International scientific journal "Transfer of Innovative Technologies"

Investigation of the relationship between the strength limit and the long time fatigue of steel reinforcements of reinforced concrete structures

2021-10-29T18:20:39+03:00

The results of experimental studies have shown a strong effect of diffusion hydrogen on the static and cyclic parameters of crack resistance of reinforcing steel. It was found that with increasing flooding, especially when the hydrogen content exceeds 5 cm³/100g, both static strength and long-term strength (fatigue) decrease sharply. Moreover, these areas of hydrogen solution in reinforcing steel are characterized by a viscous nature of fracture, while for heavily flooded reinforcement (from 5 to 12 cm³/100g) is characterized by brittle fracture by the mechanism of microcracking in the hardened (martensite or troostite structure). The analysis of the obtained experimental results allowed to determine the optimal hydrogen content in the reinforcing steel (3…5 cm³/100g), the excess of which can cause a decrease in the crack resistance of the reinforcement during long-term operation, especially in corrosive environments.

The mechanism of hydrogen influence on crack resistance of metal at static and alternating loading which consists in diffusion and dislocation movement of hydrogen in structure of a reinforcing core that as a result that causes strong flooding of steel and its embrittlement is offered. It is established that carbon and low-alloy sieves, which are characterized by ferritic-pearlitic and sorbitol structure provide high resistance, especially to long-term fatigue, and the transition to steels with a structure of martensite or tempered (transient structure of bainite) structure of bainite sharply reduces reinforcing steel, which makes it impossible to use in the manufacture of reinforcement involved in reinforced concrete structures designed for long-term operation (more than 50…60 years). Thus, the obtained diagram can be recommended to designers of reinforced concrete structures for hydraulic purposes, as it greatly facilitates the reasonable choice of reinforcement in the development of reinforced concrete structures for responsible and long-term use.

Stabilization of the process of mechanized pulsed-arc welding

2021-10-29T18:38:55+03:00

The main disadvantage of the mechanized arc welding process in shielding gases with short circuits is the spatter during melting of the electrode metal and its transfer to the weld pool, which affects the productivity of the process, reducing it. Its elimination is possible through the implementation of the controlled transfer of molten electrode metal into the weld pool. The implementation of such a transfer and the control of the processes that take place in the arc gap to a large extent determine the conditions for the qualitative formation of the deposited metal, the stability of the process, the magnitude of the loss of electrode metal and the manufacturability of the processes of arc welding in shielding gases. At the present stage of development of welding technologies, controlled transfer of electrode metal is possible due to the pulsed nature of arc burning. In this case, one of the main methods for increasing the efficiency of the process is to limit the maximum value of the short circuit current by increasing the inductive resistance of the welding circuit.

The research aimed to determine the effect of the rate of rising of the welding current during a short circuit on the stability of the welding arc. It was found that an increase in the current growth rate, starting from 1.23 kA/s to 50 kA/ s, leads to a decrease in the average duration of short circuits by at least 10 times. At the same time, the average frequency of short circuits increases by more than 2 times, from 36...38 s^-1 to 80...86 s^-1. The reason for this is the increase in the values of the electrodynamics’ Lorentz force, the action of which leads to the compression of the liquid metal bridge of the drop (pinch effect) due to an increase in the short circuit current. At the same time, there is a violation of the stability of the pulse process, and this is reflected in an increase in the average frequency of arc breaks by more than 30 times from 0.33 s^-1 to 10 s^-1. An increase in the energy parameters of the welding process led to a decrease in the average frequency of short circuits (2...3 times) and their average duration (2 times). The reason for this should be considered a change in the type of transfer of liquid metal – the welding process with short circuits has turned into a mixed process in which, along with short circuits, a droplet transfer of electrode metal is observed.

Improvement of the calculation and experimental method of evaluation of carbonization of reinforced concrete structures of sewerage underground systems

