Communications - Scientific Letters of the University of Zilina, 2012 (vol. 14), issue 3
Articles
Simulation of a Wheeled Vehicle Dynamic Regimes in Laboratory Conditions
Robert Labuda, Andrej Kovalcik, Jan Repka, Vladimir Hlavna
Communications - Scientific Letters of the University of Zilina 2012, 14(3):5-9 | DOI: 10.26552/com.C.2012.3.5-9 
The paper deals with simulation of wheeled vehicle dynamic regimes in laboratory conditions. Based on the analysis of static and dynamic characteristics of the vehicle and test equipment the calculation model was created that calculates the course of a loading moment on the simulator for the given vehicle and driving regime. The basic condition for the simulation is the requirement for reaching congruent courses of driving speeds at the same vehicle control both on the roadway and in the test room.
Analysis of Transmission Phenomena in Low-Potential Heat Transport by Heat Pipes in the Deep- Borehole Simulator
Richard Lenhard, Michal Jakubsky, Milan Malcho, Jozef Jandacka
Communications - Scientific Letters of the University of Zilina 2012, 14(3):10-16 | DOI: 10.26552/com.C.2012.3.10-16
This article presents a proposal of a simulator for low-potential geothermal heat transfer by means of heat pipes into the heat pump exchanger section. On this device the research on transmission phenomena at different temperatures at the simulator inlet was done. Measurements were taken at various temperature and pressure parameters of carbon dioxide as a working substance in the heat pipe. The paper contains experimental measurements on the simulator for low potential heat transfer and their analysis, theoretical analysis of phase changes in carbon dioxide in the heat pipes depending on changes in pressure and temperature. Simultaneously, the impact...
Physical Modeling of Flow in a Tundish for Continuous Casting Machine
Maria Carnogurska, Miroslav Prihoda
Communications - Scientific Letters of the University of Zilina 2012, 14(3):17-23 | DOI: 10.26552/com.C.2012.3.17-23
The paper describes a procedure for obtaining similarity criteria for a real object - a tundish for continuous casting machine (CCM) and its reduced physical model. The procedure is demonstrated on the basis of Navier-Stockes differential equations and with the help of dimensional analysis. To obtain similarity criteria dimensional analysis makes use of dimensions of those physical quantities which significantly influence the mentioned phenomenon. From the above it results that when modeling a concrete phenomenon with the help of this method it is inevitable to thoroughly know the physical substance of the phenomenon to expressly ensure the choice...
Meshless Modelling of Laminate Mindlin Plates under Dynamic Loads
Milan Zmindak, Daniel Riecky
Communications - Scientific Letters of the University of Zilina 2012, 14(3):24-31 | DOI: 10.26552/com.C.2012.3.24-31
Collocation method and Galerkin method have been dominant in the existing meshless methods. A meshless local Petrov-Galerkin (MLPG) method is applied to solve laminate plate problems described by the Reissner-Mindlin theory for transient dynamic loads. The Reissner-Mindlin theory reduces the original three-dimensional (3-D) thick plate problem to a two-dimensional (2-D) problem. The bending moment and the shear force expressions are obtained by integration through the laminated plate for the considered constitutive equations in each lamina. The weak-form on small subdomains with a Heaviside step function as the test functions is applied to derive local...
Optimization of Thin Shell Structures Using FSD Algorithms
Milan Saga, Martin Dudinsky, Peter Pechac
Communications - Scientific Letters of the University of Zilina 2012, 14(3):32-38 | DOI: 10.26552/com.C.2012.3.32-38
The paper presents a theoretical and numerical study of the efficiency of the fully stress design (FSD) algorithm in the case of thin shell finite elements. Relation between membrane forces, bending moments and the element thickness is analysed by means of numerical tests. Subsequent numerical testing and a new iterative algoritm to providing the rapid convergence of the optimizing process is proposed.
Measuring Strain of the Lattice Towers
Vladimir Dekys, Jozef Broncek
Communications - Scientific Letters of the University of Zilina 2012, 14(3):39-42 | DOI: 10.26552/com.C.2012.3.39-42
The paper deals with strain measuring of bolted steel lattice high voltage tower structure on the test field. This measurement was associated to the test according to international standard IEC 60652, Ed. 2.0. If the tower is simulated as a truss structure and we expect the linear behavior of this object then the test data and calculation may show variations. The displacements of screw joint were detected as a source of this variation or non linear properties of structure. The key to this conclusion was detection of peak in measurement data.
