| 1. |
- Efsing, Pål, 1965-, et al.
(författare)
-
IGSCC DISPOSITION CURVES FOR ALLOY 82 IN BWR NORMAL WATER CHEMISTRY
- 2007
-
Ingår i: 13th International Conference on Environmental Degradation of Materials in Nuclear Power Systems. - 9781605600598 - 9781605600598 ; , s. 1353-1363
-
Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- In many nuclear power plants, areas of susceptible material in the reactor systems are replaced or mitigated. Many of the areas where the nickel-based weld metal Alloy 182 have been used, are not replaceable but need to be mitigated. One possibility to mitigate is to make known susceptible material non-accessible for the reactor coolant water by covering it with less susceptible materials. One such possibility that has been utilized frequently in the Swedish Boiling Water Reactor (BWR) fleet is in-lay welding of butt welds in the main circulation and feed water loops with the less susceptible Alloy 82, which has fewer reported failure cases under these conditions. The study focuses on the development of a Factor of Improvement between Alloy 182 and the replacement, Alloy 82 material. As part of this, a disposition curve under conditions relevant for Normal Water Chemistry, NWC, in the Swedish BWRs is presented.
|
|
| 2. |
- Felsberg, Michael, 1974-, et al.
(författare)
-
Exploratory Learning Strucutre in Artificial Cognitive Systems
- 2007
-
Ingår i: International Cognitive Vision Workshop. - Bielefeld : eCollections.
-
Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- One major goal of the COSPAL project is to develop an artificial cognitive system architecture with the capability of exploratory learning. Exploratory learning is a strategy that allows to apply generalization on a conceptual level, resulting in an extension of competences. Whereas classical learning methods aim at best possible generalization, i.e., concluding from a number of samples of a problem class to the problem class itself, exploration aims at applying acquired competences to a new problem class. Incremental or online learning is an inherent requirement to perform exploratory learning. Exploratory learning requires new theoretic tools and new algorithms. In the COSPAL project, we mainly investigate reinforcement-type learning methods for exploratory learning and in this paper we focus on its algorithmic aspect. Learning is performed in terms of four nested loops, where the outermost loop reflects the user-reinforcement-feedback loop, the intermediate two loops switch between different solution modes at symbolic respectively sub-symbolic level, and the innermost loop performs the acquired competences in terms of perception-action cycles. We present a system diagram which explains this process in more detail. We discuss the learning strategy in terms of learning scenarios provided by the user. This interaction between user ('teacher') and system is a major difference to most existing systems where the system designer places his world model into the system. We believe that this is the key to extendable robust system behavior and successful interaction of humans and artificial cognitive systems. We furthermore address the issue of bootstrapping the system, and, in particular, the visual recognition module. We give some more in-depth details about our recognition method and how feedback from higher levels is implemented. The described system is however work in progress and no final results are available yet. The available preliminary results that we have achieved so far, clearly point towards a successful proof of the architecture concept.
|
|
| 3. |
|
|
| 4. |
- Östberg, Tomas, et al.
(författare)
-
Enhanced biodegradation of diesel fuel hydrocarbons in soil by the addition of fermented whey
- 2005
-
Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Industrial organic byproducts such as whey or fermented whey contain easily accessible carbon and micronutrients which could be used to stimulate microbial degradation of hazardous organic contaminants in soil. In this work we have investigated the possibility to use fermented whey as a growth supplement to enhance the aerobic degradation of diesel fuel hydrocarbons in soil. Experiments were carried out with two soils, a sand soil and a loamy sand soil, contaminated with diesel fuel at a concentration of 5000 mg kg-1 soil dry weight (dw). Fermented whey was added at different dosages to nutrient amended soil microcosms. Petroleum hydrocarbon mineralization was monitored by analysis of evolved 14CO2 from added 14C-labeled n-hexadecane. Mineralization curves were fitted to a three-half-order kinetics model. Enhanced mineralization was observed in sand soil at 7 and 22C and in loamy sand soil at 22C but the stimulatory effect was most pronounced in the sand soil at 22C, where the addition of 6 and 60 ml fermented whey kg-1 soil dw, increased the final degree of n-hexadecane mineralization from 49% in the control soil to 60 and 67% respectively. The increased total mineralization was characterized by an increase in the amount of substrate mineralized by first-order kinetics despite a decrease in the first order rate constant, k1. The highest concentration of fermented whey, 60 ml kg-1, gave rise to substrate competition, diauxie, which resulted in an extended lag phase.
|
|
