81 results about "Field calibration" patented technology

The invention provides a testing device and a testing method for postprocessor temperature field calibration, and belongs to the technical field of internal combustion engine postprocessing, and the method comprises the following steps: installing the testing device, fixing a plurality of thermocouple probes on a base, and enabling the end surfaces of the thermocouple probes to extend to a specified measurement area of a diesel particle filter; triggering and starting a regeneration process of the diesel particulate filter under a target working condition, and synchronously collecting temperature data from the thermocouple probe in real time; calculating the maximum temperature gradient in the diesel particulate filter based on the temperature data; and comparing the maximum temperature gradient with a preset safety threshold, and adjusting a regeneration control strategy according to a comparison result. According to the invention, the test efficiency, the data accuracy and the economical efficiency are obviously improved.

The invention discloses an alternating current system residual current monitoring device operation verification device and method, and belongs to the technical field of residual current monitoring device verification, the verification device comprises a verification control unit, at least one verification unit and at least one verification CT; the verification control unit sends a control instruction to each verification unit according to the expected current of the to-be-verified residual current monitoring device so as to control the verification unit to output the current, and the current output port of each verification unit is short-circuited through the corresponding configured current output wire so that the current output by the verification unit flows through the current output wire. Meanwhile, a current output wire is wound around a current monitoring CT corresponding to the verification unit, so that the current monitoring CT can measure the real-time disturbance current and the output current of the circuit at the same time; and each verification unit measures the real-time disturbance current of the circuit through the correspondingly configured verification CT. The device can be used for operation field calibration, test acceptance and the like of the residual current monitoring device.

The application provides an array programmable temperature field calibration device and method, belonging to the technical field of temperature measurement and calibration. The device comprises a system control unit, a plurality of temperature control units, a bidirectional temperature control module and a composite heat insulation structure. The system control unit is used to generate control instructions corresponding to a target two-dimensional temperature distribution pattern, and a graphical interface is provided for users to set the pattern. The plurality of temperature control units are arranged in an array to form a radiation surface, and each temperature control unit receives independent control instructions. The bidirectional temperature control module is integrated in each temperature control unit, and is used to independently adjust the temperature of the radiation surface of the unit according to the received control instructions. The composite heat insulation structure is arranged between adjacent temperature control units, and is used to suppress the thermal cross talk between the units. The application can flexibly and efficiently generate a high-precision programmable two-dimensional temperature field, which is used for comprehensive calibration of non-contact temperature sensors.

The invention relates to the technical field of electromagnetic environment effect testing, and discloses a phased array multifunctional electromagnetic environment effect testing system and a calibration method thereof.The system comprises an active array plane, a comprehensive processing extension set, a comprehensive frequency source extension set, an external feed source combination, a superheterodyne receiver and a digital acquisition extension set; wherein the active array plane is provided with a plurality of minimum sub-arrays, each minimum sub-array is composed of at least one active channel and a corresponding radiation antenna unit, and each minimum sub-array is used for receiving one excitation signal to complete power amplification and radiation synthesis; and the path number of the independent excitation signals generated by the comprehensive frequency source extension set corresponds to the number of the minimum subarrays. The calibration method comprises darkroom plane near-field calibration, external feed source combination calibration and active array plane calibration before working. The system and the method provided by the invention have the advantages of relatively strong accurate construction capability of a complex electromagnetic environment, extremely high test flexibility, multi-beam coordination and high-precision full-link calibration, and stable and reliable operation.

The present application relates to electromagnetic environment effect test technical field, disclose a kind of phased array multifunctional electromagnetic environment effect test system and its calibration method, system includes active array surface and comprehensive processing extension, comprehensive frequency source extension, external feed source combination, superheterodyne receiver and digital acquisition extension;Wherein: active array surface has dry minimum subarray, each minimum subarray is formed by at least one active channel and corresponding radiating antenna unit, each minimum subarray is used to receive one way excitation signal to complete power amplification and radiate synthesis;And the number of independent excitation signal generated by comprehensive frequency source extension corresponds with the number of minimum subarray.The calibration method includes darkroom planar near-field calibration, external feed source combination calibration and active array surface calibration before work.The system and method of the present application have strong accurate construction ability of complex electromagnetic environment, extremely high test flexibility, multi-beam coordination and high-precision full-link calibration, stable and reliable operation.

