Technology audit and production reserves

Consideration of electronic mean heat transport via a low dimension system

Thu, 11 Apr 2024 00:00:00 +0300

The object of research is the complex realm of energy localization and coherent ballistic electronic transport within low-dimensional silicon quantum wires, specifically those doped with germanium atoms. Unlike their three-dimensional counterparts, low-dimensional systems exhibit unique electronic transport behaviors, necessitating novel analytical approaches for a comprehensive understanding. The core of this investigation leverages the Phase Field Matching Theory (PMFT) and the tight-binding (TB) approximation, sophisticated methodologies that enable a deep dive into the quantum mechanical nuances of these systems. Through this lens, we examine the intricate dynamics of dispersion relationships, phase factors, group velocities, and notably, the impact of defects introduced by the germanium doping.

This research meticulously analyzes how these defects affect electronic and thermal conductivities, along with densities of states, offering new insights into the role of Fano resonances in the fluctuation of transmission and reflection spectra. These resonances, we find, are crucially dependent on the nature of the defects, their configuration, and the electronic parameters in their vicinity, underscoring the nuanced interplay between material composition and electronic properties in low-dimensional systems.

The implications of our findings extend far beyond the theoretical. They pave the way for significant advancements in nanotechnology and the design of electronic devices, highlighting the potential for creating more efficient, high-performance components. Furthermore, this work proposes a framework for developing non-destructive testing methodologies that could revolutionize material science by enabling the precise analysis of defects in low-dimensional systems without causing damage. This is particularly critical for the ongoing development of materials with optimized properties for various applications, from electronics to energy storage.

In essence, this research not only enriches our understanding of the physics governing low-dimensional systems but also offers practical insights into leveraging these properties for technological innovation. By bridging the gap between theoretical physics and material science, our study sets the stage for the next generation of electronic components and non-destructive evaluation techniques, marking a significant step forward in the application of quantum mechanics to real-world challenges.

Analysis of the energy efficiency of a system with a hybrid solar collector and thermal energy storage

Stepan Mysak, Stepan Shapoval — Mon, 15 Apr 2024 00:00:00 +0300

The object of research is heat transfer in a hybrid thermal photovoltaic solar collector.

International agreements and strategies aimed at combating climate change and reducing greenhouse gas emissions strongly call for the active implementation of renewable energy sources on a global scale. A special emphasis is placed on the development of solar energy, which has significant growth potential due to the constant improvement of technologies and cost reduction of production. With this in mind, the authors focused on the development and analysis of a computer model of an innovative hybrid system that effectively combines a solar collector for the simultaneous production of both thermal and electrical energy.

The research included a detailed study of the temperature changes of the heat carrier in the hybrid photovoltaic solar collector and thermal accumulator during the period of solar irradiation. Thanks to careful monitoring, the main patterns of gradual temperature increase in both key components of the hybrid system were established. In addition, an assessment of the dynamics of changes in the instantaneous thermal power of the solar collector under the influence of various factors, such as the intensity of solar radiation, the angle of inclination of the collector, wind speed, etc., was carried out.

The results of computer modeling showed the average indicator of the efficiency of the entire hybrid system, as well as its variations during a certain time of operation. In addition, the change in the instantaneous specific heat capacity and the overall efficiency of heat energy generation by the hybrid photovoltaic solar collector were analyzed. Special attention was paid to the study of the dynamics of changes in the thermal efficiency of the entire system, as well as its ability to efficiently store thermal energy in a specialized battery.

The comprehensive analysis made it possible to obtain the key thermophysical parameters of the developed hybrid system with a photovoltaic solar collector. This data is extremely important, as it will allow engineers and scientists to accurately calculate the potential performance and efficiency of such a system when it is put into practical use in the future. In general, the results of the study emphasize the promising development of hybrid solar collectors as one of the leading technologies in the field of renewable energy in the context of global challenges of climate change.

