Abstract: Ceramic radomes are fabricated using a method which reduces the dielectric losses of the ceramic material. A Si.sub.3 N.sub.4 ceramic powder is mixed with a suitable densification aid and then sintered to form a dense ceramic having a glassy phase. Silicon dioxide is then provided on the surface of the ceramic by packing it in silicon dioxide powder or by heating it in air to oxidize its surface. The ceramic and silicon dioxide are heated at a temperature sufficient to cause diffusion of impurities and additive cations from the glassy phase into the silicon dioxide. The surface of the ceramic is then ground to remove pits and to shape the ceramic into a radome.

Abstract: Noise is removed from the digitized output of a sensor, subject to undesired resonance, even when the resonant frequency is unknown or drifts, with sufficiently low phase delay for the sensor to be used in closed-loop control. A very narrow notch filter which removes the resonance-induced noise is recursive (IIR) and therefore has a low phase delay. However, the apparatus which determines the center frequency of the notch filter is non-recursive, and therefore stable. It includes a tunable FIR filter which tracks the same resonance that we wish the IIR filter to remove. Tuning the FIR filter to minimize the output of the FIR filter therefore tunes the notch frequency to align with the resonant frequency. The tuning parameter which adaptively produces this result is suitably scaled and biased, and is applied to the IIR filter.

Abstract: APPARATUS AND METHOD FOR MULTIPLE PROCESSOR SOFTWARE DEVELOPMENT include a host computer 10, a control processor 12, and a bus 16 between them and one or more nodes 14. Each node 14 includes a master processor 22 and one or more slave processors 24, all of the processors 22, 24 sharing a memory 26. Multiple processor application software may be developed using the host computer 10 and control processor 12 by concurrently monitoring every processor 22, 24 of every node 14. Each master processor 22 is monitored directly through a master transmit/receive buffer 20 between it and the bus 16, and each slave processor 24 of each node 14 is monitored indirectly through a slave transmit/receive buffer 38 in the node's shared memory 26, the buffer 38 extending between that slave processor 24 and that node's master processor 22.

Abstract: An estimate of amplitude of a sinusoidal signal is computed from a value of the signal by computing the value of a quadrature-phase signal and computing the amplitude based on the value of the signal and the value of the quadrature-phase signal. The quadrature-phase signal is computed, for example, by a Hilbert transform. The amplitude is approximated as the sum of the magnitude of one value and an even polynomial of the other value when the magnitude of the other value is relatively small. The amplitude is computed precisely by an iterative application of the approximation. In an automatic gain control, for example, the desired value is substituted for the actual amplitude in the iterative formula, to compute an error estimate that always has the same sign as the actual error. Therefore, the automatic gain control converges to set the amplitude of the sinusoidal signal to the desired value.

Abstract: A process is provided for protecting, containing, and/or completing fragile microelectronic and microelectromechanical (MEM) structures on a low conductivity substrate during anodic wafer bonding of a covering wafer. The wafer includes raised areas that contact the substrate at selected bonding regions to support the wafer as a covering structure over the substrate. The covering wafer includes additional raised areas, such as pillars or posts, that contact selected electric circuit lines on the substrate to form temporary shorts through the wafer. During anodic bonding of the wafer to the substrate, the temporary shorts maintain the connected circuit lines and microstructures at nearly the same electric potential to prevent unwanted arcing and electrostatic forces that could damage the fragile structures. The pillars or posts can be formed at the same time as the raised bonding areas, but on unwanted and otherwise unused portions of the covering wafer.

Abstract: Micromachining a microelectromechanical structure requires one or more heavily doped silicon layers. Intricately patterned structures are created in a heavily doped surface layer on a relatively undoped substrate. The substrate is subsequently dissolved in a selective etch. The doping prevents the patterned structures from dissolving. In this invention, a doped layer is grown epitaxially onto the first substrate rather than by diffusing a dopant into the substrate. This produces additional planarity, thickness control, and dopant profile control. The structure may then be placed into a larger device, such as an infrared sensor, an accelerometer, or an angular rate sensor.

