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Interaction Rule between Rare Earths and LowMelting Point Elements in Fe-,Cu-,AI-,Ni-Base Liquid Solutions 被引量:1
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作者 Du Ting Sun Yunyong +1 位作者 Wu Yeming Wang Longmei 《Journal of Iron and Steel Research International》 SCIE EI CAS CSCD 1997年第1期15-18,共5页
Interaction rule between representative RE and Sn, Sb, Pb, Cu, S, P low melting point elements respectively in Fe , Cu , Al , Ni base liquid solutions including totally 34 ternary and quarternary systems was inve... Interaction rule between representative RE and Sn, Sb, Pb, Cu, S, P low melting point elements respectively in Fe , Cu , Al , Ni base liquid solutions including totally 34 ternary and quarternary systems was investigated. For each system some thermodynamic properties were obtained, such as the standard free energies of equilibrium reactions, activity interaction coefficients etc .. 展开更多
关键词 rare earth low melting point element FE CU Al and Ni base solution interaction rule
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A Generalized Point Conforming Rectangular Plate Element
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作者 Wang Deyu Chen Tieyun Associate Professor, Department of Naval Architecture and Ocean Engineering, Shanghai Jiao Tong University,Shanghai 200030 Professor, Department of Naval Architecture and Ocean Engineering, Shanghai Jiao Tong University,Shanghai 200030 《China Ocean Engineering》 SCIE EI 1995年第3期297-301,共5页
A generalized point conforming rectangular element for plate bending is proposed. The present element displacement field can not only satisfy the continuity of normal displacement and its derivative at the element nod... A generalized point conforming rectangular element for plate bending is proposed. The present element displacement field can not only satisfy the continuity of normal displacement and its derivative at the element node, but also satisfy the generalized continuity at the middle point of each element boundary, where the generalized conforming condition is to make the non-conforming residual to be minimum. Numerical results show that the proposed element is more accurate than the ordinary 4-node non-conforming rectangular plate element (ACM element). 展开更多
关键词 FEM generalized conforming element point conforming rectangular element plate bending
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HIGH ACCURACY FINITE VOLUME ELEMENT METHOD FOR TWO-POINT BOUNDARY VALUE PROBLEM OF SECOND ORDER ORDINARY DIFFERENTIAL EQUATIONS 被引量:4
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作者 Wang Tongke(王同科) 《Numerical Mathematics A Journal of Chinese Universities(English Series)》 SCIE 2002年第2期213-225,共13页
In this paper, a high accuracy finite volume element method is presented for two-point boundary value problem of second order ordinary differential equation, which differs from the high order generalized difference me... In this paper, a high accuracy finite volume element method is presented for two-point boundary value problem of second order ordinary differential equation, which differs from the high order generalized difference methods. It is proved that the method has optimal order error estimate O(h3) in H1 norm. Finally, two examples show that the method is effective. 展开更多
关键词 SECOND order ordinary differential equation TWO-point boundary value problem high accuracy finite volume element method error estimate.
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Element-free Galerkin method for free vibration of rectangular plates with interior elastic point supports and elastically restrained edges 被引量:1
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作者 王砚 王忠民 阮苗 《Journal of Shanghai University(English Edition)》 CAS 2010年第3期187-195,共9页
