Modeling Of Physical Processes Research Articles

ПРИМЕНЕНИЕ ВИЗУАЛИЗАЦИИ ДЛЯ УПРАВЛЕНИЯ АКТИВНОСТЬЮ ОБУЧАЮЩИХСЯ В ПРОЦЕССЕ ИЗУЧЕНИЯ МЕХАНИЧЕСКОГО ДВИЖЕНИЯ

The results of research work are presents.The purpose of work is to activate students by using the educational potential of visualization in conditions of harmonious complement of real and virtual laboratory work in mechanical movement studying process.
 For the first time in laboratory practice it was possible to successfully create virtual training models similar to real models of physical processes that complement real models using visualization tools and methods, as well as to perform simultaneously visualization of measuring instruments and physical processes within one laboratory task with variable initial data.

MAN IN SPACE AND SPACE IN MAN OR A HYDRO-MECHANICAL ANALOGY OF THE STREAMS OF LIFE

Based on the analysis of experimental data on the dynamics of a person’s physical condition and the activity of his organs, an extended interpretation of Kolmogorov’s hydrodynamic analogy is proposed. A satisfactory description by this physical model of the wave processes of life, starting from biological and ending with historical, creates a theoretical basis for its wide application in various branches of knowledge.

Modeling of physical and chemical processes in the synthesis of foam glass of various modifications: phase analysis and prediction of properties

To achieve effective thermal insulation of enclosing structures, it is necessary to increase the resistance to heat transfer through the use of advanced thermal insulation materials. A promising heat-insulating material is foam glass, which has a low thermal conductivity, high mechanical strength, frost resistance and low density. The physical properties of foam glass are determined by the structure of its macro- and microstructure, which depend on the temperature regime of synthesis and composition components. In the work, the choice of the optimal compositions of foam glass for correct comparison was carried out, a physicochemical model was developed, the qualitative and quantitative phase composition of foam glass samples was determined using the method of X-ray phase analysis to verify the results obtained. Based on the performed calculations of the composition of phases and components that are formed during the synthesis of various modifications of foam glass, the possible phases were determined using physicochemical models and methods for minimizing thermodynamic potentials. These methods make it possible to determine the equilibrium composition of a heterogeneous system and the thermodynamic parameters of processes. The reliability of the model is confirmed by the results of X-ray phase analysis, which showed the presence of phases obtained by calculation. The scientific novelty of the study lies in determining the features of the formation of crystalline phases during the synthesis of foam glass, taking into account the temperature-time conditions and composition. The study showed that the formation of the mineral composition of foam glass in the considered modifications is significantly affected by Na2B4O7∙10H2O and natural chalk. Additionally, microimpurities affect the formation of new aluminosilicate phases and the redistribution of the main chemical elements between the mineral components of foam glass. This also leads to changes in the density and composition of amorphous phases. An efficient model has been developed using the Gibbs isobaric-isothermal potential minimization method, numerical values of the number of probable phases and components formed during the synthesis of foam glass material have been obtained.

Computer models as a means of improving the effectiveness of teaching physics

Computer models and programs are one of the main tools in education, therefore, the development of a plan for their development and use in the field of education is one of the main problems. The use of computer models will help to explore a new topic, a demonstration experiment and phenomena without violating safety regulations. Many experts believe that the computer currently makes it possible to make a qualitative breakthrough in the education system. Models of physical phenomena and experiments actively shape students' knowledge. In teaching a number of sections of the physics course, such as atomic and nuclear physics, quantum mechanics, and elementary particle physics, essential questions about conducting experiments are obvious. These sections relate to important areas of physics that deal with the study of phenomena and processes in the microcosm. Therefore, due to some difficulties in equipping physics classrooms, the computer acts as an assistant. In quantum physics and atomic physics, computer models are considered that help explain the phenomena under study, the course of processes, as well as methods of working with computer programs that simulate laboratory installations in this section, since physical laboratory assistants are an integral part of training. The use of computer models and programs for educational purposes gives students a unique opportunity to plunge into the world of quantum and atomic physics. This study analyzes the effectiveness of such models in the educational process, their impact on students' understanding of the basic concepts of quantum and atomic physics, and also compiles questionnaires based on these problems. The survey covers about 40 physics teachers. The work is based on the analysis of existing pedagogical experiments and research in the field of application of computer models for teaching physics. The focus is on assessing the impact of these models on the quality of knowledge and their ability to make complex concepts accessible and understandable to students. The obtained results can serve as a basis for further improvement of methods of teaching quantum and atomic physics using computer programs. The introduction of computer programs can help the student create an effective learning environment for his work at his own pace and in collaboration with the class. It can be said that the use of models of physical processes in preparing students for effective learning opens up great opportunities for creating high-quality and new forms and methods, the use of computer models of physical phenomena plays an important role. Of particular importance in the development of students' abilities to observe, think, generalize based on observed facts, and predict the course of the observed process.

