bluuebunny/crossref_metadata_2025_split huggingface dataset:
Assessment of the technical condition of intercoolers for turbocharged internal combustion engines
Authors: Sergienko S N , Mikhailov A D , Poslavsky A P , Kletsova O A 
Published: June 2021

AbstractThe presented work considers the analysis of methods and means for assessing the technical condition of charge air coolers in vehicles in operation. Metallographic studies of the fragments of samples, identified local sections of the heat exchanger, have been carried out. Various defects of the internal heat transfer surface, caused by the influence of operational factors, have been revealed. The article also touches upon the problem of imperfection of methods and means of instrumental control of the operating parameters of the heat exchange equipment of road transport. It is proposed to carry out diagnostics of the technical condition of heat exchangers at specialized stands equipped with an instrumentation and apparatus complex. The prospects of new developments in the field of diagnostic equipment for determining the operating characteristics of heat exchangers with the ability to measure the most important parameter - heat transfer are noted. An important addition, confirming the relevance of the chosen direction of research, is the substantiation of the value of the described developments not only as a tool for measuring the parameters of the state of heat exchangers, but also to solve the problem of predicting their residual resource. The results of the conducted research are presented. Using the method of physical modeling, an algorithm has been developed for diagnosing the technical condition of the charge air cooler in operation. Issues of provision with methods and means of diagnosing parameters of heat exchangers of vehicles in operation and repair are considered.
Factors influencing the surface quality of architectural concrete
Authors: Tsimbalyuk Y , Karpova E , Sedova A , Skripkiunas G 
Published: June 2021

Abstract
Architectural concrete has wide opportunities to be used both for exteriors and interiors in different buildings. Architectural concrete is the type of concrete which is usually not subjected to finishing, therefore higher standards are declared for its surface quality. According to normative documents, architectural concrete needs to have a uniform colour tone, texture, minimal defects and porosity of the surface. The present research demonstrates the concrete surface quality obtained in the course of varying different factors such as the presence of stabilizing admixture, granulometry of aggregates, usage of fly ash and workability of the concrete mixture. In the course of the research, the testing of raw materials and concrete in the fresh and hardened state were performed according to standard methodologies. The assessment of concrete surface quality was provided through the analysis of concrete surface photo 50x50 cm size. Based on the experimental results, it can be stated that better quality of the concrete surface was obtained in case of usage of gravel with two fractions of 4/16 and 2/8 and fly ash in the dosage of 25 % cement weight in the presence of plasticizing and stabilizing admixtures. The concrete mixture with high workability showed better filling of formwork and mixture particles packing on the formwork surface which led to a better quality of the concrete surface.
Impact of acid treatment on the puzzolan activity of natural zeolite tuff
Authors: Smorodinova T N , Kotvanova M K 
Published: June 2021

Abstract
Using the methods of thermal gravimetric analysis, and X-ray phase analysis, the puzzolan activity of the natural zeolite tuff of the Lyulinsky deposit of Khanty-Mansiysk Autonomous District -Yugra as a mineral additive to cement was evaluated. Acid modification of natural zeolite tuff was performed. The selection of modification conditions was carried out by varying the concentration of the acid solution, the time of exposure to the reagent, and the temperature. The optimal parameters were: the concentration of hydrochloric acid 3 M, the duration of acid exposure-5 hours, the temperature of 80°C. It was found that the treatment of tuff with 3M hydrochloric acid solution leads to a significant increase in puzzolan activity. The strengthening effect of the modified additive is shown. The strength of cement samples with the addition of zeolite tuff at a similar age increases by 28%. The effect of the addition of zeolite tuff on the phase composition of cement during hydration and hardening is studied. A more significant decrease in the content of portlandite was recorded when using a modified additive compared to the addition of zeolite tuff in its native state, which is consistent with the data obtained from the mass loss curves. At the same time, an increase in the content of ettringite, which contributes to the strengthening of the structure of the binder part of the cement stone, is shown. The degree of hydration of cement was estimated by the change in the content of alite. A complexometric determination of the aluminum content in the washing waters after acid treatment of zeolite tuff was carried out. It is shown that acid treatment leads to its dealuminization, which is associated with the restructuring of the zeolite framework. This, in turn, provides an increase in the number of active acid centers responsible for its adsorption properties and reactivity on the surface of the aluminum-silicate framework of the zeolite.
Wind tower based on unexploited industrial chimneys of St. Petersburg
Authors: Krasnozhen S E , Cherenkov V S , Ivanova V A , Elistratov V V 
Published: June 2021

