Abstract: A foreign object detection device includes a detection coil unit including a detection coil substrate (220) and a plurality of coils (242), which are mounted on a surface of the detection coil substrate (220) and each include a conductive pattern turned around the Z axis, and a detector (26) connected to the coils (242) to detect the existence of a foreign object on the basis of a vibration signal output when each of the coils (242) is excited. The coils (242) each define an opening. The detection coil substrate (220) has a through hole (228) extending through the detection coil substrate (220), and a component space for accommodating a switch (248) or a wiring pattern (250), within each of the openings of the coils (242) as seen in the Z-axis direction.

Abstract: A magnetic inductance tomography (MIT) device for imaging a tissue of a patient can include multiple coils, electronic circuitry, and one or more processors. The electronic circuitry can separately energize individual coils of the multiple coils to generate magnetic fields perturbed by the tissue. The one or more processors can receive MIT signals responsive to the magnetic fields perturbed by the tissue and process the MIT signals to generate an MIT image. The MIT signals can include a first MIT signal generated by a first coil of the multiple coils and a second MIT signal generated by a second coil of the multiple coils. The first MIT signal can be indicative of a characteristic of the tissue at a different depth in the tissue from a surface of the tissue than the second MIT signal.

Abstract: A magnetic element for strengthening a magnetic field formed in an object and an eddy current sensor using the magnetic field are provided. The eddy current sensor includes a bottom face portion which is a magnetic body, a magnetic core portion provided at the middle of the bottom face portion and a peripheral wall portion provided on the periphery of the bottom face portion. The eddy current sensor further includes an excitation coil disposed on an outer periphery of the magnetic core portion and capable of generating a magnetic field and an excitation coil disposed on an outer periphery of the peripheral wall portion and capable of generating a magnetic field.

Abstract: An apparatus for determining magnetic properties of a portion of a magnetizable endless belt. The apparatus includes a primary coil for generating a magnetic field. The windings of the primary coil are wound around the endless belt. A secondary coil measures the magnetic flux density. A slotted yoke guides the magnetic flux. The endless belt extends through slots in the yoke. First measuring devices measure the magnetic field in a width portion parallel to the endless belt. Second measuring devices measure the magnetic field in the width portion parallel to the endless belt.

Abstract: A method for determining an effective case depth of a metal component includes forming a conditioned core surface by blasting or shot peening an exposed surface of the metal component with blast media. The exposed surface is a contiguous exposed surface of the case and core. The method includes measuring surface texture, compressive stresses, or another suitable characteristic of the conditioned core surface using a surface metrology sensor, and identifying a case-core boundary using the measured characteristic, including identifying a location at which a predetermined difference or gradient in the characteristic is present within the exposed surface. The method also includes measuring the effective case depth as a perpendicular distance between a reference surface of the case and the case-core boundary.

Abstract: The present disclosure provides a high-frequency magnetoimpedance testing apparatus and method. A testing platform in the apparatus is arranged within a Helmholtz coil and connected to a modulating electric current source and a high-frequency impedance analyzer, respectively; the Helmholtz coil is connected to a DC power source; a processor is connected to the high-frequency impedance analyzer and the DC power source separately; the testing platform includes a first double-sided copper-clad plate, and mode transition switches and connection terminals that are arranged on the first double-sided copper-clad plate; one end of the first double-sided copper-clad plate is connected to the high-frequency impedance analyzer, while the other end of the same is connected to a load; the mode transition switches are connected to the modulating electric current source.

Abstract: An apparatus and method for the non-destructive determination of the content of the magnetizable and/or non-magnetizable portion of a sample, in which the sample is provided in an air gap of a magnetically conductive yoke, an alternating magnetic field is generated by an alternating magnetic field strength of an excitation coil in the yoke, and first measurement data relating to the sample are collected using a measuring device which is inductively coupled to the yoke, and comparing the first measurement data to second measurement data relating to a reference sample, wherein the same alternating magnetic field strength or the same alternating magnetic field is applied to both the reference sample and the sample and the difference between the two collected sets of measurement data is included as a measure in the determination of the content for the magnetizable and/or non-magnetizable content portion of the sample.

