Project's information

Project's title Direct, inverse and optimal control problems for new classes of fractional differential equations
Project’s code QTRU01.01/21-22
Research hosting institution Institute of Mathematics
Coordinating unit, co-chair Chelyabinsk State University, Russia
Project leader’s name Bui Trong Kien and Vladimir Evgenyevich Fedorov
Project duration 01/06/2021 - 30/06/2023
Project’s budget 200 million VND
Classify Excellent
Goal and objectives of the project
Focus on  qualitative study for direct problems, inverse problems and optimal control problems giverned by fractional differential equations
Main results
Research results:
a) Initial value problems for some classes of linear evolution equation with several fractional derivatives
We proved the existence and uniqueness of solutions to the  initial problems for linear inhomogeneous equations of a general form with several Gerasimov–Caputo fractional derivatives in Banach spaces.  The obtained  results are applied to the study of a class of initial-boundary value problems for equations with several Gerasimov–Caputo time derivatives and with polynomials with respect to a self-adjoint elliptic differential operator in space variables.
b) Distributed control for semilinear equations with Gerasimov–Caputo fractional derivatives
We consider the optimal control problem for semilinear evolution equations where  the higher fractional derivative are presented via  lower fractional derivatives. The operator depends on the Gerasimov–Caputo fractional derivatives of lower orders is nonlinear. We then prove the existence of an  optimal control under a weaker condition of uniform in time local Lipschitz continuity with respect to the phase variables of the nonlinear operator, instead of the condition of its Lipschitz continuity. 
c) Linear inverse problems for multi-term equations with Riemann — Liouville derivatives
We consider the well-posedness of linear inverse coefficient problems for
multi-term equations in Banach spaces with fractional Riemann – Liouville derivatives and with bounded operators. We then gave some criteria on the well-posedness for the problem.  
d) Optimal control problem governed by fractional differential equations with control constraints
We proved the existence of optimal solutions and established first-and second-order optimality conditions for the problem. Besides, we showed that if the state equation is linear, then the optimal solutions are Holder continuous. 
 
Education and tranining result: Nguyen Quoc Tuan who is a member of the project and a PhD student of the Institute of Mathematics,  completed his doctoral thesis. He will defend his thesis  in 2024.  
 
Cooperation result:  establised a good relationship on  research coopertions with  professor V.E. Fedorov’s group of the Department of Mathematics, Chelyabinsk State University. 
Novelty and actuality and scientific meaningfulness of the results

Give a new result on the existence of solution to a class of evolution equation with fractional derivatives in Banach spaces
Give new results on the existence of optimal solutions and optimality conditions to the optimal control problems governed by  differential equations with fractional order.
 Give  some criteria on the well-posedness of the linear inverse coefficient problem for multi-term equations in Banach spaces with fractional Riemann – Liouville derivatives. 

Products of the project

List of pulications related to the project.
 1. M. M. Turov1, V. E. Fedorov and  B. T. Kien, Linear inverse problems for multi-term equations with Riemann — Liouville derivatives, УДК 518.517 MSC 35R30, 35R11, 34G10,  DOI https://doi.org/10.26516/1997-7670.2021.38.36
2.  B. T. Kien,  V. E. Fedorov and T. D. Phuong,  Optimal control problems governed by fractional differential equations with control constraints, SIAM J. Control Optim., Vol. 60, No. 3, pp. 1732-1762, 2022. 

Recommendations

The project is completed on time. The obtaned results meet  demands  of the  objective and research contents of the project.  Some research contents of the project are  continued to studty in the near future.  
Thank to the project, we improved and extended our research area in mathematics. So we wish that Vietnam Academy of Science and Technology continues to support such  projects with more funds.