scholarly journals Influence of High-speed Elevator Operation Parameters on Longitudinal Vibration of Time-varying Hoisting System

2018 ◽  
Author(s):  
Shuohua Zhang ◽  
Ruijun Zhang ◽  
Shunxin Cao ◽  
Qing Zhang
Keyword(s):  
High Speed ◽  
Longitudinal Vibration ◽  
Time Varying ◽  
Operation Parameters ◽  
Hoisting System

scholarly journals Time-Varying Characteristics of the Longitudinal Vibration of a High-Speed Traction Elevator Lifting System

2020 ◽  
Vol 25 (2) ◽  
pp. 153-161
Author(s):  
Qing Zhang ◽  
Tao Hou ◽  
Rui-Jun Zhang ◽  
Jie Liu
Keyword(s):  
High Speed ◽  
Longitudinal Vibration ◽  
Tensile Force ◽  
Time Varying ◽  
Precise Integration ◽  
Operation Process ◽  
Quintic Polynomial ◽  
Hoisting System ◽  
The Galerkin Method ◽  
Lifting System

Hoisting rope in a high-speed traction elevator lifting system exhibits strong time-varying characteristics, which, to a large extent, affect the comfort and safety of high-speed elevators. In order to analyse the influence of the time-varying characteristics on the vibration of elevators during the whole operation process, the longitudinal vibration of the hoisting rope of a lifting elevator is introduced to study the effect of the time varying characteristics of a lifting system on the time-varying characteristics of longitudinal vibration. The nonlinear time-varying model of the longitudinal vibration of the hoisting rope is established using the Hamilton principle and energy method. The Galerkin method is used to discretize the partial differential equations of vibration. The quintic polynomial is used to fit the ideal operating state of the elevator. Following this, the quintic polynomial is input as the motion parameter. The precise integration for the time-varying model of longitudinal vibration of the lift system is put forward. The time variant of elevator hoisting system is solved and vibration analysis is carried out with elevator case. It is observed that, during operation, as the length of the hoist rope increases, the acceleration of the longitudinal vibration of the elevator increases too. As the tensile force, provided by the tensioning device, increases, the acceleration decreases.

Dynamic analysis of high-speed traction elevator and traction car–rope time-varying system

2019 ◽  
Vol 50 (2) ◽  
pp. 37-45 ◽  
Author(s):  
Qing Zhang ◽  
Yu-hu Yang ◽  
Tao Hou ◽  
Rui-jun Zhang
Keyword(s):  
Dynamic Model ◽  
High Speed ◽  
Longitudinal Vibration ◽  
Variable Mass ◽  
Traction Force ◽  
Vertical Vibration ◽  
Time Varying ◽  
Quintic Polynomial ◽  
Input Motion ◽  
Rope System

In this study, the compensating ropes and tension device on elevator vibration, as well as the car and hoisting ropes between the top of the car and traction wheel in a high-speed traction elevator lift system, were considered a system to analyze the effect of traction force. In addition, the vertical vibration of the system was used as the research object. The influence of hoisting ropes quality was measured, and a time-varying dynamic model with variable mass, damping, and stiffness for the car–hoisting rope system was constructed from the perspective of time-varying structural mechanics. Simultaneously, the ideal running state of the elevator, which is fitted by using the quintic polynomial, was utilized as input motion parameter. Then, a case study was conducted by using the fine integral method for the vertical vibration dynamic model of the car–hoisting rope system. Finally, the nonlinear vertical vibration response of the car–hoisting rope system during the operation of high-speed traction elevator was obtained. Results indicated that the influence of traction force, compensating ropes, and tension device on the vibration of the car–hoisting rope system when the elevator is in the upward process is greater than when the elevator is in the downward process. In addition, the low quality of the elevator car leads to the production of strong longitudinal vibration. The linear density of the hoisting ropes has a slight effect on the longitudinal vibration of elevator.

scholarly journals Analysis of longitudinal vibration acceleration based on continuous time-varying model of high-speed elevator lifting system with random parameters

2021 ◽  
Vol 22 ◽  
pp. 28
Author(s):  
Qing Zhang ◽  
Tao Hou ◽  
Hao Jing ◽  
Ruijun Zhang
Keyword(s):  
High Speed ◽  
Integration Method ◽  
Longitudinal Vibration ◽  
Time Varying ◽  
Random Parameters ◽  
Acceleration Response ◽  
Precise Integration ◽  
Response Expression ◽  
Lifting System ◽  
Random Part

