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Symmetry, Volume 11, Issue 3 (March 2019)

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Cover Story (view full-size image) Classically, the mass can be placed freely in a point, in the quantum mechanical space-time (ST) it [...] Read more.
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Open AccessArticle
A Novel Approach to Multi-Attribute Group Decision-Making based on Interval-Valued Intuitionistic Fuzzy Power Muirhead Mean
Symmetry 2019, 11(3), 441; https://doi.org/10.3390/sym11030441
Received: 28 January 2019 / Revised: 15 March 2019 / Accepted: 20 March 2019 / Published: 25 March 2019
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Abstract
This paper focuses on multi-attribute group decision-making (MAGDM) course in which attributes are evaluated in terms of interval-valued intuitionistic fuzzy (IVIF) information. More explicitly, this paper introduces new aggregation operators for IVIF information and further proposes a new IVIF MAGDM method. The power [...] Read more.
This paper focuses on multi-attribute group decision-making (MAGDM) course in which attributes are evaluated in terms of interval-valued intuitionistic fuzzy (IVIF) information. More explicitly, this paper introduces new aggregation operators for IVIF information and further proposes a new IVIF MAGDM method. The power average (PA) operator and the Muirhead mean (MM) are two powerful and effective information aggregation technologies. The most attractive advantage of the PA operator is its power to combat the adverse effects of ultra-evaluation values on the information aggregation results. The prominent characteristic of the MM operator is that it is flexible to capture the interrelationship among any numbers of arguments, making it more powerful than Bonferroni mean (BM), Heronian mean (HM), and Maclaurin symmetric mean (MSM). To absorb the virtues of both PA and MM, it is necessary to combine them to aggregate IVIF information and propose IVIF power Muirhead mean (IVIFPMM) operator and the IVIF weighted power Muirhead mean (IVIFWPMM) operator. We investigate their properties to show the strongness and flexibility. Furthermore, a novel approach to MAGDM problems with IVIF decision-making information is introduced. Finally, a numerical example is provided to show the performance of the proposed method. Full article
Open AccessArticle
A New Ranking Methodology for Pythagorean Trapezoidal Uncertain Linguistic Fuzzy Sets Based on Einstein Operations
Symmetry 2019, 11(3), 440; https://doi.org/10.3390/sym11030440
Received: 30 January 2019 / Revised: 2 March 2019 / Accepted: 5 March 2019 / Published: 25 March 2019
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Abstract
In this article, we proposed new Pythagorean trapezoidal uncertain linguistic fuzzy aggregation information—namely, the Pythagorean trapezoidal uncertain linguistic fuzzy Einstein weighted averaging (PTULFEWA) operator, the Pythagorean trapezoidal uncertain linguistic fuzzy Einstein ordered weighted averaging (PTULFEOWA) operator, and the Pythagorean trapezoidal uncertain linguistic fuzzy [...] Read more.
In this article, we proposed new Pythagorean trapezoidal uncertain linguistic fuzzy aggregation information—namely, the Pythagorean trapezoidal uncertain linguistic fuzzy Einstein weighted averaging (PTULFEWA) operator, the Pythagorean trapezoidal uncertain linguistic fuzzy Einstein ordered weighted averaging (PTULFEOWA) operator, and the Pythagorean trapezoidal uncertain linguistic fuzzy Einstein hybrid weighted averaging (PTULFEHWA) operator—using the Einstein operational laws. We studied some important properties of the suggested aggregation operators and showed that the PTULFEHWA is more general than the other proposed operators, which simplifies these aggregation operators. Furthermore, we presented a multiple attribute group decision making (MADM) process for the proposed aggregation operators under the Pythagorean trapezoidal uncertain linguistic fuzzy (PTULF) environment. A numerical example was constructed to determine the effectiveness and practicality of the proposed approach. Lastly, a comparative analysis was performed of the presented approach with existing approaches to show that the proposed method is consistent and provides more information that may be useful for complex problems in the decision-making process. Full article
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Open AccessArticle
Influence of Cattaneo–Christov Heat Flux on MHD Jeffrey, Maxwell, and Oldroyd-B Nanofluids with Homogeneous-Heterogeneous Reaction
Symmetry 2019, 11(3), 439; https://doi.org/10.3390/sym11030439
Received: 4 March 2019 / Revised: 17 March 2019 / Accepted: 19 March 2019 / Published: 25 March 2019
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Abstract
This research article deals with the determination of magnetohydrodynamic steady flow of three combile nanofluids (Jefferey, Maxwell, and Oldroyd-B) over a stretched surface. The surface is considered to be linear. The Cattaneo–Christov heat flux model was considered necessary to study the relaxation properties [...] Read more.
