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> Scientific Route OÜ en-US EUREKA: Physics and Engineering 2461-4254 <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> Study of sediment deposition processes and assessment of the change in the W-H characteristics of the madaghis reservoir <p>The accumulation of sediments in reservoir is always a problem. Over time, these accumulations occupy the volume meant for water management, dramatically reducing the reservoir's effectiveness. The environment of the river basin below the reservoir undergoes significant changes. In this regard, assessing changes in volumetric W-H characteristics, particularly in reservoirs built on high turbidity rivers, is critical. The Mataghis Reservoir on Tartar River was chosen as the object of study. The quantity of accumulated sediments was established by original measurements and was calculated in three hydrologic ways at distinct stages of operation. The actual graphs showing the reservoir's W-H volumetric characteristics were made two decades after commissioning and are still in use. According to the findings, over 70 per cent of the reservoir volume has been filled with sediments over the course of the reservoir's thirty-year operation. A theoretical model of the sediment buildup process in basins has been created. Separate parameters have been created for the deposition of bottom sediments entering the reservoir and suspended particles in the flow. Based on them, the patterns of distribution of accumulated sediments according to the length and height of the reservoir were drawn out. The vertical pulsation velocity and the results of studies for determining the minimum rate of soil particle flow were used. To solve sedimentation problems in operating and newly constructed reservoirs, a methodology for evaluating changes in the amount of collected water and changes in the volume of water control, as well as a theoretical method for projecting their future behavior, can be applied</p> Pargev Baljyan Arestak Sarukhanyan Eleonora Avanesyan Copyright (c) 2023 Pargev Baljyan, Arestak Sarukhanyan, Eleonora Avanesyan 2023-01-19 2023-01-19 1 3 12 10.21303/2461-4262.2023.002757 The development of carbon monoxide oxidation reactor for multi-chamber furnaces for baking electrode blanks <p>The article highlights the development of cheap affordable highly efficient catalytic oxidation system of harmful components of industrial flue gases of carbon graphite enterprises, its design features according to the parameters of furnace equipment, which will significantly improve the environmental safety of metallurgical and machine-building enterprises. The presented calculation and design solutions, in addition to carbon production, can be used in environmental protection technologies at other environmentally hazardous facilities to neutralize toxic emissions.</p> <p>The paper presents the calculation of the catalytic CO oxidation reactor made for the real flow rate of flue gases with temperature range 270−390&nbsp;ºC, which come out of the combustion chamber of the Riedhammer "first fire" kiln, heated by the flue gases. For such medium exothermic processes, mass and heat transfer between gas flow and the outer surface of the catalyst grains is sufficient intense. In this case for description of the catalytic process in the reactor is sufficient to use quasi-homogeneous single-phase model.</p> <p>The model of plug-flow reactor with a fixed bed of catalyst was used to calculate the flow parameters of the gas mixture through a reactor loaded with a composite zeolite-based manganese-oxide catalyst in the process of catalytic CO oxidation. The calculation results obtained using the software CHEMCAD&nbsp;7.1.5 were almost identical to the previously made calculation. The peculiarity of the suggested solution was the use of the designed catalytic reactor for treatment of large volume of flue gases with low concentrations of CO at the companies of electrode carbon graphite production</p> Olena Ivanenko Andrii Trypolskyi Оleksandr Khokhotva Igor Mikulionok Anton Karvatskii Vyacheslav Radovenchyk Sergii Plashykhin Tanya Overchenko Serhii Dovholap Peter Strizhak Copyright (c) 2023 Olena Ivanenko, Andrii Trypolskyi, Оleksandr Khokhotva, Igor Mikulionok, Anton Karvatskii, Vyacheslav Radovenchyk, Sergii Plashykhin, Tanya Overchenko, Serhii Dovholap, Peter Strizhak 2023-01-19 2023-01-19 1 13 23 10.21303/2461-4262.2023.002747 Research of the technology for hydrate prevention in gas transportation system <p>The principal aim of natural and associated gas preparation to transportation is provision of normal transportation inside field niacin gas pipelines. Developed gas and gas condensate field, production of which consists of great amount of different aggressive admixtures and mineral salts, require efficient of natural gas for further transportation.