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- Gustavsson, Rune, et al.
(författare)
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Societies of Computation (SoC). A Framework for Open Distributed systems-phase II:1995-98
- 1995
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- The research program Societies of Computation (SoC) at the IDE department of HK/R has been in operation since more than one year [ 11, [2]. The SoC framework takes a Multi Agent System (MAS) approach when addressing issues in open distributed computing. The results so far are very promising and will shortly be outlined below. Assessment of those results combined by results and ideas from the international research society as well as needs from enterprises are background material for our next phase. The goals and expected results from this phase is briefly discussed in following sections. The research group, performing activities in the SoC framework, has been formed during the first phase of the project, and has at present the following active members: Rune Gustavsson, professor and principal investigator, Hans Akkermans, professor at Twente University and guest researcher, Eric Astor, Ph.D., University of Lund, Olle Lindeberg, Ph.L., HK/R, Staffan Hagg, Ph.L., HK/R, Fredrik Ygge, MSc., HK/R and Sydkraft, Barcin Kozbe, M.Sc., Ericsson Infocom Christer Lundberg, M.Sc, University College of Kalmar, Bengt Carlsson, M.Sc., University of Lund Occasionally also other researchers at IDE are involved in shorter R&D activities conducted under the SoC umbrella. Applications developed in SoC have also been sources for several projects performed by undergra-duate students, during the fiscal year of 1994-95 about 12 person years, from several undergraduate programs. Those activities of the SoC program have mainly been performed within the center SIKT. SIKT, Society Information and Knowledge Technologies, is a recently formed center at HK/R. The key industrial partner up to this point has been Sydkraft AB. The project Intelligent Distribution Automation (IDA) at Sydkraft has been a valuable partner for developing applications and assessing results. Ronneby Energi AB (REAB) and Affarsverken i Karlskrona AB are also actively supporting our R&D. The project Communication and Distributed Computing for Efficient Management of Energy Systems, supported by governmental agencies, has been instrumental for introducing and assessing MAS technologies in the Swedish research society as well as to Swedish industry.
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| 2. |
- Hägg, Staffan
(författare)
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A Sentinel Approach to Fault Handling in Multi-Agent Systems
- 1996
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Rapport (refereegranskat)abstract
- Fault handling in Multi-Agent Systems (MAS) is not much addressed in current research. Normally, it is considered difficult to address in detail and often well covered by traditional methods, relying on the underlying communication and operating system. In this paper it is shown that this is not necessarily true, at least not with the assumptions on applications we have made. These assumptions are a massive distribution of computing components, a heterogeneous underlying infrastructure (in terms of hardware, software and communication methods), an emerging configuration, possibly different parties in control of sub-systems, and real-time demands in parts of the system. The key problem is that while a MAS is modular and therefore should be a good platform for building fault tolerant systems, it is also non-deterministic, making it difficult to guarantee a specific behaviour, especially in fault situations. Our proposal is to introduce sentinels to guard certain functionality and to protect from undesired states. The sentinels form a control structure to the MAS, and through the semantic addressing scheme they can monitor communication, build models of other agents, and intervene according to given guidelines. As sentinels are agents themselves, they interact with other agents through agent communication. The sentinel approach allows system developers to first implement the functionality (by programming the agents) and then add on a control system (the sentinels). The control system can be modified on the fly with no or minimal disturbance to the rest of the system. The present work is conducted in cooperation with Sydkraft, a major Swedish power distribution company. Examples are taken from that venture, and it is shown how problems can be solved by programming DA-SoC agents, developed here.
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| 3. |
- Hägg, Staffan
(författare)
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A Sentinel Approach to Fault Handling in Multi-Agent Systems
- 1997
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Konferensbidrag (refereegranskat)abstract
- Fault handling in multi agent systems (MAS) is not much addressed in current research. Normally, it is considered difficult to address in detail and often well covered by traditional methods, relying on the underlying communication and operating system. It is shown that this is not necessarily true, at least not with the assumptions on applications we have made. These assumptions are: massive distribution of computing components; heterogeneous underlying infrastructure (in terms of hardware, software and communication methods); emerging configuration; possibly different parties in control of subsystems; and real time demands in parts of the system. The key problem is that while a MAS is modular, it is also non deterministic, making it difficult to guarantee a specific behaviour. Our proposal is to introduce sentinels to guard certain functionality and to protect from undesired states. The sentinels form a control structure to the MAS, and through the semantic addressing scheme they can monitor communication, build models of other agents, and intervene according to given guidelines. Sentinels interact with other agents through agent communication. The sentinel approach allows system developers to first implement the functionality (by programming the agents) and then add on a control system (the sentinels). The control system can be modified on the fly with no or minimal disturbance to the rest of the system. The work presented is conducted in cooperation with Sydkraft, a Swedish power distribution company. Examples are taken from that venture, and it is shown how problems can be solved by programming DA-SoC agents.
