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Symmetry, Volume 12, Issue 7 (July 2020) – 97 articles

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Open AccessFeature PaperArticle
Numerical Simulation of Dendritic Pattern Formation in an Isotropic Crystal Growth Model on Curved Surfaces
Symmetry 2020, 12(7), 1155; https://doi.org/10.3390/sym12071155 (registering DOI) - 11 Jul 2020
Abstract
In this paper, we present several numerical simulation results of dendritic pattern formation using an isotropic crystal growth model, which is based on phase-field modeling, on curved surfaces. An explicit time-stepping method is used and the direct computing method to the Laplace–Beltrami operator, [...] Read more.
In this paper, we present several numerical simulation results of dendritic pattern formation using an isotropic crystal growth model, which is based on phase-field modeling, on curved surfaces. An explicit time-stepping method is used and the direct computing method to the Laplace–Beltrami operator, which employs the point centered triangulation approximating Laplacian over the discretized surface with a triangular mesh, is adopted. Numerical simulations are performed not only on simple but also on complex surfaces with various curvatures, and the proposed method can simulate dendritic growth on complex surfaces. In particular, ice crystal growth simulation results on aircraft fuselage or metal bell-shaped curved surfaces are provided in order to demonstrate the practical relevance to our dendrite growth model. Furthermore, we perform several numerical parameter tests to obtain a best fitted set of parameters on simple surfaces. Finally, we apply this set of parameters to numerical simulation on complex surfaces. Full article
Open AccessArticle
Novel Numerical Approach Based on Modified Extended Cubic B-Spline Functions for Solving Non-Linear Time-Fractional Telegraph Equation
Symmetry 2020, 12(7), 1154; https://doi.org/10.3390/sym12071154 (registering DOI) - 10 Jul 2020
Abstract
The telegraph model describes that the current and voltage waves can be reflected on a wire, that symmetrical wave patterns can form along a line. A numerical study of these voltage and current waves on a transferral line has been proposed via a [...] Read more.
The telegraph model describes that the current and voltage waves can be reflected on a wire, that symmetrical wave patterns can form along a line. A numerical study of these voltage and current waves on a transferral line has been proposed via a modified extended cubic B-spline (MECBS) method. The B-spline functions have the flexibility and high order accuracy to approximate the solutions. These functions also preserve the symmetrical property. The MECBS and Crank Nicolson technique are employed to find out the solution of the non-linear time fractional telegraph equation. The time direction is discretized in the Caputo sense while the space dimension is discretized by the modified extended cubic B-spline. The non-linearity in the equation is linearized by Taylor’s series. The proposed algorithm is unconditionally stable and convergent. The numerical examples are displayed to verify the authenticity and implementation of the method. Full article
(This article belongs to the Special Issue Advanced Calculus in Problems with Symmetry)
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Open AccessArticle
Microsolvation of Histidine—A Theoretical Study of Intermolecular Interactions Based on AIM and SAPT Approaches
Symmetry 2020, 12(7), 1153; https://doi.org/10.3390/sym12071153 (registering DOI) - 10 Jul 2020
Abstract
Histidine is unique among amino acids because of its rich tautomeric properties. It participates in essential enzymatic centers, such as catalytic triads. The main aim of the study is the modeling of the change of molecular properties between the gas phase and solution [...] Read more.
Histidine is unique among amino acids because of its rich tautomeric properties. It participates in essential enzymatic centers, such as catalytic triads. The main aim of the study is the modeling of the change of molecular properties between the gas phase and solution using microsolvation models. We investigate histidine in its three protonation states, microsolvated with 1:6 water molecules. These clusters are studied computationally, in the gas phase and with water as a solvent (Polarizable Continuum Model, PCM) within the Density Functional Theory (DFT) framework. The structural analysis reveals the presence of intra- and intermolecular hydrogen bonds. The Atoms-in-Molecules (AIM) theory is employed to determine the impact of solvation on the charge flow within the histidine, with emphasis on the similarity of the two imidazole nitrogen atoms—topologically not equivalent, they are revealed as electronically similar due to the heterocyclic ring aromaticity. Finally, the Symmetry-Adapted Perturbation Theory (SAPT) is used to examine the stability of the microsolvation clusters. While electrostatic and exchange terms dominate in magnitude over polarization and dispersion, the sum of electrostatic and exchange term is close to zero. This makes polarization the factor governing the actual interaction energy. The most important finding of this study is that even with microsolvation, the polarization induced by the presence of implicit solvent is still significant. Therefore, we recommend combined approaches, mixing explicit water molecules with implicit models. Full article
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Open AccessArticle
Hesitant Fuzzy SWARA-Complex Proportional Assessment Approach for Sustainable Supplier Selection (HF-SWARA-COPRAS)
Symmetry 2020, 12(7), 1152; https://doi.org/10.3390/sym12071152 (registering DOI) - 09 Jul 2020
Viewed by 148
Abstract
The selection of sustainable supplier is an extremely important for sustainable supply chain management (SSCM). The assessment process of sustainable supplier selection is a complicated task for decision experts due to involvement of several qualitative and quantitative criteria. As the uncertainty is commonly [...] Read more.
