Model free control based on GIMC structure
- Authors: Wang, Zenghui.
- Date: 2012.
- Subjects: Generalized internal model control. , Model free controller. , Nominal model. , Stability. , Uncertain system.
- Language: English
- Type: Article.
- Identifier: http://hdl.handle.net/10210/16724 , uj:15806 , Citation: Wang, Z. et al. 2012. Model free control based on GIMC structure. International journal of control, automation, and systems, 10(1):173-179. , DOI: 10.1007/s12555-012-0120-3
- Description: Abstract: Many control researches for complicated and uncertain system are model-dependent and therefore require some prior knowledge for the complex systems. To avoid this problem, a number of model-free controllers are proposed. However, it is difficult to determine the control performance as the controller is not designed according certain system model especially when there are uncertainties and/or nonlinear dynamics in the system. To get over this problem, the model free controller (MFC) based on generalized internal model control (GIMC) structure is proposed in this paper. The MFC is used to attenuate the disturbance or uncertainty, and the system performance is determined by the nominal model and the nominal model controller. The parameters of nominal-model controller can be easily changed for meeting the change of the desired requirements. Moreover, the robust controller in the original GIMC is disassembled and rearranged to make the proposed methods easier to use, and the proposed method makes the controller be more flexible and greatly improves the system performance. Finally, the experiment results show that the MFC can be used to control the nonlinear systems and get the expected performance. The statistical analysis of performance for servo and regulatory behaviors also shows that the proposed method can achieve a better control performance than just using model free controller.
- Full Text:
- Authors: Wang, Zenghui.
- Date: 2012.
- Subjects: Generalized internal model control. , Model free controller. , Nominal model. , Stability. , Uncertain system.
- Language: English
- Type: Article.
- Identifier: http://hdl.handle.net/10210/16724 , uj:15806 , Citation: Wang, Z. et al. 2012. Model free control based on GIMC structure. International journal of control, automation, and systems, 10(1):173-179. , DOI: 10.1007/s12555-012-0120-3
- Description: Abstract: Many control researches for complicated and uncertain system are model-dependent and therefore require some prior knowledge for the complex systems. To avoid this problem, a number of model-free controllers are proposed. However, it is difficult to determine the control performance as the controller is not designed according certain system model especially when there are uncertainties and/or nonlinear dynamics in the system. To get over this problem, the model free controller (MFC) based on generalized internal model control (GIMC) structure is proposed in this paper. The MFC is used to attenuate the disturbance or uncertainty, and the system performance is determined by the nominal model and the nominal model controller. The parameters of nominal-model controller can be easily changed for meeting the change of the desired requirements. Moreover, the robust controller in the original GIMC is disassembled and rearranged to make the proposed methods easier to use, and the proposed method makes the controller be more flexible and greatly improves the system performance. Finally, the experiment results show that the MFC can be used to control the nonlinear systems and get the expected performance. The statistical analysis of performance for servo and regulatory behaviors also shows that the proposed method can achieve a better control performance than just using model free controller.
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Chaotic particle swarm optimization with neural network structure and its application
- Sun. A., Hopfield neural network.
- Authors: Sun. A. , Hopfield neural network.
- Date: 2011
- Subjects: Particle swarm optimization. , Bifurcation. , Convergence.
- Language: English
- Type: Article.
- Identifier: http://hdl.handle.net/10210/17007 , uj:15833 , ISSN: 0305-215X , Citation: Sun, Y. 2011. Chaotic particle swarm optimization with neural network structure and its application. Engineering Optimization, 43(1): 19-37
- Description: Abstract: A new particle swarm optimization (PSO) algorithm having a chaotic Hopfield Neural Network (HNN) structure is proposed. Particles exhibit chaotic behaviour before converging to a stable fixed point which is determined by the best points found by the individual particles and the swarm. During the evolutionary process, the chaotic search expands the search space of individual particles. Using a chaotic system to determine particle weights helps the PSO to escape from the local extreme and find the global optimum. The algorithm is applied to some benchmark problems and a pressure vessel problem with nonlinear constraints. The results show that the proposed algorithm consistently outperforms rival algorithms by enhancing search efficiency and improving search quality
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- Authors: Sun. A. , Hopfield neural network.
- Date: 2011
- Subjects: Particle swarm optimization. , Bifurcation. , Convergence.
- Language: English
- Type: Article.
