Showing papers on "Magneto published in 2003"

Studying magneto‐convection by numerical simulation

Abstract: Following a brief overview of the two main approaches to investigate the interaction between magnetic fields and convective flows near the solar surface layers by numerical simulation, namely idealized model problems and ‘realistic’ large-eddy simulations, we present first results obtained with a newly developed MHD code. The first example concerns the realistic simulation of the magnetic field dynamics in a solar plage region while the second example demonstrates small-scale dynamo action in idealized compressible convection.

Magnet topology optimization to reduce harmonics in high speed axial flux generators

Abstract: Despite the wide-ranging application potentials high-speed permanent magnet generators can offer the literature reveals a scarcity of design studies on these machines. This paper, we concerns with the configuration of PM on the quality of induced voltage in an ironless high-speed Axial Flux PM generator (AFPMG). The generator is a 240V eight-pole disc type machine with rated output of 18kVA at 50,000 rpm. It comprises of two rotor discs, each with eight embedded PM poles, and an ironless stator winding positioned between the rotors. A semi-circular shape is chosen for PM rotor poles, due to the ease of machining and assembly over other possible alternatives, and also their ability to produce near sinusoidal waveforms with various stator-winding shapes relatively easily. The investigation focuses on the effects on the harmonic content of the induced voltage due to varying distance between adjacent magnets. An efficient 3D finite element model (FE) that exploits the symmetry of machine is constructed for the proposed generator. The model then generates the predicted induced back emf over a range of distance between adjacent magnets, while maintaining the volume of the magnets constant. A prototype with the semi-circular magnets was constructed to provide experimental validation to the FE model. The validated model forms the basis for further formulation of design rules, and in particular, on the study of harmonics minimization.

Magneto resistive sensor applies pulsed test magnetic field from current carrying wire and obtains functional or fail or revised calibration signal

Abstract: A magneto resistive sensor (2) test system excites the sensor between expected measurements (b) with a known periodic magnetic field from a current carrying wire (8) and filters (a) and processes (5) this to give a functional or fail signal or new calibration transmitted to a central processor over a system bus.

Digital magneto-sensitive torque sensor

Abstract: A digital torque sensor employing a torsion bar, a target wheel at each end thereof, and at least two magnetosensitive (galvanomagnetic) sensors, in the form of magnetosensitive arrays, one for each target wheel, respectively, to precisely determine the angle of twist of the torsion bar. The torque sensor also provides target wheel relative position, rotational speed and rotational direction, and is capable of self-compensation over wide temperature ranges and air gaps, including tilts, does not require tight assembly tolerances and has a theoretically infinite life due to its non-contact nature.

Sensor and method for measuring a current of charged particles

Abstract: A current sensor (1) is disclosed for measuring a magnetic field (8) induced by a current of charged particles (3) having at least one magneto resistive sensor element (2;6;12;16) for enclosing the magnetic field induced by the current of charged particles, the magneto resistive sensor element being arranged perpendicularly to the current (3) during use. A method for accurately determining a current of charged particles is also disclosed making use of the current sensor (1). Further a protective switch device (30) is disclosed for protecting a user of an electrical device (31) by switching a supply current to the electric device off in case of malfunction of the electric device is also provided comprising the above current sensor (1).

Device for generation of a thermal flow of magneto-calorific material for industrial and household refrigeration applications

Abstract: A device for the generation of a thermal flow of magneto-calorific material comprises a thermal flow generation unit (30) provided with two thermal components (31) containing a magneto-calorific element (32), magnetic components (303) arranged to emit a magnetic field, displacement mechanisms coupled to the magnetic components to displace it with respect to the magneto-calorific elements in order to subject them to a variation of magnetic field in a manner made to vary with temperature and a system for the recuperation of heat and/or cold units emitted by the magneto-calorific elements. The displacement mechanisms are alternating and arranged to displace the magnetic components with respect to the magneto-calorific elements according to an alternating movement.

Modeling and signal processing of magneto-optic images for aviation applications

Abstract: Magneto-optic imaging (MOI) is a relatively new technology that produces analog images of magnetic flux leakage from surface and subsurface defects. An alternating current carrying foil serves as the excitation source and induces eddy currents in a conducting test specimen. Under normal conditions, the associated magnetic flux is tangential to specimen surface. Anomalies in the specimen result in generating a normal component of the magnetic flux density. The magneto-optic sensor produces a binary valued image of this anomalous magnetic field. The current system has two shortcomings. First, the presence of a textured background due to the domain structures in the sensor makes detection of third layer cracks and corrosion difficult. Second, the qualitative nature of the MO images does not provide a basis for making quantitative improvements to the MOI system. The availability of a theoretical model that can simulate the MOI system performance is extremely important for the optimization of the MOI sensor and hardware system. This paper presents a finite element model and its use in understanding the capabilities of the MOI system. In addition the paper also presents signal-processing methods for eliminating the background noise.