This research article deals with the determination of magnetohydrodynamic steady flow of three combile nanofluids (Jefferey, Maxwell, and Oldroyd-B) over a stretched surface. The surface is considered to be linear. The Cattaneo–Christov heat flux model was considered necessary to study the relaxation properties of the fluid flow. The influence of homogeneous-heterogeneous reactions (active for auto catalysts and reactants) has been taken in account. The modeled problem is solved analytically. The impressions of the magnetic field, Prandtl number, thermal relaxation time, Schmidt number, homogeneous–heterogeneous reactions strength are considered through graphs. The velocity field diminished with an increasing magnetic field. The temperature field diminished with an increasing Prandtl number and thermal relaxation time. The concentration field upsurged with the increasing Schmidt number which decreased with increasing homogeneous-heterogeneous reactions strength. Furthermore, the impact of these parameters on skin fraction, Nusselt number, and Sherwood number were also accessible through tables. A comparison between analytical and numerical methods has been presented both graphically and numerically. Full article
(This article belongs to the Special Issue Symmetry and Fluid Mechanics)
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Open AccessArticle
Effects MHD and Heat Generation on Mixed Convection Flow of Jeffrey Fluid in Microgravity Environment over an Inclined Stretching Sheet
Symmetry 2019, 11(3), 438; https://doi.org/10.3390/sym11030438
Received: 14 March 2019 / Revised: 20 March 2019 / Accepted: 22 March 2019 / Published: 25 March 2019
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Abstract
In this paper, Jeffrey fluid is studied in a microgravity environment. Unsteady two-dimensional incompressible and laminar g-Jitter mixed convective boundary layer flow over an inclined stretching sheet is examined. Heat generation and Magnetohydrodynamic MHD effects are also considered. The governing boundary layer equations [...] Read more.
In this paper, Jeffrey fluid is studied in a microgravity environment. Unsteady two-dimensional incompressible and laminar g-Jitter mixed convective boundary layer flow over an inclined stretching sheet is examined. Heat generation and Magnetohydrodynamic MHD effects are also considered. The governing boundary layer equations together with boundary conditions are converted into a non-similar arrangement using appropriate similarity conversions. The transformed system of equations is resolved mathematically by employing an implicit finite difference pattern through quasi-linearization method. Numerical results of temperature, velocity, local heat transfer, and local skin friction coefficient are computed and plotted graphically. It is found that local skin friction and local heat transfer coefficients increased for increasing Deborah number when the magnitude of the gravity modulation is unity. Assessment with previously published results showed an excellent agreement. Full article
(This article belongs to the Special Issue Symmetry and Fluid Mechanics)
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Open AccessArticle
An Innovative Design of Substitution-Boxes Using Cubic Polynomial Mapping
Symmetry 2019, 11(3), 437; https://doi.org/10.3390/sym11030437
Received: 8 February 2019 / Revised: 14 March 2019 / Accepted: 22 March 2019 / Published: 25 March 2019
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Abstract
In this paper, we propose to present a novel technique for designing cryptographically strong substitution-boxes using cubic polynomial mapping. The proposed cubic polynomial mapping is proficient to map the input sequence to a strong 8 × 8 S-box meeting the requirements of a [...] Read more.
In this paper, we propose to present a novel technique for designing cryptographically strong substitution-boxes using cubic polynomial mapping. The proposed cubic polynomial mapping is proficient to map the input sequence to a strong 8 × 8 S-box meeting the requirements of a bijective function. The use of cubic polynomial maintains the simplicity of S-box construction method and found consistent when compared with other existing S-box techniques used to construct S-boxes. An example proposed S-box is obtained which is analytically evaluated using standard performance criteria including nonlinearity, bijection, bit independence, strict avalanche effect, linear approximation probability, and differential uniformity. The performance results are equated with some recently scrutinized S-boxes to ascertain its cryptographic forte. The critical analyses endorse that the proposed S-box construction technique is considerably innovative and effective to generate cryptographic strong substitution-boxes. Full article
Open AccessArticle
Hirota Difference Equation and Darboux System: Mutual Symmetry
Symmetry 2019, 11(3), 436; https://doi.org/10.3390/sym11030436
Received: 1 March 2019 / Revised: 18 March 2019 / Accepted: 21 March 2019 / Published: 25 March 2019
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Abstract
We considered the relation between two famous integrable equations: The Hirota difference equation (HDE) and the Darboux system that describes conjugate curvilinear systems of coordinates in R3. We demonstrated that specific properties of solutions of the HDE with respect to independent [...] Read more.
We considered the relation between two famous integrable equations: The Hirota difference equation (HDE) and the Darboux system that describes conjugate curvilinear systems of coordinates in R 3 . We demonstrated that specific properties of solutions of the HDE with respect to independent variables enabled introduction of an infinite set of discrete symmetries. We showed that degeneracy of the HDE with respect to parameters of these discrete symmetries led to the introduction of continuous symmetries by means of a specific limiting procedure. This enabled consideration of these symmetries on equal terms with the original HDE independent variables. In particular, the Darboux system appeared as an integrable equation where continuous symmetries of the HDE served as independent variables. We considered some cases of intermediate choice of independent variables, as well as the relation of these results with direct and inverse problems. Full article
(This article belongs to the Special Issue Symmetries and Integrability of Difference Equations)
Open AccessArticle
Single and Multi-Soliton Solutions for a Spectrally Deformed Set of Maxwell-Bloch Equations
Symmetry 2019, 11(3), 435; https://doi.org/10.3390/sym11030435
Received: 24 February 2019 / Revised: 19 March 2019 / Accepted: 20 March 2019 / Published: 25 March 2019
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Abstract
A specific spectral deformation of the Maxwell-Bloch equations of nonlinear optics is investigated. The Darboux transformation formalism is adapted to this spectrally deformed system to construct its single and multi-soliton solutions. The Effects of spectral deformation on soliton behaviour is studied. Full article
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Open AccessArticle
Coupling Conditions for Water Waves at Forks
Symmetry 2019, 11(3), 434; https://doi.org/10.3390/sym11030434
Received: 15 January 2019 / Revised: 15 March 2019 / Accepted: 19 March 2019 / Published: 24 March 2019
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Abstract
We considered the propagation of nonlinear shallow water waves in a narrow channel presenting a fork. We aimed at computing the coupling conditions for a 1D effective model, using 2D simulations and an analysis based on the conservation laws. For small amplitudes, this [...] Read more.
