共查询到20条相似文献，搜索用时 15 毫秒
1.
在建筑等工程领域中,需要张拉千斤顶给受拉构件中的钢筋施加预拉应力来提高构件的刚度和强度。张拉千斤顶的动力由高压电动油泵提供。从能量转换效率、工艺性可靠性等方面对四种高压电动油泵结构方案进行比较,确认叶片摆动油缸驱动双偏心轮式径向变量柱塞泵方案综合性能较优,能满足千斤顶在施工过程中的低压大流量和高压小流量工况变化要求,适合作为预应力施工机具高压电动油泵的设计方案。 相似文献
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李林 《西南师范大学学报(人文社会科学版)》2008,34(3):120-124
信息资源已经成为重要生产要素、无形的资产和社会财富,信息流能带动物资流、资金流和劳动力流动。信息资源可以有效突破城乡二元结构制约,形成工业对农业、城市对农村的反哺机制,成为推动社会主义新农村建设的强大动力。在分析农业信息服务内涵、理论和西部地区新农村建设实践问题基础上,提出在西部地区具体区情下发展信息服务、推动新农村建设的建议。 相似文献
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A new method was worked out to improve the precision of springback prediction in sheet metal forming by combining the finite element method (FEM) with the data mining (DM) technique. First the genetic algorithm (GA) was adopted for recognizing the material parameters. Then according to the even design idea, the suitable calculation scheme was confirmed, and FEM was used for calculating the springback. The computation results were compared with experiment data, the difference between them was taken as source data, and a new pattern recognition method of DM called hierarchical optimal map recognition method (HOMR) is applied for summarizing the calculation regulation in FEM. At the end, the mathematics model of the springback simulation was established.Based on the model, the calculation errors of springback can be controlled within 10 % compared with the experimental results. 相似文献
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林明生 《闽西职业技术学院学报》2007,9(2):35-37
在龙岩中山广场地下室顶板预应力项目的工程实践中,根据该广场地下室顶板的预应力设计、预应力筋的布置特点,结合施工中的管理以及技术经济分析,说明龙岩中山广场地下室超长顶板采用无粘结预应力技术,设计施工都是成功的,具有显著的社会和经济效益。 相似文献
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夏禹 《温州大学学报(社会科学版)》2004,17(2):29-31,35
本文叙述了预应力混凝土管桩的生产及在温州地区应用情况，并阐述了预应力混凝土管桩在建筑设计、运输、保管及施工中应注意的问题． 相似文献
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为配合因考虑地基辐射阻尼作用和大坝坝体横缝非线性应分析方法和动接触力计算模型，该文建立了对非线性结构反映静动荷载耦合作用的静动组合计算方法，使得动接触力模型能够用于静力问题的计算，同时使得静力计算和采用波动模拟方法的动力计算能够统一、连续进行。 相似文献
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The key in the force transmission between the tower and the foundation for offshore wind turbines is to transfer the large moment and horizontal loads.The finite element model of a large-scale prestres... 相似文献
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根据新型城镇化的内涵,构建人口城镇化、经济城镇化、公共服务城镇化、基础设施城镇化以及城乡一体化5个维度,运用熵值法对广西2003-2012年的城镇化水平进行评价,并在此基础上用主成分回归对广西新型城镇化动力进行分析,结果表明:广西新型城镇化水平不断提升,其中经济城镇化水平提高最快;影响广西新型城镇化发展的主要动力依次为行政力、产业集聚力、市场力和外向力。 相似文献
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工程力学中杆件内力计算的简捷方法是指利用截面左右侧上的外力直接计算内力.根据杆件发生不同的基本变形,可以归纳为:杆件某一截面上的内力等于截面一侧所有外力在沿杆轴线方向或垂直杆轴线方向上投影的代数和,或所有外力对截面形心的力矩的代数和. 相似文献
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A double strut cable dome structural system was presented to improve the mechanical behaviour of a cable dome. This structure has good stability and is convenient to construct. To investigate its construction method and static performance, a structural model with a 6-m diameter was designed. From the nodal equilibrium equation, the calculation formulas for the prestress distribution with self-weight considered were deduced. Two types of construction methods, namely, assembling at high altitude and integral lifting, were adopted in the shape-forming process of the double strut cable dome, monitoring the internal force of the cable-strut components and the structural deformation. According to loading tests under full-span load and half-span load, the static behaviour of the structure was obtained and compared with the results from finite element analysis. Using the formulas deduced in this paper, the actual initial prestress considering self-weight for a double strut cable dome can be obtained accurately. This structure was suitable for tensioning the outer diagonal cables to apply prestress. Combined with the construction method for integral lifting, the difficulty and workload of the construction process can clearly be reduced, making the structure favourable for engineering application. Under an external load, the internal force of the ridge cables and inner diagonal cables decreases and the internal force of the other components increases. The results of the model tests were in good agreement with those of the finite element analysis. 相似文献
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针对用户使用搜索引擎输入关键词查询信息时,由于输入法的原因或者不小心输入错误关键词等,致使搜索结果不符合用户预期的问题,提出基于搜索引擎日志的中文纠错方法。首先对用户网络日志展开研究,对数据进行预处理,将用户常见错误分为两大类：一类为拼音引起的错误,针对该类错误,参考并改进了基于拼音索引的中文模糊匹配算法进行纠错;另一类为多字、少字、异位及别字引起的错误,针对该类错误,设计了模糊匹配方法结合最小编辑距离方法进行纠错。经过实验验证,证明了该纠错方法的有效性,该方法能够一定程度上提升用户体验,满足实际工程需要。 相似文献
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新能源产业是一个复杂的系统,它的正常运行需要强大、稳健而持久的动力。新能源产业发展的动力因素包括技术进步、市场需求、产业链构建、政府政策和发展环境等。其中,技术进步、市场需求和产业链构建构成新能源产业发展的内部动力系统,政府政策和发展环境构成新能源产业发展的外部动力系统。内部动力系统和外部动力系统本身以及两大动力系统之间的协调运行构成新能源产业发展的动力机制。完善的动力机制是推动新能源产业健康快速发展的重要条件。 相似文献
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Miriam Reiner 《Interactive Learning Environments》2013,21(1):31-55
