Abstract: A limiting feature in spacecraft such as communication satellites is becoming the amount of surface such as 5, 6 available for dissipating waste heat from the electrical equipment in the satellite. The invention provides a deployable radiator 11 which carries a number of capillary pumped loops consisting of an evaporator, an outward limb and a return limb. The panel 11 is rolled up to coil the elements prior to launch, and unrolled when in orbit. The outward and return lengths of tube act as condenser for the capillary pumped loop, transport the heat over the radiating panel 11 and also provide the spring force for the panel to unroll.

Abstract: Phenylethynyl containing reactive additives were prepared from aromatic diamines containing phenylethynyl groups and various ratios of phthalic anhydride and 4-phenylethynylphthalic anhydride in glacial acetic acid to form the imide in one step or in N-methyl-2-pyrrolidinone to form the amide acid intermediate. The reactive additives were mixed in various amounts (10% to 90%) with oligomers containing either terminal or pendent phenylethynyl groups (or both) to reduce the melt viscosity and thereby enhance processability. Upon thermal cure, the additives react and become chemically incorporated into the matrix and effect an increase in crosslink density relative to that of the host resin. This resultant increase in crosslink density has advantageous consequences on the cured resin properties such as higher glass transition temperature and higher modulus as compared to that of the host resin.

Abstract: A satellite-based antenna system that employs an improved dual function subreflector. An exemplary antenna system comprises a flat plate dual function subreflector and a subreflector positioning mechanism that selectively positions the subreflector at predetermined positions corresponding to two or more operational positions of the satellite. A plurality of feed arrays couple energy to and from the subreflector, and a main reflector generates beams for desired coverage areas. The present invention provides optimum performance from a dual reflector antenna when operating in two or more different satellite positions, with no compromise to the performance for either mode of operation.

Abstract: An automatic, on-board system for orbiting spacecraft that controls and reduces short-term transients caused by roll momentum unloads by manipulating the states of the nutation damper through resetting one of the states in the polynomial transfer function to a value in proportion to the magnitude of the expected roll momentum unload and creating a transient equal and opposite in magnitude to that expected by the roll unload. The compensator will, of its own accord, automatically damp out the resulting transient. Thus the short-term transient is reduced without biasing the spacecraft in roll. No angle bias need be changed or removed.

Abstract: A spacecraft orbit control system and method that provides orbit control of a spacecraft. The system comprises the spacecraft, one or more electric and/or chemical thrusters disposed on the spacecraft, and a control processor having control outputs coupled to the plurality of thrusters. An orbit control algorithm is implemented that determines the current orbit of the spacecraft, determines whether or not to perform stationkeeping, determines desired changes in certain orbit parameters if stationkeeping is to be performed, determines thruster firings that accomplish the desired orbit parameter changes, and fires the thrusters to perform spacecraft stationkeeping and provide spacecraft longitude control. The present invention may be used with any type of orbit determination procedure (such as GPS or ranging, with or without orbit propagation) and any type of stationkeeping algorithm that calculates thruster firings from desired orbit-parameter corrections.

Abstract: An automatic network analyzer that measures continuous wave radio microwave driven transfer characteristics of nonlinear devices and simultaneously calculates and displays corresponding noise driven transfer characteristics and noise power ratio data. This automatic network analyzer employs software or firmware that uses closed-form equations to exactly calculate noise parameters. This is done in real-time as CW measurements are taken.

Abstract: The optical system of this invention is an unique type of imaging spectrometer, i.e. an instrument that can determine the spectra of all points in a two-dimensional scene. The general type of imaging spectrometer under which this invention falls has been termed a computed-tomography imaging spectrometer (CTIS). CTIS's have the ability to perform spectral imaging of scenes containing rapidly moving objects or evolving features, hereafter referred to as transient scenes. This invention, a reflective CTIS with an unique two-dimensional reflective grating, can operate in any wavelength band from the ultraviolet through long-wave infrared. Although this spectrometer is especially useful for rapidly occurring events it is also useful for investigation of some slow moving phenomena as in the life sciences.

Abstract: A method and apparatus for processing a wafer comprising a material selected from an electrical semiconducting material and an electrical insulating material. The wafer has opposed generally planar front and rear sides and a peripheral edge, wherein said wafer is pressed against a pad in the presence of a slurry to reduce its thickness. The thickness of the wafer is controlled by first forming a recess such as a dimple on the rear side of the wafer. A first electrical conducting strip extends from a first electrical connection means to the base surface of the recess to the second electrical connector. The first electrical conducting strip overlies the base surface of the recess. There is also a second electrical conductor with an electrical potential source between the first electrical connector and the second electrical connector to form.

Abstract: A solid-state apparatus for tracking the wavelength of a laser emission has a power splitter that divides the laser emission into at least three equal components. Differing phase shifts are detected and processed to track variations of the laser emission.

Abstract: An optical device having a semi-spherical or hemispherical field-of-view is provided. A conically-shaped piece of optical material has an annular surface satisfying Snell's Law for total internal reflection with respect to light passing through the piece and incident on the annular surface from within the piece.

Abstract: A surface-sizing agent for providing a recording paper contains bacterial cellulose and/or plant-originated fine fibrous cellulose (having an average diameter of 10 &mgr;m or less), and a cationic polymer. The cationic polymer may be at least partially bonded to the bacterial cellulose and/or the plant-originated fine fibrous cellulose. The cationic polymer may be an acrylic polymer, a vinyl polymer or an allyl polymer each comprising a quaternary amino group.

