Increase of elevator speed brings about amplified vibrations of high-speed elevator. In order to reduce the horizontal vibrations of high-speed elevator, a new type of hydraulic active guide roller system based on fuz...Increase of elevator speed brings about amplified vibrations of high-speed elevator. In order to reduce the horizontal vibrations of high-speed elevator, a new type of hydraulic active guide roller system based on fuzzy logic controller is developed. First the working principle of the hydraulic guide system is introduced, then the dynamic model of the horizontal vibrations for elevator cage with active guide roller system and the mathematical model of the hydraulic system are given. A fuzzy logic controller for the hydraulic system is designed to control the hydraulic actuator. To improve the control performance, preview compensation for the controller is provided. Finally, simulation and experiments are executed to verify the hydraulic active guide roller system and the control strategy. Both the simulation and experimental results indicate that the hydraulic active guide roller system can reduce the horizontal vibrations of the elevator effectively and has better effects than the passive one, and the fuzzy logic controller with preview compensation can give superior control performance.展开更多
An inside-cushion structure with sidestep and taper-shaped plungers is studied to address the problems of high impact and vibration in high-speed hydraulic cylinders.First,the three stages of cushion processes are dis...An inside-cushion structure with sidestep and taper-shaped plungers is studied to address the problems of high impact and vibration in high-speed hydraulic cylinders.First,the three stages of cushion processes are discussed according to the varying flow area as the piston moves.Then,to establish a precise mathematical model,the states of the flow field are estimated in terms of the Reynolds number.Accordingly,the simulation model parameterized against measured data is developed and verified by experiment.Last,the average velocity,peak cushion pressure,and terminal velocity are defined to evaluate cushion performance.According to these optimized objectives,the non-linear programming by quadratic Lagrange(NLPQL)algorithm is applied to optimize the structure parameters.The optimization results indicate that the peak cushion pressure is reduced by 28%and terminal velocity is reduced by 21%without reduction of average velocity.展开更多
In this study, the mean droplet diameter in the cavity zone and the total mass transfer area of a multi-stage highspeed disperser(HSD) reactor with different packing combinations were measured and evaluated. The effec...In this study, the mean droplet diameter in the cavity zone and the total mass transfer area of a multi-stage highspeed disperser(HSD) reactor with different packing combinations were measured and evaluated. The effects of rotational speed and packing radius, as well as the packing ring radius and numbers, on the mean droplet diameter and the total mass transfer area were evaluated. A model was established to calculate the mass transfer area in the cavity zone in the HSD reactor, and it was found that the packings contribute 61%–82% of the total mass transfer area. A correlation for predicting the mass transfer area in the packing zone was regressed by the dimensionless analysis method. An enhancement factor based on the mass transfer area in the packing zone was proposed to evaluate the effect of packing combination on mass transfer area. Two optimum packing combinations were proposed in consideration of the mean droplet diameter and the enhancement factor.展开更多
The aerodynamic braking is a clean and non-adhesion braking, and can be used to provide extra braking force during high-speed emergency braking. The research of aerodynamic braking has attracted more and more attentio...The aerodynamic braking is a clean and non-adhesion braking, and can be used to provide extra braking force during high-speed emergency braking. The research of aerodynamic braking has attracted more and more attentions in recent years. However, most researchers in this field focus on aerodynamic effects and seldom on issues of position control of the aerodynamic braking board. The purpose of this paper is to explore position control optimization of the braking board in an aerodynamic braking prototype. The mathematical models of the hydraulic drive unit in the aerodynamic braking system are analyzed in detail, and the simulation models are established. Three control functions--constant, linear, and quadratic--are explored. Two kinds of criteria, including the position steady-state error and the acceleration of the piston rod, are used to evaluate system performance. Simulation results show that the position steady state-error is reduced from around 12-2 mm by applying a linear instead of a constant function, while the acceleration is reduced from 25,71-3.70 m/s2 with a quadratic control function. Use of the quadratic control function is shown to improve system performance. Experimental results obtained by measuring the position response of the piston rod on a test-bench also suggest a reduced position error and smooth movement of the piston rod. This implies that the acceleration is smaller when using the quadratic function, thus verifying the effectiveness of control schemes to improve to system performance. This paper proposes an effective and easily implemented control scheme that improves the position response of hydraulic cylinders during position control.展开更多
