Showing papers on "Magneto published in 2006"

Magneto-science : magnetic field effects on materials: fundamentals and applications

Abstract: Fundamentals of Magnetic Field Effects- Effects of Magnetic Force- Effects of Lorentz Force and Magnetohydrodynamic Effects- Magneto-thermodynamic Effects- Magnetic Orientation- Dynamic Spin Chemistry- Novel Magnetic Field Effects

Boundary Element Method for Magneto Electro Elastic Laminates

Abstract: A boundary integral formulation and its numerical implementation are presented for the analysis of magneto electro elastic media. The problem is formulated by using a suitable set of generalized variables, namely the generalized displacements, which are comprised of mechanical displacements and electric and magnetic scalar potentials, and generalized tractions, that is mechanical tractions, electric displacement and magnetic induction. The governing boundary integral equation is obtained by generalizing the reciprocity theorem to the magneto electro elasticity. The fundamental solutions are calculated through a modified Lekhnitskii’s approach, reformulated in terms of generalized magnetoelectro-elastic displacements. To assess the reliability and effectiveness of the formulation, some numerical analyses have been carried out and the convergence of the method has been studied. The multidomain approach has been developed for the analysis of multilayered structures. Numerical results obtained show good agreement with those found in the literature. keyword: Magneto-electro-elastic materials; Boundary element method; Laminates modeling.

Discussion on electromagnetic crack face boundary conditions for the fracture mechanics of magneto-electro-elastic materials

Abstract: This paper discusses electromagnetic boundary conditions on crack faces in magneto- electroelastic materials, where piezoelectric, piezomagnetic and magnetoelectric effects are coupled. A notch of finite thickness in these materials is also addressed. Four idealized electromagnetic boundary conditions assumed for the crack-faces are separately investigated, i.e. (a) electrically and magnetically impermeable (crack-face), (b) electrically impermeable and magnetically permeable, (c) electrically permeable and magnetically impermeable, and (d) electrically and magnetically permeable. The influence of the notch thickness on important parameters, such as the field intensity factors, the energy release rate at the notch tips and the electromagnetic fields inside the notch, are studied and the results are obtained in closed-form. Results under different idealized electromagnetic boundary conditions on the crack-face are compared, and the applicability of these idealized assumptions is discussed.

Vector magneto-hysteresis E&S model and magnetic characteristic analysis

Abstract: This paper describes the utilization of two-dimensional vector magnetic property for the advanced magnetic field analysis which is called the magnetic characteristic analysis. There are some possibilities to develop new applications using the magnetic characteristic analysis and the vector magnetic property. This is due to the high density and the high efficiency of electric machines. It is very important to use the vector magnetic property in such cases

Magneto-resistive memory in ferromagnetic (Ga,Mn)As nanostructures

Abstract: We show a novel magneto-resistive effect that appears in lithographically shaped, three-arm nanostructure, fabricated from ferromagnetic (Ga,Mn)As layers. The effect, related to a rearrangement of magnetic domain walls between different pairs of arms in the structure, reveals as a dependence of zero-field resistance on the direction of previously applied magnetic field. This effect could allow designing devices with unique switching and memory properties.

Application of the magneto-optic Faraday effect in NDT

Abstract: A magneto-optic/eddy current imaging device is presented in this paper to detect invisible defects on the surface and at the subsurface of metallic specimens. The device combines a magnetic inductor to induce eddy currents in the structure under test with an optical set-up to image the resultant magnetic field, thanks to the magneto-optic Faraday effect occurring in a magnetic-optic film which the linear polarised light penetrates. Finally, the image is received by Charge Coupled Device (CCD) to realise visual non-destructive testing. In this paper, the operation principle and the set-up of the new system are described, and the experimental results are discussed, according to which the method presented is proved feasible to non-destructive testing.

A magneto sensor system and method of use

Abstract: Instruments, systems and methods for using the instrument and systems are disclosed, where the systems include a magneto sensor (208), such as a superconducting quantum interference device ('SQUID') and are designed to detect changes in a magnetic field in an animal including a human.

