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The Tension Cosmology, Largest Cosmic Structures and Explosions of Supernovae from SST
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作者 Sylwester Kornowski 《Journal of High Energy Physics, Gravitation and Cosmology》 CAS 2024年第3期1029-1044,共16页
Here, using the Scale-Symmetric Theory (SST) we explain the cosmological tension and the origin of the largest cosmic structures. We show that a change in value of strong coupling constant for cold baryonic matter lea... Here, using the Scale-Symmetric Theory (SST) we explain the cosmological tension and the origin of the largest cosmic structures. We show that a change in value of strong coupling constant for cold baryonic matter leads to the disagreement in the galaxy clustering amplitude, quantified by the parameter S8. Within the same model we described the Hubble tension. We described also the mechanism that transforms the gravitational collapse into an explosion—it concerns the dynamics of virtual fields that lead to dark energy. Our calculations concern the Type Ia supernovae and the core-collapse supernovae. We calculated the quantized masses of the progenitors of supernovae, emitted total energy during explosion, and we calculated how much of the released energy was transferred to neutrinos. Value of the speed of sound in the strongly interacting matter measured at the LHC confirms that presented here model is correct. Our calculations show that the Universe is cyclic. 展开更多
关键词 Scale-Symmetric Theory tension Cosmology Coupling Constants Parameters σ8 and S8 Largest Cosmic structures Dark Energy Supernova Explosion Cyclic Universe
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Electronic Structures and Optical Properties of Ga Doped Single-Layer Indium Nitride
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作者 Zhi-wei Li De-ping Guo +2 位作者 Guang-yi Huang Wang-li Tao Man-yi Duan 《Chinese Journal of Chemical Physics》 SCIE CAS CSCD 2018年第3期313-317,368,共6页
Electronic structures and optical properties of single-layer In1-xGaxN are studied by employing Heyd-Scuseria-Ernzerh(HSE) method based on the first-principles. The band structure and density of states(DOS) of sin... Electronic structures and optical properties of single-layer In1-xGaxN are studied by employing Heyd-Scuseria-Ernzerh(HSE) method based on the first-principles. The band structure and density of states(DOS) of single-layer In1-xGaxN are calculated, and the band gap ranges from 1.8 eV to 3.8 eV as the ratio x changes, illustrating the potential for the tunability of band gap values via Ga doped. We also have investigated optical properties of single-layer In1-xGaxN such as dielectric function, refractive index and absorption coefficient, the main peak of dielectric function spectrum and the absorption edge are found to have a remarkable blue-shift as the concentration of Ga increases. Furthermore, the optical properties of single-layer In1-xGaxN are analyzed based on the band structures and DOS analysis. Such unique optical properties have profound application in nanoelectronics and optical devices. 展开更多
关键词 Electronic structure OPTICAL properties single-layer In1-xGaxN Heyd-Scuseria-Ernzerh method
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Dynamic Analysis of Tension Leg Platform for Offshore Wind Turbine Support as Fluid-Structure Interaction 被引量:6
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作者 黄虎 张社荣 《China Ocean Engineering》 SCIE EI 2011年第1期123-131,共9页
Tension leg platform (TLP) for offshore wind turbine support is a new type structure in wind energy utilization. The strong-interaction method is used in analyzing the coupled model, and the dynamic characteristics ... Tension leg platform (TLP) for offshore wind turbine support is a new type structure in wind energy utilization. The strong-interaction method is used in analyzing the coupled model, and the dynamic characteristics of the TLP for offshore wind turbine support are recognized. As shown by the calculated results: for the lower modes, the shapes are water's vibration, and the vibration of water induces the structure's swing; the mode shapes of the structure are complex, and can largely change among different members; the mode shapes of the platform are related to the tower's. The frequencies of the structure do not change much after adjusting the length of the tension cables and the depth of the platform; the TLP has good adaptability for the water depths and the environment loads. The change of the size and parameters of TLP can improve the dynamic characteristics, which can reduce the vibration of the TLP caused by the loads. Through the vibration analysis, the natural vibration frequencies of TLP can be distinguished from the frequencies of condition loads, and thus the resonance vibration can be avoided, therefore the offshore wind turbine can work normally in the complex conditions. 展开更多
关键词 offshore wind turbine tension leg platform fluid structure interaction dynamic characteristics yaw resonance vibration
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A FORM FUNCTION METHOD FOR FORM FINDING OF TENSION STRUCTURE
