Associated Professor, Head of Laboratory of Biocybernetics, Department of pathophysiology, 1st Faculty of Medicine, Charles University, Czech Republic.

Speech Title: Modelica – a language for integrative and system physiology modelling
Abstract: The integrative model of human physiology connects individual physiological subsystems into a single unit. They are enormous (contain thousands of variables) and represent a formalized description of interconnected physiological regulations. The issue of formalization of physiological systems became part of a series of international projects (e.g. the worldwide program PHYSIOME, or the European program VIRTUAL PHYSIOLOGICAL HUMAN). The development of large-scale models of human physiology was facilitated by a new (i.e. equation-based) generation of simulation environments, especially by the Modelica language. Fundamental innovation is the possibility to describe individual parts of the model as a system of equations directly describing the behavior of that part and not the algorithm of solving of these equations. The connection of these equation-based principles with object-oriented principles makes Modelica a great language for the huge systems that are typical in integrative and system physiology. Unlike block-oriented causal modelling languages (e.g. Simulink) where the structure of connections among hierarchical blocks represents rather the computation process instead of the modelled reality, the structure of models in Modelica shows the structure of the modelled reality. These advantages are demonstrated in practice by our implementation of the large integrative model of human physiology “HumMod”, which we reimplemented (modified and expanded) in the acausal environment of the Modelica language. Our implementation of this model in Modelica has brought a much clearer description of the simulated complex physiological relationships than the original block oriented implementation.
Keywords: simulation; integrative physiology; system physiology; modelling languages; block-oriented modelling; causal modelling; acausal modelling; Modelica