Magnetic field sensor for use in magneto resistive element, particularly four elements in bridge connection, has chip arranged on substrate or even formed on substrate

Abstract: The magnetic field sensor has a chip (50), which is arranged on the substrate (40) or even formed on the substrate. The magneto resistive element (41 to 44) has a hysteresis-afflicted characteristic and a magnetic current is detected by a magneto resistive element as a magnetic field signal. The magneto resistive element has a medium, by which the characteristic of the magneto resistive element is improved and hysteresis is reduced. The hysteresis-characteristics is reduced over the signal current by superimposed of a high frequency demagnetizing pulse.

Multi-Gap Superconductivity in MgB$_{2}$: Magneto-Raman Spectroscopy

Abstract: Abstract Electronic Raman scattering studies on MgB 2 single crystals as a function of excitation and polarization have revealed three distinct superconducting features: a clean gap below 37 cm −1 and two coherence peaks at 109 and 78 cm −1 which we identify as the superconducting gaps in π- and σ-bands and as the Leggett’s collective mode arising from the fluctuation in the relative phase between two superconducting condensates residing on corresponding bands. The temperature and field dependencies of the superconducting features have been established. A phononic Raman scattering study of the E 2g boron stretching mode anharmonicity and of superconductivity induced self-energy effects is presented. We show that anharmonic two phonon decay is mainly responsible for the unusually large linewidth of the E 2g mode. We observe ∼2.5% hardening of the E 2g phonon frequency upon cooling into the superconducting state and estimate the electron–phonon coupling strength associated with this renormalization.

Active write current adjustment for magneto-resistive random access memory

Abstract: In a method of programming a magneto resistive memory cell, a first magnetic field is applied to the magneto resistive memory cell. It is determined whether the magneto resistive memory cell meets a programming criterion. In case that the magneto resistive memory cell does not meet the programming criterion, a second magnetic field, which is higher or lower than the first magnetic field, is applied to the magneto resistive memory cell. It is then determined whether the magneto resistive memory cell meets a programming criterion. The magnetic field is increased or decreased in case that the magneto resistive memory cell does not meet the programming criterion until the magneto resistive memory cell meets the programming criterion.

Integrated Giant Magneto Resistors — a new Sensor Technology for Automotive Applications

Abstract: The paper will give an introduction to the principle of the giant magneto resistive — GMR — effect and the silicon system integration of GMR sensors. The two main applications of a GMR are as a magnetic field strength sensor and as an angular field direction sensor. They will be discussed under consideration of automotive requirements.

Design of New Intelligent Metal Detector

Abstract: A new excellent sensitivity metal detector based on eddy current of metal is introduced.It is used by traffic department for safety checking to travelers and their baggage,it also be used in construction to detect reinforcing bar,iron tube and soon.The sensor probe is composed of field coil and giant magneto resistive sensor.The input square wave pulse makes alternating magnetic field generated around the field coil.When approaching metal,magnetic field of the original field coil is changed because of the eddy current magnetic field generated from the metal.The changed magnetic field is transformed into electrical signal by the giant magneto resistive sensor centered in the field coil.The signal is processed and displayed under the control of single chip processor.

Coupled simulation of the thermo-magneto-mechanical properties of a Ni-Mn-Ga actuator

Abstract: A combination of different finite element (FEM) programs is used to simulate the coupled thermo-magneto- mechanical properties of a Ni-Mn-Ga double-beam cantilever. First, simulations of the static and dynamic temperature distributions are presented for different electrical heating conditions taking into account the effects of martensitic phase transformation. The results are used for a self-consistent mechanical deflection analysis of the actuator in the inhomogeneous magnetic field of a permanent magnet. The influence of the shape recovery, ferromagnetic and Lorentz force on the actuator performance are discussed.

