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Showing papers on "Shields published in 1999"


Patent
01 Dec 1999
TL;DR: In this paper, a new antenna coil shield is proposed to filter interacting electromagnetic energy field components to pass those components corresponding to a magnetic dipole oriented at an angle from the tool axis.
Abstract: Methods and apparatus for making directional measurements of earth formations surrounding a borehole. New antenna coil shield designs are utilized to provide selective attenuation of at least one electromagnetic energy field component as the component interacts with the shield. The new shields are implemented in several downhole tool configurations to provide azimuthally focused formation measurements. In effect, the new shield filters interacting electromagnetic energy field components to pass those components corresponding to a magnetic dipole oriented at an angle from the tool axis. The shields thereby alter a coil's envelope of influence to electromagnetic energy. The new shields also form part of a system for making directional measurements while drilling.

114 citations


Journal ArticleDOI
TL;DR: In this article, the neutral beam power transmitted into the helical axis stellarator TJ-II is calculated for the final duct design of TJ-2, where the transmitted beam is intercepted by the first toroid-alfield coil before reaching the plasma.
Abstract: The neutral beam power transmitted into the helical axis stellarator TJ-II is calculated for the final duct design of TJ-II. The transmitted beam is intercepted by the first toroidalfield coil before reaching the plasma. The nontrappedfraction of the beam hits various vacuum vessel components. The adopted design of the graphite thermal shields used as vacuum vessel protection at TJ-II is presented. The design achieves a compromise between maximum power into the torus and minimum loads on sensitive parts. A three-dimensional version of the beam geometric code DENSB is set up to calculate the power loads due to shine-through neutrals on the shields under these circumstances. Power load maps are the input to the finite element code ANSYS for the calculation of temperature distributions. For the usual duty cycle at TJ-II (300-ms pulses every 300 s), the peak surface saturation temperatures at all surfaces remain under 650 °C, well below the tolerable limits for graphite.

27 citations


Patent
16 Apr 1999
TL;DR: In this paper, conductive shields have contoured mating surfaces that become flat, or co-planar, at the circuit board-shield interface when the shields are fastened to opposite sides of a circuit board.
Abstract: In a shielding scheme for circuit boards, conductive shields have contoured mating surfaces that become flat, or co-planar, at the circuit board-shield interface when the shields are fastened to opposite sides of the circuit board. The contoured mating surfaces compensate for deformation of the shields resulting from the fastening so that uniform mechanical pressure is applied at all designated points along the circuit board-shield interface even though fastening points are intermittently spaced throughout the shields. When compressible conductive gaskets are optionally interposed between the shields and the circuit board, stops are included to accommodate for the thickness of the gasket. High signal isolation is achieved without correspondingly high contact area on the circuit board and without closely-spaced fastening points. Low assembly time and manufacturing cost results for shielded circuit board assemblies incorporating the shielding scheme.

23 citations


Journal ArticleDOI
01 May 1999
TL;DR: In this paper, the authors investigated the shielding characteristics of galvanized iron trunking and found that both field reflection and field attenuation are two key factors, determined by impedance and skin depth ratios, respectively.
Abstract: Metallic enclosures of rectangular shape (e.g. galvanised iron trunking) are often installed in large buildings for the purpose of mechanical protection. Recently shielding performance of such enclosures has been of interest as a result of concerns about power-frequency magnetic field interference. The paper addresses shielding characteristics of rectangular shields, based on theoretical discussion, numerical simulations and laboratory experiments. It is found that both field reflection and field attenuation are two key factors, determined by impedance and skin depth ratios, respectively. Galvanised iron trunking can be approximately modelled as a linear shield with a constant equivalent relative permeability, the value of which is proportional to current magnitude. The shielding impact of shield parameters and source orientation, as well as guidelines for trunking design, is also discussed.

