Abstract: An apparatus for automatically correcting phase shifts in a nuclear magnetic resonance (NMR) spectrum. The apparatus comprises first and second phase correction means. The first phase correction means corrects phase shifts due to measurement delay, phase shifts due to a frequency filter, and phase shifts due to off-resonance effects. The second phase correction means corrects constant terms of the phase shifts. Where the spectrum is a multi-dimensional NMR spectrum, the first phase correction means corrects the phase shifts on the directly observed axis. The first phase correction means corrects the phase shifts due to the measurement delay and the phase shifts due to the off-resonance effects on the indirectly observed axis. The second phase correction means corrects the phase shifts only on the directly observed axis. This construction permits automatic corrections of the phase shifts without relying on spectroscopist's eye, individual intuition or experience.

Abstract: An apparatus for measuring conductivity of earth formations penetrated by a wellbore including a magnet for inducing a static magnetic field in the earth formations penetrated by the wellbore. The apparatus includes means for generating a radio frequency magnetic field in the wellbore and the earth formations, means for selectively varying a frequency of the radio frequency magnetic field, and means for receiving a nuclear magnetic resonance signal from excited nuclei in the earth formations. The means for receiving includes means for measuring a difference in phase between the magnetic resonance signal and the radio frequency magnetic field. The phase difference measured is related to the conductivity of the earth formations.

Abstract: Methods and apparatus are described to produce stick-slip motion of a logging tool within a cased well attached to a wireline that is drawn upward by a continuously rotating wireline drum. The stick-slip motion results in the periodic upward movement of the tool in the cased well described in terms of a dwell time during which time the tool is stationary, the move time during which time the tool moves, and the stroke that is upward distance that the tool translates during the "slip" portion of the stick-slip motion. This method of measurement is used to log the well at different vertical positions of the tool. Therefore, any typical "station-to-station logging tool" may be modified to be a "continuous logging tool", where "continuous" means that the wireline drum continually rotates while the tool undergoes stick-slip motion downhole and measurements are performed during the dwell times when the tool is momentarily stationary.

Abstract: A magnetostrictive linear displacement transducer includes an elongated member of a material with a large magnetostriction coefficient. There is a coil and a pulse driver for magnetizing the member to cause a detectable magnetostrictive effect for short discrete periods of time. A magnet is movable along the path adjacent the member and is capable of magnetizing a localized portion of the member adjacent the magnet efficiently to cause an alteration in the magnetostrictive effect in the localized portion in concert with the pulse driver and the coil. There is a piezoelectric device at one end for detecting axial strain pulses propagated along the member caused by the magnetostrictive effect. There is a comparator for measuring time lags between initiation of each separate discrete period of time and detection of a corresponding strain pulses by the piezoelectric device and thereby a position of the magnet along the path.

Abstract: A system and method for determining fiber-depth of at least one layer of reinforcing fibers within an electrically conductive workpiece is provided. The system comprises an eddy current probe having one or more eddy current elements for generating a respective electrical signal indicative of a spacing with respect to a predetermined section of the reinforcing fibers. A signal processor is connected to the eddy current probe to receive and to process each spacing-indication electrical signal so as to generate data indicative of fiber-depth of the predetermined section relative to a workpiece surface. A display device may be connected to the signal processor to provide visual indicia representative of the fiber depth. Further a controller may be connected to receive and store the fiber-depth data which can be used by a machining device for selectively removing material from the workpiece surface, in accordance with the stored fiber-depth data.

Abstract: A magnetostrictive wire waveguide type position measuring system wherein the wire waveguide is mounted within a small diameter brass tube which, in turn, is mounted by way of resilient suspension components within a rigid outer tube affixed to a position reference frame. The suspension components isolate the waveguide from relatively high frequency shock inputs characteristic of rough environment applications. The position signal is derived from output signal quantities generated by the propagation times of sonic disturbances from a first reference magnet held in a fixed position relative to the outer housing and a second user magnet which moves relative to the outer housing with the element or quantity being monitored.

