Abstract: A detector of ferromagnetic materials having a permanent magnet floating in a contaier and restrained under the influence of a soft ferrite mass spaced below it to rotatable movement about a vertical axis centrally of the container. The magnet has a normal at rest position from which it is rotatable when a ferromagnetic material moves through its magnetic field. The magnet carries a curved mirror onto the concaved face of which a light beam is focused, and which beam in an at rest normal position of the magnet is reflected by the mirror onto a zero point of an observer's readout scale. When the magnet is caused to rotate from its at rest position by a ferromagnetic material moving through its magnetic field, the light beam is caused to move away from the zero point; and when the ferromagnetic material has moved out of the magnetic field, the magnet and light beam return to their normal positions but with some oscillation before doing so.

Abstract: For use with automatic machinery for packaging a food product in foil pouches and then inserting a desired number of pouches in a box, a method and apparatus for scanning the boxes to check for missing pouches. The scan is accomplished by applying like alternating magnetic fields through each box and through the foil used to make the pouches at a point upstream from where the pouches are formed. Detected field absorption associated with the upstream foil is used as a reference, and the difference between it and detected field absorption associated with a box is proportional to the number of pouches in the box. The apparatus can detect if one out of two, one out of three, or one out of four is missing, and compensates the differential signal for variations in foil thickness by multiplying the reference signal by N-1, where N is desired pouch count per box. If a pouch is missing from a box, a signal is generated which can be used to trigger a rejection mechanism to remove the short-count box.

Abstract: A system for helically driving an inspection probe within a tube of a nuclear steam generator is provided, wherein the system is particularly useful in driving a combination eddy-current and ultrasonic probe. The system generally includes a head assembly insertable with the tube for inspection, a drive frame assembly to be located external of the steam generator, and a conduit system connecting the head assembly and drive frame assembly. Particularly, the head assembly includes a portion fixable to the tube by a pressure bladder and a movable portion helically movable with a probe to the fixable portion. The drive motor and electrical pick-up are slidably movable on the drive frame assembly to move linearly with the probe during inspection so as not to limit the stroke of the probe, wherein the drive motor and pick-up are connected with the head assembly by way of two flexible coaxial conduits.

Abstract: A magnetic signal pickup mechanism is presented. The mechanism comprises an orbiting mass fixedly coupled to a cyclically repetitively moving element which by moving through its cycle causes the mass to orbit. A relatively tight but slightly moveable wire is coupled to selected points at each end so as to pass near at least one part of the orbit of the mass. One of the mass and the wire is ferro magnetic and the other of the mass and the wire is a permanent magnet sufficiently powerful so that the wire moves one cycle in an orbit in response to each orbit of the mass. A signal detector is coupled to the wire to count orbits of the wire.

Abstract: Method, according to the eddy current method, for checking damage on the surface of round, e.g., ball-shaped, metal objects, whereby a similar object is supported and made to rotate around at least one axis while an electronic contact-free scanner or sensor is aimed at the surface of the object, characterized by the fact that the round object is placed on a fixed support and a gaseous medium, e.g., air is blown against the object in such manner that between the support and the object a gas or air layer is formed which carries the object, and the object is made to rotate by the gas or air flow.

Abstract: In a system for determining the relative position of a first object with respect to a second object, electrical detection of registration is achieved. This registration can be used during the manufacture of printed circuit boards or discrete wiring boards to determine the registration between layers of wiring, or between wiring layers and printed circuit layers. The system introduces an a.c. current at a suitable frequency into at least one first conductive pattern wired or etched or otherwise provided near the perimeter of a printed or wired first layer of a circuit board panel. The panel having the first pattern is moved relative to similarly wired second conductive patterns on a second layer or base plate, mounting table, etc., to which detection circuits are connected. Voltage induced in the second patterns is detected and indicates the positional relationship between the first and second conductive patterns and, hence, objects associated with such patterns.

