| 1. |
- Ekblom Bak, Elin, 1981-, et al.
(författare)
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Accelerometer derived physical activity patterns in 27.890 middle‐aged adults : The SCAPIS cohort study
- 2022
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Ingår i: Scandinavian Journal of Medicine and Science in Sports. - : John Wiley & Sons. - 0905-7188 .- 1600-0838. ; 32:5, s. 866-880
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Tidskriftsartikel (refereegranskat)abstract
- The present study aims to describe accelerometer-assessed physical activity (PA) patterns and fulfillment of PA recommendations in a large sample of middle-aged men and women, and to study differences between subgroups of socio-demographic, socio-economic, and lifestyle-related variables. A total of 27 890 (92.5% of total participants, 52% women, aged 50–64 years) middle-aged men and women with at least four days of valid hip-worn accelerometer data (Actigraph GT3X+, wGT3X+ and wGT3X-BT) from the Swedish CArdioPulmonary bioImage Study, SCAPIS, were included. In total, 54.5% of daily wear time was spent sedentary, 39.1% in low, 5.4% in moderate, and only 0.1% in vigorous PA. Male sex, higher education, low financial strain, born in Sweden, and sedentary/light working situation were related to higher sedentary time, but also higher levels of vigorous PA. High BMI and having multiple chronic diseases associated strongly with higher sedentary time and less time in all three PA intensities. All-year physically active commuters had an overall more active PA pattern. The proportion fulfilling current PA recommendations varied substantially (1.4% to 92.2%) depending on data handling procedures and definition used. Twenty-eight percent was defined as having an “at-risk” behavior, which included both high sedentary time and low vigorous PA. In this large population-based sample, a majority of time was spent sedentary and only a fraction in vigorous PA, with clinically important variations between subgroups. This study provides important reference material and emphasizes the importance of a comprehensive assessment of all aspects of the individual PA pattern in future research and clinical practice.
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| 2. |
- Holmgren, Emil, et al.
(författare)
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More Electric Aircraft (MEA) : Scaling Aspects and Weight Impact
- 2022
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Ingår i: ICAS, Proceedings, 33th Congress of the International Council of the Aeronautical Sciences, Stockholm, Sweden. - : International Council of the Aeronautical Sciences.
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- This paper is about investigating the differences in fuel consumption of conventional and equivalent electricalsubsystems of passenger aircraft. The goal is to develop a framework that can help evaluate fuel consumptionof passenger aircraft, both conventional aircraft and More Electric Aircraft (MEA), for a given size of aircraftand a given stretch of flight.The work presented in this paper originates from pre-studies within MEA research performed by the ReliabilityCentered Asset Management (RCAM) research group at KTH in collaboration with SAAB that has been doneon a passenger aircraft with comparable size to the Airbus A320. The main difference to the prior study isthe addition of subsystem weight, passenger scaling effects, environmental dependencies and flight profile, alladded to increase the accuracy and diversity of the model. The fuel consumption is based on studies of existingtechnology for several passenger aircraft from Airbus and Boeing. The main focus was the EnvironmentalControl System (ECS).A numerical model of passenger aircraft including the ECS was constructed in MATLAB with different levelsof electrification, a conventional ECS or a fully electric ECS. A special case with an Airbus A320 with 180passengers doing a round trip between Copenhagen and Stockholm on a hot day was studied.The results show possible fuel savings in the magnitude of 4% to 8% when electrifying the ECS for the casestudied and for aircraft with 156 to 700 passengers.
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| 3. |
- Johansson, Emil, 1973-
(författare)
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Synthesis and Characterisation of Potential Hydrogen Storage Materials
- 2004
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The dissociative and non-dissociative hydrogen uptake in carbon nanostructures and metallic films were investigated by measurements and analysis of solubility isotherms. The total, non-dissociative, uptake for multi-walled nano-barrels and amorphous nanoporous carbon was determined to be 6.2 and 4.2 wt. % respectively at 77 K and the adsorption energies (at lowest coverage) -7.2 and -4.2 kJ/mol. At 298 K the H-uptake was negligible. At low concentrations the H-uptake of Nb-films is strongly affected by the film thickness. For thicknesses less then about 31 nm, the absorption energy was found to be temperature dependent. Such changes have not been observed in Nb films before. The presence of multiple absorption energies was shown to limit the possibility to obtain relevant absorption and interaction energies by traditional Sievert's and van 't Hoff analysis. The Mg1-xNix system (0<0.43) was investigated with respect to the hydrogen uptake. For Mg2Ni the hydrogen uptake, at an external hydrogen pressure of 1 bar, is close to 1.33 H/M (Mg2NiH4). The enthalpy of formation is smaller in the film as compared to bulk material. The changes in the absorption energy are caused by the adhesion to the substrate as well as the nanocrystallinity of the absorbing layers. The optical band gap of Mg2NiH4 was determined to be 2.4 eV. In Mg1-xYx (0<0.17) it was found that the Y-concentration limits the hydrogen uptake at 1 bar. However, the kinetics of the uptake improves substantially with a minimum of 7 at.% of Y. For Mg-Y the optical band gap (3.6 eV) is independent of Y concentration within the concentration range investigated, while the transmittance decreases with increasing Y content.
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