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- Bäckström, Christer, et al.
(författare)
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From Macro Plans to Automata Plans
- 2012
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Ingår i: ECAI 2012. 20th European Conference on Artificial Intelligence, 27-31 2012, August, Montpellier, France. - 9781614990970 - 9781614990987 ; , s. 91-96
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Konferensbidrag (refereegranskat)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.
(författare)
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Macros, Reactive Plans and Compact Representations
- 2012
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Ingår i: ECAI 2012. 20th European Conference on Artificial Intelligence 27-31 August 2+12, Montpellier, France. - 9781614990970 - 9781614990987 ; , s. 85-90
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Konferensbidrag (refereegranskat)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.
(författare)
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When Acyclicity is not Enough: Limitations of the Causal Graph
- 2013
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Ingår i: Proceedings of the Twenty-Third International Conference on Automated Planning and Scheduling. - : AAAI Press. - 9781577356097 ; , s. 117-125
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Konferensbidrag (refereegranskat)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.
(författare)
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SMALL SCALE IN-SITU BIOREMEDIATIONOF DIESEL CONTAMINATED SOIL –SCREENING LIFE CYCLE ASSESSMENT OF ENVIRONMENTAL PERFORMANCE
- 2010
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Ingår i: ECO-TECH´10, 22-24 November 2010, Kalmar, Sweden. ; , s. 827-835
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)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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- Gustafsson, Mats, et al.
(författare)
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Physical bounds on the partial realized gain
- 2010
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Ingår i: [Host publication title missing]. ; , s. 1-6
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Konferensbidrag (refereegranskat)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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- Haller, Henrik, et al.
(författare)
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TURNING WASTE INTO A RESOURCE FOR REMEDIATION OF CONTAMINATED SOIL IN TROPICAL DEVELOPING COUNTRIES
- 2012
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Ingår i: PROCEEDINGS LINNAEUS ECO-TECH 2012. ; , s. 468-480
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Contaminated soil from industrial or agricultural activities poses a health threat to animals and humans and can also have a detrimental effect on economic systems by making land unsuitable for agriculture and other economic purposes. This problem is of particular concern in tropical developing countries where agriculture is the economic base. Traditional methods for soil remediation are often expensive and energy consuming. In-situ bioremediation has been proposed as a cheaper alternative to conventional methods in areas where remediation would otherwise not be implemented. Despite encouraging results in the laboratory, the practice of in-situ bioremediation is limited, partially due to its inefficiency at low temperatures. The objective of this study is to provide an inventory of some waste products that potentially can be used as amendments for in-situ bioremediation in developing countries in tropical climate. Emphasis has been given to map efficient methods that are appropriate to economically marginalised people in such countries. Waste from livestock operations, crop residues and processing waste constitute the major waste flows in many developing countries. A number of organic by-products can potentially be used to stimulate microbial activity for bioremediation purposes. Three amendments; whey, pyroligneous acid and compost teas were selected to be studied in detail due to their liquid nature and documented capacity to stimulate microorganisms with capacity to degrade pollutants. Experiments are needed to determine their potential for in-situ bioremediation in developing countries in tropical climate.
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| 10. |
- Johansson, Björn, 1975, et al.
(författare)
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Sustainable Production by Integrating Business Models of Manufacturing and Recycling Industries
- 2011
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Ingår i: Proceedings of the 18th CIRP International Conference on Life Cycle Engineering. - 3642196918 ; , s. 723-
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Konferensbidrag (refereegranskat)abstract
- Future raw material shortage, high price levels and environmental regulations requires increased reuse of materials andcomponents. This will substantially influence conditions for both manufacturing and recycling industries, which need toinnovate their business models. Our hypothesis is that an integrated co-operation between organizations within these industries, employing symbiotic business models will increase the profitability and reduce the total environmental impact. Findings from interaction with manufacturing and recycling industries using a business model framework as baseline are presented. Results indicate that profit and decreased environmental effects can be achieved through symbiotic business models, but further development and implementation is needed.
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