Abstract: A load positioning system with gravity compensation has a servo-motor (12), position sensing feedback potentiometer (38) and velocity sensing tachometer (42) in a conventional closed-loop servo arrangement to cause lead screw (14) and ball nut (20) to vertically position load (22). Gravity compensating components comprise the DC motor (32), gears (34) and (36), which couple torque from motor (32) to the lead screw (14), and constant-current power supply (37). The constant weight of the load (22) applied to the lead screw (14) via the ball nut (20) tends to cause the lead screw (14) to rotate, the constant torque of which is opposed by the constant torque produced by motor (32) when fed from the constant-current source (37). The constant current is preset as required by potentiometer (54) to effect equilibration of the load (22) which thereby enables the positioning servo-motor (12) to "see" the load (22) as weightless under both static and dynamic conditions.

Abstract: Cured polyfunctional epoxy resins including tris(hydroxyphenyl)methane triglycidyl ether are toughened by addition of polybrominated polymeric additives having an EE below 1500 to the pre-cure composition. Carboxy-terminated butadiene-acrylonitrile rubber is optionally present in the pre-cure mixture as such or as a pre-formed copolymer with other reactants. Reinforced composites, particularly carbon-reinforced composites, of these resins are disclosed and shown to have improved toughness.

Abstract: A method and apparatus for digitizing audio signals being generated from a plurality of parties (A, B) in order to provide audio communication between the parties with a minimum of interference. Each of the parties has an audio transmitter and receiver (38, 58) provided for transmitting and receiving audio signals. The audio signals are converted (40) to a PCM companded eight-bit parallel signal followed by conversion (42) to a serial signal for transmitting to a remote location and then reconverting (46) each of the companded serial signals to a first eight-bit parallel signal. A pre-programmed ROM (48) is located at the remote location and has a plurality of inputs and outputs. Each of the eight-bit parallel signals from the individual parties are fed to the ROM causing the ROM to produce an eight-bit signal on the output representing the instantaneous sum of the eight-bit parallel signals being supplied to the inputs thereof.

Abstract: Compounds having the general formula 1 ##STR1## wherein X and Y are functional groups, preferably amino groups, are polymerized with, for example, polyfunctional epoxides to provide heat and fire resistant polymers useful for making flame and fire resistant polymer structures such as for aircraft secondary structures. The groups R in 1 are preferably alkyl and lower halo (e.g., chloro) alkyl.

Abstract: A display for aiding the pilot of an aircraft in anomalous wind environments. Wind velocity components are measured by an instrument 11, processed by a computer 12 and a vector generator 17 and then displayed as a vector 34 on the display shown in FIG. 3. A signal F indicative of flap position selects a flight validated lift curve which is displayed as a lift curve channel 42. During normal wind conditions the cursor 35 marking the termination of vector 34 is in the channel of curve 42. However, during wind anomalies cursor 35 moves outside the channel. It then becomes the task of the pilot to control the aircraft such that cursor 35 will move back into the channel.

Abstract: A two axis joystick controller (14) produces at least one output signal in relation to pivotal displacement of a member (32) with respect to an intersection of the two axes. The member (32) is pivotally movable on a support (42) with respect to the two axes. The support (42) has a centrally disposed aperture (46). A light source (34) is mounted on the pivotally movable member (32) above the aperture (46) to direct light (47) through the aperture. A light sensor (48) is mounted below the aperture (46) in the support (42) at the intersection of the two axes to receive the light (47) from the light source (34) directed through the aperture (46). The light sensor (48) produces at least one output signal related to a location on the sensor (48) at which the light (47) from the light source strikes the sensor (48). The two axis controller (14) is small enough in size to be mounted on another, hand-operated X-Y controller (10) for thumb operation by a hand positioned to operate the other X-Y controller (10).