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作者 孙宗光 赵俭斌 《Applied Mathematics and Mechanics(English Edition)》 SCIE EI 2000年第11期1277-1281,共5页
A new form function involving parameters Pi is presented. On the basis of the form function, an initial form of tension structure was Sound by interpolating through the control points on boundary of the structure. The... A new form function involving parameters Pi is presented. On the basis of the form function, an initial form of tension structure was Sound by interpolating through the control points on boundary of the structure. The form function can be controlled by changing beta (1) according to the pre-tension and the boundary of the structure. The final form of a tension structure should be an equilibrium system under the pretension. To examine the nature of the initial form, the FEM was used. Many examples show that the initial form gives a very ideal result for equal or unequal pre-tension in two directions of the structure. In general cases, there is little difference between the initial form and the final one. 展开更多
关键词 tension structure form finding form function
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Tensile force correction calculation method for prestressed construction of tension structures
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作者 Xin ZHUO Guo-fa ZHANG +1 位作者 Koichiro ISHIKAWA Dao-an LOU 《Journal of Zhejiang University-Science A(Applied Physics & Engineering)》 SCIE EI CAS CSCD 2008年第9期1201-1207,共7页
Factors such as errors during the fabrication or construction of structural components and errors of calculation as- sumption or calculation methods, are very likely to cause serious deviation of many strings’ actual... Factors such as errors during the fabrication or construction of structural components and errors of calculation as- sumption or calculation methods, are very likely to cause serious deviation of many strings’ actual prestressing forces from the designed values during tension structure construction or service period, and further to threaten the safety and reliability of the structure. Aiming at relatively large errors of the prestressing force of strings in a tension structure construction or service period, this paper proposes a new finite element method (FEM), the "tensile force correction calculation method". Based on the measured prestressing forces of the strings, this new method applies the structure from the zero prestressing force status approach to the measured prestressing force status for the first phase, and from the measured prestressing force status approach to the designed prestressing force status for the second phase. The construction tensile force correction value for each string can be obtained by multi-iteration with FEM. Using the results of calculation, the strings’ tensile force correction by group and in batch will be methodic, simple and accurate. This new calculation method can be applied to the prestressed correction construction simulation analysis for tension structures. 展开更多
关键词 tension structures Prestressed construction High precision
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Innovative Applications of Post-Tension for Restoration and Rehabilitation of Bridges and Structures--Case Studies in India
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作者 Ramesh Kommajosyula Narapraju Venkat Ramana Rao 《Journal of Civil Engineering and Architecture》 2014年第7期869-880,共12页
This paper deals with new and innovative case studies of application of post-tensioning for restoration of structures for buildings, bridges and rock stabilization in India. In earlier situations for these types of ca... This paper deals with new and innovative case studies of application of post-tensioning for restoration of structures for buildings, bridges and rock stabilization in India. In earlier situations for these types of cases conventional method of repair and rehabilitation has been used. These innovative approaches for restoration have led to enormous saving of cost and time. The advantages of post tensioning are well known in the civil industry and are being used for the last 40 to 50 years. Post tensioning is one of the best methods to induce stresses in the concrete before application of live load and this technique can also be widely used for restoration and rehabilitation of structures. Unlike the use of post-tensioning in new structures there are no definite methods or codes for application in restoration and rehabilitation of structures. For restoration and rehabilitation of structures, PT (post tensioned) technique can be applied in combination with other techniques and materials available. Bridge lifting is a tricky and risky job especially when the superstructure is displaced appreciably by a natural calamity, etc.. Not only the present state of structure needs proper study before commencement of restoration and rehabilitation but also calls for careful execution. This paper deals with case studies of innovative applications of post tensioning in restoration and rehabilitation of structures and restoration of bridge structure in Andaman & Nicobar Island, India affected by Sumatra quake. 展开更多
关键词 RESTORATION REHABILITATION structures external post tensioning rock stabilization.