Design of the intensification method with the help of FracCADE software

Victoriia Rubel, Vadym Pshyk — Fri, 29 Mar 2024 00:00:00 +0200

The object of research in the work is the FracCADE software, with which it is possible to simulate the process of hydraulic fracturing and well field, on which the intensification method is designed. This hydraulic fracturing simulator was developed by Schlumberger Ltd. based on proven physical principles of hydraulic fracturing to optimize the treatment process and proven in practice. The system includes a range of hydraulic fracturing models, from 2D models to extensive 3D simulations with lateral communication. It includes a number of complementary modules for fracturing fluid and proppant optimization, injection scheduling, real-time monitoring, pressure equalization, production forecasting and economic evaluation. Some models allow simulating the geometry of the fracture, solving proppant concentration problems, and simulating possible shielding due to proppant covering the fracture or the dehydration process.

Hydraulic fracturing remains one of the main engineering tools for increasing the productivity of wells. The effect is achieved due to:

– creation of a conductive channel (fracture) through the damaged (contaminated) zone around the well, in order to penetrate beyond its boundaries;

– spreading of the channel (fracture) in the formation to a considerable depth in order to further increase the productivity of the well;

– creation of a channel (fracture), which would allow changing, influencing the fluid flow in the formation.

In the latter case, fracturing really becomes an effective tool that allows to manage the operation of the reservoir (in particular, change its filtering characteristics) and implement long-term strategic development programs. The concept of hydraulic fracturing is quite simple. In general, for relatively simple geology, the physical foundations of fracturing theory are fairly well developed and tested. For the most part, the difficulties boil down to two problems: the real geological conditions and the complex multidisciplinary nature of the fracturing process itself.

The process of designing fracturing in order to achieve a certain result is closely related to rock mechanics (which affects the geometric parameters of the fracture), fluid hydromechanics (in which the tasks of controlling the flow of the working fluid and placing the proppant in the fracture are solved) and chemistry, which determines the behavior of materials, which are used during hydraulic fracturing. Moreover, the hydraulic fracturing project must take into account the physical limitations imposed by the specifics of the real deposit and well. In addition, to achieve the desired results, the fracturing operation must be carried out in strict accordance with the calculations (that is, a complete cycle in which each operation plays its role).

Improving the technology of manufacturing cast brake drums in pink sand molds

Vitalii Lysenkov, Dmitriy Demin — Fri, 12 Apr 2024 00:00:00 +0300

The object of research in the paper is the production technology of casting «brake drum» from cast iron of the basic grade SCh20 according to GOST 1412-85 (DSTU EN 1561, EN-GJL-200). The existing problem is that due to the imperfection of the technological processes of manufacturing castings, final internal defects of a shrinking nature are possible. This can lead to a decrease in the strength and operational reliability of the drums, regardless of the chemical composition, which may meet the technical conditions and should provide the specified strength indicators according to the grade of cast iron.

Based on the results of 3D modeling, it has been found that with the existing technology of manufacturing brake drum castings in one-time sand molds, final shrinkage defects are formed in the upper part of the casting. To eliminate this problem, a decision is proposed to increase the allowance for mechanical processing on the upper surface of the casting. The possible excess of the mass of the casting and excess consumption of the alloy that will occur when implementing this solution can be compensated by reducing the allowance on other surfaces based on their optimization by the method of dimensional chains and reducing the thickness of the casting wall. For this, a reduction in the carbon content in the alloy is proposed as a factor in increasing the tensile strength of cast iron. On the basis of 90 serial meltings in industrial conditions, the possibility of increasing the strength limit of cast iron by approximately 11 % by reducing the average carbon content in cast iron from 3.45 % to 3.4 % has been proven.

The proposed solutions are the essence of improving the production technology of cast brake drums, which are produced by casting in one-time sand molds.

The presented study will be useful for machine-building enterprises that have foundries in their structure, where iron is melted for the production of castings.

The choice of rational adjustment of the chemical composition of iron melted in an electric arc furnace on the basis of technological audit of serial films

Denis Nikolaev — Fri, 05 Apr 2024 00:00:00 +0300

The object of research in the work is cast iron of the SCh20 grade according to GOST 1412-85 (DSTU EN 1561, EN-GJL-200), which is melted in an electric arc furnace. In this work, the parameters of serial smeltings of cast iron used for machine-building castings were determined, which were used to select the content of elements of the chemical composition.

The existing problem is that the impossibility of taking into account many factors influencing the formation of the chemical composition of cast iron during smelting leads to deviations of the chemical composition from the requirements regulated by the technical conditions. The main reason for this is the uncontrollability of the chemical composition of the charge materials and the difficulty of accurately determining the soot of the elements during the smelting process. This can lead to the formation of a shortage of cast iron, or to excessive costs for smelting, associated with the need for additional technological operations and the use of additional materials to eliminate detected deviations of the composition from the requirements.

