Research On Dynamic Reconfiguration Technologies Of Distributed Simulation System

With increasing application domain and scale of distributed simulation technology, new challenges emerge in simulation interoperability and adaptability. Dynamic reconfiguration is a kind of technique which can support adapting simulation executive online. It is valuable to improve simulation flexibility and promote simulation application level in critical occasions. The research in this direction has been a frontier issue in current modeling and simulation region. In this research effort, we study this problem from four aspects: basic concept, system architecture, modeling method and realization mechanism.From the viewpoint of modeling and simulation methodology, internal nature of simulation reconfiguration is illustrated with the concepts of dynamic system level specification and entity space. In the illustration, the importance of model semantic for simulation reconfiguration research is clear. To provide general approach of simulation dynamic reconfiguration, Discrete Event System Specification (DEVS) is selected as the model specification for system description and a reconfigurable modeling and simulation framework for DEVS components is proposed. Within this framework, reflective dynamic structure model and control mechanisms constitue the critical technologies needed to be developed for simulation reconfiguration.Based on the fundamental semantic description theory of timed relative system, we propose a formal timed trajectory semantic definition for DEVS model and a method to describe it with Timed Transition System (TTS). Furthermore, to improve the semantic descriptive level of DEVS models, an equivalent semantic transformation from DEVS to Timed Automata (TA) is proposed. Then, semantic property of a DEVS model can be validated by applying temporal logic checking to its semantic equivalent TA model.Dynamic structure model is the basis for performing simulation reconfiguration activity. By extending parallel DEVS specification, we build a distributed-centralized reflective dynamic structure model called PVDSDE. This model preservs state transition structure and protocol of traditional parallel DEVS model, and also adds structure transition elements and protocols in both atomic and coupled model levels. Moreover, the model has the character of closure under coupling and can satisfy the requirements of composable simulation.The simulation realization mechanism of PVDSDE is studied in this dissertation. After comparing and analyzing several realization modes for running PVDSDE on distributed simulation platforms, we propose a flat structural framework and scheduling mechanism for executing PVDSDE models in High Level Architecture (HLA) simulation environment. For the time management issue in PVDSDE/HLA, we introduce a mapping time advancing algorithm, the effectiveness of which is validated through real experiments.As for simulation execution modes, distributed simulation cloning technique is studied, which can support performing concurrent multiple simulation scenarios in one same execution. We implement the concurrent reconfiguration of multiple scenarios simultaneously through combing simulation cloning with dynamic structural models. It improves the efficiency of simulation execution and also provides an effective running mode for implementing online-decision. The architectures and scenario partition algorithms of HLA simulation cloning are dicussed thoroughly in this research. Applicabilities of different scenario partition algorithms for different architectures are also tested and analyzed. Moreover, an articulated simulation cloning middleware and a loosely coupled federate architecture are proposed for cloning realization. Through real experiments, it is found that distributed simulation cloning technique can improve simulation executive performance evidently.Based on critical technologies studied above, we developed a prototype of reconfigurable simulation system development with the Modeling Integrated Computing (MIC) method. The prototype supports model driven development and encapsulates some general modules, such as scheduler, adapter, cloning middleware etc. In the end, the feasibility of this research effort is validated through a concrete application of the prototype in XX countermeasure simulation.