Organizatori

• Prof. dr. Dumitrel Ghiba
• CS.II. dr. Adina Ciomaga
• Lect. dr. Alexandra Melnig

Programul seminarului

Joi 29 ianuarie 2026, ora 11:00 (Sala de Conferinţe a Facultăţii de Matematică)

• Dr. Trung Hieu GIANG, Faculty of Mathematics and Physics, Charles University, Prague, Czech Republic; and Institute of Mathematics, Vietnam Academy of Science and Technology, Hanoi, Vietnam An improved existence theorem for rigid nonlinearly elastic plates.

Abstract: A plate is rigid if its admissible displacement fields inducing vanishing two-dimensional strain tensors must vanish. We prove that the nonlinear model of Kirchhoff-Love for such a plate has a solution for any applied forces and boundary conditions. Then, we give sufficient conditions on the data ensuring the rigidity of the plate. Together, these results substantially generalize an existence theorem by Rabier where the plate is assumed to be clamped on its entire boundary. This is a joint work with Cristinel Mardare.

Joi 8 ianuarie 2026, ora 11:00 (Sala de Conferinţe a Facultăţii de Matematică)

• Drd. Diana Elena MIRCIU, University of Klagenfurt, Austria Abordarea zgomotului neaditiv în probleme inverse.

Abstract: Problemele inverse urmăresc identificarea cauzelor pe baza efectelor observate şi sunt adesea sensibile la erori în date, astfel încât soluţia nu depinde continuu de măsurători, fiind necesare tehnici de regularizare pentru a obţine o aproximare stabilă a acesteia. Vom prezenta rezultate recente privind estimarea erorii pentru anumite metode variaţionale de regularizare, folosind distanţe Bregman, în situaţia în care datele sunt perturbate de zgomot neaditiv. Partea a doua abordează metode iterative de regularizare, precum algoritmii Primal–Dual Hybrid Gradient (PDHG) şi Condat–Vu, potriviţi pentru probleme de optimizare nenetede, şi evidenţiază rezultate noi privind ratele de convergenţă ale acestora în prezenţa datelor perturbate de zgomot.

Vineri 5 decembrie 2025, ora 14:00 (Sala de Conferinţe a Facultăţii de Matematică)

• Dr. Mihai-Cosmin PAVEL, Institutul de matematică "Simion Stoilow" al Academiei Române, IMAR Projectivity of moduli spaces of vector bundles.

Abstract: This talk begins with an introduction to the study of moduli spaces of vector bundles on a given complex projective manifold. A remarkable feature of these moduli spaces is that they are often endowed with a rich geometric structure (projective, Kähler, etc.), closely related to that of the underlying manifold. We then present two approaches to constructing such moduli spaces. The first one is classical and relies on Geometric Invariant Theory (GIT), which endows the moduli space with a projective structure. However, there are many situations where GIT methods are not applicable, such as those arising in the theory of Bridgeland stability. For these cases, we describe a more general stack-theoretic construction, which does not necessarily guarantee the projectivity of the resulting moduli spaces. Finally, we discuss how this projectivity issue can be addressed in two concrete examples, one based on joint work with M. Toma and the other on joint work with T. Tajakka.

Luni 24 noiembrie 2025, ora 12:00 (Sala de Conferinţe a Facultăţii de Matematică)

• Prof. univ. dr. Ionel Rovenţa, Facultatea de Matematică-Universitatea din Craiova The approximation of boundary controls for wave equation via moments problem and Ingham's inequality.

Abstract: The controllability theory of dynamical systems was, in the last decades, a very active field due from one side to its useful industrial applications and from the other side to the new and important specific mathematical advances. There exists a close relation between the control theory and the calculus of variations and optimization, many of its problems having equivalent formulations consisting of minimization of some functionals. Presently, the problems have an increased difficulty due to the complexity of the systems or controls and the necessity to offer concrete implementation and numerical approximations.

Vineri 13 iunie 2025, ora 13:00 (Sala de Conferinţe a Facultăţii de Matematică)

• Conf. univ. dr. Ionuţ Munteanu, Facultatea de Matematică-UAIC, IMOM Observer design for parabolic-type equations in 2-D and 3-D.

Abstract: We will consider evolution equations governed by second-order linear differential operators that can be diagonalized via an extension of the Sturm-Liouville theory from the 1-D case to the 2-D and 3-D cases. The boundary stabilizing controller is constructed via a finite-dimensional observer that includes $M$ interior measurements. The spectral reduction method is used, and a proportional control design is employed.

Vineri 30 mai 2025, ora 14:30 (Amfiteatrul Al. Myller)

• Cristinel MARDARE, Sorbonne Universite, Paris, Franţa Rigidity estimates for mappings with applications in nonlinear elasticity.

Abstract: A classical theorem of Liouville about mappings from an Euclidean space into itself states that if such a mapping is sufficiently smooth and its gradient is a field of orthogonal matrices, then the mapping is necessarily affine. A quantitative version of this theorem, due to Friesecke, James & Muller, states that the W^1,p(Ω)-distance, 1 < p < +∞, between a mapping u : Ω -> Rⁿ and the set of all affine mappings from Ω into Rⁿ is bounded above by the L^p-distance between the gradient field ∇u : Ω -> R^n×n and the set of all matrix fields from Ω into the set of special orthogonal matrices of order n.

We will discuss the applications of this result in nonlinear elasticity.

Marţi 1 aprilie 2025, ora 10:00 (Sala de Conferinţe a Facultăţii de Matematică)

• Olivier Ley, INSA Rennes, FranţaNonlocal Hamilton-Jacobi equations on networks.

Abstract: There are a lot of recent developments about nonlinear, first-order PDEs of Hamilton-Jacobi type on networks. In this context, I will present some joint work with Guy Barles (Tours) and Erwin Topp (Rio), in which we study the well-posedness of nonlocal Hamilton-Jacobi equations on networks, with Kirchhof conditions at the vertices. We are able to deal with integro-differential with order, strictly less than one. I will explain how we define solutions of such equations on a network, how we construct them, and how we extend an approach of Lions & Souganidis to prove uniqueness.

Vineri 14 martie 2025, ora 14:00 (Amfiteatrul Al. Myller)

• Liviu IGNAT, IMAR Bucureşti, Approximations of the best constants.

Abstract: In this talk we consider some well known quotients related with either eigenvalue problems, Sobolev or Hardy’s inequality. We consider the infimum of these quotients and their discrete analogous in a finite element subspace. We estimate the difference between the best constants above as the discretization parameter goes to zero and obtain sharp convergence rates.