Deformation and defects in hydroforming of Y-shaped tubes

Hydroforming process of a Y-shaped stainless steel tube was investigated through numerical simulation and experiments. The forming process and reasons of typical defects were analyzed with three different loading paths. Thickness distribution of formed Y-shaped tube was obtained. It is shown by numerical and experimental results that the transition regions are depressed in the forming condition of low inner pressure and wrinkles occur, while fracture occurs in the forming condition of high inner pressure. After forming, the thickness in left transition fillet region is the largest, that in fight transition fillet region is thinner, and the thinnest thickness is at the top of the protrusion. The original thickness line is below the top of the protrusion. The thinning area occurs above this line, while the thickening area is below this line. The maximum thinning rate is significantly increased as the calibration pressure increases, while the maximum thickening rate remains almost unchanged.

灭菌注射用水联合“Y”型双管路泵入法在老年重症脑卒中患者肠内营养中的应用

灭菌注射用水联合“Y”型双管路泵入法在老年重症脑卒中患者肠内营养中的应用效果 方法 本次实验研究将2022年7月-2023年5月本院神经内科专科ICU收治需肠内营养的80例老年重症脑卒中患者作为研究对象,根据其肠内营养泵入方法不同分为2组,其中接受灭菌注射用水联合“Y”型双管路泵入法的老年重症脑卒中肠内营养患者40例作为研究组,接受常规肠内营养泵入法的老年重症脑卒中患者40例作为对照组,对吸入性肺炎、胃潴留及腹泻的发生率进行分析。结果 研究组与对照组相比,吸入性肺炎、肠梗阻、胃潴留及腹泻的发生率均有统计学意义(P<0.05)。结论 探讨灭菌注射用水联合“Y”形双管路泵入法对改善老年重症脑卒中患者的营养状况和改善病人的预后作用。

双离心压气机共用单一进气歧管致进口流场畸变的仿真分析

针对V型发动机的共用单一管路对置离心压气机进口流场畸变特性进行了研究,通过台架试验测试了初始压气机性能,完成了仿真模型的标定。在此基础上分析了压气机进口流场的变化特征,分析结果表明:共用单一管路对压气机特性影响明显,造成了两侧压气机堵塞流量的降低,在大流量工况区域效率明显下降,右侧压气机恶化程度要明显高于左侧。原因在于受安装位置空间限制,喉口处畸变扩展与进口周向畸变叠加效应使得右侧压气机在周向和叶高方向的畸变程度均高于左侧压气机。进口的畸变效应会一直持续至压气机叶轮内部,使压气机性能变差。

薄煤层泵送矸石充填开采技术研究及应用

针对北宿煤矿薄煤层,岩巷、半煤岩巷道掘进量大及建筑物下压煤问题突出的实际情况,决定利用矸石输送泵输送矸石充填采空区,实验确定了矸石充填料及配合比,设计了充填系统和工艺,研制了薄煤层两柱支撑式充填挡矸支架及管路出口"Y"型双向闸板阀,并对沿空留巷巷旁挡墙进行了设计,2011 年 10 月 30 日,在 C1661 工作面通过工业性试验,取得圆满成功,实现了绿色开采,有利于可持续发展。