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- Bäckström, Christer, et al.
(author)
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From Macro Plans to Automata Plans
- 2012
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In: ECAI 2012. 20th European Conference on Artificial Intelligence, 27-31 2012, August, Montpellier, France. - 9781614990970 - 9781614990987 ; , s. 91-96
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Conference paper (peer-reviewed)abstract
- Macros have a long-standing role in planning as a tool for representing repeating subsequences of operators. Macros are useful both for guiding search towards a solution and for representing plans compactly. In this paper we introduce automata plans which consist of hierarchies of finite state automata. Automata plans can be viewed as an extension of macros that enables parametrization and branching. We provide several examples of the utility of automata plans, and prove that automata plans are strictly more expressive than macro plans. We also prove that automata plans admit polynomialtime sequential access of the operators in the underlying “flat” plan, and identify a subset of automata plans that admit polynomial-time random access. Finally, we compare automata plans with other representations allowing polynomial-time sequential access.
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- Bäckström, Christer, et al.
(author)
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Macros, Reactive Plans and Compact Representations
- 2012
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In: ECAI 2012. 20th European Conference on Artificial Intelligence 27-31 August 2+12, Montpellier, France. - 9781614990970 - 9781614990987 ; , s. 85-90
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Conference paper (peer-reviewed)abstract
- The use and study of compact representations of objects is widespread in computer science. AI planning can be viewed as the problem of finding a path in a graph that is implicitly described by a compact representation in a planning language. However, compact representations of the path itself (the plan) have not received much attention in the literature. Although both macro plans and reactive plans can be considered as such compact representations, little emphasis has been placed on this aspect in earlier work. There are also compact plan representations that are defined by their access properties, for instance, that they have efficient random access or efficient sequential access. We formally compare two such concepts with macro plans and reactive plans, viewed as compact representations, and provide a complete map of the relationships between them.
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- Jonsson, Anders, et al.
(author)
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When Acyclicity is not Enough: Limitations of the Causal Graph
- 2013
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In: Proceedings of the Twenty-Third International Conference on Automated Planning and Scheduling. - : AAAI Press. - 9781577356097 ; , s. 117-125
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Conference paper (peer-reviewed)abstract
- Causal graphs are widely used in planning to capture the internal structure of planning instances. In the past, causal graphs have been exploited to generate hierarchical plans, to compute heuristics, and to identify classes of planning instances that are easy to solve. It is generally believed that planning is easier when the causal graph is acyclic. In this paper we show that this is not true in the worst case, proving that the problem of plan existence is PSPACE-complete even when the causal graph is acyclic. Since the variables of the planning instances in our reduction are propositional, this result applies to STRIPS planning with negative pre-conditions. Having established that planning is hard for acyclic causal graphs, we study a subclass of planning instances with acyclic causal graphs whose variables have strongly connected domain transition graphs. For this class, we show that plan existence is easy, but that bounded plan existence is hard, implying that optimal planning is significantly harder than satisficing planning for this class.
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- Akambih Tajam, Joseph, et al.
(author)
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SMALL SCALE IN-SITU BIOREMEDIATIONOF DIESEL CONTAMINATED SOIL –SCREENING LIFE CYCLE ASSESSMENT OF ENVIRONMENTAL PERFORMANCE
- 2010
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In: ECO-TECH´10, 22-24 November 2010, Kalmar, Sweden. ; , s. 827-835
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Conference paper (other academic/artistic)abstract
- Spillage of diesel oil and other petroleum products is a commonly creating need for siteremediation of contaminated soils. In Sweden the most common remediation action isexcavation of the contaminated soil and off site biological treatment by composting.However, a number of small sites spread out in rural areas end up low on priority lists, andwill not be attended to within foreseeable future if ever. For such areas a low cost, easy toapply remediation techniques would be of interest. Enhanced bioremediation of dieselcontaminants in soil by whey addition has been demonstrated in lab scale. Whey is a byproductfrom cheese production. A first pilot remediation trial on an actual site in Gäddede,County of Jämtland, was started the summer of 2010. Using this site as a case study ascreening life cycle assessment model has been set up. The goal of the study was toinvestigate the environmental performance of the whey method, to benchmark the wheymethod toward the excavation and composting practice and to identify environmental hotspots in the whey treatment life cycle. The study aims at establishing if further work shouldbe put into developing the method, or if the environmental performance is such that the wheymethod should be abandoned. It should be noted that even with a slightly worseenvironmental performance compared to other remediation alternatives whey treatment couldstill be of interest, since the small scale sites in rural areas we talk about here otherwise mostoften would not be attended to.Results from the screening life cycle assessment indicate a rather good environmentalperformance of the whey method, partly depending on impact category considered. For thewhey method, impacts from farming activities in the milk production chain allocated to thewhey give significant contributions. Transportation gives important impacts from both thewhey method and the excavation and off site composting, thus logistics should always beconsidered and optimized. The whey on-site treatment could be an interesting alternative forbioremediation especially at sites that would not otherwise be treated, due to small size orremote location.
