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Feature Papers in Section "Engineering and Materials" 2024

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A special issue of Symmetry (ISSN 2073-8994). This special issue belongs to the section "Engineering and Materials".

Deadline for manuscript submissions: 31 December 2024 | Viewed by 11780

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Dr. Vasilis K. Oikonomou

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Physics Department, Aristotle University of Thessaloniki, 54124 Thessaloniki, Greece
Interests: cosmology; inflationary cosmology; modified theories of gravity; physics of the early universe; dark energy; dark matter; supersymmetry; mathematical physics; high energy physics; theoretical physics; epistemic game theory; game theory
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Dear Colleagues,

In the multidisciplinary Section “Engineering and Materials" of the Symmetry journal, we welcome original research articles with top-level mathematical modeling or experimental outcomes and a strong substantiation of conclusions and results, as well as relevant analytical reviews on all aspects of symmetry or asymmetry in engineering, materials, energy sciences, and other interdisciplinary areas.

We aim to provide a virtual forum and database for experts, publishing papers with engineering significance that are dedicated to the most up-to-date issues and mainstream topics. The Section will fill the gap of mathematical modeling in these areas in the scientific literature, emphasizing articles related to cutting-edge technologies and contemporary technology applications. Articles are expected to have original content and demonstrate clear scientific novelty.

Other areas of interest associated with engineering and materials science require a multidisciplinary approach.

Dr. Vasilis K. Oikonomou
Guest Editor

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All submissions that pass pre-check are peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Symmetry is an international peer-reviewed open access monthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 2400 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

materials engineering
nanotechnology
power systems and thermal engineering
mechanical engineering, mechatronics, and robotics
automation and control engineering
electronic engineering
communication engineering
chemical and molecular engineering
optical engineering and technology
fiber optics technology
mathematical and formal aspects of superconductivity
mechanochemical aspects of aqueous solutions
green chemistry fabrication of materials

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Published Papers (10 papers)

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Research

18 pages, 337 KiB

Open AccessArticle

Lagrangian Coupling of Dissipative Electrodynamic Waves with the Thermal Absorption and Emission

by Ferenc Márkus and Katalin Gambár

Symmetry 2024, 16(12), 1559; https://doi.org/10.3390/sym16121559 - 21 Nov 2024

Viewed by 198

Abstract

Electromagnetic wave dissipation is experienced in radiative absorbing-emitting processes and signal transmissions via media. The absorbed wave initiates thermal processes in the conducting medium. Conversely, thermal processes generate electromagnetic waves in the vacuum–material interface region. The two processes do not take place symmetrically, i.e., the incoming and thermalizing electromagnetic spectrum does not occur in the reverse process. The conservation of energy remains in effect, and the loop process “electromagnetic wave–thermal propagation–electromagnetic wave” is dissipative. In the Lagrangian formalism, we provide a unified description of these two interconnected processes. We point out how it involves the origin of the asymmetry. Full article

(This article belongs to the Special Issue Feature Papers in Section "Engineering and Materials" 2024)

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18 pages, 381 KiB

Open AccessCommunication

A Fourth-Order Tensorial Wiener Filter Using the Conjugate Gradient Method

by Laura-Maria Dogariu, Ruxandra-Liana Costea, Constantin Paleologu and Jacob Benesty

Symmetry 2024, 16(11), 1433; https://doi.org/10.3390/sym16111433 - 28 Oct 2024

Viewed by 977

Abstract

The recently developed iterative Wiener filter using a fourth-order tensorial (FOT) decomposition owns appealing performance in the identification of long length impulse responses. It relies on the nearest Kronecker product representation (with particular intrinsic symmetry features), together with low-rank approximations. Nevertheless, this new iterative filter requires matrix inversion operations when solving the Wiener–Hopf equations associated with the component filters. In this communication, we propose a computationally efficient version that relies on the conjugate gradient (CG) method for solving these sets of equations. The proposed solution involves a specific initialization of the component filters and sequential connections between the CG cycles. Different FOT-based decomposition setups are also analyzed from the point of view of the resulting parameter space. Experimental results obtained in the context of echo cancellation confirm the good behavior of the proposed approach and its superiority in comparison to the conventional Wiener filter and other decomposition-based versions. Full article

(This article belongs to the Special Issue Feature Papers in Section "Engineering and Materials" 2024)

