Dr. Cristian-Daniel **Alecsa**

(former researcher at ICTP, between 2017-2021)

This website contains information which is no longer updated

Dr. Cristian-Daniel **Alecsa**

(former researcher at ICTP, between 2017-2021)

This website contains information which is no longer updated

- cristian.alecsa[at]ictp.acad.ro
- Publons Profile

ResearcherID

**Former position****:**

Research Assistant at *Tiberiu Popoviciu Institute of Numerical Analysis*

Postdoc, *Romanian Institute for Science and Technology*

**Research domains:**

- Optimization Methods for Machine Learning
- Data Science Techniques
- Scientific Computing & Numerical Algorithms
- Mathematical Modeling

**Personal Data**

Date and place of birth : 15.03.1990, Săveni, Botoșani

**Educational Background**

2005 – 2009 : High School „Dr. Mihai Ciucă”, Săveni, section Mathematics – Computer Science

2010 – 2013 : Faculty of Mathematics and Computer Science, “Babeş-Bolyai” University, Cluj-Napoca

2013 – 2015 : Master Studies at Faculty of Mathematics and Computer Science, “Babeş-Bolyai” University, Cluj-Napoca, field Applied Mathematics;

2015 – 2019 : Doctoral Studies at Faculty of Mathematics and Computer Science, “Babeş-Bolyai” University, Cluj-Napoca, field *Nonlinear Operators and Differential Equations*

**Employment Experience**

**3 February 2020 – ?**: Machine Learning Researcher at Romanian Institute of Science and Technology (RIST) : Postdoc position for the”DeepRiemann” project entitled “Riemannian Optimization Methods for Deep Learning” – funded European Regional Development Fund and the Romanian Government through the Competitiveness Operational Program 2014-2020

**1 January 2017 – January 2021**: Assistant Researcher at Tiberiu Popoviciu Institute of Numerical Analysis (ICTP), Romanian Academy, Cluj-Napoca, Romania

**3 July 2019 – 23 December 2019** : Machine Learning Engineer at EspresSoft-Tech SRL, Cluj-Napoca, Romania

**Conferences and Workshops **

- 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. - Interdisciplinary Conference for Phd Students, Baru Mare, Hunedoara, 3-5 June 2016
- Student Scientific Session, Phd Students, Cluj-Napoca, 31 May 2016
- Student Scientific Session, Phd Students, Cluj-Napoca, 6 June 2017
- Numerical Analysis, Approximation and Modeling (Symposium), Cluj-Napoca, 14 June 2017
- Național Session of Mathematics Scientific Communications, Iași, 6-9 July 2017
- Weekly Seminars at ‘Tiberiu Popoviciu’ Institute of Numerical Analysis, 2017
- PhD Scientific Reports at ‘Nonlinear Operators and Differential Equations’ Research Group, UBB, 2015-present

**Teaching Experience**

http://www.cs.ubbcluj.ro/files/orar/2015-1/cadre/alcc.html

Seminar – Basic Mathematics – first semester, 2015/2016, Mathematics for Computer Science (teaching in Romanian), Undergraduate (for 1st and 2nd year students)

Seminar – Differential Equations – first semester, 2015/2016, Mathematics (teaching in Romanian), Undergraduate (for 2nd year students)

Lab – Differential Equations – first semester, 2015/2016, Mathematics (teaching in Romanian), Undergraduate (for 2nd year students)

http://www.cs.ubbcluj.ro/files/orar/2015-2/cadre/alcc.html

Seminar – Special Topics of Differential Equations – second semester, 2015/2016, Mathematics and Mathematics for Computer Science (teaching in Romanian), Undergraduate (for 2nd year students)

Lab – Dynamical Systems – second semester, 2015/2016, Computer Science (teaching in English), Undergraduate (for 2nd year students)

http://www.cs.ubbcluj.ro/files/orar/2016-1/cadre/alcc.html

Lab – Probability and Statistics – first semester, 2016/2017, Computer Science (teaching in Romanian), Undergraduate (for 2nd year students)

Lab – Probability and Statistics – first semester, 2016/2017, Computer Science (teaching in English), Undergraduate (for 2nd year students)

Seminar – Differential Equations – first semester, 2016/2017, Mathematics (teaching in Romanian), Undergraduate (for 2nd year students)

Lab – Differential Equations – first semester, 2016/2017, Mathematics (teaching in Romanian), Undergraduate (for 2nd year students)

http://www.cs.ubbcluj.ro/files/orar/2016-2/cadre/alcc.html

Lab – Numerical Calculus – second semester, 2016/2017, Computer Science (teaching in English), Undergraduate (for 3rd year students)

Lab – Numerical Analysis – second semester, 2016/2017, Mathematics (teaching in Romanian), Undergraduate (for 2nd year students)

Lab – Dynamical Systems – second semester, 2016/2017, Computer Science (teaching in English), Undergraduate (for 1st year students)

http://www.cs.ubbcluj.ro/files/orar/2017-1/cadre/alcc.html

Lab – Mathematical Statistics – first semester, 2017/2018, Mathematics for Computer Science (teaching în Romanian), Undergraduate (for 3rd year students)

Seminar – Differential Equations – first semester, 2017/2018, Mathematics (teaching in Romanian), Undergraduate (for 2nd year students)

Seminar – Differential Equations – first semester, 2017/2018, Mathematics for Computer Science (teaching in Romanian), Undergraduate (for 2nd year students)

http://www.cs.ubbcluj.ro/files/orar/2017-2/cadre/alcc.html

Seminar – Dynamical Systems – second semester, 2017/2018, Computer Science (teaching in Romanian), Undergraduate (for 1st year students)

