12,111 research outputs found

    Formation of Non-reciprocal Bands in Magnetized Diatomic Plasmonic Chains

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    We show that non-reciprocal bands can be formed in a magnetized periodic chain of spherical plasmonic particles with two particles per unit cell. Simplified form of symmetry operators in dipole approximations are used to demonstrate explicitly the relation between spectral non-reciprocity and broken spatial-temporal symmetries. Due to hybridization among plasmon modes and free photon modes, strong spectral non-reciprocity appears in region slightly below the lightline, where highly directed guiding of energy can be supported. The results may provide a clear guidance on the design of one-way waveguides

    Nonstationary Discrete Choice: A Corrigendum and Addendum

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    We correct the limit theory presented in an earlier paper by Hu and Phillips (Journal of Econometrics, 2004) for nonstationary time series discrete choice models with multiple choices and thresholds. The new limit theory shows that, in contrast to the binary choice model with nonstationary regressors and a zero threshold where there are dual rates of convergence (n^{1/4} and n^{3/4}), all parameters including the thresholds converge at the rate n^{3/4}. The presence of non-zero thresholds therefore materially affects rates of convergence. Dual rates of convergence reappear when stationary variables are present in the system. Some simulation evidence is provided, showing how the magnitude of the thresholds affects finite sample performance. A new finding is that predicted probabilities and marginal effect estimates have finite sample distributions that manifest a pile-up, or increasing density, towards the limits of the domain of definition.Brownian motion, Brownian local time, Discrete choices, Integrated processes, Pile-up problem, Threshold parameters

    A Thermal Degradation Study of Insulation Materials Extruded Polystyrene

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    AbstractThis paper presents a research on the thermal degradation of typical polymer insulation materials extruded polystyrene (XPS) under both oxidizing gas air and non-oxidizing gas nitrogen. The Kissinger-Akahira-Sunose method was employed to calculate the activation energy values according to thermogravimetic analysis (TGA) results. Thermal degradation characteristics of XPS were studied by using thermogravimetry and differential scanning calorimetry (TG-DSC) hyphenated technique. XPS follows a two-stage and three-stage weight loss during the entire process under nitrogen and air, respectively. Evolved products of XPS and the degradation mechanism in helium were investigated with pyrolysis-gas chromatography-mass spectrometry (Py-GC-MS) method. The results reveal that styrene monomers are the dominate products of XPS degradation. Methylbenzene, α-methyl styrene, dimer and some other oligmers of styrene are also detected
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