三峡升船机塔柱横梁支撑系统设计

本文介绍了三峡升船机塔柱横梁混凝土施工支撑系统的实施方案,从贝雷架支撑体系所承受荷载要求、结构强度要求以及变形稳定性要求出发,通过科学计算制定出合理的贝雷架支撑系统的支座系统设计方案、结构设计方案以及上部钢管排架设计方案,并对贝雷架支撑系统以及相应的塔柱混凝土墙体结构在混凝土浇筑前后以及混凝土浇筑过程中的应力（应变）、变形、位移进行了监测。监测结果表明,横梁支撑系统满足了横梁浇筑支撑要求,施工质量优良,安全可靠,设计与施工方案可行。     

三峡升船机塔柱横梁混凝土施工技术

三峡升船机船厢室段塔柱承重结构的横梁混凝土浇筑施工难度大、复杂性高、无成熟技术可供参考。本文结合三峡升船机塔柱横梁混凝土浇筑的结构特点以及施工特性,总结了三峡升船机续建工程顶部横梁混凝土的施工技术,即采用分层、分块浇筑的办法,通过科学计算后进行合理的施工机械布置和浇筑施工管理,以保证塔柱横梁混凝土的施工质量。通过对贝雷架支撑系统的监测结果分析可知,贝雷架支撑系统的应力变形、挠度变形以及排架变形均满足施工承载要求,筒体位移亦满足技术要求,贝雷架支撑系统稳定、安全。三峡升船机塔柱横梁混凝土施工实践证明了本技术方案的有效性与可靠性,亦可为类似工程的施工组织设计与现场实施工作提供一定的参考。     

三峡升船机横梁贝雷架支撑系统荷载试验

在三峡升船机续建工程中,针对塔柱横梁施工支撑体系复杂的特点,在横梁混凝土浇筑前进行荷载试验。试验选取轴1、轴2横梁及其相应的基础梁贝雷架作为模型,按照1∶1进行荷载原型试验,通过布置监测点以及采用合理的检测频率,完成试验数据的采集与分析。本次试验取得以下成果：得出了各类型杆件在加载过程中的最大应力值;随着加载量的增加,横梁、基础梁贝雷架的挠度变化量慢慢增大,模板及排架立杆高程在下降;随着加载量的增加,横梁、基础梁贝雷架都发生了较小的侧向位移,轴2横梁模板左右方向变化量和排架立杆垂直度左右方向变化量均很小;试验监测数据表明,经加强后的贝雷架杆件加载后的各项参数满足安全要求,技术方案可应用于塔柱横梁施工,保证升船机塔柱横梁施工安全。     

高支模自动化实时监测在混凝土浇筑过程中的分析与应用

高支模自动化实时监测为建筑业安全生产起到预防事故、减少损失的积极作用。该文通过对某工程建筑高大模板的自动化实时监测在混凝土浇筑过程中的支架整体水平位移、模板沉降、立杆轴力、立杆倾角监测值分析,论述了高支模自动化实时监测在混凝土浇筑过程中的应用,可以整体、实时、多参数监控监测高支模,能够及时自动预、报警和排除险情,保障作业人员的人身安全。     

拉伸速率控制模式及拉伸速率对冷轧薄板强度测试结果的影响

按照GB/T 228.1—2010中推荐的不同拉伸速率控制模式及拉伸速率对冷轧镀锌钢板进行了拉伸对比试验,分析了应变速率、横梁位移速率及应力速率对冷轧薄板规定非比例延伸强度R_p0.2、下屈服强度R以及抗拉强度R_tn测试结果的影响。结果表明:采用应变速率进行控制得到的拉伸试验数据相对其他两种速率控制模式更为稳定,可以最大限度地降低拉伸测试结果的不确定度;采用0.000 25 s^-1的应变速率控制模式所得试验结果的稳定性与采用40～50 MPa·s^-1的应力速率控制模式所得结果较为接近;在不同拉伸速率控制模式下,提高应变、横梁位移和应力速率均会使屈服强度R_p0.2和R_el增加,而抗拉强度R_tn基本上处于稳定状态。     

浅谈混凝土温度裂缝的控制

在混凝土浇筑工程中,由于混凝土受到自约束拉应力和外约束拉应力的影响将产生裂缝。因此需要在施工过程中采取有效的控温措施,以保证混凝土的质量。本文作者通过对混凝土温度监测及温度裂缝控制过程及防止裂缝的措施进行了阐述。     

