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Modelling, Volume 5, Issue 4 (December 2024) – 18 articles

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32 pages, 1410 KiB  
Article
Modeling the Production of Nanoparticles via Detonation—Application to Alumina Production from ANFO Aluminized Emulsions
by Pedro M. S. Santos, Belmiro P. M. Duarte, Nuno M. C. Oliveira, Ricardo A. L. Mendes, José L. S. A. Campos and João M. C. Silva
Modelling 2024, 5(4), 1642-1673; https://doi.org/10.3390/modelling5040086 - 7 Nov 2024
Viewed by 83
Abstract
This paper investigates the production of nanoparticles via detonation. To extract valuable knowledge regarding this route, a phenomenological model of the process is developed and simulated. This framework integrates the mathematical description of the detonation with a model representing the particulate phenomena. The [...] Read more.
This paper investigates the production of nanoparticles via detonation. To extract valuable knowledge regarding this route, a phenomenological model of the process is developed and simulated. This framework integrates the mathematical description of the detonation with a model representing the particulate phenomena. The detonation process is simulated using a combination of a thermochemical code to determine the Chapman–Jouguet (C-J) conditions, coupled with an approximate spatially homogeneous model that describes the radial expansion of the detonation matrix. The conditions at the C-J point serve as initial conditions for the detonation dynamic model. The Mie–Grüneisen Equation of State (EoS) is used, with the “cold curve” represented by the Jones–Wilkins–Lee Equation of State. The particulate phenomena, representing the formation of metallic oxide nanoparticles from liquid droplets, are described by a Population Balance Equation (PBE) that accounts for the coalescence and coagulation mechanisms. The variables associated with detonation dynamics interact with the kernels of both phenomena. The numerical approach employed to handle the PBE relies on spatial discretization based on a fixed-pivot scheme. The dynamic solution of the models representing both processes is evolved with time using a Differential-Algebraic Equation (DAE) implicit solver. The strategy is applied to simulate the production of alumina nanoparticles from Ammonium Nitrate Fuel Oil aluminized emulsions. The results show good agreement with the literature and experience-based knowledge, demonstrating the tool’s potential in advancing understanding of the detonation route. Full article
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24 pages, 1143 KiB  
Article
Machine Learning-Based Optimization Models for Defining Storage Rules in Maritime Container Yards
by Daniela Ambrosino and Haoqi Xie
Modelling 2024, 5(4), 1618-1641; https://doi.org/10.3390/modelling5040085 (registering DOI) - 5 Nov 2024
Viewed by 229
Abstract
This paper proposes an integrated approach to define the best consignment strategy for storing containers in an export yard of a maritime terminal. The storage strategy identifies the rules for grouping homogeneous containers, which are defined simultaneously with the assignment of each group [...] Read more.
This paper proposes an integrated approach to define the best consignment strategy for storing containers in an export yard of a maritime terminal. The storage strategy identifies the rules for grouping homogeneous containers, which are defined simultaneously with the assignment of each group of containers to the available blocks (bay-locations) in the yard. Unlike recent literature, this study focuses specifically on weight classes and their respective limits when establishing the consignment strategy. Another novel aspect of this work is the integration of a data-driven algorithm and operations research. The integrated approach is based on unsupervised learning and optimization models and allows us to solve large instances within a few seconds. Results obtained by spectral clustering are treated as input datasets for the optimization models. Two different formulations are described and compared: the main difference lies in how containers are assigned to bay-locations, shifting from a time-consuming individual container assignment to the assignment of groups of containers, which offers significant advantages in computational efficiency. Experimental tests are organized into three campaigns to evaluate the following: (i) The computational time and solution quality (i.e., space utilization) of the proposed models; (ii) The performance of these models against a benchmark model; (iii) The practical effectiveness of the proposed solution approach. Full article
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17 pages, 12404 KiB  
Article
Predicting Cyclist Speed in Urban Contexts: A Neural Network Approach
by Ricardo Montoya-Zamora, Luisa Ramírez-Granados, Teresa López-Lara, Juan Bosco Hernández-Zaragoza and Rosario Guzmán-Cruz
Modelling 2024, 5(4), 1601-1617; https://doi.org/10.3390/modelling5040084 - 5 Nov 2024
Viewed by 252
Abstract
Bicycle use has become more important today, but more information and planning models are needed to implement bike lanes that encourage cycling. This study aimed to develop a methodology to predict the speed a cyclist can reach in an urban environment and to [...] Read more.