Abstract: An inductive pickup assembly senses the electromagnetic fields of plural ignition elements of an automotive engine, access to which elements is prevented by associated engine housing structure. The pickup assembly includes a frame having a flat platform on which multiple sensors are mounted, each sensor comprising an electromagnetic pickup coil with a magnetizable metal core integral with a magnetizable metal shield plate which covers one end of the coil. The frame has a support member with depending feet having apertures which mate with fasteners on the housing structure to serve as a template for accurately locating the pickup assembly on the housing structure.

Abstract: The rotation type absolute encoder of the present invention is constituted by a magnetic type one-pulse encoder for detecting one or more rotations, and an optical type absolute encoder comprising a plural number of aspheric LED lens as a light source, a group of detecting elements corresponding to the area of the light source, a slit disc beginning from the track of two slits, and a differential input type current-to-voltage convertor. This absolute encoder is also so constructed as to back up the circuit voltage by an external battery and an internal large capacitance capacitor when a current is cut, and has a circuit for serially transmitting a signal indicating the number of rotations and the absolute angle to an external controller, and a circuit for synthesizing and outputting one reference pulse per rotation from the signals of the magnetic type one-pulse encoder and the optical type absolute encoder.

Abstract: Measurement of a physical property such as coercive force of a member to be inspected is performed at a plurality of locations in one region of the member. Similar measurement is performed in a plurality of different regions of the member and a maximum or minimum value (extreme value) is determined for each of the regions. On the basis of the extreme values thus determined, a recurrence period is determined in accordance with an extreme value statistic theory with the aid of a computer, whereon an estimated maximum value of the physical property of the member as a whole is determined from the recurrence period. On the basis of the estimated maximum value, the degree of deterioration of the member is predicted by the computer by consulting the data indicating the previously determined relation between the physical property and the degree of deterioration.

Abstract: In a method for nondestructive measurement of the heat affected zone of an identification code on a nuclear fuel rod tube, the change in impedance of an electromagnetic coil produced by a portion of the tube to be etched with a bar code is measured before and after the etching of the bar code is performed by use of laser power. The impedance change in the coil produced by the bar code-bearing tube portion is compared with the impedance change produced in the coil by the same tube portion before the bar code is generated thereon to determine whether a maximum allowed depth of the heat affected zone of the tube portion has been exceeded.

Abstract: Apparatus and method for precisely controlling the movement of a magnetostrictive transducer including an elongated magnetostrictive rod, means for inducing a magnetic field in the rod and supplying drive current for moving the rod in response to the drive current. A temperature compensated strain sensor configuration on the rod detects the amount of rod movement in response to the drive current and provides an output signal proportionate thereto. Feedback control means coupled between the strain sensor and the current driver respond to the strain sensor output signal and vary the drive current until the strain sensor output signal matches the voltage reference set point developing the drive current.

Abstract: A magnetic speed sensor air gap fault-detection arrangement having a two-input AND gate for each of the two-axle trucks of a railway vehicle for conditioning a gap process circuit common to each axle. Each of the gap process circuits of each axle is activated to provide a logical "1" output to an associated two-input AND gate. The associated two-input AND gates each outputs a logical "1" to a respective gap counter circuit when the axle rate reaches a predetermined value. The respective gap counter circuits count the logical "1's" and activate an associated gap fault check circuit to reset the respective gap counter circuit and to display an error code and to output a logical "1" signal to the dynamic diagnostic apparatus.

Abstract: A method employing torque magnetometry for measuring magnetic properties of a workpiece, for example, measuring the anisotropy of a magnetic thin film. The present method utilizes a novel alternative to known methods of torque magnetometry, namely, employing a viscometer, as modified in accordance with the present invention. The present method preserves all the virtues of torque magnetometry, yet realizes method objectives of efficiency, low cost, and accurate measurement.

Abstract: Both an apparatus and a method for simultaneously inspecting the walls of a tube with both ultrasonic and eddy current probes is disclosed herein. The apparatus generally comprises a cylindrical housing assembly insertable within the tube to be inspected, and a probe carrier rotatably mounted within and helically movable with respect to the housing. The probe carrier holds three ultrasonic probes for transmitting ultrasonic beams which are directly oriented radially, chordally, and axially with resepect to the longitudinal axis of the tube, as well as an eddy current probe for simultaneously inspecting the walls of the tube with electromagnetic lines of flux. The apparatus further includes a helical drive train formed from a lead screw assembly having a motor means, a drive shaft, and a drive sleeve for imparting a helical scanning motion to the probe carrier with respect to the housing.

