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不连序系列的动态加权优化适线法 被引量:1
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作者 程银才 《水电能源科学》 北大核心 2021年第8期54-56,98,共4页
针对现行水文频率计算存在的3个问题,频率曲线各段拟合精度存在差异、采用矩法计算不连序系列统计参数前提假设及区别一般洪水与特大洪水假设的合理性,针对性地提出了解决问题的方法,即采用模糊数学原理估计适线法参数初值、根据隶属度... 针对现行水文频率计算存在的3个问题,频率曲线各段拟合精度存在差异、采用矩法计算不连序系列统计参数前提假设及区别一般洪水与特大洪水假设的合理性,针对性地提出了解决问题的方法,即采用模糊数学原理估计适线法参数初值、根据隶属度大小区别特大洪水与一般洪水、依据洪水大小不同动态加权优化适线法。最后结合实例,采用加权的优化适线法进行频率计算。结果表明,所提方法可行,且精度较高,在工程实践上可参考应用。 展开更多
关键词 连序系列 加权 隶属度 优化 适线法
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关于不连序潮位系列设计潮位计算问题 被引量:5
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作者 李松仕 《水文》 CSCD 北大核心 2000年第6期21-23,61,共4页
对《堤防工程设计规范》中不连序潮位系列设计潮位计算方法进行了分析, 认为该规范中的有关规定欠妥,提出了一种正确合理的计算方法。
关键词 设计潮位 计算方法 连序潮位 钱铁公式
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论不连序系列样本概率权重矩不偏计算公式 被引量:3
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作者 李松仕 《水文》 CSCD 北大核心 1996年第3期7-12,共6页
人们普遍认为要从理论上通过数学分析的方法来论证不连序系列样本概率权重矩的偏倚性是很困难的。本文根据次序统计量理论,分析推证了不连序系列样本概率权重矩的不偏计算公式。论证结果具有较重要的理论和实用意义。
关键词 概率仅重矩 连序系列 不偏计算公式
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不连序系列双权函数法权系数的研究
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作者 许兴中 《闽江学院学报》 1995年第3期89-91,共3页
用双权函数估计不连序系列的统计参数时。
关键词 双权函数 连序系列 积分权系数
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考虑历史洪水资料的三峡水库运行期非一致性设计洪水估算
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作者 谢雨祚 郭生练 +3 位作者 熊立华 王俊 钟斯睿 杨媛婷 《水利学报》 EI CSCD 北大核心 2024年第6期643-653,共11页
水利水电工程规划设计采用单站的天然年最大洪水系列资料和P-Ⅲ型适线法推求设计洪水,确定水库特征水位。然而上游水库的建成运行,破坏了下游洪水资料系列的一致性假定。本文通过构建非一致性洪水频率分析时变矩模型,计算了长江上游重... 水利水电工程规划设计采用单站的天然年最大洪水系列资料和P-Ⅲ型适线法推求设计洪水,确定水库特征水位。然而上游水库的建成运行,破坏了下游洪水资料系列的一致性假定。本文通过构建非一致性洪水频率分析时变矩模型,计算了长江上游重点水库群的水库系数;并根据连续型随机变量分布函数单调递增的特性,提出了基于Q-Q图的时变P-Ⅲ型适线法;推求出考虑历史洪水资料的三峡水库运行期非一致性设计洪水,并与极大似然法的估算成果进行比较。结果表明:①水库系数作为时变P-Ⅲ型分布的协变量,可以反映洪水系列的非一致性变化规律;②时变P-Ⅲ型适线法侧重考虑历史洪水点据的拟合,拟合效果优于极大似然法;③相较原设计成果,三峡水库运行期1000年一遇设计洪峰Q m、洪量W 3d和W 7d削减18%左右,洪量W 15d和W 30d削减14%左右,长江上游水库群的调蓄作用直接影响三峡水库运行期的防洪库容和特征水位。 展开更多
关键词 设计洪水 非一致性 连序系列 时变矩法 水库系数 P-Ⅲ型适线法 极大似然法 三峡水库
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历史洪水在洪水序列隐含周期分析中的应用 被引量:5
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作者 朱颖元 石凝 董爱红 《灾害学》 CSCD 2004年第1期46-53,共8页
历史洪水调查是洪水序列的重要组成部分,对揭示洪水序列的周期,论证周期的稳定性和可靠性具有重要的作用。本文提出具有历史洪水调查的不连序序列三种周期分析模型,理论分析和实例计算结果表明,文中提出的模型是合理和可行的。
关键词 历史洪水 连序洪水序列 周期分析模型 功率谱方法 周期图方法 方差分析法
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对Hurwitz定理的一个推广
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作者 金珩 赵希武 《内蒙古民族大学学报》 2000年第1期49-52,共4页
本文对判别实二次型正定性的重要方法之一———Hurwitz定理做了推广 ,使得本来需从实二次型的矩阵A =(aij) n×n(A′ =A)的左上角元a11开始取从 1到n阶顺序主子式进行的判定 ,变成可以从A的主对角线上任意元aii(i =1,2 ,… ,n)开... 本文对判别实二次型正定性的重要方法之一———Hurwitz定理做了推广 ,使得本来需从实二次型的矩阵A =(aij) n×n(A′ =A)的左上角元a11开始取从 1到n阶顺序主子式进行的判定 ,变成可以从A的主对角线上任意元aii(i =1,2 ,… ,n)开始取从 1到n阶连序主子式进行判定。因此 ,本文给出的方法使用起来更为方便、灵活 。 展开更多
关键词 二次型的矩阵 正定二次型 矩阵的顺序主子式 逆序主子式 连序主子式
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几种经验频率公式适应性的分析 被引量:1
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作者 王守鹤 秦大庸 《水利水电技术》 CSCD 北大核心 1989年第5期1-3,31,共4页
一、前言由于水文特征值的不确定性,在我国的洪水频率分析中,一般采用适线法,假定洪水系列服从P-Ⅲ型分布,选用目估适线或优选适线来推求统计参数,以确定洪水设计值。因此。
关键词 洪水频率 连序系列 统计计算
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Some properties of monotone set functions defined by Choquet integral 被引量:4
