LONGITUDINAL DISPERSION IN RWERS: A DEAD-ZONE MODEL SOLUTION

Abstract. An Aggregated Dead Zone (ADZ) model is presented for longitudinal dispersion of tracer in river channels, in which the channel cross-section is divided into two parallel regions: the bulk flow and dead zone storage. Tracer particles in the bulk flow are assumed to obey plug-flow advection at the discharge velocity U without any mixing effects. The dispersive properties of the model are completely embodied in the residence time for tracer storage in the dead zone. The model provides an excellent description and prediction of empirical concentration-time distributions, for times t < x/U. Its physical realism is demonstrated by using it to describe the evolution of a tracer cloud in the River Severn, U.K., and by comparing it with a more complex model which incorporates the additional effects of shear flow dispersion within the bulk flow. The ADZ model is a potentially useful tool for practical prediction of dispersion in natural channels. Keywords: Channels; dispersion; dead zones; tracers; River Severn

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An investigation of fine sediment mixing within free-flowing and surcharged manholes

Water Science & Technology ◽

10.2166/wst.1998.0052 ◽

1998 ◽

Vol 37 (1) ◽

pp. 215-222

Author(s):

I. Guymer ◽

R. O'Brien ◽

O. Mark ◽

P. Dennis

Keyword(s):

Dead Zone ◽

Laser Induced Fluorescence ◽

Fine Sediment ◽

Longitudinal Dispersion ◽

Qualitative Description ◽

Suspended Material ◽

Mixing Processes ◽

Future Developments ◽

Mixing Effects ◽

Sediment Mixing

Previous studies of the effects of manholes on longitudinal dispersion has concentrated on the spreading of solutes. This papers presents new data describing the influence of a surcharged and free-flowing manhole structure on the longitudinal dispersion of a fine suspended material. The effects of benching within the manhole structure are also illustrated. Laser Induced Fluorescence (LIF) techniques have been used to provide a qualitative description of the mixing processes present within a surcharged manhole. Nephelometric results have provided estimates of the parameters required to simulate the mixing effects using either increase in variance or aggregated dead zone techniques. A preliminary attempt at describing these observations using available software is discussed and recommendations for future developments are made.

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Improved Pole-placement Control with Feed-forward Dead Zone Compensation for Position Tracking of Electro-Pneumatic Actuator System Improved Pole-placement Control with Feed-forward Dead Zone Compensation for Position Tracking of Electro-Pneumatic Actuato

ELEKTRIKA- Journal of Electrical Engineering ◽

10.11113/elektrika.v20n2.272 ◽

2021 ◽

Vol 20 (2) ◽

pp. 25-32

Author(s):

Noorhazirah Sunar ◽

Mohd Fua’ad Rahmat ◽

Ahmad ‘Athif Mohd Fauzi ◽

Zool Hilmi Ismail ◽

Siti Marhanis Osman ◽

...

Keyword(s):

Dead Zone ◽

Pneumatic Actuator ◽

Pole Placement ◽

Position Tracking ◽

Zone Model ◽

Feed Forward ◽

The Dead ◽

Chattering Effect ◽

Pole Placement Controller ◽

Pole Placement Control

Dead-zone in the valve degraded the performances of the Electro-Pneumatic Actuator (EPA) system. It makes the system difficult to control, become unstable and leads to chattering effect nearest desired position. In order to cater this issue, the EPA system transfer function and the dead-zone model is identified by MATLAB SI toolbox and the Particle Swarm Optimization (PSO) algorithm respectively. Then a parametric control is designed based on pole-placement approach and combine with feed-forward inverse dead-zone compensation. To reduce chattering effect, a smooth parameter is added to the controller output. The advantages of using these techniques are the chattering effect and the dead-zone of the EPA system is reduced. Moreover, the feed-forward system improves the transient performance. The results are compared with the pole-placement control (1) without compensator and (2) with conventional dead-zone compensator. Based on the experimental results, the proposed controller reduced the chattering effect due to the controller output of conventional dead-zone compensation, 90% of the pole-placement controller steady-state error and 30% and 40% of the pole-placement controller with conventional dead-zone compensation settling time and rise time.

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Low-Complexity Adaptive Saturated Control of a Class of Nonlinear Systems with Its Application

Mathematical Problems in Engineering ◽

10.1155/2019/7135930 ◽

2019 ◽

Vol 2019 ◽

pp. 1-9

Author(s):

Gang Zhang ◽

Deqiang Cheng ◽

Qiqi Kou

Keyword(s):

Nonlinear Systems ◽

Dead Zone ◽

External Disturbance ◽

Original System ◽

Low Complexity ◽

Control Law ◽

Zone Model ◽

Time Varying ◽

Saturated Control ◽

Output Constraint

This paper investigates a low-complexity saturated control law for a class of nonlinear systems with consideration of the time-varying output constraint, control constraint, and external disturbance. First, a dead-zone model is employed to transform the control saturation nonlinearity into a linear one with respect to the real input signal. Then, the original system with time-varying output constraint is transformed into a constraint-free one, based on which a novel adaptive saturated control law is devised along the filtered error manifold. By employing minimum learning parameter technique and virtual error concept, only two adaptive parameters are needed to update online, which reduces the computational burdens dramatically. Finally, the applications to Duffing-Holmes chaotic system are organized to validate the effectiveness of the proposed control law.

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An adaptive robust control scheme for robot manipulators with unknown backlash nonlinearity in gears

Transactions of the Institute of Measurement and Control ◽

10.1177/0142331218810773 ◽

2018 ◽

Vol 41 (10) ◽

pp. 2789-2802 ◽

Cited By ~ 4

Author(s):

Soheil Ahangarian Abhari ◽

Farzad Hashemzadeh ◽

Mahdi Baradarannia ◽

Hamed Kharrati

Keyword(s):

Robust Control ◽

Controller Design ◽

Robot Manipulators ◽

Dead Zone ◽

Main Idea ◽

Adaptive Robust Control ◽

Zone Model ◽

Robot Trajectory ◽

Zone Parameter ◽

The Stability

This paper presents an adaptive robust control algorithm for the nonlinear dynamics of robot manipulators with unknown backlash in gears. The basic nonlinear model of a serial manipulator robot is used for the controller design, and this is combined with the nonlinear proposed dead zone model, based on the input and output torque. The main idea of providing this model is to achieve a dynamic model of the system considering the backlash of the robot joint gears, and having less complexity such that the developed controller does not need the inverse backlash model. The adaptive robust controller is developed, without using the inverse backlash model. The proposed controller is designed based on an unknown dead zone parameter and it guarantees the stability and path tracking of the robot trajectory with unknown dead zone parameter in the desired range. Numerical simulations are conducted to show the effectiveness of the proposed controller. Finally, the efficiency and capability of the proposed controller in dealing with the unknown backlash nonlinearities in gears of the manipulator are demonstrated by experimental results with a five-bar manipulator.

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