We considered the propagation of nonlinear shallow water waves in a narrow channel presenting a fork. We aimed at computing the coupling conditions for a 1D effective model, using 2D simulations and an analysis based on the conservation laws. For small amplitudes, this analysis justifies the well-known Stoker interface conditions, so that the coupling does not depend on the angle of the fork. We also find this in the numerical solution. Large amplitude solutions in a symmetric fork also tend to follow Stoker’s relations, due to the symmetry constraint. For non symmetric forks, 2D effects dominate so that it is necessary to understand the flow inside the fork. However, even then, conservation laws give some insight in the dynamics. Full article
(This article belongs to the Special Issue Symmetries of Nonlinear PDEs on Metric Graphs and Branched Networks)
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Open AccessArticle
Fluctuation Theorem of Information Exchange between Subsystems that Co-Evolve in Time
Symmetry 2019, 11(3), 433; https://doi.org/10.3390/sym11030433
Received: 27 February 2019 / Revised: 21 March 2019 / Accepted: 22 March 2019 / Published: 22 March 2019
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Abstract
Sagawa and Ueda established a fluctuation theorem of information exchange by revealing the role of correlations in stochastic thermodynamics and unified the non-equilibrium thermodynamics of measurement and feedback control. They considered a process where a non-equilibrium system exchanges information with other degrees of [...] Read more.
Sagawa and Ueda established a fluctuation theorem of information exchange by revealing the role of correlations in stochastic thermodynamics and unified the non-equilibrium thermodynamics of measurement and feedback control. They considered a process where a non-equilibrium system exchanges information with other degrees of freedom such as an observer or a feedback controller. They proved the fluctuation theorem of information exchange under the assumption that the state of the other degrees of freedom that exchange information with the system does not change over time while the states of the system evolve in time. Here we relax this constraint and prove that the same form of the fluctuation theorem holds even if both subsystems co-evolve during information exchange processes. This result may extend the applicability of the fluctuation theorem of information exchange to a broader class of non-equilibrium processes, such as a dynamic coupling in biological systems, where subsystems that exchange information interact with each other. Full article
(This article belongs to the Special Issue Current Trends in Symmetric Polynomials with their Applications)
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Open AccessArticle
Algebraic Entropy of a Class of Five-Point Differential-Difference Equations
Symmetry 2019, 11(3), 432; https://doi.org/10.3390/sym11030432
Received: 9 March 2019 / Revised: 20 March 2019 / Accepted: 20 March 2019 / Published: 22 March 2019
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Abstract
We compute the algebraic entropy of a class of integrable Volterra-like five-point differential-difference equations recently classified using the generalised symmetry method. We show that, when applicable, the results of the algebraic entropy agrees with the result of the generalised symmetry method, as all [...] Read more.
We compute the algebraic entropy of a class of integrable Volterra-like five-point differential-difference equations recently classified using the generalised symmetry method. We show that, when applicable, the results of the algebraic entropy agrees with the result of the generalised symmetry method, as all the equations in this class have vanishing entropy. Full article
(This article belongs to the Special Issue Symmetries and Integrability of Difference Equations)
Open AccessArticle
An Improved OTSU Algorithm Using Histogram Accumulation Moment for Ore Segmentation
Symmetry 2019, 11(3), 431; https://doi.org/10.3390/sym11030431
Received: 26 February 2019 / Revised: 15 March 2019 / Accepted: 20 March 2019 / Published: 22 March 2019
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Abstract
When using image processing technology to analyze mineral particle size in complex scenes, it is difficult to separate the objects from the background with traditional algorithms. This paper proposes an ore image segmentation algorithm based on a histogram accumulation moment, which is applied [...] Read more.
When using image processing technology to analyze mineral particle size in complex scenes, it is difficult to separate the objects from the background with traditional algorithms. This paper proposes an ore image segmentation algorithm based on a histogram accumulation moment, which is applied to multi-scenario ore object location and recognition. Firstly, the multi-scale Retinex color restoration algorithm is used to improve the contrast in the dark region and eliminates the shadows generated by the stacked adhesion ores. Then, the zero-order and first-order cumulative moments close to the selected gray level are calculated, reducing the error caused by noise. Finally, the selected gray level gradually approaches the optimal threshold to avoid falling into local optimum. It can segment mineral images with unimodal or insignificant bimodal characteristic histogram effectively and accurately. Ore images in three different scenarios are used to verify the accuracy and effectiveness of the proposed method. The experimental results demonstrate that the proposed algorithm provides better segmentation results than other methods. Full article
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Open AccessArticle
On a SIR Model in a Patchy Environment Under Constant and Feedback Decentralized Controls with Asymmetric Parameterizations
Symmetry 2019, 11(3), 430; https://doi.org/10.3390/sym11030430
Received: 15 February 2019 / Revised: 7 March 2019 / Accepted: 14 March 2019 / Published: 22 March 2019
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Abstract
This paper presents a formal description and analysis of an SIR (involving susceptible- infectious-recovered subpopulations) epidemic model in a patchy environment with vaccination controls being constant and proportional to the susceptible subpopulations. The patchy environment is due to the fact that there is [...] Read more.
