期市场交易对现货市场运行的影响,分析发电商在现货市场中的报价策略,提出一种模拟电力现货市场发电商竞价均衡的双层优化模型和多智能体深度强化学习(multi-agent deep reinforcement learning,MADRL)求解算法。引入供需比...为研究中长期市场交易对现货市场运行的影响,分析发电商在现货市场中的报价策略,提出一种模拟电力现货市场发电商竞价均衡的双层优化模型和多智能体深度强化学习(multi-agent deep reinforcement learning,MADRL)求解算法。引入供需比表征现货市场供需关系,并使用前景理论刻画发电商的有限理性行为特征,以此分析中长期市场交易对现货市场中发电商报价策略的影响。在MADRL求解过程中,将发电商建模为智能体,现货市场出清建模为环境,通过迭代求解得到均衡状态下各发电商的报价策略和现货市场出清价格。以中国东部区域包含8家发电商的实际电力系统为例开展仿真,结果表明,该MADRL算法可以有效求解各发电商的报价策略,准确模拟不同中长期市场设置对现货市场运行的影响。研究结论可为电力交易机构评估发电商竞价行为和制定市场规则提供参考依据。展开更多
文摘黄河上游是流域主要产水区和径流年际调蓄区,其水情预报水平是决定全流域水资源利用与水安全保障的关键,为使理论研究更好地支撑工作实践,系统梳理黄河上游水情预报现状:一是基于CiteSpace软件,对1983-2024年中国知网(CNKI)和Web of Science(WoS)国内外数据库有关黄河上游水情预报的研究工作进行文献计量分析;二是梳理物理机理、数据驱动和物理-数据耦合3类预报模型在黄河上游的研究进展情况;三是总结黄河上游洪水预报与中长期径流预报两大业务的工作现状。在此基础上,从业务需求和变化形势出发,指出未来工作重点方向。结果表明:现有研究多集中于唐乃亥以上地区,对唐乃亥至兰州区间预报关注不足;研究方法以物理机理和数据驱动模型为主,耦合模型占比不足4%;尽管数据驱动模型表现满意,但耦合模型因其能够兼顾物理过程可解释与海量数据挖掘优势,表现出更大的发展潜力;未来应加强多源数据融合、径流驱动机制、超长期径流预报、工程场景变化等研究,进一步强化黄河上游水情预报对决策管理的支撑能力。
基金This work was supported by Science Foundation of China grants from the National Natural （No. 304717076）, the Department of Education of Liaoning Province （Key Laboratory Project No. LS2010172）, and Ministry of Education of China （Key Research Project of Science and Technology No. 208028）.
文摘Background Although it is generally acknowledged that patients with ruptured abdominal aortic aneurysm （rAAA） obtain the greatest benefit from endovascular repair （EVAR）, convincing evidence on the medium-long term effect is lacking. The aim of this study was to compare and summarize published results of rAAA that underwent EVAR with open surgical repair （OSR）. Methods A search of publicly published literature was performed. Based on an inclusion and exclusion criteria, a systematic meta-analysis was undertaken to compare patient characteristics, complications, short term mortality and medium-long term outcomes. A random-effects model was used to pool the data and calculate pooled odds ratios and weighted mean differences. A quantitative method was used to analyze the differences between these two methods. Results A search of the published literature showed that fourteen English language papers comprising totally 1213 patients with rAAA （435 EVAR and 778 OSR） would be suitable for this study. Furthermore, 13 Chinese studies were included, including 267 patients with rAAA totally, among which 238 patients received operation. The endovascular method was associated with more respiratory diseases before treatment （OR=1.81, P=0.01）, while there are more patients with hemodynamic instability before treatment in OSR group （OR=1.53, P=0.031）. Mean blood transfusion was 1328 ml for EVAR and 2809 ml for OSR （weighted mean difference （WMD） 1500 ml, P=0.014）. The endovascular method was associated with a shorter stay in intensive care （WMD 2.34 days, P 〈0.001） and a shorter total post- operative stay （WMD 6.27 days, P 〈0.001）. The pooled post-operative complication rate of respiratory system and visceral ischemia seldom occurred in the EVAR group （OR=0.48, P 〈0.001 and OR=0.28, P=0.043, respectively）. The pooled 30-day mortality was 25.7% for EVAR and 39.6% for OSR, and the odds ratio was 0.53 （95% confidence interval （CI） 0.41-0.70, P 〈0.001）. There was not, however, any significant reduction in the medium-long all-cause mortality rate （HR=1.13, P=0.381） and re-intervention rate （OR= 2.19, ,~=-0.243） following EVAR. In EVAR group, nevertheless, incidence of type I endoleak was significantly lower than type II endoleak （OR=0.33, P=0.039） at late follow-up period. Conclusions On the basis of this systematic review, rAAA EVAR results in less blood use for transfusion, shorter operation time, shorter intensive care unit and hospital stays, and lower 30-day mortality. However, in the medium-long term, it is not associated with a reduction in all-cause mortality.
文摘为了尽力消除市场力的影响,探讨电力中长期市场的机制设计问题.针对原Vickrey-Clarke-Groves(VCG)机制在双侧竞价时预算不平衡的缺陷,提出了一种基于参考价出清的VCG(reference price clearing based VickreyClarke-Groves,RPCBV)机制.证明了RPCBV机制满足个体理性、激励相容性和(正)预算平衡性;且在大数据和重复竞价情况下,当成员报价和参考价选取分别满足适当要求和规则时,其损失的社会福利是有限或可控的.此外,RPCBV机制的计算量相比于原VCG机制减少了近一半.数值仿真表明RPCBV机制对于电力中长期市场的双侧竞价是有效的和可实施的,且进一步阐释了该交易机制的内涵和应用.
文摘为研究中长期市场交易对现货市场运行的影响,分析发电商在现货市场中的报价策略,提出一种模拟电力现货市场发电商竞价均衡的双层优化模型和多智能体深度强化学习(multi-agent deep reinforcement learning,MADRL)求解算法。引入供需比表征现货市场供需关系,并使用前景理论刻画发电商的有限理性行为特征,以此分析中长期市场交易对现货市场中发电商报价策略的影响。在MADRL求解过程中,将发电商建模为智能体,现货市场出清建模为环境,通过迭代求解得到均衡状态下各发电商的报价策略和现货市场出清价格。以中国东部区域包含8家发电商的实际电力系统为例开展仿真,结果表明,该MADRL算法可以有效求解各发电商的报价策略,准确模拟不同中长期市场设置对现货市场运行的影响。研究结论可为电力交易机构评估发电商竞价行为和制定市场规则提供参考依据。