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Tensegrities and Tensioned Structures
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作者 MªDolores Alvarez Elipe 《Journal of Architectural Environment & Structural Engineering Research》 2020年第3期10-16,共7页
“Push-and-pull”efficient structures have been inconceivable between XVIII centuries.It is because of the incapacity of obtain an efficient behaviour of tensioned material.Since XVIII centuries,architecture developed... “Push-and-pull”efficient structures have been inconceivable between XVIII centuries.It is because of the incapacity of obtain an efficient behaviour of tensioned material.Since XVIII centuries,architecture developed some structural knowledge generating novel structural forms in the architecture and engineering that were not known before.Tensegrities and tensioned structures were studied due to the knowledge of geometry and tension.Some investigations about tensegrities and tensioned structures have been developed since that moment.Tensegrities are bar and cable structures that work only in compression or tension efforts.Bars and cables are balanced,but in appearance the growth is disorderly.Most of deployable structures are based on tensegrity systems.The research is focused in presenting a summary of tensegrities and tensioned architectures that have been used in the structural design of novel patterns.The research of adequate materials to tension efforts will be crucial in this study.The investigation presents an important state of the art that provides technical solutions to apply on novel architectures based on tensegrities and tensioned structures.The research is useful to produce the current constructive solutions based on these constructive systems. 展开更多
关键词 TENSEGRITY tensioned GEOMETRY structure Compression tension EFFORT
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Quantitative Structure-Property Relationship on Prediction of Surface Tension of Nonionic Surfactants
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作者 ZhengWuWANG XiaoYiZHANG 《Chinese Chemical Letters》 SCIE CAS CSCD 2002年第4期363-366,共4页
A quantitative structure-property relationship (QSPR) study has been made for the prediction of the surface tension of nonionic surfactants in aqueous solution. The regressed model includes a topological descriptor, ... A quantitative structure-property relationship (QSPR) study has been made for the prediction of the surface tension of nonionic surfactants in aqueous solution. The regressed model includes a topological descriptor, the Kier & Hall index of zero order (KH0) of the hydrophobic segment of surfactant and a quantum chemical one, the heat of formation (fHD) of surfactant molecules. The established general QSPR between the surface tension and the descriptors produces a correlation coefficient of multiple determination, 2r=0.9877, for 30 studied nonionic surfactants. 展开更多
关键词 Quantitative structure-property relationship surface tension nonionic surfactants.
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The Tension Balance Structure of China's Human Rights Development Path
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作者 齐延平 TIAN Tong(Translated) 《The Journal of Human Rights》 2021年第5期738-746,共9页
The human rights white paper has in it the basic concepts of human rights,the form of the human rights system,and the mode of human rights practice in modern China.It is based on the tension balance structure between ... The human rights white paper has in it the basic concepts of human rights,the form of the human rights system,and the mode of human rights practice in modern China.It is based on the tension balance structure between the historical feature and rationality,the cultural feature and similarity,the realistic feature and the common feature of human rights.Adhering to the historical nature of human rights rather than abstract rationality,and the cultural diversity and equality of human rights rather than one dominant model,and the particularity of human rights rather than universality is the pillar of China’s human rights philosophy,system,and practice.The human rights development path that combines the top-down leadership of China’s ruling party,the capability of the Chinese government in taking a holistic approach and the bottom-up driving force of the people is very different from the natural evolution path of the West. 展开更多
关键词 human rights in China historical feature cultural feature realistic feature tension balance structure
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The Influence of Atmospheric Pressure on Air Content and Pore Structure of Air-entrained Concrete 被引量:14
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作者 LI Yang WANG Zhendi WANG Ling 《Journal of Wuhan University of Technology(Materials Science)》 SCIE EI CAS 2019年第6期1365-1370,共6页
