Communications - Scientific Letters of the University of Zilina, 2021 (vol. 23), issue 1
Operation and Economics in Transport
Assessing the Energy Efficiency of an Electric Car
František Synák, Matej Kučera, Tomáš Skrúcaný
Communications - Scientific Letters of the University of Zilina 2021, 23(1):A1-A13 | DOI: 10.26552/com.C.2021.1.A1-A13 
Electric car does not supply all the electric energy, obtained from the electric network, to the wheels in the form of mechanical energy. During such a transformation, a part of this energy is lost. The article endeavours to determine the energy efficiency of selected electric car. The electric car used for measurements is not from the batch production since that is a vehicle designed at University of Zilina. The efficiency has been observed while driving under the conditions of amended methodology of New European Driving Cycle (NEDC). The measured value of electric car's efficiency is being analyzed from the energy consumption, as well as emission...
Influence of Selected Factors on Implementation of the PPP Projects in Transport
Beata Zagożdżon, Andrzej Rogowski
Communications - Scientific Letters of the University of Zilina 2021, 23(1):A14-A20 | DOI: 10.26552/com.C.2021.1.A14-A20
Countries seek to use the knowledge and capital of the private sector to minimise the gap between the transport infrastructure needs and the capacity of their budgets. A form of private investor involvement is usually a public-private partnership PPP. However, success in implementing the PPP projects requires appropriate economic, legal and institutional conditions. The article presents results of research aimed at identifying the PPP success factors in Poland and assessing the strength of impact of individual factors on the implementation of projects. An analysis of the subject literature was carried out, based on which the success factors were determined....
The Transport Service of Small Towns
Jozef Gnap, Jana Kupčuljaková, Ľubomír Černický, Grzegorz Dydkowski
Communications - Scientific Letters of the University of Zilina 2021, 23(1):A21-A31 | DOI: 10.26552/com.C.2021.1.A21-A31
The paper is focused on assessment of the transport services in small towns. Current legislation in the Slovak Republic, however, does not clearly determine which cities must provide the urban public transport (UPT). Analysis of the current state of the UPT evaluated 71 district towns of the SR and it was found out that 21 towns did not provide operation of the UPT. Another criterion for evaluation was the number of inhabitants of the city over 10,000 in Slovakia and selected regions of the Czech Republic and Poland. The paper presents results of a research conducted in the area of a transport operation, along with a proposal for the content of the...
Analysis of Transportation Companies in the Czech Republic by the Kohonen Networks - Identification of Industry Leaders
Jakub Horák, Petr Šuleř, Jaromír Vrbka
Communications - Scientific Letters of the University of Zilina 2021, 23(1):A32-A43 | DOI: 10.26552/com.C.2021.1.A32-A43
Computational models of artificial neural networks are currently used in different areas. Accuracy of results exceeds the performance of traditional statistical techniques. Artificial neural networks as the Kohonen map may be used e.g. to identify industry leaders, thus replacing the traditional cluster analysis and other methods. The aim of this contribution is to analyse the transportation industry in the Czech Republic by the Kohonen networks and identify industry leaders. The data file contains results - division of companies into a total of 100 clusters. Each cluster is subjected to analysis of absolute indicators and several parameters, average,...
Modelling of the Traffic Flow Basic Characteristics at the Road Network Selected Section
Alica Kalašová, Simona Skřivánek Kubíková, Veronika Harantová
Communications - Scientific Letters of the University of Zilina 2021, 23(1):A44-A53 | DOI: 10.26552/com.C.2021.1.A44-A53
Elimination of connection between an increase in transport and economic growth has been the main aim of the transport policy of the EU for a few years and it has not been accomplished yet. Transportation causes considerable external costs that have concrete originators but are not paid by them. The biggest external costs are connected with emissions, noise, accidents and congestions. In this contribution, the problem of congestions, which currently bother drivers in EU was analysed, together with possibilities for their solving, since the congestions' reduction is one of the priorities of the EU's transport policy. The task was to observe a relation...
