Coronavirus disease of 2019 or COVID-19 (acronym for coronavirus disease 2019) is an emerging infectious disease caused by a strain of coronavirus called SARS-CoV-22, contagious with human-to-human transmission via respiratory droplets or by touching contaminated surfaces then touching them face. Faced with what the world lives, to define this problem, we have modeled it as an optimal control problem based on the models of William Ogilvy Kermack et Anderson Gray McKendrick, called SEIR model, modified by adding compartments suitable for our study. Our objective in this work is to maximize the number of recovered people while minimizing the number of infected. We solved the problem theoretically using the Pontryagin maximum principle, numerically we used and compared results of two methods namely the indirect method (shooting method) and the Euler discretization method, implemented in MATLAB.

Algeria is rich country, it uses fertilizers to improve its cereal production as it is usually known. However, Algerian farmers use fertilizers in a bad manner and in a quite random way. This causes both ground, water pollution, and a loss of output.In the present paper we study a modelization of the evolution of the cereal output production controlled by means of adding fertilizers. We set an optimal control problem where we aim at maximizing the cereal output and meanwhile minimizing pollution effects. We solve theoretically this optimal control problem with the Pontryagin Maximum Principle and then provide different numerical methods to implement it: indirect methods based on the shooting method and direct methods based on a combination of AMPL with IPOPT. Mathematics Subject Classification (2010) 49K15 · 49M25 · 49J15 Statement of the ProblemIn a cereal field, consider x(t), t ∈ [0, T ] the rate of pollution at time t . In the absence of fertilizers, the rate of pollution x(t) is naturally (slowly) decreasing. Let α denote the natural decreasing rate. We assume that, in the absence of fertilizers, x(t) is evolving accordinġAdding fertilizers to the cereal field is a usual way in order to increase the cereal output, however it causes pollution. Denoting by u(t), t ∈ [0, T ], the rate of fertilizers, we assume that the evolution of the pollution rate x(t) is given bẏ(1) N. Moussouni ( ) · M. Aidene

In this work, we have modelled the problem of maximizing the velocity of a rocket moving with a rectilinear motion by a linear optimal control problem, where the control represents the action of the pilot on the rocket. In order to solve the obtained model, we applied both analytical and numerical methods. The analytical solution is calculated using the Pontryagin maximum principle while the approximate solution of the problem is found using the shooting method as well as two techniques of discretization: the technique using the Cauchy formula and the one using the Euler formula. In order to compare the different methods, we developed an implementation with MATLAB and presented some simulation results.

In this paper, we study a modelization of the evolution of cereal output production, controlled by adding fertilizers and in presence of locusts, then by adding insecticides. The aim is to maximize the cereal output and meanwhile minimize pollution caused by adding fertilizers and insecticides. The optimal control problem obtained is solved theoretically by using the Pontryagin Maximum Principle, and then numerically with shooting method.

In this work, we have proposed a new approach for solving the linear-quadratic optimal control problem, where the quality criterion is a quadratic function, which can be convex or non-convex. In this approach, we transform the continuous optimal control problem into a quadratic optimization problem using the Cauchy discretization technique, then we solve it with the active-set method. In order to study the efficiency and the accuracy of the proposed approach, we developed an implementation with MATLAB, and we performed numerical experiments on several convex and non-convex linearquadratic optimal control problems. The obtained simulation results show that our method is more accurate and more efficient than the method using the classical Euler discretization technique. Furthermore, it was shown that our method fastly converges to the optimal control of the continuous problem found analytically using the Pontryagin's maximum principle.

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