Abstract: When a control unit is operated by a lighting control signal, when a reference voltage source unit outputs the reference voltage, voltage inputted into an error amplifier from a time constant circuit increases gradually with passage of time so as to reach the reference voltage. The error amplifier compares the voltage, which gradually increases with a power to be impressed to a lamp. An inverter circuit controls power to be supplied to the lamp according to the error signal. Thereby, the lamp power is controlled at time immediately after the lamp lighting signal is inputted. In addition, by providing a thermo-sensitive element for detecting circumference environmental temperature, it is possible to reduce influence to the light intensity due to the circumference environmental temperature. Further, the time constant circuit and the thermo-sensitive element may be provided in the detecting circuit.

Abstract: The invention comprises a method and electronic circuit to operate a quartz auxiliary lamp lighting lamp and circuit to light a quartz auxiliary lamp at 120 Vac and 50-60 Hz current connected to an electronic HID ballast operating at a frequency of 100 Hz to over 400 kHz and voltages of from 120 Vac, as provided by a multitap transformer and related circuitry.

Abstract: Methods and apparatus are disclosed for balancing currents passing through multiple parallel circuit branches and in some cases through parallel fluorescent lamps. Single transformers with multiple-leg magnetic cores are wound in specific manners that simplify current balancing. Conventional three-legged EE-type magnetic cores, with disclosed windings are used to balance current in circuits with three or more parallel branches, such as parallel connected Cold Cathode Fluorescent Lamps (CCFLs).

Abstract: Methods and apparatus are disclosed for balancing currents passing through multiple parallel circuit branches and in some cases through parallel fluorescent lamps. Single transformers with multiple-leg magnetic cores are wound in specific manners that simplify current balancing. Conventional three-legged EE-type magnetic cores, with disclosed windings are used to balance current in circuits with three or more parallel branches, such as parallel connected Cold Cathode Fluorescent Lamps (CCFLs).

Abstract: Methods and apparatus are disclosed for balancing currents passing through multiple circuit loads and in some cases through fluorescent lamps. Multiple-leg magnetic cores are wound in specific manners to simplify current balancing. Conventional three- or more than three-legged EE- and EI-type magnetic cores, with disclosed windings are used to balance current in circuits with multiple branches, such as connected Cold Cathode Fluorescent Lamps (CCFLs).

Abstract: A light fixture includes multiple sets of light-producing devices, such as bulbs. A first set of bulbs is illuminated. When one or more bulbs in the first set of bulbs fails, the failure is detected, and a second set of bulbs is illuminated: If a number of good bulbs remaining falls below a predetermined threshold, the light fixture provides a notification that a bulb change is required. The notification may include visual, audio, or electronic notification. By providing multiple sets of bulbs and a controller to detect a bulb failure and automatically switch to a different set of bulbs, the light fixture and method of the preferred embodiments provide high-reliability lighting that automatically compensates when a bulb burns out.

Abstract: A power output device includes a bridged output stage, a reference voltage generator and a detecting unit to compare the output voltages from the aforementioned two units. The bridged output stage may be implemented by a full-bridge or a half-bridge configuration. The reference voltage generator is symmetric to the bridged output stage to generate a reference voltage, which is served as a reference voltage range for the voltage difference of the two terminals of the turned-on transistors in the bridged output stage during operation. When the detecting unit detects the voltages across the two terminals of the turned-on transistors in the bridged output stage exceed the reference voltage range, all the transistors are turned off and no power is outputted to the load. Therefore, the circuit is capable of preventing damages caused by a large current due to overload or short circuit.

Abstract: A discharge lamp lighting circuit 1 is provided with a DC-AC conversion circuit 3 having a plurality of switching elements 5H, 5L and a series resonance circuit (8, 9, 7p), and control means 17 for preventing a situation in which the drive frequency of the switching element remains less than its specified minimum frequency. When the discharge lamp is lit, driving control of the switching element is carried out in a frequency range higher than the series resonance frequency. By using a driving situation detection circuit 15, a driving situation of the switching element is monitored based on a relation with a phase of a lamp current which flows through the discharge lamp. If the drive frequency of the switching element becomes less than the specified minimum frequency, the drive frequency is increased, and thereby, a lower limit of the drive frequency is automatically restricted.

