I am a professor emeritus. I am affiliated with the Faculty of Industrial Engineering in Novo mesto, Slovenia. As a professor at the faculty, I teach the courses Selected Chapters in Mechanics, Intelligent Maintenance of Processes and Devices, Energy Systems in Vehicles and Vehicle Software.
This paper treats the control of nonstationary oscillations of acoustic pressure in the combustio... more This paper treats the control of nonstationary oscillations of acoustic pressure in the combustion instability process, which appears in the combustion chamber. Two models of nonstationary combustion process control are presented, where first of them is a classic model, which applies the Rayleigh criterium of phase matching between heat-release rate and acoustic pressure. The second model is an alternative van der Pol model exhibiting selfexciting oscillations due to the feedback with a negative damping. The paper outlines the model of fuel control, which is successfully applied for quenching of selfexcited oscillations. Efficiency of fuel control to quench selfexcited oscillations is shown in the phenomenon of competitive quenching, where the influence of various control parameters is explained.
The paper treats the numerical construction of dispersion curves which belong to the propagation ... more The paper treats the numerical construction of dispersion curves which belong to the propagation of Rayleigh-Lamb waves in isotropic elastic media. The Newton-Raphson method.is applied for computation of real, imaginary and complex wavenumbers in dependence on the frequency of the wave. Due to multivaluedness, unexpected jumps between modes of dispersion curves occur in branch tracing, which prevents successful direct application of the method. This shortcoming is eliminated in the article by introducing the arc-length continuation method. The efficiency of this supplement to the Newton-Raphson method is shown on the example of an aluminum plate with constructions of dispersion curves for real, imaginary and complex wave numbers.
This paper treats competitive predator-prey systems, which growth of populations and their mutual... more This paper treats competitive predator-prey systems, which growth of populations and their mutual interactions are time dependent. For solving a general Lotka-Volterra system of equations, the multistage homotopy perturbation (MH-P) method is developed to predict the time evolution of the dynamical system and its properties, such as existence of stable periodic orbits. As the newest achievement, the efficiency of MH-P method is provedintreatment of almost-periodic variations of coefficients with incommensurate excitation frequencies.The periodic variations of coefficients are analyzed as special case by assuming that excitation frequencies are commensurate. By using MH-P method, the approximate analytic solutions are obtained, which are very accurate in the long term behaviour. Although an usefull convergence test of the computed solution is provided, the accuracy of MH-P method is compared also by results of the numerical integration of Lotka-Volterra equations by using the Runge...
V članku je obravnavan model samovzbujenih vibracij v procesu struženja z eno prostostno stopnjo,... more V članku je obravnavan model samovzbujenih vibracij v procesu struženja z eno prostostno stopnjo, ki sestoji iz regulacijske strukture z direktno vejo, primarno povratno zvezo in regenerativno povratno zvezo. Direktna veja služi za modeliranje dinamike procesa odrezavanja in strukturne dinamike. Regenerativna povratna zveza služi za modeliranje časovne zakasnitve, ki v procesu odrezavanja nastaja zaradi vrtenja obdelovanca. Vibracije pri struženju nastanejo, ko postane regulacijska struktura nestabilna in neugodno vplivajo na kvaliteto procesa odrezavanja (groba površina in slaba dimenzijska natančnost obdelovanca). Prav tako pa povzročajo hitro obrabo rezalnega orodja in celo možno poškodbo stružnice. V prispevku je izpeljana vodilna diferencialna enačba vibracij v procesu struženja, ki jo rešujemo z novo metodo koračnega harmonskega ravnovesja (MKHR). S pomočjo te metode konstruiramo stabilnostni diagram procesa struženja, ki z določitvijo stabilnih področij zagotavlja optimalne p...
Članek obravnava Kartezijanski in Baconski pristop v znanosti in tehniki, ki sta v štirih stoletj... more Članek obravnava Kartezijanski in Baconski pristop v znanosti in tehniki, ki sta v štirih stoletjih razvoja moderne znanosti imela po vsej verjetnosti največji vpliv. Kartezijanski pristop je deduktiven, znanstveni pogled na naravne pojave pa univerzalen. Baconski pogled temelji na eksperimentu in uveljavlja induktivni način sklepanja. V članku je prikazano, da sta oba pristopa vsak zase nezadostna, pač pa sta združena izredno uspešna. Uporaba obeh načel je prikazana pri lastnih raziskavah na področju nelinearnih stacionarnih in nestacionarnih nihanj nosilcev in elektromehanskih sistemov. Obravnavani so nepričakovani pojavi v teh sistemih, ki jih ne moremo predvidevati v okviru kartezijanskih, lahko pa jih odkrijemo z uporabo Baconskih načel raziskovanja.
