Abstract: A radio mode selectivity block 41 for a detector 1 for detecting a buried current carrying conductor comprises a plurality of beat frequency oscillators 53 to center the bandwidth of detection of the detector 1 on target very low frequency (VLF) frequency bands. The frequencies of the beat frequency oscillators are chosen to fall within the VLF frequency bands used in a number of countries, so that the detector 1 can be used in radio mode in these countries without the need for local configuration.

Abstract: There is described an inductive position sensor in which a signal generator applies a excitation signal to an excitation winding formed on a first member, the excitation winding being electromagnetically coupled to at least two resonant circuits formed on a second member which are spaced from each other along a measurement path. The excitation windings are shaped so that the electromagnetic coupling between the exciting winding and each of the resonators varies along the measurement path. In this way, by applying an excitation signal to the excitation winding, respective different signals are induced in the resonators which depend upon the relative position of the first and second members.

Abstract: An apparatus serves to sense the absolute value of the rotational position of a shaft (14). The apparatus has a first single-turn rotary encoder (30) that is arranged at one end (20) of the shaft (14) and is arranged to sense the latter's rotational position within a single shaft revolution. Also provided are: a multi-turn rotary encoder unit which senses the number of revolutions of the shaft (14) and which comprises a reduction gear linkage (18); a rotary element (42), driven by the output of the linkage, that is oriented as an imaginary continuation of the shaft (14) and coaxially therewith; and a second single-turn rotary encoder (48) which is arranged to sense the rotational position of the rotary element (42) within a single revolution. The reduction gear linkage (18) surrounds the shaft (14), and its output element (38) is connected, via a connecting member (40), to said rotary element (42) around the first single-turn rotary encoder (30).

Abstract: A tandem rotation detector is provided for effectively preventing the occurrence of leakage flux between rotation angle detection mechanisms so that high-precision detection can be always realized. The tandem rotation detector of the present invention includes a first rotation angle detection mechanism 2A configured to generate a magnetic flux through a coil 11A of a first outer core 10A provided inside a cylindrical housing 1 for detecting the rotation angle of a rotary shaft 4A arranged in the central portion of the housing 1, and a second rotation angle detection mechanism 2B, placed side by side with the first rotation angle detection mechanism 2A, and configured to generate a magnetic flux through a coil 11B of a second outer core 10B provided inside the housing 1 to detect the rotation angle of a rotary shaft 4B, in which current flows through the coil 11A of the first outer core 10A and the coil 11B of the second outer core 10B in different directions from each other.

Abstract: Disclosed are a rotation angle detection device including: a stator provided with a one-phase excitation winding and two-phase output windings; and a rotor having salient poles, and a dynamo-electric machine using the same. The two-phase output windings are wound around a plurality of teeth of the stator, and respective numbers of turns of the two-phase output windings are obtained by using m-phase windings (m is an integer of 3 or more) imaginarily defined to convert the numbers of turns of the m-phase windings into those of two-phase windings. Thus, since the number of phases decreases compared with the case in which the windings are structured with m phases, a structure is simplified, and a manufacturing process is facilitated.

Abstract: A scale that includes a first base body having a first non-magnetizable support and a first set of magnetic elements that are arranged laterally next to the first non-magnetizable support, are magnetized in a single identical direction and are arranged in a measuring direction. A second base body having a second non-magnetizable support and a second set of magnetic elements that are arranged laterally next to the second non-magnetizable support, are magnetized in the single identical direction and area arranged in the measuring direction. The first base body and the second base body are put together such that in the measuring direction alternating ones of the first and second sets of magnetic elements are arranged and the first and second sets of magnetic elements have different magnetic orientations with respect to each other.

Abstract: Exemplary embodiments of the invention provide a sensor attachment mechanism capable of attaching a position detecting sensor having directivity in a proper direction to a fluid pressure cylinder having a rail extending along the length of a cylinder tube on the outer surface thereof. Embodiments include a position detecting sensor for sensing the operating position of a piston is attached with a sensor holder to a grooved rail extending along the length of a cylinder tube on the outer surface thereof. The position detecting sensor has directivity in magnetic detection. The sensor holder includes a base mounted on the rail and a sensor holding part extending from the base. The sensor holding part is close to or in contact with the surface of the cylinder tube outside rail walls.

Abstract: A geophysical prospecting method and apparatus that utilizes the harmonics and sub harmonics waves induced into the earth by the electric power grid. The amplitude-frequency data are converted to amplitude-depth data and further converted to a differential curve. The resulting differential curve is compared to known patterns of the interested geological features, such as hydrocarbon reservoir, to identify whether the features exist and at what depth such geological features lie.

Abstract: A device for evaluating magnetic component performance and methods of evaluating transient magnetic performance of such components are disclosed. Magnetic flux capacity and/or energy loss of a magnetic component is/are measured, and the measurement data is electronically processed to evaluate the magnetic performance of the component.

Abstract: An underground prospecting method and apparatus that utilizes the harmonics and fractional harmonic waves induced into the earth by the electric power grid. The data are converted to amplitude-depth and phase-depth data. The resulting data may be plotted and are compared to known patterns of the interested underground features, such as hydrocarbon, water, minerals and cavities, to identify whether the features exist and at what depth such underground features lie.

Abstract: A multimeter includes a body portion, a cover pivotally connected to the frame such that the cover is selectively moveable about a rotational axis between an open position and a closed position, and a probe assembly including a pair of measuring lines connectable to the frame. The cover includes a magnetic portion on an exterior surface thereof that is configured and positioned to magnetically mount the body portion for use in an inclined relation to a metal surface when the cover is in the open position, and to magnetically mount the body portion to a metal surface when in the closed position.