Abstract: A device for eddy current testing of tubes of a heat exchanger having a U-shape tube bundle includes a test sensor having an insertion tip and a longitudinal axis. Elastic hose pieces are connected to the insertion tip. At least three coils are disposed along the elastic hose pieces. A pusher hose is connected to the elastic hose pieces. A pusher device is connected to the pusher hose for inserting the pusher hose into a tube of a tube bundle. The coils have contact surfaces each extending over only a portion of the inner periphery of the tube of the tube bundle. The coils are staggered about the circumference of the test sensor and are staggered along the longitudinal axis of the test sensor. A location recognition unit is disposed in the test sensor.

Abstract: A gap sensor comprising a C-type core (38, 62, 126) wrapped with a coil (44, 68, 130), and arranged to be responsive to the variable reluctance in a magnetic circuit passing through the core, two refiner plates (28a, 28b, 194, 198) and the gap (34, 90) between the plates. The two sensing ends (134, 136) of the transducer core legs (128, 132) are positioned in close proximity to the circumferential surfaces, or rims (82, 86, 212, 214) of the two spaced apart refiner plates, respectively. The magnetic field generated by the coil follows a magnetic path or circuit including the core (38), the radial gaps (46), between the sensor and the discs (16, 18), the refiner disc material, the plates (28a, 28b) mounted on the disc, and the clearance gap (34) between the two refiner plates.

Abstract: The present invention discloses a single sensor performing both tactile and proximity sensing. The sensor includes a magnetic field generator, a magnetic field sensor for sensing changes in the magnetic field in response to an object changing position with respect to the field to provide proximity sensing. By providing for relative movement between the response to the object touching the sensor, tactile sensing is provided.

Abstract: A system for photoinductive imaging for flaw detection of materials and for calibrating eddy-current probes includes positioning an eddy-current probe adjacent to a specimen to be analyzed or to be used as a calibration fixture. A source of thermal energy is modulated and focused to a localized area on the specimen. Thermal energy is then scanned across at least a portion of the detection area of the eddy-probe. The resulting signal from the eddy-current probe is recorded and can depict either thermal-influenced components of the specimen or the response pattern of the eddy-current probe. The record can therefore be used to image flaws or physical holes or shapes of the specimen or calibrate the eddy-current probe.

Abstract: A system and method for nondestructively inspecting and monitoring materials that indicates the structural integrity of the material is disclosed. The inspection method includes the following steps. First, the material to be subsequently monitored, is tagged by dispersing a small amount of finely divided particles throughout the material. The tagged material is then applied in accordance with its application, such as adhesive material to two pieces to be joined to form an adhesive joint. When the adhesive joint or other material is to be inspected, the tagged particles are activated to cause an inherent structural resonance in the tagged material. The activation and structural resonance of the material is then monitored and measured with a probe. Finally, the structure resonance of the material is related to the structural integrity of the adhesive joint, the matrix-reinforcement interface integrity of a composite material, or the state of cure of a resin.

Abstract: An improved non-contact type pattern sensor includes a magnetic resistor element arranged facing a pattern track on a recoridng medium having a magnetized pattern in the pattern track. A clearance sensor is arranged to face the pattern track on the recording medium and generates a detection signal as a function of the distance between the clearance sensor and the pattern track. The control unit connected to the clearance sensor generates an output signal which varies as a function of the detection signal. A magnetic field generator connected to the control unit is arranged near the magnetic sensor element and generates a bias magnetic field whose intensity varies as a function of the output signal.

Abstract: A method and apparatus for measuring dynamic head and track misregistration in, for example, a magnetic disk file. A reference signal waveform is recorded onto a track on a recording medium. The track has a center line and an off-center line parallel to the center line. The recorded reference signal waveform is read a plurality of times with the transducer centered approximately above the off-center line of the track to produce a plurality of off-track playback signal waveforms. A track misregistration signal waveform is produced by computing the difference between one off-track playback signal waveform and the average off-track playback signal waveform.

