117 results about "Secondary field" patented technology

Systems and methods are provided for the detection of conductive bodies using three-component electric or magnetic dipole transmitters. The fields from multiple transmitters can be combined to enhance fields at specific locations and in specific orientation. A one- two- or three-component receiver or receiver array is provided for detecting the secondary field radiated by a conductive body. The data from multiple receivers can be combined to enhance the response at a specific sensing location with a specific orientation. Another method is provided in which a three-component transmitter and receiver are separated by an arbitrary distance, and where the position and orientation of the receiver relative to the transmitter are calculated, allowing the response of a highly conductive body to be detected.

An exterior rearview mirror assembly for a motor vehicle includes a mounting bracket securable to a lateral side of a vehicle. A mirror case is secured to the mirror bracket. A primary reflector is fixedly secured to the primary portion of the backing plate. The primary reflector defines a primary field of view extending laterally away from the lateral side of the motor vehicle. A secondary reflector defines a secondary field of view extending laterally in space disposed adjacent the lateral side of the motor vehicle, wherein the secondary field of view overlaps the primary field of view in a range of 20% to 80%. The field of view of the secondary reflector is also directed downwardly with respect to the field of view of the primary reflector.

The invention relates to a transient electromagnetic measurement device which comprises a transmitting antenna coil, a receiving antenna coil and a zero setting antenna coil which are parallel to each other. The transmitting antenna coil and the zero setting antenna coil are connected in series. Magnetic flux penetrating through the receiving antenna coil of a primary field generated by the transmitting antenna coil and the zero setting antenna coil is equal to zero or close to zero all the time, the primary field strength of a detection region below a receiving point is ensured, accordingly, the transient process of induction generated by a receiving antenna when emission current is off is eliminated or weakened, the signal to noise ratio of a secondary field signal of an underground medium sensed by the receiving antenna is increased greatly, and high-precision transient electromagnetic detection is achieved.

The invention relates to a transient electromagnetic ground hole detection method and device for detecting hidden objects to cause disasters, wherein a large transmitting loop surrounding a target stratum completely is arranged on the ground; electricity is supplied, so that a primary electromagnetic field is generated, and in a hole drilled along the stratum underground, a three-component secondary field around the hole is directly received. Transmitting is separated from receiving. Interference of local good electric conductors, industrial electromagnetic signals, periodic electric signals and the like on the ground can be avoided. Besides, the shielding influence of a low-resistivity layer or a low-resistivity mineralized zone on the surface of the stratum can be avoided. A receiving device is placed in the drilled hole so that a complex construction environment outside the hole can be avoided, for example, heading equipment, anchor rods, anchor nets, transportation equipment, industrial electricity and the like exist in a coal mine roadway.

The invention discloses a transient electromagnetic response signal horizontal component measuring method and an observation device thereof. A transmitting coil (4) is designed to be provided with two mutually perpendicular symmetry axes. A plane is perpendicular to one symmetry axis and passes through the other symmetry axis to form a reference plane (1). The vertical reference plane (1) is parallel to the first symmetry axis to form a receiving coil winding cylindrical surface (6). A receiving coil (2) is continuously wounded on two sides of the reference plane (1) towards the same direction with the receiving coil winding cylindrical surface (6) as a datum. Finally, signals of the transmitting coil (4) and the receiving coil (2) can be measured and calculated. Through adoption of symmetry of primary-field horizontal component signals of the symmetrical transmitting coil, primary-field induction signals in the receiving coil are mutually canceled so that secondary-field horizontal component signals can be reserved and signal to noise ratio (SNR) of secondary response signal measurement of transient electromagnetism can be guaranteed. Consequently, resolution capability of an exploration system is improved. The transient electromagnetic response signal horizontal component measuring method and the observation device thereof can be applied to the transient electromagnetic exploration field such as in the aviation field, in the ocean field, on the ground and in wells and roadways.

There is provided a method for combining datasets, comprising: receiving a primary training dataset; receiving unclassified secondary dataset(s) comprising secondary data instances including secondary fields; identifying, for a first set of values of primary field(s) of training dataset, a second set of secondary fields of the secondary datasets according to the first set of values matched to corresponding values in respective secondary field(s) of secondary dataset(s) according to a matching requirement; linking each respective matched values to other secondary fields of the respective matched secondary field; generating a set of classification features based at least on the linked secondary fields; selecting a subset of pivotal classification features according to a correlation requirement; identifying a subset of pivotal secondary fields based on the secondary fields associated with each pivotal classification feature; and documenting the selected subset of pivotal features for use in an automated machine learning process.

