8,439 research outputs found
A Generative Model For Zero Shot Learning Using Conditional Variational Autoencoders
Zero shot learning in Image Classification refers to the setting where images
from some novel classes are absent in the training data but other information
such as natural language descriptions or attribute vectors of the classes are
available. This setting is important in the real world since one may not be
able to obtain images of all the possible classes at training. While previous
approaches have tried to model the relationship between the class attribute
space and the image space via some kind of a transfer function in order to
model the image space correspondingly to an unseen class, we take a different
approach and try to generate the samples from the given attributes, using a
conditional variational autoencoder, and use the generated samples for
classification of the unseen classes. By extensive testing on four benchmark
datasets, we show that our model outperforms the state of the art, particularly
in the more realistic generalized setting, where the training classes can also
appear at the test time along with the novel classes
Compact Electrodynamics in 2+1 dimensions: Confinement with gapless modes
We consider 2+1 dimensional compact U(1) gauge theory at the Lifshitz point
with dynamical critical exponent . As in the usual theory, monopoles
proliferate the vacuum for any value of the coupling, generating a mass scale.
The theory of the dilute monopole gas is written in terms a non-relativistic
Sine-Gordon model with two real fields. While monopoles remove some of the
massless poles of the perturbative field strength propagator, a gapless mode
representing the incomplete screening of monopoles remains, and is protected by
a shift invariance of the original theory. Timelike Wilson loops still obey
area laws, implying that minimal charges are confined, but the action of
spacelike Wilson loops of linear size L goes instead as .Comment: 4 pages, RevTeX. Some equations simplified. Version to appear in
Physical Review Letter
Optimal fabrication processes for unidirectional metal-matrix composites: A computational simulation
A method is proposed for optimizing the fabrication process of unidirectional metal matrix composites. The temperature and pressure histories are optimized such that the residual microstresses of the composite at the end of the fabrication process are minimized and the material integrity throughout the process is ensured. The response of the composite during the fabrication is simulated based on a nonlinear micromechanics theory. The optimal fabrication problem is formulated and solved with non-linear programming. Application cases regarding the optimization of the fabrication cool-down phases of unidirectional ultra-high modulus graphite/copper and silicon carbide/titanium composites are presented
Exclusion statistics: A resolution of the problem of negative weights
We give a formulation of the single particle occupation probabilities for a
system of identical particles obeying fractional exclusion statistics of
Haldane. We first derive a set of constraints using an exactly solvable model
which describes an ideal exclusion statistics system and deduce the general
counting rules for occupancy of states obeyed by these particles. We show that
the problem of negative probabilities may be avoided with these new counting
rules.Comment: REVTEX 3.0, 14 page
Metal Matrix Laminate Tailoring (MMLT) code: User's manual
The User's Manual for the Metal Matrix Laminate Tailoring (MMLT) program is presented. The code is capable of tailoring the fabrication process, constituent characteristics, and laminate parameters (individually or concurrently) for a wide variety of metal matrix composite (MMC) materials, to improve the performance and identify trends or behavior of MMC's under different thermo-mechanical loading conditions. This document is meant to serve as a guide in the use of the MMLT code. Detailed explanations of the composite mechanics and tailoring analysis are beyond the scope of this document, and may be found in the references. MMLT was developed by the Structural Mechanics Branch at NASA Lewis Research Center (LeRC)
Spoof detection using time-delay shallow neural network and feature switching
Detecting spoofed utterances is a fundamental problem in voice-based
biometrics. Spoofing can be performed either by logical accesses like speech
synthesis, voice conversion or by physical accesses such as replaying the
pre-recorded utterance. Inspired by the state-of-the-art \emph{x}-vector based
speaker verification approach, this paper proposes a time-delay shallow neural
network (TD-SNN) for spoof detection for both logical and physical access. The
novelty of the proposed TD-SNN system vis-a-vis conventional DNN systems is
that it can handle variable length utterances during testing. Performance of
the proposed TD-SNN systems and the baseline Gaussian mixture models (GMMs) is
analyzed on the ASV-spoof-2019 dataset. The performance of the systems is
measured in terms of the minimum normalized tandem detection cost function
(min-t-DCF). When studied with individual features, the TD-SNN system
consistently outperforms the GMM system for physical access. For logical
access, GMM surpasses TD-SNN systems for certain individual features. When
combined with the decision-level feature switching (DLFS) paradigm, the best
TD-SNN system outperforms the best baseline GMM system on evaluation data with
a relative improvement of 48.03\% and 49.47\% for both logical and physical
access, respectively
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