Symmetry

20 pages, 1105 KiB

Open AccessArticle

A Generalization of Trapezoidal Fuzzy Numbers Based on Modal Interval Theory

by Lambert Jorba^*,†

and Romà Adillon^†

¹ Departament de Matemàtica Econòmica, Financera i Actuarial, Universitat de Barcelona, 08034 Barcelona, Spain

^† These authors contributed equally to this work.

Symmetry 2017, 9(10), 198; https://doi.org/10.3390/sym9100198 - 21 Sep 2017

Cited by 12 | Viewed by 4347

Abstract

We propose a generalization of trapezoidal fuzzy numbers based on modal interval theory, which we name “modal interval trapezoidal fuzzy numbers”. In this generalization, we accept that the alpha cuts associated with a trapezoidal fuzzy number can be modal intervals, also allowing that [...] Read more.

We propose a generalization of trapezoidal fuzzy numbers based on modal interval theory, which we name “modal interval trapezoidal fuzzy numbers”. In this generalization, we accept that the alpha cuts associated with a trapezoidal fuzzy number can be modal intervals, also allowing that two interval modalities can be associated with a trapezoidal fuzzy number. In this context, it is difficult to maintain the traditional graphic representation of trapezoidal fuzzy numbers and we must use the interval plane in order to represent our modal interval trapezoidal fuzzy numbers graphically. Using this representation, we can correctly reflect the modality of the alpha cuts. We define some concepts from modal interval analysis and we study some of the related properties and structures, proving, among other things, that the inclusion relation provides a lattice structure on this set. We will also provide a semantic interpretation deduced from the modal interval extensions of real continuous functions and the semantic modal interval theorem. The application of modal intervals in the field of fuzzy numbers also provides a new perspective on and new applications of fuzzy numbers. Full article

(This article belongs to the Special Issue Fuzzy Sets Theory and Its Applications)

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17 pages, 562 KiB

Open AccessArticle

Generalized Chordality, Vertex Separators and Hyperbolicity on Graphs

by Álvaro Martínez-Pérez

Department of Economic analysis and Finances, Universidad de Castilla-La Mancha, Avda. Real Fábrica de Sedas s/n, 45600 Talavera de la Reina, Spain

Symmetry 2017, 9(10), 199; https://doi.org/10.3390/sym9100199 - 24 Sep 2017

Cited by 7 | Viewed by 3992

Abstract

A graph is chordal if every induced cycle has exactly three edges. A vertex separator set in a graph is a set of vertices that disconnects two vertices. A graph is

δ

-hyperbolic if every geodesic triangle is

δ

-thin. In this paper, [...] Read more.

A graph is chordal if every induced cycle has exactly three edges. A vertex separator set in a graph is a set of vertices that disconnects two vertices. A graph is

δ

-hyperbolic if every geodesic triangle is

δ

-thin. In this paper, we study the relation between vertex separator sets, certain chordality properties that generalize being chordal and the hyperbolicity of the graph. We also give a characterization of being quasi-isometric to a tree in terms of chordality and prove that this condition also characterizes being hyperbolic, when restricted to triangles, and having stable geodesics, when restricted to bigons. Full article

(This article belongs to the Special Issue Graph Theory)

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31 pages, 341 KiB

Open AccessFeature PaperArticle

Solvability of the Class of Two-Dimensional Product-Type Systems of Difference Equations of Delay-Type (1, 3, 1, 1)

by Stevo Stević^1,2

¹ Mathematical Institute of the Serbian Academy of Sciences, Knez Mihailova 36/III, 11000 Beograd, Serbia

² Operator Theory and Applications Research Group, Department of Mathematics, King Abdulaziz University, P.O. Box 80203, Jeddah 21589, Saudi Arabia

Symmetry 2017, 9(10), 200; https://doi.org/10.3390/sym9100200 - 25 Sep 2017

Cited by 2 | Viewed by 2805

Abstract

This paper essentially presents the last and important steps in the study of (practical) solvability of two-dimensional product-type systems of difference equations of the following form

z_{n} = α z_{n - k}^{a} w_{n - l}^{b},

[...] Read more.

This paper essentially presents the last and important steps in the study of (practical) solvability of two-dimensional product-type systems of difference equations of the following form

z_{n} = α z_{n - k}^{a} w_{n - l}^{b},

w_{n} = β w_{n - m}^{c} z_{n - s}^{d},

n \in N_{0},

where

k, l, m, s \in N

,

a, b, c, d \in Z

, and where

α, β

and the initial values are complex numbers. It is devoted to the most complex case which has not been considered so far (the case

k = l = s = 1

and

m = 3

). Closed form formulas for solutions to the system are found in all possible cases. The structure of the solutions to the system is considered in detail. The following five cases: (1)

b = 0

; (2)

c = 0

; (3)

d = 0

; (4)

a c \neq 0

; (5)

a = 0

,

b c d \neq 0

, are considered separately. Some of the situations appear for the first time in the literature. Full article

(This article belongs to the Special Issue Symmetry: Feature Papers 2017)

21 pages, 633 KiB

Open AccessFeature PaperArticle

Testing Lorentz Symmetry Using High Energy Astrophysics Observations

by Floyd W. Stecker^1,2

¹ NASA Goddard Space Flight Center, Greenbelt, MD 20771, USA

² Department of Physics and Astronomy, University of California, Los Angeles, CA 90095, USA

Symmetry 2017, 9(10), 201; https://doi.org/10.3390/sym9100201 - 25 Sep 2017

Cited by 18 | Viewed by 3628

Abstract

We discuss some of the tests of Lorentz symmetry made possible by astrophysical observations of ultrahigh energy cosmic rays,

γ

-rays and neutrinos. These are among the most sensitive tests of Lorentz invariance violation because they are the highest energy phenomena known to [...] Read more.

We discuss some of the tests of Lorentz symmetry made possible by astrophysical observations of ultrahigh energy cosmic rays,

γ

-rays and neutrinos. These are among the most sensitive tests of Lorentz invariance violation because they are the highest energy phenomena known to man. Full article

(This article belongs to the Special Issue Violation of Lorentz Symmetry)

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17 pages, 425 KiB

Open AccessFeature PaperArticle

Towards a New Proposal for the Time Delay in Gravitational Lensing

by Nicola Alchera^†, Marco Bonici^† and Nicola Maggiore^*,†

¹ Dipartimento di Fisica, Università di Genova, via Dodecaneso 33, I-16146 Genova, Italy

^† I.N.F.N.—Sezione di Genova.

Symmetry 2017, 9(10), 202; https://doi.org/10.3390/sym9100202 - 25 Sep 2017

Cited by 4 | Viewed by 3355

Abstract

One application of the Cosmological Gravitational Lensing in General Relativity is the measurement of the Hubble constant

H_{0}

using the time delay

Δ t

between multiple images of lensed quasars. This method has already been applied, obtaining a value of [...] Read more.

One application of the Cosmological Gravitational Lensing in General Relativity is the measurement of the Hubble constant

H_{0}

using the time delay

Δ t

between multiple images of lensed quasars. This method has already been applied, obtaining a value of

H_{0}

compatible with that obtained from the SNe 1A, but non-compatible with that obtained studying the anisotropies of the CMB. This difference could be a statistical fluctuation or an indication of new physics beyond the Standard Model of Cosmology, so it desirable to improve the precision of the measurements. At the current technological capabilities it is possible to obtain

H_{0}

to a percent level uncertainty, so a more accurate theoretical model could be necessary in order to increase the precision about the determination of

H_{0}

. The actual formula which relates

Δ t

with

H_{0}

is approximated; in this paper we expose a proposal to go beyond the previous analysis and, within the context of a new model, we obtain a more precise formula than that present in the literature. Full article

(This article belongs to the Special Issue Symmetry in Quantum Field Theory)

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20 pages, 1463 KiB

Open AccessArticle

Polar Bear Optimization Algorithm: Meta-Heuristic with Fast Population Movement and Dynamic Birth and Death Mechanism

by Dawid Połap

and Marcin Woz´niak^*

Institute of Mathematics, Silesian University of Technology, Kaszubska 23, 44-100 Gliwice, Poland

Symmetry 2017, 9(10), 203; https://doi.org/10.3390/sym9100203 - 28 Sep 2017

Cited by 167 | Viewed by 9927

Abstract

In the proposed article, we present a nature-inspired optimization algorithm, which we called Polar Bear Optimization Algorithm (PBO). The inspiration to develop the algorithm comes from the way polar bears hunt to survive in harsh arctic conditions. These carnivorous mammals are active all [...] Read more.

In the proposed article, we present a nature-inspired optimization algorithm, which we called Polar Bear Optimization Algorithm (PBO). The inspiration to develop the algorithm comes from the way polar bears hunt to survive in harsh arctic conditions. These carnivorous mammals are active all year round. Frosty climate, unfavorable to other animals, has made polar bears adapt to the specific mode of exploration and hunting in large areas, not only over ice but also water. The proposed novel mathematical model of the way polar bears move in the search for food and hunt can be a valuable method of optimization for various theoretical and practical problems. Optimization is very similar to nature, similarly to search for optimal solutions for mathematical models animals search for optimal conditions to develop in their natural environments. In this method. we have used a model of polar bear behaviors as a search engine for optimal solutions. Proposed simulated adaptation to harsh winter conditions is an advantage for local and global search, while birth and death mechanism controls the population. Proposed PBO was evaluated and compared to other meta-heuristic algorithms using sample test functions and some classical engineering problems. Experimental research results were compared to other algorithms and analyzed using various parameters. The analysis allowed us to identify the leading advantages which are rapid recognition of the area by the relevant population and efficient birth and death mechanism to improve global and local search within the solution space. Full article

(This article belongs to the Special Issue Information Technology and Its Applications)

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22 pages, 1224 KiB

Open AccessArticle

Logical and Geometrical Distance in Polyhedral Aristotelian Diagrams in Knowledge Representation

by Lorenz Demey^1,* and Hans Smessaert²

¹ Center for Logic and Analytic Philosophy, KU Leuven, 3000 Leuven, Belgium

² Research Group on Formal and Computational Linguistics, KU Leuven, 3000 Leuven, Belgium

Symmetry 2017, 9(10), 204; https://doi.org/10.3390/sym9100204 - 29 Sep 2017

Cited by 13 | Viewed by 6862

Abstract

Aristotelian diagrams visualize the logical relations among a finite set of objects. These diagrams originated in philosophy, but recently, they have also been used extensively in artificial intelligence, in order to study (connections between) various knowledge representation formalisms. In this paper, we develop [...] Read more.

