bluuebunny/crossref_metadata_2025_split huggingface dataset:
Determination of the magnitude of short-circuit surge current for the construction of relay protection on reed switches and microprocessors
Authors: Neftissov Alexandr , Biloshchytskyi Andrii , Talipov Olzhas , Andreyeva Oxana 
Published: December 2021

A study of the functioning of reed switches under the influence of a magnetic field created by a current in a conductor in a transient mode with the presence of an aperiodic component has been carried out. A well-known method for determining current using reed switches was implemented. At the same time, it was determined that the originally formulated method did not give the required result within the limits of errors. This is most likely due to the peculiarities of the mechanism of movement of the reed switch contacts. Alternatively, the measurements were taken to take the return currents instead of the pick-up currents and the time between the return times. They are more stable. Simulation is performed, experimental determination of the value of surge current by measuring time is carried out. The main element of the created installation was the power transformer coil with low active and high inductive resistance. As part of the study, the reed switches were placed in a magnetic field with an aperiodic component, as in the transient mode. This study will show the applicability of reed switches for the construction of relay protection devices that will not need current transformers to obtain information about the primary current in the conductor. In the course of the research, it was found that the error in determining the magnitude of current was no more than 10 %. Using microprocessors, it is possible to build relay protection devices with a speed of up to 20 ms. This result makes it possible to build new devices. Since in the well-known developments, it was only said about determining the magnitude of current in a steady state. When building relay protection devices on reed switches, without using current transformers, it will be possible to build backup protections that duplicate not only the devices themselves, but also the primary measuring transformers with other sensitive elements. This will improve the reliability of the power supply.
Prediction of combined cycle power plant electrical output power using machine learning regression algorithms
Authors: Santarisi Nader S. , Faouri Sinan S. 
Published: December 2021

In order to monitor the performance and related efficiency of a combined cycle power plant (CCPP), in addition to the best utilization of its power output, it is vital to predict its full load electrical power output. In this paper, the full load electrical power output of CCPP was predicted employing practically efficient machine learning algorithms, including linear regression, ridge regression, lasso regression, elastic net regression, random forest regression, and gradient boost regression. The original data came from an actual confidential power plant, which was working on a full load for 6 years, with four major features: ambient temperature, relative humidity, atmospheric pressure, and exhaust vacuum, and one target (electrical power output per hour). Different regression performance measures were used, including R2 (coefficient of determination), MAE (Mean Absolute Error), MSE (Mean Squared Error), RMSE (Root Mean Squared Error), and MAPE (Mean Absolute Percentage Error). Research results revealed that the gradient boost regression model outperformed other models with and without using the dimensionality reduction technique (PCA) with the highest R2 of 0.912 and 0.872, respectively, and had the lowest MAPE of 0.872 % and 1.039 %, respectively. Moreover, prediction performance dropped slightly after using the dimensionality reduction technique almost in all regression algorithms used. The novelty in this work is summarized in predicting electrical power output in a CCPP based on a few features using simpler algorithms than reported deep learning and neural networks algorithms combined. That means a lower cost and less complicated procedure as per each, however, resulting in practically accepted results according to the evaluation metrics used.
Defining patterns of heat transfer through the fire-protected fabric to wood
Authors: Tsapko Yuriy , Tsapko Аleksii , Bondarenko Olga 
Published: December 2021

Under the thermal action on wood when applying a protective screen made from fire-retardant fabric, the process of temperature transfer is natural. It has been proven that depending on the thermal properties of the coating of fire-proof fabric, this could lead to varying degrees of heat transfer. Therefore, it becomes necessary to study the conditions for establishing low thermal conductivity and establishing a mechanism that inhibits heat transfer to wood. Given this, a mathematical model has been built of the process of heat transfer to wood when it is protected by a screen made of fire-proof fabric. According to the experimental data on determining the temperature on the non-heated surface of the fabric and the resulting dependences, the density of the heat flow transmitted to wood through fire-proof fabric was determined. Thus, with an increase in the temperature, the density of the heat flow to the surface of the wood through a protective screen made of fire-proof protected coating based on "Firewall-Attic" increases to a value above 16 kW/m2, which is not sufficient for ignition of wood. Instead, the density of the heat flow through the protective screen of fire-proof fabric protected by the "Firewall-Wood"-based coating did not exceed 14 kW/m2. This makes it possible to argue about the compliance of the detected mechanism of formation of heat-insulating properties in the protection of wood and the practical attractiveness of the proposed technological solutions. Thus, the peculiarities of inhibition of the process of heat transfer to wood through a protective screen made of fire-proof fabric under the action of a radiation panel imply the formation of a heat-insulating layer of coked cellular material when decomposing the coating. Thus, on the surface of the fire-proof fabric, a temperature above 280 °C was achieved and, on an untreated surface of the fabric, it did not exceed 220 °C, which is insufficient for the ignition of wood.
Design of an universal source for semi-automatic ac welding and induction heating
Authors: Burlaka Vladimir , Lavrova Elena , Podnebennaya Svetlana , Ivanov Vitaliy , Burikov Serhii 
Published: December 2021

