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Symmetry, Volume 12, Issue 8 (August 2020) – 181 articles

Cover Story (view full-size image): The visible electronic absorption band of pyridinium dicarbethoxy methylid due to intramolecular charge transfer can be used to characterize the excited electronic state. This band is very sensitive to the solvent nature, allowing the determination of the nature and strength of intermolecular interactions. View this paper.
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Open AccessArticle
Enhancement in Quality Estimation of Resistance Spot Welding Using Vision System and Fuzzy Support Vector Machine
Symmetry 2020, 12(8), 1380; https://doi.org/10.3390/sym12081380 - 18 Aug 2020
Viewed by 701
Abstract
The current nondestructive testing methods such as ultrasonic, magnetic, or eddy current signals, and even the existing image processing methods, present certain challenges and show a lack of flexibility in building an effective and real-time quality estimation system of the resistance spot welding [...] Read more.
The current nondestructive testing methods such as ultrasonic, magnetic, or eddy current signals, and even the existing image processing methods, present certain challenges and show a lack of flexibility in building an effective and real-time quality estimation system of the resistance spot welding (RSW). This paper provides a significant improvement in the theory and practices for designing a robotized inspection station for RSW at the car manufacturing plants using image processing and fuzzy support vector machine (FSVM). The weld nuggets’ positions on each of the used car underbody models are detected mathematically. Then, to collect perfect pictures of the weld nuggets on each of these models, the required end-effector path is planned in real-time by establishing the Denavit-Hartenberg (D-H) model and solving the forward and inverse kinematics models of the used six-degrees of freedom (6-DOF) robotic arm. After that, the most frequent resistance spot-welding failure modes are reviewed. Improved image processing methods are employed to extract new features from the elliptical-shaped weld nugget’s surface and obtain a three-dimensional (3D) reconstruction model of the weld’s surface. The extracted artificial data of thousands of samples of the weld nuggets are divided into three groups. Then, the FSVM learning algorithm is formed by applying the fuzzy membership functions to each group. The improved image processing with the proposed FSVM method shows good performance in classifying the failure modes and dealing with the image noise. The experimental results show that the improvement of comprehensive automatic real-time quality evaluation of RSW surfaces is meaningful: the quality estimation could be processed within 0.5 s in very high accuracy. Full article
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Open AccessArticle
On Taylor Series Expansion for Statistical Moments of Functions of Correlated Random Variables
Symmetry 2020, 12(8), 1379; https://doi.org/10.3390/sym12081379 - 18 Aug 2020
Cited by 1 | Viewed by 612
Abstract
The paper is focused on Taylor series expansion for statistical analysis of functions of random variables with special attention to correlated input random variables. It is shown that the standard approach leads to significant deviations in estimated variance of non-linear functions. Moreover, input [...] Read more.
The paper is focused on Taylor series expansion for statistical analysis of functions of random variables with special attention to correlated input random variables. It is shown that the standard approach leads to significant deviations in estimated variance of non-linear functions. Moreover, input random variables are often correlated in industrial applications; thus, it is crucial to obtain accurate estimations of partial derivatives by a numerical differencing scheme. Therefore, a novel methodology for construction of Taylor series expansion of increasing complexity of differencing schemes is proposed and applied on several analytical examples. The methodology is adapted for engineering applications by proposed asymmetric difference quotients in combination with a specific step-size parameter. It is shown that proposed differencing schemes are suitable for functions of correlated random variables. Finally, the accuracy, efficiency, and limitations of the proposed methodology are discussed. Full article
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Open AccessArticle
Lie Symmetry Analysis, Exact Solutions, Conservation Laws and Bäcklund Transformations of the Gibbons-Tsarev Equation
Symmetry 2020, 12(8), 1378; https://doi.org/10.3390/sym12081378 - 18 Aug 2020
Cited by 1 | Viewed by 486
Abstract
In this paper, we mainly put the Lie symmetry analysis method on the Gibbons-Tsarev equation (GTe) to obtain some new results, including some Lie symmetries, one-parameter transformation groups, explicit invariant solutions in the form of power series. Subsequently, the self-adjointness of the GTe [...] Read more.
In this paper, we mainly put the Lie symmetry analysis method on the Gibbons-Tsarev equation (GTe) to obtain some new results, including some Lie symmetries, one-parameter transformation groups, explicit invariant solutions in the form of power series. Subsequently, the self-adjointness of the GTe is singled out. It follows that the conservation laws associated with symmetries of GTe are constructed with the aid of Ibragimov’ method. Finally, we present the Bäcklund transformations so that more abundant solutions can be worked out. Full article
(This article belongs to the Section Mathematics and Symmetry)
Open AccessArticle
The Symmetries in Film and Television Production Areas Based on Virtual Reality and Internet of Things Technology
Symmetry 2020, 12(8), 1377; https://doi.org/10.3390/sym12081377 - 18 Aug 2020
Cited by 2 | Viewed by 737
Abstract
To enrich the form of film and television production, improve the level of film and television production, and satisfy the film-watching experiences of audiences, based on Virtual Reality (VR) and the Internet of Things (IoT) technology, with the help of S3 Studio Max [...] Read more.
