有向图上基于层次树索引的最大cycle truss社区搜索

社区搜索旨在从信息网络中找出包含用户查询顶点的高内聚连通子图,cycle truss是一种基于cycle三角形的社区搜索模型,而现有的基于索引的cycle truss社区搜索方法存在索引空间大、搜索效率低、社区内聚性低的缺点。为了解决这一问题,提出一种基于层次树索引的最大cycle truss社区搜索方法。首先,提出了k-cycle truss分解算法,并引入了两个重要的概念:cycle三角连通与k-层次等价。基于k-层次等价设计了层次树索引TreeCIndex与表结构索引SuperTable,在此基础上,并基于这两个新的索引,提出了两个高效的cycle truss社区搜索算法。在4个真实数据集上与已有的基于TrussIndex与EquiTruss的社区搜索算法进行了比较,实验结果表明,TreeCIndex与SuperTable比TrussIndex与EquiTruss节省至少41.5%的空间,索引构建的时间节省8.2%至98.3%,且搜索最大cycle truss社区的效率分别高出了一个和两个数量级。

Control and vibration analyses of a sandwich doubly curved micro-composite shell with honeycomb,truss,and corrugated cores based on the fourth-order shear deformation theory

Curved shells are increasingly utilized in applied engineering due to their shared characteristics with other sandwich structures,flexibility,and attractive appearance.However,the inability of controlling and regulating vibrations and destroying them afterward is a challenge to scientists.In this paper,the curve shell equations and a linear quadratic regulator are adopted for the state feedback design to manage the structure vibrations in state space forms.A five-layer sandwich doubly curved micro-composite shell,comprising two piezoelectric layers for the sensor and actuator,is modeled by the fourth-order shear deformation theory.The core(honeycomb,truss,and corrugated)is analyzed for the bearing of transverse shear forces.The results show that the honeycomb core has a greater effect on the vibrations.When the parameters related to the core and the weight percentage of graphene increase,the frequency increases.The uniform distribution of graphene platelets results in the lowest natural frequency while the natural frequency increases.Furthermore,without taking into account the piezoelectric layers,the third-order shear deformation theory(TSDT)and fourth-order shear deformation theory(FOSDT)align closely.However,when the piezoelectric layers are incorporated,these two theories diverge significantly,with the frequencies in the FOSDT being lower than those in the TSDT.

Defect Inspection Technology for Steel Truss Suspension Bridges

Steel truss suspension bridges are prone to developing defects after prolonged use.These defects may include corrosion of the main cable or the steel truss.To ensure the normal and safe functioning of the suspension bridge,it is necessary to inspect for defects promptly,understand the cause of the defect,and locate it through the use of inspection technology.By promptly addressing defects,the suspension bridge’s safety can be ensured.The author has analyzed the common defects and causes of steel truss suspension bridges and proposed specific inspection technologies.This research is intended to aid in the timely discovery of steel truss suspension bridge defects.

异质网络中基于关键词属性的Truss社区搜索

社区搜索旨在信息网络中寻找与用户指定的查询节点高度相关的稠密连通子图,是社会网络分析的重要研究内容。现有的社区搜索方法大多是针对同质网络,但现实中的信息网络通常是包含多种节点类型和多种关系类型的属性异质网络。提出了异质网络中基于元路径P和元结构S的P-距离和S-距离及(k,d,P)-truss和(k,d,S)-truss社区模型以度量子图的结构内聚性,同时提出了关键词属性得分函数用于度量不同子图的关键词属性相关性,最后提出了搜索具有最高关键词属性得分的(k,d,P)-truss和(k,d,S)-truss的社区搜索算法。搜索算法能够找到同时具有结构内聚性和关键词属性相关性的个性化社区,并且支持限制查询节点与社区内任意节点的最大距离d来控制社区搜索的范围。在真实数据集上与相关的社区搜索算法进行了实验对比,结果证明了所提算法的有效性和可行性。

An experimental study of in-plane arch-shaped dampers

As an effort to minimize material utilization, seismic steel dampers designed to deform inelastically in an in-plane flexural mode have attracted serious attention recently. This paper presents a new type of metallic yielding damper referred to as the in-plane arch-shaped damper modified from its portal frame-shaped counterpart by replacing the straight beam with a circular arch to minimize the effects of stress concentration and warping, and therefore to avoid premature failure. Component tests of both the portal frame-shaped and arch-shaped in-plane dampers were conducted for comparison. Hysteresis loops obtained from the component tests under cyclic loads indicate substantial improvement on the energydissipative characteristics of the proposed damper. Moreover, seismic performance assessment of the proposed damper was carried out further via shaking table tests of a five-story model frame. Encouraging results have been achieved in terms of acceleration reduction, damping enhancement and peak suppression of the frequency response functions, suggesting the potential of the proposed device to be used in earthquake-resisting systems.