Identification of the State of a Magneto-Fluidized Bed by Pressure Fluctuations

Abstract: Local instantaneous pressure signals obtained through a magneto-fluidized bed have been analyzed using both classical and advanced signal analysis methods, which can deliver the necessary information about the presence of the bubbling and turbulent flow pattern. The conventional signal processing tool such as autocorrelation and cross correlation were used as preliminary tools to analyze the data. Evaluation of the dominant bubble frequency was completed using the autocorrelation function and power spectral density function. Mutual information function was used to identify the periodicity and the predictability of the local instantaneous pressure signals. Since it does not demand any particular functional relationships between the data points, it is a better method (compared to autocorrelation function) for measuring the predictability of nonlinear systems.

Spark ignition debugging instrument

Abstract: The utility model discloses a spark ignition debugging apparatus, which comprises an SCM, wherein the SCM is used for identifying and processing a state signal of an engine and sending out an ignition signal; an external interruption interface of the SCM is connected with a magneto trigger signal acquisition module and a magneto illumination signal acquisition module; an input end of the magneto trigger signal acquisition module and an input end of the magneto illumination signal acquisition modular are respectively connected with a magneto signal output end of the engine which is debugged; a communication interface of the SCM is connected with an actual ignition angle signal acquisition module and an ignition driving module of the engine; an input end of the actual ignition angle signal acquisition module of the engine is connected with an output end of a high voltage bag of the engine which is debugged; the ignition driving module is connected with a direct current CDI device; an output end of the direct current CDI device is connected with the high voltage bag of the engine which is debugged. The utility model can arbitrarily set ignition advance angles of the engine under different rotating speed, can find out optimum ignition advance angles of different particular target values under different rotating speed and can lead the engine to work with the optimum ignition advance angle under the particular target value.

Magneto-optic remote sensor for angular rotation, linear displacements, and evaluation of surface deformations

Abstract: A system and method to detect angular rotation, linear displacement and/or surface deformations is presented. The method is based on the ability of a linear polarized light to interact with magnetic materials and to change its polarization angle due to Faraday effect. A basic structure of the system consists of a magneto-optic (MO) film with a two-domain structure and a single domain wall which are generated by gradient magnetic field produced by opposite polarity permanent magnets placed near the film. An AC magnetic field applied perpendicular to the MO film surface causes the magnetic domain wall in the MO film to oscillate at the same frequency. This leads to a detected output AC modulated signal. By measuring the temporal changes in this signal, information on angular rotation, linear displacement and/or surface deformation can be obtained.

Temperature Distribution of Power Transformer by Coupled Magneto-Fluid-Thermal Analysis

Abstract: This paper presents the temperature distribution of power transformer by coupled magneto-fluid-thermal analysis. Heat sources are calculated by magnetic field analysis. Temperature distribution is obtained by computational fluid dynamics algorithm considering the natural convection. The predicted temperature distribution of power transformer model shows good agreement with the experimental data

Irregular singularity of the magneto-rotational instability in a Keplerian disk.

Abstract: The center of a Keplerian disk is an irregular singularity for the eigenfunctions of magnetorotational instabilities. The system is studied using the small-radius approximation, which by no means implies that the analysis is valid only in the vicinity of the center of the astrophysical disks. In fact, the singularity has an effect on the entire disk and yields continuous eigenvalues (growth rates in the unstable regime and real frequencies in the stable regime) with rather intriguing implications for the non-Hermitian nature of the rotating plasmas. Through the Laplace transform, as well as numerical simulations, interesting long-term behavior of the instability has been found.

Magneto motive machine

Abstract: This invention relates to a magneto motive machine turning energy of a magnetic field to dynamic energy to output it for operation, in which, N and S poles of stator magnets are arrayed alternately and the magnetic fields of the multiple magnets are not influenced by each other. When the rotor magnets move to the dynamic zone, the direction of each rotor magnetic field is always parallel to that of the stator, in the resistance zone, the rotor magnets can turn over the pole orderly, therefore, the rotor can rotate both in the dynamic zone and the resistance zone to output power by its shaft.

