bluuebunny/crossref_metadata_2025 huggingface dataset:
Inserção múltipla, intermitência e filiação cultural
Authors: Nunes Jordão Horta
Published: May 2021

O objetivo é analisar o trabalho de músicos brasileiros na França, afetado pelo regime de trabalhadores intermitentes de espetáculos e o trabalho por projetos. Procura-se identificar as formas identitárias relacionadas a trajetórias profissionais, caracterizar a organização de trabalho e as formas de contratação. A metodologia recorre a dados governamentais, à literatura sobre trabalho musical e a entrevistas, além de observação em ambientes laborais. O trabalho de brasileiros pode ser comparado ao de músicos em geral na França, caracterizando-se pela pluriatividade, múltipla inserção e polarização entre contratos por tempo indeterminado ou determinado e prestação de serviços eventuais. Entretanto, a “filiação cultural” a gêneros musicais característicos, associada às redes de cooperação pode ser compreendida como estratégia de construção identitária profissional em um mercado competitivo.
Study of the problem of ensuring security in the storage and processing of confidential data
Authors: Martishin Sergey Anatolyevich , Khrapchenko Marina Valeryevna , Shokurov Alexander Vladimirovich
Published: May 2021

We introduce an overview of modern approaches to cloud confidential data processing. A significant part of data warehouse and data processing systems is based on cloud services. Users and organizations consider such services as a service provider. This approach allows users to take benefit from all of these technologies: they do not need to purchase, install and maintain expensive equipment, they can access the data and the calculation results from any device. Such data processing on cloud services carries certain risks because one of the participants of the protocol for securing access to cloud data storage may be an adversary. This leads to the threat of confidential information leakage. The above approaches are intended for databases in which information is stored in the encrypted form and they allow to work in the familiar paradigm of SQL queries. Despite the advantages such approach has some limitations. It is necessary to choose an encryption method and to maintain a balance between the reliability of encryption and the set of requests required by users. In the case if users are not limited by the framework of SQL queries, we propose another way of implementation of cloud computing over confidential data using free software. It is based on lambda architecture combined with certain restrictions on allowed deductively safe database queries.
Developing Web Applications with Awareness of Data Quality Elements – DQAWA
Authors: Guerra-García César Arturo , Perez-Gonzalez Hector Gerardo , Ramírez-Torres Marco Tulio , Juárez Ramírez Reyes
Published: May 2021

An acceptable level of quality in data is nowadays a paramount for any kind of organization or enterprise that wishes its business processes to prosper. Thus, introducing activities focused in the data quality management is a crucial requirement for the analysts if the level of quality of data for the functionality or service at hand is to be ensured. Such specialized data quality management activities should be presented as early as possible during the software development process. So far and having done a search for proposals in this field, there is still a lack of either methodological or technological proposals with which a developer could be able to design data quality aware applications in the specific field of Web application development. Considering the benefits offered in the field of Model Driven Web Engineering, this work presents a partial outcome of our research in this novel field: a metamodel and a UML profile, both able to be used as data quality artefacts during the design stage of Web applications. The main objective is to provide the designer with the tools needed to design Web applications, in order to prevent data quality issues.
User Story Estimation based on the Complexity Decomposition using Bayesian Networks
Authors: Durán Mayra , Juárez-Ramírez Reyes , Jiménez Samantha , Tona Claudia
Published: May 2021

Currently, in Scrum, there are different methods to estimate user stories in terms of effort or complexity. Most of the existing techniques consider factors in a fine grain level; these techniques are not always accurate. Although Planning Poker is the most used method in Scrum to estimate user stories, it is primarily effective in experienced teams since the estimation mostly depends on the observation of experts, but it is difficult when is used by inexperienced teams. In this paper, we present a proposal for complexity decomposition in a coarse grain level, in order to consider important factors for complexity estimation. We use a Bayesian network to represent those factors and their relations. The edges of the network are weighted with the judge of professional practitioners about the importance of the factors. The nodes of the network represent the factors. During the user estimation phase, the Scrum team members introduce the values for each factor; in this way, the network generates a value for the complexity of a User story, which is transformed in a Planning Poker card number, which represents the story points. The purpose of this research is to provide to development teams without experience or without historical data, a method to estimate the complexity of user stories through a model focused on the human aspects of developers.
Vehicle Image Classifier for Bridge Displacement Correlation
Authors: Flores-Fuentes Wendy
Published: May 2021

