bluuebunny/crossref_metadata_2025_split huggingface dataset:
Features for the design of a specialized information-measuring system for the study of thermoelectric properties of semiconductors
Authors: Dunets Roman , Dzundza Bogdan , Turovska Liliia , Pavlyuk Myroslav , Poplavskyi Omelian 
Published: May 2021

Methods for studying thermoelectric parameters of semiconductors that are optimal for the implementation of software and hardware have been analyzed and selected. It is based on the Harman method and its modifications, adapted for pulse measurements, which are convenient to implement on a modern element base. An important advantage of these methods is the absence of the need for accurate measurements of heat fluxes, which greatly simplifies and reduces the time for conducting experimental research.
The required operating ranges for the voltage 10 µV–1 V, for the current 10 µA–300 mA and the element base performance at the processing level of 40–200 million samples per second have been determined. Structural and electrical circuits, as well as software for a specialized computer system for studying thermoelectric parameters of both bulk and thin-film thermoelectric materials, and express analysis of the operational characteristics of finished modules have been developed. It has been shown that the proposed scheme copes well with the task. And the use of FPGA and 32-bit microcontrollers provide sufficient processing speed up to 200 MSPS and the necessary synchronization modes for the implementation of the Harman pulse method even when studying films of nanometer thickness.
Experimental studies of both bulk thermoelectric modules based on Bi2Te3 and thin-film thermoelectric material based on PbTe have been carried out. The effectiveness of the developed tools and techniques has been shown, which made it possible to more than halve the time for sample preparation and experiment. Based on the presented models, all the main thermoelectric and operational parameters have been determined, in particular, electrical conductivity, Seebeck coefficient, thermal conductivity, thermoelectric figure of merit.
As a result of the development of specialized computer tools, it was possible to reduce the labor intensity of the process of measuring the main electrical and operational parameters of semiconductor thermoelectric materials and energy conversion modules based on them, as well as to automate the process of defects identification of thermoelectric modules. The labor intensity of the research process has decreased not only due to the automation of the measurement process, but also due to an optimized technique that allows research on a sample of one configuration, since the manufacture and preparation of samples are the most laborious
Designing a structure of the magnetically active part of dipole electromagnets for the system of vertical convergence-separation of beams
Authors: Getman Andriy 
Published: May 2021

This paper reports the results of calculating the magnetic parameters for a direct dipole magnet in the system of vertical convergence-separation of particle beams of the upper and lower rings of the heavy-ion collider. An optimized variant of the yoke and superconducting winding structures has been obtained, providing for the assigned value of a homogeneous magnetic field inside the aperture at the minimized contributions of higher-order harmonics, average-integral along the length. The results from the analysis of the transverse projections of the magnetic induction obtained by 2D modeling of two variants of the design of the central cross-section of the dipole electromagnet are presented. The analysis results have established the dependence of the stability of magnetic parameters in the aperture of the electromagnet when the current in the winding changes on the volume of those yoke regions whose magnetization value is close to saturation. A 3D model of the magnetically active part has been built for two variants of the electromagnet design, and the values of the average-integral harmonics of transverse projections of magnetic induction in the aperture have been calculated. The relationship between the third average-integral harmonic of magnetic induction and the size lengths of the yoke and winding has been empirically established, making it possible to correct the heterogeneity of the transverse magnetic field in the aperture of the electromagnet. The results of optimization of the structure of the magnetically active part of the electromagnet are presented on the criteria for a minimum of the values of the average-integral coefficients of magnetic induction, carried out on the basis of correction of the initial geometric parameters of the yoke and winding. An improvement in the stability of magnetic parameters has been demonstrated, by 3 times, as well as a two-fold reduction in the contribution to the heterogeneity by the third average-integral harmonic when using a two-row arrangement of the winding turns inside the yoke in the design of the electromagnet
Development of a model of electric impedance in the contact between the skin and a capacitive active electrode when measuring electrocardiogram in combustiology
Authors: Savchuk Arsen 
Published: May 2021