Consolidation of Cargos in the Road Transport as a Key Method to Success
Zbigniew Łukasik, Aldona Kuśmińska-Fijałkowska, Jacek Kozyra, Sylwia Olszańska
Communications - Scientific Letters of the University of Zilina 2021, 23(1):A54-A61 | DOI: 10.26552/com.C.2021.1.A54-A61
The problem of consolidation of goods for the provider of logistic services, which is a third part that delivers goods from many suppliers to one business client in time horizon was analysed in this article. Every parcel has a fixed date of reception in the source and delivery schedule in a destination. In the age of highly developed economy, time pressure and costs, outsourcing is a condition necessary to improve the functioning of enterprises. New logistic chains, networks of terminals and intermodal connections are built every year to reduce the transport costs and improve the whole process. In this article, the authors presented the benefits resulting...
Optimisation of Distribution Routes: A Case Study
Rudolf Kampf, Martina Hlatká, Patrik Gross
Communications - Scientific Letters of the University of Zilina 2021, 23(1):A62-A73 | DOI: 10.26552/com.C.2021.1.A62-A73
This article focuses on optimisation of the distribution routes for a company that produces carpets, floor coverings and tapestries. The optimisation process is based on operational research methods including, without limitations, Mayer's method and the single linkage method. The obtained results are subsequently compared to the current situation and evaluated in terms of time and costs. The conclusion provides the optimised economic solution.
Mechanical Engineering in Transport
Influence of the Load Distribution and Sizes on the Wheel Geometry in Passenger Cars
Jarosław Gonera, Jerzy Napiórkowski, Kamil Ciborowski
Communications - Scientific Letters of the University of Zilina 2021, 23(1):B1-B12 | DOI: 10.26552/com.C.2021.1.B1-B12
This paper discusses impact of changes in the load size and distribution in passenger cars on geometry of the suspension and steering systems. It was found to have a major impact on the road safety. The research was carried out with the four most popular suspension system designs used in modern passenger cars, i.e. multi-link suspension on both front and rear axles, only on the front axle, only on the rear axle and a simple suspension design for both front and rear axles. Eight load variants were used for the tests. Changes in the following wheel geometry parameters were identified: toe-in and camber angles of all the wheels and castors for the front...
Analysis of Traffic Noise in Two Cross-Sections at the Road Crossing The City
Andrzej Bąkowski, Leszek Radziszewski
Communications - Scientific Letters of the University of Zilina 2021, 23(1):B13-B21 | DOI: 10.26552/com.C.2021.1.B13-B21
The paper presents an analysis of the noise recorded by the two road traffic noise-monitoring stations. The stations were located in Kielce, Poland, at the road No. 74: on the outskirts of the city and near the center. Based on the experimentally recorded data, an equivalent sound level and acoustic pressure were determined for three sub-intervals of the day: nights, days and evenings. The conducted analyses showed that the average annual values (depending only on the time sub-intervals) of the median do not differ significantly between stations. A similar conclusion can be drawn based on simulations of the median and the C90 percentile of the sound...
Dynamic Properties and Wear Analysis of a Rail Vehicle with Wheels' Self-Lubricating Coatings
Rafał Melnik, Andrzej Chudzikiewicz, Seweryn Koziak, Michał Opala, Ján Dižo
Communications - Scientific Letters of the University of Zilina 2021, 23(1):B22-B32 | DOI: 10.26552/com.C.2021.1.B22-B32
The problem of wheel and rail wear in railway transport generates costs of reprofiling and availability of vehicles and infrastructure. One of the possibilities of wear minimizing is decreasing of the friction coefficient in wheel-rail contact by means of lubricants. Such a solution has drawbacks from which the most crucial are: decrease of tractive/braking forces and difficulties with the precise spreading of the lubricant. These disadvantages may be avoided by modern, innovative self-lubricating coatings, applied at the production stage on the wheel flanges. The aim of the study is to investigate the effect of self-lubricating coatings on a rail...
