12,317 research outputs found

    Self Interference of Single Electrodynamic Particle in Double Slit

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    It is by the long established fact in experiment and theory that electromagnetic waves, here as one component of an IED particle, passing a double slit will undergo self inference each, producing at a detector plane fringed intensities. The wave generating point charge of a zero rest mass, as the other component of the particle, is maintained a constant energy and speed by a repeated radiation reabsorption/reemission scheme, and in turn steered in direction in its linear motion by the reflected radiation field, and will thereby travel to the detector along (one of) the optical path(s) of the waves leading to a bright interference fringe. We elucidate the process formally based on first principles solutions for the IED particle and known principles for wave-matter interaction.Comment: Presentation at The 6th Int. Symp. Quantum Theory and Symmetries, Univ. Kent, 2009

    Choreograthons: Hackathons for Dance

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    date-added: 2015-03-24 04:16:59 +0000 date-modified: 2015-03-24 04:16:59 +0000date-added: 2015-03-24 04:16:59 +0000 date-modified: 2015-03-24 04:16:59 +0000This work was supported by the Arts and Humanities Research Council, CreativeWorks London Hub, grant AH/J005142/1, and the European Regional Development Fund, London Creative and Digital Fusion

    Spontaneous Aharonov-Casher effect of neutral hard-core bosons in one-dimensional mesoscopic rings

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    Using a tight-binding model Hamiltonian and applying the Jordan-Wigner transformation, we have investigated the Aharonov-Casher (AC) effect for many neutral hard-core bosons in one-dimensional (1D) mesoscopic rings with the self-induced AC phase included. The total energy and the persistent fluxon current are analytically derived for 1D perfect lattices. More importantly, it is suggested that, in the absence of the external AC flux, the self-sustained AC flux state could be the ground state of a system with weak disorder. The possibility of experimenal observations is briefly discussed. © 1995 The American Physical Society.published_or_final_versio

    Cost effective and sustainable? Photovoltaic (PV) rebate program in Australia

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    The Australian Government has recently announced a Renewable Energy Target (RET) scheme to provide up front payments of 8,000foraround25,250householdsofincomelessthan8,000 for around 25,250 households of income less than 100,000 per year installing a 150 watt solar panel system starting on 01 July 2009 using 202milliontaxpayersmoney.Theschemehasnotincludedhouseholdswithincomesgreaterthan202 million taxpayers' money. The scheme has not included households' with incomes greater than 100,000, nor developers who produce new houses. Whether the policies are effective and sustainable is arguable. This paper examines policies designed to encourage households to install solar panel system in Australia and demonstrates reasons for supporting developers to build green houses using Net Present Value (NPV) analysis in a case study. The findings suggest that the government should support installation of solar systems by both households and the developers. ©2009 IEEE

    Supercurrent determined from the Aharonov-Bohm effect in mesoscopic superconducting rings

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    We have solved the Bogoliubov-de Gennes equation for a clean, one-dimensional mesoscopic superconducting ring threaded by a magnetic flux Φ. We show that the superfluid velocity is driven directly by Φ while the relative motion of the pair of electrons is independent of Φ. Meanwhile, the fluxoid quantization is obtained straightforwardly. More importantly, we have also calculated the supercurrent numerically and self-consistently and find it is periodic in Φ with the period Φshc/2e for Φs≤Φd=(mvdL/ Latin small letter h with strokeπ)Φs and with the period Φ0hc/e for Φd<Φs, which arises from mesoscopic effects. © 1994 The American Physical Society.published_or_final_versio

    Vortex states in iron-based superconductors with collinear antiferromagnetic cores

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    Magnetism in the FeAs stoichiometric compounds and its interplay with superconductivity in vortex states are studied by self-consistently solving the Bogoliubov-de Gennes equations based on a two-orbital model with including the on-site interactions between electrons in the two orbitals. It is revealed that for the parent compound, magnetism is caused by the strong Hund's coupling, and the Fermi-surface topology aids to select the spin-density-wave (SDW) pattern. The superconducting (SC) order parameter with s± = Δ0 cos (kx) cos (ky) symmetry is found to be the most favorable pairing for both the electron- and hole-doped cases while the local density of states exhibits the characteristic of nodal gap for the former and full gap for the latter. In the vortex state, the emergence of the field-induced SDW depends on the strength of the Hund's coupling and the Coulomb repulsions. The field-induced SDW gaps the finite-energy contours on the electron- and hole-pocket sides, leading to the dual structures with one reflecting the SC pairing and the other being related to the SDW order. These features can be discernable in STM measurements for identifying the interplay between the field-induced SDW order and the SC order around the core region. © 2009 The American Physical Society.published_or_final_versio