Advanced computing brings opportunities for innovation in a broad gamma of applications. Traditional practices based on visual and manual methods tend to be replaced by cyber-physical systems to automate processes. The present work introduces an example of this, a machine vision system research based on deep learning to classify bridge load, to give support to an optical scanning system for structural health monitoring tasks. The optical scanning system monitors the health of structures, such as buildings, warehouses, water dams, etc. by the measurement of their coordinates to identify if a coordinate displacement befalls that could indicate an anomaly in the structure that can be related to structural damage. The use of this optical scanning system to monitor the structural health of bridges is a little more complicated due to the vehicle's transit over the bridge that causes a vehicle-bridge interaction which manifests as a bridge oscillation. Under this scheme, the bridge oscillation corresponds to their coordinate’s displacement due to the vehicle-bridge interaction, but not necessarily due to bridge damage. So, a bridge load classifier is required to correlate the bridge coordinates measurements behavior with the bridge oscillation due to vehicle-bridge interaction to discriminate the normal behavior of the structure to abnormal behavior or identify tendencies that could indicate bridge deformation or discover if the bridge behavior due to loads is changing through the time.
Conceptos y prácticas culturales de la medicina ancestral bribri y cabecar en Costa Rica
Authors: García Segura Alí , Jaén Rojas Alejandro
Published: May 2021

Este artículo reflexiona, en el contexto de la pandemia de COVID-19, sobre las prácticas sociales y culturales de la medicina tradicional de los pueblos originarios bribri y cabécares de Costa Rica para enfrentar las enfermedades contagiosas. Para lograr este objetivo, revisamos fuentes bibliográficas en antropología, lingüística e historia, pero sobre todo, volvimos a revisar las entrevistas que habíamos realizado durante muchos años a varios a médicos de los pueblos originarios, bribris y cabécares. Todo ello nos ha permitido descubrir que, muchas prácticas sociales y culturales, que prevalecen aún en estos dos pueblos originarios, esconden un complejo sistema de conceptos y protocolos médicos, que garantizan un saber hacer y un saber actuar ante enfermedades contagiosas. Conceptos como cuarentena, aislamiento, familiar o comunal, el tener cuidado de no tocar ciertos objetos, aparecen con total nitidez, en una concepción de mundo que privilegia la reflexión sobre la salud y la enfermedad.
Determination of dynamic loading of bearing structures of freight wagons with actual dimensions
Authors: Fomin Oleksij , Lovska Alyona
Published: May 2021

The determination of the dynamic loading of the bearing structures of the main types of freight wagons with the actual dimensions under the main operating conditions is carried out. The inertial coefficients of the bearing structures of the wagons are determined by constructing their spatial models in the SolidWorks software package. Two cases of loading of the bearing structures of the wagons – in the vertical and longitudinal planes – have been taken into account. The studies were carried out in a flat coordinate system. When modeling the vertical loading of the bearing structures of wagons, it was taken into account that they move in the empty state with butt unevenness of the elastic-viscous track. The bearing structures of the wagons are supported by bogies of models 18-100. The solution of differential equations of motion was carried out by the Runge-Kutta method in the MathCad software package. When determining the longitudinal loading of the bearing structures of wagons, the calculation was made for the case of a shunting collision of wagons or a "jerk" (tank wagon). The accelerations acting on the bearing structures of the wagons are determined.
The research results will help to determine the possibility of extending the operation of the bearing structures of freight wagons that have exhausted their standard service life.
It has been established that the indicators of the dynamics of the load-carrying structures of freight wagons with the actual dimensions of the structural elements are within the permissible limits. So, for a gondola wagon, the vertical acceleration of the bearing structure is 4.87 m/s2, for a covered wagon – 5.5 m/s2, for a flat wagon – 5.8 m/s2, for a tank wagon – 4.25 m/s2, for a hopper wagon – 4.5 m/s2. The longitudinal acceleration acting on the bearing structure of a gondola wagon is 38.25 m/s2, for a covered wagon – 38.6 m/s2, for a flat wagon – 38.9 m/s2, for a tank wagon – 27.4 m/s2, for a hopper wagon – 38.5 m/s2. This makes it possible to develop a conceptual framework for restoring the effective functioning of outdated freight wagons.
The conducted research will be useful developments for clarifying the existing methods for extending the service life of the bearing structures of freight wagons that have exhausted their standard resource
Development of cores acquisition model with two switching mechanisms in a retailer-oriented closed-loop supply chain system
Authors: Yuliawati Evi , Pratikto Pratikto , Sugiono Sugiono , Novareza Oyong
Published: May 2021

