Dr. Călin-Ioan **Gheorghiu**

## Academic degree:

Ph.D. in Mathematics (1984, Bucharest University, Mathematics and Mechanics Faculty)

### Current position:

Senior researcher at *Tiberiu Popoviciu Institute of Numerical Analysis*

Professor at “Lucian Blaga” University, Sibiu (between 1999-2010)

### Current research domains:

- Spectral methods (collocation, Galerkin, tau)
- Numerical analysis of dynamical systems
- Mathematical modeling of some physics-chemical hydrodynamical phenomena

### Past research activity:

- Finite element and finite differences type methods

### Scientific affiliation:

Elected vice-president of ROMAI, member of GAMM, EUROMECH, COST and scientific reviewer for Zentralblatt MATH zbMATH.

**Personal Data**

Date and place of birth | September 27, 1950, Alba-Iulia, Romania |

Citizenship | Romanian |

Nationality | Romanian |

ghcalin[at]ictp.acad.ro; cigheorghiu11[at]gmail.com | |

**Education and degrees**

1984 | Ph.D. in Mathematics Bucharest University, Faculty of Mathematics and Mechanics Scientific advisor: Acad. Caius Iacob Thesis: Finite Element Method in some Problems of Viscous Fluid Mechanics |

1973-1974 | Master of Science in Fluid Mechanics Babeş-Bolyai University, Faculty of Mathematics and Mechanics, Cluj-Napoca Scientific advisor: Prof. Dr. I. Stan Thesis: Numerical methods for establishing the concentration in flows involving chemical reactions over a rotating disk |

1969-1973 | Bachelor Degree, Mathematics Babeş-Bolyai University, Faculty of Mathematics and Mechanics, Cluj-Napoca |

1965-1969 | “Horia Cloşca şi Crişan” High School, Alba-Iulia |

**Further experiences and training**

September 2002 | Computer Simulation of Surfaces and Interfaces, NATO ASI, Varna, Bulgaria |

April 2001 | Complexity from Microscopic to Macroscopic Scales; Coherence and Large Deviations, NATO Advances Study Institute, Geilo, Norway |

March- April 1998 |
Visiting researcher at Oxford University, OCIAM & Computing Laboratory (Soros Scholarship), UK |

September- October 1996 |
Microlocal Analysis and Spectral Theory, NATO Advanced Study Institute Course, Univ. Torino, Italy |

September 1995 | Control of Flow Instabilities and Unsteady Flows, International Centre for Mechanical Sciences (CISM) Udine, Italy |

September 1990 | Variational Methods in Mechanics, Szombathely, Hungary |

September 1990 | Mathematical Modeling of Industrial Processes, SASIAM, Tecnopolis-Bari, Italy |

September 1987 | Non-Smooth Mechanics and Applications, International Centre for Mechanical Sciences (CISM) Udine, Italy |

September 1986 | Finite and Boundary Element Techniques from Mathematical and Engineering Point of View, International Centre for Mechanical Sciences (CISM) Udine, Italy |

**Employment history**

2014-present | Senior Researcher (I) at “Tiberiu Popoviciu” Institute of Numerical Analysis (ICTP), Romanian Academy |

1995-2013 | Senior Researcher (II) at ICTP |

1990-1995 | Senior Researcher (III) at ICTP |

1988-1990 | mathematician, Babeş-Bolyai University, Faculty of Mathematics |

1978-1988 | mathematician, Technical University Cluj-Napoca, Department of Civil Engineering and Computing Center |

1974-1978 | hydrologist, Institute of Meteorology and Hydrology, Bucharest, Cluj Sector |

**Courses in charge**

Feb. 08-Mar. 16 2010 | Visiting professor at Abdus Salam School of Mathematical Sciences (ASSMS) , Lahore, Pakistan, Numerical methods for nonlinear dynamical systems; Numerical analysis; MATLAB |

Jul. 01-Oct. 30 2008; Jul. 01- Sept. 20 2010 | Visiting professor at African University of Science and Technology, Abuja, Nigeria, Numerical methods for nonlinear dynamical systems; Numerical analysis; Partial differential equations; MATLAB |