Vzdražljive (ekscitabilne) celice se imenujejo celice, ki so sposobne proizvajati akcijske potenc... more Vzdražljive (ekscitabilne) celice se imenujejo celice, ki so sposobne proizvajati akcijske potenciale. Akcijski potenciali nastajajojo v nevronih in mišicah v obliki signalov. Signalni mehanizem povzroča možgansko aktivnost oziroma krčenje mišic. Lipidni plasti celične membrane se obnašata kot kondenzator, spremenljive prevodnosti membrane za posamezne ione pa so posledica ionskih kanalov, ki se lahko odpirajo ali zapirajo in s tem bolje ali slabše prevajajo. Na tej osnovi lahko celično membrano modeliramo kot električno vezje. V članku je predstavljena izpeljava enačb Hodgkin-Huxleyevega modela celične membrane s pomočjo osnovnih zakonov elektrotehnike in kinetike prvega reda. Dobljeni matematični model celične membrane je uporabljen za simulacijo akcijskega potenciala s simboličnim programskim orodjem Mathematica®.
This paper treats a three level nonlinear supply chain, which consists from a manufacturer, a dis... more This paper treats a three level nonlinear supply chain, which consists from a manufacturer, a distributor and a retailer as a dynamical system. The dynamic behavior of supply chain is modelled by using the continuous Lorenz-like model with disturbances. The Lorenz model is known from physics in the study of dissipative hydrodynamical systems with excitation and represents a paradigmatic example of the deterministic system, which is able to exhibit chaotic motions. Very complex supply chain relationships are modelled due to the information flow distortion at the distributor, caused by disturbances, which appear at the retailer. By using the proposed nonlinear supply chain model, the steady state, the saturation and the chaotic state of the supply chain are analyzed, respectively. The range of parameter values, which are characteristic for the appearance of such states are determined. In the paper, the meaning of the regular state in which the supply chain cannot keep due to the dist...
This paper treats the control of nonstationary oscillations of acoustic pressure in the combustio... more This paper treats the control of nonstationary oscillations of acoustic pressure in the combustion instability process, which appears in the combustion chamber. Two models of nonstationary combustion process control are presented, where first of them is a classic model, which applies the Rayleigh criterium of phase matching between heat-release rate and acoustic pressure. The second model is an alternative van der Pol model exhibiting selfexciting oscillations due to the feedback with a negative damping. The paper outlines the model of fuel control, which is successfully applied for quenching of selfexcited oscillations. Efficiency of fuel control to quench selfexcited oscillations is shown in the phenomenon of competitive quenching, where the influence of various control parameters is explained.
The paper treats the numerical construction of dispersion curves which belong to the propagation ... more The paper treats the numerical construction of dispersion curves which belong to the propagation of Rayleigh-Lamb waves in isotropic elastic media. The Newton-Raphson method.is applied for computation of real, imaginary and complex wavenumbers in dependence on the frequency of the wave. Due to multivaluedness, unexpected jumps between modes of dispersion curves occur in branch tracing, which prevents successful direct application of the method. This shortcoming is eliminated in the article by introducing the arc-length continuation method. The efficiency of this supplement to the Newton-Raphson method is shown on the example of an aluminum plate with constructions of dispersion curves for real, imaginary and complex wave numbers.
This paper treats competitive predator-prey systems, which growth of populations and their mutual... more This paper treats competitive predator-prey systems, which growth of populations and their mutual interactions are time dependent. For solving a general Lotka-Volterra system of equations, the multistage homotopy perturbation (MH-P) method is developed to predict the time evolution of the dynamical system and its properties, such as existence of stable periodic orbits. As the newest achievement, the efficiency of MH-P method is provedintreatment of almost-periodic variations of coefficients with incommensurate excitation frequencies.The periodic variations of coefficients are analyzed as special case by assuming that excitation frequencies are commensurate. By using MH-P method, the approximate analytic solutions are obtained, which are very accurate in the long term behaviour. Although an usefull convergence test of the computed solution is provided, the accuracy of MH-P method is compared also by results of the numerical integration of Lotka-Volterra equations by using the Runge...
