Open Access Original Research Article

On the Significance of the Fields’ Energy-Momentum Tensor

E. Comay

Physical Science International Journal, Page 1-9
DOI: 10.9734/psij/2019/v21i430114

This work discusses the significance of the energy-momentum tensor of physical fields of an elementary particle. The Noether theorem shows how this tensor can be derived from the Lagrangian density of a given field. This work proves that the energy-momentum tensor can also be used for a consistency test of a field theory. The results show that the Dirac Lagrangian density of a spin-1/2 massive particle yields consistent results. On the other hand, problems exist with the present structure of quantum electrodynamics, and with quantum fields of massive particles that are described by a second order differential equation. All problematic results are confirmed by an independent analysis.

Open Access Original Research Article

A First Approach to Loop Quantum Gravity in the Momentum Representation

W. F. Chagas-Filho

Physical Science International Journal, Page 1-8
DOI: 10.9734/psij/2019/v21i430115

We present a generalization of the first-order formalism used to describe the dynamics of a classical system. The generalization is then applied to the first-order action that describes General Relativity. As a result we obtain equations that can be interpreted as describing quantum gravity in the momentum representation.

Open Access Original Research Article

Kink Type Traveling Wave Solutions of Right-handed Non-commutative Burgers Equations via Extended (G'/G) -Expansion Method

Harun-Or-Roshid .

Physical Science International Journal, Page 1-6
DOI: 10.9734/psij/2019/v21i430117

The extended (G'/G)-expansion method is significant for finding the exact traveling wave solutions of nonlinear evolution equations (NLEEs) in mathematical physics. In this paper, we enhanced new traveling wave solutions of right-handed non-commutative burgers equations via extended -expansion. Implementation of the method for searching exact solutions of the equation provided many new solutions which can be used to employ some practically physical and mechanical phenomena. Moreover, when the parameters are replaced by special values, the well-known solitary wave solutions of the equation rediscovered from the traveling wave solutions and included free parameters may imply some physical meaningful results in fluid mechanics, gas dynamics, and traffic flow.

Open Access Original Research Article

Nonlinear Finite Element Modelling for Reinforced Concrete Beams Retrofitted with FRP in Bending

Ihab Samir Abdou Ibrahim Mattar

Physical Science International Journal, Page 1-20
DOI: 10.9734/psij/2019/v21i430118

For the purpose of simulating the behaviour of reinforced concrete (R.C)[1] beams retrofitted with fibre-reinforced polymers/plastics (FRP)[2] in bending, a finite element (FE)[3] modelling procedure has been developed throughout this paper. The FE software package ABAQUS CAE 6.11-3 was used. The data required for such modelling process are boundary conditions, geometric and material properties. Non-available material properties are obtained through experimentally verified numerical material models. FRP isotropic and orthotropic material models are compared; both models nearly yielded similar results. Also, perfect bond model and cohesive zone model for the interface between concrete and FRP have been compared. Unlike the perfect bond model, the cohesive zone model captured the debonding. The modelling procedure was validated through its application to R.C beams retrofitted with FRP in bending. The FE model results were compared to experimental results where both results were highly correlated. Such results include load-deflection curves and cracking pattern. The effect of sheet width and number of FRP layers is emphasized through performing a parametric study. Increasing sheet width is only effective at longer sheet lengths regarding increasing both; stiffness and load carrying capacity. Upon increasing the number of FRP layers, only shifting of the yielding point of reinforcement was noticed.

Open Access Review Article

Chemical Speciation and Fractionation Study of Heavy Metals in Top Sediment Deposit of Owena River, Nigeria

Kolawole Rasheed, Akinnawo Solomon, Ademola Aiyesanmi

Physical Science International Journal, Page 1-13
DOI: 10.9734/psij/2019/v21i430113

This study investigates the chemical speciation and fractionation of heavy metals (Cd, Cr, Cu, Ni and Pb) in relation to their levels of pollution from six different locations along the course of Owena River during the dry and wet season of 2015. The top sediment deposit was subjected to sequential extraction and the heavy metals were identified and quantified using atomic absorption spectrophotometer. The concentration of the analyzed heavy metals in the top sediment deposit were found to occur below the maximum permissible limit of the Dutch reference standard for soil/sediment, thereby the sediment collected from Owena river is not contaminated with the analyzed heavy metals. The overall results of this research suggest that the mobility and bioavailability of heavy metals in sediment collected from Owena River decreases in the following order:  Cu > Pb > Cr > Cd > Ni.