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- Rödjegård, Henrik, 1974-, et al.
(author)
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Drowsy Driver & Child Left behind-Prevention via in Cabin CO2 Sensing
- 2020
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In: SAE technical paper series. - 400 Commonwealth Drive, Warrendale, PA, United States : SAE International. - 0148-7191. ; :April
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Journal article (peer-reviewed)abstract
- Can one technical solution help prevent drowsy drivers and detect a child left behind? Yes, using a single, maintenance-free, Non-Dispersive Infrared (NDIR) gas sensor integrated in the cabin ventilation system. Carbon dioxide (CO2) is an established proxy for ventilation needs in buildings. Recently, several studies have been published showing a moderate elevation of the indoor carbon dioxide level effect cognitive performance such as information usage, activity, focus and crisis response. A study of airplane pilots using 3-hour flight simulation tests, showed pilots made 50% more mistakes when exposed to 2,500 ppm carbon dioxide compared to 700 ppm. This has a direct impact on safety. All living animals and humans exhale carbon dioxide. In our investigations we have found that an unintentionally left behind child, or pet, can easily be detected in a parked car by analyzing the carbon dioxide trends in the cabin. Even an 8-month old baby acts as a carbon dioxide source, increasing cabin CO2 levels at a 20ppm/minute rate allowing for detection within one minute. Vehicles running with the ventilation system in recirculation mode normally reach above the fresh air limit of 1,000 ppm within a few minutes. The carbon dioxide level normally stabilizes between 3,000 and 10,000 ppm. Levels that will make the driver drowsy, reducing their cognitive performance and impact safety. Using an NDIR gas sensor in the ventilation system will reduce driver performance degradation due to elevated carbon dioxide levels, allowing reliable detection of any unintentionally left behind children or pets, potentially saving lives. © 2020 SAE International. All Rights Reserved.
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| 2. |
- Johannesson, Karin, 1982-, et al.
(author)
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Temporal phosphorus dynamics affecting retention estimates in agricultural constructed wetlands
- 2017
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In: Ecological Engineering. - Amsterdam : Elsevier. - 0925-8574 .- 1872-6992. ; 103, s. 436-445
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Journal article (peer-reviewed)abstract
- Data from seven constructed wetlands (CWs) in the south of Sweden were analyzed to investigate the effects of water flow and season on inflow phosphorus (P) concentrations and temporal P retention variations in CWs receiving runoff from arable land. The form of P (dissolved or particulate) during different water flows (high and low) and seasons (warm and cold) was investigated using the results of total P (TP) and phosphate analyzed in grab samples that had been collected regularly or occasionally during two to nine years, along with continuous water flow measurements.The form of inflow and outflow P (particulate or dissolved P) differed between CWs, and also varied with season and flow. For instance, in three of the CWs, particulate P (PP) dominated the inflow during the cold period with high flow, while during the other periods the proportion of PP was approximately 50%. In one CW situated in a catchment with high clay content, PP dominated both inflow and outflow at all times. The average clay content in catchment top soils was positively correlated to the flow-weighted inflow TP concentrations.In three CWs receiving runoff through drainage pipes, the relationship between TP concentrations (TPin) and water flow was positive, both during high and low flow, and during warm and cold period. However, in four CWs that received surface water runoff, the relationship between TPin and water flow was positive during high flow periods (i.e. the 25% sampling occasions with the highest flow), and during low flow and warm period, the relationship was negative in these four wetlands, indicating either anoxic stagnant water upstream or influence from rural wastewater.The temporal dynamics of P concentrations mean that in some of the CWs, the main part of the annual P retention may occur during a few days with high water flows. The correlation between concentration and water flow suggests that the water sampling strategy may have a considerable impact on retention estimates, as exemplified by some calculation examples.
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| 3. |
- Weisner, Stefan E.B, et al.
(author)
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Influence of alternative states on nitrogen removal in experimental wetlands
- 2007
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In: 2nd International Symposium on Wetland Pollutant Dynamics and Control - WETPOL 2007. - Tartu : Institute of Geography, University of Tartu. - 9789949116881 ; , s. 357-359
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Conference paper (other academic/artistic)abstract
- Denitrification is the main process that remove nitrate from the water in wetlands. Plants can supply denitrifying bacteria with organic carbon and suitable attachment surfaces (Weisner et al. 1994). They also promote the development of anaerobic conditions through litter accumulation and decomposition, which would favour denitrification. The presence of plants has been shown to enhance nitrate removal in field studies (Bachand and Horne 2000). Toet et al. (2005) found a higher nitrogen removal in wetland compartments with emergent plants than with submersed plants. Results from microcosm studies have shown that the potential for denitrification is specific for different plant species (Bastviken et al. 2005).Wetlands may typically exist in alternative states, dominated by different kinds of vegetation. The purpose of this study was to investigate the effect of alternative state on nitrogen removal under controlled conditions in experimental wetlands.
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