The stochastic bid generation problem in combinatorial transportation auctions

In this paper, we deal with the generation of bundles of loads to be submitted by carriers participating in combinatorial auctions in the context of long-haul full truckload transportation services. We develop a probabilistic optimization model that integrates the bid generation and pricing problems together with the routing of the carrier’s fleet. We propose two heuristic procedures that enable us to solve models with up to 400 auctioned loads

<span style="font-size:10.0pt;font-family: "Times New Roman";mso-fareast-font-family:"Times New Roman";mso-bidi-font-family: Mangal;mso-ansi-language:EN-US;mso-fareast-language:EN-US;mso-bidi-language: HI" lang="EN-US">Structural study of C₂D₆ thin films adsorbed on MgO (100)</span>

748-752The structure of C2D6 thin films adsorbed on high homogeneous MgO (100) powder surface have been investigated by means of neutron diffraction techniques at 10 K. Neutron diffraction spectra have been recorded for three different coverages. Two bi-dimensional solids S1 and S2 have been determined, respectively for a coverage θ =0.7 layer and θ =1.2 layer. In agreement with LEED measurement,<span style="mso-ansi-language: EN-US" lang="EN-US"> the S2 phase presents the commensurability C(x2)R45° with the MgO (100) surface. The S1 phase also presents a commensurate structure with the substrate lattice but its commensurability is weaker than that of S2. The (2D) solid phase, measured at an intermediate coverage θ =1.0 layer is a mixture of S1 and S2. For both solid phases, unit cell, location and orientation of molecules within are determined. The commensurate cell of the S1 solid with the MgO (100) surface is given. </span

Influence of anionic vacancies on the conductivity of La 9.33Si6-xAlxO26-x/2 oxide conductors with an oxyapatite structure

Al-doped oxyapatite-type lanthanum silicates La9.33Si 6-xAlxO26-x/2□x/2 (x = 0, 0.4, 0.8 and 1) powders have been prepared by the solid state reaction at high temperature in order to determine the influence of anionic vacancies on the electrical properties of the material. The crystal structure and properties of La9.33Si6-xAlxO 26-x/2□x/2 powders have been studied by X-ray diffraction (XRD) patterns, magic-angle spinning nuclear magnetic resonance (MAS-NMR) technique and complex impedance analysis. All the compounds of La 9.33Si6-xAlxO 26-x/2□x/2 oxyapatites doped with Al3+ consist of a hexagonal structure with a P63/m space group. Lanthanum silicates doped with trivalent Al3+ have a higher conductivity than those without trivalent Al3+ at the Si4+ site. The extra oxygen O(4) atoms in site 2a (0, 0, 0.25) occupy channels running through the structure that are responsible for the high oxygen ion conduction. However, Al substitution seems to produce oxygen vacancies and create another pathway for oxide ions. The expansion of the channels (La(1)-O(4) distance) leads to an increase in the conductivity. For the best sample (x = 1), the conductivity observed was 5 × 10-3 S cm-1 at 750 °C. © 2014 Published by Elsevier B.V.This work was supported by Spanish Agency of International Cooperation (AECI-B/026856/09).Peer Reviewe

Structural aspects that enhance oxygen mobility in La9-2 x/3Mn0.5 REx□0.5-x/3(SiO4)6O 2 with RE = Ca, Sr and Ba

Oxyapatite-type silicates, La9-2x/3Mn 0.5 REx□0.5-x /3(SiO4)6O2 (x = 0.5; RE = Ca, Sr and Ba), were prepared by a high temperature solid-state reaction. Structure and unit-cell parameters were deduced from the analysis of X-ray powder diffraction data. Le Bail refinement of the X-ray powder diffraction data showed that the compounds have a hexagonal cell (P 63/m space group). The electrical properties of the materials were studied using the ac impedance spectroscopy technique. The extra oxygen O(4) atoms in site 2a (0, 0, 0.25) occupy channels running through the structure that are responsible for the high oxygen ion conduction. The presence of cation vacancies should enhance oxygen hopping along the c-axis; however, the analysis of the frequency dependence of ac conductivity suggests that oxygen motions are produced along three axes. The n-factor value of the dimensionality of the oxide ions increases with the conductivity when the size of RE cation decreases. © 2014 Elsevier B.V. All rights reserved.Peer Reviewe

Minimum power multicasting in wireless networks under probabilistic node failures

Minimum power multicasting, Probabilistic mathematical models, Multihop networks,