The selection of sustainable supplier is an extremely important for sustainable supply chain management (SSCM). The assessment process of sustainable supplier selection is a complicated task for decision experts due to involvement of several qualitative and quantitative criteria. As the uncertainty is commonly occurred in sustainable supplier selection problem and hesitant fuzzy set (HFS), an improvement of Fuzzy Set (FS), has been proved as one of the efficient and superior ways to express the uncertain information arisen in practical problems. The present study proposes a novel framework based on COPRAS (Complex Proportional Assessment) method and SWARA (Step-wise Weight Assessment Ratio Analysis) approach to evaluate and select the desirable sustainable supplier within the HFSs context. In the proposed method, an extended SWARA method is employed for determining the criteria weights based on experts’ preferences. Next, to illustrate the efficiency and practicability of the proposed methodology, an empirical case study of sustainable supplier selection problem is taken under Hesitant Fuzzy (HF) environment. Further, sensitivity analysis is performed to check the stability of the presented methodology. At last, a comparison with existing methods is conducted to verify the strength of the obtained result. The final outcomes confirm that the developed framework is more consistent and powerful than other existing approaches. Full article
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Open AccessAddendum
Addendum: Susanto, H; Karjanto, N; Zulkarnain; Nusantara, T; Widjanarko, T. Soliton and Breather Splitting on Star Graphs from Tricrystal Josephson Junctions. Symmetry 2019, 11, 271
Symmetry 2020, 12(7), 1151; https://doi.org/10.3390/sym12071151 (registering DOI) - 09 Jul 2020
Viewed by 145
Abstract
The authors would like to make the following addenda and correction to their paper [...] Full article
Open AccessArticle
Symmetric Potentiometric Cells for the Measurement of Unified pH Values
Symmetry 2020, 12(7), 1150; https://doi.org/10.3390/sym12071150 (registering DOI) - 09 Jul 2020
Viewed by 180
Abstract
A unified pH scale of absolute values (pHabs scale) enables the comparison of acidities in different solvents. To date, very few different experimental setups have been used for the measurement of values on this scale. The article describes the design and performance [...] Read more.
A unified pH scale of absolute values (pHabs scale) enables the comparison of acidities in different solvents. To date, very few different experimental setups have been used for the measurement of values on this scale. The article describes the design and performance of the different symmetric cells used for unified pH measurement by several institutions. Well-established and reliable standard aqueous buffer solutions are the first step of method validation necessary to achieve a robust metrological level for more complex media. The pH of aqueous standard buffers was measured by differential potentiometry, where the potential between two glass electrodes is measured directly. All the tested electrochemical cells prove to be suitable for unified pH measurements. This validation highlights that the method is, to a large extent, independent of the used equipment, including the cell geometry. The inherent symmetry of the cell design helps to reduce the experimental workload and improve the accuracy of obtained results. Full article
(This article belongs to the Special Issue Symmetry in Acid-Base Chemistry)
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Open AccessArticle
Exact Likelihood Inference for an Exponential Parameter under Generalized Adaptive Progressive Hybrid Censoring
Symmetry 2020, 12(7), 1149; https://doi.org/10.3390/sym12071149 (registering DOI) - 09 Jul 2020
Viewed by 128
Abstract
In this paper, we propose a new type censoring scheme named a generalized adaptive progressive hybrid censoring scheme (GenAdPrHyCS). In this new type censoring scheme, the experiment is assured to stop at a pre-assigned time. This censoring scheme is designed to correct the [...] Read more.
In this paper, we propose a new type censoring scheme named a generalized adaptive progressive hybrid censoring scheme (GenAdPrHyCS). In this new type censoring scheme, the experiment is assured to stop at a pre-assigned time. This censoring scheme is designed to correct the drawbacks in the AdPrHyCS. Furthermore, we discuss inference for one parameter exponential distribution (ExD) under GenAdPrHyCS. We derive the moment generating function of the maximum likelihood estimator (MLE) of scale parameter of ExD and the resulting lower confidence bound under GenAdPrHyCS. Full article
(This article belongs to the Section Mathematics and Symmetry)
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Open AccessArticle
Clustering Stock Performance Considering Investor Preferences Using a Fuzzy Inference System
Symmetry 2020, 12(7), 1148; https://doi.org/10.3390/sym12071148 (registering DOI) - 09 Jul 2020
Viewed by 157
Abstract
The fact that many stocks are traded in the marketplace makes the selection process of choosing the right stocks for investment crucial and challenging. In the literature on stock selection, cluster analysis-based methods have usually been used to group and to determine the [...] Read more.
The fact that many stocks are traded in the marketplace makes the selection process of choosing the right stocks for investment crucial and challenging. In the literature on stock selection, cluster analysis-based methods have usually been used to group and to determine the best stock for investment. Many established cluster analysis-based methods often cluster stocks under consideration using the average of the variables, where stocks with similar scores are concluded as having the same performances. Nevertheless, the performance results obtained do not reflect the actual performance of the stocks. Depending only on the average score of each variable is inefficient, as market situations usually involve uncertain extreme values. Moreover, when grouping stock performance, the established clustering methods assume that investors’ selection preferences are single and unclear, when actually, in reality, investors’ selection preferences vary; some investors are pessimistic, while others may be more optimistic. Due to this issue, this paper presents a novel fuzzy clustering method using a fuzzy inference system to flexibly assess the consistent evaluations given to stock performance that differentiate between pessimistic and optimistic investors that are symmetrical in nature. All variables considered in this study were defined in terms of linguistic inputs, where the consensus among them was aggregated using rule bases. These rule bases provide assistance in obtaining the linguistic output, which is the actual performance of the stock. Next, each stock under consideration was ranked using the proposed novel stock selection strategy based on investors’ confidence levels and preferences. The proposed method was then applied to a case study of 30 Syariah stocks listed on the Malaysian stock exchange, where the results obtained were empirically validated with established cluster analysis-based methods. Full article
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Open AccessArticle
Impact of Feature Selection Methods on the Predictive Performance of Software Defect Prediction Models: An Extensive Empirical Study
Symmetry 2020, 12(7), 1147; https://doi.org/10.3390/sym12071147 (registering DOI) - 09 Jul 2020
Viewed by 203
Abstract
Feature selection (FS) is a feasible solution for mitigating high dimensionality problem, and many FS methods have been proposed in the context of software defect prediction (SDP). Moreover, many empirical studies on the impact and effectiveness of FS methods on SDP models often [...] Read more.