Retailer-Oriented Closed-Loop Supply Chain (ROCLSC) is an integration of forward and reverse supply chains with retailer taking charge of the remanufacturing, distribution, and collecting activities. This type of mechanism is quite effective, since the majority of product returns management is performed by the retailer. However, in practical industries, the implementation of ROCLSC is still limited. In this study, we investigate a ROCLSC system that involves an Original Equipment Manufacturer (OEM) and a retailer. OEM plays a role as a producer of new products, while the retailer is in charge of remanufacturing, collecting, as well as selling and distributing both newly manufactured and remanufactured products. We develop a mathematical model to maximize the profit of each party. Although several studies have developed models for cores acquisition, here we apply a different cores switching mechanism. We introduced the fixed rate and flat rate mechanisms used in the business-to-business (B2B) system, where product functions are very important to consumers. In addition, this research focuses on ROCLSC where most of the existing cores acquisition models are Manufacturer-Oriented Closed-Loop Supply Chain (MOCLSC). The result of this study shows that the retailer will get higher profits when the product returns are acquired through the fixed rate mechanism, rather than the flat rate mechanism. Therefore, determining the optimal amount of cores collected through the fixed rate mechanism will increase the retailer’s profit, as well as joint profit of both parties. From the results, we also point out an interesting note that the retailer should increase efforts to sell new products along with the increasing proportion of consumer Willingness to Pay (WTP) for remanufactured products. Hence, both OEM and retailer profits can be increased consecutively
An analysis of SmBa0.5Sr0.5Co2O5+δ double perovskite oxide for intermediate–temperature solid oxide fuel cells
Authors: Subardi Adi , Susanto Iwan , Kartikasari Ratna , Tugino Tugino , Kuntara Hasta , Wijaya Andy Erwin , Purnomo Muhamad Jalu , Indra Ade , Fahmi Hendriwan , Fu Yen-Pei
Published: May 2021

The main obstacle to solid oxide fuel cells (SOFCs) implementation is the high operating temperature in the range of 800–1,000 °C so that it has an impact on high costs. SOFCs work at high temperatures causing rapid breakdown between layers (anode, electrolyte, and cathode) because they have different thermal expansion. The study focused on reducing the operating temperature in the medium temperature range. SmBa0.5Sr0.5Co2O5+δ (SBSC) oxide was studied as a cathode material for IT-SOFCs based on Ce0.8Sm0.2O1.9 (SDC) electrolyte. The SBSC powder was prepared using the solid-state reaction method with repeated ball-milling and calcining. Alumina grinding balls are used because they have a high hardness to crush and smooth the powder of SOFC material. The specimens were then tested as cathode material for SOFC at intermediate temperature (600–800 °C) using X-ray powder diffraction (XRD), thermogravimetric analysis (TGA), electrochemical, and scanning electron microscopy (SEM) tests. The X-ray powder diffraction (XRD) pattern of SBSC powder can be indexed to a tetragonal space group (P4/mmm). The overall change in mass of the SBSC powder is 8 % at a temperature range of 125–800 °C. A sample of SBSC powder showed a high oxygen content (5+δ) that reached 5.92 and 5.41 at temperatures of 200 °C and 800 °C, respectively. High diffusion levels and increased surface activity of oxygen reduction reactions (ORRs) can be affected by high oxygen content (5+δ). The polarization resistance (Rp) of samples sintered at 1000 °C is 4.02 Ωcm2 at 600 °C, 1.04 Ωcm2 at 700 °C, and 0.42 Ωcm2 at 800 °C. The power density of the SBSC cathode is 336.1, 387.3, and 357.4 mW/cm2 at temperatures of 625 °C, 650 °C, and 675 °C, respectively. The SBSC demonstrates as a prospective cathode material for IT-SOFC
Obtaining glucose-based 5-hydroxymethylfurfural on large-pore zeolites
Authors: Patrylak Lyubov , Konovalov Serhii , Pertko Olexandra , Yakovenko Anzhela , Povazhnyi Volodymyr , Melnychuk Oleksandr
Published: May 2021