Abstract: Control process for mode change decisions for an infinitely variable transmission with several modes of operation (A, B) comprising at least two parallel coupling paths, each containing a closed coupler for the first mode of operation (A) and open for a second (B), with the two couplers being closed simultaneously during a delay period during the mode changes, characterized by the fact that the mode change decision is imposed onto the transmission if the speed differential (DWb, DWa) at the terminals of the coupler to be closed to change the mode, exceeds a first pre-established threshold (SNb, SPa).

Abstract: A recording apparatus including: (a) a recording head unit for performing a dot recording operation by activation of the actuators; (b) a main circuit for outputting a plurality of sets of drive waveform signals; and (c) a head driver unit for receiving the sets of drive waveform signals outputted from the main circuit, generating a drive signal based on one of the drive waveform signals that is selected from among each of the received sets of drive waveform signals, and supplying the generated drive signal to each actuator of the recording head. The main circuit transmits a single set of waveform data signals containing data representative of the plurality of sets of drive waveform signals, to the head driver unit. The head driver unit includes a waveform signal retriever operable to retrieve the plurality of sets of drive waveform signals from the single set of waveform data signals, with reference to reference signals, so that the head driver unit receives the plurality of sets of drive waveform signals.

Abstract: A voltage modulating apparatus for a motor of an electrical vehicle includes a driver, a governor, a PWM device, a Hall sensor and an energy saver. The driver sends a driving signal to a motor of the electrical vehicle. The governor is controlled by a user to output a speed adjusting signal to the driver so that the driver can drive the motor to change a rotating speed. The PWM device is connected to the driver. The Hall sensor is installed in the motor for detecting a speed change of the motor to send a Hall signal to the PWM device. The energy saver is connected with driver for detecting a change of the driving signal to control the PWM device to send a PWM signal to the driver merely as the rotating speed of the motor is reduced. As such, a power saving effect for the motor is obtained.

Abstract: A generator-motor apparatus (100) includes a control circuit (20), an alternator (50), electrode plates (83, 84), and switching devices (SW1 to SW6). The electrodes plates (83, 5 84) have a substantial horseshoe shape, and are provided on an end surface of the alternator (50) so as to surround a rotating shaft (50A) of the alternator (50). Each of the switching devices (SW1 to SW6) is formed by sandwiching a MOS transistor between two electrodes, and has a can structure for sealing the internal space of the switching device using a resin. The switching devices (SW1, SW3, SW5) are directly attached to the electrode plate (83) by means of soldering, and the switching devices (SW2, SW4, SW6) are directly attached to the electrode plate (84) by means of soldering. The control circuit (2% controls the switching devices (SW1 to SW6). The switching devices (SW1 to SW6) drive the alternator (50) as an electric motor or an electric power generator.

Abstract: Disclosed herein is a power device. The power device has a power source; timing circuitry powered by the power source for producing a current pulse output having a pulse width; a switch for triggering the current pulse output produced by the timing circuitry; an armature motor powered by the power source and in electrical communication with the timing circuitry for receiving the current pulse therefrom, the armature motor comprising: an electro-magnetic core; a first winding for carrying electric current to energize a magnetic field associated with the electro-magnetic core; a second winding for carrying current to reset the magnetic field associated with the electro-magnetic core, the first and second windings wound about the electro-magnetic core; and a swinging armature for providing movement in response to the energizing of the magnetic field about electromagnetic core. The first winding and the second winding are bifilar wound together about the electro-magnetic core.

Abstract: An apparatus for controlling an electric motor (14) for, when energized, moving a vehicle window (22) selectively up or down and selectively in an auto up or auto down mode. The apparatus includes an electrical circuit electrically coupled to the electric motor (14) to energize the electrical motor (14) to move the window (22) toward one of the fully open and fully closed positions. The circuit includes a printed circuit board (46) and a first switch (10) for selectively energizing the electrical motor (14). An actuator (32) is movable to actuate the first switch (10) to actuate the electrical motor (14). A second switch (200) for selectively energizing the electrical motor (14) in an auto function mode is activated by a member (150) extending through the printed circuit board (46).

Abstract: Control parameters can be easily and precisely adjusted, the response of a motor controller can be highly accurately made at high speed and a vibration can be suppressed to a low level. Even when an inertia is varied during an operation or a viscous friction is high, the inertia or a viscous friction coefficient can be identified by a control parameter adjusting unit (18) for performing a calculation on the basis of a torque command Tref and the speed Vfb of a motor. As a result, control parameters can be easily and precisely adjusted and the response of a motor controller can be highly accurately carried out at high speed and a vibration can be suppressed to a low level.

