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- Andersson, Annika
(författare)
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Frazil ice at water intakes
- 1997
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- To provide a better understanding of how frazil ice deposits on trash racks at water intakes, the phenomenon was video recorded at two hydropower plants and in a refrigerated laboratory flume. Initial accretion of frazil ice around a single bar and the motion of particles in the vicinity of an obstacle was simulated through numerical modelling and studied using plastic particles in a laboratory flume. Ice initially accumulates on the upstream face of the bars, and it progresses then to the upstream sides of the bars. Tha frazil ice layer grows in all directions, and it finally bridges over the spaces between bars. The ice blockage starts at the upper part of the rack and progresses downward. The head losses across each intake, which are observed continuously at the plants, illustrate the degree and importance of ice growth. Observations from laboratory experiments with a single bar in a flume, showed that frazil ice particles deposited on all bar surfaces. Separate flume tests were run with plastic particles simulating ice particles. The frequency of collision of these particles with the front face of a rectangular bar varied with the particle density and the fluid velocity. In a test with particles of various sizes, the smaller particles were more likely to enter the side wake than larger ones. A mathematical model can be used to predict patterns of ice deposition that correspond to the observed results. Such a model must include a hydrodynamic part for viscous flows and a particle trajectory model. Some models neglect the term for force due to pressure gradient in their calculations of a particle trajectory because the particles had larger density than the surrounding fluid. Ice particles have almost the same density as the water and simulated results showed that this term, caused by the pressure gradient, is the dominant force that counter the momentum of the particles when they move in the region close to the obstacle. The simulated results were affected by the particle size distribution, therefore the size distribution of frazil ice particles in a river is a factor in further studies. In tests in which no particles were allowed to deposit on the front part of the bar, in a simulation of a heated bar, lesser amounts deposited on the other parts of the bar. Knowledge of the way frazil ice accumulates on water intakes and the initial ice accretion on individual trash racks should be valuable in future work for finding methods to reduce the ice blockage and in the verification of more detailed model studies.
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- Banakar, Reza
(författare)
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Salman Rushdie och liberalismens heliga ko
- 1992
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Ingår i: Häften för kritiska studier. - 0345-4789. ; 25:2, s. 3-14
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Tidskriftsartikel (refereegranskat)abstract
- Ställd inför det religiöst motiverade dödsdomen mot en välkänd författare har opinionen i väst stirrat sig blind på en enda aspekt av "Rushdie-affären": den hotade tryckfriheten. Denna artikel analyserar andra sidor av konflikten och söker dess rötter i problem som uppkommer i ett multikulturellt samhälle – problem som även finns i Sverige.
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- Brolin Låftman, Sara, et al.
(författare)
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Do health complaints in adolescence negatively predict the chance of entering tertiary education in young adulthood?
- 2017
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Ingår i: Scandinavian Journal of Public Health. - : SAGE Publications. - 1403-4948 .- 1651-1905. ; 45:8, s. 878-885
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Tidskriftsartikel (refereegranskat)abstract
- Background: Self-reported psychological and psychosomatic health complaints, such as nervousness, sadness, headache and stomach-ache, are common among adolescents, particularly among girls, and studies suggest that the prevalence has risen among adolescent girls during the last few decades. However, only a limited number of studies have investigated the potential long-term consequences of such health complaints. The aim of the current study was to assess whether psychological and psychosomatic health complaints in adolescence predict the chance of entering tertiary education in young adulthood among women and men. Methods: The data used are from the Swedish Young-LNU, which is based on a nationally representative sample with self-reported survey information from adolescents aged 10–18 years in 2000 and from the same individuals at ages 20–28 in 2010 (n=783). Information was also collected from parents and from official registers. Results: Linear probability models showed that self-reported psychological complaints in adolescence were associated with a lower chance of having entered tertiary education 10 years later. This association was accounted for by differences in grade point average (GPA), suggesting that GPA may mediate the association between psychological complaints and later education. The pattern was similar for both genders. Furthermore, among men, psychosomatic complaints in adolescence were significantly associated with a lower likelihood of having entered tertiary education 10 years later when adjusting for GPA and social class in adolescence. A similar but non-significant tendency was found among women. Conclusions: The findings suggest that health complaints in adolescence may have long-term consequences in terms of lower educational attainment.
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- Burghout, Wilco, et al.
(författare)
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Incident management and traffic information : Simulation-based traffic prediction
- 2009
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Ingår i: 16th ITS World Congress.
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Konferensbidrag (refereegranskat)abstract
- Incident response and mitigation are the main tasks of operators at traffic control centres. Simulation models have a good chance of reproducing and predicting the effects of incident response by explicitly modelling drivers' responses to the incident and provided information. In the PREDIKT project, sponsored by the Swedish National Road Administration, a state-of-the-art mesoscopic simulation model (MEZZO) has been extended to provide decision support for incident management. In this paper we describe and test a number of essential modelling components such as modelling the incident response logic, a mixed-Logit model and a method for generation of alternative routes for drivers' route switching. In addition we present the results of a fast calibration method based on Simultaneous Perturbation Statistic Approximation (SPSA). The model components are tested in a small case study that investigates the impact of delay in information after incidents.
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- Černiavski, Rafal, et al.
(författare)
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Uppsala University at SemEval-2022 Task 1 : Can Foreign Entries Enhance an English Reverse Dictionary?
- 2022
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Ingår i: Proceedings of the 16th International Workshop on Semantic Evaluation (SemEval-2022). - Stroudsburg, PA, USA : Association for Computational Linguistics. - 9781955917803 ; , s. 88-93
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Konferensbidrag (refereegranskat)abstract
- We present the Uppsala University system for SemEval-2022 Task 1: Comparing Dictionaries and Word Embeddings (CODWOE). We explore the performance of multilingual reverse dictionaries as well as the possibility of utilizing annotated data in other languages to improve the quality of a reverse dictionary in the target language. We mainly focus on characterbased embeddings. In our main experiment, we train multilingual models by combining the training data from multiple languages. In an additional experiment, using resources beyond the shared task, we use the training data in Russian and French to improve the English reverse dictionary using unsupervised embeddings alignment and machine translation. The results show that multilingual models occasionally but not consistently can outperform the monolingual baselines. In addition, we demonstrate an improvement of an English reverse dictionary using translated entries from the Russian training data set.
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