543 results about "Field strength" patented technology

The invention discloses an experimental calibration method based on multi-sensor signal fusion processing, particularly relates to the field of data analysis, and comprises the steps of a stepped confrontation disturbance protocol, data stream processing and real-time analysis, and multi-stage logic judgment and calibration execution. A stepped confrontation disturbance protocol is created for the first time, potential errors of the sensor are excited in real time and corrected in a closed loop mode under the condition that system operation is not interrupted, and a traditional shutdown calibration mode is thoroughly replaced; a multi-stage disturbance defense system is constructed, and composite interferences such as spectrum aliasing, overload distortion and signal-to-noise ratio attenuation caused by electromechanical thermal multi-physical field strong coupling are effectively suppressed; laser space calibration and dynamic rigidity modulation technologies are fused, and space drift errors caused by deformation of the mounting base and mechanical loosening are accurately diagnosed and compensated. Finally, long-term precision stability and data fusion reliability of the multi-source sensor under complex working conditions are achieved.

The invention discloses a power distribution network line fault positioning detection system, and relates to the technical field of power distribution network fault detection. The system comprises a mixed information acquisition layer, a fault feature extraction layer, an intelligent diagnosis layer and a fault positioning layer. The mixed signal acquisition layer comprises a high-frequency transient wave recording unit, a power frequency measurement unit, a wireless pulse sensor and a distributed optical fiber temperature measurement unit; the fault feature extraction layer comprises a time-frequency analysis module, a preprocessing module and a three-dimensional feature vector module; the intelligent diagnosis layer comprises a convolutional attention network, a space-time diagram neural network and a transfer learning module; the fault positioning layer comprises a particle swarm module and a fuzzy reasoning module. According to the invention, data information of the cable is acquired through the mixed information acquisition layer, a video analysis window function is dynamically matched with signal characteristics, a time domain graph scale, a frequency domain resonance component and a space field intensity gradient are constructed, fault diagnosis and positioning are carried out by using the intelligent diagnosis layer, and the fault positioning detection efficiency of the power distribution network is improved.

The invention discloses a response time conduction type testing device and method for a radio frequency channel protection device. The response time conduction type testing device comprises a transient field intensity generating device, an isolator, a directional coupler, a first attenuator, a second attenuator, a third attenuator, a first power meter, a second power meter, a high-speed oscilloscope, a vector network analyzer and a radio frequency channel protection device to be tested. According to the method, the response performance of the protection device under the influence of the transient strong field can be comprehensively, safely and accurately evaluated, the amplitude limiting function of the protection device can still be effectively exerted under the action of the transient strong field with an extremely narrow rising edge, and then subsequent devices, circuits and equipment are prevented from being damaged.

The invention provides a large-area split type flexible magnetic tactile sensor with a sensing function, and the sensor employs a plurality of flexible square magnetic sheets which are magnetized in the thickness direction, and the polarities of the flexible square magnetic sheets are alternately arranged in a checkerboard array mode in which the polarities of the magnetic fields of the adjacent flexible square magnetic sheets are opposite, so as to simulate a flexible magnetic film which is magnetized in a folded manner. The magnetic flux density of a contact force acquisition area is enhanced, a U-net algorithm is adopted to carry out field intensity-force relation fitting on the divided acquisition area, and a contact force cloud picture is generated, so that a Hall sensor and a flexible magnetic film can keep a large distance to carry out split type large-area contact force sensing, and lossless split type installation is realized; and compared with simple magnetic field modes such as unidirectional magnetization, the touch sensor has higher sensitivity. According to the size of a required contact force measuring surface, more flexible magnetic touch sensor arrays are arranged, a contact force cloud picture is drawn together through a plurality of units, and the flexible magnetic touch sensor array has application potential in the fields of bionic robots, flexible electronics, medical treatment and the like.

The invention relates to the technical field of connector detection, and discloses a reliability detection method based on a connector. The method comprises the following steps: acquiring real-time monitoring data of a multi-channel electrical sensor of a connector in a power-on state, wherein the real-time monitoring data covers a contact impedance fluctuation sequence, temperature rise gradient distribution and an electromagnetic leakage intensity spectrum; performing time-frequency domain fusion processing on the monitoring data, and extracting dynamic characteristic parameter sets such as impedance attenuation rate, heat conduction lag coefficient and field intensity distortion factor of each contact point; then, according to the parameter space distribution difference, a three-dimensional degradation model comprising a material performance attenuation layer, a contact surface deformation topology layer and an insulating medium loss layer is constructed; coupling mechanical stress and electric heating field intensity distribution based on the model, and generating life prediction indexes of each region; and finally, completing reliability grading according to the indexes, and outputting a detection report with key failure position marks. According to the method, comprehensive and accurate evaluation of the reliability of the connector is realized, and an effective technical path is provided for quality control of the connector.

