Electromagnetic Physics Research Articles

Homophily and missing links in citation networks.

Citation networks have been widely used to study the evolution of science through the lenses of the underlying patterns of knowledge flows among academic papers, authors, research sub-fields, and scientific journals. Here we focus on citation networks to cast light on the salience of homophily, namely the principle that similarity breeds connection, for knowledge transfer between papers. To this end, we assess the degree to which citations tend to occur between papers that are concerned with seemingly related topics or research problems. Drawing on a large data set of articles published in the journals of the American Physical Society between 1893 and 2009, we propose a novel method for measuring the similarity between articles through the statistical validation of the overlap between their bibliographies. Results suggest that the probability of a citation made by one article to another is indeed an increasing function of the similarity between the two articles. Our study also enables us to uncover missing citations between pairs of highly related articles, and may thus help identify barriers to effective knowledge flows. By quantifying the proportion of missing citations, we conduct a comparative assessment of distinct journals and research sub-fields in terms of their ability to facilitate or impede the dissemination of knowledge. Findings indicate that Electromagnetism and Interdisciplinary Physics are the two sub-fields in physics with the smallest percentage of missing citations. Moreover, knowledge transfer seems to be more effectively facilitated by journals of wide visibility, such as Physical Review Letters, than by lower-impact ones. Our study has important implications for authors, editors and reviewers of scientific journals, as well as public preprint repositories, as it provides a procedure for recommending relevant yet missing references and properly integrating bibliographies of papers.

The Theory of Essence. [Part] 2. An Electromagnetic-Quantum Mechanical Model of Interactionism

Article discussing the theory of essence, based on the physics of electromagnetism and quantum mechanics, which solves the problem of interaction resulting from Descartes's dualistic conception of human nature. The theory is empirically based in phenomena consistently reported by near-death experiencers.

Prácticas pedagógicas e índices de creatividad en la enseñabilidad de la física electromagnética

The purpose of the research was to analyze pedagogical practices of teachers and the creativity of students of electromagnetic physics at the Universidad Francisco de Paula Santander. The research follows a quantitative, descriptive approach. The sample of the study was composed of 10 teachers who guided and two groups of 42 students who enrolled in the subject Electromagnetic Physics in the second half of 2015 and first of 2106 in the Faculty of Engineering. Results: each teacher implements different approach and didactic strategies in their pedagogical practice, with a creativity index of 0.9 where teacher motivation factor to orient their class is associated with the academic performance of the student. Creativity index evaluated according to the MIDE indexes in engineering students is between 0.7 and 1. Conclusion: Analysis Capacity index is the most representative indicator in the creativity of students, teacher motivation factor has high relation with academic performance of student.

Fractional Calculus-Based Modeling of Electromagnetic Field Propagation in Arbitrary Biological Tissue

The interaction of electromagnetic fields and biological tissues has become a topic of increasing interest for new research activities in bioelectrics, a new interdisciplinary field combining knowledge of electromagnetic theory, modeling, and simulations, physics, material science, cell biology, and medicine. In particular, the feasibility of pulsed electromagnetic fields in RF and mm-wave frequency range has been investigated with the objective to discover new noninvasive techniques in healthcare. The aim of this contribution is to illustrate a novel Finite-Difference Time-Domain (FDTD) scheme for simulating electromagnetic pulse propagation in arbitrary dispersive biological media. The proposed method is based on the fractional calculus theory and a general series expansion of the permittivity function. The spatial dispersion effects are taken into account, too. The resulting formulation is explicit, it has a second-order accuracy, and the need for additional storage variables is minimal. The comparison between simulation results and those evaluated by using an analytical method based on the Fourier transformation demonstrates the accuracy and effectiveness of the developed FDTD model. Five numerical examples showing the plane wave propagation in a variety of dispersive media are examined.