Modelling of Critical Velocities of the Cardan Mechanism using Transfer Matrix Method
Petr Hrubý, Tomáš Náhlík
Communications - Scientific Letters of the University of Zilina 2021, 23(1):B33-B38 | DOI: 10.26552/com.C.2021.1.B33-B38
The presented paper focuses to rotating components of mechanical constructions. The problem of the spatial combined bending-gyratory vibration and calculation of the Eigen frequencies is studied. The model of Cardan Mechanism is solved by the transfer matrix method. Transfer matrices were derived for shaft, concentrated mass and elastic bearing. The physical and mechanical properties of each part of the mechanism are hidden in these matrices. A procedure for calculating Eigen frequencies was proposed.
An Example of Reparatory Surface Welding of the Mining Machine Vital Part
Dušan Arsić, Ružica Nikolić, Vukić Lazić, Srbislav Aleksandrović, Ljubica Radović, Nada Ilić, Branislav Hadzima
Communications - Scientific Letters of the University of Zilina 2021, 23(1):B39-B45 | DOI: 10.26552/com.C.2021.1.B39-B45
Mining machines' components, or the whole structure, are prone to frequent premature damages and fractures what is explained either by inadequate design and construction or by insufficient knowledge of the material's and welded joints' properties and oversights in manufacturing. Here is considered the bucket-wheel excavator, i.e. the fracture of the tooth of the girth gear, which enables the circular motion of the excavator's upper structure (which was in operation for 5000 hours). The gear was made of the cast steel GS 40 MnCrSi3 V. The reparatory hard-facing (HF) technology of the fractured tooth required specification of numerous operations including...
Development of a Method for Diagnosing Injectors of Diesel Engines
Ildar Gabitov, Andrei Negovora, Shamil Nigmatullin, Arseny Kozeev, Mahmut Razyapov
Communications - Scientific Letters of the University of Zilina 2021, 23(1):B46-B57 | DOI: 10.26552/com.C.2021.1.B46-B57
The purpose of this study was to improve the diagnostics efficiency of modern diesel engine injectors with electronic controls. Experimental studies, performed using certified specialized equipment of injectors' manufacturers and standard software packages for data analysis, made it possible to prove adequacy of theoretical research and get results that are more accurate. Those results contribute to development of a software product that allows identifying a particular faulty element during the defective injector's operation by using mathematical processing of the diagnostic data obtained when testing the injector. Thus, the time spent to repair the...
Calculation of the Vehicles Stress-Deformed State while Transporting the Liquid Cargo
Oleksii Grevtsev, Ninel Selivanova, Pavlo Popovych, Liubomyr Poberezhny, Oksana Shevchuk, Igor Murovanyi, Andrii Hrytsanchuk, Liubov Poberezhna, Vasyl Zapukhliak, Galyna Hrytsuliak
Communications - Scientific Letters of the University of Zilina 2021, 23(1):B58-B64 | DOI: 10.26552/com.C.2021.1.B58-B64
To calculate the stress-deformed state of road-tanker metal structures during the liquid cargo transportation, the solution for bending axially and symmetrically loaded circular plates is proposed, which is based on the theory of elasticity approach. Dependencies for calculating stresses and displacements under arbitrary load law and support type are substantiated. Deformation of the support under the action of axisymmetric loading leads to appearance of a temperature field.
Use of the Bezier Curves for a Vehicles Driving Cycles' Modeling
Valerii Dembitskyi
Communications - Scientific Letters of the University of Zilina 2021, 23(1):B65-B75 | DOI: 10.26552/com.C.2021.1.B65-B75
While performing the research of the vehicles operating characteristics in real operating conditions, a question of creation or correction of a movement driving cycle always appears. An absence of a mathematical model rather complicates the research process and makes a quick correction of movement conditions impossible. To solve the given problem, it was proposed to model a driving cycle using the Bezier curves. As a result of this research, it is stated that the most advantageous is to use the Bezier curves of the second and third degrees. During the analysis of results of driving cycles modeling and their comparison to the standardized and real movement...
