Abstract: Methods are described for using acoustic energy to agglomerate fine particles on the order of one micron diameter that are suspended in gas, to provide agglomerates large enough for efficient removal by other techniques. The gas with suspended particles, is passed through the length of a chamber (24) while acoustic energy at a resonant chamber mode is applied to set up one or more acoustic standing wave patterns (40,42,44) that vibrate the suspended particles to bring them together so they agglomerate. Several widely different frequencies can be applied to efficiently vibrate particles of widely differing sizes. The standing wave pattern can be applied along directions (R in FIG. 3) transversed to the flow of the gas. The particles can be made to move in circles by applying acoustic energy in perpendicular directions (P,Q in FIG. 6) with the energy in both directions being of the same wavelength but 90.degree. out of phase.

Abstract: An improvement in a method for simultaneously slicing one or a multiplicity of boules of silicon into silicon wafers, the improvement of which comprises forming a plurality of vertical stacks of horizontal saw blades of circular configuration arranged in juxtaposed coaxial alignment, each blade being characterized by having a cutting diameter slightly greater than the cutting diameter of the blade arranged immediately thereabove; imparting simultaneous rotation to the blades, supporting in depending relation a plurality of enlongated boules of silicon, simultaneously translating the boules through the blades, and simultaneously imparting rotation to the boules as the boules are passed through said blades for slicing wafers therefrom; and an improved apparatus for performing said method.

Abstract: A correlation spectrometer permanently incorporates a reference cell (12) and an electro-optical phase modulator (EOPM) (50) in the light path between a sample cell (30) and a detector (20). The effect of the EOPM is such that its frequency modulates all of the monochromatic component of the incoherent radiation passing through it. The EOPM is adjusted so that when it is ON all of the energy in the monochromatic components is thrown into sidebands (55) differing from the original frequencies by integral multiples of the modulation frequency, with the total amount of energy absorbed from the original radiation remaining constant. When there is no coincidence between the constituents in the two cells, the detector's output is the same when the EOPM is ON and when it is OFF. However, when there is coincidence the detector's output changes when the EOPM is switched between its two states. The change in the detector's output is related to the quantity of the constituents in the sample cell.

Abstract: A method and apparatus are provided for indicating the altitude at which an aircraft should fly so the W/d ratio (weight of the aircraft divided by the density of air) more closely approaches the optimum W/d for the aircraft. A passive microwave radiometer on the aircraft is directed at different angles with respect to the horizon, to determine the air temperature and therefore the density of the air, at different altitudes. The weight of the aircraft is known. The altitude of the aircraft is changed to fly the aircraft at an altitude at which is W/d ratio more closely approaches the optimum W/d ratio for that aircraft.

Abstract: A hollow cathode apparatus is described, which can be rapidly and reliably started. An ignitor (30) positioned upstream from the hollow cathode (20), generates a puff of plasma (36) that flows with the primary gas to be ionized through the cathode. The plasma puff creates a high voltage breakdown between the downstream end (24) of the cathode and a keeper electrode (32), to heat the cathode to an electron-emitting temperature.

Abstract: A guidance sensor for a wire-following vehicle which is phase sensitive, includes an array of coils (C1-C16) positioned to sense the vertical component of a magnetic field (17) produced by the AC current through the guidance wire 15. The outputs of the coils are fed to associated flip flops (FF1-FF16). Flip flops associated with coils, through which flux passes in one direction, e.g. up, are driven to one state, e.g. true, and flip flops associated with coils through which flux passes in the opposite direction, e.g. down, are driven to a false state. The control signal to guide the vehicle to be over the wire is a function of the number of flip flops in the true state. Circuitry (45, 46) is included to prevent flip flops from assuming a wrong state due to noise.

Abstract: A solar pond (16) adapted for efficiently trapping and storing radiant solar energy without the use of a salt concentration gradient in the pond is disclosed. A body of water (20) which may be fresh, saline, relatively clear or turbid, is substantially covered by a plurality of floating honeycomb panels (18). The honeycomb panels (18) are made of a material such as glass which is pervious to short wave solar radiation but impervious to infrared radiation. Each honeycomb panel (18) includes a multitude of honeycomb cells (42) having a height-to-width aspect ratio of at least approximately 14 to 1. The honeycomb panels (18) are divided into the elongated honeycomb cells (42) by a multitude of intermediate plates (44) disposed between a bottom plate (34) and top plate (36) of the panel (18). The solar pond (16) of the invention is well suited for providing hot water of approximately 85.degree.-90.degree. C. temperature for direct heating applications, and for electrical power generation.