In this paper, for studying the influence of the randomness of structural parameters of high-speed elevator lifting system (HELS) caused by manufacturing error and installation error, a continuous time-varying model of HELS was constructed, considering the compensation rope mass and the tension of the tensioning system. The Galerkin weighted residual method is employed to transform the partial differential equation with infinite degrees of freedom (DOF) into the ordinary differential equation. The five-order polynomial is used to fit the actual operation state curve of elevator, and input as operation parameters. The precise integration method of time-varying model of HELS is proposed. The determination part and the random part response expression of the longitudinal dynamic response of HELS are derived by the random perturbation method. Using the precise integration method, the sensitivity of random parameters is determined by solving the random part response expression of time-varying model of HELS, and the digital characteristics of the acceleration response are analyzed. It is found that the line density of the hoisting wire rope has the maximum sensitivity on longitudinal vibration velocity response, displacement response and acceleration response, and the sensitivity of the elastic modulus of the wire rope is smallest.

Modeling of Rope Longitudinal Vibration on Flexible Hoisting System with Time-Varying Length

2011 ◽  
Vol 130-134 ◽  
pp. 2783-2788
Author(s):  
Ji Hu Bao ◽  
Peng Zhang ◽  
Chang Ming Zhu
Keyword(s):  
Mutual Influence ◽  
Longitudinal Vibration ◽  
Rigid Motion ◽  
Time Varying ◽  
Governing Equations ◽  
Modeling Methods ◽  
Varying Length ◽  
The Mean ◽  
Hoisting System ◽  
Mean Time

Aimed at the longitudinal vibration of rope hoisting system with time-varying length, the governing equations are developed employing the Hamilton’s principle considering mutual influence of the rigid motion and deformation of rope. The Galerkin’s method is used to discretize the governing equations. In the mean time, The motions of elevator hoisting system were illustrated to evaluate the proposed mathematical models. The results of simulation show that the modeling methods can represent the longitudinal vibration of rope hoisting system with time-varying length in the paper. The governing equations derived can provide guidelines for further study on flexible hoisting system.

scholarly journals The Impact of Participation in PPP Projects on Total Factor Productivity of Listed Companies in China

2021 ◽  
Vol 13 (14) ◽  
pp. 7603
Author(s):  
Xiangdong Liu ◽  
Guangxi Cao
Keyword(s):  
Total Factor Productivity ◽  
High Speed ◽  
Operation Mode ◽  
Listed Companies ◽  
Financing Constraints ◽  
Eastern Region ◽  
Time Varying ◽  
Factor Productivity ◽  
The Impact ◽  
China’S Economy

The key to transforming China’s economy from high-speed growth to high-quality development is to improve total factor productivity (TFP). Based on the panel data of China’s listed companies participating in PPP (Public–Private Partnerships) projects from 2010 to 2019, this paper constructs the time-varying DID method to test the impact of participation in PPP projects on the company’s TFP empirically, explore the mechanism of the effect of participation in PPP projects on the company’s TFP, and then conduct heterogeneous analysis from four perspectives: region, industry, ownership form, and operation mode. The empirical results show that participation in PPP projects can significantly promote the growth of the company’s TFP, which mainly comes from the promotion of the innovation level of listed companies and the alleviation of financing constraints by participating in PPP projects. In addition, participation in PPP projects has a significant impact on TFP of listed companies in the eastern region, listed companies in the secondary and tertiary industries, state-owned listed companies, and listed companies participating in PPP projects under the BOT mode.

scholarly journals Does the Opening of High-Speed Railway Lines Reduce the Carbon Intensity of China’s Resource-Based Cities?

