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故郷への旅
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作者 杨舒予 《外语教学》 1982年第2期82-83,73,共3页
列车闇中西走。時時拔黑煤煙窓吹込来变匂漂z列车旅客互见,喋何食。声流行歌放送疲楽旅娱楽気分出谐刀每统俗笥乙 P●k泊。
关键词 列车旅客 声流 行歌 黑煤 达人 简元 人法 老人 私法 下扫
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归一思想探索
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作者 周修知 《宁德师范学院学报(自然科学版)》 1994年第1期6-8,55,共4页
本文以归一思想为指导,探索总结出一些消元方法.
关键词 归一思想 消元法 一元 多元 相关元 无关元 简元 繁元
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A simplified simulation method of friction pendulum bearings 被引量:5
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作者 Wang Yanhua Feng Yan Wu Jing 《Journal of Southeast University(English Edition)》 EI CAS 2018年第4期480-487,共8页
In order to improve the computation efficiency and simulation accuracy,a novel simplified simulation method for friction pendulum bearing( FPB) is proposed. The behavior of FPB was analyzed based on the stress charact... In order to improve the computation efficiency and simulation accuracy,a novel simplified simulation method for friction pendulum bearing( FPB) is proposed. The behavior of FPB was analyzed based on the stress characteristics of the slider of FPB. Then,a novel simplified FPB model with a single pendulum and a nonlinear spring was established. The mechanical behavior of the simplified model was analyzed and it conformed well to the basic requirements of FPB. Furthermore,shaking table tests of a concrete slab block structure isolated by four FPBs were carried out, followed by finite element simulations of the test using the proposed simplified model.Three waves and eleven loading scenarios were selected in the test. The results show that the overall trend of the relative displacement time-history curves,the horizontal acceleration time-history curves and the vertical acceleration time-history curves from the numerical simulation match in a good manner with those obtained from the tests. Specifically,it is found that the difference of the peak value within these curves between the simulation and test results is less than 15%,which means that the proposed simplified model can be used to simulate the FPB behaviors under dynamic loadings with acceptable accuracy for engineering purposes. 展开更多
关键词 friction pendulum bearing (FPB) simplified model finite element modelling shaking table test
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Beam-track interaction of high-speed railway bridge with ballast track 被引量:18
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作者 闫斌 戴公连 张华平 《Journal of Central South University》 SCIE EI CAS 2012年第5期1447-1453,共7页
Based on the construction bridge of Xiamen-Shenzhen high-speed railway(9-32 m simply-supported beam + 6×32 m continuous beam),the pier-beam-track finite element model,where the continuous beam of the ballast trac... Based on the construction bridge of Xiamen-Shenzhen high-speed railway(9-32 m simply-supported beam + 6×32 m continuous beam),the pier-beam-track finite element model,where the continuous beam of the ballast track and simply-supported beam are combined with each other,was established.The laws of the track stress,the pier longitudinal stress and the beam-track relative displacement were analyzed.The results show that reducing the longitudinal resistance can effectively reduce the track stress and the pier stress of the continuous beam,and increase the beam-track relative displacement.Increasing the rigid pier stiffness of continuous beam can reduce the track braking stress,increase the pier longitudinal stress and reduce the beam-track relative displacement,Increasing the rigid pier stiffness of simply-supported beam can reduce the track braking stress,the rigid pier longitudinal stress and the beam-track relative displacement. 展开更多
关键词 high-speed railway beam-track interaction ballast track rail longitudinal force continuous beam
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Optimal design of automotive body B-pillar using simplified finite element model of body-in-prime combined with an optimization procedure
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作者 Mehri IZANLOO Abolfazl KHALKHALI 《Journal of Central South University》 SCIE EI CAS CSCD 2022年第12期3939-3955,共17页
Optimization of an automotive body structure faces the difficulty of having too many design variables and a too large design search space. A simplified model of body-in-prime(BIP) can solve this difficulty by reducing... Optimization of an automotive body structure faces the difficulty of having too many design variables and a too large design search space. A simplified model of body-in-prime(BIP) can solve this difficulty by reducing the number of design variables. In this study, to achieve lighter weight and higher stiffness, the simplified model of BIP was developed and combined with an optimization procedure;consequently, optimal designs of automotive body B-pillar were produced. B-pillar was divided into four quarters and each quarter was modelled by one simplified beam. In the optimization procedure, depth, width, and thickness of the simplified beams were considered as the design variables.Weight, bending and torsional stiffness were also considered as objective functions. The optimization procedure is composed of six stages: designing the experiments, calculating grey relational grade, calculating signal-to noise ratio,finding an optimum design using Taguchi grey relational analysis, performing sensitivity analysis using analysis of variance(ANOVA) and performing non-dominated sorting and multi-criteria decision making. The results show that the width of lower B-pillar has the highest effect(about 55%) and the obtained optimum design point could reduce the weight of B-pillar by about 40% without reducing the BIP stiffness by more than 1.47%. 展开更多
