University of Architecture, Civil Engineering and Geodesy

About: University of Architecture, Civil Engineering and Geodesy is a education organization based out in Sofia, Bulgaria. It is known for research contribution in the topics: Finite element method & Beam (structure). The organization has 3808 authors who have published 3822 publications receiving 30736 citations. The organization is also known as: Sofia Polytechnic.

Discrete Approximation of Impulsive Differential Inclusions

Abstract: The article deals with the approximation of the solution set and the reachable sets of an impulsive differential inclusion with variable times of impulses. It is strongly connected to [11] and is its continuation. We achieve order of convergence 1 for the Euler approximation under Lipschitz assumptions on the set-valued right-hand side and on the functions describing the jump surfaces and jumps themselves. Another criterion prevents the beating phenomena and generalizes available conditions. Several test examples illustrate the conditions and the practical evaluation of the jump conditions.

MgO Refractory Attack by Transient Non-saturated EAF Slag

Abstract: The gangue content in iron ore pellets that are used to produce direct-reduced iron (DRI) affects the slag volume during subsequent electric furnace steelmaking. Industrial and laboratory measurements and simulations have shown that unfluxed gangue from DRI also strongly affects the degree of saturation of the steelmaking slag with MgO. Laboratory tests show slag-line attack of such undersaturated slag on an MgO crucible, in support of reported refractory wear during steelmaking with higher-gangue DRI.

Free damped vibrations of a viscoelastic oscillator based on Rabotnov's model

Abstract: Free damped vibrations of a linear viscoelastic oscillator based on Rabotnov’s model involving one fractional parameter and several relaxation (retardation) times are investigated. The analytical solution is obtained in the form of two terms, one of which governs the drift of the system’s equilibrium position and is defined by the quasi-static processes of creep occurring in the system, and the other term describes damped vibrations around the equilibrium position and is determined by the systems’s inertia and energy dissipation. The drift is governed by an improper integral taken along two sides of the cut of the complex plane. Damped vibrations are determined by two complex conjugate roots of the characteristic equation, which are located in the left half-plane of the complex plane. The behaviour of the characteristic equation roots as function of the system’s parameters is shown in the complex plane.