1,721,250 research outputs found
Non-Normality Improves Information Transmission Performance of Network Systems
No full textIn this paper, we propose a new measure of communication performance of linear network systems, the information gain, and we show that this measure is strongly affected by the degree of non-normality of the networks adjacency matrix. Specifically, we prove that the numerical abscissa of the networks adjacency matrix, a well-known indicator of matrix non-normality, regulates the behavior of the information gain. Further, we establish a lower bound on the information gain of positive networks, i.e., weighted networks with positive weights. This bound reveals that the information gain may exhibit an exponential dependence on the graphical distance between the transmitter and the receiver nodes. Finally, we present a design methodology which provably enhances the information gain while keeping the networks weights bounded in magnitude. We illustrate and validate our theoretical findings by means of examples with structured and random networks
Stability analysis and synthesis for scalar linear systems with a quantized feedback
No full textIt is well known that a linear system controlled by a quantized feedback may exhibit the wild dynamic behavior which is typical of a nonlinear system. In the classical literature devoted to control with quantized feedback, the flow of information in the feedback was not considered as a critical parameter. Consequently, in that case, it was natural in the control synthesis to simply choose the quantized feedback approximating the one provided by the classical methods, and to model the quantization error as an additive white noise. On the other hand, if the flow of information has to be limited, for instance, because of the use of a transmission channel with limited capacity, some specific considerations are in order. The aim of this paper is to obtain a detailed analysis of linear scalar systems with a stabilizing quantized feedback control. First, a general framework based on a sort of Lyapunov approach encompassing known stabilization techniques is proposed. In this case, a rather complete analysis can be obtained through a nice geometric characterization of asymptotically stable closed-loop maps. In particular, a general tradeoff relation between the number of quantization intervals, quantifying the information flow, and the convergence time is established. Then, an alternative stabilization method, based on the chaotic behavior of piecewise affine maps is proposed. Finally, the performances of all these methods are compared
System theoretic propertiesof convolutional codes over rings
No full textConvolutional codes over rings are particularly suitable for representing codes over phase-modulation signals. In order to develop a complete structural analysis of this class of codes, it is necessary to study rational matrices over rings, which constitutes the generator matrices (encoders) for such convolutional codes. Noncatastrophic, minimal, systematic, and basic generator matrices are introduced and characterized by using a canonical form for polynomial matrices over rings. Finally, some classes of convolutional codes, defined according to the generator matrix they admit, are introduced and analyzed from a system-theoretic point of view
Minimal and systematic convolutional codes over finite abelian groups
No full textConvolutional codes over Abelian groups provide an effective theoretical framework for the analysis of some classes of TCM codes. The encoder synthesis for this class of codes is not as simple as in the binary case, since minimal encoders in the group case might be necessarily nonlinear. In this contribution an algorithmic method testing whether a convolutional code over an Abelian group admits a systematic or a minimal homomorphic encoder is provided. This test consists in verifying whether a subgroup splits in a group. Through this method, the class of codes admitting systematic encoders and the class of codes admitting minimal encoders can be compared. Finally this test is applied to some examples of practical relevance
I reperti faunistici provenienti dal sito del Neolitico recente di Botteghino (Parma)
No full textIl sito di Botteghino è ubicato a circa 7 km a sud di Parma. Lo scavo ha messo in luce diverse strutture pertinenti a un abitato della cultura Chassey, databile al Neolitico recente. Complessivamente sono stati analizzati 1452 reperti, dei quali solo 218 sono stati determinati a causa dello stato di conservazione dei materiali. Il gruppo dei caprovini è maggiormente presente nei contesti dello scavo più importanti (66% NR), mentre il maiale risulta essere la seconda specie allevata. Il bue è la specie domestica meno rappresentata; la macellazione di questi animali in età adulta fa ipotizzare che fossero allevati prevalentemente per lo sfrutt amento della forza lavoro e per la produzione secondaria. Le uniche specie selvatiche rinvenute sono il cervo e il cinghiale, che non rappresentavano elementi importanti nell’economia della comunità neolitica del sito. In generale il sito di Botteghino rientra piutt osto bene nel quadro economico-ambientale emerso dal confronto con altri depositi archeologici dell’Italia settentrionale
I sistemi multi-agents e gli algoritmi di consenso
Full text linkRecently, multi-agent systems have become a central study topic in many different disciplines including biology, engineering, physics, and social science. This has led to the emergence of large and constantly growing interdisciplinary research field, known as network science. The analysis of the mathematical models describing such systems has achieved significant results, but remains mostly an open research field, where many fundamental breakthroughs are expected in the next years. Such analysis is especially motivated by the quest for the development of tools for control and design of such systems. In this paper, we deal with consensus algorithms, an important example of design of multi-agent systems that has been inspired by the dynamics of cooperative systems in natural and social sciences
Analisi archeozoologica dei reperti faunistici provenienti dal sito del Neolitico recente del Botteghino (PR)
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