To enrich the form of film and television production, improve the level of film and television production, and satisfy the film-watching experiences of audiences, based on Virtual Reality (VR) and the Internet of Things (IoT) technology, with the help of S3 Studio Max and Photoshop software, a VR film-watching system is built, which realizes the interaction with users on different devices through somatosensory interaction sensors. In addition, by utilizing Twirling720, the panoramic sound recording is achieved. Through this system, a smart IoT platform between users, films, and devices is built. Finally, this platform is utilized to produce the film and television work Van Gogh in Dream, which is evaluated and analyzed through questionnaires. The results show that the technology system of this set of film and television production is complete, and the production level of film and television works have been significantly improved. The audience recognition of film and television production based on this technology is 55%, and the impression evaluation is over 56%. However, knowledge acquisition is only 20%, and historical understanding is above 50%. These dimensions show that compared with traditional film production, artificial intelligence films can bring a better experience to audiences, but knowledge acquisition is less. Therefore, professional knowledge will be improved at the later stage. The above results provide a theoretical basis for the application of artificial intelligence technology in film production and production mode. Full article
(This article belongs to the Special Issue Symmetries in Art, Nature, and Biomolecules)
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Open AccessReview
Fluctuating Asymmetry, Developmental Noise and Developmental Stability: Future Prospects for the Population Developmental Biology Approach
Symmetry 2020, 12(8), 1376; https://doi.org/10.3390/sym12081376 - 18 Aug 2020
Cited by 1 | Viewed by 584
Abstract
Developmental noise—which level may vary within a certain backlash allowed by natural selection—is a reflection of the state of a developing system or developmental stability. Phenotypic variations inside the genetically determined norm observed in case of fluctuating asymmetry provide a unique opportunity for [...] Read more.
Developmental noise—which level may vary within a certain backlash allowed by natural selection—is a reflection of the state of a developing system or developmental stability. Phenotypic variations inside the genetically determined norm observed in case of fluctuating asymmetry provide a unique opportunity for evaluating this form of ontogenetic variability. Low levels of developmental noise for the biologic system under study is observed under certain conditions, while its increase acts as a measure of stress. The concordance of changes in developmental stability with changes in other parameters of developmental homeostasis indicates the significance of fluctuating asymmetry estimates. All this determines the future prospects of the study of fluctuating asymmetry not only for developmental biology, but also for population biology. The study of developmental stability may act as the basis of an approach of population developmental biology to assess the nature of the phenotypic diversity and the state of natural populations under various impacts and during evolutionary transformations. Full article
(This article belongs to the Special Issue Fluctuating Asymmetry as a Measure of Stress)
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Open AccessArticle
Lagrange Multiplier Test for Spatial Autoregressive Model with Latent Variables
Symmetry 2020, 12(8), 1375; https://doi.org/10.3390/sym12081375 - 18 Aug 2020
Viewed by 475
Abstract
The focus of this research is to develop a Lagrange multiplier (LM) test of spatial dependence for the spatial autoregressive model (SAR) with latent variables (LVs). It was arranged by the standard SAR, where the independent variables were replaced by factor scores of [...] Read more.
The focus of this research is to develop a Lagrange multiplier (LM) test of spatial dependence for the spatial autoregressive model (SAR) with latent variables (LVs). It was arranged by the standard SAR, where the independent variables were replaced by factor scores of the exogenous latent variables from a measurement model (in structural equation modeling) as well as their dependent variables. As a result, an error distribution of the SAR-LVs should have a different distribution from the standard SAR. Therefore, this LM test for the SAR-LVs is based on the new distribution. The estimation of the latent variables used a weighted least squares (WLS) method. The estimation of the SAR-LVs parameter used a two-stage least squares (2SLS) method. The SAR-LVs model was applied to the model with a positive and negative spatial autoregressive coefficient to illustrate how it was interpreted. Full article
(This article belongs to the Section Mathematics and Symmetry)
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Open AccessArticle
A Fast and Noise Tolerable Binarization Method for Automatic License Plate Recognition in the Open Environment in Taiwan
Symmetry 2020, 12(8), 1374; https://doi.org/10.3390/sym12081374 - 18 Aug 2020
Viewed by 540
Abstract
License plate recognition is widely used in our daily life. Image binarization, which is a process to convert an image to white and black, is an important step of license plate recognition. Among the proposed binarization methods, Otsu method is the most famous [...] Read more.
License plate recognition is widely used in our daily life. Image binarization, which is a process to convert an image to white and black, is an important step of license plate recognition. Among the proposed binarization methods, Otsu method is the most famous and commonly used one in a license plate recognition system since it is the fastest and can reach a comparable recognition accuracy. The main disadvantage of Otsu method is that it is sensitive to luminance effect and noise, and this property is impractical since most vehicle images are captured in an open environment. In this paper, we propose a system to improve the performance of automatic license plates reorganization in the open environment in Taiwan. Our system uses a binarization method which is inspired by the symmetry principles. Experimental results showed that when our method has a similar time complexity to that of Otsu, our method can improve the recognition rate up to 1.30 times better than Otsu. Full article
(This article belongs to the Section Computer and Engineering Science and Symmetry)
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Open AccessArticle
Symmetry, Transactions, and the Mechanism of Wave Function Collapse
Symmetry 2020, 12(8), 1373; https://doi.org/10.3390/sym12081373 - 18 Aug 2020
Cited by 1 | Viewed by 845
Abstract
The Transactional Interpretation of quantum mechanics exploits the intrinsic time-symmetry of wave mechanics to interpret the ψ and ψ* wave functions present in all wave mechanics calculations as representing retarded and advanced waves moving in opposite time directions that form a quantum “handshake” or transaction. This handshake is a 4D standing-wave that builds up across space-time to transfer the conserved quantities of energy, momentum, and angular momentum in an interaction. Here, we derive a two-atom quantum formalism describing a transaction. We show that the bi-directional electromagnetic coupling between atoms can be factored into a matched pair of vector potential Green’s functions: one retarded and one advanced, and that this combination uniquely enforces the conservation of energy in a transaction. Thus factored, the single-electron wave functions of electromagnetically-coupled atoms can be analyzed using Schrödinger’s original wave mechanics. The technique generalizes to any number of electromagnetically coupled single-electron states—no higher-dimensional space is needed. Using this technique, we show a worked example of the transfer of energy from a hydrogen atom in an excited state to a nearby hydrogen atom in its ground state. It is seen that the initial exchange creates a dynamically unstable situation that avalanches to the completed transaction, demonstrating that wave function collapse, considered mysterious in the literature, can be implemented with solutions of Schrödinger’s original wave mechanics, coupled by this unique combination of retarded/advanced vector potentials, without the introduction of any additional mechanism or formalism. We also analyze a simplified version of the photon-splitting and Freedman–Clauser three-electron experiments and show that their results can be predicted by this formalism. Full article
(This article belongs to the Special Issue Symmetries in Quantum Mechanics)
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Open AccessArticle
Shapovalov Wave-Like Spacetimes
Symmetry 2020, 12(8), 1372; https://doi.org/10.3390/sym12081372 - 18 Aug 2020
Cited by 4 | Viewed by 433
Abstract
A complete classification of space-time models is presented, which admit the privileged coordinate systems, where the Hamilton–Jacobi equation for a test particle is integrated by the method of complete separation of variables with separation of the isotropic (wave) variable, on which the metric [...] Read more.
