Showing papers on "Shields published in 2004"

Numerical analysis of magnetic shielding efficiency of multilayered screens

Abstract: An extension of the thin shell formulation for the analysis of the shielding efficiency of multilayered passive shields is presented in the paper. After a validation of the proposed approach by comparison with analytical results in the case of a cylindrical shield placed in a uniform field, the model is applied to the analysis of shielding configurations of practical interest.

Application of Electrically Conductive Textiles as Electromagnetic Shields in Physiotherapy

Abstract: The technology of electrically conductive fibre production has been devised at the Textile Research Institute (Łodź, Poland), and has patent protection in Europe and the USA. Elec-trically conductive nonwovens (stitch-bonded and needled) made from these fibres differ from each other not only in production technology, but also in electric properties. Measu-ring the shielding effectiveness of these fabrics proved a possibility of their application as electromagnetic shields. Their practical application was presented for physiotherapy where short-wave and microwave diathermy is used. Key words: electro-conductive textiles, electromagnetic shields, physiotherapy. and considerably lower cost, in compari-son with shields made of metal sheets and wire mesh.Materials of high electrical conductance can act as electromagnetic field shields only in the range of higher frequencies (>300 MHz). In practice, in this case they equally attenuate the electric component E as well as the magnetic component H. For fields of frequency <30 MHz, at-tenuation of the magnetic component H is very difficult, and is possible only thanks to the use of ferromagnetic materials. For some applications, only the attenuation of the electric component E is satisfactory. Fabrics made of Nitril-Static (PAN fibres modified by Cu

Performance optimization of critical nets through active shielding

Abstract: We propose the concept of active shields-shields that switch concurrently with a signal wire of interest. Active shields aid signal transitions through the coupling between the signal wire and shields. For RC dominated wires, the active shields switch in the same phase as the signal wire since capacitive coupling is the dominant coupling mechanism. For wires with dominant inductive coupling, active shields switch in the opposite phase of the signal wire. We show that under fixed area and input capacitance constraints, in-phase active shielding outperforms traditional (passive) shielding and wire sizing/spacing techniques for minimizing delays and transition times on RC-dominated wires. For RLC wires, we demonstrate a region of feasibility (in terms of signal wire widths) for which opposite-phase active shielding outperforms the passive shielding technique. Opposite-phase active shielding suppresses ringing behavior to a greater degree than passive shields, providing similar performance to differential signaling while maintaining the simplicity of single ended signaling. The benefits of opposite-phase active shielding as compared to passive shielding are shown in the context of various clock net optimizations where reductions in ringing behavior (up to 4.5X) and transition times (up to 40% reduction) are achieved.

Non-contact capacitive sensor and cable with dual layer active shield

Abstract: A non-contact capacitive sensor probe including a metallic sensor having a first surface opposite a dielectric medium to be sensed; a plurality of active metallic shields adjacent to the metallic sensor, each of the active metallic shields having a pattern of grooves inhibiting eddy currents on a surface of the shield, wherein the pattern on one shield does not overlap with the pattern on a second shield, and a passive metallic shield adjacent the active metallic shields, such that active metallic shields are sandwiched between the metallic sensor and the passive metallic shield.

Apparatus and method for fluid flow measurement with sensor shielding

Abstract: Methods and apparatuses for detecting radial flows of conductive fluid are provided. In an embodiment of the present invention, shields are used to prevent or reduce circulating electrical currents from causing a voltage difference that would adversely affect the measured voltage difference between two adjacent electrodes. The shields may be a conduit through which conductive fluid may flow. Groups of sensors, e.g., two or more, may be placed within the shield. The shields may have any cross-section shape. Generally, once the circulating electrical current flow between the electrode pairs is substantially reduced or eliminated, only the voltage difference from the localized induced electric field remains. This way, a true induced voltage may be measured, and thus an accurate value for the fluid velocity may be determined.