</p> <p>The results of aforesaid system phase state test investigation are given in the article. Its presently at water phase and salt composition.</p> <p>A Principals physical and chemical factors of inhibitor composition under different proportion of components were determined under laboratory conditions. New inhibitor composition, was selected on the base of experimental investigation results there also was developed the technology of inhibitor application for gas field treatment.</p> <p>Since the efficiency of gas storage and transportation processes depends on the compliance of these processes with the requirements of the related equipment and relevant technologies, the operating modes of gas lift lines and compressor stations should be regularly examined. There is no doubt that the efficiency of storage and transportation of natural and associated gas is ensured at a distributed level, provided that the technological equipment is reliable, durable and operates in accordance with the requirements. One of the most important issues is to improve the used technology to prevent hydrate formation in the process of production, storage and transportation of gas condensate in complex conditions. On the basis of scientific a research and field surveys there were developed new scientific a technical measure to increase the efficiency of the installation for preparation of gas</p> Abdulaga Gurbanov Ijabika Sardarova Javida Damirova Copyright (c) 2023 Abdulaga Gurbanov, Ijabika Sardarova, Javida Damirova 2023-01-19 2023-01-19 1 24 31 10.21303/2461-4262.2023.002746 Experimental investigation of water to air heat exchanger performance as passive cooling strategy on ventilation system in tropical region <p>This experimental study aims to investigate and analyze the performance of a Water-Air Heat Exchanger that functions as passive cooling in a building ventilation system in the tropics. Before being blown into the room, the high-temperature outdoor air will be passively cooled by the lower-temperature water. Air driven by an Inline Duct Fan with a constant mass flow rate of 4.68&nbsp;cubic meters per minute flows through a PVC hose as a heat exchanger inserted into a full water reservoir with a diameter of 100&nbsp;cm and a height of 110&nbsp;cm. A heat exchanger hose with a diameter of 6.35&nbsp;cm and a length of 4130&nbsp;cm is installed in a spiral-circular manner with a total of 16&nbsp;coils with a diameter of 80&nbsp;cm to increase the heat transfer effectiveness between water and air. The passive cooling effectiveness is analyzed by decreasing the air temperature between the inlet and outlet of the ventilator after passing through the heat exchanger. The temperature, humidity, and daylight measurement data were carried out for 36&nbsp;consecutive hours using a multichannel data logger at several locations; ventilator inlet, ventilator outlet, water in the tub, and outside air. The measurement results show that the designed water-to-air heat exchanger provides a significant passive cooling effect and can reduce air temperature to 6.88&nbsp;°C. By utilizing the passive cooling effect, the cooling energy gain obtained during the measurement period in the ventilation system of this building is 8.3&nbsp;kWh. The methodology and results of this research are expected to make a positive contribution to the development of the concept of energy-efficient buildings by using passive cooling techniques</p> Remon Lapisa Andre Kurniawan Jasman Jasman Dori Yuvenda Randi Purnama Putra Waskito Waskito Arwizet Karudin Krismadinata Krismadinata Copyright (c) 2023 Remon Lapisa, Andre Kurniawan, Jasman Jasman, Dori Yuvenda, Randi Purnama Putra, Waskito Waskito, Arwizet Karudin, Krismadinata Krismadinata 2023-01-19 2023-01-19 1 32 41 10.21303/2461-4262.2023.002591 Development of a hardware emulator of a nanosatellite gyroscope <p>The gyroscope sensor has multiple applications in consumer electronics, aircraft navigation, and control systems. Significant errors that match the corresponding data are a typical disadvantage of this sensor. This needs to be done by making error models that can be used to get the right level of measurement accuracy. For