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Volume 16 Issue 1

January 2018

Issue of Open Physics

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Contents
Journal Overview

Centrality is widely used to measure which nodes are important in a network. In recent decades, numerous metrics have been proposed with varying computation complexity. To test the idea that approximating a high-complexity metric by a low-complexity metric, researchers have studied the correlation between them. However, these works are based on Pearson correlation which is sensitive to the data distribution. Intuitively, a centrality metric is a ranking of nodes (or edges). It would be more reasonable to use rank correlation to do the measurement. In this paper, we use degree, a low-complexity metric, as the base to approximate three other metrics: closeness, betweenness, and eigenvector. We first demonstrate that rank correlation performs better than the Pearson one in scale-free networks. Then we study the correlation between centrality metrics in real networks, and find that the betweenness occupies the highest coefficient, closeness is at the middle level, and eigenvector fluctuates dramatically. At last, we evaluate the performance of using top degree nodes to approximate three other metrics in the real networks. We find that the intersection ratio of betweenness is the highest, and closeness and eigenvector follows; most often, the largest degree nodes could approximate largest betweenness and closeness nodes, but not the largest eigenvector nodes.

The aim of this paper is the multi-physical modeling of synchronous permanent magnet machines, dedicated to hybrid electrical vehicles application, using reluctance network lumped mechanical and thermal models. The modeling approaches are presented and validated by comparing the obtained results to those of finite element method with a close look to the airgap modeling and the consideration of soft magnetic materials non-linearity in the electromagnetic modeling. As well as a close look also on the conduction and convection heat coefficients for the machine different regions in the thermal modeling. Finally a focus on the mass, damping and stiffness matrix computation in lumped mechanical modeling taking into account the temperature influence on the materials mechanical properties. In addition a simplified rotating electrical machine is described and multiple coupled analysis were done in order to derive the structure magneto-vibroacoustic performances.

Aiming at the low recognition rate, low recognition efficiency, poor anti-interference and high missing detection rate of current traffic sign recognition methods, a fast recognition algorithm based on SURF for static traffic sign information of highway is proposed. The expansion of the digital morphological method is used to connect the cracks in the traffic sign. Traffic sign images are corroded according to the corrosion, and the connected areas are contracted or refined. Regions of interest are detected by region filling. According to the result of traffic sign image processing, the scale of traffic sign image is normalized by bilinear interpolation method, and the SURF feature points of traffic sign image are extracted. The FLANN algorithm is used to realize feature point matching, and the threshold is set to determine the best matching point. The matching result is output and the traffic sign information is recognized. Experimental results show that the algorithm has high recognition rate and recognition efficiency, strong anti-interference, and can control the rate of missing detection in a certain range.

Latent heat storage represents a promising technique to achieve net zero energy buildings. This work investigates the behaviour of phase change material (PCM) inside a rectangular enclosure, which represents the geometry of a latent heat storage system. The left side of the unit is exposed to a constant temperature ( T h ), while the other three walls are exposed to convection heat transfer boundary condition [ h = 5, 10, and 15 W/(m 2 K)] and different ambient temperatures ( T ∞ = 297 ◦ and 307 ◦ K). The ambient temperatures were selected to be at/above the melting temperature of the studied PCM (coconut oil). To study the melting process of the PCM, the continuity, Navier-Stokes and energy equation were used. The Navier-Stokes equations were modified using the Carman-Kozeny relation. The finite element method was utilized to produce numerical results. The results are presented in terms of flow and thermal fields, Nusselt number ( Nu ), and the melt fraction ( MF ) of the PCM. The results show that, when T ∞ = T m , the melting rate of the PCM slows down with increasing the convection heat transfer coefficient. While the melting rate accelerates with increasing the convection heat transfer coefficient when T ∞ > T m .

About this journal

Open Physics (PHYS) is a peer-reviewed, open access, electronic journal devoted to the publication of fundamental research results in all fields of physics. The journal provides the readers with free, instant, and permanent access to all content worldwide; and the authors with extensive promotion of published articles, long-time preservation, no space constraints and immediate publication.

