During the operation of magnetic liquid double suspension bearing(MLDSB),due to rotor resonance,assembly error and other factor,the vibration amplitude of the rotor in resonance state exceeds the original design clear...During the operation of magnetic liquid double suspension bearing(MLDSB),due to rotor resonance,assembly error and other factor,the vibration amplitude of the rotor in resonance state exceeds the original design clearance,resulting in the collision damage between the rotor and the stator,the rotor and the casing.This paper presents a method to simulate the influence of different factors on the dynamic characteristics of 5 degrees of freedom(DOF)rotor based on the dynamic model of MLDSB.Firstly,according to the second Lagrange equation,the dynamic equation of 5 DOF rotor is derived,and the mathematical model is established.Then,based on 5 DOF rotor dynamic equation,the rotor transient dynamic equation under collision state is obtained,and the rotor transient collision dynamic simulation model is established.Finally,the key influencing factors of rotor dynamic characteristics are extracted,and the influence mapping relationship of rotor displacement,axis locus and stress distribution under different factors is simulated by using ANSYS Workbench software.The experimental results show that this method can effectively reflect the influence of various factors on the dynamic characteristics of the rotor.This method can provide theoretical reference for the design and control of MLDSB.展开更多
目的评估维持性血液透析(maintenance hemodialysis,MHD)动静脉内瘘右利手患者的双侧上肢功能,了解动静脉内瘘对上肢功能的影响及内瘘侧上肢功能的影响因素。方法横断面研究,纳入北京市6家血液透析中心的MHD动静脉内瘘且右利手患者,收...目的评估维持性血液透析(maintenance hemodialysis,MHD)动静脉内瘘右利手患者的双侧上肢功能,了解动静脉内瘘对上肢功能的影响及内瘘侧上肢功能的影响因素。方法横断面研究,纳入北京市6家血液透析中心的MHD动静脉内瘘且右利手患者,收集人口学资料、生化资料、握力、关节活动度及简易上肢功能检查(simple test for evaluating hand function,STEF)等上肢功能指标。内瘘侧及非内瘘侧上肢功能的比较采用t检验(或非参数检验),采用多元线性回归分析MHD患者动静脉内瘘侧握力的影响因素。结果共入组MHD患者90例,其中男性51例(56.7%),年龄(59.63±10.60)岁,中位透析龄62.50(24.00,113.00)月。患者非内瘘侧握力高于内瘘侧握力(t=-5.133,P<0.001);多元线性回归结果显示MHD患者内瘘侧握力与血肌酐(β=0.353,P<0.001)、认知功能评分(β=0.223,P=0.006)呈正相关,与尿素清除指数(Kt/V)呈负相关(β=-0.235,P=0.007),男性握力大于女性(β=-0.253,P=0.004)。非内瘘侧腕关节尺偏的角度大于内瘘侧(t=-2.814,P=0.006)。在STEF各项操作中,内瘘侧在大球(t=2.327,P=0.021)、大圆片(t=2.472,P=0.015)、布(t=2.688,P=0.008)项目中操作时间长于无内瘘侧。结论MHD患者内瘘侧握力、关节活动度及灵活性均存在下降,影响内瘘侧握力的因素包括性别、血肌酐、Kt/V和认知功能评分。展开更多
为研究温度变化对天然状态及饱和状态下粉质黏土强度以及变形的影响,以典型季冻区广泛分布的粉质黏土为研究对象,通过全球数字系统(global digital system,GDS)非饱和土三轴测试系统对天然状态下非饱和土以及GDS温控式静/动三轴测试系...为研究温度变化对天然状态及饱和状态下粉质黏土强度以及变形的影响,以典型季冻区广泛分布的粉质黏土为研究对象,通过全球数字系统(global digital system,GDS)非饱和土三轴测试系统对天然状态下非饱和土以及GDS温控式静/动三轴测试系统对饱和粉质黏土,在不同温度条件下进行三轴试验。对试验结果进行研究分析可得:非饱和以及饱和粉质黏土的应力-应变曲线均呈现出应变硬化的特性。非饱和粉质黏土的黏聚力随温度降低表现出不断增加的趋势,而内摩擦角随温度降低逐渐减小,但整体变化趋势较小。饱和土的黏聚力与非饱和土变化趋势相同,随温度的降低其黏聚力逐渐增加,但相同温度时其黏聚力小于非饱和土,其内摩擦角则呈先减小后增加的转变趋势。无竖向压力作用时,相同围压条件下,非饱和与饱和粉质黏土轴向变形量随温度降低而增加,相同温度条件下,两者的轴向变形量随围压的增加会有所减小。试验成果可为季冻区粉质黏土地层工程的设计施工提供理论依据。展开更多