The procedure of technological audit of serial smeltings is proposed, the feature of which is a comprehensive assessment of the actual indicators of smelting. They include: mathematical expectations of the content of the elements of the chemical composition, estimates of their dispersions, root mean square deviations, systematic errors, scattering fields and deviations of the lower and upper limits of the content of each element from the lower and upper limits required by the technical conditions. The results of such an audit are the possibility of calculating corrective combinations of charge materials and ferroalloys, which eliminate inaccuracies in the calculation of the charge and the determination of the heat of the elements during the smelting process.

As a result of the audit of a sample of 31 serial smelters, it was established that the average content of the elements C, Mn, Si, Cr exceeds the average required by technical conditions. These deviations are: +0.04 % C, +0.06 % Mn, +0.038 % Si, +0.06 % Cr. To compensate for these deviations, the following combination of charge materials and ferroalloys, which are introduced into the melt before delivering the cast iron to the casting area, is proposed: 44 kg of steel scrap +88 kg of recycled iron.

The presented study will be useful for machine-building enterprises that have foundries in their structure, where iron is melted for the production of castings.

Development of the hardness mathematical model of Ti-alloyed iron for cast parts used in conditions of intensive abrasive friction

Andriy Barsuk — Wed, 03 Apr 2024 00:00:00 +0300

The object of research is wear-resistant cast iron, intended for cast parts that work under conditions of intense abrasive friction during operation. Examples of such parts can be mixer blades of various functional purposes, the operational properties of which include stability, which depends on the hardness, determined on the HRC scale. To give such cast parts wear-resistant properties, the cast iron from which they are made is alloyed with elements that contribute to the formation of carbides of different composition: W, V, Mo, Ti, etc. The main problem that prevents the purposeful selection of materials is incomplete knowledge about the effect of chemical composition on properties, in particular, wear resistance, which prevents a justified selection criterion.

Using regression analysis methods, a mathematical model was obtained, including a regression equation of the form HRC=f(C; C_eq; Ti), which relates the content of carbon, titanium and carbon equivalent in cast iron and hardness. The resulting model allows for purposeful selection of the chemical composition, which ensures a given value of HRC, on which wear resistance depends. Optimization of the chemical composition, performed according to this model, made it possible to determine that the chemical composition, which provides the maximum hardness of HRC=49, is outside the planning area: C=3.54 %, C_eq=3.95 %, Ti=3.56 %. It was established that the same value of hardness can be obtained inside the considered planning area, which has an arbitrary appearance, provided with available conditions of a passive experiment. According to the available experimental data, the values of the input variables equal to C=3.34 %, C_eq=3.727 %, Ti=0.73 % ensure obtaining hardness at the level of HRC=49. Such alternative options regarding composition and properties may indicate that the HRC=f(C; C_eq; Ti) response surface has a complex appearance that requires additional research.

Development of decision-making technology for the provision of services in project implementation

Tue, 09 Apr 2024 00:00:00 +0300

The object of research is decision-making processes regarding the provision of services within the framework of cross-border projects.

To achieve the aim of the research, an analysis of the service provision market was first conducted, its features have been revealed and problems arising in the processes of its functioning have been identified. The main problem is to find the optimal distribution of services between performers in the service management system. A mathematical model of the problem of single- and multi-criteria optimization has been developed, where the problem is decomposed into independent sub-problems. The problem is presented in the form of a linear programming problem. Various efficiency criteria of the found distributions are proposed. Depending on the number of criteria, the problem will be a single-criteria Boolean programming problem or a multi-criteria optimization problem. An iterative method for finding the optimal distribution of services has been created, and individual methods are laid out in the form of production rules, which is understandable and allows to gain new knowledge.

Based on the obtained data, a decision-making technology has been developed regarding the distribution of service consumers between performers. At the same time, decision-making methods were used, which allow optimizing the processes of service provision. A systematic approach was used when designing information technology. This made it possible to create an effective and problem-relevant technology that helps in making informed decisions about the distribution of services between participants of cross-border projects. A structural and functional diagram of the decision support system has been developed. Its structural elements are detailed.