The invention relates to the field of electric field quantum measurement, in particular to a low-frequency electric field measurement method and a three-photon Rydberg system. The low-frequency electric field measurement method comprises the following steps: moving an atom gas chamber containing cesium atoms to a low-frequency electric field to be measured; cesium atoms are driven by probe light to transition from a ground state 6S1 / 2 to an excited state 6P1 / 2; driving cesium atoms to jump from an excited state 6P1 / 2 to an excited state 9S1 / 2 through decoration light; driving the cesium atoms to transition from an excited state 9S1 / 2 to a higher Rydberg state nP3 / 2 through coupled light to obtain Rydberg atoms; a photoelectric detector is adopted to detect the absorption condition of the detection light; based on the absorption condition, an oscilloscope is adopted to observe EIT spectrum change; based on the EIT spectrum change, obtaining a spectrum frequency shift amount; and the electric field intensity of the low-frequency electric field to be measured is calculated through the spectral frequency shift amount and the polarizability of the Rydberg atoms, so that the shielding problem of the atomic air chamber to the low-frequency electric field can be reduced, the spectral line width is narrower, and the electric field measurement resolution is greatly improved.

The invention provides a keyless entry system calibration method and apparatus, an electronic device and a medium. The method comprises the steps of determining a first region and a second region according to a to-be-calibrated function of a target antenna, a first field intensity threshold and a second field intensity threshold; the first field intensity threshold value is greater than the second field intensity threshold value; the second area comprises the first area; based on the position of the key in the expansion area, determining a first field intensity measurement value and a second field intensity measurement value corresponding to the position; the first field intensity measurement value is the field intensity measurement value of the key relative to the target antenna, and the second field intensity measurement value is the field intensity measurement value of the key relative to at least one other antenna on the vehicle; the expansion area is an area which is in the second area and is not in the first area; determining a judgment rule set according to the to-be-calibrated function; and determining a target field intensity threshold value corresponding to the to-be-calibrated function according to the judgment rule set, the first field intensity measurement value and the second field intensity measurement value.

The present invention discloses a low-frequency large-span electromagnetic wave CT data correction method, which comprises the following steps: Step 1, obtaining the initial emission field strength, the ground surface absorption coefficient and the absorption coefficient in the borehole: using the initial emission field strength obtained in Step 1, the distance from the emission antenna in the borehole to the hole mouth, and the distance from the receiving antenna in the borehole to the hole mouth, to obtain the field strength propagating along the borehole and the field strength propagating along the borehole, and the field strength of the corrected low-frequency electromagnetic wave propagating in a straight line at the shortest distance in the medium. The correction method disclosed by the present invention solves the problem of poor inversion effect of the measured data of the low-frequency cross-hole electromagnetic wave CT, realizes the application of the low-frequency cross-hole electromagnetic wave CT technology in a large hole distance of 20-40 m, improves the detection efficiency and reduces the detection cost.

Described herein are systems and techniques for improving accuracies of determinations made using a nuclear magnetic resonance (NMR) sensing device when the NRM sensing device collects data in a wellbore. NMR sensing devices include a magnet that provides a magnetic field that aligns the spins of protons in substances near the NMR sensing device. The magnetic field strength provided by this magnet affects the sensitivity of the NMR sensing device and affects frequencies that the NMR sensing device effectively uses when the NMR sensing device operates. Furthermore, the field strength of magnets used in an NMR sensing device varies with temperature. Since temperatures within a wellbore vary significantly and since these temperatures affect how an NMR sensing device operates, systems and techniques of the present disclosure collect calibration data in a calibration chamber such that data sensed by the NMR sensing device can be interpreted more accurately when temperatures change.

The invention provides a ship electromagnetic environment prediction method and device based on an empirical model, equipment and a medium, and the method comprises the steps: firstly, carrying out the translation of a space field point in a global rectangular coordinate system according to the geometric position of an original point, and constructing a local rectangular coordinate system; then, based on the local rectangular coordinate system, antenna attitude conversion is carried out on the space field points, and array polar coordinates are generated; then, according to the polar coordinates of the array, a discrimination field domain is constructed by discriminating the relative distance between the space field point and the array antenna; and finally, based on the discrimination field domain, performing gain on a preset field point through a three-dimensional gain graph, and performing field intensity calculation on the preset field point to complete prediction of the electromagnetic environment of the preset field point. According to the embodiment of the invention, the prediction of the electromagnetic environment is realized, the calculation efficiency and precision are improved, and the engineering practice requirements are met.