Abstract: A wireless power transmitting device transmits wireless power signals to a wireless power receiving device using an output circuit that includes a wireless power transmitting coil. Measurement circuitry is coupled to the output circuit to help determine whether the wireless power receiving device is present and ready to accept transmission of wireless power. The measurement circuitry includes a measurement circuit that is coupled to the output circuit and that measures signals while oscillator circuitry supplies the output circuit with signals at a probe frequency. The measurement circuitry also includes a measurement circuit that is coupled to the output circuit and that measures signals while the oscillator circuitry sweeps signals applied to the output circuit between a first frequency and a second frequency to detect sensitive devices such as radio-frequency identification devices. Impulse response circuitry in the measurement circuitry is used to make inductance and Q factor measurements.

Abstract: The invention relates to a method for observing a magnetic field of a material volume, in particular for determining properties of a workpiece under, in particular, magnetic, mechanical, thermal, and/or electrical excitation of a material volume of the workpiece, wherein the magnetic field of the material volume is sensed as a function of time and of frequency with high frequency resolution.

Abstract: A particle alignment method in accordance with at least one of the present inventions includes the step of positioning a cochlear implant, which is implanted within a patient's head and which includes a magnet apparatus with a central axis and magnetic material particles, at a location outside of the scanning area of an MRI system, adjacent to the MRI system, and within the MRI magnetic field in such a manner that the central axis of the magnet apparatus is at least substantially parallel to the MRI magnetic field.

Abstract: Aiming at a hardness mismatch phenomenon in the existing structure hardness design process according to an integral intensity viewpoint, the invention provides a quantitative matching design method for structure heat treatment-hardness distribution. The specific method comprises determining an ideal static intensity field distribution of the dangerous section of the structure according to a limit static stress distribution of a dangerous section of the structure; determining an ideal hardness distribution of the dangerous section of the structure by utilizing an intensity-hardness conversion relation; determining heat treatment requirements such as surface hardness, core hardness and the like by combining material and heat treatment mode; determining an actual hardness distribution of the dangerous section of the structure according to a material end quenching curve and the heat treatment requirement.

Abstract: A material defect detection device that detects a material defect in a predetermined region of metallic equipment using a magnetic field distribution in the predetermined region measured by a magnetic sensor array including a plurality of magnetic sensors, the material defect detection device including: a processor that calculates a density distribution of magnetic dipoles in the predetermined region based on the magnetic field distribution and calculates a depth distribution of material defect in the predetermined region based on the density distribution of the magnetic dipoles.

Abstract: A system for measuring torque on a component having a residually magnetized region is provided. The system includes a torque sensor for sensing an electromagnetic characteristic of the component and transmitting a plurality of signals that are indicative of the electromagnetic characteristic. The system also includes a computer communicatively coupled to the torque sensor for receiving the signals. The computer includes a processor and a memory. The processor is programmed to determine, using the signals, that the torque sensor is affected by the residually magnetized region of the component.

Abstract: A semiconductor device includes a semiconductor substrate; a vertical Hall element including a magnetosensitive portion, and formed in the semiconductor substrate; and an excitation wiring provided above a surface of the semiconductor substrate and apart from the magnetosensitive portion. The excitation wiring is formed of a single wiring with a plurality of turns. The excitation wiring includes a plurality of main wiring portions arranged side by side, and apart from one another in an overlapping region that overlaps the magnetosensitive portion as viewed in plan view from a direction orthogonal to the surface of the semiconductor substrate; and auxiliary wiring portions connecting each of the plurality of main wiring portions to one another in series.