high-precision space applications, the navigation design system should take into account the angle random walk (N), bias instability error (B), and rate random walk (K) of the BMG160 gyroscope. For this reason, this paper shows how to use Allan Variance (AVAR) and Power Spectral Density (PSD) for the experimental identification and modeling of the stochastic parameters of the Bosch BMG160 gyroscope embedded in a nanosatellite in order to get an accurate gyroscope model. This work also demonstrates the principle of operation of the equivalent electronic model intended to carry out advanced simulations without recourse to the real material in order to avoid the problem of bad manipulation and availability of the material in order to reduce the time and cost of development. The interpretation of the Allan curves and the PSD obtained from the measurements collected over a long period is presented, as well as a comparison between the real raw data of the BMG160 gyroscope and the designed hardware emulator in both the time and frequency domains. This is done to evaluate the accuracy of the gyroscope model emulating the real sensor in laboratory simulations. The experimental results show that the signals from the emulator and the BMG160 gyroscope are quite close. Therefore, the proposed prototype could be an optimal solution for laboratory calculations and simulations</p> Aziz El Fatimi Adnane Addaim Zouhair Guennoun Copyright (c) 2023 Aziz El Fatimi, Adnane Addaim, Zouhair Guennoun 2023-01-19 2023-01-19 1 42 53 10.21303/2461-4262.2023.002528 Developing a prototype centre using agricultural smart sensors to promote agrarian production with technology <p>This article presents the development of a model center using agricultural intelligent center technology. The goal of this research is 1.&nbsp;To develop a wireless sensor network. 2.&nbsp;To be a source of learning on the use of sensor technology in agriculture. For local and nearby farmers Using the Sufficiency Economy Learning Center, according to King's Science. The Rajamangala University of Technology Suvarnabhumi is a research area. With the problems faced in farming today. It found that the world's climate change whether it's drought. Rains leave ranges and toxic airborne particulate matter caused by farming to match current problem conditions. The researchers then designed a two-part system: 1.&nbsp;Node Moisture Sensor that measures soil moisture and commands the opening – It also controls on-off with a manual switch. Wind speed and wind direction sensors, light intensity sensors, temperature, and humidity sensors, and Particulate Matters Sensor 1.0,&nbsp;2.5,&nbsp;10 with environmental reports within the growing area via Wi-F signals to (Sever) Raspberry Pi record real-time data. Every 30&nbsp;seconds According to research, node moisture sensors can measure soil moisture and record results, and the station measures the environment within the growing area via a Wi-F signal to (Sever) Raspberry Pi. Rainfall values measured by local rainfall sensors measuring up to 35.3&nbsp;mm are within the threshold of heavy rain. The maximum wind speed measured is 8.5&nbsp;km/h, the maximum temperature of 35.8&nbsp;degrees Celsius, and the maximum humidity of 99.9&nbsp;percent, the light intensity is up to 58,002&nbsp;Lux, and the Final Particles, with pm 1.0 up to 40.1&nbsp;microns, PM&nbsp;2.5 up to 51.3&nbsp;microns and PM&nbsp;10 up to 63.5&nbsp;microns. Apply agriculture to 50&nbsp;interested farmers after receiving knowledge transfer of smart sensor technology. The expansion has resulted in 3&nbsp;farmers and will continue to expand in the future. Promote the use of agricultural technology. Intensifying communities and supporting global climate change</p> Wichai Nramat Wasakorn Traiphat Phuachat Sukruan Prachum Utaprom Saranyaras Tongsawai Suriya Namgaew Suvinai Sodajaroen Copyright (c) 2023 Wichai Nramat, Wasakorn Traiphat, Phuachat Sukruan, Prachum Utaprom, Saranyaras Tongsawai, Suriya Namgaew, Suvinai Sodajaroen 2023-01-19 2023-01-19 1 54 66 10.21303/2461-4262.2023.002604 Analysis of flow characteristics of cylindrical and helical type multi-lobe roots blower <p>Roots blower is a positive displacement machine that has the advantage of a larger flow than conventional blowers. Roots blowers are widely used in industrial production such as chemicals, food, medical, etc. However, during actual operation, this type of machine often achieves low performance. One of the issues that greatly affect performance is the flow characteristics