Abstract: In order to measure the permeability of a magnetic material, a permanent magnet is positioned at a distance from the surface of a magnetic material. A first magnetic field sensor is placed proximate the magnetic material on the magnetic axis of the permanent magnet. The axis of sensitivity of the magnetic field sensor is perpendicular to the field of the permanent magnet and in a plane perpendicular to the surface of the magnetic material. A second magnetic field sensor for compensating for temperature and stray field effects can be positioned perpendicular to the magnetic axis of the permanent magnet with its axis of sensitivity parallel to the axis of sensitivity of the magnetic field sensor.

Abstract: A magnetic resonance imaging superconducting magnet including a cryostat, a gradient coil and superconducting gradient shield positioned around the gradient coil with an active resistive shimming member contiguous to the cryostat vessel; and the gradient shield being selectively cooled to superconducting operation after the magnetic shimming fields generated by the shimming member for field homogeneity within the bore of the magnetic resonance imaging magnet are induced onto, and maintained by, the superconducting gradient shield and operation of the resistive shimming member discontinued.

Abstract: A method of measuring motion properties of nuclei within pore spaces of a porous medium. The method includes applying a static magnetic field to the medium to polarize the nuclei, generating a first magnitude of magnetic field gradient within the pore spaces of the medium, applying a radio frequency magnetic field to excite the nuclei, receiving nuclear magnetic resonance signals from the nuclei, and calculating the motion properties from rates of decay of the amplitude of the nuclear magnetic resonance signals.

Abstract: A magnetic resonance (MR) multislice method, in which in each cycle nuclear magnetization is successively excited in a respective group of measuring slices which are situated at a distance from one another and the MR signals generated under the influence of at least one gradient magnetic field are acquired, is such that the groups of measuring slices excited in different cycles exhibit a spatial offset relative to one another which is smaller than the distance between the measuring slices excited in a cycle and the gradient magnetic fields are varied from one cycle to another. The nuclear magnetization distribution in a reconstruction slice is reconstructed from the MR signals acquired in the various cycles and originating from measuring slices which neighbour one another in space and are situated to both sides of the reconstruction slice.

Abstract: Apparatus for detecting ferromagnetic debris in a fluid medium in a container includes a plug attachable to the container and having an associated magnetic field preferably produced by a permanent magnet. The plug is at least partly exposed to the fluid to capture debris in the fluid. The apparatus further includes a portable sensor for optically sensing the captured debris, with the sensor having a probe that is connectable to the plug. A method for using such apparatus is provided, and in general a method of detecting ferromagnetic particles in a fluid medium in a container includes the steps of: a) magnetically capturing particles from the fluid using a plug with the container, and b) interrogating the plug with light for captured particles using a portable probe.

Abstract: An RF coil tuning circuit is disclosed in which two banks of parallel capacitive branches are provided. Each capacitive branch includes a fixed value capacitor, a relay and a PIN diode connected in series. An impedance of the tuning circuit is adjusted to the optimum VSWR=1 condition by first switching the eight PIN diodes to learn which open/closed condition applies the fixed value capacitors in the optimum combination. Then, the PIN diodes are all closed and the optimum combination is applied using the open/closed states of the relays.

Abstract: A nondestructive inspection device and a method of monitoring a defective condition in a rotating member of a combustion turbine engine using a nondestructive inspection device is presented. The nondestructive inspection device includes a sensor for monitoring the rotating member and a holder assembly for positioning the sensor near the rotating member without disassembling the combustion turbine engine. The holder assembly is capable of interchangeably positioning either an ultrasound transducer or an eddy current sensor. Signals indicative of the monitored condition are recorded and compared to a signal representation generated from a reference standard having a known defect so that a defective condition can be ascertained. The location of a defective condition is ascertained by using a magnetic belt having a plurality of magnets wrapped around the rotating member and an additional sensor to detect the magnets as they rotate.

Abstract: Flux of magnetic field generated from an object P of magnetic measurement, which links with the pick-up coils of the fluxmeters, where the flux is converted into electrical signals by each of the SQUID chips driven by the FLL circuits. The electrical signals are sent to the data collection unit via the signal processing circuit. In the data collection unit, the electrical signals are converted into digital data by the A/D converter. The converted digital data are recorded on a hard disk or a magnet-optical disk or the like, of the data recording section. The digital data recorded on the data recording medium are compensated with use of a crosstalk compensation matrix so as to remove the interference due to crosstalk for each channel, by the crosstalk compensation section. The compensated data are displayed directly on the display in the form of a magnetic field distribution or time waveform, and sent to the data analysis section.

