Abstract: Foamed cross-linked poly-N-arylenebinzimidazoles are prepared by mixing an organic tetraamine and an ortho substituted aromatic dicarboxylic acid anhydride in the presence of a blowing agent and then heating the prepolymer to a temperature sufficient to complete polymerization and foaming of the reactants. In another embodiment of the process, the reactants are heated to form a prepolymer. The prepolymer is then cured at higher temperatures to complete foaming and polymerization.

Abstract: Plastic surfaces can be improved physically and optically by treating them with a plasma of boron trifluoride. The trifluoride can be the sole reactant or be part of a mixture also containing an organic monomeric substance such as perfluorobutene-2 or an organosilane. The boron trifluoride-containing coating can also serve as an intermediate coating between the plasticl surface and a plasma deposited organic polymer.

Abstract: An intumescent-ablator coating composition which comprises an intumescent agent such as the ammonium salt of 1,4-nitroaniline-2-sulfonic acid or 4,4-dinitrosulfanilide, a polymeric binder system and about 5 to 30% by weight, based on the total weight of the intumescent agent and the binder, of an endothermic filler having a decomposition temperature about or within the exothermic region of the intumescent agent.

Abstract: A leveling apparatus for the precise level adjustment of a scientific instrument. A base member is provided having a hollow cylindrical shape. A table for supporting the instrument rests on the base and has a shaft portion extending below the table. The upper portion of the shaft fits tightly into the hollow portion of the base member whereas the lower portion of the shaft is machined to fit loosely. The lower portion of the shaft is provided with a groove cut around the circumference thereof. Adjusting screws are threaded through the hollow cylindrical portion and are adapted to enter the groove. By adjusting the screws, the lower portion of the shaft is moved in a vertical plane since the shaft is loosely fitted into the cylinder. The upper portion of the shaft which is tightly fitted into the upper end of the cylinder causes the cylinder to deform slightly providing a fulcrum point which allows the table to be leveled in response to the adjustment of the adjusting screws.

Abstract: A tread drum for animals, such as primates, includes a cylindrical housing mounted for rotation about a horizontal axis of revolution and having a cylindrical treadway portion on which the animal treads while the drum is rotated by means of a motorized drive. The treadway portion of the drum includes an electrode structure incorporated therein, with sectors thereof being independently energizable by means of a commutator and source of potential so that an electrical shock station is created behind a running-in-place station on the moving treadway. In this manner, if the animal should fall behind its running-in-place station, it may be shocked by treading on the energized electrode structure. One end of the tread drum comprises a transparent wall for unobstructed viewing of the animal being exercised.

Abstract: A walking boot assembly particularly suited for use with a positively pressurized spacesuit, including a bootie adapted to be secured to the foot of a wearer, an hermetically sealed boot for receiving the bootie having a walking sole, an inner sole and an upper portion adapted to be attached to an ankle joint of a spacesuit, a protuberance projected from the bootie and received within a recess formed in the inner sole of the boot for positioning the bootie relative to the boot, and releasable latching means for latching the protuberance in a received relationship with the recess.

Abstract: An arrangement for sensing the fluid separation along a surface employs a thermally insulating element having a continuous surface blending into and forming a part of the fluid flow surface. A heating conductor is mounted on the element at the element surface. Two thermal sensors each has a conductor, the sensor conductors being mounted at the element surface on opposite sides of the heating conductor. In operation a fluid flow along the surface in a direction successively through the conductors carries heat in its wake to the downstream conductor where it is sensed. The upstream sensor also senses the temperature of the fluid flow before it reaches the heating conductor. When the fluid flow separates from the surface at the area of the heating and sensing conductors, a sudden decrease in the temperature of the downstream sensor conductor and concomitant increase in the temperature of the upstream sensor conductor is an indication of the separation.

