9,773 research outputs found

    Gauge-invariant implementation of the Abelian Higgs model on optical lattices

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    We present a gauge-invariant effective action for the Abelian Higgs model (scalar electrodynamics) with a chemical potential μ\mu on a 1+1 dimensional lattice. This formulation provides an expansion in the hopping parameter κ\kappa which we test with Monte Carlo simulations for a broad range of the inverse gauge coupling βpl\beta_{pl} and small values of the scalar self-coupling λ\lambda. In the opposite limit of infinitely large λ\lambda, the partition function can be written as a traced product of local tensors which allows us to write exact blocking formulas. Their numerical implementation requires truncations but there is no sign problem for arbitrary values of μ\mu. We show that the time continuum limit of the blocked transfer matrix can be obtained numerically and, in the limit of infinite βpl\beta_{pl} and with a spin-1 truncation, the small volume energy spectrum is identical to the low energy spectrum of a two-species Bose-Hubbard model in the limit of large onsite repulsion. We extend this procedure for finite βpl\beta_{pl} and derive a spin-1 approximation of the Hamiltonian. It involves new terms corresponding to transitions among the two species in the Bose-Hubbard model. We propose an optical lattice implementation involving a ladder structure.Comment: 10 pages, 9 figure

    Systematic investigation of the rotational bands in nuclei with Z≈100Z \approx 100 using a particle-number conserving method based on a cranked shell model

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    The rotational bands in nuclei with Z≈100Z \approx 100 are investigated systematically by using a cranked shell model (CSM) with the pairing correlations treated by a particle-number conserving (PNC) method, in which the blocking effects are taken into account exactly. By fitting the experimental single-particle spectra in these nuclei, a new set of Nilsson parameters (κ\kappa and μ\mu) and deformation parameters (ε2\varepsilon_2 and ε4\varepsilon_4) are proposed. The experimental kinematic moments of inertia for the rotational bands in even-even, odd-AA and odd-odd nuclei, and the bandhead energies of the 1-quasiparticle bands in odd-AA nuclei, are reproduced quite well by the PNC-CSM calculations. By analyzing the ω\omega-dependence of the occupation probability of each cranked Nilsson orbital near the Fermi surface and the contributions of valence orbitals in each major shell to the angular momentum alignment, the upbending mechanism in this region is understood clearly.Comment: 21 pages, 24 figures, extended version of arXiv: 1101.3607 (Phys. Rev. C83, 011304R); added refs.; added Fig. 4 and discussions; Phys. Rev. C, in pres

    Multi-Mode Online Knowledge Distillation for Self-Supervised Visual Representation Learning

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    Self-supervised learning (SSL) has made remarkable progress in visual representation learning. Some studies combine SSL with knowledge distillation (SSL-KD) to boost the representation learning performance of small models. In this study, we propose a Multi-mode Online Knowledge Distillation method (MOKD) to boost self-supervised visual representation learning. Different from existing SSL-KD methods that transfer knowledge from a static pre-trained teacher to a student, in MOKD, two different models learn collaboratively in a self-supervised manner. Specifically, MOKD consists of two distillation modes: self-distillation and cross-distillation modes. Among them, self-distillation performs self-supervised learning for each model independently, while cross-distillation realizes knowledge interaction between different models. In cross-distillation, a cross-attention feature search strategy is proposed to enhance the semantic feature alignment between different models. As a result, the two models can absorb knowledge from each other to boost their representation learning performance. Extensive experimental results on different backbones and datasets demonstrate that two heterogeneous models can benefit from MOKD and outperform their independently trained baseline. In addition, MOKD also outperforms existing SSL-KD methods for both the student and teacher models.Comment: Accepted by CVPR 202

    A Review of Modeling and Diagnostic Techniques for Eccentricity Fault in Electric Machines

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    Research on the modeling and fault diagnosis of rotor eccentricities has been conducted during the past two decades. A variety of diagnostic theories and methods have been proposed based on different mechanisms, and there are reviews following either one type of electric machines or one type of eccentricity. Nonetheless, the research routes of modeling and diagnosis are common, regardless of machine or eccentricity types. This article tends to review all the possible modeling and diagnostic approaches for all common types of electric machines with eccentricities and provide suggestions on future research roadmap. The paper indicates that a reliable low-cost non-intrusive real-time online visualized diagnostic method is the trend. Observer-based diagnostic strategies are thought promising for the continued research

    Nuclear superfluidity for antimagnetic rotation in 105^{105}Cd and 106^{106}Cd

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    The effect of nuclear superfluidity on antimagnetic rotation bands in 105^{105}Cd and 106^{106}Cd are investigated by the cranked shell model with the pairing correlations and the blocking effects treated by a particle-number conserving method. The experimental moments of inertia and the reduced B(E2)B(E2) transition values are excellently reproduced. The nuclear superfluidity is essential to reproduce the experimental moments of inertia. The two-shears-like mechanism for the antimagnetic rotation is investigated by examining the shears angle, i.e., the closing of the two proton hole angular momenta, and its sensitive dependence on the nuclear superfluidity is revealed.Comment: 14 pages, 4 figure

    Effects of different nutrient solutions on the acclimatisation of in vitro Caladium plantlets using a simplified hydroponic system

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    An efficient acclimatisation protocol is critical to improve the survival rate and promote growth of in vitro plantlets. Herein, tissue-cultured plantlets of ‘Red Flash’ caladium (Caladium × hortulanum Birdsey) were treated with deionised water and three nutrient solutions including Japanese garden formula (JG), South China Agriculture University formula B for leafy vegetables (SCAU-B) and Hoagland solution in a simplified hydroponic system under indoor environmental conditions. The results showed that all the plantlets survived after 30 days of hydroponic culture, and the three nutrient solutions showed significant positive effects on the plant growth and the content of chlorophyll a, chlorophyll b, total chlorophyll, carotenoid, soluble sugar and soluble protein compared to the deionised water treatment. No significant difference was recorded for the other growth parameters except the average leaf number per plantlet among the nutrient solution treatments. For the analysed physiological parameters, the plantlets treated by SCAU-B contained significantly higher content than those of the Hoagland treatment except the protein content. No significant difference was found between the JG and the SCAU-B treatment except the carotenoid content, and between the JG and the Hoagland treatment except the protein content. The plantlets acclimatised in the nutrient solutions also had a good performance when transferred to plastic pots. These results implied that water alone was not capable of maintaining healthy growth of in vitro caladium plantlets, and hydroponics approach using the three nutrient solutions could be a feasible method for acclimatisation of the plantlets

    Rotation and alignment of high-jj orbitals in transfermium nuclei

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    The structure of nuclei with Z∼100Z\sim100 is investigated systematically by the Cranked Shell Model (CSM) with pairing correlations treated by a Particle-Number Conserving (PNC) method. In the PNC method, the particle number is conserved and the Pauli blocking effects are taken into account exactly. By fitting the experimental single-particle spectra in these nuclei, a new set of Nilsson parameters (κ\kappa and μ\mu) is proposed. The experimental kinematic moments of inertia and the band-head energies are reproduced quite well by the PNC-CSM calculations. The band crossing, the effects of high-jj intruder orbitals and deformation are discussed in detail.Comment: To appear in the Proceedings of the International Nuclear Physics Conference (INPC2013), June 2-7, 2013, Florence, Ital
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