17 citations


Patent
08 Nov 1999
TL;DR: In this paper, a paper roll is inserted into the dispenser, the edge of the roll contacts the shields pushing the shields into the cavities and when the paper roll tube bore reaches the shields, the shields become re-positioned in the bore of the tissue paper roll by a tensioning device.
Abstract: A toilet paper dispenser which serves the dual role of providing paper roll support arms and a shields for the cavity in the support arms. When a paper roll is inserted into the dispenser, the edge of the roll contacts the shields pushing the shields into the cavities and when the paper roll tube bore reaches the shields, the shields become re-positioned in the bore of the paper roll by a tensioning device.

16 citations


Journal ArticleDOI
TL;DR: In this paper, a new approximating formula for calculating gamma-ray buildup factors in multilayer shields was proposed, which combines the buildup factors of single-layer shields with products and quotients.
Abstract: This study proposes a new approximating formula for calculating gamma-ray buildup factors in multilayer shields. The formula combines the buildup factors of single-layer shields with products and quotients. The feasibility of the formula for reproducing the buildup factors was tested by using point isotropic buildup factors calculated with the SNID discrete ordinates code as reference data. The dose buildup factors of single-, double-, and multilayer shields composed of water, aluminum, iron, and lead were calculated for a spherical geometry in the energy range between 10 MeV and 40 keV and for total thicknesses of up to 30 mean free paths. The calculation of the buildup factors takes into account the bound electron effect of Compton scattering (incoherent scattering ), the coherent scattering, the pair production, and the secondary sources of bremsstrahlung and fluorescence. The tests have shown that the approximating formula reproduces the reference data of double-layer shields very well for most cases. With the same parameters and with a new physical consideration that takes into account in a global way the degradation of the gamma-ray energy spectrum, the buildup factors of three- and five-layer shields were also very well reproduced.

11 citations


Journal ArticleDOI
Eugene Paperno1
18 May 1999
TL;DR: In this article, the axial shielding factors of single and double-shell open-ended cylindrical magnetic shields are calculated numerically and represented by charts, where the thickness of the shells is small compared to the largest diameter and the permeability is independent of magnetic induction.
Abstract: Axial shielding factors of single and double-shell open-ended cylindrical magnetic shields are calculated numerically and represented by charts. It is assumed that the thickness of the shells is small (1%) compared to the largest diameter and the permeability is independent of magnetic induction. Dependencies of the axial shielding factors on the shields' geometry and permeability are calculated numerically and represented finally as logarithmic-scale contour plots. Single-shell shields are described by one chart only where the length-to-diameter ratio (1 to 10) and the permeability (10/sup 1/ to 10/sup 4/) normalized to the thickness-to-diameter ratio are variable parameters. Double-shell shields are described by a set of charts where the ratio of the shells' lengths (0 to 1) and the normalized permeability are variable parameters while the outer shell length to diameter ratio (3, 4, and 5) and the ratio of the shells' diameters (0.5, 0.6...0.9) are fixed parameters.

10 citations


Patent
08 Feb 1999
TL;DR: In this article, the exact position of a short along a conductor, even if the conductor is co-located with other conductors, even conductors connected to low resistance loads, is precisely located.
Abstract: A unique system has been provided to precisely locate the exact position of a short along a conductor, even if the conductor is co-located with other conductors, even conductors connected to low resistance loads. A combination of low frequency test pulse signals, at low duty cycles, and the use of a directional sensor made with shields, account for accuracy and reliability of the system. The shields are arranged to optimally shield and direct signals at the transmitter test signal frequency. The shields also acts to place the shorted wire an optimal distance from the sensor. A method of short circuit location, using the direction sensor of the above-mentioned detection system, is also provided.

9 citations


Patent
Cheng Te Lin1
22 Nov 1999
TL;DR: In this paper, an electrical connector is provided which has first and second shields which fit over an insulative housing, each of the two shields is generally U-shaped, having a central panel and a pair of opposed side panels.
Abstract: An electrical connector is provided which has first and second shields which fit over an insulative housing. Each of the two shields is generally U-shaped, having a central panel and a pair of opposed side panels. The two shields fit over the housing so that the two mating panels overlap. The side panels of the two shields are disposed against four respective sides of the housing, providing substantial shielding of the connector. Each of the side panels includes a mounting foot which extends from a bottom edge for mounting the connector to a circuit board. Each of the U-shaped shields may be formed from a generally strip-shaped blank, enabling an efficient use of materials with little waste.

