Sparse Nonlinear MIMO Filtering and Identification

In this chapter system identification algorithms for sparse nonlinear multi input multi output (MIMO) systems are developed. These algorithms are potentially useful in a variety of application areas including digital transmission systems incorporating power amplifier(s) along with multiple antennas, cognitive processing, adaptive control of nonlinear multivariable systems, and multivariable biological systems. Sparsity is a key constraint imposed on the model. The presence of sparsity is often dictated by physical considerations as in wireless fading channel-estimation. In other cases it appears as a pragmatic modelling approach that seeks to cope with the curse of dimensionality, particularly acute in nonlinear systems like Volterra type series. Three dentification approaches are discussed: conventional identification based on both input and output samples, semi–blind identification placing emphasis on minimal input resources and blind identification whereby only output samples are available plus a–priori information on input characteristics. Based on this taxonomy a variety of algorithms, existing and new, are studied and evaluated by simulation

ОЦЕНКА КАЧЕСТВА ИДЕНТИФИКАЦИИ ДИНАМИЧЕСКИХ ПАРАМЕТРОВ ПРОЦЕССА ПРОИЗВОДСТВА КАРБАМИДА

The identification of nonlinear systems using Volterra-Laguerre model is a method for estimating the dynamic coefficients of Volterra series. On base of experimental input-output data from carbamide production process, the estimation of coefficients will be using Laguerre filters and method of lest squares.Идентификация нелинейной системы с помощью модели Вольтера-Лагерра - это метод, который позволяет оценить динамические коэффициенты ряда Вольтерра, применяя свойства ортогональных функций Лагерра. На основе экспериментальных данных входа-выхода процесса производства карбамида, оцениваются коэффициенты рядов Вольтерра посредством фильтров Лагерра и метода наименьших квадратов

Ein Modell reduzierter Ordnung für die Dynamik langer flexibler Zylinder in einer Offshore-Umgebung

In this thesis the development of a reduced order model for the analysis of long flexible cylinders in an offshore environment is proposed. In particular the focus is on the modelling of the vortex induced vibrations and the aim is the development of a model capable of capturing both the in-line and cross-flow oscillations. The reduced order model is identified starting from the results of a high fidelity solver developed coupling together a finite element solver with a computational fluid dynamics finite volume solver. The high fidelity analyses are conducted on a reduced domain size representing a small section of the long cylinder, which is nevertheless, already flexible. The section is forced using a motion which matches the expected motion in full scale, and the results are used for the system-parameter identification of the reduced order model. Several different models are analysed and their results are compared and discussed. The reduced order model is identified by using a system and parameter identification approach. The final proposed model consists in the combination of a forced van der Pol oscillator, to model the cross-flow forces, and a linear state-space model, to model the in-line forces. The model developed in such a way is applied to study a full scale flexible model and the results are validated by using experiments conducted inside a towing tank. Finally the parameter identification, focusing on the van der Pol model is repeated in a probabilistic setting. In particular, the applicability of the ensemble Kalman filter for the parameter estimation of the van der Pol oscillator is discussed and analysed.In dieser Dissertationsschrift wird die Entwicklung eines reduzierten Modells (Reduced Order Model) zur Analyse von langen, flexiblen Zylindern im Hochseebereich vorgeschlagen. Der besondere Fokus liegt auf der Modellierung der durch Wirbel hervorgerufenen Vibrationen, und das Ziel ist die Entwicklung eines Modells, das in der Lage ist, sowohl Schwingungen in Richtung der Strömung als auch quer dazu abzubilden. Das reduzierte Modell wird identifiziert mit den Ergebnissen eines hochgenauen Lösers, der durch die Kopplung eines Finite Elemente-Lösers mit einem Finiten Volumen-Lösers entwickelt wurde. Die hochgenaue Analyse wird auf einem beschränkten Gebiet durchgeführt, welches einen kleinen Abschnitt eines langen Zylinders repräsentiert, der dennoch flexibel ist. Dem Zylinderabschnitt wird an den Enden eine Bewegung aufgezwungen, die der erwarteten Bewegung in der echten Größenordnung entspricht, und die Ergebnisse werden zur Systemparameteridentifizierung des reduzierten Modells genutzt. Verschiedene reduzierte Modelle werden analysiert und ihre Resultate verglichen und diskutiert. Das reduzierte Modell wird durch eine System- und eine Parameteridentifizierung bestimmt. Das schließlich vorgeschlagene Modell besteht aus der Kombination eines erzwungenen van der Pol-Oszillators, womit die Querstromkräfte modelliert werden, und einem linearen Zustandsraummodell, um die Kräfte in Strömungsrichtung zu modellieren. Das so entwickelte Modell wird auf ein flexibles Modell für die echte Größenordnung angewendet, und die Ergebnisse werden mit Experimenten in einem Schlepptank validiert. Schließlich wird die Parameteridentifizierung mit Hauptaugenmerk auf des van der Pol-Modell in probabilistischer Formulierung durchgeführt. Im Speziellen wird die Anwendbarkeit des Ensemble Kalman Filters zur Parameterschätzung des van der Pol-Oszillators diskutiert und analysiert

Radio Communications

In the last decades the restless evolution of information and communication technologies (ICT) brought to a deep transformation of our habits. The growth of the Internet and the advances in hardware and software implementations modified our way to communicate and to share information. In this book, an overview of the major issues faced today by researchers in the field of radio communications is given through 35 high quality chapters written by specialists working in universities and research centers all over the world. Various aspects will be deeply discussed: channel modeling, beamforming, multiple antennas, cooperative networks, opportunistic scheduling, advanced admission control, handover management, systems performance assessment, routing issues in mobility conditions, localization, web security. Advanced techniques for the radio resource management will be discussed both in single and multiple radio technologies; either in infrastructure, mesh or ad hoc networks

Spectrum analysis of LTI continuous-time systems with constant delays: A literature overview of some recent results

In recent decades, increasingly intensive research attention has been given to dynamical systems containing delays and those affected by the after-effect phenomenon. Such research covers a wide range of human activities and the solutions of related engineering problems often require interdisciplinary cooperation. The knowledge of the spectrum of these so-called time-delay systems (TDSs) is very crucial for the analysis of their dynamical properties, especially stability, periodicity, and dumping effect. A great volume of mathematical methods and techniques to analyze the spectrum of the TDSs have been developed and further applied in the most recent times. Although a broad family of nonlinear, stochastic, sampled-data, time-variant or time-varying-delay systems has been considered, the study of the most fundamental continuous linear time-invariant (LTI) TDSs with fixed delays is still the dominant research direction with ever-increasing new results and novel applications. This paper is primarily aimed at a (systematic) literature overview of recent (mostly published between 2013 to 2017) advances regarding the spectrum analysis of the LTI-TDSs. Specifically, a total of 137 collected articles-which are most closely related to the research area-are eventually reviewed. There are two main objectives of this review paper: First, to provide the reader with a detailed literature survey on the selected recent results on the topic and Second, to suggest possible future research directions to be tackled by scientists and engineers in the field. © 2013 IEEE.MSMT-7778/2014, FEDER, European Regional Development Fund; LO1303, FEDER, European Regional Development Fund; CZ.1.05/2.1.00/19.0376, FEDER, European Regional Development FundEuropean Regional Development Fund through the Project CEBIA-Tech Instrumentation [CZ.1.05/2.1.00/19.0376]; National Sustainability Program Project [LO1303 (MSMT-7778/2014)