Abstract: A foreign material detection apparatus has, between a transmitter coil of a power transmitting apparatus and a receiver coil of a power receiving apparatus between which power is transmitted contactlessly, a plurality of first detection coils arranged to be inductively couplable with each other and each constituting a resonant circuit having a first resonant frequency together with a first capacitor, a plurality of second detection coils arranged to be inductively couplable with each other and each constituting a resonant circuit having a second resonant frequency together with a second capacitor, a power supply circuit that supplies, to each detection coil, AC power having a frequency at which the detection coil resonates, and a detection circuit that detects foreign material contamination between the transmitter coil and the receiver coil according to a voltage of the AC power transmitted via the detection coils.

Abstract: Provided are a method for measuring the magnetic transformation rate of a steel sheet in an annealing furnace and an apparatus for measuring the same, and a continuous annealing process and a continuous galvanizing process which utilize the method and the apparatus. One such method includes delivering an alternating-current driving signal to the surface of the steel sheet by using an air-core driving coil having a size larger than, a width of the steel sheet, measuring the driving signal reflected by the steel sheet by using air-core receiving coils having a size larger than the width of the steel sheet, and determining the magnetic transformation rate of the steel sheet by using a measurement processing unit based on a distance between the steel sheet and the driving coil which has been corrected by using the measured values of the driving signal obtained by using the receiving coils.

Abstract: Methods and systems for outdoor advertising optimization and/or adaptive outdoor advertising are presented. One or more node signal receivers receive signals emitted by wireless network that are affected by physical phenomena such as reflections and scattering in the surrounding area. The received signals are processed to provide detection and tracking information regarding objects within a target volume. This information can then be employed to determine the optimal placement location or the optimal route for advertising platforms, and/or to select one or more advertisements on outdoor advertising platforms.

Abstract: In one embodiment, assessing the quality of an adhesive bond of a composite material includes passing a vector electric field through a thickness of the composite material, measuring dielectric properties of the composite material, determining one or more dielectric parameters of the composite material, and comparing the one or more dielectric parameters with one or more reference dielectric parameters.

Abstract: A metal detection system includes a detection module, a control module, a positioning module, and a computer module. The detection module includes an electromagnetic wave emitter that emits electromagnetic waves, and an electromagnetic wave receiver that senses electromagnetic signals emitted by underground metal in response to the electromagnetic waves emitted by the electromagnetic wave emitter. The control module processes the electromagnetic signals received by the electromagnetic wave receiver and generates metal detection data based on the received electromagnetic signals, or processes output signals provided by the detection module and generates metal detection data based on the output signals provided by the detection module. The positioning module generates information about positions of the metal detection device over time.

Abstract: Disclosed is an apparatus and method for generating virtual inspection channels mid-way between the physical inspection channels of an eddy current array probe, thereby reducing the coverage loss and improving defect sizing and imaging. The method is based upon a calibration to determine the mid-channel coverage loss for parallel defects having their long axis parallel to the scanning direction. Based on the coverage loss measurement, a vector analysis system is constructed enabling generation of virtual channel signals which are available for processing in the same way as physical channels, with impedance plane representation including real and/or imaginary signal components. The system differentiates between parallel and perpendicular defects and employs different algorithms to generate virtual channel signals for parallel and perpendicular defect orientations.

Abstract: A method and device for inspection of a rotating asset is disclosed. In one embodiment, the inspection device can include textured pattern projection system for projecting a textured pattern onto an object surface to provide additional surface details to improve stereoscopic image matching. In another embodiment, the inspection device can be configured to save selected images a rotating object when the object is located in a selected or trigger position in different illumination modes. The saved selected images can be transmitted and stored in a cloud-based server and analyzed in an automated fashion.

Abstract: A method includes introducing a pipe inspection tool into a first pipe positioned within a wellbore and further positioned within at least a second pipe. The pipe inspection tool includes an electromagnetic sensor having a coil antenna that includes a coil winding extending axially along at least a portion of the electromagnetic sensor. An excitation signal is transmitted between a first terminal and a second terminal of the coil antenna. A first response signal is measured between a third terminal and a fourth terminal of the coil antenna, wherein at least one of the third and fourth terminals is different from the first and second terminals. The first response signal is then processed to determine a characteristic of the first pipe.

