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Immunotherapy with interleukin-2: A study based on mathematical modeling

Sandip Banerjee (2008)

International Journal of Applied Mathematics and Computer Science

The role of interleukin-2 (IL-2) in tumor dynamics is illustrated through mathematical modeling, using delay differential equations with a discrete time delay (a modified version of the Kirshner-Panetta model). Theoretical analysis gives an expression for the discrete time delay and the length of the time delay to preserve stability. Numerical analysis shows that interleukin-2 alone can cause the tumor cell population to regress.

Improving the performance of semiglobal output controllers for nonlinear systems

Abdallah Benabdallah, Walid Hdidi (2017)

Kybernetika

For a large class of nonlinear control systems, the main drawback of a semiglobal stabilizing output feedback controllers ( 𝒰 R ) R > 0 with increasing regions of attraction ( Ω R ) R > 0 is that, when the region of attraction Ω R is large, the convergence of solutions of the closed-loop system to the origin becomes slow. To improve the performance of a semiglobal controller, we look for a new feedback control law that preserves the semiglobal stability of the nonlinear system under consideration and that is equal to some...

Improving the stability of discretization zeros with the Taylor method using a generalization of the fractional-order hold

Cheng Zeng, Shan Liang, Yuzhe Zhang, Jiaqi Zhong, Yingying Su (2014)

International Journal of Applied Mathematics and Computer Science

Remarkable improvements in the stability properties of discrete system zeros may be achieved by using a new design of the fractional-order hold (FROH) circuit. This paper first analyzes asymptotic behaviors of the limiting zeros, as the sampling period T tends to zero, of the sampled-data models on the basis of the normal form representation for continuous-time systems with a new hold proposed. Further, we also give the approximate expression of limiting zeros of the resulting sampled-data system...

Independence of asymptotic stability of positive 2D linear systems with delays of their delays

Tadeusz Kaczorek (2009)

International Journal of Applied Mathematics and Computer Science

It is shown that the asymptotic stability of positive 2D linear systems with delays is independent of the number and values of the delays and it depends only on the sum of the system matrices, and that the checking of the asymptotic stability of positive 2D linear systems with delays can be reduced to testing that of the corresponding positive 1D systems without delays. The effectiveness of the proposed approaches is demonstrated on numerical examples.

Indirect stabilization of locally coupled wave-type systems

Fatiha Alabau-Boussouira, Matthieu Léautaud (2012)

ESAIM: Control, Optimisation and Calculus of Variations

We study in an abstract setting the indirect stabilization of systems of two wave-like equations coupled by a localized zero order term. Only one of the two equations is directly damped. The main novelty in this paper is that the coupling operator is not assumed to be coercive in the underlying space. We show that the energy of smooth solutions of these systems decays polynomially at infinity, whereas it is known that exponential stability does not...

Indirect stabilization of locally coupled wave-type systems

Fatiha Alabau-Boussouira, Matthieu Léautaud (2012)

ESAIM: Control, Optimisation and Calculus of Variations

We study in an abstract setting the indirect stabilization of systems of two wave-like equations coupled by a localized zero order term. Only one of the two equations is directly damped. The main novelty in this paper is that the coupling operator is not assumed to be coercive in the underlying space. We show that the energy of smooth solutions of these systems decays polynomially at infinity, whereas it is known that exponential stability does not...

Infinite-dimensional LMI approach to analysis and synthesis for linear time-delay systems

Kojiro Ikeda, Takehito Azuma, Kenko Uchida (2001)

Kybernetika

This paper considers an analysis and synthesis problem of controllers for linear time-delay systems in the form of delay-dependent memory state feedback, and develops an Linear Matrix Inequality (LMI) approach. First, we present an existence condition and an explicit formula of controllers, which guarantee a prescribed level of L 2 gain of closed loop systems, in terms of infinite-dimensional LMIs. This result is rather general in the sense that it covers, as special cases, some known results for...

Input to state stability properties of nonlinear systems and applications to bounded feedback stabilization using saturation

J. Tsinias (2010)

ESAIM: Control, Optimisation and Calculus of Variations

The concepts of stability, attractivity and asymptotic stability for systems subject to restrictions of the input values are introduced and analyzed in terms of Lyapunov functions. A comparison with the well known input-to-state stability property introduced by Sontag is provided. We use these concepts in order to derive sufficient conditions for global stabilization for triangular and feedforward systems by means of saturated bounded feedback controllers and also recover some recent results...

Input-to-state stability of neutral type systems

Michael I. Gil' (2013)

Discussiones Mathematicae, Differential Inclusions, Control and Optimization

We consider the system ẋ ( t ) - ∫ ₀ η d R ̃ ( τ ) ẋ ( t - τ ) = ∫ 0 η d R ( τ ) x ( t - τ ) + [ F x ] ( t ) + u ( t ) (ẋ(t) ≡ dx(t)/dt), where x(t) is the state, u(t) is the input, R(τ),R̃(τ) are matrix-valued functions, and F is a causal (Volterra) mapping. Such equations enable us to consider various classes of systems from the unified point of view. Explicit input-to-state stability conditions in terms of the L²-norm are derived. Our main tool is the norm estimates for the matrix resolvents, as well as estimates for fundamental solutions of the linear parts of the considered systems,...

Input-to-state stability with respect to measurement disturbances for one-dimensional systems

Nicolas Chung Siong Fah (2010)

ESAIM: Control, Optimisation and Calculus of Variations

We consider one-dimensional affine control systems. We show that if such a system is stabilizable by means of a continuous, time-invariant feedback, then it can be made input-to-state stable with respect to measurement disturbances, using a continuous, periodic time-varying feedback. We provide counter-examples showing that the result does not generally hold if we want the feedback to be time-invariant or if the control system is not supposed affine.

Integral control of infinite-dimensional systems in the presence of hysteresis: an input-output approach

Hartmut Logemann, Eugene P. Ryan, Ilya Shvartsman (2007)

ESAIM: Control, Optimisation and Calculus of Variations

This paper is concerned with integral control of systems with hysteresis. Using an input-output approach, it is shown that application of integral control to the series interconnection of either (a) a hysteretic input nonlinearity, an L2-stable, time-invariant linear system and a non-decreasing globally Lipschitz static output nonlinearity, or (b) an L2-stable, time-invariant linear system and a hysteretic output nonlinearity, guarantees, under certain assumptions, tracking of constant reference...

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