The element-free Galerkin method is proposed to solve free vibration of rectangular plates with finite interior elastic point supports and elastically restrained edges.Based on the extended Hamilton's principle for t... The element-free Galerkin method is proposed to solve free vibration of rectangular plates with finite interior elastic point supports and elastically restrained edges.Based on the extended Hamilton's principle for the elastic dynamics system,the dimensionless equations of motion of rectangular plates with finite interior elastic point supports and the edge elastically restrained are established using the element-free Galerkin method.Through numerical calculation,curves of the natural frequency of thin plates with three edges simply supported and one edge elastically restrained,and three edges clamped and the other edge elastically restrained versus the spring constant,locations of elastic point support and the elastic stiffness of edge elastically restrained are obtained.Effects of elastic point supports and edge elastically restrained on the free vibration characteristics of the thin plates are analyzed. 展开更多
关键词 element free method rectangular thin plates interior elastic point supports elastically restrained edges free vibration
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Incremental Static Analysis of 2D Flow by Inter-Colliding Point-Particles and Use of Incompressible Rhombic Element 被引量:1
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作者 Panagis G. Papadopoulos Christopher G. Koutitas Panos P. Lazaridis 《Open Journal of Civil Engineering》 2016年第3期397-409,共13页
A simple method is proposed, for incremental static analysis of a set of inter-colliding particles, simulating 2D flow. Within each step of proposed algorithm, the particles perform small displacements, proportional t... A simple method is proposed, for incremental static analysis of a set of inter-colliding particles, simulating 2D flow. Within each step of proposed algorithm, the particles perform small displacements, proportional to the out-of-balance forces, acting on them. Numerical experiments show that if the liquid is confined within boundaries of a set of inter-communicating vessels, then the proposed method converges to a final equilibrium state. This incremental static analysis approximates dynamic behavior with strong damping and can provide information, as a first approximation to 2D movement of a liquid. In the initial arrangement of particles, a rhombic element is proposed, which assures satisfactory incompressibility of the fluid. Based on the proposed algorithm, a simple and short computer program (a “pocket” program) has been developed, with only about 120 Fortran instructions. This program is first applied to an amount of liquid, contained in a single vessel. A coarse and refined discretization is tried. In final equilibrium state of liquid, the distribution on hydro-static pressure on vessel boundaries, obtained by proposed computational model, is found in satisfactory approximation with corresponding theoretical data. Then, an opening is formed, at the bottom of a vertical boundary of initial vessel, and the liquid is allowed to flow gradually to an adjacent vessel. Almost whole amount of liquid is transferred, from first to second vessel, except of few drops-particles, which remain, in equilibrium, at the bottom of initial vessel. In the final equilibrium state of liquid, in the second vessel, the free surface level of the liquid confirms that the proposed rhombing element assures a satisfactory incompressibility of the fluid. 展开更多
关键词 2D Flow Simulation Inter-Colliding point-Particles Incremental Static Analysis Incompressible Rhombic element Hydro-Static Pressure Distribution Flow from a Vessel to Another One “Pocket” Special Purpose Computer Program
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A New Fixed Point Theorem in L-Convex Spaces with Applications 被引量:1
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作者 WEM Kai-ting 《Chinese Quarterly Journal of Mathematics》 CSCD 2013年第1期27-32,共6页
In this paper, we present a new fixed point theorem in L-convex spaces and apply it to obtain a maximal element theorem, a variational inequality and a saddle point theorem in L-convex spaces.
关键词 fixed point maximal element variational inequality saddle point
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Application of finite element method to design of reinforced concrete
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作者 JIANG Qing-yuan, XIE Ming (School of Architectural Engineering and Design, Harbin Institute of Technology, Harbin 150001, China) 《Journal of Harbin Institute of Technology(New Series)》 EI CAS 2000年第S1期28-30,共3页
