Science and Transport Progress

7-18

Authors: L. F. Dolina, P. B. Mashykhina, A. A. Karpo, A. A. Mishchenko

Purpose. The paper analyzes the state of water management in Ukraine and worldwide, as well as the best practices in this area. Methodology. The study was carried out based on the analysis of literature sources and reporting data on the state of water management in Ukraine, European countries, the USA (2010-2016). Findings. The water state analysis in the regions of Ukraine showed that the quality in most cases is close to or meets the requirements for drinking water. Drinking tap water requires post-treatment in all regions of the country. The main issue for today is the production of the necessary equipment for treatment plants. Unfortunately, not all equipment is produced in Ukraine. The condition of rural water pipelines is of particular concern. Among the tested pipelines 7.3% do not comply with the rules and regulations. At the same time, only 25% of villages in Ukraine are provided with centralized water supply. Originality. The authors presented the results of a comprehensive review of the world's issues on disinfection of drinking and waste water, where various methods are used, partly in combination with each other in Ukraine and the worldwide. The main unresolved issue today is the issue of the residual quantity of drugs in the drinking water. The main environmental threat of the world scale is the presence of medicines in drinking water. The treatment facilities are not suitable for the decomposition or trapping of medicinal products. Nowhere in the world there is protection from these substances. One of the key issues in the solution of drinking water production is seawater desalination. To reduce the cost of desalination of sea water the SWRO-membrane technology is used. Practical value. Water problems are number one problems all over the world and in Ukraine as well. It is necessary to provide for additional financing to solve problems in the preparation and purification of waters, not with whatever funds remain, taking into account the fact that water is the basis of life on earth as a whole, the health and life of the nation depends on the quality of the water supply source.

28-47

Authors: A. O. Sulym, S. O. Muzhychuk, P. O. Khozya, O. O. Melnyk, V. V. Fedorov

Purpose. The analysis of the existing studies showed that the increasing of energy efficiency of metro rolling stock becomes especially important and requires timely solutions. It is known that the implementation of regenerative braking systems on rolling stock will allow significantly solving this problem. It was proved that one of the key issues regarding the introduction of the above-mentioned systems is research on efficient use of electric energy of regenerative braking. The purpose of the work is to evaluate the amount of excessive electric power of regenerative braking under normal operation conditions of the rolling stock with regenerative braking systems for the analysis of the energy saving reserves. Methodology. Quantifiable values of electrical energy consumed for traction, returned to the contact line and dissipated in braking resistors (excessive energy) are determined using results of experimental studies of energy exchange processes under normal operating conditions of metro rolling stock with regenerative systems. Statistical methods of data processing were applied as well. Findings. Results of the studies analysis of metro rolling stock operation under specified conditions in Sviatoshinsko-Brovarskaia line of KP «Kyiv Metro system» stipulate the following: 1) introduction of regenerative braking systems into the rolling stock allows to return about 17.9-23.2% of electrical energy consumed for traction to the contact line; 2) there are reserves for improving of energy efficiency of rolling stock with regenerative systems at the level of 20.2–29.9 % of electrical energy consumed for traction. Originality. For the first time, it is proved that the most significant factor that influences the quantifiable values of the electrical energy regeneration is a track profile. It is suggested to use coefficients which indicate the amount and reserves of unused (excessive) electrical energy for quantitative evaluation. Studies on determination of the quantifiable values of electricity recovery for analysis of energy saving reserve showed prospects for further development. Practical value. The obtained qualified values of excessive electric energy of regenerative braking can be applicable to construction of new or upgrading of the existing metro rolling stock provided that energy efficient technical solution for the utilization, preservation and storage of such electrical energy is developed.

61-70

Authors: S. T. Djabbarov

Purpose. Studies of the effect of aerodynamic pressure on the maximum permissible speeds of a high-speed train on the existing railway infrastructure. Methodology. The study of the magnitude and direction of the aerodynamic pressure, its effect on the maximum speeds of a high-speed train was carried out on a train model composed of axisymmetric bodies with conical forms of head and tail parts. Findings. Determined the values of the aerodynamic pressure at different distances from the train are, when the high-speed train moves at a speed of 200 km/h or more. The maximum speeds of a high-speed train are determined taking into account the state of the infrastructure of the existing railway, ensuring the safe operation of a high-speed railway. Originality. Theoretical studies of aerodynamic pressure from secondary air currents formed during the movement of high-speed trains are performed on a model of a train composed of identical axisymmetric bodies with conical forms of head and tail moving in a compressible medium. The results of the research allow the regularity of the change in aerodynamic pressure during the movement of a high-speed train. Practical value. The obtained results allow to establish: 1) the maximum permissible speeds of a high-speed train taking into account the technical condition of permanent devices and structures of the existing railway infrastructure; 2) technical parameters of individual objects and structural elements of the infrastructure of high-speed iron subjected to the effect of aerodynamic pressure for a given maximum speed of high-speed trains.