of the blower. Flow characteristics include factors related to flow rate, pressure, and flow phenomena in the blower chamber. Flow characteristic analysis is a complex problem in hydraulic machines. Flow analysis helps to investigate the motion of the flow to design high-performance machines. This study uses a mathematical model of gear theory to design the rotor profile with cylindrical and helical lobes of the multi-lobe Roots blower. The rotor profile is formed on the principle that the ellipse rolls without slipping on the base circle. On the basis of the mathematical model of the rotor profile, the paper compares the flow rate and pressure characteristics of the two blowers. The fluid dynamics analysis model was built on ANSYS software. The structural grid model is also built to increase the computational efficiency of the mathematical model. The lobes are embedded and rotated in the blower chamber. The results show that with the same radial and axial dimensions, the cylindrical lobe has a larger flow. However, the helical lobe has a more stable flow quality than the cylindrical lobe (15.2&nbsp;% less flow fluctuation). In terms of pressure, the helical lobe type has a higher pressure than the cylindrical lobe type. In addition, the helical lobe type also reduces the influence of eddy currents acting on the blower chamber walls and rotors. That results in increased blower efficiency. The results of the paper will be a reliable basis for reducing time in the development of multi-lobe Roots blowers with high performance</p> Ngoc-Tien Tran Duc-Minh Nguyen Copyright (c) 2023 Ngoc-Tien Tran, Duc-Minh Nguyen 2023-01-19 2023-01-19 1 67 75 10.21303/2461-4262.2023.002578 A theoretical method of describing the interaction of raw cotton with moving working bodies of cotton-cleaning machines <p>A theoretical regularity of the general behavior of raw cotton as a porous medium in the technological processes of its mechanical processing is substantiated for the first time. The speed of sound in a porous cotton medium is determined. The effect of additional force stresses inside the cotton medium, caused by the filtration of the air component from cotton raw materials during the introduction of the working body, is disclosed. A generalized equation is obtained that describes the force stress in a cotton medium when exposed to a variety of shapes of working bodies of cotton machines. A method for calculating the damage to seeds and cotton fibers in the process of interaction with the working bodies of processing machines is proposed.</p> <p>In the process of processing raw cotton or cotton fiber, the fibrous mass is sharply mechanically affected by organs on the work of organs in the area of inflammation or disease, while complex processes occur inside the fibrous mass associated with a change in the measurement of density and pressure in it. Stresses in the fibers in the presence of conditions of high density of body mass, which can be manifested by plastic deformation, shortening of the fibers and severity of quality. The derived theory for the stress state of cotton raw materials in the process of processing allows to use it practically in all important issues of describing the damage of fiber and cotton seeds in the technological operations of primary processing of cotton</p> Fazil Veliev Copyright (c) 2023 Fazil Veliev 2023-01-19 2023-01-19 1 76 85 10.21303/2461-4262.2023.002756 Combined analysis of acoustic emission and vibration signals in monitoring tool wear, surface quality and chip formation when turning SCM440 steel using MQL <p>With modern production, Minimum Quantity Lubricant (MQL) technology has emerged as an alternative to conventional liquid cooling. The MQLs is an environmentally friendly lubricant method with low cost while meeting the requirements of machining conditions. In this study, the experimental and analytical results show that the obtained acoustic emission (AE) and vibration signal components can effectively monitor various circumstances in the SCM440 steel turning process with MQL, such as surface quality and chip formation as cutting tool conditions. The AE signals showed a significant response to the tool wear processes. In contrast, the vibration signal showed an excellent ability to reflect the surface roughness during turning with MQL. The chip formation process through the cutting mode parameters (cutting speed, feed and depth of cut) was detected through analysis amplitude of the vibration components <em>Ax</em>, <em>Ay </em>and<em> Az</em> and