基于锚索格构梁支护结构的高边坡健康监测研究与分析

在陇南山区,边坡工程安全问题日益突出,对边坡工程进行监测预警尤为必要。该文依托舟曲灾后重建项目某高边坡加固工程实例,建立了一套综合立体的边坡自动化监测系统。通过对边坡应力、位移的监测与分析,发现了边坡在施工和运营阶段的一些变化特征和规律:边坡支护初期,应力、位移变化的幅度较大;随着支护结构与边坡内部岩体的相互调整,二者变化趋于平稳。该边坡支护结束至今:最大位移变化速度为0.24mm/d﹤0.5mm/d,监测点最大位移累积变化量小于10mm,最大加速度为0.31mm/d2;格构梁的受力与变形也均处于弹性范围之内;边坡内部水平位移变化也较小。综合各项监测结果可以得出,锚索格构梁可以对该边坡起到有效的加固效果,该边坡在运营阶段处于稳定状态。该试验对今后同类边坡的加固设计与监测分析具有一定的参考价值。     

对金属材料拉伸试验方法标准中推荐应变控制和刚度修正方法的验证分析

采用两种拉伸标样验证了包括TENSTAND研究报告中6种方法在内的11种方法测试屈服强度的结果,证明在相同名义应变速率条件下横梁位移控制方式和应变控制方式测试得到的屈服强度是一致的。分析发现GB/T 228.1-2010中推荐应变控制和刚度修正,是由于TENSTAND WP4报告中的图38和图39误导了TENSTAND报告的结论,TENSTAND报告结论又误导了ISO 6892-1-2009和GB/T 228.1-2010的制定。通过模拟试验发现TENSTAND WP4报告中图38标称的横梁位移控制方式,实际不是采用横梁位移控制方式而是采用实时应力控制方式并在实时应力速率无法维持时切换为横梁位移控制方式。分析了造成TENSTAND WP4报告中图39横梁位移控制方式测得的屈服强度高于应变控制方式的原因是因为采用了刚度修正。分析找出了刚度修正错误的理论根源是把仅适用于弹性段的胡克定律错用到了测试屈服强度的塑性段。     

速率控制模式对GH4169高温合金拉伸性能的影响

通过对应变硬化指数、拉伸试验数据和微观晶粒形貌等进行分析,讨论了引伸计控制期间真应变在0.8%~1.6%,速率控制模式对GH4169高温合金室温(23±5)℃及高温(650±3)℃拉伸性能的影响。结果表明:室温下,应变控制模式测得的强度指标高于横梁位移控制模式测得的,而应变控制模式测得的塑性指标低于横梁位移控制模式测得的;高温下,应变控制模式与横梁位移控制模式测得的强度指标和塑性指标差异均可以忽略不计。     

再生混凝土三轴受压力学性能试验研究

为了研究再生混凝土在三轴应力状态下的力学性能,以再生骨料取代率和围压值为变化参数,设计了36个圆柱体试件,采用位移控制的加载方式进行常规三轴试验。通过试验观察了试件的破坏形态,获取试件受力破坏全过程应力-应变曲线以及峰值应力、峰值应变等特征参数,分析了再生骨料取代率和围压值对再生混凝土三轴受压力学性能的影响,提出了侧向围压值与初始弹性模量、竖向峰值应力、峰值应变之间的关系公式。研究结果表明:取代率对三轴受力再生混凝土的峰值应力和峰值应变影响不大,与天然混凝土相比,其变化分别在5%和2%的范围内波动,而取代率对再生混凝土的初始弹性模量有较大的影响,与天然混凝土相比,三轴受力再生混凝土的弹性模量提高了20%左右;侧向围压值对三轴受力再生混凝土的各项性能指标影响显著,增大围压值能有效提高再生混凝土的弹性模量、承载能力和变形性能。研究结果为再生混凝土的进一步科学研究和推广应用提供参考。     

Insertion of triangulated surfaces into a meccano tetrahedral discretization by means of mesh refinement and optimization procedures

In this paper, we present a new method for inserting several triangulated surfaces into an existing tetrahedral mesh generated by the meccano method. The result is a conformal mesh where each inserted surface is approximated by a set of faces of the final tetrahedral mesh. First, the tetrahedral mesh is refined around the inserted surfaces to capture their geometric features. Second, each immersed surface is approximated by a set of faces from the tetrahedral mesh. Third, following a novel approach, the nodes of the approximated surfaces are mapped to the corresponding immersed surface. Fourth, we untangle and smooth the mesh by optimizing a regularized shape distortion measure for tetrahedral elements in which we move all the nodes of the mesh, restricting the movement of the edge and surface nodes along the corresponding entity they belong to. The refining process allows approximating the immersed surface for any initial meccano tetrahedral mesh. Moreover, the proposed projection method avoids computational expensive geometric projections. Finally, the applied simultaneous untangling and smoothing process delivers a high‐quality mesh and ensures that the immersed surfaces are interpolated. Several examples are presented to assess the properties of the proposed method.     

Certification Institutions Expected to Update and Transfer Information on Present Standards

Standards are the basis for production enterprises to organize production, ex-factory inspection, trade (delivery) and technical exchanges, product certification, quality arbitration and supervision.……     

From Industry 4.0 to Research 4.0. Development of High Performance Fibers in the Light of Digitization

We associate a variety of innovations with the term ＂Industry 4.0＂. The pioneer of many 4.0 modifications forms the basisfor the trend towards the integrated di...     