Bicycle use has become more important today, but more information and planning models are needed to implement bike lanes that encourage cycling. This study aimed to develop a methodology to predict the speed a cyclist can reach in an urban environment and to provide information for planning cycling infrastructure. The methodology consisted of obtaining GPS data on longitude, latitude, elevation, and time from a smartphone of two groups of cyclists to calculate the speeds and slopes through a model based on a recurrent short-term memory (LSTM) type neural network. The model was trained on 70% of the dataset, with the remaining 30% used for validation and varying training epochs (100, 200, 300, and 600). The effectiveness of recurrent neural networks in predicting the speed of a cyclist in an urban environment is shown with determination coefficients from 0.77 to 0.96. Average cyclist speeds ranged from 6.1 to 20.62 km/h. This provides a new methodology that offers valuable information for various applications in urban transportation and bicycle line planning. A limitation can be the variability in GPS device accuracy, which could affect speed measurements and the generalizability of the findings. Full article
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19 pages, 7375 KiB  
Article
Squirrel Cage Induction Motors Accurate Modelling for Digital Twin Applications
by Adamou Amadou Adamou, Chakib Alaoui, Mouhamadou Moustapha Diop and Adam Skorek
Modelling 2024, 5(4), 1582-1600; https://doi.org/10.3390/modelling5040083 - 22 Oct 2024
Viewed by 544
Abstract
The ongoing industrial revolution emphasizes the importance of precise machinery monitoring. Among these machines, induction motors (IMs) stand out due to their large numbers, which imply a significant part of industrial energy consumption. To achieve accurate in-service IM monitoring, robust modelling is required, [...] Read more.
The ongoing industrial revolution emphasizes the importance of precise machinery monitoring. Among these machines, induction motors (IMs) stand out due to their large numbers, which imply a significant part of industrial energy consumption. To achieve accurate in-service IM monitoring, robust modelling is required, with a particular emphasis on in situ constraints. In this study, we create a precise digital model for squirrel cage induction motors (SCIMs) that can be used in Industry 4.0 digital twin applications. To achieve this, we survey the existing literature, describe the main modelling techniques, identify the best models in terms of ease of implementation, and ensure the accuracy of our digital representation. We develop four methods, namely finite element analysis (FEA), thermal modelling, circuit-based models, and quantum-based fuzzy logic control, as a crucial first step in implementing digital twin (DT) technology for IMs. The quantum fuzzy logic is based on the transition from classical equations to the quantum equation determining the speed of the motor in the quantum world by passing through the Schrödinger equation. We propose the DT level of integration architecture for IMs based on the industry 4.0 reference architecture model. Finally, the main tools used to successfully implement DT for IMs are revealed. Full article
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14 pages, 2765 KiB  
Article
Statistical Modeling and Probable Calculation of the Strength of Materials with Random Distribution of Surface Defects
by Roman Kvit, Petro Pukach, Tetyana Salo and Myroslava Vovk
Modelling 2024, 5(4), 1568-1581; https://doi.org/10.3390/modelling5040082 - 19 Oct 2024
Viewed by 372
Abstract
Based on the solutions of deterministic fracture mechanics and the methods of probability theory, the algorithm for calculating the probabilistic strength characteristics of plate elements of structures with an arbitrary stochastic distribution of surface defects is outlined. On the plate surface, there are [...] Read more.
