摘要:
Fast reconstruction methods are provided for 3D time-of-flight (TOF) positron emission tomography (PET), based on 2D data re-binning. Starting from pre-corrected 3D TOF data, a re-binning algorithm estimates for each transaxial slice the 2D TOF sinogram. The re-binned sinograms can then be reconstructed using any algorithm for 2D TOF reconstruction. A TOF-FORE (Fourier re-binning of TOF data) algorithm is provided as an approximate re-binning algorithm obtained by extending the Fourier re-binning method for non-TOF data. In addition, two partial differential equations are identified that must be satisfied by consistent 3D TOF data, and are used to derive exact re-binning algorithms and to characterize the degree of the approximation in TOF-FORE. Numerical simulations demonstrate that TOF-FORE is more accurate than two different TOF extensions of the single-slice re-binning method, and suggest that TOF-FORE will be a valuable tool for practical TOF PET in the range of axial apertures and time resolutions typical of current scanners.
摘要:
An apparatus, system, and method for determining the maximum supported degree of parallel sort operations in a multi-processor computing environment. An allocation module allocates a minimum number of sort files to a sort operation for each data source that participates in the parallel sort. The allocation module attempts to allocate sort files of one-half the sort operation data source file size, and iteratively reduces the sort file size requests in response to determinations that sort files of the requested size are not available. After allocation, a parallel operation module determines whether there is sufficient virtual storage to execute the sort operations in parallel. If there is not, the parallel operations module collapses the two smallest sort operations, thereby reducing the degree of parallelism by one, and repeats the request. The parallel operation module repeats the process until the sorts are executed or the process fails for lack of virtual storage.
摘要:
Emission contamination data are collected in a shifted mock scan simultaneous with the collection of transmission data during a transmission scan of a patient with a collimated gamma point source, the transmission data are corrected with the emission contamination data, and the corrected transmission data are used for attenuation correction of emission data for reconstruction of an emission image of the patient. In a preferred implementation, when the point source is at a particular axial location and illuminates an axial beamwidth of “Fz” over the gamma detector, emission contamination data are collected from the gamma detector over an axial separated region “Fz′” having about the same axial extent but axially displaced by about half of the axial field of view (FOV).
摘要:
A transmission oil sump comprises a main oil compartment, in which a suction line of an oil pump is located, and a secondary oil compartment. The secondary oil compartment is in fluid communication with the main oil compartment via an opening. To prevent the introduction of air during rapid acceleration, cornering at high speeds and/or rapid deceleration of the vehicle, a barrier closes the opening to prevent the flow of oil out of the main oil compartment into the secondary oil compartment so that the oil level, required for the oil pump in the main compartment, remains adequately high. When not closed, the opening of the secondary oil compartment is open to ensure oil flow from the secondary oil compartment to the main oil compartment. The secondary oil compartments is arranged so as to collect oil that leaks from transmission components.
摘要:
A method of hydroprocessing a heavy hydrocarbon feedstock using a hydroprocessing catalyst having specific properties making it effective in the hydroconversion of at least a portion of the heavy hydrocarbon feedstock to lighter hydrocarbons. The hydroprocessing catalyst comprises a Group VIB metal component (e.g., Cr, Mo, and W), a Group VIII metal component (e.g., Ni and Co) and, optionally, a potassium metal component that are supported on a support material comprising alumina. The alumina has novel physical properties that, in combination with the catalytic components, provide for the hydroprocessing catalyst. The hydroprocessing catalyst is particularly effective in the conversion of the heavy hydrocarbon feedstock. The alumina is characterized as having a high pore volume and a high surface area with a large proportion of the pore volume being present in the pores within a narrow pore diameter distribution about a narrowly defined range of median pore diameters. The support material preferably does not contain more than a small concentration of silica. The alumina component is preferably made by a specific method that provides for an alumina having the specific physical properties required for the hydroprocessing catalyst.
摘要:
A countershaft-type dual clutch transmission for a vehicle has two clutches having input sides connected to a driveshaft (AN) and output sides connected respectively to one of two transmission input shafts arranged coaxial to a mainshaft axis. A sub-transmission is associated in each instance with the transmission input shafts, at least two countershafts, a plurality of gear planes to which are assigned gear ratio steps, and at least one output shaft which can be connected to the sub-transmissions via an output gear plane. Only six gear planes with at least nine assigned gear ratio steps can be realized via only four double shift elements and at least one single shift element. Each countershaft can be coupled with four gear ratio steps via double shift elements, and one of the transmission input shafts can be coupled with a gear ratio step via a single shift element.
摘要:
The invention concerns a fired refractory product based on refractory grains and binder, and process for the production thereof.The refractory product comprises a charge of refractory grains belonging to the group comprising carbonaceous products such as anthracite, natural graphite, artificial graphite, amorphous carbon, coke, refractory compounds known as RHM such as silicon carbide and refractory oxides such as alumina, corundum, magnesia, silica and chromium oxide, taken separately, in mixture or in combination; said grains are secured together by a cement based on a coked carbonaceous product and metal silicon in powder form; and the final proportion of metal silicon is from 1 to 15.8% and preferably from 3 to 10.5%.The product is intended for the manufacture of side linings for tanks for the production of aluminum by igneous electrolysis, and linings for blast furnaces and electric furnaces for electrometallurgy operations.
摘要:
A bearing arrangement for mounting a gear bolt (1) as the bearing axle for a gearwheel (2) in a transmission housing. The gear bolt (1) is held in the transmission housing by only a single component in the form of an intermediate plate (3).
摘要:
A countershaft-type dual clutch transmission for a vehicle has two clutches having input sides connected to a driveshaft (AN) and output sides connected respectively to one of two transmission input shafts arranged coaxial to a mainshaft axis. A sub-transmission is associated in each instance with the transmission input shafts, at least two countershafts, a plurality of gear planes to which are assigned gear ratio steps, and at least one output shaft which can be connected to the sub-transmissions via an output gear plane. Only six gear planes with at least nine assigned gear ratio steps can be realized via only four double shift elements and at least one single shift element. Each countershaft can be coupled with four gear ratio steps via double shift elements, and one of the transmission input shafts can be coupled with a gear ratio step via a single shift element.
摘要:
A transmission oil sump comprises a main oil compartment, in which a suction line of an oil pump is located, and a secondary oil compartment. The secondary oil compartment is in fluid communication with the main oil compartment via an opening. To prevent the introduction of air during rapid acceleration, cornering at high speeds and/or rapid deceleration of the vehicle, a barrier closes the opening to prevent the flow of oil out of the main oil compartment into the secondary oil compartment so that the oil level, required for the oil pump in the main compartment, remains adequately high. When not closed, the opening of the secondary oil compartment is open to ensure oil flow from the secondary oil compartment to the main oil compartment. The secondary oil compartments is arranged so as to collect oil that leaks from transmission components.