Abstract: An apparatus for performing electrophoresis and a multiple-sample applicator for use therewith. Electrophoresis is a physical process in which electrically charged molecules and colloidal particles, upon the application of a DC current, migrate along a gel or a membrane that is wetted with an electrolyte. If a membrane is used, its middle section is kept in tension horizontally above an electrolyte tank, while the ends of the membrane hang down into the electrolyte. If a gel is used, it is held in a tray which is placed on a cooling plate, and wicks make contact with the electrolyte. The tank has unique protected electrodes for conducting the DC current.A multiple-sample applicator is provided which coacts with a novel tank cover to permit an operator either to depress a single button, thus causing multiple samples to be deposited on the gel or on the membrane simultaneously, or to depress one or more sample applicators separately by means of a separate button for each applicator.

Abstract: An intumescent composition, which comprises a mixture of 4,4'-dinitrosulfanilide as the intumescent agent in a polymer binder mixture of a chlorinated polyolefin, a bisphenol A epoxy resin and a rubber-like amine hardener.

Abstract: A honeycomb-laminate composite structure comprisingA. a cellular core of a polyquinoxaline foam in a honeycomb structure, andB. a layer of a non-combustible fibrous material impregnated with a polyimide resin laminated on the cellular core,A process for producing the honeycomb-laminate composite structure and articles containing the honeycomb-laminate composite structure.

Abstract: A gas analyzer is disclosed which responds to the resonant absorption or emission spectrum of a specific gas by producing an acoustic resonance in a chamber containing a sample of that gas, and which measures the amount of that emission or absorption by measuring the stength of that acoustic resonance, e.g., the maximum periodic pressure, velocity or density achieved. In the preferred embodiment, a light beam is modulated periodically at the acoustical resonance frequency of a closed chamber which contains an optically dense sample of the gas of interest. The light beam is introduced into the chamber through a window transparent to the radiation in the spectral band of interest and located at a position in the chamber which can support a pressure maximum during acoustical resonance of the gas within the chamber. Periodic heating of the absorbing gas by the periodically modulated light beam incident on the gas then causes a cyclic expansion, movement, and pressure within the gas.

Abstract: An apparatus for measuring a sorbate dispersed or dissolved in a fluid stream and comprising an oscillator for generating a first alternating-current signal, an acoustic transmission line for disposition in the fluid stream and including an elongated body having a surface capable of sorbing an amount of the sorbate to be measured representative of the concentration thereof in the fluid stream, the body being capable of propagating acoustic energy along its length from one end portion to another end portion, the propagated acoustic energy being damped in amplitude and shifted in phase such that the change in amplitude or phase is proportional to the amount of sorbate sorbed by the surface, a first transducer for converting the alternating current signal to acoustic energy and for applying the acoustic energy to the one end portion, a second transducer for converting the acoustic energy propagated to the other end portion to a corresponding electrical signal, and a comparator for comparing the electrical signal

Abstract: A display for an aircraft simulator that produces an image of an air strip or the like that is accurate in color and in relative light intensity. A television camera supported over a terrain model that simulates an aircraft landing zone, a full spectrum color monitor connected to the camera and lens system for projecting the monitor image onto a lens or screen visually accessible to a trainee in the simulator. The camera is supported on a gantry frame and is movable in six degrees of freedom. There is a control yoke and like simulated aircraft controls accessible to the trainee the outputs of which are linked to the gantry frame. A monochromatic calligraphic display, a digital computer for producing a pattern on the display that corresponds to the lights associated with the landing strip on the terrain model and an optical system for projecting the calligraphic image onto the same lens so that it is superposed on the video representation on the landing field.

Abstract: An apparatus for dispensing fluid according to a time schedule is disclosed. Fluid automatically flows to individual dispensing units at predetermined times from a fluid supply and is available only for a predetermined interval of time after which an automatic control causes the fluid to drain from the individual dispensing units. Fluid deprivation continues until the beginning of a new cycle when the fluid is once again automatically made available at the individual dispensing units.

