Lijuan Wang’s research while affiliated with Wuhan University and other places

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Publications (29)


Convergence of minimal norm control problems of linear heat equations with time delay
  • Article

January 2024

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4 Reads

Mathematical Control and Related Fields

Yaxing Ma

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Lijuan Wang

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Xiuxiang Zhou

Equivalence of three kinds of optimal control problems for linear heat equations with memory
  • Article
  • Full-text available

November 2022

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26 Reads

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1 Citation

ESAIM Control Optimisation and Calculus of Variations

This paper studies an equivalence theorem for three different kinds of optimal control problems, which are optimal time control problems, optimal norm control problems, and optimal target control problems. The controlled systems in this paper are internally controlled linear heat equations with memory.

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Quantitative unique continuation for parabolic equations with Neumann boundary conditions

February 2022

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94 Reads

In this paper, we establish a globally quantitative estimate of unique continuation at one time point for solutions of parabolic equations with Neumann boundary conditions in bounded domains. Our proof is mainly based on Carleman commutator estimates and a global frequency function argument, which is motivated from a recent work [5]. As an application, we obtain an observability inequality from measurable sets in time for all solutions of the above equations.


Figure 1. Example.
A uniform bound on costs of controlling semilinear heat equations on a sequence of increasing domains and its application

January 2022

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41 Reads

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1 Citation

ESAIM Control Optimisation and Calculus of Variations

In this paper, we first prove a uniform upper bound on costs of null controls for semilinear heat equations with globally Lipschitz nonlinearity on a sequence of increasing domains, where the controls are acted on an equidistributed set that spreads out in the whole Euclidean space R N . As an application, we then show the exact null-controllability for this semilinear heat equation in R N . The main novelty here is that the upper bound on costs of null controls for such kind of equations in large but bounded domains can be made uniformly with respect to the sizes of domains under consideration. The latter is crucial when one uses a suitable approximation argument to derive the global null-controllability for the semilinear heat equation in R N . This allows us to overcome the well-known problem of the lack of compactness embedding arising in the study of null-controllability for nonlinear PDEs in generally unbounded domains.



Exact synchronization and asymptotic synchronization for linear ODEs

December 2021

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30 Reads

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2 Citations

Science China Mathematics

This paper studies exact synchronization and asymptotic synchronization problems for a controlled linear system of ordinary differential equations. In this paper, we build up necessary and sufficient conditions for exact synchronization and asymptotic synchronization problems. When a system is not controllable but exactly synchronizable, it can be asymptotically synchronized in any given rate and the state of exact synchronization is given. However, when a system is not controllable and can be asymptotically synchronized in any given rate, it may not be exactly synchronizable.


Minimal time control problem of a linear heat equation with memory

November 2021

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20 Reads

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2 Citations

Systems & Control Letters

This paper studies a minimal time control problem for a linear heat equation with memory. The purpose of such a problem is to find a control (among certain control constraint set), which steers the solution of the heat equation with memory from a given initial state to a given target as soon as possible. In this paper, we study the existence of optimal control to this problem, show the bang–bang property of the optimal control and build up a necessary and sufficient condition of the optimal control.



Minimal Time Impulse Control Problem of Semilinear Heat Equation

March 2021

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48 Reads

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3 Citations

Journal of Optimization Theory and Applications

The paper is concerned with a kind of minimal time impulse control problem for a semilinear heat equation. We study the existence of optimal controls of this problem, establish a nontrivial Pontryagin’s maximum principle for this problem and then derive the bang–bang property of optimal controls. Based on the existence and the bang–bang property of optimal controls, we discuss the equivalence of the minimal time impulse control problem and its corresponding minimal norm impulse control problem.



Citations (20)


... The plan of the proof of Lemma 1, inspired by the ideas presented in [14,16,30], is outlined as follows. In Step 1, we perform a change of function and introduce both the symmetric and antisymmetric parts. ...