the AE signal. Finally, Gaussian process regression and adaptive neuro-fuzzy inference systems (GPR-ANFIS) algorithms were combined to predict the surface quality and tool wear parameters of the MQL turning process. Tool condition monitoring devices assist the operator in monitoring tool wear and surface quality limits, stopping the machine in case of imminent tool breakage or lower surface quality. With the unique combination of AE and vibration analysis model and the training and testing samples established by the experimental data, the corresponding average prediction accuracy is 97.57&nbsp;%. The highest prediction error is not more than 3.8&nbsp;%, with a confidence percentage of 98&nbsp;%. The proposed model can be used in industry to predict surface roughness and wear of the tools directly during turning</p> Dung Tien Hoang Nguyen Van Thien Thoa Thi Thieu Pham Trinh Duy Nguyen Copyright (c) 2023 Dung Tien Hoang, Nguyen Van Thien, Thoa Thi Thieu Pham, Trinh Duy Nguyen 2023-01-19 2023-01-19 1 86 101 10.21303/2461-4262.2023.002509 Experimental determination of dynamic characteristics of a railway track <p>It is known a priori that vibrations that occur in the elements of the track structure during the passage of a train load are a superposition of free and forced mechanical vibrations. It has been established that the range of oscillation frequencies of the elements of the track superstructure includes oscillations with a frequency from tens to hundreds and thousands of hertz. However, the influence of vibrations on the track and their dependence, in turn, on the design of the track, has not been fully studied, which causes controversy between specialists in this matter. There is an opinion that in intermediate fastenings, the main role is played by an elastic gasket, which ensures the vertical rigidity of the rail-sleeper assembly. It has been experimentally established that in the frequency range below the frequency of free oscillations of rail fastenings, the force applied to the upper surface of the elastic gasket is transferred to the lower surface in an unchanged form.</p> <p>The article discusses the vibrations that occur in the elements of the upper structure of the track (rails, sleepers, rail fastenings, ballast base) during the passage of a moving load, which significantly affect the strength, and, consequently, the durability of both the elements themselves and the railway track generally. Vibrograms, oscillograms, accelerograms of rail oscillations and their spectra during the passage of TALGO are presented. At present, the VOSSLOH fastening, developed in Germany, has been widely used in the construction of tracks on high-speed railways of the Republic of Kazakhstan. In this regard, there is a need for a comprehensive study of the operation of this type of fastening under a train load</p> Aigul Zhangabylova Gulmira Bikhozhayeva Mikhail Kvashnin Assel Kurbenova Kuralay Joldassova Copyright (c) 2023 Aigul Zhangabylova, Gulmira Bikhozhayeva, Mikhail Kvashnin, Assel Kurbenova, Kuralay Joldassova 2023-01-19 2023-01-19 1 102 111 10.21303/2461-4262.2023.002748 The evaluation on performance of narrow- gap welding thick steel plates under the influence of main welding parameters <p>This work presents the experimental results of narrow gap butt welding of steel plates with large thickness by using the Metal Active Gas (MAG) welding method.The typical defects are accompanied with this process such as the infusion in the side wall and the porosity due to the narrow gap which affect on the melting process. Thus, some publications noted the results of welding for the thickness up to 20−30&nbsp;mm and the chamfer angle about 30° using GMAW/MIG, GTAW/TIG, SMAW and new development such as laser – arc hybrid, laser multi- pass technique, super -TIG welding etc. But the production requires the solution to save the costs by the reduction of time, labour and investment keeping the standard quality. That is the aim of this study. In order to improve the quality of weld joint and increase the productivity of the process, is it suggested to develop the innovative welding process, in which the welding voltage – <em>U<sub>w</sub></em>, the translational velocity of the tip – <em>V<sub>t</sub></em>, and rotational velocity of the tip – <em>V<sub>r</sub></em>, are changing. This helped to increase the thickness of steel plates up to 50&nbsp;mm and the chamfer angle decreased at 15°, providing the satisfied quality of the weld. The micrography study serve as the preliminary proof of this hypothesis.