Conference Technology Transfer: fundamental and innovative technical solutions
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PECULIARITIES OF MATHEMATICAL MODELING OF THE FLOW WHEN SELECTING THE GENERAL SIZES OF A BRIDGE CROSSING WITH GROUP HOLES
Get PDFThe problems of mathematical modeling of hydrodynamics of open flows are analyzed in the article when general sizes of bridge crossings with group holes are assigned. Most of the existing methods for calculating branched flows are based on the use of one-dimensional models, it does not allow to describe sufficiently the hydrodynamic processes occurring in zones with separated flows. Therefore, in the calculation of bridge crossings with group holes, two-dimensional models that take into account the features of the morphology of natural watercourses, the uneven distribution of the average velocities along the vertical, the phenomenon of flow separation, as well as the change in rate along the flow due to the separation of the flow is suggested. The existing experimental and theoretical studies are analyzed, the flow structure and the physical model of the flow branching process in the zone of influence of bridge crossings with group holes are considered. Based on the fundamental equations of flow transfer, a mathematical two-dimensional model of the flow of open flows is presented, which takes into account the influence of secondary currents. To substantiate the zone of influence of bridge crossings with group holes, an equation for vorticity is proposed that reflects the distribution of vortex structures. For the closure of the equations of motion and continuity, algebraic relations for the Reynolds stresses in conjunction with the two-parameter k-ε model for depth-averaged values are used, which is modified to take into account the effect of the curvature of the flow. The method of numerical realization of the proposed mathematical model is based on the predictor-corrector method using the McCormack scheme, modified by splitting the model equations with respect to spatial coordinates and time. The method of successive upper relaxation based on the Gauss-Seidel iterative method is used to realize the algebraic relations of turbulent stress transfer. The conclusion is made about the expediency of practical application of this mode
ANALYSIS OF WAYS TO INTENSIFY FLOCCULATION OF FINELY DISPERSED SLIME
Get PDFThe object of research is the process of the slime cleaning of the coal preparation plant from suspended solids by flocculation. The process of flocculation is multifactorial and depends on the concentration of the solid phase in the slime, the dispersed composition, the salinity, the pH of the medium, the concentration and degree of dilution of the flocculant and many other factors that have not been adequately studied in the current literature. Based on previous studies, it was suggested that the flocculant was introduced into the slime in two portions in an amount of 40 % and 60 % of the total flow. The aim of research is an experimental check of the influence of methods of dispersing and introducing the first portion of the flocculant onto the efficiency of sedimentation of the slime on the real slime. For this, in the diluted slime with water in a ratio of 1:1, the first portion of the flocculant is introduced in two ways: after diluting the slime with water and into the water before mixing it with the slime. It is established that the preliminary dispersion of the flocculant in a large volume of water leads to a significant increase (above 80-85 %) in the sedimentation rate of the formed floccules, as well as their strength to mechanical actio
MONITORING OF WASTEWATER PURIFICATION PROCESS
Get PDFThere were conducted the researches to identify new correlation between traditional controlling process indicators of cleaning stock water from phosphates and concentration of phosphates in purified water that can be used for the development of new techniques.
Analytical laboratory data of the current purification station were carried out with the use of the Pearson correlation coefficient to detect a connection between concentration of phosphates in the purified water and four kinds of hydrobiological data using Microsoft Excel a computer program with functions Corel batch analysis.
The most informative for monitoring of purification from the phosphates is the indicator of the number of types of hydrobionts. Change of concentration of phosphates goes in antiphase to the amount of types of hydrobionts. Therefore, for the convenience of the users there was completed the visualization of the existing trend using the introduced by the authors index-modified number of hydrobionts.
There was presented an algorithm monitoring the process of sewage purification from phosphates, which requires the creation of a database and preliminary plotting of dependence of phosphates Sf concentration on the number of hydrobionts NG. The further displaying of laboratory data indicator NG on the schedule allows to predict the expected concentration of phosphates Sf in purified sewage and in case of poor forecast to carry out operational actions. The survey is based on the basis of a new methodology, which was transferred for the introduction to "Chernihivodokanal" (Chernihiv, Ukraine
RELIEF AND SOIL COVER OF THE NORTHERN BLACK SEA REGION: ECOLOGICAL AND GEOMORPHOLOGICAL ASPECT
Get PDFThe possibilities of mutual dependence of the areas of genetic types and varieties of the soil cover of the intensively developed region of the Northern Black Sea Coast with taxonomy of geomorphologic zoning, with morphogenetic categories of the relief of the earth's surface, with separate topographical and genetically homogeneous surfaces, with simple and complex surfaces of different morphology, exposition, morphometric parameters (vertical and horizontal dismemberment, steepness of the slopes) are considered and analyzed.
The relevance of this approach is important and timely, given the presence of a number of problems in the Ukrainian economy. The study is carried out both in the territory of the regions a whole and in key areas, which in general represent the most revealing features of orographic, geomorphologic and paleogeographic character, distribution and quality of soil cover.