1999-2010 | Professor at “L. Blaga” University, Sibiu, Numerical methods for dynamical systems; Differential equations |

Aug. 01-Oct. 20 2005 | Visiting professor at King Mongkut Institute of Technology, Ladkrabang, Bangkok, Thailand, Numerical methods for nonlinear dynamical systems; Numerical analysis |

Feb. 21-Jul. 05 2005 | Visiting professor at Nanjing University for Astronautics and Aeronautics, College of Sciences, Nanjing, China, Finite elements method; Numerical analysis |

Jun. 01-Sept. 30 1999 | Visiting professor at King Mongkut Institute of Technology, Ladkrabang, Bangkok, Thailand, Finite element and numerical modeling courses |

1998-1999 | Associate professor at Department of Mathematics, Technical University Cluj-Napoca , Mathematical analysis, Differential geometry |

Jun. 01-Sept. 30 1997 | Visiting professor at King Mongkut Institute of Technology, Ladkrabang, Bangkok, Thailand, Finite element and numerical analysis courses |

1995-1996 | Associate professor at Faculty of Mathematics and Computer Science, Babeş-Bolyai University, Numerical methods in hydrodynamics |

**Selected Meetings and Symposia**

- the annual meetings of
*Academic Days of Cluj*and*Conferences for Applied and Industrial Mathematics*ROMAI (former*Annual Colloquia of Fluid Mechanics and its Technical Applications*) - the meetings of GAMM (2), ECMI (1), ICM (1), Euromech Colloquia (2), ICIAM (1)
*The Eighth Congress of Romanian Mathematicians*, 2015, Iaşi, Romania

**Membership in professional societies**

*Geselltschaft fur Angewandte Mathematik und Mechanik*(GAMM), member*European Cooperation in Science and Technology*(COST), member*European Mechanics Society*(EUROMECH), member*Romanian Society of Industrial and Applied Mathematics*ROMAI-member, elected vice-president;*European Consortium for Mathematics in Industry*(ECMI), former member*Society of the Romanian Mathematicians*SSMR, member.

**Grants**

- 2-CEx06-11-96/19.09.2006-2008, MEC,
*Efficient numerical methods with applications on supercomputers*(participant) - 7037/2001/ , MEC,
*Numerical methods for dissipative dynamical systems*(coordinator) - 6100/13.10.2000, ANSTI,
*Numerical analysis of nonlinear parabolic dynamical systems*(coordinator) - 4122/1998-1999, MCT,
*Numerical methods for the qualitative study of some nonlinear dynamical systems*(coordinator) - GAR-29/1996,
*Numerical methods for the study of the eigenvalues of some bilocal problems. Applications in hydrodynamical stability and subcritical transition to turbulence*(coordinator)

**Other professional activities**

- Reviewer for: Zentralblatt fur Mathematik, Acta Applicandae Mathematicae (The Netherlands), Studia Universitatis “Babeş-Bolyai” Math. (Cluj-Napoca, Romania)
- Scientific evaluator for Umm Al-Qura University Journal of Science-Medicine-Engineering and for Permanent Committee for Academic Promotion, King Abdulaziz University (Saudi Arabia)
- Scientific reviewer for some ISI journals: HFF, Microfluidics and Nanofluidics (MANO), Applied Mathematics and Computation, Advances in Computation, APNUM, JOEMS, British Journal of Mathematics & Computer Science, ASME Journal of Computational and Nonlinear Dynamics, etc.

**Awards**

- “Simion Stoilow” award of Romanian Academy, for the monograph
*Finite Element Method and Applications*, Romanian Academy Publishing House, Bucharest, 1987 (with T. Petrila)

**Computer experience**

- Operating systems: Windows
- Programming languages: MATLAB, Fortran, Scientific Word (Latex), Power Point

**Languages**

- English, French, Russian

**Note:** the publications may be consulted as posts, clickable by author (e.g., C.I. Gheorghiu), category (either, e.g., (original), (survey), paper, book or mathematical field, e.g., global random walk, time series), tag (year: 2014), etc.

The processing of the information is in progress.

