Dpto. Automática y Computación - Automatika eta Konputazioa Saila
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Publication Open Access Posibles nuevas vías de investigación en teoría de la comunicación a través de modelos matemáticos: análisis topológico(Centro de Investigaciones Sociológicas, 1978) Corres Sanz, Jesús María; Burillo López, Pedro; Automática y Computación; Automatika eta KonputazioaUno de los pocos puntos en los que los metodólogos de las ciencias sociales están de acuerdo es el divorcio existente entre trabajo teórico y trabajo metodológico en las prácticas sociales concretas. Por otro lado, para la creación del corpus de las ciencias sociales se ha tropezado secularmente con un grave problema o inconveniente: la carencia o insuficiencia de un «lenguaje común» que permitiera el trabajo interdisciplinario de los diferentes científicos sociales. Por paradójico que parezca, este inconveniente no está siendo solucionado, únicamente, desde dentro de las ciencias sociales, sino que ha sido precisa la colaboración de otras ciencias, especialmente las ciencias exactas (física, matemáticas...). Estos dos aspectos epistemológicos de las ciencias sociales han inducido a buena parte de los investigadores sociales a abordar el estudio y análisis de las prácticas sociales a través de la Teoría de la Comunicación.Publication Open Access Overtaker binary relations on complete completely distributive lattices related to the level sets of the L-fuzzy sets(Universitat Politècnica de Catalunya, 1994) Núñez, A.; Burillo López, Pedro; Fuentes González, Ramón; González, L.; Automática y Computación; Automatika eta KonputazioaThe class of overtaker binary relations associated with the order in a lattice is defined and used to generalize the representations of L-fuzzy sets by means of level sets or fuzzy points.Publication Open Access A method for inference in approximate reasoning based on normal intuitionistic fuzzy sets(Institute of Biophysics and Biomedical Engineering, Bulgarian Academy of Sciences, 1995) Bustince Sola, Humberto; Burillo López, Pedro; Mohedano Salillas, Victoria; Automática y Computación; Automatika eta KonputazioaThis paper introduces a method of approximate inference which operates with nornal intuitionistic fuzzy. We give a definition of degree of compatibility between intuitionistic fuzzy sets and we present a method for the construction of these sets. Lastly we present the method of inference in approximate reasoning with normal intuitionistic fuzzy sets and we study its most immediate properties.Publication Open Access Handling multicriteria fuzzy decision-making problems based on intuitionistic fuzzy sets(Institute of Biophysics and Biomedical Engineering, Bulgarian Academy of Sciences, 1995) Bustince Sola, Humberto; Automática y Computación; Automatika eta KonputazioaIn this paper we present a new technique for handling multicriteria decision making problems based on intuitionistic fuzzy sets. In this new technique we use the degree of reliability and of non-reliability of each criterion in relation to a set of alternatives. We also present a new score function in order to evaluate the degree of suitability of the choice of a certain alternative.Publication Open Access Intuitionistic fuzzy relations (Part I)(Universitat Politècnica de Catalunya, 1995) Burillo López, Pedro; Bustince Sola, Humberto; Automática y Computación; Automatika eta KonputazioaThis paper introduces the concept of intuitionistic fuzzy relation. We also study the choice of t-norms and t-conorms which must be done in order that the composition of intuitionistic fuzzy relations fulfills the largest number of properties. On the other hand, we also analyse the intuitionistic fuzzy relations in a set and their properties. Besides, we also study the properties of the intuitionistic fuzzy relations in a set and the properties of the composition with different t-norms and t-conorms.Publication Open Access On the intuitionistic fuzzy relations(Institute of Biophysics and Biomedical Engineering, Bulgarian Academy of Sciences, 1995) Burillo López, Pedro; Bustince Sola, Humberto; Atanassov, Krassimir; Automática y Computación; Automatika eta KonputazioaIntuitionistic fuzzy relations which generalize the already existing relations are introduced and their basic properties are shown.Publication Open Access Intuitionistic fuzzy relations (Part II). Effect of Atanassov's operators on the properties of the intuitionistic fuzzy relations(Universitat Politècnica de Catalunya, 1995) Burillo López, Pedro; Bustince Sola, Humberto; Automática y Computación; Automatika eta KonputazioaIn this paper we study the effect of Atanassov's operator on the properties of properties reflexive, symmetric, antisymmetric, perfect antisymmetric and transitive intuitionistic fuzzy relations. We finish the paper analysing the partial enclosure of the intuitionistic fuzzy relations and its effect on the conservation of the transitive property through Atanassov's operator.Publication Open Access Concept lattices associated with interval-valued L-fuzzy contexts(Institute of Biophysics and Biomedical Engineering, Bulgarian Academy of Sciences, 1995) Burusco Juandeaburre, Ana; Fuentes González, Ramón; Automática y Computación; Automatika eta KonputazioaIn 1882 Wille published the paper titled Restructuring lattice theory: an approach based on hierarchies of concepts, where he developed a new theory called formal concept theory. In that paper he analyzes 0/1 relations