A complete classification of space-time models is presented, which admit the privileged coordinate systems, where the Hamilton–Jacobi equation for a test particle is integrated by the method of complete separation of variables with separation of the isotropic (wave) variable, on which the metric depends (wave-like Shapovalov spaces). For all types of Shapovalov spaces, exact solutions of the Einstein equations with a cosmological constant in vacuum are found. Complete integrals are presented for the eikonal equation and the Hamilton–Jacobi equation of motion of test particles. Full article
(This article belongs to the Special Issue Symmetry: Feature Papers 2020)
Open AccessArticle
Single-Valued Neutrosophic Set Correlation Coefficient and Its Application in Fault Diagnosis
Symmetry 2020, 12(8), 1371; https://doi.org/10.3390/sym12081371 - 17 Aug 2020
Cited by 1 | Viewed by 561
Abstract
With the increasing automation of mechanical equipment, fault diagnosis becomes more and more important. However, the factors that cause mechanical failures are becoming more and more complex, and the uncertainty and coupling between the factors are getting higher and higher. In order to [...] Read more.
With the increasing automation of mechanical equipment, fault diagnosis becomes more and more important. However, the factors that cause mechanical failures are becoming more and more complex, and the uncertainty and coupling between the factors are getting higher and higher. In order to solve the given problem, this paper proposes a single-valued neutrosophic set ISVNS algorithm for processing of uncertain and inaccurate information in fault diagnosis, which generates neutrosophic set by triangular fuzzy number and introduces the formula of the improved weighted correlation coefficient. Since both the single-valued neutrosophic set data and the ideal neutrosophic set data are considered, the proposed method solves the fault diagnosis problem more effectively. Finally, experiments show that the algorithm can significantly improve the accuracy degree of fault diagnosis, and can better satisfy the diagnostic requirements in practice. Full article
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Open AccessArticle
Recognition of Stator Winding Inter-Turn Fault in Interior-Mount LSPMSM Using Acoustic Signals
Symmetry 2020, 12(8), 1370; https://doi.org/10.3390/sym12081370 - 17 Aug 2020
Cited by 1 | Viewed by 543
Abstract
This paper presents a novel stator inter-turn fault diagnosis method for Line Start Permanent Magnet Synchronous Motors (LSPMSMs) using the frequency analysis of acoustic signals resulting from asymmetrical faults. In this method, acoustic data are experimentally collected from a 1 hp interior mount [...] Read more.
This paper presents a novel stator inter-turn fault diagnosis method for Line Start Permanent Magnet Synchronous Motors (LSPMSMs) using the frequency analysis of acoustic signals resulting from asymmetrical faults. In this method, acoustic data are experimentally collected from a 1 hp interior mount LSPMSM for different inter-turn fault cases and motor loading levels, while including the background noise. The signals are collected using a smartphone at a sampling rate of 48,000 samples per second. The signal for each case is analyzed using fast Fourier transform (FFT), which results in the decomposition of the signal into its frequency components. The results indicate that, for both no-load and full-load conditions, 39 components are observed to be affected by the faults, whereby their amplitudes increase with the fault severity. The 40-turns fault shows the highest difference in the component amplitudes compared with the healthy condition acoustic signal. Therefore, this diagnostic method is able to detect the stator inter-turn fault for interior mount LSPMSMs. Moreover, the method is simple and cheap since it uses a readily available sensor. Full article
(This article belongs to the Special Issue Symmetry in Mechanical Engineering Ⅱ)
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Open AccessArticle
The Generalized Trust-Region Sub-Problem with Additional Linear Inequality Constraints—Two Convex Quadratic Relaxations and Strong Duality
Symmetry 2020, 12(8), 1369; https://doi.org/10.3390/sym12081369 - 17 Aug 2020
Cited by 1 | Viewed by 464
Abstract
In this paper, we study the problem of minimizing a general quadratic function subject to a quadratic inequality constraint with a fixed number of additional linear inequality constraints. Under a regularity condition, we first introduce two convex quadratic relaxations (CQRs), under two different [...] Read more.