This paper examines the role of tactile perception in conceptual construction of forces and fields. The learning environment includes a simulation of a force field. The force applied by the field on an object is transferred to the learner's hand through a tactile interface designed as a trackball. The learner experiences varying resistance from the trackball when moving an object on the screen. The forces are actually “felt”, exerted on the screen-object as if the learner's hand is immersed in the “field.” We hypothesize that a tactile interface acts as an agent aimed at recruiting the body non-propositional knowledge, for construction of formal physics knowledge on fields of forces. Twelve subjects were asked to explore the structure of several invisible fields through tactile interface, then to design a series of situations that generate current and that energetically trap a particle in a particular area. The results of the study show that s tudents with no background in physics constructed a graphical representation of a field force of a single and double center of forces similar to the formal physics representation, though they had no conceptual background (i.e., vectors, field lines). Based on the tactile information, they constructed a representation of force as a vector, of force lines, equal-force lines (potential lines for particular cases), potential well (“trap”) and motion of a charged particle in a field of forces. We show that computer tactile interface acts as a trigger for access to non-propositional knowledge employed in everyday bodily activity, but not in formal learning. The computer environment turns into a virtual environment, carrying the features of perception within “reality”, providing opportunities for conceptual construction. 相似文献
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当剪力或轴力较大时，用纯弯曲方法计算弯矩误差很大。该文对弯矩、剪力及轴力联合作用下的板料弯曲提出了一个力学模型，并按此导出了有关的计算公式。 相似文献
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"双高计划"建设背景下,高职学校的科技服务工作需要在科研理念、服务路径、师资建设、管理体系等关键问题上找准坐标定位、把握工作重点、确定发展策略。高职学校应在系统研判国家发展战略、区域经济社会现状及产业结构的前提下,以应用型科研为基础,以产学研用融合发展为导向,以区域内中小微企业及广大农村为主要服务对象,通过打造科技创新团队、产教融合创新平台、技术技能研发平台,建设中小微企业技术服务中心、产业学院、科技产业园区等各类科技服务形式融合发展,不断增强自主创新能力和整体科研实力,以科技进步和创新驱动聚力提升新旧动能转换质效,为加快构建区域现代化经济体系做出应有的贡献。 相似文献
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Dynamic tests of three bonded and two unbonded full-prestressed concrete beams were carried out.The purpose was to seek the relation between prestressing force and natural frequency.Test results indicate that the frequency of prestressed concrete(PSC)beam increases with the increase in prestressing force approximately.The results are different from the dynamic characteristics of isotropic material beam subjected to compressive axial force which were put forward by Clough et al.The reason is that the beams were considered as isotropic,homogeneous,linear elastic material in the traditional analysis method.However,more accurate results are required in the analysis of frequency of PSC beam.The constitutive mode of PSC member is analyzed based on microstructure of concrete in this paper.The orthotropic linear elastic mode is used to analyze the relation between dynamic frequency and prestressing force of concrete beam,at the same time the equivalent stiffness of prestressed tendon relating to the prestressing force is added to the bending deformation stiffness of the beam.The analytical value agrees well with the test result,indicating that the current analysis method in this paper is feasible to full-prestressed concrete beam. 相似文献
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Civil and Hydraulic Engineering Calculation of corrosion rate for reinforced concrete beams based on corrosive crack width简 总被引：1，自引：0，他引：1
This paper deals with a correction method for corrosive crack width caused by non-uniform corrosion. Considering the corrosion cracking characteristics of a reinforced concrete structure, a correction model of corrosive crack width involving the mutual impacts between adjacent measuring points is established. The calculation model for steel bar corrosion rate for single point is obtained through quantitative analysis and accelerated corrosion tests on more than 70 reinforced cubic members. Two methods are suggested by combining two models, the correction and the corrosion calculation ones. Electrolyte accelerated cor- rosion tests on seven beams are carried out to verify these methods. The experimental results show that the ratio between the maximum corrosion rate by the indirect method and the measured average value ranges from 1.4 to 2.4, and the indirect method is shown to be an effective method for calculating the maximum corrosion rate. 相似文献
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杨根宏 《泰州职业技术学院学报》2010,10(3):68-71
对受腐蚀的多层混凝土框架结构化工厂房进行加固改造,改变其使用功能,改造成为两条生产线的混凝土搅拌楼。重点从设计及施工工艺方面论述受腐蚀混凝土柱、梁、板的加固处理技术,受腐蚀的梁和柱优先采用加大截面法,板采用体外预应力法。 相似文献