Based on the solutions of deterministic fracture mechanics and the methods of probability theory, the algorithm for calculating the probabilistic strength characteristics of plate elements of structures with an arbitrary stochastic distribution of surface defects is outlined. On the plate surface, there are uniformly distributed cracks that do not interact with each other, the plane of which is normal to the surface, and the depth is much less than its length on the surface. The cracks’ depth and angle of orientation are random values, and their joint distribution density is specified. Plates made of this material are under the influence of biaxial loading. The probability of failure, along with the mean value, the dispersion, and the variation coefficient of the plate’s strength, taking into account the surface defects under different types of stress, were determined. Their dependence on the type of loading, the size of the plate, and the surface structural heterogeneity of the material were studied graphically. Joint consideration of the influence of the interrelated properties of real materials, such as defectiveness and stochasticity, on strength and fracture, opens up new opportunities in creating a theory of strength and fracture of deformable solids. Full article
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18 pages, 7447 KiB  
Article
Modeling and Simulation of Material Type Effects on the Mechanical Behavior of Crankshafts in Internal Combustion Engines
by Hasan Mhd Nazha, Muhsen Adrah, Thaer Osman, Maysaa Shash and Daniel Juhre
Modelling 2024, 5(4), 1550-1567; https://doi.org/10.3390/modelling5040081 - 19 Oct 2024
Viewed by 436
Abstract
This research aims to study the mechanical behavior of the materials most commonly used in crankshaft manufacturing by designing a four-piston crankshaft, analyzing the stresses and displacements resulting from the applied load, and determining vibration frequencies. Additionally, this study examines the thermal behavior [...] Read more.
This research aims to study the mechanical behavior of the materials most commonly used in crankshaft manufacturing by designing a four-piston crankshaft, analyzing the stresses and displacements resulting from the applied load, and determining vibration frequencies. Additionally, this study examines the thermal behavior of the crankshaft. For this purpose, a three-dimensional model of the crankshaft was designed using CATIA V5 R18 software, and finite element analysis was subsequently performed using ANSYS 2019 R1 software under static, dynamic, and thermal conditions with four different materials in various orientations. To verify the effectiveness of the proposed design, it was compared with a reference design in terms of stresses and displacements. This study also explores improvements in crankshaft geometry and shape. The results indicate that selecting the appropriate material for the working conditions and optimizing the geometry and shape enhance engine performance and reduce the crankshaft’s weight by 20%. The findings were validated by comparing the designs, which support increased productivity and improved durability. Full article
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18 pages, 883 KiB  
Article
Physics-Informed Neural Network for Solving a One-Dimensional Solid Mechanics Problem
by Vishal Singh, Dineshkumar Harursampath, Sharanjeet Dhawan, Manoj Sahni, Sahaj Saxena and Rajnish Mallick
Modelling 2024, 5(4), 1532-1549; https://doi.org/10.3390/modelling5040080 - 18 Oct 2024
Viewed by 663
Abstract
Our objective in this work is to demonstrate how physics-informed neural networks, a type of deep learning technology, can be utilized to examine the mechanical properties of a helicopter blade. The blade is regarded as a one-dimensional prismatic cantilever beam that is exposed [...] Read more.
Our objective in this work is to demonstrate how physics-informed neural networks, a type of deep learning technology, can be utilized to examine the mechanical properties of a helicopter blade. The blade is regarded as a one-dimensional prismatic cantilever beam that is exposed to triangular loading, and comprehending its mechanical behavior is of utmost importance in the aerospace field. PINNs utilize the physical information, including differential equations and boundary conditions, within the loss function of the neural network to approximate the solution. Our approach determines the overall loss by aggregating the losses from the differential equation, boundary conditions, and data. We employed a physics-informed neural network (PINN) and an artificial neural network (ANN) with equivalent hyperparameters to solve a fourth-order differential equation. By comparing the performance of the PINN model against the analytical solution of the equation and the results obtained from the ANN model, we have conclusively shown that the PINN model exhibits superior accuracy, robustness, and computational efficiency when addressing high-order differential equations that govern physics-based problems. In conclusion, the study demonstrates that PINN offers a superior alternative for addressing solid mechanics problems with applications in the aerospace industry. Full article
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13 pages, 623 KiB  
Technical Note
The Influence of Harmonic Content on the RMS Value of Electromagnetic Fields Emitted by Overhead Power Lines
by Jozef Bendík, Matej Cenký and Žaneta Eleschová
Modelling 2024, 5(4), 1519-1531; https://doi.org/10.3390/modelling5040079 - 16 Oct 2024
Viewed by 401
Abstract
This paper investigates the influence of harmonic content on the root mean square value of electromagnetic fields emitted by overhead power lines. The paper presents a methodology to assess the intensity of electric field and magnetic flux density, incorporating both fundamental frequencies and [...] Read more.