Structural safety against collapse will be ensured on the condition that stresses and strains in each element of concrete and reinforcement do not exceed the set limits. Different from the general design method, the r... Structural safety against collapse will be ensured on the condition that stresses and strains in each element of concrete and reinforcement do not exceed the set limits. Different from the general design method, the required amounts of longitudinal and stirrup reinforcements in reinforced concrete beam under certain loads by the finite element design method are interactive. There is an approximate hyperbolic relation between them. Considering economy and the design principle that beam should be stronger for shear and weaker for bending, even the yield point of longitudinal reinforcement is taken as reference point for design. According to this point, a real-life beam is designed and the design steps of the finite element method are discussed. 展开更多
关键词 FINITE element DESIGN REFERENCE point for DESIGN
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三维有限元中奇异点源的简化分析方法
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作者 潘泓 许嘉显 +2 位作者 骆冠勇 彭斯格 曹洪 《岩土力学》 EI CAS CSCD 北大核心 2024年第8期2483-2491,共9页
减压井是渗流控制的重要手段,减压浅井井底的入渗量不可忽略。在渗流场有限元有关井的计算中,含水层与井半径有巨大尺寸差异,只有将井周围的网格尺寸限制在厘米级或更少,才能达到合理的精度,但效率过低。为提高效率,分析时通常将井底简... 减压井是渗流控制的重要手段,减压浅井井底的入渗量不可忽略。在渗流场有限元有关井的计算中,含水层与井半径有巨大尺寸差异,只有将井周围的网格尺寸限制在厘米级或更少,才能达到合理的精度,但效率过低。为提高效率,分析时通常将井底简化为点源。由于点源附近的水头梯度极大,是奇异点,有限元中通常要进行等效处理才能保证全局的精度。提出了以零体积点元模拟点源的方法,该方法基于修正井水位法,利用点源解析解及四面体渗流单元,推导了点元单元的显式解。使用该点元单元模拟井底,可以在不失全局精度的条件下用大网格对点源进行模拟,避免了迭代计算,极大提高了利用三维有限元模拟点源的效率。详细介绍了该点元显式解的推导过程,验证其计算精度,并探究出简化计算方法的适用范围。最后介绍了该方法在实际排水减压抗浮工程中的应用。 展开更多
关键词 渗流 有限元法 井点 奇异点单元
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低熔点亲铜元素(LMCE)在金成矿中的作用及促进金富集的机理
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作者 刘家军 王大钊 +8 位作者 翟德高 高燊 郑波 王佳新 张斌 王冠智 王泽琳 汪林炜 翁国明 《矿床地质》 CAS CSCD 北大核心 2024年第4期712-734,共23页
低熔点亲铜元素(LMCE),包含As、Sb、Bi、Hg、Pb、Se、Te、Tl、Sn等,在戈尔德斯密特(V·M·Goldschmidt)元素地球化学分类中均属于亲铜元素。它们具有亲铜性、电负性大、低熔点、半金属的特性。在金成矿过程中,这些元素与硫的亲... 低熔点亲铜元素(LMCE),包含As、Sb、Bi、Hg、Pb、Se、Te、Tl、Sn等,在戈尔德斯密特(V·M·Goldschmidt)元素地球化学分类中均属于亲铜元素。它们具有亲铜性、电负性大、低熔点、半金属的特性。在金成矿过程中,这些元素与硫的亲和力强,多形成LMCE的硫化物、硫盐矿物、硒化物、碲化物和金属互化物,甚至形成LMCE与金的互化物和金的化合物。同时,它们在成矿流体中可以形成LMCE熔体,并对金矿床中Au的高效富集沉淀起到一种重要的桥梁作用。作者针对LMCE在金矿床中的赋存状态,总结了金矿床中LMCE富集金的特点,综合归纳了LMCE对金富集的成矿机理,认为在一些大型金矿床中,除了人们熟知的水-岩反应、硫化作用、流体沸腾、流体混合、有机成矿、岩浆脱气、叠加成矿等对热液金矿床的成矿起到重要作用外,流体-熔体分离、溶解-再沉淀、矿物重结晶、矿物表面吸附和元素替代等地质作用,也是LMCE在成矿过程中对金的富集重要机制。 展开更多
关键词 低熔点亲铜元素 赋存状态 富集特征 富集机理
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Mathematical analysis of EEP method for one-dimensional finite element postprocessing
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作者 赵庆华 周叔子 朱起定 《Applied Mathematics and Mechanics(English Edition)》 SCIE EI 2007年第4期441-445,共5页
For a class of two-point boundary value problems, by virtue of onedimensional projection interpolation, it is proved that the nodal recovery derivative obtained by Yuan's element energy projection (EEP) method has ... For a class of two-point boundary value problems, by virtue of onedimensional projection interpolation, it is proved that the nodal recovery derivative obtained by Yuan's element energy projection (EEP) method has the accuracy O(h^min{2k,k+4}) The theoretical analysis coincides the reported numerical results. 展开更多
关键词 superconvergence stress element energy projection method finite element two-point boundary value problems projection interpolation
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Finite Element Modeling and Design of Rectangular Patch Antenna with Different Feeding Techniques 被引量:1
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作者 Rajat Arora Ajay Kumar +1 位作者 Saleem Khan Sandeep Arya 《Open Journal of Antennas and Propagation》 2013年第2期11-17,共7页
