| 1. |
- Andersen, Emelie, 1989-, et al.
(författare)
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Survival possibilities of the dragonfly Aeshna viridis (Insecta, Odonata) in southern Sweden predicted from dispersal possibilities
- 2016
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Ingår i: Journal of Insect Conservation. - Dordrecht : Springer Netherlands. - 1366-638X .- 1572-9753. ; 20:2, s. 179-188
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Tidskriftsartikel (refereegranskat)abstract
- We use public records from 1980 to 2014 to analyse survival of the EU Annex IV species Aeshna viridis in Sweden, a dragonfly strongly associated with the plant Stratiotes aloides. We clustered localities with S. aloides based on assumed dispersal abilities of A. viridis, using a dispersing radius of 2–100 km, calculating the proportion of sites with S. aloides that A. viridis is able to reach. If mean dispersal capability is high (40 km or above) 92.6 % or more of the localities are connected. For a good disperser, the probability of long-time survival is good. We further analysed the species richness of other Odonata and aquatic plants at 98 localities from the dataset. A. viridis co-occurred with more Odonata in the presence of S. aloides and running water but not in lakes. S. aloides sites had a higher number of other aquatic plants. Area had no impact on the occurrence of the species. For the present situation we surveyed 32 localities with known occurrence of the species. Only half of the sites for S. aloides contained any specimens while A. viridis occurred in the same number of sites. The species co-occurred in only 8 of 32 sites. In four sites A. viridis larvae appeared among Menyanthes trifoliata, Phragmites australis, Potamogeton natans and Sphagnum spp., indicating that at high latitudes A. viridis breeds among other species. Indirect monitoring based only on S. aloides would underestimate the number of populations of the dragonfly. © 2016 Springer International Publishing Switzerland
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| 2. |
- Gåård, Anders, et al.
(författare)
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Införandet av Computer Based Mathematics (CBM) i ingenjörsutbildningar
- 2017
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Konferensbidrag (populärvet., debatt m.m.)abstract
- CBM är ett koncept som innebär användning av datorn och matematikprogramvaror som huvudverktyg i under-visningen. Istället för att som i traditionell undervisning kombinera handräkning med datorlabbar ligger tyngdpunkten i en CBM-kurs på datoriserade beräkningsverktyg. Härav för-flyttas fokus mot konceptförtåelse, modellering och tolkning av resultat. Vid Högskolan i Halmstad och Karlstads Universitet finns idag flera kurser baserat på CBM. Kvantitativt har införandet lett till ökad studentgenomströmning samtidigt som innehållet i kurser har ökat. Kvalitativa markörer, såsom studentens egen uppfattning om konceptuell förståelse och nyfikenhet inom ämnet, har baserat på kursvärderingar också ökat.
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| 3. |
- Nilsson, Bertil, 1953-, et al.
(författare)
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A goal oriented adaptive finite element method for hydrodynamic lubrication
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- We present a goal-oriented adaptive finite element method for a cavitation model based on Reynolds' equation. A posteriori error estimates and adaptive algorithms are derived, and numerical examples illustrating the theory are supplied.
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| 4. |
- Nilsson, Bertil, 1953-, et al.
(författare)
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A Stokes model with cavitation for the numerical simulation of hydrodynamic lubrication
- 2011
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Ingår i: International Journal for Numerical Methods in Fluids. - Chichester, Sussex : Wiley. - 0271-2091 .- 1097-0363. ; 67:12, s. 2015-2025
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Tidskriftsartikel (refereegranskat)abstract
- We present a cavitation model based on the Stokes equation and formulate adaptive finite element methods for its numerical solution. A posteriori error estimates and adaptive algorithms are derived, and numerical examples illustrating the theory are supplied, in particular with comparison to the simplified Reynolds model of lubrication.
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| 5. |
- Nilsson, Bertil, 1953-, et al.
(författare)
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Adaptive finite element methods for hydrodynamic lubrication with cavitation
- 2007
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Ingår i: International Journal for Numerical Methods in Engineering. - Chichester : John Wiley & Sons. - 0029-5981 .- 1097-0207. ; 72:13, s. 1584-1604
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Tidskriftsartikel (refereegranskat)abstract
- We present an adaptive finite element method for a cavitation model based on Reynolds' equation. A posteriori error estimates and adaptive algorithms are discussed, and numerical examples illustrating the theory are supplied.
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| 6. |
- Nilsson, Bertil, 1953-
(författare)
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Adaptive Finite Element Methods for the Reynolds Thin Film Model with Cavitation
- 2005
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The main purpose of this thesis is to use modern goal-oriented adaptive finite element techniques in order to improve the numerical simulation of tribology. Two novel adaptive finite element methods for the Reynolds thin film model including cavitation are presented and their different strategies are compared. The algorithms are inspired by an analogy with the obstacle problem and the cavitation problem that we consider is written as a variational inequality considering in the formulation the fact that the lubricant can not stand negative stresses induced by sub-atmospheric pressure. A posteriori, error estimates and adaptive algorithms are derived, and numerical examples illustrating the theory are supplied. The cavitation problem and calculations is introduced and put into historical and modern perspective. Modern thoughts and techniques around the oil-pocket idea in sheet metal forming are presented. The influence of oil pockets on the contact regime is assessed, and in particular the likely effect of oil-pocket-induced cavitation in order to produce lift, is discussed. The ultimate goal with the numerical simulation is to be able to optimize the surface structure so as to take advantage of cavitation effects in the lubricant.
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| 7. |
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| 8. |
- Nilsson, Björn, 1965-, et al.
(författare)
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An active backscatter wake-up and tag identification extraction protocol for low cost and low power active RFID
- 2010
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Ingår i: Proceedings of 2010 IEEE International Conference on RFID-Technology and Applications, RFID-TA 2010. - Piscataway, NJ : IEEE Press. - 9781424466986 - 9781424467006 ; , s. 86-91
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Konferensbidrag (refereegranskat)abstract
- In this paper we present a Radio Frequency Identification (RFID) protocol used to wake up and extract the ID of every tag (or a subset thereof) within reach of a reader in an active backscatter RFID system. We also study the effect on tag energy cost and read-out delay incurred when using the protocol, which is based on a frequency binary tree. Simulations show that, when using the 2.45 GHz ISM band, more than 1500 tags can be read per second.With a population of 1000 tags, the average read-out delay is 319 ms, and the expected lifetime of the RFID tags is estimated to be more than 2.5 years, even in a scenario when they are read out very often.
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