Abstract: Novel amine terminated bisaspartimides, especially 4,4'-bis{N.sup.2 -[4-(4-aminophenoxy)phenyl]aspartimido}diphenylmethane are prepared by a Michael-type reaction of an aromatic bismaleimide and an aromatic diamine in an aprotic solvent. These bisaspartimides are thermally polymerized to yield tough, resinous polymers cross-linked through --NH-- groups. Such polymers are useful in applications requiring materials with resistance to change at elevated temperatures, e.g., as lightweight laminates with graphite cloth, molding material prepregs, adhesives and insulating material.

Abstract: The present invention relates to mixed bismaleimide/biscitraconimide resins. Mixtures of the two resins produces materials which have better handling, processing or mechanical and thermal properties, particularly in graphite composites, than materials made with the individual resins. The mechanical strength of cured graphite composites prepared from a 1:1 copolymer of such bisimide resins is excellent at both ambient and elevated temperatures. The copolymer mixture provides improved composites which are lighter than metals and replace metals in many aerospace applications.

Abstract: Perfluoroether triazine elastomers having improved properties are prepared from oligomeric imidoylamidines that have, in turn, been prepared by the process of (a) reacting a perfluorodinitrile with liquid ammonia to yield a perfluorodiamidine, (b) isolating the perfluorodiamidine, (c) reacting the isolated diamidine with a perfluorodinitrile to yield a perfluoro(imidoylamidine) dinitrile, and then repeating steps (a), (b), and (c) to sequentially grow an oligomer of desired molecular size. The isolated amidine and nitrile intermediates are also disclosed. The elastomers can be fashioned into seals, gaskets, sealing components and the like.

Abstract: 4-Aminophenoxy cyclotriphosphazenes are reacted with maleic anhydride to produce maleamic acids which are converted to the maleimides. The maleimides are polymerized. By selection of starting materials (e.g. hexakis amino or trisaminophenoxy-trisphenoxy-cyclotriphosphazenes), selection of molar proportions of reactants, use of mixtures of anhydrides and use of dianhydrides as bridging groups a variety of maleimides and polymers are produced. The polymers have high limiting oxygen indices, high char yields and other useful heat and fire resistant properties making them useful as, for example, impregnants of fabrics.

Abstract: Cured polyfunctional epoxy resins including tris(hydroxyphenyl)methane triglycidyl ether are toughened by addition of polybrominated polymeric additives having an EE below 1500 to the pre-cure composition. Carboxy-terminated butadiene-acrylonitrile rubber is optionally present in the precure mixture as such or as a pre-formed copolymer with other reactants. Reinforced composites, particularly carbon-reinforced composites, of these resins are disclosed and shown to have improved toughness.

Abstract: A rack (10) for laboratory bottles and jars for chemicals and medicines has been designed to provide the maximum strength and security to the glassware in the event of a significant earthquake. The rack (10) preferably is rectangular and may be made of a variety of chemically resistant materials including polypropylene, polycarbonate, and stainless steel. It comprises a first plurality of parallel vertical walls (14, 32, 33, 16, etc.), and a second plurality of parallel vertical walls (18, 30, 31, 20, etc.) perpendicular to the first plurality of walls. These intersecting vertical walls comprise a self-supporting structure without a bottom which sits on four legs. The top surface of the rack is formed by the top edges of all the vertical walls, which are not parallel but are skewed in three dimensions. These top edges form a grid matrix having a number of intersections (22, 24, etc.) of the vertical walls which define a number of rectangular compartments having varying widths and lengths and varying heights.

Abstract: Baffles (34) in infrared telescope (10) extend circumferentially around tube (12) of the telescope. Each of the baffles (34) has a concave, rearwardly facing curved surface (36) and a frontwardly facing planar surface (38). Baffles (34) extend from the interior wall of tube (12) in an acute angle with the optical axis (20) of the telescope, relative to front end (14) of the tube (12). This acute angle becomes greater for the baffles (34) toward rear end (16) of the telescope (10). Incoming off axis rays (44) are reflected by the planar surface (38) of the baffles (34) against the curved surface (36) of a forward adjacent baffle (34) and are reflected back and forth between adjacent surfaces (38) and (36) a number of times before being reflected back as rays (46) out of the front end of the telescope (10). Other off axis rays (40) are directly reflected as rays (42) by the planar surfaces (38) of the baffles (34).