Obtaining such substances-platforms as, in particular, 5-hydroxymethylfurfural is one of the areas most actively investigated at present. They can act as raw materials for the further production of a new generation of biopolymers, fuels, pharmaceuticals, dietary supplements, and other chemicals. This paper reports the catalysts, synthesized by using methods of ion exchange and impregnation, based on the large-pore zeolites X, Y, and M, which contain the cations of rubidium, lanthanum, calcium, and ammonium. It was found that the zeolites' specific surface was 400‒500 m2/g; the selected synthesis conditions did not cause noticeable destruction of the microporous structure. In the presence of the synthesized catalysts, glucose dehydration in the aqueous medium and in dimethyl sulfoxide was carried out at 150–160 °C. The higher efficiency of polycationic forms of zeolites in a non-aqueous medium has been established. In the latter case, a 40 % yield of 5-hydroxymethylfurfural was achieved at an almost complete glucose conversion. Deactivated catalyst samples were investigated using the methods of infrared spectroscopy and differential thermal analysis/thermogravimetry. It was found that the catalyst accumulates fewer oligomerization process by-products when the reaction is implemented in dimethyl sulfoxide. The loss of mass by the samples deactivated in an aqueous medium is 30‒33 %, while in dimethyl sulfoxide – up to 24 %. The obtained results are important for practical application as the only volatile conversion product is 5-hydroxymethylfurfural with a yield of up to 40 %. That is acceptable for the possible implementation of a one-stage process of obtaining 5-hydroxymethylfurfural in the future
Defining patterns in the influence exerted by the interelated biochemical corrosion on concrete building structures under the conditions of a chemical enterprise
Authors: Shkromada Oksana , Ivchenko Viktoriia , Chivanov Vadym , Tsyhanenko Liudmyla , Tsyhanenko Hennadii , Moskalenko Volodymir , Kyrchata Іryna , Shersheniuk Olena , Litsman Yuliia
Published: May 2021

The effect of microbial and chemical corrosion on concrete structures operated in the conditions of chemical enterprises has been established that makes it possible to reliably predict the timing of their decommissioning in order to prevent industrial disasters. Even though the construction complies with all building codes, concrete structures eventually undergo chemical and biological corrosion.
The innovation proposed in this study implies investigating the depth and degree of damage to concrete at the microscopic level by the method of raster electron microscopy. In addition, the TPD-MS method has been suggested for determining the quantitative and qualitative state of the carbonate components of concrete and sulfur compounds.
This study has found that in concrete samples from the titanium dioxide production plant, the amount of carbon dioxide release is twice less than in control samples at t=600 °C while the level of sulfur dioxide, on the contrary, increases. This is due to the ability of thionic bacteria to accumulate sulfate acid that destroys the cementing component in concrete. The reported results confirm the impact of products of the activity of Acidithiobacillus thiooxidans microorganisms on corrosion processes in concrete.
In addition, when using the TPD-MS method, it was established in the storage room of the finished product that heating the control sample of concrete leads to a release of the significant amount of СО2 at t=580–600 °C. However, the experimental samples of concrete are almost lacking carbon compounds because the acid metabolites of microfungi interfere with its formation. Microscopic and REM studies revealed the localization of Acidithiobacillus thiooxidans and Aspergillus fumigatus in concrete.
This study has established patterns related to the mechanism that forms chemical compounds in concrete and the metabolism of microorganisms
Development of a simulation model of a photoplethysmographic signal under psychoemotional stress
Authors: Yavorska Evhenia , Strembitska Oksana , Strembitskyi Michael , Pankiv Iryna
Published: May 2021