- Identifier: http://hdl.handle.net/10210/17007 , uj:15833 , ISSN: 0305-215X , Citation: Sun, Y. 2011. Chaotic particle swarm optimization with neural network structure and its application. Engineering Optimization, 43(1): 19-37
- Description: Abstract: A new particle swarm optimization (PSO) algorithm having a chaotic Hopfield Neural Network (HNN) structure is proposed. Particles exhibit chaotic behaviour before converging to a stable fixed point which is determined by the best points found by the individual particles and the swarm. During the evolutionary process, the chaotic search expands the search space of individual particles. Using a chaotic system to determine particle weights helps the PSO to escape from the local extreme and find the global optimum. The algorithm is applied to some benchmark problems and a pressure vessel problem with nonlinear constraints. The results show that the proposed algorithm consistently outperforms rival algorithms by enhancing search efficiency and improving search quality
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Coexistence of multiple strange attractors governed by different initial conditions in a deterministic system
- Cang, Shi-Jian., Chen, Zeng-Qiang., Sun, Yan-Xia.
- Authors: Cang, Shi-Jian. , Chen, Zeng-Qiang. , Sun, Yan-Xia.
- Date: 2010.
- Subjects: Periodic attractor. , Chaotic attractor. , Coexistence. , Deterministic system.
- Language: English.
- Type: Article.
- Identifier: http://hdl.handle.net/10210/17560 , uj:15898 , ISSN: 1565-1339 , Citation: Cang, S-J. et al. 2010. Coexistence of multiple strange attractors governed by different initial conditions in a deterministic system. International journal of nonlinear sciences & numerical simulation, 11(9): 671-677.
- Description: Abstract: This paper presents a new four-dimension autonomous system which shows extraordinary dynamical properties . Chaotic attractor and periodic attractor or hyper-chaotic attractor and quasi-periodic attractor, which are governed by different initial conditions instead of the system parameters, can coexist in the deterministic system. These interesting phenomena are verified through numerical simulations and analyses including time series, phase portraits, Poincaré maps, bifurcation diagrams, and Lyapunov exponents.
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- Authors: Cang, Shi-Jian. , Chen, Zeng-Qiang. , Sun, Yan-Xia.
- Date: 2010.
- Subjects: Periodic attractor. , Chaotic attractor. , Coexistence. , Deterministic system.
- Language: English.
- Type: Article.
- Identifier: http://hdl.handle.net/10210/17560 , uj:15898 , ISSN: 1565-1339 , Citation: Cang, S-J. et al. 2010. Coexistence of multiple strange attractors governed by different initial conditions in a deterministic system. International journal of nonlinear sciences & numerical simulation, 11(9): 671-677.
- Description: Abstract: This paper presents a new four-dimension autonomous system which shows extraordinary dynamical properties . Chaotic attractor and periodic attractor or hyper-chaotic attractor and quasi-periodic attractor, which are governed by different initial conditions instead of the system parameters, can coexist in the deterministic system. These interesting phenomena are verified through numerical simulations and analyses including time series, phase portraits, Poincaré maps, bifurcation diagrams, and Lyapunov exponents.
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The effects of fractional order on a 3-D quadratic autonomous system with four-wing attractor.
- Wang, Z.
- Authors: Wang, Z.
- Date: 2010.
- Subjects: Fractional order. , Four-wing attractor. , Bifurcation. , Lyapunov exponent.
- Type: Article.
- Identifier: http://hdl.handle.net/10210/17149 , uj:15853 , DOI: 10.1007/s11071-010-9705-7 , Citation: Wang, Z. 2010. The effects of fractional order on a 3-D quadratic autonomous system with four-wing attractor. Nonlinear Dyn, 62(139-150)
- Description: Abstract: In this paper, a fractional 3-dimensional (3-D) 4-wing quadratic autonomous system (Qi system) is analyzed. Time domain approximation method (Grunwald–Letnikov method) and frequency domain approximationmethod are used together to analyze the behavior of this fractional order chaotic system. It is found that the decreasing of the system order has great effect on the dynamics of this nonlinear system. The fractional Qi system can exhibit chaos when the total order less than 3, although the regular one always shows periodic orbits in the same range of parameters. In some fractional order, the 4 wings are decayed to a scroll using the frequency domain approximation method which is different from the result using time domain approximation method. A surprising finding is that the phase diagrams display a character of local self-similar in the 4-wing attractors of this fractional Qi system using the frequency approximation method even though the number and the characteristics of equilibria are not changed. The frequency spectrums show that there is some shrinking tendency of the bandwidth with the falling of the system states order. However, the change of fractional order has little effect on the bandwidth of frequency spectrum using the time domain approximation method. According to the bifurcation analysis, the fractional order Qi system attractors start from sink, then period bifurcation to some simple periodic orbits, and chaotic attractors, finally escape from chaotic attractor to periodic orbits with the increasing of fractional order α in the interval [0.8, 1]. The simulation results revealed that the time domain approximation method is more accurate and reliable than the frequency domain approximation method.
