Abstract: In predicting failure of an x-ray tube in a computed tomography (CT) system, reference detector elements normally disposed on each end of the detector, receive x-rays directly from the x-ray tube. In accordance with the invention, the output values of the reference detector elements are utilized by a tube condition prediction algorithm to predict a failure in the x-ray tube of the CT system. The tube condition prediction algorithm utilizes at least one model of the CT system and at least one prediction routine, which typically is a Kalman filter, to generate the prediction. The prediction routine uses the model to analyze the output values of the reference detector elements in order to determine the condition of the x-ray tube and predict future performance of the x-ray tube.

Abstract: A turbine assembly includes a plurality of rotor blades comprising a root portion, an airfoil having a pressure sidewall and a suction sidewall, and a top portion having a cap. An outer shroud is concentrically disposed about said rotor blades, said shroud in combination with said tip portions defining a clearance gap. At least one circumferential shroud leakage discourager is disposed within the shroud. The leakage discourager(s) increase the flow resistance and thus reduce the flow of hot gas flow leakage for a given pressure differential across the clearance gap to improve overall turbine efficiency.

Abstract: An imager includes a substrate, a light-sensitive imaging array on the substrate, a scintillator over the array, and a cover over the scintillator sealed to the substrate. An edge of the array is situated close to an edge of the substrate relative to other edges of the array and substrate. A U-shaped end cap is sealed to and covers an edge of the cover, the edge of the substrate and a portion of each of the cover and substrate inward from their respective edges.

Abstract: In one embodiment, the present invention is a method for reconstructing at least one image representative of an object. This embodiment includes steps of: helically scanning the object with a multislice computed tomographic imaging system to acquire data representative of a plurality of computed tomographic image slices of an object including measurement data representative of conjugate rays; performing a minimum width helical interpolation of the acquired data to determine conjugate ray weights; increasing interpolation width when a sum of the conjugate ray weights is less than a threshold value; and filtering and backprojecting data to produce at least one image representative of the object. The filtering and backprojecting step includes weighting interpolated measurement data representative of conjugate rays using the increased interpolation width.

Abstract: A medical imaging system includes a workstation for receiving operator inputs that prescribe a scan and a plurality of servers which control the acquisition of image data and the reconstruction of prescribed images. The workstation is programmed in Java™ to produce scan descriptions that are downloaded to the servers prior to run time using a serialization mechanism.

Abstract: A Silicon carbide-silicon matrix composite having improved oxidation resistance at high temperatures in dry or water-containing environments is provided. A method is given for sealing matrix cracks in situ in melt infiltrated silicon carbide-silicon matrix composites. The composite cracks are sealed by the addition of various additives, such as boron compounds, into the melt infiltrated silicon carbide-silicon matrix.

Abstract: A method and an apparatus for dynamically optimizing the frame rate as a function of an estimate of the target motion. First, the target motion is estimated, and then this estimate is used to control the number of firings per frame and/or the degree of frame-averaging. Preferably, the motion of the target is estimated by measuring pixel brightness variations on a frame-to-frame, region-to-region or line-to-line basis. Then the degree of frame-averaging is adjusted as a function of the motion estimate. Alternatively, target motion can be estimated by calculating the Doppler signal. Other imaging parameters, such as number of transmit firings per frame, size of the transmit aperture, and transmit excitation frequency, can be adjusted as a function of estimated target motion.

Abstract: The appliance comprises a container for receiving the soiled articles, a circulation pump for distributing a hot liquid to the container, a drain positioned in the container and connected to the pump for emptying the liquid from the container upon completion of a cycle and a hydroclone connected to the drain and the pump, for removing soil from the liquid such that about ninety percent (90%) of the liquid distributed to the container during one cycle can be utilized during at least one subsequent cycle.

Abstract: One embodiment of the present invention is a method for imaging an object using a multi-slice computed tomography (CT) imaging system having a radiation source and a detector, the detector having a plurality of detector rows configured to acquire projection data from a scanned object between the radiation source and the detector, wherein each of the detector rows is perpendicular to and has a thickness in a z-direction. The method includes steps of collimating a radiation beam from the radiation source into a plurality of separate beam portions transverse to the z-direction so that the separate beam portions pass through the object and impinge on the detector rows; scanning the object using the plurality of separate beam portions to acquire projection data; and reconstructing an image of the object utilizing the acquired projection data.

Abstract: A hybrid combustor, for providing stable high and low levels of operation while minimizing emissions of NOx, CO, and UHCs, includes a casing having a chamber, a catalytic combustor disposed in the chamber, and a non-premixed combustor disposed in the chamber. The hybrid combustor may comprise a fuel nozzle comprising a casing having a chamber, and a body supportable in the chamber to define a passageway between the body and the casing. The passageway has an inlet for receiving a stream of air and an outlet for discharging a stream of fuel and air, and the body includes a tapering downstream portion. Desirably, flow separation of the fuel and air mixture from the body (i.e., recirculation of the fuel and air mixture in the passageway and/or chamber) is inhibited whereby a generally uniform fuel and air mixture is provided.

