A text-independent Persian writer identification based on feature relation graph (FRG)

The style of people's handwriting is a biometric feature that is used in person authentication. In this paper, we have proposed a text independent method for Persian writer identification. In the proposed method, pattern based features are extracted from data using Gabor and XGabor filter. The extracted features are represented for each person by using a graph that is called FRG (feature relation graph). This graph is constructed using relations between extracted features by employing a fuzzy method. The fuzzy method determines the similarity between features extracted from different handwritten instances of each person. In the identification phase, a graph similarity approach is employed to determine the similarity of the FRG generated from the test data and the FRGs generated by training data. The experimental results were satisfactory and the proposed method got about 100% accuracy on a dataset with 100 writers when enough training data was used. However, this method has been applied on Persian handwritings but we believe it can be extended on other languages especially in data representation and classification parts.     

Solid-state supercapacitor based on breath figured polymethyl methacrylate deposited by graphene: the effect of electrode surface

Solid-state supercapacitors are fabricated using transparent polymethyl methacrylate (PMMA) films decorated by breath figures BF, as an electrode and polyvinyl alcohol (PVA)-H₂SO₄ as an electrolyte. The holes on the surface of the transparent PMMA created by BF method have diameters of 0.5–10 μm. Graphene is deposited by spray coating using a dispersion mixture of graphene layers. The fabricated electrodes were characterized by cyclic voltammetry (CV), galvanostatic charge–discharge, electrochemical impedance spectroscopy, charge stability and life time for evaluating their supercapacitance performance. From CV data at 5 mV/s scan rate, high specific capacitance equal to 344 for BFPMMA/G F/g and, 45 F/g for PMMA/G has been measured. By the same way, energy densities have been measured as 430 and 56.25 Wh/kg for the mentioned electrodes, respectively.     

Thermal buckling behavior of two-dimensional imperfect functionally graded microscale-tapered porous beam

This article presents a study on the thermal buckling behavior of two-dimensional functionally graded microbeams made of porous materials. The material composition varies along thickness and length of the microbeam based on the power law distribution. The microbeam is modeled within the framework of Euler–Bernoulli beam theory. The microbeam is considered having variable material composition along thickness. The equations are derived using the modified couple stress theory and the solving process is based on the generalized differential quadrature method. The validity of the results is shown through comparison of the results with the results of other published research.     

Modeling and numerical simulation of solar chimney power plants

The solar chimney power plant is a simple solar thermal power plant that is capable of converting solar energy into thermal energy in the solar collector. In the second stage, the generated thermal energy is converted into kinetic energy in the chimney and ultimately into electric energy using a combination of a wind turbine and a generator. The purpose of this study is to conduct a more detailed numerical analysis of a solar chimney power plant. A mathematical model based on the Navier-Stokes, continuity and energy equations was developed to describe the solar chimney power plant mechanism in detail. Two different numerical simulations were performed for the geometry of the prototype in Manzanares, Spain. First, the governing equations were solved numerically using an iterative technique. Then, the numerical simulation was performed using the CFD software FLUENT that can simulate a two-dimensional axisymmetric model of a solar chimney power plant with the standard k-epsilon turbulence model. Both the predictions were compared with the available experimental data to assess the validity of the model. The temperature, velocity and pressure distributions in the solar collector are illustrated for three different solar radiations. Reasonably good quantitative agreement was obtained between the experimental data of the Manzanares prototype and both the numerical results.     

Linear Optical Response of Silicon Nanotubes Under Axial Magnetic Field

We investigated the optical properties of silicon nanotubes (SiNTs) in the low energy region, E < 0.5 eV, and middle energy region, 1.8 eV < E < 2 eV. The dependence of optical matrix elements and linear susceptibility on radius and magnetic field, in terms of one-dimensional (1-d) wavevector and subband index, is calculated using the tight-binding approximation. It is found that, on increasing the nanotube diameter, the low-energy peaks show red-shift and their intensities are decreased. Also, we found that in the middle energy region all tubes have two distinct peaks, where the energy position of the second peak is approximately constant and independent of the nanotube diameter. Comparing the band structure of these tubes in different magnetic fields, several differences are clearly seen, such as splitting of degenerate bands, creation of additional band-edge states, and bandgap modification. It is found that applying the magnetic field leads to a phase transition in zigzag silicon hexagonal nanotubes (Si h-NTs), unlike in zigzag silicon gear-like nanotubes (Si g-NTs), which remain semiconducting in any magnetic field. We found that the axial magnetic field has two effects on the linear susceptibility spectrum, namely broadening and splitting. The axial magnetic field leads to the creation of a peak with energy less than 0.2 eV in metallic Si h-NTs, whereas in the absence of a magnetic field such a transition is not allowed.