Aristotelian diagrams visualize the logical relations among a finite set of objects. These diagrams originated in philosophy, but recently, they have also been used extensively in artificial intelligence, in order to study (connections between) various knowledge representation formalisms. In this paper, we develop the idea that Aristotelian diagrams can be fruitfully studied as geometrical entities. In particular, we focus on four polyhedral Aristotelian diagrams for the Boolean algebra

B_{4}

, viz. the rhombic dodecahedron, the tetrakis hexahedron, the tetraicosahedron and the nested tetrahedron. After an in-depth investigation of the geometrical properties and interrelationships of these polyhedral diagrams, we analyze the correlation (or lack thereof) between logical (Hamming) and geometrical (Euclidean) distance in each of these diagrams. The outcome of this analysis is that the Aristotelian rhombic dodecahedron and tetrakis hexahedron exhibit the strongest degree of correlation between logical and geometrical distance; the tetraicosahedron performs worse; and the nested tetrahedron has the lowest degree of correlation. Finally, these results are used to shed new light on the relative strengths and weaknesses of these polyhedral Aristotelian diagrams, by appealing to the congruence principle from cognitive research on diagram design. Full article

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15 pages, 818 KiB

Open AccessArticle

β-Differential of a Graph

by Ludwin A. Basilio¹, Sergio Bermudo², Jesús Leaños¹ and José M. Sigarreta^3,*

¹ Academic Unit of Mathematics, Autonomous University of Zacatecas, Paseo la Bufa, int. Calzada Solidaridad, 98060 Zacatecas, Mexico

² Department of Economics, Quantitative Methods and Economic History, Pablo de Olavide University, Carretera de Utrera Km. 1, 41013 Sevilla, Spain

³ Faculty of Mathematics, Autonomous University of Guerrero, Carlos E. Adame 5, Col. La Garita, 39350 Acapulco, Guerrero, Mexico

Symmetry 2017, 9(10), 205; https://doi.org/10.3390/sym9100205 - 30 Sep 2017

Cited by 8 | Viewed by 3734

Abstract

Let

G = (V, E)

be a simple graph with vertex set V and edge set E. Let D be a subset of V, and let

B (D)

be the set of neighbours of D in [...] Read more.

Let

G = (V, E)

be a simple graph with vertex set V and edge set E. Let D be a subset of V, and let

B (D)

be the set of neighbours of D in

V ∖ D

. The differential

\partial (D)

of D is defined as

| B (D) | - | D |

. The maximum value of

\partial (D)

taken over all subsets

D \subseteq V

is the differential

\partial (G)

of G. For

β \in (- 1, Δ)

, the β-differential

\partial_{β} (G)

of G is the maximum value of

{| B (D) | - β | D | : D \subseteq V}

. Motivated by an influential maximization problem, in this paper we study the

β

-differential of G. Full article

(This article belongs to the Special Issue Graph Theory)

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19 pages, 2261 KiB

Open AccessReview

Chiral Separation in Preparative Scale: A Brief Overview of Membranes as Tools for Enantiomeric Separation

by Carla Fernandes^1,2,†, Maria Elizabeth Tiritan^1,2,3,†

and Madalena M. M. Pinto^1,2,*

¹ Laboratório de Química Orgânica e Farmacêutica, Departamento de Ciências Químicas, Faculdade de Farmácia, Rua de Jorge Viterbo Ferreira, 228, 4050-313 Porto, Portugal

² Interdisciplinary Centre of Marine and Environmental Research (CIIMAR), Edifício do Terminal de Cruzeiros do Porto de Leixões, Av. General Norton de Matos s/n, 4050-208 Matosinhos, Portugal

³ Cooperativa de Ensino Superior, Politécnico e Universitário (CESPU), Instituto de Investigação e Formação Avançada em Ciências e Tecnologias da Saúde (IINFACTS), Rua Central de Gandra, 1317, 4585-116 Gandra PRD, Portugal

^† These authors equally contributed to this work.

Symmetry 2017, 9(10), 206; https://doi.org/10.3390/sym9100206 - 30 Sep 2017

Cited by 66 | Viewed by 9724

Abstract

Given the importance of chirality in the biological response, regulators, industries and researchers require chiral compounds in their enantiomeric pure form. Therefore, the approach to separate enantiomers in preparative scale needs to be fast, easy to operate, low cost and allow obtaining the [...] Read more.

Given the importance of chirality in the biological response, regulators, industries and researchers require chiral compounds in their enantiomeric pure form. Therefore, the approach to separate enantiomers in preparative scale needs to be fast, easy to operate, low cost and allow obtaining the enantiomers at high level of optical purity. A variety of methodologies to separate enantiomers in preparative scale is described, but most of them are expensive or with restricted applicability. However, the use of membranes have been pointed out as a promising methodology for scale-up enantiomeric separation due to the low energy consumption, continuous operability, variety of materials and supports, simplicity, eco-friendly and the possibility to be integrated into other separation processes. Different types of membranes (solid and liquid) have been developed and may provide applicability in multi-milligram and industrial scales. In this brief overview, the different types and chemical nature of membranes are described, showing their advantages and drawbacks. Recent applications of enantiomeric separations of pharmaceuticals, amines and amino acids were reported. Full article

(This article belongs to the Special Issue Chiral Separations)

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23 pages, 1379 KiB

Open AccessArticle

A Two-Factor Autoregressive Moving Average Model Based on Fuzzy Fluctuation Logical Relationships

by Shuang Guan¹ and Aiwu Zhao^2,*

¹ Rensselaer Polytechnic Institute, Troy, NY 12180, USA

² School of management, Jiangsu University, Zhenjiang 212013, China

Symmetry 2017, 9(10), 207; https://doi.org/10.3390/sym9100207 - 1 Oct 2017

Cited by 17 | Viewed by 4864

Abstract

Many of the existing autoregressive moving average (ARMA) forecast models are based on one main factor. In this paper, we proposed a new two-factor first-order ARMA forecast model based on fuzzy fluctuation logical relationships of both a main factor and a secondary factor [...] Read more.

Many of the existing autoregressive moving average (ARMA) forecast models are based on one main factor. In this paper, we proposed a new two-factor first-order ARMA forecast model based on fuzzy fluctuation logical relationships of both a main factor and a secondary factor of a historical training time series. Firstly, we generated a fluctuation time series (FTS) for two factors by calculating the difference of each data point with its previous day, then finding the absolute means of the two FTSs. We then constructed a fuzzy fluctuation time series (FFTS) according to the defined linguistic sets. The next step was establishing fuzzy fluctuation logical relation groups (FFLRGs) for a two-factor first-order autoregressive (AR(1)) model and forecasting the training data with the AR(1) model. Then we built FFLRGs for a two-factor first-order autoregressive moving average (ARMA(1,m)) model. Lastly, we forecasted test data with the ARMA(1,m) model. To illustrate the performance of our model, we used real Taiwan Stock Exchange Capitalization Weighted Stock Index (TAIEX) and Dow Jones datasets as a secondary factor to forecast TAIEX. The experiment results indicate that the proposed two-factor fluctuation ARMA method outperformed the one-factor method based on real historic data. The secondary factor may have some effects on the main factor and thereby impact the forecasting results. Using fuzzified fluctuations rather than fuzzified real data could avoid the influence of extreme values in historic data, which performs negatively while forecasting. To verify the accuracy and effectiveness of the model, we also employed our method to forecast the Shanghai Stock Exchange Composite Index (SHSECI) from 2001 to 2015 and the international gold price from 2000 to 2010. Full article

(This article belongs to the Special Issue Fuzzy Sets Theory and Its Applications)

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14 pages, 1688 KiB

Open AccessArticle

Scale Effect and Anisotropy Analyzed for Neutrosophic Numbers of Rock Joint Roughness Coefficient Based on Neutrosophic Statistics

by Jiqian Chen¹, Jun Ye^1,2,*

and Shigui Du¹

¹ Key Laboratory of Rock Mechanics and Geohazards, Shaoxing University, 508 Huancheng West Road, Shaoxing 312000, Zhejiang Province, China, chenjiqian@yahoo.com (J.C.)

² Department of Electrical and Information Engineering, Shaoxing University, 508 Huancheng West Road, Shaoxing 312000, Zhejiang Province, China

Symmetry 2017, 9(10), 208; https://doi.org/10.3390/sym9100208 - 1 Oct 2017

Cited by 203 | Viewed by 5049

Abstract

In rock mechanics, the study of shear strength on the structural surface is crucial to evaluating the stability of engineering rock mass. In order to determine the shear strength, a key parameter is the joint roughness coefficient (JRC). To express and analyze JRC [...] Read more.

In rock mechanics, the study of shear strength on the structural surface is crucial to evaluating the stability of engineering rock mass. In order to determine the shear strength, a key parameter is the joint roughness coefficient (JRC). To express and analyze JRC values, Ye et al. have proposed JRC neutrosophic numbers (JRC-NNs) and fitting functions of JRC-NNs, which are obtained by the classical statistics and curve fitting in the current method. Although the JRC-NNs and JRC-NN functions contain much more information (partial determinate and partial indeterminate information) than the crisp JRC values and functions in classical methods, the JRC functions and the JRC-NN functions may also lose some useful information in the fitting process and result in the function distortion of JRC values. Sometimes, some complex fitting functions may also result in the difficulty of their expressions and analyses in actual applications. To solve these issues, we can combine the neutrosophic numbers with neutrosophic statistics to realize the neutrosophic statistical analysis of JRC-NNs for easily analyzing the characteristics (scale effect and anisotropy) of JRC values. In this study, by means of the neutrosophic average values and standard deviations of JRC-NNs, rather than fitting functions, we directly analyze the scale effect and anisotropy characteristics of JRC values based on an actual case. The analysis results of the case demonstrate the feasibility and effectiveness of the proposed neutrosophic statistical analysis of JRC-NNs and can overcome the insufficiencies of the classical statistics and fitting functions. The main advantages of this study are that the proposed neutrosophic statistical analysis method not only avoids information loss but also shows its simplicity and effectiveness in the characteristic analysis of JRC. Full article

(This article belongs to the Special Issue Neutrosophic Theories Applied in Engineering)

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22 pages, 6977 KiB

Open AccessArticle

Reliability Improved Cooperative Communication over Wireless Sensor Networks

by Zhuangbin Chen¹, Ming Ma², Xiao Liu¹, Anfeng Liu^1,*

and Ming Zhao³

¹ School of Information Science and Engineering, Central South University, Changsha 410083, China

² Department of Computer Science, Stony Brook University, New York, NY 11794, USA

³ School of Software, Central South University, Changsha 410075, China

Symmetry 2017, 9(10), 209; https://doi.org/10.3390/sym9100209 - 1 Oct 2017

Cited by 23 | Viewed by 5149

Abstract

With the development of smart devices and connection technologies, Wireless Sensor Networks (WSNs) are becoming increasingly intelligent. New or special functions can be obtained by receiving new versions of program codes to upgrade their software systems, forming the so-called smart Internet of Things [...] Read more.

