a b s t r a c tThis study presents an evaluation of an advanced Doppler radar-based method for detection of vital signs, presence, and activity of a human subject in a test room with radar-signal reflecting aluminum-coated surfaces. Ten test subjects lay in four positions, and they sat in two locations in the room, both breathing normally and holding their breath. The mean ratios of the pulse rates determined from the radar signal and electrocardiography and respiration reference signals were 110% (respiration) and 99% (heartbeat), and the mean occupied and empty room radar signal variance ratios were 608 (breathing) and 20 (breath-hold). In a one-subject activity monitoring test, walking, standing and lying activities could be well separated from the radar signal. The results are promising and the proposed system seems to have potential to be used in position-independent health and activity monitoring of, for example, elderly people in care homes or intoxicated people in police custody.
The concept of a local audio environment is to have sound playback locally restricted such that, ideally, adjacent regions of an indoor or outdoor space could exhibit their own individual audio content without interfering with each other. This would enable people to listen to their content of choice without disturbing others next to them, yet, without any headphones to block conversation. In practice, perfect sound containment in free air cannot be attained, but a local audio environment can still be satisfactorily approximated using directional speakers. Directional speakers may be based on regular audible frequencies or they may employ modulated ultrasound. Planar, parabolic, and array form factors are commonly used. The directivity of a speaker improves as its surface area and sound frequency increases, making these the main design factors for directional audio systems. Even directional speakers radiate some sound outside the main beam, and sound can also reflect from objects. Therefore, directional speaker systems perform best when there is enough ambient noise to mask the leaking sound. Possible areas of application for local audio include information and advertisement audio feed in commercial facilities, guiding and narration in museums and exhibitions, office space personalization, control room messaging, rehabilitation environments, and entertainment audio systems.
Direction-sensitive visitor counting sensors can be used in demand-controlled ventilation (DCV). The counting performance of two light beam sensors and three camera sensors, all direction sensitive, was simultaneously evaluated at an indoor location. Direction insensitive sensors (two mat sensors and one light beam sensor) were additionally tested as a reference. Bidirectional counting data of free people flow was collected for 36 days in one-hour resolution, including five hours of manual counting. Compared to the manual results, one of the light beam sensors had the most equally balanced directional overall counting errors (4.6% and 5.2%). The collected data of this sensor was used to model the air transportation energy consumption of visitor counting sensor-based DCV and constant air volume ventilation (CAV). The results suggest that potential savings in air transportation energy consumption could be gained with the modeled DCV as its total daily airflow during the test period was 54% of the total daily airflow of the modeled CAV on average. A virtually real-time control of ventilation could be realized with minute-level counting resolution. Site-specific calibration of the visitor counting sensors is advisable and they could be complemented with presence detectors to avoid unnecessary ventilation during unoccupied periods of the room. A combination of CO 2 and visitor counting sensors could be exploited in DCV to always guarantee sufficient ventilation with a short response time.
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