Universe and Matter Conjectured as a 3-Dimensional Lattice with Topological Singularities

One fundamental problem of modern physics is the search for a theory of everything able to explain the nature of space-time, what matter is and how matter interacts. There are various propositions, as Grand Unified Theory, Quantum Gravity, Supersymmetry, String and Superstring Theories, and M-Theory. However, none of them is able to consistently explain at the present and same time electromagnetism, relativity, gravitation, quantum physics and observed elementary particles. In this paper, one summarizes the content of a new book, published in English [2] and in French [3], in which it is suggested that Universe could be a massive elastic 3D-lattice, and that fundamental building blocks of Ordinary Matter could consist of topological singularities of this lattice, namely diverse dislocation loops and disclination loops. For an isotropic elastic lattice obeying Newton’s law, with specific assumptions on its elastic properties, one obtains the result that the behaviours of this lattice and of its topological defects display “all” known physics, unifying electromagnetism, relativity, gravitation and quantum physics, and resolving some longstanding questions of modern cosmology. Moreover, studying lattices with axial symmetries, represented by “colored” cubic 3D-lattices, one has identified a lattice structure whose topological defect loops coincide with the complex zoology of elementary particles, which could open a very promising field of research. Here, only main steps and principal results of the new theory are presented and discussed, without showing the mathematical concepts and developments contained in the book.

Cristales fotónicos empleados en tratamientos médicos

La fotónica se ha estudiado por más de dos décadas con el fin de trabajar en la construcción, desarrollo y manipulación de la luz especialmente de estructuras cristalinas a escala nanométrica para ser empleadas en las telecomunicaciones, computación, celdas solares hasta biosensores, y demás aplicaciones que han sido de gran utilidad en la actualidad como lo es en la biomédica. Por esta razón, en el presente artículo, expone un estudio retrospectivo de los cristales fotónicos, con el propósito de dejar como precedente un estado del arte que manifieste los fundamentos teóricos, aplicativos de cristales fotónicos en tratamientos médicos. Así mismo, se expone de manera descriptiva y comparativa el estudio de los cristales fotónicos según la física desde la perspectiva electromagnética por medio de las leyes de maxwell con una visión macroscópica del comportamiento de los cristales fotónicos y desde el punto de vista de la optoelectrónica. Por último, se expresan conclusiones cualitativas de la implementación de cristales fotónicos en tratamiento médicos.

Progress in Geant4 Electromagnetic Physics Modelling and Validation

In this work we report on recent improvements in the electromagnetic (EM) physics models of Geant4 and new validations of EM physics. Improvements have been made in models of the photoelectric effect, Compton scattering, gamma conversion to electron and muon pairs, fluctuations of energy loss, multiple scattering, synchrotron radiation, and high energy positron annihilation. The results of these developments are included in the new Geant4 version 10.1 and in patches to previous versions 9.6 and 10.0 that are planned to be used for production for run-2 at LHC. The Geant4 validation suite for EM physics has been extended and new validation results are shown in this work. In particular, the effect of gamma-nuclear interactions on EM shower shape at LHC energies is discussed.

First experience of vectorizing electromagnetic physics models for detector simulation

The recent emergence of hardware architectures characterized by many-core or accelerated processors has opened new opportunities for concurrent programming models taking advantage of both SIMD and SIMT architectures. The GeantV vector prototype for detector simulations has been designed to exploit both the vector capability of mainstream CPUs and multi-threading capabilities of coprocessors including NVidia GPUs and Intel Xeon Phi. The characteristics of these architectures are very different in terms of the vectorization depth, parallelization needed to achieve optimal performance or memory access latency and speed. An additional challenge is to avoid the code duplication often inherent to supporting heterogeneous platforms. In this paper we present the first experience of vectorizing electromagnetic physics models developed for the GeantV project.

Multiphysics-based design and analysis of the high-speed aerostatic spindle with application to micro-milling

High-speed aerostatic spindles are essential for ultra-precision micro-milling machine tools. The distinguishing functional characteristics of the spindle system are achieved through innovative design and integration of thermal, fluidic, and electromagnetic physics on the spindle structure and system. These physics, together with the shaft dynamics, interact dynamically and collectively to determine the spindle’s performance. It is thus required to have a comprehensive analysis and scientific understanding on the multiple physics interactions within the spindle, which is essential for design of the spindle working at much higher speeds and accuracy under various increasingly stringent engineering conditions. This paper presents an integrated multiphysics simulation approach to design and analysis of high-speed aerostatic spindles. Based on the proposed approach, an integrated multiphysics simulation platform is developed with application to micro-milling machines. Experiments have been designed and carried out to validate the integrated multiphysics simulation method and evaluate the simulation results, which show that the integrated multiphysics model is able to predict and analyze the performance characteristics of the high-speed aerostatic spindle. The integrated multiphysics model and the corresponding virtual spindle simulation can be used as a powerful design aid for supporting the design and analysis of next generation high-speed aerostatic spindles at nanometric precision.

