Computation

11 pages, 2221 KiB

Open AccessArticle

Size-Dependent Switching in Thin Ferroelectric Films: Mathematical Aspects and Finite Element Simulation

by Elena Veselova, Anna Maslovskaya and Alexander Chebotarev

Computation 2023, 11(1), 14; https://doi.org/10.3390/computation11010014 - 15 Jan 2023

Cited by 2 | Viewed by 2104

The paper is devoted to the theoretical analysis and numerical implementation of a mathematical model of a nonlinear reaction–diffusion system on the COMSOL Multiphysics platform. The applied problem of the computer simulation of polarization switching in thin ferroelectric films is considered. The model [...] Read more.

The paper is devoted to the theoretical analysis and numerical implementation of a mathematical model of a nonlinear reaction–diffusion system on the COMSOL Multiphysics platform. The applied problem of the computer simulation of polarization switching in thin ferroelectric films is considered. The model is based on the Landau–Ginzburg–Devonshire–Khalatnikov thermodynamic approach and formalized as an initial-boundary value problem for a semilinear parabolic partial differential equation. The theoretical foundations of the model were explained. The user interface design application was developed with COMSOL Multiphysics. A series of computational experiments was performed to study the ferroelectric hysteresis and temperature dependences of polarization on the example of a ferroelectric barium titanate film. Full article

(This article belongs to the Special Issue Application of Finite Element Methods)

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27 pages, 1258 KiB

Open AccessArticle

HFCVO-DMN: Henry Fuzzy Competitive Verse Optimizer-Integrated Deep Maxout Network for Incremental Text Classification

by Gunjan Singh and Arpita Nagpal

Computation 2023, 11(1), 13; https://doi.org/10.3390/computation11010013 - 11 Jan 2023

Cited by 1 | Viewed by 2360

Abstract

One of the effectual text classification approaches for learning extensive information is incremental learning. The big issue that occurs is enhancing the accuracy, as the text is comprised of a large number of terms. In order to address this issue, a new incremental [...] Read more.

One of the effectual text classification approaches for learning extensive information is incremental learning. The big issue that occurs is enhancing the accuracy, as the text is comprised of a large number of terms. In order to address this issue, a new incremental text classification approach is designed using the proposed hybrid optimization algorithm named the Henry Fuzzy Competitive Multi-verse Optimizer (HFCVO)-based Deep Maxout Network (DMN). Here, the optimal features are selected using Invasive Weed Tunicate Swarm Optimization (IWTSO), which is devised by integrating Invasive Weed Optimization (IWO) and the Tunicate Swarm Algorithm (TSA), respectively. The incremental text classification is effectively performed using the DMN, where the classifier is trained utilizing the HFCVO. Nevertheless, the developed HFCVO is derived by incorporating the features of Henry Gas Solubility Optimization (HGSO) and the Competitive Multi-verse Optimizer (CMVO) with fuzzy theory. The proposed HFCVO-based DNM achieved a maximum TPR of 0.968, a maximum TNR of 0.941, a low FNR of 0.032, a high precision of 0.954, and a high accuracy of 0.955. Full article

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13 pages, 1070 KiB

Open AccessArticle

An Efficient Path Planning Algorithm Using a Potential Field for Ground Forces

by Nakyeong Sung, Suhwan Kim and Namsuk Cho

Computation 2023, 11(1), 12; https://doi.org/10.3390/computation11010012 - 11 Jan 2023

Cited by 2 | Viewed by 2316

Abstract

With the development and proliferation of unmanned weapons systems, path planning is becoming increasingly important. Existing path-planning algorithms mainly assume a well-known environment, and thus pre-planning is desirable, but the actual ground battlefield is uncertain, and numerous contingencies occur. In this study, we [...] Read more.

