EUREKA: Physics and Engineering <p><strong>EUREKA: Physics and Engineering </strong>scientific journal whose main aim is to publish materials allowed to see&nbsp;<strong><em>new discoveries at the intersection of sciences.</em></strong></p> en-US <p style="text-align: justify;">Our journal abides by the <a href="" target="_blank" rel="noopener">Creative Commons CC BY</a> copyright rights and permissions for open access journals.</p> <p style="text-align: justify;">Authors, who are published in this journal, agree to the following conditions:</p> <p style="text-align: justify;">1. The authors reserve the right to authorship of the work and pass the first publication right of this work to the journal under the terms of a <a href="" target="_blank" rel="noopener">Creative Commons CC BY</a>, which allows others to freely distribute the published research with the obligatory reference to the authors of the original work and the first publication of the work in this journal.</p> <p style="text-align: justify;">&nbsp;2. The authors have the right to conclude separate supplement agreements that relate to non-exclusive work distribution in the form in which it has been published by the journal (for example, to upload the work to the online storage of the journal or publish it as part of a monograph), provided that the reference to the first publication of the work in this journal is included.</p> (Helen Klimashevska) (Helen Klimashevska) Fri, 30 Sep 2022 16:18:16 +0300 OJS 60 Analysis of cosmological bias within spherical collapse model <p>The goal of our research work is to analyze cosmological bias parameter. Parametric equations of spherical collapse model are used to calculate the values of spherical collapse over density and mass variance, which is further used in bias formulae to find the values of cosmological bias. Spherical collapse over density has been calculated in the range of redshift 0 to 1. Also, it is compared with the value according to the spherical collapse model. Bias is one of the parameters which are utilized to infer cosmological parameters. Extracting the cosmological parameters is very much useful to know and understand about the birth and evolution of our universe. As there is no direct probe to get the idea about the existence of dark matter. Bias factor helps to analyze about dark matter. The bias coefficient of higher order terms in Taylor series expansion are found to be in ascending order. Increasing values of bias indicate the large-scale structure formation at current epoch is more and more clustered. Values of bias are discussed in result. Also, bias values have been analyzed for redshift in the range 2 to 0. The graph has been plotted bias versus redshift. Let’s found bias decreases with decrease of redshift. That means bias evolves with redshift. Bias value less than one and negative value of bias implies that structure formation is in linear region and higher values of bias indicates the structure formation occurs in nonlinear region. Negative value of bias is also called as antibias. That means the structure formation has not started yet. It is still in linear region. The bias value nearly equal to one indicates that the structure formation has been transformed from linear region to nonlinear region. So, the result showing bias values greater than one indicates that evolution of structure formation occurs in nonlinear region.</p> Sujata Mohanty, Rajesh Gopal Copyright (c) 2022 Sujata Mohanty, Rajesh Gopal Fri, 30 Sep 2022 15:35:23 +0300 Building a mathematical model to prevent hydrate formation in gas pipelines <p>Development of mathematical models of laminar gas flow in certainty and uncertainty conditions were considered. All factors that influence to character of flow of gas in pipeline and conditions of arising of hydrate inside of pipeline wall are analyzed. Results of analyze were used for development mathematical model of gas flow in pipeline that allow to calculate main parameters of hydrate deposition process. Model of gas flow consist of three non-linear differential equations that can be solved by exist soft wares. Two and three-dimension characteristic obtained, that describe of quantity of hydrate deposited at given process depending on time.</p> <p>Besides, the effectiveness of using DELPHI 7&nbsp;software to determine the preparation of gas for transportation and the hydrates formed during transportation and its prevention based on the results of the application software was discussed. As a result, the change in cross-sectional area of the pipeline of hydrates formed on the inner surface of the pipeline is shown in 3D. Hydrate formation and elimination are visually represented by graphs. The results of theoretical and practical studies of changes in the inner surface of the pipeline depending on temperature and pressure have been identified. All this was investigated during quasi-stationary gas flow in the pipelines and the results were obtained.