Reference:

Null Approximate Impulse Controllability for a Degenerate Parabolic Equation in Non Divergence Form with Drift
Quantitative unique continuation for parabolic equations with Neumann boundary conditions
  • Citing Article
  • January 2022

Mathematical Control and Related Fields

... There are many interesting works about norm optimal control problems governed by evolution equations (see, for instance, [10], [9], [7], [15], [14], [6], [16]). Most of them are mainly concerned with two topics: characterization of norm optimal controls, and connections between minimal (or maximal) time controls and the minimal norm controls. ...

Equivalence of three kinds of optimal control problems for linear heat equations with memory

ESAIM Control Optimisation and Calculus of Variations

... On the one side, we want to avoid chaos in some fields of engineering for its characteristic. On the other side, chaotic property can be applied in secure communication in order to enhance the security of information [1][2][3][4][5]. These extensive and deep researches lead to a large number of areas of implementation related to nonlinear systems with chaotic characteristic. ...

Exact synchronization and asymptotic synchronization for linear ODEs
  • Citing Article
  • December 2021

Science China Mathematics

... In [20], the authors proved that the unique continuation estimate for the pure heat equation in R n holds if and only if the unbounded observable set is thick set. In [21,22], the authors proved a global interpolation inequality for solutions of the heat equation with bounded potential at one point of time variable using the parabolic-type frequency function method. In [23], the authors proved a Hölder-type interpolation inequalities of unique continuation for fractional order parabolic equations with space-time dependent potentials on a thick set. ...

A uniform bound on costs of controlling semilinear heat equations on a sequence of increasing domains and its application

ESAIM Control Optimisation and Calculus of Variations

... For such an ideal state, it is necessary to study dynamical systems with discontinuous trajectories, which can also be called impulsive dynamic systems. In recent years, due to the needs of modern technology, impulsive control system and impulsive perturbation system have attracted more and more attention, and the application of impulse dynamical system in technical problems is increasingly extensive, such as [33,7,39,37,3,28,30,34,29,26]. As is known to all that time delay is ubiquitous in dynamical systems and engineering applications. ...

Constrained Approximate Null Controllability of The Coupled Heat Equation with Impulse Controls
  • Citing Article
  • September 2021

SIAM Journal on Control and Optimization

... In fact, the theory of minimum time impulse controls has been extensively used in various practical mathematical models, and has become an important research field in recent years. This can be found in a large number of literature (see [1,4,7,11,12,15,16,21,23,26,28,31]). ...

Minimal Time Impulse Control Problem of Semilinear Heat Equation

Journal of Optimization Theory and Applications

... This question is motivated by the literature [14], which studies a similar equation in a bounded convex domain. Extensive related references can be found in [2,5,9,13] and the rich works cited therein. Reference [16] studies the relationship between the observation region and observability for the linear heat equation in R n and shows that an observation region satisfies the observability inequality if and only if it is γ−thick at scale L for some γ > 0 and L > 0. To study this problem, we need to characterize suitable conditions for the observation region ω. ...

Observability Inequalities for the Heat Equation with Bounded Potentials on the Whole Space
  • Citing Article
  • July 2020

SIAM Journal on Control and Optimization

... For time-dependent systems, the control problem (1.1)-(1.2) posed in M(Ī c ; L 2 (ω)) yields controls with compact support in time. This characteristic allows for determining the optimal moments for control device actions, akin to a generalization of impulse control [31][32][33][34][35][36][37][38][39][40][41]. Recall that in impulse control problems, the control q in (1.1)-(1.2) is replaced by ...

Minimal Norm Control Problem Governed by Semilinear Heat Equation with Impulse Control

Journal of Optimization Theory and Applications

... For time-dependent systems, the control problem (1.1)-(1.2) posed in M(Ī c ; L 2 (ω)) yields controls with compact support in time. This characteristic allows for determining the optimal moments for control device actions, akin to a generalization of impulse control [31][32][33][34][35][36][37][38][39][40][41]. Recall that in impulse control problems, the control q in (1.1)-(1.2) is replaced by ...

Minimal Time Impulse Control of an Evolution Equation

Journal of Optimization Theory and Applications