Long-term ECG (electrocardiogram) measurement in patients with burns is a complicated problem since the overlapping of surface contact electrodes can lead to additional injuries. The possibility of ECG recording in patients with burns using capacitive electrodes was not proved, and there are no models of the electrode contact with a patient’s body while rehabilitation means are used.
In this paper, the model of the contact between capacitive electrodes and the skin was modified and the circuit model of the contact: skin – bandages (saline solution) – film – active capacitive electrode, was described. The influence of the parameters of a capacitive electrode on the amplitude-frequency characteristics (AFC) of the contact of an electrode with skin was assessed. It was found that contact capacitance is crucial to obtain a high-quality ECG signal. The parameters of the impedance of bandages, saline solution, a dielectric film were calculated, and their effect on the AFC was studied. Based on the modified model, the AFC contact was modeled taking into consideration all the calculated parameters; it was found that the resulting AFC of the contact corresponds to the frequency range of the ECG signal. Analysis of the calculations proves the possibility of using capacitive electrodes when applying various rehabilitation means. It was found that at a change in the impedance of the saline solution from 0.1 gigaohms to 1 gigaohm, the changes in the AFC of the contact are not crucial for the final quality of the received signal.
All calculations were carried out by modeling in the Qucs environment (ngspice SPICE).
Simulation results can be used in the development of new types of capacitive electrocardiographic electrodes. The proposed model can be used to study other wound covers, as well as to model physiological processes when putting artificial skin and wound covers
Development of a three-zone combustion model for stratified-charge spark-ignition engine
Authors: Korohodskyi Volodymyr , Rogovyi Andrii , Voronkov Oleksandr , Polivyanchuk Andrii , Gakal Pavlo , Lysytsia Oleksii , Khudiakov Igor , Makarova Tamara , Hnyp Mariіa , Haiek Yevhen 
Published: May 2021

A thermodynamic model for calculating the operating process in the cylinder of a spark-ignition engine with internal mixture formation and stratified air-fuel charge based on the volume balance method was developed. The model takes into account the change in the working fluid volume during the piston movement in the cylinder.
The equation of volume balance of internal mixture formation processes during direct fuel injection into the engine cylinder was compiled. The equation takes into account the adiabatic change in the volume of the stratified air-fuel charge, consisting of fuel-air mixture volume and air volume. From the heat balance equation, the change in the fuel-air mixture volume during gasoline evaporation in the fuel stream and from the surface of the fuel film due to external heat transfer was determined.
Basic equations of combustion-expansion processes of the stratified air-fuel charge were derived, taking into account three zones corresponding to combustion products, fuel-air mixture and air volumes. The equation takes into account the change in the working fluid volume due to heat transfer and heat exchange between the zones and the walls of the above-piston volume. Dependences for determining the temperature in the three considered zones and pressure in the cylinder were obtained.
Graphs of changes in the volumes of the combustion products, fuel-air mixture and air zones with the change of the above-piston volume in partial load modes (n=3,000 rpm) were plotted. With increasing load from bmep=0.144 MPa to bmep=0.322 MPa, at the moment of fuel ignition, the volume of the fuel-air mixture increases from 70 % to 92 % of the above-piston volume. At the same time, the air volume decreases from 30 % to 8 %.
Analysis of theoretical and experimental indicator diagrams showed that discrepancies in the maximum combustion pressure do not exceed 5 %
Modeling of a system of quality assessment indicators of measuring instruments
Authors: Velychko Oleh , Hrabovskyi Oleh , Gordiyenko Tetyana , Volkov Serhii 
Published: May 2021

Modern measuring instruments (MI) are of great importance for providing measurements in all areas of the national economy. Their main purpose is to conduct accurate and reliable measurements in order to obtain complete and reliable measurement information. To perform this important function, MI must be of appropriate quality, which must be reliably assessed.
In the traditional definition, MI is a technical means that is used in measurements and has standardized characteristics. For technical means, there is a traditional system of quality indicators. In addition to these quality indicators, additional specific indicators should be established for MI, which should objectively assess the metrological characteristics.
The expediency of creating and using a special system of quality indicators for all stages of the MI life cycle is proved. Building such a system requires maximum use of quantitative characteristics that express certain quality indicators. Important indicators of this system are a number of MI indicators related to metrological characteristics. For MI, it is also advisable to use a common system of quality indicators for technical facilities.
The proposed multiple models of MI quality indicators and evaluation of MI quality indicators allow studying the influence of MI quality indicators and performing their evaluation at all stages of the MI life cycle. Understanding and managing the system for evaluating MI quality indicators helps to increase efficiency in achieving planned results. For effective implementation of these models, it is necessary to use regulated requirements of some international and regional standards and recommendations
Improved control of energy consumption by a photovoltaic system equipped with a storage device to meet the needs of a local facility
Authors: Shavolkin Olexander , Shvedchykova Iryna , Jasim Jasim Mohmed Jasim 
Published: May 2021

