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19th EMSS, 2007 |
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19th European Modeling and Simulation Symposium (Simulation in Industry) 4-6 October 2007 Bergeggi (Sv), Italy |
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Session CO-IV: Simulation visualization and control of complex system
MODELLING, SIMULATION AND CONTROL OF THE BELL 206L-4 HELICOPTER, Pedro Balaguer, Ramon Vilanova
The article presents the mathematical modelling, simulation and the attitude control system design for a Bell 206L-4 helicopter. The helicopter is a complex system as it is multivariable, non-linear and strongly coupled. These dynamical features must be captured by the model in order to design a properly performing controller. The nonlinear mathematical model is used first to derive a simpler linear model to be used for control design purposes and, secondly to check the resulting control system over the nonlinear model. One model feature is that the helicopter attitude is modelled by means of quaternions instead of classical rotation matrices. The use of quaternions prevents problems associated with rotation matrices (e.g. gimbal lock and lack of the commutativity property). The simulation structure is discussed and implemented in C/C++. Simulation results of the attitude control with a LQR regulator are presented.
AN EXPERIMENTAL ENVIRONMENT FOR THE RUNTIME COMMUNICATION AMONG DIFFERENT SOLVERS AND VISUALIZATION MODULES, Fabio Bruno, Francesco Caruso, Maurizio Muzzupappa, Andre Stork
During the development of complex industrial products, several physical and engineering domains are involved. Mechatronic products, for example, are the result of the synergy among mechanical engineering, electronics and computer science. Therefore, the development of such products requires a constant and continuous cooperation among the designers responsible of the different fields of knowledge. Further, to prevent possible design errors before the building of the physical mock-up, there is the need of a simulation environment able to perform analyses in several physical domains. A possible solution to this need is the employment of a software package able to compute multi-domain simulations. However, the existent solutions do not allow engineers to employ their own solver or to choose the best combination among the available simulation software. This paper describes the development of an experimental middleware that supports the communication among different synchronously running simulations, solving interrelated problems and integrating a graphical interactive environment to support the interdisciplinary team in the design review and decision taking.
INTEROPERABLE SIMULATION FOR TRAINING IN INTERMODAL LOGISTICS IN LAND TERMINAL, Davide Modula, Attilio Rocca
The research project named INNOVARE (Intermodal development of Activities in Novara and Vercelli for Human Resources – Equal) has the target to develop an interoperable simulation for teaching to logistic operators how to move industrial vehicles used in intermodal ports like contstaker, transtainers, cranes and trucks inside land terminals. The simulator is based on High Level Architecture (HLA) standards, following the protocols of DMSO/USA in order to combine more training simulators and more operators with different vehicles together in complex missions more similar to reality.
POLARIZATION EFFECTS IN MODELING UNSTEDAY STATE REVERSE OSMOSIS, C. Cerrato, L. Maga, A. P. Reverberi, A.G. Bruzzone
Desalination and ultrafiltration processes have gained a growing interest in recent years and a very rich literature has been developed to model both large scale plants and local convectiondiffusion phenomena governing the single-step units [1-2]. In the latter context, membrane separation technologies by reverse osmosis are a very promising tool to realize separation of ions from aqueous solutions and in recovery of valuable or toxic cations from wastewaters. The most important modelling techniques in describing reverse osmosis rely upon different schemes that, as a first approximation, can be summarized in semi-emipirical mass-transfer models, film theory and more accurate differential-algebraic models accounting for hydrodynamics and interface thermodynamics [3]. Semi-empirical models represent a first and maybe rough attempt where the concentration profile is studied by analogies with heat transfer correlations. Film theory can be considered a satisfactory trade-off between computational simplicity and reliability of results. In fact, this theory allows to treat a complex mass transfer process as a simple one-dimensional problem provided the axial convection close to the membrane surface is assumed negligible. However, the most interesting approach to better foresee the concentration trend near the membrane surface is based on an unsteady-state modelling of the diffusion-convection equation in one or two space variables [4-5]. According to this strategy, fouling can be predicted with good accuracy. Unfortunately, this technique is often affected by numerical instabilities related, for instance, to a bad matching between initial and boundary conditions that may severely endanger the applicability of the method. In this paper, we propose a numerical simulation of a single-step separation in a spiral wound module in unsteadystate regime with axial and radial diffusion. The scheme is organized as follows. In section 2, we outline the essentials of the model and we describe the numerical algorithm. In section 3, we present the results of the simulations obtained with different values of the parameters conditioning the yield of the global process. In particular, we estimate the role of the diffusivity in tuning the onset of the polarization regime. In section 3 we draw the conclusion and trace the direction for future works.
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