between the object and attribute sets. Applying the L-fuzzy set theory to Wille’s results, we have developed the L-fuzzy concept theory dealing with L-fuzzy relations inside 0/1 relations. The final purpose of our theory is knowledge acquisition and classification. Taking as departure point the L-fuzzy concept theory, in this paper we study contexts defined by interval-valued L-fuzzy relations between the object and attribute sets. We give a new definition of L-fuzzy concept valid for this case and analyze the structure of the L-fuzzy concept set. We apply these results to a medical example.Publication Open Access Orderings in the referential set induced by intuitionistic fuzzy relation(Institute of Biophysics and Biomedical Engineering, Bulgarian Academy of Sciences, 1995) Burillo López, Pedro; Bustince Sola, Humberto; Automática y Computación; Automatika eta KonputazioaIn this paper we present different orderings in the referential set induced by intuitionistic fuzzy relations of ordering. We can see how these induced orders justify the definition given of intuitionistic fuzzy antisymmetry and the definition of partial enclosure.Publication Open Access A theorem for constructing interval-valued intuitionistic fuzzy sets from intuitionistic fuzzy sets(Institute of Biophysics and Biomedical Engineering, Bulgarian Academy of Sciences, 1995) Bustince Sola, Humberto; Burillo López, Pedro; Automática y Computación; Automatika eta KonputazioaIn this paper we present a theorem that allows us to construct interval-valued intuitionistic fuzzy sets from intuitionistic fuzzy sets. We also study the way of recovering intuitionistic fuzzy sets used in the construction of the interval-valued intuitionistic fuzzy set from different operators. We analise the numerical measures of information of the internal-valued intuitionistic fuzzy set constructed in function with the numerical measures of information of the intuitionistic fuzzy sets used in its construction. We review the most important properties of intuitionistic fuzzy sets and of internal-valued intuitionistic fuzzy sets and we analise three operators among these sets along with their properties.Publication Open Access About the intuitionistic fuzzy set generators(Institute of Biophysics and Biomedical Engineering, Bulgarian Academy of Sciences, 1997) Bustince Sola, Humberto; Mohedano Salillas, Victoria; Automática y Computación; Automatika eta KonputazioaIn this paper form the definition of intuitionistic fuzzy sets we analyze the intuitionistic fuzzy generators and the complementation in these sets. We start by defining the intuitionistic fuzzy generators in order to then study the particular cases for which this definition coincides with the fuzzy complementation. Afterwards we analyze the existence of equilibrium points, dual points and we present characterization theorems of intuitionistic fuzzy generators. Lastly, we study a manner of constructing intuitionistic fuzzy sets and analyse the structure of the complementary of intuitionistic fuzzy sets built.Publication Open Access Use of CBR for IP over ATM(SPIE, 1997) Aracil Rico, Javier; Morató Osés, Daniel; Izal Azcárate, Mikel; Donézar, C.; Automática y Computación; Automatika eta KonputazioaInternet traffic burstiness allows for statistical multiplexing gain in the available bandwidth of an ATM link. However, a dynamic allocation bandwidth assignment (ABR) has to be performed. In this paper we evaluate the real advantages of ABR versus CBR for Internet service provisioning. We consider performance parameters such as connection setup delay and active waiting time due to flow control and show that CBR schemes can be a good alternative for Internet service provisioning over ATM networks.Publication Open Access On completeness and direction in fuzzy relational systems(Universitat Politècnica de Catalunya, 1998) Burillo López, Pedro; Fuentes González, Ramón; González, L.; Automática y Computación; Automatika eta KonputazioaThe concepts of bounded subset, complete subset and directed subset, which are well known in the context of partially ordered sets (X, ≤), are extended in order to become applicable, with coherence, in fuzzy relational systems (X, R). The properties of these generalized structures are analyzed and operative examples of them are presented.Publication Open Access IPmiser, sistema de monitorización de enlaces ATM a 155Mbps(1998) Aracil Rico, Javier; Morató Osés, Daniel; Izal Azcárate, Mikel; Solana, Juan Ignacio; Ariste, Teresa; Fillmore, David; Automática y Computación; Automatika eta KonputazioaPublication Open Access Herramienta de gestión en tiempo real de redes de área extensa(1998) Magaña Lizarrondo, Eduardo; Aracil Rico, Javier; Villadangos Alonso, Jesús; Automática y Computación; Automatika eta KonputazioaThis paper presents PROMIS, a new network management tool based on a distributed architecture of traffic probes. It allows network managers to monitor traffic from any wide area network segment in real time using a WWW console or a Tcl/Tk graphic interface.Publication Open Access Técnicas eficientes de filtrado y análisis de tráfico para la monitorización continua de redes de comunicaciones(1999) Ruiz, José Javier; Magaña Lizarrondo, Eduardo; Aracil Rico, Javier; Villadangos Alonso, Jesús; Automática y Computación; Automatika eta KonputazioaThis paper presents an efficient traffic filtering and analysis architecture for network monitoring. Opposed to the usual network monitoring architectures that