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Y. Sheng et al.
indicate individual’s attributes or relationships between individuals. As a kind
of knowledge representation method, description logic can not only represent the
knowledge in the domain but also have the mechanism of reasoning, which can
derive the implicit knowledge. The reasoning in the description logic is divided
into two types: conceptual reasoning and instance detection. Conceptual reasoning includes determining the consistency (satisfaction) of concepts, inclusion
relationships, equivalence relations, and disjointness; instance detection refers to
determining whether a given instance belongs to a concept.
Released by Stanford University, Protege software is a software for creating
ontologies based on Java. It is also a knowledge-based editor. It is an opensource software. This software is mainly used for the construction of ontology in
the Semantic Web. Protege provides the construction of concepts, relationships,
attributes, and instances, and users do not need to focus on the concrete ontology
description language. Users can construct the domain ontology model at the
conceptual level. The Protege tool supports some different reasoners and allows
users to choose one from several options. These reasoners can perform reasoning
based on description logic. Reasoners are the engine to run the queries based
on logical rules. These reasoners can not only execute reasoning rules but also
examine semantic consistency. They can also answer logical questions according
to concepts and their relationships defined in existing ontologies.
6 Case Study
We demonstrate the process of the proposed approach by a case study in this
section. Suppose there is a flight from Shanghai to Beijing, as depicted in Fig. 5.
A 4DTrajectory has a RoutePoint and the time that the flight passes it. A
Thunderstorm has a group of Forcast results, and each result consists of the
affected area and time. We can add the relations between affected areas and
route points by analyzing the geographic position.
Then, Semantic Web Rule Language (SWRL) is used to define reasoning
rules. Overlaps, Overlapped By, Starts, Started By, During, Contains, Finishes,
Finished By, and Equals are defined as sub-properties of TemporalConflict. While
PO, EQ, TPP, TPPi, NTPP, and NTPPi are sub-properties of SpatialConflict.
We define the following reasoning rules to support decision-making in ATM:
F ourDT rajectory(?tr1) ∧ hasF lightRouteElement(?tr1, ?re1)∧
hasT rajectoryP oint(?re1, ?pd1) ∧ hasT ime(?pd1, ?t1) ∧ hasRouteP oint(?pd1, ?r)
∧ T hunderStorm(?th2) ∧ hasF orcast(?th2, ?fc2) ∧ hasT ime(?th2, ?t2)
∧ hasAf f ectedArea(?th2, ?aa) ∧ T emporalConf lict(?t1, ?t2)
∧ SpatialConf lict(?aa, ?r) → conf lictW ith(?tr1, ?th2).
Then, we run the reasoner and the results are depicted in Fig. 6.
Based on the proposed ontological model, we can also define reasoning rules
to detect the conflicts between two trajectories. That is, if the origin trajectory
is infeasible, we generate a new one. With these reasoning rules, we can tell if
the new trajectory conflicts with a thunderstorm or other trajectories.
Y. Sheng et al.
indicate individual’s attributes or relationships between individuals. As a kind
of knowledge representation method, description logic can not only represent the
knowledge in the domain but also have the mechanism of reasoning, which can
derive the implicit knowledge. The reasoning in the description logic is divided
into two types: conceptual reasoning and instance detection. Conceptual reasoning includes determining the consistency (satisfaction) of concepts, inclusion
relationships, equivalence relations, and disjointness; instance detection refers to
determining whether a given instance belongs to a concept.
Released by Stanford University, Protege software is a software for creating
ontologies based on Java. It is also a knowledge-based editor. It is an opensource software. This software is mainly used for the construction of ontology in
the Semantic Web. Protege provides the construction of concepts, relationships,
attributes, and instances, and users do not need to focus on the concrete ontology
description language. Users can construct the domain ontology model at the
conceptual level. The Protege tool supports some different reasoners and allows
users to choose one from several options. These reasoners can perform reasoning
based on description logic. Reasoners are the engine to run the queries based
on logical rules. These reasoners can not only execute reasoning rules but also
examine semantic consistency. They can also answer logical questions according
to concepts and their relationships defined in existing ontologies.
6 Case Study
We demonstrate the process of the proposed approach by a case study in this
section. Suppose there is a flight from Shanghai to Beijing, as depicted in Fig. 5.
A 4DTrajectory has a RoutePoint and the time that the flight passes it. A
Thunderstorm has a group of Forcast results, and each result consists of the
affected area and time. We can add the relations between affected areas and
route points by analyzing the geographic position.
Then, Semantic Web Rule Language (SWRL) is used to define reasoning
rules. Overlaps, Overlapped By, Starts, Started By, During, Contains, Finishes,
Finished By, and Equals are defined as sub-properties of TemporalConflict. While
PO, EQ, TPP, TPPi, NTPP, and NTPPi are sub-properties of SpatialConflict.
We define the following reasoning rules to support decision-making in ATM:
F ourDT rajectory(?tr1) ∧ hasF lightRouteElement(?tr1, ?re1)∧
hasT rajectoryP oint(?re1, ?pd1) ∧ hasT ime(?pd1, ?t1) ∧ hasRouteP oint(?pd1, ?r)
∧ T hunderStorm(?th2) ∧ hasF orcast(?th2, ?fc2) ∧ hasT ime(?th2, ?t2)
∧ hasAf f ectedArea(?th2, ?aa) ∧ T emporalConf lict(?t1, ?t2)
∧ SpatialConf lict(?aa, ?r) → conf lictW ith(?tr1, ?th2).
Then, we run the reasoner and the results are depicted in Fig. 6.
Based on the proposed ontological model, we can also define reasoning rules
to detect the conflicts between two trajectories. That is, if the origin trajectory
is infeasible, we generate a new one. With these reasoning rules, we can tell if
the new trajectory conflicts with a thunderstorm or other trajectories.