890,674 research outputs found
Spatial filters selection towards a rehabilitation BCI
Introducing BCI technology in supporting motor imagery (MI) training has revealed the rehabilitative potential of MI, contributing to significantly better motor functional outcomes in stroke patients. To provide the most accurate and personalized feedback during the treatment, several stages of the electroencephalographic signal processing have to be optimized, including spatial filtering. This study focuses on data-independent approaches to optimize spatial filtering step.
Specific aims were: i) assessment of spatial filters' performance in relation to the hand and foot scalp areas; ii) evaluation of simultaneous use of multiple spatial filters; iii) minimization of the number of electrodes needed for training.
Our findings indicate that different spatial filters showed different performance related to the scalp areas considered. The simultaneous use of EEG signals conditioned with different spatial filters could either improve classification performance or, at same level of performance could lead to a reduction of the number of electrodes needed for successive training, thus improving usability of BCIs in clinical rehabilitation context
Numerical Simulations of Pinhole and Single Mode Fibre Spatial Filters for Optical Interferometers
We use a numerical simulation to investigate the effectiveness of pinhole
spatial filters at optical/IR interferometers and to compare them with
single-mode optical fibre spatial filters and interferometers without spatial
filters. We show that fringe visibility measurements in interferometers
containing spatial filters are much less affected by changing seeing conditions
than equivalent measurements without spatial filters. This reduces visibility
calibration uncertainties, and hence can reduce the need for frequent
observations of separate astronomical sources for calibration of visibility
measurements. We also show that spatial filters can increase the
signal-to-noise ratios of visibility measurements and that pinhole filters give
signal-to-noise ratios within 17% of values obtained with single-mode fibres
for aperture diameters up to 3r_0. Given the simplicity of the use of pinhole
filters we suggest that it represents a competitive, if not optimal, technique
for spatial filtering in many current and next generation interferometers.Comment: 7 pages, 7 postscript figures. Accepted by MNRA
Internet Filter Use In ACL Libraries
Will Internet filters deliver us from evil or are they a necessary evil? Are Christian colleges using Internet filters? If so, which filters? What roles are Christian librarians assuming in this decision-making process
New trends in active filters for improving power quality
Since their basic compensation principles were proposed around 1970, active filters have been studied by many researchers and engineers aiming to put them into practical applications. Shunt active filters for harmonic compensation with or without reactive power compensation, flicker compensation or voltage regulation have been put on a commercial base in Japan, and their rating or capacity has ranged from 50 kVA to 60 MVA at present. In near future, the term of active filters will cover a much wider sense than that of active filters in the 1970s did. The function of active filters will be expanded from voltage flicker compensation or voltage regulation into power quality improvement for power distribution systems as the capacity of active filters becomes larger. This paper describes present states of the active filters based on state-of-the-art power electronics technology, and their future prospects toward the 21st century, including the personal view and expectation of the author</p
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