Abstract: Construction and assessment methods provide a three dimensional scanning trajectory to ensure the acquisition of a complete set of Radon data for exact image reconstruction of an object irradiated by a cone beam source is described. The three dimensional scanning trajectory must be nowhere disconnected permitting the source to traverse the scanning trajectory in a continuous manner from start point to end point. The trajectory defines edges wherein a convex surface is formed by connecting these edges, this surface is known as a convex hull. If the convex hull defined by a trajectory encloses the object to be scanned, a complete set of Radon data for exact image reconstruction of the object can be acquired. This provision amounts to satisfying the three dimensional completeness criterion. Furthermore, if any planar projection of the trajectory encloses the corresponding planar projection of the object, the three dimensional completeness criterion is satisfied by using projected planar visualization aids.

Abstract: A seam-tracking apparatus for a welding system has a welding arm which directs an energy beam toward a seam. The seam-tracking apparatus includes an eddy current sensor formed by an array of eddy current elements, each producing a respective electrical signal when positioned adjacent to the seam to be tracked. An eddy current signal processor receives each respective electrical signal so as to generate position data indicative of the location of the seam. A controller is responsive to the position data so as to align the eddy current sensor and the welding arm over the seam so that the energy beam continuously impinges on the seam, as the welding arm advances along the seam. The eddy current sensor may be flexible, in which case the seam-tracking apparatus can track a seam between workpieces having curved surfaces.

Abstract: Imaging of a region of interest within a larger object is accomplished without the need for determining Radon derivatives of portions of the object outside a field of view which generally corresponds to the region of interest. The field of view and region of interest may be relatively large compared to a relatively small area detector used for the imaging. In order to provide a complete data set satisfying Radon completeness requirements with little or no collection of data from outside the region of interest, a source scanning trajectory uses a first circle, a second circle, and a helical portion connecting the first and second circles. The first and second circle and helical portion define a cylinder which is outside and surrounding the field of view, which is likewise a cylinder.

Abstract: Computerized tomography (CT) reconstruction of images is accomplished for asymmetric grids. After initial data acquisition and normalization, the asymmetric projection data is distorted by a compression process which effectively converts the data into symmetric data. The data may then be processed using Radon reconstruction procedures which convert projection data into object density functions. The object density functions or data which are provided are then subject to a stretching or extension procedure which compensates or reverses the initial distortion or compression. Cone beam imaging with asymmetric grids may be two-dimensional or three dimensional when utilizing the technique.

Abstract: An improved high performance x-ray system having a rotating anode therein which includes an improved coating for the x-ray tube rotor. The surface of the x-ray tube rotor is coated with a ductile coating wherein at least about 40,000 x-ray scan-seconds are accomplished prior to tube failure due to spalling. The coating may be a ductile alloy such as Rene' 80 having a thickness of about 0.2 to about 5.0 mils thick and may be even thicker. The rotor coating has ductile properties with a strain to fail greater than 0.05% and thermal expansion properties which when placed on an x-ray tube rotor, provides at least about 40,000 x-ray scan-seconds prior to tube failure due to rotor spalling.

Abstract: Carbon monoxide and unburned hydrocarbon burnout in gas turbine combustors is promoted by a combustor liner having a plurality of vortex generating members or ridges formed therein. The liner includes a substrate having an inner surface and a thermal barrier coating disposed on the inner surface. The vortex generating ridges are formed in the thermal barrier coating and extend transverse to the mean direction of flow through the liner. The thermal barrier coating is capped with a catalytic material which enhances carbon monoxide and unburned hydrocarbon oxidation. The ridges are defined by raised portions of the catalytic material and are of sufficient height to cause mixing between the hot flame products and the cool incompletely-burned flow along the liner wall. Alternatively, the ridges can be defined by forming corrugations in the substrate and disposing a uniform catalytically-active thermal barrier coating over the corrugated substrate.