**Computer experience**

Programming languages: Matlab, C, C++, Maple, HTML, CSS, JQuery

Word-processing languages: LaTeX, Scientific Work Place, Beamer

**Languages **

English

- A. Viorel, C.D. Alecsa, T.O. Pinţa,
*Asymptotic analysis of a structure-preserving integrator for damped Hamiltonian systems*, Discrete & Continuous Dynamical Systems, 41 (7), 3319-3341, doi: 10.3934/dcds.2020407 - C.D. Alecsa, S.C. László, T. Pinţa,
*An extension of the second order dynamical system that models Nesterov’s convex gradient method*, Appl. Math. Optim. (2020). doi: 10.1007/s00245-020-09692-1 - 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. - 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 - 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 - C.-D. Alecsa,
*The long time behavior and the rate of convergence of symplectic convex algorithms obtained via splitting discretizations of inertial damping systems*, arXiv:2001.10831 - C.D. Alecsa,
*Sequences of contractions on cone metric spaces over Banach algebras and applications to nonlinear systems of equations and systems of differential equations*, International Journal of Nonlinear Analysis and Applications, 10, 2, 2019, 227-254. doi: 10.22075/ijnaa.2019.18884.2040 - 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. - V. Moisoiu, A. Stefancu, S. D. Iancu, T. Moisoiu, L. Loga, L. Dican, C. D. Alecsa, I. Boros, A. Jurj, D. Dima, C. Bagacean, R. Tetean, E. Burzo, C. Tomuleasa, F. Elec, N. Leopold,
*SERS assessment of the cancer-specific methylation pattern of genomic DNA: towards the detection of acute myeloid leukemia in patients undergoing hematopoietic stem cell transplantation*, Anal. Bioanal. Chem. 411 (2019) no. 29, pp. 7907–7913. (doi: 10.1007/s00216-019-02213-2) - C.D. Alecsa,
*Common fixed points for Presic operators via simulation functions*, J. Nonlin. Conv. Analysis, 20 (2019) no. 3, 363-377. - V. Moisoiu, A. Socaciu, A. Stefancu, S. D. Iancu, I. Boros, C. Alecsa, C. Rachieriu, A. R. Chiorean, D. Eniu, N. Leopold, C. Socaciu, D. Eniu,
*Breast cancer diagnosis by surface-enhanced Raman scattering (SERS) of urine*, Appl. Sci.,**9**(2019) no. 4, 806. - C. D. Alecsa,
*Approximating fixed points for nonlinear generalized mappings using Ishikawa iteration*, Rend. Circ. Mat. Palermo, II. Ser. 68 (2011) 1, pp. 163-191 - C.D. Alecsa,
*Some fixed point results linked to α − β rational contractions and modified multivalued Hardy-Rogers operators*, J. Fixed Point Theory, 2018, 2018:3 - C.D. Alecsa,
*Some fixed point results regarding convex contractions of Presić type*, J. Fixed Point Theory Appl. (2018) 20: 7. - C.D. Alecsa,
*Fixed point theorems for generalized contraction mappings on b-rectangular metric spaces*, Studia Universitatis Babeş-Bolyai Mathematica, 62 (2017) No. 4, 499-524 - C.D. Alecsa,
*Stability results and qualitative properties for Mann’s algorithm via admissible perturbations technique*, Applied Analysis and Optimization, 1 (2017) no. 2, 327-344 - C. Alecsa,
*On new faster fixed point iterative schemes for contraction operators and comparison of their rate of convergence in convex metric spaces*, Int. J. Nonlinear Anal. Appl. 8 (2017) No. 1, 353-388 - C.D. Alecsa, A. Petrusel,
*On some fixed point theorems for multi-valued operators by altering distance technique*, J. Nonlinear Var. Anal. 1 (2017), 237-251.

Postdoc position at Romanian Institute of Science and Technology – for the”DeepRiemann” project entitled “Riemannian Optimization Methods for Deep Learning” – funded European Regional Development Fund and the Romanian Government through the Competitiveness Operational Program 2014-2020

Research Assistant at the Technical University of Cluj-Napoca – national research grant “Research Projects for Young Independent Teams” PN-III-P1-1.1-TE-2016-0266, entitled “Optimizare neneteda, convexa si neconvexa, o abordare din perspectiva sistemelor dinamice” (in Romanian)

GitHub projects: https://github.com/CDAlecsa

Contributor to a Deep Learning library: https://github.com/rist-ro/argo

Research Internship at the Research Group on Applied Mathematics, Faculty of Mathematics, University of Vienna, 05.11.2019 – 12.11.2019

Updated June 26, 2021.

AbstractFlow and multicomponent reactive transport in saturated/unsaturated porous media are modeled by ensembles of computational particles moving on regular lattices according to specific random walk rules. The occupation number of…

Read More AbstractT. A. Burton presented in some examples of integral equations a notion of progressive contractions on C([a, ∞[). In 2019, I. A. Rus formalized this notion (I. A. Rus, Some…

Read More (original), (survey), Convergence orders, Fixed point theory, history, ISI/JCR, iterative methods, local convergence, Newton method, nonlinear equations in R, Numerical Analysis, paper, secant/chord method, successive approximations

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Abstract The high speed of \(x_{k}\rightarrow x^\ast\in{\mathbb R}\) is usually measured using the C-, Q- or R-orders: \begin{equation}\tag{$C$} \lim \frac {|x^\ast – x_{k+1}|}{|x^\ast – x_k|^{p_0}}\in(0,+\infty), \end{equation} \begin{equation}\tag{$Q$} \lim \frac {\ln…

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