Abstract: A process for plating aluminum alloy substrates (10), such as 390 aluminum alloy pistons (12), with iron comprises (a) plating on the aluminum substrate a layer of zincate from a zincate bath; (b) plating on the zincate layer a layer (14) of nickel from an electroless nickel bath; (c) plating on the nickel layer a layer (16) of iron from an iron ammonium sulfate bath; and (d) plating on the iron layer a layer (18) of tin from an alkaline tin bath. During the electroless plating, the zincate layer, which protects the underlying aluminum against oxidation, is sacrificed. All of these baths are environmentally much safer than cyanide and chloride. They are also cost effective and can be utilized in a totally closed loop plating system.

Abstract: A method and system for using two-way ranging navigation to accurately determine the range along the path from source to destination by measuring the time delay during round-trip communication via satellite. The two-way ranging navigation measurements are used as calibration references, thereby improving the positioning accuracy of GPS. The system includes GPS and a two-way ranging navigation system for taking position measurements of a target. A correction factor is determined as a function of the measurements and the GPS position is adjusted by the correction factor. The method for calibrating GPS using two-way ranging navigation involves taking a two-way ranging navigation measurement and a GPS measurement of a target, determining a correction factor as a function of the measurements, and correcting the GPS position by taking a second GPS measurement and adjusting it by the correction factor.

Abstract: The dominant physical parameter that affects the internal stress of electroplated metals on substrates have been identified and their effects have been systematically studied. Thin electroplated metals have very high internal stresses, even though the substrate displacements are small. Increasing the electroplated metal's thickness greatly reduces the magnitude of the stress, which can be either tensile or compressive depending on the plating conditions, but it may not necessarily reduce the displacement of the substrate. Based on the research done in connection to this application, the relationship between the plating temperatures and the current density needed to obtain near-zero-stress state for electroplated nickel on silicon substrate can be deduced.

Abstract: A scalable switch matrix and demodulator bank architecture for a satellite payload processor wherein the demodulators are connected to the output ports of the switches as the data load on the uplink beams varies. The switch matrix includes a first switch layer for receiving the uplink transmission beams and a plurality of demodulators connected to the output parts of the first switch layer. The number of demodulators is limited by the number of active uplink sub-bands which is generally less than the number of sub-bands per beam times the number of transmission beams. Thus, only a relatively few number of demodulators are distributed among the uplink transmission beams as required. This results in a readily scalable architecture having higher demodulation utilization rates than dedicated demodulation architectures.

Abstract: A method for producing topographic projections, especially useful for producing many small projections of less than about 100 &mgr;m in diameter and in height. This method is useful for making contact pads of membrane probes used to test integrated circuits and spacers of liquid crystal light valves.

Abstract: A method and system for determining a position of an orbiting transceiver in a communications network includes at least a first and second transceiver at a first and second known location, respectively, on Earth. The first and second transceivers are adapted to transmit and receive communications signals to and from the orbiting transceiver. A processor coupled to one of the first and second transceivers determines a first and second range measurement between each of the first and second transceivers and the orbiting transceiver, respectively, as well as corresponding first and second range rates representative of a time rate of change of the first and second range measurements.

Abstract: A method of making material layers for semiconductor devices by metal organic vapor phase epitaxy includes the steps of wafer preparation, oxide desorption, growth and post growth with an accompanying reduction of a residual sheet charge at the substrate-epitaxy interface. During the oxide desorption step, a substrate is heated to a temperature minimlly necessary to remove oxide from the substrate. In accordance with such method, material layers for a low noise high electron mobility transistor (HEMT) can be grown without a bulk, buffer layer immediately adjacent the substrate. Rather, a super lattice structure is immediately adjacent to and between the substrate and a channel layer.

Abstract: Methods are provided for determining and enhancing the service efficiency of mobile communications. To assess communication efficiency in each communication region of interest, a signal-fading record is generated for that region and this record is then analyzed to find availability and energy cost for each of a plurality of power-control parameter sets. The results facilitate the selection of power-control parameter sets that enhance system efficiency in each communication region.

Abstract: Disclosed is a computerized data display system including a computer operating in accord with a window display management system for the display and control of a plurality of data windows on a display screen of a display device. The data windows are displayed on the display screen in a spatial relation corresponding to the field of view seen from a preselected viewing location selected by means of a control signal provided as an input to the computer. A head coupled image display device, coupled to the display screen of the display device, is adapted to display the data windows appearing on the display screen of the display device separately to each eye of a user to create a binocular, stereoscopic virtual screen image to the user that has a virtual screen size independent of the size of the display screen of the display device.

Abstract: An antenna circuit, a method of manufacturing, and a method of operating the same are provided. An antenna member, a first dielectric layer, a top ground plane, a radiating slot ring through the top ground plane, a second dielectric layer, a stripline feed member, a third dielectric layer, and a bottom ground plane are all laminated together within a specified arrangement to form an efficient multi-band micro-strip antenna circuit. A micromachined electromagnetic switch is utilized to alter the length of the antenna member, thereby producing resonant frequencies which correlate with those radiated by the ring slot.

