Abstract: A technique is described for use in determining the reliability of microscopic conductors deposited on an uneven surface of an integrated circuit device. A wafer containing integrated circuit chips is formed with a test area having regions of different heights. At the time the conductors are formed on the chip areas of the wafer, an elongated serpentine assay conductor is deposited on the test area so the assay conductor extends over multiple steps between regions of different heights. Also, a first test conductor is deposited in the test area upon a uniform region of first height, and a second test conductor is deposited in the test area upon a uniform region of second height. The occurrence of high resistances at the steps between regions of different height is indicated by deriving the "measured length" of the serpentine conductor using the resistance measured between the ends of the serpentine conductor, and comparing that to the design length of the serpentine conductor.

Abstract: In a system having a driver, a motor, and a mechanical plant, a multiloop feedback control apparatus for controlling the movement and/or positioning of a mechanical plant, the control apparatus having a first local bridge feedback loop for feeding back a signal representative of a selected ratio of voltage and current at the output of the driver, and a second bridge feedback loop for feeding back a signal representative of a selected ratio of force and velocity at the output of the motor. The control apparatus may further include an outer loop for feeding back a signal representing the angular velocity and/or position of the mechanical plant.

Abstract: A steam reformer is disclosed having an annular steam reforming catalyst bed formed by concentric cylinders and having a catalytic combustor located at the center of the innermost cylinder. Fuel is fed into the interior of the catalytic combustor and air is directed at the top of the combustor, creating a catalytic reaction which provides sufficient heat so as to maintain the catalytic reaction in the steam reforming catalyst bed. Alternatively, air is fed into the interior of the catalytic combustor and a fuel mixture is directed at the top. The catalytic combustor provides enhanced radiant and convective heat transfer to the reformer catalyst bed.

Abstract: An image difference detection system is described, of the type wherein two created image representations such as transparencies representing the images to be compared lie coplanar, while light passes through the two transparencies and is formed into coincident images at the image plane for comparison. The two transparencies are formed by portions of a polarization rotation spacial light modulator display such as a multi-pixel liquid crystal display or a magneto optical rotation type. In a system where light passing through the two transparencies is polarized in transverse directions to enable the use of a Wollaston prism to bring the images into coincidence, a liquid crystal display can be used which is devoid of polarizing sheets that would interfere with transverse polarizing of the light passing through the two transparencies.

Abstract: A concatenated coding system consisting of a (255,223) Reed-Solomon outer code and a convolutional inner code is provided with either a block of preinterleaved frames or an interleaver of frames in a block of data symbols to be coded in the outer decoder. By interleaving, errors are constrained to occur in only one symbol in a frame, which can be corrected by the Reed-Solomon outer decoder. After transmission and inner decoding, the data symbols are deinterleaved for outer decoding. Instead of preinterleaving at the source, or interleaving before inner encoding, the frames of data symbols may be interleaved at the receiver after inner decoding and then combined with the inner decoded check symbols for outer decoding. The outer encoder is a bit-serial Reed-Solomon encoder with programmable interleaving, and the inner decoder is a Viterbi decoder.

Abstract: A method of effecting modifications at the surfaces of materials using low energy ion beams of known quantum state, purity, flux and energy. The ion beam is obtained by bombarding ion-generating molecules with electrons which are also at low energy. The electrons used to bombard the ion generating molecules are separated from the ions thus obtained and the ion beam is directed at the material surface to be modified. Depending on the type of ion generating molecules used, different ions can be obtained for different types of surface modifications such as oxidation and diamond film formation.

Abstract: A nozzle assembly in a multi-element spherical shell generation system includes first and second side-by-side spaced apart nozzles and a web portion extending between and connecting the nozzles. The first nozzle has an inner orifice adapted to discharge a first filler material and an outer annular orifice separated from and defined in concentric relation about the inner orifice and adapted to discharge a first shell material. The second nozzle has an inner orifice adapted to discharge a second filler material and an outer annular orifice separated from and defined in concentric relation about the inner orifice and adapted to discharge a second shell material.

Abstract: Spatial light modulation (22) in a III-V single crystal (12), e.g., gallium arsenide, is achieved using the photorefractive effect. Polarization rotation created by beam coupling is utilized in one embodiment. In particular, information (16)on a control beam (14) incident on the crystal is transferred to an input beam (10), also incident on the crystal. An output beam (18) modulated in intensity is obtained by passing the polarization-modulated input beam through a polarizer (20).

Abstract: A system is described for maintaining a sample material in a molten state and away from the walls of a container in a microgravity environment, as in a space vehicle. A plurality of sources of electromagnetic radiation, such as an infrared wavelength, are spaced about the object, with the total net electromagnetic radiation applied to the object being sufficient to maintain it in a molten state, and with the vector sum of the applied radiation being in a direction to maintain the sample close to a predetermined location away from the walls of a container surrounding the sample. For a processing system in a space vehicle that orbits the Earth, the net radiation vector is opposite the velocity of the orbiting vehicle.

Abstract: A dynamic logic circuit (AND or OR) utilizes one depletion-mode metal-semiconductor FET for precharging an internal node A, and a plurality of the same type of FETs in series, or a FET in parallel with one or more of the series connected FETs for implementing the logic function. A pair of FETs are connected to provide an output inverter with two series diodes for level shift. A coupling capacitor may be employed with a further FET to provide level shifting required between the inverter and the logic circuit output terminal. These circuits may be cascaded to form a domino chain.