With the development and proliferation of unmanned weapons systems, path planning is becoming increasingly important. Existing path-planning algorithms mainly assume a well-known environment, and thus pre-planning is desirable, but the actual ground battlefield is uncertain, and numerous contingencies occur. In this study, we present a novel, efficient path-planning algorithm based on a potential field that quickly changes the path in a constantly changing environment. The potential field is composed of a set of functions representing enemy threats and a penalty term representing distance to the target area. We also introduce a new threat function using a multivariate skew-normal distribution that accurately expresses the enemy threat in ground combat. Full article

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13 pages, 2167 KiB

Open AccessArticle

Modified Kleene Star Algorithm Using Max-Plus Algebra and Its Application in the Railroad Scheduling Graphical User Interface

by Ema Carnia, Rinaldi Wilopo, Herlina Napitupulu, Nursanti Anggriani and Asep K. Supriatna

Computation 2023, 11(1), 11; https://doi.org/10.3390/computation11010011 - 9 Jan 2023

Cited by 2 | Viewed by 1671

Abstract

In max-plus algebra, some algorithms for determining the eigenvector of irreducible matrices are the power algorithm and the Kleene star algorithm. In this research, a modified Kleene star algorithm will be discussed to compensate for the disadvantages of the Kleene star algorithm. The [...] Read more.

In max-plus algebra, some algorithms for determining the eigenvector of irreducible matrices are the power algorithm and the Kleene star algorithm. In this research, a modified Kleene star algorithm will be discussed to compensate for the disadvantages of the Kleene star algorithm. The Kleene star algorithm’s time complexity is

O (n (n!))

, and the new Kleene star algorithm’s time complexity is

O (n^{4})

, while the power algorithm’s time complexity cannot be calculated. This research also applies max-plus algebra in a railroad network scheduling problem, constructing a graphical user interface to perform schedule calculations quickly and easily. Full article

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20 pages, 2850 KiB

Open AccessArticle

The Differential Evolution Algorithm for Solving the Problem of Size Selection and Location of Infectious Waste Incinerator

by Thitiworada Srisuwandee, Sombat Sindhuchao and Thitinon Srisuwandee

Computation 2023, 11(1), 10; https://doi.org/10.3390/computation11010010 - 8 Jan 2023

Cited by 5 | Viewed by 1888

Abstract

The disposal of infectious waste remains one of the most severe medical, social, and environmental problems in almost every country. Choosing the right location and arranging the most suitable transport route is one of the main issues in managing hazardous waste. Identifying a [...] Read more.

The disposal of infectious waste remains one of the most severe medical, social, and environmental problems in almost every country. Choosing the right location and arranging the most suitable transport route is one of the main issues in managing hazardous waste. Identifying a site for the disposal of infectious waste is a complicated process because both tangible and intangible factors must be considered together, and it also depends on various rules and regulations. This research aims to solve the problem of the size selection and location of infectious waste incinerators for 109 community hospitals in the upper part of northeastern Thailand by applying a differential evolution algorithm to solve the problem with the objective of minimizing the total system cost, which consists of the cost of transporting infectious waste, the fixed costs, and the variable cost of operating the infectious waste incinerator. The developed differential evolution produces vectors that differ from the conventional differential evolution. Instead of a single set of vectors, three are created to search for the solution. In addition to solving the problem of the case study, this research conducts numerical experiments with randomly generated data to measure the performance of the differential evolution algorithm. The results show that the proposed algorithm efficiently solves the problem and can find the global optimal solution for the problem studied. Full article

(This article belongs to the Special Issue Operations Research for Supply Chain Management)

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16 pages, 4736 KiB

Open AccessArticle

Improved Computational Prediction of the Electrochemical Reduction Potential of Twenty 3-Aryl-Quinoxaline-2-Carbonitrile 1,4-Di-N-Oxide Derivatives

by Shambhu Bhattarai, Pradeep Mareta, Philip W. Crawford, Jonathan M. Kessler and Christina M. Ragain

Computation 2023, 11(1), 9; https://doi.org/10.3390/computation11010009 - 7 Jan 2023

Cited by 1 | Viewed by 1503

Abstract

The ability of density functional theory (DFT) using the functional B3LYP with the cc-pVTZ basis set to accurately predict the electrochemical properties of 20 3-aryl-quinoxaline-2-carbonitrile 1,4-di-N-oxide derivatives in dimethylformamide (DMF) was investigated and compared to previous predictions from B3LYP/6-31G and B3LYP/lanl2dz. The B3LYP/cc-pVTZ [...] Read more.