基金Supported by the National Natural Science Foundation of China(No.52075468)。
文摘During the operation of magnetic liquid double suspension bearing(MLDSB),due to rotor resonance,assembly error and other factor,the vibration amplitude of the rotor in resonance state exceeds the original design clearance,resulting in the collision damage between the rotor and the stator,the rotor and the casing.This paper presents a method to simulate the influence of different factors on the dynamic characteristics of 5 degrees of freedom(DOF)rotor based on the dynamic model of MLDSB.Firstly,according to the second Lagrange equation,the dynamic equation of 5 DOF rotor is derived,and the mathematical model is established.Then,based on 5 DOF rotor dynamic equation,the rotor transient dynamic equation under collision state is obtained,and the rotor transient collision dynamic simulation model is established.Finally,the key influencing factors of rotor dynamic characteristics are extracted,and the influence mapping relationship of rotor displacement,axis locus and stress distribution under different factors is simulated by using ANSYS Workbench software.The experimental results show that this method can effectively reflect the influence of various factors on the dynamic characteristics of the rotor.This method can provide theoretical reference for the design and control of MLDSB.
文摘目的评估维持性血液透析(maintenance hemodialysis,MHD)动静脉内瘘右利手患者的双侧上肢功能,了解动静脉内瘘对上肢功能的影响及内瘘侧上肢功能的影响因素。方法横断面研究,纳入北京市6家血液透析中心的MHD动静脉内瘘且右利手患者,收集人口学资料、生化资料、握力、关节活动度及简易上肢功能检查(simple test for evaluating hand function,STEF)等上肢功能指标。内瘘侧及非内瘘侧上肢功能的比较采用t检验(或非参数检验),采用多元线性回归分析MHD患者动静脉内瘘侧握力的影响因素。结果共入组MHD患者90例,其中男性51例(56.7%),年龄(59.63±10.60)岁,中位透析龄62.50(24.00,113.00)月。患者非内瘘侧握力高于内瘘侧握力(t=-5.133,P<0.001);多元线性回归结果显示MHD患者内瘘侧握力与血肌酐(β=0.353,P<0.001)、认知功能评分(β=0.223,P=0.006)呈正相关,与尿素清除指数(Kt/V)呈负相关(β=-0.235,P=0.007),男性握力大于女性(β=-0.253,P=0.004)。非内瘘侧腕关节尺偏的角度大于内瘘侧(t=-2.814,P=0.006)。在STEF各项操作中,内瘘侧在大球(t=2.327,P=0.021)、大圆片(t=2.472,P=0.015)、布(t=2.688,P=0.008)项目中操作时间长于无内瘘侧。结论MHD患者内瘘侧握力、关节活动度及灵活性均存在下降,影响内瘘侧握力的因素包括性别、血肌酐、Kt/V和认知功能评分。
文摘为研究温度变化对天然状态及饱和状态下粉质黏土强度以及变形的影响,以典型季冻区广泛分布的粉质黏土为研究对象,通过全球数字系统(global digital system,GDS)非饱和土三轴测试系统对天然状态下非饱和土以及GDS温控式静/动三轴测试系统对饱和粉质黏土,在不同温度条件下进行三轴试验。对试验结果进行研究分析可得:非饱和以及饱和粉质黏土的应力-应变曲线均呈现出应变硬化的特性。非饱和粉质黏土的黏聚力随温度降低表现出不断增加的趋势,而内摩擦角随温度降低逐渐减小,但整体变化趋势较小。饱和土的黏聚力与非饱和土变化趋势相同,随温度的降低其黏聚力逐渐增加,但相同温度时其黏聚力小于非饱和土,其内摩擦角则呈先减小后增加的转变趋势。无竖向压力作用时,相同围压条件下,非饱和与饱和粉质黏土轴向变形量随温度降低而增加,相同温度条件下,两者的轴向变形量随围压的增加会有所减小。试验成果可为季冻区粉质黏土地层工程的设计施工提供理论依据。
