Abstract: A composite shell adapted to cover a source or sensor, particularly for subsurface applications. The shell provides transparency to the passage of signals to or from the source or sensor. The shell is adapted with a uniform semi-conductive surface providing a path for electric currents flowing within a subsurface borehole to short near the source or sensor.

Abstract: An object is to automatically detect the positions of spike noise, create a distribution diagram, and perform pass/fail decisions. The cross-correlation function of the signal waveform from a magnetic head 1 and a reference waveform simulating spike noise is used in extraction of spike noise. The number of peaks in the cross-correlation function exceeding a threshold value is counted, and quantitative evaluation of spike noise is performed.

Abstract: A magnetic sensor includes a magnetic sensitive member 11 including an amorphous wire, a detection coil 12 wound around the magnetic sensitive member 11, and a sample-and-hold circuit for detecting a voltage induced in the amorphous wire 11 when a pulse current is interrupted. The sample-and-hold circuit has a sample-and-hold unit B31 and a delay circuit. The sample-and-hold unit B31 includes an electronic switch S31, a capacitor C32, a resistor R32, a resistor R33, and a high-input amplifier A31. The delay circuit includes a resistor R31 connected to a control terminal of the electronic switch S31 and a capacitor C31.

Abstract: A rotation sensor provides a control with an indication of shaft position. The sensor utilizes a magnetic connection between a cam follower and a transducer. The magnetic connection eliminates problems in the prior art such as degradation due to wear and corrosion. In particular, a rotating shaft carries a cam. The cam drives a cam follower. As the cam follower moves, a magnet moves. The transducer can sense movement of this magnet. In preferred embodiments, the cam follower is driven to pivot and the magnet is mounted on the pivot point of the cam follower. The present invention is disclosed for use in motorcycle throttle handles, accelerator pedals, brake pedals, and detecting shaft position for valve timing.

Abstract: A novel magnetic imaging microscope test system with high spatial (1–10 nm) and temporal (˜1 ns) resolution of the magnetic field is disclosed, as well as the system application for characterization of read and write heads for magnetic recording. The test system includes a scanner assembly and a work piece holder for holding a work piece to be tested. The scanner assembly and the work piece holder are positionable relative to each other at very fine resolution during scanning. A probe arm is cantilevered from the scanner assembly to bring a probe head into close proximity to the work piece holder. The probe head is configured scan a work piece in contacting engagement therewith so that a magnetic device on the probe head magnetically interacts with a magnetic field generating or magnetic field sensing device on the work piece. A probe head for use in the test system and a related test method are also disclosed.

Abstract: A well logging tool and method are disclosed comprising a conductive mandrel, an antenna array disposed around the conductive mandrel, wherein the antenna array comprises a plurality of antennas disposed on insulating supports and at least one contact spacer, the at least one contact spacer having at least one conductor channel having a contact assembly disposed therein, a sleeve disposed over the antenna array, wherein the sleeve includes at least one electrode assembly, the at least one electrode and the contact assembly adapted to provide a radially conductive path from an exterior of the well logging tool to the conductive mandrel and wherein the electrode assembly comprises a first conductor exposed to the exterior of the well logging tool and at least one second conductor conductively connected to the first conductor and exposed to an inner surface of the sleeve, wherein at least one of the first conductor or the second conductor being in sealed contact with the sleeve to prevent the passage of fluid th

Abstract: A subsurface imaging cable includes a plurality of sensor modules, wherein the plurality of the sensor modules are flexible and each of the plurality of the sensor modules is spaced apart on the subsurface imaging cable at a selected distance; and a flexible medium connecting the plurality of the sensor modules, wherein the subsurface imaging cable is flexible and adapted to be wound on a reel. A method for subsurface images includes acquiring direct-current measurements at a plurality of sites in a survey area; acquiring a first set of electric and magnetic measurements from natural electromagnetic fields at the plurality of sites; acquiring a second set of electric and magnetic measurements using controlled electric and magnetic sources at the plurality of sites; and determining a subsurface conductivity distribution from the direct-current measurements and the first set and the second set of electric and magnetic measurements.

