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Perturbed Systems (perturbed + system)
Selected AbstractsSpectral Theory for Perturbed SystemsGAMM - MITTEILUNGEN, Issue 1 2009Fritz Colonius Abstract This paper presents an overview of topological, smooth, and control techniques for dynamical systems and their interrelations for the study of perturbed systems. We concentrate on spectral analysis via linearization of systems. Emphasis is placed on parameter dependent perturbed systems and on a comparison of the Markovian and the dynamical structure of systems with Markov diffusion perturbation process. A number of applications is provided (© 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Harmonic Balance, Melnikov method and nonlinear oscillators under resonant perturbationINTERNATIONAL JOURNAL OF CIRCUIT THEORY AND APPLICATIONS, Issue 3 2008Michele Bonnin Abstract The subharmonic Melnikov's method is a classical tool for the analysis of subharmonic orbits in weakly perturbed nonlinear oscillators, but its application requires the availability of an analytical expression for the periodic trajectories of the unperturbed system. On the other hand, spectral techniques, like the Harmonic Balance, have been widely applied to the analysis and design of nonlinear oscillators. In this manuscript, we show that bifurcations of subharmonic orbits in perturbed systems can be easily detected computing the Melnikov's integral over the Harmonic Balance approximation of the unperturbed orbits. The proposed method significantly extends the applicability of the Melnikov's method since the orbits of any nonlinear oscillator can be easily detected by the Harmonic Balance technique, and the integrability of the unperturbed equations is not required anymore. As examples, several case studies are presented, the results obtained are confirmed by extensive numerical experiments. Copyright © 2007 John Wiley & Sons, Ltd. [source] Numerical computation of cross-coupled algebraic Riccati equations related to H2/H, control problem for singularly perturbed systemsINTERNATIONAL JOURNAL OF ROBUST AND NONLINEAR CONTROL, Issue 8 2004Hiroaki Mukaidani Abstract In this paper, we present a numerical algorithm to the cross-coupled algebraic Riccati equations(CARE) related to H2/H, control problems for singularly perturbed systems (SPS) by means of Newton's method. The resulting algorithm can be widely used to solve Nash game problems and robust control problems because the CARE is solvable even if the quadratic term has an indefinite sign. We prove that the resulting iterative algorithm has the property of the quadratic convergence. Using the solution of the CARE, we construct the high-order approximate H2/H, controller. Copyright © 2004 John Wiley & Sons, Ltd. [source] Habitat selection and sampling design for ecological assessment of heterogeneous ponds using macroinvertebratesAQUATIC CONSERVATION: MARINE AND FRESHWATER ECOSYSTEMS, Issue 7 2009Cristina Trigal-Domínguez Abstract 1.Habitat heterogeneity has many implications in ecological assessment studies. On one hand it provides varying niches for organisms, increasing diversity. On the other hand, the inherent spatial variability of structurally complex systems may overlap with ecological condition making it difficult to disentangle the effects of perturbation. This study investigated the combined and single effects of habitat and pond condition on the macroinvertebrate assemblages of 35 ponds located in north-west Spain and spanning a range of water quality and habitat characteristics. 2.Macroinvertebrate communities and several environmental variables were sampled in the summer of 2004 or 2003. Samples were collected from four dominant habitats (vegetated shores, shores without vegetation, submerged vegetation, bare sediments) following a time-limited sampling. Non-metric multidimensional scaling and two-way crossed ANOSIM were used to investigate the taxonomic and functional differences in macroinvertebrate assemblage structure among habitats (four types) and pond conditions (optimal, good, moderate, poor, very poor). To investigate the individual and combined effects of pond condition and habitat on several diversity measures GLM models were used. In addition, the accuracy of two sampling designs , stratified and multihabitat , was compared using the CVs of seven macroinvertebrate attributes. 3.Results showed that macroinvertebrate communities differed significantly, albeit weakly, among habitat types and pond condition categories. In particular, the abundance of several Chironomidae genera, rarefied richness and Shannon index decreased both in perturbed systems and bare sediments, whereas no marked differences occurred between shores and submerged vegetation. 4.We suggest that a multihabitat approach together with the use of community attributes not (or slightly) affected by habitat type will provide more comparable results across ponds than a stratified approach or observation of the whole community, especially in ponds where degradation leads to habitat loss.Copyright © 2009 John Wiley & Sons, Ltd. [source] ROBUST CONTROL FOR A CLASS OF UNCERTAIN STATE-DELAYED SINGULARLY PERTURBED SYSTEMSASIAN JOURNAL OF CONTROL, Issue 2 2005H.R. Karimi ABSTRACT This paper considers the problem of robust control for a class of uncertain state-delayed singularly perturbed systems with norm-bounded nonlinear uncertainties. The system under consideration involves state time-delay and norm-bounded nonlinear uncertainties in the slow state variable. It is shown that the state feedback gain matrices can be determined to guarantee the stability of the closed-loop system for all , , (0, ,00) and independently of the time-delay. Based on this key result and some standard Riccati inequality approaches for robust control of singularly perturbed systems, a constructive design procedure is developed. We present an illustrative example to demonstrate the applicability of the proposed design approach. [source] | ||||||||||