Models that can predict the correct logistics actions that need to be taken to ensure the availability of spare parts during maintenance of railway vehicles are of considerable interest. Since the occurrence of defects is a random phenomenon it is not possible to know in advance what spare parts will be required at any point in time. This situation requires the creation of a stochastic model that can incorporate uncertainty. Deterministic and stochastic models of maintenance logistics are based on the assumption of a non-zero stock level of spare parts. Carrying an extensive inventory of parts requires a large financial outlay and it is still often the case that a required spare part is not immediately available and has to be obtained. This paper shows, provided certain conditions are met, that it is possible to create cost-effective maintenance procedures even if the required spare part is not immediately available. Thus, the amount of money locked up in stock can be effectively regulated, thus reducing operating costs.

The preparation of the fuel mixture of a conventional internal combustion engine is currently controlled exclusively electronically. In order for the electrical management of an internal combustion engine to function properly, it is necessary that all its electronic components work flawlessly and fulfill their role. Failure of these electronic components can cause incorrect fuel mixture preparation and also affect driving safety. Due to the effect of individual failures, it has a negative impact on road safety and also negatively affects other participants. The task of the research is to investigate the effect of the failure of electronic engine components on the selected operating characteristics of a vehicle. The purpose of this article is to specify the extent to which a failure of an electronic engine component may affect the operation of a road vehicle. Eight failures of electronic systems (sensors and actuators) were simulated on a specific vehicle, with a petrol internal combustion engine. Measurements were performed in laboratory conditions, the purpose of which was to quantify the change in the operating characteristics of the vehicle between the faulty and fault-free state. The vehicle performance parameters and the production of selected exhaust emission components were determined for selected vehicle operating characteristics. The results show that in the normal operation of vehicles, there are situations where a failure in the electronic system of the engine has a significant impact on its operating characteristics and, at the same time, some of these failures are not identifiable by the vehicle operator. The findings of the publication can be used in the drafting of legislation, in the field of production and operation of road vehicles, and also in the mathematical modeling of the production of gaseous emissions by road transport.

Detail záznamu - Complex view to racing car upright design and manufacturing - Detail záznamu - Vědecká knihovna UJEP

The aim of the article is to present the concept of an indirect diagnostic method using the assessment of the variability of the amount of released heat (mass fraction burn) and the heat release rate. The Wiebe function for the assessment of variability has been used. The Wiebe function parameters from the course of the high-pressure indication in the cylinder of internal combustion engine using linear regression have been calculated. From a sufficiently large number of measured samples, the upper and lower limits of the Wiebe function parameters have been statistically determined. Lower and upper limits characterize variability of the heat release process not only in terms of quantity but also in terms of heat release rate. The assessment of variability is thus more complicated than using one integral indicator, typically the mean value of amount of the released heat. The procedure enabling a more accurate estimation of heat generation beginning has been shown. For the combustion process variability assessment of the engine, statistical test of relative frequencies has been used.

In a conventional internal combustion engine, only electrical controls are used to prepare the fuel mixture. All parts must operate flawlessly in order for the vehicle and its components to operate correctly. Road safety may be negatively impacted by the failure of specific components. The purpose of the study was to ascertain how much the malfunction of particular electrical components affects how the vehicle operates. The vehicle's individual electronic parts were removed, and the engine power was then assessed. The primary determinant of a vehicle's technical condition is thought to be its engine power. The preparation of the combustion mixture was affected by the individual component disconnections, which reduced the vehicle's performance. A vehicle with an in-line four-cylinder engine was used for the experiment, which was conducted in a lab setting. This vehicle's eight components were gradually disengaged. The change in engine power was observed while they were disconnected. The measured values were always evaluated in terms of an automobile that had no defects and was in excellent condition. The study's findings demonstrate that there are circumstances in which a vehicle's usual operation is adversely affected when one or more of its electrical components malfunctions.