To study the effect of atmospheric pressure on the properties of fresh and hardened airentrained concrete, three kinds of air entraining agents were used for preparing air-entrained concrete in the plateaus(Lhasa, 61 ... To study the effect of atmospheric pressure on the properties of fresh and hardened airentrained concrete, three kinds of air entraining agents were used for preparing air-entrained concrete in the plateaus(Lhasa, 61 kPa) and the plains(Beijing, 101 kPa). Air content, slump, compressive strength and pore structure of the three air-entrained concretes were tested in these two places. It is found that the air content of concrete under low atmospheric pressure(LAP) is 4%-36% lower than that of concrete under normal atmospheric pressure(NAP), which explaines the decrease of slump for air-entrained concrete under LAP. Pore number of hardened concrete under LAP is reduced by 48%-69%. While, the proportion of big pores(pore diameter >1 200 μm) and air void spacing factor are increased by 1.5%-7.3% and 51%-92%, respectively. The deterioration of pore structure results in a 3%-9% reduction in the compressive strength of concrete. From the results we have obtained, it can be concluded that the increase of critical nucleation energy of air bubbles and the decrease of volumetric compressibility coefficient of air in the concrete are responsible for the variation of air content and pore structure of concrete under LAP. 展开更多
关键词 low atmospheric pressure air-entrained concrete air content pore structure surface tension
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Parametric Dimensional Analysis on the Structural Response of An Innovative Subsurface Tension Leg Platform in Ultra-Deep Water 被引量:4
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作者 ZHEN Xing-wei WU Jia-hao +2 位作者 HUANG Yi HAN Yue YAO Jin-jiang 《China Ocean Engineering》 SCIE EI CSCD 2018年第4期482-489,共8页
The innovative Subsurface Tension Leg Platform(STLP), which is designed to be located below Mean Water Level(M.W.L) to minimize direct wave loading and mitigate the effect of strong surface currents, is considered as ... The innovative Subsurface Tension Leg Platform(STLP), which is designed to be located below Mean Water Level(M.W.L) to minimize direct wave loading and mitigate the effect of strong surface currents, is considered as a competitive alternative system to support shallow-water rated well completion equipment and rigid risers for large ultra-deep water oil field development. A detailed description of the design philosophy of STLP has been published in the series of papers and patents. Nonetheless, design uncertainties arise as limited understanding of various parameters effects on the structural response of STLP, pertaining to the environmental loading, structural properties and hydrodynamic characteristics. This paper focuses on providing quantitative methodology on how each parameter affects the structural response of STLP, which will facilitate establishing the unique design criteria as regards to STLP. Firstly, the entire list of dimensionless groups of input and output parameters is proposed based on VaschyBuckingham theory. Then, numerical models are built and a series of numerical tests are carried out for validating the obtained dimensionless groups. On this basis, the calculation results of a great quantity of parametric studies on the structural response of STLP are presented and discussed in detail. Further, empirical formulae for predicting STLP response are derived through nonlinear regression analysis. Finally, conclusions and discussions are made. It has been demonstrated that the study provides a methodology for better control of key parameters and lays the foundation for optimal design of STLP. The obtained conclusions also have wide ranging applicability in reference to the engineering design and design analysis aspects of deepwater buoy supporting installations, such as Grouped SLOR or TLR system. 展开更多
关键词 subsurface tension leg platform structural response dimensional analysis ultra-deep water
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Internal Force Analysis Due to the Supporting Translation in Statically (Indeterminate) Structures for Different Elastic Modulus 被引量:1
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作者 姚文娟 叶志明 《Journal of Shanghai University(English Edition)》 CAS 2004年第3期274-280,共7页
For statically indeterminate structure, the internal force will be changed with the translation of the supports, because the internal force is related to the absolute value of the stiffness EI. When the tension is dif... For statically indeterminate structure, the internal force will be changed with the translation of the supports, because the internal force is related to the absolute value of the stiffness EI. When the tension is different with the compression modulus, EI is the function of internal force and is not constant any more that is different from classic mechanics. In the other words, it is a nonlinear problem to calculate the internal force. The expression for neutral axis of the statically indeterminate structure was derived in the paper. The iterative program for nonlinear internal force was compiled. One case study was presented to illustrate the difference between the results using the different modulus theory and the single modulus theory as in classical mechanics. Finally, some reasonable suggestions were made for the different modulus structures. 展开更多
关键词 different moduli in tension and compression statically indeterminate structure translation of support nonlinear internal force iteration.
