70 results about "Vector potential" patented technology

In order to design on-chip interconnect structures in a flexible way, a CAD approach is advocated in three dimensions, describing high frequency effects such as current redistribution due to the skin-effect or eddy currents and the occurrence of slow-wave modes. The electromagnetic environment is described by a scalar electric potential and a magnetic vector potential. These potentials are not uniquely defined, and in order to obtain a consistent discretization scheme, a gauge-transformation field is introduced. The displacement current is taken into account to describe current redistribution and a small-signal analysis solution scheme is proposed based upon existing techniques for static fields in semiconductors. In addition methods and apparatus for refining the mesh used for numerical analysis is described.

Provided is an analytical method based permanent magnet motor field analysis and torque calculation method. The method comprises the following steps of: step 1: establishing a magnetic vector potential mathematical model of a gap zone and a permanent magnet region; step 2: establishing a magnetic vector potential mathematical model of a slot area; step 3: calculating a cogging torque; and step 4: analyzing and comparing an analytical calculating result. The invention provides an analytical method based permanent magnet motor field analysis and torque calculation method. According to the structural features of a surface mounted radially magnetized permanent magnet motor model, the analytical model is divided into three sub-regions, namely a permanent magnet region, a gap zone and a slot area; a magnetic vector Laplace equation or a Poisson equation is established in each region; sub-region equations are connected through junction conditions, so as to obtain the analytical expression of a load air gap field and a slot field by using a direct analytical method.

In this invention, an exciting unit applies, to a fluid, a time-changing magnetic field asymmetrical to a plane (PLN). An electrode is placed on the plane in a measuring tube, and detects a resultant electromotive force of an electromotive force based on a ∂A/∂t component (A: vector potential, t: time) irrelevant to a flow velocity of the fluid and an electromotive force based on a v×B component originating from the flow velocity of the fluid, the resultant electromotive force being generated by the magnetic field applied to the fluid and the flow of the fluid. A state quantifying unit extracts the ∂A/∂t component from the resultant electromotive force detected by the electrode, extracts, from the ∂A/∂t component, a variation factor dependent on a parameter to be detected, and quantifies the parameter on the basis of the variation factor. The parameter is at least one of a characteristic and state of the fluid and a state in the measuring tube. In this invention, the characteristic and state of the fluid and the state in the measuring tube can be detected regardless of the flow rate of the fluid by using the same hardware arrangement as that of an electromagnetic induction type flowmeter.

The present invention is a marine controlled source electromagnetic method finite element forward method of anisotropic media. The method comprises: firstly, setting a reference electrical conductivity, wherein three non-zero diagonal elements of the reference electrical conductivity are electrical conductivities in the direction of three main axes: x, y, z; next, setting three Euler rotation angles, and after three times of Euler rotation, obtaining an electrical conductivity tensor model in any direction; then starting from Maxwell equations, obtaining a finite element equation that is satisfied by magnetic vector potential and scalar potential under Coulomb regulations on a condition that the electrical conductivity presents anisotropy; then, performing discrete segmentation on a research region by using a non-structural grid, so that a complicated geoelectric model can be constructed; combining an incomplete LU discomposition pre-condition factor with an IDR(s) algorithm, so as to realize efficient and precise solution of a large sparse linear equation; and finally, deriving vector potential and scalar potential of a secondary field by using weighted moving least squares solution, to obtain each component of an electromagnetic field. The method provided by the present invention has excellent universality and can be promoted for electromagnetic method numerical value simulation with complicated electrical conductivity distribution and high precision.

The invention discloses a magnetic field analytic calculating method for a surface-mounted permanent magnet motor with a tilted trough structure and relates to the field of permanent magnet motor magnetic field calculating technologies. The magnetic field analytic calculating method comprises the following steps: a motor is axially divided into Nz sections of magnetic field solution domains in three-dimensional space, each section of magnetic field solution domain is divided into four sub-domains, the magnetic vector potential partial differential equations of the sub-domains of each section are built respectively, the general solutions of the sub-domains of each section solution domain are worked out by adopting the separation quantity method, and the boundary conditions among the sub-domains of each solution domain are built to determine fourier coefficient values; the definite expressions of the magnetic vector potential partial differential equations of the sub-domains, namely, the magnetic vector potential functions of the sub-domains, are worked out; air gap magnetic flux density expressions are calculated based on the magnetic vector potential functions of the sub-domains, and the magnetic linkage, the cogging torque, the counter emf and the electromagnetic torque of the motor can be further calculated. According to the invention, the magnetic field calculation and performance analysis of the surface-mounted permanent magnet motor provided with a stator tilted trough can be conducted rapidly and accurately.