**Books:**

**Textbooks** (for students)

C.I. Gheorghiu, Amelia Bucur, *General Mathematics*, “Lucian Blaga” University Publishing House, Sibiu, 2001, 163 pp. ISBN 973-651-309-2 (Textbook in Romanian)

**Articles:**

- R. Precup, C.-I. Gheorghiu,
*Theory and computation of radial solutions for Neumann problems with φ-Laplacian*, Qualitative Theory of Dynamical Systems,**23**(, art. no. 107, https://doi.org/10.1007/s12346-024-00963-8 - C.I. Gheorghiu,
*Accurate Laguerre collocation solutions to a class of Emden–Fowler type BVP,*, - J. Rodriguez-Lopez, R. Precup, C.-I. Gheorghiu, On the localization and numerical computation of positive radial solutions for φ-Laplace equations in the annulus, Electronic Journal of Qualitative Theory of Differential Equations, 2022, no. 47, pp. 1-22, doi.org/10.14232/ejqtde.2022.1.47
- C.-I. Gheorghiu,
*Chebfun solutions to a class of 1D singular and nonlinear boundary value problems,*Computation, 10 (2022) no. 7, art. id. 116, http://doi.org/10.3390/computation10070116 - C.I. Gheorghiu,
*Accurate spectral collocation computations of high order eigenvalues for singular Schrödinger equations-revisited,*Symmetry,**13**(2021) 5, https://doi.org/10.3390/sym13050761

