Dynamic model of crop growth system and numerical simulation of crop growth process under the multi-environment external force action

2003 ◽  
Vol 24 (6) ◽  
pp. 727-737
Author(s):  
Li Zi-zhen ◽  
Wang Wan-xiong ◽  
Xu Cai-lin
Keyword(s):  
Numerical Simulation ◽  
Dynamic Model ◽  
External Force ◽  
Growth Process ◽  
Crop Growth ◽  
Force Action ◽  
Growth System

Options for Transpiration Water Removal in a Crop Growth System Under Zero Gravity Conditions

1991 ◽  
Author(s):  
C. C. Blackwell ◽  
M. Kliss ◽  
B. Yendler ◽  
B. Borchers ◽  
Boris S. Yendler ◽  
...  
Keyword(s):  
Crop Growth ◽  
Water Removal ◽  
Zero Gravity ◽  
Growth System

scholarly journals Hydrodynamic Analysis of Self-Propulsion Performance of Wave-Driven Catamaran

2021 ◽  
Vol 9 (11) ◽  
pp. 1221
Author(s):  
Weixin Zhang ◽  
Ye Li ◽  
Yulei Liao ◽  
Qi Jia ◽  
Kaiwen Pan
Keyword(s):  
Numerical Simulation ◽  
Flow Field ◽  
Dynamic Model ◽  
Dynamic Structure ◽  
Ocean Waves ◽  
Static State ◽  
Small Surface ◽  
Propulsion Performance ◽  
Multi Body ◽  
Body Dynamic

The wave-driven catamaran is a small surface vehicle driven by ocean waves. It consists of a hull and hydrofoils, and has a multi-body dynamic structure. The process of moving from static state to autonomous navigation driven by ocean waves is called “self-propulsion”, and reflects the ability of the wave-driven catamaran to absorb oceanic wave energy. Considering the importance of the design of the wave-driven catamaran, its self-propulsion performance should be comprehensively analysed. However, the wave-driven catamaran’s multi-body dynamic structure, unpredictable dynamic and kinematic responses driven by waves make it difficult to analyse its self-propulsion performance. In this paper, firstly, a multi-body dynamic model is established for wave-driven catamaran. Secondly, a two-phase numerical flow field containing water and air is established. Thirdly, a numerical simulation method for the self-propulsion process of the wave-driven catamaran is proposed by combining the multi-body dynamic model with a numerical flow field. Through numerical simulation, the hydrodynamic response, including the thrust of the hydrofoils, the resistance of the hull and the sailing velocity of the wave-driven catamaran are identified and comprehensively analysed. Lastly, the accuracy of the numerical simulation results is verified through a self-propulsion test in a towing tank. In contrast with previous research, this method combines multi-body dynamics with computational fluid dynamics (CFD) to avoid errors caused by artificially setting the motion mode of the catamaran, and calculates the real velocity of the catamaran.

Dynamic model for population distribution and optimum immigration and job creation policies

2004 ◽  
Vol 31 (2) ◽  
pp. 261
Author(s):  
N. U. Ahmed ◽  
Yongjuan He
Keyword(s):  
Numerical Simulation ◽  
Optimal Control ◽  
Control Theory ◽  
Dynamic Model ◽  
Optimal Control Theory ◽  
Close Agreement ◽  
Population Distribution ◽  
Job Creation ◽  
Population Level ◽  
Decision Control

In this paper we demonstrate that by use of modern Systems and Optimal Control theory, it is possible to formulate optimum immigration and job creation strategies while maintaining population level close to certain pre-specified targets. With this objective in mind, we consider a simplified dynamic model based on a previous model developed in (Ahmed and Rahim, 2001:325-358) to describe the population distribution in Canada. Numerical results demonstrate that the model population is in close agreement with the actual population. This model was then used to formulate a control problem with immigration and job creation rates being the decision (control) variables. Using optimal control theory, optimum immigration and job creation policies were determined. Results are illustrated by numerical simulation and they are found to be very encouraging.

An Adaptive Robust Control for Hard Rock Tunnel Boring Machine Cutterhead Driving System

2015 ◽  
Author(s):  
Chengjun Shao ◽  
Jianfeng Liao ◽  
Xiuliang Li ◽  
Hongye Su
Keyword(s):  
Robust Control ◽  
Dynamic Model ◽  
External Force ◽  
Hard Rock ◽  
Tunnel Boring Machine ◽  
Adaptive Robust Control ◽  
Driving System ◽  
Tunnel Boring ◽  
Rock Tunnel ◽  
Hard Rock Tbm

The cutterhead driving system of tunnel boring machine is one of the key components for rock cutting and excavation. In this paper, a generalized nonlinear time-varying dynamic model is established for the hard rock TBM cutterhead driving system. Parametric uncertainties and nonlinearities and unknown disturbances exist in the dynamic model. An adaptive robust control strategy is proposed to compensate the uncertainties and nonlinearities to achieve precise cutterhead rotation speed control. In order to simulate the comprehensive performances of adaptive robust control controller, three different kinds of external force disturbances are added in this model. Compared to the traditional PID, ARC can effectively handle the different kinds of external force disturbances with sufficient small tracking errors.

scholarly journals Locomotion Control of Snake-Like Robot with Rotational Elastic Actuators Utilizing Observer

2019 ◽  
Vol 9 (19) ◽  
pp. 4012 ◽  
Author(s):  
Shunsuke Nansai ◽  
Takumi Yamato ◽  
Masami Iwase ◽  
Hiroshi Itoh
Keyword(s):  
Numerical Simulation ◽  
Control System ◽  
Dynamic Model ◽  
Ground Surface ◽  
Surface Conditions ◽  
Luenberger Observer ◽  
Key Points ◽  
Switching Dynamic ◽  
Head Control ◽  
Frictional Coefficients

The purpose of this paper is designing a head control system capable of adapting to passive side-slipping. The environments in which snake-like robots are expected to be utilized generally have ground surface conditions with nonuniform frictional coefficients. In such conditions, the passive wheels of the snake-like robot have a chance of side-slipping. To locomote the snake-like robot dexterously, a control system which adapts to such side-slipping is desired. There are two key points to realizing such a system: First, a dynamic model capable of representing the passive side-slipping must be formulated. A solution for the first key point is to develop a switching dynamic model for the snake-like robot, which switches depending on the occurrence of the side-slipping, by utilizing a projection method. The second key point is to adapt the control system’s behavior to side-slipping. An idea for such a solution is to include the side-slipping velocity in the weighting matrices. An algorithm to estimate the occurrence of side-slipping and the particular side-slipping link is constructed, to formulate the dynamic model depending on the actual side-slipping situation. The effectiveness of the designed Luenberger observer and the head control system for side-slipping adaptation is verified through numerical simulation.

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