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A document retrieval system is a quite useful tool in office environments, expecially for professionals who are interested in keeping along with the state of the art of their field by quickly consulting documents. The paper describes the design and the implementation of a document retrieval system based on a concept extraction from documents. Concept(More)
Melting in Na(n) clusters described with an empirical embedded-atom potential has been reexamined in the size range 55</=n</=147 with a special attention at sizes close to 130. Contrary to previous findings, premelting effects are also present at such medium sizes, and they turn out to be even stronger than the melting process itself for Na(133) or Na(135).(More)
The design and implementation of an input/output processor for an ATM switch are described. This IC was realized on a 0.7 /spl mu/m BiCMOS technology. To manipulate ATM cells at a frequency of 311 MHz (STM16) at the I/O of the chip, ECL blocks were employed. The core of the chip is composed of CMOS cells that run at a maximum clock speed of 65 MHz. Pure(More)
  • F Calvo
  • 1999
We present a numerical procedure for extracting Lyapunov characteristic exponents from classical molecular-dynamics simulations of molecular systems. The theoretical frame chosen to describe the orientational degrees of freedom is the quaternions scheme. We apply the method to small methane clusters. Two different model potentials are used to investigate(More)
The structures and stabilities of Ar(n)Na+ clusters (n < or = 54) are investigated using atomistic potentials fitted to reproduce ab initio calculations performed at the coupled-cluster level on the smaller clusters. Polarization effects are described using either the interaction between dipoles induced by the sodium ion, or a small charge transfer in the(More)
The relative performances of different implementations of the Wang-Landau method are assessed on two classes of systems with continuous degrees of freedom, namely, two polypeptides and two atomic Lennard-Jones clusters. Parallel tempering Monte Carlo simulations serve as a reference, and we pay particular attention to the variations of the multiplicative(More)
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