关于半导体厂房Truss层压力的探讨

以我国某新建的半导体芯片厂洁净室Truss层压力测试结果为例,利用在线监测和手持式仪表现场测试相结合的方法,来分析Truss层压力的变化的情况。测试发现核心生产区在符合设计规范的压力情况下[1],百级生产区相对应的Truss层为负压,而且负压值在30Pa左右;其他核心生产区域对应的Truss层也为微负压,负压值为10Pa左右,无法满足Truss层为微正压的技术要求。调试测试中发现,压力损失主要集中在局部阻力和沿程阻力,局部阻力主要是高架地板和DCC的压损;沿程阻力主要是下技术夹层至DCC之间以及过DCC后回风夹道至Truss层之间的压损。

Study on Truss Robot Structure of Refrigerator Automatic Loader

Aiming at the requirements of intelligent loading and shipping in large household appliance industry,an automatic loading and unloading robot for refrigerator is proposed.The robot is a gantry truss robot,which is composed of active support,passive support,beam and fixture components at both ends to realize the taking and placing of the refrigerator on the logistics transmission line to the truck.In the actual working conditions,the no-load truss robot experiment,found that the robot in the design problems,and the robot was optimized.It not only solves the safety hazards of the refrigerator when grabbing and stacking products,but also realizes the automation and intelligence of the refrigerator conveying process.

System Reliability Analysis for Truss Structures Based on Automatic Updated Model

Multiple failure modes tend to be identified in the reliability analysis of a redundant truss structure.This identification process involves updating the model for identifying the next potential failure members.Herein we intend to update the finite element model automatically in the identification process of failure modes and further perform the system reliability analysis efficiently.This study presents a framework that is implemented through the joint simulation of MATLAB and APDL and consists of three parts:reliability index of a single member,identification of dominant failure modes,and system-level reliability analysis for system reliability analysis of truss structures.Firstly,RSM(response surface method)combines with a constrained optimization model to calculate the reliability indices ofmembers.Then theβ-unzipping method is adopted to identify the dominant failuremodes,and the system function in MATLAB,as well as the EKILL command in APDL,is used to facilitate the automatic update of the finite element model and realize load-redistribution.Besides,the differential equivalence recursion algorithmis performed to approximate the reliability indices of failuremodes efficiently and accurately.Eventually,the PNET(probabilistic network evaluation technique)is used to calculate the joint failure probability as well as the system reliability index.Two illustrative examples demonstrate the accuracy and efficiency of the proposed system reliability analysis framework through comparison with corresponding references.

Mechanic Analysis of the Key Node in Steel Truss Bridge

Steel truss bridges are frequently used in bridge engineering because of their good ability of spanning capacity, construction and light self-weight. Main trusses are the critical component of steel truss bridge and the main truss are made of truss members linked by integral joints. This paper presents the mechanic performance of key joints, and the codified design of joints in steel truss girders according to the latest European norms. The results showed that the fatigue resistance of welded joints evaluation is necessary to predict, detect, and repair the crack in time for the safety service life of the bridge. The stresses of integral joint are greater than that of truss members;the stresses in the center area of the integral joint are greater than the stress at the edge.

大跨度钢桁架结构卸载模拟及监测技术研究

以江苏省盐城黄淮湿地博物馆钢桁架结构卸载施工为背景,旨在通过有限元技术及基于多传感器融合的现场监测技术研究大跨度桁架结构卸载施工关键技术。研究结果表明:有限元计算结果能够获取卸载施工过程中的关键要素,为后续监测方案的设计提供参考。后续的监测结果表明,有限元方法对位移的计算结果可靠性要高于应力,与实际情况更加接近;基于多传感器融合的监测方法能够提高监测结果的准确性和远程监控效果,为桁架结构的安全性和可靠性提供了有力支撑。研究结果可为大跨度钢结构建筑的施工提供参考。

大跨度钢桁梁桥智能建造技术应用的可行性研究

大跨度钢桁梁桥的构件制造及拼装复杂,采用场内预制组装仍需消耗大量的人力、财力及工期。因此,本文采用BIM桥梁建模、三维激光扫描和虚拟预拼装技术,进行了基于BIM技术的施工方案模拟的可行性研究和基于BIM技术与三维激光扫描方法结合的构件加工质量检测研究,并在此基础上进行了基于BIM技术与三维激光扫描方法结合的虚拟拼装技术研究,探索了大跨度钢桁梁桥智能建造技术应用于指导工程实施的可行性。

