19 results about "Shielding factor" patented technology

The invention relates to a design method of a magnetic shielding system and the magnetic shielding system.The design method of the magnetic shielding system comprises the steps that a shielding parameter calculation model of multi-layer cylinder magnetic shielding is established, parameters of the cylinder magnetic shielding serve as input, and shielding coefficients serve as output; performing optimization solution on the shielding parameter calculation model through a first optimization algorithm to obtain an optimal shielding parameter combination; the optimal shielding parameter combination is used for building a passive magnetic shielding cylinder; establishing a magnetic field calculation model generated by the magnetic field decoupling shimming coil in the passive magnetic shielding cylinder, taking the parameters of the cylinder magnetic shielding and the parameters of the shimming coil as inputs, and taking the magnetic induction intensities in the radial direction, the azimuth angle and the height direction as outputs; optimizing the magnetic field decoupling shimming coil configuration by adopting a second optimization algorithm based on the magnetic field calculation model to obtain an optimal coil configuration; the magnetic field decoupling shimming coil is wound in the passive magnetic shielding cylinder based on the optimal coil configuration. Through collaborative optimization of magnetic shielding and shimming coils, extremely weak magnetic measurement is realized.

The present application relates to a kind of magnetic resonance imaging anti electromagnetic interference coil design method, the method includes six execution steps: step 1, input superconducting magnet coil structure;Step 2, determine the position of anti electromagnetic interference coil;Step 3, calculate the number of turns of anti electromagnetic interference coil;Step 4, integrate superconducting magnet coil and anti electromagnetic interference coil structure information and calculate magnetic field transfer vector, inductance matrix, coil area vector;Step 5, construct mathematical optimization model with shielding factor as objective function and solve the axial position of anti electromagnetic interference coil;Step 6, anti electromagnetic interference coil number of turns integer optimization and calculate shielding factor.The method can be applied to the anti electromagnetic interference coil design of any magnetic resonance imaging superconducting magnet, has good design flexibility and engineering applicability.

The present invention discloses a wire quality detection method based on wire shielding performance, comprising the following steps: collecting electromagnetic interference source data and wire structure data; performing a matrix construction operation to obtain a magnetic interference source characteristic matrix; performing a matrix value extraction operation to obtain a first energy impact factor and a second energy impact factor; performing an interference parameter construction operation to obtain an initial interference degree sequence; performing a sequence update operation to obtain an interference degree distance sequence; performing a cluster region extraction operation to obtain a sensitive shielding region; performing a calculation to obtain a sensitive shielding factor; performing a calculation to obtain a wire shielding value; when the wire shielding value is less than a preset wire shielding performance threshold, determining that the wire shielding performance does not meet the requirements; and when the wire shielding value is greater than or equal to the preset wire shielding performance threshold, determining that the wire shielding performance meets the requirements. This method reflects the shielding performance of the wire by combining electromagnetic interference source and wire structure data, thereby improving the accuracy of wire quality detection.

The application discloses a kind of arbitrary shape energized coil magnetic field calculation method considering magnetic shielding effect, it is related to the technical field of magnetic field calculation, by the technical method in the present application, in the physical scene of the existence magnetic shielding effect, arbitrary shape energized coil is equivalently converted into combination coil, then shielding coefficient considering magnetic shielding effect is added to each current-carrying straight segment, shielding coefficient is optimized by difference evolution algorithm, then the space magnetic field generated by energized coil at different positions is obtained by forward calculation;The magnetic field calculation method of the application can simplify the magnetic field calculation process of arbitrary shape energized coil under different application scenarios, improve the calculation efficiency, and has strong applicability and wide application range.

The invention relates to the technical field of wire and cable detection equipment, and discloses a cable measurement clamp for suppressing electromagnetic interference signals, comprising an all-copper base on which two displacement guide rods are vertically fixed; the displacement sliding block can slide along the guide rod and is driven by a trapezoidal thread screw with an adjusting hand wheel; the locking mechanism is used for locking the position of the displacement sliding block; the copper belt guide wheel and the high-density red copper woven belt are arranged on the displacement sliding block. And the woven belt forms an adjustable annular structure through the guide wheel, is used for wrapping a cable shielding layer in a full-wrapping surface contact manner, and is electrically connected with the binding posts on the all-copper base and the displacement sliding block. According to the invention, the contact resistance is greatly reduced through surface contact, and accurate control and stable maintenance of the clamping force are realized through graded clamping and locking design, so that the accuracy and repeatability of the shielding coefficient test are remarkably improved on the premise of not damaging the cable, and the device is particularly suitable for detection of various railway signal cables.