A simple hybrid method for ELF shielding by imperfect finite planar shields

Abstract: A simple method is described for calculating the shielding performance of a two-dimensional (2-D) thin finite-width shield made of imperfect material in the presence of the magnetic field from line source conductors. First, solutions to two canonical problems with closed-form simple analytic formulas are presented; shielding by reflection from and absorption in thin planar shields of infinite extent and shielding by perfect conductor shields of finite width. Then the method for calculation of magnetic-field shielding by perfect conductor finite-width shields is extended using the simple interpolation method, to thick shields made of imperfect material. Finally, the hybrid solution is developed by adding the two results in quadrature. The result is a simple theory for shielding by finite-width shields made of any real shielding material of arbitrary thickness. Its accuracy has been validated by comparison to finite-element method solutions and existing measurements.

Photosensitive thick-film paste materials for forming light-transmitting electromagnetic shields, light-transmitting electromagnetic shields formed using the same, and method of manufacture thereof

Abstract: The present invention relates to light-transmitting electromagnetic shields which, when installed at the front of displays such as plasma display panels (PDP), cathode-ray tubes (CRT) or electroluminescent (EL) displays, have electromagnetic shielding properties that cut down on the emission of electromagnetic waves, have a high visible light transmittance, lower the reflectance to outside light, and have a good durability.

Finite magnetic shields effect on the transport current in superconductor strips

Abstract: The effect of finite magnetic shields on the current distribution and voltage in superconductor strips is studied theoretically and experimentally. It is found that the reduction of the edge current peaks due to the magnetic shields saturates fast when the thickness of the shields is increased. This enables the use of thin magnets for shielding provided that the small thickness of the shields is compensated by high magnetic permeability. The effect of soft magnets (ferrites) on the current–voltage characteristics in the YBCO strip is studied experimentally for different strip-magnet arrangements and compared to the theory predictions.

Adjustable windrower shields

Abstract: Windrow shields that pivot adjacent the forward ends thereof into and out of the path of crop material to control the width of the windrow. An electric motor and linkage to the shields allows the special relationship between the shields to be adjusted on-the-go from the operator's location.

Improvement of MERCURE-6's General Formalism for Calculating Gamma-Ray Buildup Factors in Multilayer Shields

Abstract: This study proposes an improvement of the general formalism for calculating gamma-ray buildup factors in multilayer shields developed by Assad et al. The main modification concerns the treatment of the double-layer shield formed by the two first layers of a multilayer shield. Instead of replacing the double-layer shield with an equivalent thickness of the layer of the second material, the improved general formalism replaces it with a single-layer shield made of an appropriate material. The determination of the appropriate material is implemented into MERCURE-6.1 thanks to neural networks trained on a large set of various configurations.One-dimensional comparisons with the TWODANT transport S{sub n} code shows the accuracy of the new formalism for shields composed of three and five layers. Indeed, for three-layer shields with an infinitesimal second layer and for multilayer shields composed of numerous thin layers (more than 15), MERCURE-6.1 matches the reference data quite well. The MERCURE-6.1 ability to solve three-dimensional realistic cases is highlighted by comparisons to the TRIPOLI-4 and MCNP-4C Monte Carlo codes.

Strippable semiconductive shield and compositions therefor

Abstract: This invention is generally directed to semi-conductive power cable shields, cables with such shield and compositions for making such shields. The semi-conductive shields are strippable from power cable insulation, resistant to thermal aging, have improved processability during cable extrusion and include little or no butyl nitrile rubber (NBR).

Shield for wheel assemblies

Abstract: A shield for wheel assemblies formed of a metal band that is inserted into wheels so as to cover and protect the inner surface of the wheels. The shields can be made from stainless steel and used to protect the inner surfaces of aluminum from damage caused by debris that contact a vehicle braking assembly. The shields are secured in the wheels by a mechanical locking arrangement in which the outer ends of the shields snap-fit along outboard rim flanges of the wheels. Adhesives or sealants can be used to secure the shields to the wheels and to prevent moisture and debris from becoming trapped between the shields and inner surfaces of the wheels.

Split ring casting for boiler tubes with protective shields

Abstract: A series of upright boiler tubes periodically exposed to the abrasive action of a stream of blowing fluid cleaning medium. Vertically spaced shields mounted on the boiler tubes for protection from the fluid cleaning medium. A split ring casting located between the protective shields to maintain the boiler tubes in an aligned and fixed spaced relationship. The split ring casting is sized to overlap adjacent portions of the protective shields thereby covering any gaps exposing the boiler tubes to the action of the fluid cleaning medium.