In this paper, we study the problem of minimizing a general quadratic function subject to a quadratic inequality constraint with a fixed number of additional linear inequality constraints. Under a regularity condition, we first introduce two convex quadratic relaxations (CQRs), under two different conditions, that are minimizing a linear objective function over two convex quadratic constraints with additional linear inequality constraints. Then, we discuss cases where the CQRs return the optimal solution of the problem, revealing new conditions under which the underlying problem admits strong Lagrangian duality and enjoys exact semidefinite optimization relaxation. Finally, under the given sufficient conditions, we present necessary and sufficient conditions for global optimality of the problem and obtain a form of S-lemma for a system of two quadratic and a fixed number of linear inequalities. Full article
(This article belongs to the Special Issue Symmetry in Nonlinear Functional Analysis and Optimization Theory)
Open AccessArticle
Preliminary Design and Cross-Sectional Form Study of Closed-Type Concrete-Filled Steel Tube Support for Traffic Tunnel
by and
Symmetry 2020, 12(8), 1368; https://doi.org/10.3390/sym12081368 - 17 Aug 2020
Cited by 1 | Viewed by 471
Abstract
In view of the structural form and common construction methods of traffic tunnels, the bearing performance of the closed-type CFST support designed for traffic tunnels is studied. The closed-type CFST support, which consist of a CFST girder with external shotcrete, is improved from [...] Read more.
In view of the structural form and common construction methods of traffic tunnels, the bearing performance of the closed-type CFST support designed for traffic tunnels is studied. The closed-type CFST support, which consist of a CFST girder with external shotcrete, is improved from the CFST support used in mine roadways. The reasonable cross-sectional form of closed-type CFST support is analyzed by the FEM. The closed-type CFST support is mainly composed of CFST arches, a shotcrete layer, sleeves, and blind flanges. The post-buckling analysis of the closed-type CFST circular arch members using circular-shaped, rectangular-shaped, triangular-shaped, and trapezoidal-shaped steel tubes is implemented. The result shows that the closed-type CFST support has better performance than the traditional tunnel support. The study also found that for closed-type CFST support, the triangular-shaped steel tube section has the highest bearing capacity, stiffness, and steel utilization rate, which is the preferred cross-sectional form. The bearing capacity of the circular-shaped steel tube section is acceptable. Moreover, the circular-shaped steel tubes are more convenient to obtain and process, so it is also an optional cross-sectional form. The square-shaped and trapezoidal-shaped steel tube sections have neither performance advantages nor economic efficiency, so these two forms are not recommended. Full article
(This article belongs to the Special Issue Composite Structures with Symmetry)
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Open AccessFeature PaperArticle
Bound Electron Transitions under the Influence of Electromagnetic Wave in Constant Magnetic Field
Symmetry 2020, 12(8), 1367; https://doi.org/10.3390/sym12081367 - 17 Aug 2020
Viewed by 490
Abstract
Motion and radiative transitions of an electron in a magnetic field under the influence of an external electromagnetic wave are studied for various confining conditions in semiconductor, graphene, in quantum wells, and relativistic generalization in terms of the Klein–Gordon equation are considered. In [...] Read more.
Motion and radiative transitions of an electron in a magnetic field under the influence of an external electromagnetic wave are studied for various confining conditions in semiconductor, graphene, in quantum wells, and relativistic generalization in terms of the Klein–Gordon equation are considered. In particular, the following problems are discussed. The so-called cyclotron resonance, which may appear in graphene, is studied with indication for appearance of the so-called frequency-halving. The problem is solved for two-dimensional massless charged particle, whose gapless nature is protected by sublattice symmetry. The exact classical calculation of this effect is undertaken in the framework of a 2D classical equation for a zero-mass electron. We also find an exact solution of the Schrödinger equation for charge carriers in semiconductors under the influence of an external magnetic field and in the field of electromagnetic wave with an account for their radiative transitions. Solutions of the relativistic Klein–Gordon equation in this configuration of electromagnetic fields are found as a certain generalization of the results obtained for the non-relativistic case. These results may serve as a first step for further efforts to find exact solutions of wave equations for quasiparticles in solid state structures in external fields. Full article
(This article belongs to the Special Issue Advances in Synchrotron and Undulator Radiation Studies)
Open AccessArticle
Coordinated Control and Dynamic Optimal Dispatch of Islanded Microgrid System Based on GWO
Symmetry 2020, 12(8), 1366; https://doi.org/10.3390/sym12081366 - 17 Aug 2020
Viewed by 498
Abstract
As an effective carrier of renewable distributed power sources, such as wind power and photovoltaics, microgrids have attracted increasing attention as the energy crisis becomes more serious. This paper focuses on the symmetry between the dynamic optimal dispatch and the coordinated control of [...] Read more.
As an effective carrier of renewable distributed power sources, such as wind power and photovoltaics, microgrids have attracted increasing attention as the energy crisis becomes more serious. This paper focuses on the symmetry between the dynamic optimal dispatch and the coordinated control of islanded microgrid to determine the optimal system configuration that can reliably meet energy needs. In order to solve energy management problems, operating costs and environmental benefits, a novel methodology that combines dynamic optimal dispatch and Grey Wolf Optimizer (GWO) is developed in this study to obtain the best output of different system components. This is to minimize the total cost of microgrid power generation and reduce pollutant emissions. In addition, a comparison is carried out between GWO and Particle Swarm Optimization (PSO). Moreover, the comparison between system configurations in six different scenarios and the effectiveness of GWO in solving optimization problems are presented. Finally, the simulation results show that GWO is more effective than PSO in determining the optimization parameters and the utilization rate of renewable energy in different scenarios is up to 92.96%. The simulations and experimental results verify the successful performance of the research method proposed in this study. Full article
(This article belongs to the Special Issue Symmetry in Renewable Energy and Power Systems)
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Open AccessReview
Characterisation and Manipulation of Polarisation Response in Plasmonic and Magneto-Plasmonic Nanostructures and Metamaterials
Symmetry 2020, 12(8), 1365; https://doi.org/10.3390/sym12081365 - 17 Aug 2020
Cited by 2 | Viewed by 1121
Abstract
Optical properties of metal nanostructures, governed by the so-called localised surface plasmon resonance (LSPR) effects, have invoked intensive investigations in recent times owing to their fundamental nature and potential applications. LSPR scattering from metal nanostructures is expected to show the symmetry of the [...] Read more.
