15 results about "Transverse magnetization" patented technology

A silicon-photonic optical modulator includes at least one optical input and at least one optical waveguide that is connected to the at least one optical input. The at least one optical waveguide is configured to propagate quasi-transverse-magnetic (quasi-TM) polarized light, where each of the at least one optical waveguide is configured as a rib waveguide that includes a rib arranged on a slab. The silicon-photonic optical modulator also includes at least one electrode configured to apply at least one electric field to the quasi-TM polarized light in the at least one optical waveguide. In some implementations, a height of the rib waveguide is greater than 0.85 λ / n, where λ is a free-space wavelength of light and n is a refractive index of silicon in the silicon-photonic optical modulator, and a width of the rib waveguide is greater than a thickness of the slab.

An echo planar imaging method capable of reducing image distortion is provided. Two radio frequency (RF) pulses α and β are used to respectively flip over a longitudinal magnetization into a transverse plane at different moments, so as to obtain observable transverse magnetization; the transverse magnetization obtained by flipping over the longitudinal magnetization by means of α and β are respectively rephased in two different echo trains by means of gradient pulses. Navigator echo signals are respectively collected before the two gradient echo trains, and the amplitude difference between two gradient echo train signals is corrected on the basis of the amplitude difference between the two navigator echo signals. Correcting the signals collected by the two gradient echo trains, so as to obtain two pieces of image data, and the two pieces of image data are averaged to obtain a final image.

The application discloses a kind of magnetic flux leakage testing device, including body, rotating assembly, detection component and tracking component, rotating assembly rotation is set on body and is used to rotate around steel pipe axis, detection component includes longitudinal magnetizer, transverse magnetizer and probe component, longitudinal magnetizer is set on rotating assembly, transverse magnetizer is set on body, both are spaced along steel pipe axial direction, to form longitudinal detection area and transverse detection area, probe component is set on rotating assembly, and respectively located longitudinal detection area and transverse detection area, tracking component includes rack and follow-up structure, probe component is installed on follow-up structure, follow-up structure is used to drive probe component to be close or far from the movement relative to steel pipe surface, probe component has at least one translational degree of freedom and / or at least one rotational degree of freedom relative to tracking component, to solve the technical problem that two direction defects are difficult to realize continuous, integrated detection in the same detection equipment in prior art.

The invention discloses a non-diagnostic method for selectively detecting glycine molecules in a mixed system based on magnetic resonance optimal control pulses, which is characterized in that the evolution of nuclear spin quantum states of mixed molecules including the glycine molecules is simultaneously controlled by utilizing broadband excited optimal control pulses; before and after the optimized pulse is applied, a magnetization vector of glycine molecule nuclear spinning is always in a z direction, and transverse magnetization vectors of other molecules are dispersed by applying gradient pulse, so that retention and selective detection of glycine magnetic resonance signals are realized. The method has a wide application scene.

Disclosed in the present invention are a 3D navigator-based 3D gradient spin-echo diffusion imaging method, and a device. The method comprises: first, using a global saturation module to destroy previous residual transverse magnetization; second, by means of a diffusion encoding module, embedding a pair of trapezoidal cosine oscillation gradients or pulse gradients into radio frequency pulses of 90°x-180°y-90°-x, and separating diffusion encoding from signal acquisition; then using a fat saturation module to suppress a fat signal; using a 3D gradient spin-echo readout method to acquire an image signal; and finally, acquiring a 3D navigation echo signal in the last spin echo for correcting a phase error between multiple excitations. The present invention can effectively eliminate phase errors between multiple acquisitions and realize high-resolution whole-brain diffusion imaging. Compared with 2D echo planar imaging, the present invention increases the signal-to-noise ratio of diffusion magnetic resonance imaging, thereby supporting higher-resolution whole-brain 3D diffusion magnetic resonance imaging.

A method and a magnetic resonance imaging (MRI) system improve an MRI signal from a magnetization of interest. The method includes performing an MRI pulse sequence containing three consecutive radio frequency (RF) elements, namely, a first element that is an inversion-recovery pulse sequence characterized by a time of inversion, a second element that is an image-encoding pulse sequence starting at the time of inversion with an excitation RF pulse followed by an image-encoding gradient and a data sampling. The second element is followed by a third element. An MRI signal generated by the object and sampled by image readout blocks applied to the object by the MRI system during each repetition time, is acquired. From the MRI signal, an image of the object is reconstructed. The third element is a modified driven-equilibrium (mDE) pulse sequence configured for achieving a conversion of a transverse magnetization component.

