id: 05953700 dt: a an: 05953700 au: Dai, Xuewu; Breikin, Timofei; Wang, Hong; Kulikov, Gennady; Arkov, Valentin ti: Modeling a complex aero-engine using reduced order models. so: Mohammadpour, Javad (ed.) et al., Efficient modeling and control of large-scale systems. New York, NY: Springer (ISBN 978-1-4419-5756-6/hbk; 978-1-4419-5757-3/ebook). 89-111 (2010). py: 2010 pu: New York, NY: Springer la: EN cc: ut: model identification algorithm; data driven reduced order modeling; dynamic nonlinear least squares (DNLS) identification; Hessian approximation ci: li: doi:10.1007/978-1-4419-5757-3_4 ab: Summary: This chapter describes the modeling phase of the engine model-based condition monitoring. The aim is to find a fast OE model identification algorithm suitable for the limited on-board computation facilities of the on-board condition monitoring system. The chapter is organized as follows. Section 2 provides an introduction to gas turbine systems. Section 3 discusses the performance criterion and structure selection during data driven reduced order modeling. Section 4 defines the objective function for OE modeling and presents the development of DNLS (Dynamic Nonlinear Least Squares) identification algorithm. In order to accelerate the identification speed, two techniques are employed. The first one is iterative calculation of the gradient (the Jacobian). The dependency within output errors is taken into account by adding an weighted sum of past gradients to the current Jacobian matrix. Secondly, Hessian approximation is used. In order to further accelerate the convergence speed at a relatively low computation cost, the second order Hessian matrix is used and approximated by the first order information. Finally, the potential of the proposed DNLS for reduced order modeling of a gas turbine engine is illustrated in Sect. 5. Data gathered at an aero engine test-bed serves as test vehicle to demonstrate the improvements in convergence speed and the reduction of computation cost. rv: