Authors:Abdelkarim Kelleche; Nasser-eddine Tatar Pages: 343 - 364 Abstract: The paper deals with an axially moving viscoelastic structure modeled as an Euler–Bernoulli beam. The aim is to suppress the transversal displacement (transversal vibrations) that occur during the axial motion of the beam. It is assumed that the beam is moving with a constant axial speed and it is subject to a nonlinear force at the right boundary. We prove that when the axial speed of the beam is smaller than a critical value, the dissipation produced by the viscoelastic material is sufficient to suppress the transversal vibrations. It is shown that the rate of decay of the energy depends on the kernel which arise in the viscoelastic term. We consider a general kernel and notice that solutions cannot decay faster than the kernel. PubDate: 2017-06-01 DOI: 10.1007/s00245-016-9334-8 Issue No:Vol. 75, No. 3 (2017)

Authors:I McGillivray Pages: 365 - 401 Abstract: Let U be a bounded open connected set in \(\mathbb {R}^n\) ( \(n\ge 1\) ). We refer to the unique weak solution of the Poisson problem \(-\Delta u = \chi _A\) on U with Dirichlet boundary conditions as \(u_A\) for any measurable set A in U. The function \(\psi :=u_U\) is the torsion function of U. Let V be the measure \(V:=\psi \,\mathscr {L}^n\) on U where \(\mathscr {L}^n\) stands for n-dimensional Lebesgue measure. We study the variational problem $$\begin{aligned} I(U,p):=\sup \Big \{ J(A)-V(U)\,p^2\,\Big \} \end{aligned}$$ with \(p\in (0,1)\) where \(J(A):=\int _Au_A\,dx\) and the supremum is taken over measurable sets \(A\subset U\) subject to the constraint \(V(A)=pV(U)\) . We relate the above problem to an unstable two-phase membrane problem. We characterise optimsers in the case \(n=1\) . The proof makes use of weighted isoperimetric and Pólya–Szegö inequalities. PubDate: 2017-06-01 DOI: 10.1007/s00245-016-9335-7 Issue No:Vol. 75, No. 3 (2017)

Authors:Maisa Khader; Belkacem Said-Houari Pages: 403 - 428 Abstract: We consider the Cauchy problem for the one-dimensional Timoshenko system coupled with the heat conduction, wherein the latter is described by the Gurtin–Pipkin thermal law. We study the decay properties of the system using the energy method in the Fourier space (to build an appropriate Lyapunov functional) accompanied with some integral estimates. We show that the number \(\alpha _g\) (depending on the parameters of the system) found in (Dell’Oro and Pata J Differ Equ 257(2):523–548, 2014), which rules the evolution in bounded domains, also plays a role in an unbounded domain and controls the behavior of the solution. In fact, we prove that if \(\alpha _g=0,\) then the \(L^2\) -norm of the solution decays with the rate \((1+t)^{-1/12}\) . The same decay rate has been obtained for \(\alpha _g\ne 0,\) but under some higher regularity assumption. This high regularity requirement is known as regularity loss, which means that in order to get the estimate for the \(H^s\) -norm of the solution, we need our initial data to be in the space \(H^{s+s_0},\ s_0>1\) . PubDate: 2017-06-01 DOI: 10.1007/s00245-016-9336-6 Issue No:Vol. 75, No. 3 (2017)

Authors:Giorgio Ferrari; Frank Riedel; Jan-Henrik Steg Pages: 429 - 470 Abstract: In this paper we study continuous-time stochastic control problems with both monotone and classical controls motivated by the so-called public good contribution problem. That is the problem of n economic agents aiming to maximize their expected utility allocating initial wealth over a given time period between private consumption and irreversible contributions to increase the level of some public good. We investigate the corresponding social planner problem and the case of strategic interaction between the agents, i.e. the public good contribution game. We show existence and uniqueness of the social planner’s optimal policy, we characterize it by necessary and sufficient stochastic Kuhn–Tucker conditions and we provide its expression in terms of the unique optional solution of a stochastic backward equation. Similar stochastic first order conditions prove to be very useful for studying any Nash equilibria of the public good contribution game. In the symmetric case they allow us to prove (qualitative) uniqueness of the Nash equilibrium, which we again construct as the unique optional solution of a stochastic backward equation. We finally also provide a detailed analysis of the so-called free rider effect. PubDate: 2017-06-01 DOI: 10.1007/s00245-016-9337-5 Issue No:Vol. 75, No. 3 (2017)

Authors:Jianliang Zhai; Tusheng Zhang Pages: 471 - 498 Abstract: In this paper, we establish a large deviation principle for stochastic models of incompressible second grade fluids. The weak convergence method introduced by Budhiraja and Dupuis (Probab Math Statist 20:39–61, 2000) plays an important role. PubDate: 2017-06-01 DOI: 10.1007/s00245-016-9338-4 Issue No:Vol. 75, No. 3 (2017)