关键词 body-in-prime(BIP)model finite element model bending stiffness torsional stiffness B-pillar Taguchi method multi criterion decision-making(MCDM)method
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A Simplified Approach to Analysis of High-Rise Frame Tube Structures
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作者 周岱 周笠人 刘红玉 《Journal of Shanghai Jiaotong university(Science)》 EI 2003年第1期92-97,共6页
Based on finite element method and finite strip method, a simplified approach was presented to analyze high rise frame tube structures. The generalized strip element is introduced and then the generalized stiffness ma... Based on finite element method and finite strip method, a simplified approach was presented to analyze high rise frame tube structures. The generalized strip element is introduced and then the generalized stiffness matrices for beam and column line are derived by using the displacement functions that describe the nodal displacements and displacement transforms. Furthermore, the formulas for the generalized stiffness matrix of generalized strip element and load arrays corresponding to the displacement parameters were developed. It is shown through a series of numerical computation that the nodal angular displacements at the same floor in a generalized strip element are approximately identical. A comparison of the finite element method and the finite strip method shows that the simplified approach not only is accurate, but also reduces the number of basic unknown quantities. 展开更多
关键词 beam column line framed generalized strip element generalized stiffness matrix
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Minimal Elements in the Poset of Graphic Sequences
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作者 李炯生 胡跃进 《Journal of Mathematical Research and Exposition》 CSCD 2000年第2期171-176,共6页
A nonincreasing sequence ( of n nonnegative integers is said to be graphic if it is the degree sequence of a simple graph G of order n. The set of all graphic sequences of n terms with even sum 2m and trace f is a pos... A nonincreasing sequence ( of n nonnegative integers is said to be graphic if it is the degree sequence of a simple graph G of order n. The set of all graphic sequences of n terms with even sum 2m and trace f is a poset G_(n,m,f) under majorization relation. The paper characterizes the minimal elements in the poset G_(n,m,f) and determines the number of minimal elements in various posets of graphic sequences. 展开更多
关键词 GRAPH graphic sequence POSET minimal elements.
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Optomechanical Dark State in a Dual-Species Bose-Einstein Condensate
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作者 景辉 D.S. Goldbaum 《Communications in Theoretical Physics》 SCIE CAS CSCD 2012年第10期551-556,共6页
We study cavity optomechanics of ultracold dual-species atomic mixtures with nonlinear collisions.Interspecies interactions provide a direct parametric coupling of fictitious mechanical elements which,through interfer... We study cavity optomechanics of ultracold dual-species atomic mixtures with nonlinear collisions.Interspecies interactions provide a direct parametric coupling of fictitious mechanical elements which,through interfering with the intracavity optical field,leads to a switchable optically-dark state for either species.This demonstrates a matterwave analog of recently observed mechanical wave mixing and quantum motional-state swapping,with applications in the construction of integrated phononic devices,and the cavity-enhanced detection of quantum degenerate atomic mixtures. 展开更多
关键词 OPTOMECHANICS Bose-Einstein condensate BISTABILITY
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Lanthanide-catalyzed cyclocarbonylation and cyclothiocarbonylation: a facile synthesis of benzannulated 1,3-diheteroatom five- and six-membered heterocycles
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作者 JING YuFeng LIU RuiTing +1 位作者 LIN YangHui ZHOU XiGeng 《Science China Chemistry》 SCIE EI CAS 2014年第8期1117-1125,共9页
La[N(SiMe3)2]3 proves to be an efficient catalyst system for the cyclocarbonylation of 1,2-disubstituted benzenes with isocyanates. In this approach, aryl/alkyl isocyanates react with o-phenylenediamine, o-aminophenol... La[N(SiMe3)2]3 proves to be an efficient catalyst system for the cyclocarbonylation of 1,2-disubstituted benzenes with isocyanates. In this approach, aryl/alkyl isocyanates react with o-phenylenediamine, o-aminophenol, o-aminothiophenol, catechols and anilines ortho-substituted by CH2NH2 and CONH2 to form, respectively, the corresponding benzimidazolones, benzoxazolones, benzothiazolones, benzodioxolones, 3,4-dihydroquinazolin-2(1H)-one, and quinazolinediones. These results represent the first example of lanthanide-catalyzed carbonylation. This methodology is also applicable for the preparation of various benzannulated 1,3-diheteroatom cyclic thioketones starting from aryl/alkyl isothiocyanates or CS2 in good to excellent yields. Based on the results of experiments performed using an o-aminobenzamido dianion lanthanide complex, a general mechanism, involving the tandem reaction of two lanthanide-ligand bonds with one heterocumulene molecule, is proposed as well. 展开更多
关键词 lanthanide catalyst 1 2-disubstituted benzene ISOCYANATE ISOTHIOCYANATES CYCLOCARBONYLATION cyclothiocarbonylation
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杭县是怎样贯彻浙江省第一届统计科长会议的精神的
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《中国统计》 1953年第11期17-18,共2页
第一、积极向领导反映情况,提出建设性的意见.该县统计科长于会议结束回县后,即根据会议精神具体地研究了县里的情况,分析了工作中的有利条件与不利条件,拟订了比较切实可行的工作计划,向领导汇报,获得领导的具体指示与有力支持,明确了... 第一、积极向领导反映情况,提出建设性的意见.该县统计科长于会议结束回县后,即根据会议精神具体地研究了县里的情况,分析了工作中的有利条件与不利条件,拟订了比较切实可行的工作计划,向领导汇报,获得领导的具体指示与有力支持,明确了方向,从而创造了开展工作的有利条件,提高了工作信心.经验证明,具体的分析情况,依靠领导。 展开更多
关键词 浙江省 简元 鞍垫 平凿 跨零 重叩 盾心 食精 干量 阴水
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