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STATIC ANALYSIS OF CABLE STRUCTURE
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作者 黄炎 兰伟仁 《Applied Mathematics and Mechanics(English Edition)》 SCIE EI 2006年第10期1425-1430,共6页
Based on the nonlinear geometric relation between strain and displacement for flexible cable, the equilibrium equation under self-weight and influence of temperature was established and an analytical solution of displ... Based on the nonlinear geometric relation between strain and displacement for flexible cable, the equilibrium equation under self-weight and influence of temperature was established and an analytical solution of displacement and tension distribution defined in Eulerian coordinate system was accurately obtained. The nonlinear algebraic equations caused by cable structure were solved directly using the modified Powell hybrid algorithm with high precision routine DNEQNE of Fortran. For example, a cable structure consisting of three cables jointly supported by a vertical spring and all the other ends fixed was calculated and compared with various methods by other scholars. 展开更多
关键词 cable structure nonlinear deformation analytical method DISPLACEMENT tension
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Practical Aspects of the Design and Construction of a Small Cable Roof Structure
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作者 Vinicius Fernando Arcaro Luiz Carlos de Almeida 《Open Journal of Civil Engineering》 2017年第3期453-467,共15页
Cable roof structures?have?only become widespread in large span structures in the latter part of the twentieth century. However,?they?still represent a relatively new form of roof construction, especially as in the pr... Cable roof structures?have?only become widespread in large span structures in the latter part of the twentieth century. However,?they?still represent a relatively new form of roof construction, especially as in the present case of a small span innovative structural solution. The contribution of this text to the structural engineering community lies in the increased interest in building simple cable roof structures. Since its completion in September 1996, this small cable roof structure has been recognized as an interesting architectural and structural example. The text describes