Authors:Tijana Levajković; Hermann Mena; Amjad Tuffaha Pages: 499 - 523 Abstract: We present an approximation framework for computing the solution of the stochastic linear quadratic control problem on Hilbert spaces. We focus on the finite horizon case and the related differential Riccati equations (DREs). Our approximation framework is concerned with the so-called “singular estimate control systems” (Lasiecka in Optimal control problems and Riccati equations for systems with unbounded controls and partially analytic generators: applications to boundary and point control problems, 2004) which model certain coupled systems of parabolic/hyperbolic mixed partial differential equations with boundary or point control. We prove that the solutions of the approximate finite-dimensional DREs converge to the solution of the infinite-dimensional DRE. In addition, we prove that the optimal state and control of the approximate finite-dimensional problem converge to the optimal state and control of the corresponding infinite-dimensional problem. PubDate: 2017-06-01 DOI: 10.1007/s00245-016-9339-3 Issue No:Vol. 75, No. 3 (2017)

Authors:Hessah Al Motairi; Mihail Zervos Pages: 525 - 551 Abstract: We consider an irreversible capacity expansion model in which additional investment has a strictly negative effect on the value of an underlying stochastic economic indicator. The associated optimisation problem takes the form of a singular stochastic control problem that admits an explicit solution. A special characteristic of this stochastic control problem is that changes of the state process due to control action depend on the state process itself in a proportional way. PubDate: 2017-06-01 DOI: 10.1007/s00245-016-9341-9 Issue No:Vol. 75, No. 3 (2017)

Abstract: This paper analyzes problems in which a large benevolent player, controlling a set of policy variables, maximizes aggregate welfare in a continuous-time economy populated by atomistic agents subject to idiosyncratic shocks. We first provide as a benchmark the social optimum solution, in which a planner directly determines the individual controls. Then we analyze the optimal design of social policies depending on whether the large player may credibly commit to the future path of policies. On the one hand, we analyze the open-loop Stackelberg solution, in which the optimal policy path is set at time zero and the problem is time-inconsistent. On the other hand we analyze the time-consistent feedback Stackelberg solution. PubDate: 2017-06-23

Abstract: The paper studies the convergence, as N tends to infinity, of a system of N coupled Hamilton–Jacobi equations, the Nash system, when the coupling between the players becomes increasingly singular. The limit equation turns out to be a mean field game system with a local coupling. PubDate: 2017-06-23

Abstract: In this paper, by introducing a new concept of the (f, g, h)-quasimonotonicity and applying the maximal monotonicity of bifunctions and KKM technique, we show the existence results of solutions for quasi mixed equilibrium problems when the constraint set is compact, bounded and unbounded, respectively, which extends and improves several well-known results in many respects. Next, we also obtain a result of optimal control to a minimization problem. Our main results can be applied to the problems of evolution equations, differential inclusions and hemivariational inequalities. PubDate: 2017-06-22

Abstract: In this paper, we study the split common null point problem. Then, using the hybrid projection method and the metric resolvent of monotone operators, we prove a strong convergence theorem for an iterative method for finding a solution of this problem in Banach spaces. PubDate: 2017-06-22

Authors:Nguyen Quang Huy; Do Sang Kim; Nguyen Van Tuyen Abstract: In the present paper, we focus on the vector optimization problems with constraints, where objective functions and constrained functions are Fréchet differentiable, and whose gradient mapping is locally Lipschitz. By using the second-order symmetric subdifferential and the second-order tangent set, we introduce some new types of second-order regularity conditions in the sense of Abadie. Then we establish some second-order necessary optimality conditions Karush–Kuhn–Tucker-type for local efficient (weak efficient, Geoffrion properly efficient) solutions of the considered problem. In addition, we provide some sufficient conditions for a local efficient solution to such problem. PubDate: 2017-06-20 DOI: 10.1007/s00245-017-9432-2

Authors:Rong Liu; Guirong Liu Abstract: This paper investigates the optimal contraception control for a nonlinear size-structured population model with three kinds of mortality rates: intrinsic, intra-competition and female sterilant. First, we transform the model to a system of two subsystems, and establish the existence of a unique non-negative solution by means of frozen coefficients and fixed point theory, and show the continuous dependence of the population density on control variable. Then, the existence of an optimal control strategy is proved via compactness and extremal sequence. Next, necessary optimality conditions of first order are established in the form of an Euler–Lagrange system by the use of tangent-normal cone technique and adjoint system. Moreover, a numerical result for the optimal control strategy is presented. Our conclusions would be useful for managing the vermin. PubDate: 2017-06-19 DOI: 10.1007/s00245-017-9428-y

