237 research outputs found
Geometry of compositionality
Word embedding is a popular representation of words in vector space, and its geometry reveals the lexical semantics. This thesis further explores the interesting geometric properties of word embedding, and looks into its interaction with the context representation. We propose an innovative method to detect whether a given word or phrase is used literally in a specific context. This work focuses on three specific applications in natural language processing: idiomaticity, sarcasm and metaphor detection. Extensive experiments have shown that this embedding-based method achieves good performance in multiple languages
Gas pressure sintering of BN/Si3N4 wave-transparent material with Y2O3–MgO nanopowders addition
AbstractBN/Si3N4 ceramics performed as wave-transparent material in spacecraft were fabricated with boron nitride powders, silicon nitride powders and Y2O3–MgO nanopowders by gas pressure sintering at 1700°C under 6MPa in N2 atmosphere. The effects of Y2O3–MgO nanopowders on densification, phase evolution, microstructure and mechanical properties of BN/Si3N4 material were investigated. The addition of Y2O3–MgO nanopowders was found beneficial to the mechanical properties of BN/Si3N4 composites. The BN/Si3N4 ceramics with 8wt% Y2O3–MgO nanopowders showed a relative density of 80.2%, combining a fracture toughness of 4.6MPam1/2 with an acceptable flexural strength of 396.5MPa
Recurrent Chunking Mechanisms for Long-Text Machine Reading Comprehension
In this paper, we study machine reading comprehension (MRC) on long texts,
where a model takes as inputs a lengthy document and a question and then
extracts a text span from the document as an answer. State-of-the-art models
tend to use a pretrained transformer model (e.g., BERT) to encode the joint
contextual information of document and question. However, these
transformer-based models can only take a fixed-length (e.g., 512) text as its
input. To deal with even longer text inputs, previous approaches usually chunk
them into equally-spaced segments and predict answers based on each segment
independently without considering the information from other segments. As a
result, they may form segments that fail to cover the correct answer span or
retain insufficient contexts around it, which significantly degrades the
performance. Moreover, they are less capable of answering questions that need
cross-segment information.
We propose to let a model learn to chunk in a more flexible way via
reinforcement learning: a model can decide the next segment that it wants to
process in either direction. We also employ recurrent mechanisms to enable
information to flow across segments. Experiments on three MRC datasets -- CoQA,
QuAC, and TriviaQA -- demonstrate the effectiveness of our proposed recurrent
chunking mechanisms: we can obtain segments that are more likely to contain
complete answers and at the same time provide sufficient contexts around the
ground truth answers for better predictions
Transferable E(3) equivariant parameterization for Hamiltonian of molecules and solids
Using the message-passing mechanism in machine learning (ML) instead of
self-consistent iterations to directly build the mapping from structures to
electronic Hamiltonian matrices will greatly improve the efficiency of density
functional theory (DFT) calculations. In this work, we proposed a general
analytic Hamiltonian representation in an E(3) equivariant framework, which can
fit the ab initio Hamiltonian of molecules and solids by a complete data-driven
method and are equivariant under rotation, space inversion, and time reversal
operations. Our model reached state-of-the-art precision in the benchmark test
and accurately predicted the electronic Hamiltonian matrices and related
properties of various periodic and aperiodic systems, showing high
transferability and generalization ability. This framework provides a general
transferable model that can be used to accelerate the electronic structure
calculations on different large systems with the same network weights trained
on small structures.Comment: 33 pages, 6 figure
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