Onboard real time modeling of aircraft engines with Hammerstein-Wiener representation

An identification-based approach for aircraft engine modeling using the nonlinear HammersteinWiener representation was proposed.Hammerstein-Wiener modeling for both limited flight envelope and extended flight envelope was investigated.Simulation shows that the resulting model can be valid over 10%variation of rotational speed of the engine,compared with those linear models that are only valid over 3%—5%change of rotational speed.It is further demonstrated that the proposed method can be utilized over large envelope up to 20% variation of rotational speed of the engine.The fundamental idea is to use nonlinear models to extend the feasible/valid region rather than those linear models.This may consequently simplify the switching logic in the onboard digital control units.This is often overlooked in aircraft engine control community,but has been emphasized in the research.

Real-time Life-cycle Modular Design Method Based on Game Theory for Jack-up

To study an entity the entire jack-up performs as a total system with close interdependency and high level of integration of a myriad of subsystems supporting each individual function. All subsystems should be arranged in regular geometric space with clear regional division according to their respective functions. The ＂building block＂ such as arrangement makes it feasible to apply modular design method while the integration and conflicts among subsystems offer an arena for game theoretic analysis. All the contradictions between subsystems should be resolved bye the designer. Here we present a game theoretic analysis methodology, which based on the basic principles of game theory, through the establishment of matrix-mode game models to describe and analyze engineering design tasks. By using this method the optimization process in various fields of expertise can be effectively coordinated and controlled, and the parallel design patterns can be achieved to some extent. Taking account of the impact of commercial or technical activities in platform＇s life cycle, time line is considered in the early stage of design process which provides more convenience for efficient upgrade and reconfiguration. Some second-hand three-legged jack-up upgrade design process is used as an example to illustrate the utility of the method.

The CMEKF Method for Sub-Sea Pipeline Monitoring and Leak Detection

A practical approach is discussed for sub-sea pipeline monitoring and leak detection based on the real time transient model . The characteristic method of transient simulation is coupled with the Extended Kalman Filter to estimate the system state where the only observed data are inlet and outlet flow rate and pressure. Because EKF has a time variant track under the non-stationary stochastic process with additive Gaussian noise, the high sensitivity of RTTM to non-stationary operating condition is reduced. A leak location recursion estimation formula is presented based on the real time observed data. The results of 27 groups of test data indicate that the procedure presented is sensitive to a wide range of detectable leak sizes and has a low average relative error of leak location .