Feature selection (FS) is a feasible solution for mitigating high dimensionality problem, and many FS methods have been proposed in the context of software defect prediction (SDP). Moreover, many empirical studies on the impact and effectiveness of FS methods on SDP models often lead to contradictory experimental results and inconsistent findings. These contradictions can be attributed to relative study limitations such as small datasets, limited FS search methods, and unsuitable prediction models in the respective scope of studies. It is hence critical to conduct an extensive empirical study to address these contradictions to guide researchers and buttress the scientific tenacity of experimental conclusions. In this study, we investigated the impact of 46 FS methods using Naïve Bayes and Decision Tree classifiers over 25 software defect datasets from 4 software repositories (NASA, PROMISE, ReLink, and AEEEM). The ensuing prediction models were evaluated based on accuracy and AUC values. Scott–KnottESD and the novel Double Scott–KnottESD rank statistical methods were used for statistical ranking of the studied FS methods. The experimental results showed that there is no one best FS method as their respective performances depends on the choice of classifiers, performance evaluation metrics, and dataset. However, we recommend the use of statistical-based, probability-based, and classifier-based filter feature ranking (FFR) methods, respectively, in SDP. For filter subset selection (FSS) methods, correlation-based feature selection (CFS) with metaheuristic search methods is recommended. For wrapper feature selection (WFS) methods, the IWSS-based WFS method is recommended as it outperforms the conventional SFS and LHS-based WFS methods. Full article
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Open AccessArticle
A Novel Method for Detection of Tuberculosis in Chest Radiographs Using Artificial Ecosystem-Based Optimisation of Deep Neural Network Features
Symmetry 2020, 12(7), 1146; https://doi.org/10.3390/sym12071146 (registering DOI) - 08 Jul 2020
Viewed by 178
Abstract
Tuberculosis (TB) is is an infectious disease that generally attacks the lungs and causes death for millions of people annually. Chest radiography and deep-learning-based image segmentation techniques can be utilized for TB diagnostics. Convolutional Neural Networks (CNNs) has shown advantages in medical image [...] Read more.
Tuberculosis (TB) is is an infectious disease that generally attacks the lungs and causes death for millions of people annually. Chest radiography and deep-learning-based image segmentation techniques can be utilized for TB diagnostics. Convolutional Neural Networks (CNNs) has shown advantages in medical image recognition applications as powerful models to extract informative features from images. Here, we present a novel hybrid method for efficient classification of chest X-ray images. First, the features are extracted from chest X-ray images using MobileNet, a CNN model, which was previously trained on the ImageNet dataset. Then, to determine which of these features are the most relevant, we apply the Artificial Ecosystem-based Optimization (AEO) algorithm as a feature selector. The proposed method is applied to two public benchmark datasets (Shenzhen and Dataset 2) and allows them to achieve high performance and reduced computational time. It selected successfully only the best 25 and 19 (for Shenzhen and Dataset 2, respectively) features out of about 50,000 features extracted with MobileNet, while improving the classification accuracy (90.2% for Shenzen dataset and 94.1% for Dataset 2). The proposed approach outperforms other deep learning methods, while the results are the best compared to other recently published works on both datasets. Full article
Open AccessArticle
On Certain Covering Properties and Minimal Sets of Bigeneralized Topological Spaces
Symmetry 2020, 12(7), 1145; https://doi.org/10.3390/sym12071145 (registering DOI) - 08 Jul 2020
Viewed by 117
Abstract
We introduce q-Lindelöf, u-Lindelöf, p-Lindelöf, s-Lindelöf, q-countably-compact, u-countably-compact, p-countably-compact, and s-countably-compact as new covering concepts in bigeneralized topological spaces via q-open sets and u-open sets in bigeneralized topological spaces. Relationships between them are [...] Read more.
We introduce q-Lindelöf, u-Lindelöf, p-Lindelöf, s-Lindelöf, q-countably-compact, u-countably-compact, p-countably-compact, and s-countably-compact as new covering concepts in bigeneralized topological spaces via q-open sets and u-open sets in bigeneralized topological spaces. Relationships between them are studied. As two symmetries relationships, we show that q-Lindelöf and u-Lindelöf are equivalent concepts, and that q-countably-compact and u-countably-compact are equivalent concepts. We focus on continuity images of these covering properties. Finally, we define and investigate minimal q-open set, minimal u-open set, and minimal s-open sets as three new types of minimality in bigeneralized topological spaces. Full article
Open AccessArticle
Biquaternionic Dirac Equation Predicts Zero Mass for Majorana Fermions
Symmetry 2020, 12(7), 1144; https://doi.org/10.3390/sym12071144 (registering DOI) - 08 Jul 2020
Viewed by 124
Abstract
A biquaternionic version of the Dirac Equation is introduced, with a procedure for converting four-component spinors to elements of the Pauli algebra. In this version, mass appears as a coefficient between the 4-gradient of a spinor and its image under an outer automorphism [...] Read more.