</p> <p>The microstructures in 4&nbsp;regions, such as the weld center zone, heat-affected zone (HAZ), parent metal region, and the boundary between the weld metal and the HAZ were examined. The microstructures of 13&nbsp;positions from different experiments are investigated using the optical microscope (Axiovert&nbsp;25).These experiments covered all specific points (node) locating accordingly to three layers from bottom to top of the weld joint . The findings proved the welding quality is similar in case of narrow gap but the chamfer angle is twice lower and the thickness is increased. The result of the study enhances the productivity due to saving the labour cost and the welding materials. It is recommended to consider the effect of other factors (such as cooling conditions, dwell time when the arc approaching the side walls) to optimize the weld quality. There is the huge volume of the heavy steel constructions with the thick steel construction and specific narrow gap in industry. The results of this study with the optimization and more deeper evaluation the influence of main parameters of welding process to eliminate the typical defects will be the valuable reco&nbsp;mmendation for the managers and engineers in the production of metallic constructions</p> Vu Duong Copyright (c) 2023 Vu Duong 2023-01-19 2023-01-19 1 112 119 10.21303/2461-4262.2023.002588 Combination of design of experiments and simple additive weighting methods: a new method for rapid multi-criteria decision making <p>Multi-criteria decision making to choose the best option is a complicated task but a required activity in all fields. The problem will be more complicated if, after making a decision, one/several options are added to the list of options to be ranked. In this case, if only a certain multi-criteria decision making method is used, the decision-making shall be required to be started over again. This study recommends a simple solution to overcome this situation. The recommended solution is a combination between the Design Of Experiments method and a certain multi-criteria decision making method. Simple Additive Weighting method was selected in this study as one of the multi-criteria decision making methods for testing. Use the Design Of Experiments method to design an experiment matrix with the main input parameters being the criteria of options. The Simple Additive Weighting method is applied to calculate the output value of each experiment, called the score of the experiment. Develop a mathematical relation between the scores of the experiments and the criteria. This relation is used to recalculate the scores for options to be ranked. Three different cases were performed to evaluate the effectiveness of the new method. The results of ranking alternatives by new method have been compared with when using other methods. Sensitivity analysis was also performed in each case. The generation of different scenarios is done using different methods to determine the weights for the criteria. The best alternative determined when using the new method is always similar to when using other methods. In addition, when using the new method, the best alternative is determined regardless of the method of determining the weights for the criteria. The obtained results have proved the accuracy of the methodology and the advantages of the recommended method. Future work is also mentioned in the last part of this article</p> Tran Van Dua Copyright (c) 2023 Tran Van Dua 2023-01-19 2023-01-19 1 120 133 10.21303/2461-4262.2023.002733 A numerical research on the interaction between underwater explosion bubble and deformable structure using CEL technique <p>The dynamic process of an underwater explosion (UNDEX) bubble in the vicinity of deformable structures is a complex phenomenon that has been studied by many researchers. The dynamic process of a UNDEX bubble is a complex transient problem that results in a highly distorted bubble and large deformation of the structure. The previous work has introduced various solutions for studying the interaction between the UNDEX bubble and deformable structure. The interaction between the bubble and nearby structures has been widely solved by the combination of the boundary element method (BEM) and the finite element method (FEM). However, this couple requires tight time-step controlling, long-time analysis, and large computer resources. Furthermore, this combination is not widely used as the FEM code in commercially available software for