Abstract: The invention relates to a novel apparatus for detecting as well as quantifying superconductivity characterized by a rigid-stemmed pendulum used to support the superconductive sample for free-swinging movement about a low-friction fulcrum in a magnetic field effective to swing the pendulum to one side, connecting both a first mechanism to the pendulum operative to sense the movement of the pendulum and generate a signal proportional thereto along with a second mechanism effective to receive such a signal from the first mechanism and react thereto in a manner to null the movement of the pendulum along with the sample suspended therefrom, and, finally, connecting a signal processing mechanism into the system whereby the signal generated by the first mechanism is quantified as a measure of the superconductive properties of the sample.

Abstract: A cantilever beam is employed to place a magnet in proximity to a sample while the sample is maintained at a superconducting temperature. The magnet causes the sample, assuming it is superconductive, to itself generate a magnetic field which interacts with the magnet. Means are provided for measuring the movement of the cantilever beam, such movement being a measure of the interaction of the sample's magnetic field with the magnet. Several types of cantilever beams are disclosed, one of which is adapted to move in a direction orthogonal to the surface of the sample and another of which is adapted to move parallel to the surface of the sample. This enables the obtaining of quantitative measurements of the bulk properties of high temperature superconducting materials.

Abstract: A method and apparatus for testing steel components for temper embrittlement uses magneto-acoustic emission to nondestructively evaluate the component. Acoustic emission signals occur more frequently at higher levels in embrittled components. A pair of electromagnets are used to create magnetic induction in the test component. Magneto-acoustic emission signals may be generated by applying an AC current to the electromagnets. The acoustic emission signals are analyzed to provide a comparison between a component known to be unembrittled and a test component. Magnetic remanence is determined by applying a DC current to the electromagnets, then turning the magnets off and observing the residual magnetic induction.

Abstract: In accordance with this invention, a noncontacting sensing system (12) is disclosed for providing information regarding the gap between, and relative position of, two relatively movable elements such as a vehicle (14) and a guideway (16). As its main component, the system (12) includes an array (64) of four sensor assemblies (66). Each assembly (66) defines a target magnetic loop (T), which includes adjacent discrete pole pieces (28) in the guideway (16), and a separate reference magnetic loop (R). Hall-effect pickups (84) employed in the two loops (T and R) provide information regarding the relative magnetic intensity in the loops. A microprocessor (109) divides the output of the target loop pickups (88, 90, 92, and 94) by that of the reference loop pickup (96), in accordance with instructions provided in a read-only memory (ROM)(106). As a result, a corrected signal is produced for each assembly (66) independent of time-varying factors of the assembly (66).

Abstract: A method and apparatus including a circuit for measuring the displacement of an electromagnetic device wherein the measuring is effected by utilizing the perturbations which occur in the energizing current of the device when the moveable member contacts a second member during a "gap" measurement, for example. The circuit includes circuitry for obtaining a first derivative signal having indicator portions corresponding to the perturbations. An apparatus including a test block is used for testing center-to-center distances.

Abstract: A portable, battery powered, electronic wheel wear gauge is described for use in train wheel wear measurements. The gauge consists of a portable computer controller electrically connected to a portable gauge head. The gauge automatically determines proper positioning of the gauge head with respect to a wheel and then automatically measures rim thickness, flange thickness, flange height and, optionally, rim diameter of a train wheel using suitable contact and non-contact sensors. The measurement readings are displayed and can be stored in a non-volative memory of the controller for subsequent transfer to another computer or a printer.

Abstract: The invention provides an arrangement for determining the speed and rotor position of an electric machine, which arrangement consists of a tachometer generator having a permanent-magnet-excited rotor and a coaxially arranged rotor position transmitter which has a rotor body equipped with permanent magnets. Around the circumference of the rotor body magnetic-field sensitive sensor elements are arranged. A compact assembly of the tachometer generator and rotor position transmitter without detrimental mutual interference is possible by the provision that first permanent magnets magnetized in the tangential direction are arranged centered to the pole gaps of the tachometer generator rotor at the rotor body in such a manner that the sides of two adjacent permanent magnets facing each other have the same polarity as the magnet pole extending between the respective pole gaps of the tachometer generator rotor.

