Abstract: A method for brazing together two parts at least one of which comprises a titanium aluminide material is described wherein a metallic layer of foil or powder is inserted between the parts in laminar contact with respective confronting surfaces thereof to be joined, the metallic layer comprising a metal which forms with titanium a eutectic composition having a characteristic fusion temperature lower than the fusion temperature of the metal, and the metallic layer and confronting surfaces of the parts are heated to a temperature of about the characteristic fusion temperature of the eutectic composition.

Abstract: A system for digital conferencing over narrowband channels which allows use by multiple simultaneous speakers and which allow for interfacing between vocoders which operate at different bit rates. The system takes advantage of the properties of multi-rate parametric vocoders (which includes the Sinusoidal Transform Coder and the Multi-Band Excitation Vocoder, as well as embedded coders), defined as parametric vocoders for whom the basic model and parameter set remain unchanged over a wide range of bit-rates. The system performs signal summation. To maintain quality for a single speaker while allowing multiple speakers, the system adaptively allocates channel bandwidth based on the number of speakers to be represented. This system also provides digital-to-digital conversion between narrow-band digitizers (vocoders) operating at different bit-rates.

Abstract: A process that enables a distributed compute network to operate with a network operating system software program. The distributed computer network includes a computer server unit which has output ports and a central processing unit that controls the distributed computer network. The distributed computer network also includes a plurality of computer workstations which are electrically connected to the computer server unit. The first step of the process beings by searching the computer server unit to find an unoccupied area of memory. The second step of the process includes loading the network operating system software program onto the unoccupied area of memory of the computer server unit. The third step of the process includes reconfiguring the computer server unit output ports to eliminate memory address problems with the plurality of computer workstations.

Abstract: MODTRAN is a moderate resolution model and computer code used to predict atmospheric transmittance and background radiance in the microwave, infrared, visible and near ultraviolet spectral regions (0 to 50,000 cm.sup.-1 or 0.2 m to infinity). The code maintains complete compatibility with LOWTRAN 7, specifically, MODTRAN retains all of the capabilities of the LOWTRAN 7 model. Both codes contain the same six built-in model atmospheres; spherical refractive geometry, aerosol models, clouds (water and ice), rain attenuation and options to calculate single scattered solar/lunar radiance, solar/lunar irradiance and multiply scattered thermal and solar radiance. The MODTRAN code improves LOWTRAN'S spectral resolution from 20 to 2 cm.sup.-1 full width/half maximum (fwhm) with an option to vary the resolution between 2 and 50 cm.sup.-1 (fwhm). The band model parameters were formulated from the HITRAN line atlas for twelve atmospheric gases: H.sub.2 O, CO.sub.2, O.sub.3, N.sub.2 O, CO, CH.sub.4, O.sub.2, NO, SO.sub.

Abstract: Whenever any laser is interfaced with any type of optics there is always backscatter back into the laser. For diode lasers this backscatter makes it emit chaotic radiation where the frequency spectrum is broad and contains many different frequencies. This means that the laser has limited use as a source of information transfer in fibers. This weakness can be overcome, by driving the laser with an external cavity filled with a Kerr material. The addition of a Kerr material in the external cavity suppresses the chaos, or coherence collapse. Thus the new apparatus of laser plus external cavity filled with a Kerr material increases the stability of the diode laser.

Abstract: In a gas turbine engine having a laybrinth seal between an annular rotor and stator therein, in which the stator is surmounted by a honeycomb structure and the rotor has a knife edge which is mounted to rotate in close annular proximity with said honeycomb structure, an improvement is provided wherein such labyrinth seal has a layer of abradeable coating atop the honeycomb structure for the rotor knife edge to rotate proximate thereto and to rub in, without substantially damaging the knife edge nor the honeycomb structure. In one embodiment the layer of abradeable coating is mounted on a metalic foil which is mounted in turn, atop the honeycomb structure. The abradeable coating thus provided, is more yieldable and less damaging to a rotor knife edge than is the honeycomb structure of the prior art, to better preserve rotor and stator and thus the labryrinth seal.