Optical properties of metal nanostructures, governed by the so-called localised surface plasmon resonance (LSPR) effects, have invoked intensive investigations in recent times owing to their fundamental nature and potential applications. LSPR scattering from metal nanostructures is expected to show the symmetry of the oscillation mode and the particle shape. Therefore, information on the polarisation properties of the LSPR scattering is crucial for identifying different oscillation modes within one particle and to distinguish differently shaped particles within one sample. On the contrary, the polarisation state of light itself can be arbitrarily manipulated by the inverse designed sample, known as metamaterials. Apart from polarisation state, external stimulus, e.g., magnetic field also controls the LSPR scattering from plasmonic nanostructures, giving rise to a new field of magneto-plasmonics. In this review, we pay special attention to polarisation and its effect in three contrasting aspects. First, tailoring between LSPR scattering and symmetry of plasmonic nanostructures, secondly, manipulating polarisation state through metamaterials and lastly, polarisation modulation in magneto-plasmonics. Finally, we will review recent progress in applications of plasmonic and magneto-plasmonic nanostructures and metamaterials in various fields. Full article
(This article belongs to the Special Issue Recent Advances in Linear and Nonlinear Optics)
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Open AccessArticle
A Definition of Two-Dimensional Schoenberg Type Operators
Symmetry 2020, 12(8), 1364; https://doi.org/10.3390/sym12081364 - 17 Aug 2020
Viewed by 501
Abstract
In this paper, a way to build two-dimensional Schoenberg type operators with arbitrary knots or with equidistant knots, respectively, is presented. The order of approximation reached by these operators was studied by obtaining a Voronovskaja type asymptotic theorem and using estimates in terms [...] Read more.
In this paper, a way to build two-dimensional Schoenberg type operators with arbitrary knots or with equidistant knots, respectively, is presented. The order of approximation reached by these operators was studied by obtaining a Voronovskaja type asymptotic theorem and using estimates in terms of second-order moduli of continuity. Full article
Open AccessArticle
A Modified Median String Algorithm for Gene Regulatory Motif Classification
Symmetry 2020, 12(8), 1363; https://doi.org/10.3390/sym12081363 - 14 Aug 2020
Cited by 1 | Viewed by 645
Abstract
Consensus string is a significant feature of a deoxyribonucleic acid (DNA) sequence. The median string is one of the most popular exact algorithms to find DNA consensus. A DNA sequence is represented using the alphabet Σ= {a, c, g, [...] Read more.
Consensus string is a significant feature of a deoxyribonucleic acid (DNA) sequence. The median string is one of the most popular exact algorithms to find DNA consensus. A DNA sequence is represented using the alphabet Σ= {a, c, g, t}. The algorithm generates a set of all the 4l possible motifs or l-mers from the alphabet to search a motif of length l. Out of all possible l-mers, it finds the consensus. This algorithm guarantees to return the consensus but this is NP-complete and runtime increases with the increase in l-mer size. Using transitional probability from the Markov chain, the proposed algorithm symmetrically generates four subsets of l-mers. Each of the subsets contains a few l-mers starting with a particular letter. We used these reduced sets of l-mers instead of using 4ll-mers. The experimental result shows that the proposed algorithm produces a much lower number of l-mers and takes less time to execute. In the case of l-mer of length 7, the proposed system is 48 times faster than the median string algorithm. For l-mer of size 7, the proposed algorithm produces only 2.5% l-mer in comparison with the median string algorithm. While compared with the recently proposed voting algorithm, our proposed algorithm is found to be 4.4 times faster for a longer l-mer size like 9. Full article
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Open AccessArticle
How Opinion Leaders Affect Others on Seeking Truth in a Bounded Confidence Model
Symmetry 2020, 12(8), 1362; https://doi.org/10.3390/sym12081362 - 14 Aug 2020
Cited by 1 | Viewed by 596
Abstract
Seeking truth is an important objective of agents in social groups. Opinion leaders in social groups may help or hinder the other agents on seeking the truth by symmetric nature. This paper studies the impact of opinion leaders by considering four characteristics of [...] Read more.
Seeking truth is an important objective of agents in social groups. Opinion leaders in social groups may help or hinder the other agents on seeking the truth by symmetric nature. This paper studies the impact of opinion leaders by considering four characteristics of opinion leaders—reputation, stubbornness, appeal, and extremeness—on the truth-seeking behavior of agents based on a bounded confidence model. Simulations show that increasing the appeal of the leader whose opinion is opposite to the truth has a straightforward impact, i.e., it normally prevents the agents from finding the truth. On the other hand, it also makes the agents who start out close to the truth move away from the truth by increasing the group bound of confidence, if there is an opinion leader opposite to the truth. The results demonstrate that the opinion of the leader is important in affecting the normal agents to reach the truth. Furthermore, for some cases, small variations of the parameters defining the agents’ characteristics can lead to large scale changes in the social group. Full article
(This article belongs to the Section Physics and Symmetry)
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Open AccessArticle
Combination of the Single-Valued Neutrosophic Fuzzy Set and the Soft Set with Applications in Decision-Making
Symmetry 2020, 12(8), 1361; https://doi.org/10.3390/sym12081361 - 14 Aug 2020
Cited by 5 | Viewed by 619
Abstract
In this article, we propose a novel concept of the single-valued neutrosophic fuzzy soft set by combining the single-valued neutrosophic fuzzy set and the soft set. For possible applications, five kinds of operations (e.g., subset, equal, union, intersection, and complement) on single-valued neutrosophic [...] Read more.
