Search results for "Systems Theory"
showing 10 items of 220 documents
Harmonic Balance Method and Stability of Discontinuous Systems
2019
The development of the theory of discontinuous dynamical systems and differential inclusions was not only due to research in the field of abstract mathematics but also a result of studies of particular problems in mechanics. One of the first methods, used for the analysis of dynamics in discontinuous mechanical systems, was the harmonic balance method developed in the thirties of the twentieth century. In our work, the results of analysis obtained by the method of harmonic balance, which is an approximate method, are compared with the results obtained by rigorous mathematical methods and numerical simulation.
Sense of belonging to Latvia in Latvian- and Russian-speaking residents of Latvia
2019
This study examined the sense of belonging to Latvia in Latvian-speaking and Russianspeaking residents of Latvia. The structural model involved opportunities for the fulfillment of personal goals and views of the situation in Latvia and the community as predictors of the sense of belonging at both levels of ecological systems. The Russianspeaking subsample consisted of 202 students ranging in age from 18 to 36 (65% females). The Latvian-speaking subsample involved 438 students ranging in age from 18 to 37 (67% females). The Sense of Belonging in Social Context Questionnaire and the Future of Country Questionnaire were applied. Belonging to community predicted belonging to Latvia in both gro…
Implementing an ATL model checker tool using relational algebra concepts
2014
Alternating-Time Temporal Logic (ATL) is a branching-time temporal logic that naturally describes computations of open systems. An open system interacts with its environment and its behavior depends on the state of the system as well as the behavior of the environment. ATL model-checking is a well-established technique for verifying that a formal model representing such a system satisfies a given property. In this paper we describe a new interactive model checker environment based on algebraic approach. Our tool is implemented in client-server paradigm. The client part allows an interactive construction of ATL models represented by concurrent game structures as directed multi-graphs. The se…
Redundant Picard–Fuchs System for Abelian Integrals
2001
We derive an explicit system of Picard-Fuchs differential equations satisfied by Abelian integrals of monomial forms and majorize its coefficients. A peculiar feature of this construction is that the system admitting such explicit majorants, appears only in dimension approximately two times greater than the standard Picard-Fuchs system. The result is used to obtain a partial solution to the tangential Hilbert 16th problem. We establish upper bounds for the number of zeros of arbitrary Abelian integrals on a positive distance from the critical locus. Under the additional assumption that the critical values of the Hamiltonian are distant from each other (after a proper normalization), we were…
Inferring the Relative Resilience of Alternative States
2013
Ecological systems may occur in alternative states that differ in ecological structures, functions and processes. Resilience is the measure of disturbance an ecological system can absorb before changing states. However, how the intrinsic structures and processes of systems that characterize their states affects their resilience remains unclear. We analyzed time series of phytoplankton communities at three sites in a floodplain in central Spain to assess the dominant frequencies or "temporal scales" in community dynamics and compared the patterns between a wet and a dry alternative state. The identified frequencies and cross-scale structures are expected to arise from positive feedbacks that…
Multimedia and Internet Systems : Theory and Practice
2013
Aleksander Zgrzywa, Kazimierz Choro, and Andrzej Siemiski (Eds.) Multimedia and Internet Systems: Theory and Practice During the last 20 years we have witnessed a rapid development of Multimedia and Network Information Systems. What is even more important, the pace of change does not show any sign of slowing. When we look back we see how many research projects that have originated at various universities or in research facilities are now part of our everyday life. This monograph offers the reader a very broad review of the most recent scientific investigations in that area. The book is a collection of carefully selected and the most representative investigations, solutions, and applications…
Detecting nonlinear causal interactions between dynamical systems by non-uniform embedding of multiple time series.
2010
This study introduces a new approach for the detection of nonlinear Granger causality between dynamical systems. The approach is based on embedding the multivariate (MV) time series measured from the systems X and Y by means of a sequential, non-uniform procedure, and on using the corrected conditional entropy (CCE) as unpredictability measure. The causal coupling from X to Y is quantified as the relative decrease of CCE measured after allowing the series of X to enter the embedding procedure for the description of Y. The ability of the approach to quantify nonlinear causality is assessed on MV time series measured from simulated dynamical systems with unidirectional coupling (the Rössler-…
Dynamical analysis of anisotropic inflation
2016
Inflaton coupling to a vector field via the $f^2(\phi)F_{\mu\nu}F^{\mu\nu}$ term is used in several contexts in the literature, such as to generate primordial magnetic fields, to produce statistically anisotropic curvature perturbation, to support anisotropic inflation and to circumvent the $\eta$-problem. Here, I perform dynamical analysis of such a system allowing for most general Bianchi I initial conditions. I also confirm the stability of attractor equilibrium points in phase-space directions that had not been investigated before.
Semipredictable dynamical systems
2015
A new class of deterministic dynamical systems, termed semipredictable dynamical systems, is presented. The spatiotemporal evolution of these systems have both predictable and unpredictable traits, as found in natural complex systems. We prove a general result: The dynamics of any deterministic nonlinear cellular automaton (CA) with $p$ possible dynamical states can be decomposed at each instant of time in a superposition of $N$ layers involving $p_{0}$, $p_{1}$,... $p_{N-1}$ dynamical states each, where the $p_{k\in \mathbb{N}}$, $k \in [0, N-1]$ are divisors of $p$. If the divisors coincide with the prime factors of $p$ this decomposition is unique. Conversely, we also prove that $N$ CA w…
Active controlled structural systems under delta-correlated random excitation: linear and nonlinear case
2006
Abstract Reduction of structural vibration in active controlled dynamical system is usually performed by means of convenient control forces dependent of the dynamic response. In this paper the existent studies will be extended to dynamical systems subjected to non-Gaussian random process accounting for the time delay involved in the application of active control actions. Control forces acting with time-delay effects will be expanded in Taylor series evaluating response statistics by means of the extended Ito differential rule to consider the effects of the non-normality of the input processes. Numerical application provided shows the feasibility of the proposed method to analyze stochastic …