Abstract: An electron beam microwave device having an evacuated interaction chamber to which are coupled a resonant cavity which has an opening between the resonant cavity and the evacuated interaction chamber and an electron gun which causes a narrow beam of electrons to traverse the evacuated interaction chamber. The device also contains a mechanism for feeding back a microwave electromagnetic field from the resonant cavity to the evacuated interaction chamber in such a way as to modulate the direction of propagation of the electron beam, thereby further amplifying the microwave electromagnetic field. Furthermore, provision is made for coupling the electromagnetic field out of the electron beam microwave device.

Abstract: A multireflector antenna utilizes a frequency-selective surface (FSS) in a subreflector to allow signals in two different RF bands to be selectively reflected back into a main reflector and to allow signals in other RF bands to be transmitted through it to the main reflector for primary focus transmission. A first approach requires only one FSS at the subreflector which may be an array of double-square-loop conductive elements. A second approach uses two FSS's at the subreflector which may be an array of either double-square-loop (DSL) or double-ring (DR). In the case of DR elements, they may be advantageously arranged in a triangular array instead of the rectangular array for the DSL elements.

Abstract: Surmounting obstacles in the path of a robot vehicle is accomplished by rotating the wheel forks of the vehicle about their transverse axes with respect to the vehicle body so as to shift most of the vehicle weight onto the rear wheels, and then driving the vehicle forward so as to drive the now lightly-loaded front wheels (only) over the obstacle. Then, after the front wheels have either surmounted or completely passed the obstacle (depending upon the length of the obstacle), the forks are again rotated about their transverse axes so as to shift most of the vehicle weight onto the front wheels. Then the vehicle is again driven forward so as to drive the now lightly-loaded rear wheels over the obstacle. Once the obstacle has been completely cleared and the vehicle is again on relatively level terrain, the forks are again rotated so as to uniformly distribute the vehicle weight between the front and rear wheels.

Abstract: A capacitive type proximity sensor having improved range and sensitivity between a surface and an intruding object in the vicinity of the surface having a voltage source, a number of outer electrical conductors on the surface with each forming one electrode of a number of sensor capacitors, the other electrode for each sensor capacitor being the object. The outer conductors are made from thin sheets of conductive material covered with insulation. An intermediate electrical conductor is located between the outer conductors and the surface and is of a size larger than the outer conductors to act as a shield for reducing the parasitic capacitance between the outer conductors and the surface. The intermediate conductor is also made from a thin sheet of conductive material covered with insulation.

Abstract: An ion exchange polymer comprised of an alkali metal or alkaline earth metal salt of a poly(carboxylic acid) in a poly(vinyl acetal) matrix is described. The polymer is made by treating a mixture made of poly(vinyl alcohol) and poly(acrylic acid) with a suitable aldehyde and an acid catalyst to cause acetalization with some cross-linking. The material is then subjected to an alkaline aqueous solution of an alkali metal salt or an alkali earth metal salt. All of the film forming and cross-linking steps can be carried out simultaneously, if desired.

Abstract: A feedback control system compensator of the PID type is provided, wherein the proportional component of the compensator is replaced with a tilted component having a transfer function s to the power of -1/n. The resulting transfer function of the entire compensator more closely approximates an optimal transfer function, thereby achieving improved feedback controller. Further, as compared to conventional PID compensators, the TID compensator allows for simpler tuning, better disturbance rejection ratio, and smaller effects of plant parameter variations on closed loop response.

Abstract: A method and an apparatus for the rapid learning of nonlinear mappings and topological transformations using a dynamically reconfigurable artificial neural network is presented. This fully-recurrent Adaptive Neuron Model (ANM) network has been applied to the highly degenerative inverse kinematics problem in robotics, and its performance evaluation is bench-marked. Once trained, the resulting neuromorphic architecture was implemented in custom analog neural network hardware and the parameters capturing the functional transformation downloaded onto the system. This neuroprocessor, capable of 10.sup.9 ops/sec, was interfaced directly to a three degree of freedom Heathkit robotic manipulator. Calculation of the hardware feed-forward pass for this mapping was benchmarked at .apprxeq.10 .mu.sec.

