18,915 research outputs found
Recognizing Multi-talker Speech with Permutation Invariant Training
In this paper, we propose a novel technique for direct recognition of
multiple speech streams given the single channel of mixed speech, without first
separating them. Our technique is based on permutation invariant training (PIT)
for automatic speech recognition (ASR). In PIT-ASR, we compute the average
cross entropy (CE) over all frames in the whole utterance for each possible
output-target assignment, pick the one with the minimum CE, and optimize for
that assignment. PIT-ASR forces all the frames of the same speaker to be
aligned with the same output layer. This strategy elegantly solves the label
permutation problem and speaker tracing problem in one shot. Our experiments on
artificially mixed AMI data showed that the proposed approach is very
promising.Comment: 5 pages, 6 figures, InterSpeech201
Bose-Einstein Condensation with Entangled Order Parameter
We propose a practically accessible non-mean-field ground state of
Bose-Einstein condensation (BEC), which occurs in an interspecies two-particle
entangled state, and is thus described by an entangled order parameter. A
suitably defined entanglement entropy is used as the characterization of the
non-mean-field nature, and is found to persist in a wide parameter regime. The
interspecies entanglement leads to novel interference terms in the dynamical
equations governing the single particle orbital wavefunctions. Experimental
feasibility and several methods of probe are discussed. We urge the study of
multi-channel scattering between different species of atoms.Comment: V1: 5 pages, 4 figures. Accepted by Phys. Rev. Lett.; V2: A couple of
very minor typos corrected, publishe
Berry Phase Effects on Electronic Properties
Ever since its discovery, the Berry phase has permeated through all branches
of physics. Over the last three decades, it was gradually realized that the
Berry phase of the electronic wave function can have a profound effect on
material properties and is responsible for a spectrum of phenomena, such as
ferroelectricity, orbital magnetism, various (quantum/anomalous/spin) Hall
effects, and quantum charge pumping. This progress is summarized in a
pedagogical manner in this review. We start with a brief summary of necessary
background, followed by a detailed discussion of the Berry phase effect in a
variety of solid state applications. A common thread of the review is the
semiclassical formulation of electron dynamics, which is a versatile tool in
the study of electron dynamics in the presence of electromagnetic fields and
more general perturbations. Finally, we demonstrate a re-quantization method
that converts a semiclassical theory to an effective quantum theory. It is
clear that the Berry phase should be added as a basic ingredient to our
understanding of basic material properties.Comment: 48 pages, 16 figures, submitted to RM
Chiral anomaly and anomalous finite-size conductivity in graphene
Graphene is a monolayer of carbon atoms packed into a hexagon lattice to host
two pairs of massless two-dimensional Dirac fermions in the absence of or with
negligible spin-orbit coupling. It is known that the existence of non-zero
electric polarization in reduced momentum space which is associated with a
hidden chiral symmetry will lead to the zero-energy flat band of zigzag
nanoribbon. The Adler-Bell-Jackiw chiral anomaly or non-conservation of chiral
charges at different valleys can be realized in a confined ribbon of finite
width. In the laterally diffusive regime, the finite-size correction to
conductivity is always positive and goes inversely with the square of the
lateral dimension W, which is different from the finite-size correction
inversely with W from boundary modes. This anomalous finite-size conductivity
reveals the signature of the chiral anomaly in graphene, and is measurable
experimentally.Comment: 5 pages, 2 figure
Studies on Utilizing the Three Famous International Index Systems to Evaluate Scientific Research Level of Higher Learning Institutions
Science Citation Index (SCI), The Engineering Index (EI) and Index to Scientific & Technical Proceeding (ISTP) are widely accepted and used to evaluate the scientific research level of higher learning institutions by many country's science and technology field currently. After research, we point out the blemishes in this method and put forward the problems that need to be noticed, and then, under current conditions, bring forward brand-new standard and method to estimate research level, efficiency, fund exploitation and so on. One shouldn't over-emphasize the total amount of papers collected in SCI, EI & ISTP when evaluating the scientific research level of higher learning institutions, whereas using ‘comprehensive factor’ analysis method can make it more scientific and efficient
The Return to Capital in China
China's investment rate is one of the highest in the world, which naturally leads one to suspect that the return to capital in China must be quite low. Using the data from China's national accounts, we estimate the rate of return to capital in China. We find that the aggregate rate of return to capital averaged 25% during 1978-1993, fell during 1993-1998, and has become flat at roughly 20% since 1998. This evidence suggests that the aggregate return to capital in China does not appear to be significantly lower than the return to capital in the rest of the world. We also find that the standard deviation of the rate of return to capital across Chinese provinces has fallen since 1978.
Analysis of marine container terminal gate congestion, truck waiting cost, and system optimization
As world container volume continues to grow and the introduction of 12,000 TEUs plus containerships into major trade routes, the port industry is under pressure to deal with the ever increasing freight volume. Gate congestion at marine container terminal is considered a major issue facing truckers who come to the terminal for container pickup and delivery. Harbor truckers operate in a very competitive environment; they are paid by trip, not by the hours they drive. Gate congestion is not only detrimental to their economic well-being, but also causes environmental pollution.
This thesis applies a multi-server queuing model to analyze marine terminal gate congestion and quantify truck waiting cost. In addition, an optimization model is developed to minimize gate system cost. Extensive data collection includes field observations and online camera observation and terminal day-to-day operation records. Comprehensive data analysis provides a solid foundation to support the development of the optimization model. The queuing analysis indicates that there is a substantial truck waiting cost incurred during peak season. Three optimization alternatives are explored. The results prove that optimization by appointment is the most effective way to reduce gate congestion and improve system efficiency. Lastly, it is the recommendation to use the combination of optimization by appointment and productivity improvement to mitigate terminal gate congestion and accommodate the ever growing container volume
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