Communications - Scientific Letters of the University of Zilina, 2018 (vol. 20), issue 3
Operation and Economics in Transport
Determination of Time Savings for Passengers by Applying the Public Passenger Transport Preference in Cities
Jozef Gnap, Jana Kupculjakova, Stefania Semanova
Communications - Scientific Letters of the University of Zilina 2018, 20(3):3-8 | DOI: 10.26552/com.C.2018.3.3-8 
The paper deals with the issue of delays of public transport vehicles at the signal controlled junctions. Based on the road traffic survey results, the average values of vehicle delays were determined. By using those values, it is possible to define time savings for the vehicles and mainly for passengers that are transported. The time savings were determined based on the relationships and coefficients defined in this paper.
Influence of Driving Fluency on Economic and Ecological Aspects of Transport
Oldrich Hyks, Kristyna Neubergova, Pavel Pribyl
Communications - Scientific Letters of the University of Zilina 2018, 20(3):9-14 | DOI: 10.26552/com.C.2018.3.9-14
The paper is focused on the influence of driving behaviour on fuel consumption and the subsequent environmental impacts. The main issue is to estimate the economic and environmental costs connected with the forced deceleration or stopping and the subsequent acceleration of a motor vehicle in urban traffic. Authors introduce a physical model of a vehicle with variable parameters that allows the calculation of economic and ecological losses in congestions on the basis of data generated by an arbitrary floating car. The losses include the lost kinetic energy of a vehicle during the forced braking, accelerated degradation of vehicle components, the loss...
Mechanical Engineering in Transport
Influence of the Titania Content on the Microstructure and Properties of Plasma Sprayed Alumina-Titania Coatings
Anna Goral, Wojciech Zorawski, Otakar Bokuvka
Communications - Scientific Letters of the University of Zilina 2018, 20(3):15-18 | DOI: 10.26552/com.C.2018.3.15-18
The composite alumina-titania coatings have been widely used in industry fields to protect metallic components from wear, corrosion and thereby prolonging their service time. This paper presents an analysis of the microstructure and mechanical properties of Al2O3-TiO2 composite coatings, plasma sprayed on steel substrates from feedstocks containing various concentrations of the TiO2 powder. The coatings revealed lamellar microstructure, formed by the rapid solidification of molten droplets of the powder on previously deposited splats. The main phase identified in the coatings was γ-Al2O3 phase, the others were TiO2 and α-Al2O3, as well...
Resistance of High-Strength Steels to Stress Corrosion Cracking Depending on External Environment pH Factor
Petr Jonsta, Irena Vlckova, Zdenek Jonsta, Vladimir Tomasek, Tatana Fenclova
Communications - Scientific Letters of the University of Zilina 2018, 20(3):19-23 | DOI: 10.26552/com.C.2018.3.19-23
The paper deals with the study of stress corrosion cracking of high-strength steels in an aqueous environment with a varying pH factor ranging from 5.5 to 12.0. Steels were studied after quenching and tempering, one of the steels was prone to temper embrittlement. Single-edge notched pre-cracked specimens were used for the experiments. Changes in the pH factor at the crack tip were measured using an antimony electrode. The pH factor values at the crack tip dropped to 2.0. Steel prone to temper embrittlement showed significantly shorter incubation period and more accelerated development of corrosion process compared to the optimized heat treatment of...
Electrochemical Characterization of Az31 Magnesium Alloy Treated by Ultrasonic Impact Peening (Uip)
Daniel Kajanek, Branislav Hadzima, Filip Pastorek
Communications - Scientific Letters of the University of Zilina 2018, 20(3):24-29 | DOI: 10.26552/com.C.2018.3.24-29
Electrochemical characteristics of AZ31 magnesium alloy after impacting by ultrasonic impact peening (UIP) were measured in order to evaluate its effect on corrosion resistance of mentioned alloy. For this purpose, potentio-dynamic polarization (PD) tests and electrochemical impedance spectroscopy (EIS) of ground and impacted samples were performed in 0.1 M NaCl solution at the temperature of 22±2 °C after 5 minutes of potential stabilization. The obtained PD curves were analysed using the Tafel extrapolation method and data from EIS measurements in form of Nyquist plots were quantified by the equivalent circuit method. The results showed clearly...