环形桁架式空间薄膜展开机构运动精度可靠性建模与分析

空间薄膜展开机构的姿态和位置精度会对薄膜索网的工作形态产生影响。文章首先构建环形桁架式空间薄膜展开机构运动精度可靠性理论模型,然后基于ADAMS建立考虑展开机构杆长误差的参数化仿真模型,并采用蒙特卡罗法对展开机构进行运动精度可靠性仿真分析,求解运动精度可靠度。结果表明,以机构展开到位时折展杆支撑点所拟合的空间圆心坐标位置误差及半径误差作为其运动精度可靠性量化评价指标是正确的。该研究可为空间薄膜展开机构的可靠性设计提供参考。

大跨斜拉桥双层桁架主梁施工状态的阻力系数

针对规范中对大跨径桁架桥的双层主梁阻力系数在取值上的局限,提出一种主梁阻力系数计算方法,以施工阶段节段模型的风洞试验结果为基础,对双层桁架主梁进行模型简化后,使用CFD计算得出其三分力系数.采用不同迎风面特征尺寸,桁架片数以及桁架间距,分析了迎风面特征尺寸对主梁的阻力系数的影响.讨论了桁架间距以及片数不同对主梁的阻力系数的影响趋势.结果表明:迎风面特征高度与特征宽度对主梁阻力系数影响的变化规律并不相同,对此提出以桁架纵高比为变量的双层桁架桥梁主梁的阻力系数拟合公式;当桁架间距较小时,桁架片数对主梁阻力系数无影响,但当桁架间距与桁架高度比值达到3时,桁架片数的变化会对主梁的阻力系数产生较大的影响.

大跨度公铁双层斜拉桥主梁涡激共振机理与控制

以拟建的某主跨808 m公铁双层斜拉桥为工程依托,采用节段模型风洞试验研究不同攻角下双层桁架梁断面的涡振性能及5种气动控制措施的抑振效果,结合计算流体动力学(CFD)静态绕流模拟,对比分析双层桁架梁断面的涡振机理及控制方法.研究表明:主梁断面原设计方案在+3°和0°风攻角下存在明显的竖向和扭转涡振现象,且振幅超过规范允许值;间隔封闭上层桥面栏杆或增设抑流板可有效抑制主梁扭转涡振,但竖向涡振振幅仍不满足规范要求;上弦杆外侧增设风嘴可有效抑制主梁竖向和扭转涡振,而下弦杆外侧增设风嘴对主梁涡振抑振效果有限.气流经主梁原设计断面上层桥面分离后,在其上下表面形成周期性脱落的大尺度旋涡,并在上层桥面后部再附,这是主梁发生竖向涡振的主要诱因;上弦杆外侧增设风嘴可引导气流平稳通过上层桥面,消除了周期性的旋涡脱落,并在其上表面形成一段狭长“回流区”,从而有效抑制了涡振的发生.

成都中海天府新区超高层项目结构设计

成都中海天府新区超高层项目建筑高度488.9m,为西南地区已建和在建的最高建筑物。塔楼采用巨柱框架⁃伸臂桁架⁃核心筒结构体系,具有8个环带桁架层和2个伸臂层,无外围巨型斜撑,次框架柱不连续的特点。介绍塔楼结构设计策略,包括结构整体性能参数、抗震性能目标和关键构件的性能水准的设定。阐述基础、环带桁架、伸臂桁架、巨型钢管混凝土柱、角部大悬挑、塔冠的结构布置及设计;进行了次框架结构的防连续倒塌分析以及加强层楼板、水平支撑、斜柱、斜墙等关键构件的计算分析;给出了与巨柱、伸臂相连的关键节点的构造措施以及结构长期荷载效应下的施工模拟结果和处理措施等。结果表明,结构体系及布置合理安全,各构件能够满足预定的性能目标。