79-90

Authors: А. O. Redko, I. O. Redko

Purpose. This paper highlights experimental research of heat exchange in coarse particles to ensure the performance of ecological characteristics of Heat supply system. Methodology. The test stand has been developed to solve the defined task. It helps to do the research at the temperature of fluidizing bed and pulsating fluidizing bed at the range 800–1000°С. The temperature of the fluidized bed was provided by burning natural gas and wood waste. Sand and chamotte with a particle size of 1.0 to 5.0 mm were used as the layer material. The heat-transfer coefficient from the layer to the surface, immersed in the layer, and the density of the heat flux were measured by a calorimetric method under steady-state conditions. Smooth tubes and transversely finned with different height and rib spacing were investigated. Experiments in a high-temperature pulsating fluidized bed were carried out with pulsating combustion of natural gas in a layer or in a sublattice chamber into which natural gas and air were separately supplied. The frequency of combustion pulsations was provided by the automation system. The flash frequency was regulated in the range from 0.14 to 5 Hz. Findings. It is presented the results of physical modeling to find out the heat-transfer coefficients of smooth and finned tubes in fluidizing bed of coarse particles in the process of wood waste and gaseous fuel combusting. It is proved that the coefficient of heat transfer increases with increasing temperature by 2–2,5 times in the bed which contains particles diameter of 2.5–5 mm is 300–350Vt/(m2 К) that is much higher than for layer furnaces. The results of the experiments are presented in the form of a generalized relationship that takes into account the diameter of the particles and the value of the finning coefficient. Heat transfer of finned tubes is 15–20% less then smooth tubes but the density of heat flow referred to the area of a finned tube is 0,12–0,20 МVt/m2 that is higher than for smooth ones. At pulsating fuel supply with frequency 1-2 Hz the heat-transfer coefficient gets higher from 10–15% till 25–30%. At a ripple frequency of 2 to 5 Hz, the heat-transfer coefficient varies from 510 to 570W/(m2K). With a further increase in the pulsation frequency, the heat-transfer coefficient decreases and amounts to 515–520 W/(m2K). A significant effect of the ripple pulsation from 0.8 to 0.3 is shown: the heat-transfer coefficient is increased by 30–35%. However, an unstable combustion regime of the gas-air mixture and the ejection of material particles from the layer are observed. The results of the experiments are presented in the form of a generalized relationship. Originality. The authors have presented the obtained experimental data about heat-transfer coefficients of finned tubes in fluidizing bed and pulsing fluidizing bed of coarse particles at the temperature of layer 800–1100оС. Practical value. The results obtained at the research help to develop furnace devices with low-temperature fluidizing bed in the process of immersion in a layer of finned tubes layers. The research data is presented in criterial view which is convenient for practical using.

99-106

Authors: O. H. Reidemeister, V. O. Kalashnyk, O. A. Shykunov

Purpose. The scientific work is intended to develop a methodology for describing the structure of the railway vehicles (they are considered as a system of rigid bodies connected by rigid, elastic and dissipative elements), which would allow us to obtain the equations of motion in an easily algorithmized way. Methodology. When constructing the model, authors tend to ensure that its structure reflects the structure of the mechanical system, that is, parts of the model must correspond to parts of the car. In this case, the model takes the form of a hierarchically organized graph whose vertices correspond to the bodies, attachment points of the connecting elements and to the connecting elements themselves, and the edges describe the sets of processes that are related to the incident vertexes. As a rule, these are movements and forces: for the edge between the body and the attachment point they are generalized movements of the body and the general forces acting on it; for the edge between the attachment point and the connecting element - the movements of the point and the forces arising in the element. To each vertex there corresponds a group of equations describing the motion of the system. The nature of the equations depends on the type of the vertex. For the body it is the equations of body motion; for the point - the expressions for the point displacements through generalized displacements of the body and generalized forces acting on the body, through the forces arising in the connecting element; for the connecting element - the expression for the forces arising in it through the deformation of the element. The graph can be regarded as oriented. The direction of the edge is chosen in such a way that for each vertex the values on the right-hand side of the vertex-associated equation would correspond to the incoming edge, and in the left-hand side - to the outgoing edge. Findings. A technique for constructing a dynamic model of oscillations of railway vehicles as a system of rigid bodies is developed on the basis of their description using hierarchically organized graphs. The technique was tested to construct a model of spatial oscillations of a 4-axle freight car with an axial load of 25 tons in Simulink package. Originality. For the first time, a technique has been developed for describing the structure of a railway vehicle using a hierarchical graph, which makes it possible to obtain equations of motion in an easily algorithmized manner. Practical value. The proposed methodological approach will allow, after creating a library of bodies and connecting elements, to significantly reduce the time spent on modeling the oscillations of different vehicles.

