Communications - Scientific Letters of the University of Zilina, 2001 (vol. 3), issue 1
Articles
Natural Gas-Fuelled, Spark-Ignited = 1 /Twc Engine
Michal Takats
Communications - Scientific Letters of the University of Zilina 2001, 3(1):5-10 | DOI: 10.26552/com.C.2001.1.5-10 
Description of the implementation of stoichiometric concept on natural gas-fuelled, spark-ignited engine for co-generation plant (CHP). Description of behavior of closed loop -control system and exhaust gas aftertreatment. Examples of optimization procedure and its results at particular engine concern its environmental properties, power and efficiency. Comparisons are made between the stoichiometric engine and lean burn one.
Contact of Wheel and Rail in Computer Simulation of Vehicle Dynamics and Axle Drive Dynamics
Oldrich Polach
Communications - Scientific Letters of the University of Zilina 2001, 3(1):11-19 | DOI: 10.26552/com.C.2001.1.11-19
In computer simulations different methods are used to calculate tangential wheel-rail forces in vehicle dynamics and in the analysis of traction systems. For the simulation of vehicle dynamics and drive dynamics interaction, the varying methods have to be combined into one method. Using the friction coefficient decreasing with increasing slip velocity between wheel and rail, decreasing part of creep-force function behind the adhesion limit as well as various adhesion conditions can be taken into account in the vehicle dynamics simulations.The proposed method of wheel-rail forces calculation was tested using an ADAMS/Rail model of a four axle locomotive....
An Analysis of a Mobile Vehicle with Dual Run
Vladimir Hlavna, Pavel Fitz, Rastislav Istenik
Communications - Scientific Letters of the University of Zilina 2001, 3(1):20-34 | DOI: 10.26552/com.C.2001.1.20-34
Plane motion of a model vehicle with additional equipment is theoretically solved in this paper. The paper further deals with some questions concerning spatial motion of a dual-run wheel and consequences of such motion. The used method allows changing an arbitrary parameter in a very simple and effective way. The objective of the paper is to compare velocity, mass, stiffness and impact of damping on the vehicle motion. A test stand to measure properties of wheel-track-ground interactions was also designed.
Contribution to the Analysis of Non-Stationary Random Vibration of Vehicles
Milan Saga
Communications - Scientific Letters of the University of Zilina 2001, 3(1):35-43 | DOI: 10.26552/com.C.2001.1.35-43
The goal of the paper is to include non-stationary random vibration excitation into the "classic" statistical solution of vehicles. Other vehicle parameters are the deterministic functions. The non-stationary random function will be modelled by changeable speed of the vehicle and vertical unevenness of track. We shall assume evolutionary Gaussian process. The dynamics of railway vehicle motion will be analysed by the Monte Carlo simulation and the theory of Markov processes.
Test Conditions of Diesel Engine Particulate Emission and the Results Obtained
Jerzy Cisek, Zygmunt Szlachta, Marian Marian Zabłocki
Communications - Scientific Letters of the University of Zilina 2001, 3(1):44-52 | DOI: 10.26552/com.C.2001.1.44-52
In this work, based on experimental results, the effect of four factors of particulate emission measurements were taken into account: the method of determining the exhaust dilution in a diluting tunnel, the ratio of exhaust gases dilution, conditioning of the filters used in particle emission measurements and isokinetics of sampling a diluting tunnel.The results presented in this paper concern four chosen parameters characterizing conditions of the measurement of particle emissions. Obviously, this data does not close the question of influence on other parameters on their result measurements. They show, however, the necessity of more detailed specification...
The Importance and Essential Function of the Level of Information about Reliability of Means of Transport
Stefan Liscak
Communications - Scientific Letters of the University of Zilina 2001, 3(1):53-62 | DOI: 10.26552/com.C.2001.1.53-62
Increasing requirements on the operation reliability of means of transport require interdisciplinary approach.Theoretical estimations of reliability depend on the quality of information, mostly on the law of damage cumulation in the case of complicated operation strain. On the basis of the quality of the entry information about the operation reliability of means of transport, it is possible to use the theoretical considerations about reliability in the optimisation of the technological process of transportation.
Course of Kinematic Parameters during the Course of Braking and Action of Dynamic Effects
Pavol Hudec, Eduard Rojko
Communications - Scientific Letters of the University of Zilina 2001, 3(1):63-68 | DOI: 10.26552/com.C.2001.1.63-68
The article deals with a course of kinematic values at rolling of car wheels during the course of braking focusing on experimental measurement of their time-base relations and effect of a braking slip of front wheels on a course of braking along with an effect of a gradient of braking deceleration build-up on a moment of wheel blocking from a view of safe car handling in direction.