A biquaternionic version of the Dirac Equation is introduced, with a procedure for converting four-component spinors to elements of the Pauli algebra. In this version, mass appears as a coefficient between the 4-gradient of a spinor and its image under an outer automorphism of the Pauli algebra. The charge conjugation operator takes a particulary simple form in this formulation and switches the sign of the mass coefficient, so that for a solution invariant under charge conjugation the mass has to equal zero. The multiple of the charge conjugation operator by the imaginary unit turns out to be a complex Lorentz transformation. It commutes with the outer automorphism, while the charge conjugation operator itself anticommutes with it, providing a second more algebraic proof of the main theorem. Considering the Majorana equation, it is shown that non-zero mass of its solution is imaginary. Full article
(This article belongs to the Special Issue Symmetry in High Energy Physics)
Open AccessArticle
An Improved Fast Affine Motion Estimation Based on Edge Detection Algorithm for VVC
Symmetry 2020, 12(7), 1143; https://doi.org/10.3390/sym12071143 (registering DOI) - 08 Jul 2020
Viewed by 151
Abstract
As a newly proposed video coding standard, Versatile Video Coding (VVC) has adopted some revolutionary techniques compared to High Efficiency Video Coding (HEVC). The multiple-mode affine motion compensation (MM-AMC) adopted by VVC saves approximately 15%-25% Bjøntegaard Delta Bitrate (BD-BR), with an inevitable increase [...] Read more.
As a newly proposed video coding standard, Versatile Video Coding (VVC) has adopted some revolutionary techniques compared to High Efficiency Video Coding (HEVC). The multiple-mode affine motion compensation (MM-AMC) adopted by VVC saves approximately 15%-25% Bjøntegaard Delta Bitrate (BD-BR), with an inevitable increase of encoding time. This paper gives an overview of both the 4-parameter affine motion model and the 6-parameter affine motion model, analyzes their performances, and proposes improved algorithms according to the symmetry of iterative gradient descent for fast affine motion estimation. Finally, the proposed algorithms and symmetric MM-AMC flame of VTM-7.0 are compared. The results show that the proposed algorithms save 6.65% total encoding time on average, which saves approximately 30% encoding time of affine motion compensation. Full article
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Open AccessArticle
Specific Structure and Properties of Composite Membranes Based on the Torlon® (Polyamide-imide)/Layered Perovskite Oxide
Symmetry 2020, 12(7), 1142; https://doi.org/10.3390/sym12071142 (registering DOI) - 08 Jul 2020
Viewed by 67
Abstract
The use of perovskite-type layered oxide K2La2Ti3O10 (Per) as a modifier of the Torlon® polyamide-imide (PAI) membrane has led to the formation of an specific structure of a dense nonsymmetrical film, namely, a thin perovskite-enriched [...] Read more.
The use of perovskite-type layered oxide K2La2Ti3O10 (Per) as a modifier of the Torlon® polyamide-imide (PAI) membrane has led to the formation of an specific structure of a dense nonsymmetrical film, namely, a thin perovskite-enriched layer (3–5 μm) combined with the polymer matrix (~30 μm). The PAI/Per membrane structure was studied by SEM in combination with energy dispersive microanalysis of the elemental composition which illustrated different compositions of top and bottom surfaces of the perovskite-containing membranes. Measurement of water and alcohol contact angles and calculation of surface tension revealed hydrophilization of the membrane surface enriched with perovskite. The transport properties of the nonsymmetrical PAI/Per membranes were studied in the pervaporation of ethanol‒ethyl acetate mixture. The inclusion of 2 wt.% Per in the PAI gives a membrane with a high separation factor and increased total flux. Full article
(This article belongs to the Special Issue Asymmetric Membranes)
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Open AccessArticle
Durrmeyer-Type Generalization of Parametric Bernstein Operators
Symmetry 2020, 12(7), 1141; https://doi.org/10.3390/sym12071141 (registering DOI) - 08 Jul 2020
Viewed by 63
Abstract
In this paper, we present a Durrmeyer type generalization of parametric Bernstein operators. Firstly, we study the approximation behaviour of these operators including a local and global approximation results and the rate of approximation for the Lipschitz type space. The Voronovskaja type asymptotic [...] Read more.
In this paper, we present a Durrmeyer type generalization of parametric Bernstein operators. Firstly, we study the approximation behaviour of these operators including a local and global approximation results and the rate of approximation for the Lipschitz type space. The Voronovskaja type asymptotic formula and the rate of convergence of functions with derivatives of bounded variation are established. Finally, the theoretical results are demonstrated by using MAPLE software. Full article
(This article belongs to the Special Issue Polynomials: Special Polynomials and Number-Theoretical Applications)
Open AccessArticle
The Exponential-Centred Skew-Normal Distribution
Symmetry 2020, 12(7), 1140; https://doi.org/10.3390/sym12071140 (registering DOI) - 08 Jul 2020
Viewed by 140
Abstract
Data from some research fields tend to exhibit a positive skew. For example, in experimental psychology, reaction times (RTs) are characterised as being positively skewed. However, it is not unlikely that RTs can take a normal or, even, a negative shape. While the [...] Read more.
Data from some research fields tend to exhibit a positive skew. For example, in experimental psychology, reaction times (RTs) are characterised as being positively skewed. However, it is not unlikely that RTs can take a normal or, even, a negative shape. While the Ex-Gaussian distribution is suitable to model positively skewed data, it cannot cope with negatively skewed data. This manuscript proposes a distribution that can deal with both negative and positive skews: the exponential-centred skew-normal (ECSN) distribution. The mathematical properties of the proposed distribution are reported, and it is featured in two non-synthetic datasets. Full article
Open AccessArticle
The Statistical Damage Constitutive Model of the Mechanical Properties of Alkali-Resistant Glass Fiber Reinforced Concrete
Symmetry 2020, 12(7), 1139; https://doi.org/10.3390/sym12071139 (registering DOI) - 08 Jul 2020
Viewed by 52
Abstract
Alkali-resistant glass fiber reinforced concrete (AR-GFRC) has greatly improved in terms of tensile strength, toughness, durability, and reduction of cracking, which has been proven by testing. However, the constitutive relationship of fiber reinforced concrete under complicated stress represents a complex theoretical problem. In [...] Read more.