The ability of density functional theory (DFT) using the functional B3LYP with the cc-pVTZ basis set to accurately predict the electrochemical properties of 20 3-aryl-quinoxaline-2-carbonitrile 1,4-di-N-oxide derivatives in dimethylformamide (DMF) was investigated and compared to previous predictions from B3LYP/6-31G and B3LYP/lanl2dz. The B3LYP/cc-pVTZ method was an improvement over the B3LYP/6-31G and B3LYP/lanl2dz methods as it was able to predict the first reduction potential of the diazine ring (wave 1) for all of the 3-aryl-quinoxaline-2-carbonitrile 1,4-di-N-oxide derivatives accurately. The B3LYP/cc-pVTZ predicted electrochemical potentials had a strong correlation to experimental values for wave 1. None of the methods demonstrated the ability to predict the nitro wave reduction potential for derivatives containing a nitro group. B3LYP/cc-pVTZ predicted electrochemical potentials for the second reduction of the diazine ring (wave 2) had a low correlation to the experimental values for the derivatives without a nitro group and no correlation of the derivatives when the nitro group was included in the analysis. Full article

(This article belongs to the Section Computational Chemistry)

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21 pages, 7894 KiB

Open AccessArticle

Application of Orthogonal Functions to Equivalent Linearization Method for MDOF Duffing–Van der Pol Systems under Nonstationary Random Excitations

by Amir Younespour, Hosein Ghaffarzadeh and Shaohong Cheng

Computation 2023, 11(1), 8; https://doi.org/10.3390/computation11010008 - 5 Jan 2023

Viewed by 1728

Abstract

Many mechanical systems manifest nonlinear behavior under nonstationary random excitations. Neglecting this nonlinearity in the modeling of a dynamic system would result in unacceptable results. However, it is challenging to find exact solutions to nonlinear problems. Therefore, equivalent linearization methods are often used [...] Read more.

Many mechanical systems manifest nonlinear behavior under nonstationary random excitations. Neglecting this nonlinearity in the modeling of a dynamic system would result in unacceptable results. However, it is challenging to find exact solutions to nonlinear problems. Therefore, equivalent linearization methods are often used to seek approximate solutions for this kind of problem. To overcome the limitations of the existing equivalent linearization methods, an orthogonal-function-based equivalent linearization method in the time domain is proposed for nonlinear systems subjected to nonstationary random excitations. The proposed method is first applied to a single-degree-of-freedom (SDOF) Duffing–Van der Pol oscillator subjected to stationary and nonstationary excitations to validate its accuracy. Then, its applicability to nonlinear MDOF systems is depicted by a 5DOF Duffing–Van der Pol system subjected to nonstationary excitation, with different levels of system nonlinearity strength considered in the analysis. Results show that the proposed method has the merit of predicting the nonlinear system response with high accuracy and computation efficiency. In addition, it is applicable to any general type of nonstationary random excitation. Full article

(This article belongs to the Special Issue Mathematical Modeling and Study of Nonlinear Dynamic Processes)

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21 pages, 4660 KiB

Open AccessArticle

Sparse Reconstruction Using Hyperbolic Tangent as Smooth l₁-Norm Approximation

by Hassaan Haider, Jawad Ali Shah, Kushsairy Kadir and Najeeb Khan

Computation 2023, 11(1), 7; https://doi.org/10.3390/computation11010007 - 4 Jan 2023

Cited by 4 | Viewed by 2210

Abstract

In the Compressed Sensing (CS) framework, the underdetermined system of linear equation (USLE) can have infinitely many possible solutions. However, we intend to find the sparsest possible solution, which is

l_{0}

-norm minimization. However, finding an

l_{0}

norm solution out of [...] Read more.