This paper investigates the influence of harmonic content on the root mean square value of electromagnetic fields emitted by overhead power lines. The paper presents a methodology to assess the intensity of electric field and magnetic flux density, incorporating both fundamental frequencies and harmonics. The results of our calculations indicate that harmonic distortion in current waveforms can significantly increase the RMS value of magnetic flux density but its effect on electric field intensity is minimal. Additionally, our findings highlight a potential increase in induced voltages on buried or overhead steel pipelines in the vicinity of OPLs, which could pose risks such as pipeline damage and increased corrosion. This underscores the importance of considering harmonic content in EMF exposure evaluations to address both health risks and potential infrastructure impacts comprehensively. Effective harmonic management and rigorous infrastructure monitoring are essential to prevent potential hazards and ensure the reliability of protective systems. Full article
(This article belongs to the Topic EMC and Reliability of Power Networks)
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14 pages, 2841 KiB  
Article
Improving Patient Experience in Outpatient Clinics through Simulation: A Case Study
by Abdullah Alrabghi and Abdullah Tameem
Modelling 2024, 5(4), 1505-1518; https://doi.org/10.3390/modelling5040078 - 15 Oct 2024
Viewed by 456
Abstract
This research aims to present a case study on the use of simulation to support operational decision-making and improve the patient experience in outpatient clinics. A simulation model was developed to represent patient flow through the endocrine clinics of the internal medicine department [...] Read more.
This research aims to present a case study on the use of simulation to support operational decision-making and improve the patient experience in outpatient clinics. A simulation model was developed to represent patient flow through the endocrine clinics of the internal medicine department in a large hospital in Saudi Arabia. The research evaluated the impact of using simulation models on different aspects of healthcare facility operations, such as patient flow, resource utilization, and staffing. Potential bottlenecks and inefficiencies in the clinic’s processes were identified. Furthermore, improvements were suggested and evaluated that could significantly reduce patient waiting times and increase the number of patients served. Different scenarios and strategies were evaluated without the need for real-world implementation, which can be costly and time consuming. The model can also be easily modified and adapted to accommodate changes in patient demand, staffing levels, or other factors that may impact clinic operations. The findings demonstrate the utility of simulation models in healthcare management. Overall, the use of simulation models in healthcare management has the potential to revolutionize the way clinics and hospitals operate, leading to improved patient outcomes and more efficient use of resources. Full article
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15 pages, 1496 KiB  
Article
Modeling of a Fluid with Pressure-Dependent Viscosity in Hele-Shaw Flow
by Benedetta Calusi and Liviu Iulian Palade
Modelling 2024, 5(4), 1490-1504; https://doi.org/10.3390/modelling5040077 - 9 Oct 2024
Viewed by 448
Abstract
We investigate the Hele-Shaw flow of fluids whose viscosity depends on pressure, i.e., piezo-viscous fluids, near the tip of a sharp edge. In particular, we consider both cases of two-dimensional symmetric and antisymmetric flows. To obtain the pressure field, we provide a procedure [...] Read more.
We investigate the Hele-Shaw flow of fluids whose viscosity depends on pressure, i.e., piezo-viscous fluids, near the tip of a sharp edge. In particular, we consider both cases of two-dimensional symmetric and antisymmetric flows. To obtain the pressure field, we provide a procedure that is based on the method of separation of variables and does not depend on a specific choice of the expression for the pressure-dependent viscosity. Therefore, we show the existence of a general procedure to investigate the behavior of piezo-viscous fluids in Hele-Shaw flow and its solution near a sharp corner. The results are applied to the case of an exponential dependence of viscosity on pressure as an example of exact solutions for the pressure field. Full article
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21 pages, 2103 KiB  
Article
On the Utilization of Emoji Encoding and Data Preprocessing with a Combined CNN-LSTM Framework for Arabic Sentiment Analysis
by Hussam Alawneh, Ahmad Hasasneh and Mohammed Maree
Modelling 2024, 5(4), 1469-1489; https://doi.org/10.3390/modelling5040076 - 7 Oct 2024
Viewed by 655
Abstract
Social media users often express their emotions through text in posts and tweets, and these can be used for sentiment analysis, identifying text as positive or negative. Sentiment analysis is critical for different fields such as politics, tourism, e-commerce, education, and health. However, [...] Read more.