The invention discloses a method for calculating the induced voltage of a metal sheath of a direct-current cable laid in parallel with alternating current and direct current. The method comprises the following steps: calculating the penetration depth of an electromagnetic field in the ground; utilizing a mirror image method to simulate the influence of the ground on the conductor, enabling the ground conductor to be equivalent to a virtual mirror image conductor with a specific depth, and determining the distance from the power transmission conductor to the induced conductor and the mirror image conductor; calculating the magnetic induction intensity based on the distance, and deducing the magnetic flux per unit length of a conductor and a ground loop through magnetic field superposition; calculating induced electromotive force generated by the single wire on the induction conductor; calculating the induced electromotive force generated by each phase on the induction conductor by combining the relative position and the phase difference of the three-phase current; the shielding effect of the metal sheath is considered, a shielding coefficient is introduced, and the total induced electromotive force of the direct-current cable metal sheath is obtained through the superposition principle. The method can effectively improve the accuracy of induced voltage prediction and the engineering application efficiency.

The invention relates to a channel estimation method of a multi-RIS auxiliary OFDM system facing an occlusion scene. The method specifically comprises the following steps: firstly, modeling by introducing a shielding factor, and constructing a cascade channel model representing a multi-RIS shielding state; secondly, multiple RISs are divided into different groups, a grouping training protocol is designed, and effective signal components are extracted by subtracting signals received by adjacent time frames; then, a three-dimensional tensor signal model is constructed by combining the structure sparse characteristic of a channel, and the actual shielding condition is estimated by adopting a tensor decomposition and clustering algorithm; and finally, based on the estimated shielding information, designing a shielding compensation and channel recovery scheme so as to realize reconstruction of each channel parameter and a complete channel. According to the method, high-precision and robust channel estimation can be realized with relatively low hardware complexity and training overhead in a shielding environment, and the communication reliability of the multi-RIS auxiliary OFDM system is effectively improved.

The application discloses a method for measuring second-order Zeeman frequency shift of an atomic fountain, and the method comprises the following steps: acquiring an external axial magnetic field variation through a measuring device installed on a cesium atomic fountain clock; when the external axial magnetic field variation does not exceed a variation threshold, the cesium atomic fountain clock does not need to be interrupted, a coarse measurement of a center frequency of a current magnetic-sensitive Ramsey transition fringe is realized according to the magnetic field variation and a shielding factor, and a corresponding second-order Zeeman frequency shift is obtained; when the external axial magnetic field variation exceeds the variation threshold, the cesium atomic fountain clock is interrupted, and an accurate measurement of the center frequency of the current magnetic-sensitive Ramsey transition fringe is realized by using a magnetic-sensitive Ramsey transition method, and a corresponding second-order Zeeman frequency shift is obtained. The application can realize real-time, rapid and accurate measurement of the second-order Zeeman frequency shift, and is helpful for reducing a deviation between the cesium atomic fountain clock and an international atomic time, improving a monthly operation rate of the cesium atomic fountain clock, and improving a position of the cesium atomic fountain clock in international atomic time calibration.

The invention provides a radar simulation model target intervisibility calculation method and system based on a terrain shielding table, and the method comprises the steps: collecting and calculating elevation data based on the elevation data in a TIF format, carrying out the arrangement management through employing a tile pyramid model, and carrying out the hierarchical management of the elevation data. Before simulation operation, terrain shielding tables are generated in batches according to radar deployment positions and basic performance parameters. In the simulation operation process, the radar model calculates the oblique distance, azimuth angle and pitch angle parameters of the target in the effective detection range, all shielding points of the terrain shielding table are traversed until the shielding point closest to the target point is found, and the target pitch angle is compared with the shielding angle of the shielding point to determine the target pitch angle. And calculating an intervisibility result of the radar model and the target. According to the method, an algorithm which considers the influence of a terrain shielding factor on a radar detection result is improved, the accuracy of intervisibility calculation of an aerial target in an effective detection range by the model is greatly improved, and the confidence coefficient of a simulation result is ensured.

