Abstract: A miniature solid state fluid flow sensor has a low diffusivity substrate, such as a polymer film, which is optionally mounted on a thermally conductive base. A resistor strip on the substrate is connected to an electrical oscillator and thus emits thermal waves which are propagated through the fluid at a rate dependent on a fluid flow component perpendicular to the strip. A thermoelectric detector, spaced from one side or each side of the strip, senses the thermal waves; and detector circuitry determines the time or phase shift due to fluid flow.A reference sensor is positioned relative to the primary flow sensor to compensate for the effects of pressure and temperature changes and uses properties of symmetry to assure low sensitivity to variations in the direction of fluid flow.

Abstract: Ultrasonic transducers spring biased into seating engagement in a pair of opposed spot welding tips transmit and receive ultrasonic waves and associated circuitry measures the time of flight between the transducers which is a function of tip separation, workpiece temperature and nugget size which are indicators of the progress of a weld. The rate of change of flight time is measured and the weld current is adjusted early in the weld cycle to maintain a preset rate of weld growth. The weld current is terminated later in the cycle if the transit time rate falls below another preset value. Otherwise the weld current and termination time follow a standard schedule.

Abstract: To couple light signals between two relatively rotating parts, two rings of transparent material, each mounted on one of the parts, are provided on a common axis and have a slight spacing between their rings which is filled with an index matching fluid. Recesses in each ring are provided to receive light emitters or detectors, respectively. Each recess defines a curved wall serving as a light collection or focusing lens which serves as a window into or out of a ring. The assembly is completed by a pair of coaxial spacers or retainers each of which are mounted on one of the relatively rotating parts and also secured to one of the transparent rings. Light coupled into one of the rings through a window is transmitted by the index matching fluid to the other ring and it is emitted from a window of that ring.

Abstract: A rocker switch assembly includes a rocker pivoted about a central axis, an actuator responsive to the rocker and pivoting about either end, and conductive rubber push-button switches selectively operated by the actuator with minimum lateral deformation. The actuator is translucent to serve as a light conductor to carry light from an adjacent lamp to the rocker which bears translucent legends. The actuators of adjacent pairs of switch mechanisms are lit by a single lamp between them.

Abstract: An illuminated pushbutton switch has a translucent button aligned with a lamp, a stationary contact, and a sinuous spring urging the button to its released position, the spring being bifurcated and straddling the lamp to allow a clear illumination path. The spring serves as the movable contact of the switch and engages the stationary contact when the button is depressed.

Abstract: A method and apparatus are disclosed for analyzing the dynamic resistance of a resistance spot welding process to determine the time of an expulsion event and use that time as the weld completion time for controlling weld termination via a weld feedback signal, controlling automatic current stepping, and identifying maintenance needs. A preconditioning pulse is used to stabilize the weld process and aid in obtaining interpretable resistance information. After an initial blanking period the resistance curve is analyzed by calculating first and second derivative values and applying several algorithms that make possible the computer recognition of characteristic resistance curve shapes resulting from weld expulsion under good geometry, bad geometry and edge weld conditions.

Abstract: Spectroscopic measurements of stable isotopes are performed using a tunable lead salt diode laser. The design of the system is based upon the optimization of isotopic spectral lines from two different path lengths in an absorption cell using a single gaseous sample. A short path cell to measure the more abundant species and a long path cell to measure the less abundant species are used. A micrometer adjustment of a path length is used for equalizing spectral line intensities to obtain a measure of isotope enrichment or of absolute isotopic concentration.

Abstract: A method and apparatus are disclosed for resistance spot welding including applying a preconditioning pulse at the beginning of a welding process to stabilize the resistances at the interface of the sheets being welded and at the interface of the electrodes and the sheets. A current pulse is applied just after contact of electrodes and the workpiece when the electrode force is between about 10% and 75% of its final value to melt interface surfaces followed by a cooling time to permit dissipation of heat from the interfaces, and is finally followed by a conventional weld current schedule. The contact time is determined be electrically monitoring the conductivity between the electrodes as they are moved toward the workpiece. Alternatively, the applied electrode pressure is monitored to determine when sufficient electrode force is applied to the workpiece to achieve the proper resistance for the pulse application.

Abstract: A first linear sensor tracks the movement of an object through an inspection station and a second linear sensor views the object transverse to the object path to acquire a line image of the object, and a synchronizing arrangement responds to the sensed position of the object to trigger the second sensor at spaced object positions to obtain a plurality of line images which cummulatively represent the object image. The image is compared, line-by-line, as acquired with a stored model of the object to determine the correlation between the object and the model.

Abstract: A self aligning microbend sensor comprises a tubular housing having internal threads, an expandable insert with external threads loosely threaded into the housing with sufficient tolerance to allow expansion of the insert in response to a parameter being measured while maintaining registration of the threads, and a fiber optic element between the housing and the insert and extending transverse to the threads, such that upon expansion of the insert the fiber optic element experiences microbending due to deformation by the threads.

Abstract: A precipitation sensor for detecting when a predetermined fraction of the sensor area is covered with water drops comprises an insulating substrate, a pair of spaced electrodes of conductive material on the substrate, and an array of conductive spots on the substrate between the electrodes, the spots being arranged to define an open circuit between the electrodes when the substrate is dry and a closed circuit when at least some of the spots are bridged by water drops. This sensor uses the physical principle of percolation to respond accurately to small amounts of precipitation and is preferably integrated in the wipe area of a windshield surface and is incorporated in the wiper control system.

