Abstract: A linear transducer array with low overall side lobe sensitivity for use in steered beam imagers has a different interelement spacing for transmit than for receive, and preferably has a shorter transmit array with elements spaced at one-half wavelength as the center portion of a longer receive array whose unit elements are spaced at a full wavelength. Two or more elements in the center portion can be coupled together to a receiving channel to maintain constant spacing for the receive aperture in a 100% active transducer.

Abstract: A curved transducer array or a flat array with an acoustic converging lens functions as a fixed focus physical lens and is focused near maximum range. At longer ranges the full aperture is utilized for good resolution, and at shorter ranges up to a specified fraction of maximum range improved resolution is achieved by a dynamic aperture control which increases the array aperture by steps by switching in more transducer elements. This simplified sector scanner does not require dynamic electronic focusing.

Abstract: A B-scan ultrasonic imager such as a single-sector scanner has a dynamic aperture and focus control to attain improved lateral resolution especially at ranges less than the maximum array aperture. As the range from which echoes are being received propagates out, the array aperture during each echo reception period is increased by steps by switching in more elements of the total transducer array. At least one adjustment of receiving channel time delays is made to dynamically focus the echoes at different focal points.

Abstract: An ultrasonic multi-sector scanner performs overlapping scans such that echoes are generated by many steered beams. A peak reading digital scan converter has a random access memory with a matrix of memory cell locations corresponding to image pixels. An analog or digital comparator compares the incoming echo amplitude with the stored amplitude at an addressed memory location, and writes the incoming data into that location only when the incoming amplitude is larger. The stored largest echo amplitude data is read out in a raster at TV rates for imaging on a cathode ray tube.

Abstract: The time-of-arrival of timing signals transmitted by two satellites is measured relative to a crystal clock, and an approximate position fix is computed for the ship or other object being located. Because of clock error the position fixes are displaced along a hyperbolic line of position. A two-way active range measurement through a third satellite or one timing signal satellite enables computation of an independently determined line of position, the true position fix being at its intersection with the hyperbolic line of position. The clock error is corrected and the method of position fixing from two timing satellites is repeated until the clock drift exceeds acceptable limits. A continuous navigation service and also position surveillance are realized.

Abstract: The position of a ship or other object being located is determined at an earth station using an active ranging satellite and a satellite which transmits time signals. One line of position is determined by two-way active ranging through the first satellite. The other line of position is determined by one-way ranging from the second satellite. The time interval between the time of arrival of the timing signal at the ship and reception of the active ranging signal at the ship is measured and sent back to the earth station with the ship's active ranging response. The position fix is then computed at the earth station.

Abstract: A steered beam B-scan ultrasonic imaging system has a linear transducer array divisible into multiple sub-arrays of transducer elements each operable to perform a sector scan, with the origin points displaced longitudinally along the array between sector scans. The system performs overlapping sector scans and is capable of imaging randomly oriented specularly reflecting targets. Time delays in the transmitting and receiving channels to steer the transmitted beam and to focus the received echoes are provided by digital techniques, by reversible digital shift registers, or by charge coupled device delay lines. The multiple sector image is displayed in real time in an intensity versus displacement format on a cathode ray tube.

Abstract: Liquid amorphous metal alloy is manufactured into shaped laminations ready for assembly in an inductive component in one process. The rotating chill surface to which the melt is delivered has high thermal conductivity metal in a pattern corresponding to the shaped lamination and is surrounded by thermally insulating material. Melt coming in contact with the high thermal conductivity metal becomes amorphous and that contacting the thermally insulating areas cools more slowly and becomes crystalline. The brittle crystalline scrap is broken away from the strip of laminations and is collected and recycled to the melt.

Abstract: The frequency response of the cutting tool of a coal mining machine is monitored at a resonant frequency of the cutting tool, using a vibration transducer mounted on a non-rotating support arm, to detect the difference between coal and rock or other enclosing material. The horizon control sensor maintains the mining machine within the undulating coal seam.

Abstract: A decogging feedback control for current source inverter motor drives uses a change of instantaneous torque feedback signal with no dc component that is a function of only the instantaneous pulsating component of measured torque. The change of torque signal modulates the voltage applied to the dc link and therefore the dc link current to materially reduce the detrimental cogging torque pulsations and stabilize the motor, and can be switched out at a low frequency above which it is not needed so that the motor can respond properly to rapid variations in torque.

