Turnpike theorem for an infinite horizon optimal control problem with time delay

An optimal control problem for systems described by a special class of nonlinear differential equations with time delay is considered. The cost functional adopted could be considered as an analogue of the terminal functional defined over an infinite time horizon. The existence of optimal solutions as well as the asymptotic stability of optimal trajectories (that is, the turnpike property) are established under some quite mild restrictions on the nonlinearities of the functions involved in the description of the problem. Such mild restrictions on the nonlinearities allowed us to apply these results to a blood cell production model. © 2014 Society for Industrial and Applied Mathematics

Discrete-continuous analysis of optimal equipment replacement

In Operations Research, the equipment replacement process is usually modeled in discrete time. The optimal replacement strategies are found from discrete (or integer) programming problems, well known for their analytic and computational complexity. An alternative approach is represented by continuous-time vintage capital models that explicitly involve the equipment lifetime and are described by nonlinear integral equations. Then the optimal replacement is determined via the optimal control of such equations. These two alternative techniques describe essentially the same controlled dynamic process. We introduce and analyze a model that unites both approaches. The obtained results allow us to explore such important effects in optimal asset replacement as the transition and long-term dynamics, clustering and splitting of replaced assets, and the impact of improving technology and discounting. In particular, we demonstrate that the cluster splitting is possible in our replacement model with given demand in the case of an increasinTheoretical findings are illustrated with numeric examples.vintage capital models, optimization, equipment lifetime, discrete-continuous models.

Investment, replacement and scrapping in a vintage capital model with embodied technological change

This paper analyzes and compares two alternative policies of determining the service life and replacement demand for vintage equipment under embodied technological change. The policies are the infinite-horizon replacement and the transitory replacement ending with scrapping. The corresponding vintage capital models are formulated in the dynamic optimization framework. These two approaches lead to different estimates of the duration of replacements and the impact of technological change on the equipment service life.vintage capital equipment; embodied technological change; service life; replacement; scrapping

Turnpilke property for infinite-dimensional generalized LQ problem

We provide a characterization of the exponential (integral) turnpike property for infinite dimensional generalized linear-quadratic optimal control problems in terms of structural properties of the control system, such as exponential stabilizability and detectability. The proof relies on the analysis of the exponential convergence of solutions to the differential Riccati equations to the algebraic counterpart, and on a necessary condition for exponential stabilizability in terms of a closed range test

An exponential turnpike theorem for dissipative discrete time optimal control problems

revised 2013, 23 p.International audienceWe investigate the exponential turnpike property for nite horizon undercounted discrete time optimal control problems without any terminal constraints. Considering a class of strictly dissipative systems we derive a boundedness condition for an auxiliary optimal value function which implies the exponential turnpike property. Two theorems illustrate how this boundedness condition can be concluded from structural properties like controllability and stabilizability of the control system under consideration

Manifold turnpikes of nonlinear port-Hamiltonian descriptor systems under minimal energy supply

Turnpike phenomena of nonlinear port-Hamiltonian descriptor systems under minimal energy supply are studied. Under assumptions on the smoothness of the system nonlinearities, it is shown that the optimal control problem is dissipative with respect to a manifold. Then, under controllability assumptions, it is shown that the optimal control problem exhibits a manifold turnpike property

Optimal control of the Lotka–Volterra system: turnpike property and numerical simulations

The Lotka-Volterra model is a differential system of two coupled equations representing the interaction of two species: a prey one and a predator one. We formulate an optimal control problem adding the effect of hunting both species as the control variable. We analyse the optimal hunting problem paying special attention to the nature of the optimal state and control trajectories in long time intervals. To do that, we apply recent theoretical results on the frame to show that, when the time horizon is large enough, optimal strategies are nearly steady-state. Such path is known as turnpike property. Some experiments are performed to observe such turnpike phenomenon in the hunting problem. Based on the turnpike property, we implement a variant of the single shooting method to solve the previous optimisation problem, taking the middle of the time interval as starting point

Turnpike Property for Generalized Linear-Quadratic Optimal Control Problem

The turnpike phenomenon describes the long time behavior of optimally controlled systems whose optimal trajectories over a sufficiently large time horizon stay for most of the time close to a prescribed trajectory of the system. This thesis is devoted to the characterization of the turnpike property for generalized LQ optimal control problem. Through our research, we derive both sufficient and necessary conditions for the turnpike property in infinite dimensional setting. It is shown that the turnpike property is closely related to certain structural properties of the control system. In particular, we deduce an equivalent condition of the turnpike property in terms of the exponential stabilizability and detectability of the system for finite dimensional case and point spectrum case. We also show in our thesis that the turnpike property for generalized LQ optimal control problem is equivalent to the turnpike property for LQ optimal control problem plus an algebraic condition. Next, we investigate the applications of our results to the generalized LQ optimal control problem subject to the parabolic equations, wave equations, delay equations and in relation with model predictive control schemes

Optimal Equipment Replacement and Scrapping Under Improving Technology

The rational replacement management of hi-tech equipment is an important problem of technology management. This paper analyzes and compares two alternative policies for determining the service life and replacement demand of industrial equipment under improving technology. These policies lead to different estimates of the impact of new technology on the replacement policies and equipment service life