ФОРМУВАННЯ ПРЕДМЕТНИХ КОМПЕТЕНТНОСТЕЙ МАЙБУТНЬОГО ВЧИТЕЛЯ ФІЗИКИ ЗАСОБАМИ ІКТ

The article considers the importance of the competence approach in the training of future specialists, which means the focus of the educational process on the formation and development of key and subject competencies of the individual. The need to improve the system of professional training of future teachers based on a rational combination of traditional and innovative forms of organization of the educational process, in particular the use of modern pedagogical software training tools, is well-founded. The methodological features of conducting physics classes when using ICT differs from the classical one in that the teacher needs to develop new structural and logical schemes, a whole package of electronic materials (electronic applications in the form of tables, graphs, diagrams, electronic textbooks, presentations, video materials, complexes of electronic virtual laboratory works, etc.) before classes. ICT tools allow the teacher to expand the possibilities of presenting various types of information, to activate the attention of students, to strengthen their motivation, to develop cognitive processes: thinking, imagination and fantasy, to introduce modelling of physical processes and objects, to carry out automated control of knowledge, to implement the technology of remote and personally-oriented teaching.

Physical modeling in water treatment technologies

In most cases, water pollution is associated with the presence in it of a dispersed phase of various substances, which, depending on its physical state, forms various polydisperse heterogeneous aggregate-unstable systems: suspensions, emulsions, and foams. The paper analyzes the application of physical models for the description of complex dispersed systems, analyzes the possibilities of classic modeling methods and the limits of the application of the considered models. The paper studies the influence of temperature changes (of seasonal or climatic origin) on the kinetics of gravitational sedimentation in wastewater treatment technologies. Considered models of physical processes accompanying the gravitational deposition of dispersed particles in hydromechanical sedimentation tanks, which take into account the Brownian motion of these particles, capable, as it turns out, of causing coagulation. And coagulation makes it possible to transfer pollutants into a state of dispersed phase with a larger particle size. Within the framework of the considered model, it was established that the time and speed of particle sedimentation in gravity sedimentation systems may change significantly with external temperature changes. Accordingly, the quality of cleaning in a sedimentation plant, which works on the principle of gravity, can significantly increase (when heated from the outside) or decrease (when cooled). Thus, the need to take into account temperature changes in the processes of gravitational sedimentation of particles in treatment facilities is an urgent task. The paper concluded that in order to improve the existing technologies of water purification in the conditions of a change in external conditions (temperature), combinations of purification methods are appropriate for better water purification. In particular, the method of gravity sedimentation and the method of electrochemical or electrophoretic purification, gradual or simultaneous processes of hydromechanical sedimentation of pollutants, filtering or flotation processes. The practical significance of the work lies in the fact that it concerns the search for ways to improve the existing technological processes of water purification and increase its quality.

New applications of the fractional derivative to extract abundant soliton solutions of the fractional order PDEs in mathematics physics

The motive of this research work is to unravel the mysteries of nature through fractional-order partial differential equations (PDEs). Here, we focus on two important fractional order nonlinear PDEs, namely the fractional order (4+1)-dimensional Fokas equation, which is used to give the model of many physical phenomena and dynamical processes, and the other one is the fractional order (2+1)-dimensional breaking soliton equation which is used to analyze the nonlinear problems like optical fiber communications, ocean engineering, etc. Recently, it has been an essential topic to extract the new soliton solutions which are used to investigate the hidden physical conditions of the nonlinear fractional PDEs. So, it is essential to solve those nonlinear fractional PDEs which have a physical impact in the fields of science and modern engineering. In our investigation, we attempt to provide nonlinear wave propagation patterns and investigate the equations, as mentioned earlier, through a computational method. A computing operating software called Mathematica has been applied to get a clear visualization of our gained outcomes, and we ascertain such types of shapes as the bell shape soliton, the anti-bell shape soliton, the singular bell shape soliton, the periodic solution, and the singular periodic solution. Our obtained results can keep an indispensable role in explaining various physical phenomena of nature shortly, and the applied method is the very cogent, efficient, and interesting to extract such types of solutions. Since we extract abundant solutions of these models, so we hope that this article is the best applications of mention method.

