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基于分期设权理想点法的水文模型参数多目标优化 被引量:5
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作者 康艳 伊丽 龚家国 《天津大学学报(自然科学与工程技术版)》 EI CSCD 北大核心 2021年第5期458-467,共10页
针对水文模型参数多目标优化问题中计算复杂且多目标之间存在相互矛盾的问题,提出了基于分期设权理想点法的水文模型参数多目标优化方法.以ABCD水文模型为月径流预报模型,构建径流总水量误差、平均相对误差、高水流量纳什效率系数和低... 针对水文模型参数多目标优化问题中计算复杂且多目标之间存在相互矛盾的问题,提出了基于分期设权理想点法的水文模型参数多目标优化方法.以ABCD水文模型为月径流预报模型,构建径流总水量误差、平均相对误差、高水流量纳什效率系数和低水流量纳什效率系数4种目标函数,采用分期设权理想点法将多目标函数转化为单目标,并采用粒子群优化算法求解目标函数.以泾河流域月径流为例,设置全时期(A)、丰水期(B)、枯水期(C)、分期模拟-组合(D)4种模拟方案,分析不同方案下模型模拟效果,结果表明:在全时期模拟方案中,相较于单目标优化方案A1~A4,多目标优化方案A5能有效地表征多个水文过程特征,协调目标函数间的互斥关系,模拟效果更优;在分期模拟方案中,目标权重为0.75时的子方案B3、C3既能合理体现目标函数表征的水文特征,又能兼顾其他目标函数,模拟效果相对最佳;丰、平、枯水期分期模拟-组合方案D对高水流量与低水流量过程模拟效果较全时期多目标优化方案的模拟效果更优,评价指标决定系数R2、效率系数Ens均达到0.8以上,平均绝对百分误差APE小于1%,说明分期模拟-组合方案D能有效提高模型模拟精度. 展开更多
关键词 水文模型参数多目标优化 分期设权理想 ABCD水文模型 径流模拟 泾河流域
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中国现当代文学批评史的分期问题 被引量:2
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作者 林炜娜 《广东第二师范学院学报》 2017年第4期33-39,共7页
目前学界对中国现当代文学批评史起点研究有着三种具有代表性的观点:"晚清说""五四说"及"20世纪整体观照说",这是研究者根据具体批评著作、文学活动或政治历史事件对文学批评发展进程所作的价值判断,体... 目前学界对中国现当代文学批评史起点研究有着三种具有代表性的观点:"晚清说""五四说"及"20世纪整体观照说",这是研究者根据具体批评著作、文学活动或政治历史事件对文学批评发展进程所作的价值判断,体现了研究者们在批评史编写过程中的分期立场和理论依据。在差异之下,建构科学合理的批评史分期需要把握三个关系:一是处理好文学批评史与文学史的关系;二是处理好批评史中断裂和继承的关系;三是把握历史的整体发展与阶段性停滞甚至后退的关系。在此基础上,可将中国现当代文学批评史以1917年王国维《<红楼梦>评论》为起点,其"现代性"特征延伸至1942年文代会的召开,20世纪40年代—70年代为当代文学批评的过渡期,1978年后进入到以多元化审美模式为特点的当代文学批评期。 展开更多
关键词 文学批评史 分期起始 质变 现代性
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故县水库汛限水位设计与运用研究 被引量:3
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作者 王玉峰 刘红珍 李保国 《人民黄河》 CAS 北大核心 2009年第2期38-40,共3页
根据地区洪水规律,通过对洛河上游暴雨洪水季节特征、分期规律的研究,结合小浪底水库初期运用的情况,提出了故县水库汛限水位设计与运用研究的思路和技术架构,重点分析了不同运用期故县水库合理的汛限水位。结果表明:将8月20日作为前、... 根据地区洪水规律,通过对洛河上游暴雨洪水季节特征、分期规律的研究,结合小浪底水库初期运用的情况,提出了故县水库汛限水位设计与运用研究的思路和技术架构,重点分析了不同运用期故县水库合理的汛限水位。结果表明:将8月20日作为前、后汛期的分期点是比较合理的;按530 m汛限水位进行防洪运用是比较安全的。 展开更多
关键词 分期洪水 分期点 模糊数学 汛限水位 兴利效益 故县水库
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分期择点穿刺法在膝骨关节炎透明质酸钠注射治疗中的应用 被引量:3
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作者 郭彦涛 杨少锋 邓博 《中国中医骨伤科杂志》 CAS 2015年第3期54-56,共3页
膝骨关节炎(osteoarthritis,OA)是一种骨伤科常见退变性疾病,研究表明:人群膝骨关节炎患病率达9.56%,老年人群则明显增高,达50%以上[1]。在膝骨关节炎的治疗方法中,关节腔注射透明质酸钠(sodium hyaluronate,SH)是一种较为常用的... 膝骨关节炎(osteoarthritis,OA)是一种骨伤科常见退变性疾病,研究表明:人群膝骨关节炎患病率达9.56%,老年人群则明显增高,达50%以上[1]。在膝骨关节炎的治疗方法中,关节腔注射透明质酸钠(sodium hyaluronate,SH)是一种较为常用的非手术治疗方法,但由于透明质酸钠注射治疗的疗程较长,穿刺次数较多,临床上常因穿刺方法不当或穿刺并发症等原因使部分患者中止治疗,影响治疗效果。 展开更多
关键词 膝骨关节炎 透明质酸钠 分期穿刺法