Abstract: A circuit for generating a sequence of pseudo random numbers, {A.sub.k }. There is an exponentiator (30') in GF(2.sup.m) for the normal basis representation of elements in a finite field GF(2.sup.m) each represented by m binary digits and having two inputs and an output from which the sequence {A.sub.k } of pseudo random numbers is taken. One of the two inputs is connected to receive the outputs {E.sub.k } of maximal length shift register of n stages. There is a switch (32) having a pair of inputs and an output. The switch (32) output is connected to the other of the two inputs of the exponentiator (30'). One of the switch (32) inputs is connected for initially receiving a primitive element A.sub.0 in GF(2.sup.m). Finally, there is a delay circuit (34) having an input and an output.

Abstract: An imaging device that automatically rotates upon descent through an atmosphere provides an onboard image detector a sweeping panoramic scan as it descends. No moving parts or propulsion system are required. The location, angle and pitch of the winged structure, together with its inertia properties, passively induces rotation. The angled location of the image detector takes advantage of the resulting rotation. Data generated by the image detector may be transmitted to a remote receiver or, alternatively, stored for subsequent recovery.

Abstract: A surface-tension liquid pumping system is provided by one or more arrays of converging solid monofilament fibers or metal wires (strands) spaced apart at an input end to gather liquid, and gathered close together at the opposite end where menisci forms between wetted strands to force liquid in the direction of convergence of the strands. The liquid pumping system is independent of gravity. It is illustrated as being used in a heat pump having a heating box to vaporize liquid and a condensing chamber. Condensed liquid is returned by the pumping system to the heating box where it is again vaporized. A vapor tube carries the vapor to the condensing chamber. In that way, a closed system pumps heat from the heating box to the evaporating chamber and from there radiated to the atmosphere.

Abstract: A lower stage chemisorption refrigeration system physically and functionally coupled to an upper stage physical adsorption refrigeration system. Waste heat generated by the lower stage cycle is regenerated to fuel the upper stage cycle thereby greatly improving the energy efficiency of a two-stage sorption refrigerator. The two stages are joined by disposing a first pressurization chamber providing a high pressure flow of a first refrigerant for the lower stage refrigeration cycle within a second pressurization chamber providing a high pressure flow of a second refrigerant for the upper stage refrigeration cycle. The first pressurization chamber is separated from the second pressurization chamber by a gas-gap thermal switch which at times is filled with a thermoconductive fluid to allow conduction of heat from the first pressurization chamber to the second pressurization chamber.

Abstract: A fault-tolerant multi-processor computer system of the hypercube type comprising a hierarchy of computers of like kind which can be functionally substituted for one another as necessary. Communication between the working nodes is via one communications network while communications between the working nodes and watch dog nodes and load balancing nodes higher in the structure is via another communications network separate from the first.

Abstract: A method and apparatus are described which facilitate the growing of silicon ribbon. A container for molten silicon has a pair of passages in its bottom through which filaments extend to a level above the molten silicon, so as the filaments are pulled up they drag up molten silicon to form a ribbon. A pair of guides surround the filaments along most of the height of the molten silicon, so that the filament contacts only the upper portion of the melt. This permits a filament to be used which tends to contaminate the melt if it is in long term contact with the melt. This arrangement also enables a higher melt to be used without danger that the molten silicon will run out of any bottom hole.

Abstract: A continuous flow ash lockhopper includes an ash hopper at the outlet of a high temperature, high pressure reactor vessel containing heated high pressure gas, a fluidics control chamber having an input port connected to the ash hopper's output port and an output port connected to the input port of a pressure letdown means, and a control chamber connected to a variable pressure control fluid (gas or steam) supply for regulating the pressure in the control chamber to be equal to or greater than the internal gas pressure of the reactor vessel, whereby the reactor gas is contained while ash is permitted to continuously flow from the ash hopper's output port, impelled by gravity. The fluidics control chamber may be provided with a variable port to inject control fluid at a desired velocity.

Abstract: In a transverse-pumped, solid-state laser, a nonabsorptive cladding surrounds a gain medium. A single transverse mode, namely the TEM.sub.00 mode, is provided. The TEM.sub.00 mode has a cross-sectional diameter greater than a transverse dimension of the gain medium but less than a transverse dimension of the cladding. The required size of the gain medium is minimized while a threshold for laser output is lowered.

Abstract: A small and simple system is provided for cooling or heating a small component by flowing air or other fluid over it, which does not require any macroscopic moving parts. The system includes a transducer and reflector that are spaced apart with the component between them, and with the transducer being operated at a frequency resonant to the spacing between it and the reflector. The resulting standing wave pattern produces acoustic streaming which results in the circulating of air or other fluid in the environment across the component. The system is especially useful in the reduced gravity environment of outer space because of the absence of any buoyancy-induced convection there.

Abstract: A far infrared (FIR) range responsive photodetector. There is a substrate (28) of degenerate germanium. A a plurality of alternating impurity-band (32) and high resistivity (30) layers of germanium are disposed on the substrate (28). The impurity-band layers (32) have a doping concentration therein sufficiently high to include donor bands which can release electrons upon impingement by FIR photons of energy hv greater than an energy gap .epsilon.. The high resistivity layers (30) have a doping concentration therein sufficiently low as to not include conducting donor bands and are depleted of electrons. Metal contacts (36, 38) are provided for applying an electrical field across the substrate (28) and the plurality of layers (30, 32). In the preferred embodiment as shown, the substrate (28) is degenerate n-type (n.sup.++) germanium; the impurity-band layers (32) are n.sup.+ layers of germanium doped to approximately the low 10.sup.16 cm.sup.-3 range; and, the high resistivity layers (30) are n.sup.