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30 pages, 10171 KiB

Open AccessArticle

Photoacoustic Waveform Design for Optimal Parameter Estimation Based on Maximum Mutual Information

by Zuwen Sun and Natalie Baddour

Symmetry 2024, 16(10), 1402; https://doi.org/10.3390/sym16101402 - 21 Oct 2024

Viewed by 958

Abstract

Waveform design is a potentially significant approach to improve the performance of an imaging or detection system. Photoacoustic imaging is a rapidly developing field in recent years; however, photoacoustic waveform design has not been extensively investigated. This paper considers the problem of photoacoustic waveform design for parameter estimation under constraints on input energy. The use of information theory is exploited to formulate and solve this optimal waveform design problem. The approach yields the optimal waveform power spectral density. Direct inverse Fourier transform of the optimal waveform frequency spectrum amplitude is proposed to obtain a real waveform in the time domain. Absorbers are assumed to be stochastic absorber ensembles with uncertain duration and location parameters. Simulation results show the relationship between absorber parameter distribution and the characteristics of optimal waveforms. Comparison of optimal waveforms for estimation, optimal waveforms for detection (signal-to-noise ratio) and other commonly used waveforms are also discussed. The symmetry properties of the forward and inverse Fourier Transforms are used to analyze the time and frequency properties and provide a heuristic view of how different goals affect the choice of waveform. Full article

(This article belongs to the Special Issue Feature Papers in Section "Engineering and Materials" 2024)

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18 pages, 5645 KiB

Open AccessArticle

Assessing Vulnerabilities in Line Length Parameterization and the Per-Unit-Length Paradigm for Phase Modulation and Figure-of-Merit Evaluation in 60 GHz Liquid Crystal Phase Shifters

by Jinfeng Li and Haorong Li

Symmetry 2024, 16(10), 1261; https://doi.org/10.3390/sym16101261 - 25 Sep 2024

Viewed by 3491

Abstract

The figure-of-merit (FoM) is a crucial metric in evaluating liquid crystal (LC) phase shifters, significantly influencing the selection of superior device candidates. This paper identifies, for the first time, a fundamental limitation in the widely-used High-Frequency Structure Simulator (HFSS), a closed-source commercial tool, when modeling reconfigurable delay line phase shifters (RDLPS) based on LC at millimeter-wave (mmW) frequencies for Beyond 5G (B5G) and Sixth-Generation (6G) applications. Specifically, the study reveals unreliable predictions of differential phase shifts (DPS) when using the line length parameterization (LLP) approach, with an accuracy of only 47.22%. These LLP-induced inaccuracies lead to misleading FoM calculations, potentially skewing comparative analyses against phase shifters implemented with different geometries or advanced technologies. Additionally, the per-unit-length (PUL) paradigm, commonly employed by microwave circuit engineers for evaluating and optimizing microwave transmission line designs, is also found to have limitations in the context of mmW RDLPS based on LC. The PUL methodology underestimates the FoM by 1.38206°/dB for an LC coaxial RDLPS at 60 GHz. These findings underscore a critical symmetry implication, where the assumed symmetry in phase shift response is violated, resulting in inconsistent performance assessments. To address these challenges, a remediation strategy based on a scenario-based “Length-for-π” (LFP) framework is proposed, offering more accurate performance characterization and enabling better-informed decision-making in mmW phase shifter design. Full article

(This article belongs to the Special Issue Feature Papers in Section "Engineering and Materials" 2024)

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16 pages, 9639 KiB

Open AccessArticle

Hierarchical Hypervapotron Structure Integrated with Microchannels for Advancement of Thermohydraulic Performance