Abstract: A center-to-center distance measuring device for measuring the exact spacing between print solenoids. The devie uses a test block having a top surface and a bottom surface which are parallel. The top surface has first and second bevel surfaces which are parallel to each other, extend from the top surface towards the bottom surface and are spaced apart at a predetermined distance. The print solenoids are positioned perpendicularly to the top surface of the test block such that the print wires of the print solenoids impact against the test block when energized. The displacement of the print wires from the solenoids is used to determine the center-to-center spacing as the print wires impact against the bevel surfaces as the test block is moved.

Abstract: A displacement sensor or displacment gauge (3) for detecting misalignment measures the dislocation of a machine part, such as a post (12), by means of four magnetic coils (24N, etc.) deployed 90.degree. apart around the post and each energized by an oscillator (36N, etc.). A reference position of the machine part (12) relative to another component (6) of the machine is first established. Subsequent displacement is detected and excessive displacement is indicated if it exceeds a predetermined threshold magnitude.Signals from the four coils are processed combined in such a way that the magnitude of the radius of a displacement of the machine part (12) from the reference position is ascertained and provided irrespective of the direction of the displacement.

Abstract: Eddy current probe apparatus having an expansible sleeve thereon capable of hydraulically diametrically expanding a tubular member into engagement with an adjacent structure and capable of hydraulically diametrically expanding a tubular sealing member disposed in the tubular member into engagement with the interior wall of the tubular member, which probe is capable also of detecting the location of the structure and the extent of diametrical expansion of the sealing member and tubular member. The apparatus comprises a support body, expansion means sealingly attached to and surrounding the support body for diametrically expanding the tubular member or sealing member, and electromagnetic means connected to the support body for continuously electromagnetically detecting the variations in the electromagnetic characteristics of the tubular member, sealing member, and structure and the extent of diametrical expansion of the tubular member and sealing member.

Abstract: This invention is related to a method and device for measuring the distance (.delta.) between the discs of a refiner, in which method a magnetic field is generated by means of a coil (5) placed at one disc (4), which magnetic field is allowed to run at least partly through the other disc (3). According to the invention the measuring is carried out by using the actual distance between the refiner discs as the object of measuring in that the magnetic flux over the distance between the discs caused by the coil (5), which is formed at least at one refiner-disc tooth (7) or comparable element, is measured such that the flux running over the distance between two opposite teeth (7,8) is detected by means of another coil (6), such as is formed round at least either of said teeth, the signal induced in the coil being interpreted as a quantity that expresses the distance (.delta.) between the teeth.

Abstract: A turbine blade shroud clearance monitoring system is comprised of a plurality of sensors for measuring the clearance between the stationary portion of the turbine and the shroud segments in each turbine blade row. The measurements are averaged by a microprocessor to produce an average clearance value for each shroud segment. The microprocessor then analyzes the average clearance values for each shroud segment to determine when the clearance between a shroud segment and the stationary portion of the turbine is approaching a critical value. Output responsive to the foregoing analysis is then generated.

Abstract: A proximity switch assembly (10) for signaling the location of a movable member (36) at either of opposite end limits of movement relative to a stationary frame (44,46) includes a compact elongate housing (58) adapted to be mounted on the frame to extend along the path of movement of a power driven member (32), such as the piston rod of a hydraulic cylinder, which shifts the movable member between its end limits. The proximity switch is fixedly mounted in the housing and carries a switch actuating member (68) mounted for sliding movement over a relatively short distance sufficient to move an actuating target (74) into and out of actuating proximity of an air core proximity sensing coil (120) within the housing. A circuit board holder (96) formed of dielectric plastic material nests within the housing to protect, electrically insulate and precisely position components (120, 100, 102) carried thereby.

