厚壁岔管的应力分析

文中用有限单元法的三维等参元对岔管进行了应力分析,给出了岔管交接区的影响范围L=2.7(Rt)~(1/2)。对已有实验结果的岔管进行了计算,计算表明:用三维等参元分析厚壁岔管是有效的方法。文中的程序可用于分析各种回转体岔管,例如锥形岔管。     

管类件定径挤压极限变形程度的数值模拟

分析了管类件定径挤压成形工艺，借助于有限元软件Deform-3D平台，对不同参数组合的45^#管类件定径挤压工艺进行了有限元数值模拟。给出了成形极限范围和不同参数对极限变形程度的影响规律。     

WDB620高强钢月牙肋岔管制造技术

本文结合哈萨克斯坦玛依纳水电站月牙肋钢岔管的特点,总结了应用国产WDB620高强钢,板厚最大达120mm的钢岔管在加工厂的制造工艺,具体包括锥体加工、岔管拼装、肋板焊接、水压试验与应力检测等关键技术,可以为其它钢岔管、类似压力容器的制造提供依据和参考。     

弯管传感器弯径比的三坐标测量方法

通过对ZWL型智能弯管流量计中弯管传感器弯径比测量方法的不断探索,本文提出了用三坐标测量机对弯管传感器进行测量的方法。建立求解弯径比的数学模型,三坐标测量机测取三维坐标点和用MATLAB软件编写弯径比的计算软件,求出弯径比的计算结果。该方法具有较高的精度,并且操作方便,具有通用性。     

引水分流岔管上调压室位置优化研究

针对水电站引水分流岔管上布置长廊式调压室的局部水头损失特性，采用有限体积法离散控制方程，使用SIMPLEC算法耦合速度、压力场，选用适合高雷诺数流场计算的realizable k-（紊流模型计算研究了调压室不同位置处系统局部水头损失的变化规律。计算表明：引水分流岔管上布置调压室能减小系统局部水头损失：调压室位置变化使系统局部水头损失随之改变：调压室阻抗孔位于岔管内壁高流速区外边界时系统局部水头损失最小。     

侧向过岔时轮径差对高速车辆动力学性能的影响

轮径差的出现会影响高速车辆通过道岔时的动态性能，尤其是侧向过岔的情况。为进一步揭示其影响规律，本文以高速车辆和18号高速道岔为例，建立车辆—道岔耦合动力学模型，分析不同轮径差下高速车辆以80 km/h侧向过岔时的动力学特性。结果表明，大轮径位于尖轨侧时，等值同相轮径差会减小轮轨横向力和车体横向加速度；大轮径位于基本轨侧时，等值反相轮径差会增大高速车辆侧向过岔时的脱轨系数和轮重减载率。由于实际运营中高速车辆轮径差类型不确定，应尽量避免轮径差超过1 mm,以确保高速车辆侧向过岔时的安全性与平稳性不受影响；尖轨侧车轮轮径大于基本轨侧时车轮磨耗加剧，故应避免此类情况发生，以延长车轮和钢轨的寿命。     

地下工程新技术的实践

广蓄电站高压岔管的P.D值达5.8×10４kN·m，未采用常规的钢岔管，在钢筋混凝土岔管设计原则上，主要依靠围岩承担水压力。施工中从控制爆破、混凝土质量、高压灌浆等方面实现设计意图。这种结构安全可靠，投资省，效益好。广蓄斜井引进了一套间断式的斜井滑模，经改进和完善，获得了成功。在天荒坪抽水蓄能电站长斜井施工中，研制了自主知识产权的XHM-7型斜井滑模设备，实现了斜井混凝土衬砌的连续滑升，显示了该设备结构新颖、安全可靠、速度快、造价低的优势。以上两项新技术的成功实践，为我国类似工程的推广和应用提供了有益的经验。     

钢岔管CAD/CAM系统的研究与开发

给出以Visual Basic5.0 为平台,与AutoCAD相集成,设计出一套钢岔管CAD／CAM的实用软件的具体过程,成功实现了钢岔管施工放样详图的计算机辅助设计及钢板下料的计算机辅助制造。该系统能计算并绘制四种类型岔管的全套放样图,并通过CAD／CAM系统的集成,可将CAD参数传递给CAM子系统,生成焊缝代码文件,实现下料及焊接。     

大型钢岔管洞外拼装及水压试验施工技术研究

本文针对大型钢岔管在洞外进行拼装及水压试验,介绍了钢岔管拼装顺序,并对水压试验项目中涉及的试验流程、应力测试、残余应力测试、声发射检测、变形检测等内容,进行了详细论述。     

用最小二乘法评定螺纹中径的测量结果

本文用最小二乘法建立螺纹牙侧的一线性咽归模型，按照螺纹中径定义确定中径圆柱线线与牙侧交点的坐标，求出螺纹中径尺寸，并按概率统计原理该中尺寸的置信区间。     

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.     

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...     

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.     

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.……     

The Research of Anti-Wear Properties of Organomolybdenum Compounds in the Engine Oils

A four-ball tester was used to evaluate the anti-wear performance of three kinds of organomolybdemun compounds in the engine oils, i. e., molybdenum dialkyldithiophosphate (MoDDP), molybdenum dialkyldithiocarbamate ( MoDTC), and sulphur and phosphorus freeorganomolybdeum (Molybdate). The results indicate that a low concentration of MoDDP doesn' t improve the anti-wear properties of the commercial engine oils, but a high concentration of MoDDP can obviously improve the anti-wear properties and the load-carrying capacity of the engine oils. MoDTC doesn' t improve the antiwear properties of the engine oils, but worsens the anti-wear properties of the oils. Signifi can timprove ment of frictional and wear characteristics is obtained with Molybdate added in the commercial engine oils and the formulated oils.     

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.     

Synthesis of Alumina-Zirconia Nanocomposites by Solgel Process

Al₂O₃-ZrO₂ nanocomposites were developed starting with the solgel process. Composite alumina-zirconia nanopowders were synthesized from metallorganic precursors (Aluminium secondary butoxide and zirconium Iso propoxide) using the solgel process. The parameters affecting the synthesis—solvent, concentration of precursor, R/H ratio (i.e., dilution of water in solvent)—were varied as also the temperature and pH. BET and TEM were used to measure nanosize. Diffuse reflectance spectroscopy and also qualitative optical absorption led to identical particle size estimate. The variation of process parameters was used to study the effect and interdependence of process parameters. Artificial Neural Networks was used to rigorously analyze the process. Although this led to confirmation of interdependence of parameters, the presence of a single overwhelming solvent variable was also established. Then the optimal process was used to synthesize more nanopowder. To produce bulk nanocomposite the nanopowders were sintered by varying the temperature and time period. The sintered lithoids were probed with a vickers hardness tester to measure elastic modulus, hardness, and fracture toughness. The results showed high elastic modulus, modest hardness, and very high fracture toughness.     

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.……     

Friction Stir Processing Strategies for Uniform Distribution of Reinforcement in a Surface Composite

Friction stir processing (FSP) is an important technique for preparing surface composites. Fabricating defect-free surface composites with uniform particle distribution by FSP is a challenging task. In this study, silicon carbide particles reinforced AA5083 alloy surface composites was fabricated using different FSP strategies including variation in process parameters, dual-tool processing and tool offset overlapping. Material flow of the processed material with reinforcement particles demonstrated that the distribution of particles was influenced by the stirring action of the probe as well as the extrusion of the plasticized material due to the movement of the tool. Process parameters, particularly rotational speed, showed a dominant influence on the distribution of silicon carbide particles.