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- Backlund, Per, et al.
(author)
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Pre-hospital training and simulation initiative
- 2014
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Conference paper (peer-reviewed)abstract
- Background The pre-hospital process is a complex one involving aspects such as medical skills as well as care taking, team performance, inter-organizational cooperation and communication. This calls for novel training methods and technology support. Our review of literature (covering the areas of pre-hospital care, training simulator technologies and methods and process modelling) indicates that the different aspects are typically trained in isolation, e.g. medical skills using patient simulators.Objective The pre-hospital training center project addresses the overall complexity of the pre-hospital process by taking all of the aspects into account when designing scenarios and technology support for training the complete prehospital process (covering alarm, on-scene activities, transportation and hand-over). This is indeed a challenging task as we need to develop both training methods and technology support for a very complex training situation.Methods The project will develop a prototype scenario along with technology support to enact it. The training scenario will involve many of the aspects listed above and will be tested in a field experiment with ambulance personnel. Results The expected outcome of the project is a platform for establishing a pre-hospital simulation and training center. The initial technologies, research results and experiences will be used to form a consortium for further work and development. Conclusions We have identified a need for a pre-hospital training center with the unique and ambitious idea of covering the entire pre-hospital process as well as its many interacting aspects. To the best of our knowledge this approach is not at all common and we expect the complexity to be so high that it is a challenging enough research area that can only be addressed if we have a well-designed simulation and training center in place with all the different areas of knowledge represented, i.e. pre-hospital medicine as well as simulation and visualization technology.
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- Grönlund, Erik, et al.
(author)
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Ekoteknik (Ecotechnics / Ecotehcnology) – 30 Years of Experience in Interdiciplinery Education
- 2014
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In: Proceedings of the 20th International Sustainable Development Research Conference Trondheim 18-20 June 2014. - Trondheim : Norwegian University of Science and Technology, Department of Product Design. - 9788291917344 ; , s. 17-21
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Conference paper (peer-reviewed)abstract
- An important part of a society’s resilience is how prepared it is to cope with the changing conditions during the alpha and omega phases according to resilience theory. Lars Thofelt, an academic from the mid Sweden region, early recognized this need for students to develop skills needed for a societal change, and devoted his life to pedagogy suitable for this. The main outcome of his achievement was the interdisciplinary university program in Ecotechnics/Ecotechnology (Ekoteknik in Swedish), at Mid Sweden University. Ecology, economy and technology in cooperation for sustainable development were the original approach, and still are.Thofelt’s ideas had a main focus of helping students develop their inherent capabilities of solving problems and overcome obstacles. After Thofelt’s 12 years at the program his ideas were carried on by former colleagues and students, and the teaching further developed with a mix of the Thofelt tradition and other experiences brought in by new employees. This paper describes this interdisciplinary teaching approach with special focus on development of resilience capacity in students.It was concluded that 1) a key element to develop resilience skills in students is to push them to a self-propelled learning behavior rather than traditional teaching, 2) not too easily provide the students with answers will develop their problem solving skills, 3) doing-before-reading teaching is more time consuming but seem to give deeper knowledge, 4) interdisciplinary teaching will in the long run benefit from having the interdisciplinary team within the department, rather than as a conglomerate of several departments.
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| 10. |
- Gustafsson, Mats, et al.
(author)
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Physical bounds on the partial realized gain
- 2010
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In: [Host publication title missing]. ; , s. 1-6
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Conference paper (peer-reviewed)abstract
- An antenna identity, derived from the forward scattering sum rule, shows that the partial realized gain of an antenna is related to the polarizability of the antenna structure. The partial realized gain contains the mismatch, directivity, efficiency, and polarization properties of the antenna. The antenna identity expresses how the performance depends on the electrical size and shape of the antenna structure. It is also the starting point for several antenna bounds. In this paper, the identity, its associated physical bounds, and computational aspects of the polarizability dyadics are discussed.
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