189 research outputs found
Understanding water permeation in graphene oxide membranes
Water transport through graphene-derived membranes has gained much interest
recently due to its promising potential in filtration and separation
applications. In this work, we explore water permeation in graphene oxide
membranes using atomistic simulations, by considering flow through interlayer
gallery, expanded pores such as wrinkles of interedge spaces, and pores within
the sheet. We find that although flow enhancement can be established by
nanoconfinement, fast water transport through pristine graphene channels is
prohibited by a prominent side-pinning effect from capillaries formed between
oxidized regions. We then discuss flow enhancement in situations according to
several recent experiments. These understandings are finally integrated into a
complete picture to understand water permeation through the layer-by-layer and
porous microstructure and could guide rational design of functional membranes
for energy and environmental applications.Comment: arXiv admin note: text overlap with arXiv:1308.536
Analyzing Hidden Representations in End-to-End Automatic Speech Recognition Systems
Neural models have become ubiquitous in automatic speech recognition systems.
While neural networks are typically used as acoustic models in more complex
systems, recent studies have explored end-to-end speech recognition systems
based on neural networks, which can be trained to directly predict text from
input acoustic features. Although such systems are conceptually elegant and
simpler than traditional systems, it is less obvious how to interpret the
trained models. In this work, we analyze the speech representations learned by
a deep end-to-end model that is based on convolutional and recurrent layers,
and trained with a connectionist temporal classification (CTC) loss. We use a
pre-trained model to generate frame-level features which are given to a
classifier that is trained on frame classification into phones. We evaluate
representations from different layers of the deep model and compare their
quality for predicting phone labels. Our experiments shed light on important
aspects of the end-to-end model such as layer depth, model complexity, and
other design choices.Comment: NIPS 201
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