The application belongs to the technical field of ship identification, and specifically discloses a ship target identification method and device based on multi-modal fusion, which comprises the following steps: acquiring radar echo data and satellite image data of a water area to be identified in real time, and quantifying a radar electromagnetic scattering interference factor and a satellite optical shielding factor; based on the radar electromagnetic scattering interference factor and the satellite optical shielding factor, dynamically allocating fusion weight coefficients of the radar echo data and the satellite image data through a bilinear pooling network of an attention mechanism, and performing feature fusion on the radar echo data and the satellite image data based on the fusion weight coefficients to obtain a fusion feature map; based on a pre-constructed spatiotemporal consistency loss function, aligning a radar echo data time sequence track in the fusion feature map and a ship body contour in the satellite image data in the time and space dimensions; and based on the aligned fusion feature map, determining the classification and position of a ship target.

The application relates to a low-level swept field test method and device, computer equipment, a computer readable storage medium and a computer program product. The method comprises the following steps: acquiring multiple preset polarization modes of a transmitting antenna, multiple preset illumination angles, and a reference electric field intensity corresponding to each preset polarization mode; for a preset combination formed by different preset polarization modes and different preset illumination angles, acquiring a received electric field intensity of an electric field in a first electromagnetic wave received by a receiving antenna under the condition that the transmitting antenna transmits an electromagnetic wave with a preset intensity based on the preset combination; and determining a target shielding coefficient of a measured system based on the received electric field intensity corresponding to the preset combination in which the preset polarization mode is located and the reference electric field intensity corresponding to the preset polarization mode. The method provided by the application can make the determined shielding coefficient more accurate.

The invention discloses a method for measuring the second-order Zeeman frequency shift of an atomic fountain, and the method comprises the steps: obtaining the variable quantity of an outer axial magnetic field through a measurement device disposed on a cesium atom fountain clock, and enabling the operation of the cesium atom fountain clock not to be interrupted when the variable quantity of the outer axial magnetic field does not exceed a change threshold value. According to the magnetic field change and the shielding factor, rough measurement of the center frequency of the current magnetic-sensitive Ramsey transition fringes is achieved, a corresponding second-order Zeeman frequency shift is obtained, when the outer axial magnetic field change quantity exceeds a change threshold value, operation of the cesium atom fountain clock is interrupted, accurate measurement of the center frequency of the current magnetic-sensitive Ramsey transition fringes is achieved through a magnetic-sensitive Ramsey transition method, and the precision of the center frequency of the current magnetic-sensitive Ramsey transition fringes is improved. And the corresponding second-order Zeeman frequency shift is obtained. According to the method, the second-order Zeeman frequency shift can be rapidly and accurately measured in real time, and great help is provided for reducing the deviation between the cesium atom fountain clock and international atomic time, improving the monthly operation rate of the cesium atom fountain clock and improving the status of the cesium atom fountain clock in international atomic time calibration.

The utility model relates to the technical field of winding machines, in particular to a three-hook needle type winding machine suitable for a small-sized annular magnetic ring, and the magnetic performance test of a material is an important means for characterizing the material in different test environments. The method mainly comprises direct-current magnetic performance testing, alternating-current magnetic performance testing, material residual magnetism testing, material magnetic noise testing, material shielding coefficient testing and the like. Before direct-current and alternating-current magnetic performance tests are carried out, copper wires of different specifications need to be wound on a small annular sample. At present, the process is mainly completed manually, that is, an operator manually winds copper wires of two specifications for the front and back of a sample. In order to solve the problems that the consumed time is long, the quality of a wound coil has large randomness, and the consistency and reliability of a test result are difficult to guarantee, the three-crochet-needle type winding machine suitable for the small annular magnetic ring provided by the utility model is characterized in that a three-crochet-needle winding mechanism comprises an upper crochet needle, a right crochet needle and a left crochet needle; after the three crochet hooks act in sequence, a metal wire can be quickly wound on a small annular sample, and the winding machine is simple in mechanism and easy to industrialize.