A phase plate for an electron microscope in which a portion of a magnetic thin-wire ring or a magnetic thin-wire rod (15) spans an opening of a support member (14) having the opening, the magnetic thin-wire ring or magnetic thin-wire rod (15) generates a vector potential, and a phase difference is formed between electron beams that pass through left and right sides of a spanning portion of the magnetic thin-wire ring or the magnetic thin-wire rod (15). The phase plate prevents the electron beam loss more effectively, can be applied at an accelerating voltage within a wide rage from a low voltage to a high voltage, causes no difficulties in production, has good utility, and makes it possible to obtain a high-contrast image.

The invention discloses a method for calculating plane wave reflection coefficients in an elastic multi-layered medium. The method comprises the following steps: (1) if plane harmonic waves enter into a target layer series from a medium n+1, generating reflected longitudinal waves and reflected transverse waves in the n+1 medium, generating transmitted longitudinal waves and transmitted transverse waves in a medium 1, and writing each medium layer in a scalar potential form and a vector potential form; (2) determining relation among the displacement, stress and bit shift; (3) loading the scalar potential and vector potential of the step (1) into the step (2) to obtain a displacement and stress relation expression between the (n+1)th layer and the first layer; and (4) obtaining a displacement and stress transfer matrix containing elasticity coefficients of each layer according to the displacement and stress relation expression, which is obtained in the steps (3), between the (n+1)th layer and the first layer, solving, and obtaining reflection and transmission coefficients. According to the method, the influence of multiple waves and transformed waves of the elastic layer series as well as thickness and frequency on the reflection coefficient is considered fully, so that the method is applicable to thin-layer AVO (Amplitude Variation with Offset) analytical simulation and is high in calculation efficiency.

A system and method for numerically computing electromagnetic fields that is based on extremizing the action integral. The scalar and vector potentials are parameterized. The electromagnetic fields that result from those scalar and vector potentials are derived, and then the parameters are varied to extremize the action integral. In an embodiment, a Lagrangian density is constructed from the electromagnetic fields and potentials. The variation of the action integral is computed as a series of equations in which each equation is the result of taking a derivative of the action integral with respect to a parameter of a Lagrangian density. Solving for the values of the parameters yields the electromagnetic fields.

The invention discloses a method for calculating a signal-to-noise ratio (SNR) of a magnetic resonance imaging (MRI) RF coil, belonging to the technical field of magnetic resonance imaging (MRI), which is characterized by comprising the following steps: constructing an RF coil and a load size and material parameter model, listing integral equations satisfied by current densities, calculating skin depth and surface resistivity of a conductor and dissecting the conductor on the basis, converting the integral equations into algebraic equations, solving the algebraic equations to obtain current density distribution in the conductor, calculating magnetic flux density distribution in the load by using Biot-Savart integral, and adopting vector potential to obtain electric field strength distribution in the load, thus calculating self resistance, load eddy-current loss equivalent resistance and SNR of the RF coil. The invention improves the calculation efficiency of self resistance, load eddy-current loss and electric magnetic field space distribution of the conductor.

The invention provides an axial magnetic flux permanent magnet eddy current coupler electromagnetic torque analysis algorithm. The algorithm is characterized by firstly calculating the equivalent average magnetic conductivity [mu]eq of back iron of a conductor; determining the specific forms of various coefficients correlating with the number of times of harmonic n in field domain magnetic vector potential expressions of the conductor and the back iron thereof; then calculating an eddy current transverse effect correction factor k's; finally obtaining an electromagnetic torque value under the given air gap and slip ratio. The axial magnetic flux permanent magnet eddy current coupler electromagnetic torque analysis algorithm gives full consideration to the factor that the transverse effect correction factor changes with the speed (slip), the establish theoretical modeling is approximate to actual conditions, and permanent magnet eddy current coupler electromagnetic torques under various working conditions can be predicted accurately.