Method and apparatus for forming polycrystalline layer using laser crystallization

Abstract: A method and an apparatus for forming a polycrystalline layer using laser annealing for preventing damage to the peripheral region of the substrate during laser annealing. The laser annealing comprises a shadow mask structure. When crystallizing an amorphous layer by laser annealing, the shadow mask structure shields the peripheral region of the amorphous layer from laser irradiation. A method for forming a polycrystalline layer using the laser annealing apparatus is also provided in the invention.

Lithography equipment, method of manufacturing device, and device manufactured thereby

Abstract: PROBLEM TO BE SOLVED: To provide lithography equipment which makes temperature stability of a projection system surer by active heat transport, while minimizing impact of mechanical vibration by the heat transport. SOLUTION: In the lithography projection equipment, the projection system comprises one or more optical operating mirrors, and a heat shield which shields heat emission to the mirrors and/or a supporting structure of the mirrors or from the mirrors and/or the supporting structure of the mirrors. Although the heat shield is cooled compulsorily, as the mirrors and the heat shield are supported separately by a supporting frame, vibration of the mirrors by forced cooling is reduced. Preferably, the heat shield includes a heat shield which shields heat emission to the mirrors or from the mirrors, and shields heat emission to heat shields and/or supporting structures for individual mirrors or from the heat shields and/or the supporting structures. COPYRIGHT: (C)2005,JPO&NCIPI

Hypervelocity Impact Analysis of International Space Station Whipple and Enhanced Stuffed Whipple Shields

Abstract: : The International Space Station (ISS) must be able to withstand the hypervelocity impacts of micrometeoroids and orbital debris that strike its many surfaces. In order to design and implement shielding which will prevent hull penetration or other operational losses, NASA must first model the orbital debris and micrometeoroid environment. Based upon this environment, special multi-stage shields called Whipple and Enhanced Stuffed Whipple Shields are developed and implemented to protect the ISS surfaces. Ballistic limit curves that establish shield failure criteria are determined via ground testing. These curves are functions of material strength, shield spacing, projectile size, shape and density, as well as a number of other variables. The combination of debris models and ballistic limit equations allows NASA to model risk to the ISS using a hydrocode called BUMPER. This thesis modifies and refines existing ballistic limit equations for U.S. Laboratory Module shields to account for the effects of the projectile (debris/ micro-meteoroid) densities. Using these refined ballistic limit equations this thesis also examines alternative shielding materials and configurations to optimize shield design for minimum mass and maximum stopping potential, proposing alternate shield designs for future NASA ground testing. A final goal of this thesis is to provide the Department of Defense a background in satellite shield theory and design in order to improve protection against micrometeoroid and orbital debris impacts on future space-based national systems.

Anti-vibration bars for boiler tubes with protective shields

Abstract: A bank of horizontally oriented boiler tubes which are periodically exposed to the abrasive action of a stream of blowing fluid cleaning medium. Portions of the boiler tubes, located at the top of the bank, are provided with spaced shields for protection from the fluid cleaning medium. An anti-vibration bar extends vertically between the protective shields to suppress vibration of the boiler tubes. A cap is fitted over the top end of the anti-vibration bar. The cap is sized to overlap adjacent portions of the protective shields thereby covering any gaps between the anti-vibration bar and the shields that would expose the boiler tubes to the action of the fluid cleaning medium.

Magnetic Shields for Underground Power Lines

Abstract: This paper describes a simple method for shielding the magnetic fields generated by underground power lines. It consists on placing a cylindrical shell made of a ferromagnetic material. The principle for reducing the magnetic field outside the shield is that the ferromagnetic material absorbs the magnetic field generated by the buried power line and only a very small portion of the magnetic field survives outside the shield. As the shield is made of a high-conductivity ferromagnetic material, eddy currents are induced inside it and they generate a magnetic field opposed to the magnetic field generated by the power line. It results that the total magnetic field H inside the shield is reduced. It is well known that the relative magnetic permeability of ferromagnetic materials decreases sharply when magnetic fields intensities H are very weak (below 0,1 A/m) and when they are very strong (due to saturation phenomena). In these situations the shielding efficiency of these materials is dramatically reduced. The selection of an adequate material to act as a magnetic field is decisive. Such a material must have a high magnetic permeability when dealing with very weak magnetic fields and a high electric conductivity in order to maximize the absorption losses. For these reasons the selected material has been the purified iron (at least 99’95 % pureness).