The invention discloses a bauxite component quantitative detection method and system, and relates to the technical field of bauxite component quantitative detection, and the method comprises the following steps: building a dust dynamic sensing reference around a light path area of an intelligent sensing system, and extracting stable fluctuation characteristics of environment background light intensity through continuous high-frequency collection of incident light intensity along with time; and on the basis of the established dust dynamic sensing reference, synchronously comparing the reflected light intensity change acquired in real time, and when the rhythm of the reflected light intensity change deviates from a stable fluctuation characteristic, judging that the currently acquired data contains an environment shielding factor, and marking the corresponding spectral data as a dust influence state. Through trend constraint and continuous connection fusion, smooth characteristic peak change is maintained, and dynamic feedback adjustment is realized, so that the detection precision and data consistency are maintained under the dust disturbance condition, and the stability and reliability of quantitative detection of bauxite components are improved.

The utility model relates to the technical field of buildings, and particularly discloses an anti-seismic assembly type building body with a double Faraday cage structure, a plurality of frames comprise assembly type wall bodies and are used for fixing the assembly type wall bodies, each assembly type wall body comprises a shearing force frame, a plurality of Faraday cage plates are arranged on the two sides of each shearing force frame, and the Faraday cage plates are arranged on the two sides of each shearing force frame. Mounting cavities are formed in the Faraday cage plates located on the two sides of the shear frame, and filler is arranged in the mounting cavities. A plurality of through holes are formed in the Faraday cage plate in a rectangular array mode, and the edge of one side of each through hole is warped up to form a hole plate. The thickness of the Faraday cage plate is 0.8 mm, and the through holes are square holes of 20 mm * 20 mm. According to the shielding coefficient of the space grating type shielding, the lightning protection performance and the anti-electromagnetic interference performance are stronger; due to the arrangement of the pore plate, when other thermal insulation materials are installed, the thermal insulation materials can be embedded into the thermal insulation board through the pore plate, so that the thermal insulation boards are fixed more tightly, and meanwhile waste materials are prevented from being generated when the through holes are formed.

The invention discloses a radiation shielding factor determination method and device, equipment and a storage medium, and belongs to the technical field of computers. The method specifically comprises the following steps: acquiring radioactive source information and a shielding material of a to-be-detected area; based on the radioactive source information, obtaining at least one radioactive source irradiation type; based on preset structure parameters, performing reconstruction processing on the shielding material to obtain shielding material structure information; constructing a plurality of shielding object models based on preset life body parameters, at least one radioactive source irradiation type and the shielding material structure information; and determining the radiation shielding factor based on at least one radiation source irradiation type, the shielding material structure information and a plurality of shielding object models.

The invention discloses a mechanical arm for industrial manufacturing, and relates to the technical field of welding mechanical arms. Comprising a mechanical arm main body part, and a cleaning part is mounted on the mechanical arm main body part and used for cleaning impurities on the mechanical arm main body part; two guide mounting pieces are mounted on the mechanical arm main body piece; the two guide mounting pieces are respectively used for detecting the abrasion of the mechanical arm main body piece; the two sleeving extrusion pieces are mounted on the mechanical arm main body piece, and the two guiding mounting pieces are sleeved with the two sleeving extrusion pieces correspondingly; the distance detection piece can be used for detecting the distance between the movable contact and the fixed contact when the movable contact and the fixed contact are attached to clamp a workpiece, and can be used for detecting factors such as distance increase or shielding caused by deformation of a welding area of the workpiece, and once problems such as bending exist at a welding position, welding quality reduction and even desoldering are easily caused; the problems that according to an existing resistance welding mechanical arm for industrial manufacturing, the welding distance cannot be automatically monitored conveniently, and the welding quality is easily affected are solved.

The invention specifically discloses a superconducting wind generator Dewar magnetic field shielding performance testing method and system, and relates to the technical field of electromagnetic compatibility testing. According to the method, a test system comprising a shielding chamber, a self-made rectangular loop antenna, a one-to-two power divider, a low-frequency signal source and a low-frequency spectrometer / low-frequency receiver is configured to measure the gain between a transmitting antenna and a receiving antenna with or without a Dewar assembly; and if the received signal is larger than the background noise by 6dB when the Dewar assembly exists or does not exist, determining the lowest frequency corresponding to the condition as the test starting frequency, calculating a shielding coefficient SF, and evaluating the magnetic field shielding performance of the Dewar. The system is simple in configuration, low in cost, good in repeatability and small in uncertainty, and can effectively meet the test requirements of the Dewar magnetic field shielding performance of the superconducting wind power generator.