This invention belongs to the field of pipeline internal inspection technology and aims to solve the problems of large errors and low accuracy in the internal inspection of magnetic pipeline defects in existing technologies. Specifically, it involves a magnetic field gradient compensation method for a transverse excitation detector. Based on a selected pipeline segment, artificial defects are created; the pipeline segment is magnetized using a transverse excitation detector; defect signals of pit-like defects, general defects, axial grooves, and axial concave grooves are collected using the probe of the transverse excitation detector and a static experimental platform to obtain signal relationship diagrams of different types of defects and different positions in the pipeline; based on the defect signal diagrams at different positions of the magnetized field, a reverse compensation model is established to correct the non-uniformity in the transverse magnetization process, and a baseline correction model is obtained; based on the baseline correction model, a sensitivity compensation model is established, and a compensation coefficient is used to correct the sensitivity difference, resulting in a sensitivity compensation model. This invention can effectively reduce the influence of the spatial location of defects on the leakage magnetic field and improve the accuracy of defect quantification.

The present application discloses a magnetic resonance non-contrast angiography method, apparatus and computer device, which relate to the field of medical imaging technology and can improve the diagnostic value of magnetic resonance angiography. The method includes: applying a combined pulse to the region to be imaged based on the non-selective water excitation pulse in the modified T2 magnetization preparation module, controlling the longitudinal magnetization vector of the fat signal to be opposite to the direction of the main magnetic field, and the direction of the longitudinal magnetization vector of the water signal to be the same as the direction of the main magnetic field, so as to obtain water signals with different transverse magnetization vectors, where the water signals include arterial signals and venous signals; using a three-dimensional fast gradient echo sequence to perform signal acquisition to obtain water signals corresponding to multiple echo time points; and obtaining a non-contrast angiography image containing at least arterial characteristics and venous characteristics according to the water signals corresponding to multiple echo time points. The present application is applicable to large-range angiography based on non-contrast-enhanced magnetic resonance.

Methods, apparatus, and storage medium for enhancing diffusion-weighted magnetic resonance imaging (MRI) by using steady-state free procession (SSFP) of ultra-short echo time (UTE) and UTE-based magnetization transfer MRI. One method includes, for each of a plurality of data acquisition sequences: for each of a plurality of data acquisition sequences: applying a set of radio-frequency (RF) pulses to interact with transverse magnetization within an imaging volume of an object in a magnetic field, applying a three-dimension (3D) magnetic gradient within the imaging volume, wherein the 3D magnetic gradient comprises a 3D spiral pulse, and acquiring, during the 3D spiral pulse, raw imaging data from the imaging volume; and constructing a raw MRI image based on the raw imaging data acquired from the plurality of data acquisition sequences.

The application provides a magnetic flux reverse type axial flux motor, which comprises a first stator, a second stator and a rotor, the first stator and the second stator comprise a stator core, a permanent magnet and an armature winding, the permanent magnet is composed of an axial magnetization permanent magnet and a transverse magnetization permanent magnet, and is embedded into the stator core tooth top in an alternating pole mode, the aggregation of permanent magnet flux is realized, and the back electromotive force waveform is improved. The rotor comprises a first rotor core, a second rotor core and a magnetic separation disc, the rotor core is laminated by silicon steel sheets, the first rotor core and the second rotor core are opposite to the first stator and the second stator respectively, and an air gap surface is arranged between the opposite rotor core and the stator, and the magnetic separation disc realizes the decoupling of the double air gap magnetic circuit. The first stator and the second rotor core are arranged in a staggered mode with the second stator and the second rotor core to offset part of the cogging torque and reduce the torque ripple.

Method for operating a magnetic resonance tomograph for spatially resolved spin resonance measurement of an object, in particular a living object, which is arranged in a static magnetic field B0, whereby an alignment of the object's spins and a longitudinal net magnetization Mz along the direction Z of the static magnetic field results, and wherein a transverse magnetization component Mxy is generated or changed, in particular by generating a spin flip from the Z direction by a desired flip angle, in particular by 90 degrees, by means of at least one high-frequency excitation pulse (1) in spin resonance, wherein spin echo signals from at least one desired volume element of the object are measured using a sequence of high-frequency pulses (4, 5, 7) and switched gradient magnetic fields (2, 3, 6).wherein the at least one volume element is determined by several gradient magnetic fields superimposed at least temporarily on the homogeneous magnetic field B0, wherein the sequence of high-frequency pulses comprises a first (4) and a second high-frequency rephasing pulse (5), in particular a first (4) and second high-frequency rephasing pulse (5) directly after the generation of a transverse magnetization component by means of a high-frequency excitation pulse (1), wherein from the second high-frequency rephasing pulse (5) onwards both a spin echo and a stimulated echo are generated, wherein in addition to a gradient magnetic field (6) in the frequency coding direction, which is switched on during the measurement acquisition to acquire a line of the raw data space, an additional gradient magnetic field (8) in the frequency coding direction is switched on, which generates echo signals or echo signal components newly generated by the high-frequency rephasing pulses (5, 7),in particular, those not attributable to a refocusing of the original spin echo after the first radio frequency rephasing pulse (4) and / or of the original stimulated echo after the second radio frequency rephasing pulse (5), are shifted out of the raw data space or raw data line acquired in a subsequent measurement, characterized in that, during an evolution time (Tau) between the first (4) and second radio frequency rephasing pulse (5), T2*-induced relaxation processes act on a transverse magnetization component present after the first radio frequency rephasing pulse (4), and a magnetization component present in the longitudinal direction after the first radio frequency rephasing pulse (4) remains unaffected, wherein the absolute time between the first (4) and second radio frequency rephasing pulse (5) is extended by the evolution time beyond the duration of an echo interval,which is present between subsequent equidistant high-frequency rephasing pulses (5, 7).