The finite element modeling of three dimensional structures is important for researchers especially in the field of antennas and other domains of electromagnetic waves. This paper presents a finite element calculation... The finite element modeling of three dimensional structures is important for researchers especially in the field of antennas and other domains of electromagnetic waves. This paper presents a finite element calculations and numerical analysis for the microstrip patch antennas. In this paper, two different designs have been modelled and analyzed and both designs are based on the rectangular patches. The feeding point of one design is inside the patch while the other design contains feeding point outside the patch is T shaped. The computational analysis showed some interesting results for radiation pattern and far field domain. For these designs, the characteristic impedance taken is 50 Ω and the operating frequency domain is 1.4 to 1.7 GHz. The microstrip patch antennas are encapsulated in the inert spherical atmosphere of 20 mm thickness containing air inside it. 展开更多
关键词 MICROSTRIP PATCH Antenna Finite element Method T SHAPED FEEDING point FAR Field Domain
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Research on Algorithm of the Point Set in the Plane Based on Delaunay Triangulation 被引量:2
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作者 Bin Yang Shuyuan Shang 《American Journal of Computational Mathematics》 2012年第4期336-340,共5页
In the paper, an improved algorithm is presented for Delaunay triangulation of the point-set in the plain. Based on the original algorithm, we propose the notion of removing circle. During the process of triangulation... In the paper, an improved algorithm is presented for Delaunay triangulation of the point-set in the plain. Based on the original algorithm, we propose the notion of removing circle. During the process of triangulation, and the circle dynamically moves, the algorithm which is simple and practical, therefore evidently accelerates the process of searching a new point, while generating a new triangle. Then it shows the effect of the algorithm in the finite element mesh. 展开更多
关键词 point-Set in the PLANE DELAUNAY TRIANGULATION Removing Circle FINITE element MESH
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火灾下LYP160屈曲约束支撑抗震性能研究
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作者 何文福 李志威 +3 位作者 胡宝琳 胡吴彪 丁振坤 田华 《上海大学学报(自然科学版)》 CAS CSCD 北大核心 2024年第2期318-331,共14页
为研究屈曲约束支撑(buckling-restrained brace,BRB)及其体系在高温工况的抗震性能,对BRB芯材低屈服点LYP160钢材分别进行了常温和高温材料力学性能试验.通过与试验结果比较,建立了BRB热-力耦合精细化有限元分析模型,验证了该模型的准... 为研究屈曲约束支撑(buckling-restrained brace,BRB)及其体系在高温工况的抗震性能,对BRB芯材低屈服点LYP160钢材分别进行了常温和高温材料力学性能试验.通过与试验结果比较,建立了BRB热-力耦合精细化有限元分析模型,验证了该模型的准确性;对火灾下LYP160屈曲约束支撑的温度场、滞回曲线、骨架曲线和耗能能力等性能进行了对比分析;对不同工况(3种火灾工况和常温工况)下8层配置屈曲约束支撑钢框架(BRB structure,BS)和原结构(original structure,OS)分别进行了弹塑性动力时程分析.研究结果表明:3种火灾工况下BS的平均层间位移角较于OS分别降低了30.4%、33.2%和42%;OS柱塑性铰损坏严重,且更多出现在柱上,BS整体损坏程度较OS轻,更为安全可靠. 展开更多
关键词 屈曲约束支撑 低屈服点钢 火灾 有限元 抗震性能
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海洋科考船码头设计要素和要点研究及应用
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作者 王红尧 吴周翔 覃杰 《中国港湾建设》 2024年第3期61-65,共5页
随着国内海洋开发、海洋科考及海洋维权等需求的日益增加,现有的科考船码头普遍无法适应大型及新型科考船的实际需求。为了更好地推进海洋科考船码头的规划建设,通过对海洋科考船码头营运模式和功能需求两大功能要素、船型要素分析总结... 随着国内海洋开发、海洋科考及海洋维权等需求的日益增加,现有的科考船码头普遍无法适应大型及新型科考船的实际需求。为了更好地推进海洋科考船码头的规划建设,通过对海洋科考船码头营运模式和功能需求两大功能要素、船型要素分析总结,提出了海洋科考船码头设计过程中的选址、水域布置、装卸工艺、水工结构、后方陆域及配套工程等要点,可为后续类似海洋科考船码头工程设计提供参考。 展开更多
关键词 海洋科考船 码头 设计要素 设计要点
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MAXIMAL ELEMENTS OF A FAMILY OF G_B-MAJORIZED MAPPINGS IN PRODUCT FC-SPACES AND APPLICATIONS 被引量:2
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作者 丁协平 《Applied Mathematics and Mechanics(English Edition)》 SCIE EI 2006年第12期1607-1618,共12页
A new family of GB-majorized mappings from a topological space into a finite continuous topological spaces (in short, FC-space) involving a better admissible set-valued mapping is introduced. Some existence theorems... A new family of GB-majorized mappings from a topological space into a finite continuous topological spaces (in short, FC-space) involving a better admissible set-valued mapping is introduced. Some existence theorems of maximal elements for the family of GB-majorized mappings are proved under noncompact setting of product FCspaces. Some applications to fixed point and system of minimax inequalities are given in product FC-spaces. These theorems improve, unify and generalize many important results in recent literature. 展开更多