Abstract
Due to the expansion of St. Petersburg from the beginning of the 20th century, the city has formed a Gray Belt of unexploited factories, some of which are architectural heritage. The modern solution to the problem of the Gray Belt is the creation of lofts and public spaces from them, however, it is also practiced transforming former factories into a site for generating “green energy”. Because of the finiteness of the extracted minerals, the use of renewable resources is the most favourable way of producing electricity. The purpose of this work is to consider the possibility of using an industrial pipe to generate energy on the example: one of the highest unexploited pipes in Grey Belt - a steamshop’s chimney (100m), built-in 1955. The result of the study is to determine the inexpediency of using the principle of a wind tube in chimneys in the Gray belt in St.Petersburg, because, based on the calculations, according to the developed method, the height required for the wind turbine to start moving is 154 m in the summertime in St. Petersburg. During the consideration of the highest pipe in the Leningrad Region (320m), there was concluded that it can provide electricity for 31 people.
Corrosion resistant fine-grained ash concrete for repairs of constructions in the linen production
Authors: Petropavlovskaya V , Sulman M , Novichenkova T , Petropavlovskii K 
Published: June 2021

Abstract
The article deals with the study of the compositions of corrosion-resistant concrete. They can be successfully used to prevent the destruction of structures in linen processing plants. Such plants include single workshops with an aggressive environment. Keeping retted stalks in compositions that are aggressive for structures is reflected in the condition of reinforced concrete and concrete structures of these workshops. Violation of the integrity of such structures can lead to severe environmental consequences. To eliminate such consequences, it is necessary to carry out reconstruction. Repair and reconstruction of structures must be organized through the use of innovative concrete. Such concretes must have a high density and resistance to corrosion. Analysis of information sources showed the effectiveness of using ashes with a high content of aluminosilicates. The work identified factors that determine the strength and density of concrete with the addition of ash. Based on the results of the work, recommendations were formed on the use of plasticizers. The composition of the organo-mineral complex has been developed.
Selection of a rational algorithm for data processing of the weight measuring system of a hoisting crane
Authors: Ivanov S D , Nazarov A N , Mikhalchik N L 
Published: June 2021

Abstract
The paper deals with the choice of the algorithm for processing the data of the load sensor of the crane weight measuring system being developed. The requirements for the weight measuring system are based on the operating conditions of the crane (the nature of the dynamic process, the limitation of the weighing time) and the planned use of information about the weight of goods (the required accuracy). A comparison of 5 signal processing algorithms is presented: direct averaging, search for extremes with two different modes of pre-smoothing, nonlinear regression, and averaging using a short-term memory buffer. A series of experiments was conducted to compare the methods. The data was obtained on the KMG-201 bridge crane. Based on the results of numerical evaluation of the results of experimental data processing, conclusions are drawn about the applicability of the considered algorithms for analyzing the dynamic process of the crane lifting mechanism. The algorithms for finding extremes, regardless of the pre-smoothing modes, did not show the required accuracy (the relative error was 5%). The averaging algorithm using a short-term memory buffer showed the highest accuracy (the relative error was 1%). The influence of the parameters of the data reception board on the result of the algorithms is estimated. The parameters varied in the range: bit depth 10-12 bits, sensor polling frequency 4.1-256 Hz. Most experiments showed an increase in accuracy with increasing bit depth. Also, according to the results of the experiments, it was found that an increase in the sensor polling frequency of more than 64 Hz in the conditions of this dynamic process does not affect the accuracy of determining the weight of the load. The study showed the need for further work in the direction of determining the optimal parameters of the averaging algorithm with a short-term memory buffer and determining the limit of increasing accuracy with increasing the bit depth of the data reception board.
Research of the composition of cement-sandy binders modified by waste of processing of petroleum bituminous rocks
Authors: Kuatbayeva T K , Zhambakina Z M , Abiyeva G S , Karshyga G O 
Published: June 2021

Abstract
The paper deals with the issues of technology of binding silicate materials with the use of mineral waste from the processing of petroleum bituminous rocks (PBR) – optimization of the ratio of raw components of the mixture of binders, development of optimal technological parameters for their production.
The optimal compositions of binders were studied using waste from the processing of PBR as an activating component of cement. The influence of mechanic and chemical activation on the change in the acid-base parameters of the suspension from the crushed material was revealed. The effect of the content of additives on the degree of hydration was studied. The influence of the hardening conditions on the strength of the binder with additives of waste from the processing of PBR was studied. As a result of the experimental work carried out, technological processes for the production of binders based on waste from the processing of PBR were justified and developed. The optimal ratio of the mixture of waste from the processing of PBR with cement and the technological parameters that allow ensuring the optimal grade of the cement-sand binder are found. Silicate materials based on it have high physical and mechanical properties, meet regulatory requirements and have high resistance under operating conditions.
Effective building mixtures based on hemihydrate plaster and highly dispersed mineral fillers
Authors: Petropavlovskaya V , Zavadko M , Novichenkova T , Sulman M , Buryanov A 
Published: June 2021

