53,885 research outputs found
Discriminative Tandem Features for HMM-based EEG Classification
AbstractâWe investigate the use of discriminative feature extractors in tandem configuration with generative EEG classification system. Existing studies on dynamic EEG classification typically use hidden Markov models (HMMs) which lack discriminative capability. In this paper, a linear and a non-linear classifier are discriminatively trained to produce complementary input features to the conventional HMM system. Two sets of tandem features are derived from linear discriminant analysis (LDA) projection output and multilayer perceptron (MLP) class-posterior probability, before appended to the standard autoregressive (AR) features. Evaluation on a two-class motor-imagery classification task shows that both the proposed tandem features yield consistent gains over the AR baseline, resulting in significant relative improvement of 6.2% and 11.2 % for the LDA and MLP features respectively. We also explore portability of these features across different subjects. Index Terms- Artificial neural network-hidden Markov models, EEG classification, brain-computer-interface (BCI)
Augmented Reality in Astrophysics
Augmented Reality consists of merging live images with virtual layers of
information. The rapid growth in the popularity of smartphones and tablets over
recent years has provided a large base of potential users of Augmented Reality
technology, and virtual layers of information can now be attached to a wide
variety of physical objects. In this article, we explore the potential of
Augmented Reality for astrophysical research with two distinct experiments: (1)
Augmented Posters and (2) Augmented Articles. We demonstrate that the emerging
technology of Augmented Reality can already be used and implemented without
expert knowledge using currently available apps. Our experiments highlight the
potential of Augmented Reality to improve the communication of scientific
results in the field of astrophysics. We also present feedback gathered from
the Australian astrophysics community that reveals evidence of some interest in
this technology by astronomers who experimented with Augmented Posters. In
addition, we discuss possible future trends for Augmented Reality applications
in astrophysics, and explore the current limitations associated with the
technology. This Augmented Article, the first of its kind, is designed to allow
the reader to directly experiment with this technology.Comment: 15 pages, 11 figures. Accepted for publication in Ap&SS. The final
publication will be available at link.springer.co
Interference Mitigation for Cognitive Radio MIMO Systems Based on Practical Precoding
In this paper, we propose two subspace-projection-based precoding schemes,
namely, full-projection (FP)- and partial-projection (PP)-based precoding, for
a cognitive radio multiple-input multiple-output (CR-MIMO) network to mitigate
its interference to a primary time-division-duplexing (TDD) system. The
proposed precoding schemes are capable of estimating interference channels
between CR and primary networks, and incorporating the interference from the
primary to the CR system into CR precoding via a novel sensing approach. Then,
the CR performance and resulting interference of the proposed precoding schemes
are analyzed and evaluated. By fully projecting the CR transmission onto a null
space of the interference channels, the FP-based precoding scheme can
effectively avoid interfering the primary system with boosted CR throughput.
While, the PP-based scheme is able to further improve the CR throughput by
partially projecting its transmission onto the null space.Comment: 12 pages, 4 figures, submitted to the IEEE Trans. Wireless
Communications in April 201
Augmented reality meeting table: a novel multi-user interface for architectural design
Immersive virtual environments have received widespread attention as providing possible replacements for the media and systems that designers traditionally use, as well as, more generally, in providing support for collaborative work. Relatively little attention has been given to date however to the problem of how to merge immersive virtual environments into real world work settings, and so to add to the media at the disposal of the designer and the design team, rather than to replace it. In this paper we report on a research project in which optical see-through augmented reality displays have been developed together with prototype decision support software for architectural and urban design. We suggest that a critical characteristic of multi user augmented reality is its ability to generate visualisations from a first person perspective in which the scale of rendition of the design model follows many of the conventions that designers are used to. Different scales of model appear to allow designers to focus on different aspects of the design under consideration. Augmenting the scene with simulations of pedestrian movement appears to assist both in scale recognition, and in moving from a first person to a third person understanding of the design. This research project is funded by the European Commission IST program (IST-2000-28559)
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