+This paper has considered improving the management of energy consumption by a photovoltaic system with a storage device for a local object connected to the network. The aim of the study is to reduce expenditures when paying for electricity consumed from the network, when loading an object, independent of the time of year, and to eliminate energy generation to the grid. An energy generation control algorithm has been improved whereby the state of battery charge during the day is based on a forecast. That could reduce electricity consumption at night with better utilization of rechargeable battery and photovoltaic battery power during the day. It is proposed to use autonomous operation by disconnecting from the network during peak tariff hours and during the day with enough energy generation by a photovoltaic battery. This would ensure the normal functioning of an object in the event of a possible deterioration in the quality of voltage in the network while reducing the loss of energy in the inverter. Predictive control of the expected battery charge at the next checkpoint (at 0.5 hours or less between control points) has been proposed. A control system structure has been developed whereby a rechargeable battery current is set depending on an operational mode, the tariff zone, and the projected generation by a photovoltaic battery while reducing the modulation frequency under an autonomous mode. In this case, the modes are switched and the structure is changed taking into consideration the state of battery charge. Simulation in the daily cycle has shown the possibility of reducing the cost of electricity consumed from the network by 1.7‒8 times at two or three tariff rates. Simulation of electromagnetic processes in the system confirms acceptable regulation indicators when switching the structure, as well as a decrease in the energy loss in an inverter under an autonomous mode by up to 40 %
Devising a procedure for substantiating the type and volume of redundant structural-functional elements of reconnaissance-firing systems
Authors: Maistrenko Oleksandr , Karavanov Oleksandr , Riman Oleksii , Kurban Volodymyr , Shcherba Andrii , Volkov Ihor , Kravets Taras , Semiv Galina 
Published: May 2021

This paper proposes an algorithm for substantiating the type and volume of redundant structural and functional elements of reconnaissance-firing systems, taking into consideration the operational patterns of such systems. Underlying this algorithm is the combination of survivability assessment methods and reliability assessment methods. Such an arrangement aimed to improve the efficiency of the application of these methods and reduce uncertainty in the calculations.
The results from calculating an example of the application of a procedure for substantiating the type and volume of redundant structural and functional elements of reconnaissance-firing systems have been analyzed. The analysis of the results shows that the set task is fulfilled, in particular the specified probability of trouble-free functioning of a reconnaissance-firing system, with a combined type of redundancy. Moreover, it implies giving preference to passive redundancy, using active one only to critical elements – individual functional elements of the control subsystem. The advantage of a mixed type of redundancy over a passive redundancy is 28 %. In addition, it has been established that the multiplicity of redundancy, for accepted conditions, should not be lower than 2. A procedure for substantiating the type and volume of redundant structural and functional elements of reconnaissance-firing systems has been devised, taking into consideration the operational patterns of such systems. The specified procedure includes an algorithm, as well as methods for assessing survivability and methods for assessing the reliability of functioning. This procedure was tested for feasibility by considering an example of justifying the type and volume of redundant structural and functional elements of reconnaissance-firing systems that produced an adequate result. The result has been confirmed by the practical application of reconnaissance-firing systems in recent armed conflicts
Devising a method to improve the accuracy of maintaining the pre-set temperature and humidity conditions at a vegetable storage facility under a food storing mode
Authors: Kachanov Petro , Yevseienko Oleh , Yevsina Nataliia 
Published: May 2021