aspects of the design and construction of a small cable roof that was designed as a roof for an open-air theater stage for the city of Sao Jose do Rio Pardo, Sao Paulo, Brazil. A cable network, in the shape of a hyperbolic paraboloid surface, is anchored in a reinforced concrete edge ring. The projection of the ring’s axis onto the ground plane is an ellipse. Workers with specialized training were employed in the various stages of the construction, which was completed in September 1996. 展开更多
关键词 CABLE ROOFS Hypar ROOFS tension structureS
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三种新型钢结构体系研究
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作者 舒赣平 范圣刚 +2 位作者 陆金钰 郑宝锋 秦颖 《建筑结构》 北大核心 2024年第19期99-106,共8页
传统粗放型建造方式存在环境污染、耗能过大等问题。近年来,建筑行业正向绿色节能方向转型,推动钢结构建筑的发展是实现这一转型的重要方法和必由之路。钢结构具有自重轻、强度大、易于安装等优点,根据社会现阶段发展的需求,各种钢结构... 传统粗放型建造方式存在环境污染、耗能过大等问题。近年来,建筑行业正向绿色节能方向转型,推动钢结构建筑的发展是实现这一转型的重要方法和必由之路。钢结构具有自重轻、强度大、易于安装等优点,根据社会现阶段发展的需求,各种钢结构体系应运而生。为促进新型钢结构体系的发展及其工程应用,结合笔者课题组近年来相关的研究方向和成果,对装配式钢结构、自适应索杆张力结构、不锈钢材料结构三种结构体系的研究进行了详细的总结与介绍。 展开更多
关键词 新型钢结构体系 结构体系性能 装配式钢结构 自适应索杆张力结构 不锈钢材料结构
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非侵入式翼伞操纵绳张力传感器弹性体设计和有限元分析
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作者 郭瑞鹏 李前奇 +2 位作者 齐贺轩 赵敏 姚敏 《传感器与微系统》 CSCD 北大核心 2024年第8期99-101,105,共4页
针对目前的张力传感器难以用于翼伞操纵绳张力测量的问题,根据翼伞操纵绳张力的特点,设计了一种非侵入式的张力传感器结构。利用Ansys软件对设计的传感器弹性体进行了有限元仿真分析,研究了不同的结构参数对传感器弹性体的影响,给出了... 针对目前的张力传感器难以用于翼伞操纵绳张力测量的问题,根据翼伞操纵绳张力的特点,设计了一种非侵入式的张力传感器结构。利用Ansys软件对设计的传感器弹性体进行了有限元仿真分析,研究了不同的结构参数对传感器弹性体的影响,给出了最佳的弹性体结构参数。 展开更多
关键词 非侵入式 张力传感器 弹性体 结构参数 有限元分析
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基于滑模变结构的精密涂布机放卷系统张力控制策略研究
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作者 黄磊 徐莉萍 +1 位作者 李健 何鹏博 《印刷与数字媒体技术研究》 CAS 北大核心 2024年第3期267-273,共7页
张力稳定是涂布工艺的一个基础条件,如何提高放卷系统的张力控制精度是精密涂布机张力控制面临的难点问题。本研究针对精密涂布机放卷系统张力稳定性控制需求,提出了一种基于滑模变结构控制策略的放卷系统张力控制方法。首先,根据精密... 张力稳定是涂布工艺的一个基础条件,如何提高放卷系统的张力控制精度是精密涂布机张力控制面临的难点问题。本研究针对精密涂布机放卷系统张力稳定性控制需求,提出了一种基于滑模变结构控制策略的放卷系统张力控制方法。首先,根据精密涂布机放卷系统的工作原理,建立了放卷系统的参数时变、非线性动力学模型,分析了张力波动的主要原因;然后,在放卷系统张力模型的基础上,设计了一个放卷张力系统滑模变结构控制器,并利用李雅普诺夫(Lyapunov)定理进行了系统稳定性分析;最后,通过仿真试验对所设计的滑模变结构控制器进行了性能验证。仿真结果表明,相比于传统PID控制,本研究所设计的滑模变结构控制器对放卷张力系统具有更好的控制鲁棒性。 展开更多
关键词 精密涂布机 放卷系统 滑模变结构 张力控制
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灌浆插筋式模块钢结构连接节点力学性能试验研究
