A well‐posed problem for electromagnetic media with quadrupoles

In this paper, we consider a non‐local electromagnetic medium for which the quadrupole term in the electric induction is not negligible. After giving an outline of the physical model, the problem of Maxwell equations for such a medium is addressed by proving existence and uniqueness of solutions and a principle of constrained minimum is shown to hold as a consequence of some thermodynamical restrictions. Copyright © 2003 John Wiley & Sons, Ltd.     

Note on “Domain wall universe in the Einstein–Born–Infeld theory” [Phys. Lett. B 679 (2009) 160]

The interaction between bulk and dynamic domain wall in the presence of a linear/non-linear electromagnetism make energy density, tension and pressure on the wall all variables, depending on the wall position. In Lee et al. (2009) [1] this fact seems to be ignored.     

Variational principles in electromagnetism

A history of variational principles is presented through theirapplications to linear models arising from the theory of electromagnetism.This historical survey is enriched by some original contribution.     

《电磁学》中静电类问题的可视化仿真实验设计

《电磁学》中基本概念、基本规律理论性强、场图复杂.针对离散点电荷系在空间产生的场分布、静电场中导体的静电感应现象、静电场中电介质的极化现象等典型静电类电磁问题,利用Matlab中的偏微分方程工具箱(PDEtool)、数学物理方程进行可视化仿真实验设计.仿真结果中电场线、等势线的分布很好地体现出典型电磁现象及相关物理性质,有助于信息技术条件下的教学方法改革.     

Forms of the evans-vigier fieldB (3)

The newly inferred longitudinal magnetic field of vacuum electromagnetism is given in a number of equivalent forms derived in several different ways. It is therefore overwhelmingly likely that the Evans-Vigier fieldB ⁽³⁾ will be isolated experimentally through its characteristic square root power density dependence. It is the first classical field of vacuum electromagnetism to be inferred since Maxwell and as such fundamentally extends our understanding of the nature of electromagnetism and field-particle theory.     

On disagreements concerning transformation rules for electromagnetic quantities

My purpose is to discuss some disagreements found in the literature on electromagnetic theory, bearing on how the fields should be transformed under improper transformations of spatial coordinates and time reversals. I hope to encourage workers to eliminate the disagreements. Also, I will point out logical errors made by some experts.      

The electromagnetic impulse pendulum and momentum conservation

Summary Largely quantitative experiments by Pappas have indicated that the momentum imparted to an electrodynamic impulse pendulum was not balanced by an equal and opposite momentum change of field energy as required by the special theory of relativity. The authors repeated Pappas' experiment using discharge currents from a capacitor bank which contained a known amount of stored energy. It turned out that, for momentum conservation, the magnetic-field energy required would have been 1000 to 2000 times as large as the energy that was actually stored in the capacitors. In the second part of the paper the pendulum experiments are interpreted in terms of Ampère's force law. It is shown that the Ampère force exerted on the pendulum is almost exactly the same as the lorentz force, but it arises in different parts of the pendulum conductor. Furthermore, the Ampère reaction force does not reside in the field but in the stationary part of the circuit which supplies current to the pendulum. Hence in the Ampère electrodynamics the momentum is definitely conserved. The experimental and analytical findings confirm the work by Pappas. A new and important experimental fact emerged from the present investigation. The momentum imparted to the pendulum was found to be significantly smaller than the calculated mechanical impulse given by the Lorentz and Ampère force laws. The Ampère force distribution offers an explanation of this observation in terms of the elastic distortion of the pendulum structure. The Lorentz force distribution could not produce this distortion.