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作者 欧阳耀 李军 《Journal of Southeast University(English Edition)》 EI CAS 2003年第4期423-426,共4页
In this paper, some properties of the monotone set function defined by theChoquet integral are discussed. It is shown that several important structural characteristics of theoriginal set function, such as weak null-ad... In this paper, some properties of the monotone set function defined by theChoquet integral are discussed. It is shown that several important structural characteristics of theoriginal set function, such as weak null-additivity, strong order continuity, property (s) andpseudomelric generating property, etc., are preserved by the new set function. It is also shown thatC-integrability assumption is inevitable for the preservations of strong order continuous andpseudometric generating property. 展开更多
关键词 non-additive measure monotone set function choquet integral
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设计潮位计算的算法设计与应用分析
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作者 李世才 彭月英 《水资源研究》 2002年第2期38-40,共3页
设计潮位的计算机算法,其难点是有关的表格查算和绘制频率曲线图,对极值I型分布律的λpm值表和泊松-耿贝尔复合极值分布的β值表,都可归纳为求解^-yn和σn的值,并给出整个计算过程的数学模型和算法设计简介,提出了不连序系列λpn... 设计潮位的计算机算法,其难点是有关的表格查算和绘制频率曲线图,对极值I型分布律的λpm值表和泊松-耿贝尔复合极值分布的β值表,都可归纳为求解^-yn和σn的值,并给出整个计算过程的数学模型和算法设计简介,提出了不连序系列λpn值的合理算法。用电算程序对广西沿海六个潮位站设计高(低)潮位的分析计算表明,极值I型分布具有较好的适应性。 展开更多
关键词 设计潮位 极值I型分布 连序系列 数学模型
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Improved Statistical Interconnect Timing Analysis Considering Scattering Effect
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作者 林赛华 杨华中 +1 位作者 罗嵘 汪蕙 《Journal of Semiconductors》 EI CAS CSCD 北大核心 2006年第11期1918-1922,共5页
We propose an improved statistical approach for modeling interconnect slew that takes into account the scattering effect of a nanoscale wire. We first propose a simple, closed-form scattering effect resistivity model,... We propose an improved statistical approach for modeling interconnect slew that takes into account the scattering effect of a nanoscale wire. We first propose a simple, closed-form scattering effect resistivity model, considering the effects of both width and thickness. Then we use this model to derive statistical expressions of the slew metrics using the SS2M model. We find that the delay and slew can be greatly increased when considering the scattering effect. The proposed statistical SS2M model has an average error of 4.16% with respect to SPICE Monte Carlo simulations, with an average error of standard deviation of only 3.06%. 展开更多
关键词 INTERCONNECT scatterin EFFECT timin analysis
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Concatenated Trellis Coding and CPM for DS/SSMA Communications in Rayleigh Fading Channel
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作者 仰枫帆 梁树雄 毕光国 《Journal of Southeast University(English Edition)》 EI CAS 1999年第1期9-16,共8页
