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EMI Group était une major du disque. La maison de disque a été créée en mars 1931 sous le nom de Electric and Musical Industries, par la fusion de la filiale anglaise de Columbia Records et de la Gramophone Company/HMV. Historique Les débuts d'EMI remontent à 1897 avec la création de la société Gramophone Company, qui exploite l'invention du gramophone. Gramophone Company vend à la fois les disques et les machines pour écouter la musique et devient dans les machines à écrire, l'hôtellerie, la restauration, le bingo, la radio, la télévision, les radars, les scanners. En 1899, pour , la Gramophone Company acquiert un tableau représentant un chien écoutant un gramophone et baptisé His Master's Voice (HMV). Elle en fait son logo qui apparaîtra pour la première fois en 1909. En 1904, à Rome, cette jeune entreprise mène à bien un grand projet d'enregistrement en collaboration avec le Vatican. Il s'agit de la célébration du millénaire de saint Grégoire I

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PHYS-100: Advanced physics I (mechanics)

La Physique Générale I (avancée) couvre la mécanique du point et du solide indéformable. Apprendre la mécanique, c'est apprendre à mettre sous forme mathématique un phénomène physique, en modélisant la situation et appliquant les lois de la physique.

PHYS-201(d): General physics: electromagnetism

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EE-576: Electromagnetic compatibility

In this lecture, students will get the basic knowledge on electromagnetic compatibility.

Localization of Electromagnetic Interference Sources Using a Time-Reversal Cavity

Mohammad Azadifar, Hamidreza Karami, Amirhossein Mostajabi, Marcos Rubinstein

In this article, we propose and implement a novel technique to locate electromagnetic interference (EMI) sources using the concept of time-reversal (TR) cavity. We show in an intuitive manner that reflections from the surfaces of a cavity can emulate an infinite number of sensors in the TR method. In order to locate EMI sources, the equipment under test (EUT) is placed in a rectangular metallic cavity, of suitable dimensions according to the considered frequency band and the EUT size, equipped with a simple monopole or dipole antenna. We demonstrate that by using only one sensor, we are able to locate EMI sources by taking advantage of the focusing properties of a TR cavity. The entropy criterion is applied to obtain the focusing time slice in which the maximum electric field determines the location of the EMI source. Both 2- and 3-D numerical simulation schemes are deployed to demonstrate the ability of the proposed technique. The validity of numerical simulations is tested against frequency domain measurements. Compared with the conventional EMI tests in anechoic chambers and scanning methods, the proposed technique represents a simpler and cost-effective test method requiring only one sensor (a monopole or dipole antenna).

2021

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Single-Sensor EMI Source Localization Using Time Reversal: An Experimental Validation

Mohammad Azadifar, Hamidreza Karami, Farhad Rachidi-Haeri, Marcos Rubinstein, Zhaoyang Wang

The localization of electromagnetic interference (EMI) sources is of high importance in electromagnetic compatibility applications. Recently, a novel localization technique based on the time-reversal cavity (TRC) concept was proposed using only one sensor, and its application to localize EMI sources was validated numerically. In this paper, we present a validation of the proposed time-reversal process in which the forward step of the time-reversal process is performed experimentally and the backward step is carried out via numerical simulations, a realistic scenario which is applicable to practical source localization problems. To the best of the authors’ knowledge, this is the first implementation of a three-dimensional electromagnetic time-reversal process in which the forward signal is provided experimentally while the backward propagation step is carried out numerically. The considered experimental setup is formed by a partially open cavity and two monopole antennas to emulate the EMI source and the sensor (receiving antenna), respectively. Assuming that the location of the source is the feed point of the monopole antenna, the resulting three-dimensional location error in the experimental validation was only 1.49 cm, which is about one-third the length of the monopole antenna, corresponding to about λmin/2 (diffraction limit).

2021

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A Compressive Sensing Framework for EMI Source Localization Using a Metalens Structure: Localization Beyond the Diffraction Limit

Mohammad Azadifar, Hamidreza Karami, Marcos Rubinstein

In this article, we propose a novel approach for the localization of electromagnetic interference (EMI) sources based on the concept of compressive sensing and metalenses. We show that using the spatial and frequency dispersion offered by the metalens, we can create a scanning beam to provide an image of the current distribution in a printed circuit board. We deployed a computational imaging framework to extract the information in the observation plane of the imaging system and thus obtain the location of the EMI source. To use mode diversity offered by the metalens, we suggest using the compressive sensing platform. To the authors’ best knowledge, this is the first utilization of metalenses, computational imaging, and compressive sensing to locate EMI sources. Numerical simulation is used to implement and investigate the ability of the proposed approach to localized EMI sources. The obtained results show a very accurate localization skill. The proposed approach overcomes the diffraction limit and provides λ /17 superresolution. Moreover, the proposed approach uses a single stationary antenna to collect data and does not need either mechanical scanning, which is time consuming, or a beamforming array, which is expensive.

2022

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Industrie musicale

vignette|Industrie et Musique (allégories) au musée ethnographique de Budapest L'industrie musicale (appelée également industrie du disque) désigne les activités qui contribuent à l'offre de produits

Royaume-Uni

Le Royaume-Uni (prononcé en français : ), en forme longue le Royaume-Uni de Grande-Bretagne et d'Irlande du Nord (United Kingdom et United Kingdom of Great Britain and Northern Ireland), est un p

Sound recording and reproduction

Sound recording and reproduction is the electrical, mechanical, electronic, or digital inscription and re-creation of sound waves, such as spoken voice, singing, instrumental music, or sound effects.