Abstract: In one embodiment, the present invention is a method for reconstructing a computed tomographic image of an object that includes steps of: helically scanning an object with a multislice CT imaging system to collect projection data; identifying a center view of the collected projection data; performing an operation selected from the group of helical interpolation and helical extrapolation on the collected projection data to produce super-views of the object; weighting an angular range of the super-views with normalized helical weights, the normalized helical weights being dependent upon whether interpolation or extrapolation was performed; and backprojecting the weighted super-views to produce a reconstricted image of the object.

Abstract: A method of preparing cellular pellets from a prepolymer comprising a blowing agent, the method comprising the steps of: a) extruding the prepolymer through a die, the die maintained at conditions such that the blowing agent remains in the condensed phase in the prepolymer prior to emerging from the die, and b) upon emergence of the prepolymer through the die, substantially simultaneously cooling the prepolymer by contacting the prepolymer with a cooling agent and cutting the prepolymer; the conditions outside the die being maintained such that the blowing agent vaporizes in the prepolymer to form pores.

Abstract: A method for rapidly processing multi-slice helical fan beam CT imaging data to generate tomographic images, the method including processing the fan beam helical data to generate parallel constant-Z projections proximate an image plane, filtering the parallel constant-Z projections and mathematically combining the filtered parallel constant-Z projections as a function of the spatial relationship between the imaging plane and the constant-Z projections to generate at least one image.

Abstract: An MRI system acquires NMR signals and digitizes them at a fixed sample rate. A lower, prescribed sample rate is obtained by fractionally decimating the sampled NMR signals. Fractional decimation is achieved by a combination of zeropadding the sampled NMR signal in the frequency domain and decimating the sampled NMR signal in the time domain.

Abstract: An article includes a substrate formed of a superalloy, a silicon-based ceramic material and a thermally stable silicon diffusion barrier layer. The thermally stable diffusion barrier layer is intermediate to the substrate and ceramic material and prevents diffusion of silicon or carbon into the substrate. The diffusion barrier coating is any coating that is thermally stable and that prevents diffusion of silicon or carbon across a ceramic material:superalloy interface. In a method of forming an article, a superalloy substrate is formed, a thermally stable diffusion barrier layer is applied onto the substrate and a silicon-based ceramic material is supported by the barrier layer coated substrate. The diffusion barrier layer substantially prevents diffusion of silicon from the ceramic material into the superalloy substrate.

Abstract: In one aspect, the present invention is a method for filtering projection data of a computed tomographic scan of an object. The method includes steps of: acquiring projection data representing a tilted, helical scan of an object; zero padding the acquired projection data; determining a Fourier transform of the zero padded projection data; determining a product of the Fourier transform of the zero padded projection data, a ramp function, and a phase shift function; and determining an inverse Fourier transform of the multiplied, transformed projection data as filtered projection data. The above-described method provides filtered data that produces compensated tilted, helically scanned CT images having significantly better spatial resolution than those methods employing a high frequency kernel boost.

Abstract: A method of depositing a thin membrane so that it conforms to an irregular shaped surface of a scintillator includes the steps of aligning the membrane in a desired position with respect to the irregular surface so that the membrane is in contact with at least some protruding portions of the scintillator, and drawing the membrane down over the irregular surface so that the membrane is conformingly disposed around substantially all protrusions without deforming or bending the needle-like protrusions. The membrane is drawn down by applying a substantially uniform differential pressure across the thin membrane so as to urge the membrane into conformal contact with irregular surface. An imager array fabricated with this process includes a scintillator having an irregular surface and a monolithic reflective layer disposed thereover in conformal contact with the irregular surface.

Abstract: Methods and apparatus for calibration simplification in a computed tomography (CT) system are described. In one embodiment, the CT system utilizes calibration values from a first scan type, or mode of operation, to determine calibration values for at least a second scan type. As a result, the time required to perform calibration of the CT system is reduced.

Abstract: In one embodiment of the present invention, a method is provided for analyzing performance of tracking control loop in a CT imaging system configured to position an x-ray beam using the tracking control loop. The method includes the steps of collecting control loop data over a plurality of views during scanning and of evaluating control loop data relative to the corresponding views to measure at least one imaging system characteristic. This method provides the imaging system user with data that facilitates insight into possible causes for imaging artifacts. In another embodiment, a CT imaging system is provided including a tracking control loop. The CT imaging system is configured to position an x-ray beam using the tracking control loop, collect control loop data over a plurality of views during scanning and evaluate control loop data relative to the corresponding views to measure at least one imaging system characteristic.

Abstract: One aspect of the present invention is a method for computerized tomographic (CT) imaging of an object. One embodiment of the method includes scanning an object with a CT imaging system to acquire views that include projection samples of an object; interpolating the acquired views within a selected view range to produce interpolated views; weighting the interpolated views to compensate for the interpolation; weighting the acquired views; and filtering and backprojecting the weighted, interpolated views and the weighted acquired views to generate an image of the object. View aliasing artifacts are reduced by this embodiment without using conjugate samples.