# Institute annual report 2020

(version of December 22, 2020)

## Human resources

The Numerical Analysis and Approximation Theory workgroup:

- Dr. Emil
**Cătinaş**(workgroup coordinator) - Prof. Dr. Octavian
**Agratini** - Dr. Diana
**Otrocol** - Dr. Flavius
**Pătrulescu** - Dr. Mihai
**Nechita** - Imre
**Boros** - Dr. Cristian-Daniel
**Alecsa**

The Numerical Modeling workgroup:

- Dr. Călin-Ioan
**Gheorghiu**(workgroup coordinator) - Dr. rer. nat. habil. Nicolae
**Suciu** - Dr. Maria
**Crăciun**

## PhD advisors

- Dr. rer. nat. habil. Nicolae
**Suciu**supervises PhD theses.

He has recently supervised the thesis*Filtered density functions for uncertainty assessment of transport in groundwater*, by Lennart Schüler, defended on September 8, 2016, at Jena University, Germany; the thesis received the distinction*Magna Cum Laudae*. - Prof. dr. Ion
**Păvăloiu**, honorary member, has supervised -in the past- 8 PhD theses at North University of Baia-Mare and at Babeş-Bolyai University. - Prof. dr. Octavian
**Agratini**, who supervises PhD theses at Babes-Bolyai University.

## Papers published in 2020 in JCR/ISI indexed journals:

**Papers in JCR journals from abroad**

- C.D. Alecsa, I. Boros, F. Frank, P. Knabner, M. Nechita, A. Prechtel, A. Rupp, N. Suciu,
*Numerical benchmark study for flow in highly heterogeneous aquifers*, Adv. Water Res., 138 (2020), 103558. Impact Factor (IF) 2019:**4.01** - C.D. Alecsa, T. Pinţa, I. Boros,
*New optimization algorithms for neural network training using operator splitting techniques*, Neural Networks, 126 (2020), 178-190. doi: 10.1016/j.neunet.2020.03.018 IF 2019:**5.53** - E. Burman, M. Nechita, L. Oksanen,
*A stabilized finite element method for inverse problems subject to the convection-diffusion equation. I: diffusion-dominated regime*, Numer. Math. 144 (2020), pp. 451-477 IF 2019:**2.05** - M. Crăciun, T. Harko,
*Testing Bose-Einstein condensate dark matter models with the SPARC galactic rotation curves data*, The European Physical Journal C, 80 (2020) 8, 735, 1-28,**IF 2019: 4.3** - C.-D. Alecsa, S.C. László, A. Viorel,
*A gradient-type algorithm with backward inertial steps associated to a nonconvex minimization problem*, Numer. Algor. 84 (2020), pp. 485-512. - F. Pătrulescu, T. Groşan, I. Pop,
*Natural convection from a vertical plate embedded in a non-Darcy bidisperse porous medium*, ASME-Journal of Heat Transfer 142(1): 012504, HT-19-1097 (2020), (11 pages) - V. Ilea, A. Novac, D. Otrocol, R. Precup,
*Solutions with a prescribed interval of positivity for differential systems with nonlocal conditions*, Appl. Math. Comput., 375 (2020), doi: 10.1016/j.amc.2020.125092 - V. Ilea, D. Otrocol,
*Existence and uniqueness of the solution for an integral equation with supremum, via w-distances*, Symmetry 2020, 12, 1554, https://doi.org/10.3390/sym12091554 - O. Agratini,
*Linear positive operators constructed by using Beta-type bases*, Hacettepe Journal of Mathematics & Statistics, 49 (2020) no. 3, pp. 1030-1038, doi: 10.15672/hujms.549015 - C. I. Gheorghiu,
*Spectral collocation based on quasi-classical orthogonal polynomials applied to solve a singular BVP from hydrodynamics*, AIP Conference Proceedings 2293, 100004 (2020); https://doi.org/10.1063/5.0026783 - A.M. Acu, A. Maduta, D. Otrocol, I. Raşa,
*Inequalities for information potentials and entropies*, Mathematics 2020, 8(11), 2056; https://doi.org/10.3390/math8112056

**Papers in JCR journals from Romania**

- O. Agratini,
*Modifying an approximation process using non-Newtonian calculus*, Stud. Univ. Babes-Bolyai Math. 65 (2020) no. 2, 291–301, doi: 10.24193/subbmath.2020.2.10 - V. Ilea, D. Otrocol,
*On the Burton method of progressive contractions for Volterra integral equations*, Fixed Point Theory, 21 (2020) no. 2, 585-594.

