72,973 research outputs found
Group Invariant Deep Representations for Image Instance Retrieval
Most image instance retrieval pipelines are based on comparison of vectors
known as global image descriptors between a query image and the database
images. Due to their success in large scale image classification,
representations extracted from Convolutional Neural Networks (CNN) are quickly
gaining ground on Fisher Vectors (FVs) as state-of-the-art global descriptors
for image instance retrieval. While CNN-based descriptors are generally
remarked for good retrieval performance at lower bitrates, they nevertheless
present a number of drawbacks including the lack of robustness to common object
transformations such as rotations compared with their interest point based FV
counterparts.
In this paper, we propose a method for computing invariant global descriptors
from CNNs. Our method implements a recently proposed mathematical theory for
invariance in a sensory cortex modeled as a feedforward neural network. The
resulting global descriptors can be made invariant to multiple arbitrary
transformation groups while retaining good discriminativeness.
Based on a thorough empirical evaluation using several publicly available
datasets, we show that our method is able to significantly and consistently
improve retrieval results every time a new type of invariance is incorporated.
We also show that our method which has few parameters is not prone to
overfitting: improvements generalize well across datasets with different
properties with regard to invariances. Finally, we show that our descriptors
are able to compare favourably to other state-of-the-art compact descriptors in
similar bitranges, exceeding the highest retrieval results reported in the
literature on some datasets. A dedicated dimensionality reduction step
--quantization or hashing-- may be able to further improve the competitiveness
of the descriptors
A Compact and Discriminative Feature Based on Auditory Summary Statistics for Acoustic Scene Classification
One of the biggest challenges of acoustic scene classification (ASC) is to
find proper features to better represent and characterize environmental sounds.
Environmental sounds generally involve more sound sources while exhibiting less
structure in temporal spectral representations. However, the background of an
acoustic scene exhibits temporal homogeneity in acoustic properties, suggesting
it could be characterized by distribution statistics rather than temporal
details. In this work, we investigated using auditory summary statistics as the
feature for ASC tasks. The inspiration comes from a recent neuroscience study,
which shows the human auditory system tends to perceive sound textures through
time-averaged statistics. Based on these statistics, we further proposed to use
linear discriminant analysis to eliminate redundancies among these statistics
while keeping the discriminative information, providing an extreme com-pact
representation for acoustic scenes. Experimental results show the outstanding
performance of the proposed feature over the conventional handcrafted features.Comment: Accepted as a conference paper of Interspeech 201
A Hierarchical Recurrent Encoder-Decoder For Generative Context-Aware Query Suggestion
Users may strive to formulate an adequate textual query for their information
need. Search engines assist the users by presenting query suggestions. To
preserve the original search intent, suggestions should be context-aware and
account for the previous queries issued by the user. Achieving context
awareness is challenging due to data sparsity. We present a probabilistic
suggestion model that is able to account for sequences of previous queries of
arbitrary lengths. Our novel hierarchical recurrent encoder-decoder
architecture allows the model to be sensitive to the order of queries in the
context while avoiding data sparsity. Additionally, our model can suggest for
rare, or long-tail, queries. The produced suggestions are synthetic and are
sampled one word at a time, using computationally cheap decoding techniques.
This is in contrast to current synthetic suggestion models relying upon machine
learning pipelines and hand-engineered feature sets. Results show that it
outperforms existing context-aware approaches in a next query prediction
setting. In addition to query suggestion, our model is general enough to be
used in a variety of other applications.Comment: To appear in Conference of Information Knowledge and Management
(CIKM) 201
DEPFET detectors for direct detection of MeV Dark Matter particles
The existence of dark matter is undisputed, while the nature of it is still
unknown. Explaining dark matter with the existence of a new unobserved particle
is among the most promising possible solutions. Recently dark matter candidates
in the MeV mass region received more and more interest. In comparison to the
mass region between a few GeV to several TeV, this region is experimentally
largely unexplored. We discuss the application of a RNDR DEPFET semiconductor
detector for direct searches for dark matter in the MeV mass region. We present
the working principle of the RNDR DEPFET devices and review the performance
obtained by previously performed prototype measurements. The future potential
of the technology as dark matter detector is discussed and the sensitivity for
MeV dark matter detection with RNDR DEPFET sensors is presented. Under the
assumption of three background events in the region of interest and an exposure
of one kgy a sensitivity of cm
for dark matter particles with a mass of 10 MeV can be reached.Comment: submitted to EPJ
Gravitational waves: search results, data analysis and parameter estimation
The Amaldi 10 Parallel Session C2 on gravitational wave (GW) search results, data analysis and parameter estimation included three lively sessions of lectures by 13 presenters, and 34 posters. The talks and posters covered a huge range of material, including results and analysis techniques for ground-based GW detectors, targeting anticipated signals from different astrophysical sources: compact binary inspiral, merger and ringdown; GW bursts from intermediate mass binary black hole mergers, cosmic string cusps, core-collapse supernovae, and other unmodeled sources; continuous waves from spinning neutron stars; and a stochastic GW background. There was considerable emphasis on Bayesian techniques for estimating the parameters of coalescing compact binary systems from the gravitational waveforms extracted from the data from the advanced detector network. This included methods to distinguish deviations of the signals from what is expected in the context of General Relativity
An Asymmetric B Factory at 10^(36) Luminosity
The physics opportunities at an asymmetric B Factory operating at the unprecedented luminosity of 10^(36) cm^(–2) s^(–1) are unique and attractive. The accelerator appears to be practical and the challenges of performing a sensitive experiment in this environment can be met
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