scholarly journals Vibration Analysis and Control of a Vibration Screed System for Asphalt Pavers

2020 ◽  
Vol 25 (3) ◽  
pp. 363-372
Author(s):  
Vanliem Nguyen ◽  
Zhenpeng Wu ◽  
Beiping Zhang ◽  
Zhang Jian Run
Keyword(s):  
Working Conditions ◽  
Vibration Analysis ◽  
Excitation Frequency ◽  
Mean Square ◽  
Dynamic Parameters ◽  
Objective Functions ◽  
Nonlinear Dynamic Model ◽  
Compression Efficiency ◽  
Centre Of Gravity ◽  
And Control

To reduce shaking of a vibration screed system (VSS) and improve the paving performance of an asphalt paver (AP), the root-mean-square (RMS) acceleration responses at points on the front and rear screed floors are analyzed via an experimental method. A 3D nonlinear dynamic model of the VSS is also built to evaluate the influence of the dynamic parameters of the VSS on the compression efficiency, paving quality, and working stability of the AP based on the objective functions of the vertical, pitching, and rolling RMS values at the centre of gravity of the screed. The angular deviations, $alpha$ and $gamma$, of the tamper are then controlled to improve the paving performance. The research results show that the excitation frequency, $f_{t}$, and both angular deviations, $alpha$ and $gamma$, of the tamper strongly affect the paving performance. The compression efficiency is quickly enhanced, while both paving quality and working stability are significantly reduced with increasing the excitation frequency $f_{t}$ and reducing the angular deviations. $alpha$ and $gamma$. and vice versa. Additionally, the screed shaking and paving performance of the AP are remarkably improved by control of the angular deviations, $alpha$ and $gamma$, under different working conditions.

Vibration Analysis and Control of Nuclear Power Crane with MRFD

2018 ◽  
Vol 10 (08) ◽  
pp. 1850093 ◽  
Author(s):  
Yi Xiao Qin ◽  
Bo Lun Li ◽  
Xin Li ◽  
Yan Qing Li ◽  
Zhi De Zhang ◽  
...  
Keyword(s):  
Vibration Control ◽  
Working Conditions ◽  
Control Strategy ◽  
Vibration Analysis ◽  
Nuclear Power ◽  
Control Method ◽  
Control Model ◽  
Fluid Damper ◽  
Magneto Rheological ◽  
And Control

The nuclear power crane is required to have high security and stability, as its lifting mechanism and span structure are needed to perform predominantly in serious working conditions. A new vibration analysis and control method on the nuclear power crane is proposed to improve its stability, which is based on magneto rheological fluid damper (MRFD) and switch algorithm control strategy. The simulation is completed through dynamic model and control model. The experiment is accomplished in a serving crane. Both numerical simulated and experimental results show that the vibration of nuclear power crane is suppressed significantly with MRFD. It is proved that MRFD should be taken into consideration in the vibration control of nuclear power crane.

scholarly journals Development, Modeling and Control of a Dual Tilt-Wing UAV in Vertical Flight

Drones ◽  
2020 ◽  
Vol 4 (4) ◽  
pp. 71
Author(s):  
Luz M. Sanchez-Rivera ◽  
Rogelio Lozano ◽  
Alfredo Arias-Montano
Keyword(s):  
Dynamic Model ◽  
Attitude Control ◽  
Test Bench ◽  
Aerodynamic Coefficients ◽  
Nonlinear Dynamic Model ◽  
Modeling And Control ◽  
Drag And Lift ◽  
And Control ◽  
Dynamics Method ◽  
Indoor And Outdoor

Hybrid Unmanned Aerial Vehicles (H-UAVs) are currently a very interesting field of research in the modern scientific community due to their ability to perform Vertical Take-Off and Landing (VTOL) and Conventional Take-Off and Landing (CTOL). This paper focuses on the Dual Tilt-wing UAV, a vehicle capable of performing both flight modes (VTOL and CTOL). The UAV complete dynamic model is obtained using the Newton–Euler formulation, which includes aerodynamic effects, as the drag and lift forces of the wings, which are a function of airstream generated by the rotors, the cruise speed, tilt-wing angle and angle of attack. The airstream velocity generated by the rotors is studied in a test bench. The projected area on the UAV wing that is affected by the airstream generated by the rotors is specified and 3D aerodynamic analysis is performed for this region. In addition, aerodynamic coefficients of the UAV in VTOL mode are calculated by using Computational Fluid Dynamics method (CFD) and are embedded into the nonlinear dynamic model. To validate the complete dynamic model, PD controllers are adopted for altitude and attitude control of the vehicle in VTOL mode, the controllers are simulated and implemented in the vehicle for indoor and outdoor flight experiments.