A simulation model of a photoplethysmographic signal under psychoemotional stress taking into account the nature of signals of biological origin and stress response stages was developed. The method of constructing the simulation model is based on reconstructing the waveform and coding points of the signal taking into account the stress response curve using harmonic functions at characteristic time intervals. Using the simulation model of the photoplethysmographic signal under psychoemotional stress with previously known parameters allows validation of methods and algorithms for processing such data. It was found that in the process of simulation, it is necessary to take into account the signal frequency, random component and stress response curve. This complicates the simulation algorithm. However, using the simulation model with variable input parameters allows reproducing the signal with an emphasis on stress response stages. One of the features of the proposed model is the ability to reproduce the signal by coding points for amplitude and time intervals using harmonic functions. The relative error for the amplitude variation of the model and experimental data is 3.97 %, and for the period – 3.41 %. Calculation of Student's t-test showed a statistically insignificant difference: p=0.296 for the amplitude and p=0.275 for the period. This indicates that the simulation model takes into account the signal characteristics under stress: frequency, random component and stress response curve. Using the proposed simulation model is an adequate way to assess methods and algorithms for analyzing the state of the cardiovascular system under psychoemotional stress
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
Development of a model for choosing strategies for investing in information security
Authors: Lakhno Valeriy , Malyukov Volodimir , Akhmetov Berik , Kasatkin Dmytro , Plyska Liubov
Published: May 2021

This paper has proposed a model of the computational core for the decision support system (DSS) when investing in the projects of information security (IS) of the objects of informatization (OBI). Including those OBI that can be categorized as critically important. Unlike existing solutions, the proposed model deals with decision-making issues in the ongoing process of investing in the projects to ensure the OBI IS by a group of investors. The calculations were based on the bilinear differential quality games with several terminal surfaces. Finding a solution to these games is a big challenge. It is due to the fact that the Cauchy formula for bilinear systems with arbitrary strategies of players, including immeasurable functions, cannot be applied in such games. This gives grounds to continue research on finding solutions in the event of a conflict of multidimensional objects. The result was an analytical solution based on a new class of bilinear differential games. The solution describes the interaction of objects investing in OBI IS in multidimensional spaces. The modular software product "Cybersecurity Invest decision support system " (Ukraine) for the Windows platform is described. Applied aspects of visualization of the results of calculations obtained with the help of DSS have been also considered. The Plotly library for the Python algorithmic language was used to visualize the results. It has been shown that the model reported in this work can be transferred to other tasks related to the development of DSS in the process of investing in high-risk projects, such as information technology, cybersecurity, banking, etc.
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
Solving a task of coordinated control over a ship automated electric power system under a changing load
Authors: Budashko Vitalii , Shevchenko Valerii
Published: May 2021