This paper presents a formal description and analysis of an SIR (involving susceptible- infectious-recovered subpopulations) epidemic model in a patchy environment with vaccination controls being constant and proportional to the susceptible subpopulations. The patchy environment is due to the fact that there is a partial interchange of all the subpopulations considered in the model between the various patches what is modelled through the so-called travel matrices. It is assumed that the vaccination controls are administered at each community health centre of a particular patch while either the total information or a partial information of the total subpopulations, including the interchanging ones, is shared by all the set of health centres of the whole environment under study. In the case that not all the information of the subpopulations distributions at other patches are known by the health centre of each particular patch, the feedback vaccination rule would have a decentralized nature. The paper investigates the existence, allocation (depending on the vaccination control gains) and uniqueness of the disease-free equilibrium point as well as the existence of at least a stable endemic equilibrium point. Such a point coincides with the disease-free equilibrium point if the reproduction number is unity. The stability and instability of the disease-free equilibrium point are ensured under the values of the disease reproduction number guaranteeing, respectively, the un-attainability (the reproduction number being less than unity) and stability (the reproduction number being more than unity) of the endemic equilibrium point. The whole set of the potential endemic equilibrium points is characterized and a particular case is also described related to its uniqueness in the case when the patchy model reduces to a unique patch. Vaccination control laws including feedback are proposed which can take into account shared information between the various patches. It is not assumed that there are in the most general case, symmetry-type constrains on the population fluxes between the various patches or in the associated control gains parameterizations. Full article
(This article belongs to the Special Issue Symmetry and Complexity 2019)
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Open AccessArticle
Multiparametric Analytical Solution for the Eigenvalue Problem of FGM Porous Circular Plates
Symmetry 2019, 11(3), 429; https://doi.org/10.3390/sym11030429
Received: 11 March 2019 / Revised: 18 March 2019 / Accepted: 20 March 2019 / Published: 22 March 2019
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Abstract
Free vibration analysis of the porous functionally graded circular plates has been presented on the basis of classical plate theory. The three defined coupled equations of motion of the porous functionally graded circular/annular plate were decoupled to one differential equation of free transverse [...] Read more.
Free vibration analysis of the porous functionally graded circular plates has been presented on the basis of classical plate theory. The three defined coupled equations of motion of the porous functionally graded circular/annular plate were decoupled to one differential equation of free transverse vibrations of plate. The one universal general solution was obtained as a linear combination of the multiparametric special functions for the functionally graded circular and annular plates with even and uneven porosity distributions. The multiparametric frequency equations of functionally graded porous circular plate with diverse boundary conditions were obtained in the exact closed-form. The influences of the even and uneven distributions of porosity, power-law index, diverse boundary conditions and the neglected effect of the coupling in-plane and transverse displacements on the dimensionless frequencies of the circular plate were comprehensively studied for the first time. The formulated boundary value problem, the exact method of solution and the numerical results for the perfect and imperfect functionally graded circular plates have not yet been reported. Full article
(This article belongs to the Special Issue Symmetry in Applied Continuous Mechanics)
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Open AccessArticle
Modelling the Impact of Transit Media on Information Spreading in an Urban Space Using Cellular Automata
Symmetry 2019, 11(3), 428; https://doi.org/10.3390/sym11030428
Received: 31 January 2019 / Revised: 14 March 2019 / Accepted: 19 March 2019 / Published: 22 March 2019
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Abstract
Information spreading processes are the key drivers of marketing campaigns. Activity on social media delivers more detailed information compared to viral marketing in traditional media. Monitoring the performance of outdoor campaigns that are carried out using this transportation system is even more complicated [...] Read more.
Information spreading processes are the key drivers of marketing campaigns. Activity on social media delivers more detailed information compared to viral marketing in traditional media. Monitoring the performance of outdoor campaigns that are carried out using this transportation system is even more complicated because of the lack of data. The approach that is presented in this paper is based on cellular automata and enables the modelling of the information-spreading processes that are initiated by transit advertising within an urban space. The evaluation of classical and graph cellular automata models and a coverage analysis of transit advertising based on tram lines were performed. The results demonstrated how the number of lines affects the performance in terms of coverage within an urban space and the differences between the proposed models. While research is based on an exemplary dataset taken from Szczecin (Poland), the presented framework can be used together with data from the public transport system for modelling advertising resources usage and coverage within the urban space. Full article
(This article belongs to the Special Issue Information Technology and Its Applications 2018)
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Open AccessArticle
Critical Components Identification for Service-Oriented Systems
Symmetry 2019, 11(3), 427; https://doi.org/10.3390/sym11030427
Received: 14 February 2019 / Revised: 16 March 2019 / Accepted: 18 March 2019 / Published: 22 March 2019
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Abstract
Identifying critical components are of great significance to the overall reliability of service-oriented systems (SOSs). As the size of the SOS increases, identifying critical components in the process of predicting the SOS reliability can reduce the number of components that need to be [...] Read more.