Modeling microwave heating of frozen mashed potato in a domestic oven incorporating electromagnetic frequency spectrum

Domestic microwave oven magnetrons produce microwaves in a frequency range of 2.45 ± 0.05 GHz. Most microwave heat transfer simulations simplify that the magnetron produces a monochromatic electromagnetic wave of frequency of 2.45 GHz to reduce the computational complexity. This study assumes that the magnetron produces a frequency spectrum defined by a Gaussian distribution of frequencies with a central frequency of 2.45 GHz and investigates the effect of Gaussian distribution variance of (0.05 GHz)2, (0.025 GHz)2, (0.017 GHz)2 on prediction accuracy when compared to using monochromatic frequency of 2.45 GHz. A three-dimensional finite element model coupling electromagnetic and heat transfer physics was developed to simulate heating of 550 g of frozen mashed potato for 6 min. The model was validated in a 1250 W rated microwave oven with the mashed potato tray placed at the center of the stationary turntable. The electromagnetic power densities were determined separately at five different frequencies equidistant between 2.4 and 2.5 GHz. They were then weighted averaged, based on the selected Gaussian distribution. Simulated temperature profiles of the models using the monochromatic frequency of 2.45 GHz and Gaussian frequency spectrum with different variances were compared with experimental temperature profiles obtained using a thermal imaging camera at the end of cooking and five fiber-optic thermocouples during cooking. The model results showed that predicted spatial surface temperature pattern by the model using frequency spectrum with the largest variance (0.05 GHz)2 had better agreement with the experimental temperature pattern when compared to that using a monochromatic frequency of 2.45 GHz. In the transient temperature profile measurement, the average RMSE value of five locations was 7.5 and 13.1 °C for simulations using frequency spectrum and monochromatic frequency of 2.45 GHz, respectively. When compared to using the monochromatic frequency of 2.45 GHz, the frequency spectrum with an assumption of having a Gaussian distribution with mean of 2.45 GHz and variance of (0.05 GHz)2 improved the accuracy of temperature field pattern and transient temperature profile.

Guided waves' dispersion curves in anisotropic viscoelastic single- and multi-layered media

Guided waves propagating in lossy media are encountered in many problems across different areas of physics such as electromagnetism, elasticity and solid-state physics. They also constitute essential tools in several branches of engineering, aerospace and aircraft engineering, and structural health monitoring for instance. Waveguides also play a central role in many non-destructive evaluation applications. It is of paramount importance to accurately represent the material of the waveguide to obtain reliable and robust information about the guided waves that might be excited in the structure. A reasonable approximation to real solids is the perfectly elastic approach where the frictional losses within the solid are ignored. However, a more realistic approach is to represent the solid as a viscoelastic medium with attenuation for which the dispersion curves of the modes are, in general, different from their elastic counterparts. Existing methods are capable of calculating dispersion curves for attenuated modes but they can be troublesome to find and the solutions are not as reliable as in the perfectly elastic case. In this paper, in order to achieve robust and accurate results for viscoelasticity a spectral collocation method is developed to compute the dispersion curves in generally anisotropic viscoelastic media in flat and cylindrical geometry. Two of the most popular models to account for material damping, Kelvin–Voigt and Hysteretic, are used in various cases of interest. These include orthorhombic and triclinic materials in single- or multi-layered arrays. Also, and due to its importance in industry, a section is devoted to pipes filled with viscous fluids. The results are validated by comparison with those from semi-analytical finite-element simulations.

Analysis of Photoacoustic Response from Gold–Silver Alloy Nanoparticles Irradiated by Short Pulsed Laser in Water

We perform a finite element-based numerical analysis to calculate the photoacoustic (PA) signal generated by spherical gold–silver (Au–Ag) alloy nanoparticles (NPs). These spherical particles are size-controlled and monodispersed, with tunable plasmonic resonance wavelength via change of the alloy composition. This enables their use in PA imaging as a contrast agent. This theoretical framework self-consistently solves the electromagnetic, thermodynamic and transient acoustic pressure physics using a multiphysics coupling approach. We model our system as an optically heterogeneous medium irradiated by a nanosecond laser pulse in the tissue therapeutic optical window (NIR irradiation, with wavelength of 800 nm). We calculate the PA signal generated by the photothermal expansion of both the particle and its surrounding medium. The results show the impact of the gold molar fraction (GMF) of Au–Ag alloy NPs on the PA signal for different NP sizes. We show that significantly stronger PA signals are achieved usi...