Flow calorimeter for enthalpy increment measurements on condensed gases

A flow calorimeter for enthalpy increment measurements on condensed gases is presented. A better knowledge of the properties of the liquefied natural gas is needed, and therefore a liquid loop has been designed for our flow calorimeter. The fluid loop in the calorimeter is designed in order to avoid the two-phase region, since two phases would give compositional disturbances in the measurements. The avoidance of the two-phase region is made possible by increasing the pressure of the test fluid after the measurement section, then heating the fluid at super-critical pressure past the critical point. Finally, the fluid is throttled to the low-pressure gas state at the inlet condition of the compressor that circulates the fluid. To perform the pressure increase, a new cryogenic pump has been designed. To evaluate the new equipment, measurements were taken on liquid ethane over the temperature range 146–256 K at pressure between 0.9 and 5.1 MPa.     

Refrigerators Enter a New Era of Health Preservation Frestech initiates the establishment of China's first standard for household sterilization refrigerators

On November 30, 2007, the China Association for Standardization (CAS) held a press conference at Beijing Diaoyutai State Guest House. Leaders from the China Household Electric Appliance Research Institute, the China Household Electric Appliance Association, and the China Consumers' Association attended and made speeches.……     

Roman iron and steel: A review

ABSTRACT

The production of ferrous metal increased during the Roman Late Republican period, Principate and Empire. The direct bloomery process was used to extract the metal from its ores using slag-tapping and slag-pit furnaces. The fuel was charcoal and an air blast was introduced by bellows-operated tuyères. Iron formed as a bloom, often as a spongy mass of metal, which contained impurities from the smelting process, including unreacted ore, fuel, slag and fragments from the furnace walls, while the metal was often inhomogeneous with varied carbon contents. Blooms were either smithed directly into bars or ingots or they were broken up, which also allowed the removal of gross impurities and a selection of pieces with similar properties to be made. These could then be forge-welded together and formed into characteristically shaped ingots. Making steel in the furnace seems to have been achieved: it depended on the ore and the furnace and conditions within it. Surface carburization was also carried out. Iron and steel were used extensively in construction and for tools and weapons. Fire welding was often used to add pieces of steel to make the edges of tools and weapons, which could be heat-treated by quenching to harden them.     

Optimum-Simulation von Ernteprozessen

Zusammenfassung Bei der Gestaltung von Ernteprozessen — beispielsweise des Prozesses Mähdrusch, Körnertransport und -abnahme — als transportverbundene Fließarbeitsverfahren mit mindestens zwei verschiedenen Arbeitsmitteln gibt es einen großen Optimierungsspielraum. Solche Prozesse sind mehrstufige Bedienungsprozesse mit gemischter Anordnung der Bedienungseinrichtungen. Außerdem besitzen sie stark ausgeprägte räumliche Aspekte. Es wird vor allem gezeigt, welche Merkmale solcher Prozesse in Simulationsmodellen abgebildet sein müssen, welche Zielgrößen in Abhängigkeit von welchen Einflußgrößen unter Berücksichtigung welcher Prozeßbedingungen ermittelt werden sollten und wie der Bewertungsprozeß zur Ermittlung der gewünschten Informationen gestaltet werden muß.     

A study of centrifugal cast high boron high speed steel

In the present study a high‐boron high speed steel (HSS) roll material was designed. Many expensive alloy elements have been substituted by cheap boron alloy, and high‐boron high speed steel roll has been manufactured by centrifugal casting method. The microstructures, mechanical properties and wear resistance of centrifugal casting high‐boron high speed steel roll have been investigated by optical microscopy (OM), scanning electron microscopy (SEM), and X‐ray diffraction (XRD) analysis, hardness test, impact test and wear test. The results indicated that the solidification microstructures of high‐boron high speed steel roll consisted of M₂(B,C), (W,Mo)₂(B,C), M₃(B,C), M₂₃(B,C)₆ type borocarbides and martensite, a small amount of retained austenite. Borocarbides were continuously distributed over the grain boundary. After quenching from 1050 °C, local broken network appeared in partial borocarbides, and fine secondary borocarbide precipitated from the matrix. After tempering from 525 °C, the amount of precipitated borocarbide increased significantly. After heat treatment, the hardness of high‐boron high speed steel roll excelled 60 HRC, and its impact toughness excelled 8.0 J/cm². The single groove steel rolling amount of high‐boron high speed steel rolls increases by 500% than that of bainite cast iron roll, when the rolls are used in K₁ mill housing of bar mill.     

Thixotropy of Systems with Shear Thinning and Plastic Flow Behavior

The definition of the thixotropy is a decrease in viscosity with time in shear and a subsequent recovery of viscosity after the shear deformation is removed.We ...