Alkali-resistant glass fiber reinforced concrete (AR-GFRC) has greatly improved in terms of tensile strength, toughness, durability, and reduction of cracking, which has been proven by testing. However, the constitutive relationship of fiber reinforced concrete under complicated stress represents a complex theoretical problem. In order to investigate the microscopic damage evolution and failure mechanism of AR-GFRC, the meso-statistical damage theory, microcontinuum theory, and composite material theory were considered, and uniaxial tensile tests of two types of AR-GFRC were conducted. A new damage variable expression of the AR-GFRC was proposed, and the stress-strain curve was redefined by considering the residual strength based on experimental fitting parameters and statistical parameters. A Weibull distribution was assumed and a statistical damage constitutive model was developed of the deformation process of the AR-GFRC while considering the residual strength effect; detailed calculation methods to determine the mechanical and statistical parameters of the concrete were developed. The validation results show that the theoretical stress-strain curve of the constitutive model is in good agreement with the experimental curve and the trend is consistent. Full article
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Open AccessArticle
Model and Solution of Complex Emergency Dispatch by Multiple Rescue Centers with Limited Capacity to Different Disaster Areas
Symmetry 2020, 12(7), 1138; https://doi.org/10.3390/sym12071138 (registering DOI) - 08 Jul 2020
Viewed by 82
Abstract
A disaster emergency consists of many unfavorable factors, such as different disaster areas, the limited capacity of the rescue centers, and complex rescue conditions. After taking into account the resources of the rescue centers, the ability of rescue teams, and the distance between [...] Read more.
A disaster emergency consists of many unfavorable factors, such as different disaster areas, the limited capacity of the rescue centers, and complex rescue conditions. After taking into account the resources of the rescue centers, the ability of rescue teams, and the distance between the rescue centers and the disaster areas, this paper has established a complex model for multiple centers with limited capacity to dispatch teams for emergencies in different disaster areas. The model is solved by the genetic algorithm. Firstly, the paper takes the rescue task as the subunit to perform integer programming. Secondly, a rule is designed according to the symmetry of parents’ crossing. According to the rule, single parent crossover only allows two situations, (1) different rescue mission for the same rescue center and (2) different rescue centers under the same rescue mission. Finally, the performance of parent crossing and symmetric single parent crossing is compared. The results show that the two algorithms can converge to the optimal solution, but each of them has unique advantages in terms of convergence speed and stability. It is suggested that the strategy of the single-parent crossover should be used to deal with local emergency responses and that the two-parent crossover strategy is be used for more complicated global emergency responses. Full article
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Open AccessArticle
Mental Rotation Ability: Right or Left Hemisphere Competence? What We Can Learn from Callosotomized and Psychotic Patients
Symmetry 2020, 12(7), 1137; https://doi.org/10.3390/sym12071137 - 07 Jul 2020
Viewed by 188
Abstract
Mental rotation is an abstract operation whereby a person imagines rotating an object or a body part to place it in a different position. The ability to perform mental rotation was attributed to right hemisphere for objects, to the left for one’s own [...] Read more.
Mental rotation is an abstract operation whereby a person imagines rotating an object or a body part to place it in a different position. The ability to perform mental rotation was attributed to right hemisphere for objects, to the left for one’s own body images. Mental rotation seems to be basic for imitation in anatomical mode. Previous studies showed that control subjects, callosotomized and psychotic patients chose the mirror-mode when imitating without instructions; when asked to use the same or opposite limb as the model, controls chose the anatomical mode, callosotomized patients mainly used mirror mode, psychotic patients were in between. The preference of callosotomized subjects is likely due to defective mental rotation, because of the lack of the corpus callosum (CC), thus suggesting an asymmetry in the hemispheric competence for mental rotation. Present research investigated the mental rotation ability in control subjects, callosotomized and psychotic patients. All subjects were shown pictures of a model, in first or third person perspective, with a cup in her right or left hand. They had to indicate which model’s hand held the cup, by answering with a verbal or motor modality in separate experimental sessions. In both sessions, control subjects produced 99% of correct responses, callosotomy patients 62%, and psychotic patients 91%. The difference was statistically significant, suggesting a role of the CC in the integration of the two hemispheres’ asymmetric functions in mental rotation. Full article
(This article belongs to the Special Issue Symmetry and Asymmetry in Brain Behavior and Perception)
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Open AccessArticle
Energy Efficiency and User Capacity Optimization of Cognitive MIMO Systems Via the SCMA-Based Nonorthogonal Time Slot Allocation
Symmetry 2020, 12(7), 1136; https://doi.org/10.3390/sym12071136 - 07 Jul 2020
Viewed by 142
Abstract
This paper investigates the energy-efficient communications and user capacity in the cognitive multiple input multiple output (MIMO) symmetric system of underlay mode. The advantage of the improved energy efficiency provided by the orthogonal slot allocation for time division multiple access (TDMA) has a [...] Read more.