Social media users often express their emotions through text in posts and tweets, and these can be used for sentiment analysis, identifying text as positive or negative. Sentiment analysis is critical for different fields such as politics, tourism, e-commerce, education, and health. However, sentiment analysis approaches that perform well on English text encounter challenges with Arabic text due to its morphological complexity. Effective data preprocessing and machine learning techniques are essential to overcome these challenges and provide insightful sentiment predictions for Arabic text. This paper evaluates a combined CNN-LSTM framework with emoji encoding for Arabic Sentiment Analysis, using the Arabic Sentiment Twitter Corpus (ASTC) dataset. Three experiments were conducted with eight-parameter fusion approaches to evaluate the effect of data preprocessing, namely the effect of emoji encoding on their real and emotional meaning. Emoji meanings were collected from four websites specialized in finding the meaning of emojis in social media. Furthermore, the Keras tuner optimized the CNN-LSTM parameters during the 5-fold cross-validation process. The highest accuracy rate (91.85%) was achieved by keeping non-Arabic words and removing punctuation, using the Snowball stemmer after encoding emojis into Arabic text, and applying Keras embedding. This approach is competitive with other state-of-the-art approaches, showing that emoji encoding enriches text by accurately reflecting emotions, and enabling investigation of the effect of data preprocessing, allowing the hybrid model to achieve comparable results to the study using the same ASTC dataset, thereby improving sentiment analysis accuracy. Full article
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15 pages, 4416 KiB  
Article
A Novel Application of Computational Contact Tools on Nonlinear Finite Element Analysis to Predict Ground-Borne Vibrations Generated by Trains in Ballasted Tracks
by Andrés García Moreno, Antonio Alonso López, María G. Carrasco García, Ignacio J. Turias and Juan Jesús Ruiz Aguilar
Modelling 2024, 5(4), 1454-1468; https://doi.org/10.3390/modelling5040075 - 7 Oct 2024
Viewed by 674
Abstract
Predictive numerical models in the study of ground-borne vibrations generated by railway systems have traditionally relied on the subsystem partition approach (segmented). In such a method, loads are individually applied, and the cumulative effect of the rolling stock is obtained through superposition. While [...] Read more.
Predictive numerical models in the study of ground-borne vibrations generated by railway systems have traditionally relied on the subsystem partition approach (segmented). In such a method, loads are individually applied, and the cumulative effect of the rolling stock is obtained through superposition. While this method serves to mitigate computational costs, it may not fully capture the complex interactions involved in ground-borne vibrations—especially in the frequency domain. Recent advancements in computation and software have enabled the development of more sophisticated vibrational contamination prediction models that encompass the entire dynamics of the system, from the rolling stock to the terrain, allowing continuous simulations with a defined time step. Furthermore, the incorporation of computational contact mechanics tools between various elements not only ensures accuracy in the time domain but also extends the analysis into the frequency domain. In this novel approach, the segmented models are shifted to continuous simulations where the nonlinear problem of a rigid–flexible multibody system is fully considered. The model can predict the impact of a high-speed rail (HSR) vehicle passing, capturing the key intricacies of ground-borne vibrations and their impact on the surrounding environment due to a deeper comprehension of the occurrences in the frequency domain. Full article
(This article belongs to the Special Issue Finite Element Simulation and Analysis)
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19 pages, 937 KiB  
Article
Acausal Fuel Cell Simulation Model for System Integration Analysis in Early Design Phases
by Leonardo Cavini, Susan Liscouët-Hanke and Nicole Viola
Modelling 2024, 5(4), 1435-1453; https://doi.org/10.3390/modelling5040074 - 6 Oct 2024
Viewed by 660
Abstract
Hydrogen technologies have the potential to reduce aviation’s CO2 emissions but come with many challenges. This paper introduces a scalable hydrogen fuel cell model tailored for system integration analysis in early aircraft design phases. The model focuses on Proton Exchange Membrane Fuel [...] Read more.