МОДЕЛИРОВАНИЕ ФИЗИЧЕСКИХ ПРОЦЕССОВ СОЗДАНИЯ МАТЕРИАЛОВ

Improving the mechanical properties of metals and alloys is at the heart of the efforts of materials scientists and metallurgists to ensure the reliability of modern structural materials under various conditions. The specificity of the material of the Al-Fe-Si system with a content of each component of more than 5% makes it impossible to obtain the material by traditional casting. Additive manufacturing of materials is a new promising direction, which, thanks to the thermal effect, effectively creates multicomponent systems with favorable properties. This work is devoted to the processes of modeling physical processes, in particular, obtaining a phase diagram of the state of the cermet material of the Al-Fe-Si system in the ThermoCalc software package. The relevance of the study is determined by the development of a technology for obtaining material with a given composition and properties by additive methods, the use of a flux minimizes the waste of charge elements and eliminates oxidation at high temperatures. At the same time, the high temperatures achieved during the implementation of the synthesis ensure the full formation of the required phase composition. The purpose of this study is to model a multicomponent Al-Fe-Si system with its further testing. The temperature conditions for the formation of phases in a material with a composition of 60–90 wt % aluminum, 0–30 wt % iron, with a constant silicon content of 10 % are considered. This composition is characterized by the formation of one ternary compound with a highly symmetrical type of crystal lattice - the α-AlFeSi phase, while this phase exists in the temperature range of 950°C - 400°C. The results obtained predict the susceptibility of the material to plastic deformation, but exclusively using heating to the temperature of the predominance of the α-AlFeSi phase. The results of the physical experiment are in good agreement with the obtained simulation results. After synthesis, the material has a characteristic cast microstructure. The data obtained make it possible to select the technological conditions necessary for further processing of the obtained material.

Investigating limnological processes and modern sedimentation at Lake Żabińskie, northeast Poland: a decade-long multi-variable dataset, 2012–2021

Abstract. Here, we present a dataset of a decade-long monitoring project of Lake Żabińskie, a hardwater eutrophic lake in northeast Poland. The lake contains annually laminated (varved) sediments that form a unique archive of past environmental variability. Regular measurements of the lake water physical and chemical characteristics were done using a multiparameter sonde and a set of temperature sensors deployed in the water column. Seasonal variability in sediment fluxes was documented by a sediment trap. Field sampling provided information about the hydrochemistry of incoming streams and of the lake outflow. The overall monitoring program was designed to assess relationships among meteorological conditions, limnological processes, and modern sedimentation and to answer the question of whether meteorological and limnological phenomena can be precisely tracked with varves. However, this dataset can also be used for modeling physical and biogeochemical processes in lakes. The dataset is archived at https://doi.org/10.34808/w8w7-9x34 (Tylmann et al., 2023).

Determination of the Curie temperature of structural alloys by analyzing the electrical characteristics of wires

The Curie temperature for many structural multicomponent alloys can only be estimated approximately, for example, from state diagrams. The necessity of an operational assessment of this parameter arises in the design of technologies for processing and controlling structural materials, in mathematical modeling of physical processes. The paper describes an experimental method for determining the temperature of magnetic transformation by measuring the temperature dependences of inductance and electrical resistance of wire samples. Verification of the procedure was carried out by determining the Curie temperature of nickel and comparing it with data obtained by other methods. We established the dependence of the Curie temperature of nickel on the carbon content and determined the Curie temperatures for alloys of Fe-Cr and Fe-Ni systems. Using numerical modeling and experimental data, temperature dependences of the relative magnetic permeability of materials were obtained. The results show the presence of the Hopkinson effect in the materials under study and the presence of inflection points on the electrical resistance curves.