Abstract: According to a preferred aspect of the instant invention, there is provided a system and method of moving a disc drive arm in the presence of nonlinear magnetic bias. Further, in another preferred embodiment the instant method will be adaptive and/or self-corrective and is especially useful when used with disc drive hardware other than the hardware that was used to model the control law.

Abstract: A method and system for controlling a power converter coupled to a polyphase power line. The method includes measuring at least two motor phase currents, obtaining a floating reference frame for the current Park vector, adjusting the reference frame based on an estimated rotor speed, and controlling the power converter via the floating reference frame to reinitiate power to a motor while a rotor is still moving.

Abstract: The present invention provides wireless and direct wired methods and devices for automatically closing electrically-driven roll-down storm shutters in the presence of rain on one or more rain sensors.

Abstract: A handling system able to efficiently process information relating to a plurality of conveyed articles, the handling system provided with a conveyer for conveying workpieces, a visual sensor for detecting positions of workpieces by acquiring images of a plurality of tracking ranges obtained by dividing a belt into sections, an encoder for detecting an amount of movement of the belt, a tracking manager for monitoring amounts of movement of the plurality of tracking ranges based on the amount of movement detected by the encoder and specifying the tracking range passing through a workpiece detection area, a workpiece manager for selecting the article in the tracking range specified by the tracking manager, and a controller for controlling operations of robots so as to hold the workpiece selected by the workpiece manager.

Abstract: A digital speed controlling apparatus includes: a target speed calculator that calculates a target speed of a driven conveyor belt, based on a sampling time; a current speed calculator that calculates a current speed of the conveyor belt, based on displacement and a difference of a sampling time; a target speed determining unit that determines whether a target speed is smaller than a predetermined value; a speed corrector that replaces the current speed with a set value, when the target speed is smaller than the predetermined value and also when the current speed is the minimum unit displacement per the sampling cycle; a speed error calculator that calculates an error between a replaced set value and the target speed; and an automatic controller that controls the drive motor based on a speed error.

Abstract: There is provided a servo controller for synchronously controlling a master side drive source to drive one drive axis and a slave side drive source to drive the other drive axis. The servo controller includes a correction data calculation means for calculating correction data to correct a positional deviation of a slave side drive source according to a synchronization error which is a difference between a positional deviation of a master side drive source and a positional deviation of the slave side drive source, in which the correction data is added to the positional deviation of the slave side drive source.

Abstract: An objective is to obtain a high robust position controller and a controlling method therefor, with respect to their technique in which control gain, in order to prevent an overshoot due to frictions, is most suitably adjusted. The position controller having a feedforward system includes: a friction-coefficient-estimated-value setting unit for setting arbitrary friction-coefficient-estimated-values; an overshoot-prevention-gain calculator for determining speed-integral-term feedforward gain, based on estimated friction-coefficient values set by the friction-coefficient-estimated-value setting unit; and a speed feedforward multiplying unit for calculating the product of the speed-integral-term feedforward gain multiplied by a feedforward command value that is based on a positional command; the multiplication product from the speed feedforward multiplying unit being used to reduce the feedforward term.

Abstract: A frequency converter for outputting a power to drive a motor, having: an inverter unit for inverting a d.c. power to an a.c. power; a control unit for controlling the inverter unit; and a housing for supporting at least the inverter unit and control unit, wherein a rise time change unit is provided in the housing, the rise time change unit changes a rise time of a waveform of a voltage output from the inverter unit.

Abstract: A motor drive for conditioning power to be delivered to a non-motor load includes a voltage feedback circuit that monitors a DC bus voltage and, based on changes in the DC bus voltage, adjusts a power conditioning scheme such that near steady-state load conditions are maintained in response to a transient load condition. The voltage feedback circuit has a voltage sensor that provides voltage feedback to a controller that determines what changes in power conditioning are needed in response to a transient load condition that manifests itself in a change in DC bus voltage.

Abstract: A device for power reduction during an operation of an inductive load, which is operated in a turn-on phase with an increased supply voltage and in a holding phase statically or in PWM operation with the on-board voltage, has a transistor disposed between the on-board voltage source and the inductive load as a switch. A further transistor is connected in series with this transistor and both the source terminals and also the gate terminals of both transistors are connected to one another. With this circuit configuration unwanted current flows are prevented through the substrate diodes of both transistors.