Optimization of Parameters of a Planetary Gearbox Using the Taguchi-Grey Relational Analysis
Slavica Miladinovic, Sandra Velickovic, Blaza Stojanovic, Ruzica Nikolic
Communications - Scientific Letters of the University of Zilina 2018, 20(3):30-35 | DOI: 10.26552/com.C.2018.3.30-35
Optimization of parameters of central gears of a planetary gearbox was performed in this study. Since the optimization of multi-performance characteristics is more complex compared to optimization of a single-performance characteristics, the Taguchi-Grey analysis was used. That approach combines the Taguchi orthogonal array L27 with the Grey relational analysis to determine the influence of the material, module and gear width on the safety coefficient of the planetary gearbox. A Grey relational grade obtained from the Grey relational analysis is used as the performance characteristics in the Taguchi method and Analysis of variance (ANOVA). The optimal...
Reduction of the Local Stress Field around Holes through Porous Shaped Structures
Stefano Monti
Communications - Scientific Letters of the University of Zilina 2018, 20(3):36-41 | DOI: 10.26552/com.C.2018.3.36-41
Geometrical discontinuities in mechanical components are detrimental for the mechanical properties of the product itself. Actually, in proximity of such features, the stress increases due to the stress concentration factor, that in the case of a circular hole is equal to 3. Several solutions have been proposed to reduce the stress concentration value. In the present article, the application of a particular porous pattern that can be obtained by laser cutting with the appropriate finishing requirements is introduced in order to modify the local stress field and reduce the stress concentration value near the hole boundary.
Numerical CFD Analysis of an Aerodynamic Head Cover of a Rotorcraft Motor
Katarzyna Szwedziak, Tomasz Lusiak, Zaneta Grzywacz, Kacper Drozd
Communications - Scientific Letters of the University of Zilina 2018, 20(3):42-47 | DOI: 10.26552/com.C.2018.3.42-47
Autogyros can become an alternative for the use of rotorcrafts in various fields of life, including agroforestry. They have better economic performance than helicopters, owing to, among other things, the presence of a bearing rotor. Most autogyros also have other advantages in terms of no need for the compliance with stringent regulatory regulations - with respect to new constructions, lower combustion, noise and emissions of toxic elements. The cover of the bearing rotor head is an important element of rotorcrafts, which demonstrates that aerodynamics plays an important role in aerodynamic designs. Therefore, in this article, air flow model testing...
Influence of Surface Roughness on the Cavitation Wear of P265GH and X2CrNi18-9 Steel Cavitation Generators
Tomasz Linek, Tomasz Tanski, Wojciech Borek
Communications - Scientific Letters of the University of Zilina 2018, 20(3):48-54 | DOI: 10.26552/com.C.2018.3.48-54
The aim of this paper was to determine the effect of surface roughness of cavitation generators made from two different materials: P265GH steel, with a ferritic-pearlitic structure, and X2CrNi18-9 (304L) steel with an austenitic structure on the mass loss and cavitation wear. Cavitation generators were tested in the conditions of cavitation wear environment continuously for 500 PMHs in a specially designed and constructed author's stream and flow device. Based on the carried out experiments was confirmed that the highest mass loss - 0.1752 g is seen for a sample of P265GH steel wet sanded with paper with the grain size of 1000. The smallest mass loss...
Electrical Engineering in Transport
Design of CNC Device Designed for Automation of the Application of Viscous Materials
Peter Drgona, Rastislav Stefun, Lubomir Stefke
Communications - Scientific Letters of the University of Zilina 2018, 20(3):55-60 | DOI: 10.26552/com.C.2018.3.55-60
This article deals with the design and practical realization of a CNC device designed for the application of viscous materials, such as a thermal conducting paste. Nowadays, growing trend of usage of electronic circuits in transportation systems is observed. Switched mode power supplies are widely used in all types of means of transport and their infrastructure. For correct operation of power converters, produced heat must be dissipated. Thermal conducting paste is used for better heat dissipating but its application on surface can be an issue. Designed CNC device serves for easier and more accurate application in production process in transport industry.