Identifying critical components are of great significance to the overall reliability of service-oriented systems (SOSs). As the size of the SOS increases, identifying critical components in the process of predicting the SOS reliability can reduce the number of components that need to be predicted and shorten the prediction time. Moreover, predicting the reliability of critical components can also ensure the stability of the SOS. Therefore, we transform the relationships among service components of the SOS into a service dependency graph. Then, an improved weighted LeaderRank algorithm (IW-LeaderRank) is proposed to measure the importance of components and obtain the sequence of critical components. Through experimental analysis, the method can accurately and efficiently identify critical components in SOSs. Full article
(This article belongs to the Special Issue Symmetry in Computing Theory and Application)
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Open AccessArticle
A Haptic Model for the Quantum Phase of Fermions and Bosons in Hilbert Space Based on Knot Theory
Symmetry 2019, 11(3), 426; https://doi.org/10.3390/sym11030426
Received: 19 December 2018 / Revised: 25 February 2019 / Accepted: 7 March 2019 / Published: 22 March 2019
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Abstract
A generalization of the famous Dirac belt trick opens up the way to a haptic model for quantum phases of fermions and bosons in Hilbert space based on knot theory. We introduce a simple paper strip model as an aid for visualization of [...] Read more.
A generalization of the famous Dirac belt trick opens up the way to a haptic model for quantum phases of fermions and bosons in Hilbert space based on knot theory. We introduce a simple paper strip model as an aid for visualization of the quantum phases before and after Hopf-mapping, which can be extended to arbitrary spin states with almost no mathematical formalism. Knot theory arises naturally, leading to the Jones polynomials derived from Artin’s braid group for fermionic knots and for bosonic links. The paper strip model explicitly illuminates the relation between these knots and links within the S U ( 2 ) -representation of spin-jstates in C 2 j + 1 before Hopf-mapping and the number p = 2 j of nodes in the stellar representation in C P 1 after Hopf mapping. Full article
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Open AccessArticle
Effects of Hadron-Quark Phase Transitions in Hybrid Stars within the NJL Model
Symmetry 2019, 11(3), 425; https://doi.org/10.3390/sym11030425
Received: 28 February 2019 / Revised: 19 March 2019 / Accepted: 20 March 2019 / Published: 22 March 2019
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Abstract
We study local and non-local Polyakov Nambu-Jona-Lasinio models and analyze their respective phase transition diagram. We construct hybrid stars using the zero temperature limit of the local and non-local versions of Nambu-Jona-Lasinio model for quark matter and the modern GM1(L) parametrization of the [...] Read more.
We study local and non-local Polyakov Nambu-Jona-Lasinio models and analyze their respective phase transition diagram. We construct hybrid stars using the zero temperature limit of the local and non-local versions of Nambu-Jona-Lasinio model for quark matter and the modern GM1(L) parametrization of the non-linear relativistic mean field model for hadronic matter. We compare our models with data from PSR J1614-2230 and PSR J0343+0432 and also from GW170817 and its electromagnetic counterpart GRB170817A and AT2017gfo. We study observational signatures of the appearance of a mixed phase as a result of modeling a phase transition that mimics the Gibbs formalism and compare the results with the sharp first-order phase transition obtained using the Maxwell construction. We also study in detail the g-mode associated with discontinuities in the equation of state, and calculate non-radial oscillation modes using relativistic Cowling approximation. Full article
(This article belongs to the Special Issue Nambu-Jona-Lasinio model and its applications)
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Open AccessArticle
An Effective Global Optimization Algorithm for Quadratic Programs with Quadratic Constraints
Symmetry 2019, 11(3), 424; https://doi.org/10.3390/sym11030424
Received: 13 January 2019 / Revised: 6 March 2019 / Accepted: 7 March 2019 / Published: 22 March 2019
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Abstract
This paper will present an effective algorithm for globally solving quadratic programs with quadratic constraints. In this algorithm, we propose a new linearization method for establishing the linear programming relaxation problem of quadratic programs with quadratic constraints. The proposed algorithm converges with the [...] Read more.
This paper will present an effective algorithm for globally solving quadratic programs with quadratic constraints. In this algorithm, we propose a new linearization method for establishing the linear programming relaxation problem of quadratic programs with quadratic constraints. The proposed algorithm converges with the global optimal solution of the initial problem, and numerical experiments show the computational efficiency of the proposed algorithm. Full article
(This article belongs to the Special Issue New Trends in Dynamics)
Open AccessArticle
Performance Improvement of a Liquid Molten Salt Pump: Geometry Optimization and Experimental Verification
Symmetry 2019, 11(3), 423; https://doi.org/10.3390/sym11030423
Received: 1 February 2019 / Revised: 11 March 2019 / Accepted: 20 March 2019 / Published: 22 March 2019
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Abstract
In order to enhance the hydraulic efficiency of a liquid molten salt pump, the improvement on the pump was carried out through numerical and experimental methods. The internal flow field obtained by the numerical simulation was analysed. The results show that there are [...] Read more.
In order to enhance the hydraulic efficiency of a liquid molten salt pump, the improvement on the pump was carried out through numerical and experimental methods. The internal flow field obtained by the numerical simulation was analysed. The results show that there are low-velocity area in the scroll region and large curvature of the streamline at the outlet. Geometric modification was made by trimming the back-blades of the impeller and filleting the sharp corner of the outlet pipe. The modified pump performance was verified by the experiments. The hydraulic efficiency, the pressure fluctuation, vibration characteristics between the original and modified pump were compared. The results showed that the hydraulic efficiency of the modified pump increased 7.4%. In addition, the pressure fluctuation and vibration intensity were also reduced compared with the original pump. This result shows that the geometric modification improves not only the hydraulic performance but also the structural properties. Full article
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Open AccessArticle
GPU-based Fast Motion Synthesis of Large Crowds Using Adaptive Multi-Joint Models
Symmetry 2019, 11(3), 422; https://doi.org/10.3390/sym11030422
Received: 18 February 2019 / Revised: 12 March 2019 / Accepted: 20 March 2019 / Published: 22 March 2019
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Abstract
This paper introduces a GPU (graphics processing unit)-based fast motion synthesis algorithm for a large crowd. The main parts of the algorithms were selecting the most appropriate joint model given adaptive screen-space occupancy of each character and synthesizing motions for the joint model [...] Read more.
