DISH ANTENNA HAVING SWITCHABLE BEAMWIDTH NASA Case No. GSC-11760-1 Canada, France, Germany, Address inquiries to: Goddard Space Flight Center Mail Code: 204 Greenbelt, MD 20771 [Corresponding to U.S. Patent No. 3,866,233] The need frequently arises to augment narrow beamwidth transmitting and/or receiving antennas with a wide beamwidth “acquisition" mode. The present invention is a switchable beam width antenna employing a common main reflecting dish operable in at least two different beamwidth modes. It includes a concave parabolic main reflecting dish with a central circular region and a surrounding coaxial annular region. The central region of the main dish can be excited for wide beamwidth or the entire dish for narrow beamwidth. Conventional digital computers are composed of devices which perform logical operations on one-dimensional electrical binary signals. Such conventional digital computers are used to process large two-dimensional image or array data only with great difficulty since, in general, point-by-point scanning or interrogation of the images or arrays is required to convert the image data to a serial data stream suitable for digital computer processing. In this invention two-dimensional radiant energy gate devices receive two input arrays and provide an output array having digital states dependent only on the digital states of the signal elements of the two input arrays at corresponding row and column positions. The logic devices include an array of photoconductors responsive to at least one of the input arrays for either selectively accelerating electrons to a phosphor output surface, applying potentials to an electroluminescent output layer, exciting an array of discrete radiant energy sources, or exciting a liquid crystal to influence crystal transparency or refectivity. ELECTROSTATICALLY CONTROLLED HEAT SHUTTER NASA CASE No. NPO-11942 Australia, Canada, France, Address inquiries to: NASA Pasadena Office [Corresponding to U.S. Patent No. 3,763, 928] A heat transfer assembly for conducting thermal energy includes a hermetically sealed container enclosing a quantity of inert gas such as nitrogen. Two opposed walls of the container have high thermal conducting characteristics while the connecting walls have low thermal conducting characteristics. Electrodes are positioned adjacent the high thermal conducting walls and biased relative to the conducting walls to a corona potential for creating an ionic gas wind which must contact the conducting walls to be neutralized. The contact of the gas molecules permits the maximum thermal energy transfer between the walls. Baffles can be positioned adjacent the electrodes to regulate gas flow between the high thermal conducting surfaces. A surgical tissue macerating and removal tool is disclosed wherein a rotating member having a cutting tip is utilized. When the instrument is to be used in an eye, a treatment fluid is supplied to the operative site and a first pump is provided to evacuate macerated material and treatment fluid from the eye. A second pump means is provided on the rotating member to provide a counter flow of treatment fluid into the space between the rotating member and the support tube. The second pump may provide additional support for the rotating member. Means is also provided for axially positioning rotating member to increase or decrease cutting action. CATALYTIC TRIMERIZATION OF AROMATIC NITRILES AND TRIARYL-S-TRIAZINE RING CROSS-LINKED HIGH TEMPERATURE RESISTANT POLYMERS AND COPOLYMERS MADE THEREBY NASA Case No. LEW-12053-1 Canada, France, Great Britain, Address inquiries to: Lewis Research Center [Corresponding U.S. Patent-Application Pending] Prior trimerization methods are unsuitable for processing the aromatic nitrile-modified (terminated and/or appended) condensationtype prepolymers into s-triazine ring cross-linked high temperature resistant matriz resins for fiber reinforced composites. With this invention, aromatic nitriles such as p-cyanobenzoic acid and its esters, etc. can be directly trimerized to their corresponding triaryl-s-triazines at moderate temperature and pressure. Also, with this invention, the norborene groups on the addition-type polyimides are replaced by aromatic nitrile groups, or part of the monomeric reactants (aromatic diamines and tetracarboxylic acid dianhydride or their derivatives) of those soluble high molecular weight polyimides having relatively low thermal stability were replaced by nitrile appended aromatic diamines and aromatic tetracarboxylic acid dianhydrides or their derivatives. These terminating and/or appending aromatic nitrile groups are then catalytically trimerized to produce new triaryl-s-trazine ring containing or cross-linked polyimides which possess the outstanding thermal stability of both polyimides and aryl-s-triazines for continuous use at temperatures above 315°C. |