235 results about "Uniform field" patented technology

A framework encloses a stepper motor, mounting structure, and circuitry for use in calibrating the responses of utility locators or the precise frequency outputs of locating transmitters, and associated tilt, directional, angle, and gradient sensors. The framework contains two Helmholtz or similar field windings embedded in its sides to achieve maximum accuracy in calibration of locating instruments, such that a locator may be precisely situated within the uniform field of the windings for calibration measurement or testing. Calibration and testing may be done manually or by automated means.

An arrangement, for use in whitening a patient's teeth includes an arched surface and an array of light-generating devices, for example, light emitting diodes positioned on the arched surface. The light-generating devices are arranged to form a relatively uniform field of light in a particular range of wavelengths, and further arranged to focus the generated light in an overlapping manner onto a patient's teeth when the mouthpiece is properly positioned relative to the patient's face. The proper positioning is aided by a number of light sources, in the visible range, that shine on the patient's face in a predetermined manner when the mouthpiece is properly positioned. To remove whatever heat is generated at the surface of the patient's teeth in the course of the procedure, the mouthpiece includes air passages between the light emitting devices, and a fan that draws air away from the patient's face.

The invention discloses a method and a device for detecting tissue boundaries by use of ultrasonic images. The method comprises a search step and a detection step, wherein the search step is used for searching an ultrasonic image of a detection target for an initial center point of a target region and determining an initial region boundary curve according to the initial center point; the detection step takes the initial center point as a pole, starts searching for the position of a target region boundary along a polar line passing the pole from an initial region boundary, and calculates the energy functional of gray-scale distribution in different positions, wherein a position corresponding to the minimum value of the energy functional of gray-scale distribution is the boundary of the target region. As the invention first detects the center point and then rapidly detects the boundaries along the polar line, the invention is simpler and rapider in detection. Region segmentation functional adopted in the invention can effectively avoid the influence of ultrasonic image noise and effectively detects weak boundaries. In addition, grey scale correction along the polar line can eliminate the influence of non-uniform fields of image gray-scale distribution.

Bender devices are demonstrated by developing non-uniform fields within a homogeneous, non-planar single slab active member material of non-uniform thickness through geometrical constraints and electrode placement. Single slab actuators are demonstrated for semiconductor designs including MEMS applications. Single slab bender periodic designs are demonstrated to be well suited for MEMS fabrication. Shaped actuators having a topological pattern formed across at least one portion are demonstrated to induced strain at the patterned portion of the actuator, causing the patterned portion to flare into open and close positions upon application of an external field. Voltage transformers, spark generators, power sources, and sensors are developed using the non-planar, homogeneous, single slab active member material of non-uniform thickness. Last, semiconductor process design techniques are demonstrated for periodic and other non-planar single slab actuators.

An apparatus for magnetic resonance imaging is described having a casing with an inner bore which in some embodiments is substantially frustoconical shape for receiving a subject. The apparatus contains devices disposed in the casing to create a uniform field within an inner bore. The apparatus employs dual access since the inner bore has a first and second end at the outer edge of the casing for which the part of the subject's body would travel so as to be imaged. Further, in some embodiments, the apparatus provides one or more recesses for inserting at least one gradient coils into position about an inner bore. The MRI system induces resonance in selected dipoles in an examination region created along an inner bore of a casing housing in a magnetic resonance imaging system such that the selected dipoles generate magnetic resonance signals to create an image representation of the part of the subject's body.

The invention relates to a portable NMR detection permanent magnet for radially adjusting a uniform field, which mainly includes a radially adjusting permanent magnet and a base plate. The radially adjusted permanent magnet provides the main magnetic field of the magnet, which is composed of M-layer sub-magnetic ring arrays stacked layer by layer. The inner and outer diameters of each layer of sub-magnetic rings are different, and the magnetic field distribution in the center of the magnet is controlled by adjusting the ratio of inner and outer diameters; the base plate includes upper and lower cover plates and the middle M-1-layer substrate, the upper and lower cover plates are placed at both ends of the magnet, grooves are processed on both sides of the middle substrate, and the magnetic blocks are embedded to form a sub-magnetic ring. The distance between each layer is determined by the substrate; Layers are stacked, and finally the entire magnet structure is fixed with screws. The portable NMR detection permanent magnet provided by the present invention adopts a radial adjustment method to improve the uniformity of the magnetic field, effectively solves the impact of the end effect caused by the limited height of the cylindrical magnet, and realizes the generation of a high uniformity magnetic field in a small volume, which is in line with the future The requirement of portability and miniaturization of NMR system.