This paper proposes a circuit solution and a power source control algorithm for semi-automatic AC welding with improved energy and weight-size characteristics. A distinctive feature of the designed source is the absence of an input rectifier: welding is carried out with a high-frequency alternating current. That has made it possible to significantly reduce power losses in the source, as well as provide the possibility of implementing induction heating by connecting an inductor to the source output.
Another distinctive feature of the designed source is an increased power factor and a reduced level of higher harmonics of the current consumed. The power factor of the described source reaches 0.94 against 0.5÷0.7 for sources equipped with a conventional rectifier with capacitive smoothing.
The designed source's composition includes a power supply system for the wire feed drive with speed stabilization due to positive feedback on the motor current. That has made it possible to ensure the stable operation of the drive in a wide range of speeds. A model has also been developed of a flux wire welding torch containing a feed drive and a coil with a wire (up to 100 mm in diameter), placed, in order to reduce the size, in the handle of the torch.
In addition to the welding function, the source makes it possible to solve the tasks related to induction heating and/or hardening of small parts; to that end, a compact inductor is connected to its output.
Tests of the source showed the feasibility of the proposed ideas and circuit solutions. The dimensions of the source are 190×107×65 mm; weight, 1.4 kg; output current, up to 120 A. The proposed technical solution enables the construction of small-sized, lightweight, universal, easy-to-use power supplies for semi-automatic welding with the option of induction heating
Implementation of reengineering technology to ensure the predefined geometric accuracy of a light aircraft keel
Authors: Maiorova Kateryna , Vorobiov Iurii , Boiko Maksym , Suponina Valeriia , Komisarov Oleh 
Published: December 2021

The subject of this research is the technology of reengineering and control of parts of aircraft objects (AOs) and technological equipment for their manufacture. The predefined accuracy of the keel of a light aircraft and molding surfaces of technological equipment for its manufacture has been ensured by using reengineering technology and CAD systems. A portrait of the actual physically existing keel of a light aircraft was built in the *.stl file format using the software Artec Studio (USA). The control and comparison of the geometry of the shapes of the analytical standard with the actual physically existing keel of a light aircraft based on its portrait have been implemented. The methods used are the analysis and synthesis of the experimental geometry of shapes, the method of expert evaluations. The following results were obtained: based on the analysis and synthesis, the presence of significant errors in the accuracy of the manufacture of the keel for a light aircraft in the range from −5.26 mm to +5.39 mm was detected. It has been shown that the key factor is the keel's relative plane indicator, which is outside the tolerance margin and is 85 %. It was decided to fabricate new technological equipment from another material – organic plastics. Control of the technological equipment made from organic plastics for the keel of a light aircraft showed that the shape-forming surfaces of the equipment have appropriate shapes and sizes corresponding to the existing analytical standard and are devoid of inaccuracies that occurred in the previous version. The range of keel margins that was made using the new technological equipment from organic plastics is from –0.51 mm to +0.34 mm while the relative plane of the keel outside the tolerance margin does not exceed 15 %. The study results showed the adequacy of the decisions taken, ensuring the predefined accuracy for the keel of a light aircraft and molding surfaces of technological equipment for its manufacture.
Food safety of plasma-chemically activated water and bread made with its use
Authors: Mykolenko Svitlana , Pivovarov Olexandr , Yefimov Valentyn , Sova Nataliia , Tymchak Dmytro 
Published: December 2021

Water treatment by contact non-equilibrium low-temperature plasma refers to innovative methods of processing food raw materials, which requires determining the level of safety of its use to meet the requirements of food safety for humans. The test animals were divided into four test groups with two different basic diets. The tested substances were drinking main water (control group) and plasma-chemically activated water (experimental group); wheat bread (control group) and wheat bread produced using plasma-chemically activated water (experimental group). It was found that there was no significant difference between the control and experimental groups of animals in body weight and its changes during 90 days of the introduction of the test substances into the diet. The amount of water and feed consumed was in direct proportion to the change in the weight of animals in the corresponding diets.
The hematological and biochemical analysis of the blood of the test rats did not confirm the toxic or allergenic effect of the studied feeding factors on their organism. An increase in the number of erythrocytes in the blood and activation of the phagocytic activity of experimental groups of animals were confirmed. This confirms the positive effect of plasma-chemically activated water and wheat bread made with its use on metabolic processes in the body of animals.
Macromorphological parameters of the body of animals and the results of histological studies of the stomach, liver, kidneys and femur as potential target organs demonstrated the absence of dystrophic-degenerative changes in these organs. A comprehensive study of the food safety of plasma-chemically activated water and wheat bread made with its use proves the possibility of using an innovative method of water treatment in food production.
Establishment of the dependence of the strength indicator of the composite material of pressure hoses on the character of single damages
Authors: Nazarenko Sergii , Kushnareva Galina , Maslich Natalia , Knaub Ludmila , Naumenko Nataliia , Kovalenko Roman , Konkin Valery , Sukharkova Elena , Kolienov Oleksandr 
Published: December 2021