The application relates to a magnetic resonance image generation method and device, computer equipment and a storage medium. The method comprises the following steps: in a target cardiac cycle, a preparation module is applied in response to receiving an electrocardio trigger signal to flip a first initial longitudinal magnetization vector corresponding to a detection object into a first transverse magnetization vector and to scatter into a first vector value; an inversion recovery pulse is applied in response to reaching a vector recovery time after the preparation module is applied; magnetic resonance data of the detection object is acquired by using a target imaging sequence in response to reaching an inversion recovery time after the inversion recovery pulse is applied; and the magnetic resonance data is reconstructed to obtain a target magnetic resonance image of the detection object. The method ensures that the longitudinal magnetization vector corresponding to the detection object is recovered from the first vector value to the signal strength of the vector recovery time before the inversion recovery pulse is applied at the interval vector recovery time, so that the longitudinal magnetization vectors corresponding to the detection object are all the same, and the quality of the magnetic resonance image is improved.

The application discloses a 3D gradient spin echo diffusion imaging method and device based on a 3D navigator. The method first destroys previous residual transverse magnetization in a global saturation module; secondly, a pair of trapezoidal cosine oscillation gradients or pulse gradients are embedded into 90° x -180° y -90° ‑x RF pulses to separate diffusion encoding from signal acquisition; then, a fat saturation module is used to suppress fat signals; then, a 3D gradient spin echo readout mode is used to acquire image signals; finally, 3D navigator echo signals are acquired in the last spin echo to correct phase errors between multiple excitations. The application can effectively eliminate phase errors between multi-section acquisitions and realize high-resolution diffusion imaging of the whole brain. Compared with 2D planar echo imaging, the application improves the signal-to-noise ratio of diffusion magnetic resonance imaging, thereby supporting higher-resolution whole brain 3D diffusion magnetic resonance imaging.

The invention discloses a system and a method for measuring a three-dimensional magnetic field by using an integrated micro-ring device, and belongs to the technical field of optical fiber sensing and magnetic field measurement. The system comprises a light source, a transmission straight waveguide, a polarization controller, a 1: 2 type Y waveguide, two sensing micro-rings (built-in magneto-optical waveguides) perpendicular to each other and a photoelectric detector. According to the invention, by using the asymmetry of the magneto-optical waveguide in the horizontal / vertical direction, transverse magnetization respectively changes TE / TM mode propagation constants; the x / y-axis magnetic field and the z / y-axis magnetic field are sensed through the two micro-rings respectively, and a three-dimensional magnetic field is obtained through simultaneous operation. The device is high in integration level, small in size, simple in process and high in environmental adaptability, and has practical value. According to the invention, each micro-ring measuring device is integrated on a single chip, the integration level is relatively high, the size is small, the process is relatively simple, and the method has relatively high environmental adaptability and practical value.

The present invention relates to the technical field of electric motors, and in particular to a magnetic flux leakage prevention rotor and a disc-type electric motor. The magnetic flux leakage prevention rotor comprises: a main body and a plurality of magnetic members, which are arranged on the main body, wherein by using the center of the main body as the center of a circle, the plurality of magnetic members are distributed on the main body in a ring array, and the magnetic directions of two ends of the magnetic member are parallel to the movement direction of the main body; the main body is provided with a first surface and a second surface, and the plurality of magnetic members are arranged on the first surface; the second surface is provided with a leakage prevention structure, the first surface is configured to face an electromagnetic structure of a stator, and the leakage prevention structure is configured to prevent escape of magnetic field lines of the magnetic members when the magnetic field of the electromagnetic structure is increased; and the leakage prevention structure is prepared by means of transverse magnetization. In the present invention, the leakage prevention structure is arranged on the surface of the rotor facing away from the stator of the electromagnetic structure, and the magnetic field is also arranged on the surface of the rotor facing away from the electromagnetic structure of the stator by means of the leakage prevention structure, such that when the alternating magnetic field of the electromagnetic structure is suddenly increased, magnetic lines of force of the rotor cannot escape, thereby ensuring the normal operation of the electric motor.