Hydrogen technologies have the potential to reduce aviation’s CO2 emissions but come with many challenges. This paper introduces a scalable hydrogen fuel cell model tailored for system integration analysis in early aircraft design phases. The model focuses on Proton Exchange Membrane Fuel Cells (PEMFCs) and is based on thermodynamic equations and empirical data to simulate performance under different ambient and operating conditions; it also includes a simplified model of the Balance of Plant (BOP) systems and is implemented in OpenModelica. The model performance is validated through a comparison of the simulated polarization curves with real datasheet data. A case study highlights the peculiarities of this model by studying the sizing of the fuel cell stacks for a modified ATR 72 aircraft. The developed model effectively supports the early design exploration of the aircraft with a greater level of detail for system integration studies, essential to better explore the potential of aircraft featuring hydrogen-based power systems. Full article
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22 pages, 3573 KiB  
Article
The Estimating Parameter and Number of Knots for Nonparametric Regression Methods in Modelling Time Series Data
by Autcha Araveeporn
Modelling 2024, 5(4), 1413-1434; https://doi.org/10.3390/modelling5040073 - 5 Oct 2024
Viewed by 465
Abstract
This research aims to explore and compare several nonparametric regression techniques, including smoothing splines, natural cubic splines, B-splines, and penalized spline methods. The focus is on estimating parameters and determining the optimal number of knots to forecast cyclic and nonlinear patterns, applying these [...] Read more.
This research aims to explore and compare several nonparametric regression techniques, including smoothing splines, natural cubic splines, B-splines, and penalized spline methods. The focus is on estimating parameters and determining the optimal number of knots to forecast cyclic and nonlinear patterns, applying these methods to simulated and real-world datasets, such as Thailand’s coal import data. Cross-validation techniques are used to control and specify the number of knots, ensuring the curve fits the data points accurately. The study applies nonparametric regression to forecast time series data with cyclic patterns and nonlinear forms in the dependent variable, treating the independent variable as sequential data. Simulated data featuring cyclical patterns resembling economic cycles and nonlinear data with complex equations to capture variable interactions are used for experimentation. These simulations include variations in standard deviations and sample sizes. The evaluation criterion for the simulated data is the minimum average mean square error (MSE), which indicates the most efficient parameter estimation. For the real data, monthly coal import data from Thailand is used to estimate the parameters of the nonparametric regression model, with the MSE as the evaluation metric. The performance of these techniques is also assessed in forecasting future values, where the mean absolute percentage error (MAPE) is calculated. Among the methods, the natural cubic spline consistently yields the lowest average mean square error across all standard deviations and sample sizes in the simulated data. While the natural cubic spline excels in parameter estimation, B-splines show strong performance in forecasting future values. Full article
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18 pages, 3575 KiB  
Article
Empirical Comparison of Forecasting Methods for Air Travel and Export Data in Thailand
by Somsri Banditvilai and Autcha Araveeporn
Modelling 2024, 5(4), 1395-1412; https://doi.org/10.3390/modelling5040072 - 2 Oct 2024
Viewed by 532
Abstract
Time series forecasting plays a critical role in business planning by offering insights for a competitive advantage. This study compared three forecasting methods: the Holt–Winters, Bagging Holt–Winters, and Box–Jenkins methods. Ten datasets exhibiting linear and non-linear trends and clear and ambiguous seasonal patterns [...] Read more.
Time series forecasting plays a critical role in business planning by offering insights for a competitive advantage. This study compared three forecasting methods: the Holt–Winters, Bagging Holt–Winters, and Box–Jenkins methods. Ten datasets exhibiting linear and non-linear trends and clear and ambiguous seasonal patterns were selected for analysis. The Holt–Winters method was tested using seven initial configurations, while the Bagging Holt–Winters and Box–Jenkins methods were also evaluated. The model performance was assessed using the Root-Mean-Square Error (RMSE) to identify the most effective model, with the Mean Absolute Percentage Error (MAPE) used to gauge the accuracy. Findings indicate that the Bagging Holt–Winters method consistently outperformed the other methods across all the datasets. It effectively handles linear and non-linear trends and clear and ambiguous seasonal patterns. Moreover, the seventh initial configurationdelivered the most accurate forecasts for the Holt–Winters method and is recommended as the optimal starting point. Full article
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20 pages, 6528 KiB  
Article
Specific Characteristics of Numerical Simulation of Mechatronic Systems with PWM-Controlled Drives
by Andrey Achitaev, Konstantin Timofeev, Konstantin Suslov, Yuri Kalachev and Yuri Shornikov
Modelling 2024, 5(4), 1375-1394; https://doi.org/10.3390/modelling5040071 - 1 Oct 2024
Viewed by 529
Abstract
This paper explores the features of numerical simulation used to analyze the dynamic behaviour of drives controlled by pulse-width modulators. Modern motor control systems commonly employ pulse-width modulation. Effective numerical modelling of such systems presents unique challenges because the models employed are continuous-event [...] Read more.