With the development of smart devices and connection technologies, Wireless Sensor Networks (WSNs) are becoming increasingly intelligent. New or special functions can be obtained by receiving new versions of program codes to upgrade their software systems, forming the so-called smart Internet of Things (IoT). Due to the lossy property of wireless channels, data collection in WSNs still suffers from a long delay, high energy consumption, and many retransmissions. Thanks to wireless software-defined networks (WSDNs), software in sensors can now be updated to help them transmit data cooperatively, thereby achieving more reliable communication. In this paper, a Reliability Improved Cooperative Communication (RICC) data collection scheme is proposed to improve the reliability of random-network-coding-based cooperative communications in multi-hop relay WSNs without reducing the network lifetime. In WSNs, sensors in different positions can have different numbers of packets to handle, resulting in the unbalanced energy consumption of the network. In particular, nodes in non-hotspot areas have up to 90% of their original energy remaining when the network dies. To efficiently use the residual energy, in RICC, high data transmission power is adopted in non-hotspot areas to achieve a higher reliability at the cost of large energy consumption, and relatively low transmission power is adopted in hotspot areas to maintain the long network lifetime. Therefore, high reliability and a long network lifetime can be obtained simultaneously. The simulation results show that compared with other scheme, RICC can reduce the end-to-end Message Fail delivering Ratio (MFR) by 59.4%–62.8% under the same lifetime with a more balanced energy utilization. Full article

(This article belongs to the Special Issue Applications of Internet of Things)

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13 pages, 819 KiB

Open AccessArticle

Convergence Analysis on a Second Order Algorithm for Orthogonal Projection onto Curves

by Xiaowu Li^1,†

, Lin Wang^1,†, Zhinan Wu^2,†, Linke Hou^3,*,†, Juan Liang^4,*,† and Qiaoyang Li^5,*,†

¹ College of Data Science and Information Engineering, Guizhou Minzu University, Guiyang 550025, China

² School of Mathematics and Computer Science, Yichun University, Yichun 336000, China

³ Center for Economic Research, Shandong University, Jinan 250100, China

⁴ Department of Science, Taiyuan Institute of Technology, Taiyuan 030008, China

⁵ Center for the World Ethnic Studies, Guizhou Minzu University, Guiyang 550025, China

^† These authors contributed equally to this work.

Symmetry 2017, 9(10), 210; https://doi.org/10.3390/sym9100210 - 1 Oct 2017

Cited by 6 | Viewed by 4154

Abstract

Regarding the point projection and inversion problem, a classical algorithm for orthogonal projection onto curves and surfaces has been presented by Hu and Wallner (2005). The objective of this paper is to give a convergence analysis of the projection algorithm. On the point [...] Read more.

Regarding the point projection and inversion problem, a classical algorithm for orthogonal projection onto curves and surfaces has been presented by Hu and Wallner (2005). The objective of this paper is to give a convergence analysis of the projection algorithm. On the point projection problem, we give a formal proof that it is second order convergent and independent of the initial value to project a point onto a planar parameter curve. Meantime, for the point inversion problem, we then give a formal proof that it is third order convergent and independent of the initial value. Full article

(This article belongs to the Special Issue Advances in Computer Graphics, Geometric Modeling, and Virtual and Augmented Reality)

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20 pages, 3966 KiB

Open AccessReview

The Development of Key Technologies in Applications of Vessels Connected to the Internet

by Zhe Tian¹

, Fushun Liu^1,*, Zhixiong Li^2,3

, Reza Malekian^4,*

and Yingchun Xie¹

¹ College of Engineering, Ocean University of China, Qingdao 266100, China

² School of Mechatronics Engineering, China University of Mining & Technology, Xuzhou 221106, China

³ School of Mechanical Engineering, Iowa State University, Ames, IA 50011, USA

⁴ Department of Electrical, Electronic & Computer Engineering, University of Pretoria, Pretoria 0002, South Africa

Symmetry 2017, 9(10), 211; https://doi.org/10.3390/sym9100211 - 1 Oct 2017

Cited by 31 | Viewed by 9056

Abstract

With the development of science and technology, traffic perception, communication, information processing, artificial intelligence and the shipping information system have become important in supporting the realization of intelligent shipping transportation. Against this background, the Internet of Vessels (IoV) is proposed to integrate all [...] Read more.

With the development of science and technology, traffic perception, communication, information processing, artificial intelligence and the shipping information system have become important in supporting the realization of intelligent shipping transportation. Against this background, the Internet of Vessels (IoV) is proposed to integrate all these advanced technologies into a platform to meet the requirements of international and regional transportations. The purpose of this paper is to analyze how to benefit from the Internet of Vessels to improve the efficiency and safety of shipping, and promote the development of world transportation. In this paper, the IoV is introduced and its main architectures are outlined. Furthermore, the characteristics of the Internet of Vessels are described. Several important applications that illustrate the interaction of the Internet of Vessels’ components are proposed. Due to the development of the Internet of Vessels still being in its primary stage, challenges and prospects are identified and addressed. Finally, the main conclusions are drawn and future research priorities are provided for reference and as professional suggestions for future researchers in this field. Full article

(This article belongs to the Special Issue Applications of Internet of Things)

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17 pages, 4737 KiB

Open AccessArticle

A Novel Approach Based on Time Cluster for Activity Recognition of Daily Living in Smart Homes

by Yaqing Liu^1,2,3,4, Dantong Ouyang², Yong Liu^3,* and Rong Chen¹

¹ School of Information Science & Technology, Dalian Maritime University, Dalian 116026, China

² Key Laboratory of Symbolic Computation and Knowledge Engineering of Ministry of Education, Jilin University, Changchun 130012, China

³ Artificial Intelligence Key Laboratory of Sichuan Province, Sichuan University of Science and Engineering, Zigong 643000, China

⁴ School of Computer and Software, Nanjing University of Information Science & Technology, Nanjing 210044, China

Symmetry 2017, 9(10), 212; https://doi.org/10.3390/sym9100212 - 1 Oct 2017

Cited by 17 | Viewed by 5152

Abstract

With the trend of the increasing ageing population, more elderly people often encounter some problems in their daily lives. To enable these people to have more carefree lives, smart homes are designed to assist elderly people by recognizing their daily activities. Although different [...] Read more.

With the trend of the increasing ageing population, more elderly people often encounter some problems in their daily lives. To enable these people to have more carefree lives, smart homes are designed to assist elderly people by recognizing their daily activities. Although different models and algorithms that use temporal and spatial features for activity recognition have been proposed, the rigid representations of these features damage the accuracy of activity recognition. In this paper, a two-stage approach is proposed to recognize the activities of a single resident. Firstly, in terms of temporal features, the approximate duration, start and end time are extracted from the activity records. Secondly, a set of activity records is clustered according to the records’ temporal features. Then, the classifiers are used to recognize the daily activities in each cluster according to the spatial features. Finally, two experiments are done to validate the recognition of daily activities in order to compare the proposed approach with a one-dimensional model. The results demonstrate that the proposed approach favorably outperforms the one-dimensional model. Two public datasets are used to evaluate the proposed approach. The experiment results show that the proposed approach achieves average accuracies of 80% and 89%, respectively. Full article

(This article belongs to the Special Issue Applications of Internet of Things)

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38 pages, 1898 KiB

Open AccessArticle

IoT’s Tiny Steps towards 5G: Telco’s Perspective

by Enida Cero¹, Jasmina Baraković Husić^1,2,* and Sabina Baraković^3,4

¹ BH Telecom, Joint Stock Company, Sarajevo, Franca Lehara 7, 71000 Sarajevo, Bosna i Hercegovina

² Faculty of Electrical Engineering, University of Sarajevo, Zmaja od Bosne bb, 71000 Sarajevo, Bosna i Hercegovina

³ Faculty of Transport and Communications, University of Sarajevo, Zmaja od Bosne 8, 71000 Sarajevo, Bosna i Hercegovina

⁴ Department for Computer Engineering, American University in Bosnia and Herzegovina, Trg solidarnosti 10, 71000 Sarajevo, Bosna i Hercegovina

Symmetry 2017, 9(10), 213; https://doi.org/10.3390/sym9100213 - 2 Oct 2017

Cited by 24 | Viewed by 8900

Abstract

The numerous and diverse applications of the Internet of Things (IoT) have the potential to change all areas of daily life of individuals, businesses, and society as a whole. The vision of a pervasive IoT spans a wide range of application domains and [...] Read more.

The numerous and diverse applications of the Internet of Things (IoT) have the potential to change all areas of daily life of individuals, businesses, and society as a whole. The vision of a pervasive IoT spans a wide range of application domains and addresses the enabling technologies needed to meet the performance requirements of various IoT applications. In order to accomplish this vision, this paper aims to provide an analysis of literature in order to propose a new classification of IoT applications, specify and prioritize performance requirements of such IoT application classes, and give an insight into state-of-the-art technologies used to meet these requirements, all from telco’s perspective. A deep and comprehensive understanding of the scope and classification of IoT applications is an essential precondition for determining their performance requirements with the overall goal of defining the enabling technologies towards fifth generation (5G) networks, while avoiding over-specification and high costs. Given the fact that this paper presents an overview of current research for the given topic, it also targets the research community and other stakeholders interested in this contemporary and attractive field for the purpose of recognizing research gaps and recommending new research directions. Full article

(This article belongs to the Special Issue Applications of Internet of Things)

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15 pages, 5900 KiB

Open AccessArticle

Computer-Aided Panoramic Images Enriched by Shadow Construction on a Prism and Pyramid Polyhedral Surface

by Jolanta Dzwierzynska

Department of Architectural Design and Engineering Graphics, Rzeszow University of Technology, Powstancow Warszawy 12, 35-959 Rzeszow, Poland

Symmetry 2017, 9(10), 214; https://doi.org/10.3390/sym9100214 - 3 Oct 2017

Cited by 6 | Viewed by 5154

Abstract

The aim of this study is to develop an efficient and practical method of a direct mapping of a panoramic projection on an unfolded prism and pyramid polyhedral projection surface with the aid of a computer. Due to the fact that straight lines [...] Read more.