The invention provides a plasma degumming machine and an ignition method. The plasma degumming machine comprises a Faraday cylinder, a quartz cylinder, an inductance coil and an ignition device, and the top wall of the Faraday cylinder is grounded; the quartz cylinder is arranged in the Faraday cylinder and forms a plasma cavity; the inductance coil is wound on the periphery of the Faraday cup and is used for receiving a high-voltage high-frequency signal; the ignition device is connected to the inductance coil and forms equivalent capacitance with the inductance coil and / or the Faraday cup; wherein the equivalent capacitor is used for coupling high frequency and high voltage from the inductance coil, high field intensity used for ionizing gas is formed in the plasma cavity based on discharge of the equivalent capacitor, and the ignition device conducts the top wall and / or the side wall of the Faraday cup along with increase of the density of plasma obtained by continuous ionization of the gas in the plasma cavity. The plasma degumming machine provided by the invention can realize rapid ignition, and the ignition device can be automatically grounded after ignition. The invention further provides an ignition method based on the plasma degumming machine.

The invention discloses a method for calculating a radio propagation simulation model in a complex environment based on correction factors. The system comprises a correction factor calculation module, a complex environment simulation calculation module, a simulation correction module and a simulation data output module. The correction factor calculation module determines a correction factor according to the difference value between the actual measurement value and the simulation value of the corresponding point; the complex environment simulation calculation module performs simulation calculation on each longitude and latitude point according to an existing simulation algorithm; the simulation correction module corrects the simulation value and the correction factor; and the simulation data output module outputs the simulation data according to the matrix. The method has the beneficial effects that the wireless field intensity simulation prediction precision in a complex urban environment is improved, the prediction error of the corrected model in a high-rise building dense area is remarkably reduced, the accuracy of base station layout and signal coverage is effectively improved, and the method can be widely applied to planning and optimization of a wireless communication network and has a wide application prospect. And powerful technical support is provided for improving communication quality.

The invention discloses a vehicle high-frequency electromagnetic radiation measurement method, device, equipment, medium and product, and relates to the technical field of vehicle test.The method comprises the steps that field uniformity verification is conducted on a whole vehicle electromagnetic reverberation chamber, it is determined that the field uniformity in a target frequency band meets the requirement, a tested vehicle needs to be parked in the whole vehicle electromagnetic reverberation chamber, and the tested vehicle needs to be parked in the target frequency band; all electric equipment which is not necessary for testing is closed by the vehicle; measuring the insertion loss of the whole vehicle electromagnetic reverberation chamber by using a vector network analyzer; performing a radiation emission test on the vehicle in the target frequency band, and receiving and recording test data by using an EMI receiver; and calculating the radiation emission power and the radiation field intensity of the vehicle based on the test data and the insertion loss.

The utility model discloses a crane equipment near-electricity alarm based on field intensity detection in the technical field of near-electricity alarms, which comprises a crane, a signal receiving component is mounted at one end of a crane body of the crane, an induction transmitting module is arranged at one end of a suspension arm of the crane, and the signal receiving component comprises a signal receiving module. The signal receiving module is in electric signal connection with the induction transmitting module, a supporting base is installed at the bottom of the signal receiving module, the safety protection design in the signal receiving module effectively reduces pollution and damage of the external environment to key parts of the equipment, long-term stable operation of the equipment is guaranteed, and the dust removing piece arranged in the protection part can effectively remove dust in the equipment. According to the near-electricity alarm designed in the scheme, impurities accumulated on the explosion-proof glass can be regularly cleaned through cooperation with the guide sliding groove, the clear display effect is ensured, sight blocking caused by dust accumulation is reduced, the safety and reliability in the operation process are improved, and potential safety hazards can be effectively reduced in an electric power construction site.

A system and method for measuring and mapping electromagnetic field strength using an unmanned aerial vehicle (UAV) equipped with a field strength indicator. The UAV records signal power levels while tracking its position via GPS, transmitting data in real-time to a ground station. The ground station software generates detailed maps and charts visualizing antenna signal propagation. Users can customize measurement parameters to achieve desired resolution and granularity. The system and method provide an efficient and automated method for assessing antenna performance across various azimuths and elevations.

