Abstract: A circuit for sensing the driving current of a motor, the circuit comprising: a driver configured to generate a driving current for each phase of a multiple-phase motor, the instantaneous sum of all the driving currents being zero; a current sensor for each phase of the multiple-phase motor, each current sensor configured to measure the driving current of that phase and comprising a plurality of current sensor elements arranged with respect to each other such that each current sensor element has the same magnitude of driving current systematic error due to magnetic fields external to the driving current to be measured; and a controller configured to, for each phase of the multiple-phase motor, generate an estimate of the driving current of that phase to be the measured driving current of that phase minus 1/n of the total of the measured driving currents for all phases, n being the number of phases of the multiple-phase motor.

Abstract: An integrated circuit that can include a driver having a first driver output, and a first resistance coupled between a first node coupled to the first driver output and a second node. The first resistance can include a process resistor including a first material having a first temperature coefficient, and an interconnect resistor configured to provide at least 20% of the first resistance and including a second material having a second temperature coefficient which changes resistance in an opposite direction with temperature as compared to the first temperature coefficient. A first terminal of the interconnect resistor is directly connected to a first terminal of the process resistor.

Abstract: The present invention relates to a monitoring system of wind-induced motion or vibration in at least one overhead cable (102), in particular a conductor aerial cable (102) of a transmission or distribution electric line. The monitoring system comprises: at least three sensor nodes (104) adapted to be installed in positions different from each other on a first overhead cable (102) and configured for detecting the motion or vibration through a synchronous signal acquisition. Each of the at least three sensor nodes (104) comprises a respective triaxial accelerometer sensor (301) configured for acquiring a first node signal and a first processor (302) configured for identifying, in the first node signal, a maximum node amplitude and an associated node frequency through a spectral analysis of the first node signal.

Abstract: A component sensitive to an electromagnetic field, which includes a first absorbent material, able to partially absorb energy of a given electromagnetic field and converting the absorbed energy into heat. The sensitive component includes a second fluorescent and thermosensitive material, placed in contact with the first material in order to store the heat converted by the first material. The second material is able to re-emit, under the action of a predetermined excitation light, a light by fluorescence with light intensity dependent on the stored heat.

Abstract: A method for determining a dynamic rating for a conductive path includes using a sensor to measure a value for a load parameter and selecting a heating process associated with the load parameter. A rated temperature change is changed by removing temperature changes due to a heating process other than the selected heating process to produce an impaired rated temperature change. A thermal load percentage is determined from the impaired rated temperature change. The thermal load percentage and the measured value are then used to determine the dynamic rating for the load parameter. A method also includes measuring a temperature rise, a current, and a voltage on the conductive path multiple times. Using at least two basis functions and the multiple measured temperature rises, currents and voltages, the values for at least two variables are determined. Trends in each variable are determined to determine a condition of electric equipment.

Abstract: A power system and related methods provide sense resistor fault detection and safe operation of switching power converters and connected devices such as portable electronic devices powered by the switching power converter. The power system detects an open circuit or short circuit condition of the sense resistor and controls output current of the switching power converter to ensure safe operating conditions of the power system and connected equipment. The power system can also detect initial inrush current of the connected equipment and detect a duty cycle of the switching power converter to positively detect a short circuit condition of the sense resistor.

Abstract: A system and method for discharging a high voltage vehicle battery. The system includes a discharge circuit having a reference voltage source providing a reference voltage and a load for discharging the battery. A negative terminal of the voltage source is electrically coupled to a negative terminal of the battery so that upon initiation of the discharging sequence, the battery is discharged through the load to the reference voltage. The discharge circuit can be electrically configured so that the battery, the voltage source and the load are electrically coupled in series or the battery, the voltage source and the load are electrically coupled in parallel.

Abstract: A thermocouple device includes a shared conductor for a shunt measurement and a thermocouple measurement. For example, the thermocouple device may include a shared conductor that provides a signal to both calculate current of a shunt and calculate a temperature of the shunt. The thermocouple device may provide an efficient structure that accurately calculates current and temperature. In addition, the thermocouple device may use the temperature of the shunt to detect when a conductive path is overheating. The temperature of the shunt may also be used for other purposes.

Abstract: An arrangement for use in a utility meter is disclosed. The arrangement includes a meter blade coupled to a current coil. The arrangement further includes a current sensor that includes a winding about a core. The current sensor is in a current sensing relationship with the current coil. The winding has a resistance that varies as a function of temperature. The arrangement further includes a processing circuit that is operably coupled to receive a measurement signal from the winding. The processing circuit is configured to determine a DC component of the measurement signal, determine the resistance of the winding based at least in part on the determined DC component, and cause a value representative of the determined resistance to be displayed or communicated to an external device.