The aim of this study is to develop an efficient and practical method of a direct mapping of a panoramic projection on an unfolded prism and pyramid polyhedral projection surface with the aid of a computer. Due to the fact that straight lines very often appear in any architectural form we formulate algorithms which utilize data about lines and draw panoramas as plots of functions in Mathcad software. The ability to draw panoramic images of lines enables drawing a wireframe image of an architectural object. The application of the multicenter projection, as well as the idea of shadow construction in the panoramic representation, aims at achieving a panoramic image close to human perception. The algorithms are universal as the application of changeable base elements of panoramic projection—horizon height, station point location, number of polyhedral walls—enables drawing panoramic images from various viewing positions. However, for more efficient and easier drawing, the algorithms should be implemented in some graphical package. The representation presented in the paper and the method of its direct mapping on a flat unfolded projection surface can find application in the presentation of architectural spaces in advertising and art when drawings are displayed on polyhedral surfaces and can be observed from multiple viewing positions. Full article

(This article belongs to the Special Issue Polyhedral Structures)

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33 pages, 716 KiB

Open AccessFeature PaperArticle

Occurrence of Chiral Bioactive Compounds in the Aquatic Environment: A Review

by Cláudia Ribeiro^1,2,†

, Ana Rita Ribeiro^3,*,†, Alexandra S. Maia^1,4 and Maria Elizabeth Tiritan^1,2,5

¹ CESPU, Instituto de Investigação e Formação Avançada em Ciências e Tecnologias da Saúde, Rua Central de Gandra, 1317, 4585-116 Gandra PRD, Portugal

² Centro Interdisciplinar de Investigação Marinha e Ambiental (CIIMAR/CIMAR), Universidade do Porto, Rua dos Bragas 289, 4050-123 Porto, Portugal

³ Laboratory of Separation and Reaction Engineering—Laboratory of Catalysis and Materials (LSRE-LCM), Faculdade de Engenharia, Universidade do Porto, Rua Dr. Roberto Frias s/n, 4200-465 Porto, Portugal

⁴ Universidade Católica Portuguesa, CBQF—Centro de Biotecnologia e Química Fina—Laboratório Associado, Escola Superior de Biotecnologia, Rua Arquiteto Lobão Vital, Apartado 2511, 4202-401 Porto, Portugal

⁵ Laboratório de Química Orgânica e Farmacêutica, Departamento de Ciências Químicas, Faculdade de Farmácia da Universidade do Porto, Rua de Jorge Viterbo Ferreira, 228, 4050-313 Porto, Portugal

^† Joint 1st Authors.

Symmetry 2017, 9(10), 215; https://doi.org/10.3390/sym9100215 - 3 Oct 2017

Cited by 35 | Viewed by 6350

Abstract

In recent decades, the presence of micropollutants in the environment has been extensively studied due to their high frequency of occurrence, persistence and possible adverse effects to exposed organisms. Concerning chiral micropollutants in the environment, enantiomers are frequently ignored and enantiomeric composition often [...] Read more.

In recent decades, the presence of micropollutants in the environment has been extensively studied due to their high frequency of occurrence, persistence and possible adverse effects to exposed organisms. Concerning chiral micropollutants in the environment, enantiomers are frequently ignored and enantiomeric composition often neglected. However, enantioselective toxicity is well recognized, highlighting the need to include enantioselectivity in environmental risk assessment. Additionally, the information about enantiomeric fraction (EF) is crucial since it gives insights about: (i) environmental fate (i.e., occurrence, distribution, removal processes and (bio)degradation); (ii) illicit discharges; (iii) consumption pattern (e.g., illicit drugs, pharmaceuticals used as recreational drugs, illicit use of pesticides); and (iv) enantioselective toxicological effects. Thus, the purpose of this paper is to provide a comprehensive review about the enantioselective occurrence of chiral bioactive compounds in aquatic environmental matrices. These include pharmaceuticals, illicit drugs, pesticides, polychlorinated biphenyls (PCBs) and polycyclic musks (PCMs). Most frequently analytical methods used for separation of enantiomers were liquid chromatography and gas chromatography methodologies using both indirect (enantiomerically pure derivatizing reagents) and direct methods (chiral stationary phases). The occurrence of these chiral micropollutants in the environment is reviewed and future challenges are outlined. Full article

(This article belongs to the Special Issue Chiral Separations)

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17 pages, 3492 KiB

Open AccessArticle

An Interactive Personalized Recommendation System Using the Hybrid Algorithm Model

by Yan Guo, Minxi Wang^* and Xin Li^*

College of Management Science, Chengdu University of Technology, Chengdu 610059, China

Symmetry 2017, 9(10), 216; https://doi.org/10.3390/sym9100216 - 6 Oct 2017

Cited by 33 | Viewed by 9790

Abstract

With the rapid development of e-commerce, the contradiction between the disorder of business information and customer demand is increasingly prominent. This study aims to make e-commerce shopping more convenient, and avoid information overload, by an interactive personalized recommendation system using the hybrid algorithm [...] Read more.

With the rapid development of e-commerce, the contradiction between the disorder of business information and customer demand is increasingly prominent. This study aims to make e-commerce shopping more convenient, and avoid information overload, by an interactive personalized recommendation system using the hybrid algorithm model. The proposed model first uses various recommendation algorithms to get a list of original recommendation results. Combined with the customer’s feedback in an interactive manner, it then establishes the weights of corresponding recommendation algorithms. Finally, the synthetic formula of evidence theory is used to fuse the original results to obtain the final recommendation products. The recommendation performance of the proposed method is compared with that of traditional methods. The results of the experimental study through a Taobao online dress shop clearly show that the proposed method increases the efficiency of data mining in the consumer coverage, the consumer discovery accuracy and the recommendation recall. The hybrid recommendation algorithm complements the advantages of the existing recommendation algorithms in data mining. The interactive assigned-weight method meets consumer demand better and solves the problem of information overload. Meanwhile, our study offers important implications for e-commerce platform providers regarding the design of product recommendation systems. Full article

(This article belongs to the Special Issue Information Technology and Its Applications)

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11 pages, 439 KiB

Open AccessArticle

Exact Finite Differences. The Derivative on Non Uniformly Spaced Partitions

by Armando Martínez-Pérez

and Gabino Torres-Vega^*

Physics Department, Cinvestav, Apdo. postal 14-740, 07300 Mexico City, Mexico

Symmetry 2017, 9(10), 217; https://doi.org/10.3390/sym9100217 - 7 Oct 2017

Cited by 3 | Viewed by 3235

Abstract

We define a finite-differences derivative operation, on a non uniformly spaced partition, which has the exponential function as an exact eigenvector. We discuss some properties of this operator and we propose a definition for the components of a finite-differences momentum operator. This allows [...] Read more.

We define a finite-differences derivative operation, on a non uniformly spaced partition, which has the exponential function as an exact eigenvector. We discuss some properties of this operator and we propose a definition for the components of a finite-differences momentum operator. This allows us to perform exact discrete calculations. Full article

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9 pages, 713 KiB

Open AccessArticle

On the Fibration Defined by the Field Lines of a Knotted Class of Electromagnetic Fields at a Particular Time

by Manuel Arrayás^†

and José L. Trueba^*,†

¹ Área de Electromagnetismo, Universidad Rey Juan Carlos, Calle Tulipán s/n, 28933 Móstoles (Madrid), Spain

^† These authors contributed equally to this work.

Symmetry 2017, 9(10), 218; https://doi.org/10.3390/sym9100218 - 9 Oct 2017

Cited by 7 | Viewed by 3817

Abstract

A class of vacuum electromagnetic fields in which the field lines are knotted curves are reviewed. The class is obtained from two complex functions at a particular instant

t = 0

so they inherit the topological properties of red the level curves of [...] Read more.

A class of vacuum electromagnetic fields in which the field lines are knotted curves are reviewed. The class is obtained from two complex functions at a particular instant

t = 0

so they inherit the topological properties of red the level curves of these functions. We study the complete topological structure defined by the magnetic and electric field lines at

t = 0

. This structure is not conserved in time in general, although it is possible to red find special cases in which the field lines are topologically equivalent for every value of t. Full article

(This article belongs to the Special Issue Knot Theory and Its Applications)

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15 pages, 530 KiB

Open AccessArticle

Experimental Design for Testing Local Lorentz Invariance Violations in Gravity

by Ya-Fen Chen, Yu-Jie Tan and Cheng-Gang Shao^*

Key Laboratory of Fundamental Physical Quantities Measurement of Ministry of Education, Hubei Key Laboratory of Gravitation and Quantum Physics, School of Physics, Huazhong University of Science and Technology, Wuhan 430074, China

Symmetry 2017, 9(10), 219; https://doi.org/10.3390/sym9100219 - 10 Oct 2017

Cited by 7 | Viewed by 5074

Abstract

Local Lorentz invariance is an important component of General Relativity. Testing for Local Lorentz invariance can not only probe the foundation stone of General Relativity but also help to explore the unified theory for General Relativity and quantum mechanics. In this paper, we [...] Read more.

Local Lorentz invariance is an important component of General Relativity. Testing for Local Lorentz invariance can not only probe the foundation stone of General Relativity but also help to explore the unified theory for General Relativity and quantum mechanics. In this paper, we search the Local Lorentz invariance violation associated with operators of mass dimension

d = 6

in the pure-gravity sector with short-range gravitational experiments. To enlarge the Local Lorentz invariance violation signal effectively, we design a new experiment in which the constraints of all fourteen violation coefficients may be improved by about one order of magnitude. Full article

(This article belongs to the Special Issue Violation of Lorentz Symmetry)

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25 pages, 2477 KiB

Open AccessArticle

Energy Efficient Fuzzy Adaptive Verification Node Selection-Based Path Determination in Wireless Sensor Networks

by Muhammad Akram¹ and Tae Ho Cho^2,*

¹ College of Information and Communication Engineering, Sungkyunkwan University, Suwon 16419, Korea

² College of Software, Sungkyunkwan University, Suwon 16419, Korea

Symmetry 2017, 9(10), 220; https://doi.org/10.3390/sym9100220 - 10 Oct 2017

Cited by 1 | Viewed by 4187

Abstract

Wireless sensor networks are supplied with limited energy resources and are usually installed in unattended and unfriendly environments. These networks are also highly exposed to security attacks aimed at draining the energy of the network to render it unresponsive. Adversaries launch counterfeit report [...] Read more.

Wireless sensor networks are supplied with limited energy resources and are usually installed in unattended and unfriendly environments. These networks are also highly exposed to security attacks aimed at draining the energy of the network to render it unresponsive. Adversaries launch counterfeit report injection attacks and false vote injection attacks through compromised sensor nodes. Several filtering solutions have been suggested for detecting and filtering false reports during the multi-hop forwarding process. However, almost all such schemes presuppose a conventional underlying protocol for data routing that do not consider the attack status or energy dissipation on the route. Each design provides approximately the equivalent resilience in terms of protection against compromised node. However, the energy consumption characteristics of each design differ. We propose a fuzzy adaptive path selection to save energy and avoid the emergence of favored paths. Fresh authentication keys are generated periodically, and these are shared with the filtering nodes to restrict compromised intermediate filtering nodes from the verification process. The scheme helps delay the emergence of hotspot problems near the base station and exhibits improved energy conserving behavior in wireless sensor networks. The proposed scheme provides an extended network lifetime and better false data filtering capacity. Full article

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31 pages, 13885 KiB

Open AccessArticle

Intelligent Aggregation Based on Content Routing Scheme for Cloud Computing

by Jiachen Xu¹, Xiao Liu¹, Ming Ma², Anfeng Liu^1,*

, Tian Wang³ and Changqin Huang⁴

¹ School of Information Science and Engineering, Central South University, Changsha 410083, China

² Department of Computer Science, Stony Brook University, Stony Brook, NY 11794, USA

³ Department of School of Computer Science and Technology, Huaqiao University, Quanzhou 362000, China

⁴ School of Information Technology in Education, South China Normal University, Guangzhou 510631, China

Symmetry 2017, 9(10), 221; https://doi.org/10.3390/sym9100221 - 11 Oct 2017

Cited by 17 | Viewed by 5785

Abstract

Cloud computing has emerged as today’s most exciting computing paradigm for providing services using a shared framework, which opens a new door for solving the problems of the explosive growth of digital resource demands and their corresponding convenience. With the exponential growth of [...] Read more.