Abstract: A synthetic aperture radar system (SAR) having a range correlator (10) is provided with a hybrid azimuth correlator (12) for correlation utilizing a block-pipelined Fast Fourier Transform (12a) having a predetermined FFT transform size with delay elements (Z) for so delaying SAR range correlated data as to embed in the Fourier transform operation a corner-turning function as the range correlated SAR data is converted from the time domain to a frequency domain. A transversal filter (12b) connected to receive the SAR data in the frequency domain, and from a generator (14b) a range migration compensation function, D, to a programmable shift register (30) for accurate range migration compensation; weights, W.sub.i, to multipliers (35-38) for interpolation, and an azimuth reference function, .phi..sub.j, in the frequency domain to a multiplier 42 for correlation of the SAR data.

Abstract: An arrangement for calibrating a photon detector particularly applicable for the ultra-violet (UV) and vacuum ultra-violet (VUV) regions is based on electron photon coincidence utilizing crossed electron beam-atom beam collisions. Atoms are excited by electrons which lose a known amount of energy and scatter with a known remaining energy, while the excited atoms emit photons of known radiation. Electrons of the known remaining energy scattered in a particular direction are separated from other electrons and are sensed and counted. Photons emitted in a direction related to the particular direction of scattered electrons are detected by a detector to serve as a standard. Each of the electrons is used to initiate the measurement of a time interval which terminal with the arrival of a photon exciting the photon detector.

Abstract: A system is described for acoustically levitating an object (12, FIG. 1) within a portion of a chamber (14) that is heated to a high temperature, while a driver (22) at the opposite end of the chamber is maintained at a relatively low temperature. The cold end of the chamber is constructed so it can be telescoped to vary the length (L.sub.1) of the cold end portion and therefore of the entire chamber, so that the chamber remains resonant to a normal mode frequency, and so that the pressure at the hot end of the chamber is maximized. The precise length of the chamber at any given time, is maintained at an optimum resonant length by a feedback loop. The feedback loop includes an acoustic pressure sensor (42) at the hot end of the chamber, which delivers its output to a control circuit (44), which controls a motor (36) that varies the length (L) of the chamber to a level where the sensed acoustic pressure is a maximum.

Abstract: A method is described for thinning an epitaxial layer (16) of a wafer (12) that is to be used in producing diodes having a specified breakdown voltage and which also facilitates the thinning process. Current is passed through the epitaxial layer, by connecting a current source between the substrate (14) of the wafer and an electrolyte (20) in which the wafer is immersed. When the wafer is initially immersed, the voltage across the wafer initially drops and then rises at a steep rate (from 56 to 58). When light is applied to the wafer the voltage drops (from 60 to 62), and when the light is interrupted the voltage rises again (from 66 to 68). These changes in voltage, each indicate the breakdown voltage of a Schottky diode that could be prepared from the wafer at that time.

Abstract: The columnar electron content of the ionosphere between a spacecraft (10) and a receiver (12, 14) is measured in realtime by cross correlating two coherently modulated signals transmitted at different frequencies (L.sub.1, L.sub.2) from the spacecraft to the receiver using a cross correlator (16). The time difference of arrival of the modulated signals is proportional to electron content of the ionosphere. A variable delay (21) is adjusted relative to a fixed delay (20) in the respective channels (L.sub.1, L.sub.2) to produce a maximum at the cross correlator output. The difference in delay required to produce this maximum is a measure of the columnar electron content of the ionosphere. A plurality of monitoring stations (31, 32, 33) and spacecrafts (GPS satellites 34, 35, 36) are employed to locate any terrestrial event that produces an ionospheric disturbance.

Abstract: Electrodes (18) are positioned in intimate contact with an outer surface of a thin electrically-insulating protecting layer (16) of architectural reflective glass (20). Application of a voltage of sufficient magnitude substantially destroys the insulating layer (16) located beneath the electrodes (18). A subsequent application of voltage results in a passage of current through the underlying thin, light-reflective metal or metal oxide layer (14) and in concomitant output of heat.