Abstract: A power system and related methods provide sense resistor fault detection and safe operation of switching power converters and connected devices such as portable electronic devices powered by the switching power converter. The power system detects an open circuit or short circuit condition of the sense resistor and controls output current of the switching power converter to ensure safe operating conditions of the power system and connected equipment. The power system can also detect initial inrush current of the connected equipment and detect a duty cycle of the switching power converter to positively detect a short circuit condition of the sense resistor.

Abstract: Provided is an overheat detection circuit having a small circuit scale, low cost, and low electric power consumption. The overheat detection circuit implemented in a CMOS semiconductor device includes: a reference voltage circuit connected between a base and an emitter of a parasitic bipolar transistor; and a current detection circuit connected to the emitter of the parasitic bipolar transistor, in which the current detection circuit is configured to detect a flow of a current through the parasitic bipolar transistor to output an overheat detection signal.

Abstract: A temperature of a semiconductor element is measured based on a temperature coefficient of a voltage between the first electrode and the second electrode when no heat is generated when causing a constant current of an extent such that the semiconductor element does not generate heat to be input wherein current is caused to flow from a third electrode to a second electrode in accordance with voltage applied between a first electrode and the second electrode. Also, a constant current such that the semiconductor element generates heat is input into the third electrode, with voltage applied between the first electrode and second electrode of the semiconductor element kept constant, and power is measured based on the current such that the semiconductor element generates heat and on voltage when heat is generated between the third electrode and second electrode when the semiconductor element generates heat.

Abstract: Systems and methods for determining an effective wind speed are disclosed. A system includes a first detector, a second detector and a processing unit. The first detector includes a heated temperature-sensing element having a heater and a first temperature sensor, and a first housing at least partially housing the heated temperature-sensing element. The second detector includes a non-heated temperature-sensing element having a second temperature sensor, a second housing at least partially housing the non-heated temperature-sensing element. The processing unit can be adapted to determine the effective wind speed according to a temperature at the heated temperature-sensing element, a temperature at the non-heated temperature-sensing element, and/or a difference between these temperatures and in accordance with an algorithm or table of values.

Abstract: An apparatus is provided for securing to and collecting power from an electrical conductor, including a current transformer comprising a core and an electrical winding that receives an induced current from magnetic flux generated according to alternating current present on the electrical conductor, and a clamping mechanism that attaches the apparatus to the electrical conductor. According to various aspects, apparatus may include a housing that encloses circuitry for monitoring conditions of the electrical conductor, where the circuitry includes one or more sensors, and wireless communications circuitry.

Abstract: The power conversion device includes an AC power source, a power conversion unit, and an LC filter unit arranged between the AC power source and the power conversion unit, and the LC filter unit has a temperature detection element provided in one part or in a plurality of parts configuring the LC filter unit, and the power conversion unit has a temperature detection unit configured to receive temperature data detected by the temperature detection element and a determination unit configured to calculate temperature rise values of one or plurality of parts, or temperature differences between the plurality of parts based on the temperature data received by the temperature detection unit and to determine whether or not there is an abnormality in the LC filter unit in accordance with the calculation result.

Abstract: A radio frequency sensor system includes a printed circuit board (PCB). The PCB includes a first exterior layer, a second exterior layer, a first interior layer, a second interior layer, and an inner perimeter that defines an aperture through the PCB. The PCB also includes a first loop. The first loop includes a first plurality of sensor pads coupled to a first plurality of vias by a first plurality of traces. The first plurality of sensor pads is arranged on the inner perimeter. The PCB also includes a second loop. The second loop includes a second plurality of sensor pads coupled to a second plurality of vias by a second plurality of traces. The second plurality of sensor pads is arranged on the inner perimeter. A core ring is embedded within the first interior layer proximal to the first plurality of sensor pads, the first plurality of vias, and the first plurality of traces. A center conductor, for carrying RF current, extends through the aperture.