</p> <p>The assumes regarding calculation of parameters of gas flow were determined and necessary recommendations for applying of developed model in different conditions with taking account of temperature and pressure variation and depending on time of hydrate deposition were presented. The diagram of gas-hydrate separation boundary considered for detailed analysis of process</p> Abdulaga Gurbanov, Ijabika Sardarova, Javida Damirova Copyright (c) 2022 Abdulaga Gurbanov, Ijabika Sardarova, Javida Damirova Fri, 30 Sep 2022 00:00:00 +0300 Characteristics and performance analysis of different grain sizes bamboo-activated carbons for motorcycle flue gas adsorption <p>The use of fossil fuels in human activities such as motorcycles has led to an increase in the concentration emitted in the atmosphere. Various efforts and methods such as adsorption using activated carbon have been developed and applied to reduce the emission. Therefore, this study focuses on the characteristics and performance of bamboo-activated carbons in the adsorption of motorcycle flue gases. This was carried out using different grain sizes (<em>z</em>) of activated carbons AC-M1, AC-M2, and AC-M3 for grain sizes of <em>z</em>≤250, 250&lt;<em>z</em>≤420, and 420&lt;<em>z</em>≤590 microns, respectively, which were derived from swat bamboo and carbonized at a temperature of 750&nbsp;<sup>○</sup>C. Furthermore, physical activation was applied by heating the charcoal at the same temperature under a nitrogen flow rate of 150 mL/min nitrogen. The Thermogravimetric (TGA), scanning electron microscopy (SEM), and adsorption isotherm tests were employed for the characterization of activated carbons. Additionally, the performances of activated carbons for motorcycle flue gas adsorption (CO<sub>2</sub>, CO, and HC) were carried out by a motorcycle emission test. According to the results, activated carbon AC-M1 produced the best characteristics and performance for adsorption of motorcycle flue gas, as it has a pore volume of 0.135&nbsp;cm<sup>3</sup>/g, a specific surface area of 244.69&nbsp;m<sup>2</sup>/g, and a nitrogen adsorption capacity of 87.047&nbsp;cm<sup>3</sup>/g. These characteristics prove to have good adsorption efficiencies at 100&nbsp;%, 87.30&nbsp;%, and 100&nbsp;% for adsorption of CO<sub>2</sub>, CO, and HC, respectively.</p> Dewa Ngakan Ketut Putra Negara, Tjokorda Gde Tirta Nindhia, Made Sucipta, I Made Widiyarta, I Putu Hariwangsa Copyright (c) 2022 Dewa Ngakan Ketut Putra Negara, Tjokorda Gde Tirta Nindhia, Made Sucipta, I Made Widiyarta, I Putu Hariwangsa Fri, 30 Sep 2022 14:32:35 +0300 Dynamic analysis as a method of wells interaction evaluation in making technological decisions <p>The complexity of developing oil fields determines the creation and improvement of fundamentally new approaches to the analysis and management of various technological processes of oil production based on indirect methods of interpreting current geological and field information for making strategic and tactical decisions to rationalize it.This article discusses the formation of stagnant and poorly drained zones of oil deposits due to the redistribution of hydrodynamic flows of reservoir fluids.</p> <p>In order to analyze and evaluate the effectiveness of applying the technology to change the direction of filtration flows in the reservoir under consideration, it is necessary to study the influence of non-stationary processes on oil production.</p> <p>Based on the construction of operational maps of total oil and water production, water cut and the degree of interaction by periods of development, the state of the reservoir system is analyzed and conclusions are made about the characteristic features of the direction of water-oil flows with the subsequent formation of stagnant zones.</p> <p>The proposed approach to decision-making allows to carry out the dynamic regulation of hydrodynamic flows in order to stabilize and reduce oil production losses for the period under consideration and make the necessary decision on the issuance of technological recommendations for the impact on the operation of the exploitation object, taking into account the minimization of energy and resource costs.</p> <p>The proposed method was tested on the example of the analysis of the state of development of one of the fields in Azerbaijan, which is in the final stage of development. As an information array, the dynamics of changes in oil and water flow rates by wells in various periods of development was chosen.