Abstract: A centrifugal compressor (50) includes at least one pair of cylinders (56 and 58) arranged in coaxial alignment and supported for angular displacement about a common axis of rotation (84) normally bisecting a common longitudinal axis of symmetry for the cylinders. The cylinders are characterized by ported closures (64 and 66) located at the mutually remote ends thereof through which the cylinders are charged and discharged, and a pair of piston heads (68 and 70) seated within the cylinders and supported for floating displacement in compressive strokes in response to unidirectional angular displacement imparted to the cylinders.

Abstract: A system is described for use with a solar concentrator such as a parabolic dish type that concentrates solar radiation onto a small opening (18) of a receiver, for protecting the receiver in certain circumstances, including tracking failure wherein the concentrated solar radiation would fall on the face plate (26) surrounding the receiver opening and burn it, or in the event of lack of coolant circulation which could cause burning of the receiver cavity walls (22). The protective system includes a shutter mechanism (30) stored in an open configuration beside the receiver opening and operable in case of failure to close shutters (34) over the opening, while also moving the mechanism away from the opening and closer to the dish concentrator so that only less concentrated solar radiation must be blocked by the shutter mechanism.

Abstract: A synthetic aperture radar (SAR) target simulator for simulating the radar return, or echo, from a target seen by a SAR antenna mounted on a platform moving with respect to the target includes a first-in first-out memory (26) which has digital information clocked in at a rate related to the frequency of a transmitted radar signal and digital information clocked out with a fixed delay defining range between the SAR and the simulated target, and at a rate related to the frequency of the return signal. An rf input signal having a frequency similar to that utilized by a synthetic aperture array radar is mixed with a local oscillator (16) signal to provide a first baseband signal having a frequency considerably lower than that of the rf input signal. The first baseband signal is converted to a plurality of digital words which are clocked into the memory (26) at a rate related to the frequency of the local oscillator (16).

Abstract: Yields of soluble organic extract are increased up to about 50% by the supercritical extraction of particulate coal at a temperature below the polymerization temperature for coal extract fragments (450.degree. C.) and a pressure from 500 psig to 5,000 psig by the conjoint use of a solvent mixture containing a low volatility, high critical temperature coal dissolution catalyst such as phenanthrene and a high volatility, low critical temperature solvent such as toluene.

Abstract: An integrating IR detector array for imaging is provided in a hybrid circuit with InSb mesa diodes (1, 2 . . . 128) in a linear array, a single J-FET preamplifier (30) for readout, and a silicon integrated circuit multiplexer (34). A reset switch (32) is also provided to reset (charge) all of the diodes to a predetermined level at the end of each line scan. Thin film conductors in a fan-out pattern deposited on an Al.sub.2 O.sub.3 substrate (42) connect the diodes to the multiplexer, and thick film conductors also connect the reset switch and preamplifier to the multiplexer. Two-phase clock pulses (.phi..sub.1 and .phi..sub.2) are applied with a logic return signal to the multiplexer through a triax comprised of three thin film conductors deposited one over the other with silicate glass insulation between layers. A lens (14) focuses a scanned image onto the diode array for horizontal read out one line at a time while a scanning mirror (22) provides vertical scan.

Abstract: A brushless DC tachometer is disclosed that includes a high strength toroidal permanent magnet (25) for providing a uniform magnetic field in an air gap, an annular pole piece (21) opposite the magnet, and a pickup coil (19) wound around the pole piece (21) and rotating about the axis of the pole piece. The pickup coil is rotated by an input shaft (15) to which the coil (19) is coupled with a friction clip. The output of the coil (19) is conducted to circuitry (31) by a twisted wire pair (29). The input shaft (15) also activates a position transducing potentiometer (13).

Abstract: An ion mass spectrometer is described which detects and indicates the characteristics of ions received over a wide angle, and which indicates the mass to charge ratio, the energy, and the direction of each detected ion. The spectrometer includes a magnetic analyzer (18) having a sector magnet (24) that passes ions received over a wide angle, and an electrostatic analyzer (30) positioned to receive ions passing through the magnetic analyzer. The electrostatic analyzer includes a two dimensional ion sensor (32) at one wall of the analyzer chamber, that senses not only the lengthwise position of the detected ion to indicate its mass to charge ratio, but that also detects the ion position along the width of the chamber to indicate the direction in which the ion was travelling.