Papers by Keyword: Modeling

Abstract: The research presented in this scientific paper focuses on modeling the dynamics of multicomponent systems with particles of different geometries using the GROMACS software package. Three main types of particles were analyzed in the study: spheres, ellipsoids, and plates, each of which has its own unique geometric characteristics that affect their behavior in the environment. The modeling allowed us to investigate the influence of particle shape on their diffusion, self-organization, and interaction between particles of different shapes. In particular, spherical particles, having an isotropic geometry, show the highest diffusion coefficient, since their symmetrical structure minimizes the resistance of the environment. This, in turn, makes them ideal for modeling simple interactions in liquids or colloids. Ellipsoidal particles, due to their anisotropy, have a slightly reduced diffusion coefficient, since their orientation in space affects the motion. Plates, which have a significant surface area relative to the volume, demonstrate the lowest diffusion rate, which is associated with a large interaction with the environment and the resistance created by their geometry. The results of the study also showed that the diffusion coefficient decreases with increasing particle size for all types. At the same time, spheres demonstrated the highest diffusion coefficient at the same size compared to other geometries, while plates have the lowest values ​​of this indicator. Analysis of the trajectories of particle motion in space using the GROMACS software allowed us to assess the influence of geometry on particle mobility. It was found that spheres exhibit the largest displacement amplitude, which indicates their high mobility and chaotic nature of the motion. Ellipsoids have a more stable motion with smaller displacements, which is associated with their geometric anisotropy. Plates, due to the large resistance of the environment, have the smallest displacements, which indicates limited mobility. It should be noted that the obtained research results open up opportunities for a deeper understanding of interactions in complex multicomponent systems and can be useful for further research in various fields. It is also worth noting that the comparison of different types of particles with different geometries and their influence on diffusion processes allowed us to obtain valuable information for improving models and practical applications in relevant fields of science and technology.

Abstract: The article considers the use of numerical methods in the SCILAB environment for modeling particle trajectories under the influence of various physical forces: gravity, electromagnetism and friction. The simulations conducted allowed us to study the dynamics of particle motion in three-dimensional space under various conditions, in particular the influence of forces on changing trajectories and stabilizing motion. The results obtained demonstrate the effectiveness of using the SCILAB software as a tool for numerical modeling of complex physical systems, which ensures the accuracy of calculations and clarity of visualization. It should also be noted that the use of such approaches allows us to study particle motion in various fields of science and technology, in particular in physics, engineering and systems analysis. Numerical methods implemented in SCILAB provide flexibility in taking into account the initial conditions and parameters of the system, opening up prospects for further research into complex interactions in multicomponent systems.

Abstract: The article discusses the application of the discrete element method (DEM) for modeling the behavior of spherical particles in granular media. Key aspects of particle contact interactions, including frictional forces, elasticity, coordination number, and the shape factor of spherical particles, are analyzed and investigated. It is worth noting that the proposed methodology enables the study of the mechanical properties of systems with particles of various sizes and compositions, as well as the modeling of their behavior in confined spaces and under dynamic influences. The modeling results demonstrate the high accuracy and versatility of the DEM for analyzing processes in bulk materials, particularly transportation, mixing, and granulation. The findings underscore the effectiveness of using DEM to solve complex problems and highlight prospects for its further improvement.

Abstract: The aim of the work was to determine the possibility of not taking into account the orientation (vertical or horizontal) of the studied elements of steel-reinforced concrete slabs with a corrugated profile during their heating in a modular small-sized fire furnace. The work investigated the temperature distributions on the outer surface of the corrugated ceiling profile of a steel-reinforced concrete slab of horizontal orientation simulated in the fire furnace chamber. To create geometric models of the fire furnace chamber and the studied element, a CAD software complex was used. To solve the heat engineering problem, mathematical (numerical) methods were used, based on solving systems of differential equations of continuous media such as the Navier-Stokes equation and the Fourier heat conductivity equation. According to the results obtained, the temperature distribution on the outer surface of the steel profile of the reinforced concrete slab is uniform, the temperature deviation in different places on the surface does not exceed 7 %. The maximum temperature on the heating surface of the steel profile of the reinforced concrete slab in the last minute of computer simulation reached 921 °С and the average temperature at this time over the entire surface of the structure was 917 °С. To determine the appropriate orientation of the test sample during fire tests, a comparison of the obtained temperature distributions on the outer surface of the corrugated profile of a horizontally placed reinforced concrete slab with the temperature distributions on the outer surface of the corrugated profile of a vertically placed reinforced concrete slab, which were given in the previous work was made. Analysis of the average surface temperatures of the corrugated profile of a reinforced concrete slab of horizontal and vertical orientation showed that the temperature distribution over the surface of the profile was uniform in both cases and the results obtained show good reproducibility of the experiment during computer simulation. And the orientation of the tested elements does not affect the temperature distribution over the outer surface of the corrugated profile of a reinforced concrete slab in the simulated furnace.

