A measurement device applies a pulse current or a current of a plurality of frequencies to a laminated body having a plurality of layers having different electrical conductivities. The device acquires in-plane distribution information indicating distribution of a magnetic field of a first plane outside the laminated body. A processor generates three-dimensional magnetic field distribution information indicating a three-dimensional distribution of magnetic field on an outside of the laminated body based on the in-plane distribution information, and generates information on an inside of the laminated body by processing the three-dimensional magnetic field distribution information on the outside of the laminated body. The in-plane distribution information includes information indicating response characteristics to a change in the current applied by the current applying unit. In addition, the three-dimensional magnetic field distribution information on the outside of the laminated body includes frequency characteristics of the magnetic field.

An electromagnet for a thermography system comprising a first elongated magnetic core spaced apart from a second elongated magnetic core; at least a first shorting bar connecting substantially at a first end of the first elongated magnetic core and a first end of the second elongated magnetic core; and at least a first excitation coil configured to conduct electrical current.

According to one embodiment of the invention, a magnetic sensor includes a first sensor part. The first sensor part includes a first magnetic member, a first counter magnetic member, and a first magnetic element. A direction from the first magnetic member to the first counter magnetic member is along a first direction. The first magnetic element includes one or a plurality of first extending portions. A first portion of the first extending portion overlaps the first magnetic member in a second direction crossing the first direction. A first counter portion of the first extending portion overlaps the first counter magnetic member in the second direction. A first direction length along the first direction of the first extending portion is longer than a third direction length along a third direction of the first extending portion. The third direction crosses a plane including the first direction and the second direction.

The present disclosure provides a construction structure corrosion measurement sensor having accuracy higher than that of conventional sensors, and a method for measuring corrosion by using the same. To this end, the present disclosure provides a sensor assembly including an eddy-current sensor including an insulator a coil surrounding the outer periphery of the insulator. The present disclosure also provides a construction structure corrosion measurement method including the steps of: positioning a sensor assembly next to a rebar inside a construction structure in parallel with and adjacent to the rebar; applying a voltage to the sensor assembly; measuring a voltage generated by an eddy current resulting from the adjacent rebar; and conducting measurement at a predetermined time interval so as to measure a voltage change.

There is provided a sensor unit for a fastener assembly, the sensor unit comprising a mounting arranged to rigidly attach the sensor unit to, or adjacent to, a fastener assembly; and a sensor, that is an optical flow sensor or an inductive sensor, configured to sense movement of the fastener assembly. The sensor unit may comprise a processor arranged to process the output of the sensor to detect loosening of the fastener assembly and to output a signal representing the status of the fastener assembly. The sensor unit may comprise a wireless communication unit arranged to communicate the signal.

A probe 100 includes exciter units 102 arranged in an array and detector units 104 and 106, also arranged in arrays, with the arrays positioned proximal to and in the shape of the exterior circumference of an individual boiler tube 108. The detector units 104 are “absolute” coil detectors which are used to detect and quantify general wall loss, for example, resulting from steam impingement erosion. The detectors 106 are differential, axial pairs which are used for detecting pits in the boiler tubers. The exciter units and detector units are mounted in a stainless steel housing 110 of the probe. The housing 110 is shaped to closely match the contour of the boiler tube 108. The probe can be moved along the boiler tubes by hand to inspect the flame side of boiler tubes, one at a time. Wheels 112 are provided to roll the probe along the boiler tubes.

An embodiment identifies a cause of change in magnetic permeability of an object under inspection and evaluates the state of surface treatment(s) of the object under inspection with high accuracy. An embodiment of the method includes preparing a non-destructive inspection apparatus; placing the object under inspection; generating eddy current in the object under inspection; continuously changing the penetration depth of an AC magnetic field in the object under inspection; calculating the value of impedance at each penetration depth in the object under inspection; and evaluating the state of the surface treatment(s) by: calculating the ratio between the value of impedance at each penetration depth in the object under inspection and the value of impedance at a corresponding penetration depth in steel which has not been subjected to a surface treatment; and identifying a cause of a change in magnetic permeability of the object under inspection based upon the calculated ratio.

An eddy current sensor for detecting an eddy current that can be generated in a wafer includes a magnetic core. The core has a base, a central wall provided on the base in the center of the base in a first direction, and end walls provided on the base at either end portion of the base in the first direction. The eddy current sensor includes exciting coils which are disposed on the end walls and which generates an eddy current in the wafer, and a detecting coil which is disposed on the central wall and which detects the eddy current.

A form-fitting eddy current array probe for inspecting helical gears is provided, the probe comprising: a leg which includes a sensor zone with a plurality of eddy current arrays; an arm attached to and normal with the leg to provide an L-shaped probe, the arm including a sensor zone with a plurality of eddy current arrays; a resilient layer underlying the sensor zones; a gel layer attached to an upper surface of the sensor zones, the gel layer including a fluid gel and an outer covering encasing the fluid gel; and an encoder distally located on the leg. A method of inspecting a girth gear set including a helical gear and a girth gear using the form-fitting eddy current array probe is also provided.

A probe 100 includes exciter units 102 arranged in an array and detector units 104 and 106, also arranged in arrays, with the arrays positioned proximal to and in the shape of the exterior circumference of an individual boiler tube 108. The detector units 104 are “absolute” coil detectors which are used to detect and quantify general wall loss, for example, resulting from steam impingement erosion. The detectors 106 are differential, axial pairs which are used for detecting pits in the boiler tubers. The exciter units and detector units are mounted in a stainless steel housing 110 of the probe. The housing 110 is shaped to closely match the contour of the boiler tube 108. The probe can be moved along the boiler tubes by hand to inspect the flame side of boiler tubes, one at a time. Wheels 112 are provided to roll the probe along the boiler tubes.