Magneto resistive film with smaller temperature coefficient of magneto resistive ratio

Abstract: PROBLEM TO BE SOLVED: To provide a magneto resistive film which is useable in an environment where a temperature change is large, and which has a smaller temperature coefficient of a magneto resistive ratio (MR ratio), and exhibits greater magneto resistive effect with the MR ratio of 5% or more, and further which has a higher electric resistivity of 10 4 μΩcm or more. SOLUTION: A magneto resistive film is represented by a general formula (Fe 1-a-b Co a Ni b ) 100-x-y-z M x O y F z , with M being a nano-granular thin film comprising an element of one kind or more selected from Be, Mg, Al, Si, Ca, Ti, V, Cr, Sr, Zr, Nb, Mo, Ba, Hf, Ta, W, and a rear earth element, and has a temperature coefficient of an MR ratio of ±500 ppm/°C within a temperature range of from -50 to +120°C, and further exhibits greater magneto resistive effect having the MR ratio of 5% or more together with an electric resistivity of 10 4 μΩcm or higher. COPYRIGHT: (C)2003,JPO

Finite element analysis of coupled magneto-thermal fields for compact busbar trunking system

Abstract: By using ANSYS software,this paper presents an in-direct coupled Finite Element Analysis(FEA)model for analyz-ing the harmonic magnetic field and steady thermal field of compact busbar trunking system.The power-frequency magnetic field,which takes eddy currents into account,is analyzed firstly.Then the decentralized Joule heat is coupled into the thermal field as heat generation rate.A predict-corrector method is used to guarantee the validity of predicted temperature rise of busbars and outer shielding,which has serious influence on the heat source and dissipation.Experimental values prove that this FEA model offers accurate results.The maximum error between the calculated and the experimental results is within1.2K.

Position determining device using magneto-resistance element

Abstract: The device has a magnet (41) projecting a bias magnetic field toward gear-teeth. A magnetic sensor has four magneto resistive unit bridges that are arranged between a rotor (31) and the magnet. A unit performs a multistage differential calculation from the outputs of the bridges and obtains a single differential output. The bridges produce outputs that vary according to a direction of the bias magnetic field.

Method for manufacture of magneto-resistive bit structure

Abstract: A magnetic bit structure for a magneto-resistive memory is disclosed that has bit ends that are sufficiently large to accommodate a minimum size contact or via hole. By providing such an arrangement, the magnetic bit structure may be fabricated using conventional contact and/or via processing steps. As such, the cost of manufacturing the device may be reduced, and the overall achievable yield may be increased.

Magnetorefractive Effect and Cubic Nonlinear Magneto-optics in Magnetic Granular Alloys

Abstract: We present a brief review of recent experimental and theoretical results on new magneto-optical phenomena in magnetic granular metal-insulator alloys with tunnel-type magnetoresistance, focusing on magnetorefractive effect and cubic nonlinear magneto-optics.

Magneto-thermal unit

Abstract: FIELD: power engineering; development of electrical energy generators and motors. SUBSTANCE: unit has shaft-mounted rotor with working members arranged over periphery, stator, heating-and-cooling system, and at least one magnetic system built of permanent magnets and magnetic shields integrated by magnetic circuit. Rotor is made in the form of turbine that has two disks, interconnected working members in the form of blades wholly or partially made of magnetically soft material possessing temperature-dependence properties. Permanent magnets are installed with opposite poles of working surfaces facing each other and interpole gap accommodating turbine blades. Heating-and-cooling system is fixed on shaft and made in the form of commutator assembly with guide ducts provided at their ends with nozzles for producing flow of heat and coolant and feeding them to running blades. EFFECT: enhanced specific and total power output. 6 cl, 5 dwg

Force sensing device having magnetized element and magneto electric material

Abstract: The present invention relates to a force sensing device, and in particular to a force sensing device for sensing an oscillating force or for application as a filter. In general terms, the invention proposes a force sensing device having a magneto electric material and a magnetic element moveable relative thereto in response to an applied force. The magneto electric material is exposed to the magnetic field of the magnetic element which has a magnetisation direction parallel to the direction of the movement.

Magneto-resistive device having magnetically soft reference

Abstract: A magneto-resistive device (10) includes first and second ferromagnetic layers (12 and 14) having different coercivities, and a spacer layer (16) between the first and second layers (12 and 14). Each ferromagnetic layer (12 and 14) has a magnetization that can be oriented in either of two directions.

Fault detector for component with conducting material has polarization circuit with electrical conductor close to magneto resistor

Abstract: The fault detector, comprising an electrical winding (3) fed by a variable current to create a magnetic field that penetrates the component being monitored and one or more magneto resistors (2) with axes of sensitivity parallel to one surface of the component, includes a polarization circuit with an electrical conductor (6) close to the magneto resistor(s). The fault detector, comprising an electrical winding (3) fed by a variable current to create a magnetic field that penetrates the component being monitored and one or more magneto resistors (2) with axes of sensitivity parallel to one surface of the component, includes a polarization circuit with an electrical conductor (6) close to the magneto resistor(s). The conductor lies parallel to the monitored surface and perpendicular to the magneto resistors' axes of sensitivity, and has a current passing through it to create a magnetic polarization in the magneto resistors so they function in a linear mode. The magneto resistor(s) lie on a supple substrate (5).