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作者 陈志华 孟凡贵 +3 位作者 刘红波 尚静媛 崔萌 闫翔宇 《天津大学学报(自然科学与工程技术版)》 EI CSCD 北大核心 2024年第3期311-320,共10页
针对模块钢结构建筑间的连接问题,提出了一种新型的由钢筋与CGM灌浆料组成的灌浆插筋式模块钢结构连接节点形式,并采用试验和理论分析的方法,对节点柱的轴压性能、轴拉性能和抗弯性能进行了深入研究,提出了相应的承载力计算方法.研究结... 针对模块钢结构建筑间的连接问题,提出了一种新型的由钢筋与CGM灌浆料组成的灌浆插筋式模块钢结构连接节点形式,并采用试验和理论分析的方法,对节点柱的轴压性能、轴拉性能和抗弯性能进行了深入研究,提出了相应的承载力计算方法.研究结果表明:①在轴向压力作用下,此节点上下两侧空钢管发生屈曲破坏,轴压承载力约为钢管截面屈服承载力的97%,表明此节点具有较好的抗压承载能力;不同钢筋直径试件的荷载-位移曲线基本一致,表明节点的抗压承载力与钢筋直径无关;②在轴向拉力作用下,试件在节点的连接缝隙处发生分离,灌浆料表面呈现了斜向裂缝;在钢筋直径为14~18 mm的范围内,构件的极限抗拉承载力为钢管极限承载力的28%~32%,并且随着钢筋直径的增大,试件的极限抗拉承载力增大、延性减小;③在弯矩作用下,试件一侧受拉、另一侧受压,在节点的连接缝隙处钢管发生分离,受拉区灌浆料形成斜向裂缝;在钢筋直径为14~18 mm的范围内,构件的抗弯承载力为钢管承载力的37%~47%,并且随着钢筋直径的增大,试件的极限抗拉承载力增大、延性减小,试件的屈服位移和极限位移均增大. 展开更多
关键词 模块钢结构 节点 水泥基灌浆料 轴压性能 轴拉性能 抗弯性能
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预应力耗能钢框架抗连续倒塌机制研究
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作者 王述红 陈浩 +1 位作者 单思镝 魏崴 《建筑结构》 北大核心 2024年第16期52-59,共8页
针对预应力耗能(PTED)钢框架结构的连续倒塌问题,采用ABAQUS软件建立精细化有限元模型,对框架结构拆除承重构件后不平衡荷载重分配的行为展开研究。并将有限元结果与1/3缩尺PTED钢框架的准静态试验结果进行对比分析,验证了模型的准确性... 针对预应力耗能(PTED)钢框架结构的连续倒塌问题,采用ABAQUS软件建立精细化有限元模型,对框架结构拆除承重构件后不平衡荷载重分配的行为展开研究。并将有限元结果与1/3缩尺PTED钢框架的准静态试验结果进行对比分析,验证了模型的准确性。在此基础上,进一步开展了PTED钢框架抗连续倒塌受力机制的研究,并分析了初始预应力、预应力钢绞线数量、钢构件材料强度和梁翼缘宽厚比四种因素对钢框架抗连续倒塌机制的影响。结果表明:PTED钢框架抗连续倒塌过程主要包括三个阶段:初始阶段、压拱机制有利阶段和压拱机制不利阶段;倒塌抗力由预应力钢绞线拉力和梁柱之间的竖向作用力共同提供;提高初始预应力、预应力钢绞线数量、钢材屈服强度和降低梁翼缘宽厚比,均会使峰值荷载增大;钢绞线数量的增多使框架在失效柱位移较小时可以提供较大的抗力;增强梁柱构件抵抗局部屈曲变形的能力会提升预应力钢框架抗连续倒塌能力。 展开更多
关键词 自复位结构 预应力耗能钢框架 连续倒塌机制 抗力
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氯化胆碱/二醇基低共熔溶剂的理化性质及其结构表征
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作者 朱振宝 李翯 《陕西科技大学学报》 北大核心 2024年第1期37-44,共8页
近年来,低共熔溶剂具有类离子液体特性受到了越来越多的关注,与离子液体相比,低共熔溶剂不仅具有成本低、易合成等优势而且其应用领域更为广泛.为了拓宽其在食品领域中的应用,分别以氯化胆碱作为氢键受体,以乙二醇、1,3-丙二醇、1,4-丁... 近年来,低共熔溶剂具有类离子液体特性受到了越来越多的关注,与离子液体相比,低共熔溶剂不仅具有成本低、易合成等优势而且其应用领域更为广泛.为了拓宽其在食品领域中的应用,分别以氯化胆碱作为氢键受体,以乙二醇、1,3-丙二醇、1,4-丁二醇作为氢键供体合成和制备低共熔溶剂体系,利用FTIR和^(1)H NMR研究其氢键作用,并测定了不同温度(303.15~343.15 K)、摩尔比和烷基链长对其理化性质的影响.结果发现,随着二醇含量增加,氯化胆碱/醇基低共熔溶剂中氯化胆碱的氢键作用减弱,二元醇的氢键作用增强,氯化胆碱/乙二醇摩尔比(1∶3)形成的氢键作用比较适宜.并且,随着温度升高,低共熔溶剂的粘度降低,电导率升高,密度无明显变化.在同一温度下,随着烷基链长度的增加,低共熔溶剂的粘度和极性增强,电导率、表面张力、pH降低.随着醇基含量增加,其粘度降低,pH先升高后降低,极性、表面张力无明显变化.研究结果不仅揭示了氯化胆碱/二醇基低共熔溶剂体系的氢键作用,而且理化性质研究可以为其用于萃取领域提供科学指导,具有重要意义和价值. 展开更多
关键词 低共熔溶剂 结构表征 粘度 电导率 极性 表面张力 PH
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