In this article, we propose a novel concept of the single-valued neutrosophic fuzzy soft set by combining the single-valued neutrosophic fuzzy set and the soft set. For possible applications, five kinds of operations (e.g., subset, equal, union, intersection, and complement) on single-valued neutrosophic fuzzy soft sets are presented. Then, several theoretical operations of single-valued neutrosophic fuzzy soft sets are given. In addition, the first type for the fuzzy decision-making based on single-valued neutrosophic fuzzy soft set matrix is constructed. Finally, we present the second type by using the AND operation of the single-valued neutrosophic fuzzy soft set for fuzzy decision-making and clarify its applicability with a numerical example. Full article
Open AccessArticle
Shortest Path Solution of Trapezoidal Fuzzy Neutrosophic Graph Based on Circle-Breaking Algorithm
Symmetry 2020, 12(8), 1360; https://doi.org/10.3390/sym12081360 - 14 Aug 2020
Cited by 2 | Viewed by 538
Abstract
The shortest path problem is a topic of increasing interest in various scientific fields. The damage to roads and bridges caused by disasters makes traffic routes that can be accurately expressed become indeterminate. A neutrosophic set is a collection of the truth membership, [...] Read more.
The shortest path problem is a topic of increasing interest in various scientific fields. The damage to roads and bridges caused by disasters makes traffic routes that can be accurately expressed become indeterminate. A neutrosophic set is a collection of the truth membership, indeterminacy membership, and falsity membership of the constituent elements. It has a symmetric form and indeterminacy membership is their axis of symmetry. In uncertain environments, the neutrosophic number can more effectively express the edge distance. The objectives in this study are to solve the shortest path problem of the neutrosophic graph with an edge distance expressed using trapezoidal fuzzy neutrosophic numbers (TrFNN) and resolve the edge distance according to the score and exact functions based on the TrFNN. Accordingly, the use of a circle-breaking algorithm is proposed to solve the shortest path problem and estimate the shortest distance. The feasibility of this method is verified based on two examples, and the rationality and effectiveness of the approach are evaluated by comparing it with the Dijkstra and Bellman algorithms. Full article
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Open AccessFeature PaperArticle
Discrete-Inverse Optimal Control Applied to the Ball and Beam Dynamical System: A Passivity-Based Control Approach
Symmetry 2020, 12(8), 1359; https://doi.org/10.3390/sym12081359 - 14 Aug 2020
Cited by 3 | Viewed by 643
Abstract
This express brief deals with the problem of the state variables regulation in the ball and beam system by applying the discrete-inverse optimal control approach. The ball and beam system model is defined by a set of four-order nonlinear differential equations that are [...] Read more.
This express brief deals with the problem of the state variables regulation in the ball and beam system by applying the discrete-inverse optimal control approach. The ball and beam system model is defined by a set of four-order nonlinear differential equations that are discretized using the forward difference method. The main advantages of using the discrete-inverse optimal control to regulate state variables in dynamic systems are (i) the control input is an optimal signal as it guarantees the minimum of the Hamiltonian function, (ii) the control signal makes the dynamical system passive, and (iii) the control input ensures asymptotic stability in the sense of Lyapunov. Numerical simulations in the MATLAB environment allow demonstrating the effectiveness and robustness of the studied control design for state variables regulation with a wide gamma of dynamic behaviors as a function of the assigned control gains. Full article
(This article belongs to the Special Issue Advances in Nonlinear, Discrete, Continuous and Hamiltonian Systems)
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Open AccessArticle
Simulation of Boiling Heat Transfer at Different Reduced Temperatures with an Improved Pseudopotential Lattice Boltzmann Method
Symmetry 2020, 12(8), 1358; https://doi.org/10.3390/sym12081358 - 14 Aug 2020
Viewed by 550
Abstract
The pseudopotential Lattice Boltzmann Method has attracted much attention in the recent years for the simulation of boiling heat transfer. Many studies have been published recently for the simulation of the bubble cycle (nucleation, growth and departure from a heated surface). This paper [...] Read more.
The pseudopotential Lattice Boltzmann Method has attracted much attention in the recent years for the simulation of boiling heat transfer. Many studies have been published recently for the simulation of the bubble cycle (nucleation, growth and departure from a heated surface). This paper puts forward two-dimensional simulations of bubble nucleation, growth and departure using an improved pseudopotential Lattice Boltzmann Model from the literature at different reduced temperatures, Tr=0.76 and Tr=0.86. Two different models using the Bhatnagar–Gross–Krook (BGK) and the Multiple-Relaxation-Time (MRT) collision operators with appropriate forcing schemes are used. The results for pool boiling show that the bubbles exhibit axial symmetry during growth and departure. Numerical results of departure diameter and release period for pool boiling are compared against empirical correlations from the literature by varying the gravitational acceleration. Reasonable agreement is observed. Nucleate boiling trends with heat flux are also captured by the simulations. Numerical results of flow boiling simulations are compared by varying the Reynolds number for both reduced temperatures with the MRT model. It was found that the departure diamenter and release period decreases with the increase of the Reynolds number. These results are a direct effect of the drag force. Proper conclusions are commented at the end of the paper. Full article
(This article belongs to the Special Issue Liquid-Solid Interfacial Phenomena on Complex Surfaces)
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Open AccessArticle
Supplier Selection in the Nuclear Power Industry with an Integrated ANP-TODIM Method under Z-Number Circumstances
Symmetry 2020, 12(8), 1357; https://doi.org/10.3390/sym12081357 - 14 Aug 2020
Cited by 1 | Viewed by 688
Abstract
Under the double pressure of global energy consumption and climate change, nuclear power has become a low-carbon alternative energy source that could transform the energy structure of the globe. In the nuclear power industry, selecting suitable suppliers plays a significant role in improving [...] Read more.