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Solitary Wave and Periodic Wave Solutions for the Relativistic Toda Lattices 被引量:2
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作者 MAZheng-Yi ZHUJia-Min ZHENGChun-Long 《Communications in Theoretical Physics》 SCIE CAS CSCD 2005年第1期27-30,共4页
In this work, an adaptation of the tanh/tan-method that is discussed usually in the nonlinear partial differential equations is presented to solve nonlinear polynomial differential-difference equations. As a concrete ... In this work, an adaptation of the tanh/tan-method that is discussed usually in the nonlinear partial differential equations is presented to solve nonlinear polynomial differential-difference equations. As a concrete example,several solitary wave and periodic wave solutions for the chain which is related to the relativistic Toda lattice are derived.Some systems of the differential-difference equations that can be solved using our approach are listed and a discussion is given in conclusion. 展开更多
关键词 tanh-method solitary wave and periodic wave solutions differential-difference equation Toda lattice
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Positive Periodic Solutions for Nonautonomous Differential Equations with Delay 被引量:2
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作者 PENG Shi-guo 《Chinese Quarterly Journal of Mathematics》 CSCD 北大核心 2006年第4期561-566,共6页
By utilizing a fixed point theorem on cone, some new results on the existence ofpositive periodic solutions for nonautonomous differential equations with delay are derived.
关键词 positive periodic solutions NONAUTONOMOUS differential equations with delay fixed point theorem CONE
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Quantitative Analysis on Postponement Strategies of Decoupling Points in Mass Customization
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作者 汪蓉 邵晓峰 +1 位作者 黄培清 季建华 《Journal of Donghua University(English Edition)》 EI CAS 2003年第1期74-76,共3页
The key to mass customizing effectively is postponing the deco upling point of customer order in the supply network. This paper focused on quantitative analysis on postponement strategies of multiple decoupling points... The key to mass customizing effectively is postponing the deco upling point of customer order in the supply network. This paper focused on quantitative analysis on postponement strategies of multiple decoupling points in mass customization to improve operating efficiency and quickly meet customer demands with a minimum amount of inventory. 展开更多
关键词 mass customization postponement strategy decoupling points.
