Search results for "MAGNETIC FIELD"

Comparative Determinations of Magnetic Induction in AC and DC Circuits

2019

The influence of the electromagnetic field on the human body, although still heavily studied, can have long-term negative effects. The static electromagnetic field is generated by a continuous current source and has a current flow characteristic conventionally set + from -. The variable electromagnetic field is produced by the alternating current and has the ability to change its direction over time with a frequency of 50 or 60 Hz. It is considered that the non-hazardous limit value for the magnetic field (according to Federal Office for Radiation Security in Germany) is 100 microT for 50 Hz and 83 microT for 60 Hz. For the electric field, the exposure limit value is 5kV/m. Electromagnetic …

Flux density at the airgap of small DC motors with different permanent-magnet poles

1993

Human Sleep EEG under the Influence of Pulsed Radio Frequency Electromagnetic Fields

2000

Former exploratory investigations of sleep alterations due to global system for mobile communications (GSM) signals have shown a hypnotic and REM-suppressive effect under field exposure. This effect was observed in a first study using a power flux density of 0.5 W/m<sup>2</sup>, and the same trend occurred in a second study with a power flux density of 0.2 W/m<sup>2</sup>. For the present study, we applied a submaximal power flux density of 50 W/m<sup>2</sup>. To investigate putative effects of radio frequency electromagnetic fields (EMFs) of cellular GSM phones on human sleep EEG pattern, all-night polysomnographies of 20 healthy male subjects both with …

Reply to “Comment on ‘Limits of the measurability of the local quantum electromagnetic field amplitude’ ”

1999

Green’s Function of a Spin- 1 2 $$\tfrac {1}{2}$$ Particle in a Constant External Magnetic Field

2020

Our objective here is to find the Green’s function of a spin-\(\tfrac {1}{2}\) particle in an external electromagnetic field. Accordingly we start with the defining equation

Time-dependent Maxwell field operators and field energy density for an atom near a conducting wall

2009

We consider the time evolution of the electric and magnetic field operators for a two-level atom, interacting with the electromagnetic field, placed near an infinite perfectly conducting wall. We solve iteratively the Heisenberg equations for the field operators and obtain the electric and magnetic energy density operators around the atom (valid for any initial state). Then we explicitly evaluate them for an initial state with the atom in its bare ground state and the field in the vacuum state. We show that the results can be physically interpreted as the superposition of the fields propagating directly from the atom and the fields reflected on the wall. Relativistic causality in the field …

Compton Scattering Program Studying Nucleon Polarizabilities

2017

The A2 collaboration at the Mainz Microtron has undertaken a program of Compton scattering experiments with the goal of extracting the proton and, in the future, neutron polarizabilities. These are fundamental parameters that describe the response of the nucleon to an electromagnetic field. An extraction of these parameters will provide a crucial test of QCD theories. This talk presented the concept and status of this program, including some preliminary results.

The renormalized electron mass in non-relativistic quantum electrodynamics

2007

This work addresses the problem of infrared mass renormalization for a scalar electron in a translation-invariant model of non-relativistic QED. We assume that the interaction of the electron with the quantized electromagnetic field comprises a fixed ultraviolet regularization and an infrared regularization parametrized by $\sigma>0$. For the value $p=0$ of the conserved total momentum of electron and photon field, bounds on the renormalized mass are established which are uniform in $\sigma\to0$, and the existence of a ground state is proved. For $|p|>0$ sufficiently small, bounds on the renormalized mass are derived for any fixed $\sigma>0$. A key ingredient of our proofs is the operator-t…

Exact solution of generalized Tavis - Cummings models in quantum optics

1996

Quantum inverse methods are developed for the exact solution of models which describe N two-level atoms interacting with one mode of the quantized electromagnetic field containing an arbitrary number of excitations M. Either a Kerr-type nonlinearity or a Stark-shift term can be included in the model, and it is shown that these two cases can be mapped from one to the other. The method of solution provides a general framework within which many related problems can similarly be solved. Explicit formulae are given for the Rabi splitting of the models for some N and M, on- and off-resonance. It is also shown that the solution of the pure Tavis - Cummings model can be reduced to solving a homogen…

Automatic optimization of multichip RFID tags

2012

The automatic optimization is proposed of the passive RF part of RFID, with special attention to multi-chip tags, and to the novel concept of RFID grids. Performance metrics follows a recent all-comprehensive approach. The proposed approach employs a Genetic Algorithm-based optimization, and an efficient electromagnetic problem parameterization and solution strategy. Resulting structures, while non-intuitive in shape, exhibit enhanced performance.