某钢管桁架设计计算若干问题的讨论

某工程钢管桁架计算分析表明,杆间荷载产生的次弯矩效应不容忽略,按现行STS版本建模时可采用增设节点的办法处理。本文对桁架设计中减少次弯矩的调整思路、对半铰结构计算模型及对桁架腹杆设置的讨论可供类似工程参考。     

弯道悬沙特性试验研究

本文重点研究弯道悬沙水流的水力特征和泥沙特征变化以及弯道半径对其影响。试验表明,弯道悬沙水流水面横比降与清水相比略有差异,悬沙水流较清水时弯道水面横比降小,弯道半径越大,差异越小。水流入弯道后,水流流速、水流含沙量以及悬沙粒径均进行了重分布。弯道凹凸岸最大流速调整位置随弯道半径的减小而下移。弯道内凸岸含沙量逐渐增加,悬沙粒径也逐渐增粗,在弯道末端断面,凸岸含沙量与凹岸含沙量比值达到最大值,相应凸岸悬沙中值粒径与凹岸悬沙中值粒径比值也达到最大。弯道半径不同,泥沙在横向调整程度也不同。     

冷弯型钢输电铁塔主斜材连接方式的理论和试验研究

冷弯薄壁型钢是一种高效经济型钢材，传统输电铁塔设计采用的都是普通热轧型钢。随着电力事业的不断发展开发利用新型输电铁塔势在必行。为此，本文在研究了采用这种新型钢材设计输电铁塔强度问题之后（可省钢材３０％左右）。又通过理论和试验对构件节点连接方式的问题做了进一步研究。为其应用提供了理论根据。     

回转窑轮带应力和材质探索

回转窑轮带主要承受温差应力、弯曲应力和接触应力。因此,正确计算并合理控制这三种应力就可有效提高轮带的使用性能和使用寿命。如在支撑结构位置的设计、耐火材料的选用、原料选择及操作控制方面,都应考虑降低轮带内外温差的技术措施,以降低温差应力。文章详细介绍了这三种应力的计算公式;并分析了合金元素Cr,Mn,Si,Mo对铸钢组织性能的影响。最后,还介绍了回转窑轮带材质的发展及其许用应力的确定。     

喷嘴洗涤器弯头开孔结构有限元分析及强度评定

由于弯头开孔结构无法按常规设计方法进行开孔补强计算,故对弯头接管开孔区域建立了三维有限元力学分析模型。利用三维实体模型,真实地模拟了特殊结构的形状、载荷分布、边界条件,计算出最接近真实状况的应力分布情况;根据有限元分析结果,按JB4732-1995《钢制压力容器——分析设计标准》进行了应力强度评定,为详细工程设计提供了弯头开孔补强计算方法。     

Flow disturbance compensation calculated with flow simulations for ultrasonic clamp-on flowmeters with optimized path arrangement

Ultrasonic clamp-on flowmeters (USCF) are popular among measurement technologies due to the versatility of applications, increasing accuracy, and easy, non-intrusive mounting, with the sensors being mounted directly on the external surface of the pipe. In industrial applications, installation space is usually restricted and therefore, flowmeters must be mounted often directly downstream of flow disturbances (FD). A major issue of USCF is the long inlet run needed downstream of FD to achieve a measurement within the specified accuracy. A configuration of two V-paths is proposed, axially rotated 90° relative to each other, that compensates for the flow error introduced due to disturbed flow conditions, independent of the rotational position of the flowmeter. Flow disturbance compensation (FlowDC) is achieved, i.e., accurate measurements within the specification of 2% flow rate accuracy, when the flowmeter is mounted as close as 2 pipe diameters (D) downstream of a FD. Computational fluid dynamics (CFD) are employed to generate rotationally independent correction factors that compensate for the error introduced from disturbed inlet conditions. An automated simulation method is developed to generate correction factors for 90° bend, out-of-plane bend, expansion, and contraction, at mounting distances from 2D to 100D, several flow rates, and rotational positions 0°, 90°, 180°, 270°. This study would be practically impossible with non-automated simulations or solely with measurements. In-house experiments were performed with an industrial clamp-on device at selected distances from the FD with the aim of verifying the simulation results. An independent field-test is presented that showcases the value of FlowDC in USCF applications. The automated simulations have the capability to simulate further FDs on-demand, with the aim of creating a database for the needs of the respective application in industry.     

斜楔滑块机构在弯曲级进模中的新应用

在分析制件的基础上,介绍了"压缩机储液罐托架"的冲压排样方式的选择、关键工位冲压工艺的特点和模具的结构设计。     

大口径弯管国产化技术问题探讨

本文从国内我油气管道大口径弯管制造装备现状，技术标准及陕京输气管道工程弯管制造国产化的经验，论证了大口径弯管制造国产化的可能性，并提出了大口径弯管国产化的工作方法和步骤。     

Generalized mixed-mode reflective LCDs with large cell gaps and high contrast ratios

Abstract— A generalized mixed twisted-nematic/birefringent-effect mode reflective LCD is presented. This new mode encompasses all previously published reflective nematic LCD modes and is clearly shown on the parameter space diagrams. We also discuss how to obtain operating conditions of this generalized mixed-mode display with large cell gaps, low color dispersion, and high contrast at low voltages. This operating mode is particularly suitable for reflective crystalline-silicon-backplane active-matrix LCDs.     

热带钢精轧机板形在线设定系统设计

结合1450mm6机架热带钢连轧机板形在线设定系统软件，介绍了该系统的数据通信、多线程编程方法和数据处理等，并推导了弯辊力预设定模型及其补偿系数。通过对现场考核，并分析了系统投入前后大量实测结果的统计情况，证明了设定模型的有效性、数据通信的可靠性和多线程编程方式的优越性。