La Teoría de Sistemas como lenguaje

L'article analyse les possibilités, les problemes et les limitations des soi-disant modeles informatiques de simulation de systemes utilisés pour la représentation de certains aspects et conduites de la réalité. Puisque la téchnique précede la compréhension théorique de l'évenement, il faut un appareil théorique qui permette de comprendre ce qu'on fait en construisant des tels modeles: la Théorie des Systemes atteint ce but. Aucun schéma conceptuel, aucun ,langage ou vision du monde où la pluralité est le caractere dominant, n'importe quelle méthodologie avec une volonté de représentation invite à partir de la même épistémologie pluraliste.Analysis of the possibilities, problems and limitations of so-called informatic models of simulating systems need for the representation of specific aspects and behaviours of the reality. Being technique ahead of theoretic comprehension of the fact, it is necessary a theoretic system to be able to understand what happens when shaping those models: the theory of systems fulfils this aim. No conceptual scheme, language of view of the world has the quality of using up reality, nor takes a privileged place.Publicad

Performance evaluation of an online load change detection algorithm

Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertising or promotional purposes, creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other works. F. Mata, and J. Aracil, "Performance evaluation of an online load change detection algorithm", in 2nd International Conference on Computer and Automation Engineering, ICCAE 2010. Volume 1, p. 261 - 266In this paper we evaluate an online load change detection algorithm, aimed to identify changes in traffic loads when monitoring Internet links. This online change detector was first introduced in [1] and produces an alert when a sustained and statistically significant change has been detected. Then, the network manager verifies the change and takes action if the change is truly relevant. We show that the behavior of the algorithm with synthetically generated time series is appropriate, and the obtained results are as expected.The authors would like to acknowledge the support of the Spanish Ministerio de Ciencia e Innovación (MICINN) to this work under the FPU fellowship program

A new controller for the inverted pendulum on a cart

This paper presents a complete solution to the problem of swinging-up and stabilization of the inverted pendulum on a cart, with a single control law. The resulting law has two parts: first, an energy-shaping law is able to swing and maintain the pendulum up. Then, the second part introduces additional control to stop the cart and it is based on forwarding control with bounded input. The resulting control law is the sum of both parts and does not commute between different laws although there exist switches inside the controller.MEC-FEDER DPI2006-0733

Bifurcations and aggregation in large scale systems

This paper deals with the following problem: assume that a qualitative analysis (behaviour modes, bifurcation points, type of atractors .•• ) of a nonlinear dynamical system has been carried out and that afterwards this dynamical system is transformed into a large scale system through a disaggregating process of some (or all) of its variables. The problem at stake is to analyze whether the disagaregation gives rise to new behaviour modes, as a consequence of the appearance of new bifurcations in the disaggregated dynamical system. That leads us to study whether the original system and the disaggregated one are "equivalents" or whether the second one is richer in behaviours than the first one.The paper develops general results for standard disaggregation forms. Furthermore, practical applications of the proposed methodology to urban dynamics models is included .Comisión Asesora de Investigación Científica y Técnica (CAICYT) 1102/8

Flow-concurrence and bandwidth ratio on the Internet

The relevance of flow-based monitoring in tasks such as the detection of anomalies and denial of use attacks, traffic reporting, performance evaluation, software routing among others motivates the study of the Internet traffic in terms of flows. However, by the time a network manager or practitioner start any of these tasks, they face the challenge of planning probes’ capacities, which depends on the number of concurrent flows. Unfortunately, while the bandwidth of a network or link, both in operation and in future deployments, can be known, or at least estimated in advance, nothing is known about the load in terms of concurrent flows. We aimed at filling this gap by studying the concurrence of flows with respect to the bandwidth normalized by factors such as protocol shares, timeouts, applications, time and years among others. As a result, we provide the research community with several models, based on lognormal distributions, and parameter estimates in such a way that any player in the Internet arena can estimate the number of concurrent flows in their own infrastructure. Moreover, such results emerge from a diverse set of network traces so making the extrapolation of conclusions viableThis work was partially funded by the Spanish Ministry of Economyand Competitiveness through the research project TRAFICA(MINECO/FEDER TEC2015-69417-C2-1-R

Terminología

[ES] Este artículo se ocupa del término inglés fuzzy, cuya traducción al español también ha sido objeto de múltiples controversias, hasta el punto de que no han faltado valedores de la adopción del término en inglés, tal cual. Sin embargo, en español tenemos un término que recoge muy bien el significado de fuzzy y este es el de borroso. Hay otro término que también ha alcanzado un uso bastante extendido y es el de difuso.Aracil, J. (2010). Terminología. Revista Iberoamericana de Automática e Informática industrial. 1(3):83-84. http://hdl.handle.net/10251/146687OJS83841

High-speed TCP flow record extraction using GPUs

The final publication is available at Springer via http://dx.doi.org/10.1007/s11227-015-1478-9Traffic analysis is an essential part of capacity planning, quality of service assurance, and reinforcement of security in current telecommunication networks. Traffic volume increases with network speed and the analysis of large traffic traces is computationally intensive. The paper presents, for the first time ever, a flow extraction software that allows to obtain complex TCP-aware flow records at 4.4 millions of packets per second in a single GPU. Such TCP flow records include number of retransmissions and duplicates per flow, whose calculation is very challenging to obtain at high-speed. Our software significantly increases the processing performance of the recently proposed high-speed sniffers based on commodity hardware and demonstrates the advantages of applying massively parallel processing devices for traffic analysis

Analysis of IP delay variation in edge OBS nodes

This is an electronic version of the paper presented at the European Conference on Networks and Optical Communications, held in Stockholm on 2007This paper evaluates the packet delay from its arrival at the burstifier until the burst is finally released. Such evaluation comprises the delay due to burstification together with the delay which is due to waiting in the transmission queue. More specifically, we focus on the delay jitter, which has an impact on the performance of multimedia applications.The authors would like to acknowledge the support of the E-Photon/One+ Network of Excellence (FP6-IST-027497) to this work