In this paper, direct sequence spread spectrum multiple access (DS/SSMA) communication system employing serially concatenated trellis coded modulation (TCM) and continuous phase modulation (CPM) over flat Rayleigh fa... In this paper, direct sequence spread spectrum multiple access (DS/SSMA) communication system employing serially concatenated trellis coded modulation (TCM) and continuous phase modulation (CPM) over flat Rayleigh fading channel are presented. The performance of this concatenated TCM/CPM DS/SSMA system is exploited by the theoretical analysis and numerical simulations. The results demonstrate that significant improvements in error probability of this DS/SSMA system over the system with single TCM or CPM of different modulation indices can be achieved under the same conditions. 展开更多
关键词 concatenated TCM/CPM direct sequence spread spectrum multiple access Rayleigh fading channel
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Tuning the mechanosensitivity of a BK channel by changing the linker length 被引量:6
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作者 Hucheng Zhao 《Cell Research》 SCIE CAS CSCD 2008年第8期871-878,共8页
Some large-conductance Ca^2+ and voltage-activated K^+(BK) channels are activated by membrane stretch. However, the mechanism of mechano-gating of the BK channels is still not well understood. Previous studies hav... Some large-conductance Ca^2+ and voltage-activated K^+(BK) channels are activated by membrane stretch. However, the mechanism of mechano-gating of the BK channels is still not well understood. Previous studies have led to the proposal that the linker-gating ring complex functions as a passive spring, transducing the force generated by intracellular Ca^2+ to the gate to open the channel. This raises the question as to whether membrane stretch is also transmitted to the gate of mechanosensitive (MS) BK channels via the linker-gating complex. To study this, we changed the linker length in the stretch-activated BK channel (SAKCaC), and examined the effect of membrane stretch on the gating of the resultant mutant channels. Shortening the linker increased, whereas extending the linker reduced, the channel mechanosensitivity both in the presence and in the absence of intracellular Ca^2+. However, the voltage and Ca^2+ sensitivities were not significantly altered by membrane stretch. Furthermore, the SAKCaC became less sensitive to membrane stretch at relatively high intracellular Ca^2+ concentrations or membrane depolarization. These observations suggest that once the channel is in the open-state conformation, tension on the spring is partially released and membrane stretch is less effective. Our results are consistent with the idea that membrane stretch is transferred to the gate via the linker-gating ring complex of the MS BK channels. 展开更多
关键词 BK channel mechanosensitive channel mechano-gating HEART
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The Sequential Continuity of Multiplication on a Class of Infinite Matrix Algebras
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作者 赵玟亨 刘金霞 《Chinese Quarterly Journal of Mathematics》 CSCD 2002年第2期49-52,共4页
Let λ and μ are sequence spaces and have both the signed_weak gliding hump property, (λ,μ) be the algebra of the infinite matrix operators which transform λ into μ, in this paper, we study the strong? Mackey... Let λ and μ are sequence spaces and have both the signed_weak gliding hump property, (λ,μ) be the algebra of the infinite matrix operators which transform λ into μ, in this paper, we study the strong? Mackey? weak multiplier sequentially continuous problem of infinite matrix algebras (λ,μ). 展开更多
