Search results for "Systems Theory"
showing 10 items of 220 documents
Model Identification of a Network as Compressing Sensing
2013
In many applications, it is important to derive information about the topology and the internal connections of dynamical systems interacting together. Examples can be found in fields as diverse as Economics, Neuroscience and Biochemistry. The paper deals with the problem of deriving a descriptive model of a network, collecting the node outputs as time series with no use of a priori insight on the topology, and unveiling an unknown structure as the estimate of a "sparse Wiener filter". A geometric interpretation of the problem in a pre-Hilbert space for wide-sense stochastic processes is provided. We cast the problem as the optimization of a cost function where a set of parameters are used t…
Information Decomposition in Multivariate Systems: Definitions, Implementation and Application to Cardiovascular Networks
2016
The continuously growing framework of information dynamics encompasses a set of tools, rooted in information theory and statistical physics, which allow to quantify different aspects of the statistical structure of multivariate processes reflecting the temporal dynamics of complex networks. Building on the most recent developments in this field, this work designs a complete approach to dissect the information carried by the target of a network of multiple interacting systems into the new information produced by the system, the information stored in the system, and the information transferred to it from the other systems; information storage and transfer are then further decomposed into amou…
An Urbanistic Project Based on General Systems Theory
1991
This paper intends to be an outline of the Urbanistic Development Planning of the Valencian Community in Spain to be performed during the years 1991 to 1993, The following are considered as objectives of the Planning: – Quality of Life improvement, – protection of Nature, – rational management of natural resources, – rational use of land; all based on social demand. The territory and the mechanism of intervention is considered as a system whose elements can be grouped as: – uses of land, – infrastructure, equipment, services, – objectives, – intervention and management. The Planning proposes itself to be: integral, strategic, prospective, programmed, controllable and participative, A simula…
Phantom development for daily checks in electron intraoperative radiotherapy with a mobile linac.
2020
Abstract Purpose IORT with mobile linear accelerators is a well-established modality where the dose rate and, therefore, the dose per pulse are very high. The constancy of the dosimetric parameters of the accelerator has to be checked daily. The aim of this work is to develop a phantom with embedded detectors to improve both accuracy and efficiency in the daily test of an IORT linac at the surgery room. Methods The developed phantom is manufactured with transparent polymethyl methacrylate (PMMA), allocating 6 parallel-plate chambers: a central one to evaluate the on-axis beam output, another on-axis one placed at a fixed depth under the previous one to evaluate the energy constancy and four…
Iterative closure method for non-linear systems driven by polynomials of Gaussian filtered processes
2008
This paper concerns the statistical characterization of the non-Gaussian response of non-linear systems excited by polynomial forms of filtered Gaussian processes. The non-Gaussianity requires the computation of moments of any order. The problem is solved profiting from both the stochastic equivalent linearization (EL), and the moment equation approach of Ito's stochastic differential calculus through a procedure divided into two parts. The first step requires the linearization of the system, while retaining the non-linear excitation; the response statistical moments are calculated exactly, and constitute a first estimate of the moments of the actual non-linear system. In the second step, t…
What is a physical measure of spatial inhomogeneity comparable to the mathematical approach?
1999
A linear transformation f(S) of configurational entropy with length scale dependent coefficients as a measure of spatial inhomogeneity is considered. When a final pattern is formed with periodically repeated initial arrangement of point objects the value of the measure is conserved. This property allows for computation of the measure at every length scale. Its remarkable sensitivity to the deviation (per cell) from a possible maximally uniform object distribution for the length scale considered is comparable to behaviour of strictly mathematical measure h introduced by Garncarek et al. in [2]. Computer generated object distributions reveal a correlation between the two measures at a given l…
Is translation an autopoietic system?
2010
Translation is analyzed from the standpoint of its systemic properties. Translation is shown to have the capacity to observe itself and its difference from the environment. Observation being a major autopoietic factor, translation may be considered as an autopoietic system. Doubts about this hypothesis arise because of the peculiarities of communicative properties of translation. Translation plays the role of the mediating party in complex translation communication events and its communicative behavior is ‘defective’ in that translation does not act upon source messages because its communicative function is passing messages on to the target party. As a system, translation may be studied aga…
Variaatio oppimisen osoittajana ja ohjaajana
2021
Arvioitu teos:
 Sirkku Lesonen: Valuing variability. Dynamic usage-based principles in the L2 development of four Finnish language learners. Groningen Dissertations in Linguistics 184. Groningen: Rijksuniversiteit Groningen 2020. 310 s. isbn 9789403426747. Saatavilla verkossa osoitteessa http://urn.fi/URN:ISBN:978-94-034-2675-4.
Control of Power Converters with Hybrid Affine Models and Pulse-Width Modulated Inputs
2021
In this paper, hybrid dynamical systems theory is applied to the analysis and control of switched converters with Pulse-Width Modulated (PWM) inputs. The system is described by a state-space model with continuous flows and discrete jumps, without averaged equations. The modulation effects are captured in full without using time-dependent signals, by enlarging the state vector to include the PWM waveform generation process. Furthermore, the sample-and-hold mechanism associated with the sampling frequency is also taken into account with this approach. A control law is proposed based on a Lyapunov function candidate. Furthermore, convergence sets and the steady state jitter, inherent to PWM-ba…
Dynamics of the Shapovalov mid-size firm model
2020
Forecasting and analyses of the dynamics of financial and economic processes such as deviations of macroeconomic aggregates (GDP, unemployment, and inflation) from their long-term trends, asset markets volatility, etc., are challenging because of the complexity of these processes. Important related research questions include, first, how to determine the qualitative properties of the dynamics of these processes, namely, whether the process is stable, unstable, chaotic (deterministic), or stochastic; and second, how best to estimate its quantitative indicators including dimension, entropy, and correlation characteristics. These questions can be studied both empirically and theoretically. In t…