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Sökning: WFRF:(Karlsson Per) > Luleå tekniska universitet

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  • Glynn, James, et al. (författare)
  • Economic Impacts of Future Changes in the Energy System : National Perspectives
  • 2015
  • Ingår i: Informing Energy and Climate Policies Using Energy Systems Models. - Cham : Encyclopedia of Global Archaeology/Springer Verlag. - 9783319165394 - 9783319165400 ; , s. 359-387
  • Bokkapitel (refereegranskat)abstract
    • In a climate constrained future, hybrid energy-economy model coupling gives additional insight into interregional competition, trade, industrial delocalisation and overall macroeconomic consequences of decarbonising the energy system. Decarbonising the energy system is critical in mitigating climate change. This chapter summarises modelling methodologies developed in the ETSAP community to assess economic impacts of decarbonising energy systems at a national level. The preceding chapter focuses on a global perspective. The modelling studies outlined here show that burden sharing rules and national revenue recycling schemes for carbon tax are critical for the long-term viability of economic growth and equitable engagement on combating climate change. Traditional computable general equilibrium models and energy systems models solved in isolation can misrepresent the long run carbon cost and underestimate the demand response caused by technological paradigm shifts in a decarbonised energy system. The approaches outlined within have guided the first evidence based decarbonisation legislation and continue to provide additional insights as increased sectoral disaggregation in hybrid modelling approaches is achieved
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  • Glynn, James, et al. (författare)
  • Economic Impacts of Future Changes in the Energy System : Global Perspectives
  • 2015
  • Ingår i: Informing Energy and Climate Policies Using Energy Systems Models. - Cham : Encyclopedia of Global Archaeology/Springer Verlag. - 9783319165394 - 9783319165400 ; , s. 333-358
  • Bokkapitel (refereegranskat)abstract
    • In a climate constrained future, hybrid energy-economy model coupling gives additional insight into interregional competition, trade, industrial delocalisation and overall macroeconomic consequences of decarbonising the energy system. Decarbonising the energy system is critical in mitigating climate change. This chapter summarises modelling methodologies developed in the ETSAP community to assess economic impacts of decarbonising energy systems at a global level. The next chapter of this book focuses on a national perspective. The range of economic impacts is regionally dependent upon the stage of economic development, the level of industrialisation, energy intensity of exports, and competition effects due to rates of relative decarbonisation. Developed nation’s decarbonisation targets are estimated to result in a manageable GDP loss in the region of 2 % by 2050. Energy intensive export driven developing countries such as China and India, and fossil fuel exporting nations can expect significantly higher GDP loss of up to 5 % GDP per year by mid-century.
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4.
  • Gustafsson, Emil (författare)
  • Design and application of experimental methods for steel sheet shearing
  • 2016
  • Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
    • Shearing is the process where sheet metal is mechanically cut between two tools. Various shearing technologies are commonly used in the sheet metal industry, for example, in cut to length lines, slitting lines, end cropping etc. Shearing has speed and cost advantages over competing cutting methods like laser and plasma cutting, but involves large forces on the equipment and large strains in the sheet material. The constant development of sheet metals toward higher strength and formability leads to increased forces on the shearing equipment and tools.Shearing of new sheet materials imply new suitable shearing parameters. Investigations of the shearing parameters through live tests in the production are expensive and separate experiments are time consuming and requires specialized equipment. Studies involving a large number of parameters and coupled effects are therefore preferably performed by finite element based simulations. Accurate experimental data is still a prerequisite to validate such simulations. There is, however, a shortage of accurate experimental data to validate such simulations.In industrial shearing processes, measured forces are always larger than the actual forces acting on the sheet, due to friction losses. Shearing also generates a force that attempts to separate the two tools with changed shearing conditions through increased clearance between the tools as result. Tool clearance is also the most common shearing parameter to adjust, depending on material grade and sheet thickness, to moderate the required force and to control the final sheared edge geometry.In this work, an experimental procedure that provides a stable tool clearance together with accurate measurements of tool forces and tool displacements, was designed, built and evaluated. Important shearing parameters and demands on the experimental set-up were identified in a sensitivity analysis performed with finite element simulations under the assumption of plane strain. With respect to large tool clearance stability and accurate force measurements, a symmetric experiment with two simultaneous shears and internal balancing of forces attempting to separate the tools was constructed.Steel sheets of different strength levels were sheared using the above mentioned experimental set-up, with various tool clearances, sheet clamping and rake angles. Results showed that tool penetration before fracture decreased with increased material strength. When one side of the sheet was left unclamped and free to move, the required shearing force decreased but instead the force attempting to separate the two tools increased. Further, the maximum shearing force decreased and the rollover increased with increased tool clearance.Digital image correlation was applied to measure strains on the sheet surface. The obtained strain fields, together with a material model, were used to compute the stress state in the sheet. A comparison, up to crack initiation, of these experimental results with corresponding results from finite element simulations in three dimensions and at a plane strain approximation showed that effective strains on the surface are representative also for the bulk material.A simple model was successfully applied to calculate the tool forces in shearing with angled tools from forces measured with parallel tools. These results suggest that, with respect to tool forces, a plane strain approximation is valid also at angled tools, at least for small rake angles.In general terms, this study provide a stable symmetric experimental set-up with internal balancing of lateral forces, for accurate measurements of tool forces, tool displacements, and sheet deformations, to study the effects of important shearing parameters. The results give further insight to the strain and stress conditions at crack initiation during shearing, and can also be used to validate models of the shearing process.