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Kinetic effects of nanosecond discharge on ignition delay time
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作者 Xingqian Mao Guoxiu Li +1 位作者 Qi Chen Yujun Zhao 《Chinese Journal of Chemical Engineering》 SCIE EI CAS CSCD 2016年第12期1719-1727,共9页
The effects of nanosecond discharge on ignition characteristics of a stoichiometric methane–air mixture without inert diluent gas were studied by numerical simulation at 0.1 MPa and an initial temperature of 1300 K. ... The effects of nanosecond discharge on ignition characteristics of a stoichiometric methane–air mixture without inert diluent gas were studied by numerical simulation at 0.1 MPa and an initial temperature of 1300 K. A modified non-equilibrium plasma kinetic model was developed to simulate the temporal evolution of particles produced during nanosecond discharge and its afterglow. As important roles in ignition, path fluxes of O and H radicals were analyzed in detail. Different strength of E/N and different discharge duration were applied to the discharge process in this study. And the results presented that a deposited energy of 1–30 m J·cm^(-3) could dramatically reduce the ignition delay time. Furthermore, temperature and radicals analysis was conducted to investigate the effect of non-equilibrium plasma on production of intermediate radicals. Finally, sensitivity analysis was employed to have further understanding on ignition chemistries of the mixture under nanosecond discharge. 展开更多
关键词 Nanosecond discharge Ignition delay time Methane Kinetic modeling Numerical simulation
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Periodic Solutions of Singular Neutral Differential Systems with Infinite Delay
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作者 ZHOU Gui-fang ZHANG Hai JIANG Wei 《Chinese Quarterly Journal of Mathematics》 CSCD 2011年第1期56-60,共5页
In this paper,we discuss the periodic solutions of the nonlinear singular neutral differential systems with infinite delay.By using matrix measure and Krasnoselskii's fixed point theorem,we obtained the suffcient con... In this paper,we discuss the periodic solutions of the nonlinear singular neutral differential systems with infinite delay.By using matrix measure and Krasnoselskii's fixed point theorem,we obtained the suffcient conditions of the existence of periodic solutions. 展开更多
关键词 infinite delay degenerate differential systems periodic solutions Krasnoselskii's fixed point theorem
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Global Attractivity in a Delay Difference Equation 被引量:1
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作者 李先义 朱德明 《Journal of Mathematical Research and Exposition》 CSCD 北大核心 2003年第2期270-274,共5页
A new sufficient condition is given for the global attractivity of solutions ofthe delay difference equation xn+1= xnf(xn, zn-1), n = 0,1…,As an application, ourresults partly confirm a conjecture of G. Ladas.
关键词 delay difference equation global asymptotic stability global attractivity SEMICYCLE periodic point of prime period two.
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Theory of center-focus for a class of higher-degree critical points and infinite points 被引量:24
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作者 刘一戎 《Science China Mathematics》 SCIE 2001年第3期365-377,共13页
For the real planar autonomous differential system, the questionsof detection between center and focus, successor function, formal series, central integration, integration factor, focal values, values of singular poin... For the real planar autonomous differential system, the questionsof detection between center and focus, successor function, formal series, central integration, integration factor, focal values, values of singular point and bifurcation of limit cycles for a class of higher-degree critical points and infinite points are expounded. 展开更多
关键词 higher-degree critical infinite point center-focus bifurcation of limit cycle
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POSITIVE PERIODIC SOLUTIONS OF FIRST AND SECOND ORDER ORDINARY DIFFERENTIAL EQUATIONS 被引量:17
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作者 LIYONGXIANG 《Chinese Annals of Mathematics,Series B》 SCIE CSCD 2004年第3期413-420,共8页
In this paper the existence results of positive ω-periodic solutions are obtained forsecond order ordinary differential equation-u'(t)=f(t,u(t)) (t∈R), and also for firstorder ordinary differential equation u... In this paper the existence results of positive ω-periodic solutions are obtained forsecond order ordinary differential equation-u'(t)=f(t,u(t)) (t∈R), and also for firstorder ordinary differential equation u'(f)=f(t,u(t)) (t∈R), where f: R×R^+→Ris a continuous function which is ω-periodic in t. The discussion is based on the fixedpoint index theory in cones. 展开更多
关键词 Positive periodic solution CONE Fixed point index
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Spin Squeezing and Fixed-Point Bifurcation
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作者 黄亦筱 马健 +1 位作者 井晓幸 王晓光 《Communications in Theoretical Physics》 SCIE CAS CSCD 2012年第12期800-806,共7页
We study spin squeezing and classical bifurcation in a nonfinear bipartite system. We show that the spin squeezing can be associated with a fixed-point bifurcation in the classical dynamics, namely, it acts as an indi... We study spin squeezing and classical bifurcation in a nonfinear bipartite system. We show that the spin squeezing can be associated with a fixed-point bifurcation in the classical dynamics, namely, it acts as an indicator of the classical bifurcation. For the ground state of a system with coupled giant spins, we find that the spin squeezing achieves its minimum value near the bifurcation point. We also study the dynamics of the spin squeezing, for an initial state corresponding to one of the fixed point, we find that in the stable regime, the spin squeezing exhibits periodic oscillation and always persists except at some fixed times, while in the unstable regime, the periodic oscillation phenomenon disappears and the spin squeezing survives for a short time. Finally, we show that the mean spin squeezing, which is defined to be averaged over time, attains its minimum value near the bifurcation point. 展开更多
关键词 spin squeezing fixed point BIFURCATION
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