- C.I. Gheorghiu,
*Accurate spectral collocation solutions to 2nd-order Sturm–Liouville problems*, Symmetry, 13 (2021) 3, 385, doi: 10.3390/sym13030385 - C. I. Gheorghiu,
*Accurate spectral collocation computation of high order eigenvalues for singular Schrödinger equations,*Computation,**9**(2021) 2, 19 pp. https://doi.org/10.3390/computation9010002 - C. I. Gheorghiu,
*Accurate spectral collocation solutions to some Bratu’s type Boundary Value Problems*, arXiv:2011.13212 - C. I. Gheorghiu,
*Spectral collocation solutions to second order singular Sturm-Liouville eigenproblems*, Symmetry, 13 (2021) 3, doi: 10.3390/sym13030385 - 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 - C.I. Gheorghiu, B. Zinsou,
*Analytic vs. numerical solutions to a Sturm-Liouville transmission eigenproblem*, J. Numer. Anal. Approx. Theory, 48 (2019) no. 2, 159-174. - C.I. Gheorghiu,
*Spectral collocation solutions to a class of pseudo-parabolic equations*, G. Nikolov et al. (Eds.): NMA 2018, LNCS 11189, pp. 1–8, 2019. doi: 10.1007/978-3-030-10692-8_20 - C.I. Gheorghiu,
*On the numerical treatment of the eigenparameter dependent boundary conditions*, Numerical Algorithms,**77**(2018) no. 1, pp 77–93, DOI: 10.1007/s11075-017-0305-1 - C.I. Gheorghiu,
*Stable spectral collocation solutions to Cauchy problems for nonlinear dispersive wave equations*, Proceedings of the 4th Conference of Mathematical Society of Moldova (CMSM4), 2017, pp. 277-280. ISBN 978-9975-71-915-5 - J.P. Boyd, C.I. Gheorghiu,
*All roots spectral methods: Constraints, floating point arithmetic and root exclusion*, Applied Mathematics Letters 67 (2017) 28–32 DOI: 10.1016/j.aml.2016.11.015 (IF 2016:**2.233**) - C.I. Gheorghiu,
*Spectral collocation solutions to systems of boundary layer type*, Numer. Algor.,**73**(2016) no. 1, pp 1–14, doi: 10.1007/s11075-015-0083-6 - C.I. Gheorghiu,
*Stable spectral collocation solutions to a class of Benjamin Bona Mahony initial value problems.*Appl. Math. Comp.,**273**(2016) 1090-1099. (Impact factor 2014: 1.551) - B. Plestenjak, C.I. Gheorghiu, M.E. Hochstenbach,
*Spectral collocation for multiparameter eigenvalue problems arising from separable boundary value problems.*J. Comput. Phys.**298**(2015) 595-601. (Impact factor 2014: 2.434) - C.I. Gheorghiu,
*Pseudospectral solutions to some singular nonlinear BVPs. Applications in nonlinear mechanics.*Numer. Algor.,**68**(2015) 1-14. (Impact factor 2013: 1.042) - C.I. Gheorghiu,
*Laguerre collocation solutions vs. analytic results for singular semilinear BVPs on the half line,*ROMAI J.,**11**(2015), pp. 69-87. - C.I. Gheorghiu, C. Morosanu,
*Accurate spectral solutions to a phase-field transition system*, ROMAI J.,**10**(2014) 2, 1-11. - C.I. Gheorghiu,
*On the accuracy of pseudospectral differentiation.*ROMAI J.,**10**(2014) 1, 55-62. - C.I. Gheorghiu,
*Laguerre collocation solutions to boundary layer type problems*. Numer. Algor.,**64**(2013) 385-401. (Impact factor 2012: 1.042) - C.I. Gheorghiu, J. Rommes,
*Application of the Jacobi-Davidson method to accurate analysis of singular linear hydrodynamic stability problems*. Int. J. Numer. Meth. Fluids,**71**(2013) 358-369. (Impact factor 2012: 1.293) - C.I. Gheorghiu, M.E. Hochstenbach, B. Plestenjak, J. Rommes,
*Spectral collocation solutions to multiparameter Mathieu’s system,*Appl. Math. Comput.,**218**(2012) 11990-12000. (Impact factor 2011: 1.317) - I.F. Dragomirescu, C.I. Gheorghiu,
*Analytical and numerical solutions to an electrohydrodynamic stability problem*. Appl. Math. Comput.,**216**(2010) 3718-3727. (Impact Factor 2009: 1.124) - C.I. Gheorghiu, F.-I. Dragomirescu,
*Spectral methods in linear stability. Applications in thermal convection with variable gravity field*, Appl. Numer. Math.,**59**(2009) 1290-1302. (Impact Factor 2009: 1.207) - C.I. Gheorghiu,
*Accurate numerical solutions to stationary free surface problems from capillarity*, Phys. Part. Nuclei Lett., 5 (2008), 286-289. - C.I. Gheorghiu, A.C. Mureşan,
*On the long time energy conservation by high order geometric integrators*, PADEU,**19**(2007), 213-219. - C.I. Gheorghiu, A.C. Mureşan,