A method for electrical survey of hydrocarbons deposits under seabed depths up to 1500 m and equipment therefor are provided. The equipment includes a vessel, a generator, an excitation field block, connected with a vertical dipole with coax electrodes, a data registration / processing block, bottom systems with. The lower dipole electrode is situated at maximally 100 m from the seabed, the upper electrode at maximally 200 m from the surface. The operation of the generator and bottom systems is synchronized the dipole is submersed into the sea, and fed with alternating-sign rectangular current pulses, whose on-off time ratio and duration are programmably determined. The bottom systems register reflected signals and electromagnetic field components, when the dipole's current is on and off. Analysis of the signals accounts modifications of primary and secondary fields, transient field changes for determination of the environment resistivity and strata polarization characteristics thereby improving the hydrocarbons deposits prognosis.

The present disclosure discloses a mine transient electromagnetic (TEM) three-component detection method. TEM transmitting coils and receiving coils are adjusted according to geological features in a coal mine. Depending on different measurement manners, the number of magnetic-field lines cut by a low-resistance body greatly varies, and thus the strength of the resulting secondary fields also greatly varies. The present disclosure uses three sets of receiving coils that are arranged perpendicular to each other. One of the three sets of receiving coils and a transmitting coil are arranged according to a coincident loop device, such that response data in all directions can be received from a single transmission. At an underground roadway head, fan shape scan is achieved by changing angles of the transmitting coil and the receiving coils, to obtain more electromagnetic responses, such that a water-rich region in the formation can be more accurately determined.

A three-dimensional inversion method for airborne transient electromagnetic conductivity based on the Bornn iterative method, involving electromagnetic exploration. Provide a set of three-dimensional conductivity inversion algorithm based on the frequency domain to improve the calculation speed of the inversion; the algorithm uses the fitting of the secondary field value to perform the inversion calculation, thereby removing the influence of the ground response of the direct wave on the signal and improving the inversion calculation speed. Acting precision. Firstly, the time-domain signal of the total field is obtained from the transient electromagnetic system, and then the time-domain response of the corresponding theoretical uniform half-space is calculated to extract the secondary field signal required for the inversion. First use the electric field integral equation to solve the electric field distribution in the calculation area, and calculate the secondary field value through the definition of the contrast function. Then use the Born iterative method to establish the inversion process, fit the secondary field values ​​in the frequency domain, and iteratively solve the contrast function, so as to obtain the distribution of the medium in the underground calculation area, and realize the three-dimensional inversion of the conductivity of the transient electromagnetic system. play.

The invention relates to an electrical resistivity correcting method for a mine transient electromagnetic method. The method includes 1, placing an emitting coil at a measurement point position, setting a transmit-receive distance as TR1, acquiring a primary field value as indicated in the description and a secondary field value containing mutual inductance electro-dynamic potential as indicated in the description through instrument data collection; 2, keeping the position of the emitting coil unchanged, increasing the transmit-receive distance to TR2, acquiring primary field value as indicated in the description and a secondary field value containing mutual inductance electro-dynamic potential as indicated in the description through instrument data collection; 3, putting collected data into a correction formula as indicated in the description for cancelling the mutual inductance electro-dynamic potential, and obtaining a ground secondary field signal V2; 4, performing whole-area apparent resistivity calculation and time depth conversion on the secondary field signal V2 subjected to mutual inductance electro-dynamic potential cancelling and obtaining an apparent resistivity-depth curve. According to the invention, electrical resistivity correction is performed by utilizing transmit-receive distance observation data of two different processes and mutual inductance signals are cancelled, the valid ground secondary field signal is extracted and a problem of electric resistivity distortion caused by using the mine transient electromagnetic method can be solved well. Since the detection depth is in direct proportion to and the electric resistivity, the detection depth of the mine transient electromagnetic method is improved.

A method and apparatus for magnetic field drift compensation for a superconducting magnet system includes electrically coupling a micro-flux injection system to a secondary B0 superconducting coil in a secondary compensation circuit; magnetically coupling the secondary compensation circuit to the superconducting magnet via the secondary B0 superconducting coil; switching the micro-flux injection system on and off either thermally or magnetically to induce a first current from a flux coil of the secondary compensation circuit into the secondary B0 superconducting coil producing a secondary field to compensate magnet field drift of the superconducting magnet.

The invention relates to a transient electromagnetic ground hole detection method and device for detecting hidden objects to cause disasters, wherein a large transmitting loop surrounding a target stratum completely is arranged on the ground; electricity is supplied, so that a primary electromagnetic field is generated, and in a hole drilled along the stratum underground, a three-component secondary field around the hole is directly received. Transmitting is separated from receiving. Interference of local good electric conductors, industrial electromagnetic signals, periodic electric signals and the like on the ground can be avoided. Besides, the shielding influence of a low-resistivity layer or a low-resistivity mineralized zone on the surface of the stratum can be avoided. A receiving device is placed in the drilled hole so that a complex construction environment outside the hole can be avoided, for example, heading equipment, anchor rods, anchor nets, transportation equipment, industrial electricity and the like exist in a coal mine roadway.