## Papers published in other journals

- T. Cătinaș, D. Otrocol,
*Iterates of Cheney-Sharma type operators on a triangle with curved side*, J. Comp. Anal. Appl., 28 (2020) no. 4, pp. 737-744. - O. Agratini,
*A stop over Jain operators and their generalizations*, Annals of West University of Timisoara – Mathematics and Computer Science, 56 (2018) no. 2, pp. 28-42.

## Prizes

- M. Nechita,
*Sir George Jessel studentship*, University College London (february 2020).

## Papers accepted and published online in JCR/ISI journals [with coordinates to follow in 2021]

## Preprints in Arxiv

- C. I. Gheorghiu,
*Accurate spectral collocation computation of high order eigenvalues for singular Schroedinger equations.*arXiv/3486226[math-ph] - C. I. Gheorghiu,
*Accurate spectral collocation solutions to some Bratu’s type Boundary Value Problems*. arXiv/3486209[math.NA] - C. I. Gheorghiu,
*Spectral collocation solutions to second order singular Sturm-Liouville eigenproblems*, arXiv/ 3484569[math.NA] - C.D. Alecsa, I. Boros, F. Frank, P. Knabner, M. Nechita, A. Prechtel, A. Rupp, N. Suciu,
*Benchmark for numerical solutions of flow in heterogeneous groundwater formations*, arxiv 1911.10774. - E. Burma, M. Nechita, L. Oksanen,
*A stabilized finite element method for inverse problems subject to the convection-diffusion equation. II: convection-dominated regime*, 2020., arXiv:2006.13201

## Papers accepted

- N. Suciu,
*Global random walk solutions for flow in porous media*, accepted paper, ENUMATH 2019 Proceedings, to apear (Springer)

### Posts in notable repositories

- C. I. Gheorghiu
*, A third-order nonlinear BVP on the half-line*, January 2020, https://www.chebfun.org/examples/ode-nonlin/GulfStream.html

## Members of Editorial Boards

- Studia UBB Math.: O. Agratini (senior Editor)
- J. Numer. Anal. Approx. Theory: O. Agratini (Editor-in-Chief), E. Catinas (Editor-in-Chief), D. Otrocol, M. Nechita, I. Boros
- ROMAI Journal: N. Suciu, C.I. Gheorghiu
- Mathematica (Cluj): O. Agratini
- Open Journal of Discrete Mathematics: O. Agratini
- J. Science and Arts: O. Agratini

## Conferences organized

–

## Conferences attended by the members of the Institute

**International conferences**

- C.D. Alecsa, I. Boros, F. Frank, P. Knabner, M. Nechita, A. Prechtel, A. Rupp, N. Suciu, D443:
*Numerical benchmark study for flow in highly heterogeneous aquifers*, EGU General Assembly 2020 – Sharing Geoscience Online, https://doi.org/10.5194/egusphere-egu2020-10504 - O. Agratini,
*Using the sequences of linear operators to approximate signals*, The 2nd International Conference on Mathematics and Computers in Science and Engineering, MACISE 2020, Madrid, Spain, January 18-20, 2020. https://www.macise.org/#Plenary - S.C. Laszlo, C.D. Alecsa, T. Pinta,
*An extension of the second order dynamical system that models Nesterov’s convex gradient method*, Games, Dynamics and Optimization (GDO2020), Rome, Italy, February 24-26, 2020.

National conferences

–

**Grants**

- International grant SU 415/4-1 (https://gepris.dfg.de/gepris/projekt/405338726) obtained by dr. rer. habil. N. Suciu from (Deutschefourschungs Gmemeindschaft), for the project
*“Integrated global random walk model for reactive transport in groundwater adapted to measurement spatio-temporal scales”*(01.10.2018-30.09.2021), in progress at Erlangen-Nuernberg University.