Abstract: An apparatus for immunoassay using a 96-well microplate includes a mechanism for supporting the microplate in a relatively fixed position, a magnetic microplate assembly containing multiple cylindrical magnets positioned in 4.times.6 arrays for insertion from the bottom of the microplate in the spaces between the wells of the microplate, and a device for moving the magnet microplate assembly relative to the microplate thereby to permit selective separation of magnetic components within the microplate wells. The magnets, preferably cylindrical in configuration, are placed between groups of four wells in the microplate. The magnetic microplate assembly is reusable. The magnets do not come into contact with any of the fluids within the wells of the microplate.

Abstract: The present invention is a brake control system for preventing the skidding of a wheel on a surface. The phase relationship between the brake pressure applied to the brakes and the torque created from the braking applied is determined. This relationship allows the present brake control system to maintain the wheels from skidding on a surface by maintaining a positive slope of such brake pressure and torque phase relationship. A second embodiment provides a backup system wherein the percentage of slip is determined and compared to an input percentage slip. The second embodiment system overrides the torque command system when the torque command system fails.

Abstract: An eddy current probe for nondestructive testing, having a rotatable shoe that holds the eddy current coil. The probe is attached to an arm of automated eddy current test equipment, and has a coil-containing shoe that may be rotated to a desired angle with respect to the surface to be inspected. The probe has a motor and pulley system for providing this rotational motion.

Abstract: Method and apparatus for reducing the effects of noise jamming on coherent frequency or phase modulated signals employs a two channel radio signal processing system (15, 20) which accepts an input signal containing a desired signal (S) and a jamming signal (J) from a receiver input circuit (10). In the first channel (15), a hetrodyne mixer (30) and wideband filter (35) select the difference frequency component between the jamming signal and the desired signal [X(t)] while in the second channel (20), a local oscillator (45), mixer (50) and filter (55) function to select the difference frequency between the jamming signal and the local oscillator [Y(t)]. A third mixer (90) and bandpass filter (95) combines the outputs X(t) and Y(t) to provide the desired signal, including its original phase and frequency modulation components substantially independent and free of the jamming signal, to the receiver output circuit (12).

Abstract: A detachable, articulated rotating eddy current inspection tool includes a body member having a connector at one end for mechanically and electrically attaching the body member to a rotating drive member while at the other an eddy current probe is supported for radial movement with respect to the axis of rotation of the body member. A motor located within the body moves a slide on which the probe is mounted while at the same time a counterbalancing slide is moved radially in the opposite direction to maintain said tool in dynamic balance. An encoder housed within said body member senses the location of said eddy current probe with respect to the axis of rotation of said body member. A rotary transformer is used to transfer signals which control the position of the probe and to receive information from the eddy current probe and the encoder. The encoder output signals are modulated by the eddy current probe exciter signal to enable probe positions information to be sent through a rotary transformer.

Abstract: A detachable, articulated rotating eddy current inspection tool includes a body member having a connector at one end for mechanically and electrically attaching the body member to a rotating drive member while at the other an eddy current probe is supported for radial movement with respect to the axis of rotation of the body member. A motor located within the body moves a slide on which the probe is mounted while at the same time a counterbalancing slide is moved radially in the opposite direction to maintain said tool in dynamic balance. An encoder housed within said body member senses the location of said eddy current probe with respect to the axis of rotation of said body member. A rotary transformer is used to transfer signals which control the position of the probe and to receive information from the eddy current probe and the encoder. The encoder output signals are modulated by the eddy current probe exciter signal to enable probe position information to be sent through a rotary transformer.

Abstract: A light weight data recorder employs a non-volatile electronic memory to store several channels of data occurring before and after a triggering event. Data may be retained in the memory with the aid of a NiCad battery. Upon the occurrence of a triggering event, which may be user defined, the input of new data into the memory will be terminated after a selectable predetermined time has passed. This allows data to be recorded both before and after a specified event. The triggering event may be derived by sensing a change in the signal level of one of the data inputs by a predetermined amount, or it may be a specially generated signal. Once a triggering event has occurred, the data retained in memory is protected. Circuit means are provided to retrieve the stored data without destroying it. Another circuit permits recording of new data in the memory only after a unique signal has been detected.