Abstract
The work was aimed at developing a gypsum dry construction mixture with highly dispersed fillers based on industrial waste for interior decoration. The problem of creating effective gypsum materials was solved by improving the structural, physical and mechanical properties of gypsum stone by modifying it with highly dispersed fillers. The effect was achieved by creating a multicomponent composition based on hemihydrate plaster. The proposed work is aimed at developing a gypsum dry construction mixture with highly dispersed fillers for interior decoration of buildings. Dry construction mixes based on gypsum binder are one of the most relevant materials on the building supplies market. They meet the most important aspects from the standpoint of efficiency and safety - environmental, fire and others. However, the problem of ensuring high performance properties requires a solution. In this work, the problem is solved by improving the structural, physical and mechanical properties of gypsum stone by modifying it with highly dispersed fillers. The effect was achieved by creating a multicomponent composition based on plaster. Additionally, the problem of environmental protection is being solved, since secondary products were used as fillers - waste from the production of basalt products and thermal power plants. They differ in the required grain and chemical composition. Acid ash was used. Basalt and acid ash particles have a mechanical effect on the structure of the gypsum stone and influence the processes of structure formation of the gypsum stone. They change the morphology of gypsum crystals. This improves the mechanical strength, the average density of the modified gypsum stone and other physical and mechanical characteristics.
Changes in the structural and phase composition and strength characteristics of concrete during liquid corrosion in chloride-containing media
Authors: Rumyantseva V E , Konovalova V S , Narmaniya B E 
Published: June 2021

Abstract
The results of physico-chemical studies that allow us to judge the changes occurring in the cement stone under the influence of liquid chloride-containing media are analysed. Samples of CEM I 42,5N Portland cement with a water-cement ratio of W/C = 0,3 were exposed to solutions of 2 % MgCl 2, 0,001 % HCl and 0,1 % CaCl 2 for 150 days. Changes in the strength characteristics of CEM I 42,5N Portland cement samples under the influence of chloride-containing media were studied. It is established that the 2 % MgCl 2 solution is an extremely aggressive medium in the conditions of liquid corrosion of concrete, its action causes a deterioration in the strength characteristics of concrete by 1,5 times. The changes in the structural and phase composition of concrete that occur under the influence of chloride-containing media are studied. The relationship between the characteristics of the cement stone structure and the strength parameters of the cement stone is established. The decrease in the strength of cement concrete is associated with the decomposition of calcium hydrosilicate C 2SH under the influence of liquid aggressive chloride-containing media, as evidenced by the decrease in intensity and the disappearance of the lines corresponding to this compound on X-ray images.
Control of rock massifs state for sustainability of natural and man-caused slopes and underground structures under influence of contemporary seismic and tectonic processes
Authors: Melikulov A D , Salyamova K D , Yu Gasanova N , Ismailov A S 
Published: June 2021

Abstract
The article deals with issues related to the peculiarities of the formation and change in time of the stress-strain state of rock massifs as objects of active man-caused impact of engineering facilities, both surface and subsurface, hydrotechnical and road construction, mining operations, including development of mineral deposits by open-cut and underground methods. Arrays of rock formations have a wide range of properties that manifest themselves as hazardous natural geological events, and also under any technological influences to them, including the method of blasting destruction. The peculiarities of the behavior of such arrays consist in the combination of the characteristics of solid as elastic and plastic bodies, including brittle, and viscous-flowing bodies, and creep.
Technological impact on the rock mass can lead to undesirable dangerous consequences both from the point of view of the object’s stability and safety, and the need for additional material costs to maintain the equilibrium in the new conditions. The identification of the potential area of permissible deformations and the conditions for the destruction of such an array of rocks, taking into account the time factor, is of practical interest for selecting effective parameters of mining technology that allow the prevention of dangerous undesirable consequences of destruction.
Research methods of the process of heat and mass transfer in different media with diffusion and subdiffusion
Authors: Aleroeva H , Aleroev T 
Published: June 2021