This paper explores the features of numerical simulation used to analyze the dynamic behaviour of drives controlled by pulse-width modulators. Modern motor control systems commonly employ pulse-width modulation. Effective numerical modelling of such systems presents unique challenges because the models employed are continuous-event and have hybrid behaviour due to the presence of nonlinear links with discontinuities of the first kind. Therefore, it is essential to have special integration methods with variable steps, which should be factored in when developing the model. This paper shows how these problems are solved when modelling an electric drive with a DC motor using the SimInTech software. Full article
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10 pages, 5003 KiB  
Communication
The Impact of the Polymer Layer Thickness in the Foundation Shim on the Stiffness of the Multi-Bolted Foundation Connection
by Rafał Grzejda
Modelling 2024, 5(4), 1365-1374; https://doi.org/10.3390/modelling5040070 - 26 Sep 2024
Viewed by 407
Abstract
Finite element modelling of multi-bolted foundation connections used for the foundation of heavy machinery or equipment is presented. Connections made using different types of shims, with particular emphasis on polymer–steel shims, are investigated. The stiffness characteristics for the adopted models of multi-bolted foundation [...] Read more.
Finite element modelling of multi-bolted foundation connections used for the foundation of heavy machinery or equipment is presented. Connections made using different types of shims, with particular emphasis on polymer–steel shims, are investigated. The stiffness characteristics for the adopted models of multi-bolted foundation connections at the installation stage are described and compared. It is shown that the use of polymer–steel shims can result in a significant improvement in the stiffness of a multi-bolted foundation connection compared to a connection with a polymer shim, and in achieving a multi-bolted foundation connection with a stiffness similar to that of a connection with a steel shim (at a sufficiently low polymer layer thickness). Full article
(This article belongs to the Section Modelling in Engineering Structures)
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26 pages, 10499 KiB  
Article
Novel Adaptive Hidden Markov Model Utilizing Expectation–Maximization Algorithm for Advanced Pipeline Leak Detection
by Omid Zadehbagheri, Mohammad Reza Salehizadeh, Seyed Vahid Naghavi, Mazda Moattari and Behzad Moshiri
Modelling 2024, 5(4), 1339-1364; https://doi.org/10.3390/modelling5040069 - 24 Sep 2024
Viewed by 454
Abstract
In the oil industry, the leakage of pipelines containing hydrocarbon fluids causes significant environmental and economic damage. Recently, there has been a growing trend in employing data mining techniques for detecting leaks. Among these methods is the Hidden Markov Model, which, despite good [...] Read more.
In the oil industry, the leakage of pipelines containing hydrocarbon fluids causes significant environmental and economic damage. Recently, there has been a growing trend in employing data mining techniques for detecting leaks. Among these methods is the Hidden Markov Model, which, despite good results with stationary data, becomes inefficient when a leak causes a drop in the pressure or flow, reducing its accuracy. This paper presents an adaptive Hidden Markov method. Previous methods had low accuracy due to insufficient information for accurate leak detection. They often classified the size and location of leaks broadly. In contrast, the proposed model extracts hidden features to accurately identify the location and size of leaks, even in noisy conditions. Simulating a leak in a section of an oil pipeline in the Iranian Oil Export Corridor demonstrates the proposed method’s superiority over common methods like K-NN, SVM, Naive Bayes, and logistic regression. Full article
(This article belongs to the Topic Oil and Gas Pipeline Network for Industrial Applications)
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