The invention discloses a calibration-free soil dry density in-situ measurement method, and belongs to the technical field of soil physical property detection in geotechnical engineering and agricultural engineering. The method comprises the following steps: firstly, acquiring a volume dielectric constant epsilon and an environment temperature of soil in situ, and acquiring a mass water content omega of the soil in situ; secondly, determining physical parameters of the soil, wherein the physical parameters comprise a soil particle dielectric constant, a soil particle relative density and a water dielectric constant determined according to the temperature T; and finally, substituting the volume dielectric constant, the mass water content omega and the physical parameters of the soil into a calculation model constructed on the basis of a soil solid-liquid-gas three-phase mixed medium theory, and solving to obtain the dry density of the soil. According to the method, a calculation model is constructed based on physical characteristics of a soil solid-liquid-gas three-phase mixed medium, parameters which can be directly measured are obtained in situ, and the dry density is directly solved after the parameters are substituted into the model, so that tedious steps of field calibration in a traditional method are avoided, and in-situ, rapid and calibration-free measurement of the dry density of the soil is realized.

The invention discloses a field calibration device for an airborne navigation system, and belongs to the field of navigation system calibration. The device comprises a positioning and orienting system, a movable three-axis turntable and a portable industrial control all-in-one machine, the positioning and orientation system comprises a gyro north seeker, a laser tracker, a satellite receiver, an RTK data radio assembly, an antenna, a control acquisition box, a battery box, a tripod, a power cable, a gyro north seeker signal output cable, a laser tracker signal output cable, an antenna signal output cable and an acquisition signal output cable; the movable three-axis rotary table comprises an inner shaft table top, an inner code disc, a middle code disc, an outer code disc, an outer motor, an outer slip ring, an inner shaft worm and gear shaft system, a middle shaft worm and gear shaft system, a north guide mirror, a base, an electric control box, a main shaft driver, a power supply and a roller, the given angular position is realized by controlling the rotary table to rotate, and the given angular speed is realized by controlling the rotation angular rate; the attitude angle is given by controlling three axes of the rotary table and is used for attitude calibration of an airborne navigation system.

The utility model relates to the technical field of earthquake monitoring, and discloses an earthquake monitoring station field calibration device comprising a supporting seat; the rotating disc is rotationally connected to the supporting seat, and a pointer is arranged on the rotating disc; the supporting seat is located on the peripheral side of the rotating disc and provided with a dial, the dial is provided with scale marks, and the pointer points to the scale marks; the north seeker is mounted on the rotating disc, the north seeking direction of the north seeker is the same as the direction of the pointer, and the north seeker and the pointer rotate synchronously. According to the utility model, the north seeker is arranged on the rotating disk, the north seeker can determine the true north direction value of an attached carrier by measuring the rotation angular velocity of the earth, the process is not interfered and influenced by an external magnetic field or other environments, the north seeker and the pointer synchronously rotate, and when the orientation direction of the pointer is true north direction, the north seeker and the pointer are in real north direction. A seismometer may be mounted in this direction. Therefore, the installation precision of the seismometer is improved, manual operation errors are reduced, and the precision of earthquake monitoring and early warning is improved.

The invention relates to the technical field of intelligent medical building and traffic planning, in particular to a method for building a three-dimensional parking building in a hospital based on instant modeling and analogue simulation analysis, and solves the problem that a traditional planning method mainly depends on manual investigation and static capacity estimation. In order to solve the problems of backward data acquisition, single analysis dimension, decision dependence on subjective experience and insufficient prediction and evaluation ability in the prior art, the method comprises the following steps: S1, constructing a binocular depth camera operation environment, configuring ORB-SLAM, YOLOv8 and Byterack algorithms, and carrying out simulation test and field calibration; s2, field space properties are investigated on site, the EMR of a patient, namely electronic case data of the patient, is acquired and analyzed, main traffic flow lines of the patient are visualized, and high-frequency nodes and traffic paths are determined. According to the method, the defects of data lag, high subjectivity and the like of a traditional planning method are overcome, a whole-process quantitative decision from data acquisition, simulation modeling to scheme generation is realized, and the hospital traffic efficiency and the medical treatment quality are remarkably improved.

