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Content available Mathematical modeling of the aeroion mode in a car
EN
In this study, a mathematical method is proposed for calculating the concentration field of air ions of different polarities and dust levels in the passenger compartment, taking into account the geometry of the passenger compartment and seats, shelves, and other internal elements of the passenger compartment. The method also takes into account changes in the rate of the air flow ventilation, the location and number of ionizers, and sources of positive ions and dust, taking into account their different intensities and locations. On the basis of a numerical model for this method, software has been developed that allows users to carry out computational experiments without requiring much time for calculation. Based on the results, the optimal location of the ionizer in the passenger compartment of the car was determined to ensure comfortable conditions for the stay of passengers, which favorably affects their health. It has been found that the presence of two ionizers is optimal for creating comfort in the car with an ionization intensity of Qn= 0.47 ×1010 ions/s located at the top of the car. If there is one ionizer located on the dashboard or at the top of the car with a higher ionization rate than ions/s, it is not possible to simultaneously provide optimal ionization parameters for passengers in the front and rear seats of the car.
EN
This article stresses the need to develop multimodal passenger transport. Particular attention is paid to the construction of HUBs based on railway stations. HUB is the transport interchange node, passenger complex, which redistributes passenger flows between transport modes and directions. They allow to optimize transportation processes, as well as to create an infrastructure for convenient and fast passenger transfer between different transport modes. The preconditions for creating organizational conditions to ensure the sustainable development of the passenger railway transport sector are outlined. In the near future, combined passenger transport with the participation of several modes of transport will attract tourists from around the world. The authors’ concept of the term “passenger comfort zone” is proposed, which takes into account all the needs of modern tourists. The mechanism of multimodal transportations of passengers by railway transport in interaction with other participants of the servicing process is presented. A model of institutional support for the development of multimodal passenger railway transport is proposed to create conditions for integrated transport services for passengers by the passenger railway transport complex. The expediency of forming a system of railway passenger HUBs in Ukraine is vital to attracting investments to improve transport and tourism infrastructure, as well as to roll stock and a range of services for the benefit of all stakeholders in the transport sector (e.g., the state, investors, and passengers).
EN
In this study, a numerical model is proposed for calculating pollution zones near the road, taking into account the geometry of the automobile transport meteorological conditions, the location of the barriers and their height, and the chemical transformation of nitrogen oxides in the atmospheric air. The numerical solution is based on the integration of the mass transfer equations using the finite-difference method. To determine the components of the air flow velocity vector, a two-dimensional model of the potential flow is used, where the Laplace equation for the velocity potential is the modeling equation. Based on this numerical model, a software package has been developed that allows computational experiments and does not require large expenditures of computer time. Based on the results obtained, an assessment was made of the effectiveness of the use of barriers to reduce the level of air pollution near highways. It has been established that the use of barriers of different heights reduces the level of pollution behind the road by approximately 20-50%.
EN
In this study, the methodological foundations of the technology for the local reduction of chemical pollution from vehicles were improved through the use of twolevel suction units and guide plates of various lengths installed on the nozzles of the suction devices. A program has been developed for the numerical calculation of the carbon monoxide concentration field for evaluating the efficiency of using two-level exhaust systems with different lengths of guide plates on the gas flow selection pipes. The solution of the equations of hydrodynamics and mass transfer is carried out on the basis of finite-difference methods. A number of physical and computational experiments have been carried out; it has been established that the concentration of carbon monoxide in the zone of two-level suctions location decreases by 46-68%.
EN
The main objective of the simulation is to study the effect caused by the parameters of the longitudinal profile on the maxima of longitudinal forces in freight trains of increased length during adjustment braking and running-out. To decrease the number of numerical experiments, some empirical formulae for estimating the maximum longitudinal forces during the motion of freight trains along the track with various configurations of its longitudinal profile's gradient changes have been obtained for the first time. Comparison of those forces with the permitted values, from the point of view of the railway stock strength and eventual vehicle derailment, has been performed. As a result of numerical integration of the system of non-linear differential equations of train motion for the considered driving modes, the values of the greatest longitudinal shock and quasi-static forces, as well as the dependence of the latter on the train length, initial braking velocity, on the algebraic difference of gradients and the length of the horizontal area that separates two gradients with opposite signs are estimated. The proposed mathematical model and methodology can be applied during standardization of the longitudinal profile's parameters from the point of view of the freight traffic safety for the trains of various length.
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