This paper presents a new DEVS/NS-2 modeling and simulation environment which supports both high and low levels of abstraction for network m odeling and sim ulation. DEVS (Discrete Even t System Specification) is a welldefined m athematical f ormalism specif ication for structure and behavior of dynamic system s. The NS-2 is a discre te event network simulator, whose primary use is intended to build and run various detailed network m odels and protocols such as TCP/IP, satellite links, and wireless networks. By combining the two powerful modeling and simulation systems, the significant benefits attained by the interoperabl e sim ulation of DEVS and NS-2 are reduction of the cost, increased hi gh and low level m odeling power, and enhanced r eusability. To integ rate the sys tems seam lessly, two major challenges are add ressed. The firs t cha llenge is to synchronize the different ways of handling event schedules by th e two simulation system s. This paper illustrates h ow the s imulation tim e advances of DEVS and NS-2 are synchronized with each other. The latte r problem is related to assign ing the appropriate level of model structure and behavior within the combined system. The details of low level ne twork with protocol and com ponent description is m odeled by NS-2 while DEVS serves as controller by modeling the high level behavior (e.g. us e case scenario bu ilder) of target network m odels and interaction of the as sociated actors. In this paper, we take two exam ples of wireless sensor netw orks. The first exam ple is to describe our approach to the de velopment process for m odeling and simulation in DEVS/NS-2 environm ent, and the purpose of the second example is to show how DEVS/NS-2 environ ment is ef ficient f or m ilitary system applications. Th is exam ple is extended to dem onstrate an effective way to m ake a decision on the appropria te level of sensor node' s behavior. This leads to the disc ussion of trad eoffs between energ y efficiency and effectiveness of decision making for the sensor network. The advantages and at BALL STATE UNIV on November 19, 2014 dms.sagepub.com Downloaded from the disadvantages are d iscussed in the last part of this paper by com paring DEVS/NS-2 environm ent with its r elated studies such as DEVS BUS and OPNET.
To develop a simulator for automated manufacturing systems using an object-oriented modeling paradigm, we have researched the message-passing architecture and methodology of rapid model construction. For the message-passing methodology, we propose a modified hierarchical control architecture, modified to allow signal paths between adjacent job flow-connected resources. Model libraries using the proposed architecture have been described zwith DEVS formalism and have been implemented based on DEVSim++ so that they support the hierarchical and modular concept. In order to support the rapid modeling concept, we have designed a prototype simulator in which the entire message-passing architecture is constructed from limited and partial information in order to reduce modeling overload for users. By showing a sample modeling procedure of a system, we demonstrate the interesting features of the developed simulator.
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