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The regularity of the positive part of functions in L 2 ( I ; H 1 ( Ω ) ) H 1 ( I ; H 1 ( Ω ) * ) with applications to parabolic equations

Daniel Wachsmuth — 2016

Commentationes Mathematicae Universitatis Carolinae

Let u L 2 ( I ; H 1 ( Ω ) ) with t u L 2 ( I ; H 1 ( Ω ) * ) be given. Then we show by means of a counter-example that the positive part u + of u has less regularity, in particular it holds t u + L 1 ( I ; H 1 ( Ω ) * ) in general. Nevertheless, u + satisfies an integration-by-parts formula, which can be used to prove non-negativity of weak solutions of parabolic equations.

Convergence analysis of smoothing methods for optimal control of stationary variational inequalities with control constraints

Anton SchielaDaniel Wachsmuth — 2013

ESAIM: Mathematical Modelling and Numerical Analysis - Modélisation Mathématique et Analyse Numérique

In the article an optimal control problem subject to a stationary variational inequality is investigated. The optimal control problem is complemented with pointwise control constraints. The convergence of a smoothing scheme is analyzed. There, the variational inequality is replaced by a semilinear elliptic equation. It is shown that solutions of the regularized optimal control problem converge to solutions of the original one. Passing to the limit in the optimality system of the regularized problem...

Sufficient optimality conditions and semi-smooth newton methods for optimal control of stationary variational inequalities

Karl KunischDaniel Wachsmuth — 2012

ESAIM: Control, Optimisation and Calculus of Variations

In this paper sufficient second order optimality conditions for optimal control problems subject to stationary variational inequalities of obstacle type are derived. Since optimality conditions for such problems always involve measures as Lagrange multipliers, which impede the use of efficient Newton type methods, a family of regularized problems is introduced. Second order sufficient optimality conditions are derived for the regularized problems...

Second-order sufficient optimality conditions for the optimal control of Navier-Stokes equations

Fredi TröltzschDaniel Wachsmuth — 2006

ESAIM: Control, Optimisation and Calculus of Variations

In this paper sufficient optimality conditions are established for optimal control of both steady-state and instationary Navier-Stokes equations. The second-order condition requires coercivity of the Lagrange function on a suitable subspace together with first-order necessary conditions. It ensures local optimality of a reference function in a L s -neighborhood, whereby the underlying analysis allows to use weaker norms than L .

Convergence and regularization results for optimal control problems with sparsity functional

Gerd WachsmuthDaniel Wachsmuth — 2011

ESAIM: Control, Optimisation and Calculus of Variations

Optimization problems with convex but non-smooth cost functional subject to an elliptic partial differential equation are considered. The non-smoothness arises from a -norm in the objective functional. The problem is regularized to permit the use of the semi-smooth Newton method. Error estimates with respect to the regularization parameter are provided. Moreover, finite element approximations are studied. as well as error estimates are developed and confirmed by numerical experiments....

Sufficient optimality conditions and semi-smooth newton methods for optimal control of stationary variational inequalities

Karl KunischDaniel Wachsmuth — 2012

ESAIM: Control, Optimisation and Calculus of Variations

In this paper sufficient second order optimality conditions for optimal control problems subject to stationary variational inequalities of obstacle type are derived. Since optimality conditions for such problems always involve measures as Lagrange multipliers, which impede the use of efficient Newton type methods, a family of regularized problems is introduced. Second order sufficient optimality conditions are derived for the regularized problems...

Second-order sufficient optimality conditions for the optimal control of Navier-Stokes equations

Fredi TröltzschDaniel Wachsmuth — 2005

ESAIM: Control, Optimisation and Calculus of Variations

In this paper sufficient optimality conditions are established for optimal control of both steady-state and instationary Navier-Stokes equations. The second-order condition requires coercivity of the Lagrange function on a suitable subspace together with first-order necessary conditions. It ensures local optimality of a reference function in a -neighborhood, whereby the underlying analysis allows to use weaker norms than .

Convergence and regularization results for optimal control problems with sparsity functional

Gerd WachsmuthDaniel Wachsmuth — 2011

ESAIM: Control, Optimisation and Calculus of Variations

Optimization problems with convex but non-smooth cost functional subject to an elliptic partial differential equation are considered. The non-smoothness arises from a -norm in the objective functional. The problem is regularized to permit the use of the semi-smooth Newton method. Error estimates with respect to the regularization parameter are provided. Moreover, finite element approximations are studied. as well as error estimates are developed and confirmed by numerical experiments. ...

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