Academic literature on the topic 'Flat electromagnetic shield'

In the article, the magnetic and thermal field distributions generated by underground two-circuit extra-high voltage power cable line in the environment, particularly near the cables and flat aluminum shield, which is located at a different distance from the cables and has different thicknesses, are analyzed. The unique features of the magnetic field and temperature distributions inside the shield are computed and studied. For the cases under consideration, the Joule losses in the external shield do not exceed 3% of the losses in the cables. The primary electromagnetic characteristics are compared for the aluminum shield (shielding efficiency is 1,94) and the shield with lower conductivity (shielding efficiency is equal to 1,2). As shown, the thicker shield helps to increase the ampacity of the cable line owing to lower heating. The actual operating current of the cable line under consideration depends on the distance of the shield from the cables owing to the relation between their maximum temperature and this distance. Ref. 15, fig. 7, table.

Abstract The width-bending behaviors for a rare earth barium copper oxide (REBCO) high-temperature superconducting (HTS) tape have been investigated. It has been found experimentally that the width-bending strain of a Yttrium Barium Copper Oxide (YBCO) tape does not degrade the critical current as much as is expected from the axial strain. The critical current is not directly affected by the width-bending strain but by the axial strain, which the width-bending strain generates by the Poisson effect. Since Poisson’s ratio is about 0.3, the axial strain effective on the critical current is about 30% of the width-bending strain. Therefore, the width-bending strain of even 1.5% degrades the critical current by only 15% if the REBCO layer side is bent inward. However, the critical current degraded by more than 70% when the REBCO layer is outward. The width-bending effects on the critical current have been further examined, considering Poisson’s ratio changes and the neutral plane shift of the REBCO tape substrate. Those changes would occur when the material yields due to severe width-bending. Based on the width-bending of REBCO tapes, flat-tape Rutherford-type cabling is discussed. A REBCO Rutherford-type cable can provide various advantages, especially for narrow-tape cabling. The flat-tape Rutherford-type cable has better characteristics against an electromagnetic transverse Lorentz force. Furthermore, the tape length of the cable can be approximately the same as the cable length allowing for excellent tape usage. REBCO Rutherford-type cabling will be a promising high-current, high-field cabling method using thin substrate REBCO tapes. It will be useful for AC ramp-field and pulse-field applications with low AC losses and low shield currents. It notes that the filaments in the cable are symmetrically distributed in parallel. Therefore, each filament’s inductance is uniform, and a uniform current distribution among the filaments can be obtained.

Abstract We have developed a three-component borehole seismometer, using 2-Hz electromagnetic moving-coil geophones as sensing elements. The main achievement of our new borehole package is a compact internal device for leveling horizontal geophones. Horizontal moving-coil geophones with a period longer than 0.5 sec need to be leveled to better than 1.5° to avoid nonlinear response and asymmetric clipping. In boreholes, where the axis of the package may well deviate from the vertical by more than 1.5°, a special device is required for leveling the horizontal geophones. A gimbal stage was adapted from the design of ocean-bottom seismometers for leveling the two orthogonally oriented horizontal geophones: the geophones can be leveled to better than 0.1° from an initial tilt of 10.5°. The external package is 14 cm in diameter and approximately 40 cm long. The gimbal stage uses free-flex flexural pivots and, during the leveling operation, suspends a brass pendulum that houses the horizontal sensors. In comparison with borehole seismometers that use electronic-feedback principles, the disadvantages of our system are a lack of response at long periods and, because of coil contacting stops, its inability to record strong motions. Nonetheless, it has an inherently low noise level, consumes no power, is simple to build, and is inexpensive; it is therefore suitable for rapid deployment for aftershock studies and for low-noise operation at remote sites. Such seismometers, using Mark Products L-22D 2-Hz geophones, have been installed at several sites in California: at the bottom of adjacent boreholes ∼ 150 and ∼ 300 m deep, in granite at station KNW near Keenwild and at Piñon Flat of the Anza digital seismic array, and at the bottom of an 88-m-deep borehole in hydrothermally altered serpentine in the Marina District of San Francisco. The effects of cable impedance on the geophone output have been analyzed and found to be negligible for a cable length of 335 m consisting of four pairs of shielded #20 gauge wires. Azimuthal orientation of horizontal geophones can be determined using first P-arrival particle motion generated by regional earthquakes. Earthquake data recorded by these borehole seismometers have been employed by several investigators for studies on the effects of near-surface weathered rocks on the corner frequencies of earthquake spectra near Anza, California, on the seismic-shear-wave-polarization characteristics of seismograms recorded in the southern California batholith at 300 m depth, and on site-resonance amplification caused by sedimentary deposits overlying bedrock in the Marina District of San Francisco.

Актуальність теми: екранування надвисокочастотних електромагнітних полів завад є важливим завданням фізичного захисту та підвищення електромагнітної сумісності радіоелектронної апаратури. Мета дослідження: визначення матеріалів, що найкращі для використання у електромагнітних екранах для придушення надвисокочастотних завад. Об'єкт дослідження: електромагнітні екрани. Предмет дослідження: ефективність екранування з оцінкою коефіцієнтів екранування. Наукова новизна одержаних результатів: наукова новизна полягає у підвищенні ефективності екранування апаратури від електромагнітних завад надвисокої частоти шляхом конструювання екранів у вигляді трьох шарів різнотипних металів (магнітного та немагнітного), коли проміжний шар магнітний, а граничні — немагнітні. Окрім того, тришаровий екран суттєво підвищує коефіцієнт екранування за рахунок збільшення ефективності механізму відбиття електромагнітної хвилі від границь шарів. Публікації: Ніколенко Б. М. Електромагнітні екрани для надвисокочастотних полів / Комп'ютерне моделювання та оптимізація складних систем (КМОСС-2018): матеріали IV Міжнародної науково-технічної конференції / ДВНЗ "УДХТУ". - Дніпро: Баланс-клуб, 2018. - с. 91 - 93.
Relevance of the topic: Shielding of ultrahigh frequency electromagnetic interference fields is an important task of physical protection and electromagnetic compatibility improvement in radio electronic devices. Research purpose: the defining of materials the best to use in electromagnetic shields for ultrahigh frequency interferences rejecting. Object of research: electromagnetic shields. Subject of research: shielding efficiency with shielding factor estimation. Scientific novelty: scientific novelty lies in improving the efficiency of equipment shielding from electromagnetic ultrahigh frequency interferences. It is doing by constructing the shields as three layers of different types of metals (magnetic and nonmagnetic), when the intermediate layer is magnetic and the boundary layers are nonmagnetic. Furthermore, the three-layer shield greatly increases the shielding factor by raising the mechanism of efficiency by reflection of the electromagnetic wave from layer boundaries. Publications: Ніколенко Б. М. Електромагнітні екрани для надвисокочастотних полів / Комп'ютерне моделювання та оптимізація складних систем (КМОСС-2018): матеріали IV Міжнародної науково-технічної конференції / ДВНЗ "УДХТУ". - Дніпро: Баланс-клуб, 2018. - с. 91 - 93.