Abstract: A magnetoelectric magnetic field sensor has one or more laminated magnetostrictive layers and piezoelectric layers. The magnetostrictive layers are magnetized by a bias magnetic field in a longitudinal, in-plane direction. The piezoelectric layers can be poled in the longitudinal direction or perpendicular direction. The longitudinal magnetization of the magnetostrictive layers provides greatly increased sensitivity at lower bias fields compared to other magnetoelectric sensors. Perpendicular poling of the piezoelectric layers tends to provide higher sensitivity at lower detection frequency (e.g. less than 1 Hz). Longitudinal poling tends to provide higher sensitivity at high detection frequency (e.g. above 10 Hz). Also included are embodiments having relative thicknesses for the magnetostrictive layers that are optimized for sensitivity. Equations are provided for calculating the best relative thickness for the magnetostrictive layer for maximum sensitivity.

Abstract: The encoder rotor of an absolute magnetic encoder mounted on a servomotor shaft has a first drum of a bipolar magnet, and a second drum with a Q-bit multipolar magnetic pole track and a reference track. A signal processor generates absolute signals on the basis of detected signals, which differ in phase by 90° and in which a single rotation represents a single period, from X-phase and Y-phase magnetic sensors disposed facing the first drum, and on the basis of A- and B-phase signals, which differ in phase by 90°, and a reference signal obtained from A-, B-, and Z-phase magnetic sensors disposed facing the second drum. Even if the number of bits Q of the multipolar magnetic pole track is increased in order to enhance the resolution, the number of magnetic pole tracks does not need to be increased, and higher resolution can therefore be obtained without increasing the axial length.

Abstract: A magnetic position sensor has a stator (16?, 36, 52) formed of magnetic material and a pair of magnets (14a, 14b; 34a, 34b; 54a, 54b; 64a, 64b) rotatably mounted about the stator and movable between opposite angular extremities and spaced from the stator by a primary cylindrical air gap (5). A secondary air gap (4) is formed in a stationary member at a location at which the magnetic field varies with the angular position of the magnets. A first Hall Effect sensor (18) is disposed in the secondary air gap to measure the magnetic field there-across as an indication of the angular position of the magnets. A second reference sensor (22) is provided to detect the magnetic decay of the magnets. The second sensor can be a Hall Effect sensor disposed at a location at which the magnetic field is relatively constant, independent of the angular position of the magnets. The reference sensor output can be used as a diagnostic indicator or as a correction for the first sensor output.

Abstract: A method and apparatus for use within a borehole for simultaneously determining the horizontal resistivity, vertical resistivity, and relative dip angle for anisotropic earth formations. An antenna configuration in which a transmitter antenna and a receiver antenna are oriented in non-parallel planes such that the vertical resistivity and the relative dip angle are decoupled. Preferably, either the transmitter or the receiver is mounted in a conventional orientation in a first plane that is normal to the tool axis, and the other antenna is mounted in a second plane that is not parallel to the first plane. Also included are a method and apparatus for steering a downhole tool during a drilling operation in order to maintain the borehole within a desired earth formation. The steering capability is enabled by computing the difference or the ratio of the phase-based or amplitude-based responses of the receiver antennas which are mounted in planes that are not parallel to the planes of the transmitter antennas.

Abstract: A magnetic sensor unit includes an actuator motor and a magnetic position sensor. The actuator motor has a magnetic circuit including motor magnets. The magnetic position sensor includes a sensor magnet and a hall element for detecting magnetic flux. Magnet clearances are formed between the motor magnets. The hall element is disposed outside of the motor to detect the magnetic flux in a direction penetrating through the magnet clearances, and which is perpendicular to a direction from one of the motor magnets to the other. In this disposition of the hall element, it is restricted that the hall element detects leaking magnetic flux from the motor magnets.

Abstract: A rotary input for a linear variable differential transformer (LVDT) system connects to a gear reduction system. The gear reduction produces a reduced rotary output in a rotary output member. The output member is threaded, and a nut is threaded onto the output member. Therefore, the nut translates as the rotary output member rotates. The armatures of one or more LVDTs attach to the nut. Each armature contains a magnetic member. As the nut translates along the threaded output member, the nut translates the armatures. Armature movement moves the magnetic members to create a differential voltage between the secondary coils of the LVDT.

Abstract: A rotary position sensing system and method are disclosed, including a shaft comprising an offset mounting hole, and a magnet having a magnetic field that is magnetized across an axis of the magnet, wherein the magnet is mounted to the shaft at the offset mounting hole and oriented to the offset mounting hole. One or more Hall-effect sensing elements can also be located a fixed distance from the magnet to provide a linear output signal proportional to the magnetic field of the magnet and the angular position of the shaft, thereby providing an angular position measurement of a device mated to the shaft.