*On the accuracy of Stoermer/Verlet method as the numerical integrator of the n-body problem – Application to solar system*, Rom. Astron. J.,**16**(2006) 93-102. - C.I. Gheorghiu,
*Nonlinear deterministic dynamics with applications*, Preprint King Mongkut’s Institute of Technology, Ladkrabang, Bangkok, Thailand, 53 pp., Octomber, 2005. - C.I. Gheorghiu,
*On spectral properties of Chebyshev-type methods. Dimensions vs. structure*, Studia Univ. Babeş-Bolyai Math. Cluj-Napoca,**L**(2005) 61-66. - C.I. Gheorghiu,
*On the scalar measure of non-normality of matrices – dimension vs. structure*, General Mathematics, 11 (2003) nos. 1–2, 21–32. - C.I. Gheorghiu,
*On some one-step implicit methods as dynamical systems*, Rev. Anal. Numér. Théor. Approx.,**32**(2003) 171-175. - C.I. Gheorghiu, A. Mureşan,
*On the significance of integral properties of orbits in some superlinear fixed-period problems*, Seminar on Fixed Point Theory, Cluj-Napoca,**3**(2002) 223-230. - C.I. Gheorghiu, D. Trif,
*Direct and indirect approxima**tions**to positive solution for a nonlinear reaction-diffusion problem. Part I. Direct (variational) approximation*, Rev. Anal. Numér. Théor. Approx.**31**(2002) 61-70. - C.I. Gheorghiu, D. Trif,
*Direct and indirect approximations to positive solution for a nonlinear reaction-diffusion problem. Part II. Indirect approximation*, Rev. Anal. Numér. Théor. Approx.**31**(2002) 171-178. - C.I. Gheorghiu, E. Borşa,
*On the flow of a viscous thin layer on an inclined solid plane driven by a constant surface tension gradient*, Rev. Anal. Numér. Théor. Approx.**30**(2001) 127-134. - C.I. Gheorghiu, D. Trif,
*On the bifurcation and variational approximation of the positive solution of a nonlinear reaction-diffusion problem*, Studia Univ. Babeş-Bolyai Math.,**XLV**(2000) 29-37. - E. Borşa, C.I. Gheorghiu,
*On the Marangoni flow on an inclined plane*, Bul. Inst. Politehnic din Iaşi, Supliment Mecanica Fluidelor,**XLVI**(**L**) (2000) 61-64. - E. Borşa. C. I. Gheorghiu,
*On the Marangoni and gravity flow in an inclined channel of an arbitrary section*, Rev. Roum. Sci Techn.-Mec. Appl.,**45**(2000) 255-264. - C.I. Gheorghiu,
*A unified treatment of boundary layer and lubrication approximations in viscous fluid mechanics*, Rev. Anal. Numér. Théor. Approx.,**29**(2000) 135-138. - C.I. Gheorghiu, D. Trif,
*The numerical approximation to positive solution for some reaction-diffusion problems*, PU.M.A.,**11**(2000) no. 2, 243-253. - C.I. Gheorghiu,
*The solution to problem 97-8 by Ph. Korman, SIAM Rev., 39 (1997)*, SIAM Rev.,**40**(1998) 382-385. - C.I. Gheorghiu, Al. Tămăşan,
*On the bifurcation of the null solutions of some boundary value problems*, An. St. Univ. Ovidius Constanta, Seria Matematica,**5**(1997), 59-64. - E. Chifu, E. Gavrila, M. Sălăjan, C.I. Gheorghiu,
*Surface mobility of surfactant solutions, XVII. Determination of Marangoni rate of flow in simulated zero gravity conditions*, J. Roum. Colloid Surface Chem. Assoc.,**2**(1997), pp. 25-29. - I.S. Pop, C.I. Gheorghiu,
*A Chebyshev-Galerkin method for fourth order problems*, Proceedings of ICAOR (International Conference on Approximation and Optimization – Romania), Cluj-Napoca, July-August 1996, vol. II, pp. 217-220. - C.I. Gheorghiu,
*On the behavior of a thin liquid layer flowing due to gravity and a surface tension gradient, I. Mathematical aspects*, Studia Univ. Babeş-Bolyai Math.,**XLI**(1996) 47-54. - C.I. Gheorghiu,
*Comment on ”Numerical analysis for the effect of surfactants on a circular liquid lens I”*, Rev. Roum. Sci. Techn. – Mec. Appl.,**41**(1996) nos. 5-6, p. 493. - C.I. Gheorghiu, T. Petrila,
*On the motion of a drop due to a surface tension gradient*, Proceedings of ICAOR (International Conference on Approximation and Optimization – Romania), 1996, vol. II, pp. 117-118. - C.I. Gheorghiu, I.S. Pop,
*A modified Chebyshev-tau method for a hydrodynamic stability problem*, Proceedings of ICAOR (International Conference on Approximation, Optimization – Romania), 1996, vol. II, pp. 119-126. - C. I. Gheorghiu, S.I. Pop,