In the Compressed Sensing (CS) framework, the underdetermined system of linear equation (USLE) can have infinitely many possible solutions. However, we intend to find the sparsest possible solution, which is

l_{0}

-norm minimization. However, finding an

l_{0}

norm solution out of infinitely many possible solutions is NP-hard problem that becomes non-convex optimization problem. It has been a practically proven fact that

l_{0}

norm penalty can be adequately estimated by

l_{1}

norm, which recasts a non-convex minimization problem to a convex problem. However,

l_{1}

norm non-differentiable and gradient-based minimization algorithms are not applicable, due to this very reason there is a need to approximate

l_{1}

norm by its smooth approximation. Iterative shrinkage algorithms provide an efficient method to numerically minimize

l_{1}

-regularized least square optimization problem. These algorithms are required to induce sparsity in their solutions to meet the CS recovery requirement. In this research article, we have developed a novel recovery method that uses hyperbolic tangent function to recover undersampled signal/images in CS framework. In our work,

l_{1}

norm and soft thresholding are both approximated with the hyperbolic tangent functions. We have also proposed the criteria to tune optimization parameters to get optimal results. The error bounds for the proposed

l_{1}

norm approximation are evaluated. To evaluate performance of our proposed method, we have utilized a dataset comprised of 1-D sparse signal, compressively sampled MR image and cardiac cine MRI. The MRI is an important imaging modality for assessing cardiac vascular function. It provides the ejection fraction and cardiac output of the heart. However, this advantage comes at the cost of a slow acquisition process. Hence, it is essential to speed up the acquisition process to take the full benefits of cardiac cine MRI. Numerical results based on performance metrics, such as Structural Similarity (SSIM), Peak Signal to Noise Ratio (PSNR) and Root Mean Square Error (RMSE) show that the proposed tangent hyperbolic based CS recovery offers a much better performance as compared to the traditional Iterative Soft Thresholding (IST) recovery methods. Full article

(This article belongs to the Special Issue Computational Medical Image Analysis)

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9 pages, 1837 KiB

Open AccessArticle

Dispersive FSO Performance Estimation with Gaussian Pulses and Laplace Modeled Time Jitter

by P. J. Gripeos, D. Oreinos, D. Kriempardis, A. D. Tsigopoulos, E. Kapotis, A. Katsis and H. E. Nistazakis

Computation 2023, 11(1), 6; https://doi.org/10.3390/computation11010006 - 4 Jan 2023

Viewed by 1695

Abstract

FSO communications tend to be one of most convenient, wireless, high-data-rate communications technologies of global telecom networking, and they are implemented and operated with low-cost resources. Despite their advantages, FSO systems’ performance is delimited by several physical phenomena, which act on propagating signal [...] Read more.

FSO communications tend to be one of most convenient, wireless, high-data-rate communications technologies of global telecom networking, and they are implemented and operated with low-cost resources. Despite their advantages, FSO systems’ performance is delimited by several physical phenomena, which act on propagating signal beams through the atmospheric path. Among other effects, chromatic dispersion and time jitter affect the shape and the detection instant of the incoming optical pulse, respectively. This results in signal fading and probable misdetections, and the signal fades along the propagation path due to power losses. Particularly, chromatic dispersion affects the width of the longitudinal information pulse, while the stochastic nature of the time jitter effect is treated with the use of a statistical model for the instantly received irradiance of the detecting pulse at the corresponding time slot. In this study, the symmetrical Laplace distribution was chosen for weak time jitter effect emulation because of its symmetry in pulse detection before or after the center of the specific timeslot. Thus, the joint influence of all three effects could considered, including all the parameters involved. Moreover, new-closed-form mathematical expressions were derived in order to accurately estimate the availability and the reliability of the FSO links under consideration. Next, using the derived mathematical forms, performance outcomes were presented for typical parameter values for realistic FSO links. Full article

(This article belongs to the Special Issue Selected Papers from the 10th International Conference from Scientific Computing to Computational Engineering (IC-SCCE 2022))

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19 pages, 11913 KiB

Open AccessArticle

Modeling of Quantum Dots with the Finite Element Method

by G.A. Mantashian, P.A. Mantashyan and D.B. Hayrapetyan

Computation 2023, 11(1), 5; https://doi.org/10.3390/computation11010005 - 2 Jan 2023

Cited by 15 | Viewed by 4041

Abstract

Considering the increasing number of experimental results in the manufacturing process of quantum dots (QDs) with different geometries, and the fact that most numerical methods that can be used to investigate quantum dots with nontrivial geometries require large computational capacities, the finite element [...] Read more.