Abstract: A circuit for use in a transponder located in an aircraft or the like for identifying a true side lobe suppression signal being transmitted by a ground located transmitted system. The true side lobe suppression signal includes at least pulses P1 and P2. The circuit causes the transponder to produce a reply signal upon the amplitude of the P1 pulse being a predetermined ratio to said P2 pulse. The circuit includes a pair of transistors with a capacitor connected to the output of the second transistor. The pulses P1 and P.sub.2 are supplied to the base electrode of the first transistor. Pulse P1 turns on the two transistors and charges the capacitor to a predetermined level so that when the second pulse P2 arrives, it does not turn on a transistor when it is equal to or less than the first pulse P1.

Abstract: Metal, preferably divalent copper, cobalt or nickel, phthalocyanine tetraamines are used as curing agents for epoxides. The resulting copolymers have high thermal and chemical resistance and are homogeneous. They are useful as binders for laminates, e.g. graphite cloth laminate.

Abstract: Metastable ionization detectors used for chromatographic analysis usually employ a fixed high voltage for the ionization potential. For this reason, the operating range is limited to about three orders of magnitude. By use of the technique disclosed in the instant invention, operating ranges of about nine orders of magnitude are obtained.The output current from a metastable ionization detector (MID) is applied to a modulation voltage circuit. An adjustment is made to balance out the background current, and an output current, above background, is applied to an input of a strip chart recorder. For low level concentrations, i.e., low detected output current, the ionization potential will be at a maximum and the metastable ionization detector will operate at its most sensitive level.

Abstract: Phosphorus-containing polyimides and copolyimides are synthesized in a two-step polycondensation reaction from 1-[(diorganooxyphosphonyl)methyl]-2,4- and -2,6-diaminobenzenes and tetracarboxylic anhydride. The diorgano position of the diorganooxyphosphonyl group includes alkyl, such as ethyl, substituted alkyl, such as 2-chloroethyl, and aryl such as phenyl. The tetracarboxylic anhydrides include compounds such as pyromellitic dianhydride and benzophenone tetracarboxylic dianhydride. The glass transition temperature (Tg) of the polyimides is reduced by incorporation of the (dialkoxyphosphonyl)methyl groups. Both the molecular weight and the thermal stability of the polymers are reduced with increasing concentration of the phosphorus moieties.

Abstract: Pentaerythritol can be converted to its diformal, 2,4,8,10-tetroxaspiro[5.5]undecane, by heating it to a temperature within the range of about 110.degree. to 150.degree. C. for a period of up to 10 minutes, in the presence of a slight excess of paraformaldehyde and of a catalytic quantity of an acid catalyst such as sulfuric acid. The reaction may be carried out in two steps, by forming first the monoformal, then the diformal. In any case, total reaction time is about 10 minutes and yield of diformal are greater than 90%.Previous processes require hours or days, and often, tedious operating procedures.

Abstract: Metal 4, 4', 4", 4"'-tetracarboxylic phthalocyanines (MPTC) are prepared by reaction of trimellitic anhydride, a salt or hydroxide of the desired metal (or the metal in powdered form), urea and a catalyst. A purer form of MPTC is prepared than heretofore. These tetracarboxylic acids are then polymerized by heat to sheet polymers which have superior heat and oxidation resistance. The metal is preferably a divalent metal having an atomic radius close to 1.35.ANG..

Abstract: An active R bandpass filter network (10) is formed by four operational amplifier stages interconnected by discrete resistances. One pair of stages (12, 14) synthesizes an equivalent input impedance of an inductance (L.sub.eq) in parallel with a discrete resistance (R.sub.0) while the second pair of stages (16, 18) synthesizes an equivalent input impedance of a capacitance (C.sub.eq) serially coupled to another discrete resistance (R.sub.i) coupled in parallel with the first two stages. The equivalent input impedances aggregately define a tuned resonant bandpass filter in the roll-off regions of the operational amplifiers.