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Simulation Platform (simulation + platform)
Selected AbstractsA programming environment for behavioural animationCOMPUTER ANIMATION AND VIRTUAL WORLDS (PREV: JNL OF VISUALISATION & COMPUTER ANIMATION), Issue 5 2002Frédéric Devillers Abstract Behavioural models offer the ability to simulate autonomous agents like organisms and living beings. Psychological studies have shown that human behaviour can be described by a perception,decision,action loop, in which the decisional process should integrate several programming paradigms such as real time, concurrency and hierarchy. Building such systems for interactive simulation requires the design of a reactive system treating flows of data to and from the environment, and involving task control and preemption. Since a complete mental model based on vision and image processing cannot be constructed in real time using purely geometrical information, higher levels of information are needed in a model of the virtual environment. For example, the autonomous actors of a virtual world would exploit the knowledge of the environment topology to navigate through it. Accordingly, in this paper we present our programming environment for real-time behavioural animation which is compounded of a general animation and simulation platform, a behavioural modelling language and a scenario-authoring tool. Those tools has been used for different applications such as pedestrian and car driver interaction in urban environments, or a virtual museum populated by a group of visitors. Copyright © 2002 John Wiley & Sons, Ltd. [source] Improving realism of a surgery simulator: linear anisotropic elasticity, complex interactions and force extrapolationCOMPUTER ANIMATION AND VIRTUAL WORLDS (PREV: JNL OF VISUALISATION & COMPUTER ANIMATION), Issue 3 2002Guillaume Picinbono Abstract In this article, we describe the latest developments of the minimally invasive hepatic surgery simulator prototype developed at INRIA. The goal of this simulator is to provide a realistic training test bed to perform laparoscopic procedures. Therefore, its main functionality is to simulate the action of virtual laparoscopic surgical instruments for deforming and cutting tridimensional anatomical models. Throughout this paper, we present the general features of this simulator including the implementation of several biomechanical models and the integration of two force-feedback devices in the simulation platform. More precisely, we describe three new important developments that improve the overall realism of our simulator. First, we have developed biomechanical models, based on linear elasticity and finite element theory, that include the notion of anisotropic deformation. Indeed, we have generalized the linear elastic behaviour of anatomical models to ,transversally isotropic' materials, i.e. materials having a different behaviour in a given direction. We have also added to the volumetric model an external elastic membrane representing the ,liver capsule', a rather stiff skin surrounding the liver, which creates a kind of ,surface anisotropy'. Second, we have developed new contact models between surgical instruments and soft tissue models. For instance, after detecting a contact with an instrument, we define specific boundary constraints on deformable models to represent various forms of interactions with a surgical tool, such as sliding, gripping, cutting or burning. In addition, we compute the reaction forces that should be felt by the user manipulating the force-feedback devices. The last improvement is related to the problem of haptic rendering. Currently, we are able to achieve a simulation frequency of 25,Hz (visual real time) with anatomical models of complex geometry and behaviour. But to achieve a good haptic feedback requires a frequency update of applied forces typically above 300,Hz (haptic real time). Thus, we propose a force extrapolation algorithm in order to reach haptic real time. Copyright © 2002 John Wiley & Sons, Ltd. [source] The design of supervisory rule-based control in the operating theatre via an anaesthesia simulatorEXPERT SYSTEMS, Issue 1 2002M. Mahfouf The development of online drug administration strategies in operating theatres represents a highly safety-critical situation. The usefulness of different levels of simulation prior to clinical trials has been shown in previous studies in muscle relaxant anaesthesia. Thus, in earlier work on predictive self-tuning control for muscle relaxation a dual computer real-time simulation was undertaken, subsequent to algorithm validation via off-line simulation. In the present approach a supervised rule-based control algorithm is used. The control software was implemented on the actual machine to be used in theatre, while another computer acted as a real-time patient simulator. This set-up has further advantages of providing accurate timing and also finite data accuracy via the ADC/DAC interface, or the equivalent digital lines. Also, it provides for controller design fast simulation studies compared to the real-time application. In this paper, a new architecture which combines several hierarchical levels for control (a Mamdani-type fuzzy controller), adaptation (self-organizing fuzzy logic control) and performance monitoring (fault detection, isolation and accommodation) is developed and applied to a computer real-time simulation platform for muscle relaxant anaesthesia. Experimental results showed that the proposed algorithm fulfilled successfully the requirements for autonomy, i.e. automatic control, adaptation and supervision, and proved effective in dealing with the faults and disturbances which are normally encountered in operating theatres during surgery. [source] Three-dimensional simulations of biofilm growth in porous mediaAICHE JOURNAL, Issue 2 2009D. A. Graf von der Schulenburg Abstract Biofilm growth occurs in a variety of random porous media in a range of industrial processes; prediction of its growth and subsequent influence on hydrodynamics is hence desirable. In this study, we present the first numerical 3D pore-scale model of biofilm growth in porous media, based on a lattice Boltzmann simulation platform complemented with an individual-based biofilm model (IbM). We use it to explore the coupled interaction between nutrient mass transport, biofilm growth, and hydrodynamics. Biofilm is shown to be very effective at reducing the permeability of porous media, particularly under nutrient limited conditions. We conclude with a direct comparison of 3D and 2D biofilm growth simulations in porous media and show the necessity of performing the simulations in 3D. © 2008 American Institute of Chemical Engineers AIChE J, 2009 [source] Lumped dynamic model for a bistable genetic regulatory circuit within a variable-volume whole-cell modelling frameworkASIA-PACIFIC JOURNAL OF CHEMICAL ENGINEERING, Issue 6 2009Gheorghe Maria Abstract Genetic regulatory circuits (GRCs) including switches, oscillators, signal amplifiers or filters, and signalling circuits are responsible for the control of cell metabolism. Modelling such complex GRCs is a difficult task due to high complexity of the the process (partly known) and the structural, functional and temporal hierarchical organisation of the cell system. Modular lumped representation, grouping some reactions/components and including different types of variables, is a promising alternative allowing individual module characterisation and elaboration of extended simulation platforms for representing the GRC dynamic properties and designing new cell functions. Such models allow to in-silico design modified micro-organisms with desirable properties for practical applications in bioprocess engineering and biotechnology. In the present work, the analysis of a designed bistable switch formed by two gene expression modules is performed in a variable-volume and whole-cell modelling framework, by mimicking the Escherichia coli cell growth. The advantages but also limitations of such a new approach are investigated, by using a Hill-type kinetics combined with few elementary steps, with the aim of better representing the adjustable levels of key intermediates tuning the GRC regulatory properties in terms of stability strength, species connectivity, responsiveness, and regulatory efficiency under stationary and dynamic perturbations. Copyright © 2009 Curtin University of Technology and John Wiley & Sons, Ltd. [source] | ||||||||||