SIMULATION: Transactions of The Society for Modeling and Simulation International

Mukherjee, Amalendu; Rastogi, Vikas; Dasgupta, Anirvan

doi: 10.1177/0037549707084668pmid: N/A

This paper presents a dynamic analysis of an electro-mechanical system through the umbra-Lagrange's equation proposed in a previous paper, which includes dissipative and non-potential fields in a compact Lagrangian form. An eXtended Noether's theorem along with an umbra-Hamiltonian is employed to get invariants of motion, or possible invariant trajectories. The umbra-Lagrangian of this electro-mechanical system is obtained through an eXtended Karnopp's algorithm. The major contribution of this paper is the dynamic analysis eXploiting the symmetries of an electromechanical system comprising an eXternally and internally damped, symmetric, elastic rotor driven by a two-phase induction motor. For such a system the umbra-Lagrangian remains unchanged under two families of continuous transformations. The behavior of the limiting dynamics is obtained and validated through simulations. The stability issue of this system is also eXamined. Similar analysis is also eXtended to an identical rotor driven by a three-phase induction motor. As SO (2) symmetries are not obvious in this case due to the presence of three stator inertances, the three-phase induction motor is reduced to an equivalent SO (2) symmetric two-phase induction motor, to which the analysis is applied.

Balci, Deniz; Kesen, Saadettin Erhan; Baykoç, Ömer Faruk

doi: 10.1177/0037549070852953pmid: N/A

Although a great deal of successful research has been carried out in just-in-time (JIT) philosophy, few researchers have focused on the adaptation of JIT philosophy in service systems. Despite the recent improvements in the service systems, few studies have been carried out which eXamine the effects of the JIT philosophy on service systems which have a different structure to production systems. As a result of the benefits obtained from successful application of the JIT philosophy in the production systems, we have adapted the JIT philosophy for the service systems and eXamined the obtainable benefits. For this purpose, observation and time-scaling studies were made in an Adult Emergency Service in Turkey. Within the framework of the data acquired in this study, the eXisting system was modeled. By analyzing the simulation results, an alternative system has been proposed which can be applied to the system. Results show that the proposed system under the principle of JIT philosophy outperforms the eXisting system.

Newport, Calvin; Kotz, David; Yougu Yuan, ; Gray, Robert S.; Jason Liu, ; Elliott, Chip

doi: 10.1177/0037549707085632pmid: N/A

All analytical and simulation research on ad hoc wireless networks must necessarily model radio propagation using simplifying assumptions. A growing body of research, however, indicates that the behavior of the protocol stack may depend significantly on these underlying assumptions. The standard response to this problem is a call for more realism in designing radio models. But how much realism is enough? This study is the first to approach this question by validating simulator performance (both at the physical and application layers) with the results of real-world data. Referencing an eXtensive set of measurements from a large outdoor routing eXperiment, we start by evaluating the relative realism of common assumptions made in radio model design, identifying those which provide a reasonable approXimation of reality. Although several such investigations have been made for static sensor networks, radio behavior in mobile network deployments is a much less-studied topic. We then reproduce our eXperimental setup in our simulator, and generate the same application-layer metrics under progressively smaller sets of these assumptions. By comparing the simulated outcome to the outcome of our eXperiment, we are able to discern at what point our balance of simplification and realism captures the real behavior of our target environment.

Khoury, Hiam M.; Kamat, Vineet R.; Ioannou, Photios G.

doi: 10.1177/0037549707086038pmid: N/A

This paper illustrates how simulation modeling and visualization can be of substantial help in studying airside airport operations, and can greatly contribute in planning and designing construction operations at airports in a way that has the least impact on airside operations. The characteristic that distinguishes the current work is the capability to model and animate airside airport operations with high fidelity using general purpose discrete event simulation and visualization tools typically used to model and animate construction operations. The focus of the presented work is on evaluating the capabilities of state-of-the-art construction simulation and visualization tools in being able to accurately model and animate airside airport operations. The paper presents the simulation model and 3D animation of the airside operations at Detroit Metropolitan Wayne County Airport (DTW) in Romulus, Michigan. It also presents simultaneous modeling and visualization of operations in two different domains (i.e. airside operations and construction). The solution to the problem is described in detail using a simulation model developed in STROBOSCOPE and a 3D animation created using VITASCOPE. The obtained results highlight and prove that general-purpose tools, even if originally designed for specific domains, can be effective in studying operations involving the interaction of entities in multiple domains such as construction and airport operations.