This paper investigates the energy-efficient communications and user capacity in the cognitive multiple input multiple output (MIMO) symmetric system of underlay mode. The advantage of the improved energy efficiency provided by the orthogonal slot allocation for time division multiple access (TDMA) has a side effect of restricting the number of users accessing the system. To tackle the above problem, this paper proposes a nonorthogonal time resource allocation method with sparse code multiple access (SCMA), which allows one to convert the orthogonal slot units of TDMA into non-orthogonal shared slot units for multiple secondary users (SUs). The method of adding virtual users is adopted, wherein each SU is treated as multiple SUs who occupy a shared unit, to facilitate the packet access. Finally, the greedy algorithm is applied to optimize the time slot allocation of unoccupied shared slot units. The simulation results show that SCMA-based nonorthogonal slot allocation can reduce not only the energy consumption by nearly 40%, but also the average power interference from SUs to primary users by nearly 2 dB if their number is relatively high. Moreover, in the case of satisfying the rate requirement of the users, the system user capacity increased by more than 50%. Full article
(This article belongs to the Section Computer and Engineer Science and Symmetry)
Open AccessArticle
A Knot Theoretic Extension of the Bloch Sphere Representation for Qubits in Hilbert Space and Its Application to Contextuality and Many-Worlds Theories
Symmetry 2020, 12(7), 1135; https://doi.org/10.3390/sym12071135 - 07 Jul 2020
Viewed by 160
Abstract
We argue that the usual Bloch sphere is insufficient in various aspects for the representation of qubits in quantum information theory. For example, spin flip operations with the quaternions I J K = e 2 π i 2 = 1 and J [...] Read more.
We argue that the usual Bloch sphere is insufficient in various aspects for the representation of qubits in quantum information theory. For example, spin flip operations with the quaternions I J K = e 2 π i 2 = 1 and J I K = + 1 cannot be distinguished on the Bloch sphere. We show that a simple knot theoretic extension of the Bloch sphere representation is sufficient to track all unitary operations for single qubits. Next, we extend the Bloch sphere representation to entangled states using knot theory. As applications, we first discuss contextuality in quantum physics—in particular the Kochen-Specker theorem. Finally, we discuss some arguments against many-worlds theories within our knot theoretic model of entanglement. The key ingredients of our approach are symmetries and geometric properties of the unitary group. Full article
(This article belongs to the Special Issue The Importance of Being Symmetrical)
Open AccessArticle
Holographic Projection of Electromagnetic Maxwell Theory
Symmetry 2020, 12(7), 1134; https://doi.org/10.3390/sym12071134 - 07 Jul 2020
Viewed by 149
Abstract
The 4D Maxwell theory with single-sided planar boundary is considered. As a consequence of the presence of the boundary, two broken Ward identities are recovered, which, on-shell, give rise to two conserved currents living on the edge. A Kaç-Moody algebra formed by a [...] Read more.
The 4D Maxwell theory with single-sided planar boundary is considered. As a consequence of the presence of the boundary, two broken Ward identities are recovered, which, on-shell, give rise to two conserved currents living on the edge. A Kaç-Moody algebra formed by a subset of the bulk fields is obtained with central charge proportional to the inverse of the Maxwell coupling constant, and the degrees of freedom of the boundary theory are identified as two vector fields, also suggesting that the 3D theory should be a gauge theory. Finally the holographic contact between bulk and boundary theory is reached in two inequivalent ways, both leading to a unique 3D action describing a new gauge theory of two coupled vector fields with a topological Chern-Simons term with massive coefficient. In order to check that the 3D projection of 4D Maxwell theory is well defined, we computed the energy-momentum tensor and the propagators. The role of discrete symmetries is briefly discussed. Full article
(This article belongs to the Special Issue Boundaries in Quantum Field Theories)
Open AccessArticle
A Cosserat Model of Elastic Solids Reinforced by a Family of Curved and Twisted Fibers
Symmetry 2020, 12(7), 1133; https://doi.org/10.3390/sym12071133 - 07 Jul 2020
Viewed by 128
Abstract
A Cosserat theory for fiber-reinforced elastic solids developed in Steigmann (2012) is generalized to accommodate initial curvature and twist of the fibers. The basic variables of the theory are a conventional deformation field and a rotation field that describes the local fiber orientation. [...] Read more.
A Cosserat theory for fiber-reinforced elastic solids developed in Steigmann (2012) is generalized to accommodate initial curvature and twist of the fibers. The basic variables of the theory are a conventional deformation field and a rotation field that describes the local fiber orientation. Constraints on these fields are introduced to model the materiality of the fibers with respect to the underlying matrix deformation. A variational argument delivers the relevant equilibrium equations and boundary conditions and furnishes the interpretation of the Lagrange multipliers associated with the constraints as shear tractions acting on the fiber cross sections. Finally, the theory of material symmetry for such solids is developed and applied to the classification of some explicit constitutive functions. Full article
(This article belongs to the Special Issue Recent Advances in the Study of Symmetry and Continuum Mechanics)
Open AccessArticle
Asymmetries in Processes of Electron–Positron Annihilation
Symmetry 2020, 12(7), 1132; https://doi.org/10.3390/sym12071132 - 07 Jul 2020
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Abstract
Processes of electron–positron annihilation into a pair of fermions were considered. Forward–backward and left–right asymmetries were studied, taking into account polarization of initial and final particles. Complete 1-loop electroweak radiative corrections were included. A wide energy range including the Z boson peak and [...] Read more.
Processes of electron–positron annihilation into a pair of fermions were considered. Forward–backward and left–right asymmetries were studied, taking into account polarization of initial and final particles. Complete 1-loop electroweak radiative corrections were included. A wide energy range including the Z boson peak and higher energies relevant for future e + e colliders was covered. Sensitivity of observable asymmetries to the electroweak mixing angle and fermion weak coupling was discussed. Full article
(This article belongs to the Special Issue Symmetry in Particle Physics)
Open AccessArticle
A Decision-Making Algorithm Based on the Average Table and Antitheses Table for Interval-Valued Fuzzy Soft Set
Symmetry 2020, 12(7), 1131; https://doi.org/10.3390/sym12071131 - 07 Jul 2020
Viewed by 138
Abstract
Interval-valued fuzzy soft set is one efficient mathematical model employed to handle the uncertainty of data. At present, there exist two interval-valued fuzzy soft set-based decision-making algorithms. However, the two existing algorithms are not applicable in some cases. Therefore, for the purpose of [...] Read more.