Civil Engineering in Transport
Compaction Density Determination of the Road Asphalt Layers
Denisa Cihlarova, Petr Mondschein, Silvia Capayova
Communications - Scientific Letters of the University of Zilina 2018, 20(3):61-66 | DOI: 10.26552/com.C.2018.3.61-66
This paper analyses the destructive and non-destructive methods for checking the degree of compaction of asphalt layers and their multi-criteria evaluation. The data obtained during laying of ACO 11+50 mm thickness was selected for the analysis. The bulk density was determined by using probes Troxler 3440, Troxler 2701 and from the drill cores in these given locations. According to the analysis accuracy, the probe Troxler 2701 used to determine the final degree of compaction of the construction asphalt layer and for the routine control of compaction is not suitable, even though when applying AHP (Analytic Hierarch Process) it was assessed as the second...
Optimisation of Transition Areas between Ballastless Track and Ballasted Track in the Area of the Tunnel Turecky Vrch
Libor Izvolt, Jozef Harusinec, Michal Smalo
Communications - Scientific Letters of the University of Zilina 2018, 20(3):67-76 | DOI: 10.26552/com.C.2018.3.67-76
The paper follows previously published papers in Communications - Scientific Letters of the University of Zilina No. 4/2014, No. 4/2015 and No. 4/2016, where were presented the results of the diagnostics of the track geometry of the experimental sections surrounding the portals of a new building of the Tunnel Turecky vrch. Based on the data obtained by comprehensive diagnostics, there can be stated that the problematic section in the slab track are the transition areas allowing the transfer of the vehicle between the line structures with a different bending stiffness. The comprehensive diagnostics was realised by the continuous method (measuring trolley...
Quantitative Land Suitability Mapping for Crop Cultivation
Svitlana Kokhan, Antonina Moskalenko, Oleg Drozdivskyi
Communications - Scientific Letters of the University of Zilina 2018, 20(3):77-83 | DOI: 10.26552/com.C.2018.3.77-83
Developing the structure of geodatabase and knowledge base to provide quantitative mapping of land suitability for cultivation the main crops has been shown in the research. The general model and catalogs of knowledge base were designed that are structuring and formalizing information for creating thematic and complex maps and geomodels. The real world spatial problems give rise to multi-criteria decision-making based on geographical information systems (GIS). The GIS environment provides both aggregation and spatial analysis of various georeferenced data. In this paper, the two approaches of multi-criteria evaluation (MCE) are represented - overlaying...
Management Science and Informatics in Transport
Characteristics of Changes of Transportation Performance for Pairs of Critical Edges
Peter Czimmermann, Michal Kohani
Communications - Scientific Letters of the University of Zilina 2018, 20(3):84-87 | DOI: 10.26552/com.C.2018.3.84-87
When the robustness of a public service system design is tested, we can often use scenarios where possible random failures can occur and they can influence the time the service is accessible which is provided for system users. The construction of a suitable scenario is based on the choice of links of the transportation network which influence the system performance in a substantial way. In such scenarios one or multiple arcs can be affected by this failure. In our contribution we present characteristics of pairs of critical arcs that can be used to develop an algorithm for the creation of critical scenarios.
The Modified Rural Postman Problem in Vehicle Route Optimization
Petr Kozel, Lucie Orlikova, Sarka Michalcova
Communications - Scientific Letters of the University of Zilina 2018, 20(3):88-92 | DOI: 10.26552/com.C.2018.3.88-92
The submitted paper deals with designing routes of the vehicles, which provide the transport network services. We limit our focus to such tasks, where the priority is the edge service in the transport network and the initial problem is finding an Eulerian path. Regarding to real-life problems, this contribution presents such procedure of solving, which takes into account both the existence of a mixed transport network containing one-way roads and the existence of a wider transport network. In this network, there are only selected edges with possibility of the effective passages. This problem can be solved by the modified Rural Postman Problem assuming...