V članku je obravnavan model samovzbujenih vibracij v procesu struženja z eno prostostno stopnjo,... more V članku je obravnavan model samovzbujenih vibracij v procesu struženja z eno prostostno stopnjo, ki sestoji iz regulacijske strukture z direktno vejo, primarno povratno zvezo in regenerativno povratno zvezo. Direktna veja služi za modeliranje dinamike procesa odrezavanja in strukturne dinamike. Regenerativna povratna zveza služi za modeliranje časovne zakasnitve, ki v procesu odrezavanja nastaja zaradi vrtenja obdelovanca. Vibracije pri struženju nastanejo, ko postane regulacijska struktura nestabilna in neugodno vplivajo na kvaliteto procesa odrezavanja (groba površina in slaba dimenzijska natančnost obdelovanca). Prav tako pa povzročajo hitro obrabo rezalnega orodja in celo možno poškodbo stružnice. V prispevku je izpeljana vodilna diferencialna enačba vibracij v procesu struženja, ki jo rešujemo z novo metodo koračnega harmonskega ravnovesja (MKHR). S pomočjo te metode konstruiramo stabilnostni diagram procesa struženja, ki z določitvijo stabilnih področij zagotavlja optimalne p...
Članek obravnava Kartezijanski in Baconski pristop v znanosti in tehniki, ki sta v štirih stoletj... more Članek obravnava Kartezijanski in Baconski pristop v znanosti in tehniki, ki sta v štirih stoletjih razvoja moderne znanosti imela po vsej verjetnosti največji vpliv. Kartezijanski pristop je deduktiven, znanstveni pogled na naravne pojave pa univerzalen. Baconski pogled temelji na eksperimentu in uveljavlja induktivni način sklepanja. V članku je prikazano, da sta oba pristopa vsak zase nezadostna, pač pa sta združena izredno uspešna. Uporaba obeh načel je prikazana pri lastnih raziskavah na področju nelinearnih stacionarnih in nestacionarnih nihanj nosilcev in elektromehanskih sistemov. Obravnavani so nepričakovani pojavi v teh sistemih, ki jih ne moremo predvidevati v okviru kartezijanskih, lahko pa jih odkrijemo z uporabo Baconskih načel raziskovanja.
Vzdražljive (ekscitabilne) celice se imenujejo celice, ki so sposobne proizvajati akcijske potenc... more Vzdražljive (ekscitabilne) celice se imenujejo celice, ki so sposobne proizvajati akcijske potenciale. Akcijski potenciali nastajajojo v nevronih in mišicah v obliki signalov. Signalni mehanizem povzroča možgansko aktivnost oziroma krčenje mišic. Lipidni plasti celične membrane se obnašata kot kondenzator, spremenljive prevodnosti membrane za posamezne ione pa so posledica ionskih kanalov, ki se lahko odpirajo ali zapirajo in s tem bolje ali slabše prevajajo. Na tej osnovi lahko celično membrano modeliramo kot električno vezje. V članku je predstavljena izpeljava enačb Hodgkin-Huxleyevega modela celične membrane s pomočjo osnovnih zakonov elektrotehnike in kinetike prvega reda. Dobljeni matematični model celične membrane je uporabljen za simulacijo akcijskega potenciala s simboličnim programskim orodjem Mathematica®.
This paper treats a three level nonlinear supply chain, which consists from a manufacturer, a dis... more This paper treats a three level nonlinear supply chain, which consists from a manufacturer, a distributor and a retailer as a dynamical system. The dynamic behavior of supply chain is modelled by using the continuous Lorenz-like model with disturbances. The Lorenz model is known from physics in the study of dissipative hydrodynamical systems with excitation and represents a paradigmatic example of the deterministic system, which is able to exhibit chaotic motions. Very complex supply chain relationships are modelled due to the information flow distortion at the distributor, caused by disturbances, which appear at the retailer. By using the proposed nonlinear supply chain model, the steady state, the saturation and the chaotic state of the supply chain are analyzed, respectively. The range of parameter values, which are characteristic for the appearance of such states are determined. In the paper, the meaning of the regular state in which the supply chain cannot keep due to the dist...
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