scholarly journals QUADRATIC DIFFERENTIAL EQUATIONS: PARTIAL GELFAND–SHILOV SMOOTHING EFFECT AND NULL-CONTROLLABILITY

2020 ◽  
pp. 1-53
Author(s):  
Paul Alphonse
Keyword(s):  
Euclidean Space ◽  
Quadratic Differential ◽  
Parabolic Equations ◽  
Evolution Equations ◽  
Differential Operators ◽  
Null Controllability ◽  
Geometric Condition ◽  
Positive Time ◽  
Regularizing Effects ◽  
Necessary And Sufficient

We study the partial Gelfand–Shilov regularizing effect and the exponential decay for the solutions to evolution equations associated with a class of accretive non-selfadjoint quadratic operators, which fail to be globally hypoelliptic on the whole phase space. By taking advantage of the associated Gevrey regularizing effects, we study the null-controllability of parabolic equations posed on the whole Euclidean space associated with this class of possibly non-globally hypoelliptic quadratic operators. We prove that these parabolic equations are null-controllable in any positive time from thick control subsets. This thickness property is known to be a necessary and sufficient condition for the null-controllability of the heat equation posed on the whole Euclidean space. Our result shows that this geometric condition turns out to be a sufficient one for the null-controllability of a large class of quadratic differential operators.

scholarly journals Eventual domination for linear evolution equations

2021 ◽  
Author(s):  
Jochen Glück ◽  
Delio Mugnolo
Keyword(s):  
Evolution Equations ◽  
Differential Operators ◽  
Sufficient Conditions ◽  
Abstract Theory ◽  
Important Special Case ◽  
Linear Evolution ◽  
Necessary And Sufficient ◽  
Adjoint Operators ◽  
Linear Evolution Equations ◽  
Special Case

AbstractWe consider two $$C_0$$ C 0 -semigroups on function spaces or, more generally, Banach lattices and give necessary and sufficient conditions for the orbits of the first semigroup to dominate the orbits of the second semigroup for large times. As an important special case we consider an $$L^2$$ L 2 -space and self-adjoint operators A and B which generate $$C_0$$ C 0 -semigroups; in this situation we give criteria for the existence of a time $$t_1 \ge 0$$ t 1 ≥ 0 such that $$e^{tB} \ge e^{tA}$$ e tB ≥ e tA for all subsequent times $$t\ge t_1$$ t ≥ t 1 . As a consequence of our abstract theory, we obtain many surprising insights into the behaviour of various second and fourth order differential operators.

scholarly journals Controllability of a 2 × 2 parabolic system by one force with space-dependent coupling term of order one

2017 ◽  
Vol 23 (4) ◽  
pp. 1473-1498 ◽  
Author(s):  
Michel Duprez
Keyword(s):  
Parabolic Equations ◽  
Order Term ◽  
Null Controllability ◽  
Technical Tool ◽  
Bounded Interval ◽  
First Order ◽  
The Moment ◽  
Necessary And Sufficient ◽  
And Control ◽  
Main Technical Tool

This paper is devoted to the controllability of linear systems of two coupled parabolic equations when the coupling involves a space dependent first order term. This system is set on an bounded interval I ⊂⊂ R, and the first equation is controlled by a force supported in a subinterval of I or on the boundary. In the case where the intersection of the coupling and control domains is nonempty, we prove null controllability at any time. Otherwise, we provide a minimal time for null controllability. Finally we give a necessary and sufficient condition for the approximate controllability. The main technical tool for obtaining these results is the moment method.

scholarly journals Poisson hail on a hot ground

2011 ◽  
Vol 48 (A) ◽  
pp. 343-366
Author(s):  
Francois Baccelli ◽  
Sergey Foss
Keyword(s):  
Euclidean Space ◽  
Service Time ◽  
Evolution Equations ◽  
Stationary Regime ◽  
Service Discipline ◽  
Closed Sets ◽  
Random Closed Sets ◽  
Exponential Moments ◽  
First In First Out ◽  
Arrival Intensity

We consider a queue where the server is the Euclidean space, and the customers are random closed sets (RACSs) of the Euclidean space. These RACSs arrive according to a Poisson rain and each of them has a random service time (in the case of hail falling on the Euclidean plane, this is the height of the hailstone, whereas the RACS is its footprint). The Euclidean space serves customers at speed 1. The service discipline is a hard exclusion rule: no two intersecting RACSs can be served simultaneously and service is in the first-in–first-out order, i.e. only the hailstones in contact with the ground melt at speed 1, whereas the others are queued. A tagged RACS waits until all RACSs that arrived before it and intersecting it have fully melted before starting its own melting. We give the evolution equations for this queue. We prove that it is stable for a sufficiently small arrival intensity, provided that the typical diameter of the RACS and the typical service time have finite exponential moments. We also discuss the percolation properties of the stationary regime of the RACS in the queue.

scholarly journals Carleman estimates and null controllability of a class of singular parabolic equations

2018 ◽  
Vol 8 (1) ◽  
pp. 1057-1082
Author(s):  
Runmei Du ◽  
Jürgen Eichhorn ◽  
Qiang Liu ◽  
Chunpeng Wang
Keyword(s):  
Control Systems ◽  
Parabolic Equations ◽  
Null Controllability ◽  
Carleman Estimates ◽  
Energy Estimates ◽  
Semilinear Parabolic Equations ◽  
Linearized Equations ◽  
Singular Parabolic Equations ◽  
Semilinear Parabolic

Abstract In this paper, we consider control systems governed by a class of semilinear parabolic equations, which are singular at the boundary and possess singular convection and reaction terms. The systems are shown to be null controllable by establishing Carleman estimates, observability inequalities and energy estimates for solutions to linearized equations.

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