1,171 research outputs found
Language Transfer of Audio Word2Vec: Learning Audio Segment Representations without Target Language Data
Audio Word2Vec offers vector representations of fixed dimensionality for
variable-length audio segments using Sequence-to-sequence Autoencoder (SA).
These vector representations are shown to describe the sequential phonetic
structures of the audio segments to a good degree, with real world applications
such as query-by-example Spoken Term Detection (STD). This paper examines the
capability of language transfer of Audio Word2Vec. We train SA from one
language (source language) and use it to extract the vector representation of
the audio segments of another language (target language). We found that SA can
still catch phonetic structure from the audio segments of the target language
if the source and target languages are similar. In query-by-example STD, we
obtain the vector representations from the SA learned from a large amount of
source language data, and found them surpass the representations from naive
encoder and SA directly learned from a small amount of target language data.
The result shows that it is possible to learn Audio Word2Vec model from
high-resource languages and use it on low-resource languages. This further
expands the usability of Audio Word2Vec.Comment: arXiv admin note: text overlap with arXiv:1603.0098
Broadband angular selectivity of light at the nanoscale: Progress, applications, and outlook
Humankind has long endeavored to control the propagation direction of light. Since time immemorial, shades, lenses, and mirrors have been used to control the flow of light. In modern society, with the rapid development of nanotechnology, the control of light is moving toward devices at micrometer and even nanometer scales. At such scales, traditional devices based on geometrical optics reach their fundamental diffraction limits and cease to work. Nano-photonics, on the other hand, has attracted wide attention from researchers, especially in the last decade, due to its ability to manipulate light at the nanoscale. This review focuses on the nano-photonics systems that aim to select light based on its propagation direction. In the first half of this review, we survey the literature and the current state of the art focused on enabling optical broadband angular selectivity. The mechanisms we review can be classified into three main categories: (i) microscale geometrical optics, (ii) multilayer birefringent materials, and (iii) Brewster modes in plasmonic systems, photonic crystals, and metamaterials. In the second half, we present two categories of potential applications for broadband angularly selective systems. The first category aims at enhancing the efficiency of solar energy harvesting, through photovoltaic process or solar thermal process. The second category aims at enhancing light extracting efficiency and detection sensitivity. Finally, we discuss the most prominent challenges in broadband angular selectivity and some prospects on how to solve these challenges.United States. Army Research Office (W911NF-13-D0001)United States. Department of Energy (DE-SC0001299
Topological surface electronic states in candidate nodal-line semimetal CaAgAs
We investigate systematically the bulk and surface electronic structure of
the candidate nodal-line semimetal CaAgAs by angle resolved photoemission
spectroscopy and density functional calculations. We observed a metallic,
linear, non--dispersive surface band that coincides with the
high-binding-energy part of the theoretical topological surface state, proving
the topological nontriviality of the system. An overall downshift of the
experimental Fermi level points to a rigid-band-like -doping of the samples,
due possibly to Ag vacancies in the as-grown crystals.Comment: 6 pages, 5 figure
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