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991.
ABSTRACTIn order to effectively implement measures against the adverse effects of large earthquakes on telecommunication conduits, it is important to elucidate which conduit is vulnerable. Telecommunication conduits consist of pipe bodies and joints, and as is well known the joints are weaker than the bodies against seismic loading. Hence, the seismic performance of the conduits depends on the performance of the joints. To maintain conduits properly, the corrosion rate of conduits' joint in the field must be determined. Several sites were selected and investigated for the amount of stagnant water in manholes. Next, the stagnant water test specimens were collected and observed for the extent of corrosion inside via a pipe camera, and subsequently analysed collected water test specimens. Moreover, the solution resistances and polarisation resistances using the AC impedance method and carbon steel coupons were measured. The experiments revealed differences between the measured values recorded at the different sites. It was also found that some data were related to corrosion on the inside of the conduits.This paper is part of a supplementary issue from the 17th Asia-Pacific Corrosion Control Conference (APCCC-17). 相似文献
992.
通过优化螺杆组合,研究了CFRPA复合材料中碳纤维的长度分布对其力学性能的影响,用MM-200磨损试验机测试了CFRPA复合材料的磨损性能。结果表明:通过适当的螺杆组合,复合材料的力学性能显著提高,合适的螺杆组合可以使树脂中长碳纤维的比例增大,改善增强效果,使CFRPA的耐磨性提高,摩擦系数下降。 相似文献
993.
994.
应用多普勒激光测速计测量同向旋转双螺杆挤出机捏合区域的速度分布。在90r/min的转速下,测量了两螺杆捏合区中推力区和阻力区熔体的轴向速度和法和速度。 相似文献
995.
牛顿流体单螺杆挤出中速度场的坐标系依赖性 总被引:2,自引:0,他引:2
利用简化同心无限长圆筒地牛顿流体单螺杆挤出中不同坐标系选取,即机筒转、螺杆静止和直转、机筒静止两种情形,讨论了所产生的速度场差异问题。结果表明,速度场对坐标系存在着依赖性。螺杆、机筒间间隙相对机筒直径值(H/D)越大,引起的差异就越大,深螺槽时效应尤为明显。还给出了定量评价此作用的一个修正系数。 相似文献
996.
Melt mixing in an extruder with polymers is an effective approach for forming nanocomposites, allowing mass production applications. The intent of this study is to investigate carbon nanofiber composites with ultrahigh molecular weight polyethylene (UHMWPE) matrix using the twin‐screw extruder. To decrease the high viscosity of UHMWPE, a low density polyethylene (LDPE) was added into the UHMWPE. The effects of carbon nanofibers (CNFs) on the crystalline structures and properties of the nanocomposites were analyzed. The differential scanning calorimetry (DSC) and X‐ray diffraction (XRD) measurements showed the addition of CNFs decreases the degree of crystallinity, but does not impart significant effects on the crystalline structure of the UHMWPE/LDPE blend. Tensile test results showed that the nanocomposite with loading of 3 wt % CNFs had an increase of 38% in tensile strength and 15% in modulus. The thermal stability and thermal conductivity of UHMWPE/LDPE blends were also enhanced by the addition of CNFs. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008 相似文献
997.
Based on the vortex-velocity method,the dimensionless control equations of three-dimensional flow in single screw extruder were developed,and a new simulation method for the flow of non-Newtonian fluids was presented.A staggered grid arrangement was used,in which the dependent variables were located at different mesh points in the computational domain.The discretization scheme was second-order accurate,resulting from the use of central differencing.The simulation concerned the incompressible fluid obeying power law and the application of the finite volume method to the geometrical configuration of channel with aspect ratio up to 13.The distributions of velocities and stresses were investigated for different longitudinal pressure gradients.It was found that the distributions of velocities and stresses agreed well with the result of the two-dimensional approximation over 84% width scope owing to the large aspect ratio of the cross-section of the channel.The output decreased linearly with the increase of the longitudinal pressure gradients as observed in dimensionless forms.In addition,the center of the recirculating region in the channel cross-section drifted upward with the increase of longitudinal pressure gradients,which had positive influence on mixing performance. 相似文献
998.
针对现存滚珠丝杠副综合测试平台普遍存在的安全系数过高和机构设计不尽合理的现象,提出利用ABAQUS软件对测试平台进行轻量化设计。介绍滚珠丝杠副综合测试平台整机结构及特点,指出测试平台存在安全系数过高的现象;利用ABAQUS软件的拓扑优化功能对测试平台进行力学分析,验证了改进后结构的可行性。这为未来对同类型测试平台存在的安全系数过高的现象提供了新的解决方法,具有应用价值。 相似文献
999.
某型号发射装置要求推进剂装药燃速29.0~30.0mm/s(20 ℃,10 MPa)、压强指数≤0.4(20 ℃,4~16 MPa)、装药燃速在贮存期内变化不超过1%(20 ℃,10 MPa).为使装药同时满足燃烧性能指标及燃速变化率的要求,合成了一种双金属盐催化剂,通过合成工艺研究、性能表征及结合装药应用研究,表明加... 相似文献
1000.
热管用于螺杆的传热计算 总被引:2,自引:0,他引:2
建立了热管式螺杆的热模型,计算出了热管式螺杆的总传导率,进而得出了热管式螺杆的传热方程。 相似文献