Abstract: A phased array monopole antenna has a single layer membrane upon which a plurality of antenna units are attached. Each antenna unit has a flexible curved antenna blade which bends over or springs up when the membrane is rolled or unrolled on a drum.

Abstract: A nonsacrifical laser hardened structure and method protects against incident high energy irradiation. A very thin outer face sheet with a reflective outer surface is laminated to a foam core which is further laminated to a support structure. The foam core includes liquid and vapor passages. A supply of liquid working fluid impregnates the foam core. A portion of incident irradiation energy is first reflected from the outer face sheet and substantially all the remaining irradiation energy conducted through the face sheet to be absorbed at the back of the face sheet into heat of vaporization of the liquid working fluid. Additional liquid working fluid is supplied to the back of the face sheet by capillary action through the foam core, and additional liquid working fluid is resupplied to the foam core through the liquid passages. Working fluid vapor is removed through the foam vapor passages.

Abstract: A camera system for simultaneously recording separate near-infrared and visible light images is disclosed having a visible light source for illuminating a given area with visible white light, indicia generating means for directing an image of a wavelength of light longer than wavelengths of light of the visible white light upon the given area, a first electronic camera for recording an image of the visible light but not the longer wavelength of light and a second electronic camera for recording an image of the longer wavelength of light but not the visible light, and a single cold mirror common to the two cameras for directing the two light images to their respective cameras.

Abstract: A method for fabricating a brazed sheet metal panel for use in an engine nozzle structure is described which comprises steps of providing a first sheet metal member having a plurality of spaced dimples formed therein and a second sheet metal member having a plurality of spaced cutouts corresponding in position to the spaced dimples in the first member, providing a mixture of powdered braze material and polymer binder and spraying a layer of the mixture onto a surface of the second member, assembling the first and second members in laminar contact with the cutouts of the second member in registration with the dimples of the first member and the layer of mixture between the members, and then heating the assembly under vacuum to a temperature sufficient to fuze the braze powder and to volatilize the binder.

Abstract: The invention provides a series of ferroelectic smectic liquid crystal compounds, FLC, of wide tilt angle and mixtures formulated from them that are useful for high speed modulation or switching of optical radiation. Such FLC mixtures are useful in total internal reflection, TIR switching devices. In such TIR switches, an applied DC voltage rotates the molecules through about a 90.degree. angle which changes the perceived refractive index at the FLC layer and permits rapid optical switching. For an FLC crystal material to be useful in such a device it must possess a value of molecular tilt angle .theta. of approximately 45.degree., since the dipole molecule rotates through an angle of about 2 .theta. upon application of a DC field to the cell. This requirement for a large molecular tilt angle greatly limits the compounds and mixtures thereof which can be employed in such TIR devices.

Abstract: An intensity sensitive optical switch is described which comprises a nonlinear thin film Kerr material deposited on a conducting surface.

Abstract: A porous light-weight getter which collects particulate and molecular contaminates that is believed a significant improvement over the prior art is provided in which a metal mesh matrix is coated with a low-density porous aerogel. In the prior art bare metal mesh matrices have been employed as getters, which are subject to ablation from high-velocity contaminant particles. In the composite getter of the present invention, the low-density aerogel coating protects the enclosed metal matrix from ablation and also can attract and hold the incoming high-velocity particle. On its part, the metal mesh provides reinforcing support to the aerogel covering and also good thermal conductivity therein so that such covering can be cooled to the low temperatures that attract such contaminants. The invention further provides method for manufacture of the composite getters of the invention.

