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基于多重点云与分级聚合的全级配混凝土三维细观结构高效生成方法 被引量:2
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作者 徐磊 姜磊 +1 位作者 周昌巧 任青文 《水利学报》 EI CSCD 北大核心 2022年第2期188-199,共12页
本文提出了一种高骨料含量全级配混凝土三维细观结构高效生成方法。通过建立包含各粒级随机骨料的分级骨料库,实现了所需骨料的快速选取;提出在连续投放域内构建具有空间结构的多重点云,大幅提高了全级配混凝土三维细观结构的生成效率;... 本文提出了一种高骨料含量全级配混凝土三维细观结构高效生成方法。通过建立包含各粒级随机骨料的分级骨料库,实现了所需骨料的快速选取;提出在连续投放域内构建具有空间结构的多重点云,大幅提高了全级配混凝土三维细观结构的生成效率;通过骨料分级聚合弥补了各粒级中少量骨料投放失败造成的骨料体积损失。实例以及与其他方法的对比分析表明,采用本文方法可在满足设计级配要求的前提下,高效生成骨料体积含量达60%以上的全级配混凝土三维细观结构,为开展全级配混凝土细观精细仿真奠定了基础。 展开更多
关键词 全级配混凝土 三维细观结构 多重点 分级聚合
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多维非退化扩散过程的多重时集与多重点集的不可能性
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作者 杨新建 《湖南师范大学自然科学学报》 CAS 北大核心 2007年第1期1-4,共4页
设dX(t)=σ(X(t))dB(t)+β(X(t))dt为一非退化d(d≥3)维扩散过程.证明了:(i)3维非退化扩散过程没有4重时集和4重点集;(ii)4维非退化扩散过程没有3重时集和3重点集;(iii)5维以上的非退化扩散过程没有2重时集和2重点集.
关键词 扩散过程 BROWN运动 多重时集 多重点
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关于参数曲线的多重点讨论
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作者 张府柱 《六盘水师范学院学报》 2014年第4期78-80,共3页
由参数方程表示的曲线在积分学中占有重要地位,它和定积分的换元积分法的密切联系。在求由参数曲线所围平面图形面积时,积分限的确定是一个难点,它与参数曲线的多重点息息相关。
关键词 参数曲线 参数方程 多重点
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求解全局最优问题的多重点样本水平值估计的相对熵算法 被引量:3
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作者 周心怡 汪可 +1 位作者 邬冬华 汪晨 《运筹学学报》 北大核心 2019年第1期15-27,共13页
研究有界闭箱约束下的全局最优化问题,利用相对熵及广义方差函数方程的最大根与全局最小值之间的等价关系,设计求解全局最优值的积分型水平值估计算法.对采用重点样本采样技巧产生的函数值按一定规则进行聚类,从而在各聚类中产生的若干... 研究有界闭箱约束下的全局最优化问题,利用相对熵及广义方差函数方程的最大根与全局最小值之间的等价关系,设计求解全局最优值的积分型水平值估计算法.对采用重点样本采样技巧产生的函数值按一定规则进行聚类,从而在各聚类中产生的若干新重点样本,结合相对熵算法,构造出多重点样本进行全局搜索的新算法.该算法的优点在于每次迭代选用当前较好的函数值信息,以达到随机搜索到更好的函数值信息.同时多重点样本可有利挖掘出更好的全局信息.一系列的数值实验表明该算法是非常有效的. 展开更多
关键词 广义变差函数 多重点样本 水平值估计算法 相对熵算法
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基于三阶段故障过程的多重点检策略优化模型 被引量:16
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作者 王文彬 赵斐 彭锐 《系统工程理论与实践》 EI CSSCI CSCD 北大核心 2014年第1期223-232,共10页
针对工程系统检测中常采用小检和大检相结合的方式,在基于三阶段故障延迟时间的概念上提出了多重点检策略.三阶段故障延迟时间的概念将系统的寿命分为三阶段,即,正常,初始缺陷和严重缺陷阶段.通过考虑故障更新,小检更新和大检更新,采用... 针对工程系统检测中常采用小检和大检相结合的方式,在基于三阶段故障延迟时间的概念上提出了多重点检策略.三阶段故障延迟时间的概念将系统的寿命分为三阶段,即,正常,初始缺陷和严重缺陷阶段.通过考虑故障更新,小检更新和大检更新,采用更新收益理论对单部件系统建立了一个多重点检策略模型.该模型以小检和大检间隔期为决策变量,单位时间内的期望费用最小为决策目标.为了分析多重点检策略的有效性,本文也建立了一个对应的仅含有大检的单一点检策略模型,并通过将这两种策略模型进行比较得出了多重点检优于单一点检的小检成本的临界阈值表达式,最后通过算例进行了分析.结果证明:在其他参数不变的情况下,当小检成本小于阈值时多重点检策略是最优的. 展开更多
关键词 延迟时间 三阶段的故障过程 预防性维修 多重点
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多重点击反应制备拓扑结构聚合物 被引量:2