Thanks to the analysis of the theoretical and methodological representations, an algorithm for the ecological and geomorphological analysis of the formation is used and degradation of the soil cover in the central part of the Northern Black Sea Coast is developed, based on the provisions of the philosophical vision of scientific knowledge.
This report presents a step-by-step consideration, based on the example of the investigated territory, the diverse cartographic information chosen and analyzed in the context of the message topic, in conjunction with the properties of the soil cover of the regio
PERSPECTIVES OF THE USE OF MODERN BUILDING MATERIALS IN ROAD CONSTRUCTION
Get PDFThe authors analyzed the foreign experience of using keyed joints in reinforced concrete span structures of bridges. Fiber concrete with polypropylene fibers was chosen as the investigated material. Such fibers are chemically neutral, water-resistant, have a high resistance to dynamic loads, reduce the risk of formation and development of cracking, increase abrasion what is important in the manufacture of road construction. Optimization of concrete composition with polypropylene fibers for concreting joints by physical and mechanical parameters was carried out. Parameters of optimization were compressive strength, tensile strength at bending, axial tensile strength, prism strength and abrasion. The authors performed a series of tests to study the behavior of fiber concrete in keyed joints. The analysis of obtained results out depending on the nature of failure, the value of the ultimate load and fiber concrete deformations were carried out.
The influence on the joints strength of the cross-section reinforcement percentage and the nature of placement of the reinforcing rods was considered.
It was established if to place a cross-reinforcement in two levels it increases the strength of joints in comparison with a single level with the same percentage of reinforcement. It was noted that the fracture of all samples occurred from the sear key. Cracking of fiber concrete experimental samples occurred at later stages of loading compared with samples of ordinary concrete, and the fracture was not brittle, without tearing off parts of concrete. Increase in strength is due to the chaotic placement of polypropylene fibers in concrete, and therefore, to remove fibers from concrete, it is necessary to spend more energy, which ultimately leads to an increase in strength of joint.
Experimental data suggest possibility and feasibility of polypropylene fibers in concrete joints in precast concrete structures of bridge
INVESTIGATION OF SYNTHESIS OF MODERN TECHNOLOGIES AND ECOLOGY. ECONOMIC ECOLOGY
Get PDFThe article deals with the problems of ensuring environmental safety and environmental protection, economic prerequisites for irrational nature management. The economic development of terrestrial civilization is associated with the accelerating growth of consumption of natural resources of the planet, as a result of which depletion of stocks of non-renewable types of natural raw materials and deterioration of the state of the environment as a result of intensive nature management and its environmental impact. To mechanize work in huge quantities, energy resources are consumed, natural landscapes change, artificial landscapes arise due to waste storage, hydrogeological regimes of rivers, lakes and territories change, climate changes and the reverse effect of the forces of nature. Development is accompanied by the involvement of natural resources in operation in ever increasing volumes and scales. The necessity of rethinking the technogenic and ionosphere civilization concepts of human development from the point of view of ecological safety is considered. The effectiveness of the approach to the management of ecological and economic systems is that there will be stabilization and improvement of the ecological status, preservation of unique natural objects, environmental safety of the population, sanitation of environmentally harmful and hazardous industries will be ensured. The transition to low-waste and non-waste technologies will become more rea
EXPERIMENTAL INVESTIGATION OF HEAT TRANSFER IN INTERFIN CHANNELS OF PUNCHED SPIRAL TUBE FINNING
Get PDFTo reduce the metal consumption of boilers of steam-turbine power units and waste-heat boilers of gas-steam turbine units, the spiral-tape finning of low-temperature convection heating surfaces is applied. However, the heat transfer in the bundles of such tubes has not been studied sufficiently, the influence of the geometric dimensions of the cut portion of the fins has not been experimentally investigated. In most heat exchange calculation methods, based on the generalization of the results of experimental studies, this influence is also not taken into account. It is proposed to take into account the influence of the finning geometry on heat transfer by introducing correction coefficients in the generalizing equations, determined from the results of a numerical research.
To evaluate the validity of the introduction of the results of numerical research into generalizing equations, an experimental investigation of heat exchange in the interfin channels of the punched spiral finning of the tubes is carried out. A research method is developed based on the results of measurements of the surface temperatures of the fins and air in different zones of the interfin channel along its height, as well as the air temperature in front of the bundle and the air flow through the bundle. The study is carried out by placing the calorimeter tubes in the transverse rows of the chess and corridor bundles of tubes at different Reynolds numbers.
The results of the investigation of one of the bundle. The calorimeter is installed in the fifth row of a six-row tube bundle with fin interval of Sf = 6 mm and tube steps in the bundle S1 = 85 mm, Ś2 = 85 mm.