In a method and magnetic resonance system for generating a homogenous, radio-frequency excitation field in a spatial examination volume of the magnetic resonance system for a subject examination, the magnetic resonance system having a body coil comprised of N resonator segments or groups and a control and evaluation device for the separate activation of the individual resonator segments electromagnetically decoupled from one another, separate excitation of each individual resonator segment using defined excitation parameters ensue with an examination subject located in the magnetic resonance system and the respective segment-specific or group specific magnetic field distributions in the examination volume are determined. The segment-specific or group-specific magnetic field distributions are computationally superimposed to determine a overall field distribution in the examination volume. The homogeneity of the overall field distribution is evaluated using an evaluation algorithm and a change of one or more excitation parameters of one or more resonator segments or segment groups to compensate for a known field inhomogeneity is determined. The resonator segments or segment groups are excited with the determined parameter change to acquire an a diagnostic image of the subject.

The invention proposes a novel technique for implementing high performance atomic lithography, and in particular high resolution lithography. The technique makes use of Stern-Gerlach type atomic interferometry enabling disturbances to be implemented in the atomic phase of the beam. Such interaction then directly modulates the intensity of the associated wave in the plane extending transversely to the beam of atoms, and does so in controllable manner. The installation of the invention for nanolithography by atomic interferometry comprises a Stern-Gerlach type interferometer comprising, as its phase object, four-pole magnetic induction having a transverse gradient created by four parallel bars carrying alternating direct currents, bracketed between two separator plates, preceded and followed respectively by a spin polarizer and by an analyzer operating by laser pumping. An additional uniform field is being created by another four additional bars powered in paired manner by adjustable currents in order to create a uniform field of arbitrary intensity and orientation for the interference pattern by adjusting the two current parameters. The source of atoms is a source that continuously discharges metastable helium or argon with approximately Maxwell type speed dispersion of about 30% to 40% in order to obtain a central spot.

Methods and pulse sequences for facilitating nuclear magnetic resonance (NMR) measurements in grossly inhomogeneous fields. Methods and pulse sequences according to the invention may be used to accurately measure variables such as transverse relaxation time, longitudinal relaxation time, and diffusion, without the need for data at long recovery time, thereby allowing for faster measurements. In addition, methods and pulse sequences according to embodiment of the invention may allow simultaneous encoding of information in both the amplitude and the shape of echoes, so as to allow a single-shot measurement of multiple variables, e.g., both transverse relaxation time (from the decay of echo amplitudes) and longitudinal relaxation time (from the echo shape). CPMG detection may be used to overcome the often limited signal-to-noise ratio in grossly inhomogeneous fields.

The invention relates to a spherical feedback tricomponent fluxgate magnetic full-tenser gradiometer. Three mutually perpendicular crossed enameled wire winding slots are carved on the surface of a spherical non-conductive material, and more than three tricomponent fluxgate sensors are mounted in the sphere and connected with a triaxial spherical feedback coil to form a closed loop through a control circuit so as to further form the tricomponent fluxgate magnetic full-tenser gradiometer. Compared with the prior art, the uniform field generated by the spherical coil is larger than that generated by other feedback coils; under the same uniformity, the spherical feedback coil occupies the minimum volume; the plurality of fluxgate sensors are placed in one triaxial spherical coil, the fluxgate is in a stable working state in the environment close to zero magnetism, so that mutual interference of the feedback coils during feedback of each fluxgate is avoided, the calibration is facilitated, the baseline distance is greatly shortened, and the system precision is improved. The spherical feedback tricomponent fluxgate magnetic full-tenser gradiometer is particularly suitable for being used in aeronautical, aerospace and other space-limited environments and has a wider application range.

A magnetized structure that induces in a central area of interest a homogeneous magnetic field of predetermined orientation relative to a longitudinal axis (z) of the structure comprises at least two magnetized rings (110, 120) disposed symmetrically relative to a plane (P) that is perpendicular to the longitudinal axis (z) and that contains the central area of interest, and at least one median annular magnetized structure disposed at least partly between the two magnetized rings (110, 120) and also disposed symmetrically relative to the plane (P) of symmetry, one of the two magnetized rings (110) being magnetized radially relative to the longitudinal axis (z) with divergent magnetization and the other of the two magnetized rings (120) being magnetized radially relative to the longitudinal axis (z) with convergent magnetization, and the median annular magnetized structure being magnetized with an orientation different from that of the magnetization of the two magnetized rings (110, 120). The median annular magnetized structure comprises at least one magnetized ring (150) having a magnetization distribution of orientation that varies as in Halbach dipoles and the first two magnetized rings (110, 120) and the median annular magnetized structure are each divided into individual components in the form of regularly distributed identical sectors.