Abstract: This study aims to model lahar flow from Volcano Merapi in the Krasak River following the 2010 eruption. The spatial modeling results of lahar flow are used to identify and predict lahar hazard zone. The lahar flow modeling is conducted using the Laharz toolbox, utilizing DEMNAS data, and lahar volume scenarios based on historical lahar volume data for the Krasak River from 2011. Remote sensing data, specifically Sentinel-2 imagery, is used in this study with interpretation methods to derive river hydrology information, which serves as one of the validation measures for the Krasak River flow. The model is developed based on predetermined volume scenarios: Scenario I with an initial volume of 125.000 m³, Scenario II with doubled volume of 250.000 m³, Scenario III with lahar volume of 500.000 m³, and Scenario IV with lahar volume of 1.000.000 m³. The model validation is conducted using the Mount Merapi Disaster-Prone Area Map. The resulting model is applied to predict hazard zone using a buffer method along the river, with specific distances defined. The model results indicate that as the lahar volume scenario increases, the lahar flow model can impact the prediction of lahar hazard zone.

Abstract: In this research we investigate geometric analysis and computer-aided modeling of wire bending machines. This focus on the traditional and modern approaches to their understanding shows how CAD modeling, 3D scanning, and surface roughness measurements are used to understand their mechanisms. Analysis of wire bending mechanics provides a comprehensive evaluation of manufacturing methods and their effect on performance. The results and methods of design provide a direction for future improvements to the design and functionality of these machines for optimized simultaneous manufacturing and operational performance.

Abstract: Studies on the operation of Wind Power Plants related to the role of the control system are still relatively limited. The role of the control system is very important in the power conversion of power plants. To determine the effect of the power converter control system on the DFIG model wind power plant, modeling of the PLTB with DFIG is needed as well as a control system that can be used for simulations on the network or electric power system. The research thus aims to produce a wind power generation model with a DFIG generator and its control system that can optimally regulate power conversion in operations connected to the electricity grid. Several stages were carried out in this research consisting of literature review, preparation of tools for simulation using MATLAB/Simulink, DFIG modeling with the derivation of applicable equations, model simplification, control design, simulation and analysis. At this research stage, the results obtained are part of the research stages, namely obtaining a simplified DFIG modeling. This simplified DFIG model was obtained after formulating the mathematical equations of the DFIG equivalent circuit, deriving equations for the DFIG transient model and arranging the DFIG model in state space form. Furthermore, by simplifying the shape of the state space, the relationship between the stator and rotor of the DFIG is obtained.

Abstract: The research deals with the determination of the temperature distribution in a two-stage porous catalytic medium when the heat flow passes through. The peculiarity of the proposed model of heat and mass transfer in a porous catalyst is to consider the change in the volume of the spherical particle that makes up the catalyst.A program for calculating the temperature distribution in a two-scale porous structure of a catalyst made of spherical particles that change in volume with time has been developed. It should be noted that the temperature gradient is rather high, and the temperature in the central region of the particle becomes high enough for the process of catalytic reaction initiation only after 3.25 s. The developed program together with analytical and empirical studies allow to find the range of temperature and time of heat treatment at which the given thermophysical characteristics of porous material will be observed.The work will be useful for engineers and scientists studying the problems of thermochemical reactors and heat transfer in catalytic fills.

Abstract: In this scientific work, mathematical modeling of tetrahedron elements in the finite element method is presented, which includes the determination of geometric shape, shape functions, and material properties. Unknown fields such as displacement vectors, strain, and stress tensors are considered. The methodology of applying the principle of virtual work and equilibrium equations is described, allowing the derivation of a system of differential equations to describe the behavior of the tetrahedral element. Integration over the volume and consideration of boundary conditions help reduce the equations to a system of linear algebraic equations for numerical solution using the finite element method. It was found that modeling tetrahedral elements with a specific given radius (for example, R=0.3 mm) involves stages such as geometry determination, element generation, shape function formation, stiffness matrix computation, and solving a system of linear equations. The radius R of tetrahedral elements is taken into account at all stages, ensuring accuracy and reliability in tetrahedra modeling. The research also focuses on the fact that the occurrence of minor errors in iterative processes may result from several factors, including iteration step, the number of iterations, stopping criteria, linear or nonlinear material behavior, solution method selection, the presence of geometric inhomogeneities, and element size.

Abstract: In this study we analyzed the physical mechanisms governing time-dependent dielectric breakdown (TDDB) and we used TDDB physical model of dielectric breakdown, implemented in the defect-centric Ginestra® modeling platform, to deconvolute the intrinsic material properties effects and geometry feature impact on the gate oxide (GOx) and SiC-device breakdown.