高速铁路大跨钢桁加劲连续刚构桥长期变形影响因素研究

为研究钢桁长度和高度以及合龙顺序和顶推力对钢桁加劲连续刚构桥长期变形的影响,以某在建钢桁加劲连续刚构桥为对象,采用有限元软件建立实体模型,考虑混凝土收缩徐变作用,对恒载作用下运营20年内的变形进行分析,系统分析钢桁长度和高度对连续刚构桥长期变形的影响程度,同时利用结构力学原理推导不同合龙顺序下的顶推力解析式,探讨合龙顺序和顶推力对连续刚构桥长期变形的影响。结果表明:钢桁长度和高度的增加均可使挠跨比下降,均能提高桥梁的整体刚度,考虑到实际结构受力及施工难度,建议钢桁长度在桥梁中跨长度的3/4~7/8范围内选择,挠跨比下降42.3%~44.1%,为避免出现设计过于保守的情况,建议钢桁高度取12 m,挠跨比下降43.8%;推导出不同合龙顺序下的顶推力解析式,只与桥墩和主梁的参数有关,计算简便、概念清晰,可指导实际工程中顶推力的确定;不同合龙顺序对钢桁加劲连续刚构桥长期变形的影响较小,施加顶推力后可明显改善钢桁加劲连续刚构桥的长期变形,建议在施工过程中采用先中后边的合龙顺序,同时施加顶推力,在运营20年时边跨和中跨最大竖向变形分别下降34.6%和34.2%。

叠加空腹桁架的钢-钢骨混凝土组合转换桁架设计分析与监测

针对某上弦为钢骨构件、腹杆及下弦为型钢的钢-钢骨混凝土组合转换桁架结构,采用PKPM软件对组合转换桁架和其上空腹桁架进行了多个整体模型的弹性对比分析及静力推覆分析。结果表明,施工模拟方式、楼面板刚度模拟方式、混凝土空腹桁架构件徐变、中大震下出铰情况对转换桁架和空腹桁架分担的转换荷载计算值均有较大影响,相关因素应予包络、准确地考虑。对多个子结构组合而成的结构体系,应明晰各子结构在整体中发挥的作用,以及各子结构在相关因素变动情况下的定量变化情况,以保证各子结构性能稳定性和整体结构的安全。工程施工阶段监测表明,叠加空腹桁架的组合转换桁架结构变形及构件应变基本与设计预期相符,转换结构安全合理。

航天器复合材料桁架连接增强方法与验证

大型航天器主承载复合材料桁架局部承受过大的轴向拉伸载荷时,存在接头与杆件拉脱破坏的风险。基于胶接桁架碳纤维分层破坏机理,提出了外套管增强胶接、锥面配合增强胶接和组合增强胶接3种连接增强方案,通过优化传力路径达到降低层间应力的目的。针对3种连接增强方案,投产了相应的试件开展性能测试。经试验验证,胶接增强设计方法能够有效提高承载能力33%~66%,极限拉脱力达到200 kN,可为大型航天器主承载桁架研制提供参考。

深江铁路洪奇沥公铁大桥主桥设计关键技术

研究目的:洪奇沥公铁大桥是深江铁路的控制性工程,主桥采用主跨808 m公铁合建斜拉桥一跨跨越洪奇沥水道,上层布置8车道城市快速路,下层布置4线铁路。结合建设条件、结构特点及使用性能,对主桥结构体系、主梁横断面及结构形式、索-塔锚固结构、施工方法等关键技术展开研究,确定技术合理可行和经济节约的设计方案。研究结论:(1)首创了短边跨叠合板-桁组合梁斜拉桥结构体系,主桥长度减少20%,节省工程投资;(2)首次在4线铁路公铁合建斜拉桥上采用倒梯形双主桁截面,桥面布置紧凑、受力明确;(3)提出的边跨主梁采用矩形钢管混凝土叠合板-桁组合结构,集结构受力和锚固压重于一体,施工便捷;(4)发明了“自平衡交叉锚固+齿块锚固”的索-塔混合锚固方式,技术经济性高;(5)钢主梁创新采用“纵向大节段+横向分块”施工方法,解决了超宽超高超重整节段钢桁梁运输受既有桥净空限制的难题;(6)本研究成果可为公铁合建桁梁斜拉桥设计提供参考或借鉴。

天津空客A330宽体机厂房焊接加固过程结构性能监测与分析

大跨度钢桁架加固方法多采用焊接加固增大截面法.针对大跨度钢桁架屋盖整体结构的负载焊接加固,以天津空客A321(A330宽体机厂房)屋盖为例,采用4片角钢,分肢与原H型钢的翼缘、腹板分别焊接的加固方式,设计了合理的焊接加固方案与监测方案,对结构关键构件在焊接加固过程中的应力、应变进行监测.以监测数据为依据,研究分析焊接加固过程中型钢与加固角钢的应力响应规律,验证钢桁架梁采用角钢焊接加固的传力有效性,判断焊接热输入的影响范围.结果表明:在负载焊接加固的过程中,局部高温热影响区引起应力重分布,加固角钢的存在对原有型钢构件起到了相应的承担作用,焊接加固过程中结构的安全性可以得到保证.此外,焊接加固时,通过监测相邻杆件的应力和应变,分析表明焊接热影响的范围在两个节间范围内,且带来的应力响应较小.