Interval-valued fuzzy soft set is one efficient mathematical model employed to handle the uncertainty of data. At present, there exist two interval-valued fuzzy soft set-based decision-making algorithms. However, the two existing algorithms are not applicable in some cases. Therefore, for the purpose of working out this problem, we propose a new decision-making algorithm, based on the average table and the antitheses table, for this mathematical model. Here, the antitheses table has symmetry between the objects. At the same time, an example is designed to prove the availability of our algorithm. Later, we compare our proposed algorithm with the two existing decision-making algorithms in several cases. The comparison result shows that only our proposed algorithm can make an effective decision in exceptional cases, and the other two methods cannot make decisions. It is therefore obvious that our algorithm has a stronger decision-making ability, thus further demonstrating the feasibility of our algorithm. In addition, a real data set of the homestays in Siming District, Xiamen is provided to further corroborate the practicability of our algorithm in a realistic situation. Full article
Open AccessArticle
Application of the Generalized Hamiltonian Dynamics to Spherical Harmonic Oscillators
Symmetry 2020, 12(7), 1130; https://doi.org/10.3390/sym12071130 - 07 Jul 2020
Viewed by 156
Abstract
Dirac’s Generalized Hamiltonian Dynamics (GHD) is a purely classical formalism for systems having constraints: it incorporates the constraints into the Hamiltonian. Dirac designed the GHD specifically for applications to quantum field theory. In one of our previous papers, we redesigned Dirac’s GHD for [...] Read more.
Dirac’s Generalized Hamiltonian Dynamics (GHD) is a purely classical formalism for systems having constraints: it incorporates the constraints into the Hamiltonian. Dirac designed the GHD specifically for applications to quantum field theory. In one of our previous papers, we redesigned Dirac’s GHD for its applications to atomic and molecular physics by choosing integrals of the motion as the constraints. In that paper, after a general description of our formalism, we considered hydrogenic atoms as an example. We showed that this formalism leads to the existence of classical non-radiating (stationary) states and that there is an infinite number of such states—just as in the corresponding quantum solution. In the present paper, we extend the applications of the GHD to a charged Spherical Harmonic Oscillator (SHO). We demonstrate that, by using the higher-than-geometrical symmetry (i.e., the algebraic symmetry) of the SHO and the corresponding additional conserved quantities, it is possible to obtain the classical non-radiating (stationary) states of the SHO and that, generally speaking, there is an infinite number of such states of the SHO. Both the existence of the classical stationary states of the SHO and the infinite number of such states are consistent with the corresponding quantum results. We obtain these new results from first principles. Physically, the existence of the classical stationary states is the manifestation of a non-Einsteinian time dilation. Time dilates more and more as the energy of the system becomes closer and closer to the energy of the classical non-radiating state. We emphasize that the SHO and hydrogenic atoms are not the only microscopic systems that can be successfully treated by the GHD. All classical systems of N degrees of freedom have the algebraic symmetries ON+1 and SUN, and this does not depend on the functional form of the Hamiltonian. In particular, all classical spherically symmetric potentials have algebraic symmetries, namely O4 and SU3; they possess an additional vector integral of the motion, while the quantal counterpart-operator does not exist. This offers possibilities that are absent in quantum mechanics. Full article
(This article belongs to the Special Issue Atomic Processes in Plasmas and Gases: Symmetries and Beyond)
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Open AccessArticle
Enzymatic Degradation of 2,4,6-Trichlorophenol in a Microreactor using Soybean Peroxidase
Symmetry 2020, 12(7), 1129; https://doi.org/10.3390/sym12071129 - 07 Jul 2020
Viewed by 177
Abstract
Soybean peroxidase is an enzyme extracted from soybean seed hulls. In the presence of hydrogen peroxide, the enzyme has the potential to catalyze the biodegradation of toxic substances like chlorophenols. For this reason, its use in wastewater treatment processes is environmentally friendly since [...] Read more.
Soybean peroxidase is an enzyme extracted from soybean seed hulls. In the presence of hydrogen peroxide, the enzyme has the potential to catalyze the biodegradation of toxic substances like chlorophenols. For this reason, its use in wastewater treatment processes is environmentally friendly since the enzyme can be obtained from a renewable and abundant raw material. In this work, enzymatic biodegradation of 2,4,6-trichlorophenol performed by soybean peroxidase in a microreactor was studied experimentally and theoretically. The experimental data set was obtained with a volume of 250 μL by using different soybean peroxidase concentrations and different reaction times. The fluid dynamics of the microreactor was modeled as well, using ANSYS CFX. The simulations exhibited secondary flows, which enhanced mixing. Although the laminar flow was developed, it can be assumed to be a well-mixed medium. The kinetic data were evaluated through a mechanistic model, the modified bi-bi ping-pong model, which is adequate to represent the enzymatic degradation using peroxidases. The model was composed of an initial value problem for ordinary differential equations that were solved using MATLAB. Some kinetic constants were estimated using the least square function. The results of the model fit well the experimental data. Full article
(This article belongs to the Special Issue Symmetry and Complexity of Catalysis in Flow Chemistry)
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Open AccessArticle
Two Anatomists Are Better than One—Dual-Level Android Malware Detection
Symmetry 2020, 12(7), 1128; https://doi.org/10.3390/sym12071128 - 07 Jul 2020
Viewed by 161
Abstract
The openness of the Android operating system and its immense penetration into the market makes it a hot target for malware writers. This work introduces Androtomist, a novel tool capable of symmetrically applying static and dynamic analysis of applications on the Android platform. [...] Read more.