THERMAL FIELD IN A HORIZONTAL WELL APPLIED TO THE DETERMINATION OF FLUID FLOW BY ACTIVE THERMOMETRY

Today, in the context of falling oil production and increasing water cut, the importance of geophysical control over field development is increasing. A promising method of production logging is active thermometry, it is based on the creation of a thermal disturbance area in the wellbore, for example, due to induction heating of a section of a metal pipe (liner or casing, depending on the design of the well). As a result of heat exchange with a locally heated pipe section, heat marks are formed in the liquid, moving along the wellbore. The article presents the results of physical modeling of thermal processes during local induction heating of a section of a horizontal well. It has been experimentally established that with an induction heater power of about 1 kW and flow rates in the pipe up to 50 m3/day, the heating of the pipe wall reaches 12 K. As part of the experimental studies, the movement of heat marks was monitored using two modules of temperature sensors distributed over the pipe cross section. It is shown that the nature of temperature change in time is determined by the position of the temperature sensor in the pipe section. The greatest thermal anomalies are noted for sensors pressed against the pipe in its upper part, the smallest - for sensors located in the lower part of the pipe. The fluid flow rate in the pipe was estimated from the rate of passage of the heat mark between the temperature modules. It is shown that the calculated flow rate is overestimated relative to the actual one due to the influence of natural thermal convection, which causes the occurrence of a natural convective fluid flow in addition to the forced movement with a given flow rate. A new analytical solution has been obtained for calculating the dynamics of the pipe temperature in the induction heating section, a comparison of the results of calculations using the analytical model with the experimental results showed good agreement. The results of experimental studies can be used in interpreting the results of field logging wells using active thermometry, in particular, the sensitivity of the pipe temperature in the induction heating section to the flow rate can be used to solve inverse problems of estimating the flow rate in a pipe by measuring its surface temperature using the obtained analytical solution.

Применение научной визуализации в моделировании низкотемпературной газоразрядной плазмы

This article discusses the importance of developing software and hardware complexes for data visualization and improving methods of presenting them in the modeling of low-temperature gas discharge plasma phenomena and related physical processes. In particular, issues related to creating a specialized distributed environment for solving gas discharge modeling tasks are considered. The use of computer graphics for visualization has allowed for a visual analysis of the obtained data and making necessary adjustments to the modeling process interactively with the data. The paper presents the results of visualizing a model of mercury-argon plasma in a coaxial microwave discharge. The application of local cross-sections of the computational domain for visualization has revealed the internal structure and peculiarities of the distribution of the electric field and electron concentration in the discharge tube. The obtained data served as the basis for creating an experimental prototype of a coaxial gas discharge optical radiation source.

Self-Similar Solution to the Problem of Unsteady Film Condensation on a Vertical Semi-Infinite Plate

Changes in the regimes of condensate film flow along the underlying surface in the presence of a body force are considered within the framework of a simplified physical and mathematical model of hydrodynamic and thermal processes occurring under unsteady film condensation on a vertical semi-infinite plate. The model is used to determine the applicability conditions of the zero-gravity approximation when considering film condensation. It is found that the validity of using the zero-gravity approximation to calculate the film thickness growth rate on any plate section depends not only on the magnitude of the body force, but also on time and distance between this section and the leading edge of the plate.

Perspectives of computational fluid dynamics methods in the study of membrane processes

In the mathematical modeling of membrane processes, the study of the structural features of the membranes used and the significant limitation of information in the formal description of their separation properties led to the development of physical models that take into account not only the structural features of real membranes, but also their functioning features. When compiling physical models of membrane processes, it is impossible to objectively carry out a quantitative accounting of most factors due to their great diversity and variability, which distances the mathematical model far from the real process. This is why CFD methods reliably and efficiently perform calculations for all physical models and types, including steady or transient flow, incompressible or compressible flow (from small subsonic to hypersonic), laminar or turbulent flow simulations, Newtonian or non-Newtonian fluids, ideal or real gas . The authors analyzed the possibility of using CFD to calculate the hydrodynamics of flows in a membrane bioreactor based on hollow fibers. Safarov R.R. etc., an electronic geometric model of the installation was built, mesh geometry with different densities was selected to optimize the calculation time and solution accuracy for a specific case, the kinetic dependence of cell growth was calculated, the flow rates of the nutrient medium into the intrafiber and interfiber spaces of the bioreactor were determined, and the hydrodynamic conditions were analyzed. All of the above confirms the prospects for using CFD methods for modeling membrane processes complicated by culturing cells on the surface of membranes.

