An aerosol generating device according to an embodiment includes a heater generating an aerosol by heating an aerosol generating substrate; a controller for controlling power supplied to the heater; at least one detachable element that is attachable to and detachable from an inner space or an outer space of the aerosol generating device; and a plurality of geomagnetic sensors for detecting changes in the strength of an internal magnetic field of the aerosol generating device, wherein the controller detects detachment of the detachable element based on a detection result from at least one of the plurality of geomagnetic sensors.

An aerosol generating device according to an embodiment includes a heater generating an aerosol by heating an aerosol generating substrate; a controller for controlling power supplied to the heater; at least one detachable element that is attachable to and detachable from an inner space or an outer space of the aerosol generating device; and a plurality of geomagnetic sensors for detecting changes in the strength of an internal magnetic field of the aerosol generating device, wherein the controller detects detachment of the detachable element based on a detection result from at least one of the plurality of geomagnetic sensors.

Disclosed is a magnetotelluric measurement system, comprising: a magnetic sensor probe for collecting an electromagnetic signal as an impulse response of an earth and transmitting the same to a signal readout circuit; the signal readout circuit configured for receiving and amplifying the electromagnetic signal collected by the magnetic sensor probe; a data acquisition and processing module configured for receiving and processing electromagnetic signal amplified by the signal readout circuit; a storage module configured for storing the electromagnetic signals amplified by the signal readout circuit and processed by the data acquisition and processing module; a first casing for enclosing the magnetic sensor probe and the signal readout circuit; and a second casing for enclosing the data acquisition and processing module and the storage module. The disclosure realizes the detection of low-noise wide-frequency band magnetic field signal, and solves problems involving deep detection of the mineral resources in complex areas.

Disclosed is a magnetotelluric measurement system, comprising: a magnetic sensor probe for collecting an electromagnetic signal as an impulse response of an earth and transmitting the same to a signal readout circuit; the signal readout circuit configured for receiving and amplifying the electromagnetic signal collected by the magnetic sensor probe; a data acquisition and processing module configured for receiving and processing electromagnetic signal amplified by the signal readout circuit; a storage module configured for storing the electromagnetic signals amplified by the signal readout circuit and processed by the data acquisition and processing module; a first casing for enclosing the magnetic sensor probe and the signal readout circuit; and a second casing for enclosing the data acquisition and processing module and the storage module. The disclosure realizes the detection of low-noise wide-frequency band magnetic field signal, and solves problems involving deep detection of the mineral resources in complex areas.

A method for correcting geomagnetic reference field includes measuring Earth magnetic field elements at least one known geodetic position. Earth magnetic field elements are measured at a position proximate the location. A disturbance function is determined from the Earth magnetic field measurements made at the at least one known geodetic position. A magnetic disturbance field measurement transfer function is estimated between the at the at least one known geodetic and proximate positions to estimate a disturbance function at the proximate position. The estimated magnetic disturbance function is used to correct geomagnetic reference field or measurements made at the location.

A method for correcting geomagnetic reference field includes measuring Earth magnetic field elements at least one known geodetic position. Earth magnetic field elements are measured at a position proximate the location. A disturbance function is determined from the Earth magnetic field measurements made at the at least one known geodetic position. A magnetic disturbance field measurement transfer function is estimated between the at the at least one known geodetic and proximate positions to estimate a disturbance function at the proximate position. The estimated magnetic disturbance function is used to correct geomagnetic reference field or measurements made at the location.

A transient electromagnetic device with variable shape and turns includes squares, a transmitting coil carrying frame, a transmitting coil, a turns-variable device, a current generator and a working power supply. The transmitting coil carrying frame is arranged inside the transmitting coil; the transmitting coil carrying frame is configured as a carrier of the transmitting coil, and configured for adjusting a side length of the transmitting coil and a shape of the transmitting coil; the square is configured for clamping and connecting the transmitting coil and the transmitting coil carrying frame to fix the transmitting coil to the transmitting coil carrying frame. The current generator is configured for generating transient current; the turns-variable device is configured for changing the turns of the transmitting coil; and the transmitting coil is configured for transmitting the transient current to a target area to be measured.

A transient electromagnetic device with variable shape and turns includes squares, a transmitting coil carrying frame, a transmitting coil, a turns-variable device, a current generator and a working power supply. The transmitting coil carrying frame is arranged inside the transmitting coil; the transmitting coil carrying frame is configured as a carrier of the transmitting coil, and configured for adjusting a side length of the transmitting coil and a shape of the transmitting coil; the square is configured for clamping and connecting the transmitting coil and the transmitting coil carrying frame to fix the transmitting coil to the transmitting coil carrying frame. The current generator is configured for generating transient current; the turns-variable device is configured for changing the turns of the transmitting coil; and the transmitting coil is configured for transmitting the transient current to a target area to be measured.

A method and system for detecting a subsurface tunnel includes propelling an instrumented pipeline pig through a horizontal detection conduit, acquiring and analyzing magnetometer measurements and VLF EM resistivity measurements to detect distortions and/or anomalies in the Earth's magnetic field and/or VLF electromagnetic field, respectively, and correlating the data with position data of the pipeline pig to compute a parameter of a tunnel such as, for example, location, size and depth.

A method and system for detecting a subsurface tunnel includes propelling an instrumented pipeline pig through a horizontal detection conduit, acquiring and analyzing magnetometer measurements and VLF EM resistivity measurements to detect distortions and/or anomalies in the Earth's magnetic field and/or VLF electromagnetic field, respectively, and correlating the data with position data of the pipeline pig to compute a parameter of a tunnel such as, for example, location, size and depth.