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Provozní parametry a charakteristiky aktuátorů s dilatačním prvkem
Doležel, Ivo ; Karban, P. ; Ulrych, B. ; Barglik, J. ; Pantelyat, M. ; Matyukhin, Y. ; Gontarowskiy, P.
In specific applications one needs actuators characterized by very high forces at small shifts. As actuators of classical constructions mostly cannot satisfy these requirements, the authors designed another arrangement with an inductively heated dilatation element. But huge mechanical strains and stresses of thermoelastic origin acting in its structural parts could lead to its damage or destruction. The paper deals with mathematical modeling of the device that is solved numerically in the combined formulation (while the electromagnetic field is solved independently, the thermal and thermoelastic effects are solved in the hard-coupled formulation). The algorithm is illustrated on a typical example whose results are discussed.
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Integrální výpočet magnetického pole stíněného trojfázového vedení
Karban, P. ; Doležel, Ivo ; Ulrych, B.
The paper deals with numerical modeling of a three-phase harmonic-current carrying shielded line. In most similar cases, computation of magnetic field and other associated quantities is realized using the finite element method that is effective, reliable and the results obtained correspond to the physical reality. Nevertheless, the method may become problematic when particular subre-gions (conductors, insulation, shielding elements) are geometrically incommensurable, which is even the case of thin shielding shells. That is why the authors use the integral approach for modeling of the relevant effects. Presented is its basic continuous mathematical model that is solved numerically. The theoretical analysis is supplemented with a typical example.
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Možnosti elektromagnetického čerpání tekutých kovů a jejich numerické modelování
Musil, Ladislav ; Doležel, Ivo ; Karban, P. ; Ulrych, B. ; Barglik, J.
Electromagnetic pumps and feeders of molten metals are widely spread devices used in many branches of industry. Their operation is, however, accompanied by a high consumption of energy. Im-provement of their efficiency and optimization of their design requires detailed knowledge of the relevant electromagnetic (and sometimes also thermo- and hydrodynamic) processes. The paper deals with the principles of operation of such devices, presents their mathematical models and techniques of their numerical solu-tion. The theoretical analysis is illustrated on typical examples providing the fundamental ideas about their operation parameters and characteristics.
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Integrální přístup k řešení neferomagnetického elektrodynamického akcelerátoru
Karban, P. ; Doležel, Ivo
The paper deals with the description of dynamic behavior of a nonferromagnetic electrodynamic launcher. Although the problem itself is not new, an innovative item is determination of eddy currents in the launched body based on the integral approach that provides more accurate results than former algorithms of computation based on the FEM or electric circuit techniques. The methodology is illustrated on an example whose results are discussed
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Techniky zpracování tuhých a tekutých kovů založené na elektromagnetické indukci
Doležel, Ivo ; Šolín, Pavel ; Musil, Ladislav ; Ulrych, B. ; Karban, P. ; Barglik, J.
A lot of up-to-date industrial technologies associated with treatment of solid and liquid metals are based on thermal and force effects of electromagnetic field. The fundamental process is induction heating of metals that precedes a number of consequent operations such as tempering, drying, melting, stirring, hardening, hot pressing etc. The paper summarizes physical essence of the above processes (that usually represent complex coupled problems) and presents their mathematical and computer models as well as possible methods of their solutions.
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Jev "zamrzlého pole" v elektricky vodivých médiích, řešený prostředky klasické elektrodynamiky
Doležel, Ivo ; Karban, P. ; Mayer, D. ; Ulrych, B.
The concept "frozen field" is often used in association with behavior of strongly electrically conductive media. Being introduced in astrophysics the phenomenon consists in drift of magnetic field by electrically well conductive medium (plasma or ionized mixture of gas and dust particles) that moves due to some primary mechanism not immediately associated with this magnetic field. This paper presents the description of the effect by means of classical electrodynamics in nonrelativistic medium and its solution in an integral formulation.
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Řešení nestacionárních problémů vířivých proudů integrálním přístupem
Doležel, Ivo ; Karban, P.
Althout most eddy problems are theoretically solved by various differential techniques, there exist several classes of tasks where use of the differential approach may be complicated or even prohibitive. Mentioned can be, for example, problems characterized by geometrical incommensurability of individual subdomains, by their motion or by ignorance of the boundary conditions. In such a case, application of the integral approach may be an advantage. The paper presents the theoretical background of the method.
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Program pro výpočet provozních parametrů velkých transformátorů
Karban, P. ; Doležel, Ivo
About fifteen years ago Prof. Doležel started developing a relatively large program package for solution of a wide spectrum of tasks associated with operation of large power transformers. The program ordered by one of the principal Czech manufacturers - ŠKODA Plzeň - was written in FORTRAN 77 for environment MS-DOS supplemented with memory extender DBOS and contained the following modules: Solution of 2D magnetic field distribution in the window. It could be calculated either analytically (provided that the window contains no ferromagnetic subdomains such as shunts) or numerically, using the finite element method.
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Computation of 3D Electrostatic Fields Excited by Thin Conductors
Karban, P. ; Škopek, M. ; Doležel, Ivo
Solution of 3D electric fields in a system of thin charged conductors of general shapes by classical differential methods (FDM, FEM etc.) is extremely difficult due to ignorance of boundary conditions and existence of geomertically incommensurable subdomainswithin the investigated area. Application of integral methods is also complicated because the kernel functions occuring in the first-kind Fredholm equations are intergrable only in 2D and not in 1D.
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Posuvný indukční ohřev a související jevy v kvazi-sdružené formulaci
Karban, P. ; Ulrych, B. ; Doležel, Ivo
The paper deals with quasi-coupled numerical solution of the problem of induction heating and associated phenomena in 2D axisymmetric arrangements. The process of heating is modeled by a special algorithm respecting the temperature dependencies of various material properties and (when necessary) time variable boundary conditions. The algorithm fully developed by the authors is illustrated on an example of continual induction hardening
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