This paper introduces a GPU (graphics processing unit)-based fast motion synthesis algorithm for a large crowd. The main parts of the algorithms were selecting the most appropriate joint model given adaptive screen-space occupancy of each character and synthesizing motions for the joint model with one or two input motion capture data. The different joint models had a character range from fine-detailed and fully-articulated ones to the most simplified ones. The motion synthesizer, running on a GPU, performed a series of motion blending for each joint of the characters in parallel. For better performance of the motion synthesizer, the GPU maintained a novel cache structure for given speed parameters. Using the high computation power of GPUs, the motion synthesizer could generate arbitrary speeds and orientations for the motions of a vast number of characters. Experiments showed that the proposed algorithm could animate more than 5000 characters in real-time on modest graphics acceleration cards. Full article
(This article belongs to the Special Issue Visual Symmetry 2018)
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Open AccessArticle
Reliability-Aware Cooperative Routing with Adaptive Amplification for Underwater Acoustic Wireless Sensor Networks
Symmetry 2019, 11(3), 421; https://doi.org/10.3390/sym11030421
Received: 24 February 2019 / Revised: 18 March 2019 / Accepted: 19 March 2019 / Published: 22 March 2019
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Abstract
The protocols in underwater acoustic wireless sensor networks (UAWSNs) that address reliability in packets forwarding usually consider the connectivity of the routing paths up to one- or two-hops. Since senor nodes are connected with one another using other nodes in their neighborhood, such [...] Read more.
The protocols in underwater acoustic wireless sensor networks (UAWSNs) that address reliability in packets forwarding usually consider the connectivity of the routing paths up to one- or two-hops. Since senor nodes are connected with one another using other nodes in their neighborhood, such protocols have compromised reliability. It is because these protocols do not guarantee the presence of neighbors beyond the selected one- or two-hops for connectivity and path establishment. This is further worsened by the harshness and unpredictability of the underwater scenario. In addition, establishment of the routing paths usually requires the nodes’ undersea geographical locations, which is infeasible because currents in water cause the nodes to move from one position to another. To overcome these challenges, this paper presents two routing schemes for UAWSNs: reliability-aware routing (RAR) and reliability-aware cooperative routing with adaptive amplification (RACAA). RAR considers complete path connectivity to advance packets to sea surface. This overcomes packets loss when connectivity is not established and forwarder nodes are not available for data routing. For all the established paths, the probability of successfully transmitting data packets is calculated. This avoids the adverse channel effects. However, sea channel is unpredictable and fluctuating and its properties may change after its computation and prior to information transmission. Therefore, cooperative routing is introduced to RAR with adaptive power control of relays, which makes the RACAA protocol. In RACAA, a relay node increases its transmit power than normal when the error in the data; it receives from the sender, is more than 50 % before transferring it further to destination. This further increases the reliability when such packets are forwarded. Unlike the conventional approach, the proposed protocols are independent of knowing the geographical locations of nodes in establishing the routes, which is computationally challenging due to nodes’ movements with ocean currents and tides. Simulation results exhibit that RAR and RACAA outperform the counterpart scheme in delivering packets to the water surface. Full article
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Open AccessArticle
A New GM(1,1) Model Based on Cubic Monotonicity-Preserving Interpolation Spline
Symmetry 2019, 11(3), 420; https://doi.org/10.3390/sym11030420
Received: 28 February 2019 / Revised: 18 March 2019 / Accepted: 19 March 2019 / Published: 21 March 2019
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Abstract
In the classical GM(1,1) model, an accumulated generating operation is made on the original non-negative sequence to obtain a monotone increasing 1-AGO sequence, and the forecasting model is established based on the 1-AGO sequence. A great number of scholars have improved the accuracy [...] Read more.
In the classical GM(1,1) model, an accumulated generating operation is made on the original non-negative sequence to obtain a monotone increasing 1-AGO sequence, and the forecasting model is established based on the 1-AGO sequence. A great number of scholars have improved the accuracy of grey model prediction through better developed background value and the equation for the time response. In this work, we reconstruct the background value based on a new developed monotonicity-preserving piecewise cubic interpolations spline, and thereby establish a new GM(1,1) model. Numerical examples show that the new GM(1,1) model has better prediction quality of data than the original GM(1,1) model and improves the precision of prediction in practice. Full article
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Open AccessArticle
Performance Analysis of Preemptive Priority Retrial Queueing System with Disaster under Working Breakdown Services
Symmetry 2019, 11(3), 419; https://doi.org/10.3390/sym11030419
Received: 12 January 2019 / Revised: 25 February 2019 / Accepted: 4 March 2019 / Published: 21 March 2019
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Abstract
In this investigation, a novel sort of retrial queueing system with working breakdown services is introduced. Two distinct kinds of customers are considered, which are priority and ordinary customers. The normal busy server may become inadequate due to catastrophes at any time which [...] Read more.