solving UNDEX bubble problems. This paper presents a coupled Eulerian-Lagrangian (CEL) approach in commercial software to deal with the fluid-structure interaction (FSI). The numerical model of a UNDEX bubble is first developed and verified by comparing results with experimental, BEM, and empirical data. Then both bubble behavior and structural deformation are examined in various case studies. The numerical results show that the stiffness of the structure has strongly influenced the bubble behavior and the water jet development. The pressure pulse becomes significantly large as the bubble collapse. Besides, this numerical approach also can reproduce crucial phenomena of a UNDEX bubble, such as the whipping effect and water jet attacks. Although the numerical model is developed using simplified boundary conditions, the proposed approach shows the feasibility of simulating the important features of a UNDEX bubble process as well as the response of nearby structures.</p> Anh-Tu Nguyen Copyright (c) 2023 Anh-Tu Nguyen 2023-01-19 2023-01-19 1 134 151 10.21303/2461-4262.2023.002637 Geotechnical and thermal analysis and complex impedance spectroscopy characterization of pure Moroccan bentonite material for civil engineering applications <p>Combined modulus and impedance spectra are employed in the present work to explore electrical inhomogeneity and carriers’ behaviors in a pure bentonite Moroccan clay based on equivalent circuit. It has been clearly observed that the electrical properties change due to the increase of temperature from 300&nbsp;°C to 700&nbsp;°C. The frequency-dependent imaginary modulus <em>M</em>" and imaginary impedance <em>Z</em>" curves has only one peak at each temperature indicating the predominance of the contribution of grains to the total electrical conduction in bentonite. The positions of these peaks move to higher frequencies when the temperature increases in relation with the distribution of relaxation time. Moreover, the activation energy for the conduction process in bentonite is determined from the slope of ln(ρ<em><sub>dc</sub></em>) versus of 1/<em>T</em> in the order of 700&nbsp;meV in good agreement with that obtained from the proposed equivalent circuit. On the other hand, let’s present a geotechnical study that show that our material is a swelling clay, very plastic and could be used as a binder. The external stress dependence of the bulk density, Young’s module and maximum stress are analysed. The thermal conductivity determined following the device of Lee's disks where two copper disks of thickness of 15&nbsp;mm and diameter of 30&nbsp;mm were used</p> Mohamed Essaleh Rachid Bouferra Imad Kadiri Soufiane Belhouideg Mohammed Mansori Abdeltif Bouchehma Mohamed Oubani Mohamed Benjelloun Copyright (c) 2023 Mohamed Essaleh, Rachid Bouferra, Imad Kadiri, Soufiane Belhouideg, Mohammed Mansori, Abdeltif Bouchehma, Mohamed Oubani, Mohamed Benjelloun 2023-01-19 2023-01-19 1 152 164 10.21303/2461-4262.2023.002571 Determination of the green function of a pulsed acoustic source in a uniform homogeneous flow with an arbitrary Mach number <p>The wave field created by a pulsed point source of sound in a uniform homogeneous flow with an arbitrary value of the Mach number is theoretically studied. The aim of research is to obtain an analytical dependence of the sound field on physical parameters.</p> <p>The space-waveguide Fourier expansion of the sound field is used to solve the Cauchy problem for the wave equation in a reference frame moving together with the medium. It is only necessary to transform the spatiotemporal dependence of the source, given in a fixed frame of reference, to a dependence in a moving frame of reference.</p> <p>The transition to the description of the solution in the frame of reference, relative to which the medium moves at a constant velocity, is made taking into account the main properties of the generalized Dirac δ-function.</p> <p>Analytical dependences of the sound field on physical parameters are obtained for both subsonic and supersonic flows. A comparison is made with the results of calculations for the case of a pulsed point source moving in a medium at rest. The solution obtained in this work for the case of an impulsive source moving in a medium at rest made it possible to trace its connection with the Green's function for a stationary source in a moving medium. The analytical dependence of the obtained solution for the Green's function makes it possible to write down the explicit form of the "characteristic solution surface", that is, the "wave front". It is shown that the difference between the solutions for subsonic and supersonic motion is characterized by the position of the source relative to the moving wavefront.