AI‐enhanced iterative solvers for accelerating the solution of large‐scale parametrized systems

SummaryRecent advances in the field of machine learning open a new era in high performance computing for challenging computational science and engineering applications. In this framework, the use of advanced machine learning algorithms for the development of accurate and cost‐efficient surrogate models of complex physical processes has already attracted major attention from scientists. However, despite their powerful approximation capabilities, surrogate model predictions are still far from being near to the ‘exact’ solution of the problem. To address this issue, the present work proposes the use of up‐to‐date machine learning tools in order to equip a new generation of iterative solvers of linear equation systems, capable of very efficiently solving large‐scale parametrized problems at any desired level of accuracy. The proposed approach consists of the following two steps. At first, a reduced set of model evaluations is performed using a standard finite element methodology and the corresponding solutions are used to establish an approximate mapping from the problem's parametric space to its solution space using a combination of deep feedforward neural networks and convolutional autoencoders. This mapping serves as a means of obtaining very accurate initial predictions of the system's response to new query points at negligible computational cost. Subsequently, an iterative solver inspired by the Algebraic Multigrid method in combination with Proper Orthogonal Decomposition, termed POD‐2G, is developed that successively refines the initial predictions of the surrogate model towards the exact solution. The application of POD‐2G as a standalone solver or as preconditioner in the context of preconditioned conjugate gradient methods is demonstrated on several numerical examples of large scale systems, with the results indicating its strong superiority over conventional iterative solution schemes.

Mathematical Simulation in Nuclear Medicine for Optimization Diagnostic Accuracy of SPECT/CT

Purpose: To develop the method of mathematical simulation in the field of nuclear medicine and its
 practical application in research aimed at improving the diagnostic accuracy of the SPECT/CT method.
 The basic principles of the method of mathematical simulation in nuclear medicine and the main modules of the software package “Virtual Platform for Simulation Tests of the SPECT/CT Method”, created
 at the laboratory for simulation in nuclear medicine of Novosibirsk State University and the Institute of
 Theoretical and Applied Mechanics.
 Material and methods: The main principles of the developed software package are the realism of the ‘virtual patient’ mathematical model, the accuracy in modeling of physical processes in visualization, as
 well as simulation conducting close to clinical practice. All studies were carried out in collaboration
 with clinicians. The software complex was verified by comparison with clinical data. Numerical experiments have shown a close correspondence between the results of clinical and virtual studies. In simulation tests, the same errors were obtained on images that were observed on clinical images. Simulation
 computer tests were carried out using the software package “Virtual Platform...” in the field of nuclear
 oncology, cardiology and neurology, aimed at studying the accuracy of images of pathological foci to assess the possibility of switching to quantitative SPECT, as well as optimizing the protocol for examining
 patients.
 Results: Simulation tests have shown that in order to move to quantitative SPECT, it is not enough to be
 limited to the development of a methodology for calibrating SPECT systems for a particular radionuclide. There are problems without understanding and solving which it is impossible to talk about the diagnostic accuracy of the quantitative SPECT method. Such problems are edge artifacts that appear on
 the images of pathological foci, and the rule of stopping the iterative algorithm when the values of activity in the area of interest (pathological focus) that are closest to the true values are reached. A stopping
 criterion based on Pearson's modified chi-square test of goodness of fit is proposed. There is a significantly good correlation between the proposed stop criterion and the minimum RMS error of the image
 reconstruction. The results of simulation modeling with the aim of optimizing SPECT examinations of
 brain perfusion demonstrated the possibility of reducing the data recording time compared to the standard protocol by at least two times.
 Conclusion: The computer simulation method presented in this paper is a practical technology that
 contributes to the optimization and development of a quantitative SPECT method to achieve the best
 possible results in the imaging of pathological foci. Further development of the software package is focused on applications in radionuclide therapy and theranostics.

