Image Local Features Description through Polynomial Approximation

This work introduces a novel local patch descriptor that remains invariant under varying conditions of orientation, viewpoint, scale, and illumination. The proposed descriptor incorporate polynomials of various degrees to approximate the local patch within the image. Before feature detection and approximation, the image micro-texture is eliminated through a guided image filter with the potential to preserve the edges of the objects. The rotation invariance is achieved by aligning the local patch around the Harris corner through the dominant orientation shift algorithm. Weighted threshold histogram equalization (WTHE) is employed to make the descriptor in-sensitive to illumination changes. The correlation coefficient is used instead of Euclidean distance to improve the matching accuracy. The proposed descriptor has been extensively evaluated on the Oxford's affine covariant regions dataset, and absolute and transition tilt dataset. The experimental results show that our proposed descriptor can categorize the feature with more distinctiveness in comparison to state-of-the-art descriptors. - 2013 IEEE.This work was supported by the Qatar National Library.Scopu

Malicious UAV detection using integrated audio and visual features for public safety applications

RÉSUMÉ: Unmanned aerial vehicles (UAVs) have become popular in surveillance, security, and remote monitoring. However, they also pose serious security threats to public privacy. The timely detection of a malicious drone is currently an open research issue for security provisioning companies. Recently, the problem has been addressed by a plethora of schemes. However, each plan has a limitation, such as extreme weather conditions and huge dataset requirements. In this paper, we propose a novel framework consisting of the hybrid handcrafted and deep feature to detect and localize malicious drones from their sound and image information. The respective datasets include sounds and occluded images of birds, airplanes, and thunderstorms, with variations in resolution and illumination. Various kernels of the support vector machine (SVM) are applied to classify the features. Experimental results validate the improved performance of the proposed scheme compared to other related methods

Nonlinear modeling and dynamic analysis of bioengineering hyper-elastic tubes based on different material models

In this research, nonlinear vibrations of a hyper-elastic tube accounting for large deflection and moderate rotation have been examined. The hyper-elastic tube is assumed to be surrounded by a nonlinear hardening elastic medium. Different types of hyper-elastic material models are presented and discussed including neo-Hookean, Mooney-Rivlin, Ishihara and Yeoh models. The efficacy of these models in nonlinear vibration modeling and analysis of hyper-elastic tubes has been examined. Modified von-Karman strain is used to consider both large deflection and moderate rotation. The governing equations are obtained based on strain energy function of above-mentioned hyper-elastic material models. The nonlinear governing equation of the tube contains cubic and quantic terms which is solved via extended Hamiltonian method leading to a closed form of nonlinear vibration frequency. The effect of hyper-elastic models and their material parameters on nonlinear vibrational frequency of tubes has been studied. 2019, Springer-Verlag GmbH Germany, part of Springer Nature.Scopu

Analyzing nonlocal nonlinear vibrations of two-phase geometrically imperfect piezo-magnetic beams considering piezoelectric reinforcement scheme

This article deals with analyzing nonlinear free vibrations of nonlocal two-phase piezo-magnetic beam with geometric imperfection rested on viscoelastic substrate. The two-phase piezo-magnetic material is based on a composition of piezoelectric and magnetic constituents with desirable percentages. An assumption is that the nanobeam is rested in an initial position due to geometric imperfection. In addition, the equilibrium equations of nanobeam with piezo-magnetic properties are derived utilizing Hamilton’s principle and the von Kármán geometric nonlinearity. Then, an exact solution based on the Jacobi elliptic functions has been provided to obtain nonlinear vibration frequency. It is found that nonlinear vibration behavior of the nanobeam is dependent on the magnitude of induced electric voltage, magnetic field intensity, geometric imperfection, and viscoelastic substrate parameters.Scopu

Nonlocal strain gradient effects on forced vibrations of porous FG cylindrical nanoshells

The present paper explores forced vibrational properties of porosity-dependent functionally graded (FG) cylindrical nanoshells exposed to linear-type or triangular-type impulse load via classical shell theory (CST) and nonlocal strain gradient theory (NSGT). Employing such scale-dependent theory, two scale factors accounting for stiffness softening and hardening effects are incorporated in modeling of the nanoshell. Two sorts of porosity distributions called even and uneven have been taken into account. Governing equations obtained for porous nanoshell have been solved through inverse Laplace transforms technique to derive dynamical deflections. It is shown that transient responses of a nanoshell are affected by the form and position of impulse loading, amount of porosities, porosities dispensation, nonlocal and strain gradient factors .Scopu

Small scale effects on transient vibrations of porous FG cylindrical nanoshells based on nonlocal strain gradient theory

This research investigates transient vibrational characteristics of a porous functionally graded cylindrical nanoshell under different impulsive loadings with the use of nonlocal strain gradient theory (NSGT). Based on NSGT, two size parameters accounting for stiffness softening and hardening effects are incorporated in modeling of the nanoshell. Impulse forces have three forms of triangular, rectangular and sinusoidal. Two sorts of porosity distributions called even and uneven have been taken into account. Governing equations obtained for porous nanoshell have been solved through inverse Laplace transforms technique to derive dynamical deflections. It is shown that transient responses of a nanoshell are affected by the form and position of impulse loading, amount of porosities, porosities dispensation, nonlocal and strain gradient parameters.\Scopu

Nonlinear dynamic characteristics of nonlocal multi-phase magneto-electro-elastic nano-tubes with different piezoelectric constituents

Analysis of exact nonlinear dynamic behavior of multi-phase magneto-electro-elastic (MEE) nanoshells has been presented in this paper using Jacobi elliptic functions. Multi-phase MEE material is constructed form piezoelectric and piezo-magnetic constituents for which the material properties can be controlled based on the percentages of the constituents. Nonlinear governing equations are established for MEE nanoshell based on nonlocal elasticity theory and an exact solution is provided using Jacobi elliptic function method. This method gives an exact value of vibration frequency in nonlinear regime and overcomes the shortcomings of several approximate solutions applied in the studies on nanostructures. It will be shown that nonlinear vibration behavior of MEE nanoshell in electro-magnetic field depends on the constituent's percentages. Influences of nonlocal scale factor, piezoelectric reinforcement, magnetic field intensity, and electrical voltage on vibration frequencies of the nanoshell are also investigated. 2020, Springer-Verlag GmbH Germany, part of Springer Nature.Scopu