Abstract: The invention relates to an apparatus consisting of a device for generating a magnetic field mounted for movement relative to a product sitting in or moving through its field which is suspected of carrying at least one metal component which will cause the generator to move either toward or away therefrom because of either the attractive or repulsive forces, or both, caused by the presence of this metal or these metals. A load-responsive element in the form of a load cell is connected to the field generator so as to sense its movememnt if any and output a signal evidencing such movement. A detector is connected to receive the output signal from the load cell and use this information to initiate an appropriate response to the presence of the metal or metals causing the displacement of the generator.

Abstract: An apparatus for the inspection of a stack of cylindrical objects such as roller bearings, uses an eddy current probe. The probe is positioned at an angle with respect to the surfaces of the objects in order to achieve an acceptable signal and then the objects are rotated while the probe is advanced along them to fully scan the surfaces.

Abstract: Apparatus is disclosed for locating and measuring wear in nuclear reactor control rods. Circumferential and radial eddy current test probes produce outputs corresponding respectively to volume and thickness of the control rod. A method is disclosed to determine cladding wear when the volume and thickness varies beyond preselected limits.

Abstract: A slag detector apparatus for detecting onset of 5% or less slag entrainment in a stream of molten metal employs a detection coil having an axial length at least equal to the length of a globule of molten metal in the stream being composed of a continuous succession of recurring cyclical globules of molten metal, and an impedance detector for periodic sampling and smoothing of the fluctuations of the terminal impedance of the detector coil corresponding to the fluctuating cross-sectional dimension of the stream. The detector coil is part of a signal sensitivity enhancement circuit in the apparatus which also includes a tunable capacitor connected with the detector coil. The capacitor is used for tuning the circuit to its resonance frequency so that the capacitive reactance of the circuit due to the presence of the capacitor cancels the inductive reactance of the circuit due to the presence of the coil so as to leave only an impedance that is due to resistance of the coil.

Abstract: In a pipeline through which a vehicle such as a pig is travelling, a magnetically activated detector detects the presence of the approaching pig and sends a signal to switch on a transmitter unit which supplies an alternating current to an AC coil. This generates a magnetic field for a preselected period, the flux signal being then sensed by a pair of crossed coil sensors on board the pig after which the signal is processed in a unit on-board the pig. A reference pulse is then output for recording on a tape recorder also on-board the pig. This technique enables a geographical reference of the vehicle to be fixed.

Abstract: Both an apparatus and a method for simultaneously inspecting the walls of a tube with both ultrasonic and eddy current probes is disclosed herein. The apparatus generally comprises a cylindrical housing assembly insertable within the tube to be inspected, and a probe carrier rotatably mounted within and helically movable with respect to the housing. The probe carrier holds three ultrasonic probes for transmitting ultrasonic beams which are directly oriented radially, chordally, an axially with respect to the longitudinal axis of the tube, as well as an eddy current probe for simultaneously inspecting the walls of the tube with electromagnetic lines of flux. The apparatus further includes a helical drive train formed from a lead screw assembly having a motor means, a drive shaft, and a drive sleeve for imparting a helical scanning motion to the probe carrier with respect to the housing.

Abstract: A portable device for communication is useable during movement by a person. Individual portable receivers (2), the size of a credit card, display and/or broadcast to a user, automatically or by selection, data coming via waves (3) coming from microwave or laser transmitters (1) and FM transmitters (4). The transmitters (1) can cover nerve zones such as population centers, and sequentially send a flow of data transmitted by a digital signal with for instance 900,000 bits/second. At the same time, the transmitters (4) are used to cover 95% of a territory in audio. This provides a service of public interest, allows changing the descriptive speech, provides a choice of messages, offers a presale service, and makes possible selective identification.

Abstract: An apparatus by which a sensor holder of a surface testing apparatus can be moved along a preselected path of movement over the surface to be examined. The apparatus has a guide rail establishing the path of movement, which can emulate the contour of the surface and on which the sensor holder is supported.

Abstract: An electrical defect testing device for a non-magnetic test object, for example crack detection on hot continuously cast billets, is provided with means for detecting and suppressing the influence of disturbing magnetic regions of the object (e.g. regions of cold oxide scale). The device comprises at least one sensing transducer for harmful faults which is adapted to move relative to the test object. At least one detector is associated with the transducer for identifying the presence of magnetic material, and a blocking circuit is provided which, directly or indirectly, is controlled by the magnetic detector and is used for suppressing signals originating from a fault vector, for example a signal indicating a harmful fault. The presence of magnetic material can be detected using an eddy current technique.