</p> Samira Abbasova, Gulbahar Mamedova Copyright (c) 2022 Samira Abbasova, Gulbahar Mamedova Fri, 30 Sep 2022 15:12:00 +0300 Research and analysis of characteristics of fuel from organic and industrial waste <p>The article is devoted to the actual problem of utilisation of agricultural and industrial waste as a solution to the problem of replacing traditional energy sources.</p> <p>As an alternative fuel, researchers suggest using briquettes from biomass (leafy debris, waste paper, sunflower and buckwheat husks), as well as their combination with industrial waste (coal dust). The choice of these sources of raw materials is determined by their presence in the north-eastern part of Kazakhstan.</p> <p>Studies of the physical and mechanical and thermophysical characteristics of fuel briquettes from organic mass and bio-charcoal briquettes were carried out. The studies showed the following results: the moisture content of the samples we studied lies in the range from 3.86 to 8&nbsp;%; ash content of briquettes from vegetable raw materials varies from 2.05&nbsp;% to 3.6&nbsp;%, combined briquettes from foliage and coal dust varies from 10&nbsp;% to 14&nbsp;%; average density values varies from 979.91 to 1172.63&nbsp;kg/m<sup>3</sup>; mechanical strength is in the range from 90 to 100&nbsp;%; the yield of volatile studied samples ranges from 9 to 21.4&nbsp;%. Analysis of the obtained characteristics of fuel briquettes demonstrated that they meet the requirements of existing standards. Herewith, the lower calorific value of briquettes (15290‑19048 kJ/kg) is comparable to the calorific value of coal from the Ekibastuz deposit.</p> <p>The authors studied the influence of the parameters of the briquetting process on the briquette’s strength characteristics from leaves and waste paper, and obtained a regression dependence of these briquette’s calorific value on their characteristics. The analysis of regression dependencies showed that the pressure and pressing time have the greatest influence on the briquette strength, and its composition, i.e., the ratio of leaves and waste paper in the feedstock, has the greatest influence on the lower calorific value</p> Sholpan Nurkina, Akmaral Kinzhibekova, Evgeniy Prikhodko Copyright (c) 2022 Sholpan Nurkina, Akmaral Kinzhibekova, Evgeniy Prikhodko Fri, 30 Sep 2022 15:30:12 +0300 Experimental determination of the heat exchange coefficient of industrial steam pipelines <p>The article discusses and analyses the factors related to the use of a thermal imaging camera to determine heat loss in industrial steam pipelines at factories from chemical and metallurgical industry, by measuring their surface temperature. The generally accepted enthalpy method for determination of the loss has serious drawback it gives accurate results, but in averaged units in which it is impossible to take account of the contribution of the different parts and components of the pipeline in the total heat loss. The unavailability of information on where, how and in what way along the route this loss is formed does not allow prompt and specific measures to be taken for its reduction. An attempt has been made to structure empirically a reliable analytic dependence for determination of the heat exchange coefficient, bringing together the various factors influencing the heat exchange. By the method of the least squares the free coefficient and the exponent have been determined of criterion equation satisfying initial and boundary conditions of the experiment. Based on the obtained results for determining the heat losses by measuring the surface temperature of steam pipelines with a thermal imaging system, a reliable and acceptable method is proposed, which has a place in engineering practice. For this purpose, an industrial experiment has been carried out at three actually operating steam pipelines of different diameters and steam parameters. A criterion equation has been derived that can be used as a mathematical model for software products with a practical orientation for regular assessment of heat losses of steam pipelines. Values of heat losses determined through energy balance of heat carrier and heat flux from the outer surface of the steam pipelines have been compared. Results for the heat exchange coefficient, obtained through a balance have been compared with the analytically determined values based on current standards. A new method has been developed for express evaluations of the current heat losses of the steam pipeline in real time, as the sum of the losses through its individual components gives as average values 9÷12&nbsp;% increased results for the losses compared to the enthalpy method. Its great advantage is that it can be used selectively to determine the losses through individual sections of the steam pipeline.