6 citations


Patent
01 Mar 1999
TL;DR: Magnetic shields for plastic molded electricity meter frames are positioned to substantially block external magnetic fields from adversely affecting operation of meter components as discussed by the authors, which can be utilized with either electromechanical or electronic energy meters.
Abstract: Magnetic shields for plastic molded electricity meter frames are positioned to substantially block external magnetic fields from adversely affecting operation of meter components. The shield can be utilized with either electromechanical or electronic energy meters. In an electromechanical watthour meter which employs an aluminum disk driven to rotate through a magnetic field produced by a retarding magnet, the meter frame includes an integrally formed retarding magnet shield and an integrally formed bearing shield. The shields are coextensive with the frame, and extend from an inner periphery of the frame toward the retarding magnet and the bearing, respectively. The shields are formed of a magnetically permeable powder, such as a ferrite powder mixed with the plastic material from which the meter frame is molded. The shields divert externally applied fields away from the magnetically sensitive components of the meter without adversely affecting meter accuracy.

4 citations


Journal ArticleDOI
TL;DR: In this article, the effect of thin shields of metal-composites based on a matrix of aluminum with dispersed inclusions of SiO2 and Al2O3 for hypervelocity impact of spherical steel particles are examined in a one-layer protection scheme.
Abstract: The protective effect of thin shields of metal-composites based on a matrix of aluminum with dispersed inclusions of SiO2 and Al2O3 for hypervelocity impact of spherical steel particles are examined in a one-layer protection scheme. The protective effect of shields of these materials are found to be inferior to shields of homogeneous aluminum alloy.

Proceedings ArticleDOI
13 Apr 1999
TL;DR: In this paper, an Advanced Photon Source (APS) storage ring (SR) consisting of long rigid vacuum chambers connected by flexible formed bellows components is designed with leaf spring beryllium-copper (Be-Cu) alloy contact fingers that insert into mating rigid sleeves to function as electromagnetic shields.
Abstract: The Advanced Photon Source (APS) storage ring (SR) consists of long rigid vacuum chambers connected by flexible formed bellows components. These SR bellows and additional diagnostic chambers are designed with leaf spring beryllium-copper (Be-Cu) alloy contact fingers that insert into mating rigid sleeves to function as electromagnetic shields. The shields protect the bellows convolutions from particle beam image currents and RF energy and reduce beam-induced RF resonances in the diagnostics chambers. The beam aperture of the shields is approximately the same as that of the beam chambers so that the beam impedance of the SR is minimized. The bellows shields systems' thermal performance has been tested and is monitored during APS SR beam operations. Testing included infrared radiometer camera imaging and thermocouple instrumentation of the rigid sleeve. Direct results indicate that the liners perform well under all stored beam fill loadings through and including 100-mA, 8-bunch operations. Maximum temperatures of the bellows liner systems are typically 35-500 Celsius during standard 100 mAmp stored beam fills and 50-700 Celsius during fills, producing both maximum peak and total current simultaneously. The indirect observations of ring vacuum levels support the temperature data.

Patent
28 May 1999
TL;DR: In this article, the authors proposed a method to prevent local overheating in magnetic material shields and a tank and the thermal degradation of insulators protecting the shields or the like, by a method wherein insulators are respectively provided vertically between the shields and the inside of the tank in the height direction of a tank to form cooling flow paths.
Abstract: PROBLEM TO BE SOLVED: To prevent local overheat in magnetic material shields and a tank and the thermal degradation of insulators protecting the shields or the like, by a method wherein insulators are respectively provided vertically between the shields and the inside of the tank in the height direction of the tank to form cooling flow paths. SOLUTION: Magnetic material shields 8 formed by laminating silicon steel plates of a thin plate thickness in a width W are provided side by side at the positions opposing to inside and outside winding wires 4 and 5 on the inside of a tank 7 housed with a transformer body, comprising a main leg 1, side legs 2, upper yoke parts 3 and the inside and outside winding wires 4 and 5, via prescribed gap parts in the lateral directions, in such a way that the longitudinal directions of the shields 8 are made perpendicular and the shields 8 are respectively provided with press metal fittings. Insulators are provided for protecting the shields 8, and insulators 10 are respectively provided vertical between the insulators and the inside of the tank 7 in the height direction of the tank to form cooling flow paths 11. As a result, local overheating in the shields 8 and the tank 7 and the thermal degradation of the insulators for protecting the shields 8 can be prevented from being caused.