关键词 maximal element family of GB-majorized mappings fixed point system of minimax inequalities product FC-space
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Fitting on elements of exterior orientation utilizing SPOT-5 raw data file
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作者 SONG Wei-dong~1, WANG Wei-xi~1, HU Xing-hua~2 (1. Liaoning Technical University, Fuxin 123000, China 2. Liaoning Technical University, Fuxin 123000, China) 《中国有色金属学会会刊:英文版》 CSCD 2005年第S1期35-37,共3页
In traditional pattern, the calculation of elements of exterior orientation is to calculate the elements of image forming moment by using fundamental ground control points. Utilizing satellite raw data file directly, ... In traditional pattern, the calculation of elements of exterior orientation is to calculate the elements of image forming moment by using fundamental ground control points. Utilizing satellite raw data file directly, which holds abundant information and using the numerical analysis methods of modern mathematics, the parameter equations about each element of exterior orientation are adjused and the elements of image forming moment under some precision are calculated. 展开更多
关键词 elementS of EXTERIOR ORIENTATION ground control point numerical analysis parameter equation
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Stress Distribution in Maxillary Central Incisors without Ferrules: A Finite Element Analysis of Post and Core Systems
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作者 Akihiro Tagahara Chihiro Masaki +4 位作者 Tomotaka Nodai Takashi Munemasa Taro Mukaibo Yusuke Kondo Ryuji Hosokawa 《Open Journal of Stomatology》 2021年第7期251-262,共12页
<strong>Purpose: </strong>The purpose of this study was to identify optimal post and core materials for central incisors without ferrules using three-dimensional finite element analysis and three-point ben... <strong>Purpose: </strong>The purpose of this study was to identify optimal post and core materials for central incisors without ferrules using three-dimensional finite element analysis and three-point bending tests. <strong>Methods: </strong>Stress analyses were performed with six models: cast metal post and core (MP), composite resin core alone, straight fiber-reinforced post-composite resin core (FSR), tapered fiber-reinforced post-composite resin core, straight titanium post-composite resin core (TSR), and tapered titanium post-composite resin core (TTR). A 100-N load was applied to the lingual surface at a 45&deg; angle to the long axis of the tooth. Maximum von Mises stress distributions were calculated with finite element analysis software. Five samples each of composite resin, straight fiber-reinforced post, straight titanium post, straight fiber-reinforced post and composite resin, and straight titanium post and composite resin were subjected to three-point bending tests, followed by analysis of variance and Tukey’s multiple comparison test. <strong>Results: </strong>Stress distribution was optimal on TTR. Maximum von Mises stress on the cervical side of the post was greatest in TSR (693 MPa) and TTR (556 MPa). Maximum stress on the apical side of the post was greatest in MP (110 MPa). Maximum stress in surrounding dentin was lowest in MP (203 MPa) and TTR (250 MPa). Gap distance was smallest in MP (0.09 mm) and largest in FSR (0.26 mm). Mean maximum three-point bending force was lowest in composite resin (26.9 N/mm) and highest in titanium post and composite resin (97.1 N/mm). Titanium post bending strength was consistently greater than that of the fiber-reinforced post (p < 0.01). <strong>Conclusion:</strong> These results revealed optimal stress distribution and high bending strength with the tapered titanium post and resin combination, suggesting that this combination can most effectively prevent root or post fracture in an anterior tooth without a ferrule. 展开更多
关键词 Fiber Post Titanium Post FERRULE Three-Dimensional Finite element Analysis Three-point Bending Test
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Superconvergence of Continuous Finite Elements with Interpolated Coeffcients for Initial Value Problems of Nonlinear Ordinary Differential Equation