Abstract: A method and a circuit for extracting current-voltage characteristics employ two pulse signals with different duty cycles into a device to be measured in order to extracting current-voltage characteristics of the device to be measured. The present invention may reduce the self-heating effect of the device to be measured and increase the measurable range of the device to be measured.

Abstract: This is an system to reclaim DC power unused by an load, so that the load is allowed to use nearly 100% of the DC power, making it better than AC for power reclaimation.

Abstract: The proposed soft-switching DC/DC converter includes a converter circuit including a main switch having a first, a second and a control terminals for converting an input DC voltage to an output DC voltage, a resonant circuit electrically connected to the converter circuit, and an energy transferring circuit including an auxiliary switch having a first, a second and a control terminals and magnetically coupled to the resonant circuit. In which, the main switch is turned on under a specific voltage across the first and the second terminals of the main switch and the auxiliary switch is turned off under a specific current flowing through the first and the second terminals of the auxiliary switch both controlled by the resonant circuit through a resonance effect so as to accomplish a soft-switching of the converter.

Abstract: A voltage regulator output stage can include a power device whose body to source junction is forward biased using a MOSFET trigger. The forward biasing can advantageously reduce the threshold voltage of the power device, thereby effectively increasing its gate drive as well as its output current capability. Controlling the forward biasing using the MOSFET trigger provides minimal leakage, thereby ensuring that the output stage is commercially viable as well as performance enhanced.

Abstract: An information handling system has a power supply using a DC-to-DC buck converter. The DC-to-DC buck converter maintains continuous mode of operation over a wide range of output currents by adding more inductance to the buck converter circuit when the load current is below a certain value(s). A sensing circuit may determine load current and at the certain value(s) more inductance (increased inductance value) may be added to the buck converter circuit so as to main a continuous mode of operation. When the load current increases above the certain value, the extra inductance may be removed (inductance value decreased). Thus, the buck converter may operate most efficiently and remain in the continuous operation mode for a wider range of load currents.

Abstract: An integrated circuit for controlling a switching power supply includes a signal input terminal in addition to a switching input terminal that is also provided in a conventional integrated circuit and is a terminal to switch IC operation modes using an external control signal. The switching input terminal signal is made valid when the signal input terminal voltage is higher than a threshold voltage, such that mode switching using an external control signal is enabled. When the signal input terminal voltage is lower than the threshold voltage, mode switching is automatically conducted by switching a MOSFET ON or OFF using output signals of portions of a comparator connected to a feedback terminal to which an output voltage of a power supply device is applied.

Abstract: Techniques are disclosed to extend an on time period of switch to regulate a transfer of energy from an input of a power supply to an output of a power supply. One example integrated circuit includes an energy transfer element coupled between an input and an output of the power supply. A switch is coupled to the input of the energy transfer element. A controller is coupled to the switch to control switching of the switch to regulate a transfer of energy from the input of the power supply to the output of the power supply in response to a feedback signal received from the output of the power supply. The controller is coupled to limit a maximum on time period of the switch a first maximum on time period in response to a first range of power supply operating conditions and to a second maximum on time period for a second range of power supply operating conditions.

Abstract: Techniques are disclosed to adjust a current limit in a switching regulator. One example switching regulator includes a switch to be coupled to an energy transfer element of a power supply. A controller to generate a drive signal is coupled to control switching of the switch to regulate an output of the power supply. A current limiter is included in the controller to adjust the drive signal to limit a current though the switch to a variable current limit value. The variable current limit value is set by the current limiter in response to an input line voltage to be coupled to the energy transfer element.

Abstract: A hybrid vehicle propulsion system with a double-layer capacitor is provided. A low voltage double-layer capacitor energy storage system provides power to a hybrid vehicle propulsion system. A boost converter boosts the voltage of the double-layer capacitor system to a higher operating voltage to power at least one motor/generator of the propulsion system.

Abstract: A method and apparatus for measuring a circularly polarized rotating electromagnetic wave using a magnetic field are provided. The method and apparatus are used to measure properties of a circularly polarized rotating electromagnetic wave occurring in nature by using a phenomenon that energy is intensified or attenuated when circularly polarized rotating electromagnetic waves interact. The method and apparatus are used to measure properties of a circularly polarized rotating electromagnetic wave which causes variations in a magnetic field, when circularly polarized rotating electromagnetic waves are radiated into a magnetic field formed by a magnetic body or the flow of electric current, and the variations in the magnetic field are measured as variations in electric current.