The obtained results reflect a thorough analysis of the current state of the services market and the development of effective decision-making technology, which contributes to the optimization of work in the field of cross-border projects. This approach can be useful for various subjects involved in the implementation and coordination of international projects.

Development of high-speed algorithm for binomial arithmetic addition

Igor Kulyk, Maryna Shevchenko, Anatolii Melnyk, Tetyana Protasova — Tue, 09 Apr 2024 00:00:00 +0300

The object of research is the method and algorithm of arithmetic addition of binomial numbers generated by binary binomial counting systems. The lack of binomial arithmetic, in particular the operation of adding binary binomial numbers, in a certain way prevents their introduction into information systems and the construction of information and communication technologies based on them for combinatorial optimization, generation of combinatorial objects, data compression and encryption.

In the framework of the proposed approach, instead of operating with binomial coefficients, only operations with their upper and lower parameters are carried out. At the same time, the weighting coefficients of binary binomial numbers, which are added to each other, are represented in the form of two-component tuples. Taking this into account, this paper presents an algorithm for binomial arithmetic addition using dynamic arrays.

The main idea, which is included in the structure of the algorithm of binomial arithmetic addition based on dynamic arrays, is that the transition from a two-dimensional model of summation to a one-dimensional one is carried out. At the same time, only available, existing binomial coefficients are placed in the dynamic array. Accordingly, the search for binomial coefficients equal to or greater than the quantitative equivalent takes place in much smaller areas. In comparison with the algorithm based on matrix models, this quite significantly reduces the amount of time spent when performing the summation operation, and also reduces the requirements for the amount of memory required for placing two-component tuples of the assembly array.

In the course of the research, a several-fold decrease in the number of machine cycles required to search for the necessary elements in the dynamic array was practically confirmed. This leads to an increase in the performance of the presented algorithm of binomial arithmetic addition based on dynamic arrays. In turn, this leads to the acceleration of solving information tasks of combinatorial optimization, generation of combinatorial objects, data compression and encryption, for the solution of which the operation of adding binary binomial numbers is used.

Exploring an LSTM-SARIMA routine for core inflation forecasting

Dmytro Krukovets — Fri, 05 Apr 2024 00:00:00 +0300

The object of the research is the Core Inflation Forecasting. The paper investigates the performance of the novel model routine in the exercise of the Core Inflation Forecasting. It aggregates 300+ components into 6 by the similarity of their dynamics using an updated DTW algorithm fine-tuned for monthly time series and the K-Means algorithm for grouping. Then the SARIMA model extracts linear and seasonal components, which is followed by an LSTM model that captures non-linearities and interdependencies. It solves the problem of high-quality inflation forecasting using a disaggregated dataset. While standard and traditional econometric techniques are focused on the limited sets of data that consists just a couple of variables, proposed methodology is able to capture richer part of the volatility comprising more information. The model is compared with a huge pool of other models, simple ones like Random Walk and SARIMA, to ML models like XGBoost, Random Forest and simple LSTM. While all Data Science model shows decent performance, the DTW+K-Means+SARIMA+LSTM routine gives the best RMSE over 1-month ahead and 2-month ahead forecasts, which proves the high quality of the proposed forecasting model and solves the key problem of the paper. It is explained by the model's capability to capture both linear/seasonal patterns from the data using SARIMA part as long as it non-linear and interdependent using LSTM approach. Models are fitted for the case of Ukraine as long as they’ve been estimated on the corresponding data and may be actively used for further inflation forecasting.

Designing an Internet of Things solution for monitoring vital signs

Iryna Zinko, Olha Kravchenko, Dmytro Syvoglaz — Tue, 09 Apr 2024 00:00:00 +0300

The object of study is the process of monitoring vital signs using an automated system based on an Internet of Things (IoT) solution. The study investigates and analyses the best existing solutions for continuous monitoring of human health. The research is important in the context of a possible pandemic and general health monitoring.