Hull Structural Scantlings of the Golden Series Otoryacht
Peter Patek
Communications - Scientific Letters of the University of Zilina 2001, 3(1):69-76 | DOI: 10.26552/com.C.2001.1.69-76
The paper describes the procedures for scantlings of some hull structural elements from FRP materials. The solution and software are based on the rules of classification societies GL-BV-RINA. It allows to estimate the optimal skin-plating thickness and other dimensions of the stiffeners. These procedures are applied for design of the large high-speed craft Golden Series designed for the open-sea class. The luxurious yachts built in Bratislava shipyard for foreign customer.
Thermal Loading of the Railway Wheel during Downhill Breaking
Juraj Gerlici, Peter Vesely, Tomas Lack
Communications - Scientific Letters of the University of Zilina 2001, 3(1):77-87 | DOI: 10.26552/com.C.2001.1.77-87
The paper deals with the particular factors of railway wheels heat loading while braking with a brake block and consequences of that stressing. There are discussed some phenomena of thermic interaction between the bracked wheel and the brake block. The attention is aimed to the rising and spreading of thermic fields into a wheel and brake block too. Next, there are pointed out the manner and possibilities of solution of nonstationary thermal field course. Considering the difficulty of an analytical solution the emphasis is given to the results of the experimental works on the brake bench. A compendium of the particular design variants of the monoblock...
Potential Reduction of Travel Times and Energy Consumption of Tilting Body Vehicles on ZSR
Juraj Grencik, Miloslav Klinko
Communications - Scientific Letters of the University of Zilina 2001, 3(1):88-97 | DOI: 10.26552/com.C.2001.1.88-97
Increasing the speed of passenger transport becomes an important task facing present-day railways. This task has risen both from the international agreements and from the necessity to keep competitiveness of the railway on the transport market. The paper presents a possibility to increase travel speed of passenger transport on ®SR (Slovak Railways) by use of tilting body vehicles. For the selected ®SR track sections accessible travel times were calculated for conventionaldesign vehicles and for tilting body vehicles. From comparison of the results a remarkable reduction of accessible travel times can be found. Further, the energy-consumption demands...
Scientific-Research Activity of the Department of Transport Machines, Faculty of Mechanical Engineering -Technical University of Liberec at The Field of the Vehicles Engines
Stanislav Beroun, Ladislav Bartonicek, Josef Laurin, Lubomir Moc, Celestyn Scholz
Communications - Scientific Letters of the University of Zilina 2001, 3(1):98-102 | DOI: 10.26552/com.C.2001.1.98-102
The paper shows the technical solutions and the results of the research works, connected with the conversion of Diesel engines to spark ignition (SI) gas fuelled engines for the vehicles. The attention is paid to the comparision of the exhaust pollutions from the gas fuelled engines and from original diesel engines.
Vessels for "River-Sea" Shipping Technologies
Jaromir Klepoch, Pavel Zarnay
Communications - Scientific Letters of the University of Zilina 2001, 3(1):103-112 | DOI: 10.26552/com.C.2001.1.103-112
Inland and marine water transport intersect each other in seaside areas of continents as well as in off-shore parts of world seas and oceans. That leads to their natural technological and technical integration. In the largest possible extent is this shown on the water transport means, which is a ship or eventually also a formation of vessels in various technological configuration. In that way, transport systems which are a part of combined systems of water transport named as"river-sea", are created. In these systems, apart from dimensionally smaller marine ships, which are able to navigate also into river-sea ports situated deeply in big rivers mouths,...
The Influence of Negative Temperature son the Heat Conductivity Factor of Road-Building Materials
Jan Celko, Jarmila Cardosova
Communications - Scientific Letters of the University of Zilina 2001, 3(1):113-119 | DOI: 10.26552/com.C.2001.1.113-119
Appraisal of pavement from preservation against frost influence point of view is important point of its structure evaluation. The Slovak climatic conditions originate the same cycles of pavement and subgrade freezing during a winter period. This effect is dangerous from surface deformation and loss of serviceability point of view. Therefore is necessary to know the thermo-technical properties of layers' materials for structure design. The values in nature state are measuredand evaluated only, although during freezing process the characteristics in frozen state are active. Therefore an article deals with measuring of a heat conductivity factor of building...
Diagnostics of the Deformation Properties of Grained Materials
Libor Izvolt, Milan Milan Miksik
Communications - Scientific Letters of the University of Zilina 2001, 3(1):120-126 | DOI: 10.26552/com.C.2001.1.120-126
In the field of substructure of line and ground building works, natural grained materials have considerable representation in the material basis. During the exclusive offer of these materials suppliers, it is necessary to determine the possibilities of material use into traffic-way structure. The suitability of using natural-grained materials can be judged in laboratory conditions. In the paper a method is characterised to be applicable for the complex judgement of variousmaterial use in construction layers of the traffic way or for diagnostics of the building works before their opening. Material suppliers can document the quality of the supplied material...