Abstract: The invention provides an apparatus for measuring the magnetic field strength between the magnet arrays of an insertion device in an X-ray generating system comprising a magnetic field strength sensor that produces an output signal, three stages for positioning the sensor along the X, Y and Z axes of the insertion device, means for controlling positions of the stages and information storage means for reading the output signal operably connected to the sensor. The apparatus eliminates the need for a dedicated measurement facility by mounting guide means for the long (Z-)axis directly to the insertion device. This long-axis guide means can be permanently or temporarily mounted to the insertion device. The remainder of the measurement apparatus may then be transferred onto the long-axis guide means while measurements and, if necessary, adjustments are made. The apparatus is compact, allowing greater access to magnet arrays for adjustment than existing systems.

Abstract: The invention provides an improved method and device for inspecting heat exchanger tubes from within the tube inside diameter that overcomes the shortcomings of the prior art. It adapts a guided-wave probe approach that makes use of a torsional wave mode instead of a longitudinal wave node disclosed in the prior art. The torsional wave mode has many advantages over the longitudinal wave mode for detecting defects. When energized by suitable instrumentation, the probe is caused to generate a torsional mode signal that is transmitted to the heat exchanger tube from the waveguide tube. When reflected signals from defects in the heat exchanger tube walls are returned to the inspection opening end of the heat exchanger tube, the reflected defect signals are transmitted to the probe waveguide tube for amplification, detection and characterization of the reflected signal.

Abstract: In a weak-magnetic field sensor a rectangular ring-shaped magnetic core is wound by exciting circuit patterns and detecting circuit patterns, and weak-magnetic field sensors are implemented in x-axis and y-axis directions, respectively, to precisely calculate azimuth, thereby sensing a weak-magnetic field having a strength similar to that of earth's magnetic field. The sensor includes a magnetic core having first and second cores connected in parallel to each other; exciting coils wound around the first and second cores, respectively, to supply alternating excitation current to the magnetic core; and a detecting coil alternately arranged together with the exciting coils on the same surfaces on which the exciting coils are formed, and wound around the first and second cores, in order to detect variation of magnetic fluxes generated in the magnetic core.

Abstract: An omnidirectional eddy current (EC) probe includes at least one EC channel having a first and a second sense coil that are offset in a first (x) and a second (y) direction and overlap in at least one of the directions (x,y). At least one drive coil is configured to generate a probing field for the EC channel in a vicinity of the sense coils. An omnidirectional EC inspection system includes an omnidirectional EC array probe (ECAP) that includes a number of EC channels and drive coils. Each EC channel includes first and second sense coils with opposite polarities. The drive coils have alternating polarities. Electrical connections perform differential sensing for respective EC channels. Corrective drive coils are disposed at respective ends of the EC channels and generate probing fields. An eddy current instrument is connected to the omnidirectional ECAP and receives differential sensing signals from the EC channels.

Abstract: A device for adjusting rotation angles, e.g. an electrical rotary switch (1), has a stator (2) and a rotator (3) mounted on the stator (2). The rotator (3) rotates between at least two rotational angle positions. The device has a magnet (4), e.g. a permanent magnet, which can be moved by the rotor (3), and a magnet field sensor (5), e.g. a Hall sensor, which together with the magnet (4) produces a signal which corresponds to the rotational angle position. The stator (2) has a receptacle (8) open on one side and shaped like a pot, with the receptacle (8) forming a rotating bearing for the rotator (3). The magnetic field sensor (5) is arranged in the receptacle (8) on the stator (2) and/or on a part which is mounted on the stator (2), such that the stator is a mount for the magnet field sensor (5).

Abstract: A rotation angle detector for improving the detection accuracy of a rotation angle has a movable shaft, a bearing portion for pivotably bearing against the movable shaft, a detection portion for detecting a rotation angle of the movable shaft, and a supporting portion for supporting the detection portion. The bearing portion and the supporting portion are integrally formed of the same material. As a result, since the bearing portion and the supporting portion are accurately aligned with each other, displacement of the movable shaft with respect to the detection portion can be prevented. Thus, the detection accuracy of the movable shaft rotation angle can be improved.