Method for making shielded capacitor structure

Abstract: A method and apparatus if provided for shielding a capacitor structure formed in a semiconductor device. In a capacitor formed in an integrated circuit, one or more shields are disposed around layers of conductive strips to shield the capacitor. The shields confine the electric fields between the limits of the shields.

Resistance heater and resistance furnace using same

Abstract: Each non-linear insulating space (6a,6b) is formed between thermal shields (4a1,4a2,4b1,4b2) extended integrally from each of two terminals (3a,3b) at the outer periphery of a cylindrical heating portion (2). An independent claim is also included for an electric resistance furnace.

Paint shields for light fixtures

Abstract: Paint shields formed from relatively stiff but pliable material are configured to cover the transparent or translucent lenses of light fixtures so that frames of the fixtures which extend perimetrically about the lenses can be painted by brush, by roller or by spray without getting paint on the lenses. Edge regions of the paint shields are configured to be inserted between the frames and the lenses, and central regions of the paint shields preferably are transparent or translucent to permit light from the fixtures to pass through the installed paint shields. Peripheral regions of the shields preferably are provided with visible guide formations or may be scored or perforated to facilitate trimming the shields to fit small and undersized fixtures. Central portions may be designed to fold away from other portions of the shields to stiffen the installed shields to minimize sagging.

Recording/reproducing separation type head

Abstract: PROBLEM TO BE SOLVED: To provide a recording/reproducing separate type head eliminating contact between the head and a disk by suppressing the temperature rise of the head in a manner of efficiently radiating the heat generation of the head itself to a substrate and thereby reducing the deforming amount of the head. SOLUTION: The forming area of an insulation film 2 on the substrate 1 is limited to the vicinity of a GMR film 5. By this arrangement, Joule heat generated by a coil 12 is introduced to the substrate 1 without being interrupted by the insulation film 2. An electrode 6 formed in the middle part, upper and lower shields 8, 3, and a lower magnetic pole 10 are formed of metal thin films each having high thermal conduction, and are little affected by heat. Similarly, gap films 4, 7, and 11 in the middle part and a separation film 9 are formed of Al 2 O 3 being electrical insulation films, but are not largely affected by the heat since they are thin. COPYRIGHT: (C)2004,JPO

Method for extraction of kimberlite pipe under elastic shields

Abstract: FIELD: mining industry. ^ SUBSTANCE: method includes dividing ore body on levels, and levels on blocks, driving ventilation and passing mines and ore chutes, mounting elastic shields in blocks, extraction of ore in blocks in horizontal layers with forming of trench and leaving support blocks along trench boards for support of elastic shields, transportation of ore under elastic shields, following extraction of ore from support blocks with concurrent placement of elastic shields and its delivery. Ventilation-pass mines and ore chutes pass along ends of blocks in enveloping empty rocks, extraction of ore in block during forming of trench is performed by combine, and from support blocks with concurrent placement of elastic shields - by mechanized complex. Between trench soil and elastic shield a ventilation channel is formed, which is connected to ventilation-pass mines. Ore is transported by conveyor, mounted in trench. ^ EFFECT: higher effectiveness, higher safety. ^ 9 dwg

Optimization design for shields of vacuum interrupter

Abstract: The shields of vacuum interrupter play an important role in absorbing the metal vapor and uniforming the electric field distribution. Thus, the breaking and closing performances of vacuum circuit breaker arc much influenced by the shields. In this paper, a 12kV vacuum interrupter has been taken as the investigation object, the Emax the size, shape, location of the shields have been chosen as the objective function and optimization variables respectively. The optimization design is performed by solving the inverse electric field problem using the simulated annealing optimization strategy. The optimum size, shape and location of the shields to be designed are obtained. By comparing with present 12kV vacuum interrupter, it shows that a modern design technique for the shields of vacuum interrupter is provided in this paper.