Abstract: An infrared aircraft lighting system designed for use in connection with night vision goggles includes a ring structure containing infrared lights that is installed between an existing visible light beacon and the aircraft outer surface, without requiring modification of either the aircraft structure or the existing visible light beacon. A central opening in the ring is aligned with the opening in the aircraft that was created to receive the visible light beacon. A plurality of holes extending through the ring structure permit the mounting bolts passing through a flange on the beacon light to extend on into the aircraft, thus securing both the visible light beacon and the ring structure on the aircraft. A plurality of infrared lights are mounted on said ring structure in a circular pattern so as to be visible from above. A slot formed in the ring's lower surface accommodates the electrical wiring necessary to supply power to the infrared lights.

Abstract: An apparatus for maintaining the end of a probe carrying a sensor, such as an eddy current probe, a predetermined distance from a workpiece includes a housing in which a piston is permitted to move. Air under pressure, introduced into a first chamber formed within the housing, acts on a first surface of the piston to urge it toward the workpiece. An air bearing is used to permit the almost friction free axial movement of the piston within the housing. Some of the air passes from the first chamber through a restricted opening in the piston into a second chamber and is vented toward the workpiece. The pressure in the second chamber will vary as a function of the distance of the end of the probe to the workpiece surface. The piston is provided with a second, larger, surface area exposed to the variable pressure in the second chamber, and as a result, the piston is urged away from the workpiece.

Abstract: Powders, and particularly metallic powders, are produced by electro-discharge machining of electrically conductive electrodes made of the desired materials in a cryogenic dielectric. When a sufficient quantity of powder has been produced, the cryogenic dielectric is allowed to evaporate, leaving the powders available for recovery. Powders formed by this process have unique microstructures, and thus unique properties, as a result of rapid cooling in the cryogenic medium. By using an inert cryogenic dielectric, such as argon, powders uncontaminated by the dielectric are produced.

Abstract: In a dual mode CRT deflection circuit, a capacitor for effecting rapid retrace of the CRT beam by means of resonant nonlinear operation is selectively shunted such that beam deflection may be linearly controlled. A bidirectional switch preferably comprising a field effect transistor (FET) is connected in parallel with the capacitor which in turn is connected in series with the deflection coil of the CRT with the series combination being driven by an amplifier in response to beam positioning signals. When the bidirectional switch is activated to shunt the capacitor, the deflection control circuit operates in a linear mode; and when the switch is deactivated, the deflection coil of the CRT interacts with the capacitor for resonant nonlinear operation. A comparator circuit is connected to the output of the amplifier and coupled to the bidirectional switch through an optical coupler to activate and deactivate the switch in response to conditions within the deflection control circuit.

Abstract: An acoustical transducer is provided with an acoustically absorbant backing material having an acoustical impedance precisely matching the impedance of the piezoelectric element in the transducer. The backing material is a multiphase mixture of selected materials, such as a low melting point alloy (InPb) and one or more powders having high impedance characteristics (tungsten and copper). The slope of the curve impedance versus volume fraction of the backing components is low, thus allowing the impedance of the material to be precisely controlled. The backing material is preferably electrically conductive and is fuzed to one surface of the piezoelectric element to further improve the output characteristics of the transducer.

Abstract: An acoustical transducer is provided with an acoustically absorbant backing material having an acoustical impedance precisely matching the impedance of the piezoelectric element in the transducer. The backing material is a multiphase mixture of selected materials, such as a low melting point alloy (InPb) and one or more powders having high impedance characteristics (tungsten and copper). The slope of the curve impedance versus volume fraction of the backing components is low, thus allowing the impedance of the material to be precisely controlled. The backing material is preferably electrically conductive and is fuzed to one surface of the piezoelectric element to further improve the output characteristics of the transducer.