Abstract: A conductor-mounted device (CMD) used to signal an intelligent electronic device (IED) of the existence of a fault on a portion of the electric power delivery system is described herein. The CMD may provide a heartbeat signal to the IED. The CMD may provide a fault signal to the IED. The CMD may be powered via a parasitic current draw on the conductor to which it is mounted. An IED may use a fault signal and/or LOC signal from a CMD to coordinate a high-impedance fault detection and/or downed line events.

Abstract: Inductive elements comprising anisotropic media and biasing coils for magnetically biasing thereof and methods of manufacture and operation for use in applications such as microelectronics. Application of an electrical current through the bias coils generates a magnetic field that biases the magnetic material such that a desirable orientation of anisotropy is achieved throughout the magnetic core and enables modulation of the inductive response of the device. Electrical conductors coupled to interconnects are magnetically coupled to magnetic core layers to produce self and/or mutual inductors.

Abstract: A metal detection apparatus has a passage channel (100) through which products (P) that may contain metal contaminants (C) pass. The apparatus has at least one transmitter unit (1) that provides transmitter signals to a transmitter coil (2) that is inductively coupled to a first and a second receiver coil (31; 32). The receiver coils are balanced and connected separately or combined to an input of a receiver unit (4). The transmitter coil has at least two coil sections (211, 212; 221, 222) that are arranged inclined to one another, with each coil section generating at least a first and a second magnetic field (My; MZ). Each of the first and the second receiver coils has at least a first coil section (311; 321) that is engaged in the first magnetic field and at least a second coil section (312; 322) that is engaged in the second magnetic field.

Abstract: Interrogation tools and methods are used to efficiently locate cable behind casing. The interrogation tool has at least one electromagnetic transmitter and receiver. An electromagnetic field is emitted from inside the tubular, whereby it interacts with the tubular and cable to produce a secondary electromagnetic field. The secondary electromagnetic field is measured by the receiver(s) from at least two different positions inside the tubular to produce corresponding response signals. The interrogation tool then compares the response signals to baseline response signals, whereby the position of the cable is determined. The electromagnetic measurements can be acquired simultaneously or sequentially.

Abstract: Electrically conductive proppants and methods for detecting, locating, and characterizing same are provided. The electrically conductive proppant can include a substantially uniform coating of an electrically conductive material having a thickness of at least 500 nm. The method can include injecting a hydraulic fluid into a wellbore extending into a subterranean formation at a rate and pressure sufficient to open a fracture therein, injecting into the fracture a fluid containing the electrically conductive proppant, electrically energizing the earth at or near the fracture, and measuring three dimensional (x, y, and z) components of electric and magnetic field responses at a surface of the earth or in an adjacent wellbore.

Abstract: A method for evaluating a uniformity of a magnetic field generated by a magnetic coil is disclosed. The method may include providing an electrical current to the magnetic coil to generate a magnetic field; scanning and obtaining a set of signals of the magnetic field by moving a measurement probe of a scanning tool point by point within a scanning region of the magnetic field and at a scanning height; performing a spectrum analysis on the set of signals by a spectrum analyzer to extract spectrum information of the magnetic field; transferring the set of signals and the extracted spectrum information to a computer system; selecting signals of the magnetic field with one or more frequencies from the set of signals based on the extracted spectrum information by the computer system; and analyzing the uniformity of the magnetic field by analyzing the selected signals by the computer system.