Abstract: Apparatus for an ion engine comprises a three-grid accelerator system with the decelerator grid biased negative of the beam plasma. This arrangement substantially reduces the charge-exchange ion current reaching the accelerator grid at high tank pressures, which minimizes erosion of the accelerator grid due to charge-exchange ion sputtering, known to be the major accelerator grid wear mechanism. An improved method for life testing ion engines is also provided using the disclosed apparatus. In addition, the invention can also be applied in materials processing.

Abstract: A constant current loop measuring system is provided for measuring a characteristic of an environment. The system comprises a first impedance positionable in the environment, a second impedance coupled in series with said first impedance and a parasitic impedance electrically coupled to the first and second impedances. A current generating device, electrically coupled in series with the first and second impedances, provides a constant current through the first and second impedances to produce first and second voltages across the first and second impedances, respectively, and a parasitic voltage across the parasitic impedance. A high impedance voltage measuring device measures a voltage difference between the first and second voltages independent of the parasitic voltage to produce a characteristic voltage representative of the characteristic of the environment.

Abstract: Nonlinear control method is provided for a closed-loop trajectory in a control system of the form x=.function.(x)+u through a sliding surface, s, chosen such that s=e+.lambda.e=, where e is the trajectory, and .lambda. is a positive constant using a control law of the form ##EQU1## which exploits terminal attractors of the form ##EQU2## where .alpha. is a constant greater than zero, .beta..sub.n, .beta..sub.d =(2i+1), where i belongs to the set of positive integers chosen for .beta..sub.n and .beta..sub.d, and .beta..sub.d >.beta..sub.n for convergence in finite time. For a system in which an initial S.sub.i is zero, a control law is used of the form ##EQU3## which yields a control equation ##EQU4## where .delta..sub.n, .delta..sub.d =(2i+1), wherein i belongs to the set of positive integers chosen for .delta..sub.n and .delta..sub.d, and .delta..sub.d >.delta..sub.n for retaining convergence in finite time.

Abstract: A system for recovering and recycling gases is disclosed having, in one aspect, inlet and outlet flow lines and controllers with an inflatable enclosure which, in one aspect, has a series of one or more inflatable rib stiffeners which, in one aspect, are inflatable by the gas to be stored. In one aspect the system does not present gas at an undesirable back pressure to the gas source. In one aspect a filtering relief valve is employed which prevents environmental airborne contamination from flowing back into the system when the relief valve is closing. In one aspect the system is for storing and re-using helium.

Abstract: A portion of an organic polymer article such as a membrane is made hydrophilic by exposing a hydrophobic surface of the article to a depth of about 50 to about 5000 angstroms to atomic oxygen or hydroxyl radicals at a temperature below 100.degree. C., preferably below 40.degree. C., to form a hydrophilic uniform surface layer of hydrophilic hydroxyl groups. The atomic oxygen and hydroxyl radicals are generated by a flowing afterglow microwave discharge, and the surface is outside of a plasma produced by the discharge. A membrane having both hydrophilic and hydrophobic surfaces can be used in an immunoassay by adhering antibodies to the hydrophobic surface. In another embodiment, the membrane is used in cell culturing where cells adhere to the hydrophilic surface. Prior to adhering cells, the hydrophilic surface may be grafted with a compatibilizing compound.

Abstract: An apparatus and method is disclosed for regulating flow of working fluid through parallel condensation tubes requiring subcooling. The apparatus provides an elongated restriction element extending into the outlet of the respective condensation tubes to the approximate point of onset of subcooling. The elongated restriction element is braced externally to the condensation tube with a support that is used for positioning and maintaining the elongated restriction element in the correct position. The elongated restriction element has a pentagonal cross-section and is slightly undersize with respect to the working fluid passageways through the condensation tubes. The restriction member significantly restricts flow of partially vaporized working fluid but does not significantly affect the flow of fully liquid working fluid.