A vegetable storage facility is an energy-consuming object with distributed parameters. The quality of product storage depends on the microclimate in the vegetable storage facility: current temperature, humidity, and carbon dioxide level. Existing temperature controllers in a vegetable storage facility use a two-position law of control, which leads to the consumption of excess energy and product spoilage.
The purpose of the study is to improve the work of the controller in the process of product storage at the storage phase due to closing the two-position controller through feedback in the form of a first-order aperiodic link.
To achieve the goal, the procedure for calculating the transfer function of a control object through the equation of thermal balance was used. This procedure made it possible to take into consideration the parameters of a vegetable storage facility: the area and the type of thermal insulation material of floorings, the weight, and the type of a stored product, as well as thermal energy supplied to the vegetable storage facility.
Based on the heat balance equation, the nature of the operation of controlling elements, transfer functions of a vegetable storage facility without a product, and the vegetable storage facility filled with a product, were calculated. The heat model of a vegetable storage facility was constructed in the MATLAB Simulink environment (USA) to check the algorithms of the temperature field control.
The product storage for 180 days with changes in the daily temperature of outdoor air from minus 8 °C to plus 2 °C and changes in humidity from 50 % to 100 % was modeled.
According to the results of modeling, it is possible to conclude that the addition of an aperiodic link to the feedback of the two-position controller will enable taking into consideration the inertia of a control object. This allows decreasing the maximum error in control of self-oscillations to 0.15 °C and decreasing the total operation time of controlling elements by 13 %
Identification of patterns in the structural and phase composition of the doping alloy derived from metallurgical waste processing
Authors: Poliakov Anatolii , Dzyuba Anatolii , Volokh Vadym , Petryshchev Artem , Tsymbal Bohdan , Yamshinskij Mykhail , Lukianenko Ivan , Andreev Andrey , Bilko Tamara , Rebenko Victor 
Published: May 2021

This paper reports a study into the structural-phase composition of the doping alloy made by processing metallurgical anthropogenic waste involving reduction smelting. This is required for determining the technological parameters that ensure an increase in the level of extraction of target elements during the processing of anthropogenic waste and for the further use of the doping alloy. It was revealed that the phase composition of the doping alloy manifested a solid solution of the doping elements and carbon in α-Fe. Cementite Fe3C and silicides Fe5Si3, FeSi, and FeSi2 were also identified. In this case, the doping elements were more likely to act as substitution atoms. It has been determined that the microstructure of the alloy consisted of several phases of different shapes and contents of the basic doping elements. Sites with an elevated iron level of up to 95.87 % by weight in the composition could be represented by the solid solution phase of the doping elements and carbon in α-Fe. The sites with a relatively high (% by weight) content of carbon (0.83‒2.17) and doping elements ‒ W, up to 39.41; Mo, up to 26.17; V, to 31.42; Cr, to 9.15 ‒ were apparently of a carbide nature. The sites with a silicon content of 0.43‒0.76 % by weight likely included silicide compounds. The alloy's characteristics make it possible to smelt steel grades without strict carbon restrictions, replacing some of the standard ferroalloys. Neither phases nor compounds with a relatively high propensity for sublimation were identified in the material produced. Therefore, there is no need to provide conditions to prevent evaporation and loss in the gas phase of the doping elements. That could increase the degree of extraction of the doping elements
Determining the thermal mode of bio-based raw materials composting process in a rotary-type chamber
Authors: Golub Gennadii , Grabar Ivan , Derevyanko Dmytro , Нolubenko Anna , Medvedskyi Oleksandr , Chuba Viacheslav , Solarov Oleksandr , Bilko Tamara , Pavlenko Maksym , Saienko Anatolii 
Published: May 2021

One of the promising methods to dispose of agricultural bio-based raw materials is to produce compost by aerobic fermentation in rotary chambers. High efficiency of the composting process is achieved when a proper temperature mode is maintained at each phase of the process. Changes in temperature are directly related to the effective transformation of organic substrates by microorganisms and are the reason for the low quality of produced compost in terms of its agrochemical and microbiological parameters.
It was established that a high-temperature regime is achieved on the condition that the amount of heat released during the biodegradation of raw materials by microorganisms is greater than the heat loss associated with the substrate aeration and surface cooling. Therefore, the time during which the fermented mass remains warm depends entirely on the substrate's physical-chemical characteristics, the parameters of the equipment, and the modes of its operation.
To describe the established conditions, based on the equation of thermal balance, a mathematical model has been built. The model relates the thermal costs necessary to maintain the optimal temperature regime of the process to the substrate's moisture content and specific active heat generation, as well as to such an important thermal physical parameter of the chamber as the coefficient of heat transfer of the wall material.
A rotary chamber was manufactured to investigate the thermal mode of the bio-based raw materials composting process. It has been experimentally established that the chamber walls' heat transfer coefficient of 1.6 W/(m2·°C), a value of the substrate's specific active heat generation of 9.2 W/kg, and a moisture content of 58 % provide for the thermal needs for the process with the release of 140 MJ of excess heat.
The reported study could be the basis for the modernized methodology of thermal calculations of the bio-based raw materials composting process in closed fermentation chambers