Abstract: Either resistivity or thickness of conductive thin films may be measured if the other one of the properties is known. The system employs eddy current apparatus including an alternating frequency driving coil, a detector coil mounted in a housing adjacent one surface of the thin film, and circuitry for measuring the signal across the detector coil which senses the field after it is subjected to the eddy currents generated within the conductive film. Precise adjustment of a fixed distance between coils and film surface is important and achievable by positioning the film surface at the focal point of a optical microscope objective lens to which the eddy current apparatus is coupled.

Abstract: A system combining a transducer and a signal processing circuit measures the clearance distance from the transducer to an electrically conductive moving part of a machine. The transducer contains a magnet and a coil, both coupled magnetically to a region traversed by the machine part. Eddy currents are induced in the part as it passes through the magnetic field of the transducer. These currents produce a field which moves with the part and generates a characteristic signal in the transducer coil. Amplitude and timing attributes of the signal are measured by the signal processing circuit. An experimentally derived mathematical function which relates the amplitude and timing of this signal to the clearance distance between the transducer and the moving part is used to compute the clearance distance. During this calculation useful information is also developed about the speed and transit time of the moving part. The system is adapted to turbomachinery blade condition monitoring.

Abstract: A self-diagnostic method and apparatus is described for indicating the likelihood of an impending crash of a magnetic transducer or head with a rotating magnetic medium by dynamically and periodically calculating overwrite efficiency for performing a desired control operation when it exceeds a preselected value denoting dangerous proximity of the transducer to the surface of the medium.

Abstract: A magnetic field sensor coil wherein the coil is formed into a shape comprising two generally C-shaped limbs (2, 3) one within the other, one of these limbs being covered by a magnetic screening material (4). In operation an e.m.f. is induced in each turn of the unscreened part of the coil (3) while no e.m.f. is induced in the screened part (4) and so the total e.m.f. induced is approximately equal to the e.m.f. that would be induced in a simple concentrically wound coil of the same number of turns and of the same dimensions as the unscreened portion of the coil. The coil according to the invention is especially suitable for use with a system for monitoring an electric motor where the coil may be placed adjacent the motor end plate concentrically around the motor shaft without having to uncouple the motor from its load.

Abstract: A ferrous object detector and locator includes a magnetometer sensor and a position sensor controlled by a microprocessor. The device accurately locates and identifies an unknown ferrous object and determines the depth and orientation of a buried ferrous rod. Simultaneous magnetic field measurements from the magnetometer and position information in one or more orthogonal directions from the position sensor are combined and analyzed by the microprocessor using predetermined algorithms to determine the location and identity of the object. The detecetor is capable of detecting location and identity of objects of general shape and size.

Abstract: The buildup of slag or ash on the interior surface of a furnace wall is monitored by disposing two coils to form a transformer which is secured adjacent to the inside surface of the furnace wall. The inductive coupling between the two coils of the transformer is affected by the presence of oxides of iron in the slag or ash which is adjacent to the transformer, and the application of a voltage to one winding produces a voltage at the other winding that is related to the thickness of the slag or ash buildup on the inside surface of the furnace wall. The output of the other winding is an electrical signal which can be used to control an alarm or the like or provide an indication of the thickness of the slag or ash buildup at a remote location.

Abstract: The invention is concerned with a method and apparatus for measuring magnetic losses in a ferromagnetic material specimen. According to the invention, an alternating magnetic field having a predetermined frequency and an amplitude which is modulated at a frequency lower than the predetermined frequency is applied to the specimen, and a temperature modulation at a surface of the specimen having the applied field is measured. The magnitude of magnetic losses in the specimen is determined from the measured surface temperature modulation. The method and apparatus of the invention do not necessitate winding coils around the ferromagnetic material specimen, and also enable one to obtain information about the distribution of magnetic losses in the specimen.