10,988 research outputs found

    Dependence of heat transport on the strength and shear rate of prescribed circulating flows

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    We study numerically the dependence of heat transport on the maximum velocity and shear rate of physical circulating flows, which are prescribed to have the key characteristics of the large-scale mean flow observed in turbulent convection. When the side-boundary thermal layer is thinner than the viscous boundary layer, the Nusselt number (Nu), which measures the heat transport, scales with the normalized shear rate to an exponent 1/3. On the other hand, when the side-boundary thermal layer is thicker, the dependence of Nu on the Peclet number, which measures the maximum velocity, or the normalized shear rate when the viscous boundary layer thickness is fixed, is generally not a power law. Scaling behavior is obtained only in an asymptotic regime. The relevance of our results to the problem of heat transport in turbulent convection is also discussed.Comment: 7 pages, 7 figures, submitted to European Physical Journal

    A Hybrid Quantum Encoding Algorithm of Vector Quantization for Image Compression

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    Many classical encoding algorithms of Vector Quantization (VQ) of image compression that can obtain global optimal solution have computational complexity O(N). A pure quantum VQ encoding algorithm with probability of success near 100% has been proposed, that performs operations 45sqrt(N) times approximately. In this paper, a hybrid quantum VQ encoding algorithm between classical method and quantum algorithm is presented. The number of its operations is less than sqrt(N) for most images, and it is more efficient than the pure quantum algorithm. Key Words: Vector Quantization, Grover's Algorithm, Image Compression, Quantum AlgorithmComment: Modify on June 21. 10pages, 3 figure

    Geology orbiter comparison study

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    Instrument requirements of planetary geology orbiters were examined with the objective of determining the feasibility of applying standard instrument designs to a host of terrestrial targets. Within the basic discipline area of geochemistry, gamma-ray, X-ray fluorescence, and atomic spectroscopy remote sensing techniques were considered. Within the discipline area of geophysics, the complementary techniques of gravimetry and radar were studied. Experiments using these techniques were analyzed for comparison at the Moon, Mercury, Mars and the Galilean satellites. On the basis of these comparative assessments, the adaptability of each sensing technique was judged as a basic technique for many targets, as a single instrument applied to many targets, as a single instrument used in different mission modes, and as an instrument capability for nongeoscience objectives

    Quantum integrable system with two color components in two dimensions

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    The Davey-Stewartson 1(DS1) system[9] is an integrable model in two dimensions. A quantum DS1 system with 2 colour-components in two dimensions has been formulated. This two-dimensional problem has been reduced to two one-dimensional many-body problems with 2 colour-components. The solutions of the two-dimensional problem under consideration has been constructed from the resulting problems in one dimensions. For latters with the δ\delta -function interactions and being solved by the Bethe ansatz, we introduce symmetrical and antisymmetrical Young operators of the permutation group and obtain the exact solutions for the quantum DS1 system. The application of the solusions is discussed.Comment: 14 pages, LaTeX fil

    Tramp Ship Scheduling Problem with Berth Allocation Considerations and Time-dependent Constraints

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    This work presents a model for the Tramp Ship Scheduling problem including berth allocation considerations, motivated by a real case of a shipping company. The aim is to determine the travel schedule for each vessel considering multiple docking and multiple time windows at the berths. This work is innovative due to the consideration of both spatial and temporal attributes during the scheduling process. The resulting model is formulated as a mixed-integer linear programming problem, and a heuristic method to deal with multiple vessel schedules is also presented. Numerical experimentation is performed to highlight the benefits of the proposed approach and the applicability of the heuristic. Conclusions and recommendations for further research are provided.Comment: 16 pages, 3 figures, 5 tables, proceedings paper of Mexican International Conference on Artificial Intelligence (MICAI) 201

    Some recent progress on quark pairings in dense quark and nuclear matter

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    We give a brief overview on some recent progress in quark pairings in dense quark/nuclear matter mostly developed in the past five years. We focus on following aspects in particular: the BCS-BEC crossover in the CSC phase, the baryon formation and dissociation in dense quark/nuclear matter, the Ginzburg-Landau theory for three-flavor dense matter with UAU_{A}(1) anomaly, and the collective and Nambu-Goldstone modes for the spin-one CSC.Comment: RevTex 4, 25 pages, 9 figures, presented for the KITPC (Kavli Institute for Theoretical Physics China) program "AdS/CFT and Novel Approaches to Hadron and Heavy Ion Physics' in Oct. 11- Dec. 3, 201

    Gait Difficulty, Postural Instability, and Muscle Weakness Are Associated with Fear of Falling in People with Parkinson's Disease

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    The present study aimed to examine the contribution of gait impairment, postural stability and muscle weakness to the level of fear of falling in people with Parkinson's disease (PD). Fifty-seven community-dwelling individuals with PD completed the study. Fear of falling was assessed by the Activities-specific Balance Confidence (ABC) scale. Postural stability and gait difficulty were determined by the posture and gait subscores of the Unified Parkinson's Disease Rating Scale (UPDRS-PG). A Cybex dynamometer was used to measure isokinetic knee muscle strength. Individuals with PD achieved a mean ABC score of 73.6 ± 19.3. In the multiple regression analysis, after accounting for basic demographics, fall history and disease severity, the UPDRS-PG score remained independently associated with the ABC score, accounting for 13.4% of the variance (P < 0.001). The addition of knee muscle strength significantly improved the prediction model and accounted for an additional 7.3% of the variance in the ABC score (P < 0.05). This is the first study to demonstrate that the UPDRS-PG score and knee muscle strength are important and independent determinants of the level of fear of falling in individuals with PD. Improving balance, gait stability and knee muscle strength could be crucial in promoting balance confidence in the appropriately targeted PD population

    Superconducting and normal-state interlayer-exchange-coupling in La0.67_{0.67}Sr0.33_{0.33}MnO3{3}-YBa2_{2}Cu3_{3}O7La_{7}-La_{0.67}SrSr_{0.33}MnO MnO{3}$ epitaxial trilayers

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    The issue of interlayer exchange coupling in magnetic multilayers with superconducting (SC) spacer is addressed in La0.67_{0.67}Sr0.33_{0.33}MnO3_{3} (LSMO) - YBa2_{2}Cu3_{3}O7_{7} (YBCO) - La0.67_{0.67}Sr0.33_{0.33}MnO3_{3} (LSMO) epitaxial trilayers through resistivity, ac-susceptibility and magnetization measurements. The ferromagnetic (FM) LSMO layers possessing in-plane magnetization suppress the critical temperature (Tc)_{c}) of the c-axis oriented YBCO thin film spacer. The superconducting order, however, survives even in very thin layers (thickness dY_{Y} \sim 50 {\AA}, \sim 4 unit cells) at T << 25 K. A predominantly antiferromagnetic (AF) exchange coupling between the moments of the LSMO layers at fields << 200 Oe is seen in the normal as well as the superconducting states of the YBCO spacer. The exchange energy J1_{1} (\sim 0.08 erg/cm2^{2} at 150 K for dY_{Y} = 75 {\AA}) grows on cooling down to Tc_{c}, followed by truncation of this growth on entering the superconducting state. The coupling energy J1_{1} at a fixed temperature drops exponentially with the thickness of the YBCO layer. The temperature and dY_{Y} dependencies of this primarily non-oscillatory J1_{1} are consistent with the coupling theories for systems in which transport is controlled by tunneling. The truncation of the monotonic T dependence of J1_{1} below Tc_{c} suggests inhibition of single electron tunneling across the CuO2_{2} planes as the in-plane gap parameter acquires a non-zero value.Comment: Accepted for publication in Phys. Rev.
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