Abstract: An optics assembly for observing a panoramic scene comprises a plurality of optical elements. A flat reflective element redirects light from a panoramic scene. A plurality of refractive elements, successively receive the redirected light from the reflective element and create a real pupil. An optical relay system receives light from a last of the plurality of refractive elements. The optical relay system establishes the focal length of the optics assembly, corrects optical aberrations produced at the real pupil, corrects field aberrations and produces an annular image on a flat focal plane assembly. The optics assembly produces a small F-number at field angles perpendicular to the optical axis of the optics assembly over a panoramic scene.

Abstract: A process for enhancing the bond strength of resistance welded joints between titanium alloy articles includes a first step of resistance welding two titanium alloy articles and a second step of heat treating the resistance welded titanium alloy articles in a vacuum or inert environment at temperatures in a range of 1675.degree. F. to 1825.degree. F. for a period of 15 minutes to 4 hours. The process of the present invention is particularly useful in providing efficient joining of face sheets to a honecomb core element.

Abstract: A housing provides temperature monitoring and temperature control of a specimen, while the specimen is being exposed to plasma environments for in-situ reactivity studies or other plasma processing purposes. The housing is adaptable for use with a temperature controller and a pressure measurement device. The housing includes a temperature monitoring mechanism and temperature control connections. The temperature monitoring mechanism provides in-situ specimen temperature indications. It includes a first enclosure having a specimen supporting portion on an exterior surface thereof. A fluid conduit has a first end in fluid communication with an interior portion of the first closure. A second enclosure has an interior portion thereof in fluid communication with a second end of the fluid conduit. The second enclosure includes the ability for attachment to a pressure measurement device.

Abstract: A first-order filter apparatus 48 (FIG. 4) includes an integrate-and-dump (I&D) circuit 50 and an output loop 52. The I&D circuit 50 is driven by a cyclic scaling element 54, which multiplies N consecutive input signals 56, x(m+1) to x(m+N), by a cycle of N scaling factors 58, c(1) to c(N). The I&D summer 60 drives a double-throw switch 62. The double-throw switch 62 applies the output of the I&D summer 60 to an I&D delay element 64 for N-1 input clock cycles, and for an Nth input clock cycle to the input of a non-cyclic scaling element 66. The non-cyclic scaling element 66 scales its input by a non-cyclic scaling factor, and applies its output to one input of a feedback summer 68. The output of the feedback summer 68 is y(k), the output of the apparatus. The index k advances by one every time that the index m advances by N. The output of the feedback summer 68 is also applied to an output feedback multiplying element 70, which multiplies it by B.sup.N.

Abstract: A method and apparatus for moving a first carrier tape in a first direction along a path, and a second tape toward the first tape, both in an incremental manner. After each increment of movement of the first tape, the second tape is advanced a proportional increment into overlying contact with the first tape. A press squeezes the first and second tape layers together, and a cutting mechanism is actuated to sever the overlying segment of second tape. The incremental movements of the first and second tapes are regulated so that the length of each second tape segment laid on the first tape is equal to the distance of travel of the first tape in the first direction. The direction of movement of the first tape is reversed so that at least one layer of second tape can be applied to the first tape.

Abstract: The invention is a method and apparatus for the application of machine readable matrix marking symbols, and especially two-dimensional matrix symbols, to a "host" substrate, optionally covering the symbols with protective layers, then using an ultrasound imaging apparatus to capture echo signals associated with the matrix symbols, then feeding the resultant information to a matrix symbol decoder to yield human-readable and video monitor displayable information.

Abstract: A vehicle radar emits four groups of single-frequency stepped radar pulses. In group A, the frequency of each pulse is a fixed amount higher than that of the preceding pulse. In group B, the frequency of each pulse is a fixed amount lower than that of the preceding pulse. In group C, the frequency of each pulse is the same as that of the preceding pulse. In group D, the frequency of each pulse depends on a modulo algorithm. The signals reflected from other vehicles may readily be processed with inexpensive equipment to discriminate among such other vehicles, and to determine the distance to, and relative speed of, each such vehicle.