Considering the increasing number of experimental results in the manufacturing process of quantum dots (QDs) with different geometries, and the fact that most numerical methods that can be used to investigate quantum dots with nontrivial geometries require large computational capacities, the finite element method (FEM) becomes an incredibly attractive tool for modeling semiconductor QDs. In the current article, we used FEM to obtain the first twenty-six probability densities and energy values for the following GaAs structures: rectangular, spherical, cylindrical, ellipsoidal, spheroidal, and conical QDs, as well as quantum rings, nanotadpoles, and nanostars. The results of the numerical calculations were compared with the exact analytical solutions and a good deviation was obtained. The ground-state energy dependence on the element size was obtained to find the optimal parameter for the investigated structures. The abovementioned calculation results were used to obtain valuable insight into the effects of the size quantization’s dependence on the shape of the QDs. Additionally, the wavefunctions and energies of spherical CdSe/CdS quantum dots were obtained while taking into account the diffusion effects on the potential depth with the use of a piecewise Woods–Saxon potential. The diffusion of the effective mass and the dielectric permittivity was obtained with the use of a normal Woods–Saxon potential. A structure with a quasi-type-II band alignment was obtained at the core size of ≈2.2 nm This result is consistent with the experimental data. Full article

(This article belongs to the Special Issue Application of Finite Element Methods)

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11 pages, 295 KiB

Open AccessArticle

Application of the ARA Method in Solving Integro-Differential Equations in Two Dimensions

by Rania Saadeh

Computation 2023, 11(1), 4; https://doi.org/10.3390/computation11010004 - 29 Dec 2022

Cited by 10 | Viewed by 1777

Abstract

The main purpose of this study is to investigate solutions of some integral equations of different classes using a new scheme. This research introduces and implements the new double ARA transform to solve integral and partial integro-differential equations. We introduce basic theorems and [...] Read more.

The main purpose of this study is to investigate solutions of some integral equations of different classes using a new scheme. This research introduces and implements the new double ARA transform to solve integral and partial integro-differential equations. We introduce basic theorems and properties of the double ARA transform in two dimensions, and some results related to the double convolution theorem and partial derivatives are presented. In addition, to show the validity of the proposed technique, we introduce and solve some examples using the new approach. Full article

(This article belongs to the Topic Mathematical Modeling)

10 pages, 2480 KiB

Open AccessArticle

A New Modeling Approach for Viscous Dampers Using an Extended Kelvin–Voigt Rheological Model Based on the Identification of the Constitutive Law’s Parameters

by Ovidiu Vasile and Mihai Bugaru

Computation 2023, 11(1), 3; https://doi.org/10.3390/computation11010003 - 27 Dec 2022

Cited by 3 | Viewed by 2757

Abstract

In addition to elastomeric devices, viscous fluid dampers can reduce the vibration transmitted to dynamic systems. Usually, these fluid dampers are rate-independent and used in conjunction with elastomeric isolators to insulate the base of buildings (buildings, bridges, etc.) to reduce the shocks caused [...] Read more.

In addition to elastomeric devices, viscous fluid dampers can reduce the vibration transmitted to dynamic systems. Usually, these fluid dampers are rate-independent and used in conjunction with elastomeric isolators to insulate the base of buildings (buildings, bridges, etc.) to reduce the shocks caused by earthquakes by increasing the damping capability. According to the EN 15129 standard, the velocity-dependent anti-seismic devices are Fluid Viscous Dampers (FVDs) and Fluid Spring Dampers (FSDs). Based on experimental data from a dynamic regime of a fluid viscous damper of small dimensions, for which not all the design details are known, to determine the law of behavior for the viscous damper, the characteristics of the damper are identified, including the nonlinear parameter α (exponent of velocity V) of the constitutive law. Note that the magnitude of the fluid damper force depends on both velocity (where the maximum value is 0.52 m/s) and amplitude displacement (±25 mm). Using the Kelvin–Voigt rheological models, the dynamic response of a structure fixed with a fluid viscous device is analyzed, presenting the reaction force and displacement during the parameterized application of an external shock. This new approach for FVDs/FSDs was validated using the standard deviation between the experimental data and the numerical results of the extended Kelvin–Voigt model offering researchers in the field of seismic devices a reliable method to obtain a constitutive law for such devices. Full article