Abstract: Embodiments of the present invention relate to integrated modular display panels. In one embodiment, modular display panel includes a casing having a recess. The casing includes locking points for use in attachment to an adjacent casing of another modular display panel. A printed circuit board is disposed in the recess and a plurality of LEDs attached to the printed circuit board. A driver circuit is attached to the printed circuit board. A heat sink is disposed between a back side of the casing and the printed circuit board. The heat sink thermally contacts the back side of the casing and the printed circuit board. A framework of louvers is disposed over the printed circuit board. The framework of louvers is disposed between rows of the LEDs. The framework of louvers is attached to the printed circuit board using an adhesive.

Abstract: A device for attaching to a power line conductor includes a jaw assembly and at least one jaw slot formed on a portion of the jaw assembly configured to engage a stranded power line conductor. The at least one jaw slot extends at an angle on the jaw assembly configured to match a helical angle of strands on an outer surface of the stranded power line conductor and configured to space the jaw assembly from at least one strand of the stranded power line conductor.

Abstract: A battery powered transmitter is provided with a battery status circuit that determines an output voltage level associated with the battery. The battery status circuit is provided with multiple voltage reference thresholds. One or more visual voltage status indicators are electrically coupled with the battery status circuit. The battery status circuit actuates a visual voltage status indicator when the battery status circuit determines the voltage output level of the battery to be within a first output range. One or more additional visual voltage status indicators may be actuated when the battery status circuit determines the voltage output level of the battery to be within other output ranges.

Abstract: A battery powered transmitter is provided with a battery status circuit that determines an output voltage level associated with the battery. The battery status circuit is provided with multiple voltage reference thresholds. One or more visual voltage status indicators are electrically coupled with the battery status circuit. The battery status circuit actuates a visual voltage status indicator when the battery status circuit determines the voltage output level of the battery to be within a first output range. One or more additional visual voltage status indicators may be actuated when the battery status circuit determines the voltage output level of the battery to be within other output ranges.

Abstract: A power measurement system includes: a power temperature converter attached to a power supply line of an electric instrument and having a temperature changed corresponding to a current flowing through the power supply line; a temperature measurement apparatus configured to measure the temperature of the power temperature converter; and an analyzer configured to analyze power consumed by the electric instrument by using a measurement result of the temperature of the power temperature converter obtained by the temperature measurement apparatus.

Abstract: A method for determining a heating characteristic of a glow plug, wherein pulse-width-modulated voltage pulses are applied to the glow plug and an electric variable is measured repeatedly during a voltage pulse with the heating characteristic of the glow plug determined by evaluating the difference of successive measurement results of this variable.

Abstract: The present invention provides an optical sensor for monitoring current or power in a monitored element of a device such as a bridge-wire or hot-wire of electro-explosive devices. The optical sensor comprises an optical sensor made of semiconductor material. The semiconductor material comprises an absorption edge which is sensitive to a temperature variation. The semiconductor material is for placing in thermal contact with the monitored element of the device, whereby, when the current or power varies in the monitored element, it causes a variation in temperature in the semiconductor element and hence a spectral shift of the absorption edge which can be measured and which is representative of current and power variation.

Abstract: A signal converter and method of converting a signal are provided. The converter includes a power supply, microcontroller and current sensor. The microcontroller is connected to a power supply and is configured to receive inputs from a vehicle and output signals to loads of a second vehicle. The sensor is connected to the microcontroller to monitor current flow at the loads. The output channels are configured to stagger activity on the output signals. The microcontroller reduces the duty cycle of the output signals if the current flow rises above a first threshold and resumes the output signal to full strength once the current flow falls below a second threshold. The method includes receiving an input signal, sending an output signal, measuring current flow, measuring temperature, reducing the power of the output signal, and restoring the output signal.

Abstract: An electric field sensor comprising: a substrate having a hole; a shielding electrode and a sensing electrode, disposed in the hole of the substrate; a piezoelectric bar having one end connected to the center of the shielding electrode, the other end fixed on the substrate. Present invention provides several electric field sensors, which have the same feature of utilizing electrodes interleaving vibration to modulate external electric field. They have IC-compatible operation voltage and small volume.

Abstract: Maximum transmission line or conductor loading of an overhead transmission line or conductor spanning two transmission line towers is determined by using a sensing device clamped to the overhead transmission line. The sensing device acquires real-time information that is used in an iterative process to determine sag, limiting temperature, maximum current load and minimum clearance of the transmission line or conductor.

Abstract: A method is provided for controlling the sagging of a power transmission cable hang between two towers. The cable has a first supporting portion and a second conductive portion. The method includes a first act of mounting the cable between the two towers, such that when mounted between the towers the cable has a cable load. The method further includes a second act of stretching the first portion to have a cable sag less than a desired sag, a third act of releasing at least some of the tension to obtain the desired sag, and a fourth act calculating a load magnitude carried by the first portion. If the load magnitude is less than a desired load magnitude the method includes repeating the second, third and fourth acts until the load magnitude is at the desired level.

