| 801. |
- Johansson, Stefan, et al.
(författare)
-
Using the electric field approach in the RoboCup domain
- 2002
-
Ingår i: RoboCup 2001. - Berlin, Heidelberg : Springer Berlin Heidelberg. - 9783540439127 ; , s. 117-138
-
Konferensbidrag (refereegranskat)abstract
- In autonomous robotics, so-called artificial potential fields are often used to plan and control the motion of a physical robot. In this paper, we propose to use an artificial electric field to address the problem or real time action selection in embodied, autonomous agents. We attach positive and negative electric charges to the relevant objects in the agent's domain, and use the resulting electric field to estimate the heuristic value of a given configuration. This value is used to select the action that results in the best configuration. This allows us to consider in the same framework both navigation and manipulation actions. We apply the electric field approach in the RoboCup domain, and present results drawn from our experience in the Sony legged robots league
|
|
| 802. |
|
|
| 803. |
|
|
| 804. |
- Johansson, Stefan, 1980
(författare)
-
Validitet och lärares bedömningar
- 2015
-
Ingår i: Pedagogisk forskning i Sverige. - 1401-6788. ; 20:1-2, s. 33-53
-
Tidskriftsartikel (refereegranskat)
|
|
| 805. |
- Johansson, Stefan
(författare)
-
Very preterm birth : etiological aspects and short and long term outcomes
- 2008
-
Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Very preterm birth, occurring before 32 completed weeks of gestation, is an often unexplained pregnancy complication affecting approximately 1 to 2 percent of all births. This thesis includes four studies regarding the etiology, and short and long term outcomes of very preterm birth, using Swedish population-based data. The aims were to investigate if viral infections during pregnancy increase the risk of very preterm delivery, to study the role of level of care for infant mortality in very preterm infants, and to explore long-term health in adults born very preterm, with regard to high blood pressure and type 2 diabetes. Among pregnant women in Stockholm, we identified 269 cases of very preterm birth and 301 controls with term delivery, with archived blood sampled for the Rubella serology screening in early pregnancy. Serum was investigated for presence of viral genetic material. Any viremia was detected in 10 cases and in 5 controls, corresponding to an adjusted odds ratio (95 percent confidence interval) of 2.21 (0.71-6.84). Although risk estimates were consistently elevated for any viremia and for Parvovirus B19, none were significant on a 5 percent level. Whether viral infections during pregnancy increase the risk of very preterm birth needs to be investigated in larger studies. During 1992-98, 2,253 liveborn singleton infants were born very preterm in Swedish general and university hospitals. Infant mortality rates increased by decreasing gestational age, from 5 percent at 31 weeks to 56 percent at 24 weeks. Very preterm birth at a general hospital was associated with an increased risk of infant mortality, but the risk increase was confined to extremely preterm infants born at 24 to 27 weeks, having an adjusted odds ratio for infant mortality of 2.00 (1.15-3.49). Among 329,495 young men born in Sweden 1973-81 and conscripted for military service, gestational age at birth was inversely related to high systolic blood pressure at conscription (>=140 mm Hg). Adjusted odds ratios among men born very and extremely preterm (29-32 weeks and 24-28 weeks, respectively) were 1.45 (1.28-1.64) and 1.88 (1.33-2.68), respectively. The association was not confounded by familial (common genetic and shared environmental) factors. In addition, being born small for gestational age was not a risk factor of high systolic blood pressure among men born at 24 to 32 gestational weeks, but increased the risk among men born moderately preterm (33-36 weeks) and at term (>=37 weeks). In a cohort of 18,230 Swedish twins, rates of type 2 diabetes increased with decreasing gestational age and with decreasing birth weight. In cohort analyses there was no association between preterm birth and type 2 diabetes, whereas risk of type 2 diabetes increased with decreasing birth weight. However, in co-twin case-control analyses, an increased risk of type 2 diabetes with lower birth weight was found within dizygotic but not within monozygotic twin pairs. Odds ratios per 500 grams decrease in birth weight were 1.38 (1.02-1.85) and 1.02 (0.63-1.64), respectively, indicating genetic confounding of the association between low birth weight and type 2 diabetes.
|
|
| 806. |
|
|
| 807. |
|
|
| 808. |
|
|
| 809. |
- Johansson, Stefan, et al.
(författare)
-
Wordlength Optimization of a Pipelined FFT Processor
- 1999
-
Ingår i: 42nd Midwest Symposium on Circuits and Systems, 1999.. - 0780354915 ; 1, s. 501-503
-
Konferensbidrag (refereegranskat)abstract
- This paper describes the optimization of the word lengths in an 8 k-points pipelined FFT processor. The word lengths can be freely chosen since the FFT is implemented as a full custom ASIC. According to the specification, input and output word lengths are 12 bits but improved performance on be achieved by using a longer wordlength internally. Increased wordlength means increased size, both for memory and arithmetic operations. Since the FFT processor uses large memories, especially in the early stages, it is especially important to keep wordlength short in the beginning of the pipeline. Finding a good trade-off between precision and size is a difficult problem and it is not reasonable to solve analytically. Simulations using a C-model are therefore used to find an acceptable solution. The simulations show that a good solution is obtained by starting with 12 bits and gradually increasing the wordlength up to 16 bits. The final result is rounded back to 12 bits. This is a good trade-off between precision and complexity
|
|
| 810. |
- Johansson Sevä, Ingemar, 1965-
(författare)
-
Welfare state attitudes in context : local contexts and attitude formation in Sweden
- 2009
-
Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Welfare state attitudes are often studied from the perspective of the individual's characteristics and/or national or regime-type contexts. This thesis instead seeks explanations for individuals' varying attitudes towards the welfare state at the level of local contexts (municipalities). Sweden is used as a case for testing whether there are such contextual effects. The general aim is to find out whether social, political, and institutional aspects of local context influence the attitudes of individuals. Since the general aim of this thesis is to examine how background characteristics of individuals and characteristics of local contexts simultaneously act in shaping individuals' attitudes, I use multilevel modelling in order to handle individual-level and contextual-level data simultaneously. Latent-class analysis (LCA) is also employed in the analyses to explore the patterning of variables. This is mainly done in order to create dependent variables and to distinguish between categories of municipalities sharing similar characteristics. The data consist of Swedish survey data, which have been complemented by municipal-level data. The findings indicate that the social and political context of municipalities can matter for individuals' attitude formation. Variation across municipalities in terms of the prevalence of social problems and risks seems to influence how individuals view the welfare state. Local municipal contexts characterized by many social problems and risks tend to be associated with more welfare state friendly attitudes among the local inhabitants, after taking individual-level determinants into account. Support for high social spending is greater in such milieus as is the tendency to view welfare beneficiaries with less suspicion regarding the potential abuse of welfare policies. Regarding the influence of local public service provision on attitudes, no evidence was found for feedback effects on individuals' attitudes toward public service privatization. In their attitudes towards the welfare state, individuals are to some extent influenced by their local environment. There seems to be a 'built in' thermostat in the Swedish welfare state. Local circumstances characterized by social problems and risks tend to be associated with a local citizenry having more welfare state-friendly attitudes.
|
|