Design of a Combined Passive and Active Magnetic Shield Adapted to Electrical Machines

Abstract: The paper deals with a method that makes it possible to design a shielding adapted to a given device. The method uses a field harmonic representation to identify the magneto dynamic multipoles associated to the studied device. This representation classifies the sources with respect to their main features : their amplitude, their associated decreasing law , their frequency nature. Then, depending on the required magnetic level, the classification indicates the multipoles to be suppressed. At this point, three possibilities are offered with the use of a passive , active, or combined shielding. Each kind of shielding presents advantages and drawbacks. Each of them has a particular effect on a given magneto dynamic multipole. As a consequence, it is possible to design the more adapted shielding with respect to magnetic specifications. A simple but didactic example using an electrical motor illustrates the method and the different shielding strategies.

V dual-cylinder magneto and ignition system using same

Abstract: The utility model discloses a V dual-cylinder magneto and an ignition system using the V dual-cylinder magneto. The V dual-cylinder magneto comprises the ignition system, a V dual-cylinder magneto, igniters, an ignition coil and a spark plug, wherein a convex block is arranged on a magnetic cylinder of the V dual-cylinder magneto, trigger coils of the V dual-cylinder magneto are respectively composed of two coil windings, and the igniters are two capacitive igniters. The two trigger coils of the V dual-cylinder magneto are respectively connected with the input ends of the two capacitive igniters. The output ends of the capacitive igniters are respectively connected with the input end of the ignition coil. The output end of the ignition coil is connected with the positive pole of the spark plug. The ignition system of the utility model uses the ordinary capacitive igniters, and the fabricating cost is reduced. In an abnormal condition, a dual-cylinder engine can work in a single-cylinder mode. Spark energy outputted by the igniters and the ignition coil of the ignition system is reduced, which leads the energy to be suitable for spark energy of mixed gas in the cylinder of the engine. The spark plug can not be easily damaged, and the failure rate is reduced.

Two-component matrix converter of magnetic field

Abstract: FIELD: the invention refers to measuring of inhomogeous fields in magnetic microscopy and tomography. ^ SUBSTANCE: the arrangement has a two-dimensional matrix of magneto sensitive ferromagnetic thin-film magneto resistors, an arrangement of their excitation, commutation and measuring. The lines of the matrix are covered with thin-film winding X, and the columns - with winding Y. The first ends of all windings are electrically connected up with a common wire, and the second are connected up correspondently to multi channel formers of current lines and columns. The magneto resistors are connected electrically successively and form diagonal lines so that each (I,j)-element is connected with (I+1, j+1) element. Some ends of the lines are linked up galvanically through resistance to a general wire, and others are attached to a multi channel current multiplexer. The arrangement has also preliminary and differential amplifiers, two schemes of selecting-storing and a microprocessor synchronization and control block. ^ EFFECT: matrix converter provides increase of accuracy in measuring two-component vector of tension of magnetic field without mechanical transfer. ^ 2 dwg

Electronic magnetor for high-handle chain saw

Abstract: The utility model provides an electronic magneto for a high handle chain saw. The utility model belongs to the technical field of a magneto. The utility model comprises a magnetic rotor, a magnetic steel, a balancing weight, stator iron cores, a high voltage package, a charge coil, a spark plug and an ignition control circuit, wherein the magnetic steel and the balancing weight are arranged on the wall at the inner side of the magnetic rotor, and the two stator iron cores are arranged on a chassis of a stator. A low voltage coil and a high voltage coil are coiled on the stator iron core at the same side together to form the high voltage package. The stator iron core at the other side is coiled with the charge coil. The ignition control circuit connected with the charge coil and the low voltage coil is arranged in the magnetic rotor. A flameout switch is connected with the charge coil and the ignition control circuit. The electronic magneto for a high handle chain saw of the utility model has the advantages of compact structure, simple and convenient installation, disassembly and maintenance, low cost, etc. Because a temperature control element is additionally arranged in the ignition control circuit, the ignition timing can not be influenced by the environment temperature, therefore the working performance of a chain saw is enhanced.