At the Reynolds number, Red = 10042: the heat flux in the interfin channels Q = 711.0 W, the same according to electrical measurements - 731.0 W; discrepancy - 2.73 %; the heat transfer coefficient in the blade zone is αifcb = 162.0 W/m2°C; discrepancy – 2.88 %. The average surface heat transfer coefficient in the interfin channel is ͞ αifc = 132.35 W/m2°C; by numerical calculation - 122.6; discrepancy is 7.31 %. The average surface heat transfer coefficient of a single transverse row of tubes, taking into account the flow of a part of the air through the intertubular channels, is ͞ αc = 83.05 W/m2°C; the discrepancy is 5.12 %.
In the remaining experiments, the difference in the values of the heat transfer coefficients is 3.19 ... 15.7 %. The results of the investigation confirm the validity of the use of the results of numerical investigation in generalizing equations for calculating the heat transfer of bundles of tubes with a spiral finnin
PLASMA TECHNOLOGIES FOR THE PROTECTION OF RADIO ELECTRONIC MEANS FROM EXPOSURE TO HIGH–POWER ELECTROMAGNETIC RADIATIONS WITH ULTRASHORT PULSE DURATION
Get PDFThe urgency of the improvement of methods and means of protection of radio electronic means (REM) due to the development and application of high–power electromagnetic radiation (EMR) generators with ultrashort pulses duration (UPD) is substantiated. It is pointed out that it is possible to solve the problem of REM protection by the complex application of plasma technologies using gaseous and modified solid–state media.
By analyzing the known achievements in the field of developing effective methods and creating protection facilities for REM, a number of unresolved problems in the field of creation of plasma protection technologies have been determined.
The technique of solving the formulated problems is presented and the main relations are obtained to determine the expediency of using the proposed technology in the interests of the REM integrated protection from the powerful EMR UPD.
A relation is made for the breakdown criterion in a gaseous plasma medium that relates the value of the breakdown field to the concentration of charged particles determined by the ionization source. The structure of a solid–state plasma medium is described, which can be used as a protective shield. The order of finding the REM screening coefficient is shown, based on the determination of the distribution function of charged particles for finding the main macroscopic properties of plasma by solving the kinetic equation of the Lenard–Balescu equation. A relation is given for the damping coefficient of an electromagnetic wave in solid–state plasma. Numerical estimates are presented in the form of graphs showing the possibility of using plasma technology to protect the REM from a powerful EMR through possible channels of penetration. The discussion of the obtained results is presented and it is indicated on the possibility and prospects of using the proposed technology for REM protection, especially with limitations on the weight dimensions of protection device
INVESTIGATION OF THE TRAFFIC SAFETY AND PROVISION OF THE PERFORMANCE RELIABILITY OF THE TRANSPORT INFRASTRUCTURE
Get PDFIn the track facilities over the past decade, the polygon for laying reinforced concrete crossties has significantly expanded for many reasons. The main ones are the shortage of wooden crossties, their high cost and low life. Due to frequent crossovers, the service life of wooden crossties in the curved sections of the track R≤350 m is only 7 years. This is 5 times less than the life of reinforced concrete crossties. In the curves R≤350 m under the action of the rolling stock, an intensive accumulation of residual deformations occurs, which causes a violation of the track geometry in the plan. Simultaneously, the stability of the assembled rails and crossties in the transverse plane decreases.
Given the shortcomings of the railway track on wooden crossties, a study is conducted to solve the problems of geometry, and the stability of the track in the transverse horizontal plane. To achieve this, the design of the fastener assembly KПП–5 (SB–3) has been improved, which makes it reliable and adjustable in all respects for 800 1000 million of tons of bruto. In order to ensure the stability of the track, an anchor crosstie structure has been created which can increase the resistance to transverse displacement of the assembled rails and crossties more than 2 times. The developed and justified measures will allow to create a highly efficient construction of a seamless track with reinforced concrete crossties and КПП–5 (SB–3) fastener for curved sections with a radius of 350 ÷ 200 m.
When considering these proposals with the possibility of practical use, it becomes possible to introduce a safe and reliable design of continuous welded rail track with КПП–5 fastener assembly in difficult operating condition
CALCULATION OF SHIP’S ACTIVE BRAKING CHARACTERISTICS
Get PDFThe article considers a new calculation method for determining the ship's maneuvering elements (inertial-braking characteristics) using an alternative approach. Based on the new methodology, the procedure for calculating the inertial-braking parameters of the ship is given. Within the framework of this task, an alternative approach is considered for determining the inertial-braking characteristics of a ship. The article shows that the entire braking process is divided by speed into several elementary sections and it is assumed that in each section the work of the resistance forces and the propeller stop is equal to the work of their average valuesand. And as an alternative method for determining the characteristics of the slowed and accelerated motion of the ship and its characteristics of active braking, theorems on the change in the amount of motion and kinetic energy are used. As a result, expressions of the braking time t and the coasting time S are obtained. Using the obtained expressions, an example of calculating the length and time of the coasting with active braking in the reverse direction from full forward to "full reverse" is give