103,968 research outputs found

    On the first place antitonicity in QL-implications

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    To obtain a demanded fuzzy implication in fuzzy systems, a number of desired properties have been proposed, among which the first place antitonicity, the second place isotonicity and the boundary conditions are the most important ones. The three classes of fuzzy implications derived from the implication in binary logic, S-, R- and QL-implications all satisfy the second place isotonicity and the boundary conditions. However, not all the QL-implications satisfy the first place antitonicity as S- and R-implications do. In this paper we study the QL-implications satisfying the first place antitonicity. First we establish the relationship between the first place antitonicity and other required properties of QL-implications. Second we work on the conditions under which a QL-implication generated by different combinations of a t-conorm S, a t-norm T and a strong fuzzy negation N satisfy the first place antitonicity, especially in the cases that both S and T are continuous. We further investigate the interrelationships between S- and R-implications generated by left-continuous t-norms on one hand and QL-implications satisfying the first place antitonicity on the other

    The N N -> NN pi+ Reaction near Threshold in a Chiral Power Counting Approach

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    Power-counting arguments are used to organize the interactions contributing to the N N -> d pi, p n pi reactions near threshold. We estimate the contributions from the three formally leading mechanisms: the Weinberg-Tomozawa (WT) term, the impulse term, and the Δ\Delta-excitation mechanism. Sub-leading but potentially large mechanisms, including SS-wave pion-rescattering, the Galilean correction to the WT term, and short-ranged contributions are also examined. The WT term is shown to be numerically the largest, and the other contributions are found to approximately cancel. Similarly to the reaction p p -> p p pi0, the computed cross sections are considerably smaller than the data. We discuss possible origins of this discrepancy.Comment: 31 pages, 17 figure

    Towards runtime discovery, selection and composition of semantic services

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    Service-orientation is gaining momentum in distributed software applications, mainly because it facilitates interoperability and allows application designers to abstract from underlying implementation technologies. Service composition has been acknowledged as a promising approach to create composite services that are capable of supporting service user needs, possibly by personalising the service delivery through the use of context information or user preferences. In this paper we discuss the challenges of automatic service composition, and present DynamiCoS, which is a novel framework that aims at supporting service composition on demand and at runtime for the benefit of service end-users. We define the DynamiCoS framework based on a service composition life-cycle. Framework mechanisms are introduced to tackle each of the phases and requirements of this life-cycle. Semantic services are used in our framework to enable reasoning on the service requests issued by end users, making it possible to automate service discovery, selection and composition. We validate our framework with a prototype that we have built in order to experiment with the mechanisms we have designed. The prototype was evaluated in a testing environment using some use case scenarios. The results of our evaluation give evidences of the feasibility of our approach to support runtime service composition. We also show the benefits of semantic-based frameworks for service composition, particularly for end-users who will be able to have more control on the service composition process

    Defining and Prototyping a Life-cycle for Dynamic Service Composition

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    Since the Internet has become a commodity in both wired and wireless environments, new applications and paradigms have emerged to explore this highly distributed and widespread system. One such paradigm is service-orientation, which enables the provision of software functionality as services, \ud allowing in this way the construction of distributed systems with loosely coupled parts. The Service-Oriented Architecture (SOA) provides a set of principles to create service-oriented systems, by defining how services can be \ud created, composed, published, discovered and invoked. In accordance with these principles, in this paper we address the challenge of performing dynamic service composition. The composition process and its associated tasks have to be precisely defined so that the different problems of dynamic service composition can be identified and tackled. To achieve this, this paper defines a life-cycle for dynamic service composition, which defines the required phases and stakeholders. Furthermore, we present our prototype in which the different phases of the dynamic service composition life-cycle are being implemented. This prototype is being used to experiment with and validate our initial ideas on dynamic service composition

    Long-Time Behaviour and Self-Similarity in a Coagulation Equation with Input of Monomers

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    For a coagulation equation with Becker-Doring type interactions and time-independent monomer input we study the detailed long-time behaviour of nonnegative solutions and prove the convergence to a self-similar function.Comment: 30 pages, 5 Figures, now published in Markov Processes and Related Fields 12, 367-398, (2006

    Set-up effects of piles in sand tested in the centrifuge

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    The bearing capacity of piles increases over time. Research has shown that this is caused by an increase in shaft friction combined with a constant or only slightly increasing base capacity. Although there are some ideas on the mechanisms that play a role there is no quantitative model to describe this mechanism. From the literature the shaft friction seems to increase linearly with the logarithm of time. For piles in the field this is proven by load tests performed between 1 until approximately 1000 days after installation. Literature indicates that set-up as a function of time is also present minutes and hours after installation. This allows investigating the set-up mechanisms under controlled conditions in a centrifuge. Therefore two test series have been performed to investigate the set-up for a single pile and a pile group. This paper presents the relevant literature and describes the position of the tests in the on-going research program on piles in The Netherlands. Furthermore, the results will be described and discussed. Time dependency in bearing capacity in sand can be observed in the centrifuge tests, although it is not certain whether some of the increase has not been caused by other mechanisms. It appears that the testing conditions as well as the effects of installation of neighboring piles are of great importance on the time effects

    Chiral Perturbation Theory in Few-Nucleon Systems

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    The low-energy effective theory of nuclear physics based on chiral symmetry is reviewed. Topics discussed include the nucleon-nucleon force, few-body potentials, isospin violation, pion-deuteron scattering, proton-neutron radiative capture, pion photoproduction on the deuteron, and pion production in proton-proton collisions.Comment: 15 pages, 2 figures, Latex, aipproc.sty and epsfig, invited talk at the 6th Conference on the Intersections of Particle and Nuclear Physics, Big Sky, May 199
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