Search results for "electromagnetic [effect]"
showing 10 items of 555 documents
A General Design Procedure for Symmetrical Windings of Electrical Machines
2018
Winding design methods have been a subject of research for many years of the past century. Many methods have been developed, each one characterized by some advantages and some drawbacks. Nowadays, the star of slots is the most widespread design tool for electrical machine windings. In this context, this paper presents a simple and effective procedure to determine the distribution of the EMF stars and of the winding configuration in all possible typologies of electrical machines equipped with symmetrical windings. Moreover, this procedure can also be easily implemented in a computer program in order to perform automated winding designs for rotating electrical machines. Several examples are p…
A Comparison of Special Bonding Techniques for Transmission and Distribution Cables
2020
In this paper, a review of the existing special bonding techniques for medium voltage (MV) and high-voltage (HV) cables is presented. Special bonding techniques have the purpose of reducing sheath currents, thereby limiting copper losses and the reduction of the ampacity of cables. The authors present a literature review to identify various bonding techniques and how these have evolved over the years thanks to new technologies. Simulations of the most used techniques have been performed in Matlab/Simulink, to compare their strengths and drawbacks.
Numerical simulation of radiated EMI in 42V electrical automotive architectures
2006
The work is focused on the evaluation of radiated electromagnetic interference generated by dc/dc converters in 42 V systems automotive environment. The results obtained by using the method of moments and the finite difference time domain method, separately, are presented and validated in comparison with those measured in a semi-anechoic electromagnetic chamber. A measurement system set up by the authors is employed. Both the used numerical approaches are proved to be an useful tool for radiated disturbance prediction, and also for electromagnetic compatibility oriented design of the vehicle electrical architecture.
Exact Canonical Dressing of Two-Level Atoms by Two-Photon Processes
1984
The aim of this paper is to present new exact results on the subject of dressing of a two-level atom by an electromagnetic field.
Lamb shift of a uniformly accelerated hydrogen atom in the presence of a conducting plate
2009
We investigate the effects of acceleration on the energy-level shifts of a hydrogen atom interacting with the electromagnetic field and in the presence of an infinite perfectly conducting plate. We consider the contributions of vacuum fluctuations and of the radiation reaction field to the Lamb shift, and we discuss their dependence from the acceleration of the atom. We show that, because of the presence of the boundary, both vacuum field fluctuations and radiation reaction field contributions are affected by atomic acceleration. In particular, the effect of the vacuum field fluctuations on the energy-level shifts is not equivalent to that of a thermal field. We also discuss the dependence …
The limits of the rotating wave approximation in electromagnetic field propagation in a cavity
2005
We consider three two-level atoms inside a one-dimensional cavity, interacting with the electromagnetic field in the rotating wave approximation (RWA), commonly used in the atom-radiation interaction. One of the three atoms is initially excited, and the other two are in their ground state. We numerically calculate the propagation of the field spontaneously emitted by the excited atom and scattered by the second atom, as well as the excitation probability of the second and third atom. The results obtained are analyzed from the point of view of relativistic causality in the atom-field interaction. We show that, when the RWA is used, relativistic causality is obtained only if the integrations …
Causality, non-locality and three-body Casimir–Polder energy between three ground-state atoms
2006
The problem of relativistic causality in the time-dependent three-body Casimir–Polder interaction energy between three atoms, initially in their bare ground-state, is discussed. It is shown that the non-locality of the spatial correlations of the electromagnetic field emitted by the atoms during their dynamical self-dressing may become manifest in the dynamical three-body Casimir–Polder interaction energy between the three atoms.
One-sided atomic deflection in the optical Stern-Gerlach effect and coherent trapping
2002
In the optical Stern-Gerlach effect, the interaction of a traveling two-level atom with the electromagnetic field of an optical cavity causes a splitting of the atomic trajectory. One may ask if it is possible to single out particular initial configurations of the system that will lead to selective scattering, in which the atoms follow only one trajectory. We show that these configurations consist of a coherent superposition of the atomic internal states, and of a field phase state or a field coherent state, with a precise phase relation between the two subsystems: The same configurations which produce the so-called atomic coherent trapping in the Jaynes-Cummings model.
Magnetic Field and Short-Circuit Reactance Calculation of the 3-Phase Transformer with Symmetrical Amorphous Core
2006
Magnetically symmetric, 3- phase transformer has been analysed. For the two variants of the windings, the calculation results have been compared with the measured ones. Magnetic flux density components were calculated in and out of the core. The flux distribution and short-circuit reactance have been verified experimentally and a good agreement has been obtained.
EMI Analysis in Electrical Drives under Lightning Surge Conditions
2012
In this paper, a complete model of a power drive system including the earth electrodes is proposed to evaluate electromagnetic conducted interference due to lightning pulses. Circuit model of a power drive system is joined with a full-wave approach for the simulation of the time behavior of the grounding system. The proposed model enables to predict the electromagnetic conducted interference generated in the power drive system when lightning conditions involve the earth electrodes.