Electrical Engineering in Transport
Design and Construction of High-Quality Capacitor for High Frequency and Power Application
Martin Zavřel, Vladimír Kindl, Tomáš Kavalír, Pavel Drábek
Communications - Scientific Letters of the University of Zilina 2021, 23(1):C1-C6 | DOI: 10.26552/com.C.2021.1.C1-C6
The paper proposes a design and construction of a special plated capacitor exhibiting very good high-frequency characteristics. The capacitor is designed to minimize the parasitic parameters like ESR (equivalent series resistance) and ESL (equivalent series inductance) and to be suitable for power industry applications. The paper describes the fabrication process and discusses technical issues related to technology of manufacturing and assembling. It also provides an experimental verification and the quality evaluation based on frequency characteristics compared to existing commercial high-quality capacitor.
Optimized Control of Energy Flow in an Electric Vehicle based on GPS
Matúš Danko, Branislav Hanko, Peter Drgoňa
Communications - Scientific Letters of the University of Zilina 2021, 23(1):C7-C14 | DOI: 10.26552/com.C.2021.1.C7-C14
Presented paper deals with energy flow control of an electric vehicle with multiple energy storages. For efficiency control of energy flow is necessary to know the traction profile of the route. The Global Positioning System is used for observation of the traction profile. The first of the proposed algorithms uses the whole traction profile of a predetermined route, so the control algorithm can determine when the use of energy of the secondary energy storage is useful. The second proposed algorithm uses the GPS to determine the traction profile from routes stored in memory. If the route is not predetermined, or found in the memory of stored routes,...
Estimating the Position of an Image with Unknown Intensity Shape
Yury E. Korchagin, Viacheslav N. Vereshchagin, Alexander V. Terekhov, Kirill A. Melnikov
Communications - Scientific Letters of the University of Zilina 2021, 23(1):C15-C22 | DOI: 10.26552/com.C.2021.1.C15-C22
The problem considered is to estimate the image position of a spatially extended object. It is assumed that the shape of the image intensity is a priori unknown, but it can be predicted with some error. In order to synthesize the estimate of the image position, the quasi-likelihood version of the maximum likelihood method is used. Behavior of the signal function in the neighborhood of the real image position is studied. Characteristics of the resulting estimate, such as bias and dispersion, are found by means of the local Markov approximation method. Influence of non-uniformity of the received image intensity upon the estimate accuracy is demonstrated...
Civil Engineering in Transport
Technical Feasibility of Deceit While a Vehicle is Weighed in Motion with a Very Low Speed
Zbigniew Lozia
Communications - Scientific Letters of the University of Zilina 2021, 23(1):D1-D14 | DOI: 10.26552/com.C.2021.1.D1-D14
The study concerns the problem of overloading the vehicles driven on public roads. The gross vehicle mass and individual axle loads are limited by legal regulations. However, a tricking method, applicable to most popular designs of motor vehicles and multiaxial tractor-semitrailer units, has been shown that the weighing inspectors, even if provided with precise scales, may be deceived without any interference in the scale operation. In such a method, the current vehicle state may be changed by modifying the stiffness of individual pneumatic suspension springs, which is now technically feasible. The author used two authorial vehicle models and a simulation...
Method of the Finite-Element Model Formation Containing the 3D Elements for Structural Calculations of the Reinforced Concrete Structures Considering the Crack Opening
Sergei N. Nazarenko, Galina A. Grudcina
Communications - Scientific Letters of the University of Zilina 2021, 23(1):D15-D25 | DOI: 10.26552/com.C.2021.1.D15-D25
This article presents the 3D computational modeling method for reinforced concrete structures. An example of calculation of the reinforced concrete beam, using the Finite Element Method in SCAD++ following proposed algorithm, is given. Results comparison to the analytical calculation of the model with selected reinforcement is presented. For concrete, the 3D solid Finite Elements are used and the 3D beam elements for reinforcement. The model is formed using AutoCAD and AutoLISP, which creates a text data file in SCAD format for the description of model. In addition, computation of the 3D model of the crossbar with a crack is performed. Crack sizes...
