A novel coronavirus, designated as COVID-19, emerged in Wuhan, China, at the end of 2019. In this paper, a mathematical model is proposed to analyze the dynamic behavior of COVID-19. Based on inter-city networked coup...
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In this paper, a generalized fractional-order SEIR model is proposed, denoted by SEIQRP model, which has a basic guiding significance for the prediction of the possi-ble outbreak of infectious diseases like COVID-19 a...
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Evacuation of crowds in a corridor with only one exit has been considered in this paper where distributed controllers have been constructed to regulate the crowd’s evacuation speed so that stampede tragedy can be avo...
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Evacuation of crowds in a corridor with only one exit has been considered in this paper where distributed controllers have been constructed to regulate the crowd’s evacuation speed so that stampede tragedy can be avoided. Macroscopic model for crowds of pedestrians has been firstly derived based on inspiration of LWR (Lighthill-Whitham and Richards) model and Greenshields model from traffic system where finite volume method has been introduced to simplify the obtained PDEs into finite ODEs. Distributed evacuation controllers have been constructed based on inspiration of multi-agent system and stability analysis of obtained closed-loop system has been simplified to linear system with the delicate controllers proposed. Comparisons between distributed evacuation controllers and previous evacuation controllers have also been presented to show the advantages and disadvantages of different controllers under different initial density of crowds so that tragedy of crowd stampede can be effectively avoided with appropriate selection of different controllers.
Non-Gaussian statistical signal processing is be-coming increasingly significant in the current complex world. However, the variance of a non-Gaussian distribution may not exist, therefore many conventional methods wi...
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ISBN:
(数字)9781728159539
ISBN:
(纸本)9781728159546
Non-Gaussian statistical signal processing is be-coming increasingly significant in the current complex world. However, the variance of a non-Gaussian distribution may not exist, therefore many conventional methods will be considerably weakened, meaningless or even misleading. For example, the least-squares criterion may not be robust in the non-Gaussian environment, owing to the impulsive behaviors and outliers. In the paper, the statistical measures with fractional lower order moments (FLOM) are used instead of second-order moments to assess the control performance for non-Gaussian processes. The results show that FLOM is robust against outliers for the non-Gaussian signals. In the end, Hurst exponent fitting with FLOM and multifractal detrended fluctuation analysis (MFDFA) with FLOM are applied to the real data.
Due to the stochastic of multi-agent systems, it is difficult to achieve strict consensus. In this paper, consensus in the sense of probability is achieved by reducing the output error entropy of multi-agent system. S...
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ISBN:
(数字)9781728182162
ISBN:
(纸本)9781728182179
Due to the stochastic of multi-agent systems, it is difficult to achieve strict consensus. In this paper, consensus in the sense of probability is achieved by reducing the output error entropy of multi-agent system. Sliding mode controller is the core to keep the system stability and probability density function(PDF) compensator is used to reduce the chattering effect of sliding mode and compensate the random part of the system. Radial basis function neural network combined with the minimum entropy criterion is used to model the PDF compensator, and the output error entropy of the system is minimized through the training of weights, so as to optimize the control effect. Finally, the simulation results verify the effectiveness of the method.
Selective Catalytic Reduction (SCR) is widely adopted as the flue gas denitrification method in coal-fired power plants. For the denitrification process in coal-fired power plants, the amount of ammonia injected is cr...
Selective Catalytic Reduction (SCR) is widely adopted as the flue gas denitrification method in coal-fired power plants. For the denitrification process in coal-fired power plants, the amount of ammonia injected is crucial for controlling nitrogen oxide concentrations in the flue gas. This paper adjusts the denitrification process model of SCR by analyzing its internal structure characteristics. It establishes a hierarchical change calculation SCR dynamic model by improving the method for calculating changes in flue gas concentration inside the SCR reactor. Simulation results demonstrate that the improved SCR mechanism model maintains fitting accuracy within 10% across diverse actual operating data. Based on the denitrification system’s characteristics, a modified active disturbance rejection control(MADRC) is designed and applied to the actual denitrification system. The running data indicate that replacing the ammonia spray valves on both sides of the SCR with MADRC and running for some time, the positive and negative deviations of the NO concentration at the SCR outlet on both sides remained within 20 mg/m 3 , indicating that the application of MADRC in the denitrification system has significant potential.