2021-10-29T19:29:13+03:00

Carbonization of concrete leads to a decrease in the alkalinity of concrete, an increase in the number of hydrogen ions in the pores, is one of the main factors that lead to corrosion of reinforcement, the formation of cracks and the subsequent reduction of load-bearing capacity of structures. The study of the depth of carbonization of concrete is to determine the pH of the pore liquid at different depths. There are devices with automatic maintenance of a given concentration of carbon dioxide, to determine the diffusion permeability of concrete to carbon dioxide, based on data on the rate of neutralization (carbonization) of concrete with carbon dioxide. Basically, this method is intended for use in the development of technology and design of concrete composition, providing long-term maintenance of structures in non-aggressive and aggressive gaseous environments, as chips are not prepared immediately before the test and after reaching the design age are placed in the installation with reagents for 7 days. But to determine the carbonization directly on the construction site or object often use the pH method, i.e. the indicator method of pH determination. To assess the concentration of hydrogen ions used acid-base indicators - organic substances – dyes, the color of which depends on the pH from the obtained results the algorithm of definition of depth of carbonization consists in the following actions. The improved formula of definition of depth of carbonization of concrete taking into account degree of aging and corrosion damages for what in the final formula the corresponding coefficients k_st and k_kor are entered: hcarb = {(2D˖C˖τ) / (m_o˖k_st ˖k_kor)} 1/2, where the effective diffusion coefficient of CO₂ in the concrete of the existing reinforced concrete structure, which is determined by the condition D = (m_o˖δ₂) / (2C˖t ). The thickness of the neutralized layer δ is determined experimentally on an existing structure using a physicochemical method (phenolphthalein solution or using depth gauges. .Concentration of CO₂ in air C should be determined by chemical analysis of air samples taken directly from the structure or take ≈ 0.03%. Re. the ability of concrete mo is determined by the formula m_o = 0.4 (C˖p˖f), taking the amount of cement, kg per 1m³, respectively, the strength of concrete. neutralization of concrete is equal to f = 0.5.

Transformation of the Ukrainian cities within post-Chornobyl and Post-totalitarian ‘transitional’ period

2021-10-29T17:26:11+03:00

The study of the transformation of Ukrainian cities in the post-Chornobyl and post-totalitarian transition period highlighted a number of general development trends and regional features of the global urban process. Despite the socio-economic upheavals, Russia's military aggression and population decline, Ukraine has entered the ‘human development high category’ list of countries. Studies have shown that the country urbanization level continues to grow, while balancing its spatial development potential. This is evidenced by the emergence of the ‘South-West Spatial Vector’, the ‘West Sector’ and the ‘Meridional Axis’ of the urbanization process development. This indicates, first, the ‘spatial structures memory’, the presence of which allows us to interpret post-socialist transformations as a ‘return to pre-socialist development trajectories’ of Ukraine in common Pan-European space; secondly, on the cyclical development and reversibility of ‘waves vibrational motion’ of the world urban process; thirdly, the ‘country urbanized space reaction’ to the Russian military aggression in the East of Ukraine, the annexation of the Autonomous Republic of Crimea and part of the Donbas territories.

The specifics of the post-socialist development of the Kyiv Agglomeration reflect the new status of Kyiv and the general trend of development of the European metropolitan network, as well as the ‘gravitational pattern’ of spatial development, which is manifested by territorial uneven economic development and ‘growth poles wave migration’ from center to periphery and vice versa. The post-Chornobyl growth of the tourist attractiveness of the Chornobyl Exclusion Zone, where 80% of visitors are foreigners, will contribute to the further transformation of Ukrainian cities. In particular, air communication − the development of Kyiv and the Kyiv Agglomeration; roads − development of bordering cities in the west and south of the country, as well as cities in the areas of Pan-European transport corridors influence; railway - the development of Kyiv, Chernihiv, Slavutych; the Dnipro - Visla waterway project implementation, the purpose of which is the connection of the Baltic and Black Seas - the development of city-river ports along the Dnipro and Pripyat Rivers.

Synthesis of Arts in Soviet Architecture: stages of development, main directions, causes of their occurrence

2021-10-29T18:02:46+03:00

The history of the Soviet Union, its socio-economic, socio-political and socio-cultural life is unique in comparison with other countries. The USSR was created on the model of social development, expressed by European and Russian Utopian socialists and was grounded in the classics of Marxism-Leninism. So, the system of government, economic conditions and cultural activities of a society built on the hegemony of the proletariat was a long-running social experiment that conditioned the life of the Soviet people and influenced other countries as well. The experiment of a country with total state property envisaged that the party leadership assumed responsibility for defining all spheres of political life - both internal and interstate relations - and inevitably formed unified programs of cultural activity and social development, managed them, and financed and tightly controlled their implementation. The Soviet people, the so-called "working masses", were forced to live and act under uniform rules. Depending on the planning of the political, economic and social life of the party leadership throughout the existence of the USSR, the country went through several stages, which differed in the directions of forming an architectural and urban planning environment that had to meet the tasks of state and ideological character. Familiarizing yourself with this unique experience and finding the reasons for its formation is important for understanding the trends of social development in the twentieth century.