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| 4. |
- Hägg, Staffan
(författare)
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Adaptation in a Multi-Agent System Through Semantic Addressing
- 1995
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Rapport (refereegranskat)abstract
- In many application domains the design of complex systems must cope with rapid and unforeseeable change, requiring an elaborate integration of execution and communication methods. This is especially the case when real-time constraints are present. In this paper a Multi-Agent Systems approach to distributed computing is presented. It has a programmable model of agent interaction, and the interaction is tightly integrated with the mechanisms that control the individual agent behaviour. We introduce the concepts of tailored interaction and semantic addressing which support abstraction, flexibility and robustness in open and emergent distributed systems. We then show that it enables the system to adapt to a number of frequent types of change in the environment. The automation of power distribution is a domain where new services are introduced and new infrastructures are exploited. DA-SoC is an agent architecture developed for this domain, and it exemplifies the need for adaptability and the use of semantic addressing to accomplish this.
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| 5. |
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| 6. |
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| 7. |
- Hägg, Staffan
(författare)
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Agent Technology in Industrial Applications
- 1997
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Rapport (refereegranskat)abstract
- The agent metaphor has become increasingly popular in distributed computing systems. As often with a new paradigm, it is not very clear what the exact meaning is. The meaning and the development of the agent paradigm is therefore discussed in this paper. One motivation for using agents in distributed systems is that, due to the rapid technical development of computing and communication facilities, these systems become larger, more complex, and with more heterogeneous components. The change rate for such systems will also increase. Another, but related, motivation is that, in many cases, the systems are open and emergent in new respects: Different parties will be in control of parts of the total system, and the change of the system may not be altogether predictable. It is simply not possible to describe the total system from any one point of focus or at any one point in time, meaning that traditional methods for describing and implementing the systems are not sufficient. Industrial applications (e.g. manufacturing systems, process control systems, or resource management systems) show many of the characteristics mentioned above. Specifically, there is a demand for integrating quite dispersed applications, for example systems for process control, market analysis, and economic management. There is also a stronger demand for communication and interacting with sub-contractors, partners, and customers. This is emphasized with the development of a common communication medium like the Internet. In the ISES project, the agent paradigm is studied and developed for use in Power Distribution Auto-mation. Examples of this work are given here, and the applicability of agent technology is shown for applications that concern Distribution Automation, Demand Side Management, and Home Automa-tion. It is also argued for the applicability of agent technology in other types of industrial applica-tions, based on similarities between problem domains.
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| 8. |
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| 9. |
- Hägg, Staffan
(författare)
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Commitment in Agent Cooperation, Applied to Agent-Based Simulation
- 1999
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- We regard simulation as a set of interaction episodes between partaking agents in an agent-based simulation. In order to structure the interaction we use commitments, and the semantics of such commitments is an analogy to a two-phase commit scheme used in distributed databases. A commitment is a contract between the involved agents to reach and preserve a specified goal, during a specified time. Here we define the semantics, describe the messages and outline administrative issues. The full strength of the model is reached when an initiator needs to make commitments with a number of other agents. It then awaits the replies, and then, depending on the replies, it either confirms or rejects proposed commitments. Hereby it accomplishes an analogy to an atomic action when a two-phase commit scheme is used. When the commitment scheme is applied to a simulation, a crucial part of the design is to model the requirements for accepting commitments during simulation. We introduce the concepts of an acceptance function and acceptance domains that are used to express these requirements. An example from battle field simulation is given. With the proposed model simulated objects may quite easily be replaced by real objects. With the right kind of interface, real trucks and other entities may partake in real time operations, while other entities are simulated.
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| 10. |
- Hägg, Staffan
(författare)
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Commitment in agent cooperation, applied to agent-based simulation
- 1998
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Konferensbidrag (refereegranskat)abstract
- We regard simulation as a set of interaction episodes between partaking agents in an agent-based simulation. In order to structure the interaction we use commitments, acid the semantics of such commitments is an analogy to a two-phase commit scheme used in distributed databases. A commitment is a contract between the involved agents to reach and preserve a specified goal, during a specified time. Here we define the semantics, describe the messages and outline administrative issues. The full strength of the model is reached when an initiator needs to make commitments with a number of other agents. It then awaits the replies, and then, depending on the replies, it either confirms or rejects proposed commitments. Hereby it accomplishes an analogy to an atomic action when a two-phase commit scheme is used When the commitment scheme is applied to a simulation, a crucial part of the design is to model the requirements for accepting commitments during simulation. We introduce the concepts of an acceptance function and acceptance domains that are used to express these requirements. An example from battle field simulation is given. With the proposed model simulated objects may quite easily be replaced by real objects. With the right kind of interface, real trucks and other entities may partake in real time operations, while other entities are simulated.
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