Cloud computing has emerged as today’s most exciting computing paradigm for providing services using a shared framework, which opens a new door for solving the problems of the explosive growth of digital resource demands and their corresponding convenience. With the exponential growth of the number of data types and data size in so-called big data work, the backbone network is under great pressure due to its transmission capacity, which is lower than the growth of the data size and would seriously hinder the development of the network without an effective approach to solve this problem. In this paper, an Intelligent Aggregation based on a Content Routing (IACR) scheme for cloud computing, which could reduce the amount of data in the network effectively and play a basic supporting role in the development of cloud computing, is first put forward. All in all, the main innovations in this paper are: (1) A framework for intelligent aggregation based on content routing is proposed, which can support aggregation based content routing; (2) The proposed IACR scheme could effectively route the high aggregation ratio data to the data center through the same routing path so as to effectively reduce the amount of data that the network transmits. The theoretical analyses experiments and results show that, compared with the previous original routing scheme, the IACR scheme can balance the load of the whole network, reduce the amount of data transmitted in the network by 41.8%, and reduce the transmission time by 31.6% in the same network with a more balanced network load. Full article

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15 pages, 4526 KiB

Open AccessArticle

Evaluation of Airplane Boarding/Deboarding Strategies: A Surrogate Experimental Test

by Shengjie Qiang¹, Bin Jia^2,* and Qingxia Huang²

¹ College of Transportation and Logistics, East China Jiaotong University, Nanchang 330013, China

² School of Traffic and Transportation, Beijing Jiaotong University, Beijing 100044, China

Symmetry 2017, 9(10), 222; https://doi.org/10.3390/sym9100222 - 11 Oct 2017

Cited by 19 | Viewed by 7306

Abstract

Optimally organizing passengers boarding/deboarding an airplane offers a potential way to reduce the airplane turn time. The main contribution of our work is that we evaluate seven boarding strategies and two structured deboarding strategies by using a surrogate experimental test. Instead of boarding [...] Read more.

Optimally organizing passengers boarding/deboarding an airplane offers a potential way to reduce the airplane turn time. The main contribution of our work is that we evaluate seven boarding strategies and two structured deboarding strategies by using a surrogate experimental test. Instead of boarding a real or mocked airplane, we carried out the experiment by organizing 40 participants to board a school bus with ten rows of four seats, symmetrically distributed on a single, central aisle. Experimental results confirm that the optimized strategies, i.e., Steffen and Steffen-lug, are superior to the traditional ones, i.e., Back-to-front, Window-to-aisle, and Random in time-saving and stability. However, the two structured deboarding strategies failed to reduce the deboarding time, and this result strongly suggests the prerequisites of applying such strategies only when, on average, passengers have a large amount of luggage. Besides, we further carried out a questionnaire survey of participants’ preferences on seat layout and discussed how those preferences influence the boarding time. Full article

(This article belongs to the Special Issue Civil Engineering and Symmetry)

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25 pages, 14363 KiB

Open AccessArticle

Reversible Dual-Image-Based Hiding Scheme Using Block Folding Technique

by Tzu-Chuen Lu^1,*

and Hui-Shih Leng²

¹ Department of Information Management, Chaoyang University of Technology, Taichung 41349, Taiwan

² Department of Mathematics, National Changhua University of Education, Changhua 50058, Taiwan

Symmetry 2017, 9(10), 223; https://doi.org/10.3390/sym9100223 - 12 Oct 2017

Cited by 11 | Viewed by 4901

Abstract

The concept of a dual-image based scheme in information sharing consists of concealing secret messages in two cover images; only someone who has both stego-images can extract the secret messages. In 2015, Lu et al. proposed a center-folding strategy where each secret symbol [...] Read more.

The concept of a dual-image based scheme in information sharing consists of concealing secret messages in two cover images; only someone who has both stego-images can extract the secret messages. In 2015, Lu et al. proposed a center-folding strategy where each secret symbol is folded into the reduced digit to reduce the distortion of the stego-image. Then, in 2016, Lu et al. used a frequency-based encoding strategy to reduce the distortion of the frequency of occurrence of the maximum absolute value. Because the folding strategy can obviously reduce the value, the proposed scheme includes the folding operation twice to further decrease the reduced digit. We use a frequency-based encoding strategy to encode a secret message and then use the block folding technique by performing the center-folding operation twice to embed secret messages. An indicator is needed to identify the sequence number of the folding operation. The proposed scheme collects several indicators to produce a combined code and hides the code in a pixel to reduce the size of the indicators. The experimental results show that the proposed method can achieve higher image quality under the same embedding rate or higher payload, which is better than other methods. Full article

(This article belongs to the Special Issue Information Technology and Its Applications)

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9 pages, 281 KiB

Open AccessArticle

Asymmetric Equivalences in Fuzzy Logic

by Bo Hu¹, Lvqing Bi², Sizhao Li³ and Songsong Dai^3,*

¹ School of Mechanical and Electrical Engineering, Guizhou Normal University, Guiyang 550025, China

² School of Electronics and Communication Engineering, Yulin Normal University, Yulin 537000, China

³ School of Information Science and Engineering, Xiamen University, Xiamen 361005, China

Symmetry 2017, 9(10), 224; https://doi.org/10.3390/sym9100224 - 13 Oct 2017

Cited by 4 | Viewed by 4161

Abstract

We introduce a new class of operations called asymmetric equivalences. Several properties of asymmetric equivalence operations have been investigated. Based on the asymmetric equivalence, quasi-metric spaces are constructed on [0, 1]. Finally, we discuss symmetrization of asymmetric equivalences. Full article

(This article belongs to the Special Issue Symmetry in Fuzzy Sets and Systems)

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10 pages, 241 KiB

Open AccessArticle

Magnetic Transport in Spin Antiferromagnets for Spintronics Applications

by Mohamed Azzouz

Department of Physics, Laurentian University, Ramsey Lake Road, Sudbury, ON P3E 2C6, Canada

Symmetry 2017, 9(10), 225; https://doi.org/10.3390/sym9100225 - 13 Oct 2017

Cited by 1 | Viewed by 3997

Abstract

Had magnetic monopoles been ubiquitous as electrons are, we would probably have had a different form of matter, and power plants based on currents of these magnetic charges would have been a familiar scene of modern technology. Magnetic dipoles do exist, however, and [...] Read more.

Had magnetic monopoles been ubiquitous as electrons are, we would probably have had a different form of matter, and power plants based on currents of these magnetic charges would have been a familiar scene of modern technology. Magnetic dipoles do exist, however, and in principle one could wonder if we can use them to generate magnetic currents. In the present work, we address the issue of generating magnetic currents and magnetic thermal currents in electrically-insulating low-dimensional Heisenberg antiferromagnets by invoking the (broken) electricity-magnetism duality symmetry. The ground state of these materials is a spin-liquid state that can be described well via the Jordan–Wigner fermions, which permit an easy definition of the magnetic particle and thermal currents. The magnetic and magnetic thermal conductivities are calculated in the present work using the bond–mean field theory. The spin-liquid states in these antiferromagnets are either gapless or gapped liquids of spinless fermions whose flow defines a current just as the one defined for electrons in a Fermi liquid. The driving force for the magnetic current is a magnetic field with a gradient along the magnetic conductor. We predict the generation of a magneto-motive force and realization of magnetic circuits using low-dimensional Heisenberg antiferromagnets. The present work is also about claiming that what the experiments in spintronics attempt to do is trying to treat the magnetic degrees of freedoms on the same footing as the electronic ones. Full article

(This article belongs to the Special Issue Symmetry and Symmetry Breaking in Quantum Mechanics)

29 pages, 448 KiB

Open AccessFeature PaperArticle

Skein Invariants of Links and Their State Sum Models

by Louis H. Kauffman^1,† and Sofia Lambropoulou^2,*,†

¹ Department of Mathematics, Statistics and Computer Science, University of Illinois at Chicago, Chicago, IL 60607-7045, USA

² School of Applied Mathematical and Physical Sciences, National Technical University of Athens, 15780 Athens, Greece

^† These authors contributed equally to this work.

Symmetry 2017, 9(10), 226; https://doi.org/10.3390/sym9100226 - 13 Oct 2017

Cited by 6 | Viewed by 4575

Abstract

We present the new skein invariants of classical links,

H [H]

,

K [K]

and

D [D]

, based on the invariants of links, H, K and D, denoting the regular isotopy version of the [...] Read more.

We present the new skein invariants of classical links,

H [H]

,

K [K]

and

D [D]

, based on the invariants of links, H, K and D, denoting the regular isotopy version of the Homflypt polynomial, the Kauffman polynomial and the Dubrovnik polynomial. The invariants are obtained by abstracting the skein relation of the corresponding invariant and making a new skein algorithm comprising two computational levels: first producing unlinked knotted components, then evaluating the resulting knots. The invariants in this paper, were revealed through the skein theoretic definition of the invariants

Θ_{d}

related to the Yokonuma–Hecke algebras and their 3-variable generalization

Θ

, which generalizes the Homflypt polynomial.

H [H]

is the regular isotopy counterpart of

Θ

. The invariants

K [K]

and

D [D]

are new generalizations of the Kauffman and the Dubrovnik polynomials. We sketch skein theoretic proofs of the well-definedness and topological properties of these invariants. The invariants of this paper are reformulated into summations of the generating invariants (H, K, D) on sublinks of the given link L, obtained by partitioning L into collections of sublinks. The first such reformulation was achieved by W.B.R. Lickorish for the invariant

Θ

and we generalize it to the Kauffman and Dubrovnik polynomial cases. State sum models are formulated for all the invariants. These state summation models are based on our skein template algorithm which formalizes the skein theoretic process as an analogue of a statistical mechanics partition function. Relationships with statistical mechanics models are articulated. Finally, we discuss physical situations where a multi-leveled course of action is taken naturally. Full article

(This article belongs to the Special Issue Knot Theory and Its Applications)

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31 pages, 325 KiB

Open AccessArticle

Bounded Solutions to Nonhomogeneous Linear Second-Order Difference Equations

by Stevo Stević^1,2

¹ Mathematical Institute of the Serbian Academy of Sciences, Knez Mihailova 36/III, 11000 Beograd, Serbia

² Operator Theory and Applications Research Group, Department of Mathematics, King Abdulaziz University, P.O. Box 80203, Jeddah 21589, Saudi Arabia

Symmetry 2017, 9(10), 227; https://doi.org/10.3390/sym9100227 - 14 Oct 2017

Cited by 29 | Viewed by 3680

Abstract

By using some solvability methods and the contraction mapping principle are investigated bounded, as well as periodic solutions to some classes of nonhomogeneous linear second-order difference equations on domains

N_{0}

,

Z ∖ N_{2}

and

Z

. The case when the [...] Read more.

