Communications - Scientific Letters of the University of Zilina, 2015 (vol. 17), issue 4
Articles
Hydroxyl Radical Induced Ultra-Weak Photon Emission from Tyrosine Solutions
Martin Bereta, Michal Cifra, Katerina Cervinkova, Ladislav Janousek, Jan Barabas
Communications - Scientific Letters of the University of Zilina 2015, 17(4):3-7 | DOI: 10.26552/com.C.2015.4.3-7 
This paper deals with ultra-weak photon emission (UPE) from aqueous tyrosine solutions induced by hydroxyl radical. The physical nature of this specific phenomenon is presented and the proposed mechanism of its origin during oxidation of tyrosine is described. The experimental part of the work is focused on the measurements of intensity of ultra-weak photon emission from different solutions of tyrosine. The emission from solutions with and without presence of hydroxyl radical is analyzed. The results confirm the assumption that the highest intensity is detected from the solution of tyrosine, hydrogen peroxide and ferrous sulphate heptahydrate, likely...
Evaluation of Algorithms for Identification of Minimal Cut Vectors and Minimal Path Vectors in Multi-State Systems
Miroslav Kvassay, Jozef Kostolny
Communications - Scientific Letters of the University of Zilina 2015, 17(4):8-14 | DOI: 10.26552/com.C.2015.4.8-14
Minimal Cut Vectors (MCVs) and Minimal Path Vectors (MPVs) are one of the key concepts of reliability analysis. They allow us to estimate system availability or to analyze influence of individual system components on the entire system. However, the main problem of their use, especially in reliability analysis of complex systems, lies in their identification. Several algorithms have been proposed to solve this task. Some of the most universal ones are based on logical differential calculus. These algorithms use integrated direct partial logic derivatives to find situations that can correspond to the MCVs (MPVs) and a special type of logic conjunction...
Comparison of Experimental Results with Numerical Solution of Thermal Stress Analysis
Zuzana Stankovicova, Vladimir Dekys, Leszek Radziszewski, Milan Uhricik, Milan Sapieta
Communications - Scientific Letters of the University of Zilina 2015, 17(4):15-20 | DOI: 10.26552/com.C.2015.4.15-20
This paper presents experimental measurement of the first stress invariant on the plate with hole at fatigue testing machine due to adiabatic elastic deformation. The theoretical part is concentrated on the theory of thermal stress analysis focusing on thermoelastic analysis. The experimental part is dedicated to the postprocessing of the measured data including analytical and numerical solutions for the plate with hole using finite element method (FEM).
Evaluation of Wagon Impact Tests by Various Measuring Equipment and Influence of Impacts on Cargo Stability
Jan Zamecnik, Juraj Jagelcak
Communications - Scientific Letters of the University of Zilina 2015, 17(4):21-27 | DOI: 10.26552/com.C.2015.4.21-27
This article deals with impact tests of wagons, evaluation of impacts from various measuring equipment and influence of impacts on cargo motion in the wagons when various manners of cargo securing were used. The accelerations generated during impacts were observed also by monitoring units designed for monitoring of transport and by recordings from cameras GoPro Hero. Instead of observing the influence of impacts on the cargo loaded in impacting wagons, the function of the monitoring units in a closed building with not very good GPS signal was also observed.
Assessment of Track Quality in Trial Test Sections by Spot and Continuous Method
Michal Smalo, Libor Izvolt
Communications - Scientific Letters of the University of Zilina 2015, 17(4):28-33 | DOI: 10.26552/com.C.2015.4.28-33
The quality of track alignment and track geometry is an essential precondition of safe and economical operation of railway track. The paper provides an analysis of diagnostics of relative track geometry parameters and evaluation of measurement deviations carried out by the spot and continuous method in sections of the ballasted track, transition areas and sections with the slab track structure.
Simple Model of Pellet Combustion in Retort Burner
Jozef Micieta, Jiri Hajek, Jozef Jandacka
Communications - Scientific Letters of the University of Zilina 2015, 17(4):34-39 | DOI: 10.26552/com.C.2015.4.34-39
Combustion of the solid fuel in the burner is an important issue when discussing the CFD simulation of combustion in automatic boiler. In the present work is employed a simplified method for modeling the fuel bed, which is based on mass and heat balances in order to simplify the simulation of combustion in pellet boiler. The model for solid fuel combustion in a burner is created for the purpose of automatic boiler simulations. Such approach does not require a detailed bed model of fired solid fuel. A simple model of the bed can be very useful for designers and engineers of automatic boilers. The described approach to modeling the combustion process...
Analysis of Dynamic Properties of Accelerometer Using Fractional Derivatives
Miroslaw Luft, Daniel Pietruszczak, Elzbieta Szychta
Communications - Scientific Letters of the University of Zilina 2015, 17(4):40-44 | DOI: 10.26552/com.C.2015.4.40-44
The paper outlines the use of fractional derivatives for dynamic measurements while developing a method of improved description of dynamic properties of accelerometer, which the authors consider to be the original and unique achievement of their work. The main objective of the work is an implementation of a fractional calculus-based method which allows for a description of dynamic properties of signal processing of measuring transducers with fractional orders. A dynamics of transducer is identified by the ARX method (AutoRegressive with EXternal input identification method). Identification of accelerometer was accomplished with the use of the MATLAB&Simulink...