关键词 sequence spaecs infinite matrix MULTIPLIER sequential continuity
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Genetic programming-based chaotic time series modeling 被引量:1
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作者 张伟 吴智铭 杨根科 《Journal of Zhejiang University Science》 EI CSCD 2004年第11期1432-1439,共8页
This paper proposes a Genetic Programming-Based Modeling (GPM) algorithm on chaotic time series. GP is used here to search for appropriate model structures in function space, and the Particle Swarm Optimization (PSO) ... This paper proposes a Genetic Programming-Based Modeling (GPM) algorithm on chaotic time series. GP is used here to search for appropriate model structures in function space, and the Particle Swarm Optimization (PSO) algorithm is used for Nonlinear Parameter Estimation (NPE) of dynamic model structures. In addition, GPM integrates the results of Nonlinear Time Series Analysis (NTSA) to adjust the parameters and takes them as the criteria of established models. Experiments showed the effectiveness of such improvements on chaotic time series modeling. 展开更多
关键词 Chaotic time series analysis Genetic programming modeling Nonlinear Parameter Estimation (NPE) Particle Swarm Optimization (PSO) Nonlinear system identification
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The Extension of Continuous Measure
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作者 彭祖赠 孙韫玉 《Chinese Quarterly Journal of Mathematics》 CSCD 1992年第3期88-94,共7页
In this paper we give a sufficient and necessary condition under which a continuous measure (whose values belong to, the extended half-line (0,+∞) defined on a class of sets closed under the formation of intersection... In this paper we give a sufficient and necessary condition under which a continuous measure (whose values belong to, the extended half-line (0,+∞) defined on a class of sets closed under the formation of intersection can be extended to a smallest monotone class containing this class, and we also give a condition under which there exists a unique extension. In addition, we give a method by means of which a continuous measure on a monotone class can be extended again. 展开更多
关键词 continuous measure complete partition basic continuous extension
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On Common Fixed Point of Noncompatible Mapping Pairs 被引量:2
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作者 朱元泽 吕中学 《Journal of China University of Mining and Technology》 2002年第1期111-114,共4页
In this paper, two common fixed point theorems for noncompatible maps in a metric space have been proved under the condition of without taking completeness of the space or continuity of the mapings into account. The r... In this paper, two common fixed point theorems for noncompatible maps in a metric space have been proved under the condition of without taking completeness of the space or continuity of the mapings into account. The related common point theorems were improved. 展开更多
关键词 metric space noncompatible maps common fixed point.