*On the Chebyshev-tau approximation for some singularly perturbed two point boundary value problems – Numerical experiments*, Rev. Anal. Numér. Théor. Approx.**24**(1995) 117-124. - C.I. Gheorghiu, Al. Tămăşan,
*On the existence and uniqueness of positive solutions of some mildly nonlinear elliptic boundary value problems*, Rev. Anal. Numér. Théor. Approx. 24(1995) 125-129. - E. Chifu, C.I. Gheorghiu, M. Sălăjan, E. Gavrila,
*Marangoni and gravity flows in thin liquid layers*, ITEC 1995, International Thermal Energy Congress, Morocco, June 5-8, 1995, published by E. Bilgen, A. Mir, T.H. Nguyen, P. Vasseur, Eds, vol.II, Ecole Polytechnique de Montreal, 1995, pp. 832-837. - C.I. Gheorghiu, M. Kohr-Ile,
*An integral formulation for some slow viscous flows with free surfaces*, Mathematica,**36**(**59**) (1994), pp. 43-54. - E. Chifu, E. Gavrila, M. Sălăjan, C.I. Gheorghiu,
*Surface mobility of surfactant solutions. XVI. Involvement of the fluid viscosities in the Marangoni flow – some aspects*, Studia Univ. Babeş-Bolyai Chemia**XXXIX**(1994), pp. 159-166. - C.I. Gheorghiu, Z. Kasa, I. Stan,
*Effects of surfactants on an undeformable drop initially at rest*, Studia Univ. Babeş-Bolyai Math.,**XXXVIII**(1993) 113-126. - C.I. Gheorghiu,
*On the competition between Marangoni and gravity forces to determinate the surface profiles of a liquid flow on an inclined plane open to air*, Preprint nr. 2, 1989, Research Seminar on Mechanics, ”Babeş-Bolyai” Univ. Cluj-Napoca, Faculty of Mathematics and Physics, pp. 47-52. - C.I. Gheorghiu,
*On a linear singularly perturbed two point boundary value problem*, Preprint nr. 1, 1989, Seminar on Functional Analysis and Numerical Methods, “Babeş-Bolyai” Univ. Cluj-Napoca, Faculty of Mathematics and Physics. - C.I. Gheorghiu,
*On the use of Green’s formula for solution of the Navier-Stokes equation*, Adv. Water Resources,**14**(1991) 113-117. - C.I. Gheorghiu,
*FEM and/or BEM for numerical simulation of Marangoni flow*, Eng. Anal. Bound. Elem.,**5**(1988) 195-197 (former Eng. Anal.) - C.I. Gheorghiu, E. Chifu,
*Surface mobility of surfactant solutions XII, Remarks concerning the Marangoni flow through an inclined surface canal*, Rev. Roumaine Chim.,**32**(1987) nos. 9-10, pp. 945-951. - E. Chifu, C.I. Gheorghiu, I. Stan,
*Some remarks concerning the Marangoni flow on an inclined plane*, Proceedings of the VI-th International Tagung über Grenzflächenaktive Stoffe, 1985, Akad. Verlag, Berlin, 1987, pp. 211-217. - E. Culea, C.I. Gheorghiu, Al. Nicula,
*Electrical Conductivity of Vitreous 75% V2O5-25%(As2O3-B203)*, Physica Status Solidi (a),**96**(1986) no. 1, pp. K85-K88. - E. Chifu, I. Albu, C.I. Gheorghiu, E. Gavrila, M. Sălăjan, M. Tomoaia-Cotisel,
*Marangoni flow -induced by temperature gradients- against gravity forces*, Rev. Roumaine Chim.**31**(1986) no. 1, 105-112. - E. Chifu, C.I. Gheorghiu, I. Stan,
*Surface mobility of surfactant solutions. XI Numerical analysis for the Marangoni and the gravity flow in a thin liquid layer of triangular section*, Rev. Roumaine Chim.,**29**(1984) no. 1, pp. 31-42. - C.I. Gheorghiu,
*Finite element methods for the general quasi harmonic equation*, Preprint nr. 1, 1982, Seminar of Numerical Approximation Method in Hydrodynamics and Heat Transfer, ”Babeş-Bolyai” Univ. Cluj-Napoca, Faculty of Mathematics. - I. Stan, C.I. Gheorghiu,
*Numerical methods for the flows with chemical reactions over a rotating disk*, Studia Univ. Babeş-Bolyai Math.,**25**(1980) no. 4, 24-31 (in Romanian). - L. Ilie, C.I. Gheorghiu,
*Numerical simulation of rain-runoff process within the Zalău drainage, at the Sărmăşag gauging point*, Hidrotehnica,**24**(1979) no. 7, 157-160 (in Romanian). - I. Stan, C.I. Gheorghiu,
*The shooting method in establishment of concentration profiles in diffusive boundary layer*, St. Cerc. Mec. Apl.,**37**(1978) no. 3, 353-360. (in Romanian) - I. Stan, C.I. Gheorghiu,
*Numerical methods in establishment of concentration profile for the flows with chemical reactions over rotating disk*, Studia Univ. Babeş-Bolyai Math.,**22**(1977) no. 1, 73-77 (in Romanian).

April 12, 2023: a paper published in *Journal of Physics A: Mathematical and Theoretical*

version of April 12, 2023.