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501 results on '"Ruf, C"'

107. Effects of training and motivation on auditory P300 brain-computer interface performance.

Author

Baykara, E., Ruf, C. A., Fioravanti, C., Käthner, I., Simon, N., Kleih, S. C., Kübler, A., and Halder, S.

Subjects
*BRAIN-computer interfaces, *MOTIVATION (Psychology), *AUDITORY perception, *MOTOR ability, *PARALYSIS, *DIAGNOSIS
Abstract

Objectives: Brain-computer interface (BCI) technology aims at helping end-users with severe motor paralysis to communicate with their environment without using the natural output pathways of the brain. For end-users in complete paralysis, loss of gaze control may necessitate non-visual BCI systems. The present study investigated the effect of training on performance with an auditory P300 multi-class speller paradigm. For half of the participants, spatial cues were added to the auditory stimuli to see whether performance can be further optimized. The influence of motivation, mood and workload on performance and P300 component was also examined. Methods: In five sessions, 16 healthy participants were instructed to spell several words by attending to animal sounds representing the rows and columns of a 5 x 5 letter matrix. Results: 81% of the participants achieved an average online accuracy of P70%. From the first to the fifth session information transfer rates increased from 3.72 bits/min to 5.63 bits/min. Motivation significantly influenced P300 amplitude and online ITR. No significant facilitative effect of spatial cues on performance was observed. Conclusions: Training improves performance in an auditory BCI paradigm. Motivation influences performance and P300 amplitude. Significance: The described auditory BCI system may help end-users to communicate independently of gaze control with their environment. [ABSTRACT FROM AUTHOR]

Published
2016
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119. Coherent detectors

Author

Lawrence, C R, primary, Church, S, additional, Gaier, T, additional, Lai, R, additional, Ruf, C, additional, and Wollack, E, additional

Published
2009
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120. Synthetic Aperture Interferometric Radiometer (SAIR)

Author

Ruf, C. S

Subjects
Spacecraft Instrumentation
Abstract

The aperture size requirements of imaging microwave radiometers in geosynchronous orbit ruled out filled aperture antenna systems below 10 GHz. In the regions 10 to 30 GHz, filled apertures are only marginally practical. The size requirements in turn aggravate the problems with a mechanically steered antenna beam. Both the aperture size and steering problems are resolved with a synthetic aperture interferometric radiometer (SAIR). The SAIR imaging is discussed, along with the requirements of the two-dimensional antenna elements.

Published
1989

121. A microwave radiometer weather-correcting sea ice algorithm

Author

Walters, J. M, Ruf, C, and Swift, C. T

Subjects
Oceanography
Abstract

A new algorithm for estimating the proportions of the multiyear and first-year sea ice types under variable atmospheric and sea surface conditions is presented, which uses all six channels of the SMMR. The algorithm is specifically tuned to derive sea ice parameters while accepting error in the auxiliary parameters of surface temperature, ocean surface wind speed, atmospheric water vapor, and cloud liquid water content. Not only does the algorithm naturally correct for changes in these weather conditions, but it retrieves sea ice parameters to the extent that gross errors in atmospheric conditions propagate only small errors into the sea ice retrievals. A preliminary evaluation indicates that the weather-correcting algorithm provides a better data product than the 'UMass-AES' algorithm, whose quality has been cross checked with independent surface observations. The algorithm performs best when the sea ice concentration is less than 20 percent.

Published
1987

122. The electronically steered thinned array radiometer

Author

Ruf, C. S, Tanner, A. B, and Levine, D. M

Subjects
Communications And Radar
Abstract

An L-band radiometer which allows global imaging of soil moisture from LEO is discussed. The system consists of an array of antennas with amplifiers, a device to cross-correlate the signals from the antennas, and a process to translate the resulting data into an image of brightness temperature over the field of view. The process is based on a Fourier transform relation that exists between the incident electric field strength as a function of incidence angle and electric fields across the aperture plane of the antenna. The system's image reconstruction technique and signal-to-noise performance are examined.

Published
1987

123. The Electronically Steered Thinned Array Radiometer (ESTAR)

Author

Swift, C. T, Ruf, C, Tanner, A, and Levine, D

Subjects
Instrumentation And Photography
Abstract

The concept of a thinned array radiometer is described as an alternate to large filled apertures to achieve high resolution imaging from space. The serious limitations of conventional mechanical scanning systems and the practical problems associated with a multiple receiver pushbroom system that utilizes a large antenna are discussed. The thinned array is developed in terms of aperture synthesis techniques used in radio astronomy. Examples of thinned array configurations are presented, and future directions are discussed.

Published
1986

124. Electronically Steered Thinned Array Radiometer (ESTAR) system design, calibration, and sensitivity

Author

Ruf, C, Swift, C. T, and Levine, D

Subjects
Spacecraft Instrumentation
Abstract

The ESTAR system, an imaging L-band radiometer designed to provide measurements of soil moisture from space, is described. The large aperture size dictated by the resolution requirement (10 km or less) suggests the use of aperture synthesis, and plans to have ESTAR operate in low earth orbit require that the synthesis be performed in the short data acquisition time permitted by satellite motion. Two forms of ESTAR are described. ESTAR-0 is to be an airborne prototype designed for proof of concept; it will image a line of eight adjacent pixels with 8 degree spatial resolution of 0.1 degree Kelvin temperature resolution, given 1 sec integration time. ESTAR-1 is the satellite version to operate from space. A tentative sensor design will image a line of 128 0.5 degree pixels with 2.0 degree K resolution assuming 0.7 sec integration at 700 km altitude.

Published
1985

132. GeoSTAR: a microwave sounder for geostationary applications

Author

Lambrigtsen, B. H., primary, Brown, S. T., additional, Dinardo, S. J., additional, Gaier, T. C., additional, Kangaslahti, P. P., additional, Tanner, A. B., additional, Piepmeier, J. R., additional, Ruf, C. S., additional, Gross, S. M., additional, Musko, S., additional, and Rogacki, S., additional

Published
2006
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150. Improved Limits onν¯eEmission fromμ+Decay

Author

Armbruster, B., primary, Drexlin, G., additional, Eitel, K., additional, Jannakos, T., additional, Kleinfeller, J., additional, Maschuw, R., additional, Oehler, C., additional, Plischke, P., additional, Reichenbacher, J., additional, Steidl, M., additional, Zeitnitz, B., additional, Gemmeke, H., additional, Kleifges, M., additional, Eichner, C., additional, Ruf, C., additional, Bodmann, B. A., additional, Finckh, E., additional, Hößl, J., additional, Jünger, P., additional, Kretschmer, W., additional, Wolf, J., additional, Booth, N. E., additional, Blair, I. M., additional, and Edgington, J. A., additional

Published
2003
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