Multi-Software Platform for Solving of Multibody Systems Synthesis
Alzbeta Sapietova, Milan Saga, Pavol Novak
Communications - Scientific Letters of the University of Zilina 2012, 14(3):43-48 | DOI: 10.26552/com.C.2012.3.43-48
The paper deals with design and application of multi-software platform for solving of mechanical multi-body system problems. The Adams working interface and open architecture of Matlab programming language enable share common data during parallel run of simulations. This process was used for design and implementation of evaluation algorithm and optimization of technical equipment parameters in terms of their mechanical properties. The goal is to present the mapping process of the working space of the chosen manipulating equipment and application of the optimizing approach to find its geometry parameters. Multi-software technique will be applied for...
Numerical Simulation of Residual Stresses and Distortions in Butt Weld in Simulation Programme Sysweld
Radoslav Konar, Milos Mician
Communications - Scientific Letters of the University of Zilina 2012, 14(3):49-54 | DOI: 10.26552/com.C.2012.3.49-54
The article describes the theoretical knowledge of the residual stresses induced during welding in butt welded joint and the possibilities of their simulations in a simulation programme SYSWELD. In conclusion are compared experimental and simulated results.
Determination of the Maximum Roller Bearing Load with Regards to Durability Thereof Using FEM Analysis
Slavomir Hrcek, Robert Kohar, Stefan Medvecky
Communications - Scientific Letters of the University of Zilina 2012, 14(3):55-61 | DOI: 10.26552/com.C.2012.3.55-61
This paper deals with accurate geometric models of rolling bearing components in the CAD system. This model is then employed to create a static structural analysis used to determine the size of stress between the components of a rolling bearing. Following the stress analysis, we specify the maximum load of a rolling bearing with regards to durability thereof.
Usage of Dynamic Analysis to Determine Force Interactions Between Components of Rolling Bearings
Robert Kohar, Slavomir Hrcek, Stefan Medvecky
Communications - Scientific Letters of the University of Zilina 2012, 14(3):62-67 | DOI: 10.26552/com.C.2012.3.62-67
The aim of this paper is to detail the creation of a roller bearing model in the Adams program suite for subsequent dynamic analysis and to obtain information about different parts of the bearing during the simulation. The bearing model was made so as to closely resemble its reallife counterpart, which allows us to estimate load conditions, dynamic conditions of individual bearing parts and interactions between them
The Effect of Metric Space on the Results of Graph Based Colour Image Segmentation
Martina Zachariasova, Robert Hudec, Miroslav Benco, Patrik Kamencay, Peter Lukac, Slavomir Matuska
Communications - Scientific Letters of the University of Zilina 2012, 14(3):68-72 | DOI: 10.26552/com.C.2012.3.68-72
This paper deals with the impact of the metric space on the results of colour image segmentation algorithm. Distance and similarity measures are important tasks for quality of colour image segmentation. Main idea of this research is to make a comparison of algorithm results with using different metrics. Euclidean distance is the most used metric in many colour image segmentation algorithms. This paper shows comparison of this metric with many other metrics. Nine different metrics are gradually used in efficient graph based colour image segmentation algorithm created in the C++ language. The efficiency of precision and recall is one of the investigation...
Applications of Cutting Stock Problem
Vladimir Medvid
Communications - Scientific Letters of the University of Zilina 2012, 14(3):73-77 | DOI: 10.26552/com.C.2012.3.73-77
We present one heuristic solution for the well-known cutting stock problem which was formulated by Kantorovich in 1939. It is the problem of filling an order at minimum cost for specified numbers of lengths of material to be cut to given stock lengths of given cost. When expressed as an integer programming problem the large number of variables involved generally makes computation infeasible. The same difficulty persists when only an approximate solution is being sought by linear programming.
Dynamics of Haematopoietic Stem Cells Model
Julia Stoberova
Communications - Scientific Letters of the University of Zilina 2012, 14(3):78-83 | DOI: 10.26552/com.C.2012.3.78-83
The article deals with the haematopoietic stem cells model with delay introduced by M. C. Mackey [1]. Our aim is to establish the new conditions under which the equilibria of the model are stable or unstable. The model without delay is also investigated.