    Leveraging graph dimensions in online graph search

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    Graphs have been widely used due to its expressive power to model complicated relationships. However, given a graph database DG = {g1; g2; ··· , gn}, it is challenging to process graph queries since a basic graph query usually involves costly graph operations such as maximum common subgraph and graph edit distance computation, which are NP-hard. In this paper, we study a novel DS-preserved mapping which maps graphs in a graph database DG onto a multidimensional space MG under a structural dimension Musing a mapping function φ(). The DS-preserved mapping preserves two things: distance and structure. By the distance-preserving, it means that any two graphs gi and gj in DG must map to two data objects φ(gi) and φ(gj) in MG, such that the distance, d(φ(gi); φ(gj), between φ(gi) and φ(gj) in MG approximates the graph dissimilarity δ(gi; gj) in DG. By the structure-preserving, it further means that for a given unseen query graph q, the distance between q and any graph gi in DG needs to be preserved such that δ(q; gi) ≈ d(φ(q); φ(gi)). We discuss the rationality of using graph dimension M for online graph processing, and show how to identify a small set of subgraphs to form M efficiently. We propose an iterative algorithm DSPM to compute the graph dimension, and discuss its optimization techniques. We also give an approximate algorithm DSPMap in order to handle a large graph database. We conduct extensive performance studies on both real and synthetic datasets to evaluate the top-k similarity query which is to find top-k similar graphs from DG for a query graph, and show the effectiveness and efficiency of our approaches. © 2014 VLDB

    Sea-level constraints on the amplitude and source distribution of Meltwater Pulse 1A.

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    During the last deglaciation, sea levels rose as ice sheets retreated. This climate transition was punctuated by periods of more intense melting; the largest and most rapid of these—Meltwater Pulse 1A—occurred about 14,500 years ago, with rates of sea-level rise reaching approximately 4 m per century1, 2, 3. Such rates of rise suggest ice-sheet instability, but the meltwater sources are poorly constrained, thus limiting our understanding of the causes and impacts of the event4, 5, 6, 7. In particular, geophysical modelling studies constrained by tropical sea-level records1, 8, 9 suggest an Antarctic contribution of more than seven metres, whereas most reconstructions10 from Antarctica indicate no substantial change in ice-sheet volume around the time of Meltwater Pulse 1A. Here we use a glacial isostatic adjustment model to reinterpret tropical sea-level reconstructions from Barbados2, the Sunda Shelf3 and Tahiti1. According to our results, global mean sea-level rise during Meltwater Pulse 1A was between 8.6 and 14.6 m (95% probability). As for the melt partitioning, we find an allowable contribution from Antarctica of either 4.1 to 10.0 m or 0 to 6.9 m (95% probability), using two recent estimates11, 12 of the contribution from the North American ice sheets. We conclude that with current geologic constraints, the method applied here is unable to support or refute the possibility of a significant Antarctic contribution to Meltwater Pulse 1A

    Persistent current in disordered Aharonov-Bohm rings with interacting electrons

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    The role of repulsive on-site and nearest-neighbor Coulomb interactions in disordered half-filled Aharanov-Bohm rings is studied by world-line quantum Monte Carlo simulations. The diverse dependence of the equilibrium persistent current on the couplings is found to relate systematically to the magnetic phase of the model: the maximum charge stiffness (or the persistent current) coexists with the phase-transition line between the dominant charge-density-wave state and the dominant spin-density-wave state. The stiffness vanishes with an increasing departure from the transition line. Thus in the disordered rings the Coulomb interactions can enhance the charge stiffness over the noninteracting limit in such a way as to drive the system toward the phase-transition regime.published_or_final_versio

    Dissipation function of the first-order phase transformation in VO2 ceramics by internal-friction measurements

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    In order to apply the concept of the dissipation function during the first-order phase transition (FOPT) in solids, we measured the internal friction Q-1 and shear modulus μ for a range of frequencies of polycrystalline ceramics VO2 as the sample passed through a FOPT across the temperature range of 300–420 K. The experiment was repeated for different temperature variation rate Ṫ. We have found that for each frequency, a maximum of Q-1 and a minimum of μ occurred at the same temperature Tp when Ṫ was kept constant. The numerical values of the dissipation function ΔGR plus other FOPT parameters have been deduced using Q-1 data. The general trend of ΔGR-T and other results are found to be consistent with known physical aspects.published_or_final_versio
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