Now showing items 1-20 of 94

    • Optimization of cell configuration and comparisons using evolutionary computation approaches 

      Dimopoulos, Christos; Zalzala, Ali M.S. (1998-01-01)
      This paper examines a cellular manufacturing optimization problem in a new facility of a pharmaceutical company. The new facility, together with the old one, should be adequate to handle current and future production ...
    • The ISOPHOT far-infrared serendipity sky survey 

      Stickel, Manfred; Lemke, Dietrich; Bogun, Stefan; Klaas, Ulrich; Kunkel, Michael; Toth, L. Viktor; Hotzel, Stephan; Herbstmeier, Uwe; Kessler, Martin F.; Laureijs, René J.; Burgdorf, Martin J.; Beichman, Charles A.; Rowan-Robinson, Michael; Efstathiou, Andreas; Richter, Gotthard M.; Braun, Michael I. (1998-12-01)
      The ISOPHOT Serendipity Survey utilizes the slew time between ISO's pointed observations with strip scanning measurements of the sky in the far-IR at 170 micrometers. The slews contain information about two fundamentally ...
    • A genetic programming heuristic for the one-machine total tardiness problem 

      Dimopoulos, Christos; Zalzala, Ali M.S. (1999-01-01)
      Genetic programming has rarely been applied to manufacturing optimisation problems. In this report we investigate the potential use of genetic programming for the solution of the one-machine total tardiness problem. ...
    • Evolving similarity coefficients for the solution of cellular manufacturing problems 

      Dimopoulos, Christos; Mort, Neil (2000-01-01)
      The cell formation problem is a classic manufacturing optimization problem associated with the implementation of a cellular manufacturing system. A variety of hierarchical clustering procedures have been proposed for the ...
    • NP-completeness results and efficient approximations for radiocoloring in planar graphs 

      Fotakis, Dimitris A.; Nikoletseas., Sotiris E.; Lesta, Vicky Papadopoulou; Spirakis, Paul G. (2000-01-01)
      The Frequency Assignment Problem (FAP) in radio networks is the problem of assigning frequencies to transmitters exploiting frequency reuse while keeping signal interference to acceptable levels. The FAP is usually modelled ...
    • The ISOPHOT 170 micron serendipity sky survey: A plea to FIRST 

      Stickel, Manfred; Lemke, Dietrich; Klaas, Ulrich; Beichman, Charles A.; Rowan-Robinson, Michael; Efstathiou, Andreas; Bogun, Stefan; Kessler, Martin F.; Richter, Gotthard M. (2001-01-01)
      The ISOPHOT Serendipity Survey utilized the slew time between ISO's pointed observations with strip scanning measurements of the sky in the far-infrared (FIR) at 170μm. The integral 170μm fluxes for compact sources derived ...
    • MID-FIR properties of ELAIS sources 

      Márquez, I.; Masegosa, J.; Morel, Thierry; Efstathiou, Andreas; Verma, Aprajita; Väisänen, Petri H.; Alexander, David M.; Héraudeau, Ph; Surace, Christian; Pérez-Fournón, Ismaël; Cabrera-Guerra, F.; González-Serrano, José Ignacio; González-Solares, Eduardo A.; Serjeant, Stephen B.G.; Oliver, Sebastian James; Rowan-Robinson, Michael (2001-01-01)
      We present the properties of all the galaxies detected by ISO at 7, 15 and 90μm in ELAIS northern fields. The spectral energy distribution (SED) of those 20 galaxies with IRAS detections can generally be well fitted by a ...
    • Spectroscopic properties of new IR galaxies detected in the european large area ISO survey 

      Cabrera-Guerra, F.; Pérez-Fournón, Ismaël; González-Solares, Eduardo A.; Fadda, Dario T.; González-Serrano, Ignacio; Rowan-Robinson, Michael; Serjeant, Stephen B.G.; Verma, Aprajita; Farrah, Duncan G.; Efstathiou, Andreas; Morel, Thierry; Surace, Christian; Oliver, Sebastian James; Ciliegi, Paolo; Pozzi, Francesca; Lari, Carlo; McMahon, R. G.; Willott, Chris J.; Vila-Vilaró, Baltasar; Mature, I.; LaFranca, F.; Héraudeau, Ph; Masegosa, J.; Márquez, I.; Gruppioni, Carlotta; Franceschini, Alberto; Flores, Hector (2001-01-01)
      We present preliminary results of multi-object spectroscopy of new mid-, and far-infrared selected galaxies detected in the European Large Area ISO Survey (ELAIS). The data have been obtained with the fibre spectrographs ...
    • On the average parallelism in trace monoids 

