2,598 research outputs found
Minimax Classification with 0-1 Loss and Performance Guarantees
Supervised classification techniques use training samples to find classification
rules with small expected 0-1 loss. Conventional methods achieve efficient learning
and out-of-sample generalization by minimizing surrogate losses over specific
families of rules. This paper presents minimax risk classifiers (MRCs) that do not
rely on a choice of surrogate loss and family of rules. MRCs achieve efficient
learning and out-of-sample generalization by minimizing worst-case expected 0-1
loss w.r.t. uncertainty sets that are defined by linear constraints and include the
true underlying distribution. In addition, MRCsā learning stage provides performance
guarantees as lower and upper tight bounds for expected 0-1 loss. We also
present MRCsā finite-sample generalization bounds in terms of training size and
smallest minimax risk, and show their competitive classification performance w.r.t.
state-of-the-art techniques using benchmark datasets.Ramon y Cajal Grant RYC-2016-1938
A method of moments estimator for interacting particle systems and their mean field limit
We study the problem of learning unknown parameters in stochastic interacting
particle systems with polynomial drift, interaction and diffusion functions
from the path of one single particle in the system. Our estimator is obtained
by solving a linear system which is constructed by imposing appropriate
conditions on the moments of the invariant distribution of the mean field limit
and on the quadratic variation of the process. Our approach is easy to
implement as it only requires the approximation of the moments via the ergodic
theorem and the solution of a low-dimensional linear system. Moreover, we prove
that our estimator is asymptotically unbiased in the limits of infinite data
and infinite number of particles (mean field limit). In addition, we present
several numerical experiments that validate the theoretical analysis and show
the effectiveness of our methodology to accurately infer parameters in systems
of interacting particles
A Numerical Study of Vibration-Induced Instrument Reading Capability Degradation in Helicopter Pilots
Rotorcraft suffer from relatively high vibratory levels, due to exposure to significant vibratory load levels originating from rotors. As a result, pilots are typically exposed to vibrations, which have non-negligible consequences. Among those, one important issue is the degradation of instrument reading, which is a result of complex human-machine interaction. Both involuntary acceleration of the eyes as a result of biodynamics and vibration of the instrument panel contribute to a likely reduction in instrument reading capability, affecting flight safety. Therefore, being able to estimate the expected level of degradation in visual performance may give substantial benefits during vehicle design, allowing to make necessary adjustments while there is room for design changes or when retrofitting an existing aircraft to ensure the modifications do not adversely affect visual acuity and instrument reading ability. For this purpose, simulation is a very valuable tool as a proper model helps to understand the aircraft characteristics before conducting flight tests. This work presents the assessment of vibration-induced visual degradation of helicopter pilots under vibration exposure using a modular analysis environment. Core elements of the suggested analysis framework are an aeroelastic model of the helicopter, a model of the seat-cushion subsystem, a detailed multibody model of the human biodynamics, and a simplified model of ocular dynamics. These elements are combined into a comprehensive, fully coupled model. The contribution of each element to instrument reading degradation is examined, after defining an appropriate figure of merit that includes both eye and instrument panel vibration, in application to a numerical model representative of a medium-weight helicopter
Searching for dominant high-level features for music information retrieval
Music Information Retrieval systems are often based on the analysis of a large number of low-level audio features. When dealing with problems of musical genre description and visualization, however, it would be desirable to work with a very limited number of highly informative and discriminant macro-descriptors. In this paper we focus on a speciļ¬c class of training-based descriptors, which are obtained as the loglikelihood of a Gaussian Mixture Model trained with short musical excerpts that selectively exhibit a certain semantic homogeneity. As these descriptors are critically dependent on the training sets, we approach the problem of how to automatically generate suitable training sets and optimize the associated macro-features in terms of discriminant power and informative impact. We then show the application of a set of three identiļ¬ed macro-features to genre visualization, tracking and classiļ¬cation
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