An experimental study is performed to investigate the temperature response and distribution in a sector tilted pad thrust bearing during the transient periods such as the load on the bearing changed abruptly.Lots of t...An experimental study is performed to investigate the temperature response and distribution in a sector tilted pad thrust bearing during the transient periods such as the load on the bearing changed abruptly.Lots of thermocouples are placed on different position such as the pad surface,leading and trailing edge as well as the pad block,and then these thermocouples are used to measure the temperature variation during the transient period.The load on one pad and the displacement of the runner are measured with different sensors.The effects of a sudden load change on temperature at different position of the pads are analyzed according to the experimental data.The influence of different initial conditions and the different load increment on temperature variation at the pad surface and pad body are obtained,and temperature responses at leading edge and trailing edge under different conditions are tested.This experimental study shows a significant effect of load increment and initial condition on the temperature distribution of bearing pad interface under sudden load change conditions,and the measurement of real oil film temperature is difficult due to the large thermal inertia of pad surface.展开更多
Aiming at the complex electromagnetic transient process of EMU passing by phase-separation with electric load in high-speed railway, mechanism of overvoltage caused by switching off, overvoltage caused by switching on...Aiming at the complex electromagnetic transient process of EMU passing by phase-separation with electric load in high-speed railway, mechanism of overvoltage caused by switching off, overvoltage caused by switching on and impact current is analyzed systematically in this article. π-type equivalent circuit of feeding section is put forward in the analysis of overvoltage mechanism. Overvoltage and overcurrent model of passing by phase-separation with electric load are also built. Correctness of mechanism was validated by simulation. In addition, the methods to solve the influence on substations, transformers and protection devices in this process are put forward, which provides a new idea on passing by phase-separation with electric load technology.展开更多
文摘An experimental study is performed to investigate the temperature response and distribution in a sector tilted pad thrust bearing during the transient periods such as the load on the bearing changed abruptly.Lots of thermocouples are placed on different position such as the pad surface,leading and trailing edge as well as the pad block,and then these thermocouples are used to measure the temperature variation during the transient period.The load on one pad and the displacement of the runner are measured with different sensors.The effects of a sudden load change on temperature at different position of the pads are analyzed according to the experimental data.The influence of different initial conditions and the different load increment on temperature variation at the pad surface and pad body are obtained,and temperature responses at leading edge and trailing edge under different conditions are tested.This experimental study shows a significant effect of load increment and initial condition on the temperature distribution of bearing pad interface under sudden load change conditions,and the measurement of real oil film temperature is difficult due to the large thermal inertia of pad surface.
文摘Aiming at the complex electromagnetic transient process of EMU passing by phase-separation with electric load in high-speed railway, mechanism of overvoltage caused by switching off, overvoltage caused by switching on and impact current is analyzed systematically in this article. π-type equivalent circuit of feeding section is put forward in the analysis of overvoltage mechanism. Overvoltage and overcurrent model of passing by phase-separation with electric load are also built. Correctness of mechanism was validated by simulation. In addition, the methods to solve the influence on substations, transformers and protection devices in this process are put forward, which provides a new idea on passing by phase-separation with electric load technology.
文摘目的探讨短暂性脑缺血发作(transient ischemic attacks,TIA)患者采用负荷剂量氯吡格雷治疗的临床效果。方法选取2020年6月—2022年6月厦门市第五医院收治的88例TIA患者。以随机数字表法分为研究组(n=44)和对照组(n=44)。2组均接受了血管扩张剂和神经保护药物等治疗,对照组给予常规剂量氯吡格雷治疗,研究组给予负荷剂量氯吡格雷治疗。比较2组临床疗效、神经功能、预后及不良反应。结果研究组的治疗总有效率(95.45%)高于对照组(79.55%)(P<0.05)。2组在治疗1、2周后,美国国立卫生研究院卒中量表(National Institutes of Health stroke scale,NIHSS)评分都有所降低(P<0.05),研究组治疗1、2周后NIHSS评分低于对照组(P<0.05)。2组治疗后改良Rankin量表(modified Rankin scale,mRS)评分降低(P<0.05),研究组评分低于对照组(P<0.05)。研究组不良反应总发生率(6.82%)与对照组(11.36%)比较,差异无统计学意义(P>0.05)。结论TIA患者采用负荷剂量氯吡格雷治疗具有确切的临床疗效,可有效改善神经功能及预后,且不会增加药物不良反应,体现了《短暂性脑缺血发作与轻型卒中抗血小板治疗中国专家共识》的执行标准。
