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As it is well-known, one of the main problems when dealing with fusion reactors is the plasma instability. The UPV/EHU Stellarator has been constructed to serve as a plasma control testbed so that the plasma behavior within the vacuum chamber may be studied for different real-time control laws. While in most of the large facilities the system control is performed by traditional control laws, the process...
This paper is devoted to the implications of the Kalman-Yakubovich-Popov Lemma, or Positive Real Lemma, when non-minimal state space realizations of transfer matrices of linear continuous systems are used. It is seen that some spurious parametrical conditions on the transfer matrix keep the Positive Real Lemma guaranteeing the stability from the associated Lyapunov equation.
This article covers research into rotational speed control for oscillating water column converters (OWC). The primary focus is the improvement of the Wells turbine performance by controlling its rotational speed. In this sense, the proposed control scheme has been implemented based on the NEREIDA MOWC demonstration project, a breakwater wave plant located in the Basque location of Mutriku, using Wells...
The bilinear system class under consideration is driven by two inputs: the control input plus a bilinear action input. The paper investigates the properties of positivity, transparency and excitability under the presence of state and external delays.
This paper is devoted to discuss the implications of the Kalman-Yakubovich-Popov Lemma, so-called also Positive Real Lemma, when non-minimal state space realizations of transfer matrices of linear continuous systems are used. It is seen that some extra parametrical conditions for positive realness of the transfer matrix to be equivalent to the stability Lemma from a Lyapunov equation with extended...
Epidemic basic models will be analysed. The goal is to study the stability of equilibrium points using the Lyapunov's indirect method, through the linearisation of the systems to study local stability, and the Lyapunov's direct method to study the global stability of each equilibrium point. A simulation example will show that, despite the simplicity of the models, they can give a good representation...
This paper states and studies an epidemic model where the dead corpses are also infective while the asymptomatic population is also present. There are several vaccination ways including susceptible vaccination, infectious antiviral control and culling of infectious corpses.
This paper discusses some relevant properties of a nonlinear integral equation such as the positivity and boundedness of its solution as well as its controllability under impulsive controls. The model can describe an infection evolution and the acting impulsive controls can be interpreted in particular as either vaccination actions or as variations of the infected population due to infected immigration...
This paper investigates some controllability properties of probabilistic discrete dynamic systems. Related approximate probabilistic controllability properties are also dealt with for the case when a nominal controllable system is subject to either parametrical perturbations or unmodeled dynamics.
In this paper, the discrete-time Kalman conjecture is shown to be false for systems of order two and above. Counterexamples are constructed. This contrasts with continuoustime domain systems where the Kalman conjecture is true for third-order systems.
This paper investigates stability and asymptotic properties of the error with respect to its nominal version of a non-linear time-varying perturbed functional differential system subject to point, finite-distributed and Volterra-type distributed delays associated with joint linear dynamics together with a class of a wide class of nonlinear delayed dynamics. The boundedness of the error and its asymptotic...
In this paper, a feedback-based vaccination policy is designed for a SEIR epidemic model based on the concept of partial stability of the closed-loop system. The implementable vaccination rule is designed by only taking into account the subpopulations of exposed and infectious in contrast to previous approaches where the immune and susceptible subpopulations were also considered. Therefore, the current...
This paper investigates the error between the approximate and exact solutions of a class of nonlinear differential equations which possess unique solution on a certain interval for any admissible initial conditions. The differential equations are assumed to be approximated by well-posed truncated Taylor series up to a certain order obtained about certain, in general non-periodic, sampling points t...
A mathematical model describing a generic disease is introduced and the dynamics of the subpopulations are studied. Through linearization of the continuous-time model, the stability of the equilibrium points and the characteristics of the disease are defined properly. Due to the nature of the disease, the model is discretized in order to apply some adaptive vaccination strategies involving feedback...
This paper applies the sliding mode control to a SEIR epidemic model. Initially, the controller is designed assuming certain knowledge on the upper-bounding of the uncertainty signal. Then, this condition is removed while an adaptive sliding control system is designed. The closed-loop system is able to achieve the control objective regardless the parametric uncertainties of the model and the lack...
The periodic regime in a SEIR model with a delay is studied in this paper. The model is studied first under a simple set of constant parameters and then a more complex solution is proposed, depending on a set of periodic parameters related to the variable risk of contracting the disease and the different vaccination strategies applied in order to prevent it. Both the periodic parameters and the subpopulations...
This paper proposes to use the concept of partial stability instead of that of global stability to analyze the dynamic behavior of epidemic models. The rationale behind this is that it is only needed, from a practical point of view, to ensure the boundedness of the infectious and infected subpopulations in order to get the disease under control. Thus, the partial stability of a controlled SEIR epidemic...
This paper examines decentralized observer-based stabilization for symmetric interconnected systems. The structure of these systems is composed of identical subsystems with symmetric interconnections. Linear time-invariant dynamic systems are considered within the continuous-time case. The observer inputs operate with a delayed system output. Single as well as multiple time-varying interval bounded...
An adaptive sliding mode position control for induction motors using field oriented control theory is presented. The proposed controller provides global asymptotic position tracking in the presence of unknown parameters and load torque variations. The proposed design incorporates an improved method of flux estimation that operates on the principle of flux and current observer. The proposed observer...
This paper presents a simple continuous-time linear vaccination-based control strategy for a SEIR (susceptible plus infected plus infectious plus removed populations) propagation disease model. The model takes into account the total population amounts as a refrain for the illness transmission since its increase makes more difficult contacts among susceptible and infected. The control objective is...
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