By using some solvability methods and the contraction mapping principle are investigated bounded, as well as periodic solutions to some classes of nonhomogeneous linear second-order difference equations on domains

N_{0}

,

Z ∖ N_{2}

and

Z

. The case when the coefficients of the equation are constant and the zeros of the characteristic polynomial associated to the corresponding homogeneous equation do not belong to the unit circle is described in detail. Full article

(This article belongs to the Special Issue Difference Equations, Symmetric, Close to Symmetric and Cyclic Systems of Difference Equations)

16 pages, 1588 KiB

Open AccessArticle

Decomposition and Intersection of Two Fuzzy Numbers for Fuzzy Preference Relations

by Hui-Chin Tang

Department of Industrial Engineering and Management, National Kaohsiung University of Applied Sciences, Kaohsiung 80778, Taiwan

Symmetry 2017, 9(10), 228; https://doi.org/10.3390/sym9100228 - 14 Oct 2017

Cited by 4 | Viewed by 5038

Abstract

In fuzzy decision problems, the ordering of fuzzy numbers is the basic problem. The fuzzy preference relation is the reasonable representation of preference relations by a fuzzy membership function. This paper studies Nakamura’s and Kołodziejczyk’s preference relations. Eight cases, each representing different levels [...] Read more.

In fuzzy decision problems, the ordering of fuzzy numbers is the basic problem. The fuzzy preference relation is the reasonable representation of preference relations by a fuzzy membership function. This paper studies Nakamura’s and Kołodziejczyk’s preference relations. Eight cases, each representing different levels of overlap between two triangular fuzzy numbers are considered. We analyze the ranking behaviors of all possible combinations of the decomposition and intersection of two fuzzy numbers through eight extensive test cases. The results indicate that decomposition and intersection can affect the fuzzy preference relations, and thereby the final ranking of fuzzy numbers. Full article

(This article belongs to the Special Issue Fuzzy Techniques for Decision Making)

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13 pages, 1951 KiB

Open AccessArticle

A General Zero Attraction Proportionate Normalized Maximum Correntropy Criterion Algorithm for Sparse System Identification

by Yingsong Li^1,2,*

, Yanyan Wang¹, Felix Albu³

and Jingshan Jiang²

¹ College of Information and Communication Engineering, Harbin Engineering University, Harbin 150001, China

² National Space Science Center, Chinese Academy of Sciences, Beijing 100190, China

³ Department of Electronics, Valahia University of Targoviste, 130082 Targoviste, Romania

Symmetry 2017, 9(10), 229; https://doi.org/10.3390/sym9100229 - 15 Oct 2017

Cited by 41 | Viewed by 4203

Abstract

A general zero attraction (GZA) proportionate normalized maximum correntropy criterion (GZA-PNMCC) algorithm is devised and presented on the basis of the proportionate-type adaptive filter techniques and zero attracting theory to highly improve the sparse system estimation behavior of the classical MCC algorithm within [...] Read more.

A general zero attraction (GZA) proportionate normalized maximum correntropy criterion (GZA-PNMCC) algorithm is devised and presented on the basis of the proportionate-type adaptive filter techniques and zero attracting theory to highly improve the sparse system estimation behavior of the classical MCC algorithm within the framework of the sparse system identifications. The newly-developed GZA-PNMCC algorithm is carried out by introducing a parameter adjusting function into the cost function of the typical proportionate normalized maximum correntropy criterion (PNMCC) to create a zero attraction term. The developed optimization framework unifies the derivation of the zero attraction-based PNMCC algorithms. The developed GZA-PNMCC algorithm further exploits the impulsive response sparsity in comparison with the proportionate-type-based NMCC algorithm due to the GZA zero attraction. The superior performance of the GZA-PNMCC algorithm for estimating a sparse system in a non-Gaussian noise environment is proven by simulations. Full article

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12 pages, 225 KiB

Open AccessArticle

Gravity Theories with Background Fields and Spacetime Symmetry Breaking

by Robert Bluhm

Colby College, Department of Physics and Astronomy, Mayflower Hill 5862, Waterville, Maine, 04901, USA

Symmetry 2017, 9(10), 230; https://doi.org/10.3390/sym9100230 - 16 Oct 2017

Cited by 15 | Viewed by 3855

Abstract

An overview is given of effective gravitational field theories with fixed background fields that break spacetime symmetry. The behavior of the background fields and the types of excitations that can occur depend on whether the symmetry breaking is explicit or spontaneous. For example, [...] Read more.

An overview is given of effective gravitational field theories with fixed background fields that break spacetime symmetry. The behavior of the background fields and the types of excitations that can occur depend on whether the symmetry breaking is explicit or spontaneous. For example, when the breaking is spontaneous, the background field is dynamical and massless Nambu–Goldstone and massive Higgs excitations can appear. However, if the breaking is explicit, the background is nondynamical, and in this case additional metric or vierbein excitations occur due to the loss of local symmetry, or these excitations can be replaced by dynamical scalar fields using a Stückelberg approach. The interpretation of Noether identities that must hold in each case differs, depending on the type of symmetry breaking, and this affects the nature of the consistency conditions that must hold. The Noether identities also shed light on why the Stückelberg approach works, and how it is able to restore the broken spacetime symmetry in a theory with explicit breaking. Full article

(This article belongs to the Special Issue Violation of Lorentz Symmetry)

15 pages, 3665 KiB

Open AccessArticle

Multiple Signal Classification Algorithm Based Electric Dipole Source Localization Method in an Underwater Environment

by Yidong Xu¹

, Wei Xue^1,*, Yingsong Li^1,2,*

, Lili Guo¹ and Wenjing Shang¹

¹ College of Information and Communication Engineering, Harbin Engineering University, Harbin 150001, China

² National Space Science Center, Chinese Academy of Sciences, Beijing 100190, China

Symmetry 2017, 9(10), 231; https://doi.org/10.3390/sym9100231 - 17 Oct 2017

Cited by 8 | Viewed by 4821

Abstract

A novel localization method based on multiple signal classification (MUSIC) algorithm is proposed for positioning an electric dipole source in a confined underwater environment by using electric dipole-receiving antenna array. In this method, the boundary element method (BEM) is introduced to analyze the [...] Read more.

A novel localization method based on multiple signal classification (MUSIC) algorithm is proposed for positioning an electric dipole source in a confined underwater environment by using electric dipole-receiving antenna array. In this method, the boundary element method (BEM) is introduced to analyze the boundary of the confined region by use of a matrix equation. The voltage of each dipole pair is used as spatial-temporal localization data, and it does not need to obtain the field component in each direction compared with the conventional fields based localization method, which can be easily implemented in practical engineering applications. Then, a global-multiple region-conjugate gradient (CG) hybrid search method is used to reduce the computation burden and to improve the operation speed. Two localization simulation models and a physical experiment are conducted. Both the simulation results and physical experiment result provide accurate positioning performance, with the help to verify the effectiveness of the proposed localization method in underwater environments. Full article

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15 pages, 284 KiB

Open AccessArticle

Open Gromov-Witten Invariants from the Augmentation Polynomial

by Matthew Mahowald^†

¹ Department of Mathematics, Northwestern University, Evanston, IL 60208, USA

^† Current address: 222 S Riverside Plaza Ste 2800, Chicago, IL 60606, USA.

Symmetry 2017, 9(10), 232; https://doi.org/10.3390/sym9100232 - 17 Oct 2017

Viewed by 3644

Abstract

A conjecture of Aganagic and Vafa relates the open Gromov-Witten theory of

X = O_{P^{1}} (- 1, - 1)

to the augmentation polynomial of Legendrian contact homology. We describe how to use this conjecture to compute genus zero, [...] Read more.

A conjecture of Aganagic and Vafa relates the open Gromov-Witten theory of

X = O_{P^{1}} (- 1, - 1)

to the augmentation polynomial of Legendrian contact homology. We describe how to use this conjecture to compute genus zero, one boundary component open Gromov-Witten invariants for Lagrangian submanifolds

L_{K} \subset X

obtained from the conormal bundles of knots

K \subset S^{3}

. This computation is then performed for two non-toric examples (the figure-eight and three-twist knots). For

(r, s)

torus knots, the open Gromov-Witten invariants can also be computed using Atiyah-Bott localization. Using this result for the unknot and the

(3, 2)

torus knot, we show that the augmentation polynomial can be derived from these open Gromov-Witten invariants. Full article

(This article belongs to the Special Issue Knot Theory and Its Applications)

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12 pages, 724 KiB

Open AccessArticle

How to Obtain Common Criteria Certification of Smart TV for Home IoT Security and Reliability

by Sooyoung Kang and Seungjoo Kim^*

CIST (Center for Information Security Technologies), Korea University, Seoul 02841, Korea

Symmetry 2017, 9(10), 233; https://doi.org/10.3390/sym9100233 - 17 Oct 2017

Cited by 11 | Viewed by 6636

Abstract

In the new era of IoT (Internet of Things), numerous gadgets and services include innovative IoT technologies that provide customers with convenience and improve their quality of life. Smart TVs are typical IoT devices that offer broadcasting services. However, they are susceptible to [...] Read more.

In the new era of IoT (Internet of Things), numerous gadgets and services include innovative IoT technologies that provide customers with convenience and improve their quality of life. Smart TVs are typical IoT devices that offer broadcasting services. However, they are susceptible to security intrusions via e-mail, media players, cameras, and internet connectivity. The frequency of hacking through malicious applications installed in Smart TV has rapidly increased. Therefore, appropriate countermeasures should be developed immediately. In April 2017, we (with LG electronics) received the ‘world-first’ Common Criteria EAL2 (Evaluation Assurance Level 2) certification for Smart TVs. As far as we know, no Smart TV has received a Common Criteria EAL2 security certification until now. This article describes our experience with the certification process and examines several security and reliability aspects of Smart TVs. Full article

(This article belongs to the Special Issue Advances in Future Internet and Industrial Internet of Things)

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23 pages, 2976 KiB

Open AccessFeature PaperArticle

Managing Non-Homogeneous Information and Experts’ Psychological Behavior in Group Emergency Decision Making

by Liang Wang^1,2, Álvaro Labella¹, Rosa M. Rodríguez^3,*, Ying-Ming Wang² and Luis Martínez¹

¹ Department of Computer Science, University of Jaén, 23071 Jaén, Spain

² Decision Sciences Institute, Fuzhou University, Fuzhou 350116, China

³ Department of Computer Science and A.I., University of Granada, 18071 Granada, Spain

Symmetry 2017, 9(10), 234; https://doi.org/10.3390/sym9100234 - 18 Oct 2017

Cited by 26 | Viewed by 6054

Abstract

After an emergency event (EE) happens, emergency decision making (EDM) is a common and effective way to deal with the emergency situation, which plays an important role in mitigating its level of harm. In the real world, it is a big challenge for [...] Read more.