The invention discloses a ship electromagnetic environment prediction method based on a deep forest model, and relates to the technical field of electromagnetic compatibility and antennae, and the method comprises the steps: converting the coordinates of each point of given data (simulation data) into a global rectangular coordinate relative to a main ship body, and obtaining an array rectangular coordinate of each point relative to an array plane; converting the array rectangular coordinates of the points relative to the array plane into relative array spherical coordinates of the points when the antenna attitudes are different; the original global rectangular coordinates, the relative array spherical coordinates, the azimuth angle and the pitch angle of each electromagnetic environment simulation point and the logarithmic transformation values of the field intensity values corresponding to the points are constructed into a feature combination of electromagnetic environment prediction; constructing a deep forest model, and training and obtaining optimal hyper-parameters of the model by using electromagnetic environment simulation data; performing coordinate conversion and feature combination on the coordinates of the spatial points to be predicted; obtaining a model prediction value; and obtaining a field intensity value under the original scale. By means of the method, prediction of the electromagnetic environment under a certain simulation working condition can be completed within a very short time.

The invention relates to a basin-type insulator noise reproduction method and system, computer equipment, a computer readable storage medium and a computer program product. The method is applied to a basin-type insulator noise reproduction system. The basin-type insulator noise reproduction system comprises a basin-type insulator, an M-element antenna array and a data acquisition system. The method comprises the following steps: acquiring target noise data of the basin-type insulator based on a data acquisition system; obtaining an expected radiation waveform and expected field intensity distribution of the M-element antenna array based on the basin-type insulator target noise; according to the expected radiation waveform and the expected field intensity distribution of the M-element antenna array, calling a phase regulation and control model to generate an excitation signal; and adopting the excitation signal to drive the M-element antenna array, and synthesizing a basin-type insulator to reproduce noise. By adopting the method, the noise reproduction of the basin-type insulator can be realized.

The invention relates to the technical field of electromagnetic simulation, in particular to a W-band antenna pointing angle simulation analysis method, which comprises the following steps: acquiring the size of a W-band antenna and the form of a radiation unit, extracting main lobe curvature and feed matching characteristics, identifying a main lobe edge interference path, and adjusting a reflection phase to form a dynamic reflectivity boundary. Dividing tetrahedron and hexahedron grids to evaluate polarization consistency, optimizing a field intensity relationship between a main lobe and a side lobe, screening an angle interval, and obtaining a directional angle correction parameter. According to the invention, the specific size and form of the antenna are acquired, the curvature distribution of the main lobe coverage area and the matching relation with the feed structure are deeply analyzed, and the reflection intensity difference between the main lobe path and the side lobe path is monitored, so that the pointing precision and the coverage efficiency of the antenna are effectively improved; according to the antenna design, the performance is ensured, the specific area can be optimized, and the predictability and the stability of the antenna performance are remarkably improved.

The invention discloses a signal enhancement method and device in an industrial plant area, and relates to the field of wireless communication, and the method comprises the steps: firstly, obtaining complete channel state information, and guaranteeing that all decisions are based on real channel characteristics instead of theoretical assumptions; and secondly, if the complete channel state information does not meet the target QoS demand quantization parameter, maximizing a receiving signal to interference plus noise ratio and meeting the target QoS demand are taken as optimization targets, an optimization result is obtained based on channel field intensity distribution information of a preset digital twin model, and finally, the optimization result is controlled and executed to form closed-loop feedback. According to the method, optimization is carried out based on channel field intensity distribution information of a unit space in a digital twin model, and a complex problem needing to be solved by a high-dimensional iterative solution algorithm in related technologies is converted into table lookup and interpolation operation based on space coordinates, so that the calculation complexity is remarkably reduced, the time for obtaining an optimization result is greatly shortened, and the calculation efficiency is improved. Therefore, the time when the terminal is in a poor-quality signal state is greatly reduced.

The present disclosure provides systems and methods for removing electromagnetic interference from low-field magnetic resonance images. In one aspect, a method can include projecting a low-field strength magnetic field toward an object of interest located within a field of view and transmitting a radio frequency pulse sequence to a radio frequency coil assembly configured to selectively excite magnetization in the object of interest within the field of view. The method can further include receiving an output signal from the radio frequency coil assembly during a signal acquisition period and receiving a sample signal from the radio frequency coil assembly during an interference period. The method can further include comparing the output signal and the sample signal to identify an interference component and adjusting the output signal based on the interference component.

