Two-dimensional particle images provide significantly more information about particle morphology than does the measurement of a single length scale. However, approximations are still required to estimate three-dimensional particle parameters such as external surface area and volume from a two-dimensional image. Two techniques to predict surface area and volume from a two-dimensional image are examined by using images of objects of known surface area and volume. The orthographic intersection method intersects the two-dimensional images from all possible orthogonal axes. The resulting three-dimensional objects are averaged to obtain the final particle shape descriptors. The discrete revolution method first determines the major centroidal axis of the image and then rotates the silhouette about this axis. Because the silhouette is not symmetrical with respect to the major axis, the silhouette is divided into thin strips of area perpendicular to the major axis. Each of these strips is then rotated about its own centroidal axis (parallel to the major axis). Comparisons of the results of each method for specified particles provide estimates of the accuracy of each approach. The orthographic intersection and discrete revolution methods provide superior estimates of the surface area, volume, and surface area/volume ratio as compared with approaches using single length scale equivalent spheres. The method that provided the most accurate results was the discrete revolution technique.
The long-term trend in automobiles has been increasing electronics content over time. This trend is expected to continue and drives diverse functional, form factor, and reliability requirements. These requirements, in turn, are leading to changes in the package types selected and the performance specifications of the packages used for automotive electronics. Several examples will be given. This abstract covers the development of a distributed high temperature electronics demonstrator for integration with sensor elements to provide digital outputs that can be used by the FADEC (Full Authority Digital Electronic Control) system or the EHMS (Engine Health Monitoring System) on an aircraft engine. This distributed electronics demonstrator eliminates the need for the FADEC or EHMS to process the sensor signal, which will assist in making the overall system more accurate and efficient in processing only digital signals. This will offer weight savings in cables, harnesses and connector pin reduction. The design concept was to take the output from several on-engine sensors, carry out the signal conditioning, multiplexing, analogue to digital conversion and data transmission through a serial data bus. The unit has to meet the environmental requirements of DO-160 with the need to operate at 200°C, with short term operation at temperatures up to 250°C. The work undertaken has been to design an ASIC based on 1.0 μm Silicon on Insulator (SOI) device technology incorporating sensor signal conditioning electronics for sensors including resistance temperature probes, strain gauges, thermocouples, torque and frequency inputs. The ASIC contains analogue multiplexers, temperature stable voltage band-gap reference and bias circuits, ADC, BIST, core logic, DIN inputs and two parallel ARINC 429 serial databuses. The ASIC was tested and showed to be functional up to a maximum temperature of 275°C. The ASIC has been integrated with other high temperature components including voltage regulators, a crystal oscillator, precision resistors, silicon capacitors within a hermetic hybrid package. The hybrid circuit has been assembled within a stainless steel enclosure with high temperature connectors. The high temperature electronics demonstrator has been demonstrated operating from −40°C to +250°C. This work has been carried out under the EU Clean Sky HIGHTECS project with the Project being led by Turbomeca (Fr) and carried out by GE Aviation Systems (UK), GE Research – Munich (D) and Oxford University (UK).
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