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5.
  • Hemmingsson, Eva-Stina, et al. (författare)
  • Prevalence of pain and pharmacological pain treatment among old people in nursing homes in 2007 and 2013
  • 2018
  • Ingår i: European Journal of Clinical Pharmacology. - : Springer. - 0031-6970 .- 1432-1041. ; 74:4, s. 483-488
  • Tidskriftsartikel (refereegranskat)abstract
    • PurposeMany elderly people living in nursing homes experience pain and take analgesic medication. The aim of this study was to analyze the prevalence of pain and pharmacological pain treatment among people living in nursing homes in Sweden, in two large, comparable, samples from 2007 to 2013.MethodsCross-sectional surveys were performed in 2007 and 2013, including all residents in nursing homes in the county of Västerbotten, Sweden. A total of 4933 residents (2814 and 2119 respectively) with a mean age of 84.6 and 85.0 years participated. Of these, 71.1 and 72.4% respectively were cognitively impaired. The survey was completed by the staff members who knew the residents best.ResultsThe prescription of opioids became significantly more common while the use of tramadol decreased significantly. The staff reported that 63.4% in 2007 and 62.3% in 2013 had experienced pain. Of those in pain, 20.2% in 2007 and 16.8% in 2013 received no treatment and 73.4 and 75.0% respectively of those with pain, but no pharmacological treatment, were incorrectly described by the staff as being treated for pain.ConclusionsThere has been a change in the pharmacological analgesic treatment between 2007 and 2013 with less prescribing of tramadol and a greater proportion taking opioids. Nevertheless, undertreatment of pain still occurs and in many cases, staff members believed that the residents were prescribed analgesic treatment when this was not the case.
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  • Karlsson, Jan, et al. (författare)
  • Observation of the mechanisms causing two kinds of undercut during laser hybrid arc welding
  • 2011
  • Ingår i: Applied Surface Science. - : Elsevier BV. - 0169-4332 .- 1873-5584. ; 257:17, s. 7501-7506
  • Tidskriftsartikel (refereegranskat)abstract
    • Two different kinds of undercut were identified when laser hybrid welding hot rolled HSLA-steel in either the as-rolled condition or with the top surface mill scale removed. The presence of mill scale on the steel surface was found to give a sharp angled undercut combined with a sharp oxide inclusion at the edge of the weld which would have the same mechanical effect as a crack in this position. Removal of the surface oxides before welding resulted in the elimination of the oxide inclusions and a more rounded undercut geometry indicative of superior mechanical properties, particularly fatigue life. The mechanisms of the formation of both types of undercut have been analysed by high speed photography and SEM.
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10.
  • Karlsson, Kristoffer (författare)
  • Gap discharge transducers applied to ultrasonic flow measurement
  • 2012
  • Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
    • In this thesis, the potential of the gap discharge transducer is investigated as both a sound pulse emitter and a sound pulse receiver in a gas flow measurement setup. The main objective is to use the gap discharge transducer as an integral part in a gas flow measurement system developed for harsh environments. The idea for the method considered in this study to determine the flow was taken from the time-of-flight technique used in ultrasonic flow measurements. The gap discharge transducer should then be used as both an emitter and a receiver in a setup that somewhat mimics those in ultrasonics. Earlier studies with the gap discharge transducer has shown that it is both very durable and a potent sound pulse emitter. This thesis continues these studies by incorporating the transducer into a measurement system as an emitter and also investigates its capabilities to be used as a sound pulse receiver. As an emitter in a flow measurement system the transducer was placed in a pipe with a variable flow in a laboratory environment. The transducer was set to generate sparks to create the sound pulse and standard piezoelectric receivers were used to capture the signal.To determine the possibilities to use the transducer as a receiver the transducer was placed in a vacuum chamber to test the dependence between breakdown voltage and pressure. Since a sound pulse is a change in pressure the pulse might cause breakdown in the gap between the electrodes of the transducer if an initial voltage between the electrodes is set close enough to breakdown. The investigation shows that the gap discharge transducer is a potential sound pulse emitter in a flow measurement system and, with some small calibration and more precise alignment, is capable to determine the flow quite accurately. On the other hand, to use the transducer as a receiver is concluded to be very difficult. The breakdown voltage is too unstable to allow an initial voltage close to breakdown to be set without risking spontaneous breakdown due to random events.
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