by Xin Meng, Kai Cheng, Qi Zhao and Xuemei Chen

Symmetry 2024, 16(8), 1089; https://doi.org/10.3390/sym16081089 - 22 Aug 2024

Viewed by 616

Abstract

The hypervapotron structure was considered to be a feasible configuration to meet the high heat-dissipating requirement of divertors in nuclear fusion devices. In this work, symmetric CuCrZr-based transverse microchannels (TMHC) and longitudinal microchannels (LMHC) with an integrated hypervapotron channel were proposed and manufactured, and subcooled flow boiling experiments were conducted using deionized water at an inlet temperature of 20 °C with a traditional flat-type hypervapotron channel (FHC) for comparison. The LMHC and TMHC obtained lower wall temperatures than the FHC for all conditions, and the TMHC yielded the lowest temperatures. The heat transfer coefficients of the LMHC and TMHC outperformed the FHC due to the enlarged heat transfer area, and the TMHC had the greatest heat transfer coefficient (maximumly increased by 132% compared to the FHC) because the transverse-arranged microchannels were conductive, promoting the convection and liquid replenishment ability by introducing branch flow between fins; however, the microchannels of the LMHC were insensible to flow velocities due to the block effect of longitudinal microchannels. The LMHC obtained the largest pressure drop, and the pressure drop for the FHC and TMHC were comparable since the transverse-placed microchannels had little effect on frictional pressure loss. The TMHC attained the greatest comprehensive thermohydraulic performance which might bring significant insight to the structural design of hypervapotron devices. Full article

(This article belongs to the Special Issue Feature Papers in Section "Engineering and Materials" 2024)

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15 pages, 2572 KiB

Open AccessArticle

Anti-Fatigue-Damage-Oriented Through-Life Optimization and Control of High-Power IGCT Converters in Wind Energy Systems

by Yiyang Chen, Yimin Zhang, Haoyu Chen, Zhen Li and Zhenbin Zhang

Symmetry 2024, 16(8), 1047; https://doi.org/10.3390/sym16081047 - 14 Aug 2024

Viewed by 841

Abstract

Integrated gate commutated thyristors (IGCTs) are critical components in high-voltage, high-current, and high-power conversion systems, particularly in offshore wind energy systems. However, the working environment of offshore wind energy conversion systems is extremely harsh. In this article, we propose an active damage control approach aiming at enhancing the reliability of the conversion system. By employing electro-thermal modeling for the equipment of the offshore wind energy conversion system, the junction temperature and fatigue damage of IGCT are simulated during the operation process. Using the improved model predictive current control (MPCC) method, active damage control effectively regulates the switching frequency of IGCT. IGCTs are symmetrically distributed on each leg of the converter, so the lifespan of the two IGCTs on each leg is also considered to be similar. This method balances the life of the IGCTs on the three legs of the converter and optimizes their utilization to the maximum extent. These measures effectively enhance the reliability of the conversion system and lower the operation and maintenance cost of high-power IGCT converters. The effectiveness of the proposed method is validated by co-simulation results by ANSYS and MATLAB/Simulink. Full article

(This article belongs to the Special Issue Feature Papers in Section "Engineering and Materials" 2024)

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14 pages, 1329 KiB

Open AccessArticle

Crystallographic Quaternions

by Andrzej Katrusiak and Stiv Llenga

Symmetry 2024, 16(7), 818; https://doi.org/10.3390/sym16070818 - 29 Jun 2024

Cited by 1 | Viewed by 736

Abstract

Symmetry transformations in crystallography are traditionally represented as equations and matrices, which can be suitable both for orthonormal and crystal reference systems. Quaternion representations, easily constructed for any orientations of symmetry operations, owing to the vector structure based on the direction of the rotation axes or of the normal vectors to the mirror plane, are known to be advantageous for optimizing numerical computing. However, quaternions are described in Cartesian coordinates only. Here, we present the quaternion representations of crystallographic point-group symmetry operations for the crystallographic reference coordinates in triclinic, monoclinic, orthorhombic, tetragonal, cubic and trigonal (in rhombohedral setting) systems. For these systems, all symmetry operations have been listed and their applications exemplified. Owing to their concise form, quaternions can be used as the symbols of symmetry operations, which contain information about both the orientation and the rotation angle. The shortcomings of quaternions, including different actions for rotations and improper symmetry operations, as well as inadequate representation of the point symmetry in the hexagonal setting, have been discussed. Full article

(This article belongs to the Special Issue Feature Papers in Section "Engineering and Materials" 2024)

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14 pages, 3232 KiB

Open AccessArticle

A Fault Diagnosis Method for Analog Circuits Based on Improved TQWT and Inception Model

by Xinjia Yuan, Siting Yang, Wenmin Wang, Yunlong Sheng, Xuye Zhuang and Jiancheng Yin