EMI Coupling Paths and Mitigation in a Board-to-Board Connector

Cage connectors for optical subassembly I/O modules have been identified as one of the main coupling paths in an optical link at the front-end of switches and routers. In the study presented herein, the simulation model used to study electromagnetic interference coupling physics and mitigation of the optical cage connector was corroborated by comparing the measured and simulated results for the total radiated power (TRP). Currents on the adjacent ground references to the differential signal conductors caused half-wave resonant peaks in the TRP response in the frequency range of 4–18 GHz. At frequencies from 18 to 28 GHz, both full-wave simulation and analytical formulas indicate that the radiation results primarily from the currents on the signal traces. The radiation from the optical cage connector was suppressed with absorbing materials, and the coupling path was verified, together with the optical cage and module enclosure.

Comparison of experimental proton-induced fluorescence spectra for a selection of thin high-Z samples with Geant4 Monte Carlo simulations

The general purpose Geant4 Monte Carlo simulation toolkit is able to simulate radiative and non-radiative atomic de-excitation processes such as fluorescence and Auger electron emission, occurring after interaction of incident ionising radiation with target atomic electrons. In this paper, we evaluate the Geant4 modelling capability for the simulation of fluorescence spectra induced by 1.5MeV proton irradiation of thin high-Z foils (Fe, GdF3, Pt, Au) with potential interest for nanotechnologies and life sciences. Simulation results are compared to measurements performed at the Centre d’Etudes Nucléaires de Bordeaux-Gradignan AIFIRA nanobeam line irradiation facility in France. Simulation and experimental conditions are described and the influence of Geant4 electromagnetic physics models is discussed.

Monte Carlo simulations of patient dose perturbations in rotational-type radiotherapy due to a transverse magnetic field: a tomotherapy investigation.

Several groups are exploring the integration of magnetic resonance (MR) image guidance with radiotherapy to reduce tumor position uncertainty during photon radiotherapy. The therapeutic gain from reducing tumor position uncertainty using intrafraction MR imaging during radiotherapy could be partially offset if the negative effects of magnetic field-induced dose perturbations are not appreciated or accounted for. The authors hypothesize that a more rotationally symmetric modality such as helical tomotherapy will permit a systematic mediation of these dose perturbations. This investigation offers a unique look at the dose perturbations due to homogeneous transverse magnetic field during the delivery of Tomotherapy(®) Treatment System plans under varying degrees of rotational beamlet symmetry. The authors accurately reproduced treatment plan beamlet and patient configurations using the Monte Carlo code geant4. This code has a thoroughly benchmarked electromagnetic particle transport physics package well-suited for the radiotherapy energy regime. The three approved clinical treatment plans for this study were for a prostate, head and neck, and lung treatment. The dose heterogeneity index metric was used to quantify the effect of the dose perturbations to the target volumes. The authors demonstrate the ability to reproduce the clinical dose-volume histograms (DVH) to within 4% dose agreement at each DVH point for the target volumes and most planning structures, and therefore, are able to confidently examine the effects of transverse magnetic fields on the plans. The authors investigated field strengths of 0.35, 0.7, 1, 1.5, and 3 T. Changes to the dose heterogeneity index of 0.1% were seen in the prostate and head and neck case, reflecting negligible dose perturbations to the target volumes, a change from 5.5% to 20.1% was observed with the lung case. This study demonstrated that the effect of external magnetic fields can be mitigated by exploiting a more rotationally symmetric treatment modality.

Sesquicentennial of the presentation by James Clerk Maxwell of his paper "A Dynamical Theory of the Electromagnetic Field" to the Royal Society of London

James Clerk Maxwell is generally regarded as the greatest contributor to the development of Physics in the time between Newton and Einstein. His most important contributions are the Kinetic Theory of Gases and Electromagnetism which is the unified theory of Electricity and Magnetism. Although his major work on Electromagnetism was published in 1865 it was read at a meeting of the Royal Society of London in 1864. The sesquicentennial of the theory correctly falls in 2014. In this article that event is celebrated. Parts of his early and professional life are described. Aspects of his many contributions are discussed but mainly we concentrate on his contributions through thermal and electromagnetic Physics.