Experimental studies are presented and the dependence of the change in the strength of the material of a pressure head fire hose of type T with an inner diameter of 77 mm in the longitudinal direction is established, taking into account single damages. The work describes the plan of the experiment and carried out a number of field experiments to determine the effect of the length ld and the depth K damage on the strength F of the hose material, that is, obtaining the dependence F=f (ld, K). A mathematical method of experiment planning was used and a plan was drawn up for a complete multivariate experiment of type 2k with an acceptable model accuracy of 5 %. The limits of variation of the factors are set taking into account a priori information, experimental capabilities and on the basis of the results of preliminary search experiments. The dependence in the coded and natural values of the factors is obtained. The reliability of the relationship was checked using the Fisher test, the calculated value of which was 5.98, which confirms the adequacy of the described process with a probability of 95 %.
Analyzing experimental studies of the dependence of the change in the strength of the hose material on the length and depth of damage, it can be said that the change in the strength of the hose almost linearly depends on the specified damage parameters. It is found that with increasing damage, the strength of the hose material significantly decreases. When varying the length factor and the greatest depth of damage, K=0.4 mm, the strength of the hose material decreases from 11.67 kN to 8.77 kN, and in percentage terms by 25 %.
The results obtained can be used in practical units of emergency rescue teams, when diagnosing hidden damage in pressure head fire hoses in order to prevent their failure in case of fires
Development of mandelbrot set for the logistic map with two parameters in the complex plane
Authors: Ahmed Wasan Saad , Abbas Saad Qasim , Khamees Muntadher , Jaber Mustafa Musa 
Published: December 2021

In this paper, the study of the dynamical behavior of logistic map has been disused with representing fractals graphics of map, the logistic map depends on two parameters and works in the complex plane, the map defined by f(z,α,β)=αz(1–z)β. where and are complex numbers, and β is a positive integers number, the visualization method used in this work to generate fractals of the map and to inspect the relation between the value of β and the shape of the map, this visualization analysis showed also that, as the value of β increasing, as the number of humps in the function also increasing, and it demonstrate that is true also for the function’s first iteration , f2(x0)=f(f(x0)) and the second iteration , f3(x0)=f(f2(x0)), beside that , the visualization technique showed that the number of humps in that fractal is less than the ones in the second iteration of the original function ,the study of the critical points and their properties of the logistic map also discussed it, whereas finding the fixed point led to find the critical point of the function f, in addition , it haven proven for the set of all pointsα∈C and β∈N, the iteration function f(f(z) has an attractive fixed points, and belongs to the region specified by the disc |1–β(α–1)|<1. Also, The discussion of the Mandelbrot set of the function defined by the f(f(z)) examined in complex plans using the path principle, such that the path of the critical point z=z0 is restricted, finally, it has proven that the Mandelbrot set f(z,α,β) contains all the attractive fixed points and all the complex numbers in which α≤(1/β+1) (1/β+1) and the region containing the attractive fixed points for f2(z,α,β) was identified
Interaction of surfactants with poloxamers 338 and its effect on some properties of cream base
Authors: Bezuglaya Elena , Lyapunov Nikolay , Lysokobylka Oleksii , Liapunov Oleksii , Klochkov Volodimir , Grygorova Hanna , Liapunova Anna 
Published: December 2021