Abstract: An electronic circuit comprising means (CMNS) for controlling a current (IL) through a coil (L) for the generation of a magnetic field (H). The means (CMNS) comprise means (DMNS) for the determination of a parameter which is a measure for the value of the resistance (RL) of the coil (L). During operation the maximum absolute value of the current (IL) is decreased when the parameter exceeds a certain limit.

Abstract: Apparatus and method for real-time analysis of an electric power transmission link status direct buried or installed in a duct or a tunnel are described. The method includes: real-time measuring a surface distributed temperature of the link by using a distributed temperature sensor installed along a longitudinal direction of the link; calculating a conductor temperature of the link on the basis of the surface distributed temperature and an electric current flowing through the link; calculating a heat flow emitted out of the link on the basis of the surface distributed temperature and the conductor temperature; and real-time calculating a thermal parameter of an environment around the link on the basis of the heat flow. Thus, it is possible to calculate operating conditions of the link more accurately and improve safety of electric power transmission by real-time calculating the thermal parameter of the environment around the link.

Abstract: A feedback control system, comprising a flexible rod that may have an anchored end and a free end, the rod free end movable upon the application of electric potential to the rod, a current source coupled to the rod, a movement sensor disposed on the rod, and a circuit electrically coupled to the movement sensor and to the current source and having an external input, wherein the rod may include a shape memory alloy, a bimetal, or a piezoelectric material and wherein the rod may include one or more strips arranged in a pattern such as lengthwise or helically.

Abstract: A system for sensing movement comprising an elongate object having a restrained end and an unrestrained end which is free to move in at least two degrees of freedom in response to an applied force, the unrestrained end of the elongated object being configured to move in response to the applied force. An electrically conductive element is disposed on the elongate object and is configured to cooperate with the elongate object in producing a signal usable to determine the magnitude and direction of the movement of the unanchored end due to the applied force. Sensing circuitry is electrically coupled to the electrically conductive element and is configured for processing the signal from the electrically conductive element so as to determine a magnitude and a direction of deformation and produce a signal indicative of the magnitude and direction.

Abstract: A microwave power sensor and a method for manufacturing the same. The microwave power sensor includes a semiconductor substrate with a nitride or oxide film formed thereon. A membrane which is a portion of the nitride or oxide film is floated by removing a portion of the semiconductor substrate. First and second thermocouple groups are formed to be symmetrically spaced apart from each other on the membrane. An RF input end is formed on the nitride or oxide film. A heating resistor is formed on the membrane to be connected with the RF input end. First and second ground plates are formed on the nitride or oxide film at both sides of the RF input end. A third ground plate is formed on the nitride or oxide film to be connected with the heating resistor and electrically connected with the first and second ground plates. The first and second output terminals are formed on the semiconductor substrate to be connected with the first and second thermocouple groups, respectively.

Abstract: A wide-band RF signal power detecting element includes, on an insulating substrate (21), at least one thin-film resistor (22a) for absorbing the power of a signal to be measured and generating heat, first and second ground electrodes (27, 28) formed by thin-film conductors, a first thin-film connecting portion (24) for electrically connecting the first ground electrode (27) to the thin-film resistor (22a), a second thin-film connecting portion (25) for electrically connecting the second ground electrode (28) to the thin-film resistor (22a) and narrowing the gap between the first and second thin-film connecting portions (24, 25) toward the thin-film resistor (22a), and an input electrode (26) formed between the first and second ground electrodes (27, 28) and electrically connected to the thin-film resistor (22a).

Abstract: A wide-band RF signal power detecting element includes, on an insulating substrate (21), at least one thin-film resistor (22a) for absorbing the power of a signal to be measured and generating heat, first and second ground electrodes (27, 28) formed by thin-film conductors, a first thin-film connecting portion (24) for electrically connecting the first ground electrode (27) to the thin-film resistor (22a), a second thin-film connecting portion (25) for electrically connecting the second ground electrode (28) to the thin-film resistor (22a) and narrowing the gap between the first and second thin-film connecting portions (24, 25) toward the thin-film resistor (22a), and an input electrode (26) formed between the first and second ground electrodes (27, 28) and electrically connected to the thin-film resistor (22a).