</p> Konstantin Kostov, Ivan Ivanov, Koycho Atanasov, Chavdar Nikolov, Stefan Kalchev Copyright (c) 2022 Konstantin Kostov, Ivan Ivanov, Koycho Atanasov, Chavdar Nikolov, Stefan Kalchev Fri, 30 Sep 2022 14:51:06 +0300 Simulation study of horizontal axis wind turbine using PVC pipe propeller with elbow tip <p>The potential of wind as an energy resource is still not widely used by the community through simple technology to produce electrical power. One simple technology is to use PVC pipe as the basic material for making wind turbine propellers. The purpose of this study was to determine the effect of variations in angle of attack and wind speed on the performance of a PVC pipe propeller wind turbine with an Elbow Tip. Material of blade propeller made by PVC pipe are slice half and twist from hub until tip with 90 degree of rotation. Dimension of width blade wider on the hub (3/4 of circular) and smaller on the tip (1/7 of circular). Face of blade on the hub side facing wind direction (axial) and face of blade on the tip side facing tangential direction or opposite with rotation. On the tip side installed the slice elbow with fit tip blade width. The propeller using PVC pipe with elbow tip is the important part of new design which has been test with CFD simulation and wind tunnel research with best result performance. This research uses CFD simulation and experimental methods with a comprehensive study of the aerodynamic behaviour characteristics in and around the turbine rotor. The results of the CFD simulation was found that the phenomenon positioning of momentum force were place on the outer radius due to addition elbow tip cause increasing the torque. By using elbow tip on blade propeller PVC Pipe Horizontal Axis Wind Turbine with 15° and 30° angle of attack could increasing torque about 200&nbsp;% than without the elbow tip. Beside, using 45° angle of attack although additional with elbow tip could not increasing the torque when the wind speed on 7&nbsp;m/s. The result of this research is important to know by public who interest build small grid wind turbine with low cost and easy manufacturing.</p> Bagus Wahyudi, Akhmad Faizin, Andri Setiawan, Sugeng Hadi Susilo, Hangga Wicaksono Copyright (c) 2022 Bagus Wahyudi, Akhmad Faizin, Andri Setiawan, Sugeng Hadi Susilo, Hangga Wicaksono Fri, 30 Sep 2022 14:15:45 +0300 Development of the methodological approaches for the attitude control system of the Earth remote sensing satellite in the conditions of the onboard equipment partial failures <p>The spacecraft controllability of the angular motion is possible only with operability of the attitude and orbit control system (AOCS) of the spacecraft, sensors, actuators and the spacecraft power system. However, there is a rather significant probability of failure of this equipment during the operation of the spacecraft. This is especially observed after half of the spacecraft's lifetime or because of emergency situations. There is a problem which is connected with providing the maximum performance of the AOCS in case of partial failures of their actuators (reaction wheels (RW), magnetorquer rods (MGTR), etc.).</p> <p>Thus, the purpose of this work is the development and synthesis of special algorithms for spacecraft angular motion control in the emergency situations which are connected with RWs partial failures and restrictions of onboard electricity consumption. The approach of synthesis of this control algorithms is based on using mobile control methods which allow to reserve RWs by MGTRs. There are different variants of control loops depending on MGTRs turning on combinations. There were proposed two types of control switching functions: time-periodic and switching by deviation. Also was proposed a methodology of controller synthesis using these switching functions.</p> <p>Using this methodology and computer simulation, it was shown the possibility of providing angular nadir orientation and stabilization of the spacecraft with maximum 1−1.5 deg error in case of time-periodic switching functions implementation. Switching by deviation allows to reduce onboard electricity consumption for 25−30&nbsp;% comparing with using time-periodic switching. However, the accuracy of stabilization significantly lower in case of switching by deviation. Considering these estimates, the corresponding methodological recommendations were formulated for use switching functions depending on emergency</p> Petro Zheliabov, Erik Lapkhanov Copyright (c) 2022 Petro Zheliabov, Erik Lapkhanov Fri, 30 Sep 2022 00:00:00 +0300 Research and modeling of oil refining technological processes operating in the condition of stochastic uncertainty <p>As it is known, one of the initial and important stages in the creation of optimal control systems of oil refining technological units is the development of a mathematical model that can adequately record the processes at any time.