Abstract: An active vibration control subassembly for a structure (such as a jet engine duct or a washing machine panel) undergoing bending vibrations caused by a source (such as the clothes agitator of the washing machine) independent of the subassembly. A piezoceramic actuator plate is vibratable by an applied electric AC signal. The plate is connected to the structure such that vibrations in the plate induced by the AC signal cause canceling bending vibrations in the structure and such that the plate is compressively pre-stressed along the structure when the structure is free of any bending vibrations. The compressive prestressing increases the amplitude of the canceling bending vibrations before the critical tensile stress level of the plate is reached. Preferably, a positive electric DC bias is also applied to the plate in its poling direction.

Abstract: An improved two-dimensional ultrasonic transducer array is provided by forming a plurality of elongated transducer strips each including a central body of piezoelectric material having mounted thereon a conducting inner matching layer and outer matching layer, a conducting inner backing layer and a nonconducting lossy outer backing layer, depositing a conducting film on the outer surface and one side surface of the outer matching layer and into electrical contact with the conducting backing layer of each strip and depositing a plurality of conducting films in space relation to one another on the back surface and one side surface of the lossy backing layer and into electrical contact with the conducting backing layer to provide an electric circuit to the front and back faces of the piezoelectric layer.

Abstract: An electric motor assembly. An air-ventilated electric motor includes a motor housing having a cooling-air inlet and a cooling-air outlet. An outlet muffler array is located outside, and spaced apart from, the motor housing and includes two or more outlet mufflers each having a fluid entrance and a fluid exit. An outlet connecting duct has a first end connected to the cooling-air outlet of the motor housing and has a second end connected in parallel to the fluid entrances of each of the outlet mufflers. The assembly may also include an inlet muffler array and an inlet connecting duct.

Abstract: An open magnetic resonance imaging (MRI) magnet having two generally toroidal-shaped superconductive coil assemblies spaced apart by generally spaced-apart and generally parallel inter-coil-assembly posts. Each coil assembly has associated with it a generally annular-shaped superconductive shielding assembly and at least two spaced-apart assembly posts each having one end attached to the coil assembly and another end attached to the shielding assembly The shielding coil within the shielding assembly has an inner diameter greater than the outer diameter of the main coil within the coil assembly. A cryocooler coldhead cools the entire magnet. Magnetic shielding is achieved while maintaining the openness of the open magnet.

Abstract: A system for finish machining an in-process part having an inaccessible interior cavity, an envelope of excess material to be machined, and a predefined minimum wall thickness includes a fixture for holding the in-process part to be finish machined. Also included is a co-ordinate measuring machine having a ball probe for measuring external co-ordinates of the in-process part and also having a sonic thickness probe for measuring wall thickness of the in-process part at various selected points on the part. A programmed digital computer is operably connected to the co-ordinate measuring machine to receive data regarding the measurements made. Stored in the computer is a model of the part which is to be machined and minimum wall thickness requirements at various points on the part. The computer is further programmed to calculate the optimal position of the final part in relation to its interior cavity such that wall thickness requirements are maximally satisfied over the total part surface.

Abstract: This invention relates to an apparatus and method for directly measuring the bottom pour flow rate from heated ceramic crucible, hearth/tundish combinations used in metals refining/processing industry, plasma arc melting process (PAM), a cold hearth process or other similar processes such as for pouring ingots. Such structures of this type generally allow the bottom pour flow rate to be accurately measured in relative real time without adversely affecting the flow while withstanding the hostile surroundings typically associate with a heated crucible, tundishes, PAM, cold hearth process or other similar processes.

Abstract: A superconductive magnet having a superconductive coil located within a thermal shield located within a vacuum enclosure. A cryocooler coldhead's first stage is in solid-conductive thermal contact with the thermal shield, and its second stage is in solid-conductive thermal contact with the superconductive coil. A magnet re-entrant support assembly includes an outer support cylinder located between the vacuum enclosure and the thermal shield and includes an inner support cylinder located between the thermal shield and the superconductive coil. The outer support cylinder's first end is rigidly connected to the vacuum enclosure, and its second end is rigidly connected to the thermal shield. The inner support cylinder's first terminus is rigidly connected to the thermal shield near the outer support cylinder's second end, and its second terminus is located longitudinally between the outer support cylinder's first and second ends and is rigidly connected to the superconductive coil.