Abstract: An airborne electromagnetic survey system includes: a transmitter arrangement comprising at least one current source configured to connect with a transmitter coil arrangement, and a switch arrangement between the at least one current source and the transmitter coil arrangement, the switch arrangement configured to (1) connect the at least one current source with the transmitter coil arrangement to build up a connecting secondary electromagnetic field, and (2) disconnect the at least one current source from the transmitter coil arrangement to build up a disconnecting secondary electromagnetic field; and a receiver arrangement comprising at least one receiver coil; wherein the airborne electromagnetic survey system further comprises an additional transmitter coil arrangement and a switch arrangement controller, the switch arrangement controller configured to disconnect the at least one current source from the transmitter coil arrangement and the additional transmitter coil arrangement at substantially a same ti

Abstract: A planar sensor array capable of three-dimensional magnetic field sensing is disclosed. The sensor array may be utilized, for example, in connection with security inspections and detection of concealed electronics and contraband. Each sensor pixel may comprise a planar spiral inductor to measure a magnetic field of interest in a first dimension, a first Hall effect sensor to measure the magnetic field of interest in a second dimension, and a second Hall effect sensor to measure the magnetic field of interest in the third dimension.

Abstract: In one form, an acoustic signal is generated for an acoustic transducer, where the acoustic transducer is susceptible to reverberation that defines a close proximity indication zone. The start of a close proximity indication zone window is defined after the generation of the acoustic signal at a first time. During the close proximity indication zone window, a signal is received from the acoustic transducer. When the signal is received, an obstacle is detected in the close proximity indication zone if the magnitude of a first pulse received from the transducer at a second time is less than a first threshold but greater than a second threshold for a debounce time. Additionally, a magnitude of a second pulse received from the transducer outside the close proximity indication zone window at a third time should be less than the second threshold but greater than a third threshold for the debounce time.

Abstract: System and method for characterizing material condition. The system includes a sensor, impedance instrument and processing unit to collect measurements and assess material properties. A model of the system may be used to enable accurate measurements of multiple material properties. A cylindrical model for an electromagnetic field sensor is disclosed for modeling substantially cylindrically symmetric material systems. Sensor designs and data processing approaches are provided to focus the sensitivity of the sensor to localize material conditions. Improved calibration methods are shown. Sizing algorithms are provided to estimate the size of defects such as cracks and corrosion. Corrective measures are provided where the actual material configuration differs from the data processing assumptions. Methods are provided for use of the system to characterize material condition, and detailed illustration is given for corrosion, stress, weld, heat treat, and mechanical damage assessment.

Abstract: Transmitting node and receiving node for audio coding and methods therein. The nodes being operable to encode/decode speech and to apply a discontinuous transmission (DTX) scheme comprising transmission/reception of Silence Insertion Descriptor (SID) frames during speech inactivity. The method in the transmitting node comprising determining, from amongst a number N of hangover frames, a set Y of frames being representative of background noise, and further transmitting the N hangover frames, comprising at least said set Y of frames, to the receiving node. The method further comprises transmitting a first SID frame to the receiving node in association with the transmission of the N hangover frames, where the SID frame comprises information indicating the determined set Y of hangover frames to the receiving node. The method enables the receiving node to generate comfort noise based on the hangover frames most adequate for the purpose.

Abstract: Internal components of power generation machinery, such as gas turbine engines, are inspected with a spherical, optical-camera inspection system, mounted within a camera housing on a distal end of a compact diameter, single-axis inspection scope. The inspection scope includes nested, non-rotatable telescoping tubes, which define an extension axis. Circumscribing, telescoping tubes have anti-rotation collars, which are in sliding engagement with extension tracks on a circumferential surface of an opposing, nested tube, for ease of extension and retraction of the camera during visual inspections of power generation machinery. The camera is advanced and/or retracted along a scope extension axis by nested, drive tubes, which incorporate at least one external drive screw on a circumscribed drive tube and corresponding female threads formed in a circumscribing drive tube. The spherical camera has a 360-degree field of view, and captures images without rotation about the scope extension axis.