</p> <p>The operative and accurate measurement of all input and output variables is one of the important conditions in the development of a mathematical model of technological processes.</p> <p>Studies have shown that the lack of information about the state of complex oil refining processes in many cases reduces their efficiency and effectiveness. On the other hand, the wide range of both quality and quantity of raw materials for processing makes their efficiency even more unsatisfactory. Under these conditions, it is difficult to develop mathematical models that can adequately describes the static modes of technological processes; the development of mathematical models is relevant both in scientific and practical terms.</p> <p>A priori information required on input and output variables during normal operation of the technological complex in order to implement mathematical models identification for the vacuum block of the oil refining process unit is provided in the article. On the basis of this static information, mathematical dependencies were constructed between the variables characterizing the static mode of technological processes and the adequacy of the obtained mathematical models was confirmed through the statistical apparatus</p> <p>In order to solve the problems, the research was determined to be able adequately describe the current technological conditions, which can quickly adapt to current technological situations and ensure the production of oil fractions with relatively stable quality, regardless of the disturbing effects of the system</p> Aygun Safarova, Javida Damirova Copyright (c) 2022 Aygun Safarova, Javida Damirova Fri, 30 Sep 2022 14:11:28 +0300 The development a fully-balanced current-tunable first-order low-pass filter with Caprio technique <p>This paper presents the development and design of a fully-balanced current-tunable first-order low-pass filter with Caprio technique, which could include the design and implementation of a first-order low-pass filter circuits. The filter consists of six bipolar junction transistor (BJT) and a single capacitor. The filter construction uses a bipolar junction transistor (BJT) as the main device and a single capacitor. A fully-balanced current-tunable first-order low-pass filter with Caprio technique developed. The architecture of the circuit is quite simple and proportional, symmetrical with signs of difference. Circuits developed into integrated circuits act like basic circuits for frequency filter circuits, current modes with Caprio techniques, obtained by improving the first-order low-pass filter for signal differences with incoming impedances. Adjusting the parameters of the circuit with the caprio technique achieves the optimal parameter value for correcting the total harmonic distortion value.</p> <p>The results of testing the operation of the circuit, a fully-balanced current-tunable first-order low-pass filter with Caprio technique developed and designed using the PSpice program. The simulation results showed good results in line with predicted theoretical analysis. The sensitivity of the device to the center frequency (ω<sub>0</sub>) response is low and independent of variables, the angular frequency is linear with wide current adjustment throughout the sweeping range of a wide frequency range, with a wide range of over tree orders of magnitude. Therefore, fully-balanced current-tunable first-order low-pass filter developed is very suitable to apply various applications regarding low frequency signal filtration, for example in biomedical systems, for example.</p> Samran Lertkonsarn, Worawat Sa-ngiamvibool Copyright (c) 2022 Samran Lertkonsarn, Worawat Sa-ngiamvibool Fri, 30 Sep 2022 15:18:50 +0300 Analysis of the main design and operating parameters of the device for the fermentation of bird droppings <p>The study on the utilization of poultry droppings put forward the need for the constructive and technological improvement of the biofermentation device. A drum-type bioreactor better meets the requirements for the technological process of eco-friendly biologically active fertilizer production from livestock and poultry wastes. However, the great size of the heat transfer surface of the bioreactor drum and its significant ejection momentum during spinning require quite a lot of energy. To decrease this consumption, the main constructive parameters should be optimized. The main reason is the sharp increase in prices for mineral fertilizers, the weak economic condition of most farms, the lack of advanced processing technologies and the use of organic fertilizers.