Symmetry 2024, 16(6), 720; https://doi.org/10.3390/sym16060720 - 10 Jun 2024

Cited by 1 | Viewed by 822

Abstract

A soft fault in an analog circuit is a symptom where the parameter range of a component exists symmetrically to the left and right of its nominal value and exceeds a specific range. The proposed method uses the Grey Wolf Optimization (GWO) optimized tunable Q-factor wavelet transform (TQWT) algorithm for feature refinement, the Inception model for feature extraction, and an SVM for fault diagnosis. First, the Q-factor is optimized to make it more compatible with the signal. Second, the signal is decomposed, and a single-branch reconstruction is performed using the TQWT to extract features adequately. Then, fault feature extraction is conducted using the Inception model to obtain multiscale features. Finally, a Support Vector Machine (SVM) is used to complete the entire fault diagnosis process. The proposed method is comprehensively evaluated using the Sallen–Key bandpass filter circuit and the four-op-amp biquad high-pass filter circuit widely used in electronic systems. The experimental results prove that the proposed method outperforms the existing methods in terms of diagnosis accuracy and reliability. Full article

(This article belongs to the Special Issue Feature Papers in Section "Engineering and Materials" 2024)

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29 pages, 1760 KiB

Open AccessArticle

Statistical Mechanics Approaches for Studying Temperature and Rate Effects in Multistable Systems

by Andrea Cannizzo and Stefano Giordano

Symmetry 2024, 16(5), 632; https://doi.org/10.3390/sym16050632 - 20 May 2024

Viewed by 1236

Abstract

Systems with a multistable energy landscape are widespread in physics, biophysics, technology, and materials science. They are strongly influenced by thermal fluctuations and external mechanical actions that can be applied at different rates, moving the system from equilibrium to non-equilibrium regimes. In this paper, we focus on a simple system involving a single breaking phenomenon to describe the various theoretical approaches used to study these problems. To begin with, we propose the exact solution at thermodynamic equilibrium based on the calculation of the partition function without approximations. We then introduce the technique of spin variables, which is able to simplify the treatment even for systems with a large number of coordinates. We then analyze the energy balance of the system to better understand its underlying physics. Finally, we introduce a technique based on transition state theory useful for studying the non-equilibrium dynamical regimes of these systems. This method is appropriate for the evaluation of rate effects and hysteresis loops. These approaches are developed for both the Helmholtz ensemble (prescribed extension) and the Gibbs ensemble (applied force) of statistical mechanics. The symmetry and duality of these two ensembles is discussed in depth. While these techniques are used here for a simple system with theoretical purposes, they can be applied to complex systems of interest for several physical, biophysical, and technological applications. Full article

(This article belongs to the Special Issue Feature Papers in Section "Engineering and Materials" 2024)

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16 pages, 4185 KiB

Open AccessArticle

Machine Learning-Based Research for Predicting Shale Gas Well Production

by Nijun Qi, Xizhe Li, Zhenkan Wu, Yujin Wan, Nan Wang, Guifu Duan, Longyi Wang, Jing Xiang, Yaqi Zhao and Hongming Zhan

Symmetry 2024, 16(5), 600; https://doi.org/10.3390/sym16050600 - 12 May 2024

Cited by 1 | Viewed by 1305

Abstract

The estimated ultimate recovery (EUR) of a single well must be predicted to achieve scale-effective shale gas extraction. Accurately forecasting EUR is difficult due to the impact of various geological, engineering, and production factors. Based on data from 200 wells in the Weiyuan block, this paper used Pearson correlation and mutual information to eliminate the factors with a high correlation among the 31 EUR influencing factors. The RF-RFE algorithm was then used to identify the six most important factors controlling the EUR of shale gas wells. XGBoost, RF, SVM, and MLR models were built and trained with the six dominating factors screened as features and EUR as labels. In this process, the model parameters were optimized, and finally the prediction accuracies of the models were compared. The results showed that the thickness of a high-quality reservoir was the dominating factor in geology; the high-quality reservoir length drilled, the fracturing fluid volume, the proppant volume, and the fluid volume per length were the dominating factors in engineering; and the 360−day flowback rate was the dominating factor in production. Compared to the SVM and MLR models, the XG Boost and the RF models based on integration better predicted EUR. The XGBoost model had a correlation coefficient of 0.9 between predicted and observed values, and its standard deviation was closest to the observed values’ standard deviation, making it the best model for EUR prediction among the four types of models. Identifying the dominating factors of shale gas single-well EUR can provide significant guidance for development practice, and using the optimized XGBoost model to forecast the shale gas single-well EUR provides a novel idea for predicting shale gas well production. Full article

(This article belongs to the Special Issue Feature Papers in Section "Engineering and Materials" 2024)

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