115-123

Authors: D. Y. Ihnatenko, V. D. Petrenko, O. L. Tiutkіn

Purpose. Analysis and comparison of the landslide slope finite element model calculation results of the appliance of soil-cement piles, depending on the variation of the retaining structure rigidity, makes it possible to evaluate the effectiveness of their application and the cooperative work of piles with the displacement body. It also makes it possible to make a conclusion about the advantages of using this anti-landslide protection method of the slope. Methodology. Analysis of geomorphological data obtained from the results of laboratory studies of soils on the slope section is considered. Creation of a three-dimensional finite-element slope model according to the constructed sections and depths of the soil layers. Calculation of the nonlinear problem of finite element modeling of the slope with applying of soil-cement piles of various rigidity. Findings. The obtained results of calculating the finite element model of the landslide slope, and the analysis of the stress-strain state of the construction with soil-cement piles has been carried out. Originality. Despite the widespread of using soil-cement piles as enclosing structures for the construction of foundation pits and reinforcement of foundations of emergency structures, special attention should be paid to the study of the expediency of using soil-cement retaining pile structures on landslide areas. Practical value. It is known that soil-cement retaining piles are expediently in use as a protective element, which interacts quite well with the ground environment due to its structure of the initial material. Using of modern computer programs of finite element modeling makes it possible to calculate the efficiency of the use of soil-cement piles and to determine the parameters of the necessary retaining structure according to the given geological structure of the slope, and also, depending on its shape and the physical characteristics of the soils, to compare the performance of different protective landslide structures types.

131-140

Authors: V. O. Samosvat, Zhang Rongling, O. O. Hololobova, S. Y. Buriak

Purpose. Investigation and analysis of the hanger arrangement and the structural stability of a Network arch bridge – a tied-arch bridge with inclined hangers that cross each other at least twice. It is also necessary to make a comparative analysis with other types of hanger arrangements. Methodology. The authors in their research investigated a large number of parameters to determine their influence in the force distribution in the arch. Eventually they determined optimal values for all parameters. These optimal values allowed developing a design guide that leads to optimal arch design. When solving this problem, the authors used three-dimensional finite element models and the objective was to determine the most suitable solution for a road bridge, with a span of 100 meters, consisting of two inclined steel arches, located on a road with two traffic lanes, subjected to medium traffic. The virtual prototype of the model is performed by finite element simulator Midas Civil. Findings. In this study, for the bridge deck, a concrete tie appears to be the best solution considering the structural behavior of network arches, but economic advantages caused by easier erection may lead to steel or a composite bridge deck as better alternatives. Design requirements and local conditions of each particular bridge project will decide the most economic deck design.Originality. To ensure passenger comfort and the stability and continuity of the track, deformations of bridges are constricted. A network arch is a stiff structure with small deflections and therefore suitable to comply with such demands even for high speed railway traffic.
A network arch bridge with a concrete tie usually saves more than half the steel required for tied arches with vertical hangers and concrete ties. Practical value. Following the study design advice given in this article leads to savings of about 60 % of structural steel compared with conventional tied arch bridges with vertical hangers.

149-157

Authors: M. A. Storozhuk, T. M. Pavlenko, A. R. Abbasova

Purpose. The scientific work is dedicated to development of scientific-technical bases of production and application of concrete on the basis of ashes of thermal power plants (TPP). Methodology. The properties of TPP ash, as well as the peculiarities of its behavior in a concrete mix as a fine aggregate, have been studied. It is shown that the hydrolysis and hydration of cement occur in the active environment of ash, which has a huge specific surface area. This significantly affects the course of these processes and the quality of the concrete produced. A new technology of application of ash of TPP for preparation of concrete mixes is offered. Vibrated and vibrovacuumized concretes of optimum composition from slag and ash, as well as from granite crushed stone and ash, are tested. The chara-cteristics of ordinary concrete (from granite crushed stone and quartz sand) are given to compare. Findings. The results of the tests showed the possibility of obtaining concretes of class C20/25…C25/30 on the basis of slag and ash of TPP at a limited consumption of cement. It is shown that the concrete with traditional aggregates has a lower strength than the concrete, which has ash as fine aggregate. This research results contribute to the increased use of ash in construction that solves the problem of aggregates as well as thermal power plants waste recycling. Originality. New method and technology of application of TPP ashes in concrete are developed. Ash concrete mix has rational flowability, which produces the greatest strength of ash vacuum concrete. This strength is twice or more as large as the strength of vibrated ash concrete mix with flowability S1. Practical value. The physico-chemical properties of TPP ash as aggregate for concrete are presented. Significant difference of ash from ordinary aggregates is shown. Chemical activity of the ash is justified. The special conditions of cement hardening in the case of using ash as aggregate for concrete are presented. The advantages of ash over traditional aggregate are shown. The research results contribute to the mass application of TPP ash in construction and obtaining the products from the proposed concrete of low cost with high physical-mechanical properties. Ash as an aggregate has a particularly high efficiency in vibrovacuumized concrete.