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- Boström, Henrik, et al.
(författare)
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On the Definition of Information Fusion as a Field of Research
- 2007
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- A more precise definition of the field of information fusion can be of benefit to researchers within the field, who may use uch a definition when motivating their own work and evaluating the contribution of others. Moreover, it can enable researchers and practitioners outside the field to more easily relate their own work to the field and more easily understand the scope of the techniques and methods developed in the field. Previous definitions of information fusion are reviewed from that perspective, including definitions of data and sensor fusion, and their appropriateness as definitions for the entire research field are discussed. Based on strengths and weaknesses of existing definitions, a novel definition is proposed, which is argued to effectively fulfill the requirements that can be put on a definition of information fusion as a field of research.
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- Brohede, Marcus, et al.
(författare)
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A Distributed Whiteboard Infrastructure for Information Fusion Simulations
- 2009
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Ingår i: Proceedings of the 32nd Annual IEEE Software Engineering Workshop (SEW-32). - : IEEE. - 9780769536170 ; , s. 134-142
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Konferensbidrag (refereegranskat)abstract
- We argue that architecural ideas from DeeDS, a distributed real-time database, can be used to create a whiteboard infrastructure usable in information fusion applications as well as in fault tolerant simulations. We discuss the need for faulttolerant real-time simulation in information fusion, and how this can be supported by the whiteboard infrastructure. There are many reasons to perform real-time simulations (including environment simulation) - the use of real hardware or systems can be prohibitively expensive or dangerous to people and equipment, or may simply not be available at all. The combination of real and simulated objects, or nodes, is of particular interest when it is prohibitively expensive, dangerous, or impossible to test sufficient numbers of collaborating nodes in a realistic application. The need for fault tolerance of such real-time simulations, with a mixture of real and simulated nodes, occurs because it is difficult/impossible to restart physical nodes or wait for restart of simulated nodes, if one or more simulation instances fail. The key problem when mixing real and simulated nodes is the occurrence of "external actions" that cannot easily be undone and redone when a failure has occurred. We describe a natural approach to support multiple degrees of fault tolerance in realtime simulations, based on optimistic synchronization on top of a whiteboard architecture. The whiteboard architecture is a natural and useful infrastructure metaphor for information fusion, an information-based exchange that allows real and simulated nodes to be freely mixed.
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- Brohede, Marcus
(författare)
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Bounded recovery in distributed discrete real-time simulations
- 2006
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Rapport (populärvet., debatt m.m.)abstract
- This thesis proposal defines the problem of recovery in distributed discrete real-time simulations with external actions; real-time simulations with simulation actions in the real world. A problem that these simulations encounter is that they cannot rely on rollback-based recovery (use of checkpoints) for two reasons. First, some actions in the "real world" cannot be undone, and second, the time allowed for recovery tends to be short and bounded. As a result there is a need for some form of error masking for this category of simulations. We propose an infrastructure for these simulations with external actions based on an active distributed real-time database that features replication of the distributed simulation. The degree of replication is based on the dependability requirements of the individual nodes in the simulation.A guideline for how to decompose a distributed real-time simulation into parts with different requirements on the replication protocol is also defined as an interesting topic to investigate further. We introduce the simulation infrastructure "Simulation DeeDS" featuring a replication-based recovery strategy for the category of simulations mentioned. We also show that some information fusion applications are indeed examples of applications that need real-time simulation with external actions and as such can benefit from the proposed infrastructure.
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- Brohede, Marcus, et al.
(författare)
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Optimistic database-driven distributed real-time simulation (05F-SIW-031)
- 2005
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Ingår i: Fall 2005 Simulation Interoperability Workshop. - : Curran Associates, Inc.. - 9781622761401 ; , s. 223-228
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Konferensbidrag (refereegranskat)abstract
- In this paper we present an optimistic synchronization protocol for distributed real-time simulations that uses a database as communication and storage mechanism. Each node in the simulation is also a database node and communication in the simulation is done by storing and reading to the database. The underlying replication protocol in the database then makes sure that all updates are propagated. The progress in the simulation is optimistic, i.e., each node tries to simulate as far ahead as possible without waiting for input from any other node. Since the simulations are said to be real-time we must guarantee that no events can be delivered too early nor too late. Also, recovery of a node must be done within predictable time due to the real-time constraints. Since all updates in the simulation are done through transactions we have a well-defined foundation for recovery and we show how the recovery can be done deterministically. For the simulation to function (and keep deadlines) during network partitions we allow local commits in the database. This requires that all data required on a specific node must be reachable from that node, i.e., no remote accesses should be needed. However, allowing local commits may introduce conflicting updates. These conflicts are detected and solved predictably
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- Brohede, Marcus, et al.
(författare)
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Using Distributed Active Real-Time Database Functionality in Information-Fusion Infrastructures
- 2005
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Ingår i: RTiS 2005. - Skövde : Skövde University. - 9163173492 ; , s. 5-10
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- We present a list of requirements that need to beaddressed by an infrastructure for information fusion whereapplications have real-time requirements. The requirements aregrouped into configuration requirements, temporal requirements,and robustness requirements. We show how the functionality ofa distributed active real-time database system (DARTDBS) canmeet many of the given requirements, and therefore, argue thatit is suitable for use in an information-fusion infrastructure withreal-time requirements. The design of a particular DARTDBS,the DeeDS architecture and prototype, is presented as proofof concept. A comparison with some alternative infrastructuresis briefly discussed. We describe a small distributed real-timesimulation experiment using DeeDS as infrastructure, and discussopen questions such as how to deal with uncertainty managementof information sources, recovery of information fusion nodes, andharmonizing data structures from different information sources.
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