      Michos, Ioannis C.; Mairesse, Jean; Michos, Ioannis C. (2002-01-01)
    • Radiocolorings in periodic planar graphs: PSPACE-completeness and efficient approximations for the optimal range of frequencies 

      Fotakis, Dimitris A.; Nikoletseas., Sotiris E.; Lesta, Vicky Papadopoulou; Spirakis, Paul G. (2002-01-01)
      The Frequency Assignment Problem (FAP) in radio networks is the problem of assigning frequencies to transmitters exploiting frequency reuse while keeping signal interference to acceptable levels. The FAP is usually modelled ...
    • On radiocoloring hierarchically specified planar graphs: PSPACE-completeness and approximations 

      Andreou, Maria I.; Fotakis, Dimitris A.; Nikoletseas., Sotiris E.; Lesta, Vicky Papadopoulou; Spirakis, Paul G. (2002-01-01)
      Hierarchical specifications of graphs have been widely used in many important applications, such as VLSI design, parallel programming and software engineering. A well known hierarchical specification model, considered in ...
    • ISO photometry of hyperluminous infrared galaxies: Implications for the origin of their extreme luminosities 

      Verma, Aprajita; Rowan-Robinson, Michael; McMahon, R. G.; Efstathiou, Andreas (2003-02-01)
      We present 7-180μm photometry of a sample of hyperluminous infrared galaxies (HyLIGs) obtained with the photometer and camera mounted on the Infrared Space Observatory (ISO). We have used state-of-the-art' radiative transfer ...
    • The European large area ISO survey: 90 micron number counts 

      Héraudeau, Ph; Del Burgo, Carlos; Stickel, Manfred; Efstathiou, Andreas; Rowan-Robinson, Michael; Kiss, Cs S.; Ábrahám, Péter; Oliver, Sebastian James; Klaas, Ulrich; Lemke, Dietrich (2003-02-01)
      The European Large Area ISO Survey (ELAIS) was the largest single Open Time project conducted by ISO, mapping an area of 12 square degrees at 15 μm with ISOCAM and at 90μ with ISOPHOT. We first present the data analysis ...
    • Computing the average parallelism in trace monoids 

      Krob, Daniel; Mairesse, Jean; Michos, Ioannis C. (2003-12-11)
      The height of a trace is the height of the corresponding heap of pieces in Viennot's representation, or equivalently the number of factors in its Cartier-Foata decomposition. Let h(t) and |t| stand respectively for the ...
    • The development of a quality e-learning environment based on human, social, and cultural factors 

      Mavromoustakos, Stephanos M.; Papanikolaou, Katerina; Leonidou, Constantinos; Andreou, Andreas S. (2004-06-28)
      A methodology called MATHISI, for developing a quality e-learning environment based on human, social and cultural factors is presented. The three axons on which it is based are the country characteristics in which it will ...
    • A review of evolutionary multiobjective optimization applications in the area of production research 

      Dimopoulos, Christos (2004-09-13)
      Evolutionary computation methods have been used extensively in the past for the solution of manufacturing optimization problems. This paper examines the impact of the fast-growing evolutionary multiobjective optimization ...
    • SED models of AGN 

      Siebenmorgen, Ralf; Efstathiou, Andreas (2005-04-11)
      Present AGN models aiming to account for the observed infrared SEDs consider a physical description of the dust and a solution of the radiative transfer problem. Mid infrared spectra obtained at different spatial scales ...
    • Radiocoloring in planar graphs: Complexity and approximations 

      Fotakis, Dimitris A.; Nikoletseas., Sotiris E.; Lesta, Vicky Papadopoulou; Spirakis, Paul G. (2005-08-31)
      The Frequency Assignment Problem (FAP) in radio networks is the problem of assigning frequencies to transmitters, by exploiting frequency reuse while keeping signal interference to acceptable levels. The FAP is usually ...
    • Generating and radiocoloring families of perfect graphs 

      Andreou, Maria I.; Lesta, Vicky Papadopoulou; Spirakis, Paul G.; Theodorides, B.; Xeros, Andreas (2005-09-27)
      In this work we experimentally study the min order Radiocoloring problem (RCP) on Chordal, Split and Permutation graphs, which are three basic families of perfect graphs. This problem asks to find an assignment using the ...
    • Effect of antenna beam pattern and layout on cellular performance in high altitude platform communications 

      Thornton, John; Pearce, David Anthony J.; Grace, David; Oodo, Masayuki; Katzis, Konstantinos; Tozer, Timothy C. (2005-10-01)
      High Altitude Platforms may offer high spectrum efficiency by deploying multi-beam, multi-cell communications networks. The properties of the antennas carried by the HAP payload are key to the effective exploitation of ...