The openness of the Android operating system and its immense penetration into the market makes it a hot target for malware writers. This work introduces Androtomist, a novel tool capable of symmetrically applying static and dynamic analysis of applications on the Android platform. Unlike similar hybrid solutions, Androtomist capitalizes on a wealth of features stemming from static analysis along with rigorous dynamic instrumentation to dissect applications and decide if they are benign or not. The focus is on anomaly detection using machine learning, but the system is able to autonomously conduct signature-based detection as well. Furthermore, Androtomist is publicly available as open source software and can be straightforwardly installed as a web application. The application itself is dual mode, that is, fully automated for the novice user and configurable for the expert one. As a proof-of-concept, we meticulously assess the detection accuracy of Androtomist against three different popular malware datasets and a handful of machine learning classifiers. We particularly concentrate on the classification performance achieved when the results of static analysis are combined with dynamic instrumentation vis-à-vis static analysis only. Our study also introduces an ensemble approach by averaging the output of all base classification models per malware instance separately, and provides a deeper insight on the most influencing features regarding the classification process. Depending on the employed dataset, for hybrid analysis, we report notably promising to excellent results in terms of the accuracy, F1, and AUC metrics. Full article
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Open AccessArticle
Direct Separation of the Diastereomers of Cholesterol Ester Hydroperoxide Using LC-MS/MS to Evaluate Enzymatic Lipid Oxidation
Symmetry 2020, 12(7), 1127; https://doi.org/10.3390/sym12071127 - 07 Jul 2020
Viewed by 200
Abstract
Cholesterol ester hydroperoxide (CEOOH) is one of the main lipid oxidation products contained in oxidized low-density lipoprotein (LDL). Previous studies suggest that CEOOH in oxidized LDL is closely related to several diseases. Of the oxidation mechanisms of cholesterol ester (CE) in vivo, it [...] Read more.
Cholesterol ester hydroperoxide (CEOOH) is one of the main lipid oxidation products contained in oxidized low-density lipoprotein (LDL). Previous studies suggest that CEOOH in oxidized LDL is closely related to several diseases. Of the oxidation mechanisms of cholesterol ester (CE) in vivo, it has been suggested that enzymatic oxidation induced by lipoxygenase (LOX) plays an important role. Thus, we attempted to develop a method that can evaluate the enzymatic oxidation of CE via the diastereoselective separation of CEOOH bearing 13RS-9Z,11E-hydroperoxy-octadecadienoic acid (13(RS)-HPODE CE). Firstly, we synthesized the standard of 13(RS)-HPODE CE. Using this standard, the screening of analytical conditions (i.e., column, mobile phase, and column temperature) was conducted, and separation of the diastereomers of 13(RS)-HPODE CE was achieved. The diastereoselective separation of 13(RS)-HPODE CE was also confirmed by LC-MS/MS. The developed method (column, CHIRALPAK IB N-3; mobile phase, hexane:ethanol (100:1, v/v); column temperature, 0 °C) can distinguish between enzymatic oxidation and other oxidation mechanisms of CE. Thus, the method can be expected to provide a greater understanding of the biochemical oxidation mechanisms in vivo. Such information will be essential to further elucidate the involvement of CEOOH in various diseases. Full article
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Open AccessArticle
Finite Element Study on the Wear Performance of Movable Jaw Plates of Jaw Crushers after a Symmetrical Laser Cladding Path
Symmetry 2020, 12(7), 1126; https://doi.org/10.3390/sym12071126 - 07 Jul 2020
Viewed by 203
Abstract
At present, research on the influence of friction heat on the wear resistance of laser cladding layers is still lacking, and there is even less research on the temperature of laser cladding layers under different loads by a finite element program generator (FEPG). [...] Read more.
At present, research on the influence of friction heat on the wear resistance of laser cladding layers is still lacking, and there is even less research on the temperature of laser cladding layers under different loads by a finite element program generator (FEPG). After a symmetrical laser cladding path, the wear performance of the moving jaw will change. The study of the temperature change of the moving jaw material in friction provides a theoretical basis for the surface modification of the moving jaw. The model of the column ring is built in a finite element program generator (FEPG). When the inner part of the column is WDB620 (material inside the cylinder) and the outer part is ceramic powder (moving jaw surface material), the relationship between the temperature and time of the contact surface is analyzed under the load between 100 and 600 N. At the same time, the stable temperature, wear amount, effective hardening layer thickness, strain thickness, and iron oxide content corresponding to different loads in a finite element program generator (FEPG) were analyzed. The results showed that when the load is 300 N, the temperature error between the finite element program generator (FEPG) and the movable jaw material is the largest, and the relative error is 4.3%. When the load increases, the stable temperature of the moving jaw plate increases after the symmetrical laser cladding path, and the wear amount first decreases and then increases. The minimum wear amount appears at a load of 400 N and a temperature of 340 °C; the strain thickness of the sample material increases gradually, and the effective hardening layer thickness increases. However, when the load reaches 400 N, the thickness of the effective hardening layer changes little; the content of Fe decreases gradually, and the content of FeO and Fe2O3 increases. The increase of the moving jaw increases in turn the temperature of the laser cladding layer of the test jaw material, which intensifies the oxidation reaction of the ceramic powder of the laser cladding layer. Full article
(This article belongs to the Special Issue Mesh Methods - Numerical Analysis and Experiments)
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