DES Y3 cosmic shear down to small scales: Constraints on cosmology and baryons

We present the first analysis of cosmic shear measured in DES Y3 that employs the entire range of angular scales in the data. To achieve this, we built upon recent advances in the theoretical modelling of weak lensing provided by a combination of N-body simulations, physical models of baryonic processes, and neural networks. Specifically, we used BACCOemu to model the linear and non-linear matter power spectrum including baryonic physics, allowing us to robustly exploit scales smaller than those used by the DES Collaboration. We show that the additional data produce cosmological parameters that are tighter but consistent with those obtained from larger scales, while also constraining the distribution of baryons. In particular, we measured the mass scale at which haloes have lost half of their gas, log Mc = 14.38−0.56+0.60 log(h−1 M⊙), and a parameter that quantifies the weighted amplitudes of the present-day matter inhomogeneities, S8 = 0.799−0.015+0.023. Our constraint on S8 is statistically compatible with that inferred from the Planck satellite data at the 0.9σ level. We find instead a 1.4σ shift in comparison to that from the official DES Y3 cosmic shear, because of different choices in the modelling of intrinsic alignment, non-linearities, baryons, and lensing shear ratios. We conclude that small scales in cosmic shear data contain valuable astrophysical and cosmological information and thus should be included in standard analyses.

Comparison of damping techniques in non-linear spring-mass systems for power transformers under short-circuit condition

PurposeThe simplified modeling of many physical processes results in a second-order ordinary differential equation (ODE) system. Often the damping of these resonating systems cannot be defined in the same simplified way as the other parameters due to the complexity of the physical effects. The purpose of this paper is to develop a mathematically stable approach for damping resonances in nonlinear ODE systems.Design/methodology/approachModifying the original ODE using the eigenvalues and eigenvectors of a linearized state leads to satisfying results.FindingsAn iterative approach is presented, how to modify the original ODE, to achieve a well-damped solution.Practical implicationsThe method can be applied for every physical resonating system, where the model complexity prevents the determination of the damping.Originality/valueThe iterative algorithm to modify the original ODE is novel. It can be used on different fields of the physics, where a second-order ODE is describing the problem, which has only measured or empirical damping.

METHODS FOR CALCULATING THE THERMAL AND STRESS-STRAIN CONDITIONS OF THE MAIN COMBUSTION CHAMBERS FLAME TUBES

Large-scale russian aggression has created a number of new and critical challenges in the field of security and defense. The growing number of emerging tasks, and at the same time the need for greater efficiency in solving them, determine the need to update and implement rational ways to maintain the serviceability of the required number of aircraft, taking into account their own and international experience.
 Thus, the development of a scientific and methodological apparatus for modeling physical processes that occur in resource-limiting parts and assembly units of aircraft engines, regarding their impact on the durability of the material in the process of operating factors, is an urgent scientific task. At the same time, it is taken into account that absolutely every engine loading cycle during flight or ground testing corresponds to a certain proportion of damage to its components, which determines a certain quantitative measure of their exhaustion of the resource.
 The article proposes a methodology for calculating the thermal stress-strain states of the flame tubes of the main combustion chambers. The objectivity and accuracy of the calculations is determined by the reliability of the boundary conditions required to solve the non-stationary thermal conductivity equation. The proposed technique allows to take into account the distribution of temperature fields obtained due to numerical modeling of the working process in the main modes of engine operation.

Physics-Informed Neural Networks for the Heat Equation with Source Term under Various Boundary Conditions

Modeling of physical processes as partial differential equations (PDEs) is often carried out with computationally expensive numerical solvers. A common, and important, process to model is that of laser interaction with biological tissues. Physics-informed neural networks (PINNs) have been used to model many physical processes, though none have demonstrated an approximation involving a source term in a PDE, which modeling laser-tissue interactions requires. In this work, a numerical solver for simulating tissue interactions with lasers was surrogated using PINNs while testing various boundary conditions, one with a radiative source term involved. Models were tested using differing activation function combinations in their architectures for comparison. The best combinations of activation functions were different for cases with and without a source term, and R2 scores and average relative errors for the predictions of the best PINN models indicate that it is an accurate surrogate model for corresponding solvers. PINNs appear to be valid replacements for numerical solvers for one-dimensional tissue interactions with electromagnetic radiation.