Abstract: A method of forming perforations in polymer film includes the steps of forming a conductive film pattern on the film preferably in a bow tie shape using a material with a moderate resistivity and applying a microwave field across the film for a few seconds whereupon sufficient electrical energy is dissipated in the conductive spot to perforate the polymer. This method is operative even when the polymer film is laminated between layers of other dielectric material prior to the microwave processing.

Abstract: The inductors in an induction heating apparatus are arranged in parallel branches with an SCR in series with each inductor and an RC snubber circuit in parallel with each inductor. If an SCR becomes shorted the faulty SCR is detected by a method and apparatus for coupling a capacitor across the inductors one at a time, exciting the capacitor-inductor circuit with a frequency suitable to induce a resonant condition provided the inductor is in series with a normal SCR and whereby resonance will not occur if the inductor is in series with a shorted SCR, and sensing circuit resonance thereby detecting whether the SCR in series with the selected inductor is shorted.

Abstract: A method of measuring the velocity of a fluid by noninstrusive means comprises passing a pump laser beam pulse through the fluid wherein the fluid contains a constituent absorbing the wavelength of the laser so that a temperature gradient, and therefore an index of refraction gradient, occurs in the laser beam path; and a probe laser beam is passed transverse to the pump laser beam and is deflected by the heated portion of the fluid; measuring the beam deflection and calculating from that the fluid velocity. After the pump pulse the amount of deflection reaches a peak value and then decreases at a rate independent of the concentration of the absorbing constituent. Where the pump laser beam has a Gaussian spatial profile, the deflection signal decreases according to: exp-2(v+/a).sup.2, where v is the velocity; t is time; and a is a constant representing the pump laser beam radius.

Abstract: A method of measuring the velocity of a fluid by nonintrusive means comprises passing a pulsed pump laser beam through the fluid wherein the fluid contains a constituent absorbing the wavelength of the laser so that a temperature gradient, and therefore an index of refraction gradient, occurs in the laser beam path; and a probe laser beam is passed transversely to the pump laser beam and is deflected by the heated portion of the fluid by an amount which is proportional to the concentration of the absorbing constituent and inversely proportional to the velocity of the fluid; measuring the beam deflection and calculating from that the fluid velocity, if the concentration of the absorbing constituent is known, or calculating the relative velocity if the concentration of the absorbing constituent is constant.

Abstract: Diesel fuel tends to deposit an insulating coating on surfaces it contacts. A probe, preferably in the form of a siphon tube, is coupled to a detection circuit which is responsive to either low resistance or high capacitance between the probe and ground. The probe is initially uncoated to make a resistive coupling to a fuel container when accumulated water touches the probe. When insulating deposits from the diesel fuel or other fuel oil coat the probe, capacitive coupling will occur between the probe and the accumulated water. In either case the presence of water triggers an output signal by the detection circuit.

Abstract: To reduce the temperature compensation error of a hot element mass airflow sensor due to thermal radiation losses, the element is coated with a low emissivity material. In the case of a hot film sensor which comprises a thin metal foil resistor sandwiched between polymer layers, the outer surface is covered with a low emissivity coating comprising a thin metal layer which is highly reflective to infrared radiation. A circuit supplies energy to the element to heat it to a prescribed temperature; the power required to maintain that temperature correlates with the rate of convective energy loss to the airflow and thus to the rate of mass airflow.

Abstract: Accurate dimensional control in ultrasonic welding or upsetting of plastic parts is accomplished by the method and apparatus for monitoring the ultrasonic head displacement and sensing when a predetermined trigger force is applied to the part or parts, turning on the ultrasonic energy at the trigger point and terminating the ultrasonic energy when head displacement from the trigger point reaches an empirically established value, holding the force for a hold time and measuring the maximum displacement value at the end of the hold time, releasing the force when the force returns to the trigger point, measuring the overall displacement, and determining whether the overall displacement is within allowable tolerance values. Weld time and weld energy as well as the overall head displacement are monitored for comparison with preset tolerance values to determine acceptability of the part being processed.

Abstract: At least one fiber optic light conductor extends from a source and detection area to a measurement area. In the measurement area, the fiber end is prepared with an end surface slanted relative to the fiber axis and the slanted surface is coated with a reflective material so that light conducted through the fiber is reflected from the end surface and through the side wall of the fiber onto an object being measured. Light is reflected from the object in an amount depending upon the position of the object and reflected light is carried through a similar path by the same or a similar optical fiber to the detector, such that the detector signal correlates to the position of the object.

Abstract: A tool for dressing copper spot welding electrode tips to a desired configuration comprises a disc with opposed concave faces formed at their centers in the desired configuration of the tips and adapted to be rotatably driven by a power tool. The dressing surfaces are uninterrupted surfaces of revolution and, therefore, contain no cutting edges. In operation, the electrode tips while mounted on a welding machine are clamped against a rotating dressing tool with normal welding pressure, so that as a result of the frictional engagement of the tool with the tip, the metal flows into conformity with the tool surface. Thus, no significant amount of metal is removed from the welding tip.