Abstract: The vehicle includes a fuselage; a plurality of lifting surfaces attached to the fuselage having control devices attached thereto; and, an articulated propulsion system attached to the fuselage. The propulsion system includes a duct assembly pivotally connected to the fuselage. The duct assembly includes a duct and a propeller assembly mounted within the duct. A motor assembly is connected to the propeller assembly. The duct assembly may be positioned in a substantially vertical position to provide sufficient direct vertical thrust for vertical take-off and landing and may be directed in other positions to provide a varying spectrum of take-off and landing configurations, as well as a substantially horizontal position for high speed horizontal flight. Use of the control surface in the ducted propulsion assembly provides VTOL capability in a very small environment. The environment is not required to be prepared in any special manner.

Abstract: The optical coupler includes first, second and third port assemblies and a deflecting element. The first port assembly receives a first optical signal, the first port assembly including a first lensing element. The second port assembly emits a predetermined, transmitted portion of the first optical signal. The second port assembly includes a second lensing element. The deflecting element is positioned between the first and second port assemblies. The third port assembly includes a third lensing element. The deflecting element and the third port assembly are so positioned and arranged such that a deflected portion of the first optical signal is deflected from the deflecting element and directed through the third port assembly. The predetermined, transmitted portion of the first optical signal is directed through the second port assembly without being deflected by the deflecting element.

Abstract: A majority voted multiple-fault tolerant power switch for delivering power from a power source to an intended load. The power switch includes an optical voter, which has a photo conductor array for receiving optical voter input commands from a control system and for selecting a voter output from the majority of the input commands. An electronic power switch receives power input from the power source. The power switch is controlled by the voter output. An output from the power switch is connected to the intended load. A voltage source supplies the voltage to the optical voter. An operational amplifier circuit is connected to the electronic power switch to limit over current and inhibit reverse current in the electronic power switch.

Abstract: The present invention involves enhancing machine-readable matrix symbol markings on substrate materials by the addition of magnetizable materials, and then, at a later time, taking advantage of the magnetic properties associated with the matrix symbol marking to read the marking using a magneto-optic reading apparatus. For example, the marking material may be mixed with a media having magnetic properties and applied to a component surface either via stencil or as backfill. The magnetic material enables detection with the aid of a magnetic-property detection apparatus. Once detected, the matrix symbol image is transmitted to a symbol decoder so that the information represented by the symbol can be provided to a user.

Abstract: Noise may be reduced or eliminated from a digital sawtooth signal representing the phase of a periodic signal. This may be done precisely, even when inexpensive fixed-point arithmetic is used. In one aspect of the invention, the input signal (noise plus true signal) 12 is filtered to produce, in succession: (a) mod one differentiated noise plus slope of true phase signal 28; (b) mod one differentiated noise plus slope of residual phase signal (true phase signal minus estimated slope of true phase signal) 36; (c) mod one differentiated noise 46; (d) estimated noise 62; and (e) smoothed phase signal 72. In a second aspect, a noisy phase signal 12 is extracted from a first arbitrary periodic signal and the above steps are used to generate a noise-reduced phase signal 72. The noise-reduced phase signal 72 is then used to generate a second arbitrary periodic signal of the same frequency.

Abstract: A friction boring process creates a corrosion resistant fine grain microstructure in the wall surfaces of holes bored in aluminum alloy materials. A rotating tool is inserted directly into the aluminum material, or into a pre-drilled pilot hole, at a sufficient rotational velocity and feed rate to cause working that extends beyond the diameter of the tool, frictional heating, and extraction of aluminum material by metal deformation rather than cutting action as with a conventional drill bit. Burring, smoothing, and otherwise removing aluminum material extracted from the hole may be performed by a finishing segment that limits insertion depth of the tool. Frictional heating generates a temperature sufficient for rapid recrystallization of the remaining worked metal to form a fine grain microstructure to a depth of about 2.5 mm in the hole surfaces. Corrosion protection is retained even if some fine grain material is removed during a subsequent reaming operation.