In this paper, a bank of Kalman filters is applied to aircraft gas turbine engine sensor and actuator fault detection and isolation (FDI) in conjunction with the detection of component faults. This approach uses multiple Kalman filters, each of which is designed for detecting a specific sensor or actuator fault. In the event that a fault does occur, all filters except the one using the correct hypothesis will produce large estimation errors, thereby isolating the specific fault. In the meantime, a set of parameters that indicate engine component performance is estimated for the detection of abrupt degradation. The proposed FDI approach is applied to a nonlinear engine simulation at nominal and aged conditions, and the evaluation results for various engine faults at cruise operating conditions are given. The ability of the proposed approach to reliably detect and isolate sensor and actuator faults is demonstrated.
The ␥ /␥ Ј interfacial dislocation networks in several creep-ruptured superalloys were analyzed. It was found that the morphologies of dislocation networks differ slightly from each other in these alloys. The fourth-generation superalloy has finer dislocation networks and keeps a relatively stable state. Comparatively, the interfacial dislocations in the third-generation superalloy show obvious curved features associated with possible climb or slip. These interfacial dislocation characteristics can be correlated with the creep behavior of these superalloys. The mechanisms of evolution of the interfacial dislocation networks were discussed.
This paper presents an inter-comparison of rainfall parameters (median volume diameter and rain rate) using C-band polarimetric radar, a 2D-video disdrometer and a 400 MHz profiler for the Baiu front event of 8-9 June 2005 in Okinawa, Japan. These instruments are part of the Okinawa Sub-Tropical Environment Remote Sensing Center, operated by the National Institute of Information and Communications Technology (NICT). The 2D-video disdrometer is used to derive the mean axis ratio of raindrops versus drop diameter, as well as the drop size distribution for the Baiu event. The data are then used to simulate various relations between polarimetric scattering parameters such as: specific attenuation ðA h Þ, and specific differential attenuation ðA dp Þ, versus specific differential phase ðK dp Þ which are required to correct the measured reflectivity at horizontal polarization ðZ h Þ, and the differential reflectivity ðZ dr Þ for rain attenuation. The 2D-video disdrometer data are also used to arrive at retrieval formulas for median volume diameter ðD o Þ from radar Z dr , and rain rate from radar K dp .The These inter-comparisons demonstrate the accuracy of C-band polarimetric radar to retrieve important rainfall parameters, as well as the accurate correction for rain attenuation using differential propagation phase.
Based on a fourth generation single crystal (SC) superalloy, TMS-138, we designed new SC alloys that contain higher amount of refractory elements, Nb, Ta, Mo, or Re, for strengthening. The Ru content was also increased to improve the phase stability. The creep strength and microstructure of these alloys were examined and compared with those of the base alloy TMS-138 and a third generation SC superalloy, CMSX-10K. As predicted by our alloy design program, TMS-162 (Mo and Ru addition) and TMS-173 (Re and Ru addition) exhibited excellent creep properties. Their times to 1% creep deformation at 1100 C/137MPa were about 2.5 times as long as that of TMS-138 and 5 times as long as that of CMSX-10K. The temperature capability of TMS-162 has reached a project target of 1100 C under stress at 137MPa and a creep rupture life as long as 1000 h, which is the highest ever reported.
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