The application discloses a portable switch cabinet dehumidification and temperature and humidity rapid field calibration device and method, which comprises a portable temperature and humidity environment cavity, a calibration installation unit, a standard reference unit, an air flow circulation unit and an intelligent control unit; the intelligent control unit is provided with a self-checking module, a data acquisition module, a calibration judgment module and a calibration locking module; the self-checking module determines an abnormal reference sensor through data comparison logic; the data acquisition module synchronously acquires data and constructs a sliding window data set; the calibration judgment module calculates space uniformity indexes and time stability indexes, compares the space uniformity indexes and the time stability indexes with space uniformity threshold values and time drift threshold values, and judges the environment stability; the calibration locking module calculates an environment reference true value, calculates errors of sensors to be calibrated, and generates a calibration report; the application reduces the volume and weight of the calibration equipment, reduces the deviation caused by local air flow disturbance in the calibration chamber, automatically judges the calibration environment, and improves the calibration quality.

The invention discloses a method for observing the thickness of a plunger-bushing lubricating oil film of a hydraulic rock drill. The observation method comprises the following steps: preparing equipment for observing the thickness of the plunger-bushing lubricating oil film; field-of-view calibration: placing a graduated scale on the focal plane to calibrate the size of the field-of-view of the camera; searching a movable contact area to ensure that the microscope can capture clear interference fringes; parameters of a high-speed camera and a laser source are set, and it is ensured that the contact area can be shot within the set exposure time; and starting a motor, continuously collecting photos under a set working condition, and screening out the photos of the contact area. According to the observation method, non-contact, dynamic and high-precision observation and prediction of the oil film thickness can be realized.

The utility model provides an engineering measurement field calibration and check device, which relates to the technical field of engineering field calibration and check and comprises a calibrator and a base. The edge of the upper surface of the rotating seat is fixedly provided with a plurality of threaded plates which are distributed in an annular array about the center axis of the base, the calibrator is arranged on the upper surface of the rotating seat, the threaded plates are distributed on the periphery of the calibrator, and a gear ring drives the rotating seat to rotate by shifting a gear; the rotating seat can drive the calibrator to rotate and adjust at any angle, the friction plate can descend to be in contact with the upper surface of the rubber ring by rotating the screw rod after the angle of the rotating seat is adjusted, the angle of the rotating seat is fixed by utilizing the friction force between the friction plate and the rubber ring, and the angle of the calibrator is fixed.

This invention discloses a portable on-site calibration device and method for wind sensors. The calibration device includes an execution unit, which, from bottom to top, comprises a base, a stepper motor gear compartment, and a ring angle encoder. A fixing bracket is provided on the side of the gear compartment. A wind speed generating unit includes a horizontally continuous chamber with an air outlet at the rear end. Inside the chamber, a fan module and a honeycomb panel are arranged sequentially along the wind speed direction. The honeycomb panel has uniformly arranged, closely spaced horizontal through holes with an equivalent diameter of 4-8 mm. This invention's wind speed generating unit uses only a combination of a fan module and a honeycomb panel to output a low-speed, uniform wind field. It is compact, low-cost, and has a fully open structure. Combined with an angle scale, angle stop bar, and electromagnet, it can automatically complete the wind direction sensor calibration process.

The invention provides a non-contact river channel video flow measurement system and device based on a smart phone, belongs to the technical field of river channel flow velocity measurement in water resource monitoring, and aims to solve the problems that traditional contact flow measurement is high in cost and complex in operation, and mobile phone video flow measurement has perspective distortion and is difficult in floater identification. The system comprises a video acquisition module, a field calibration module, a video preprocessing module, a target identification and tracking module, a flow velocity calculation module, a front-end interaction module and a cloud service module. The device is composed of an intelligent mobile phone integrated with a front-end module and a cloud server for deploying a core algorithm. Non-contact flow measurement is completed through module cooperation, the cost is low, operation is convenient, precision is high, scene adaptability is high, and effective technical support is provided for water resource monitoring.