Abstract: Service equipment 10 for use in hostile environments includes a detachable service unit 20 secured to a stationary service unit 50 as shown in FIG. 1. The detachable service unit includes a housing 28 with an exterior plate 22, a power control interface 16 for connection to an exterior power source 48, locating pins 30a-30d located in said exterior plate, an electrical connector 40 in the exterior plate electrically coupled to said power control interface, and a pair of clamping receptacles 24 and 25 formed in the exterior plate and located on adjacent opposite edges of the exterior plate as shown in FIGS. 4A and 4B. The stationary unit includes an electrical connector 46 for connection to the electrical connector of the detachable service unit, a clamping apparatus 60 for clamping and unclamping the detachable service unit from the stationary unit, a base clamp assembly 120 shown in FIG. 5A for mounting the clamping apparatus onto the stationary unit, and locating pin holes 51 shown in FIG.

Abstract: A landing pad system for absorbing horizontal and vertical impact forces upon engagement with a landing surface (15) where circumferentially arranged landing struts (12) respectively have a clevis (24) which receives a slidable rod member (13) and where the upper portion of a slidable rod member is coupled to the clevis by friction washers (30,32) which are force fit onto the rod member to provide for controlled constant force energy absorption when the rod member moves relative to the clevis. The lower end of he friction rod is pivotally attached by a ball and socket (44) to a support plate (42) where the support plate is arranged to slide in a transverse direction relative to a housing which contains an energy absorption material (50) for absorbing energy in a transverse direction.

Abstract: This invention is a method for the controlled growth of single-crystal semiconductor-device-quality films of SiC polytypes on vicinal (0001) SiC wafers with low tilt angles. Both homoepitaxial and heteroepitaxial SiC films can be produced on the same wafer. In particular, 3C-SiC and 6H-SiC films can be produced within selected areas of the same 6H-SiC wafer.

Abstract: The present invention discloses a method of detecting and locating current imbalances such as ground faults in multiwire systems using the Faraday effect. As an example, for 2-wire or 3-wire (1 ground wire) electrical systems, light is transmitted along an optical path which is exposed to magnetic fields produced by currents flowing in the hot and neutral wires. The rotations produced by these two magnetic fields cancel each other, therefore light on the optical path does not read the effect of either. However, when a ground fault occurs, the optical path is exposed to a net Faraday effect rotation due to the current imbalance thereby exposing the ground fault.

Abstract: Silicon and metal are coevaporated onto a silicon substrate in a molecular beam epitaxy system with a larger than stoichiometric amount of silicon so as to epitaxially grow particles of metal silicide embedded in a matrix of single crystal epitaxially grown silicon. The particles interact with incident photons by resonant optical absorption at the surface plasmon resonance frequency. Controlling the substrate temperature and deposition rate and time allows the aspect ratio of the particles to be tailored to desired wavelength photons and polarizations. The plasmon energy may decay as excited charge carriers or phonons, either of which can be monitored to indicate the amount of incident radiation at the selected frequency and polarization.

Abstract: The apparatus disclosed in the present invention measures the force at which a fiber resist the motion of an indenter driven at constant speed. This apparatus conducts these test in a vacuum of about 10.sup.-6 tort and at temperatures up to 1100.degree. C. Temperature and vacuum environment are maintained while controlling indenter motion, sample position, and providing magnified visual inspection during the test.

Abstract: A capacitive type proximity sensor having substantial range and sensitivity between a machine and an intruding object in the immediate vicinity of the machine and having a steerable sensing field has an outer electrical conductor on the machine forming one electrode of a sensor capacitor, the other electrode is the object. The outer conductor is a thin sheet of conductive material with a pair (or more) of intermediate electrical conductors located between the outer conductor and the machine. The pair of intermediate electrical conductors are in close proximity to each other and together form a surface having a size substantially larger than the outer conductor to act as a shield for reducing the parasitic capacitance between the outer conductor and the machine and to steer the sensor field. The pair of intermediate conductors are thin sheets of conductive material substantially wider than the first conductor.