(This article belongs to the Special Issue Selected Papers from the 10th International Conference from Scientific Computing to Computational Engineering (IC-SCCE 2022))

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17 pages, 345 KiB

Open AccessArticle

Solutions of the Yang–Baxter Equation Arising from Brauer Configuration Algebras

by Agustín Moreno Cañadas, Adolfo Ballester-Bolinches and Isaías David Marín Gaviria

Computation 2023, 11(1), 2; https://doi.org/10.3390/computation11010002 - 23 Dec 2022

Cited by 5 | Viewed by 1656

Abstract

Currently, researching the Yang–Baxter equation (YBE) is a subject of great interest among scientists of diverse areas in mathematics and other sciences. One of the fundamental open problems is to find all of its solutions. The investigation deals with developing theories such as [...] Read more.

Currently, researching the Yang–Baxter equation (YBE) is a subject of great interest among scientists of diverse areas in mathematics and other sciences. One of the fundamental open problems is to find all of its solutions. The investigation deals with developing theories such as knot theory, Hopf algebras, quandles, Lie and Jordan (super) algebras, and quantum computing. One of the most successful techniques to obtain solutions of the YBE was given by Rump, who introduced an algebraic structure called the brace, which allows giving non-degenerate involutive set-theoretical solutions. This paper introduces Brauer configuration algebras, which, after appropriate specializations, give rise to braces associated with Thompson’s group F. The dimensions of these algebras and their centers are also given. Full article

(This article belongs to the Special Issue Graph Theory and Its Applications in Computing)

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15 pages, 5189 KiB

Open AccessArticle

Experimental vs. Numerical Computation of Acoustic Analyses on the Thickness Influence of the Multilayer Panel

by Ovidiu Vasile and Mihai Bugaru

Computation 2023, 11(1), 1; https://doi.org/10.3390/computation11010001 - 20 Dec 2022

Cited by 1 | Viewed by 2196

Abstract

Sound-absorbing panels made with a perforated front and a sound-absorbing material on the back have been used in many forms of construction for a long time. It is a reasonably efficient system, obtaining high values of sound absorption at a specific resonant frequency, [...] Read more.

Sound-absorbing panels made with a perforated front and a sound-absorbing material on the back have been used in many forms of construction for a long time. It is a reasonably efficient system, obtaining high values of sound absorption at a specific resonant frequency, depending on the design of the structure of the sound-absorbing multilayer panel. The present work considers an acoustic panel in two constructive types, consisting of four layers: a front panel made of perforated sheet, polyethylene foam foil, basalt wool board with two different thicknesses, and a back panel of the non-perforated sheet. Due to the different thicknesses of the basalt wool board, for the multilayer structure of the acoustic panel, differences in acoustic impedance and acoustic absorption can be highlighted, experimentally determined with an impedance tube, using the transfer function method (TFM) based on EN ISO 10534-2 in the frequency range 100–3200 Hz. In the meantime, a method was developed to predict the sound absorption coefficient, namely the prediction of sound absorption coefficient using the transfer matrix method (PSAC-TMM). This computational model of the multilayer acoustic panel is introduced considering the internal geometry of the multilayer panel, as well as the computation of the acoustic impedance of each layer, all gathered through the transfer matrix method (TMM). Comparative analyses between experimental data and predictive results using PSAC-TMM were performed, validating the PSAC-TMM as a predictive method to estimate the sound absorption coefficient for acoustic multilayer panels. Full article

(This article belongs to the Special Issue Selected Papers from the 10th International Conference from Scientific Computing to Computational Engineering (IC-SCCE 2022))

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Computation, Volume 11, Issue 1 (January 2023) – 14 articles

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