The invention discloses a resistivity reconstructing method by utilizing linear double curl equation to proceed magneto-thermo-acoustic imaging. The method includes the following steps: firstly, acquiring thermo-acoustic signals of conductive objects subjected to circular tomography; secondly, acquiring thermo-acoustic source distribution on an arbitrary fault surface of the conductive object by utilizing a time reversal algorithm according to an acoustic pressure wave equation of magneto-thermo-acoustics; thirdly, drawing forth a vector potential to assume an initial value of the resistivity of the conductive object through the current continuity theorem; fourthly, solving a vector potential spatial component with the initial value of the resistivity, and then substituting the solved spatial component of vector electric potential to the thermal-acoustic source distribution to acquire an updated conductivity distribution; fifthly, comparing the updated resistivity with a resistivity set with the initial value, checking whether a given relative error is met, if yes, confirming that the updated resistivity is the solved resistivity, if not, backing to the third step to perform iterating, and using the updated resistivity as an initial resistivity to further solve the updated resistivity, thereby acquiring the conductivity distribution of the conductive object.

A conductivity image reconstructing method for magneto-thermoacoustic coupled tomography includes: acquiring a thermoacoustic source distribution of a conductive object by means of time inversion according to an electromagnetic ultrasonic signal received, and performing reconstruction according to the thermoacoustic source distribution to obtain a conductivity distribution of the conductive object. Specially, the method includes: acquiring a thermoacoustic source on a certain level by means of time inversion, acquiring a thermoacoustic source of the conductive object by means of interpolation, performing calculation by means of Biot-Savart's law according to excitation current to obtain a spatial component A1 of primary magnetic vector potential, subjecting the conductive object to spatial discretization, giving an initial value [Sigma]<0> of conductivity, according to the theorem of current continuity, solving a spatial component [Phi] <1> of scalar potential with the initial value [Sigma]<0> and the spatial component A1, substituting the spatial component [Phi]<1> of the scalar potential to a relation which the thermoacoustic source and conductivity meet so as to obtain updated conductivity [Sigma]<1>, replacing the initial value [Sigma]<0> with the updated conductivity [Sigma]<1>, repeating the process above, and stopping iteration until a relative error of the conductivity meets an equation: Sigma=||([Sigma]1-[Sigma]0)/[Sigma]0||2<=Sigma0.

The invention discloses a semi-analytic calculation method for an eddy nondestructive testing magnetic field containing a column defect. According to the method, mathematical physics and electromagnetic field principles are utilized to obtain a precise analytic expression of magnetic vector potential under a Laplace domain, and numerical method inverse Laplace transformation is performed on a complex expression of a series form of the magnetic vector potential based on MATLAB to obtain a time-domain solution to an eddy nondestructive testing signal in a conductor containing the column defect. Through the method, the eddy nondestructive testing magnetic field of the conductor containing the column defect can be calculated accurately and efficiently, and a theoretical basis is provided for application of the eddy nondestructive testing technology in the defect quantitative recognition field.

Apparatuses and methods are provided for driving an input conductor with a signal comprising a series of voltage pulses. The pulses can beneficially invoke the skin effect to generate a time-varying magnetic vector potential that projects radially from a surface of the input conductor. The time-varying magnetic vector potential can provide an electric field for inducing output voltage pulses in an output circuit. The input conductor and output circuit can have various configurations. For example, the input conductor can extend along a plane, and the output circuit can at least partially reside in the plane and extend away from the input conductor in the plane. Such a geometry can reduce any back coupling between the two circuits, e.g., between electromagnetic fields caused by any current in the two circuits. Such a geometry would not normally allow for induction between the two circuits, which can reduce any Lenz effects.

The invention discloses a method of calculating the inductance of a reactor in an inter-turn short circuit fault state, comprising the following steps: S1, building a multi-layer multi-turn coil model of a dry hollow reactor; S2, building a method of calculating the total magnetic vector potential of the hollow reactor under the condition of no short-circuit turn; S3, calculating the total magnetic vector potential and coupling inductance at a short-circuited turn in the built model; S4, based on the Kirchhoff voltage balance equation, calculating the short-circuit current of the short-circuited turn according to the AC resistance of the short-circuited turn, the coupling inductance of the short-circuited turn and the inductance of the short-circuited turn; and S5, calculating the reverse flux caused by the short-circuited turn based on the short-circuit current of the short-circuited turn, calculating the total magnetic vector potential at a non-short-circuited turn through the method in S2 to get the flux of the non-short-circuited turn, and calculating the total inductance of the reactor according to the reverse flux of the short-circuited turn and the flux of the non-short-circuited turn. The weakening effect of the ring current in the short-circuited turn on the inductance of the reactor is considered. The calculation accuracy of the total inductance of the dry hollow reactor in a fault state is improved.