A wide-range current transformer field calibration system and a self-checking method thereof, the field calibration system comprising a self-checking circuit and a CPU, the self-checking circuit comprising n groups of tap switches of a primary winding and n groups of tap switches of a secondary winding; a voltage input of a voltage regulating power supply is zero, the CPU controls the n groups of tap switches of the primary winding and the n groups of tap switches of the secondary winding to be closed or opened, a transformation ratio of a standard voltage transformer is consistent with a calibration transformation ratio of a tested current transformer; the CPU controls the voltage regulating power supply to make a current output by a current riser rise to 10% of a rated current of the standard current transformer, and performs self-checking on the field calibration system, if a current percentage value output by an error calibration device rises with a voltage rise of the voltage regulating power supply, and a display value is 0.1%, 1%, 5% or 10%, the self-checking is qualified; otherwise, the self-checking is unqualified. The present application solves problems of many field calibration test devices, complex wiring and difficult guarantee of accuracy.

This invention provides a method for calibrating gust flow fields based on a dynamic pressure sensor probe. Using the dynamic pressure sensor probe, the pressure data under no-wind conditions is averaged and then subtracted from the incoming static pressure to obtain the zero-point pressure. Then, the wind speed control system is activated, and after the wind speed stabilizes, the collected pressure is subtracted from the zero-point pressure to obtain the gust field pressure value. The gust field pressure is then averaged to obtain the gust field atmospheric pressure value at each point. The gust direction angle is obtained by substituting the measured pressure data into the calibration fitting formula, based on the incoming wind speed. Finally, the gust amplitude is obtained by combining the wind direction angle and the incoming wind speed. This method uses simple probe equipment, has low requirements for the measurement environment, is not easily damaged, and can obtain the incoming velocity and gust amplitude in real time. It can also provide the direction angle of the velocity after disturbance by the gust generator.

The invention discloses a field calibration device and method for an underwater spectrum sensor, and the method comprises the steps: preparing standard solutions with various concentrations, including pure water solutions; measuring the standard incident light intensity and each standard emergent light intensity in each standard solution, and obtaining each standard absorbance according to the standard incident light intensity and each standard emergent light intensity; respectively placing the test containers containing the standard solutions in test grooves to measure standard test incident light intensity and each standard test emergent light intensity, and obtaining each standard test absorbance according to the standard test incident light intensity and each standard test emergent light intensity; obtaining a first function relationship according to each standard absorbance and each standard test absorbance; placing the test container containing the standard solution in a field test tank to measure the field test incident light intensity and each field test emergent light intensity, and obtaining each field test absorbance according to the field test incident light intensity and each field test emergent light intensity; obtaining corresponding standard absorbance according to the field test absorbance and the first function relation; and a calibration function is obtained according to the concentration of each standard solution on site and the corresponding standard absorbance, so that the efficiency and accuracy of on-site calibration of the sensor are improved.

This application provides a field calibration system and method for calibrating a laser total station, belonging to the field of laser measurement technology. The field calibration system includes: a reference device, comprising a connecting rod and two position detectors, the two position detectors being fixedly connected by the connecting rod. The position detectors are configured to receive laser light emitted by the laser total station and determine planar position data characterizing the illumination position based on the illumination position of the laser light on the position detectors; wherein, the laser total station is configured to determine the spatial position data of the illumination position in a base coordinate system based on the illumination position, wherein the base coordinate system is established with the base of the laser total station as the origin; and a parameter calibration device, communicatively connected to the reference device and the laser total station, configured to calibrate the laser total station based on the two planar position data and the two spatial position data.

The application belongs to the technical field of sand dust test equipment, and particularly relates to a sand dust test box calibration device and a use method thereof, which comprises: a sealed main machine box; a power supply module, a core control module, an air path and sampling control module, a man-machine interaction module and a wireless communication module integrated in the main machine box; the air path and sampling control module comprises an air suction pump, a gas mass flow meter and a busbar with at least two independent sampling channels connected in sequence, and an electromagnetic valve controlled by the core control module is arranged on each sampling channel; the wireless communication module is used for receiving control instructions sent by a remote wireless remote controller; and the man-machine interaction module is used for parameter setting, information input and state display. The application is highly integrated and portable, integrates power, metering, control and interaction systems in a sealed box body, greatly simplifies the equipment structure of field calibration, is convenient to carry and arrange, and is particularly suitable for field calibration operation.