Modelling and Simulations of Dynamics of the Low-Floor Tramcar with Independently Rotating Wheels
Andrzej Chudz, Magdalena Sowinska
Communications - Scientific Letters of the University of Zilina 2015, 17(4):45-52 | DOI: 10.26552/com.C.2015.4.45-52
The article is devoted to the analysis of numerical simulation results of the tramcar dynamics. It presents the mathematical model of the one section of the low-floor tram with the bogie with independently rotating wheels. The simulations were performed according to different scenarios, connected with the track geometry, which seem to be dangerous for the tram behaviour e.g.: curving, gauge narrowing, track buckling, etc. Special attention was paid to wheel lateral displacement and forces occurring in wheel-rail contact. The simulation results reveal characteristic features of such an unconventional system of the tram, which can often demonstrate dynamics...
Proposal of Model for Effective Management of Cooperation Activities in Slovak Companies
Josef Vodak, Jakub Soviar, Viliam Lendel, Michal Varmus
Communications - Scientific Letters of the University of Zilina 2015, 17(4):53-59 | DOI: 10.26552/com.C.2015.4.53-59
Aim of this article is to offer a proposal for effective planning and organization of cooperation activities in a company, based on a comprehensive analysis of scientific literature and performed empirical research in Slovak republic. The article thus provides a tool for company managers for managing their cooperation activities. Use of this tool is meant to help minimize occurrence of conflict situations and to support smooth progress of cooperation activities from the organizational and planning perspective.
Method of Identifying the Real State of the Counter Vehicle Based on the Interpretation of Electrical Signals
Pawel Olszowiec, Miroslaw Luft
Communications - Scientific Letters of the University of Zilina 2015, 17(4):60-64 | DOI: 10.26552/com.C.2015.4.60-64
The article presents the analysis of electrical signals and system reports of motor vehicles in which the mileage counter indication has been questioned under service conditions as compared to the vehicles mechanical wear and tear. The essence of the aforementioned deliberations is an attempt at determining the universal procedures allowing for obtaining data concerning the actual vehicle mileage. Search for the intended method results from many factors functioning on the used motor vehicle market. The major factor is the uncontrolled safety level on the roads among the road users and, equally important, financial frauds in the area of motor vehicle...
Destructive Testing of the Weld Joints on Split Sleeve for Branch Connections Repairs
Marek Patek, Augustin Sladek, Milos Mician
Communications - Scientific Letters of the University of Zilina 2015, 17(4):65-69 | DOI: 10.26552/com.C.2015.4.65-69
New type of repairing technology for branch connection defects on gas pipelines has been designed recently. Repairing technique is based on manufacturing of split sleeve and welding of its parts together and to the repaired pipes by manual metal arc welding technology. Appropriate testing has to be performed to ensure practical and permanent use of such kind of sleeve in commercial area. Destructive testing was performed to confirm quality of the welds on the prototype sleeve repair. Macrostructural and hardness evaluation showed inhomogeneity present in some welds. According to that, microstructure observations, spectral analysis and mechanical tests...
Usage of 3-D Based Methods for the Detection of Aggregate Microtexture
Zuzana Florkova
Communications - Scientific Letters of the University of Zilina 2015, 17(4):70-74 | DOI: 10.26552/com.C.2015.4.70-74
Some of the available advanced three-dimensional based methods for measurement of microtexture have been described. These methods are generally divided into three categories, namely image analysis based methods, laser based methods and photogrammetry methods. Moreover, a particle of aggregate can be captured using a stereomicroscope and using the appropriate software to obtain a 3-D image of investigated aggregate. Software also includes an interactive measurement tool that allows to obtain a profile of aggregate particle. The stereomicroscope method is also presented in the paper. The usage of the microscope for the detection of aggregate microtexture...
Sanctions and Embargoes as a Crisis Response Instrument in the Context of the Ukrainian Crisis
Veronika Orieskova, Jan Havko
Communications - Scientific Letters of the University of Zilina 2015, 17(4):75-80 | DOI: 10.26552/com.C.2015.4.75-80
The paper analyzes the importance of sanctions and embargoes as a tool used by organizations of international crisis management to resolve large-scale crisis events in a peaceful way. The attention is paid to one of these crisis events, the Ukrainian crisis. On the basis of value selected parameters, which are the change of exchange rates and inflation growth in particular countries, it reviews their impact on both stakeholders, namely the countries of the European Union and the Russian Federation.
Extendingof the Life of Active Parts of Cold-Moulding Tools
Jan Moravec
Communications - Scientific Letters of the University of Zilina 2015, 17(4):81-84 | DOI: 10.26552/com.C.2015.4.81-84
Heat treatment of active components of cold-moulding tools is a necessary operation to guarantee their functionality. The tools made by this method lost required quality of durability and period of service and losses caused by their frequent exchange are high. One way we can stop it is by coating the active parts of pressing tools by thin, hard and abrasion resistant deposit that is suitable by definite method of the tool stress.
Selection of Suitable Urban Tolling System Technology
Karol Hrudkay
Communications - Scientific Letters of the University of Zilina 2015, 17(4):85-90 | DOI: 10.26552/com.C.2015.4.85-90
Article deals with the selection of suitableselection urban tolling system technology. In the paper, a lot of aspects, which have an influence on selection of particular technology in city conditions, were considered. For example: charging policy, user aspects, technical aspects and economic aspects. Although the analysis was not performed within specific conditions of a particular city, it was found out that in spite of general analysis, it is possible to form relevant and rather clear conclusions.