Abstract: The disclosed system uses a binary tree which is embedded in a De Bruijn graph to sort the survivor paths based on their path metrics. The system includes a sorting algorithm which is implemented in a pipelined fashion. The same communication structure underlining the De Bruijn graph is used, so that no additional communication overhead is required for sorting. The system implementation is parallel resulting in a high throughput.

Abstract: The use of a liquid nitrogen (LN.sub.2) bath to produce thermal stress between an aluminum heat sink and a silicon circuit board by deep cooling, makes it possible to separate each from the other product undamaged. This allows repair or replacement of the silicon substrate in a very short time with very little turn around time.

Abstract: A method for economically producing low sidelobe levels in the far field pattern of an array antenna is disclosed. The current fed to the subarrays is identically tapered to the elements of each subarray. Both the subarray current taper and the element current tapers are optimized to yield the lowest possible sidelobe levels.

Abstract: The magnetoelectric coefficient in iron-based alloys has a stress value of about 0.6 of that of the elastic limit. A reversal in sign is caused by structural phase slip which is the basis for the onset of metal fatigue. Based on this phenomenon, a method is provided for determining the onset of metal fatigue. The method includes applying a periodic mechanical stimulus at a given frequency to a test structure, and using a magnetometer, sensing the magnetic field of said structural element during the application of stimulus, and then determining whether or not there is a 180 degree difference between the phase of the stimulus and that of the magnetic response for various regions of the test structure.

Abstract: The disclosed method is for radiation testing of a nanostructure photonic device under test (DUT). The method comprises the application of a beam of optical energy to the DUT, and then establishing a computer data base for the performance of the device under test during the application of the beam. Thereafter, a tightly focused, steerable radiation beam is generated and focused on to a selected nano sized area of the DUT. A second data base is established for the performance of the DUT resulting from the application of the radiation beam, and the data of the first data base are compared with the data of said second data base to determine the affects of applying the radiation beam to the DUT, or to alter the device physical properties such as its refractive indicies, absorption, preferred polarization, and electrooptic characteristics, including electrooptic coefficients, photoelastic constants, operational (fundamental) wavelength and coupling coefficients.

Abstract: A method is disclosed for determining bulk modulus of a liquid based on a pressure-volume-temperature relationship at constant volume corrected for changes in system volume due to elevated pressure and temperature. The apparatus used to determine bulk modulus comprises a pressure vessel in which the liquid to be tested is introduced, and from which all gases are removed. The vessel is placed in a constant temperature oven and the pressure is recorded. The method for determining bulk modulus and density requires calibration of the vessel volume changs due to pressure and temperature.

Abstract: A method is disclosed for establishing an optical link between two lasers via an optical fiber by directing the output from one laser through an optical fiber and into a second laser and vice vera. Before insertion into the lasers, the output from the respective fibers is phase conjugated in a double phase conjugate mirror. Thus, the disclosed method and apparatus provide a combination of fiber optics, used to transport the light from the lasers, and optical phase conjugation, used to compensate for fiber-induced distortions.

Abstract: An optical device which uses a heterojunction field effect detector (HFED) having wavelength selectivity through the use of ion-implantation, and a wavelength selective grating. The device incorporates a Grinsch layer structure with a single GaAs quantum well. The optical power from the lens couples into a guided mode. The absorbing region is the quantum well itself. In the operation of the HFED, a positive bias is applied to the gate, and the depleted GaAs quantum well below the gate absorbs the photons, generating electron-hole pairs. The photocarriers are separated by the electric field before recombination can occur. The photocurrent is then produced in the external circuit by appropriately biasing the device. For collecting the electrons, a positive bias is applied to both the source and drain contacts, which act as dual drain contacts. The holes are removed via the collector which is maintained at ground. To maximize the responsivity (i.e.

Abstract: The disclosure provides a method for use in a robotic system for identifying fasteners used in aircraft and other applications. The fasteners include rivets (with no slots), bolts (with two slots) and screws with one or two slots. The method accepts as input a family of related signals which are known to contain symmetry. By computing the mean variance of the zero-meaned cross-correlation signals, the method automatically selects those signals which contain pertinent information while disregarding those signals which do not. The accepted signals are then used to create a composite reference signal which can be used to determine the particular fastener type.