- Full Text:
- Authors: Wang, Z.
- Date: 2010.
- Subjects: Fractional order. , Four-wing attractor. , Bifurcation. , Lyapunov exponent.
- Type: Article.
- Identifier: http://hdl.handle.net/10210/17149 , uj:15853 , DOI: 10.1007/s11071-010-9705-7 , Citation: Wang, Z. 2010. The effects of fractional order on a 3-D quadratic autonomous system with four-wing attractor. Nonlinear Dyn, 62(139-150)
- Description: Abstract: In this paper, a fractional 3-dimensional (3-D) 4-wing quadratic autonomous system (Qi system) is analyzed. Time domain approximation method (Grunwald–Letnikov method) and frequency domain approximationmethod are used together to analyze the behavior of this fractional order chaotic system. It is found that the decreasing of the system order has great effect on the dynamics of this nonlinear system. The fractional Qi system can exhibit chaos when the total order less than 3, although the regular one always shows periodic orbits in the same range of parameters. In some fractional order, the 4 wings are decayed to a scroll using the frequency domain approximation method which is different from the result using time domain approximation method. A surprising finding is that the phase diagrams display a character of local self-similar in the 4-wing attractors of this fractional Qi system using the frequency approximation method even though the number and the characteristics of equilibria are not changed. The frequency spectrums show that there is some shrinking tendency of the bandwidth with the falling of the system states order. However, the change of fractional order has little effect on the bandwidth of frequency spectrum using the time domain approximation method. According to the bifurcation analysis, the fractional order Qi system attractors start from sink, then period bifurcation to some simple periodic orbits, and chaotic attractors, finally escape from chaotic attractor to periodic orbits with the increasing of fractional order α in the interval [0.8, 1]. The simulation results revealed that the time domain approximation method is more accurate and reliable than the frequency domain approximation method.
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Plugging mechanisms and plugging reduction techniques in heap leaching operations: a review.
- Kime, Méschac-Bill., Malenga, Edouard., Nheta, Willy.
- Authors: Kime, Méschac-Bill. , Malenga, Edouard. , Nheta, Willy.
- Subjects: Heap leaching. , Plugging mechanisms. , Pore spaces. , Permeability. , Recovery.
- Type: Article.
- Identifier: http://hdl.handle.net/10210/20256 , uj:16083 , Citation: Kime, M-B., Malenga, E., Nheta, W. Plugging mechanisms and plugging reduction techniques in heap leaching operations: a review.
- Description: Abstract: Plugging of pore spaces is the most significant contributor to ponding, decrease in the mineral resource recoveries and stability problems in heap leaching operations as ore permeability is reduced. Consequently, the identification of different plugging mechanisms is very important for optimisation of heap leaching processes. This paper reviews various pore spaces plugging mechanisms, including ore heap compaction, migration of fine particles, presence of large fractions of clays in ores, agglomerate destruction under acid effect and dissolution-precipitation processes. Proactive plugging reduction techniques including ore placement, ore agglomeration, heap aeration and lixiviant application techniques are also explained as means to prevent pore spaces plugging during heap leaching operations. The findings of this paper can be useful in guiding laboratory and industrial heap leaching operations.
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- Authors: Kime, Méschac-Bill. , Malenga, Edouard. , Nheta, Willy.
- Subjects: Heap leaching. , Plugging mechanisms. , Pore spaces. , Permeability. , Recovery.
- Type: Article.
- Identifier: http://hdl.handle.net/10210/20256 , uj:16083 , Citation: Kime, M-B., Malenga, E., Nheta, W. Plugging mechanisms and plugging reduction techniques in heap leaching operations: a review.
- Description: Abstract: Plugging of pore spaces is the most significant contributor to ponding, decrease in the mineral resource recoveries and stability problems in heap leaching operations as ore permeability is reduced. Consequently, the identification of different plugging mechanisms is very important for optimisation of heap leaching processes. This paper reviews various pore spaces plugging mechanisms, including ore heap compaction, migration of fine particles, presence of large fractions of clays in ores, agglomerate destruction under acid effect and dissolution-precipitation processes. Proactive plugging reduction techniques including ore placement, ore agglomeration, heap aeration and lixiviant application techniques are also explained as means to prevent pore spaces plugging during heap leaching operations. The findings of this paper can be useful in guiding laboratory and industrial heap leaching operations.
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