provide simultaneous filters as requested by managers (packet filters), we propose a different approach that aims at minimizing CPU load by avoiding unnecessary filter duplicates. Such architecture makes it possible to optimize several parallel filters execution and thus is suitable for continuous network monitoring in which it is necessary to keep track of hundreds of filters. This architecture has been implemented in a network-monitoring tool called PROMIS whose main features are detailed in this paper.Publication Open Access Analysis of Internet services in IP over ATM networks(IEEE, 1999) Aracil Rico, Javier; Morató Osés, Daniel; Izal Azcárate, Mikel; Automática y Computación; Automatika eta KonputazioaThis paper presents a trace-driven analysis of IP over ATM services from a user-perceived quality of service standpoint. QoS parameters such as the sustained throughput for transactional services and other ATM layer parameters such as the burstiness (MBS) per connection are derived. On the other hand, a macroscopic analysis that comprises percentage of flows and bytes per service, TCP transaction duration and mean bytes transferred in both ways is also presented. The traffic trace is obtained with a novel measurement equipment that combines a header extraction hardware and a high end UNIX workstation capable of providing a timestamp accuracy in the order of microseconds. The ATM link under analysis concentrates traffic from a large population of 1,500 hosts from Public University of Navarra campus network, that produce 1,700,000 TCP connections approximately in the measurement period of one week. The results obtained from such a wealth of data suggest that QoS is primarily determined by transport protocols and not by ATM bandwidth. The sustained throughput of TCP connections never grows beyond 80 Kbps with 70% probability in the data transfer phase (i. e., in the ESTABLISHED state) and we observe a strong influence of the connection establishment phase in the user-perceived throughput. On the other hand, the burstiness of individual TCP connections is rather small, namely TCP connections do not produce bursts according to the geometric law given by slow start and commonly assumed in previously published studies.Publication Open Access Arquitectura de publicación automatizada de contenidos educativos supervisados en Internet(1999) Arin Irastorza, María Asunción; Magaña Lizarrondo, Eduardo; Astrain Escola, José Javier; Villadangos Alonso, Jesús; González de Mendívil Moreno, José Ramón; Automática y Computación; Automatika eta KonputazioaThis paper presents an automated publishing architecture of educational and supervised contents over the Internet. The system makes easier the job of publishing educational courses over the network using specific tools that automates the access control (CGI -- Common Gateway Interface), encrypts the information that goes through the net for not being accessed by strangers (SSL – Secure Sockets Layer), gives an statistical control of the usage of the system, and tutors the course. This project is multiplatform, i.e. all the components that integrate the system are available for any operating system (Windows 9X, Solaris, Linux,...) and it is based on the Web.Publication Open Access IPmiser: herramienta de medida and análisis de redes de alta velocidad(1999) Aracil Rico, Javier; Morató Osés, Daniel; Izal Azcárate, Mikel; Automática y Computación; Automatika eta KonputazioaLas redes de área extensa IP generan en la actualidad un tráfico difícil de predecir y caracterizar. Así, se hace necesario disponer de herramientas que proporcionen monitorización en tiempo real de los enlaces, sin interrupción y con la máxima fiabilidad y precisión de reloj. La herramienta IPmiser consigue este objetivo mediante un hardware dedicado y una estación de trabajo para el proceso de datos, que es además servidor seguro de información de monitorización. En este artículo se presenta la arquitectura de IPmiser, junto con los resultados más destacables de diversas mediciones en el enlace IP sobre ATM de la Universidad Publica de Navarra.Publication Open Access Analysis and stochastic characterization of TCP flows(Springer, 2000) Aracil Rico, Javier; Morató Osés, Daniel; Izal Azcárate, Mikel; Automática y Computación; Automatika eta KonputazioaSince the most Internet services use TCP as a transport protocol there is a growing interest in the characterization of TCP flows. However, the flow characteristics depend on a large number of factors, due to the complexity of the TCP. As a result, the TCS characteristics are normally studies by means of simulations or controlled network setups. In this paper we propose a TCP characterization based on a generic model based of stochastic flow with burstiness and throughput (((σ, ρ)-constraints), which is useful in order to characterize flows in ATM and other flow-switched networks. The model is obtained through extensive analysis of a real traffic trace, comprising an approximate number of 1,500 hosts and 1,700,000 TCP connections. The results suggests that TCP connections in the wide area Internet have low throughput while the packet bursts do not suffer an exponential increase, as indicated by the slow-start behavior. On the other hand, the impact of the connection establishment phase is striking. We note that the throughput of the TCP flow is approximately half the throughput which is obtained in the data transfer phase, namely after the connection has been established.