An IoT model of a solution for monitoring and analyzing vital signs in patients is proposed. The project involves the creation of hardware and software for tracking vital signs. The interaction of the two parts will ensure that the main task is to obtain the result and analyze the indicators of vital functions of the human body. The hardware is implemented using devices for scanning data on heart rate, temperature, saturation, and the ability to track electrocardiograms. It is possible to transmit data on the state of the body. The position of the sensors attached to the body is taken into account in case they come off. The device itself should be placed on the human body in the area of the front chest wall, wrists, and ankles. The device is also programmed to respond to sudden changes in these values. The software implementation is based on a web-based interface. The design of the final solutions for the interaction between the local and intermediate server was implemented using Django and Python. The ability to administer the intermediate server of the client's time zone was written using HTML, CSS, and JavaScript. The use of the IoT solution allows monitoring the indicators of vital functions of the body and their analysis. A scheme of information exchange in the system for monitoring health indicators has been built.

Environment effect on mechanical parameters of soil-mixing

Menari Farouk, Sabah Moussaoui, Mourad Belgasmia, Khelifa Abbeche — Mon, 26 Feb 2024 00:00:00 +0200

Soil improvement is originally an economical solution to make soil buildable, particularly compared to deep foundation methods using piles. The object of this research is the understanding of the behavior of soil-mixing material, in particular, what concerns the effect of environmental parameters, whether: temperature, water table level, chemical attacks, the phenomenon of aging etc. on the mechanical and physical characteristics (resistance to simple compression, resistance to simple bending, modulus of elasticity, porosity, density, etc.), of a soil-mixing column, in the short term and long term. The big problem is how to carry out experiments in the laboratory, which will be representative of the different phenomena that take place on a real scale (on site). To do this, our approach consists of studying different soil-mixing mixtures composed of «artificial» soils (clay and sand) and a CEM III/C cement, and with a variable W/C ratio. After making the test pieces, with the different dosages of cements and a ratio between clay and fixed sand, they were kept under normal temperature conditions, in order to reach a maturation age (180 days), to be able to begin the series of experiments. Once the specimens were subjected to the aging test, let’s begin to crush them with simple compression and simple bending. The parametric study highlights a percentage of clay beyond of which the resistance decreases and the rigidity of the material can pose a problem for certain structural uses. The different results obtained show that for a low cement dosage, the humidification-drying cycle influences both the resistance to simple compression and to bending simple, as well as the number of cycles affects the resistance values significantly. On the other hand, for a greater or lesser dosage of cement, the resistance values are not affected. Based on the results obtained, it is possible to conclude that the choice of cement dosage depending on the nature of the soil influences the soil-mixing column and plays an important role on the lifespan of the column; therefore, it is necessary to give primary importance to the choice of cement dosage depending on the nature of the soil treated.

Improving the design of a jaw shutter to increase the efficiency of material crushing

Iryna Kazak, Dmytro Sidorov — Wed, 17 Apr 2024 00:00:00 +0300

The object of research is the design of a jaw crusher for crushing limestone for the production of silicate bricks. The article is devoted to the study of the problem of reducing the efficiency of material crushing in a jaw crusher. The efficiency of crushing materials in jaw crushers ensures the quality of manufacturing bricks, etc. Therefore, this work is aimed at choosing a way to improve the design of the jaw crusher to increase the efficiency of material crushing.

The article defines the classification of jaw crushers, their advantages and disadvantages, describes the principle of operation of the most widely used jaw crushers in the construction industry with simple and complex rocking of the cheek. A literature and patent search and analysis of existing methods of increasing the efficiency of material crushing in jaw crushers was carried out. As a result of the literature and patent search, one of the methods of improving the design of the jaw crusher to increase the efficiency of material crushing based on the use of longitudinal protrusions on the movable jaw was selected and proposed. The protrusions on the flat sections of the working surface of the plate are made with the same pitch of their location within each section with a decrease in the pitch of the protrusions in the direction of distance from the upper part of the plate. The considered design of the movable jaw with longitudinal protrusions in the jaw crusher will ensure reliable pulling of the material into the gap between the movable and stationary jaws, which ensures high contact stresses acting on the crushed material from the side of the working surface of the plate.

Compared to known designs of jaw crushers, the improved design of the movable jaw in the jaw crusher with longitudinal protrusions of different sizes with a decrease in their size in the direction from the upper part of the plate on three sections of the working surface of the plate will contribute to ensuring high contact stresses acting on the crushed material from the side of the working surface cheeks, during its advancement between the moving and stationary cheeks and increases the efficiency of destruction of various materials.

