Showing papers on "Shields published in 1979"

EMI-Suppression from transmission lines

Abstract: Absorptive shields for transmission lines, especially those tending to radiate electromagnetic wave lengths within a frequency range of from about 10 6 to about 10 10 hertz, especially 10 7 to 10 10 hertz. The shields are flexible materials filled with ferromagnetic, or ferrimagnetic, powders of selected particle size and distribution.

Shielding of longitudinal magnetic fields with thin, closely spaced, concentric cylinders of high permeability material

Abstract: Formulae for the longitudinal shielding effectiveness of N thin, closely spaced, concentric cylinders of high permeability material have been developed and experimentally tested. For shields which cannot be oriented, or which change their orientation in the ambient field, the shielding effectiveness for longitudinal fields is generally the limiting criterion and no design formulae have previously been published for more than two shields. A simple diagrammatical method of writing the shielding formula is presented. Use of these equations is demonstrated by application to the design of magnetic shields for hydrogen maser atomic clocks. Examples of design tradeoffs such as size, weight, and material thickness are discussed. Experimental data on three sets of shields fabricated by three manufacturers are presented.

Electron, Electron-Bremsstrahlung and Proton Depth-Dose Data for Space-Shielding Applications

Abstract: A data set has been developed, consisting of depth-dose distributions for omni-directional electron and proton fluxes incident on aluminum shields. The principal new feature of this work is the accurate treatment, based on detailed Monte Carlo calculations, of the electron-produced bremsstrahlung component. Results covering the energy region of interest in space-shielding calculations have been obtained for the absorbed dose (a) as a function of depth in a semiinfinite medium, (b) at the edge of slab shields, and (c) at the center of a solid sphere. The dose to a thin tissue-equivalent detector was obtained as well as that in aluminum. Various results and comparisons with other work are given.

Transient Response of Braided-Wire Shields

Abstract: We present time-domain measurements to determine the shielding properties of braided coaxial cables. We show the influence of the transfer inductance and capacitance for various geometrical structures of the braid and, furthermore, that the waveform of the response signal depends on the optical coverage ratio of the shield.

Magnetic shielding in a low-temperature torsion pendulum experiment.

Abstract: A new type of ether drift experiment searches for anomalous torques on a permanent magnet. A torsion pendulum is used at liquid helium temperature, so that superconducting cylinders can be used to shield magnetic fields. Lead shields attenuate the earth's field, while Nb-Sn shields fastened to the pendulum contain the fields of the magnet. The paper describes the technique by which the earth's field can be reduced below 0.0001 G while simultaneously the moment of the magnet can be reduced by a factor 7 x 10 to the 4th.

Disk memory module with stackable dust shield

Abstract: An improved disk memory dust shield having an exterior surface similar to the surface of the disk module housing which mates with it, thereby allowing a plurality of dust shields to be nestingly stacked with each other. This permits all the dust shields not currently in use because their disk modules are mounted in drives, to be compactly stored.

Turbo mechanical blade shroud

Abstract: PURPOSE:To prevent a shroud from being eroded due to direct steam jet by putting anti-erosion shields between a blade and a shroud to build up a lamination. CONSTITUTION:A hole 4 to be keyed with a projection 2 on a blade 1 is made through two thin strips of shields 8, 9 made of anti-erosive material. A similar hole is made in a shroud 6, which is put on the shields 8, 9 and the projection 2 of the blade 1 is caulked to fix them on. Each edge of the shields 8, 9 is bent to make a fin 5. The anti-erosive shields 8, 9 are exposed to steam jet to prevent erosion of the shroud. The fins 5 at the ends of the shields 8, 9 function to seal.

Magnetic shield device for box

Abstract: PURPOSE:To effectively prevent eddy current loss and generation of local temperature increase by providing a staircase-like surface or an inclined surface at each end of electromagnetic shields arranged in the vicinity of the inner wall of a box.

Effectiveness and dissipation in cryogenic shields for superconducting field windings

Abstract: This paper is a contribution to the analysis of rotor shielding systems, particularly with respect to shielding and losses in cryogenic shielding systems. The method of surface wave impedance is used in a modified way, and extended to accomodate transposed shields. Solid shields are found to have good shielding properties but relatively large losses, while transposed shields have lower losses but poor shielding. Combination screens may be expected to present satisfactory characteristics, but only with the provision of adequate radial spacing within the rotor.

Mobile granular road ballast spreading and smoothing machine - has two acutely converging shields forming forward distributor on skimmer shield

Abstract: The travelling road building machine is for construction of substructure made up from granular material or varying grain size, esp. a ballast support layer, using a height-adjustable skimming shield. There is an advance distributor (12) at the front of the shield (10), converging at an acute angle in the direction of travel (F); this is plough-shaped, with two shields converging at an acute angle (12a, 12b) and its adjustable across the line of travel. The two shields may be able to swivel independently of each other about a vertical axis. This simplifies mixing of material collected from the heap.