Modeling of countermeasures for large-scale disasters using High-level Petri Nets

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Presentation of Stella Moehrle on the topic "Modeling of countermeasures for large-scale disasters using High-level Petri Nets" at ISCRAM2013

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Modeling of countermeasures for large-scale disasters using High-level Petri Nets

  1. 1. KIT – University of the State of Baden-Württemberg and National Laboratory of the Helmholtz Association Helmholtz Centre Potsdam GFZ German Research Centre for Geosciences CENTER FOR DISASTER MANAGEMENT AND RISK REDUCTION TECHNOLOGY Modeling of countermeasures for large-scale disasters using High-level Petri Nets ISCRAM 2013
  2. 2. 2 www.cedim.de Research context Modeling requirements Petri Nets Modeling of countermeasures Application of the model Possible modeling extensions Summary & future prospects Outline Stella Moehrle, Institute for Nuclear and Energy Technologies, KIT ISCRAM 2013
  3. 3. 3 www.cedim.de Context of research I How can disaster management be supported by IT to handle events for which no underlying models exist to anticipate all possible event developments and therefore no pre-defined management strategies are prepared? Objectives Use knowledge of previous disasters. Address different kinds of disasters. Recommend countermeasures in a coherent manner. Account for uncertain incoming information. Stella Moehrle, Institute for Nuclear and Energy Technologies, KIT ISCRAM 2013
  4. 4. 4 www.cedim.de Context of research II Case-based reasoning Stella Moehrle, Institute for Nuclear and Energy Technologies, KIT ISCRAM 2013 Retrieve Similar Cases Reuse Revise Confirmed solution Learned case New Case Retain Generic case base Event description Sequence of countermeasures Petri Nets Merging Petri Nets The CBR cycle illustrated is based on Aamodt, A. and Plaza, E. (1994) Case-Based Reasoning: Foundational Issues, Methodological Variations, and System Approaches, AI Communications 7,1, 39-59.
  5. 5. 5 www.cedim.de Consideration of the sequence of countermeasures implemented Applicability to different kinds of events Description of model components in a general manner Representation in a graphical manner Integration of factors influencing the decisions on countermeasures Easy extensibility Modeling requirements Stella Moehrle, Institute for Nuclear and Energy Technologies, KIT ISCRAM 2013
  6. 6. 6 www.cedim.de A Petri Net is a triple N=(P,T,F) where P and T are non-empty finite sets of places and transitions P ∩ T = ∅ F⊆ (P  T) ∪ (T  P) is a binary relation over P ∪ T. Petri Nets I Stella Moehrle, Institute for Nuclear and Energy Technologies, KIT ISCRAM 2013
  7. 7. 7 www.cedim.de Can be used for modeling and analysis, simulation and good graphical representation Allow for modeling of sequential, parallel, alternative, and iterative actions Applied successfully in various fields such as emergency and disaster management and accident modeling Petri Nets II Advantages Stella Moehrle, Institute for Nuclear and Energy Technologies, KIT ISCRAM 2013
  8. 8. 8 www.cedim.de Different types of nets: Low- and High-level Nets Low-level Nets: tokens are indistinguishable High-level Nets: tokens are distinguishable, each place, transition and arc is defined with respect to different token types Modeling countermeasures, sub-events, influencing factors, endangered objects... leads to increasing complexity High-level Petri Nets allow for a more compact description Petri Nets III Stella Moehrle, Institute for Nuclear and Energy Technologies, KIT ISCRAM 2013
  9. 9. 9 www.cedim.de Modeling of countermeasures Characteristics Stella Moehrle, Institute for Nuclear and Energy Technologies, KIT ISCRAM 2013 Decisions on countermeasures depend on (sub-)events and the resulting endangered objects Two types of transitions, (sub-)events and countermeasures Events create engangerment and endangered objects Countermeasures reduce endangerment Tokens contain information about the endangered object and the degree of endangerment Predefined range of transition labels and endangered objects
  10. 10. 10 www.cedim.de Modeling of countermeasures Example Stella Moehrle, Institute for Nuclear and Energy Technologies, KIT ISCRAM 2013 x=chemical park y=1 x=chemical park y=0.7 overflow of dike dike protection flooding A×[0,1] a1 p0 p3 p1 p2 x=city y=1 evacuationa1|y=1, a2|y=1 a1≠ a2 a2 A×[0,1]a1|y=0.7 a1 A = {chemical park, city} a1, a2 = (x,y): A × [0,1] M0(p0) = M0(p1) = M0(p2) = M0(p3) = ∅ Endangered object and degree of endangerment