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作者 Zhiguang Xiong Chuanmiao Chen 《Numerical Mathematics A Journal of Chinese Universities(English Series)》 SCIE 2007年第1期37-44,共8页
In this paper, n-degree continuous finite element method with interpolated coefficients for nonlinear initial value problem of ordinary differential equation is introduced and analyzed. An optimal superconvergence u-u... In this paper, n-degree continuous finite element method with interpolated coefficients for nonlinear initial value problem of ordinary differential equation is introduced and analyzed. An optimal superconvergence u-uh = O(hn+2), n ≥ 2, at (n + 1)-order Lobatto points in each element respectively is proved. Finally the theoretical results are tested by a numerical example. 展开更多
关键词 超收敛 有限元 原始价值 常微分方程
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玄武岩纤维增强复合材料拉挤圆管抗弯性能研究 被引量:1
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作者 孙胜江 李航宇 邢丽丽 《桥梁建设》 EI CSCD 北大核心 2024年第1期39-46,共8页
为使玄武岩纤维增强复合材料(Basalt Fiber Reinforced Polymer,BFRP)拉挤圆管在桥梁工程中得到更广泛地应用,对其抗弯性能进行试验及有限元分析。对2根长度为750 mm的BFRP拉挤圆管进行三点抗弯试验;采用LS-DYNA有限元软件对试验过程进... 为使玄武岩纤维增强复合材料(Basalt Fiber Reinforced Polymer,BFRP)拉挤圆管在桥梁工程中得到更广泛地应用,对其抗弯性能进行试验及有限元分析。对2根长度为750 mm的BFRP拉挤圆管进行三点抗弯试验;采用LS-DYNA有限元软件对试验过程进行模拟,验证有限元模拟的正确性;在保持BFRP拉挤圆管总厚度不变的条件下,研究内、外层双向纤维布的铺设厚度和角度对抗弯性能的影响。结果表明:试件从加载至破坏分为线弹性阶段、下降阶段和残余阶段,试件破坏后残余强度较大且卸载后迅速回弹恢复几何形状;有限元模拟试件的荷载~滑移曲线、失效现象和试验结果吻合较好,有限元模拟正确;布置适量厚度的内、外层双向纤维布可以提高试件的抗弯承载力;将内、外层双向纤维布铺设方向由90°变为45°后,抗弯承载力进一步提高,随着外层45°纤维布厚度增加,破坏时的挠度下降。建议制作BFRP拉挤圆管时,布置适量厚度的双向纤维布,角度以45°为宜。 展开更多
关键词 桥梁工程 玄武岩纤维增强复合材料 拉挤圆管 抗弯性能 铺设角度 铺设厚度 三点抗弯试验 有限元法
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Multivariate Analyses of Potentially Toxic Elements along an Industrialized Urban River in Northern Taiwan
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作者 Kuo-Yen Wei Li-Chuan Hsu Huang Chuen-Lan Yen 《Journal of Environmental Protection》 2021年第11期983-1000,共18页
The Ker-Ya River flows through the high-tech industrial park and urban residential areas of Hsin-Chu in northern Taiwan. Major and trace element concentrations of waste effluents, river water, and sediment samples col... The Ker-Ya River flows through the high-tech industrial park and urban residential areas of Hsin-Chu in northern Taiwan. Major and trace element concentrations of waste effluents, river water, and sediment samples collected during 2017 along the Ker-Ya River were analyzed to elucidate the distribution pattern of potential pollutants. Principal component analyses were applied, and four major contaminant associations were recognized: 1) Ce, Co, Fe, La, V, and Cr;2) Cu and Ni associated with Hg, Ni, P, Ga, W, In, and Ti;3) B, Li, Ba, Ca, and Ag;and 4) Sn with Zn, In, and Cd. All associations are considered to be mainly anthropogenic. Although the element associations recognized from the water samples are not exactly the same as those from the sediment samples but nevertheless, they are similar, suggesting that the short-term and long-term distribution patterns are consistent. The A association accounts for the most variance in the data and exhibits the widest distribution, suggesting the existence of contaminant sources in the upper and lower reaches, respectively. The sediments near the outlet of the city sewage plant also contain association A elements, signaling incomplete processing of the diverged waters sent to the plant at the river mouth. The B association (mainly Cu and Ni) appeared mainly in the upper and middle reaches, indicative of sources from industries in the upper reaches and the tributary Nan-Men Creek. The C association (B, Ba, Ca, and Li) was limited to the center part of the river, probably attributable to a nearby paper mill. The D association (primarily Sn, In, and Zn) was present in the top point of the middle reaches, suggesting the presence of other contaminant sources in the upper reaches. Although a total of four concomitant associations were recognized, none of the elements exceeded the drinking water standard, suggesting that there was no severe pollution present. 展开更多
关键词 Toxic elements Spatial Distribution Principal Component Analysis point Sources
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