Abstract: Voltage reversal in fuel cell stacks may be detected and/or prevented by monitoring each cell or small groups of cells in the stack for low voltage conditions. An improved cell voltage monitor is constructed using a plurality of voltage monitoring units in which each unit comprises a heating resistor, a rectifier in series therewith, and a sensing thermistor in thermal communication with the heating resistor. The heating resistor is electrically-connected across a cell or cells and heats the associated sensing thermistor in accordance with the voltage of the cell(s). Since the resistance of the sensing thermistor is indicative of its temperature and hence also of voltage of the cell(s), the sensing thermistor resistance can be used to signal a low voltage condition.

Abstract: A movement actuator includes an elongate filament made of a flexible material, and a strip of shape memory alloy disposed on the surface of one side of the filament. The shape memory alloy is responsive to actuation signals, heat or electrical signals, for changing its shape and when its shape changes, it causes the filament to move, i.e., bend, to accommodate the change in shape of the alloy. Also included is a signal supply device for selectively applying heat signals or electrical current to the strip of shape memory alloy to cause the alloy to change its shape and cause the filament to bend. Other patterns for the shape memory alloy could be disposed on the filament to cause other kinds of movements. For example, a helical pattern of the shape memory alloy about the filament would cause the filament to twist when the helical pattern were caused to shorten or lengthen.

Abstract: A current sensor and a method for measuring currents on an integrated circuit in an isolated manner. The current sensor uses a Peltier device as a thermal difference generator to generate a first temperature at a temperature generating junction and a second temperature at a second temperature generating junction. The two temperature generating junctions being spaced apart from one another and where the temperature difference between the first and second temperatures is a function of the sampled current. A Seebeck transducer operating as a thermal difference sensor has a first temperature sensing junction thermally coupled to the first temperature generating junction and a second temperature sensing junction thermally coupled to the second temperature generating junction.

Abstract: A current sensor and a method for measuring currents on an integrated circuit in an isolated manner. The current sensor uses a Peltier device as a thermal difference generator to generate a first temperature at a temperature generating junction and a second temperature at a second temperature generating junction. The two temperature generating junctions being spaced apart from one another and where the temperature difference between the first and second temperatures is a function of the sampled current. A Seebeck transducer operating as a thermal difference sensor has a first temperature sensing junction thermally coupled to the first temperature generating junction and a second temperature sensing junction thermally coupled to the second temperature generating junction.

Abstract: A sensor system for sensing movement comprises a rod anchored at one end to a base and plurality of strain gauges circumferentially disposed about the rod. The free end of the rod may be subject to forces in various directions. The strain gauges produce signals whose magnitudes are an indication of the degree of strain occurring at the location of the strain gauges. The use of three or more strain gauges spaced circumferentially about the rod provide both direction and degree of bend of the rod.

Abstract: A wide-band RF signal power detecting element includes, on an insulating substrate (21), at least one thin-film resistor (22a) for absorbing the power of a signal to be measured and generating heat, first and second ground electrodes (27, 28) formed by thin-film conductors, a first thin-film connecting portion (24) for electrically connecting the first ground electrode (27) to the thin-film resistor (22a), a second thin-film connecting portion (25) for electrically connecting the second ground electrode (28) to the thin-film resistor (22a) and narrowing the gap between the first and second thin-film connecting portions (24, 25) toward the thin-film resistor (22a), and an input electrode (26) formed between the first and second ground electrodes (27, 28) and electrically connected to the thin-film resistor (22a).

Abstract: A method and apparatus for determining the thermal capacity of overhead power lines is disclosed. The apparatus includes two rods of similar diameter and material properties to the line to be rated. One of the rods has a heater inside that dissipates a known amount of energy approximately equal to what the line loses during operation at the static rating. The rods are oriented parallel to the line and the temperature of each is measured. Using this information and standard equations governing the cooling of power lines, a very accurate, real-time reading of the line's thermal capacity is generated.

Abstract: A method and system for transporting electric power in a link and for the analysis of the status of an electric power transmission link and the relevant current rating capability control. The method includes dividing the link into a predetermined number of segments, each segment having an associated prediction model and at least two associated temperature sensors. Upon receiving sensor values, an expected operating condition in one of the segments is determined based on the sensor value and the electric current value. Next, an actual operating condition in the segment is determined and compared with the expected operating condition. If there is a difference between the conditions, a second predetermined prediction model is associated with the segment.