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作者 易超 韩骞 熊兴泉 《高分子学报》 SCIE CAS CSCD 北大核心 2014年第5期584-603,共20页
点击反应由Sharpless提出,是一类具有高效、可靠、高选择性等特点的反应,被广泛用于各种拓扑结构聚合物的制备.目前,应用较为广泛的点击反应主要有Cu(I)催化的叠氮/炔环加成反应(CuAAC)、Diels-Alder(D-A)反应、巯基-烯及巯基-炔点击反... 点击反应由Sharpless提出,是一类具有高效、可靠、高选择性等特点的反应,被广泛用于各种拓扑结构聚合物的制备.目前,应用较为广泛的点击反应主要有Cu(I)催化的叠氮/炔环加成反应(CuAAC)、Diels-Alder(D-A)反应、巯基-烯及巯基-炔点击反应和氮氧自由基偶合反应.近年来,将多种点击反应结合起来,为高效合成拓扑结构聚合物提供了新的思路.本文综述了近几年来采用多重点击反应策略联用制备拓扑结构聚合物的研究进展,并对其发展趋势进行展望. 展开更多
关键词 点击反应 多重点击反应 拓扑结构聚合物 联用 活性聚合
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均匀流中等源强相同浸没深度点源自由面波高数值模拟 被引量:1
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作者 窦依琳 罗志强 《应用数学和力学》 CSCD 北大核心 2020年第9期1026-1035,共10页
该文基于带耗散源Green函数的去奇异化数值方法,将正则波积分进行扩展,导出了多重点源带耗散自由表面波高公式.数值模拟多重点源不同排列下自由面波高波形及等高线的变化规律,验证了多重点源带耗散源Green函数的去奇异化数值方法的正确... 该文基于带耗散源Green函数的去奇异化数值方法,将正则波积分进行扩展,导出了多重点源带耗散自由表面波高公式.数值模拟多重点源不同排列下自由面波高波形及等高线的变化规律,验证了多重点源带耗散源Green函数的去奇异化数值方法的正确性和有效性.数值结果表明:双点源纵向排列,当增加点源位于单点源波峰时,双点源波峰波谷相互叠加;当增加点源位于单点源波谷时,双点源波峰波谷相互干扰,波振幅迅速减小,在自由面水平线上下缓慢震荡.多重点源纵向排列,点源位于不同位置,波高出现类似的周期性变化现象.多重点源横向排列,波面明显改变,自由表面波以横波形式向后扩散. 展开更多
关键词 带耗散Green函数 多重点 自由面波高 周期性
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Existence of Multiple Positive Solutions for Higher-Order p-Laplacian Boundary Value Problems
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作者 贺小明 葛渭高 《Journal of Beijing Institute of Technology》 EI CAS 2002年第2期212-216,共5页
The existence of multiple positive solutions for a class of higher order p Laplacian boundary value problem is studied. By means of the Leggett Williams fixed point theorem in cones, existence criteria which e... The existence of multiple positive solutions for a class of higher order p Laplacian boundary value problem is studied. By means of the Leggett Williams fixed point theorem in cones, existence criteria which ensure the existence of at least three positive solutions of the boundary value problem are established. 展开更多
关键词 positive solutions cone Leggett Williams fixed point theorem p Laplacian boundary value problems
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Existence of Multiple Positive Solutions of Discrete Boundary Value Problem
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作者 周桂云 《Chinese Quarterly Journal of Mathematics》 CSCD 2002年第4期99-104,共6页
In this paper, we consider the existence of multiple positive solutions of discrete boundary value problem. The theory of fixed point index is used here to derive the existence theorem.