In this investigation, a novel sort of retrial queueing system with working breakdown services is introduced. Two distinct kinds of customers are considered, which are priority and ordinary customers. The normal busy server may become inadequate due to catastrophes at any time which cause the major server to fail. At a failure moment, the major server is sent to be fixed and the server functions at a lower speed (called the working breakdown period) during the repair period. The probability generating functions (PGF) of the system size is found using the concepts of the supplementary variable technique (SVT). The impact of parameters in system performance measures and cost optimization are examined numerically. Full article
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Open AccessArticle
A New Fuzzy Multiple Attribute Decision Making Method Based on the Utility Transformation Functions
Symmetry 2019, 11(3), 418; https://doi.org/10.3390/sym11030418
Received: 1 March 2019 / Revised: 14 March 2019 / Accepted: 19 March 2019 / Published: 21 March 2019
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Abstract
The 2-tuple linguistic information model (2TLIM) is a useful tool to avoid the loss of information, which has been widely adapted in the study of the multiple attribute decision making (MADM) problem. However, there is a limitation, the limitation is that the difference [...] Read more.
The 2-tuple linguistic information model (2TLIM) is a useful tool to avoid the loss of information, which has been widely adapted in the study of the multiple attribute decision making (MADM) problem. However, there is a limitation, the limitation is that the difference between the neighboring 2-tuple linguistic information is fixed regardless of the decision-makers’ attitude. In this paper, we define the utility transformation functions based on the 2-tuple linguistic utility to overcome the drawback. Firstly, by introducing the economic utility theory, the 2-tuple linguistic utility is defined, the 2-tuple linguistic utility parameter (2TLUP) and the 2-tuple linguistic marginal utility (2TLMU) are constructed to achieve the measurement of the decision-makers’ attitude. The utility transformation functions are developed on the decision-makers’ attitude. Secondly, the 2-tuple linguistic operational laws are presented with the extended Hamacher T-norm (TN) and T-conorm (TC). Subsequently, we propose the 2-tuple linguistic utility weighted average (2TLUWA) operator and the method of MADM. Lastly, the application and the comparison with the existing methods are summarized to verify the practicality and advantages of the proposed method of MADM. Full article
(This article belongs to the Special Issue Multi-Criteria Decision Aid methods in fuzzy decision problems)
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Open AccessArticle
On Conformable Double Laplace Transform and One Dimensional Fractional Coupled Burgers’ Equation
Symmetry 2019, 11(3), 417; https://doi.org/10.3390/sym11030417
Received: 24 February 2019 / Revised: 17 March 2019 / Accepted: 18 March 2019 / Published: 21 March 2019
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Abstract
In the present work we introduced a new method and name it the conformable double Laplace decomposition method to solve one dimensional regular and singular conformable functional Burger’s equation. We studied the existence condition for the conformable double Laplace transform. In order to [...] Read more.
In the present work we introduced a new method and name it the conformable double Laplace decomposition method to solve one dimensional regular and singular conformable functional Burger’s equation. We studied the existence condition for the conformable double Laplace transform. In order to obtain the exact solution for nonlinear fractional problems, then we modified the double Laplace transform and combined it with the Adomian decomposition method. Later, we applied the new method to solve regular and singular conformable fractional coupled Burgers’ equations. Further, in order to illustrate the effectiveness of present method, we provide some examples. Full article
(This article belongs to the Special Issue Fractional Differential Equations: Theory, Methods and Applications)
Open AccessArticle
Fast Retrieval Method of Forestry Information Features Based on Symmetry Function in Communication Network
Symmetry 2019, 11(3), 416; https://doi.org/10.3390/sym11030416
Received: 15 January 2019 / Revised: 6 March 2019 / Accepted: 13 March 2019 / Published: 21 March 2019
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Abstract
Aiming at the problem of insufficient integration and sharing of forestry information resources under the current communication network and the lack of the concept set of forestry information attributes, which leads to poor information retrieval performance, a fast retrieval method of forestry information [...] Read more.
Aiming at the problem of insufficient integration and sharing of forestry information resources under the current communication network and the lack of the concept set of forestry information attributes, which leads to poor information retrieval performance, a fast retrieval method of forestry information features based on symmetry function is studied in depth, and the method is implemented by PDA (Personal Digital Assistant)-BA (Buliding Automation). Using the SED (Stream Editor) forestry information acquisition method under a communication network to collect forestry information, a forestry signal noise cancellation method based on symmetric function method is obtained. In order to improve the accuracy of forestry information acquisition, denoising of the signal in the information was carried out. Constructing forestry information data ontology, integrating forestry resources, establishing a conceptual set of forestry information attributes, distinguishing forestry information attributes, establishing a fast retrieval model of forestry information features based on the synonym library, and completing the fast retrieval of forestry information features. The experimental results show that the recall and precision of this method are 99.25% and 99.24%, respectively, and the retrieval performance is superior, which has a certain application value. Full article
(This article belongs to the Special Issue New Trends in Dynamics)
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Open AccessArticle
Generalized Picture Fuzzy Soft Sets and Their Application in Decision Support Systems
Symmetry 2019, 11(3), 415; https://doi.org/10.3390/sym11030415
Received: 1 March 2019 / Revised: 12 March 2019 / Accepted: 14 March 2019 / Published: 20 March 2019
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Abstract
In this paper, a generalized picture fuzzy soft set is proposed, which is an extension of the picture fuzzy soft sets. We investigate the basic properties of picture fuzzy soft sets and define an F-subset, M-subset, extended union, extended intersection, restricted union, restricted [...] Read more.
