Abstract: A system and method which substantially eliminates systematic error in a centroid determination of reconstructed waveforms from images generated by an image sensor. In accordance with the invention, a predetermined wavefront error is added to an input wavefront and the wavefront is detected. The predetermined wavefront error is effective to improve centroid determination. In the illustrative embodiment, the input wavefront is passed through a random phase plate. The phase plate is an optical window in which the thickness in a z-axis varies randomly over an X/Y plane. The random phase plate acts as a low pass filter and the output of the phase plate is an aberrated wavefront. That is, the nonuniform thickness of the phase plate generates random spatial phase errors in the optical wavefront. The autocorrelation function of the phase plate is such that random phase errors in the optical wavefront will filter out spatial frequencies higher than one cycle per pixel.

Abstract: The invention relates to the field of ice protectors for inhibiting atmospheric ice accumulation on aircraft structures. More particularly, the invention relates to the bonding of an ice protector to an aircraft structure. According to an aspect of the invention, a device for inhibiting atmospheric ice accumulation on an aircraft structure is provided comprising a flexible ice protector, an intermediate layer bonded to the flexible ice protector, and a pressure sensitive adhesive layer bonded to the intermediate layer. The pressure sensitive adhesive layer defines a bonding surface that bonds the ice protector to the aircraft structure.

Abstract: A method for determining a resonant frequency of a mechanical device having a first mass and at least one second mass mechanically coupled to the first mass comprises the steps of: providing a control signal to a voltage-controlled oscillator (VCO) to control the frequency of an output thereof; translating a phase shifted output of the VCO into an oscillatory force which is applied to one of the first and second masses to cause the mechanical device to respond; measuring the response of the mechanical device and generating a response signal representative thereof in frequency and amplitude; generating an error signal proportional to the phase difference between a signal representative of the output of the VCO and the measured response signal; adjusting the control signal to cause the oscillatory force applied to the one mass to sweep within a calculated frequency range rendering the amplitude of the response signal to approach and exceed a calculated threshold value; and when the calculated threshold is excee

Abstract: An arrangement for an aircraft propulsion system to determinably reduce or eliminate inlet cowl induced bending of a turbofan aircraft jet engine case during certain flight conditions. The arrangement includes a turbofan aircraft jet engine having an engine case with a fan case portion, a nacelle structure housing the engine and having a forward nacelle portion and a rearward nacelle portion, and a pylon structure to support the engine and the nacelle structure while permitting the forward nacelle structure to be translated forwardly from an operational position to a servicing position to permit access to the engine and its components. The forward nacelle portion is independently supported from the pylon and has an inner skin portion that sealingly engages the fan case portion of the engine case and an outer skin portion that is determinably locked to the rearward nacelle portion.

Abstract: An optical spectrometer system has a central axis, a detector having a detector surface disposed at one end of the system and located at a focal plane of the optical spectrometer system. A cold stop is associated with the detector for permitting entrance of target source radiation onto the detector surface while blocking background radiation from surroundings. A cooling device is coupled to the detector for cooling it and the cold stop to a predetermined low temperature. A flat plate is provided and has an spectrometer slit formed in it, the plate having a flat surface facing the detector, the flat surface being coated with a highly reflective, low emissivity material. Fore-optic focusing lenses or mirrors are located in front of the flat plate for focusing radiation onto the slit on the flat plate between the fore-optic focusing and the collimating lenses. The collimating lenses between the flat plate and the cold stop collimate the light from the slit and form a pupil at the cold stop.

Abstract: An improved OBS based technique that monitors gas emissions from smoke stacks, tail pipes, and other sources, and that separates gas column density from thermal radiance contrast. The technique of the present invention utilizes a software generated digital filter (30) constructed to correlate with only the spectrum of gas (12) of interest, and have zero correlation with background components (22). Through using the improved OBS technique of the present invention, high performance and more positive cost effective gas monitoring systems and sensors may be built and implemented.

Abstract: The present invention pertains to an ice detector particularly adapted to detect the presence of water droplets capable of forming supercooled large droplet (“SLD”) icing on aircraft surfaces. The invention takes advantage of boundary layer flow patterns adjacent to the detector, and their effect on water droplets, to provide a signal indicative of SLD icing conditions when they exist. The detector is also capable of distinguishing between the presence of water droplets that cause traditional cloud icing and SLD icing.

Abstract: A computer software architecture for an embedded computer system. The architecture includes a hierarchy of software object classes. One classification includes a common information blackboard object. Data is written to the blackboard object by processes in a protected manner, and is otherwise globally readable by all processes. A run-time executive is provided to schedule and coordinate processes. Processes register with the run-time executive at start-up. One process can know the existence and generation of data by another process. The architecture is layered in increasing levels of system abstraction. In one embodiment, the embedded system is an airborne fuel gauging subsystem.