With the widespread application of the computer and microelectronic technology in the industry,digitization becomes the inevitable developing trend of the hydraulic technology.Digitization of the hydraulic components ...With the widespread application of the computer and microelectronic technology in the industry,digitization becomes the inevitable developing trend of the hydraulic technology.Digitization of the hydraulic components is critical in the digital hydraulic technology.High-speed on-of valves(HSVs)which convert a train of input pulses into the fast and accurate switching between the on and of states belong to widely used basic digital hydraulic elements.In some ways,the characteristics of the HSVs determine the performance of the digital hydraulic systems.This paper discusses the development of HSVs and their applications.First,the HSVs with innovative structures which is classifed into direct drive valves and pilot operated valves are discussed,with the emphasis on their performance.Then,an overview of HSVs with intelligent materials is presented with considering of the switching frequency and fow capacity.Finally,the applications of the HSVs are reviewed,including digital hydraulic components with the integration of the HSVs and digital hydraulic systems controlled by the HSVs.展开更多
Correlations will be presented to describe liquid hold up, loading and flooding capacity, volumetric mass transfer coefficients on liquid and gas or vapour phase and the pressure drop as a basis for computing packed c...Correlations will be presented to describe liquid hold up, loading and flooding capacity, volumetric mass transfer coefficients on liquid and gas or vapour phase and the pressure drop as a basis for computing packed columns, dumped and regular as well, including the influence of end effects on scaling. The relationships are found on a sound physical and mathematical basis and their validity were confirmed by experimental investigations of many packings; some of them were selected to be considered in this work.展开更多
针对高压压裂泵现场施工中由于铜套裂纹引起液力端盘根密封总成快速失效的现象,提出了优化铜套开口角度α和底部圆角R,进行基于有限疲劳寿命的压裂泵盘根铜套优化设计方法。首先,通过现场施工中的4.5 in(1 in=2.54 cm)V形铜套损坏情况,...针对高压压裂泵现场施工中由于铜套裂纹引起液力端盘根密封总成快速失效的现象,提出了优化铜套开口角度α和底部圆角R,进行基于有限疲劳寿命的压裂泵盘根铜套优化设计方法。首先,通过现场施工中的4.5 in(1 in=2.54 cm)V形铜套损坏情况,估算了现有V形铜套的疲劳寿命为2830000次;然后,使用SolidWorks Simulation建立了4.5 in V形铜套的静力学有限元模型,反推确定了吸入缸压强传递系数为0.3,对4.5 in V形铜套进行了疲劳分析,计算了疲劳寿命为2797000次;最后,计算了4.5,4,3.75,3.25和5 in V形铜套在不同开口角度和圆角的疲劳寿命。结果表明:优化设计后的4 in V形铜套在开口角度改为120°后疲劳寿命增大了81.5倍,现场测试满足在液缸最大生命周期内不再产生疲劳裂纹;通过现场施工数据反推传递系数,验证疲劳寿命计算方法的有效性,优化设计了5种压力等级下铜套的开口角度和圆角。同时,为其他型号盘根铜套优化设计提供了参考方法。展开更多
文摘Increase of elevator speed brings about amplified vibrations of high-speed elevator. In order to reduce the horizontal vibrations of high-speed elevator, a new type of hydraulic active guide roller system based on fuzzy logic controller is developed. First the working principle of the hydraulic guide system is introduced, then the dynamic model of the horizontal vibrations for elevator cage with active guide roller system and the mathematical model of the hydraulic system are given. A fuzzy logic controller for the hydraulic system is designed to control the hydraulic actuator. To improve the control performance, preview compensation for the controller is provided. Finally, simulation and experiments are executed to verify the hydraulic active guide roller system and the control strategy. Both the simulation and experimental results indicate that the hydraulic active guide roller system can reduce the horizontal vibrations of the elevator effectively and has better effects than the passive one, and the fuzzy logic controller with preview compensation can give superior control performance.
基金National Natural Science Foundation of China(51705152)Jiangxi Provincial Natural Science Foundation(20161BAB206150+2 种基金20161BAB216133)Jiangxi Provincial Key R&D Program(20171BBG70040)Innovation Fund Designated for Graduate Students of Jiangxi Province(YC2018-S246)。
文摘An inside-cushion structure with sidestep and taper-shaped plungers is studied to address the problems of high impact and vibration in high-speed hydraulic cylinders.First,the three stages of cushion processes are discussed according to the varying flow area as the piston moves.Then,to establish a precise mathematical model,the states of the flow field are estimated in terms of the Reynolds number.Accordingly,the simulation model parameterized against measured data is developed and verified by experiment.Last,the average velocity,peak cushion pressure,and terminal velocity are defined to evaluate cushion performance.According to these optimized objectives,the non-linear programming by quadratic Lagrange(NLPQL)algorithm is applied to optimize the structure parameters.The optimization results indicate that the peak cushion pressure is reduced by 28%and terminal velocity is reduced by 21%without reduction of average velocity.