The invention discloses a high-power stepless magnetic damping device and a power control method thereof.The high-power stepless magnetic damping device comprises a magnetic resistance magnetic core mechanism, the magnetic resistance magnetic core mechanism achieves control over high-power stepless magnetic damping according to the electromagnetic damping principle, regulation and control response is fast, continuity of constant-power output is guaranteed, and the high-power stepless magnetic damping device is suitable for large-power stepless magnetic damping. And a circle of Halbach magnet array formed by reinforcing magnets is arranged, so that the field intensity in the unit direction is enhanced, and the generation of high-power magnetic damping is realized. According to the power control method, a static Kalman data fusion updating model is introduced for power updating, speed and accuracy are balanced, a PWM signal is output through a PID controller to adjust the input current of a control coil, and therefore the size of a magnetic field is controlled, control over the size of magnetic damping is achieved, stepless regulation and control are achieved, and the control precision is improved. Therefore, stable output of constant power is ensured.

The invention relates to the technical field of microwave ignition, in particular to a microwave generation device, equipment and method for microwave ignition, and the microwave generation device comprises a microwave source, a resonant cavity and a microwave probe; the microwave source serves as an energy source, and single-frequency continuous waves are fed into the resonant cavity through the microwave probe. The resonant cavity receives single-frequency continuous waves, and resonance is generated to collect energy; when the resonant cavity resonates, the position of an electromagnetic wave antinode is located on the microwave probe. And the microwave probe is used for secondarily focusing energy gathered in the resonant cavity on the solid energetic material to be ignited. According to the device, through the cooperative focusing effect of the resonant cavity and the microwave probe, the local field intensity is rapidly improved, the energy transfer path is shortest, the loss is minimum, the energy utilization rate and the ignition efficiency are greatly improved, and the problems that in the prior art, microwave ignition cannot achieve full utilization of energy, and the ignition efficiency is low are solved. And the problems of high excitation power, high energy consumption, low ignition efficiency and poor safety are solved.

The embodiment of the invention provides a precipitation particle type identification method and device, a storage medium and electronic equipment, and the method is applied to a server, and comprises the steps: obtaining a reflection signal value of a measured precipitation particle through a base station; acquiring the field intensity attenuation of the wireless signal transmitted by the base station through the base station and the receiver; and determining the type of the measured rainfall particles based on the reflected signal value and the field intensity attenuation amount. Through the method and the device, the problem of low accuracy of identifying the type of the rainfall particles is solved, and the effect of improving the accuracy of identifying the rainfall particles is further achieved.

The invention belongs to the technical field of transformer substation engineering monitoring, and relates to a transformer substation engineering monitoring method based on intelligent perception, which dynamically generates a hoisting track envelope space containing a specified crane boom body and a hoisting object based on historical action inertia characteristics, current operation target constraints and real-time position feedback. Associating hoisting track envelope spaces of other cranes on a substation site, calibrating an envelope space intersection domain as a tangible collision risk domain, synchronously monitoring electromagnetic field intensity space distribution of an electric field source of the substation, and dynamically calculating a safety spacing margin threshold value between the tail end of a specified crane suspension arm and the nearest electric field source based on a field intensity gradient change rate and suspension arm pose parameters; and the nearest electric field source space coverage domain smaller than the margin threshold value is calibrated as an invisible collision risk domain, and when the specified crane enters the tangible collision risk domain or the invisible collision risk domain, a graded early warning signal is triggered, so that the application degree and precision of hoisting collision monitoring of the crane of the transformer substation are remarkably improved.

A sensor element is for testing a planar data carrier with a spin resonance feature. The sensor element includes a magnetic core having an air gap into which the planar data carrier can be inserted for testing purposes, a polarization device for generating a static magnetic flux in the air gap, and a resonator device for exciting the spin resonance feature of the data carrier to be tested in the air gap. The resonator device has at least two stripline resonators positioned at different positions in the air gap. The polarization device generates an in-homogeneous magnetic flux in the air gap so that the static magnetic flux has a first field strength at the position of a first stripline resonator and a second, different field strength at the position of a second stripline resonator.