Abstract: An uncooled turbine outer air is comprised of a combination of monolithic ceramics with high temperature capability and oxidation and creep resistance, and a fiber reinforced ceramic composite with high fracture toughness. In a preferred embodiment of the invention, a fiber reinforced ceramic composite of silicon carbide and aluminum borosilicate is infiltrated by chemically vapor deposited silicon carbide. The infiltration process is continued until the composite develops a monolithic layer of silicon carbide. An additional layer is deposited on the monolithic ceramic to provide additional thermal protection.

Abstract: Method of demultiplexing a composite signal light beam includes the steps of directing the composite signal light beam and a reference light beam at a photorefractive material, modulating the reference beam at a frequency about equal to the modulation frequency of a selected signal beam to be demultiplexed, and recovering the phase conjugate signal produced by interference of the reference beam with the composite signal light beam within the photorefractive material. The method also enables optical phase detection of the selected signal beam with respect to the reference beam.

Abstract: The scalable and stable, cw photolytically excited atomic iodine laser operates at 1.315 nm. An initial power level of 55 watts/liter was obtained via the cw photolysis of an alkyl-iodide gas like C.sub.3 F.sub.7 I. The greatly enhanced laser performance was achieved using a microwave excited, electrodeless Hg plasma lamp excited with a d.c., low ripple cw microwave radiation. Both high flow, air cooling and liquid dimethyl polysiloxane cooling of these high pressure Hg lamps provided long lifetime operation with the latter promoting, stable laser operation. Transverse flow of the above gas for the removal of the quenching by-product I.sub.2 is incorporated into the laser. To insure good laser amplitude stability, both the high power magnetrons and the lamps are liquid cooled. The scalable, prolonged and stable operation of this laser system is possible via use of a closer cycle, condensative/evaporative fuel system coupled to a high flow, internal blower for heavy gases.

Abstract: The controller is microprocessor based, and provides an interface between laboratory entrances and accompanying safety shutters to block the laser beam during a laboratory breach. The shutter controller comprises a microcomputer operating in a two data bus configuration. Communication to external safety devices is accomplished through three output ports and one input port. Interface cards signal the system that an action is to be taken. In operation, the controller performs a set of very specific tasks which form the controller algorithm. When the controller receives an interrupt indicating that the laboratory was breached, the controller directs that all shutters on all lasers are closed. Output ports serve as drivers for safety shutters, interlocks, and indicator lights to convey the status of the safety shutters. An input port accepts input data from an external driver that indicates the actual state of the shutters to determine if a shutter closure failure occurred.

Abstract: A transformer bus coupler, which connects a transceiver to a data bus without impedance discontinuities. The transformer bus coupler maintains the voltage-to-current ratio of signals as they enter and leave the coupler by providing a shunt circuit that attenuates the current of these signals by the same ratio that the series elements of the coupler attenuate the voltage. The result is an avoidance of impedance discontinuities, which would otherwise result in the signal reflections and the loss of signal fidelity experienced by prior art data bus couplers.

Abstract: For the purpose on monitoring the condition in the interior of a closed metallic honeycomb panel, an optical fiber is embedded therein. An optical connector, secured within a groove has one end exposed to a source of external light, while the optical fibers are connected to the other end of the connector. In the example disclosed, the end of the optical fiber within the structure is coated with a sensor material subject to the same condition (corrosion) taking place within the structure. The reflectivity of the coating from a source of light applied through an optical connector is a measure of the condition.

Abstract: A defective focusing coil, impregnated with and held in place with epoxy is removed from its inner lead liner and its outer brass housing by immersing the assembled parts in a bath of liquid nitrogen until the temperature of the assembly is reduced to the temperature of the liquid nitrogen, about -350.degree. F. The assembly is then removed from the bath and a series of sharp blows are then directed to the side of the brass housing to break the bond between the super cooled epoxy and the housing. Axial pressure is then applied to the coil, to remove the coil and liner. The coil is then cut longitudinally into two half cylinders, whereupon the coil is split from the liner, all without injury to either the liner or the housings.