</p> <p>Our aim in these studies was to analyze the types of design and operating parameters of the device for the fermentation of bird droppings. To this end, we conducted a study on the disposal of bird droppings, and also put forward the need for constructive and technological improvement of the biofermentation device. One of such ways to solve the problem was a drum-type bioreactor, which, according to our research indicators, better meets the requirements for the technological process of producing environmentally friendly biologically active fertilizers from animal husbandry and poultry waste, however, the size of this equipment of the heat transfer surface of the bioreactor drum and its significant emission pulse during rotation require a rather large waste of energy. To reduce this consumption, it is necessary to optimize the basic design parameters.</p> <p>Devices that work continuously were recognized as the most promising. They fully meet the technological and operational requirements</p> Rovshan Hajiyev, Rasim Saidov, Gabil Mammadov, Urfan Taghiyev, Gahira Allahverdiyeva Copyright (c) 2022 Rovshan Hajiyev, Rasim Saidov, Gabil Mammadov, Urfan Taghiyev, Gahira Allahverdiyeva Fri, 30 Sep 2022 15:44:38 +0300 A study on multi-criteria decision-making in powder mixed electric discharge machining cylindrical shaped parts <p>In life as well as in engineering, many times, it is necessary to choose the best option among many different options. That will be more difficult when the criteria given for the selection contradict each other. For example, when external cylindrical grinding, the minimum surface roughness requirement necessitates a small depth of cut and feed rate. The material removal rate will be reduced in this case, and this requirement will conflict with the maximum material removal rate requirement. To solve the above problem, a very useful tool is multi-criteria decision-making (MCDM). In this paper, for the first time, MCDM results for powder mixed discharge machining (PMEDM) cylindrical parts of SKD11 tool steel with copper electrodes have been presented. In this work, eighteen experiments with the L18 (1<sup>6</sup>×5<sup>3</sup>) design using the Taguchi method were conducted. Six main input process parameters include the powder concentration, the pulse current, the servo voltage, the pulse on time, and the pulse off time. To select an alternative that simultaneously ensures two criteria including minimum surface roughness (RS) and maximum material removal speed (MRS), four different MCDM methods including MAIRCA (Multi-Attributive Ideal-Real Comparative Analysis), MARCOS (Measurement of Alternatives and Ranking according to Compromise Solution), TOPSIS (Technique for order of preference by similarity to ideal solution), and EAMR (Area-based Method of Ranking) and two methods of criteria weight calculation including MEREC (Method based on the Removal Effects of Criteria) and Entropy methods were selected. The results of MCDM when PMEDM SKD11 tool steel cylindrical parts with two methods for weight determination and four methods for solving MCDM problem were evaluated. In addition, the best alternative to ensure simultaneous minimum RS and maximum MRS was proposed.</p> Tran Huu Danh, Trieu Quy Huy, Pham Duc Lam, Nguyen Manh Cuong, Hoang Xuan Tu, Vu Ngoc Pi Copyright (c) 2022 Tran Huu Danh, Trieu Quy Huy, Pham Duc Lam, Nguyen Manh Cuong, Hoang Xuan Tu, Vu Ngoc Pi Fri, 30 Sep 2022 15:48:08 +0300 Study of interference fit between steel and brass parts <p>Interference fits are generally used in mechanical systems because they have low-cost production and their assembly parts are much smaller than other mechanical joints. Also, their geometric shapes and material properties allow technicians to actively determine how strong the fits are. In this study, let’s present research on interference fits between steel and brass assembly parts. The experimental processes were accomplished with five pairs of specimens to evaluate the behaviours of surface asperities under a high loading condition. Specifically, the specimen pair includes a C45 steel shaft and a C2680 brass hub, which have different surface roughness values (Ra). Let’s apply high-precision methods in measuring all dimensional parameters and employed axial load tests for distinctively inspecting the steel-brass interference fit performance. In every experiment, the measured responses are:</p> <p>1)&nbsp;the surface roughness values (Ra) before and after loading cycles;</p> <p>2) the axial load (<em>F<sub>a</sub></em>);</p> <p>3) the relative displacement value or the real-time interface length in loading stages (<em>l</em>).