627 research outputs found

    Intelligent planning for allocating containers in maritime terminals

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    Maritime container terminals are facilities where cargo containers are transshipped between ships or between ships and land vehicles (tucks or trains). These terminals involve a large number of complex and combinatorial problems. One of them is related to the Container Stacking Problem. A container yard is a type of temporary store where containers await further transport by truck, train or vessel. The main efficiency problem for an individual stack is to ensure easy access to containers at the expected time of transfer. Stacks are 'last-in, first-out' storage structures where containers are stocked in the order they arrive. But they should be retrieved from the stack in the order (usually different) they should be shipped. This retrieval operation should be efficiently performed, since berthing time of vessels and the terminal operations should be optimized. To do this, cranes can relocate containers in the stacks to minimize the rearrangements required to meet the expected order of demand for containers. In this paper, we present a domain-dependent heuristically guided planner for obtaining the optimized reshuffling plan, given a stacking state and a container demand. The planner can also be used for finding the best allocation of containers in a yard-bay in order to minimize the number of reshuffles as well as to be used for simulation tasks and obtaining conclusions about possible yard configurations. © 2011 Elsevier Ltd. All rights reserved.This work has been partially supported by the research projects TIN2010-20976-C02-01 (Min. de Ciencia e Innovacion, Spain), P19/08 (Min. de Fomento, Spain-FEDER) and the VALi+d Program of the Conselleria d'Educacio (Generalitat Valenciana), as well as with the collaboration of the maritime container terminal MSC (Mediterranean Shipping Company S.A.).Rodríguez Molins, M.; Salido Gregorio, MA.; Barber Sanchís, F. (2012). Intelligent planning for allocating containers in maritime terminals. Expert Systems with Applications. 39(1):978-989. https://doi.org/10.1016/j.eswa.2011.07.098S97898939

    Nucleonic resonance excitations with linearly polarized photon in γpωp\gamma p\to \omega p

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    In this work, an improved quark model approach to the ω\omega meson photo-production with an effective Lagrangian is presented. The {\it t}-channel {\it natural}-parity exchange is taken into account through the Pomeron exchange, while the {\it unnatural}-parity exchange is described by the π0\pi^0 exchange. With a very limited number of parameters, the available experimental data in the low energy regime can be consistently accounted for. We find that the beam polarization observables show sensitivities to some {\it s}-channel individual resonances in the SU(6)O(3)SU(6)\otimes O(3) quark model symmetry limit. Especially, the two resonances P13(1720)P_{13}(1720) and F15(1680)F_{15}(1680), which belong to the representation [56,28,2,2,J][{\bf 56, ^2 8}, 2, 2, J], have dominant contributions over other excited states. Concerning the essential motivation of searching for "missing resonances" in meson photo-production, this approach provides a feasible framework, on which systematic investigations can be done.Comment: 16 pages, Revtex, 9 eps figures, to appear in PR

    Systematic Regge theory analysis of omega photoproduction

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    Systematic analysis of available data for ω\omega-meson photoproduction is given in frame of Regge theory. At photon energies above 20 GeV the γ+pω+p\gamma{+}p{\to}\omega{+}p reaction is entirely dominated by Pomeron exchange. However, it was found that Pomeron exchange model can not reproduce the γ+pρ+p\gamma{+}p{\to}\rho{+}p and γ+pω+p\gamma{+}p{\to}\omega{+}p data at high energies simultaneously with the same set of parameters. The comparison between ρ\rho and ω\omega data indicates a large room for meson exchange contribution to ω\omega-meson photoproduction at low energies. It was found that at low energies the dominant contribution comes from π\pi and f2f_2-meson exchanges. There is smooth transition between the meson exchange model at low energies and Regge theory at high energies.Comment: 7 pages, 8 figures, revtex

    The abolition of the General Teaching Council for England and the future of teacher discipline

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    With the abolition of the General Teaching Council for England in the 2011 Education Act, this article considers the future of teacher discipline in England. It provides a critique of the changes to the regulation of teacher misconduct and incompetence that draws on a Foucauldian framework, especially concerning the issue of public displays of discipline and the concomitant movement to more hidden forms. In addition, the external context of accountability that accompanies the reforms to teacher discipline are considered including the perfection of the panoptic metaphor presented by the changes to Ofsted practices such as the introduction of zero-notice inspections. The article concludes that the reforms will further move teachers from being occupational professionals to being organisational professionals marking them apart from comparable professions in medicine and law

    A Sucrose Solution Application to the Study of Model Biological Membranes

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    The small-angle X-ray and neutron scattering, time resolved X-ray small-angle and wide-angle diffraction coupled with differential scanning calorimetry have been applied to the investigation of unilamellar and multilamellar dimyristoylphosphatidylcholine (DMPC) vesicles in sucrose buffers with sucrose concentrations from 0 to 60%. Sucrose buffer decreased vesicle size and polydispersity and increased an X-ray contrast between phospholipid membrane and bulk solvent sufficiently. No influence of sucrose on the membrane thickness or mutual packing of hydrocarbon chains has been detected. The region of sucrose concentrations 30%-40% created the best experimental conditions for X-ray small-angle experiments with phospholipid vesicles.Comment: PDF: 10 pages, 6 figures. MS Word sours

    Density Matrix Renormalisation Group Approach to the Massive Schwinger Model

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    The massive Schwinger model is studied, using a density matrix renormalisation group approach to the staggered lattice Hamiltonian version of the model. Lattice sizes up to 256 sites are calculated, and the estimates in the continuum limit are almost two orders of magnitude more accurate than previous calculations. Coleman's picture of `half-asymptotic' particles at background field theta = pi is confirmed. The predicted phase transition at finite fermion mass (m/g) is accurately located, and demonstrated to belong in the 2D Ising universality class.Comment: 38 pages, 18 figures, submitted to PR

    Trust Building in Electronic Markets: Relative Importance and Interaction Effects of Trust Building Mechanisms

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    We examine the relative and complementary effectiveness of trust-building strategies in online environments. While prior research has examined various antecedents to trust, we investigated two trust-building mechanisms more in depth: Web site trust and vendor reputation. We tried to understand the relative effectiveness of these two important mechanisms to provide online businesses with a clear recommendation of how to establish trust in an effective and efficient manner. Drawing from the literature on trust, we proposed vendor reputation to be more effective than Web site trust. Moreover, we examined a potential complementary effect of these mechanisms so as to provide online businesses with a deeper understanding of how to derive superior trust. We hypothesize a small such effect. The study proposes a laboratory experiment to test the model

    Quantum Computing and Quantum Simulation with Group-II Atoms

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    Recent experimental progress in controlling neutral group-II atoms for optical clocks, and in the production of degenerate gases with group-II atoms has given rise to novel opportunities to address challenges in quantum computing and quantum simulation. In these systems, it is possible to encode qubits in nuclear spin states, which are decoupled from the electronic state in the 1^1S0_0 ground state and the long-lived 3^3P0_0 metastable state on the clock transition. This leads to quantum computing scenarios where qubits are stored in long lived nuclear spin states, while electronic states can be accessed independently, for cooling of the atoms, as well as manipulation and readout of the qubits. The high nuclear spin in some fermionic isotopes also offers opportunities for the encoding of multiple qubits on a single atom, as well as providing an opportunity for studying many-body physics in systems with a high spin symmetry. Here we review recent experimental and theoretical progress in these areas, and summarise the advantages and challenges for quantum computing and quantum simulation with group-II atoms.Comment: 11 pages, 7 figures, review for special issue of "Quantum Information Processing" on "Quantum Information with Neutral Particles
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