  11. 11. 11 www.cedim.de Approach is used to model solutions of cases in the CBR system. How to reuse the nets? Idea: merge nets Aim: identify new sequences of countermeasures without losing orginal firing sequences Possible: influencing factors on the decision are known Merging of two nets is based on a common event generating the endangerment and at least one common countermeasure Additional runs after merging depend on endangerment generated and the effect of the countermeasures on the endangerment Application of the model Stella Moehrle, Institute for Nuclear and Energy Technologies, KIT ISCRAM 2013
  12. 12. 12 www.cedim.de Scenario: nuclear reactor accident in summer with an atmospheric release of 137Cs and a wet deposition due to rain. The release is over and the contaminated plume has passed. The population has not been evacuated. The area surrounding the incident has been contaminated. Three cases are retrieved. Characteristics of solutions differ: Scenario 1: Soil/grass areas are surfaces that contribute most to external dose. In particular, the focus is on playgrounds. Scenario 2: The focus is on a strategy to decontaminate city gardens. Scenario 3: The area contaminated are mostly inhabited by elderly who refuse to leave the area. There is need to protect the people and clean the area (in particular city gardens). Application of the model Example I Stella Moehrle, Institute for Nuclear and Energy Technologies, KIT ISCRAM 2013
  13. 13. 13 www.cedim.deStella Moehrle, Institute for Nuclear and Energy Technologies, KIT ISCRAM 2013 x=sensitive area y=1A×[0,1] a1 start p1 x= people y=1 relocationa2 end A = {sensitive area, people} a1, a2 = (x,y): A × [0,1] M0(p0) = M0(p1) = M0(p2) = M0(p3) = ∅ x= city garden y=1 topsoil removal rotovating A×[0,1] a1 p1‘ A = {city garden, people} a1, a2 = (x,y): A × [0,1] M0(p0) = M0(p1) = M0(p2) = M0(p3) = ∅ a1|y=1, a2|y=1 a1≠ a2 endstart x= people y=1 a2a1|y=1, a2|y=1 a1≠ a2 relocation Application of the model Example II Scenario 1 Scenario 2 atmospheric release atmospheric release
  14. 14. 14 www.cedim.de x= city garden y=1 A×[0,1] a2 P1‘‘ x= people y=1 relocation a1 endstart rotovating A = {city garden, people, sensitive area} a1, a2 ,a3 = (x,y): A × [0,1] M0(p0) = M0(p1) = M0(p2) = M0(p3) = ∅ a1|y=1, a2|y=1 ∨ a1|y=1, a3|y=1 a1 = people, a2 ≠ a3 x= sensitive area y=1 topsoil removal x= city garden y=1A×[0,1] a1 P1‘‘‘ x=elderly y=1 shelteringa2 a1|y=1, a2|y=1 a1≠ a2 end start A = {city garden, elderly} a1, a2 = (x,y): A × [0,1] M0(p0) = M0(p1) = M0(p2) = M0(p3) = ∅ rotovating Stella Moehrle, Institute for Nuclear and Energy Technologies, KIT ISCRAM 2013 a3 Application of the model Example III Scenario 1 + 2 Scenario 3 atmospheric release atmospheric release
  15. 15. 15 www.cedim.deStella Moehrle, Institute for Nuclear and Energy Technologies, KIT ISCRAM 2013 x= city garden y=1 A×[0,1] a2 P1* x= people y=1 relocation a1 endstart rotovating A = {city garden, people, sensitive area, elderly} a1, a2 ,a3, a4= (x,y): A × [0,1] M0(p0) = M0(p1) = M0(p2) = M0(p3) = ∅ a1|y=1, a2|y=1 ∨ a1|y=1, a3|y=1 ∨ a3|y=1, a4|y=1 a1 = people a2 = sensitive area a3 = city garden a4 = elderly x= sensitive area y=1 topsoil removal x= elderly y=1 sheltering a3 a4 Application of the model Example IV Scenario 1+2+3 atmospheric release city garden, people, sensitive area Net has to be adapted to the current situation by comparing possible endangered objects.
  16. 16. 16 www.cedim.deStella Moehrle, Institute for Nuclear and Energy Technologies, KIT ISCRAM 2013 x= city garden y=1 A×[0,1] a2 P1* x= people y=1 relocation a1 endstart rotovating A = {city garden,people, sensitive area , elderly} a1, a2 ,a3, a4= (x,y): A × [0,1] M0(p0) = M0(p1) = M0(p2) = M0(p3) = ∅ a1|y=1, a2|y=1 ∨ a1|y=1, a3|y=1 ∨ a3|y=1, a4|y=1 a1 = people a2 = sensitive area a3 = city garden a4 = elderly x= sensitive area y=1 topsoil removal x= elderly y=1 sheltering a3 a4 Possible modeling extensions atmospheric release Additional types Additional characteristics Refinement of degree of endangerment Time and probabilities Allow countermeasure transitions to cause endangerment Modeling of 'forbidden‘ transitions
  17. 17. 17 www.cedim.de Case-based recommendation of sequences of countermeasures by reusing the most similar cases and their solutions from the past Sequences are modeled by High-level Petri Nets Factors influencing the decisions are integrated Generic and can be extended Reuse past solutions by merging the nets Preserve orginal sequences of countermeasures Propose new combinations of countermeasures Future work: analyze feasability of countermeasures, the composition of basic patterns, different abstractation levels and characteristics after merging, evaluation of strategies Summary & future prospects Stella Moehrle, Institute for Nuclear and Energy Technologies, KIT ISCRAM 2013
  18. 18. 18 www.cedim.de Thank you for your kind attention! Stella Moehrle, Institute for Nuclear and Energy Technologies, KIT ISCRAM 2013

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