Abstract: A gradient coil system for the production of a magnetic transverse gradient field G.sub.x =dB.sub.z /dx in an NMR tomograph has axial and transverse access to the measuring volume. The gradient coil system consists of four partial coils (S.sub.1x, S.sub.2x, S.sub.3x, S.sub.4x) each with two current connections (A.sub.1, A.sub.2), which are arranged mirror symmetrically with respect to the xy-plane (z=0) and mirror symmetrically with respect to the zy-plane (x=0). Each partial coil comprises winding sections on an inner and on an outer cylinder Z.sub.1x, Z.sub.ax) about the z-axis as well as on a radial connecting surface V.sub.+x, V.sub.-x and the radial connecting surfaces V.sub.+x, V.sub.-x of those partial coils (S.sub.1x, S.sub.4x ; S.sub.2x, S.sub.3x,) which face each other opposite the xy-plane are essentially identical. An axial gap for free transverse access to the measuring volume remains between the partial coils.

Abstract: A sealed, modular downhole antenna for measuring electrical characteristics of wellbore fluids and formations. An antenna includes a thin-walled curved metal tube, which houses coil of a length of conductive wire. The wire may be insulated by an insulating coating, as well as a filler that resides in the tube. The tube includes a coupling gap, to facilitate coupling electromagnetic energy through the tube, to and from the conductive wire. The tube also has a wall opening, for ends of the wire to attach to an adapter-connector. The adapter-connector includes suitable features for modular connection to an electrical cable, electrical connectors, or other electrical equipment. Features of the invention may be provided to ensure that such connection is resistive to the high pressures that are often encountered downhole. In this respect, the tube may be also coated with a sealant layer, to hermetically seal the tube, coupling gap, and junction between the adapter-connector and the tube.

Abstract: A method for surveying terrain uses transient magnetic fields transmitted from a coil in plane parallel to and above the terrain, transient voltage response from vertically spaced receiver coils coaxial with and parallel to the transmitter coil being processed to detect highly conductive objects buried in the terrain, with the ratio of the response of the coils optionally being used to estimate the depth of objects. The responses from the coils are scaled in a predetermined ratio to provide cancellation of the response from objects in a layer of terrain at a particular depth, which layer may be at the surface to remove surface responses, or beneath the surface so as to allow surface objects to be differentiated from deeper objects by providing responses of opposite polarity.

Abstract: A system for detecting metal targets located in a background environment such as the ground evaluates metal targets by processing components of signals at two or more different frequencies. A component of the received signal induced by the ground can be eliminated by subtracting signal components measured at two different frequencies. The received signal can be processed to account for changes in the background response with frequency. The type of an unknown target can be identified by processing background excluded components to produce data characterizing the target type.

Abstract: A Hall transducer produces a signal Vsig. Threshold voltages V.sub.Pth and V.sub.Nth are generated at the beginning, t.sub.update, of each of a succession of update time intervals, of 64 pulses in Vsig, to be fixed percentages respectively of the peak to peak voltage in Vsig. A proximity-detector binary output voltage is high when Vsig exceeds threshold voltage V.sub.Pth and low when Vsig is below threshold voltage V.sub.Nth. Signals V.sub.Pold and V.sub.Nold, generated by first and second DACs, are equal to the first positive and negative peaks in Vsig after each time t.sub.update initiating the start of a successive interval. Signals V.sub.Pnew and V.sub.Nnew, simultaneously generated by third and fourth DACs, are equal to the greatest positive and negative peak voltages in Vsig during the interval ending at t.sub.update. Counters present their count to the first and second DACs that count pulses from a clock for tracking and holding +/- peaks in Vsig. After each time t.sub.

Abstract: A method and a device for monitoring rotational speed sensors, in particular rotational speed sensors for identifying the wheel speed, are described. A fault is detected if a slip coefficient which is weighted with the time exceeds a threshold value.