Abstract: An artificial leg includes a trunk socket, a thigh section hingedly coupled to the trunk socket, a leg section hingedly coupled to the thigh section and a foot section hingedly coupled to the leg section. A mechanical energy storage device, such as a spring, is operatively associated with the artificial leg for storage and release of energy during a normal walking stride of the user. More particularly, energy is stored in the mechanical energy storage device during a weight-bearing phase of the walking stride when the user's weight is on the artificial leg and energy is released during a phase of the normal walking stride, when the user's weight is removed from the artificial leg. The stored energy is released from the energy storage device to pivot the thigh section forwardly about the hinged coupling thereof to the trunk socket.

Abstract: An anthropomorphic master/slave manipulator system including master arm apparatus including a plurality of master tubular articulated portions which are coaxially adjacent one another and relatively rotatable, master transducing apparatus responsive to the relative rotation of the adjacent tubular portions and operative to provide a driving signal, slave arm apparatus including a plurality of slave tubular portions corresponding to those portions of the master arm apparatus, the slave tubular portions being coaxially adjacent one another and relatively rotatable, slave transducing apparatus responsive to the driving signal and operative to drivingly rotate the slave tubular portions through an angle that corresponds to the relative rotation of the corresponding master arm tubular portions, and a communication link between the master transducing apparatus and the slave transducing apparatus for applying the driving signal to the slave transducer.

Abstract: A precision capacitive shaft encoder providing a d-c signal corresponding to the angular position of a shaft. Two variable capacitances are coupled in tandem by a rotatable shaft. Each capacitor has a capacitance that varies linearly with a change in the angular position of the shaft, and the sum of the two capacitances is always constant for any angular position of the shaft. Each capacitance is alternately coupled to a reference d-c voltage and a discharge circuit. The capacitances are electrically coupled in series and the charge periodically acquired at the junction of the capacitances is a function of the position of the shaft. An error-compensating voltage is imposed on the junction when the capacitances are coupled to the reference voltages, and the junction is coupled to sample-and-hold apparatus provided with a error-correcting circuit.

Abstract: A self-calibrating radiometer comprising a block having a front surface for receiving incident radiation flux, an identically configured rear surface for receiving internally applied heat and a midportion for thermally insulating the rear surface from the front surface, the front surface being capable of absorbing as heat substantially all radiation flux incident thereupon and capable of reradiating substantially all of the absorbed heat, and the rear surface being capable of radiating substantially all heat applied thereto, a thermocouple configuration for sensing the heat radiated by each of the front and rear surfaces, an indicator for indicating any difference in the sensed heat, a heating element for applying enough heat to the rear surface so that no difference in heat radiated by the front and rear surfaces is indicated by the indicator, and a measuring circuit for measuring the heat applied to the rear surface, such measurement being indicative of the radiant flux incident on the front surface.

Abstract: A system for measuring fluid velocity in a turbulently flowing fluid including a sensing apparatus for dynamically sensing the mainstream and two orthogonal cross velocity components of the fluid and a transducer operative to provide three electrical output signals representative of the velocity components in the mainstream and in the cross directions. Signal processors can be utilized to derive the Reynolds stress wave and the Reynolds stress.

Abstract: A laser Doppler velocimeter for measuring the velocity of a flowing fluid comprising laser means for providing first and second beams of collimated coherent monochromatic electromagnetic radiation which are focused to intersect at a predetermined location in a flowing fluid, the movement of the particles of the fluid serving to scatter radiation in substantially all directions, the scattered radiation being shifted in frequency from that of the first beam by an amount corresponding to the velocity of the fluid at the predetermined location, a corner cube disposed generally forward of the predetermined location, the corner cube responding to a portion of the radiation scattered in the forward direction and being operative to reflect the portion in a direction substantially antiparallel to the forward direction, and a collector responsive to the frequency of the first beam and to the frequency of the reflected portion of radiation and operative to provide a frequency modulated signal representative of the veloc