关键词 nonlinear difference equation upper and lower solutions the fixed point index
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Recent developments on applications of sequential loop closing and diagonal dominance control schemes to industrial multivariable system 被引量:4
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作者 A.H.Mazinan M.F.Kazemi 《Journal of Central South University》 SCIE EI CAS 2013年第12期3401-3420,共20页
With a focus on an industrial multivariable system, two subsystems including the flow and the level outputs are analysed and controlled, which have applicability in both real and academic environments. In such a case,... With a focus on an industrial multivariable system, two subsystems including the flow and the level outputs are analysed and controlled, which have applicability in both real and academic environments. In such a case, at first, each subsystem is distinctively represented by its model, since the outcomes point out that the chosen models have the same behavior as corresponding ones. Then, the industrial multivariable system and its presentation are achieved in line with the integration of these subsystems, since the interaction between them can not actually be ignored. To analyze the interaction presented, the Gershgorin bands need to be acquired, where the results are used to modify the system parameters to appropriate values. Subsequently, in the view of modeling results, the control concept in two different techniques including sequential loop closing control(SLCC) scheme and diagonal dominance control(DDC) schemes is proposed to implement on the system through the Profibus network, as long as the OPC(OLE for process control) server is utilized to communicate between the control schemes presented and the multivariable system. The real test scenarios are carried out and the corresponding outcomes in their present forms are acquired. In the same way, the proposed control schemes results are compared with each other, where the real consequences verify the validity of them in the field of the presented industrial multivariable system control. 展开更多
关键词 multivariable system diagonal dominance control sequential loop closing control Profibus network OPC server orifice relation interaction analysis Gershogerin bands non-minimum phase system
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The Existence of Multiple Solutions for Second Order Differential Equations with Infinite Delay
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作者 孙兴旺 代新利 《Chinese Quarterly Journal of Mathematics》 CSCD 2003年第4期378-387,共10页
This paper discusses the existence of multiple solutions for second order differential equations with infinite delay.
关键词 differential euqations infinite delay Schauder fixed point theorem
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Genome-wide mining, characterization, and development of microsatellite markers in Marsupenaeus japonicus by genome survey sequencing 被引量:1
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作者 LU Xia LUAN Sheng +3 位作者 KONG Jie HU Longyang MAO Yong ZHONG Shengping 《Chinese Journal of Oceanology and Limnology》 SCIE CAS CSCD 2017年第1期203-214,共12页
The kuruma prawn, Marsupenaeus japonicus, is one of the most cultivated and consumed species of shrimp. However, very few molecular genetic/genomic resources are publically available for it. Thus, the characterization... The kuruma prawn, Marsupenaeus japonicus, is one of the most cultivated and consumed species of shrimp. However, very few molecular genetic/genomic resources are publically available for it. Thus, the characterization and distribution of simple sequence repeats(SSRs) remains ambiguous and the use of SSR markers in genomic studies and marker-assisted selection is limited. The goal of this study is to characterize and develop genome-wide SSR markers in M. japonicus by genome survey sequencing for application in comparative genomics and breeding. A total of 326 945 perfect SSRs were identified, among which dinucleotide repeats were the most frequent class(44.08%), followed by mononucleotides(29.67%), trinucleotides(18.96%), tetranucleotides(5.66%), hexanucleotides(1.07%), and pentanucleotides(0.56%). In total, 151 541 SSR loci primers were successfully designed. A subset of 30 SSR primer pairs were synthesized and tested in 42 individuals from a wild population, of which 27 loci(90.0%) were successfully amplified with specific products and 24(80.0%) were polymorphic. For the amplified polymorphic loci, the alleles ranged from 5 to 17(with an average of 9.63), and the average PIC value was 0.796. A total of 58 256 SSR-containing sequences had significant Gene Ontology annotation; these are good functional molecular marker candidates for association studies and comparative genomic analysis. The newly identified SSRs significantly contribute to the M. japonicus genomic resources and will facilitate a number of genetic and genomic studies, including high density linkage mapping, genome-wide association analysis, marker-aided selection, comparative genomics analysis, population genetics, and evolution. 展开更多
关键词 Marsupenaeus japonicus genome-wide SSR markers genome survey sequencing functional annotation
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Development of Three Multiplex PCR Primer Sets for Ark Shell(Scapharca broughtonii)and Their Validation in Parentage Assignment 被引量:1
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作者 LINing LI Qi +1 位作者 KONG Lingfeng YU Hong 《Journal of Ocean University of China》 SCIE CAS 2016年第2期311-317,共7页