---

Riassunto Esperimenti ampiamente quantitativi di Pappas hanno indicato che l'impulso assegnato ad un pendolo ad impulso elettrodinamico non è bilanciato da un cambio d'impulso uguale e opposto dell'energia del campo come richiesto dalla teoria speciale della relatività. Gli autori ahnno ripetuto l'esperimento di Pappas usando correnti di scarico da una riserva di capacitori che contiene una quantità nota di energia immagazzinata. Risulta che, per la conservazione del momento, l'energia del campo magnetico richiesta sarebbe da 1000 a 2000 volte grande come l'energia che è in realtà immagazzinata nei capacitori. Nella seconda parte del lavoro gli esperimenti cel pendolo sono interpretati sulle basi delle leggi di forza di Ampère. Si mostra che la forza di Ampère esercitata sul pendolo è quasi esattamente uguale alla forza di Lorentz, ma essa si verifica in parti differenti del conduttore del pendolo. Inoltre, la forza di reazione di Ampère non sta nel campo, ma nella parte stazionaria del circuito che fornisce corrente al pendolo. Quindi nell'elettrodinamica di Ampère l'impulso è conservato in maniera definita. I risultati sperimentali e dell'analisi confermano il lavoro di Pappas. Da questo studio è emerso un nuovo ed importante fatto sperimentale. Il momento impartito al pendolo appare essere specificativamente piú piccolo dell'impulso meccanico calcolato fornito dalla leggi di forza di Lorentz ed Ampère. La distribuzione di forze di Ampère offre una spiegazione di questa osservazione in termini di distorsione elastica della struttura del pendolo. La distribuzione di forze di Lorentz potrebbe non produrre questa distorsione.

---

Резюме Количественные эксперименты Паппаса показывают, что импульс, переданный электромагнитному импульсному маятнику, не компенсируется равным и противоположным изменением импульса поля, как это следует из специальной теории относительности. Авторы повторили эксперимент Паппаса, используя разряд батареи конденсаторов, которая содержит известное количество запасенной энергии. Оказывается, что для охранения импульса требуемая энергия магнитного поля должна в 1000–2000 раз превосходить энергию, фактическн запасенную в конденсаторах. Во второй части статьи эксперименты с маятником интерпретируются в терминах закона для силы Ампера. Показывается, что сипа Ампера, действующая на мятник, оказывается точно такои же, как сила Лоренца, но возникает в разных частях прводника маятника. Кроме того, сила реакции Ампера принадлежит не полю, а стационарной части контура, который подводит ток к маятнику. Следовательно, электродинамический импульс Ампера сохраняется. Экспериментальные и теоретические результаты подтверкдают работу Паппаса. Из проведенных исследований получен новый и важный зкспериментальный результат. Обнаружено, что импульс, переданный маятинку, оказывается знапительно меньше, чем вычесленный механический импульс, определяемый законами для сил Ампера и Лоренца. Распеделение силы Ампера предлагает объяснение этого факта с помощью упругой деформации структуры маятника. Распределение силы Лоренца не может создавать такой деформации.

     

The resonances of parametric vibration with forced vibration of the stator system of hydroelectric-generator stimulated by electromagnetism

The resonances of parametric vibration with forced vibration is analyzed, the bifurcation equation of the system is obtained and the singularity analysis is made. Some of the laws and phenomena are revealed. The transition variety and bifurcation diagram of the physical parametric plane are given. The results can be used in engineering. Supported by National Natural Science Foundation and Doctoral Programme Foundation of Institution of Higher Education of China.     

Simulations of single charged particle motion in external magnetic and electric fields

In this paper we present a software package for computational modeling of single particle motion in static and dynamic external magnetic and electric fields and show applications of our package to general cases and particular cases of space, laboratory and fusion plasmas. In addition we further elaborate on the properties of a new concept named Larmor Center Trajectory that we introduced in our previous work [D. Erzen, J.P. Verboncoeur, J. Duhovnik, N. Jeli, Int. J. Multiphys. 1, 419 (2007)] as a generalization of the well known guiding center approximation, and show the ranges of applicability of this concept, especially in strongly inhomogeneous fields when adiabatic approximations break.     

Classical dielectric models of fullerenes and estimation of heat radiation

With the aim of describing the cooling of highly excited fullerene molecules by heat radiation, we consider simple classical, dielectric models for calculation of the electromagnetic response and show that the overall distribution of oscillator strength for electronic transitions can be represented fairly well by such a model. The connection to a layer model for graphite is discussed. For thermal emission of radiation from fullerenes, which depends on the oscillator strength at low frequencies only, the classical dielectric model leads to a prediction which should be applicable at high temperatures where the fine structure of the oscillator strength distribution is smeared out. We also estimate the emission from infrared-active vibrations, which dominate at low temperatures but play a minor role at the high temperatures where formation and decay of fullerene molecules take place. Received 22 November 1999 and Received in final form 19 April 2000