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- Denby, Bruce Rolstad, et al.
(författare)
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A coupled road dust and surface moisture model to predict non-exhaust road traffic induced particle emissions (NORTRIP). Part 2 : Surface moisture and salt impact modelling
- 2013
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Ingår i: Atmospheric Environment. - : Elsevier. - 1352-2310 .- 1873-2844. ; 81, s. 485-503
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Tidskriftsartikel (refereegranskat)abstract
- Non-exhaust traffic induced emissions are a major source of airborne particulate matter in most European countries. This is particularly important in Nordic and Alpine countries where winter time road traction maintenance occurs, e.g. salting and sanding, and where studded tyres are used. Though the total mass generated by wear sources is a key factor in non-exhaust emissions, these emissions are also strongly controlled by surface moisture conditions. In this paper, Part 2, the road surface moisture submodel of a coupled road dust and surface moisture model (NORTRIP) is described.We present a description of the road surface moisture part of the model and apply the coupled model to seven sites in Stockholm, Oslo, Helsinki and Copenhagen over 18 separate periods, ranging from 3.5 to 24 months. At two sites surface moisture measurements are available and the moisture sub-model is compared directly to these observations. The model predicts the frequency of wet roads well at both sites, with an average fractional bias of -2.6%. The model is found to correctly predict the hourly surface state, wet or dry, 85% of the time. From the 18 periods modelled using the coupled model an average absolute fractional bias of 15% for PM10 concentrations was found. Similarly the model predicts the 90'th daily mean percentiles of PMio with an average absolute bias of 19% and an average correlation (R-2) of 0.49. When surface moisture is not included in the modelling then this average correlation is reduced to 0.16, demonstrating the importance of the surface moisture conditions. Tests have been carried out to assess the sensitivity of the model to model parameters and input data. The model provides a useful tool for air quality management and for improving our understanding of non-exhaust traffic emissions.
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- Said, Safwat, 1951-, et al.
(författare)
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Evaluation of pavement structure reinforced with steel fabrics
- 2002
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Ingår i: Bearing Capacity Of Roads Railways and Airfields. - London : CRC Press. - 9781000108101 - 9789058093967 - 9781003078814 ; , s. 497-504
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Bokkapitel (övrigt vetenskapligt/konstnärligt)abstract
- This paper describes the rehabilitation procedure of an old cracked asphalt pavement located at E6 motorway in the West of Sweden. A trial has been made to design the road structure with steel fabric reinforcement in the asphalt concrete. Three full-scale, 100-meter test sections were built. Two test sections were reinforced with steel fabrics and one section without reinforcement as a reference road section. These sections are instrumented with strain gauges. The sections have been tested by deflection measurements with Falling Weight Deflectometer, strain measurements at the bottom surface of the overlays, strain on the steel bars, unevenness and rut depth measurements and manual distress surveys. This work is a part of a co-operation project, called REFLEX, partly financed by the European Commission. The objective is to evaluate the performance of new and rehabilitated road structures reinforced with steel fabric.
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| 4. |
- Skau, Simon, et al.
(författare)
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Exhaustion disorder and altered brain activity in frontal cortex detected with fNIRS
- 2021
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Ingår i: Stress-the International Journal on the Biology of Stress. - : Informa UK Limited. - 1025-3890 .- 1607-8888. ; 24:1, s. 64-75
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Tidskriftsartikel (refereegranskat)abstract
- Patients with stress-related Exhaustion Disorder (ED) have problems with memory and executive function. These problems have been associated with deviant activity in prefrontal cortex (PFC). We investigated cognitive performance and functional activity in the PFC during prolonged mental activity in patients with ED (n = 20, 16 women) with a mean duration since diagnosis of 46 +/- 23 months in comparison to healthy individuals (n = 20, 12 women). A block of six neuropsychological tests was performed in a sequence that was repeated once. The brain imaging technique, functional near infrared spectroscopy (fNIRS) was used for all tests. There were no differences between the groups in terms of changes over time, i.e. difference between first and second test block. In the Stroop-Simon test, the controls showedhigher functional activity in the frontal cortex. In the left ventrolateral PFC, we observed an increased activity in controls in the incongruent compared to the congruent trials, whereas no changes were detected in the ED patient group. During processing speed tasks, only ED patients showed higher functional activity in right dorsolateral PFC. The ED patients reported lower subjective energy level and they also performed less well on a mental control task compared to healthy individuals. In conclusion, ED patients showed altered functional activity compared to controls, indicating that ED patients process information differently in the prefrontal cortex, but the functional activity did not change during the 21/2 hr procedure, as revealed by the test-retest design. Lay summary In this paper we show that patient with exhaustion disorder have a reduced functional activity in the prefrontal cortex. This functional activity was not affected by 2.5 hours mental activity.
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