Scapharca broughtonii is a commercially important and over-exploited species.In order to investigate its genetic diversity and population structure,43 novel polymorphic microsatellites were isolated and characterized.... Scapharca broughtonii is a commercially important and over-exploited species.In order to investigate its genetic diversity and population structure,43 novel polymorphic microsatellites were isolated and characterized.The number of alleles per locus ranged from 3 to 22 with an average of 6.93,and the observed and expected heterozygosities varied between 0.233 and 1.000,and 0.250 and 0.953,with an average of 0.614 and 0.707,respectively.Three highly informative multiplex PCRs were developed from nine of those microsatellites for S.broughtonii.We evaluated and validated these multiplex PCRs in 8 full-sib families.The average polymorphism information content(PIC) was 0.539.The frequency of null alleles was estimated as 3.13% of all the alleles segregation based on a within-family analysis of Mendelian segregation patterns.Parentage analysis of real offspring demonstrated that 100% of all offspring were unambiguously allocated to a pair of parents based on 3 multiplex sets.Those 43 microsatellite loci with high variability will be helpful for the analysis of population genetics and conservation of wild stock of S.broughtonii.The 3 sets of multiplex PCRs could be an important tool of pedigree reconstruction,population genetic analysis and brood stock management. 展开更多
关键词 Seapharca broughtonii microsatellites multiplex PCR parentage assignment
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Multiplicity results of breathers for the discrete nonlinear Schrodinger equations with unbounded potentials 被引量:1
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作者 ZHOU Zhan MA DeFang 《Science China Mathematics》 SCIE CSCD 2015年第4期781-790,共10页
We consider a class of discrete nonlinear Schrdinger equations with unbounded potentials. We obtain some new multiplicity results of breathers of the equations by using critical point theory. Our results greatly impro... We consider a class of discrete nonlinear Schrdinger equations with unbounded potentials. We obtain some new multiplicity results of breathers of the equations by using critical point theory. Our results greatly improve some recent results in the literature. 展开更多
关键词 multiplicity results BREATHERS discrete nonlinear Schrodinger equations critical point theory
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Some Random Coincidence Point Theorems
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作者 Ghulam Mustafa 《Journal of Mathematical Research and Exposition》 CSCD 北大核心 2003年第3期413-421,共9页
A class of multifunctions satisfying more general contractive inequalities is introduced and random coincidence point theorems for pairs of measurable nmltifunctions belonging to this class are proved.
关键词 separable metric space MULTIFUNCTIONS random coincidence point.
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Positive Solutions of Singular Fourth Order Four Point Boundary Value Problems with p-Laplacian Operator
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作者 陈永鹏 戚仕硕 《Journal of Mathematical Research and Exposition》 CSCD 2009年第4期671-681,共11页
In this paper,we consider the existence of positive solutions for the singular fourth-order four point boundary value problem with p-Laplacian operator.By using the fixed point theorem of cone expansion and compressio... In this paper,we consider the existence of positive solutions for the singular fourth-order four point boundary value problem with p-Laplacian operator.By using the fixed point theorem of cone expansion and compression,the existence of multiple positive solutions is ob-tained. 展开更多
关键词 P-LAPLACIAN singular boundary value problem positive solution cone
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Positive solutions for a multi-parameter system of second-order ordinary differential equations 被引量:4
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作者 CHENG XiYou ZHANG ZhiTao 《Science China Mathematics》 SCIE 2011年第5期959-972,共14页
In this paper, we establish the product formula for the fixed point index on product cone, andthen, as applications, consider the existence, nonexistence and multiplicity of positive solutions for a second-order ordin... In this paper, we establish the product formula for the fixed point index on product cone, andthen, as applications, consider the existence, nonexistence and multiplicity of positive solutions for a second-order ordinary differential system with parameters. The discussion is based on the product formula and thefundamental properties of the fixed point index. 展开更多
关键词 positive solution ordinary differential systems fixed point index
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A sixth-order wavelet integral collocation method for solving nonlinear boundary value problems in three dimensions
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作者 Zhichun Hou Jiong Weng +2 位作者 Xiaojing Liu Youhe Zhou Jizeng Wang 《Acta Mechanica Sinica》 SCIE EI CAS CSCD 2022年第2期81-92,I0003,共13页
A sixth-order accurate wavelet integral collocation method is proposed for solving high-order nonlinear boundary value problems in three dimensions.In order to realize the establishment of this method,an approximate e... A sixth-order accurate wavelet integral collocation method is proposed for solving high-order nonlinear boundary value problems in three dimensions.In order to realize the establishment of this method,an approximate expression of multiple integrals of a continuous function defined in a three-dimensional bounded domain is proposed by combining wavelet expansion and Lagrange boundary extension.Through applying such an integral technique,during the solution of nonlinear partial differential equations,the unknown function and its lower-order partial derivatives can be approximately expressed by its highest-order partial derivative values at nodes.A set of nonlinear algebraic equations with respect to these nodal values of the highest-order partial derivative is obtained using a collocation method.The validation and convergence of the proposed method are examined through several benchmark problems,including the eighth-order two-dimensional and fourth-order three-dimensional boundary value problems and the large deflection bending of von Karman plates.Results demonstrate that the present method has higher accuracy and convergence rate than most existing numerical methods.Most importantly,the convergence rate of the proposed method seems to be independent of the order of the differential equations,because it is always sixth order for second-,fourth-,sixth-,and even eighth-order problems. 展开更多
关键词 Nonlinear boundary value problems Eighth-order derivative Coiflet wavelet Integral collocation method Von Karman plate
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