315,281 research outputs found

    Engineering a Conformant Probabilistic Planner

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    We present a partial-order, conformant, probabilistic planner, Probapop which competed in the blind track of the Probabilistic Planning Competition in IPC-4. We explain how we adapt distance based heuristics for use with probabilistic domains. Probapop also incorporates heuristics based on probability of success. We explain the successes and difficulties encountered during the design and implementation of Probapop

    The Precise Formula in a Sine Function Form of the norm of the Amplitude and the Necessary and Sufficient Phase Condition for Any Quantum Algorithm with Arbitrary Phase Rotations

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    In this paper we derived the precise formula in a sine function form of the norm of the amplitude in the desired state, and by means of he precise formula we presented the necessary and sufficient phase condition for any quantum algorithm with arbitrary phase rotations. We also showed that the phase condition: identical rotation angles, is a sufficient but not a necessary phase condition.Comment: 16 pages. Modified some English sentences and some proofs. Removed a table. Corrected the formula for kol on page 10. No figure

    Template epitaxial growth of thermoelectric Bi/BiSb superlattice nanowires by charge-controlled pulse electrodeposition

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    © The Electrochemical Society, Inc. 2009. All rights reserved. Except as provided under U.S. copyright law, this work may not be reproduced, resold, distributed, or modified without the express permission of The Electrochemical Society (ECS). The archival version of this work was published in The Journal of The Electrochemical Society, 156(9), 2009.Bi/BiSb superlattice nanowires (SLNWs) with a controllable and very small bilayer thickness and a sharp segment interface were grown by adopting a charge-controlled pulse electrodeposition. The deposition parameters were optimized to ensure an epitaxial growth of the SLNWs with a preferential orientation. The segment length and bilayer thickness of the SLNWs can be controlled simply by changing the modulating time, and the consistency of the segment length can be well maintained by our approach. The Bravais law in the electrodeposited nanowires is verified by the SLNW structure. The current–voltage measurement shows that the SLNWs have good electrical conductance, particularly those with a smaller bilayer thickness. The Bi/BiSb SLNWs might have excellent thermoelectric performances.National Natural Science Foundation of China and the National Major Project of Fundamental Research for Nanomaterials and Nanostructures

    Superconductivity at 41 K and its competition with spin-density-wave instability in layered CeO1x_{1-x}Fx_xFeAs

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    A series of layered CeO1x_{1-x}Fx_xFeAs compounds with x=0 to 0.20 are synthesized by solid state reaction method. Similar to the LaOFeAs, the pure CeOFeAs shows a strong resistivity anomaly near 145 K, which was ascribed to the spin-density-wave instability. F-doping suppresses this instability and leads to the superconducting ground state. Most surprisingly, the superconducting transition temperature could reach as high as 41 K. The very high superconducting transition temperature strongly challenges the classic BCS theory based on the electron-phonon interaction. The very closeness of the superconducting phase to the spin-density-wave instability suggests that the magnetic fluctuations play a key role in the superconducting paring mechanism. The study also reveals that the Ce 4f electrons form local moments and ordered antiferromagnetically below 4 K, which could coexist with superconductivity.Comment: 4 pages, 5 figure

    Thermal Hall Conductivity as a Probe of Gap Structure in Multi-band Superconductors: The Case of Ba1xKxFe2As2\rm Ba_{1-x}K_xFe_2As_2

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    The sign and profile of the thermal Hall conductivity κxy\kappa_{xy} gives important insights into the gap structure of multi-band superconductors. With this perspective, we have investigated κxy\kappa_{xy} and the thermal conductivity κxx\kappa_{xx} in Ba1xKxFe2As2\rm Ba_{1-x}K_xFe_2As_2 which display large peak anomalies in the superconducting state. The anomalies imply that a large hole-like quasiparticle (qp) population exists below the critical temperature TcT_c. We show that the qp mean-free-path inferred from κxx\kappa_{xx} reproduces the observed anomaly in κxy\kappa_{xy}, providing a consistent estimate of a large qp population. Further, we demonstrate that the hole-like signal is consistent with a theoretical scenario where despite potentially large gap variations on the electron pockets, the minimal homogeneous gap of the superconducting phase resides at a hole pocket. Implications for probing the gap structure in the broader class of pnictide superconductors are discussed.Comment: 5 pages, 4 figures. Orientation significantly updated from previous (0811.4668v1) reflecting new theoretical understanding of experimental results and physical implications. Introduction, discussion, and figures updated including additional figure for model calculatio

    A General SU(2) Formulation for Quantum Searching with Certainty

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    A general quantum search algorithm with arbitrary unitary transformations and an arbitrary initial state is considered in this work. To serach a marked state with certainty, we have derived, using an SU(2) representation: (1) the matching condition relating the phase rotations in the algorithm, (2) a concise formula for evaluating the required number of iterations for the search, and (3) the final state after the search, with a phase angle in its amplitude of unity modulus. Moreover, the optimal choices and modifications of the phase angles in the Grover kernel is also studied.Comment: 8 pages, 2 figure

    Gravitational lensing effects on sub-millimetre galaxy counts

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    We study the effects on the number counts of sub-millimetre galaxies due to gravitational lensing. We explore the effects on the magnification cross section due to halo density profiles, ellipticity and cosmological parameter (the power-spectrum normalisation σ8\sigma_8). We show that the ellipticity does not strongly affect the magnification cross section in gravitational lensing while the halo radial profiles do. Since the baryonic cooling effect is stronger in galaxies than clusters, galactic haloes are more concentrated. In light of this, a new scenario of two halo population model is explored where galaxies are modeled as a singular isothermal sphere profile and clusters as a Navarro, Frenk and White (NFW) profile. We find the transition mass between the two has modest effects on the lensing probability. The cosmological parameter σ8\sigma_8 alters the abundance of haloes and therefore affects our results. Compared with other methods, our model is simpler and more realistic. The conclusions of previous works is confirm that gravitational lensing is a natural explanation for the number count excess at the bright end.Comment: 10 pages, 10 figures, accepted by MNRA

    X-ray and EUV spectroscopy of various astrophysical and laboratory plasmas -- Collisional, photoionization and charge-exchange plasmas

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    Several laboratory facilities were used to benchmark theoretical spectral models those extensively used by astronomical communities. However there are still many differences between astrophysical environments and laboratory miniatures that can be archived. Here we setup a spectral analysis system for astrophysical and laboratory (SASAL) plasmas to make a bridge between them, and investigate the effects from non-thermal electrons, contribution from metastable level-population on level populations and charge stage distribution for coronal-like, photoionized, and geocoronal plasmas. Test applications to laboratory measurement (i.e. EBIT plasma) and astrophysical observation (i.e. Comet, Cygnus X-3) are presented. Time evolution of charge stage and level population are also explored for collisional and photoionized plasmas.Comment: 11 Figures, 3 Tables, Accepted by ApJ on Jan. 23, 2014. Astrophysical Journal 201
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