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Title:Singularne točke in fazni portreti v polinomskih ravninskih sistemih navadnih diferencialnih enačb
Authors:ID Majcen, Metka (Author)
ID Ferčec, Brigita (Mentor) More about this mentor... New window
Files:.pdf MAG_Majcen_Metka_2018.pdf (14,55 MB)
MD5: BC24E21A41073C8DA86C58A2C7AA6DE9
PID: 20.500.12556/dkum/eba9ac1d-ca89-468c-9c7a-2c55688895e6
 
Language:Slovenian
Work type:Master's thesis/paper
Typology:2.09 - Master's Thesis
Organization:FNM - Faculty of Natural Sciences and Mathematics
Abstract:V magistrskem delu so obravnavani avtonomni ravninski sistemi navadnih diferencialnih enačb. Na začetku so opisani osnovni pojmi, kot so obstoj in enoličnost rešitev ter geometrijska predstavitev krivuljnih rešitev sistema. V nadaljevanju so obravnavani avtonomni sistemi v ravnini in konstrukcija njihovih faznih portretov. Drugo poglavje je namenjeno linearnim sistemom diferencialnih enačb, kjer so na začetku opisani t.i. nepovezani linearni sistemi, diagonalizacija in Jordanova forma matrike. Predvsem je poudarek na dvorazsežnih matrikah, kajti v nadaljevanju so navedene lastnosti enostavnih in neenostavnih ravninskih linearnih sistemov, njihovi fazni portreti ter tipi in stabilnost singularne točke v izhodišču. Tretje poglavje je namenjeno avtonomnim nelinearnim sistemom v ravnini in njihovim faznim portretom. Na začetku je opisana linearizacija nelinearnega sistema v okolici singularne točke in z njo povezan linearizacijski izrek. Potem je podrobneje obravnavana stabilnost singularnih točk (tudi v smislu Liapunove funkcije). Nato so navedeni in na kratko opisani še nekateri drugi objekti, ki lahko poleg singularnih točk nastopijo v faznih portretih nelinearnih sistemov: navadne točke, limitni cikli (obravnavani sta tudi Hopfova in sedlo-vozel bifurkacija), homoklinične in heteroklinične orbite. Zadnji razdelek tega poglavja pa je namenjen enemu izmed osrednjih problemov v kvalitativni teoriji sistemov navadnih diferencialnih enačb, t.j. problemu centra in fokusa. Ker je le-ta povezan z obstojem prvega integrala določene oblike, je navedena tudi definicija prvega integrala sistema diferencialnih enačb.
Keywords:navadna diferencialna enačba, singularna točka, fazni portret, trajektorija, limitni cikel, stabilnost
Place of publishing:Maribor
Publisher:[M. Majcen]
Year of publishing:2018
PID:20.500.12556/DKUM-72144 New window
UDC:517.91(043.2)
COBISS.SI-ID:24181000 New window
NUK URN:URN:SI:UM:DK:8OEFIKDW
Publication date in DKUM:28.11.2018
Views:1761
Downloads:237
Metadata:XML DC-XML DC-RDF
Categories:FNM
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Licences

License:CC BY-NC-ND 4.0, Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International
Link:http://creativecommons.org/licenses/by-nc-nd/4.0/
Description:The most restrictive Creative Commons license. This only allows people to download and share the work for no commercial gain and for no other purposes.
Licensing start date:12.09.2018

Secondary language

Language:English
Title:Singular points and phase portraits in polynominal planar systems of ordinary differential equations
Abstract:In this master thesis the autonomous planar systems of ordinary differential equations are studied. At the beginning, the basic notions such as the existence and uniqueness of the solution and the geometrical interpretation of curve solutions are described. Then, the autonomous systems in the plane and the construction of their phase portraits is considered. The second chapter is devoted to linear systems of differential equations, where at the beginning the so-called uncoupled linear systems, diagonalization and Jordan form of the matrix are studied. Especially, the focus is on the simple and non-simple planar linear systems, their phase portraits and the types and the stability of the singular point at the origin are mentioned. The third chapter is dedicated to autonomous nonlinear systems in the plane and their phase portraits. At the beginning, the linearization of nonlinear system in the neighbourhood of singular point and the Linearization theorem connected with it are stated. Then the stability of singular points (also in terms of Liapunov function) is discussed in more detail. Furthermore, some other elements are mentioned and briefly described, which can occur in the phase portraits of nonlinear systems beside singular points: ordinary points, limit cycles (Hopf bifurcation and saddle-node bifurcation are considered), homoclinic and heteroclinic orbits. The last section of this chapter is devoted to one of the main problems in qualitative theory of systems of ordinary differential equations, i.e. center-focus problem. Since this problem is connected with the existence of first integral of the certain form the definition of first integral of system of differential equations is stated, too.
Keywords:ordinary differential equation, singular point, phase portrait, trajectory, limit cycle, stability


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