Journal ArticleDOI
TL;DR: In this article, an experimental method is presented and an experimental study is made of the protective properties of flat shields for a series of materials of specific thicknesses, the decay factors of the materials are determined, and the characteristics of shock-wave loads which have passed through the shield are examined.
Abstract: An experimental method is presented and an experimental study is made of the protective properties of flat shields for a series of materials of specific thicknesses. The decay factors of the materials are determined, and the characteristics of shock-wave loads which have passed through the shield are examined.



Patent
31 May 1999
TL;DR: In this article, a submersible electric motor consisting of a body, a stator, a rotor, an end shield, and packing rings are placed into the ring-shaped canals.
Abstract: The invention relates to the machine building, particularly to the submersible electric motorsThe submersible electric motor comprises a body (1), a stator (2), a rotor (4), end shields (5, 6) and packing rings (11), filling elements placed into the ring-shaped canals, made on the cylindrical surfaces of the body (1) oriented one to another and the end shields (5, 6)The outer cylindrical surfaces of the end shields (5, 6) form together with the body (1) a single cylindrical surface, the filling elements are made with elastic segments and in the end shields (5, 6) there are made radial openings (7), by that the filling elements are placed into the radial openings (7) flush with the outer surface of the electric motorThe cantilever parts of the body (1) bulge out over the frontal surface of the stator (2) with not more than 30 mmThe technical result consists in providing the mechanization of the winding-insulating works, in decreasing the frame and increasing the reliability of the electric motor

01 Jul 1999
TL;DR: In this paper, a test to evaluate the impact of low-emissivity aluminum shields on the power use and thermal performance of a multi-deck display case typically used in supermarkets for storing dairy products was conducted.
Abstract: This paper discusses a test to evaluate the impact of lowemissivity aluminum shields on the power use and thermal performance of a multi-deck display case typically used in supermarkets for storing dairy products. The refrigerating system’s critical temperature and pressure points were tracked during the test, and the readings were then utilized to quantify various heat transfer and power-related parameters of the refrigeration cycle. It was found that using shields for extended hours of operation provides the most reduction in refrigeration load and power use.

Journal ArticleDOI
TL;DR: In this article, the influence of the material atomic number and the bremsstrahlung contribution to the examined spectra are also considered, with concrete, steel and lead single layer shields.

Journal ArticleDOI
TL;DR: In this paper, a simple design for a miniature cesium magnetometer intended for measuring the residual magnetic induction (B0≤1000 nT) in ferromagnetic shields of cylindrical shape with an internal diameter ⊘≥15 mm is described.
Abstract: A simple design for a miniature cesium magnetometer intended for measuring the residual magnetic induction (B0≤1000 nT) in ferromagnetic shields of cylindrical shape with an internal diameter ⊘≥15 mm is described.

Journal ArticleDOI
TL;DR: In this paper, the shielding effectiveness of an alternating magnetic field was studied experimentally and analytically by comparing shields made of grain-oriented silicon steel sheets with shields made by non-oriented silicon steel.
Abstract: The shielding effectiveness of an alternating magnetic field was studied experimentally and analytically by comparing shields made of grain-oriented silicon steel sheets with shields made of non-oriented silicon steel. Magnetic shielding in alternating fields became complex owing to anisotropic-frequency-dependent permeability and eddy currents. Shields with axes cross-stacked showed higher shielding effectiveness and isotropic distribution. The analytical results obtained by 3-D FEM showed some discrepancies with the experimental results.

Journal ArticleDOI
TL;DR: In this article, theoretical and experimental calculation of direct heat generation from the penetration of 6.12 MeV photons energy, emitted from an N-16 disk source, through double shielding layers combined of concrete, steel and lead shields is described.