</p> <p>The aim of this study is to propose a new relative interference value specifically between steel and brass assembly parts, which can help determine the interference loss value more accurately. It was not concluded that with the relative interference of 2.25&nbsp;‰ the load capability of steel-brass interference fits is extended. Besides, let’s narrow down the predictive loss coefficient (<em>a</em>) for steel-brass interference assemblies ranging from 1.1 to 2.1, which varies from widely used standards considering <em>a</em>=3. This result helps minimize inaccuracies in interference fit designs, calculations, and work capabilities.</p> Nguyen Huu Loc, Lam Vi Phong Copyright (c) 2022 Nguyen Huu Loc, Lam Vi Phong Fri, 30 Sep 2022 14:55:40 +0300 Enterprise risk arising from legacy production systems: a probabilistic perspective <p>The model of estimation of effective minimization of strategic risks arising at modernization of the software of legacy production systems is presented. It is shown that incompatible hypotheses of strategic risks of the enterprise in the digital economy form a complete group of pairwise incompatible independent events, and their probabilities are found by mathematical methods of processing an inversely symmetric matrix, made by experts in pairwise comparison on a 5-point scale of relative importance errors of calculations of the constructed matrix (no more than 15&nbsp;%). For these matrices, solutions of characteristic equations are found to determine the maximum values of the eigenvalues of matrices, which appear in the assessment of the adequacy of composite expert matrices together with the corresponding orders of matrices.</p> <p>To substantiate the statistical measurement under the condition of quantitative or qualitative assessment of the risk of occurrence of events, the a priori value of the probabilities of occurrence of risk in the occurrence of events is taken. The full probability formula is the formula for the probability of occurrence of an event of effective minimization of strategic risks. It is shown that to determine the a priori values of conditional probabilities of hypotheses of effective minimization of strategic risks of the enterprise it is necessary to make statistically significant sections of these hypotheses at selected enterprises for several periods, which may be subject to statistical distribution laws. Thus, the presented model for quantitative measurement, comprehensive analysis of the level of software modernization of legacy production systems of the enterprise is the initial theoretical basis for improving the system of strategic management of the enterprise in terms of digitalization.</p> Tetiana Bludova, Svitlana Usherenko, Alla Moskovchuk, Iryna Kaminska, Olga Kyslytsyna Copyright (c) 2022 Tetiana Bludova, Svitlana Usherenko, Alla Moskovchuk, Iryna Kaminska, Olga Kyslytsyna Fri, 30 Sep 2022 15:40:08 +0300 Investigation of the protective capabilities of glass from laser sounding depending on its elemental composition <p>One of the most vulnerable issues in the technical protection of information is to obtain data via leakage through the opto-electronic channel.</p> <p>In this paper, studies of the protective capabilities of glass from laser sounding depending on its elemental composition were carried out using such indicators as the coefficients of reflection and absorption of the laser beam by the window glass.</p> <p>As a result of the work, an experimental installation based on a continuous solid-state laser was assembled.</p> <p>The study of the elemental composition of window glass, which is produced by modern industry, X-ray fluorescence method and the study of the coefficients of reflection and absorption of glass samples in the experimental setup showed that the studied window glass chemically belongs to quartz (silicate).</p> <p>All chemical elements involved in its formation can be divided into 3 groups: glass-forming, transitional, modifiers, which affects the optical properties of the studied glasses, as the elements used have different not only qualitative but also quantitative parameters.</p> <p>Absorption increases if the number of chemical elements that exhibit amphoteric and non-metallic properties and have (-charge) decreases, and increases if the number of chemical elements in the glass that exhibit the most alkaline, alkaline earth properties and in which the radius of cations (+ions) increases.