Under the double pressure of global energy consumption and climate change, nuclear power has become a low-carbon alternative energy source that could transform the energy structure of the globe. In the nuclear power industry, selecting suitable suppliers plays a significant role in improving the overall performance of nuclear power projects. Along with this symmetrical impact, this paper aims to develop a multistage decision-support framework to determine the optimal nuclear power equipment supplier, which is constructed in the context of Z-number information. Concretely, the Analytic Network Process (ANP) and Tomada de Decisão Iterativa Multicritério (TODIM) are extended by Z-numbers symmetrically—namely, Z-ANP and Z-TODIM. Z-ANP is first applied to analyze the symmetrical interdependence of criteria, so as to accurately determine the criterion weights. Further, the ranking of alternatives is obtained by Z-TODIM, which sufficiently considers the risk preference and psychological states of decision-makers. Finally, a practical case of nuclear-grade cable procurement in the Karachi 2-3 international nuclear power project is performed to illustrate the practicality of the proposed method, and its robustness and superiority are proven by comparing it with current representative approaches. Full article
(This article belongs to the Section Mathematics and Symmetry)
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Open AccessArticle
Non-Linear Behaviors of Transient Periodic Plasma Dynamics in a Multifractal Paradigm
Symmetry 2020, 12(8), 1356; https://doi.org/10.3390/sym12081356 - 13 Aug 2020
Viewed by 476
Abstract
In a multifractal paradigm of motion, nonlinear behavior of transient periodic plasmas, such as Schrodinger and hydrodynamic-type regimes, at various scale resolutions are represented. In a stationary case of Schrodinger-type regimes, the functionality of “hidden symmetry” of the group SL (2R) is implied [...] Read more.
In a multifractal paradigm of motion, nonlinear behavior of transient periodic plasmas, such as Schrodinger and hydrodynamic-type regimes, at various scale resolutions are represented. In a stationary case of Schrodinger-type regimes, the functionality of “hidden symmetry” of the group SL (2R) is implied though Riccati–Gauge different “synchronization modes” among period plasmas’ structural units. These modes, expressed in the form of period doubling, damped oscillations, quasi-periodicity, intermittences, etc., mimic the various non-linear behaviors of the transient plasma dynamics similar to chaos transitions scenarios. In the hydrodynamic regime, the non-Newtonian behavior of the transient plasma dynamics can be corelated with the viscous tension tensor of the multifractal type. The predictions given by our theoretical model are confronted with experimental data depicting electronic and ionic oscillatory dynamics seen by implementing the Langmuir probe technique on transient plasmas generated by ns-laser ablation of nickel and manganese targets. Full article
(This article belongs to the Special Issue Scale Relativity and Fractal Space-Time Theory)
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Open AccessArticle
On Solutions of the Initial Value Problem for the Three-Term Fractional Differential Equation with Caputo Derivatives
Symmetry 2020, 12(8), 1355; https://doi.org/10.3390/sym12081355 - 13 Aug 2020
Viewed by 478
Abstract
In this paper, two forms of an exact solution and an analytical–numerical solution of the three-term fractional differential equation with the Caputo derivatives are presented. The Prabhakar function and an asymptotic expansion are utilized to present the double series solution. Using properties of [...] Read more.
In this paper, two forms of an exact solution and an analytical–numerical solution of the three-term fractional differential equation with the Caputo derivatives are presented. The Prabhakar function and an asymptotic expansion are utilized to present the double series solution. Using properties of the Pochhammer symbol, a solution is obtained in the form of an infinite series of generalized hypergeometric functions. As an alternative for the series solutions of the fractional commensurate equation, a solution received by an analytical–numerical method based on the Laplace transform technique is proposed. This solution is obtained in the form of a finite sum of the Mittag-Leffler type functions. Numerical examples and a discussion are presented. Full article
(This article belongs to the Special Issue Ordinary and Partial Differential Equations: Theory and Applications)
Open AccessReview
Cloud Computing Services: Taxonomy of Discovery Approaches and Extraction Solutions
Symmetry 2020, 12(8), 1354; https://doi.org/10.3390/sym12081354 - 13 Aug 2020
Viewed by 554
Abstract
Cloud computing offers new features of sharing resources and applications to meet users’ computing requirements. It is a model by which the users can access computing resources as services offered on the Internet (cloud services). Cloud service providers offer a highly diverse range [...] Read more.