Abstract: Interference patterns are generated in response to temporally coherent light incident upon an interferometer which directs the interference patterns upon an array of photosensitive elements. The photosensitive elements are connected to generate signals representative of the optical energy respectively incident on the elements. The output signals of the photosensitive elements are averaged by a passive resistor network coupled to the photosensitive elements and the signals generated by the individual elements are compared to the average signal by individual comparator circuits to detect the presence and position of an interference pattern directed upon the array.

Abstract: An acoustical transducer is provided with an acoustically absorbant backing material having an acoustical impedance precisely matching the impedance of the piezoelectric element in the transducer. The backing material is a multiphase mixture of selected materials, such as a low melting point alloy (InPb) and one or more powders having high impedance characteristics (tungsten and copper). The slope of the curve impedance versus volume fraction of the backing components is low, thus allowing the impedance of the material to be precisely controlled. The backing material is preferably electrically conductive and is fuzed to one surface of the piezoelectric element to further improve the output characteristics of the transducer.

Abstract: Reflections, having positive and negative Doppler frequency shifts, from a laser beam directed at a moving surface are passed through spatial filters, combined by a beam splitter, and focussed on an observation plane of a photodetector to provide a fringe pattern having an amplitude variation frequency responsive to the velocity of the moving surface. The laser beam may be a single beam directed substantially perpendicularly to the moving surface, or the laser beam may be divided into two beams angled toward the surface, one beam impinging with the direction of motion of the surface and the other beam impinging against the direction of motion. When two impinging beams, split from a common beam, are utilized, different polarizations and beam impingement points on the surface may be used to provide beam isolation between the beam signals. Homodyne detection with single frequency lasers is used.

Abstract: A method of ultrasonically inspecting the internal structure of a multi-ply composite material using ultrasonic transducers includes the steps of positioning an ultrasonic transmitter in acoustical contact with one surface of the material, directing a beam of acoustic energy into the material with the angle of incidence of the beam with respect to the surface being less than the second critical angle for the material but greater than normal to the surface, and receiving the reflected energy. In one embodiment, the transmitting and receiving transducers are positioned with their axis perpendicular to the orientation of the reinforcing fibers within the ply being inspected. In another embodiment, the transmitter and receiver are aligned at equal angles on either side of a line which is perpendicular to the orientation of the fibers. The receiver may be located on the same or the opposite side of the material from the transmitter.

Abstract: Dense silicon nitride bodies are fabricated using conventional hot-pressing techniques using cerium oxide as a densification aid. The bodies are then further treated in a flowing inert atmosphere at a temperature of from 1400.degree.-1600.degree. C. for from several hours to 48 hours to remove all or substantially all of the densification aid from grain boundaries. Silicon nitride bodies so treated exhibit superior elevated temperature slow crack growth resistance and strength properties and are suitable for use as structural components in high temperature environments such as jet and internal combustion engines, rockets, atomic power generation, and the like.

Abstract: A microprocessor-based ultrasonic inspection system reliably detects fatigue cracks smaller than 0.030 inch under installed fasteners by means of a unique signal-processing method. The signal-processing used in this invention takes advantage of the fact that crack signals "walk" in time as a transducer moves around a fastener. Bolt size, scan depth, and angle of incidence of an ultrasonic shear wave are used to determine the "walk rate" of a defect in the inspection zone. With this geometric information, the signal-processing technique will enhance any pulse-echo return "walking" at the computed walk rate, and thus significantly improve the ratio of crack signal to other signal sources in the material.

Abstract: An optical micrometer scans an article passing through its zone of measurement to provide a series of pulses representing the dimension of an article. Each new measurement is compared against a previous measurement, or an average of a predetermined number of previous measurements, and the difference is then compared to a previously established deviation limit. If this difference does not exceed the deviation limit, then the new measurement is transferred to the output of the circuit for utilization by the system, but if this difference exceeds the deviation limit, then the previous measurement signal will be transferred to the output. An alarm is provided whenever a predetermined number of new measurement signals outside the deviation limit occur within a certain number of measurement intervals.