The aim. Study of the interaction of surfactants with poloxamer 338 (P338) and the effect of P338 on the properties of cream bases.
Materials and methods. Solutions of the surfactants and P338 as well as cream bases were under study. The average hydrodynamic diameter (Dh) and zeta potential (ζ‑potential) were determined by the light scattering intensity and electrophoretic mobility of micelles. The electron paramagnetic resonance (EPR) spectra of spin probes in micelles, solvents and bases were obtained; the type of spectrum, isotropic constant (AN), rotational correlation times (τ) and anisotropy parameter (ε) were determined. Liquids and cream bases were studied by capillary and rotational viscometry; the flow behaviour and yield stress (t0), dynamic and apparent viscosity (η) as well as the hysteresis (thixotropic) area (AH) were determined. The microstructure of the bases was examined by optical microscopy. The strength of adhesion (Sm) was assessed by the pull-off test, and the absorption of water was studied by dialysis.
Results. Under the impact of P338 the hydrodynamic diameters of micelles formed by cationic, anionic and nonionic surfactants decreased as well as the absolute values of their ζ‑potential became lower, but the microviscosity of the micelle nuclei increased. There was also a change in the structure of the aggregates of surfactant with fatty alcohols; EPR spectra, which were superpositions characteristic for the lateral phase separation, converted into triplets that indicated the uniform distribution of lipophilic probes in the surfactant phase. When the content of P338 increased to 17 %, the rheological parameters of the bases increased drastically, the flow behaviour and the microstructure changed. The bases had the consistency of cream within temperature range from 25 °C to 70 °C and completely restored their apparent viscosity, which had decreased under shear stress. P338 enhances the adhesive properties of the bases. Due to their microstructure, cream bases have a lower ability to absorb water compared to a solution and gel containing 17 % and 20 % P338, respectively.
Conclusions. The structure of surfactant micelles and aggregates of surfactants with fatty alcohols changed under impact of P338 due to the interaction of surfactants with P338. As a result of this interaction, at a sufficiently high concentration of P338, the microstructure and flow behaviour of bases changed, their rheological parameters, which remain high at temperatures from 25 °C to 70 °C, increased significantly, and water absorption parameters decreased. The bases with P338 were more adhesive
Synthesis and antibacterial activity of 3-arylaminomethyl-1-(2-oxo-2-arylethyl)-6,7,8,9-tetrahydro-5H-[1,2,4]triazolo[4,3-a] azepin-1-ium bromides and aryl-(4-R1-phenyl-5,6,7,8-tetrahydro-2,2a,8a-triazacyclopenta[cd]azulen-1-ylmethyl)-amines
Authors: Demchenko Nataliya , Suvorova Zinaida , Fedchenkova Yuliia , Shpychak Tamara , Shpychak Oleh , Bobkova Ludmila , Demchenko Sergii 
Published: December 2021

The aim of this work is to develop methods of synthesis of 3-arylaminomethyl-1-(2-oxo-2-arylethyl)-6,7,8,9-tetrahydro-5H-[1,2,4]triazolo[4,3-a]azepin-1-ium bromides and aryl-(4-R1-phenyl-5,6,7,8-tetrahydro-2,2a,8a-triazacyclopenta[cd]azulen-1-ylmethyl)-amines and to study their antimicrobial activity against strains of gram-positive and gram-negative bacteria as well as yeast fungi.
Materials and methods. 1Н NMR spectra were recorded on Bruker 400 spectrometer operating at frequency of 400 MHz. Antimicrobial activity of the compounds synthesized was evaluated by their minimum inhibitory concentration (MIC) values.
Results and discussion. The interaction of 3-arylaminomethyl-6,7,8,9-tetrahydro-5H-[1,2,4]triazolo[4,3-a]azepines with substituted phenacyl bromides produced novel 3-arylaminomethyl-1-(2-oxo-2-arylethyl)-6,7,8,9-tetrahydro-5H-[1,2,4]triazolo[4,3-a]azepin-1-ium bromides. The latter when refluxed in 10 % solution of NaOH gave aryl-(4-R1-phenyl-5,6,7,8-tetrahydro-2,2a,8a-triazacyclopenta[cd]azulen-1-ylmethyl)-amines. The study of antimicrobial activity of the compounds obtained allowed to find derivatives which are active against С. albicans and S. aureus strains. Among the compounds tested 3-[(41-bromophenylamino)-methyl]-1-[2-(4-methoxyphenyl)-2-oxoethyl]-6,7,8,9-tetrahydro-5H-[1,2,4]triazolo[4,3-a]azepin-1-ium bromide 5cd appeared to be more active than the reference drug Cefixime and displayed close antimicrobial activity as the antibiotic Linezolid.
Conclusions. It was found out that derivatives of 3-arylaminomethyl-1-(2-oxo-2-arylethyl)-6,7,8,9-tetrahydro-5H-[1,2,4]triazolo[4,3-a]azepin-1-ium bromides display broad spectrum of antimicrobial activity and are able to inhibit growth of both bacteria and fungi. S. aureus and C. albicans turned out to be the most sensitive strains to the compounds tested, MIC was in the range of 6.2-25.0 mg/mL. Gram-negative strains of microorganisms were less sensitive to the compounds evaluated and 5fа was the most active derivative displaying antimicrobial activity at the concentration of 50.0 mg/mL. Antimicrobial activity of triazoloazepinium bromide derivatives was similar to that one of Linezolid and Fluconazole reference drugs and more pronounced than the activity of Cefixime.
Hence, the data gathered evidence the feasibility of further study of the antimicrobial properties of the most active compounds in in vivo experiments aiming at assessment of the prospects for the creation of new effective and safe antimicrobial drugs based on them