Cloud computing offers new features of sharing resources and applications to meet users’ computing requirements. It is a model by which the users can access computing resources as services offered on the Internet (cloud services). Cloud service providers offer a highly diverse range of asymmetric cloud services with heterogeneous features, which makes it difficult for the users to find the best service that fits his needs. Many research studies have been done on cloud service discovery, and several models and solutions that applied different techniques have been proposed. This paper aims at presenting the state of the art in the area of cloud services discovery by exploring the current approaches, techniques, and models. Furthermore, it proposes a taxonomy of cloud service discovery approaches. An integrative review approach was used to explore the related literature. Then, by analyzing the existing cloud service discovery solutions, a taxonomy of discovery approaches was suggested based on several perspectives including the discovery environment and the discovery process methods. The proposed taxonomy allows easily classifying and comparing cloud services discovery solutions. Moreover, it may reveal issues and gaps for further research and expose new insights for more innovative and effective cloud services discovery solutions. Full article
(This article belongs to the Section Computer and Engineering Science and Symmetry)
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Open AccessArticle
Optimized Design for NB-LDPC-Coded High-Order CPM: Power and Iterative Efficiencies
Symmetry 2020, 12(8), 1353; https://doi.org/10.3390/sym12081353 - 13 Aug 2020
Viewed by 435
Abstract
In this paper, a non-binary low-density parity-check (NB-LDPC) coded high-order continuous phase modulation (CPM) system is designed and optimized to improve power and iterative efficiencies. Firstly, the minimum squared normalized Euclidean distance and the 99% double-sided power bandwidth are introduced to design a [...] Read more.
In this paper, a non-binary low-density parity-check (NB-LDPC) coded high-order continuous phase modulation (CPM) system is designed and optimized to improve power and iterative efficiencies. Firstly, the minimum squared normalized Euclidean distance and the 99% double-sided power bandwidth are introduced to design a competitive CPM, improving its power efficiency under a given code rate and spectral efficiency. Secondly, a three-step method based on extrinsic information transfer (EXIT) and entropy theory is used to design NB-LDPC codes, which reduces the convergence threshold approximately 0.42 and 0.58 dB compared with the candidate schemes. Thirdly, an extrinsic information operation is proposed to address the positive feedback issue in iterative detection and decoding and the value of bit error rate (BER) can approximately be reduced by 5×103. Finally, iteration optimization employing the EXIT chart and mutual information between demodulation and decoding is performed to achieve a suitable tradeoff for the communication reliability and iterative decoding delay. Simulation results show that the resulting scheme provides an approximately 3.95 dB coding gain compared to the uncoded CPM and achieves approximately 0.5 and 0.7 dB advantages compared with the candidate schemes. The resulting NB-LDPC-coded high-order CPM for a given code rate and spectral efficiency converges earlier into a turbo cliff region compared with other competitors and significantly improves power and iterative efficiencies. Full article
(This article belongs to the Special Issue Iterative Numerical Functional Analysis with Applications)
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Open AccessArticle
Environmental Governance Cost Prediction of Transportation Industry by Considering the Technological Constraints
Symmetry 2020, 12(8), 1352; https://doi.org/10.3390/sym12081352 - 12 Aug 2020
Cited by 2 | Viewed by 447
Abstract
In order to solve the problem of environmental governance investment planning in the transportation industry, a cost prediction model is proposed under technological constraints, where the input output indictors emphasizes the flexibility of prediction and its characters are asymmetric, while the constructs of [...] Read more.
In order to solve the problem of environmental governance investment planning in the transportation industry, a cost prediction model is proposed under technological constraints, where the input output indictors emphasizes the flexibility of prediction and its characters are asymmetric, while the constructs of prediction model focuses on the standardization and its characters are symmetrical. The basic principle of the cost prediction model is based on an extended belief rule-based (EBRB) system to model the input-output relationship in investment planning, and a parameter learning model to improve the accuracy of the EBRB system. Additionally, the technological innovation factors are also embedded in the cost prediction model to investigate the influence of technology-related outcomes on investment planning. Finally, based on the data of environmental governance in China’s transportation industry from 2003 to 2016, the cost of transportation industry environmental management in China’s thirty provinces from 2017 to 2033 is predicted under the constraints of technological innovation. Results show that: (1) the accuracy of the proposed cost prediction model is higher than some existing cost prediction methods; (2) the predicted environmental governance costs have a significant regional difference; (3) the upgrading of technological innovation is conducive to saving the future environmental governance costs of the transportation industry in some provinces. In addition to the above results, the present study provides model supports and policy references for government decision makers in transportation industry-related environmental cost planning. Full article
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Open AccessArticle
Fuzzy Analytic Hierarchy Process-Based Multi-Criteria Decision Making for Universities Ranking
Symmetry 2020, 12(8), 1351; https://doi.org/10.3390/sym12081351 - 12 Aug 2020
Viewed by 658
Abstract
High competition between universities has been increasing over the years, and stimulates higher education institutions to attain higher positions in the ranking list. Ranking is an important performance indicator of university status evaluation, and therefore plays an essential role in students’ university selection. [...] Read more.
High competition between universities has been increasing over the years, and stimulates higher education institutions to attain higher positions in the ranking list. Ranking is an important performance indicator of university status evaluation, and therefore plays an essential role in students’ university selection. The ranking of universities has been carried out using different techniques. Main goal of decision processes in real-life problems is to deal with the symmetry or asymmetry of different types of information. We consider that multi-criteria decision making (MCDM) is well applicable to symmetric information modelling. Analytic hierarchy process (AHP) is a well-known technique of MCDM discipline, and is based on pairwise comparisons of criteria/alternatives for alternatives’ evaluation. Unfortunately, the classical AHP method is unable to deal with imprecise, vague, and subjective information used for the decision making process in complex problems. So, introducing a more advanced tool for decision making under such circumstances is inevitable. In this paper, fuzzy analytic hierarchy process (FAHP) is applied for the comparison and ranking of performances of five UK universities, according to four criteria. The criteria used for the evaluation of universities’ performances are teaching, research, citations, and international outlook. It is proven that applying FAHP approach makes the system consistent, and by the calculation of coefficient of variation for all alternatives, it becomes possible to rank them in prioritized order. Full article
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