A low energy bound atomic electron Compton scattering model for Geant4

A two-body fully relativistic three-dimensional scattering framework has been utilised to develop an alternative Compton scattering computational model to those adapted from Ribberfors’ work for Monte Carlo modelling of Compton scattering. Using a theoretical foundation that ensures the conservation of energy and momentum in the relativistic impulse approximation, this new model, the Monash University Compton scattering model, develops energy and directional algorithms for both the scattered photon and ejected Compton electron from first principles. The Monash University Compton scattering model was developed to address the limitation of the Compton electron directionality algorithms of other computational models adapted from Ribberfors’ work. Here the development of the Monash University Compton scattering model, including its implementation in a Geant4 low energy electromagnetic physics class, G4LowEPComptonModel, is outlined. Assessment of the performance of G4LowEPComptonModel was undertaken in two steps: (1) comparison with respect to the two standard Compton scattering classes of Geant4 version 9.5, G4LivermoreComptonModel and G4PenelopeComptonModel, and (2) experimental comparison with respect to Compton electron kinetic energy spectra obtained from the Compton scattering of 662keV photons off the K-shell of gold. Both studies illustrate that the Monash University Compton scattering model, and in turn G4LowEPComptonModel, is a viable replacement for the majority of computational models that have been adapted from Ribberfors’ work. It was also shown that the Monash University Compton scattering model is able to reproduce the Compton scattering triply differential cross-section Compton electron kinetic energy spectra of 662keV photons K-shell scattering off of gold to within experimental uncertainty.

Análise e caracterização das questões das provas da Olimpíada Brasileira de Física

Every year in Brazil, School Olympics are organized including various knowledge areas, such as: Portuguese Language, Mathematics, Biology, Physics, and others. The Brazilian Physics Olympiad (OBF) intends to stimulate students’ interest in Physics, by challenging and encouraging them to pursue careers in science and technology. This paper aims to investigate the contents that are present in the OBF exams and how these are addressed, in order to draw a profile of the exam that is applied to high school students. For this purpose, an analysis of the questions from the exam, from the period between 1999 and 2013, is carried out, and the contents of the questions are separated in six Physics fields: Mechanics, Wave, Thermal Physics, Electromagnetism, Geometric Optics and Modern Physics. Afterwards, graphics are developed in order to identify peculiarities of these tests. The results present positive changes in the profile of the test, which has a more contextualized and interdisciplinary approach, compared to previous editions, in line with the official documents of the Brazilian education.

Effect of decoupling electromagnetics from heat transfer analysis on prediction accuracy and computation time in modeling microwave heating of frozen and fresh mashed potato

Microwave heating models incorporating physics of electromagnetics and heat transfer are computationally intensive, which limits their use in the industry. The electromagnetic power density changes within the food during microwave heating were characterized. The effect of decoupling electromagnetics from heat transfer analysis on accuracy and computation time was evaluated for microwave heating of mashed potato at various initial states (frozen and fresh). Coupled models used updated heat source term based on temperature-dependent dielectric properties for every rotation; while decoupled models used a constant heat source term based on dielectric properties at room temperature. The simulation and validation results showed that the simplification of using the decoupled approach did not affect the predicted temperatures considerably, while reducing the computation time by 93%. When compared to the experiment, the averaged RMSE values of six transient point temperatures of room-temperature and frozen decoupled-models were 5.2 and 6.6°C, respectively, which were close to those of the coupled models. The decoupled model can be used for screening food-package designs in a short computation time. While this study demonstrated the feasibility of using the decoupled approach for a homogeneous food at various initial temperatures, further study needs to be conducted to evaluate this for heterogeneous foods.

Geant4 Electromagnetic Physics for LHC Upgrade

In this work we present recent progress in Geant4 electromagnetic physics modelling, with an emphasis on the new refinements for the processes of multiple and single scattering, ionisation, high energy muon interactions, and gamma induced processes. The future LHC upgrade to 13 TeV will bring new requirements regarding the quality of electromagnetic physics simulation: energy, particle multiplicity, and statistics will be increased. The evolution of CPU performance and developments for Geant4 multi-threading connected with Geant4 electromagnetic physics sub-packages will also be discussed.