Abstract: A circuit for determining power changes in an RF circuit includes first and second temperature sensitive resistors connected in parallel with an RF input terminal so as to have a common junction therewith. The first resistor has a positive temperature coefficient of resistance and the second resistor has a negative temperature coefficient of resistance. A DC input terminal is connected to one of the temperature sensitive resistors and an output terminal is connected to the common junction of the two temperature sensitive resistors. Third and fourth temperature sensitive resistors have a common junction. The third resistor has a positive temperature coefficient of resistance and the fourth resistor has a negative temperature coefficient of resistance. The DC input terminal is also connected to one of the third and fourth temperature sensitive resistors, and an output terminal is connected to the common junction of the third and fourth temperature sensitive resistors.

Abstract: A current sensor assembly of planar form arranged for connection in series with an electrical circuit. The circuit includes a first and second conductor. The sensor assembly includes a first conductive member adapted to contact the second conductor in the circuit. A second conductive member is adapted to contact the second conductor in the circuit. A thin layer of conductive material is connected at one end to the first conductive member and at is other end to the second conductive member so that current flow in the circuit between the first and second conductors is via the thin layer. A support supports the thin layer along its entire length. At least a part of the support contacts the thin layer is electrically insulative. The thermal conductivity of the support is different at different points along the length of the layer so that heat disposition is different at the different points and hence the temperature rise caused by current flow through the layer is different.

Abstract: A thermoelectric measurement converter is disclosed, which forms the output signal as the product of the instantaneous values of two input signals; wherein the measurement converter comprises at least one electronic resistor and at least one temperature sensor, both being disposed on a common base which is heat insulated with respect to the environment.

Abstract: Controlled bending movement of a flexible elongate rod or filament in response to a bend signal indicative of a desired amount of bending is effected by a strip of shape-changing material disposed on a first side of an elongate rod element, the shape changing material changing shape in response to an actuation signal, thereby causing the filament element to bend, and a sensor including a strain gauge disposed on the rod element on a second side opposite the first side, said sensor sensing the amount of bend in the rod element from strain indicated, and a feedback control comparing the amount of bend of the filament sensed to a desired amount of bend defined by said bend signal and altering the actuation signal as required to make the amount of bend sensed the same as the amount of bend desired.

Abstract: A device for measuring the voltage of a voltage source includes a number of temperature responsive displays and a circuit including a number of heating circuits, each heating circuit for heating one of the temperature responsive displays when a threshold voltage of the heating circuit is exceeded, and a printed resistor, each heating circuit being connected to a length of the printed resistor such that the voltage of the voltage source at which each heating circuit heats a temperature responsive display is a function of the ratio of the lengths of the printed resistor to which the heating circuits are connected.

Abstract: Electrothermal conversion elements, apparatus and methods for use in comparing, calibrating and measuring electrical signals utilizing a thin film heater on a thin, low mass, low thermal conductivity substrate and low mass thermoresistive or PN junction thermal radiation sensors. The element emits IR radiation in response to electrical input. The radiation is collected and converted to an electrical signal proportional to the RMS value of the input signal. Isothermal operation enhances both IR and electrical operation.

Abstract: A movement actuator includes an elongate filament made of a flexible material, and a strip of shape memory alloy disposed on the surface of one side of the filament. The shape memory alloy is responsive to actuation signals, heat or electrical signals, for changing its shape and when its shape changes, it causes the filament to move, i.e., bend, to accommodate the change in shape of the alloy. Also included is a signal supply device for selectively applying heat signals or electrical current to the strip of shape memory alloy to cause the alloy to change its shape and cause the filament to bend. Other patterns for the shape memory alloy could be disposed on the filament to cause other kinds of movements. For example, a helical pattern of the shape memory alloy about the filament would cause the filament to twist when the helical pattern were caused to shorten or lengthen.

Abstract: The effects of differential heating inside the calorimetric bridge are reduced by first heating the bridge externally and controlling the resulting temperature. The bridge is also heated internally by an amount that varies according to the applied power to be measured. This acts to eliminate the principal source of thermal gradients in the first instance. By applying this heat as a common mode input signal to the two terminating loads of the calorimetric bridge the bridge itself does not become unbalanced, and therefore does not attempt to measure that common power. Actual input power to be measured does initially unbalance the bridge, and is still measured as usual. A constant power circuit is response to the indication of measured power and acts to keep the sum of measured power (plus the equal amount of feedback power that balances the bridge) and the common mode power at a constant value corresponding to a full scale measurement.