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Comparative Analysis of Mitochondrial Control Region Sequence from Three Flatfish Species(Pleuronectidae)
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作者 YUJianzhong KONGXiaoyu +1 位作者 YUZiniu ZHOULishi 《Journal of Ocean University of China》 SCIE CAS 2005年第1期80-84,共5页
The 5’-end of the mitochondrial control region sequences of three flatfishes (Pleuronectiformes: Pleuronectidae) were amplified and sequenced. These sequences were compared with those of other three Pleuronectids spe... The 5’-end of the mitochondrial control region sequences of three flatfishes (Pleuronectiformes: Pleuronectidae) were amplified and sequenced. These sequences were compared with those of other three Pleuronectids species retrieved from GenBank. A phylogenetic tree was constructed based on the partial control region sequences. The results of phyloge- netic analysis are consistent with those of conventional systematics. Compared to previous studies, the structure of the 5’-end of mitochondrial control region was analyzed. The terminal associated sequence motif and its complementary motif were i- dentified at the 5’-end of the sequences. A conserved sequence block, named as CM5’d, was identified in the 5’-end of con- trol region sequences in all Pleuronectids. Another central conserved sequence block, named as CSB-F, was detected in the central conserved blocks. 展开更多
关键词 PLEURONECTIDAE FLATFISH mitochondrial control region terminal associatedsequence conserved sequence block
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Identification of connexin 50 and 57 mRNA in A-type horizontal cells of the rabbit retina
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作者 HeHUANG HuiLI ShiGangHE 《Cell Research》 SCIE CAS CSCD 2005年第3期207-211,共5页
Horizontal cells (HCs) mediate negative feedback to photoreceptors. In the mammalian retina, there are two types of HCs, which are extensively coupled to neighboring cells through homologous gap junctions. The permeab... Horizontal cells (HCs) mediate negative feedback to photoreceptors. In the mammalian retina, there are two types of HCs, which are extensively coupled to neighboring cells through homologous gap junctions. The permeability and therefore the strength of feedback can be regulated by light intensity, dopamine and many other factors. However, the component(s) of the most prominent gap junctions, those between A-type HCs in the rabbit retina, is still unknown. In this study, we compared the sequences of many types of mammalian connexins, obtained partial sequences of rabbit connexin 50 and 57. Using specific primers designed against the rabbit sequences, we identified mRNAs of connexin 50 and/or 57 in visually selected single A-type HC using multiplex RT-PCR. 展开更多
关键词 gap junctions dissociated retinal neurons single cell multiplex RT-PCR sequencing.
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Nitrogen Mineralization in Soils Along a Vegetation Chronosequence in Hong Kong 被引量:5
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作者 L.M.MARAFA K.C.CHAU 《Pedosphere》 SCIE CAS CSCD 2005年第2期181-188,共8页
This research examined nitrogen mineralization in the top 10 cm of soils along a vegetation gradient in Hong Kong at sites where fire has been absent for 0, 1, 3, 6 and 17 years (at the time of the study), and the rel... This research examined nitrogen mineralization in the top 10 cm of soils along a vegetation gradient in Hong Kong at sites where fire has been absent for 0, 1, 3, 6 and 17 years (at the time of the study), and the relationships between N mineralization and successional development of vegetation in the absence of fire. The sites including a newly burnt area (S1), short grassland (S2), tall grassland (S3), mixed tall grassland and shrubland (S4), and woodland (S5) were selected,and the in situ core incubation method was used to estimate nitrogen mineralization. Throughout the 60-day incubation in four periods, more nitrogen was mineralized at the S3 and S4 sites, the predominantly grassland sites, which contained the highest levels of soil organic matter (SOM) and total Kjeldahl nitrogen (TKN), than the S1 site, while immobilization occurred at the S2 and S5 sites. Leaching loss decreased with successional development of the vegetation, in the order of S1 > S2 > S3 > S4 > S5. The pattern of nitrogen uptake with ecological succession was less conspicuous, being complicated by the immediate effect of fire and possibly the ability of the woodland species to extract nitrogen from the deeper ground.In the absence of fire for 3 to 6 years, the build-up of SOM and TKN was accompanied by active mineralization, thus paving the way for the invasion of shrub and tree species. A close relationship existed between nitrogen mineralization and ecological succession with this vegetation gradient. Inherent mechanisms to preserve nitrogen in a fire-prone environment including immobilization and uptake and the practical relevance of nitrogen mineralization to reforestation are discussed. 展开更多
关键词 fire impact IMMOBILIZATION nitrogen mineralization successional development vegetation chronosequence
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