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World Journal of Mechanics 2014年第11期4卷 309-314页

作者： Narahari V. Joshi Department of Physics University of Los Andes Merida Venezuela

The origin for one of the fundamental laws of electromagnetism, namely faraday’s law is explained for the first time on the basis of the presence of strings in the form of a compact liquid. The rate of change of the magnetic field produces a pressure gradient in the medium giving rise to the fluid flow. According to fluid dynamics, the stress and the gradient of strain are originated in the space which creates vibrations in the system and is related with the electric field. The details of the mechanism which produces a circular motion of the electric field, XE, are also addressed.

关键词： faraday’s Law Fluid Dynamics Magnetic Field

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Induced Electromagnetic Fields Estimation in spine Examinations of MRI Patients: A Re-Evaluation of Existing Clinical Protocols at a Hospital in Accra, Ghana

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Journal of Applied Mathematics and Physics 2018年第5期6卷 1065-1075页

作者： Frempong Acheampong Theresa Dery Rita Appiah Daniel A. Abaye Graduate school of Nuclear and Allied sciences University of Ghana Legon Accra Ghana school of Basic and Biomedical sciences University of Health and Allied Sciences Ho Ghana Radiological & Medical sciences Research Institute Ghana Atomic Energy Commission Legon Accra Ghana Ghana Research Rector 1 Center Ghana Atomic Energy Commission Legon Accra Ghana

Patients undergoing Magnetic Resonance Imaging (MRI) are exposed to strong, non-uniform static magnetic fields outside of the central imaging region, in which the movement of the body may induce electric currents in tissues which could possibly be harmful. The purpose of this study was to re-evaluate existing clinical protocols by determining the induced electromagnetic (EM) fields in MRI spine examinations. The study covered 120 MRI spine examinations at the MRI Unit of a hospital in Accra, Ghana. A numerical model based on faraday’s equation was developed using the finite difference method (FDM) and MATLAB software to compute, first, a test simulation of induced EM field intensities and then actual measurements of induced fields on the spine. The simulation results were peak induced electric field, 0.39 V/m and current density, 0.039 A/m2. Patient results were;calculated maximum velocity, 0.29 m/s;peak induced electric field strength, 0.44 V/m, and current density, 0.043 A/m2. The levels of induced EM-fields were such that they would not pose any potential health hazards to the patients as these values were well below the recommended guidance levels set by the Directive IEC 60601-2-33 of the European Parliament.

关键词： MRI spine Examinations Finite Difference Method faraday’s Equation

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Electromagnetic self-Force Mechanisms and Origin of <i>R</i><sup>-1</sup>Term

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Journal of Applied Mathematics and Physics 2017年第5期5卷 1099-1105页

作者： saeed Fathi Hamed Razavi University of Tehran Tehran Iran Islamic Azad University Science and Research Branch Tehran Iran

An accelerating charged particle exerts a force upon itself. If we model the particle as a spherical shell of radius R, and calculate the force of one piece of this shell on another and eventually integrate over the whole particle, there will be a net force on the particle due to the breakdown of Newton’s third law. This symmetry breaking mechanism relies on the finite size of the particle;thus, as Feynman has stated, conceptually this mechanism doesn’t make good sense for point particles. Nonetheless, in the point particle limit, two terms survive in the self-force series: R0 and R-1 terms. The R0 term can alternatively be attributed to the well-known radiation reaction but the origin of R-1 term is not clear. In this study, we will show that this new term can be accounted for by an inductive mechanism in which the changing magnetic field induces an inductive force on the particle. Using this inductive mechanism, we derive R-1 term in an extremely easy way.

关键词： Electromagnetic self-Force self-Force Mechanisms Radiation Reaction faraday’s Law of Induction

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