Abstract: An airborne electromagnetic survey system includes: a transmitter arrangement comprising at least one current source configured to connect with a transmitter coil arrangement, and a switch arrangement between the at least one current source and the transmitter coil arrangement, the switch arrangement configured to (1) connect the at least one current source with the transmitter coil arrangement to build up a connecting secondary electromagnetic field, and (2) disconnect the at least one current source from the transmitter coil arrangement to build up a disconnecting secondary electromagnetic field; and a receiver arrangement comprising at least one receiver coil; wherein the airborne electromagnetic survey system further comprises an additional transmitter coil arrangement and a switch arrangement controller, the switch arrangement controller configured to disconnect the at least one current source from the transmitter coil arrangement and the additional transmitter coil arrangement at substantially a same ti

Abstract: A method for performing continuous calibration of a magnetometer in a device includes during operation of a device, continually performing magnetometer measurements; continuously determining a state of the device; determining a magnetometer calibration model based on the magnetometer measurements and the state of the device; continually evaluating an accuracy of the magnetometer calibration model based the magnetometer measurements and the state of the device; and updating the magnetometer calibration model based on the evaluation of the accuracy magnetometer calibration model, the magnetometer measurements, and the state of the device.

Abstract: A circuit uses a high voltage diode to automatically block high voltage flyback pulses of either polarity from the transmit coil of a pulse induction type metal detector from its sensitive receive circuitry. The circuit being fully automatic requires no control signals and permits the receive circuitry to sample the signal being received immediately following the termination of the flyback pulse.

Abstract: A rotating magnetic field probe includes three (or more) windings that work in both transmit and receive mode, to form an eddy current detection transceiver. In a transmit mode, the windings are driven with a drive signal (e.g., an alternating current) having similar or the same magnitude at each winding, but differing in phase from one another. In a receive mode, the terminal voltages of the windings is measured and summed to determine the location of a defect.

Abstract: A coil device is provided having a member adapted to extend around and conform to an outer surface of a subject and a conductor adapted to extend only once around a first portion of the subject. The coil device can be positioned about the subject in order to measure a volume of the subject. When placed about the subject in the presence of a relatively homogeneous magnetic field, the conductor can generate a signal indicative of a volume of the first portion of the subject. The coil device may also include two or more conductors separately generating signals indicating volumes of two or more corresponding portions of the subject. In some cases the coil device includes associated authorization data that can limit use of the coil device. Systems and methods incorporating the coil device are also provided.

Abstract: Various embodiments include apparatus and methods to detect and locate conductive bodies and/or provide steam-assisted gravity drainage (SAGD) steering operation. Tools can be configured with receiving sensors (310) arranged to cancel substantially a primary signal associated with a probe signal without rotating the receiving sensors to cancel the primary signal and to capture a secondary signal generated from a conductive body (301) below the earth's surface. Additional apparatus, systems, and methods are disclosed.

Abstract: A balanced coil system (2) of a metal detection system has a transmitter coil (21) connected to a first transmitter unit (1), to provide a transmitter signal (s1) comprising at least first and second operating frequencies (fTX1, fTX2). First and second receiver coils (22, 23), which compensate one another when the system is in balance, provide output signals (s22, s23) to a receiver unit (3). The respective operating frequencies are applied separately together each with a monitoring frequency (fMON) to inputs of first and second modulation units (52, 53), which provide first and a second modulated monitoring signals (sM1, sM2), each comprising a first or second modulated monitoring frequency (fMM1, fMM2) without a carrier. When applied to a summation unit (54), the modulated monitoring signals result in a combined output signal (sM12) that is applied to a monitoring coil (24), inductively coupled with at least one of the receiver coils.

Abstract: A system and method for measuring volumes and areas using electromagnetic induction techniques. A current is generated and fed into one of two coil assemblies to induce voltage into another coil assembly to provide accurate values for volume or area.