The application provides a field of view calibration method and a calibration aid. The field of view calibration method comprises the following steps: under the condition that a crucible tray bearing adapter and a centering piece are coaxial, an industrial camera captures a calibration aid in real time to obtain a tracking image; a characteristic element of the centering piece is identified in the tracking image, and a position of the characteristic element in a field of view of the industrial camera is determined; according to the position of the characteristic element in the field of view of the industrial camera, a position state deviation of a pixel profile of the centering piece is determined; the position of the industrial camera is adjusted to eliminate the position state deviation of the pixel profile of the centering piece to obtain a tracking image of a standard field of view; the position state deviation of the pixel profile of the centering piece comprises a centering deviation of the pixel profile of the centering piece in the field of view of the industrial camera and an angle deviation of the pixel profile of the centering piece in the field of view of the industrial camera.

The present application belongs to the technical field of torque detection, and particularly relates to a torque detection device, a field calibration method and a new energy gearbox test bench. The torque detection device comprises a torque detection support, a torque detection motor installed on the torque detection support, a torque detector installed on a torque detection shaft, a calibration fixing assembly arranged at an installation end of the torque detection shaft, a calibration balancing piece detachably connected with the torque detection shaft through a connecting clamping sleeve, and a plurality of weights. When torque detection is performed, the calibration balancing piece and the connecting clamping sleeve are detached from the torque detection shaft, and the torque detection shaft is butted against a workpiece to be detected. When calibration is performed, the calibration balancing piece and the torque detection shaft are coaxially arranged through the connecting clamping sleeve, and the plurality of weights are hung on the calibration balancing piece according to calibration parameters. The torque detection device can realize field calibration of the torque detector without disassembling the torque detector, and has a simple structure and reliable calibration.

The application discloses a kind of automatic measuring device and detection method of lens center thickness, including spectral confocal system and Fizeau interference system, spectral confocal system includes light source, confocal pinhole and optical system, and optical system includes first half reflection half permeation lens, chromatic focus lens and spectroscope;Fizeau interference system includes Fizeau interferometer and computer, and Fizeau interferometer includes laser emission component and first imaging mirror, reference mirror, second beam expander, second half reflection half permeation lens, second imaging mirror and CCD camera.The lens center thickness with error component is measured using spectral confocal system, the physical translation error component, tilt error component of the lens to be measured are detected in real time using field calibration and Zernike wave surface fitting in Fizeau interference system, and the measured lens center thickness is automatically corrected using error correction formula, and then the lens center thickness is accurately measured, which can greatly save labor and time cost, and improve detection efficiency.

The invention discloses a portable theodolite field calibration device and a calibration method thereof, relates to the technical field of theodolite metering detection, solves the problems of low detection precision, complicated operation and difficult maintenance of the existing theodolite detection device, and comprises a heavy tripod, a middle shaft, a light pipe combination box, a detection device leveling mechanism and a computer, the portable theodolite on-site calibrating device is designed by taking an electronic internal focusing collimator as a core design and combining an integrated tablet computer and measuring software, has the characteristics of high detection precision and easiness in operation and maintenance, is small in size and convenient to carry and assemble, can be used for realizing on-site rapid calibration of a theodolite in various environments, and has a wide application prospect. According to the portable theodolite on-site calibrating device, the main collimator can be quickly subjected to auto-collimation calibration through the auto-collimation calibration mirror, the detection precision is improved, and the portable theodolite on-site calibrating device is simple to operate, easy to assemble and debug and simple to maintain.

The application provides a multi-array system installation attitude field calibration method based on coordinate measurement. The method introduces a transition adjustment frame between a single array surface and a mast skeleton. The adjustment frame calibration can be regarded as array surface calibration. A precise total station type electronic angle measurement range finder is used to measure reference target point coordinates. General commercial three-dimensional software is used for data processing and analysis. After single array surface target point measurement is completed each time, data is checked. Array surface correction direction and correction amount are simulated in a three-dimensional model. Array surface installation attitude is corrected one by one by referring to the simulation. The correction process is monitored. The application converts array surface calibration into adjustment frame calibration, does not depend on array surface equipment, avoids repeated measurement and correction of expensive and heavy array surface, reduces workload, improves calibration efficiency, protects array surface and reduces damage.