Abstract: A photolithography system includes a light source and illumination optics which receive light from the light source and project illumination light onto a mask. Light transmitted through the mask is received by projection optics which generate an enlarged image of the mask. The enlarged image is projected onto the surface of a substrate such as a semiconductor wafer or flat panel display. The system achieves a wafer or panel feature size of less than 10 &mgr;m, preferably 3 &mgr;m, while enlarging the image of the mask to produce large wafers and panels in a single exposure. A deformable substrate chuck is selectively deformable to ensure a flat substrate surface. An alignment subsystem ensures precise registration between exposure layers.

Abstract: A translating sleeve structure for a cascade type thrust reverser system for controlling fan air for a turbofan aircraft gas turbine jet engine, such translating sleeve having a plurality of circumferentially arranged spaced blocker doors, each of which is hingedly connected to a door receptacle bonded into a single layer honeycomb panel inner wall of the sleeve at a longitudinal position which is aft of bleed ports positioned in the core cowl of the engine for periodically expelling gases from the engine at elevated temperatures and pressures. Positioning such blocker doors aft of the bleed ports precludes injury to the blocker doors or to their hinged connections to the core cowl and permits smaller uniformly sized doors to be used.

Abstract: An enhanced electrical harness arrangement for an aircraft engine that is arranged to provide optimum protection of the electrical conductors from extreme thermal, EMI, vibration and chafing problems encountered in service. The harness arrangement provides a high degree of repairability thereby ensuring a long service life for the harness wile also minimizing the time required for necessary repairs to the electrical conductor terminals. A repair splice member has an electrical conductor bundle inserted through it and is spaced from a connection of the electrical conductor bundle to an aircraft gas turbine engine.

Abstract: The present invention relates to a enclosure for a control surface position transmitter used on aerospace vehicles. The enclosure has improved capability for protecting the components of the position transmitter from damage caused by moisture-induced corrosion. The enclosure is a can-shaped structure that includes separate compartments for its mechanical and electronic components. A series of channels and passageways allow air to circulate freely in and out of the mechanical component compartment, and the electronic component compartment includes a low power heater to keep the electronic components dry and moisture-free.

Abstract: An air data probe (10) such as a pitot probe, pitot-static probe, or total air temperature probe incorporates heaters (42) within the wall (30) of the device. The heater (42) extends from the base (12) of the probe (10) to the tip (18) of the probe (10). In a preferred embodiment, the heater (42) is a wire heater that extends in the wall (30) of the probe (10) from the base (12) to the tip (18), and surrounds a sampling chamber (24) in the probe (10) in a spiral pattern.

Abstract: A pressurized bearing assembly for turbomachines like gas turbine engines wherein pressurized oil is used to apply an axial force to the outer bearing race of a ball bearing assembly. The force is transmitted through the race to the ball bearings and to the inner race of the bearing assembly, and is further transmitted, via the engine shaft, to the bearings of another, axially spaced apart bearing assembly. The force moves the balls in both assemblies into line-on-line running contact with their respective bearing races, and minimizes vibration in the assemblies.

Abstract: Fuel flow to the combustor of a gas turbine engine is regulated by controlling the amount of fuel delivered to the primary and secondary fuel orifices of a hybrid fuel nozzle. A one-way valve extending between primary and secondary fuel manifolds is controlled by an electronic sensor that acts upon signals received from sensors at station 4.5 of the engine, and by sensors that measure engine speed. By opening and closing the valve based upon T.sub.4.5 and N.sub.2 speed, optimum engine operating conditions are achieved.

Abstract: A method for determining whether surface connected, through thickness defects exist in a coated carbon-carbon composite article. The method involves the immersion of the coated article in a low viscosity liquid; if a stream of bubbles rises from the surface of the coating, such bubbles indicate the existence of at least one surface connected, through thickness defect in the coating.

Abstract: The oxidation resistance of MCrAlY-type overlay coatings is improved by incorporating small discrete oxide particles into the coating. The particles are preferably yttrium oxide, and the coating is applied by simultaneously plasma spraying MCrAlY-type powder particles and oxide particles onto a substrate in a nonoxidizing atmosphere. Improvements in resistance to rumpling has also been observed in coatings applied according to this invention.

Abstract: Casting cores particularly useful in the investment casting industry are described. The cores are characterized by the presence of hollow ceramic particles, which facilitate the removal of the core from the casting they are used to form. In a preferred embodiment of the invention, the core is characterized by solid and hollow ceramic particles sintered to each other to form a core matrix, and such particles have the same composition. In an even further preferred embodiment, high temperature stable fibers are distributed uniformly throughout the matrix.

Abstract: An improved thermal barrier coating system is described. A key feature of the invention is the presence of a thin, adherent aluminum oxide scale on the surface of the substrate. An oxide stabilized ceramic coating is present on the surface of the scale. Preferably, the ceramic coating has a columnar grain structure.

Abstract: A powder mixture for applying gas phase aluminide coatings to nickel or cobalt base superalloys is described. A preferred mixture consists essentially of Co.sub.2 Al.sub.5, NH.sub.4 F.HF, and chromium metal. The mixture is substantially free of aluminum oxide.