Abstract: A system for generating a buffer zone around a buried asset at an above surface location is provided. The system includes an electromagnetic locator device for generating a plurality of buried asset data points via a plurality of radio frequency antennas. The system also includes a server for generating a plurality of connected line segments that represent a geographical position of the buried asset, wherein the plurality of connected line segments are generated by executing an optimization algorithm based on the plurality of buried asset data points, wherein the optimization algorithm: i) minimizes a total number of line segments, ii) minimizes a distance between a line segment and a corresponding buried asset data point, iii) minimizes instances of line segments that are parallel and iv) minimizes line segments shorter than a predefined threshold, and generates a first data structure that represents a two dimensional area comprising a buffer zone.

Abstract: Provided is a power receiving device including a power receiving coil which receives power supplied by electromagnetic waves, and a measurement coil which is disposed near the power receiving coil and measures an electromagnetic field.

Abstract: A metal sensor includes a primary coil arranged in a first plane, a first compensation coil arranged in a second plane, a second compensation coil arranged in a third plane, and a magnetic field sensor arranged in a fourth plane. The first plane, the second plane, the third plane and the fourth plane are oriented parallel to one another and perpendicular to a common z-direction in each case.

Abstract: A method for analyzing objects depending on their electromagnetic properties. The method including the steps of conveying the objects to be analyzed on a conveyer belt; scanning the electromagnetic properties of the objects and the conveyer belt by an electromagnetic sensor, wherein the electromagnetic properties of the conveyer belt are dependent on metallic contaminants which are stuck in the conveyer belt; generating belt properties data representing the electromagnetic properties of the conveyer belt, and analyzing the objects according to the scanned electromagnetic properties and the belt properties data. This has the benefits that the electromagnetic properties of the conveyer belt are considered when distinguishing between metallic and non-metallic objects which have to be sorted. This way, the objects which got stuck in the conveyer belt over time, may influence a sorting less, which may improve sorting results. Further, an apparatus for executing such a method.

Abstract: A probe for detecting magnetic particles. In one embodiment, the probe includes: a cylindrical probe core having a first end and a second end, the cylindrical probe core defining two channels for containing coils of wire, one of the channels being adjacent the first end of the cylindrical probe core; two sense coils, one each of the sense coils being located in a respective one of the channels; and two drive coils, one each of the drive coils being co-located with the respective sense coil in a respective one of the channels.

Abstract: A coil arrangement for a magnetic induction impedance measurement apparatus includes an excitation coil configured to generate a magnetic excitation field in an object, a shimming coil configured to generate a shimming field, and a detection coil configured to detect a magnetic response field generated in response to the magnetic excitation field inducing a current in the object. In order to enhance an accuracy of a determination of a parameter of an object, a value of a field strength of a net magnetic excitation field in the detection coil, being the sum of the excitation field and the shimming field, is approximately within a magnitude range of an average value of a field strength of the magnetic response field in the detection coil.

Abstract: Explosion-proof magnetic flux leakage inspection apparatus for well tubing includes a hermetically sealed interior chamber with an inner wall assembly that forms and surrounds a central channel in a manner that separates the central channel from the hermetically sealed interior chamber by the inner wall assembly. The central channel has an open top and an open bottom to accommodate passage of the well tubing through the central channel. An electromagnetic coil, magnetic flux leakage detector assembly, and a shallow reading detector assembly are positioned in the hermetically sealed interior chamber around the inner wall assembly.

Abstract: The method and sensor unit allow the location and detection of metallic or metal-containing objects and materials. A coil arrangement (1.2) comprises a transmission coil and a reception coil, which are arranged on top of one another, wherein the reception coil generates a reception coil output signal. A closed compensation control regulates the reception coil output signal in the receiving coil for compensating changes which occur in the detection range of the reception coil and influence the reception coil. To this end, compensation currents are fed into the receiving branch of the reception coil and are controlled relative to each other such that the reception coil output signal or average values which are detected from the reception coil output signal after demodulation are continuously regulated relative to each other to zero even in the case of metal influence. As a result, a coil with an unregulated transmission current can be used, in which a zero output signal is continuously generated.