1,937 research outputs found
13C n.m.r. investigation on the nitrogen methylation of some azabenzenes
The 1H and 13C n.m.r. spectra of N-methylated pyridine, pyridazine, pyrimidine and pyrazine and N,N-dimethylated pyrimidine and pyrazine have been recorded and analysed. The change in the 13C chemical shifts under the influence of N-methylation (Δδ) in the diazabenzenes could be predicted by the Δδ values of pyridine. A comparison of the Δδ values of N-methylation with those of N-protonation showed that both reactions have a similar effect
Theoretical study on the protonation of AZA-aromatics
The protonation of azanaphthalenes and azabenzenes has been studied theoretically using CNDO/2 wavefunctions and perturbation theory in order to examine the correlation between pKa values and quantum-mechanical quantities
Weakly Supervised Domain-Specific Color Naming Based on Attention
The majority of existing color naming methods focuses on the eleven basic
color terms of the English language. However, in many applications, different
sets of color names are used for the accurate description of objects. Labeling
data to learn these domain-specific color names is an expensive and laborious
task. Therefore, in this article we aim to learn color names from weakly
labeled data. For this purpose, we add an attention branch to the color naming
network. The attention branch is used to modulate the pixel-wise color naming
predictions of the network. In experiments, we illustrate that the attention
branch correctly identifies the relevant regions. Furthermore, we show that our
method obtains state-of-the-art results for pixel-wise and image-wise
classification on the EBAY dataset and is able to learn color names for various
domains.Comment: Accepted at ICPR201
Exploiting Unlabeled Data in CNNs by Self-supervised Learning to Rank
For many applications the collection of labeled data is expensive laborious.
Exploitation of unlabeled data during training is thus a long pursued objective
of machine learning. Self-supervised learning addresses this by positing an
auxiliary task (different, but related to the supervised task) for which data
is abundantly available. In this paper, we show how ranking can be used as a
proxy task for some regression problems. As another contribution, we propose an
efficient backpropagation technique for Siamese networks which prevents the
redundant computation introduced by the multi-branch network architecture. We
apply our framework to two regression problems: Image Quality Assessment (IQA)
and Crowd Counting. For both we show how to automatically generate ranked image
sets from unlabeled data. Our results show that networks trained to regress to
the ground truth targets for labeled data and to simultaneously learn to rank
unlabeled data obtain significantly better, state-of-the-art results for both
IQA and crowd counting. In addition, we show that measuring network uncertainty
on the self-supervised proxy task is a good measure of informativeness of
unlabeled data. This can be used to drive an algorithm for active learning and
we show that this reduces labeling effort by up to 50%.Comment: Accepted at TPAMI. (Keywords: Learning from rankings, image quality
assessment, crowd counting, active learning). arXiv admin note: text overlap
with arXiv:1803.0309
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