Abstract: A method for two dimensional imaging of a two or three dimensional target is disclosed. As shown, a radar transmitter transmits a beam on a beam axis originating at a position spaced from the target and a radar receiver receives return signals from the target. The stationary radar observes the precessing target whose normal to the two dimensional target plane (or whose axis through a three dimensional target) intersects the transmitted beam axis at a point, and forms a cone half angle with the beam axis. With the normal (or target axis) moving along a conical surface while precessing 2 Pi around the beam axis, signal returns from the target are processed to develop a two dimensional image of the target. The process is repeated at other cone half angles and a composite, reduced-sidelobe image generated by vectorial superposition of images at multiple cone half angles.

Abstract: An optical switch comprises a heterojunction transistor having a source electrode, a gate, a mesa, and three self-aligned waveguides, the mesa being ion implanted and having a single quantum well under the gate electrode, the single quantum well being comprises of undoped, narrow bandgap material bound on both sides by regions p-doped, wide bandgap material, both of said p-doped regions have symmetrically graded bandgaps, being most narrow next to the quantum well and increasing out to a wide and constant value away from the quantum well. A highly n-doped and totally depleted charge sheet is placed in a wide bandgap material, very near the gate side of the quantum well heterojunction. The charge sheet serves to induce a voltage controllable inversion channel within the quantum well.

Abstract: A device under test is placed in a metallic reverberation chamber and test are run for various characteristics. An antenna positioned in the chamber radiates microwave energy into the chamber. There is disclosed a method of frequency stirring which uses band limited White Gaussian noise (WGN) up-converted by performing double sideband, suppressed carrier modulation with a microwave signal from a synthesized sweeper. The output is then amplified with a TWT amplifier to meet the higher power level requirements. The synthesized sweeper is used to generate the monochromatic signal which determines the center frequency of the output while the WGN source and low pass filters provide the frequency agility.

Abstract: A system for determining the angles of elevation and azimuth of a source of collimated energy comprises a detector consisting of an annular entrance opening in an opaque structure, and an annular segmented optical detector spaced from and axisymmetric with the opening. Laser, or other collimated light energy passing through the opening illuminates all, or particular portions of the segmented detector depending on the direction and angle of incidence of the energy, thereby providing all of the information necessary to determine the elevation and azimuth of the source of the energy.

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: 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.

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: This disclosure describes a single shell, double dome combustor design configuration with the intermediate dividing wall between the two annuli removed, thereby reducing weight and cost, and improving durability. An annular daisy type mixer is positioned between the domes to improve the mixing of air and combustor gases prior to the exiting of the gases from the combustor to the turbine vanes. The daisy mixer positioned downstream of the domes to provides effective, low pressure loss mixing at a a controlled axial rate, by creating effective cross-flow barriers to avoid uncontrolled fuel/air ratio transfer between the inner and outer annuli, and thereby allows a concentric and controlled axial air admission in conjunction with the individual swirlers.

Abstract: The disclosed system comprises: 1) a transmissive frequency shifter based on reflection from rotating flat surfaces and from stationary involute surfaces; 2) system to compensate for effects of rotation rate instabilities and certain imperfections in the frequency shifter's reflection geometry, and a system to multiply the frequency shift obtainable by an integer number n through an n-fold re-use of stationary reflecting surfaces.

Abstract: The disclosure describes a method of measuring stationary CW radar targets in the presence of sizable clutter and leakage signals, and to eliminate the clutter and leakage by taking a first measurement when the target is in a first position, and taking a second measurement when the target is translated to a second position such that the target signal pathlength changes by 1/2 wavelength from the first position, and then subtracting the first and second measurement to eliminate the unwanted clutter and leakage.

Abstract: A remote microwave plasma generator comprises the combination of two parts, a tunable microwave applicator, and a double wall, water cooled quartz/sapphire tube. The tunable waveguide applicator is a nonconducting adjustable waveguide short with a quartz/sapphire tube inserted through it. The adjustable end is one quarter of a guide wavelength from the center line of the tube, and the other side is 0.1 inches less in distance, thus permitting the applicator to be used with a triple stub tuner for optimum coupling.