Energies ◽  
2021 ◽  
Vol 14 (15) ◽  
pp. 4648
Author(s):  
Zhipeng Tang ◽  
Ziao Mei ◽  
Jialing Zou
Keyword(s):  
High Speed ◽  
National Average ◽  
Carbon Intensity ◽  
Time Varying ◽  
Low Carbon ◽  
High Speed Railway ◽  
Different Types ◽  
Endogenous Selection ◽  
Mode Of Development ◽  
The Impact

The carbon intensity of China’s resource-based cities (RBCs) is much higher than the national average due to their relatively intensive mode of development. Low carbon transformation of RBCs is an important way to achieve the goal of reaching the carbon emissions peak in 2030. Based on the panel data from 116 RBCs in China from 2003 to 2018, this study takes the opening of high-speed railway (HSR) lines as a quasi-experiment, using a time-varying difference-in-difference (DID) model to empirically evaluate the impact of an HSR line on reducing the carbon intensity of RBCs. The results show that the opening of an HSR line can reduce the carbon intensity of RBCs, and this was still true after considering the possibility of problems with endogenous selection bias and after applying the relevant robustness tests. The opening of an HSR line is found to have a significant reducing effect on the carbon intensity of different types of RBC, and the decline in the carbon intensity of coal-based cities is found to be the greatest. Promoting migration of RBCs with HSR lines is found to be an effective intermediary way of reducing their carbon intensity.

Behavior of Unsteady Turbulent Starting Round Jets

2012 ◽  
Vol 134 (6) ◽  
Author(s):  
Neerav Abani ◽  
Jaal B. Ghandhi
Keyword(s):  
High Speed ◽  
Penetration Rate ◽  
Injection Rate ◽  
Injection Velocity ◽  
Time Varying ◽  
Velocity Change ◽  
Rate Of Penetration ◽  
Round Jets ◽  
The Difference ◽  
Sudden Decrease

Turbulent starting jets with time-varying injection velocities were investigated using high-speed schlieren imaging. Two solenoid-controlled injectors fed a common plenum upstream of an orifice; using different upstream pressures and actuation times, injection-rate profiles with a step increase or decrease in injection velocity were tested. The behavior of the jet was found to be different depending on the direction of the injection-velocity change. A step increase in injection velocity resulted in an increased rate of penetration relative to the steady-injection case, and a larger increase in injection velocity resulted in an earlier change in the tip-penetration rate. The step-increase data were found to be collapsed by scaling the time by a convective time scale based on the tip location at the time of the injection-velocity change and the difference in the injection velocities. A sudden decrease in injection velocity to zero was found to cause a deviation from the corresponding steady-pressure case at a time that was independent of the initial jet velocity, i.e., it was independent of the magnitude of the injection-velocity change. Two models for unsteady injection from the literature were tested and some deficiencies in the models were identified.

An improved model on forecasting temperature rise of high-speed angular contact ball bearings considering structural constraints

2018 ◽  
Vol 70 (1) ◽  
pp. 15-22 ◽  
Author(s):  
De-xing Zheng ◽  
Weifang Chen ◽  
Miaomiao Li
Keyword(s):  
Heat Generation ◽  
Temperature Rise ◽  
High Speed ◽  
Structural Constraints ◽  
Ball Bearings ◽  
Content Type ◽  
Grid Model ◽  
Simulation Results ◽  
Operation Parameters ◽  
Improved Model

Purpose Thermal performances are key factors impacting the operation of angular contact ball bearings. Heat generation and transfer about angular contact ball bearings, however, have not been addressed thoroughly. So far, most researchers only considered the convection effect between bearing housings and air, whereas the cooling/lubrication operation parameters and configuration effect were not taken into account when analyzing the thermal behaviors of bearings. This paper aims to analyze the structural constraints of high-speed spindle, structural features of bearing, heat conduction and convection to study the heat generation and transfer of high-speed angular contact ball bearings. Design/methodology/approach Based on the generalized Ohm’s law, the thermal grid model of angular contact ball bearing of high-speed spindle was first established. Next Gauss–Seidel method was used to solve the equations group by Matlab, and the nodes temperature was calculated. Finally, the bearing temperature rise was tested, and the comparative analysis was made with the simulation results. Findings The results indicate that the simulation results of bearing temperature rise for the proposed model are in better agreement with the test values. So, the thermal grid model established is verified. Originality/value This paper shows an improved model on forecasting temperature rise of high-speed angular contact ball bearings. In modeling, the cooling/lubrication operation parameters and structural constraints are integrated. As a result, the bearing temperature variation can be forecasted more accurately, which may be beneficial to improve bearing operating accuracy and bearing service life.

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