8,672 research outputs found
Vibrations of micro-eV energies in nanocrystalline microstructures
The phonon density of states of nanocrystalline bcc Fe and nanocrystalline fcc Ni3Fe were measured by inelastic neutron scattering in two different ranges of energy. As has been reported previously, the nanocrystalline materials showed enhancements in their phonon density of states at energies from 2 to 15 meV, compared to control samples composed of large crystals. The present measurements were extended to energies in the micro-eV range, and showed significant, but smaller, enhancements in the number of modes in the energy range from 5 to 18 mueV. These modes of micro-eV energies provide a long-wavelength limit that bounds the fraction of modes at milli-eV energies originating with the cooperative dynamics of the nanocrystalline microstructure
Design and performance analysis of network code division multiplexing for wireless sensor networks
© 2015 IEEE. In this paper, we investigate the performance of a wireless sensor network, in which multiple groups of source nodes communicate with their respective destination nodes with the help of a common relay network. A network code division multiplexing (NCDM) scheme is proposed to remove the inter-session interference among multiple transmission sessions at each destination. We focus on analyzing the soft processing algorithm of the NCDM scheme. Based on the analysis results, a new code design criteria for the construction of the generator matrix is proposed. Simulation results show that by following the proposed code design criteria, the bit error ratio (BER) performance gap between the scheme we studied and the serial session scheme can be managed effectively. In serial session scheme, source nodes in a number of groups communicate with their respective destinations in a time division manner
Research Program towards Observation of Neutrino-Nucleus Coherent Scattering
The article describes the research program pursued by the TEXONO
Collaboration towards an experiment to observe coherent scattering between
neutrinos and the nucleus at the power reactor. The motivations of studying
this process are surveyed. In particular, a threshold of 100-200 eV has been
achieved with an ultra-low-energy germanium detector prototype. This detection
capability at low energy can also be adapted to conduct searches of Cold Dark
Matter in the low-mass region as well as to enhance the sensitivities in the
study of neutrino magnetic moments.Comment: 5 pages, 8 figures ; Proceedings of TAUP-2005 Workshop, Spain, 2005.
Updated on 2006/9/15 for Proceedings of Neutrino-2006 Conference, Santa Fe,
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Thermally stimulated relaxation and behaviors of oxygen vacancies in SrTiO<inf>3</inf> single crystals with (100), (110) and (111) orientations
Abstract
The strontium titanate (SrTiO3) single crystals with different orientations of (100), (110) and (111) were investigated using thermally stimulated depolarization current (TSDC) measurements, which has been proved to be an effective strategy to fundamentally study the relationship between relaxation phenomena and defect chemistry in dielectrics. The origins of different relaxations in SrTiO3 crystals were identified and the activation energy of oxygen vacancies was estimated from TSDC measurements. It was further found that oxygen-treated SrTiO3 crystals exhibit different relaxation behaviors. Noticeable changes of thermal relaxation associated with oxygen vacancies have taken place in relation to the crystalline anisotropy. The SrTiO3 (110) samples display higher concentration and activation energy of oxygen vacancies. First-principles calculations were carried out on SrTiO3 (110) crystals to study the effect of oxygen vacancy on different surface microstructure. From the resulting minimum formation energy of 0.63 eV, it demonstrates that the oxygen vacancies tend to form on the TiO-terminated surfaces. Considering the band structure, oxygen vacancies near the surface contribute to the transition of crystal from insulator to metallic characteristic.</jats:p
An enhanced convolutional neural network model for answer selection
© 2017 International World Wide Web Conference Committee (IW3C2), published under Creative Commons CC BY 4.0 License. Answer selection is an important task in question answering (QA) from the Web. To address the intrinsic difficulty in encoding sentences with semantic meanings, we introduce a general framework, i.e., Lexical Semantic Feature based Skip Convolution Neural Network (LSF-SCNN), with several optimization strategies. The intuitive idea is that the granular representations with more semantic features of sentences are deliberately designed and estimated to capture the similarity between question-answer pairwise sentences. The experimental results demonstrate the effectiveness of the proposed strategies and our model outperforms the state-of-the-art ones by up to 3.5% on the metrics of MAP and MRR
Analytic Bethe Ansatz for 1-D Hubbard model and twisted coupled XY model
We found the eigenvalues of the transfer matrices for the 1-D Hubbard model
and for the coupled XY model with twisted boundary condition by using the
analytic Bethe Ansatz method. Under a particular condition the two models have
the same Bethe Ansatz equations. We have also proved that the periodic 1-D
Hubbard model is exactly equal to the coupled XY model with nontrivial twisted
boundary condition at the level of hamiltonians and transfer matrices.Comment: 22 pages, latex, no figure
Exact solution of the lattice vertex model analog of the coupled Bariev XY chains
We present the algebraic Bethe Ansatz solution for the vertex model recently
proposed by Zhou as the classical analog of the Bariev interacting XY chains.
The relevant commutation rules between the creation fields contain the Hecke
symmetry pointed out recently by Hikami and Murakami. The eigenvalues of the
corresponding transfer matrix are explicitly given.Comment: Plain latex, 8 pag
Intrinsically core-shell plasmonic dielectric nanostructures with ultrahigh refractive index
Topological insulators are a new class of quantum materials with metallic (edge) surface states and insulating bulk states. They demonstrate a variety of novel electronic and optical properties, which make them highly promising electronic, spintronic, and optoelectronic materials. We report on a novel conic plasmonic nanostructure that is made of bulk-insulating topological insulators and has an intrinsic core-shell formation. The insulating (dielectric) core of the nanocone displays an ultrahigh refractive index of up to 5.5 in the near-infrared frequency range. On the metallic shell, plasmonic response and strong backward light scattering were observed in the visible frequency range. Through integrating the nanocone arrays into a-Si thin film solar cells, up to 15% enhancement of light absorption was predicted in the ultraviolet and visible ranges. With these unique features, the intrinsically core-shell plasmonic nanostructure paves a new way for designing low-loss and high-performance visible to infrared optical devices
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