</p> <p>Systematization of the elemental and quantitative composition of the studied window glass in accordance with the periods and groups of the periodic table of chemical elements, enabled the relationship between the electronic structure of chemical elements and the protective properties of glass</p> Nazarii Dzianyi, Valeriy Dudykevych, Ivan Opirskyy, Larysa Rakobovchuk, Petro Haraniuk Copyright (c) 2022 Nazarii Dzianyi, Valeriy Dudykevych, Ivan Opirskyy, Larysa Rakobovchuk, Petro Haraniuk Fri, 30 Sep 2022 14:37:58 +0300 Analysis of frequency dependence of complex impedance and electrical characterization of Fe2O3/kaolin ceramics for civil engineering applications <p>The complex impedance spectroscopy (CIS) method is usually used in order to analyze the electrical response of different semiconducting disordered materials as a function of frequency at different temperatures. The real and imaginary parts of the complex impedance can show different semicircles in the complex plane that give evidence for the presence of both bulk and grain boundary contributions. Many parameters can be deduced from the analysis of CIS data, such as relaxation times and activation energies. There are some literature data concerning electrical properties of clays and (semiconductor, sand, cement,…)/clay mixtures. Most of the published works are related to the AC conductivity of rocks with the effect of water or oil content but there are no similar studies on the characterization of the microstructure of individual clays as ceramic materials by analyzing their temperature and frequency dependence of their electrical conductivities. Hence, this paper presents an analysis of electric complex impedance of the Fe<sub>2</sub>O<sub>3</sub>/Kaolin composite in the high temperature range up to 740&nbsp;°C. Sinusoidal voltage with frequency in the range [100&nbsp;Hz, 1&nbsp;MHz] is applied to the material in order to measure the electrical conductivity for various concentrations of Fe<sub>2</sub>O<sub>3</sub> from zero to 100&nbsp;%. The activation energies for the conduction and for the relaxation processes are determined and their dependence on the density of Fe<sub>2</sub>O<sub>3</sub> analyzed. Furthermore, let’s found that Fe<sub>2</sub>O<sub>3</sub> have the effect to increase the electrical conductivity in our samples. From the Nyquist diagrams, only one semi-circle related to the contribution of the grains to the total electrical conduction is identified for all investigated samples.</p> Abdeltif Bouchehma, Mohamed Essaleh, Rachid Bouferra, Soufiane Belhouideg, Mohamed Benjelloun, Imad Sfa Copyright (c) 2022 Abdeltif Bouchehma, Mohamed Essaleh, Rachid Bouferra, Soufiane Belhouideg, Mohamed Benjelloun, Imad Sfa Fri, 30 Sep 2022 00:00:00 +0300 Principal component analysis as tool for data reduction with an application <p>The recent trends in collecting huge datasets have posed a great challenge that is brought by the high dimensionality and aggravated by the presence of irrelevant dimensions. Machine learning models for regression is recognized as a convenient way of improving the estimation for empirical models. Popular machine learning models is support vector regression (SVR). However, the usage of principal component analysis (PCA) as a variable reduction method along with SVR is suggested. The principal component analysis helps in building a predictive model that is simple as it contains the smallest number of variables and efficient. In this paper, we investigate the competence of SVR with PCA to explore its performance for a more accurate estimation. Simulation study and Renal Failure (RF) data of SVR optimized by four different kernel functions; linear, polynomial, radial basis, and sigmoid functions using <em>R</em> software, version (R x64 3.2.5) to compare the behavior of ε SVR and <em>v</em>-SVR models for different sample sizes ranges from small, moderate to large such as; 50,&nbsp;100, and 150. The performance criteria are root mean squared error (RMSE) and coefficient of determination <em>R</em><sup>2</sup> showed the superiority of ε-SVR over v- SVR. Furthermore, the implementation of SVR after employing PCA improves the results. Also, the simulation results showed that the best performing kernel function is the linear kernel. For real data the results showed that the best kernels are linear and radial basis function. It is also clear that, with ε-SVR and <em>v</em>-SVR, the RMSE values for almost kernel functions decreased with increasing sample size. Therefore, the performance of ε-SVR improved after applying PCA. In addition sample size <em>n</em>=50 gave good results for linear and radial kernel</p> Shereen Hamdy Abdel Latif, Asraa Sadoon Alwan, Amany Mousa Mohamed Copyright (c) 2022 Shereen Hamdy Abdel Latif, Asraa Sadoon Alwan, Amany Mousa Mohamed Fri, 30 Sep 2022 00:00:00 +0300