Project development and marketing in the global oil and gas industry – a constellation of stakeholders co-creating strategic value for the industry

2021-10-29T19:41:53+03:00

Project development and marketing on large oil and gas projects (LOGPs) by engineering-procurement-construction (EPC) contractors respond to massive capital investment (CAPEX) undertakings by oil and gas industry owners and takes on multi-lateral interactions carried out by a dozen of actors proactively participating in the EPC contractors’ business ecosystem created to remain competitive toward owner companies, which form of project marketing is different from a straight forward contractor – owner interaction found in the other branches of contracting industry. Most of such interactions are based on strategic trust among the relevant members built over decades of heavy win-win transactions.

This study has found the actors that compose the project development and marketing cycle in LOGPs, explored dominant logics of EPC contractor’s project development and marketing, and analysed how primary actors in LOGP development and implementation co-create strategic values for both the respective corporations, and sustainable overall industry growth.

One approach to the axisymmetric problem of impact of fine shells of the S.P. Timoshenko type on elastic half-space

2021-10-29T19:55:09+03:00

Refined model of S.P. Timoshenko makes it possible to consider the shear and the inertia rotation of the transverse section of the shell. Disturbances spread in the shells of S.P. Timoshenko type with finite speed. Therefore, to study the dynamics of propagation of wave processes in the fine shells of S.P. Timoshenko type is an important aspect as well as it is important to investigate a wave processes of the impact, shock in elastic foundation in which a striker is penetrating. The method of the outcoming dynamics problems to solve an infinite system of integral equations Volterra of the second kind and the convergence of this solution are well studied. Such approach has been successfully used for cases of the investigation of problems of the impact a hard bodies and an elastic fine shells of the Kirchhoff-Love type on elastic a half-space and a layer. In this paper an attempt is made to solve the axisymmetric problem of the impact of an elastic fine spheric shell of the S.P. Timoshenko type on an elastic half-space using the method of the outcoming dynamics problems to solve an infinite system of integral equations Volterra of the second kind. It is shown that this approach is not acceptable for investigated in this paper axisymmetric problem. The discretization using the Gregory methods for numerical integration and Adams for solving the Cauchy problem of the reduced infinite system of Volterra equations of the second kind results in a poorly defined system of linear algebraic equations: as the size of reduction increases the determinant of such a system to aim at infinity. This technique does not allow to solve plane and axisymmetric problems of dynamics for fine shells of the S.P. Timoshenko type and elastic bodies. This shows the limitations of this approach and leads to the feasibility of developing other mathematical approaches and models. It should be noted that to calibrate the computational process in the elastoplastic formulation at the elastic stage, it is convenient and expedient to use the technique of the outcoming dynamics problems to solve an infinite system of integral equations Volterra of the second kind.

The twentieth century science paradoxes

2021-10-29T20:04:36+03:00

The isolation of hypothetical theories from the realities of living matter has caused mysticism to penetrate scientific theories. With mystical thinking, the idea of using an analytical method to solve cognitive problems does not occur. Dialectical logic, in contrast to mysticism, states the opposite: any problematic tasks of cognizing the vital processes and phenomena of the universe are solvable exclusively in an analytic way, with the only method. The author created a universal and formal theory of solving intellectual (i.e., having no previously known algorithms for solving) problems associated with the knowledge of the vital functions of natural and man-made processes in any phenomena of the universe - the Kondratenko method of axiomatic modeling, the effectiveness of which is achieved by correctly setting the problem and solving it purely formal method. The correctness of the statement of the problem means, first of all, the recognition of the failure of all hypothetical (not confirmed by the results of full-scale experimentation with the subject of knowledge) theories. This requirement, in particular, to the mathematical tools used to solve problems of cognition, it revealed paradoxes in the foundations of mathematics, which are discussed in the article.

At present, in the natural and applied sciences in most publications, i.e. more than 90% associated with the construction of formal theories in these sciences, the proof of theorems is carried out:

firstly, in a meaningful way, which contradicts the urgent requirement of philosophers of science to use exclusively formal evidence, which is a criterion for assessing the correctness and reliability of evidence;

secondly, in substantive evidence in 95% of cases, an exclusively standard list of tautologies is used, which by definition is incorrect for the purpose of proving theorems on phenomena and processes of the universe based on exclusively true axioms obtained as a result of full-scale experimentation with these phenomena and processes. The article deals with the paradox in the classical approach to proving theorems, which consists in the inappropriateness of generally accepted stereotypical tautologies of classical mathematics for proving theorems.