Abstract: An interdigitated field effect transistor for high power, high frequency applications has a vertical configuration with current flow essentially normal to the surface, as compared to planar devices in which current flow is parallel to the surface. Each channel region is of the same conductivity type as the source and drain regions and is in a mesa structure surrounded by the gate metallization such that the gate metal forms an electronically blocking contact to the channel semiconductor. The device geometry has a natural strip line configuration.

Abstract: A B-scan ultrasonic imager produces a rectilinear image and has a linear transducer array with only one switch per element. Individual elements or overlapping transmit subarrays are selected sequentially to generate pulses of ultra-sound. Received echo signals are sequentially sent down a long shift register delay line, are tapped off at the pulse repetition rate, and delayed by different amounts in the several channels and summed to effect time delay focusing of the echoes. The video output signal is post-processed to improve the TV monitor picture; interpolated image lines are conveniently derived with this architecture.

Abstract: An ultrasonic imaging system for medical and industrial applications produces quantitative acoustic impedance distributions from reflection data. The method and scanner apparatus with analog computation circuitry herein described acquires echo pulses reflected from impedance discontinuities in the specimen and computes impedance projections. The ensemble of projections, as in other computerized tomography systems, is used for reconstruction of the images which in this case are impedance distributions in a thin slice of the specimen.

Abstract: A method for fabricating an electric machine stator core and winding assembly characterized by insulated sectionalized coils suitable for automatic fabrication and assembly. Bundles of straight coil side wires are externally insulated and inserted longitudinally into the stator slots, and the coil end turns are manufactured separately as planar arrays of printed circuit conductors or discrete wires adhered to end cap insulating boards. Upon stacking the boards against each stator core end face, the aligned coil end turns and sides are selectively joined to form a continuous winding. The objective is lower cost wound stators for small and medium ac and dc motors.

Abstract: A method and circuit for calculating the instantaneous pulsating component of torque for use as a cogging feedback signal to stabilize ac motors at low frequencies. An air gap flux signal is generated by integrating the instantaneous voltage across a stator phase winding during the interval the current in that winding is zero. Pulsating torque is the product of the high pass filtered flux signal and the inverter input or dc link current.

Abstract: A semiconductor controlled avalanche triode operableat microwave frequencies is turned on by a narrow pulse, and remains conducting due to the positive feedback effect of returning carriers in the base region until turned off by an opposite polarity narrow pulse. Applications include a fast switch, a memory device, and various logic circuits such as logic gates and shift registers. The memory and logic devices are fast, require low power, available in npn or pnp configurations, are simple with one triode per memory, and can be made of silicon so as to be integrable.

Abstract: To locate a corona fault in a transformer or other encased electrical apparatus by determining the propagation time for acoustic noise generated by a corona discharge, the electrical corona signal is gated and level-detected during an interval which is adjustable as to delay and length to thereby generate a timing reference to initiate acoustic signal averaging. The corona pulse can be found that results in an optimum signal-to-noise ratio in the acoustic signal being averaged, as is needed with limited test data in a noisy or reverberant acoustic environment. Also, multiple corona sources can be located.

Abstract: A binary pseudo-random sequence generated by a shift register with feedback is used as a noise signal for testing an electrical or mechanical system, and the output is sampled and the power spectra computed by discrete Fast Fourier Transform techniques. The sequence bit interval and sampling interval have a predetermined ratio, and either the noise signal or output test signal is low pass filtered, with the result that closely spaced equal amplitude sine waves are effectively applied to the system under test and their responses separated at the output with no statistical uncertainty.

Abstract: Electrical apparatus and power distribution systems are protected from lightning strike currents and voltages by the addition of mutually coupled chokes, such as bifilarly wound chokes, in electrical series relationship with the apparatus and the power distribution system to increase the impedance therebetween and cause lightning currents to flow along alternate current paths.

Abstract: A loaded spring in a pressure relief valve or other spring-loaded device is excited with acoustic vibrations and the resonant frequencies of selected vibration modes are measured. Changes in spring constant due to aging and high temperature are detected by monitoring the longitudinal vibration mode resonant frequency, and changes in loading by monitoring the transverse and/or torsional vibration mode resonant frequency. The pressure set point is ascertained from manufacturing data of resonant frequency versus set point.