Abstract: An antenna configuration suitable for LEO/MEO satellites includes a plurality of lenses whereby each lens has a plurality of feed horns positioned with respect to the lens. The lens has a first surface and a second surface. The plurality of feed horns is disposed upon a curved surface. Each of the plurality of feed horns generates a beam that has a phase distribution. The phase distributions have a predetermined phase relationship with the first surface and preferably the second surface. This allows the lens to transmit and receive a signal with desired phase distribution across a cross-section of the beam. The beams from the plurality of lenses are inter-leaved on the ground to form a contiguous coverage with multiple overlapping spot-beams.

Abstract: A spacecraft has internal structure which generates heat, and a radiator element in thermal communication with the spacecraft internal structure. The radiator element has a radiating surface and a coating on the radiating surface including a white thermal control paint. The paint has an initial solar absorptance of not greater than 0.16 and an initial infrared emittance of not less than about 0.80. The standard end-of-life projected solar absorptance is not more than about 0.33 for a paint with an inorganic binder, and the standard end-of-life projected solar absorptance is not more than about 0.6 for a paint with an organic binder.

Abstract: A spacecraft (10) having a main body portion (12) comprising a payload module (14), a bus module (16) and an antenna potion (17), a first solar wing (24) having a first side (30) and a second side (32), a second solar wing (26) having a first side (36) and a second side (38), a first battery pack (50) secured to the first solar wing and a second battery pack (52) secured to the second solar wing.

Abstract: A payload design for a multi-spot-beam satellite communication system includes a plurality of uplink spot beam receivers and downlink spot beam transmitters, and a broadcast transmitting subsystem capable of transmitting a broadcast beam to an entire system geographical service area. An input filter-switch-matrix (IFSM) controllably selects input IF signal bands for routing to an on-board digital signal processor-router (DSPR). The DSPR subsequently routes all received point-to-point and broadcast data packets to the appropriate downlink spot or broadcast transmitting subsystems for transmission thereof. The broadcast downlink allows broadcast transmissions to occur at the highest efficiency possible, while also allowing for flexible provision of surge capacity for point-to-point transmissions on previously exhausted spot beams by selective use of the broadcast beam for such point-to-point transmissions.

Abstract: A method for efficiently storing quantities used by the Fast Multipole Method (FMM) to perform field calculations is disclosed. This method takes advantage of the level structure used by the FMM. The disclosed method selects a particular level and, for each group in that level, calculates interactions with all far groups. The disclosed method does not repeat calculations for interaction of a similar distance for the same level. Rather, it references calculations previously made for the similar interaction, thereby eliminating the calculation and storage of information that is the same as information previously calculated and stored.

Abstract: A system and method for rapidly obtaining information about the suitability of terrain to meet concealment or visibility objectives, such as might be needed for military planning or for determining placement of relay antennas in a cellular communication system, is disclosed. The disclosed system precomputes heuristic visibility fields for a geographic area, then uses the precomputed heuristic visibility fields to rapidly determine points on a map that will provide the desired characteristics of exposure or concealment in response to a query.

Abstract: Linearly-polarized, single-frequency fiber lasers are realized with optical fibers that have first and second refractive indices in a first fiber grating and third and fourth refractive indices in a second fiber grating. The first and third refractive indices are arranged along a first transverse fiber axis and the second and fourth refractive indices are arranged along a second transverse fiber axis. The grating periods and the first and third refractive indices are selected to generate spectrally-aligned signal reflectances along the first transverse axis and the grating periods and the second and fourth refractive indices are selected to generate spectrally-spaced signal reflectances along the second transverse axis. Thus, a fiber resonator is formed only along the first transverse axis and the fiber laser's output signal is linearly polarized.

Abstract: A method for creating nonuniform grating strengths within fiber optic includes exposing photosensitive fiber optic material to an optical source for various periods of time through a mask. As the fiber optic material is exposed, the grating strength of the fiber changes. By linearly exposing the fiber optic material to different durations of optical energy, nonuniform grating strengths are created within the fiber, thereby creating a fiber optic section having asymmetric grating strengths.

Abstract: An attitude control system for a spacecraft which includes a bearing power and transfer assembly. The bearing power and transfer assembly is disposed between a first body and a second body. The first body and the second body are counter-rotated with respect to each other by the bearing and power transfer assembly such that the overall spacecraft momentum about the spin axis of the bearing and power transfer assembly is nominally zero.

Abstract: Spacecraft cost, volume and weight are reduced with gyroscope calibration methods that can be effected with structures (e.g., a single-axis Sun sensor and a wheel system) which are typically carried by spacecraft for other purposes. In a method embodiment, these methods include an initial step 1) of calibrating a selected gyroscope and subsequent steps for each uncalibrated gyroscope of: 2) slewing the spacecraft by a slew angle and controlling attitude with the uncalibrated gyroscope for a selected time period to thereby couple its drift into the inertial axis of a calibrated gyroscope, 3) backslewing the spacecraft to return the calibrated gyroscope to its inertial axis, and 4) measuring an error angle generated by the uncalibrated gyroscope during the selected time period (e.g., with a Sun sensor or with the calibrated gyroscope).