A hybrid wet electrostatic precipitator for collecting sub-micron and nano-particulate material. The collector can be made up of three concentric tubes or pipes with an internally formed gas path communicating between an inlet and an outlet. A first collector and discharging zone can be provided in the gas path to create a corona discharge to charge particles and to collect particulate. A second collector can be formed by a porous wall which can act as a filtration device. A third collector can be formed by two or more of the concentric circular tubes, one porous and one solid, with a zone of uniform electric field between them. The porous tube can be either the inner tube or the middle tube. A liquid pool can be placed between the first and third collectors to provide chemical treatment of the gas flow or simply filtration as the gas passes through. A high-tension voltage supply can be used to supply a discharge voltage capable of generating a corona discharge into the flow in the first zone. The corona discharge can cause the fine particulate to become charged and to be captured on the collecting electrode in a zone of uniform field. A second (or the same) high-tension voltage supply can create the uniform electric field.

The invention discloses a continuous monitor for detecting an aerosol sample, and relates to a continuous monitor for online detection of an aerosol sample by utilizing an ion mobility spectrometry technique. The development of the monitor is based on the ion mobility spectrometry technique; and an ion mobility spectrometry analysis method is used as detection means. The instrument employs air as a sample carrier gas and a drift gas, and a set of purifying and drying gas circuit with a complete system, as well as a uniform field ion mobility tube. An impact type aerosol sampling device is used for sampling samples from atmosphere and gathering the samples to a piece of polytetrafluoroethylene high temperature resistant sampling cloth which is processed specially; the sampling cloth which employs crawler-type transmission is used for gasifying the samples by thermal resolution, and then the samples are carried by the carrier gas to enter the monitor for online detection and analysis. Interval sampling or continuous sampling can be configured in sampling time; usually, the interval sampling time is set to 10-30 s; the time consumption for analyzing the sample once is lower than 60 s; the sensitivity is very high; and the related standard for analysis and detection is achieved. A software control instrument can be used for realizing warning patterns of different aerosol samples.

The invention discloses radio frequency electromagnetic field radiation immunity experiment test device and test method for an electric energy meter. An electric energy meter inspecting device, a communication and display device, a signal generator, a power amplifier and an emitting antenna are connected in sequence, and a main controller is connected with the communication and display device. During test, the electric energy meter inspecting device provides a voltage and current signal needed during the working of a tested electric energy meter and obtains an electric energy meter error value; the signal generator generates a frequency signal required by the test standard; after being amplified by the power amplifier, the frequency signal is transmitted to the emitting antenna, and an uniform field required by the test standard is generated by the emitting antenna; and the communication and display device is respectively communicated with the electric energy meter inspecting device and the signal generator by steps and reads, records and displays frequency information in the signal generator and electric energy meter error value information in the corresponding electric energy meter inspecting device. The invention can automatically record the test frequency and the corresponding electric energy meter error value and can obtain more complete and accurate test data.

A magnetic structure enclosing a prismatic cavity of regular polygonal cross-section is presented. The structure contains the field within the volume of the magnet without the need of an external ferromagnetic yoke, which makes it suitable for generating fields of several Tesla. The structures presented are designed to generate uniform fields for NMR studies, especially high intensity fields.

A method and apparatus for creating uniform heating of an microwave absorptive target. A circularly polarized waveguide mode is created that promotes uniform heating of the microwave absorptive target by rotating a propagated non-uniform field pattern around a central axis of a cylindrical cavity or waveguide. In the process of rotating the field pattern, hot and cold spots in the field pattern are averaged out over time.

The invention discloses an electronic device electromagnetic environmental effect test system and test method under an electromagnetic pulse compound field environment. A tested electronic device is fixed to a tested posture control table and placed in a uniform field test area, the tested electronic device is set to a certain working state by using an electronic device working state controller, and the tested posture control table is adjusted, a magnetic field control circuit and an electronic field control circuit are controlled to set a magnetic field amplitude value and an electronic fieldamplitude value, a magnetic field generator and an electronic field generator are subjected to linkage and trigger, and a compound field is formed to perform an irradiation effect test. The magneticfield amplitude value, the electronic field amplitude value and delaying time are continuously changed from low to high, responding phenomenon and responding signals of the tested electronic device under different interference source parameters are recorded, and effect laws are analyzed. The electronic device electromagnetic environmental effect test system and test method under the electromagnetic pulse compound field environment ensure standardization and rationality of the electromagnetic environmental effect test of the electronic device, improve accuracy of the electromagnetic environmental effect test of the electronic device, and are suitable for carrying out relative research work of an electromagnetic pulse compound field environmental effect test of a ground nuclear explosion source area.