Abstract: An airborne exploration system used with an aircraft for exploration of oil and gas, mineral deposits and aquifers. The survey system uses natural electromagnetic EM fields as an energy source. The exploration system includes at least one non-directional, wideband, total electric field, water sensor. The water sensor includes a water container filled with water and adapted for mounting on an aircraft. The water container has a pair of conductive metal bands mounted around opposite ends thereof. The metal bands provide a capacitive electrical coupling with the water in the container. The water container has a diameter substantial the size as a length of the container. Therefore, the sensor responds to an electric field substantially independent of the relative orientation of the electric field. The bands are electrically connected to a computer data processing unit mounted on the aircraft.

Abstract: A rotation angle detector for detecting a relative rotation angle of two respective parts includes two sensors, two magnetic flux induction devices as well as a magnetic flux generation unit. Variation in the magnetic flux formed in respective gaps of the two magnetic flux induction devices is detected by using the two magnetic sensors for detecting a relative rotation angle of the two parts.

Abstract: Material properties such as stress in a ferromagnetic material may be measured using an electromagnetic probe. While generating an alternating magnetic field in the object, and sensing the resulting magnetic field with a sensor, the signals from the magnetic sensor may be resolved into in-phase and quadrature components. The signals are affected by both geometrical parameters such as lift-off and by material properties, but these influences may be separated by mapping the in-phase and quadrature components directly into material property and lift-off components, and hence a material property and/or the lift-off may be determined. The mapping may be represented in the impedance plane as two sets of contours representing signal variation with lift-off (A) (for different values of stress) and signal variation with stress (B) (for different values of lift-off), the contours of both sets (A, B) being curved. The stress contours (B) intersect any one liftoff contour (A) at a constant angle.

Abstract: A rotation angle detection device capable of easy selection of detection gears is provided to detect a rotation angle of a main gear. The device includes first and second detection gears each rotatable in conjunction with the main gear, a first magnetic sensor for detecting a rotation angle of the first detection gear, a second magnetic sensor for detecting a rotation angle of the second detection gear, and a microcomputer for detecting the rotation angle of the main gear on the basis of the rotation angle detected by the first magnetic sensor and the rotation angle detected by the second magnetic sensor. The periodicity from the first magnetic sensor and the periodicity of the second magnetic sensor are set to be prime to each other. Further, the teeth number of the first magnetic sensor is set to be a numeric value obtained by multiplying the periodicity of the first magnetic sensor by a predetermined integral number.

Abstract: A method and an apparatus for structural diagnosis, which generates torsional waves upon a shaft, beam or pipe having arbitrary cross-sections, such as a circular cross-section, and senses existence or location of the cracks through analyzing reflected waves are disclosed. A magnetostrictive transducer comprises a plurality of ferromagnetic strips attached around a circumference of a member having a arbitrary cross-section with a fixed inclination; a first housing disposed to surround the ferromagnetic strips, the first housing being made of insulating material; and a coil would around the first housing. The magnetostrictive transducer can generate torsional waves upon a member when a current is supplied to the coil, and can measure reflected torsional waves.

Abstract: A two-wire type current output sensor includes two external connection terminals to one of which a power supply flows from an outside and from the other one of which the power supply flows to the outside, a detecting element capable of outputting a detection signal, a signal processing circuit for changing a current supplied to a power supply side of the signal processing circuit based on the detection signal of the detecting element and outputting the changed current, and a connection switching circuit for switching a connection between the two external connection terminals and the signal processing circuit such that one of the external connection terminals at a higher voltage is connected to the power supply side of the signal processing circuit while the other one of the external connection terminals at a lower voltage is connected to an output side of the signal processing circuit.

Abstract: In a fluxgate sensor integrated in a semiconductor substrate and a method for manufacturing the same, the fluxgate sensor includes a soft magnetic core formed on the semiconductor substrate, an excitation coil winding the soft magnetic core and being insulated by first and second insulating layers deposited above and below the soft magnetic core, respectively, and a pick-up coil, winding the soft magnetic core and being insulated by third and fourth insulating layers deposited above and below the excitation coil, respectively.

Abstract: A method is disclosed for determining spatial distribution of resistivity of Earth formations surrounding a wellbore having a conductive pipe therein. The method includes measuring resistivity of the Earth formations using measurements of current leakage along the pipe at selected axial positions. Electromagnetic properties of the Earth formations are measured from within the pipe. The measurements of electromagnetic properties correspond to a larger axial distance and to a greater lateral distance than the measurements of resistivity from current leakage. The current leakage and electromagnetic measurements are jointly inverted to obtain a model of the spatial distribution.

Abstract: A method and an apparatus of a magnetic field sensor structure are disclosed. The magnetic field sensor structure is formed by a bridge of four magnetoresistors (1–4), wherein each magnetoresistor has a longitudinal direction, and each magnetoresistor (1–4) is polarised by magnets (15–19). Also, each magnet has a main magnetisation field along an axial magnetisation direction, and a magnetic leakage field. The polarisation magnets (15–19) and the magnetoresistors (1–4) are arranged in the form of layers on the same substrate. In one embodiment, the polarisation magnets (15–19) are at the same level as the magnetoresistors (1–4) wherein the polarisation magnets (15–19) have the same main magnetisation direction, which is contained in the plane of the layers. The magnetoresistors have their longitudinal direction parallel with that of the axial direction of the magnets. In one embodiment, two magnetoresistors are arranged in the axial field of magnets and two others are in the magnet leakage field.