After an emergency event (EE) happens, emergency decision making (EDM) is a common and effective way to deal with the emergency situation, which plays an important role in mitigating its level of harm. In the real world, it is a big challenge for an individual emergency manager (EM) to make a proper and comprehensive decision for coping with an EE. Consequently, many practical EDM problems drive group emergency decision making (GEDM) problems whose main limitations are related to the lack of flexibility in knowledge elicitation, disagreements in the group and the consideration of experts’ psychological behavior in the decision process. Hence, this paper proposes a novel GEDM approach that allows more flexibility for preference elicitation under uncertainty, provides a consensus process to avoid disagreements and considers experts’ psychological behavior by using the fuzzy TODIM method based on prospect theory. Eventually, a group decision support system (GDSS) is developed to support the whole GEDM process defined in the proposed method demonstrating its novelty, validity and feasibility. Full article

(This article belongs to the Special Issue Fuzzy Techniques for Decision Making)

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10 pages, 2360 KiB

Open AccessFeature PaperArticle

A Retinal Vessel Detection Approach Based on Shearlet Transform and Indeterminacy Filtering on Fundus Images

by Yanhui Guo^1,*

, Ümit Budak²

, Abdulkadir Şengür³

and Florentin Smarandache⁴

¹ Department of Computer Science, University of Illinois at Springfield, Springfield, IL 62703, USA

² Engineering Faculty, Department of Electrical-Electronics Engineering, Bitlis Eren University, 13000 Bitlis, Turkey

³ Technology Faculty, Department of Electrical and Electronics Engineering, Firat University, 23119 Elazig, Turkey

⁴ Mathematics & Science Department, University of New Mexico, 705 Gurley Ave., Gallup, NM 87301, USA

Symmetry 2017, 9(10), 235; https://doi.org/10.3390/sym9100235 - 19 Oct 2017

Cited by 34 | Viewed by 5832

Abstract

A fundus image is an effective tool for ophthalmologists studying eye diseases. Retinal vessel detection is a significant task in the identification of retinal disease regions. This study presents a retinal vessel detection approach using shearlet transform and indeterminacy filtering. The fundus image’s [...] Read more.

A fundus image is an effective tool for ophthalmologists studying eye diseases. Retinal vessel detection is a significant task in the identification of retinal disease regions. This study presents a retinal vessel detection approach using shearlet transform and indeterminacy filtering. The fundus image’s green channel is mapped in the neutrosophic domain via shearlet transform. The neutrosophic domain images are then filtered with an indeterminacy filter to reduce the indeterminacy information. A neural network classifier is employed to identify the pixels whose inputs are the features in neutrosophic images. The proposed approach is tested on two datasets, and a receiver operating characteristic curve and the area under the curve are employed to evaluate experimental results quantitatively. The area under the curve values are 0.9476 and 0.9469 for each dataset respectively, and 0.9439 for both datasets. The comparison with the other algorithms also illustrates that the proposed method yields the highest evaluation measurement value and demonstrates the efficiency and accuracy of the proposed method. Full article

(This article belongs to the Special Issue Neutrosophic Theories Applied in Engineering)

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17 pages, 3297 KiB

Open AccessArticle

SINR-Based MCS Level Adaptation in CSMA/CA Wireless Networks to Embrace IoT Devices

by Soohyun Cho

Department of General Studies, Hongik University, Seoul 04066, Korea

Symmetry 2017, 9(10), 236; https://doi.org/10.3390/sym9100236 - 19 Oct 2017

Cited by 6 | Viewed by 5816

Abstract

This paper presents an automatic modulation and coding scheme (MCS) level adaptation algorithm to embrace Internet of Things (IoT) devices by improving the area spectral efficiency of carrier-sense multiple access with collision avoidance (CSMA/CA) wireless networks. In the proposed algorithm, senders of CSMA/CA [...] Read more.

This paper presents an automatic modulation and coding scheme (MCS) level adaptation algorithm to embrace Internet of Things (IoT) devices by improving the area spectral efficiency of carrier-sense multiple access with collision avoidance (CSMA/CA) wireless networks. In the proposed algorithm, senders of CSMA/CA wireless networks use the signal to interference plus noise ratio of acknowledgment frames from their receivers to estimate channel statuses between the senders and the receivers. Using the estimated channel status of each receiver, senders control sending rates of traffic by adjusting MCS levels of packets destined for each receiver. We use Poisson point processes (PPPs) to model the locations of participating nodes (i.e., access points and wireless devices) in a given area. We evaluate the effectiveness of the proposed algorithm using an event-driven ns-2 simulator for various PPP densities of access points and wireless devices. Full article

(This article belongs to the Special Issue Advances in Future Internet and Industrial Internet of Things)

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22 pages, 5439 KiB

Open AccessArticle

Internet of THings Area Coverage Analyzer (ITHACA) for Complex Topographical Scenarios

by Raúl Parada^1,2,*

, Daniel Cárdenes-Tacoronte²

, Carlos Monzo^2,3

and Joan Melià-Seguí^2,4

¹ Department of Information Engineering, University of Padua (UNIPD), Via Gradenigo 6/b, 35131 Padova, Italy

² Faculty of Computer Science, Multimedia and Telecommunications, Universitat Oberta de Catalunya (UOC), Rambla del Poblenou 156, 08018 Barcelona, Spain

³ eLearn Center, Universitat Oberta de Catalunya (UOC), Rambla del Poble Nou 156, 08018 Barcelona, Spain

⁴ Internet Interdisciplinary Institute, Universitat Oberta de Catalunya (UOC), Av. Carl Friedrich Gauss 5, 08860 Castelldefels, Spain

Symmetry 2017, 9(10), 237; https://doi.org/10.3390/sym9100237 - 19 Oct 2017

Cited by 9 | Viewed by 6633

Abstract

The number of connected devices is increasing worldwide. Not only in contexts like the Smart City, but also in rural areas, to provide advanced features like smart farming or smart logistics. Thus, wireless network technologies to efficiently allocate Internet of Things (IoT) and [...] Read more.

The number of connected devices is increasing worldwide. Not only in contexts like the Smart City, but also in rural areas, to provide advanced features like smart farming or smart logistics. Thus, wireless network technologies to efficiently allocate Internet of Things (IoT) and Machine to Machine (M2M) communications are necessary. Traditional cellular networks like Global System for Mobile communications (GSM) are widely used worldwide for IoT environments. Nevertheless, Low Power Wide Area Networks (LP-WAN) are becoming widespread as infrastructure for present and future IoT and M2M applications. Based also on a subscription service, the LP-WAN technology SIGFOX^TM may compete with cellular networks in the M2M and IoT communications market, for instance in those projects where deploying the whole communications infrastructure is too complex or expensive. For decision makers to decide the most suitable technology for each specific application, signal coverage is within the key features. Unfortunately, besides simulated coverage maps, decision-makers do not have real coverage maps for SIGFOX^TM, as they can be found for cellular networks. Thereby, we propose Internet of THings Area Coverage Analyzer (ITHACA), a signal analyzer prototype to provide automated signal coverage maps and analytics for LP-WAN. Experiments performed in the Gran Canaria Island, Spain (with both urban and complex topographic rural environments), returned a real SIGFOX^TM service availability above 97% and above 11% more coverage with respect to the company-provided simulated maps. We expect that ITHACA may help decision makers to deploy the most suitable technologies for future IoT and M2M projects. Full article

(This article belongs to the Special Issue Applications of Internet of Things)

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20 pages, 314 KiB

Open AccessArticle

The Interval Cognitive Network Process for Multi-Attribute Decision-Making

by Xiuli Qi, Chengxiang Yin^*

, Kai Cheng and Xianglin Liao

Department of Simulation and Data Engineering in the College of Command Information System, PLA Army Engineering University, Nanjing 210007, China

Symmetry 2017, 9(10), 238; https://doi.org/10.3390/sym9100238 - 19 Oct 2017

Cited by 2 | Viewed by 3584

Abstract

Aiming at combining the good characteristics of a differential scale in representing human cognition and the favorable properties of interval judgments in expressing decision-makers’ uncertainty, this paper proposes the interval cognitive network process (I-CNP) to extend the primitive cognition network process (P-CNP) to [...] Read more.

Aiming at combining the good characteristics of a differential scale in representing human cognition and the favorable properties of interval judgments in expressing decision-makers’ uncertainty, this paper proposes the interval cognitive network process (I-CNP) to extend the primitive cognition network process (P-CNP) to handle interval judgments. The key points of I-CNP include a consistency definition for an interval pairwise opposite matrix (IPOM) and a method to derive interval utilities from an IPOM. This paper defines a feasible region-based consistency definition and a transitivity based consistency definition for an IPOM. Both of the two definitions are equivalent to the consistency definition for a crisp pairwise opposite matrix (POM) when an IPOM is reduced to a POM. Two methods that are able to derive interval utilities from both consistent and inconsistent IPOMs are developed based on the two definitions. Four numerical examples are used to illustrate the proposed methods and to compare I-CNP to interval analytic hierarchy process (IAHP). The results show that I-CNP reflects the decision-makers’ cognition better, and that the suggestions provided by I-CNP are more convincing. I-CNP provides new useful alternative tools for multi-attribute decision-making problems. Full article

19 pages, 7017 KiB

Open AccessArticle

Fuzzy Logic-Based Model That Incorporates Personality Traits for Heterogeneous Pedestrians

by Zhuxin Xue^1,2

, Qing Dong¹, Xiangtao Fan^1,3,*, Qingwen Jin^1,2, Hongdeng Jian¹ and Jian Liu^1,3

¹ Key Laboratory of Digital Earth Science, Institute of Remote Sensing and Digital Earth, Chinese Academy of Sciences, Beijing 100094, China

² University of Chinese Academy of Sciences, Beijing 100049, China

³ Hainan Key Laboratory of Earth Observation, Sanya 572029, China

Symmetry 2017, 9(10), 239; https://doi.org/10.3390/sym9100239 - 20 Oct 2017

Cited by 16 | Viewed by 8020

Abstract

Most models designed to simulate pedestrian dynamical behavior are based on the assumption that human decision-making can be described using precise values. This study proposes a new pedestrian model that incorporates fuzzy logic theory into a multi-agent system to address cognitive behavior that [...] Read more.