Compared to known designs of jaw crushers, the improved design of the jaw crusher has a movable jaw with longitudinal protrusions of various sizes. At the same time, these protrusions are located on three sections of the working surface of the plate with a decrease in their size in the direction from the upper part of the plate. This will help ensure high contact stresses acting on the crushed material from the side of the working surface of the cheek, during its advancement between the moving and stationary cheeks. Also, this design of the working jaw of the jaw crusher with longitudinal protrusions helps to increase the efficiency of destruction of various materials.

Development of white organic light emitting diodes based on carbazole-derived compounds

Serhii Melnykov, Orest Bilas — Fri, 12 Apr 2024 00:00:00 +0300

The object of research is the thermal, photophysical, and electrophysical properties of newly synthesized carbazole-derived compounds and organic light-emitting structures based on them. The problem consists in the comprehensive solution of scientific and technical problems of improving the characteristics of white organic light-emitting diodes (OLED), expanding their emission spectrum, improving color and energy characteristics.

The results of the thermal, electrophysical and photophysical properties of the investigated carbazole compounds were obtained. They demonstrated good thermal stability. Absorption spectra in solid films were recorded in the range of 300-350 nm. Photoluminescence spectra were observed at a wavelength of 407 nm for the first and second compounds and 430 nm for the third. The quantum yield of photoluminescence in films for compounds 1, 2, and 3 was 16 %, 7 %, and 7 %, respectively.

Organic light-emitting structures of white emission color with color coordinates (0.31, 0.35), (0.32, 0.34) and (0.38, 0.34) close to natural white light (0.33, 0.33) were formed using the thermovacuum sputtering method. The turn-on voltage of the white OLED is 6 V, the maximum brightness of the light-emitting structures was 10,000 cd/m². The devices demonstrated a sufficiently high external quantum efficiency of 5 % to 7 %.

The obtained results are explained by the mixing of different types of electroluminescence, namely excitonic and electromeric. Electromeric radiation is obtained due to transport layers. This approach improves such an important parameter of white light as its quality, which includes color coordinates and color rendering index.

Due to their color characteristics, white light-emitting diodes based on carbazole-derived compounds are promising candidates for use in modern lighting systems. A separate advantage of these light-emitting structures is the dependence of the color gamut of their radiation on the applied voltage. In addition, organic LEDs based on carbazole-derived compounds have low energy consumption and are environmentally friendly due to the absence of toxic substances in their design, which creates prerequisites for both global energy savings and a reduction of the industrial burden on the environment.

Component analysis for energy-efficient multimedia networks utilizing 5G radio access technologies

Vladyslav Lavrinenko, Mikhailo Stepanov — Tue, 09 Apr 2024 00:00:00 +0300

The object of the research is the energy-efficient multimedia networks based on 5G wireless access technologies.

The research is aimed at developing energy-efficient multimedia networks based on 5G wireless access technologies, considering the increasing importance of information and communication technologies (ICT) in modern society. With the proliferation of wireless access networks and the advancement of fifth-generation mobile networks (5G), there is a need to assess and reduce the environmental impact of ICT. The article specifically focuses on the challenges related to energy consumption and CO₂ emissions in radio access networks, highlighting the responsibility to balance technological advancements with environmental concerns.

The paper examines various components and technologies necessary for enhancing energy efficiency in multimedia networks. It discusses the concept of multimedia, including digital storage, data processing, and interactive elements. Statistical data is provided to underscore the significant energy consumption and carbon footprint of the ICT industry, with an emphasis on radio access networks. Heterogeneous networks, non-orthogonal multiple access (NOMA) technologies, and multiple-input multiple-output (MIMO) technologies are identified as key components for achieving energy efficiency. The importance of reducing the distance between transmitters and receivers in heterogeneous networks is emphasized, as well as the use of energy-saving strategies such as putting small base stations into sleep mode during low network loads. Special attention is given to the role of green data centers in reducing CO₂ emissions and optimizing the use of green energy in high-performance networks. Proposed methods include leveraging renewable energy sources, improving hardware energy efficiency, and implementing energy-efficient routing.

The findings offer valuable insights for the development and implementation of energy-efficient multimedia networks, particularly in the context of 5G networks. The interdisciplinary approach advocated in the conclusion emphasizes the collective efforts needed to address environmental challenges in the field of information and communication technologies. The combination of these technologies ensures efficient resource utilization and reduced environmental impact compared to similar known approaches.