</p> <p>The calculation results can be used to describe the sound field created by an arbitrary spatiotemporal distribution of sound sources</p> Anatoliy Bryukhovetski Aleksey Vichkan' Copyright (c) 2023 Anatoliy Bryukhovetski, Aleksey Vichkan' 2023-01-19 2023-01-19 1 165 176 10.21303/2461-4262.2023.002743 Handling multi-collinearity using principal component analysis with the panel data model <p>When designing a statistical model, applied researchers strive to make the model consistent, unbiased, and efficient. Labor productivity is an important economic indicator that is closely linked to economic growth, competitiveness, and living standards within an economy. This paper proposes the one-way error component panel data model for labor productivity. One of the problems that we can encounter in panel data is the problem of multi-collinearity. Therefore, multi-collinearity problem is considered. This problem has been detected. After that, the principal component technique is used to get new good unrelated estimators. For the purposes of our analysis, the multi-collinearity problem between the explanatory variables was examined, using principal component techniques with the application of the panel data model focused on the impact of public capital, private capital stock, labor, and state unemployment rate on gross state products. The analysis was based on three estimation methods: fixed effect, random effect, and pooling effect. The challenge is to get estimators with good properties under reasonable assumptions and to ensure that statistical inference is valid throughout robust standard errors. And after application, fixed effect estimation turned out to play a key role in the estimation of panel data models. Based on the results of hypothesis testing, the real data result showed that the fixed effect model was more accurate compared to the two models of random effect and pooling effect. In addition, robust estimation was used to get more efficient estimators since heteroscedasticity has been confirmed</p> Ahmed Hassen Youssef Engy Saeed Mohamed Shereen Hamdy Abdel Latif Copyright (c) 2023 Ahmed Hassen Youssef, Engy Saeed Mohamed, Shereen Hamdy Abdel Latif 2023-01-19 2023-01-19 1 177 188 10.21303/2461-4262.2023.002582 Proof of the possibility for a public audit of a secret internet voting system <p>The aim of this study is to prove the possibility of building a system of secret Internet voting, in which a full-fledged audit is available to all voters and their proxies. A full-fledged audit should be understood as such an audit, in which everything that may be in doubt is checked. The open block of servers was created using Raspberry Pi&nbsp;3 Model B type minicomputers, which are widely known and well-established. On the basis of an open block of servers, a full-scale model of the system for conducting experimental voting was created and a detailed methodology for a full-fledged audit was developed. This methodology provides for two stages of the audit. In the first stage, voters or their proxies must be present near the server unit. In the second stage, they continue the audit remotely through a dedicated server without losing information about the security of their data. For practical acquaintance with this research, the possibility of experimental voting is given. The experiment can be conducted by anyone at any time through a link on the Internet. Thus, it is shown that not only with traditional secret voting technologies, a full-fledged audit is possible, thanks to which voters have no doubts about maintaining the secrecy of their votes and the honesty of the results. To conduct a full-fledged audit according to the described methodology, it is not require to involve highly qualified specialists, but school education, which is mandatory in many countries, is quite enough. The importance of the results is that the lack of a full-fledged audit of Internet voting systems is the main factor hindering the development of e-democracy. The lack of public auditing of Internet voting systems causes distrust in the possibility of using the Internet to conduct fair elections</p> Yurii Khlaponin Volodymyr Vyshniakov Oleh Komarnytskyi Copyright (c) 2023 Yurii Khlaponin, Volodymyr Vyshniakov, Oleh Komarnytskyi 2023-01-19 2023-01-19 1 189 200 10.21303/2461-4262.2023.002742