Most models designed to simulate pedestrian dynamical behavior are based on the assumption that human decision-making can be described using precise values. This study proposes a new pedestrian model that incorporates fuzzy logic theory into a multi-agent system to address cognitive behavior that introduces uncertainty and imprecision during decision-making. We present a concept of decision preferences to represent the intrinsic control factors of decision-making. To realize the different decision preferences of heterogeneous pedestrians, the Five-Factor (OCEAN) personality model is introduced to model the psychological characteristics of individuals. Then, a fuzzy logic-based approach is adopted for mapping the relationships between the personality traits and the decision preferences. Finally, we have developed an application using our model to simulate pedestrian dynamical behavior in several normal or non-panic scenarios, including a single-exit room, a hallway with obstacles, and a narrowing passage. The effectiveness of the proposed model is validated with a user study. The results show that the proposed model can generate more reasonable and heterogeneous behavior in the simulation and indicate that individual personality has a noticeable effect on pedestrian dynamical behavior. Full article

(This article belongs to the Special Issue Fuzzy Techniques for Decision Making)

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27 pages, 14832 KiB

Open AccessArticle

On Elastic Symmetry Identification for Polycrystalline Materials

by Peter V. Trusov and Kirill V. Ostapovich^*

Department of Mathematical Modelling of Systems and Processes, Perm National Research Polytechnic University, Perm 614990, Russia

Symmetry 2017, 9(10), 240; https://doi.org/10.3390/sym9100240 - 20 Oct 2017

Cited by 4 | Viewed by 4423

Abstract

The products made by the forming of polycrystalline metals and alloys, which are in high demand in modern industries, have pronounced inhomogeneous distribution of grain orientations. The presence of specific orientation modes in such materials, i.e., crystallographic texture, is responsible for anisotropy of [...] Read more.

The products made by the forming of polycrystalline metals and alloys, which are in high demand in modern industries, have pronounced inhomogeneous distribution of grain orientations. The presence of specific orientation modes in such materials, i.e., crystallographic texture, is responsible for anisotropy of their physical and mechanical properties, e.g., elasticity. A type of anisotropy is usually unknown a priori, and possible ways of its determination is of considerable interest both from theoretical and practical viewpoints. In this work, emphasis is placed on the identification of elasticity classes of polycrystalline materials. By the newly introduced concept of “elasticity class” the union of congruent tensor subspaces of a special form is understood. In particular, it makes it possible to consider the so-called symmetry classification, which is widely spread in solid mechanics. The problem of identification of linear elasticity class for anisotropic material with elastic moduli given in an arbitrary orthonormal basis is formulated. To solve this problem, a general procedure based on constructing the hierarchy of approximations of elasticity tensor in different classes is formulated. This approach is then applied to analyze changes in the elastic symmetry of a representative volume element of polycrystalline copper during numerical experiments on severe plastic deformation. The microstructure evolution is described using a two-level crystal elasto-visco-plasticity model. The well-defined structures, which are indicative of the existence of essentially inhomogeneous distribution of crystallite orientations, were obtained in each experiment. However, the texture obtained in the quasi-axial upsetting experiment demonstrates the absence of significant macroscopic elastic anisotropy. Using the identification framework, it has been shown that the elasticity tensor corresponding to the resultant microstructure proves to be almost isotropic. Full article

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29 pages, 3479 KiB

Open AccessArticle

Multi-Objective Optimization Algorithm Based on Sperm Fertilization Procedure (MOSFP)

by Hisham A. Shehadeh

, Mohd Yamani Idna Ldris^* and Ismail Ahmedy

Department of Computer System and Technology, Faculty of Computer Science and Information Technology, University of Malaya, Kuala Lumpur 50603, Malaysia

Symmetry 2017, 9(10), 241; https://doi.org/10.3390/sym9100241 - 20 Oct 2017

Cited by 22 | Viewed by 7102

Abstract

In this paper, we propose an extended multi-objective version of single objective optimization algorithm called sperm swarm optimization algorithm. The proposed multi-objective optimization algorithm based on sperm fertilization procedure (MOSFP) operates based on Pareto dominance and a crowding factor, that crowd and filter [...] Read more.

In this paper, we propose an extended multi-objective version of single objective optimization algorithm called sperm swarm optimization algorithm. The proposed multi-objective optimization algorithm based on sperm fertilization procedure (MOSFP) operates based on Pareto dominance and a crowding factor, that crowd and filter out the list of the best sperms (global best values). We divide the sperm swarm into three equal parts, after that, different types of turbulence (mutation) operators are applied on these parts, such as uniform mutation, non-uniform mutation, and without any mutation. Our algorithm is compared against three well-known algorithms in the field of optimization. These algorithms are NSGA-II, SPEA2, and OMOPSO. These algorithms are compared using a very popular benchmark function suites called Zitzler-Deb-Thiele (ZDT) and Walking-Fish-Group (WFG). We also adopt three quality metrics to compare the convergence, accuracy, and diversity of these algorithms, including, inverted generational distance (IGD), spread (SP), and epsilon (∈). The experimental results show that the performance of the proposed MOSFP is highly competitive, which outperformed OMOPSO in solving problems such as ZDT3, WFG5, and WFG8. In addition, the proposed MOSFP outperformed both of NSGA-II or SPEA2 algorithms in solving all the problems. Full article

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17 pages, 302 KiB

Open AccessArticle

Lattice-Based Revocable Certificateless Signature

by Ying-Hao Hung, Yuh-Min Tseng^* and Sen-Shan Huang

Department of Mathematics, National Changhua University of Education, Jin-De Campus, Chang-Hua 500, Taiwan

Symmetry 2017, 9(10), 242; https://doi.org/10.3390/sym9100242 - 20 Oct 2017

Cited by 14 | Viewed by 3940

Abstract

Certificateless signatures (CLS) are noticeable because they may resolve the key escrow problem in ID-based signatures and break away the management problem regarding certificate in conventional signatures. However, the security of the mostly previous CLS schemes relies on the difficulty of solving discrete [...] Read more.

Certificateless signatures (CLS) are noticeable because they may resolve the key escrow problem in ID-based signatures and break away the management problem regarding certificate in conventional signatures. However, the security of the mostly previous CLS schemes relies on the difficulty of solving discrete logarithm or large integer factorization problems. These two problems would be solved by quantum computers in the future so that the signature schemes based on them will also become insecure. For post-quantum cryptography, lattice-based cryptography is significant due to its efficiency and security. However, no study on addressing the revocation problem in the existing lattice-based CLS schemes is presented. In this paper, we focus on the revocation issue and present the first revocable CLS (RCLS) scheme over lattices. Based on the short integer solution (SIS) assumption over lattices, the proposed lattice-based RCLS scheme is shown to be existential unforgeability against adaptive chosen message attacks. By performance analysis and comparisons, the proposed lattice-based RCLS scheme is better than the previously proposed lattice-based CLS scheme, in terms of private key size, signature length and the revocation mechanism. Full article

15 pages, 1308 KiB

Open AccessArticle

Factors Affecting the Perception of 3D Facial Symmetry from 2D Projections

by Michael B. Lewis

School of Psychology, Cardiff University, Cardiff CF10 3AT, UK

Symmetry 2017, 9(10), 243; https://doi.org/10.3390/sym9100243 - 21 Oct 2017

Cited by 5 | Viewed by 8322

Abstract

Facial symmetry is believed to have an evolutionary significance and so its detection should be robust in natural settings. Previous studies of facial symmetry detection have used front views of faces where the decision could be made on 2D image properties rather than [...] Read more.

Facial symmetry is believed to have an evolutionary significance and so its detection should be robust in natural settings. Previous studies of facial symmetry detection have used front views of faces where the decision could be made on 2D image properties rather than 3D facial properties. These studies also employed comparative judgements, which could be influenced by attractiveness rather than symmetry. Two experiments explored the ability to detect typical levels of 3D facial asymmetry (contrasted with wholly symmetrical faces) from 2D projections of faces. Experiment 1 showed that asymmetry detection was impaired by inversion but even more impaired by 90 degrees rotation demonstrating the importance of the vertical reflection. Asymmetry detection was also reduced by yaw rotation of the head but still above-chance at 30 degrees rotation. Experiment 2 explored the effect of asymmetrical lighting and yaw rotation up to 45 degrees. Detection of asymmetry was affected by asymmetrical lighting and yaw rotation in a non-additive manner. The results are discussed in terms of the special role that faces and vertical symmetry play in visual perception. Full article

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17 pages, 3246 KiB

Open AccessArticle

Self-Adaptive Pre-Processing Methodology for Big Data Stream Mining in Internet of Things Environmental Sensor Monitoring

by Kun Lan¹, Simon Fong^1,*, Wei Song²

, Athanasios V. Vasilakos³ and Richard C. Millham⁴

¹ Department of Computer and Information Science, University of Macau, Taipa 999078, Macau

² School of Computer Science, North China University of Technology, Beijing 100144, China

³ Department of Computer Science, Electrical and Space Engineering, Lulea University of Technology, SE-97187 Lulea, Sweden

⁴ Department of Information Technology, Durban University of Technology, Ritson Campus, Durban P.O. BOX 1334, South Africa

Symmetry 2017, 9(10), 244; https://doi.org/10.3390/sym9100244 - 21 Oct 2017

Cited by 17 | Viewed by 6700

Abstract

Over the years, advanced IT technologies have facilitated the emergence of new ways of generating and gathering data rapidly, continuously, and largely and are associated with a new research and application branch, namely, data stream mining (DSM). Among those multiple scenarios of DSM, [...] Read more.

Over the years, advanced IT technologies have facilitated the emergence of new ways of generating and gathering data rapidly, continuously, and largely and are associated with a new research and application branch, namely, data stream mining (DSM). Among those multiple scenarios of DSM, the Internet of Things (IoT) plays a significant role, with a typical meaning of a tough and challenging computational case of big data. In this paper, we describe a self-adaptive approach to the pre-processing step of data stream classification. The proposed algorithm allows different divisions with both variable numbers and lengths of sub-windows under a whole sliding window on an input stream, and clustering-based particle swarm optimization (CPSO) is adopted as the main metaheuristic search method to guarantee that its stream segmentations are effective and adaptive to itself. In order to create a more abundant search space, statistical feature extraction (SFX) is applied after variable partitions of the entire sliding window. We validate and test the effort of our algorithm with other temporal methods according to several IoT environmental sensor monitoring datasets. The experiments yield encouraging outcomes, supporting the reality that picking significant appropriate variant sub-window segmentations heuristically with an incorporated clustering technique merit would allow these to perform better than others. Full article

(This article belongs to the Special Issue Emerging Approaches and Advances in Big Data)

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14 pages, 3600 KiB

Open AccessFeature PaperArticle

Using Comparisons of Clock Frequencies and Sidereal Variation to Probe Lorentz Violation

by Charles D. Lane^1,2

¹ Department of Physics, Berry College, Mount Berry, GA 30149, USA

² IU Center for Spacetime Symmetries, Indiana University, Bloomington, IN 47405, USA

Symmetry 2017, 9(10), 245; https://doi.org/10.3390/sym9100245 - 23 Oct 2017

Cited by 4 | Viewed by 3718

Abstract

This paper discusses clock-comparison experiments, which may be used to test Lorentz symmetry to an extremely high level of precision. We include a brief overview of theoretical predictions for signals of Lorentz violation in clock-comparison experiments and summarize results of experiments that have [...] Read more.

This paper discusses clock-comparison experiments, which may be used to test Lorentz symmetry to an extremely high level of precision. We include a brief overview of theoretical predictions for signals of Lorentz violation in clock-comparison experiments and summarize results of experiments that have been performed to date. Full article

(This article belongs to the Special Issue Violation of Lorentz Symmetry)

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