Authors:Nacira Agram; Bernt Øksendal Abstract: By a memory mean-field process we mean the solution \(X(\cdot )\) of a stochastic mean-field equation involving not just the current state X(t) and its law \(\mathcal {L}(X(t))\) at time t, but also the state values X(s) and its law \(\mathcal {L}(X(s))\) at some previous times \(s<t.\) Our purpose is to study stochastic control problems of memory mean-field processes. We consider the space \(\mathcal {M}\) of measures on \(\mathbb {R}\) with the norm \( \cdot _{\mathcal {M}}\) introduced by Agram and Øksendal (Model uncertainty stochastic mean-field control. arXiv:1611.01385v5, [2]), and prove the existence and uniqueness of solutions of memory mean-field stochastic functional differential equations. We prove two stochastic maximum principles, one sufficient (a verification theorem) and one necessary, both under partial information. The corresponding equations for the adjoint variables are a pair of (time-advanced backward stochastic differential equations (absdes), one of them with values in the space of bounded linear functionals on path segment spaces. As an application of our methods, we solve a memory mean–variance problem as well as a linear–quadratic problem of a memory process. PubDate: 2017-06-17 DOI: 10.1007/s00245-017-9425-1

Authors:Stefan Ankirchner; Maike Klein; Thomas Kruse Abstract: We consider the problem of optimally stopping a continuous-time process with a stopping time satisfying a given expectation cost constraint. We show, by introducing a new state variable, that one can transform the problem into an unconstrained control problem and hence obtain a dynamic programming principle. We characterize the value function in terms of the dynamic programming equation, which turns out to be an elliptic, fully non-linear partial differential equation of second order. We prove a classical verification theorem and illustrate its applicability with several examples. PubDate: 2017-06-10 DOI: 10.1007/s00245-017-9424-2

Authors:Qingying Hu; Hongwei Zhang; Gongwei Liu Abstract: We consider the initial boundary value problem for a class of logarithmic wave equations with linear damping. By constructing a potential well and using the logarithmic Sobolev inequality, we prove that, if the solution lies in the unstable set or the initial energy is negative, the solution will grow as an exponential function in the \(H^1_0(\Omega )\) norm as time goes to infinity. If the solution lies in a smaller set compared with the stable set, we can estimate the decay rate of the energy. These results are extensions of earlier results. PubDate: 2017-06-07 DOI: 10.1007/s00245-017-9423-3

Authors:Dirk Becherer; Todor Bilarev; Peter Frentrup Abstract: We study a multiplicative transient price impact model for an illiquid financial market, where trading causes price impact which is multiplicative in relation to the current price, transient over time with finite rate of resilience, and non-linear in the order size. We construct explicit solutions for the optimal control and the value function of singular optimal control problems to maximize expected discounted proceeds from liquidating a given asset position. A free boundary problem, describing the optimal control, is solved for two variants of the problem where admissible controls are monotone or of bounded variation. PubDate: 2017-05-24 DOI: 10.1007/s00245-017-9418-0

Authors:Jing Liu; Song Yao Abstract: Given \(p \in (1,2]\) , the wellposedness of backward stochastic differential equations with jumps (BSDEJs) in \(\mathbb {L}^p\) sense gives rise to a so-called g-expectation with \(\mathbb {L}^p\) domain under the jump filtration (the one generated by a Brownian motion and a Poisson random measure). In this paper, we extend such a g-expectation to a nonlinear expectation \(\mathcal{E}\) with \(\mathbb {L}^p\) domain that is consistent with the jump filtration. We study the basic (martingale) properties of the jump-filtration consistent nonlinear expectation \(\mathcal{E}\) and show that under certain domination condition, the nonlinear expectation \(\mathcal{E}\) can be represented by some g-expectation. PubDate: 2017-05-20 DOI: 10.1007/s00245-017-9422-4

Authors:Fatima Zahra Mokkedem; Xianlong Fu Abstract: In this paper we study the standard optimal control and time optimal control problems for a class of semilinear evolution systems with infinite delay. We first establish the results of existence and uniqueness of mild solution and the compactness of the solution operator for the control system. Then, based on these results, we investigate the optimal control problem with integral cost function and the time optimal control problem respectively. Under some conditions we show the existence of optimal controls for the both cases of bounded and unbounded admissible control sets. We also obtain the existence of time optimal control to a target set. In addition, a convergence theorem of time optimal controls to a point target set is proved. Finally, an example is given to show the application of the main results. PubDate: 2017-05-13 DOI: 10.1007/s00245-017-9420-6

Authors:Kazuo Yamazaki Abstract: The theory of micropolar fluids emphasizes the micro-structure of fluids by coupling the Navier–Stokes equations with micro-rotational velocity, and is widely viewed to be well fit, better than the Navier–Stokes equations, to describe fluids consisting of bar-like elements such as liquid crystals made up of dumbbell molecules or animal blood. Following the work of Weinan et al. (Commun Math Phys 224:83–106, 2001), we prove the existence of a unique stationary measure for the stochastic micropolar fluid system with periodic boundary condition, forced by only the determining modes of the noise and therefore a type of finite-dimensionality of micropolar fluid flow. The novelty of the manuscript is a series of energy estimates that is reminiscent from analysis in the deterministic case. PubDate: 2017-05-10 DOI: 10.1007/s00245-017-9419-z