Abstract: Delay-locked loops, signal locking methods and devices and system incorporating delay-locked loops are described. A delay-locked loop includes a forward delay path, a feedback delay path, a phase detector and a timer circuit. The forward delay path alternatively couples to an external clock signal and to an internal test signal. The phase detector adjusts a delay line based upon the phase differences of a feedback signal and the external clock signal. The timer circuit switches the test signal into the forward delay path and measures the time of traversal of the test signal around the forward delay path and the feedback delay path and generates a time constant for configuring the phase detector's update period. The phase detector is thereafter able to stabilize at an improved rate.

Abstract: Phase delay compensation sweep may be used in determining correct phase delay compensation of measured currents for substantially matching a measured apparent power to an expected apparent power over an operating range of current values of a current transformer (CT). A frequency sweep may also be used in determining correct phase delay compensation of each measured current in applications having multiple frequencies. Phase delay compensation for each CT current value may be stored in a phase delay compensation look-up table during the phase delay compensation sweep calibration and recalled from the look-up table during operational power measurements. Phase delay compensation for each CT current value and each frequency of that current value may be stored in a phase delay compensation look-up table during the phase delay compensation sweep calibration and recalled from the look-up table during operational power measurements.

Abstract: Disclosed is a compensated current differential relaying method and system for protecting a transformer more correctly by calculating and estimating an exciting current including a core-loss current and a magnetizing current, and, in particular, to a compensated current differential relaying method and system which can protect the transformer correctly irrespective of the level of remanent flux.

Abstract: A configurable buss element for an electricity meter includes a conductive piece of metal formed into a series of contact connectors and a network of elongate conductors extending between and among the series of contact connectors. Each of the plurality of contact connectors is configured to contact a circuit element of an electricity meter. The network of elongate conductors is operable to provide connectivity between the contact connectors and select portions of the conductive piece of metal in one of a plurality of connectivity configurations, each of the connectivity configurations corresponding to an electricity meter configuration, the select one of the plurality of connectivity configurations defined by a predetermined set of discontinuities introduced in the network of elongate conductors.

Abstract: Phase delay compensation sweep may be used in determining correct phase delay compensation of measured currents for substantially matching a measured apparent power to an expected apparent power over an operating range of current values of a current transformer (CT). A frequency sweep may also be used in determining correct phase delay compensation of each measured current in applications having multiple frequencies. Phase delay compensation for each CT current value may be stored in a phase delay compensation look-up table during the phase delay compensation sweep calibration and recalled from the look-up table during operational power measurements. Phase delay compensation for each CT current value and each frequency of that current value may be stored in a phase delay compensation look-up table during the phase delay compensation sweep calibration and recalled from the look-up table during operational power measurements.

Abstract: A method for sorting devices in automated handling equipment, including placing a plurality of input trays containing a plurality of devices and a plurality of empty trays into a handler; sorting the plurality of devices in the plurality of input trays into the plurality of empty trays according to a category of each of the plurality of devices, dynamically assigning categories to each of the plurality of empty trays for each category of the plurality of devices, dynamically assigning categories to the plurality of input trays and placing the sorted plurality of devices into the plurality of input trays, removing the empty trays housing the plurality of sorted devices from the handler and determining whether the sorting is completed.

Abstract: An impedance conversion circuit including: a first voltage-to-current converter and a second voltage-to-current converter supplied with differential input signal voltages; an inverting amplifier; and a third voltage-to-current converter for feedback; wherein a first resistance and a second resistance are connected in series with each other between an input terminal and an output terminal of the inverting amplifier, an output terminal of the first voltage-to-current converter is connected to the input terminal of the inverting amplifier, an output terminal of the second voltage-to-current converter is connected to a connection node of the first resistance and the second resistance, the output terminal of the inverting amplifier is connected to an input terminal of the third voltage-to-current converter, an output terminal of the third voltage-to-current converter is connected to an input terminal of the first voltage-to-current converter, and an impedance is connected between the connection node and a ground.