Abstract: Computerized tomography provides three-dimensional imaging by applying cone beam energy to an object to be imaged. The energy passes through the object and is detected. The resulting cone beam data is efficiently processed to provide Radon data on polar grid points on a series of vertical planes. The Radon data is calculated by initially defining a Radon circle on each of the coaxial vertical planes. Radon derivative data is calculated at intersection points between the Radon circle and the radial lines. The values of Radon derivative data are binned according to the nearest grid point or nearest two grid points. Values are stored in the bins for each point in a particular plane until values for all of the planes have been supplied. The values for all the points are recalculated with each of a series of source positions, corresponding to the relative positioning of the source of cone beam energy and the object being imaged.

Abstract: A magnet including spaced-apart first and second pole pieces with generally opposing first and second pole faces. The first pole face has an axis extending generally towards the second pole face and has a generally circular shim tray generally coaxially aligned with the axis and attached to the first pole face. The circular shim tray has shims each with a shape of generally a trapezoid when viewed facing the first pole face. The trapezoidal shaped shims may be arranged on the circumferences of imaginary concentric circles on the circular shim trays, with trapezoids on the same circumference having generally the same trapezoidal shape and with trapezoids on different circumferences having generally different trapezoidal shapes, to provide a smoother magnetic field to better reduce 3D (three-dimensional) magnetic field inhomogeneity.

Abstract: A cooling system for a superconductive magnet. A dewar, located outside the magnet, includes a vacuum jacket hermetically connected to the magnet's vacuum enclosure and includes liquid helium located within the vacuum jacket. A thermal busbar is located within and spaced apart from the hermetically connected vacuum jacket and vacuum enclosure. The thermal busbar has a first end located within the vacuum jacket and a second end located within the vacuum enclosure and in thermal contact with the magnet's superconductive coil. A cryocooler coldhead, located outside the vacuum enclosure, has a housing located outside the vacuum jacket and has a cold stage extending from the housing to inside the vacuum jacket to re-liquefy any helium boiled-off in cooling the magnet 10.

Abstract: This invention relates to an apparatus and method for providing passive shimming for a superconducting magnet of the type that has a relatively small imaging volume. Such structures of this type, generally, provide the proper amount of passive shimming for a relatively small imaging volume.

Abstract: Lean direct injection is used in a gas turbine combustor to reduce NO.sub.x emissions. The combustor has a multi-hole perforated plate disposed at the head end of the combustion chamber. The plate has a plurality of independent fuel jets and air jets for separately injecting fuel and air, respectively, into the combustion chamber in amounts which produce a lean fuel-air equivalence ratio. The perforated plate permits the fuel and air to be injected separately without any mixing outside of the combustion chamber. Fuel is delivered to the fuel jets by a fuel manifold having a branch connected to each one of the fuel jets. Air can be delivered to the air jets by an air plenum chamber located upstream of the perforated plate and in fluid communication with the air jets.

Abstract: An open magnet having two magnet assemblies arranged in a spaced-apart, parallel relationship to define a working space therebetween is provided for magnetic resonance imaging. Each assembly has an annular superconductive coil and a ferromagnetic field enhancer encircled by the superconductive coil. The field enhancers are substantially cylindrical ferromagnetic pole pieces which are encircled by a respective one of the superconductive coils. The magnet assemblies are attached to a C-shaped support frame which is rotatively mounted to a pedestal member. The frame can thus be rotated between vertical and horizontal imaging positions. The field enhancers are shaped so as to maximize homogeneity in the imaging volume while keeping their weight and volume to a minimum. The specific shape of the field enhancers is determined with a nonlinear optimization design method.

Abstract: A fuel with or without fuel bound nitrogen (FBN) is burned in a high pressure machine (20 atm) comprising fuel and air compressors, combustor and turbine at an ER of about 2-3 and temperature below the threshold for creating thermal NO.sub.x. Prompt and FBN NO.sub.x are avoided due to the rich mixture, having a dearth of O and OH, producing CO and H.sub.2 and little CH. The turbine cools the products to reduce their temperature. The cooled products are mixed with the remaining air and burned at a temperature below the thermal NO.sub.2 threshold temperature at an ER of about 0.6. Commercial stand alone machines can be used for the rich and for the lean combustors wherein air and fuel are supplied to the rich combustor and only air and the cooled combustion products of the rich machine are supplied to the lean combustor.