scholarly journals Invariance under discretization for positive systems

2021 ◽  
Author(s):  
Zbigniew Bartosiewicz
Keyword(s):  
Nonlinear Systems ◽  
Control Systems ◽  
Discrete Time ◽  
Continuous Time ◽  
Positive Systems ◽  
Time System ◽  
Fundamental Properties ◽  
Linear And Nonlinear ◽  
Linear And Nonlinear Systems ◽  
Continuous Time System

AbstractPositive dynamical or control systems have all their variables nonnegative. Euler discretization transforms a continuous-time system into a system on a discrete time scale. Some structural properties of the system may be preserved by discretization, while other may be lost. Four fundamental properties of positive systems are studied in the context of discretization: positivity, positive stability, positive reachability and positive observability. Both linear and nonlinear systems are investigated.

scholarly journals Continuous-Time System Identification for Linear and Nonlinear Systems Using Wavelet Decompositions

1997 ◽  
Vol 07 (01) ◽  
pp. 87-96 ◽  
Author(s):  
D. Coca ◽  
S. A. Billings
Keyword(s):  
Experimental Data ◽  
System Identification ◽  
Nonlinear Systems ◽  
Continuous Time ◽  
Time System ◽  
New Approach ◽  
Linear And Nonlinear ◽  
Wavelet Decompositions ◽  
Linear And Nonlinear Systems ◽  
Continuous Time System

A new approach for estimating linear and nonlinear continuous-time models directly from noisy observations is introduced using wavelet decompositions. Results using both simulated and experimental data are included to demonstrate the performance of the new algorithm.

Stability of real-time hybrid simulation involving time-varying delay and direct integration algorithms

2021 ◽  
pp. 107754632110016
Author(s):  
Liang Huang ◽  
Cheng Chen ◽  
Shenjiang Huang ◽  
Jingfeng Wang
Keyword(s):  
Real Time ◽  
Discrete Time ◽  
Continuous Time ◽  
Hybrid Simulation ◽  
Time Varying ◽  
Discrete Time System ◽  
Time System ◽  
Integration Algorithms ◽  
The Stability ◽  
Continuous Time System

Stability presents a critical issue for real-time hybrid simulation. Actuator delay might destabilize the real-time test without proper compensation. Previous research often assumed real-time hybrid simulation as a continuous-time system; however, it is more appropriately treated as a discrete-time system because of application of digital devices and integration algorithms. By using the Lyapunov–Krasovskii theory, this study explores the convoluted effect of integration algorithms and actuator delay on the stability of real-time hybrid simulation. Both theoretical and numerical analysis results demonstrate that (1) the direct integration algorithm is preferably used for real-time hybrid simulation because of its computational efficiency; (2) the stability analysis of real-time hybrid simulation highly depends on actuator delay models, and the actuator model that accounts for time-varying characteristic will lead to more conservative stability; and (3) the integration step is constrained by the algorithm and structural frequencies. Moreover, when the step is small, the stability of the discrete-time system will approach that of the corresponding continuous-time system. The study establishes a bridge between continuous- and discrete-time systems for stability analysis of real-time hybrid simulation.

Harmony search optimization for robust pole assignment in union regions for synthesizing feedback control systems

2017 ◽  
Vol 40 (6) ◽  
pp. 1956-1969 ◽  
Author(s):  
Junchang Zhai ◽  
Liqun Gao ◽  
Steven Li
Keyword(s):  
Control Systems ◽  
Discrete Time ◽  
Continuous Time ◽  
Search Algorithm ◽  
Harmony Search ◽  
Pole Assignment ◽  
Harmony Search Algorithm ◽  
Time System ◽  
Feedback Control Systems ◽  
Time Systems

This paper is concerned with robust pole assignment optimization for synthesizing feedback control systems via state feedback or observer-based output feedback in specified union regions using the harmony search algorithm. By using exact pole placement theory and the harmony search algorithm, robust pole assignment for linear discrete-time systems or linear continuous-time systems in union regions can be converted into a global dynamical optimization problem. The robust measured indices are derived for robust union region stability constraints and a robust [Formula: see text] performance. For the nonlinear, robust measured indices, a set of dynamic poles and the corresponding feedback controllers can be obtained by global dynamic optimization based on the harmony search algorithm and the idea of robust exact pole assignment. One key merit of the proposed approach is that the radius or the position of the sub-regions can be arbitrarily specified according to the transient performance request. Furthermore, the eigenstructure of the closed-loop system matrix can be optimized with better robustness for the proposed approach. Finally, the simulation results for a discrete-time system and a continuous-time system demonstrate the effectiveness and superiority of the proposed method.

scholarly journals Extreme stability and almost periodicity in continuous and discrete neuronal models with finite delays

2002 ◽  
Vol 44 (2) ◽  
pp. 261-282 ◽  
Author(s):  
S. Mohamad ◽  
K. Gopalsamy
Keyword(s):  
Discrete Time ◽  
Continuous Time ◽  
Model Neuron ◽  
Sufficient Conditions ◽  
External Stimulus ◽  
Input Stimulus ◽  
Time System ◽  
Time Model ◽  
Discrete Time Model ◽  
Continuous Time System

We consider the dynamical characteristics of a continuous-time isolated Hopfield-type neuron subjected to an almost periodic external stimulus. The model neuron is assumed to be dissipative having finite time delays in the process of encoding the external input stimulus and recalling the encoded pattern associated with the external stimulus. By using non-autonomous Halanay-type inequalities we obtain sufficient conditions for the hetero-associative stable encoding of temporally non-uniform stimuli. A brief study of a discrete-time model derived from the continuous-time system is given. It is shown that the discrete-time model preserves the stability conditions of the continuous-time system.

Discrete-time approximationsfor continuous-time Markoviancontrol systems

1984 ◽  
Vol 16 (1) ◽  
pp. 15-16
Author(s):  
A. Hordijk ◽  
F. A. Van Der Duyn Schouten
Keyword(s):  
Decision Theory ◽  
Discrete Time ◽  
Continuous Time ◽  
Time System ◽  
Time Approximation ◽  
Discrete Time Systems ◽  
Discrete Time Approximation ◽  
And Control ◽  
Time Systems ◽  
Continuous Time System

The method of discrete-time approximation is widespread in control and decision theory. However, little attention has been paid to the conditions on parameters and control under which the discrete-time systems come close to the continuous-time system.

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