Management Science and Informatics in Transport
Improving Initial Population for Genetic Algorithm using the Multi Linear Regression Based Technique (MLRBT)
Esra'a Alkafaween, Ahmad B. A. Hassanat, Sakher Tarawneh
Communications - Scientific Letters of the University of Zilina 2021, 23(1):E1-E10 | DOI: 10.26552/com.C.2021.1.E1-E10
Genetic algorithms (GAs) are powerful heuristic search techniques that are used successfully to solve problems for many different applications. Seeding the initial population is considered as the first step of the GAs. In this work, a new method is proposed, for the initial population seeding called the Multi Linear Regression Based Technique (MLRBT). That method divides a given large scale TSP problem into smaller sub-problems and the technique works frequently until the sub-problem size is very small, four cities or less. Experiments were carried out using the well-known Travelling Salesman Problem (TSP) instances and they showed promising results...
Study on the Vehicle Linear Dynamic Interval in a Traffic Flow
Oleg Fyodorovich Danilov, Victor Ivanovich Kolesov, Denis Alexandrovich Sorokin, Maxim Leonidovich Gulaev
Communications - Scientific Letters of the University of Zilina 2021, 23(1):E11-E22 | DOI: 10.26552/com.C.2021.1.E11-E22
The transportation industry of a modern city involves the effective systems for the road traffic management. To manage any object is impossible without understanding its specifics. The tasks of road traffic management are based on mathematical models of traffic flows. The "following the leader" model based on the linear dynamic interval of vehicles has become widely accepted in the model analysis. The paper discusses the mathematical model of the linear dynamic interval of vehicles; the model is identified structurally and parametrically. Coefficients of the model are analyzed in detail; a generalized assessment of the dynamic performance of the traffic...
Safety and Security Engineering in Transport
"Road Safety Sequence" - A New Concept of the Road Safety Management in Poland
Andrzej Szymanek
Communications - Scientific Letters of the University of Zilina 2021, 23(1):F1-F10 | DOI: 10.26552/com.C.2021.1.F1-F10
The article shows a fragment of the results of the author's concept of road safety management in Poland. The article shows the "program sequence" of the construction action of road safety management system in Poland. The main component of this "sequence" of actions to improve the road safety - should be the "road risk management model". It should be widely used in Poland as an element of knowledge and practices of international road safety management. It is primarily about the model of the Office for Land Transport Safety Authority in New Zealand adopted by the EU in its road safety policy. The article also presents other components of the author's...
Safety of Operation and Maintenance Activities of Rolling Stocks by the Example of Electric Multiple Units EN96
Artur Kalinowski, Norbert Radek, Jozef Bronček
Communications - Scientific Letters of the University of Zilina 2021, 23(1):F11-F19 | DOI: 10.26552/com.C.2021.1.F11-F19
This paper deals with importance of executing maintenance activities of rolling stocks by the example of the electric multiple unit EN96 series and with influence of repairing rolling stocks on the transport safety. It also discusses Poland's Supreme Audit Office report for the 2017 year that concerns the condition of safety of the rail transport in Poland. It describes the way in which the maintenance operations are performed with a division of the maintenance levels that depend of time of utilization and distance travelled by a vehicle.
Optimal Route Determination to provide Relief Following an Earthquake using the Traffic Density Ratio (Case Study: Isfahan's Fire Stations)
Seyed Ahmad Almasi, Mohammad Mehdi Khabiri, Mehdi Fallah Tafti, Meisam Akbarzadeh
Communications - Scientific Letters of the University of Zilina 2021, 23(1):F20-F32 | DOI: 10.26552/com.C.2021.1.F20-F32
Despite the very important role of primary arteries and transportation network in providing relief for regions affected by an earthquake and black spots, they have received less attention. Therefore, in the current study, at first, the status quo of the traffic black spots and safe regions was identified to predict the movement direction, evacuation of residents from their habitat and temporary residence using the region zoning. The trips were assigned to the network based on the trip distribution matrix and their relevant travel times both related to the crisis state. The results indicated that out of 94 traffic regions, located in the area under...