In this paper, a generalized picture fuzzy soft set is proposed, which is an extension of the picture fuzzy soft sets. We investigate the basic properties of picture fuzzy soft sets and define an F-subset, M-subset, extended union, extended intersection, restricted union, restricted intersection and also prove the De Morgan’s laws for picture fuzzy soft information. We investigate upper and lower substitution for both picture fuzzy sets and generalized picture fuzzy soft sets. Meanwhile, the related proofs are given in detail. Finally, we propose an algorithm to deal with generalized picture fuzzy soft information. To show the supremacy and effectiveness of the proposed technique, we illustrate a descriptive example using generalized picture fuzzy soft information. Results indicate that the proposed technique is more generalized and effective over all the existing structures of fuzzy soft sets. Full article
Open AccessFeature PaperArticle
On the Structure of Finite Groupoids and Their Representations
Symmetry 2019, 11(3), 414; https://doi.org/10.3390/sym11030414
Received: 21 December 2018 / Revised: 15 March 2019 / Accepted: 15 March 2019 / Published: 20 March 2019
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Abstract
In this paper, both the structure and the theory of representations of finite groupoids are discussed. A finite connected groupoid turns out to be an extension of the groupoids of pairs of its set of units by its canonical totally disconnected isotropy subgroupoid. [...] Read more.
In this paper, both the structure and the theory of representations of finite groupoids are discussed. A finite connected groupoid turns out to be an extension of the groupoids of pairs of its set of units by its canonical totally disconnected isotropy subgroupoid. An extension of Maschke’s theorem for groups is proved showing that the algebra of a finite groupoid is semisimple and all finite-dimensional linear representations of finite groupoids are completely reducible. The theory of characters for finite-dimensional representations of finite groupoids is developed and it is shown that irreducible representations of the groupoid are in one-to-one correspondence with irreducible representation of its isotropy groups, with an extension of Burnside’s theorem describing the decomposition of the regular representation of a finite groupoid. Some simple examples illustrating these results are exhibited with emphasis on the groupoids interpretation of Schwinger’s description of quantum mechanical systems. Full article
(This article belongs to the Special Issue New trends on Symmetry and Topology in Quantum Mechanics)
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Open AccessArticle
On the Effect of Thomson and Initial Stress in a Thermo-Porous Elastic Solid under G-N Electromagnetic Theory
Symmetry 2019, 11(3), 413; https://doi.org/10.3390/sym11030413
Received: 22 January 2019 / Revised: 6 March 2019 / Accepted: 14 March 2019 / Published: 20 March 2019
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Abstract
The present work investigated the effect of Thomson and initial stress in a thermo-porous elastic solid under G-N electromagnetic theory. The Thomson coefficient affects the heat condition equation. A constant Thomson coefficient, instead of traditionally a constant Seebeck coefficient, is assumed. The charge [...] Read more.
The present work investigated the effect of Thomson and initial stress in a thermo-porous elastic solid under G-N electromagnetic theory. The Thomson coefficient affects the heat condition equation. A constant Thomson coefficient, instead of traditionally a constant Seebeck coefficient, is assumed. The charge density of the induced electric current is taken as a function of time. A normal mode method is proposed to analyze the problem and to obtain numerical solutions. The results that were obtained for all physical sizes are graphically illustrated and we offer a comparison between the type II G-N theory and the G-N theory of type III, both in the present case and in the absence of specific parameters, as initial stress, pores and the Thomson effect. Some particular cases are also discussed in the context of the problem. The results indicate that the effect of initial stress, Thomson coefficient effect, and magnetic field are very pronounced. Full article
(This article belongs to the Special Issue Symmetry in Applied Continuous Mechanics)
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Open AccessArticle
Stability Analysis of Darcy-Forchheimer Flow of Casson Type Nanofluid Over an Exponential Sheet: Investigation of Critical Points
Symmetry 2019, 11(3), 412; https://doi.org/10.3390/sym11030412
Received: 31 December 2018 / Revised: 6 March 2019 / Accepted: 8 March 2019 / Published: 20 March 2019
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Abstract
In this paper, steady two-dimensional laminar incompressible magnetohydrodynamic flow over an exponentially shrinking sheet with the effects of slip conditions and viscous dissipation is examined. An extended Darcy Forchheimer model was considered to observe the porous medium embedded in a non-Newtonian-Casson-type nanofluid. The [...] Read more.
In this paper, steady two-dimensional laminar incompressible magnetohydrodynamic flow over an exponentially shrinking sheet with the effects of slip conditions and viscous dissipation is examined. An extended Darcy Forchheimer model was considered to observe the porous medium embedded in a non-Newtonian-Casson-type nanofluid. The governing equations were converted into nonlinear ordinary differential equations using an exponential similarity transformation. The resultant equations for the boundary values problem (BVPs) were reduced to initial values problems (IVPs) and then shooting and Fourth Order Runge-Kutta method (RK-4th method) were applied to obtain numerical solutions. The results reveal that multiple solutions occur only for the high suction case. The results of the stability analysis showed that the first (second) solution is physically reliable (unreliable) and stable (unstable). Full article
(This article belongs to the Special Issue Symmetry and Fluid Mechanics)
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