The application discloses a current transformer field calibration auxiliary wiring robot, which comprises a clamping jaw air cylinder, a tensioning device and pre-wiring, the upper part of the clamping jaw air cylinder is provided with two clamping jaws capable of moving towards each other, the clamping jaws are respectively connected with extension blocks, and the upper part of the extension blocks is provided with semicircular notches; the upper part of the clamping jaw air cylinder is connected with a mounting frame, the upper part of the mounting frame is provided with a hexagonal sleeve, the lower part of the hexagonal sleeve is welded with a circular sleeve, the lower part of the circular sleeve is welded with a rotating sleeve, and the mounting frame is provided with a through hole for the rotating sleeve to penetrate. The application has the advantages that the integrated application of a magnetic device and a camera and other components is achieved, automatic selection and state monitoring of the pre-wiring are realized, the magnetic device uses an electromagnet to adsorb the pre-wiring, the camera is responsible for capturing state information of the pre-wiring, and through precise control of the clamping jaw air cylinder, the advantages of accurate movement and positioning of the pre-wiring are realized.

The present application relates to a kind of near-field scaling compensation methods in dual-antenna station mode, it is related to RCS measurement field, including the following steps: by calculating the relative angle of the position of scaling body at different test distances and dual-antenna, obtain field intensity-distance distribution, determine scaling body placement position;RCS measurement system is built, the background electromagnetic data of the position of not placing scaling body and target position is measured;Scaling ball is placed in the midline position of dual-antenna, electromagnetic measurement is carried out and data is recorded;Subsequently, scaling ball is erected to target position, and electromagnetic measurement is carried out again and data is recorded;The scaling body data measured is combined with the field intensity-distance distribution data obtained by calculation, and the radiation field intensity compensation is calculated, to compensate the measurement data, the present application has the advantages that scaling body is selected suitable position and echo level compensation, improves the RCS measurement precision.

The application provides a kind of reference-free single-axis rotary table optical fiber strapdown inertial navigation field full-automatic calibration method, which can be realized by only needing a single-axis rotary table, replaces the higher precision double-axis or three-axis rotary table and other equipment calibrated by traditional calibration method, reduces the demand for equipment of field calibration, replaces the requirement of accurate north induction and leveling of traditional calibration method, has better adaptability to harsh environment, meets the demand of complex and changeable field, first calibrates horizontal constant bias, then calibrates sky direction gyro scale coefficient and sky direction to horizontal axis gyro installation error, finally calibrates three-axis gyro constant bias, compensates coupling error of each parameter according to the set calibration order, iteratively reduces, generates automatic calibration program by combining the calibration method designed by the application with rotary table control program, realizes full automation of field calibration process, greatly shortens the calibration time compared with traditional calibration method, has the characteristics of simple method, high efficiency and full automation.

The invention provides a calibration and verification device for an oil test box, and the device comprises a modular calibration unit which is used for carrying out the on-site calibration of physical characteristic parameters, electrochemical and optical characteristic parameters of the oil test box; and the portable box body group is used for accommodating the modular calibration unit in an integrated mode capable of being transported in a motorized manner and providing physical protection for the modular calibration unit. Through the design of modular calibration combined with the portable box body group, the problem of field maneuvering calibration of the oil test box is solved, and accurate coverage of each module of the oil test box is realized. By adopting the double box bodies which are physically isolated for integrated storage, the portability and maneuverability are remarkably improved, the requirements of field vehicle transportation and manual carrying are perfectly met, and the core premise of army maneuvering metering guarantee is met. Through the classified calibration design of the modularized calibration unit on physical characteristics, electrochemistry and optical parameters, multi-type detection requirements of the oil test box are met, and separation between calibration and an actual scene is avoided.

1. The name of the design product: multi-range integrated pressure instrument field calibration device. 2. The use of the design product: for field calibration of pressure instrument. 3. The design points of the design product: in shape. 4. The picture or photo that best indicates the design points: use state diagram.

This invention discloses a device and method for measuring the thickness of insulating coatings on metal sheets using off-axis oblique projection at the same point. The invention includes a laser displacement sensor, an eddy current displacement sensor, and a signal processing unit arranged on the same side but off-axis. The eddy current sensor measures the vertical distance *a* from its vertical probe to the upper surface of the metal substrate, and the laser sensor measures the oblique distance *b* from its tilted probe to the measurement point on the upper surface of the insulating coating. The same-point measurement design eliminates interference from sheet deformation. The signal processing unit converts the oblique distance *b* into a vertical height using a field calibration coefficient *k*, and calculates the thickness of the insulating coating *c* = *a* - *(b·k)*. This invention enables high-precision and stable online detection of insulating coatings on metal coils.