Abstract: Inspection is performed without applying an excessive pressure to an inspection object to thereby resolve inspection failure caused by excessive pressure application. An electrical connection device electrically connects a signal wiring formed on a wiring board to an electrode part of the inspection object. A contact is provided which electrically connects together the electrode part of the inspection object and the signal wiring of the wiring board. The contact includes: an electrode abutting part that abuts the electrode part located on a lower portion of the inspection object, a wiring abutting part that abuts the signal wiring, an elastic body support part that fits with the elastic body to elastically support the entire contact, and a release lever part that is pressed to thereby rotate the entire contact whereby the abutting between the electrode part of the inspection object and the electrode abutting part is released.

Abstract: A pressure activated piston-cylinder device includes a cylinder barrel with a cylinder bore, a piston with a piston rod movably guided in the cylinder bore, and a piston position sensing and indicating device. The piston position sensing and indicating device includes a magnetic activating element carried on the piston and an elongate electronic contact free transducer mounted on the cylinder barrel. The cylinder barrel includes a standard type extruded aluminum alloy barrel with an outer channel which extends in an offset parallel disposition relative to the cylinder bore, and a circuit board with electronic components connected to the transducer. The transducer as well as the circuit board are located in the groove in the cylinder barrel.

Abstract: First and second shafts (1, 2) are interconnected via a torsion bar (3) for torsional (or rotational) movement relative to each other, and first and second magnetic body sections (10, 20) are provided to rotate in interlocked relation to the rotation of the first and second shafts, respectively. The first and second magnetic body sections form at least two ring-shaped variable magnetic coupling sections opposed to each other via a gap, magnetic coupling in each of the boundary sections varies in response to variation of a relative rotational position between the first and second shafts, and variation of the magnetic coupling differs in phase between the boundary sections. Coil section (30) includes magnetic-coupling detecting coils (L1-L4) provided in corresponding relation to the boundary sections.

Abstract: A magnetic sensing apparatus includes a first magnetic transducer separated spatially from a second magnetic transducer and proximate to a target and a direction decoding circuit associated with the first and second magnetic transducers, wherein the direction decoding circuit produces output pulses that provide data indicative of a rotation of the target while rejecting rotational vibration signals associated with the target during a rotational detection of the target utilizing the first and second magnetic transducers without producing erroneous output pulses or missing an excessive number of the output pulses during speed and rotational detection operations thereof.

Abstract: A system that senses proximity includes a magnet producing a magnetic field and a sensor having a switch. The switch includes a cantilever supported by a supporting structure. The cantilever has a magnetic material and a longitudinal axis. The magnetic material makes the cantilever sensitive to the magnetic field, such that the cantilever is configured to move between first and second states. The switch also includes contacts supported by the support structure. The switch can be configured as a reed switch. When the magnet moves relative to the sensor, the cantilever interacts with a respective one of the contacts based on the position of the magnet during movement.

Abstract: Apparatus (10) for establishing the positions of metal objects in a mixed input stream of both metal and non-metal objects, the apparatus comprising a differential metal-detecting coil (14A) having a first coil portion wound in a first sense and a second coil portion of generally similar shape and size to the first, wound in a second sense opposite to the first sense, and conveying means (11) for moving objects with respect to, and past, the differential metal-detecting coil in a plane and in a direction with unit vector â, characterised in that the second coil portion is displaced from the first coil portion by a displacement B having a component in the plane in a direction with unit vector {circumflex over (b)}, wherein 0<cos?1 â·{circumflex over (b)}<?/2, and in that the apparatus further comprises analysing means for analysing the form of the output voltage of the coil as a function of time to establish the position of said metal objects in a direction ? in the plane, where ? is defined by â·?=0.

Abstract: This invention relates to a test device for metal detector portal structure, characterised by the fact that it comprises a removable rack (10) comprising support and guide means (300) for displacement of a panel (400) capable of carrying a reference sample.

Abstract: Damage and usage conditions in the vicinity of fasteners in joined structures are nondestructively evaluated using the fasteners themselves. Sensors or sensor conductors are embedded in the fasteners or integrated within the fastener construct, either in the clearance gap between the fastener and the structure material or as an insert inside the shaft or pin of the fastener. The response of the material to an interrogating magnetic or electric field is then measured with drive and sense electrodes both incorporated into the fastener or with either drive or sense electrodes external to the fastener on the material surface. In another configuration, an electric current is applied to one or more fasteners and the electric potential is measured at locations typically between the driven electrodes applying the current. The potential is measured circumferentially around the fastener at locations on the material surface or across pairs of fasteners throughout or along the joint.