Aims and Scope

The journal publishes research and review articles, rapid and short communications, comments and replies that cover the following areas of physical sciences:

Acoustics

Astrophysics,

Atomic and Molecular Physics,

Biological and Medical Physics,

Complex Networks, Socio- and Econophysics,

Computational Physics,

Condensed Matter Physics,

Cosmology and Gravitation,

Fluid Mechanics,

Geophysics,

Nanophysics,

Optics and Lasers,

Particle and Nuclear Physics,

Plasma Physics,

Statistical and Nonlinear Physics,

Surface Physics,

Theoretical and Mathematical Physics.

Volume 16 Issue 1

Issue of Open Physics

A modified Fermi-Walker derivative for inextensible flows of binormal spherical image

Abstract

Algebraic aspects of evolution partial differential equation arising in the study of constant elasticity of variance model from financial mathematics

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Three-dimensional atom localization via probe absorption in a cascade four-level atomic system

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Determination of the energy transitions and half-lives of Rubidium nuclei

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Three phase heat and mass transfer model for unsaturated soil freezing process: Part 1 - model development

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Three phase heat and mass transfer model for unsaturated soil freezing process: Part 2 - model validation

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Mathematical model for thermal and entropy analysis of thermal solar collectors by using Maxwell nanofluids with slip conditions, thermal radiation and variable thermal conductivity

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Constructing analytic solutions on the Tricomi equation

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Feynman diagrams and rooted maps

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New type of chaos synchronization in discrete-time systems: the F-M synchronization

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Unsteady flow of fractional Oldroyd-B fluids through rotating annulus

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A note on the uniqueness of 2D elastostatic problems formulated by different types of potential functions

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On the conservation laws and solutions of a (2+1) dimensional KdV-mKdV equation of mathematical physics

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Computational methods and traveling wave solutions for the fourth-order nonlinear Ablowitz-Kaup-Newell-Segur water wave dynamical equation via two methods and its applications

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Siewert solutions of transcendental equations, generalized Lambert functions and physical applications

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Numerical solution of mixed convection flow of an MHD Jeffery fluid over an exponentially stretching sheet in the presence of thermal radiation and chemical reaction

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A new three-dimensional chaotic flow with one stable equilibrium: dynamical properties and complexity analysis

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Dynamics of a dry-rebounding drop: observations, simulations, and modeling

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Modeling the initial mechanical response and yielding behavior of gelled crude oil

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Lie symmetry analysis and conservation laws for the time fractional simplified modified Kawahara equation

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Solitary wave solutions of two KdV-type equations

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Applying industrial tomography to control and optimization flow systems

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Reconstructing time series into a complex network to assess the evolution dynamics of the correlations among energy prices

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An optimal solution for software testing case generation based on particle swarm optimization

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Optimal system, nonlinear self-adjointness and conservation laws for generalized shallow water wave equation

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Alternative methods for solving nonlinear two-point boundary value problems

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Global model simulation of OH production in pulsed-DC atmospheric pressure helium-air plasma jets

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Experimental investigation on optical vortex tweezers for microbubble trapping

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Joint measurements of optical parameters by irradiance scintillation and angle-of-arrival fluctuations

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M-polynomials and topological indices of hex-derived networks

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Generalized convergence analysis of the fractional order systems

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Porous flow characteristics of solution-gas drive in tight oil reservoirs

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Complementary wave solutions for the long-short wave resonance model via the extended trial equation method and the generalized Kudryashov method

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A Note on Koide’s Doubly Special Parametrization of Quark Masses

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On right-angled spherical Artin monoid of type Dn

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Gas flow regimes judgement in nanoporous media by digital core analysis

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4 + n-dimensional water and waves on four and eleven-dimensional manifolds

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Stabilization and Analytic Approximate Solutions of an Optimal Control Problem

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On the equations of electrodynamics in a flat or curved spacetime and a possible interaction energy

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On right-angled spherical Artin monoid of type D_n