Cascade modeling of nonlinear systems

Download
index.pdf
2007
Şenalp, Erdem Türker
Show full item record
161
views
57
downloads
Modeling of nonlinear systems based on special Hammerstein forms has been considered. In Hammerstein system modeling a static nonlinearity is connected to a dynamic linearity in cascade form. Fundamental contributions of this work are: 1) Introduction of Bezier curve nonlinearity representations; 2) Introduction of B-Spline curve nonlinearity representations instead of polynomials in cascade modeling. As a result, local control in nonlinear system modeling is achieved. Thus, unexpected variations of the output can be modeled more closely. As an important demonstration case, a model is developed and named as Middle East Technical University Neural Networks and Cascade Model (METU-NN-C). Application examples are chosen by considering the Near-Earth space processes, which are important for navigation, telecommunication and many other technical applications. It is demonstrated that the models developed based on the contributions of this work are especially more accurate under disturbed conditions, which are quantified by considering Space Weather parameters. Examples include forecasting of Total Electron Content (TEC), and mapping; estimation of joint angle of simple forced pendulum; estimation of joint angles of spring loaded inverted double pendulum with forced table; identification of Van der Pol oscillator; and identification of speakers. The operation performance results of the International Reference Ionosphere (IRI-2001), METU Neural Networks (METU-NN) and METU-NN-C models are compared qualitatively and quantitatively. As a numerical example, in forecasting the TEC by using the METU-NN-C having Bezier curves in nonlinearity representation, the average absolute error is 1.11 TECu. The new cascade models are shown to be promising for system designers and operators.
Electrical engineering., Nuclear engineering.
http://etd.lib.metu.edu.tr/upload/3/12608578/index.pdf
https://hdl.handle.net/11511/17255
Graduate School of Natural and Applied Sciences, Thesis

Suggestions

Performance of bilinear time-frequency transforms in isar
Loğoğlu, Berker; Dural Ünver, Mevlüde Gülbin; Department of Electrical and Electronics Engineering (2007)
In this thesis a stepped-frequency Inverse Synthetic Aperture Radar (ISAR) is employed to develop two-dimensional range-Doppler images of a small ghter aircraft which exhibits three dimensional rotational rotation. The simulation is designed such that the target can exhibit yaw, pitch and roll motions at the same time. First, radar returns from prominent scatterers of various parts of the target are processed and displayed using conventional Fourier transform. The e ects of di erent complex motion types an...
Dense depth map estimation for object segmentation in multi-view video
Çığla, Cevahir; Alatan, Abdullah Aydın; Department of Electrical and Electronics Engineering (2007)
In this thesis, novel approaches for dense depth field estimation and object segmentation from mono, stereo and multiple views are presented. In the first stage, a novel graph-theoretic color segmentation algorithm is proposed, in which the popular Normalized Cuts 59H[6] segmentation algorithm is improved with some modifications on its graph structure. Segmentation is obtained by the recursive partitioning of the weighted graph. The simulation results for the comparison of the proposed segmentation scheme w...
Tracker-aware detection : a theoretical and an experimental study
Aslan, Murat Şamil; Saranlı, Afşar; Department of Electrical and Electronics Engineering (2009)
A promising line of research attempts to bridge the gap between detector and tracker by means of considering jointly optimal parameter settings for both of these subsystems. Along this fruitful path, this thesis study focuses on the problem of detection threshold optimization in a tracker-aware manner so that a feedback from the tracker to the detector is established to maximize the overall system performance. Special emphasis is given to the optimization schemes based on two non-simulation performance pred...
Improvements in DOA estimation by array interpolation in non-uniform linear arrays
Yaşar, Temel Kaya; Tuncer, Temel Engin; Department of Electrical and Electronics Engineering (2006)
In this thesis a new approach is proposed for non-uniform linear arrays (NLA) which employs conventional subspace methods to improve the direction of arrival (DOA) estimation performance. Uniform linear arrays (ULA) are composed of evenly spaced sensor elements located on a straight line. ULA's covariance matrix have a Vandermonde matrix structure, which is required by fast subspace DOA estimation algorithms. NLA differ from ULA only by some missing sensor elements. These missing elements cause some gaps in...
Implementation and performance evaluation of a three antenna direction finding system
Arslan, Ömer Çağrı; Tuncer, Temel Engin; Department of Electrical and Electronics Engineering (2009)
State of the art direction finding (DF) systems usually have several antennas in order to increase accuracy and robustness to certain factors. In this thesis, a three antenna DF system is built and evaluated. While more antennas give better DF performance, a three antenna system is useful for system simplicity and many of the problems in DF systems can be observed and evaluated easily. This system can be used for both azimuth and elevation direction of arrival (DOA) estimation. The system is composed of thr...
Citation Formats
E. T. Şenalp, “Cascade modeling of nonlinear systems,” Ph.D. - Doctoral Program, Middle East Technical University, 2007.
METU IIS - Integrated Information Service open@metu.edu.tr