In this paper, we study the boundary stabilization and disturbance rejection for an unstable time fractional diffusion-wave equation involving Caputo time fractional derivative. When there is no boundary external dist...
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In this paper, we study the boundary stabilization and disturbance rejection for an unstable time fractional diffusion-wave equation involving Caputo time fractional derivative. When there is no boundary external disturbance, both state feedback control and output feedback control via boundary actuation are proposed by the classical backstepping method. It is proved that the state feedback makes the closed-loop system Mittag-Leffler stable while the output feedback makes the closed-loop system asymptotically stable. When there is boundary external disturbance, we propose a disturbance estimator which is constructed by two infinite dimensional auxiliary systems to recover the external disturbance. The resulting closed-loop system is Mittag-Leffler stable and the states of all subsystem involved are uniformly bounded. As a byproduct, we solve rigorously completely the two longtime unsolved problems raised in [Nonlinear Dynam., 38(2004), 339-354] where all the results are only verified by simulations.
The fractional order proportional integral derivative controller is attracting more and more attention. To design a controller with some specification constraints for the first order plus time delay (FOPTD) system, th...
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The fractional order proportional integral derivative controller is attracting more and more attention. To design a controller with some specification constraints for the first order plus time delay (FOPTD) system, the idea of the “more flat phase” and the structure of the fractional order [proportional integral derivative] (FO[PID]) controller are proposed in this paper. Firstly, the stability region of the FO[PID] controller and the controller design with the “more flat phase” are introduced. Then the design procedure is presented by a simulation, and the pseudo code of the design procedure to obtain the parameter pairs and the achievable region is offered. The effectiveness of the proposed design method for the FO[PID] controller is verified by the experiment on the Peltier temperature control platform and the experiment results show a great potential in industrial applications.
The heat transfer dynamic is extremely common in industry process. The time-delay with single fractional pole(TDSFP) model gives higher accuracy than first-order plus time-delay(FOPTD) model for the ideal heat transfe...
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The heat transfer dynamic is extremely common in industry process. The time-delay with single fractional pole(TDSFP) model gives higher accuracy than first-order plus time-delay(FOPTD) model for the ideal heat transfer process. Actuator rate limit is a common and important phenomenon in heating process control and is becoming a stumbling block in precision process control. The actuator will get saturated for a certain duration when the identification test signal is a step function. The time duration when actuator rate is saturated can be misidentified as the delay of the process model, which misleads the controller design and generates unsatisfactory performance. This paper proposes a new model structure in identifying a TDSFP process under the step test signal and this model structure considers actuator rate limit. Parameters sensitivity is analyzed to access the effect of identification accuracy resulting from parameters estimation mismatch. An illustrative example is given to show the effectiveness of the proposed identification method and the sensitivity of system parameters.
Superheated steam temperature (SST) systems face many control difficulties caused by unknown disturbances and high order dynamics. This is becoming more and more severe due to the rapid growing of intermittent renewab...
Superheated steam temperature (SST) systems face many control difficulties caused by unknown disturbances and high order dynamics. This is becoming more and more severe due to the rapid growing of intermittent renewable generation. To improve the tracking and disturbance rejection performance of SST systems, a modified active disturbance rejection control (ADRC) is proposed. Based on its equivalent structure, this paper develops the frequency-domain analysis of the modified ADRC to present the influence of parameters on the control performance. Then the modified ADRC based on the frequency-domain analysis is applied to the SST control to verify the superiority of the modified ADRC. Based on the results of the simulation and the field application on a power plant simulator, the modified ADRC can obtain the best tracking performance with a small overshoot and short settling time compared with other comparative controllers. Besides, the modified ADRC has the smallest fluctuation range of SST under the input disturbance and load varying conditions. The superiority of the modified ADRC ensures the satisfactory control performance and shows a great potential in industrial applications.
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