938 research outputs found

    Array of Multilayer Perceptrons with No-class Resampling Training for Face Recognition

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    A face recognition (FR) problem involves the face detection, representation and classification steps. Once a face is located in an image, it has to be represented through a feature extraction process, for later performing a proper face classication task. The most widely used approach for feature extraction is the eigenfaces method, where an eigenspace is established from the image training samples using principal components analysis.In the classification phase, an input face is projected to the obtained eigenspace and classified by an appropriate classifier. Neural network classifiers based on multilayer perceptron models have proven to be well suited to this task. This paper presents an array of multilayer perceptron neural networks trained with a novel no-class resampling strategy which takes into account the balance problem between class and no-class examples andincreases the generalization capabilities. The proposed model is compared against a classical multilayer perceptron classifier for face recognition over the AT&T database of faces, obtaining results that show an improvement over the classification rates of a classical classifier.Fil: Capello, D.. Universidad Tecnológica Nacional. Facultad Regional Santa Fe; ArgentinaFil: Martínez, César Ernesto. Universidad Nacional del Litoral. Facultad de Ingeniería y Ciencias Hídricas; ArgentinaFil: Milone, Diego Humberto. Universidad Nacional de Entre Ríos; ArgentinaFil: Stegmayer, Georgina. Universidad Nacional del Litoral. Facultad de Ingeniería y Ciencias Hídricas; Argentin

    Lo studio dei vulcani attivi e delle strutture crostali con reti sismiche temporanee: storia, evoluzione e prospettive della Rete Sismica Mobile dell’Osservatorio Vesuviano (INGV)

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    In this paper the history of the Mobile Seismic Network of the Osservatorio Vesuviano (at present Department of Napoli of the Istituto Nazionale di Geofisica e Vulcanologia – INGV) is described. The instrumental development and the main research and monitoring activities since the early 1980’ are reported. Starting from the analog stations with magnetic tape recording to the first digital stations with trigger recording, until the modern multichannel 24bit devices, the technological development of the last 30 years has given a strong contribution to increase the knowledge in the seismology and seismotectonics fields. The Mobile Seismic Network has been engaged in active and passive seismic studies both on volcanic and tectonic areas. Particularly, the contribution of the Mobile Seismic Network for the monitoring of Neapolitan active volcanoes has been very important to improve the Permanent Network. During seismic crises high quality data have been gathered allowing detailed analyses of the seismic activity. Moreover, the time synchronization by means of GPS time code allowed the deployment of the Mobile Network abroad and the collaboration with the main international research institutes. At present, the Mobile Seismic Network of the Osservatorio Vesuviano is developing on multichannel acquisition systems, also in array configuration, to gathered simultaneously seismic signals with a large frequency band

    Reflections of Medical Students on Visiting Chronically Ill Older Patients in the Home

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    Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/66114/1/j.1532-5415.2006.00918.x.pd

    Mott Transition and Spin Structures of Spin-1 Bosons in Two-Dimensional Optical Lattice at Unit Filling

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    We study the ground state properties of spin-1 bosons in a two-dimensional optical lattice, by applying a variational Monte Carlo method to the S=1 Bose-Hubbard model on a square lattice at unit filling. A doublon-holon binding factor introduced in the trial state provides a noticeable improvement in the variational energy over the conventional Gutzwiller wave function and allows us to deal effectively with the inter-site correlations of particle densities and spins. We systematically show how spin-dependent interactions modify the superfluid-Mott insulator transitions in the S=1 Bose-Hubbard model due to the interplay between the density and spin fluctuations of bosons. Furthermore, regarding the magnetic phases in the Mott region, the calculated spin structure factor elucidates the emergence of nematic and ferromagnetic spin orders for antiferromagnetic (U2>0U_2>0) and ferromagnetic (U2<0U_2<0) couplings, respectively.Comment: 5 pages, 5 figures, to appear in Journal of the Physical Society of Japa

    Effects of Long-Range Correlations on Nonmagnetic Mott Transitions in Hubbard model on Square Lattice

