4,921 research outputs found

    Optimal boundary control of a viscous Cahn-Hilliard system with dynamic boundary condition and double obstacle potentials

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    In this paper, we investigate optimal boundary control problems for Cahn-Hilliard variational inequalities with a dynamic boundary condition involving double obstacle potentials and the Laplace-Beltrami operator. The cost functional is of standard tracking type, and box constraints for the controls are prescribed. We prove existence of optimal controls and derive first-order necessary conditions of optimality. The general strategy, which follows the lines of the recent approach by Colli, Farshbaf-Shaker, Sprekels (see the preprint arXiv:1308.5617) to the (simpler) Allen-Cahn case, is the following: we use the results that were recently established by Colli, Gilardi, Sprekels in the preprint arXiv:1407.3916 [math.AP] for the case of (differentiable) logarithmic potentials and perform a so-called "deep quench limit". Using compactness and monotonicity arguments, it is shown that this strategy leads to the desired first-order necessary optimality conditions for the case of (non-differentiable) double obstacle potentials.Comment: Key words: optimal control; parabolic obstacle problems; MPECs; dynamic boundary conditions; optimality conditions. arXiv admin note: substantial text overlap with arXiv:1308.561

    Ultrametricity in the Edwards-Anderson Model

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    We test the property of ultrametricity for the spin glass three-dimensional Edwards-Anderson model in zero magnetic field with numerical simulations up to 20320^3 spins. We find an excellent agreement with the prediction of the mean field theory. Since ultrametricity is not compatible with a trivial structure of the overlap distribution our result contradicts the droplet theory.Comment: typos correcte

    Bounded Reachability for Temporal Logic over Constraint Systems

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    We present CLTLB(D), an extension of PLTLB (PLTL with both past and future operators) augmented with atomic formulae built over a constraint system D. Even for decidable constraint systems, satisfiability and Model Checking problem of such logic can be undecidable. We introduce suitable restrictions and assumptions that are shown to make the satisfiability problem for the extended logic decidable. Moreover for a large class of constraint systems we propose an encoding that realize an effective decision procedure for the Bounded Reachability problem

    Constraint LTL Satisfiability Checking without Automata

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    This paper introduces a novel technique to decide the satisfiability of formulae written in the language of Linear Temporal Logic with Both future and past operators and atomic formulae belonging to constraint system D (CLTLB(D) for short). The technique is based on the concept of bounded satisfiability, and hinges on an encoding of CLTLB(D) formulae into QF-EUD, the theory of quantifier-free equality and uninterpreted functions combined with D. Similarly to standard LTL, where bounded model-checking and SAT-solvers can be used as an alternative to automata-theoretic approaches to model-checking, our approach allows users to solve the satisfiability problem for CLTLB(D) formulae through SMT-solving techniques, rather than by checking the emptiness of the language of a suitable automaton A_{\phi}. The technique is effective, and it has been implemented in our Zot formal verification tool.Comment: 39 page

    On the structure of correlations in the three dimensional spin glasses

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    We investigate the low temperature phase of three-dimensional Edwards-Anderson model with Bernoulli random couplings. We show that at a fixed value QQ of the overlap the model fulfills the clustering property: the connected correlation functions between two local overlaps decay as a power whose exponent is independent of QQ for all 0≤∣Q∣<qEA0\le |Q| < q_{EA}. Our findings are in agreement with the RSB theory and show that the overlap is a good order parameter.Comment: 5 pages, 5 figure

    USER STUDIES FOR DIGITAL LIBRARIES EVALUATION AND DEVELOPMENT

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    This tutorial - the only one in JCDL 2012 Conference - introduces a range of methods which can be applied to understand better user needs and expectations (surveys, questionnaires, interviews, deep log analysis, personas, eye tracking, ethnographic studies) and to give a practical feel how they work in real practice through a series of recent studies. It includes real life international case study which will help the participants to get a better understanding what studies could be particularly helpful according to the products and services they develop, how to involve user s in digital library evaluation, and how to engage better with users

    A minimum-energy-based capacitor voltage balancing control strategy for MPC conversion systems

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    In AC/DC/AC power conversion, the connection of a multi point clamped (MPC) rectifier with an MPC inverter simplifies the balancing of the voltages on the series-connected DC link capacitors as well as giving input power-factor correction capability. This is only true provided that an alternative balancing PWM control strategy is adopted instead of the standard PWM one. A control strategy is proposed which is based on the development of an energy function which may be minimized in real time by exploiting the existing redundancies in power-converter switching states. This strategy may be easily implemented in a DSP controller and is usable with any number of voltage levels and input/output phases. A validation has been performed by simulating a 5-level 3-phase MPC system and the significant waveforms are presente

    Extreme Peripheral Blood Plasmacytosis Mimicking Plasma Cell Leukemia as a Presenting Feature of Angioimmunoblastic T-Cell Lymphoma (AITL).

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    Angioimmunoblastic T-cell lymphoma (AITL) is one of four major subtypes of nodal peripheral T cell lymphoma, characterized by its cell of origin, the follicular helper T-cell (TFH). Patients typically present with prominent constitutional (B) symptoms, generalized lymphadenopathy, hepatosplenomegaly, cytopenias, and rash. Here we present a case of a 62-year-old male with progressive cervical adenopathy, fevers and weight loss presenting with extreme polyclonal plasmacytosis and high plasma EBV viral load. While the initial presentation appeared to mimic plasma cell leukemia or severe infection, lymph node biopsy and bone marrow biopsy confirmed a diagnosis of AITL. This case highlights the heterogeneity of the clinical presentation of AITL to enable physicians to more promptly recognize, diagnose and initiate treatment
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