The invention belongs to the technical field of radio frequency electromagnetic field measurement, and particularly discloses a quantum field intensity measurement method and system regulated and controlled by an offset electric field, and the method comprises the steps: selecting a Rydberg atomic energy level close to resonance according to the microwave frequency of a measured signal; according to the energy level of the Rydberg atom, determining the wavelength of coupled light and preparing the Rydberg atom, meanwhile, obtaining the difference value between the microwave frequency and the resonance transition frequency of the measured signal, and obtaining the energy level offset according to the difference value; acquiring the polarizability of the Rydberg atomic energy level, and acquiring a to-be-applied offset electric field value according to the energy level offset and the polarizability; according to the offset electric field value, an offset electric field is started, so that the related energy level of the Rydberg atoms moves in the offset electric field, when the energy difference between the offset Rydberg energy level and the adjacent energy level resonates with the microwave frequency of the measured signal, the offset sub-energy level forms energy level splitting and generates frequency splitting, and the frequency splitting is generated; and the electric field of the measured signal is measured according to the interval between the frequency splitting.

The invention provides a strong electromagnetic pulse radiation effect equivalent test method under a transmitting port matching condition, and the method comprises the steps: carrying out the irradiation through employing a high-power electromagnetic pulse source under a first preset field intensity, and recording a first response signal of a target cable; stopping irradiation, clamping a current injection probe on the target cable, and connecting the target cable with a signal source; performing Fourier transform on the first response signal to obtain a frequency domain signal, and determining a target pulse signal according to the frequency domain signal; adjusting the injection voltage of the current injection probe according to the target pulse signal, and monitoring a second response signal of the target cable; and performing a high-field-intensity extrapolation test according to the second response signal to complete the electromagnetic radiation effect test process. According to the invention, the equivalent difference mode response of each line to the terminal in the tested end under the irradiation and injection conditions is taken as an equivalent basis, and the equivalent pulse during injection is calculated by using the response of the irradiation test, so that the strong electromagnetic pulse radiation effect equivalent test based on the large current injection technology is completed.

The invention provides a lightning protection device current leakage detection method and system, and the method comprises the steps: firstly determining equivalent uniform field response signals corresponding to a rotating electromagnetic field at different rotating moments, and dividing the surface of a lightning protection device into a plurality of current detection blocks; the field intensity coupling relation between the surface of the lightning protection device and the detection probe in the detection probe array is determined according to the equivalent uniform field response signal corresponding to the rotation moment; determining a current density inversion field of the surface of the lightning protection device at the rotation moment by combining the frequency domain characteristics of the equivalent uniform field response signal corresponding to the rotation moment through a field intensity coupling relationship; and generating a current density topological graph of the leakage current of the lightning protection device based on all the density inversion fields, and positioning the leakage current position of the lightning protection device according to a current density abnormal region in the current density topological graph. By adopting the scheme of the invention, the influence of the complex geometric structure of the lightning protection device on the space positioning of the surface leakage current can be reduced.

The invention provides a regional electromagnetic intelligent evaluation method and system based on spectral entropy weighting, and the method comprises the following steps: collecting electromagnetic spectrum data and the motion state of a patrol vehicle, and constructing a virtual aperture data matrix through the motion information; space covariance analysis and subspace projection are carried out on the matrix, multipath scattering interference is separated and eliminated, and a pure field intensity sequence is obtained through reconstruction. By calculating the normalized spectrum entropy of the Doppler power spectrum of the pure field intensity sequence, an inverse proportion weight coefficient representing the signal confidence is generated; and weighting the weight to a pure field intensity sequence, and mapping the pure field intensity sequence to a geographic space. And dynamically adjusting the density of the evaluation grid according to the field intensity gradient, and finally carrying out weighted centroid calculation based on inverse proportion weight to obtain a regional electromagnetic environment evaluation result. According to the method, the technical problem that a regional evaluation result is not accurate due to the fact that multipath components cannot be separated and single-point data quality cannot be evaluated in traditional mobile patrol is solved.

The present disclosure provides various devices, systems, and methods for active shimming for an MRI system. For example, an MRI system can a first gradient coil, a second gradient coil, a third gradient coil, and a permanent magnet. The permanent magnet is configured to generate a magnetic field B0 having a low field strength. A method for active shimming the MRI system can include a set of candidate shimming configurations with first current values associated with the first gradient coil, second current values associated with the second gradient coil, and third current values associated with the third gradient coil. The method further includes applying, for each candidate shimming configuration, a pulse sequence; acquiring, for each pulse sequence, a magnetic resonance (MR) signal; determining, for each MR signal, a signal bandwidth based on a frequency domain of the MR signal; and designating a shimming configuration for the MRI system.