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.

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 Responses of Supercavitating Vehicles under Non-Stationary Random Excitation

2012 ◽  
Vol 591-593 ◽  
pp. 1934-1937
Author(s):  
Xiang Hua Song ◽  
Guang Ping Zou ◽  
Wei Guang An
Keyword(s):  
High Speed ◽  
Integration Method ◽  
Random Excitation ◽  
State Equation ◽  
Dynamic Responses ◽  
State Equations ◽  
Precise Integration ◽  
Supercavitating Vehicles ◽  
Structural Responses ◽  
First Moment

When the front end of the supercavitating vehicles subjects to very large axial non-stationary random excitation at high speed motion under water, it is necessary to analyze dynamic responses of supercavitating vehicles under non-stationary random excitation. The dynamical equation of supercavitating vehicles is transformed into the form of state equations. The Simpson integration method is going to calculate the integral term of the general solution of state equation to improve the precise integration method. The explicit expression of dynamic responses of supercavitating vehicles is deduced, the means and variances of structural responses are calculated with operation laws of the first moment and second moment. Under different sailing speeds and different cone-cavitator angles dynamic responses of supercavitating vehicles are given by the examples, and the effectiveness of the method was demonstrated.

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 Transverse Vibration Acceleration of a High-Speed Elevator with Random Parameters under Random Excitation

2017 ◽  
Vol 61 (3) ◽  
pp. 153 ◽  
Author(s):  
Qing Zhang ◽  
Yuhu Yang
Keyword(s):  
Standard Deviation ◽  
Covariance Matrix ◽  
High Speed ◽  
Random Excitation ◽  
System Response ◽  
Random Parameters ◽  
The Time Domain ◽  
Pseudo Excitation ◽  
Random Part ◽  
Influence Degree

The randomness of a high-speed elevator car system’s parameters was caused by manufacturing and installation error. In order to more accurately evaluate the dynamic behavior of the elevator car, the compound vibration problems containing both random excitation and random parameters were studied. The deterministic part and random part of the acceleration response were derived by the perturbation theory, and the vibration image in the time domain and frequency domain were analyzed. The sensitivity expressions of each parameter to the system response were established in the random vibration system. The acceleration standard deviation due to random excitation was calculated by the pseudo excitation method. The acceleration standard deviation due to the random parameters was obtained according to the displacement response covariance matrix and random parameters covariance matrix. The discrete degree of random excitation and random parameters on the transverse acceleration of the car was analyzed in an example, and the influence degree of each parameter on acceleration responses was quantitatively described by calculating the response sensitivity of random parameters. This paper provides an effective method for the analysis of the vibration characteristics of the high speed elevator car system.

Modeling and Computation for the High-Speed Rotating Flexible Structure

2008 ◽  
Vol 130 (4) ◽  
Author(s):  
Yong-an Huang ◽  
Zhou-ping Yin ◽  
You-lun Xiong
Keyword(s):  
High Speed ◽  
Integration Method ◽  
Order Approximation ◽  
Computational Method ◽  
Flexible Structure ◽  
Computational Stability ◽  
Precise Integration ◽  
Precise Integration Method ◽  
Piezoelectric Layers ◽  
First Order Approximation

This paper is presented to improve the modeling accuracy and the computational stability for a high-speed rotating flexible structure. The differential governing equations are derived based on the first-order approximation coupling (FOAC) model theory in the framework of the generalized Hamiltonian principle. The semi-discrete model is obtained by the finite element method, and a new shape function based on FOAC is established for the piezoelectric layers. To increase the efficiency, accuracy, and stability of computation, first, the second-order half-implicit symplectic Runge–Kutta method is presented to keep the computational stability of the numerical simulation in a long period of time. Then, the idea of a precise integration method is introduced into the symplectic geometric algorithm. An improved symplectic precise integration method is developed to increase accuracy and efficiency. Several numerical examples are adopted to show the promise of the modeling and the computational method.

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.

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