9 research outputs found
An optimal control-based numerical method for scalar transmission problems with sign-changing coefficients
No full textInternational audienceIn this work, we present a new numerical method for solving the scalar transmission problem with sign-changing coefficients. In electromagnetism, such a transmission problem can occur if the domain of interest is made of a classical dielectric material and a metal or a metamaterial, with for instance an electric permittivity that is strictly negative in the metal or metamaterial. The method is based on an optimal control reformulation of the problem. Contrary to other existing approaches, the convergence of this method is proved without any restrictive condition. In particular, no condition is imposed on the a priori regularity of the solution to the problem, and no condition is imposed on the meshes, other than that they fit with the interface between the two media. Our results are illustrated by some (2D) numerical experiments
Optimal control problem in treatment strategies for breast tumors
No full textIn this work, we present an optimal control problem under state constraints for breast cancer treatment by chemotherapy. In this instance, the drug dosage is considered as a control variable. Since chemotherapeutic agents affect both tumor cells and healthy cells, the main goal of the control problem is to minimize the evolution of tumor cells with less possible damage to the normal tissue. A system of nonlinear reaction-diffusion equations is used to describe the drug concentration in the tumor cells. The optimal control problem is formulated by specifying a performance criterion and different kinds of constraints, and the necessary optimality conditions are investigated. Afterward, numerical simulations with realistic data are presented and discussed to demonstrate the importance of suggesting optimal control strategies for tumor cell dynamics and eradication. Finally, the conclusion and the future perspectives are presented
A Penalization Approach in Breast Cancer Chemotherapy: Preliminary Numerical Simulations
No full textIn this paper, we discuss preliminary numerical simulation results that stem from an optimal control problem in breast cancer chemotherapy. The objective of this control problem is to minimize the growth of tumor cells while minimizing damage to normal tissue, considering that chemotherapeutic agents affect both tumor cells and healthy cells. The control variable is drug concentration, and the state variable is the tumor density in the breast. We first formulate the optimal control problem by specifying a performance criterion and various constraints and then investigate the necessary optimality conditions. Next, we present an optimization algorithm for solving the control problem. Finally, we present and discuss numerical simulations to demonstrate the importance of the suggested optimal control strategy for tumor cell eradication
Characterization of the fluctuations of an ultrasonic wave passing through a complex environment in order to simplify the modeling
No full textUltrasonic nondestructive testing, also called ultrasonic NDT, is a method for characterizing the thickness or internal structure of material using high-frequency acoustic waves. This technique consists in emitting an ultrasound within the object and detecting the echoes produced by the possible defects. In complex environments, in particular for certain metals, composite materials and concretes, ultrasonic waves are strongly disturbed by the material through which they propagate, which can distort measurements. Modeling these phenomena can help designing control procedures and improving their signal to noise ratio. Because simulation using finite-element methods can be computationally prohibitive, it is important to develop alternative and lighter approaches. In this report, we model these fluctuations in the same manner as dynamic speckle sequences, using stochastic processes. These methods have parameters that we fit with respect to the simulations generated by the CEA
Characterization of the fluctuations of an ultrasonic wave passing through a complex environment in order to simplify the modeling
No full textUltrasonic nondestructive testing, also called ultrasonic NDT, is a method for characterizing the thickness or internal structure of material using high-frequency acoustic waves. This technique consists in emitting an ultrasound within the object and detecting the echoes produced by the possible defects. In complex environments, in particular for certain metals, composite materials and concretes, ultrasonic waves are strongly disturbed by the material through which they propagate, which can distort measurements. Modeling these phenomena can help designing control procedures and improving their signal to noise ratio. Because simulation using finite-element methods can be computationally prohibitive, it is important to develop alternative and lighter approaches. In this report, we model these fluctuations in the same manner as dynamic speckle sequences, using stochastic processes. These methods have parameters that we fit with respect to the simulations generated by the CEA
Characterization of the fluctuations of an ultrasonic wave passing through a complex environment in order to simplify the modeling
No full textUltrasonic nondestructive testing, also called ultrasonic NDT, is a method for characterizing the thickness or internal structure of material using high-frequency acoustic waves. This technique consists in emitting an ultrasound within the object and detecting the echoes produced by the possible defects. In complex environments, in particular for certain metals, composite materials and concretes, ultrasonic waves are strongly disturbed by the material through which they propagate, which can distort measurements. Modeling these phenomena can help designing control procedures and improving their signal to noise ratio. Because simulation using finite-element methods can be computationally prohibitive, it is important to develop alternative and lighter approaches. In this report, we model these fluctuations in the same manner as dynamic speckle sequences, using stochastic processes. These methods have parameters that we fit with respect to the simulations generated by the CEA
Characterization of the fluctuations of an ultrasonic wave passing through a complex environment in order to simplify the modeling
No full textUltrasonic nondestructive testing, also called ultrasonic NDT, is a method for characterizing the thickness or internal structure of material using high-frequency acoustic waves. This technique consists in emitting an ultrasound within the object and detecting the echoes produced by the possible defects. In complex environments, in particular for certain metals, composite materials and concretes, ultrasonic waves are strongly disturbed by the material through which they propagate, which can distort measurements. Modeling these phenomena can help designing control procedures and improving their signal to noise ratio. Because simulation using finite-element methods can be computationally prohibitive, it is important to develop alternative and lighter approaches. In this report, we model these fluctuations in the same manner as dynamic speckle sequences, using stochastic processes. These methods have parameters that we fit with respect to the simulations generated by the CEA
Characterization of the fluctuations of an ultrasonic wave passing through a complex environment in order to simplify the modeling
No full textUltrasonic nondestructive testing, also called ultrasonic NDT, is a method for characterizing the thickness or internal structure of material using high-frequency acoustic waves. This technique consists in emitting an ultrasound within the object and detecting the echoes produced by the possible defects. In complex environments, in particular for certain metals, composite materials and concretes, ultrasonic waves are strongly disturbed by the material through which they propagate, which can distort measurements. Modeling these phenomena can help designing control procedures and improving their signal to noise ratio. Because simulation using finite-element methods can be computationally prohibitive, it is important to develop alternative and lighter approaches. In this report, we model these fluctuations in the same manner as dynamic speckle sequences, using stochastic processes. These methods have parameters that we fit with respect to the simulations generated by the CEA
Characterization of the fluctuations of an ultrasonic wave passing through a complex environment in order to simplify the modeling
No full textUltrasonic nondestructive testing, also called ultrasonic NDT, is a method for characterizing the thickness or internal structure of material using high-frequency acoustic waves. This technique consists in emitting an ultrasound within the object and detecting the echoes produced by the possible defects. In complex environments, in particular for certain metals, composite materials and concretes, ultrasonic waves are strongly disturbed by the material through which they propagate, which can distort measurements. Modeling these phenomena can help designing control procedures and improving their signal to noise ratio. Because simulation using finite-element methods can be computationally prohibitive, it is important to develop alternative and lighter approaches. In this report, we model these fluctuations in the same manner as dynamic speckle sequences, using stochastic processes. These methods have parameters that we fit with respect to the simulations generated by the CEA