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    The mechanism of Mott transition in the Hubbard model on the square lattice is studied without explicit introduction of magnetic and superconducting correlations, using a variational Monte Carlo method. In the trial wave functions, we consider various types of binding factors between a doubly-occupied site (doublon, D) and an empty site (holon, H), like a long-range type as well as a conventional nearest-neighbor type, and add independent long-range D-D (H-H) factors. It is found that a wide choice of D-H binding factor leads to Mott transitions at critical values near the band width. We renew the D-H binding picture of Mott transitions by introducing two characteristic length scales, the D-H binding length l_{DH} and the minimum D-D distance l_{DD}, which we appropriately estimate. A Mott transition takes place at l_{DH}=l_{DD}. In the metallic regime (l_{DH}>l_{DD}), the domains of D-H pairs overlap with one another, thereby doublons and holons can move independently by exchanging the partners one after another. In contrast, the D-D factors give only a minor contribution to the Mott transition.Comment: 13 pages, 18 figures, submitted to J. Phys. Soc. Jp

    Effect of Doublon-Holon Binding on Mott transition---Variational Monte Carlo Study of Two-Dimensional Bose Hubbard Models

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    To understand the mechanism of Mott transitions in case of no magnetic influence, superfluid-insulator (Mott) transitions in the S=0 Bose Hubbard model at unit filling are studied on the square and triangular lattices, using a variational Monte Carlo method. In trial many-body wave functions, we introduce various types of attractive correlation factors between a doubly-occupied site (doublon, D) and an empty site (holon, H), which play a central role for Mott transitions, in addition to the onsite repulsive (Gutzwiller) factor. By optimizing distance-dependent parameters, we study various properties of this type of wave functions. With a hint from the Mott transition arising in a completely D-H bound state, we propose an improved picture of Mott transitions, by introducing two characteristic length scales, the D-H binding length ξdh\xi_{\rm dh} and the minimum D-D exclusion length ξdd\xi_{\rm dd}. Generally, a Mott transition occurs when ξdh\xi_{\rm dh} becomes comparable to ξdd\xi_{\rm dd}. In the conductive (superfluid) state, domains of D-H pairs overlap with each other (ξdh>ξdd\xi_{\rm dh}>\xi_{\rm dd}); thereby D and H can propagate independently as density carriers by successively exchanging the partners. In contrast, intersite repulsive Jastrow (D-D and H-H) factors have little importance for the Mott transition.Comment: 16 pages, 22 figures, submitted to J. Phys. Soc. Jp

    Importancia de la acreditación de laboratorios de organismos de regulación enológicos

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    A medida que aumenta la globalización de los suministros de alimentos, resulta cada vez más evidente la necesidad de reforzar los sistemas que velan por la inocuidad de los alimentos en todos los países. La acreditación es el reconocimiento formal, que hace una tercera parte, de que un organismo cumple con los requisitos especificados y es competente para desarrollar tareas específicas de evaluación de la conformidad. INAVI como organismo regulador de la vitivinicultura de la República Oriental del Uruguay cuenta desde el año 2011 con un Laboratorio Acreditado por el OUA (Organismo Uruguayo de Acreditación) en la Norma ISO/IEC 17025:2005. En la actualidad cuenta con 16 alcances en dos matrices diferentes vinos y sidras asegurando así su competencia técnica. Los Organismos Reguladores en Enología con frecuencia deben tomar decisiones en referencia a la salud y bienestar de los consumidores, protección del medio ambiente, control del cumplimiento de requisitos existentes reglamentarios y legales, generación de nuevos requisitos y regulaciones, así como asignación de recursos técnicos y financieros. Para poder tomar estas decisiones los Organismos de Regulación deben tener confianza en los resultados generados, la acreditación de sus laboratorios de ensayo genera la confianza necesaria para el desarrollo de dichas actividades

    The early experience of smart specialization implementation in EU cohesion policy

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    This paper discusses the early-stage experience of the smart specialization agenda within EU Cohesion Policy. The analysis examines the types of policy prioritization choices made by different member states and regions and seeks evidence on the extent to which weaker regions, in particular, might be constrained in their choices. The paper then reviews the evidence arising out of various surveys of policy-makers’ own experience and perceptions of the agenda, and concludes with a discussion of the major features of the policy progress so far and the main challenges ahead
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