SIMULATION: Transactions of The Society for Modeling and Simulation International

Yilmaz, Levent

doi: 10.1177/0037549708099239pmid: N/A

Cuzán, Alfred G.; Bundrick, Charles M.; Heggen, Richard J.

doi: 10.1177/0037549708099938pmid: N/A

In this paper a simulation technique borrowed from civil engineering is applied to American presidential elections to explore the key relationship between federal spending and incumbent reelection, represented by the fiscal model. On the one hand, as Machiavelli would have understood, an expansionary fiscal policy militates against incumbent reelection but a cutback policy facilitates it. That is the `demand' side of the model. There is also a `supply' side: the longer the incumbents have occupied the White House, the more likely they are to implement fiscal expansion. We simulated 1,000 elections under conditions that replicated the values of the predictor variables of the fiscal model over the 1880—2004 and 1932—2004 periods of American history. The latter period deserves attention in its own right, because starting with the 1932 election, the federal share of gross domestic product broke out of the 2—3% range for the first time since World War One. This marked a qualitative change in the role of government in the United States of America. The simulated series allow patterns that are weakly detected in the historical data to emerge more clearly for observation and analysis. The results of the simulations not only confirm the empirical findings from the historical data, but suggest that the American political system is stable, maintaining alternation between political parties in the White House, a characteristic of democracies, and keeping fiscal policy within bounds of what the majority of the voters will support.

Cicirelli, Franco; Furfaro, Angelo; Nigro, Libero

doi: 10.1177/0037549708100187pmid: N/A

This paper proposes an agent infrastructure (Theatre) centered on Java for distributed simulations over High-Level Architecture/RunTime Infrastructure (HLA/RTI). The architecture rests on actors (agents) as the basic building blocks. Actors have a public message interface and encapsulate a state of local variables and a behavior patterned as a finite state machine. Actors interact with one another by asynchronous message passing. At the system level, theatres are used as the execution platforms for actors. Theatres naturally map on to HLA federates. Actors can migrate between theatres for load-balancing concerns, or in response to (re)configuration operations of dynamic structure systems. The paper introduces Theatre and demonstrates its application to a complex simulation model based on unmanned aerial vehicles (UAVs). The case study is an open agent-based distributed model where mobile agents follow communication patterns established at runtime.

Hur, Pilwon; Yang, Jeongsam; Han, Soonhung; Yoo, Byounghyun

doi: 10.1177/0037549708101180pmid: N/A

Training war fighters how to maneuver a submarine is very important, but the use of real submarines in such training is expensive and hindered by regional and temporal limitations. Modeling and simulation (M&S) can be a good alternative to costly training. However, the use of existing M&S for submarines has limitations. For instance, the commercial software and hardware need to be kept in a secure place. Depending on the location of the protected software, war fighters may travel far and take a considerable amount of time to get to these places. Long-distance travel also means they have a limited amount of time to train on the M&S machines. Furthermore, many types of M&S have only a one-channel display system, which reduces immersiveness. Another problem is that few heterogeneous simulators can be used as an integrated system. One solution to these problems involves the use of extensible 3D (X3D) graphics, a platform-independent and open standard graphic file format, which can be used with general purpose PCs. The immersiveness is increased by means of a multichannel display system and a motion chair. Finally, the individual components of a simulator can be integrated with the high level architecture and run time infrastructure (HLA/RTI). We demonstrate the proposed method through experiments with an underwater vehicle simulator.

Golestaneh, Amirreza F.; Ali, Aidy; Voon Wong, S.; Mustapha, Faizal; Zadeh, M.

doi: 10.1177/0037549708099886pmid: N/A

The aim of the present work is to predict the fatigue life of a friction stir welded (FSW) joint in the 2024-T351 aluminum alloy using the finite element method in the framework of Fracture Analysis Code for Two Dimensions (FRANC2D/L). The simulation is conducted using linear elastic fracture mechanics based on Paris' model, and the maximum tensile stress and displacement correlation methods are applied to calculate the crack direction and stress intensity factor, respectively. Several strategies are applied in order to predict the crack propagations through various welded zones regarding the corresponding parameters and Paris constants for each zone. The entire crack growth process is investigated step by step through all of the FSW zones, and the fatigue lifetimes of the FSW joint under various loading conditions are predicted by implementing the same procedure. The numerical results are validated with experimental and analytical work.