Abstract: A method of measuring the instantaneous shaft velocity of a rotary machine having a shaft with a plurality of circumferentially spaced markers thereon, comprises the steps of sensing the passage of the markers with at least two circumferentially spaced sensors mounted adjacent the shaft to generate pulses in response to the passage of the markers; for each of the sensors continually deriving from the pulses and estimated spacing signals representing an estimated spacing of the markers, a set of angular velocity signals representing the instantaneous shaft angular velocity at a given point in time t.sub.i ; and varying the estimated spacing signals on an iterative basis to attempt to match the sets of angular velocity signals derived from the respective sensors. The described method allows a more accurate ICAV (Instantaneous Crankshaft Angular Velocity) waveform to be produced than was possible using prior art techniques.

Abstract: A scanning device has a drive system to angularly reciprocate a rotatable mirror about an axis in a desired waveform in accordance with an excitation signal supplied by a programmable waveform generator. A position sensor generated as signal representing the actual waveform of reciprocation of the mirror, and a microprocessor determines a signal representing the error between the actual waveform and the desired waveform. The microprocessor includes a waveform optimizer that receives this error signal and delivers an excitation correction signal to the waveform generator to adjust the excitation signal from the waveform generator to cause the mirror to have an actual waveform substantially in accordance with the desired waveform.

Abstract: A three dimensional imaging device has a converging lens system defining an optical axis, known as the Z direction. The imaging device also includes a position sensitive detector that has a series of pixels extending in at least a selected one of two mutually perpendicular X and Y directions both perpendicular to the Z direction. The lens system will simultaneously image a plurality of distributed points on a target surface onto the detector to generate first data on the coordinate of each point on the target surface in the X and/or Y direction. Also included in the system is a mask having a pair of apertures spaced apart from each other in the selected direction and respectively aligned with portions of the lens system for imaging discrete dots on the detector. The spacing between the dots generates second data on the coordinate of each point on the target surface in the Z direction.

Abstract: A transimpedance circuit for generating an output voltage replica of an alternating current input has its accuracy improved by the use of a current comparator, the ratio windings of the comparator respectively carrying a current proportional to the input current and a current proportional to the output voltage. A further winding of the comparator detects any ampere-turns imbalance in the ratio windings, and, as a result, generates a correction signal proportional to such imbalance. This correction signal is then employed to correct the output voltage.

Abstract: A disc-shaped marine structure fabricated of steel and/or concrete, able to support useful loads as great as 125,000 tonnes, is tethered to float stably in very deep water, with only minor response motions to wave of large amplitude and long period. A planar base disc of diameter about 135 up to 200 meters carries a centered primary buoyancy tank of span 2.5 to 4.5 times the draft. The strongly braced sidewall of the tank is spaced about 10 meters inward of the disc edge, defining one wall of an upwardly open confinement chamber. A thin cylindric outer shell wall extending upwardly from the margin of the base has about 26% to 35% of its area comprised of tubular passages set radially, of length and diameter about one meter or more. Radial bracking frameworks of 50% aperturing interconnect the tank with the base disc and outer wall.A mass of seawater approximately equal to the structure's displacement is largely confined, its volume/aperture ratio being about 800 m.sup.3 /m.sup.2.

Abstract: A simple but precise procedure for measuring fish freshness in terms of trimethylamine (TMA) headspace concentration of a fish sample is provided based on air sampling the headspace with Carbotrap.RTM. or Tenax.RTM. sorbent tubes and subsequent thermal desorption and gas chromatographic analysis. The sampling and analysis are completed in less than five minutes. Fish freshness as determined by the TMA headspace concentration is consistent with the grading estimated by organoleptic tests, but the instrumental method provides a more objective and quantitative assessment of quality and an estimation of the post mortem age of the fish.

Abstract: An infrared absorption spectra recording, high pressure sample holder comprises a gasket for high compression between two diamond anvils, and an infrared light beam transmitting material partially filling a light passage through the gasket at a position between the two anvils to leave an infrared light beam transmitting, sample cavity adjacent one anvil. The surface of the filling is shaped, e.g. dished so that an infrared light beam passing through the sample will have light paths of different lengths, thereby avoiding optical interference fringes.

Abstract: An AC/DC converter is provided, suitable for use in an advanced single phase, sine wave voltage, high frequency power distribution system, such as that used on a 20 kHz Space Station Primary Electrical Power Distribution System. The converter comprises a transformer, a resonant network, a current controler, a diode rectifier and an output filter. The voltage source is converted into a sinusoidal current source. The output of this current source is rectified by the diode rectifier and is controlled by the current controller. The controlled rectified current is then filtered by the output filter to obtain a constant voltage across the load.