This paper reports the synthesis of the main processes for the basic control over a complex technical vessel system. The issue related to the semantics of the description and the method for decomposing management tasks has been proposed to resolve in the context of the synthesis of the program to coordinate control over vessel technical systems and complexes with a sophisticated structure. An example of a five-unit ship’s automated electric power system (SAEPS) for the predefined level of generated power, taking into consideration the efficiency criteria, was used to synthesize the algorithms that execute transitions from one level to another while taking into account the pre-emergency and emergency states of SAEPS. The organization of the sequential process of enabling/disabling generator units (GUs) implies developing a program for managing the coordinator's supervisor as part of a distributed two-level hierarchical structure of SAEPS control when the load changes. The sequence of operations to launch, synchronize, transfer the loading, and stop GU is based on the formation of GU optimal composition, the distribution of loads among GUs running in parallel, and the implementation of the program for optimizing the primary engine of the power plant.
The reported principles for constructing GU composition control procedures based on the principle of "rigid and flexible" thresholds have made it possible to build a diagram of adjustment of the time delay in enabling GU dependent on the demanded power. It has been proven that the proposed technique improves the reliability of SAEPS operation as it eliminates possible emergency modes when false control combinations are assigned. Databases on the quantity of GUs, their technical condition, loading, fuel consumption, and environmental parameters have been built. The synthesis of control over a five-unit SAEPS has made it possible to determine the algorithmization procedure based on using an extended data array and simplify the functioning algorithm involved in the operations of choosing the structure for a five-unit SAEPS
Improved algorithm for matched-pairs selection of informative features in the problems of recognition of complex system states
Authors: Osypenko Volodymyr , Zlotenko Borys , Kulik Tetiana , Demishonkova Svitlana , Synyuk Oleh , Onofriichuk Volodymyr , Smutko Svitlana
Published: May 2021

The problem of computer diagnostics of complex systems is one of the non-trivial tasks of modern information technology. Such systems are, for example, computer networks, automatic and/or automated control systems for complex technological objects, including related to complex problems of environmental protection, biology, etc. In pattern recognition, one of the major problems is forming subspaces of informative features, which only in the «ensemble» allow diagnosing the states of such systems with a high degree of reliability.
An effective approach to solving this problem based on the principles of inductive modeling of complex systems is proposed. The quality criterion for recognizing classes of patterns is formulated, which also makes it possible to evaluate the quality of the constructed ensemble of informative features.
As an example, the problem of constructing an ensemble of informative features represented by a binary code based on the data of an experiment to determine the hazard levels of some plant protection products is considered. Real primary data on plant protection products used in practice were applied to recognize the effect of certain characteristics on the so-called integrated «hazard indicator».
Comparative numerical estimates of the effectiveness of the proposed approach are given. In this case, there can be a fivefold gain in the amount of computations for a relatively small number of input features equal to 5 compared to the known algorithms of the class considered in the paper. It is shown that, from a practical point of view, the described algorithm has advantages over the known algorithms with brute-force search of feature subspaces in pattern recognition problems.
Synthesis of the transfer function of the voltage controller in an active filter-stabilizer converter
Authors: Shcherbak Yakiv , Semenenko Yurii , Semenenko Olexandr , Karpenko Nadiia , Suprun Olexandr , Plakhtii Oleksandr , Nerubatskyi Volodymyr
Published: May 2021

It has been established that in order to ensure effective filtration and stabilization of the voltage of DC traction substations, it is advisable to use active filters-stabilizers. The dynamic characteristics of an active filter-stabilizer have been analyzed taking into consideration its discrete properties. It has been shown that the voltage converter in an active filter-stabilizer with bilateral pulse-width modulation for small values of control signal increment is an amplitude-pulse modulator of the second kind.
In order to improve the efficiency of using an active filter-stabilizer, which is part of the DC traction substation converter, the task was set to synthesize the transfer function of its converter's voltage controller. When analyzing a closed automatic control system, it was established that the transfer function of the voltage controller, which ensures the implementation of processes of finite duration in the closed automatic control system, includes a proportional part, an integral part, and a differential part. To determine the time constants for the transfer function of the PID-controller, as well as its damping coefficient, a closed automatic control system of the active filter-stabilizer voltage converter was investigated using an apparatus of Z-transformation. The result of synthesizing the transfer function of the voltage controller has established the parameters for the controller's transfer function, which ensure that the process of finite duration is executed in a closed system of automatic control over the converter's output voltage. The transition process in the system with a stepwise input effect of the processes of finite duration has been calculated, which confirmed that the transition process in the system ends after three clock intervals of discreteness. Establishing a transition process that ends over the finite number of discrete intervals, which is determined by the order of the characteristic equation, means that the process has been optimized for performance
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 %