Dynamic monitoring feedback iteration control for damping-adjustable semi-active suspension systems

2021 ◽  
pp. 1-9
Author(s):  
Chongchong Li ◽  
Jiangyong Xiong ◽  
Tingshan Liu ◽  
Ziang Zhang
Keyword(s):  
Root Mean Square ◽  
Working Conditions ◽  
Control Algorithm ◽  
Active Suspension ◽  
Dynamic Monitoring ◽  
Iteration Algorithm ◽  
Mean Square ◽  
Control Effect ◽  
Analytic Hierarchy ◽  
Vehicle Simulation

In order to further improve vehicle ride performance, a dynamic monitoring feedback iteration control algorithm is proposed by combining the features of a variable-damping semi-active suspension system and applying them to the system. A seven-degree-of-freedom finished vehicle simulation model is built based on MATLAB/Simulink. The root-mean-square values of the acceleration of the sprung mass, the dynamic travel of the suspension and the dynamic tire load are taken as evaluation indicators of vehicle ride performance. An analytic hierarchy process (AHP) is used to determine the weighting coefficients of the evaluation indicators, and a genetic algorithm is utilized to determine the optimal damping of the suspension under various typical working conditions. Suspension damping is controlled with a dynamic monitoring feedback iteration algorithm. The correction coefficients of the control algorithm are determined according to the deviation between the obtained damping and the optimized damping so that the control parameters will agree with the optimal result under typical working conditions, and the control effect under other working conditions is verified. The simulation results indicate that the proposed dynamic monitoring feedback iteration control algorithm can effectively reduce the root-mean-square value of the acceleration of the sprung mass by 10.56% and the root-mean-square value of the acceleration of the dynamic travel of the suspension by 11.98% under mixed working conditions, thus improving vehicle ride performance. The study in this paper provides a new attempt for damping control of semi-active suspension and lays a theoretical foundation for its application in engineering.

The Effect of Bandwidth of Semiactive Dampers on Vehicle Ride

1993 ◽  
Vol 115 (3) ◽  
pp. 571-575 ◽  
Author(s):  
J. Lieh
Keyword(s):  
Fourier Transform ◽  
Significant Influence ◽  
Switching Time ◽  
Control Valve ◽  
Mean Square ◽  
Active Suspensions ◽  
Car Model ◽  
Frequency Responses ◽  
And Control ◽  
Valve Switching

A passenger car model with a full car body and four wheel-axle assemblies is used to investigate the influence of semiactive suspensions on ride performance. Mean square values are evaluated for various damping levels and control valve switching times. Due to severe nonlinearities, frequency responses are not obtained directly. They are reconstructed from Fast Fourier Transform (FFT) using a Hanning window. The results are compared with those from LQR active suspensions and pure on-off dampers. The effect of control valve switching time (bandwidth) is studied and shows a significant influence on the vehicle ride, suspension travels, and tire deflections.

Development of a Stepped Calibration Approach for XAJ Hydrological Model

2013 ◽  
Vol 405-408 ◽  
pp. 2222-2225
Author(s):  
Qian Li ◽  
Wei Min Bao ◽  
Jing Lin Qian
Keyword(s):  
Root Mean Square Error ◽  
Objective Function ◽  
Traditional Method ◽  
Hydrological Model ◽  
Model Performance ◽  
Layer By Layer ◽  
Mean Square ◽  
Objective Functions ◽  
Single Objective ◽  
Calibration Approach

This paper discusses the conceptual stepped calibration approach (SCA) which has been developed for the Xinanjiang (XAJ) model. Multi-layer and multi-objective functions which can make optimization work simpler and more effective are introduced in this procedure. In all eight parameters were considered, they were divided into four layers according to the structure of XAJ model, and then calibrated layer by layer. The SCA procedure tends to improve the performance of the traditional method of calibration (thus, using a single objective function, such as root mean square error RMSE). The compared results demonstrate that the SCA yield better model performance than RMSE.

scholarly journals Precarious or Protected? Evaluating Work Quality in the Legal Sex Industry

2016 ◽  
Vol 21 (4) ◽  
pp. 173-187 ◽  
Author(s):  
Alice Orchiston
Keyword(s):  
Sex Work ◽  
Working Conditions ◽  
Sex Workers ◽  
Sex Industry ◽  
Labour Law ◽  
Industry Regulation ◽  
Regulatory Model ◽  
And Control ◽  
The Relationship ◽  
Legal Sex

Decriminalising (or legalising) sex work is argued to improve sex workers’ safety and provide access to labour rights. However, there is a paucity of empirical research comparing how different regulatory approaches affect working conditions in the sex industry, especially in relation to venues that are managed by third parties. This article uses a mixed methods study of the Australian legal brothel sector to critically explore the relationship between external regulation and working conditions. Two dominant models of sex industry regulation are compared: decriminalisation and licensing. First, the article documents workplace practices in the Australian legal brothel sector, examining sex workers’ agency, autonomy and control over the labour process. Second, it analyses the capacity of each regulatory model to protect sex workers from unsafe and unfair working conditions. On the basis of these findings, the article concludes that brothel-based sex work is precarious and substantively excluded from the protective mantle of labour law, notwithstanding its legality. It is argued that the key determinant of conditions in the legal brothel sector is the extent to which the state enforces formal labour protections, as distinct from the underlying regulatory model adopted.

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