Kristian Sabo

 

ksabo web

Full Professor
Department of Mathematics
Josip Juraj Strossmayer University of Osijek
Trg Ljudevita Gaja 6
Osijek, HR-31000, Croatia¸

Google Scholar Profile

phone: +385-31-224-827
fax: +385-31-224-801
email:  ksabo @ mathos.hr
office:  18 (ground floor)

 


Research Interests

Applied and Numerical Mathematics (Curve Fitting, Parameter Estimation, Data Cluster Analysis) with applications in Agriculture, Economy, Chemistry, Politics, Electrical Engineering, Medicine, Food Industry, Mechanical Engineering.

Degrees

PhD in Numerical Mathematics, Department of Mathematics, University of Zagreb, 2007
MSc in Mathematics, Department of Mathematics, University of Zagreb, 2003
BSc in Mathematics and Computer Science, Department of Mathematics, Croatia, 1999
 

Publications

Journal Publications

  1. M. Benšić, P. Taler, S. Hamedović, E.K. Nyarko, K. Sabo, LeArEst: Length and Area Estimation from Data Measured with Additive Error, The R Journal (2017), prihvaćen za objavljivanje
    This paper describes an R package LeArEst that can be used for estimating object dimensions from a noisy image. The package is based on the simple parametric model for data that are drawn from uniform distribution contaminated by an additive error. Our package is able to estimate the length of the object of interest on a given straight line that intersects it as well as to estimate the object area if it is elliptically shaped. The input data may be a numerical vector as well as an image in JPEG format. In this paper, background statistical models and methods for the package are summarized, and algorithms and key functions implemented are described. Also, examples that demonstrate its usage are provided.
  2. K. Sabo, Least absolute deviations problem for the Michaelis--Menten function, Mathematica Slovaca 67/1 (2017), 245-262
    In this paper, we consider the problem of the existence of a least absolute deviations estimator for the Michaelis--Menten model function. We give necessary and sufficient conditions under which the least absolute deviations problem has a solution. In order to illustrate the usefulness of such conditions we give several numerical examples.
  3. M. Benšić, K. Sabo, Uniform distribution width estimation from data observed with Laplace additive error, Journal of the Korean Statistical Society 45/4 (2016), 505-517
    A one-dimensional problem of a uniform distribution width estimation from data observed with a Laplace additive error is analyzed. The error variance is considered as a nuisance parameter and it is supposed to be known or consistently estimated before. It is proved that the maximum likelihood estimator in the described model is consistent and asymptotically efficient and sufficient conditions for its existence are given. The method of moment estimator is also analyzed in this model and compared with the maximum likelihood estimator theoretically and in simulations. Finally, one real-world example illustrates the possibility for applications in two-dimensional problems.
  4. K. Sabo, R. Scitovski, An approach to cluster separability in a partition, Information Sciences 305 (2015), 208-218
    In this paper, we consider the problem of cluster separability in a minimum distance partition based on the squared Euclidean distance. We give a characterization of a well-separated partition and provide an operational criterion that gives the possibility to measure the quality of cluster separability in a partition. Especially, the analysis of cluster separability in a partition is illustrated by implementation of the $k$-means algorithm.
  5. M. Duspara, K. Sabo, A. Stoić, Acoustic emision as tool wear monitoring, Tehnički vjesnik 21/5 (2014), 1097-1101
    This paper describes a fast Fourie transformation and its application to monitoring tool wear. Tool wear monitoring is a difficult task because many machining processes are non-linear time-variant systems, which makes them difficult to model and the signals obtained from sensors are dependent on a number of other factors, such as machining conditions. Indirect method of tool condition monitoring is based on the acquisition of measured values of process variables (such as cutting force, temperature, vibration, acoustic emission, surface roughness) and the relationship between tool wear and these values.





Projects

  • Scientifically branded Pork (Member of the scientific project entitled above. Project started on June 1, 2014. Principal investigator is professor Goran Kušec from Faculty of Agriculture in Osijek, University of Osijek. Project was supported by Croatian Science Foundation.)

 


Professional Activities

Editorial Board

Since 2012 member of the Editorial board of the Journal Osječki matematički list

2001-2012 Editor in Chief of the Journal Osječki matematički list

 


 

Committee Memberships
  •  Member of the Organize Committee of the 4th Croatian Congress of Mathematics, Osijek, 2008
  •  Member of the Organize Committee of the 15th International Conference on Operational Research, Croatian Operational Research Society, Osijek 2014

 

Refereeing/Reviewing
 

Journal of Computational and Applied Mathematics, Journal of Classification, Mathematical Communications,  International Journal of Applied and Mathematics and Computer Science, Croatian Operational Research Review, TEAM 2012 International Conference, Osječki matematički list


 

Service Activities

Since 2013 president of Osijek Mathematical Society

2001-2013 secretary of Osijek Mathematical Society

 

Selected Other Activities (in Croatian)
 

 

  • 2014., 2015.  Večer matematike – manifestacija popularizacije matematike u organizaciji Udruge matematičara Osijeku i Hrvatskog matematičkog društva -  Član Programskog i Organizacijskog odbora
  •  2013.-2016. Matematičke pripreme za učenike srednjih škola • Programski i Organizacijski koordinator
  • 2000.-2016. Zimska matematička škola za učenike srednjih škola  • Član Programskog i Organizacijskog odbora
  • 2000.-2016. Zimska matematička škola za učenike osnovnih škola  • Član Programskog i Organizacijskog odbora
  • 2006.-2016. Stručni kolokvij Udruge matematičara Osijek • Član Programskog i Organizacijskog odbora
  • travanj, 2014.  Geometrijska škola Stanko Bilinski, Našice:  Predavanje za nastavnike: „Funkcija udaljenosti i odgovarajuća geometrija“,  Radionica za učenike: “Neki optimizacijski problemi u geometriji“
  • travanj, 2014. Festival znanosti Sveučilišta Josipa Jurja Strossmayera u Osijeku  Predavanje: „Što su optimalne izborne (upravne) jedinice i kako ih odrediti“.  Član Programskog i Organizacijskog odbora
  • listopad, 2012. Stručni skup: Nastava matematike i izazovi moderne tehnologije u organizaciji Udruge Normala - Predavanje: „Zaglađivanje podataka: metode, pristupi i primjene“

 

 


Teaching (in Croatian)

Konzultacije: Srijeda  11:00 - 12:00

Teme zavšnih i diplomskih radova (pdf)

 

Ljetni semestar 2015./2016.

Grupiranje podataka: pristupi, metode i primjene,  ponedjeljak 13:00 - 17:00, RP2

Linearno programiranje, petak 8:00-12:00, RP1

Numerička analiza, srijeda 10:00-12:00, P24

 

Zimski semestar 2015./2016.

 Diferencijalni račun, utorak, 8:00 - 11:00, P 1

 Matematički praktikum, srijeda, 8:00-10:00

 

Ljetni semestar 2014./2015.

Grupiranje podataka: pristupi, metode i primjene,  ponedjeljak 13:00 - 17:00, RP2

Linearno programiranje, utorak 15:00-19:00, P3

Numerička analiza, srijeda 8:00-10:00, P24

Primjene diferencijalnog i integralnog računa II, srijeda 10:00-11:00, P2

 


Personal

 

  • Birthdate: November 23, 1975
  • Birthplace: Kula, Vojvodina, Serbia
  • Family: married with Marija, and have one daughter Paula

 

Udžbenik Linearno programiranje (pdf)

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