Abstract
The problem of studying the laws governing the formation of the radon environment is not new. The development of the mining industry (to study the regularities of the formation of the radon environment in mine workings, it was necessary to simulate the flux of radon density, which led to the construction of various models of radon transfer), became the main catalyst for in-depth research in this direction. It should also be noted that according to the RF radiation safety standards (NRB-99), the average annual equivalent equilibrium volumetric activity (concentration) of radon in the air of residential and public buildings should not exceed the established limit. To implement this decree, various models of mass transfer (radon) were built. Most of these models are based on the advection-diffusion equation, which simulates the processes of mass transfer of matter or heat transfer in a medium with fractal geometry (in particular, in porous media). Moreover, the order of the fractional time derivative in this equation corresponds to the proportion of channels (the system described by this equation is open, that is, it is connected to the outside world either by a finite or infinite number of communication channels) open for flow in a fractal (porous) medium. This process is non-local in time. And the environment in which this process takes place will be an environment with memory. In this paper, we analyze boundary value problems for the considered equation. A method based on the separation of variables is presented, while the solution of the problems posed is written out in the form of an infinite series in the eigenfunctions of the operator generated by an ordinary differential expression of the fractional order (the order of the fractional derivative is greater than one but less than two) and boundary conditions of the Sturm-Liouville type.
Development of innovative methods of increasing the service life of equipment and pipelines
Authors: Sadigov Rovshan , Mehdiyeva Almaz , Sardarova Ijabika 
Published: June 2021

Abstract
Knowing the specific technological parameters of water source and piping systems, it is possible to determine the service life of the pipe set, as water source as pipelines, by the offered method. Complex-acting, multifunctional, thermally resistant, bactericidal type new corrosion inhibitor based on naphthenates has been developed; The technology of insulation of the surface of metal pipes with coatings made of non-corrosive, shock-resistant and corrosion-resistant basalt-plastic and glass-plastic materials has been developed. Possibility of application of basalt-plastic and glass-plastic materials in construction and repair of tanks and other capacities was studied; Technologies for the production of protective belts, transport pipes, as well as rods from pure basalt-plastic and fiberglass materials in the highly corrosive environment were developed and their application together with metal pipes and rods was analyzed. Knowing the specific technological parameters of water source and piping systems, it is possible to determine the service life of the pipe set, as water source as pipelines, by the new method. During the research, the physicochemical factors affecting the object were investigated and methods of elimination were developed: Innovative methods of corrosion protection to increase the service life of equipment and transport pipelines, as well as a statistical method to determine the dependence of the capacity of equipment and transport pipelines on mechanical, physical and chemical factors; complex-acting, multifunctional, thermally resistant, bactericidal type new corrosion inhibitor based on naphthenates has been developed.
Instability and merging of a helical vortex pair in the wake of a rotor
Authors: Schröder D , Leweke T , Hörnschemeyer R , Stumpf E 
Published: June 2021

Abstract
We present results from an experimental investigation of two closely spaced helical vortices. The two co-rotating vortices are generated in a water channel by a one-bladed rotor, whose tip geometry is modified by the addition of a perpendicular fin on the pressure side. The fin parameters are tuned so that the two vortices have approximately equal circulation. Dye visualisations and flow field measurements from Particle Image Velocimetry show that the vortices merge into a single tip vortex within less than one rotor rotation. This fast merging is caused by a rapid increase of the core radii of the initial vortices, which indicates the presence of an instability phenomenon. Analysis of the vortex velocity profiles identifies it as a centrifugal instability, linked to the presence of opposite-signed vorticity in the blade tip region. We further explore the origin of this vorticity by modifying the streamwise fin position. Measurements suggest that the interaction between the secondary fin vortex and the blade surface is partly responsible for the generation of the unstable velocity profile. The vortex resulting from the merging has a significantly larger core size than the one developing without a fin, indicating that this configuration could be beneficial in the context of Blade-Vortex Interaction noise for helicopters, or for the reduction of fatigue loads on wind turbine rotors caused by the interaction with concentrated tip vortices in the wake of upstream turbines.
LES Modelling of Highly Transient Wind Speed Ramps in Wind Farms
Authors: Andersen S J , Sørensen N. N. , Kelly M. 
Published: June 2021

Abstract
Large eddy simulations of wind farms are often performed with canonical atmospheric conditions, where the background flow is based on precursor simulations with idealized model setups yielding statistically stationary turbulent flows. However, precursor simulations can only handle gradually changing flow conditions, and are not capable of modelling highly transient and statistically non-stationary flows, e.g. frontal passages or large gusts. Such flows frequently occur in nature, and can influence the operation—and potentially design—of wind turbines. It is generally not possible to impose non-stationary features through inlet boundary conditions, if the imposed flow violates the most fundamental assumption of micro-scale flow simulations, namely conservation of mass.
This work presents a method for modelling highly transient wind speed ramps by extending and adapting the method of applying body forces to achieve specific flow scenarios, where the wind speed ramps are embedded as constrained turbulent boxes. Several scenarios with significant increases in the streamwise wind speed are simulated. Analyses of the transient wake dynamics, as the wind speed ramps propagate through large wind farms are performed to show how well the momentum is maintained throughout the numerical domain and the influence and operation of turbines during the ramp passages.