Abstract: A support for a deployable reflector for use on a modular satellite antenna assembly is constructed of an elongated boom supported at both ends by a pair of two axis actuators. The boom is attached at its inboard end to the satellite structure in close proximity to the point of attachment of the associated signal feed assembly to minimize the differential thermal stress throughout the antenna assembly.

Abstract: A mechanically simple dual-frequency (or wide band) quadrifilar helix antenna (1). It includes four helix shaped radiating elements (2-5) where each helix element consists of two or more parallel helices (2a, 2b, 3a, 3b, 4a, 4b, 5a, 5b) of different lengths that are in galvanic contact at, or close to, the feeding point (2c, 3c, 4c, 5c). The four feeding points (2c, 3c, 4c, 5c) of the helix elements (2-5) are located at the bottom of the helix, meaning that the feedings of the helix elements are located at the end (6) of the helix pointing in the direction opposite to the direction of its main radiation.

Abstract: A charge-coupled device with a low-emissivity metal layer located between a sensing layer and a substrate provides reduction in ghost images. In a typical charge-coupled device of a silicon sensing layer, a silicon dioxide insulating layer, with a glass substrate and a metal carrier layer, a near-infrared photon, not absorbed in the first pass, enters the glass substrate, reflects from the metal carrier, thereby returning far from the original pixel in its entry path. The placement of a low-emissivity metal layer between the glass substrate and the sensing layer reflects near infrared photons before they reach the substrate so that they may be absorbed in the silicon nearer the pixel of their points of entry so that the reflected ghost image is coincident with the primary image for a sharper, brighter image.

Abstract: A process for making a cast article from an aluminum alloy includes first casting an article from an alloy having the following composition, in weight percent: Silicon 11.0-14.0 Copper 5.6-8.0 Iron   0-0.8 Magnesium 0.5-1.5 Nickel 0.05-0.9  Manganese   0-1.0 Titanium 0.05-1.2  Zirconium 0.12-1.2  Vanadium 0.05-1.2  Zinc 0.05-0.9  Strontium 0.001-0.1  Aluminum balance In this alloy the ration of silicon:magnesium is 10-25, and the ratio of copper:magnesium is 4-15. After an article is cast from the alloy, the cast article is aged at a temperature within the range of 400° F. to 500° F. for a time period within the range of four to 16 hours. It has been found especially advantageous if the cast article is first exposed to a solutionizing step prior to the aging step.

Abstract: A system and method of determining locations of lightning strikes has been described. The system includes multiple receivers located around an area of interest, such as a space center or airport. Each receiver monitors both sound and electric fields. The detection of an electric field pulse and a sound wave are used to calculate an area around each receiver in which the lighting is detected. A processor is coupled to the receivers to accurately determine the location of the lighting strike. The processor can manipulate the receiver data to compensate for environmental variables such as wind, temperature, and humidity. Further, each receiver processor can discriminate between distant and local lightning strikes.

Abstract: Variable beamwidth antenna systems for use on spacecraft that is capable of changing their beamwidths while the spacecraft in on orbit. The variable beamwidth antenna systems include a main reflector, a subreflector, a feed horn, a main reflector displacement mechanism and a feed horn (or subreflector) displacement mechanism. For broaden the beamwidth, the RF feed horn and the subreflector are moved close together by proper distance. The main reflector is moved away from the subreflector along a line through centers of their respective surface by a distance given by a predetermined equation. Another embodiment of the present invention provides for a zoom contour beam antenna system that radiates a contour beam and whose beam is variable or zoomable.

Abstract: A non-invasive method and apparatus for monitoring changes in intracranial pressure which removes extracranial effects from the measurements. The method and apparatus can include the supplying of a fixed frequency electrical output to a transducer coupled to the patient's head, thereby generating an acoustical tone burst in the patient's head which generates a first echo and a second echo, the first echo reflecting from a first interface in the side of the patient's head coupled to the transducer, and the second echo reflecting from a second interface at the opposite side of the patient's head. The first and second echoes are received by the transducer which can generate a first electrical signal and a second electrical signal, wherein the first and second electrical signals vary in accordance with the corresponding first and second echoes.

Abstract: A barrier layer for a silicon containing substrate which inhibits the formation of gaseous species of silicon when exposed to a high temperature aqueous environment comprises a barium-strontium alumino silicate.

Abstract: Method and apparatus are provided for a non-invasive bubble measuring instrument operable for detecting, distinguishing, and counting gaseous embolisms such as bubbles over a selectable range of bubble sizes of interest. A selected measurement volume in which bubbles may be detected is insonified by two distinct frequencies from a pump transducer and an image transducer, respectively. The image transducer frequency is much higher than the pump transducer frequency. The relatively low-frequency pump signal is used to excite bubbles to resonate at a frequency related to their diameter. The image transducer is operated in a pulse-echo mode at a controllable repetition rate that transmits bursts of high-frequency ultrasonic signal to the measurement volume in which bubbles may be detected and then receives the echo. From the echo or received signal, a beat signal related to the repetition rate may be extracted and used to indicate the presence or absence of a resonant bubble.