基金Supported by the National Natural Science Foundation of China(21676007,21506005)
文摘In this study, the mean droplet diameter in the cavity zone and the total mass transfer area of a multi-stage highspeed disperser(HSD) reactor with different packing combinations were measured and evaluated. The effects of rotational speed and packing radius, as well as the packing ring radius and numbers, on the mean droplet diameter and the total mass transfer area were evaluated. A model was established to calculate the mass transfer area in the cavity zone in the HSD reactor, and it was found that the packings contribute 61%–82% of the total mass transfer area. A correlation for predicting the mass transfer area in the packing zone was regressed by the dimensionless analysis method. An enhancement factor based on the mass transfer area in the packing zone was proposed to evaluate the effect of packing combination on mass transfer area. Two optimum packing combinations were proposed in consideration of the mean droplet diameter and the enhancement factor.
基金supported by National Natural Science Foundation of China(Grant No.61004077)Fundamental Research Funds for the Central Universities of China(Grant No.2860219022)Foundation of Traction Power State Key Laboratory of Southwest Jiaotong University,China(Grant No.TPL1308)
文摘The aerodynamic braking is a clean and non-adhesion braking, and can be used to provide extra braking force during high-speed emergency braking. The research of aerodynamic braking has attracted more and more attentions in recent years. However, most researchers in this field focus on aerodynamic effects and seldom on issues of position control of the aerodynamic braking board. The purpose of this paper is to explore position control optimization of the braking board in an aerodynamic braking prototype. The mathematical models of the hydraulic drive unit in the aerodynamic braking system are analyzed in detail, and the simulation models are established. Three control functions--constant, linear, and quadratic--are explored. Two kinds of criteria, including the position steady-state error and the acceleration of the piston rod, are used to evaluate system performance. Simulation results show that the position steady state-error is reduced from around 12-2 mm by applying a linear instead of a constant function, while the acceleration is reduced from 25,71-3.70 m/s2 with a quadratic control function. Use of the quadratic control function is shown to improve system performance. Experimental results obtained by measuring the position response of the piston rod on a test-bench also suggest a reduced position error and smooth movement of the piston rod. This implies that the acceleration is smaller when using the quadratic function, thus verifying the effectiveness of control schemes to improve to system performance. This paper proposes an effective and easily implemented control scheme that improves the position response of hydraulic cylinders during position control.
基金Supported by Key Technologies Research and Development Program of China(Grant No.2019YFB2004502)National Natural Science Foundation of China(Grant Nos.51805350,51775362)Postdoctoral Science Foundation of China(Grant No.2019M651073).
文摘With the widespread application of the computer and microelectronic technology in the industry,digitization becomes the inevitable developing trend of the hydraulic technology.Digitization of the hydraulic components is critical in the digital hydraulic technology.High-speed on-of valves(HSVs)which convert a train of input pulses into the fast and accurate switching between the on and of states belong to widely used basic digital hydraulic elements.In some ways,the characteristics of the HSVs determine the performance of the digital hydraulic systems.This paper discusses the development of HSVs and their applications.First,the HSVs with innovative structures which is classifed into direct drive valves and pilot operated valves are discussed,with the emphasis on their performance.Then,an overview of HSVs with intelligent materials is presented with considering of the switching frequency and fow capacity.Finally,the applications of the HSVs are reviewed,including digital hydraulic components with the integration of the HSVs and digital hydraulic systems controlled by the HSVs.
文摘Correlations will be presented to describe liquid hold up, loading and flooding capacity, volumetric mass transfer coefficients on liquid and gas or vapour phase and the pressure drop as a basis for computing packed columns, dumped and regular as well, including the influence of end effects on scaling. The relationships are found on a sound physical and mathematical basis and their validity were confirmed by experimental investigations of many packings; some of them were selected to be considered in this work.
文摘针对高压压裂泵现场施工中由于铜套裂纹引起液力端盘根密封总成快速失效的现象,提出了优化铜套开口角度α和底部圆角R,进行基于有限疲劳寿命的压裂泵盘根铜套优化设计方法。首先,通过现场施工中的4.5 in(1 in=2.54 cm)V形铜套损坏情况,估算了现有V形铜套的疲劳寿命为2830000次;然后,使用SolidWorks Simulation建立了4.5 in V形铜套的静力学有限元模型,反推确定了吸入缸压强传递系数为0.3,对4.5 in V形铜套进行了疲劳分析,计算了疲劳寿命为2797000次;最后,计算了4.5,4,3.75,3.25和5 in V形铜套在不同开口角度和圆角的疲劳寿命。结果表明:优化设计后的4 in V形铜套在开口角度改为120°后疲劳寿命增大了81.5倍,现场测试满足在液缸最大生命周期内不再产生疲劳裂纹;通过现场施工数据反推传递系数,验证疲劳寿命计算方法的有效性,优化设计了5种压力等级下铜套的开口角度和圆角。同时,为其他型号盘根铜套优化设计提供了参考方法。
