Networks and non-autonomous dynamics, with applications to cell energy metabolism

Living systems are defined by their thermodynamic openness, by the fact that energy and matter are able to cross their boundaries. Without this capability to interact with their environment, living systems would be unable to support their life-sustaining functions. As a result of this continual interaction with its environment, the interior processes of a living system is forced to operate far from any equilibrium. Indeed, any system that is in equilibrium internally or with its environment could reasonably be characterised as a dead one. The dynamics of systems that are operating far from equilibrium, however, are far from understood. In this thesis, we build on an existing framework for understanding these dynamics, based in the finite-time analysis of non-autonomous oscillatory processes. This approach is motivated by a key consequence of thermodynamic openness — to introduce time-dependence to the open system. We develop an original mathematical model for the energy metabolism of cells using inter-coupled networks of non-autonomous phase oscillators, with intra-network weighted coupling. The effect of each of this model’s components on its dynamics and stability is numerically analysed. Experimental data of the metabolism of HeLa cells is analysed, finding the fundamental frequencies of this process. This analysis is used to demonstrate the capability of the model to reproduce the complex dynamics of the experiment, and this is contrasted to a comparable model of an alternative framework. It is this capacity of non-autonomous oscillations to simply and deterministically produce apparently highly complex dynamics that justifies our application of them to this problem. We demonstrate it further by viewing them through the framework of statistical time-series analysis, finding that even a single non-autonomous oscillator can appear to be 1/fβ noise in a power-spectral density estimation. Autonomous systems are shown to only present as noise when there are many of them, and hence it is the introduction of time-dependence that generates such complexity so readily. We demonstrate that this also occurs for coupled networks of non-autonomous oscillators, and in real experimental data. Analysis tools based in a finite-time framework, however, are shown to detect informative deterministic frequencies and couplings in both the numerical and experimental cases. Overall, this thesis demonstrates that networks of non-autonomous oscillations are physically linked to living systems through the time-dependence introduced by thermodynamic openness. Additionally, it is shown that they are able to reproduce living systems’ complex dynamics in a simple and usable way. Finally, it is established that much greater information about such an open system can be gained when they are analysed with this time-dependent deterministic framework in mind

Symmetry in Renewable Energy and Power Systems

This book includes original research papers related to renewable energy and power systems in which theoretical or practical issues of symmetry are considered. The book includes contributions on voltage stability analysis in DC networks, optimal dispatch of islanded microgrid systems, reactive power compensation, direct power compensation, optimal location and sizing of photovoltaic sources in DC networks, layout of parabolic trough solar collectors, topologic analysis of high-voltage transmission grids, geometric algebra and power systems, filter design for harmonic current compensation. The contributions included in this book describe the state of the art in this field and shed light on the possibilities that the study of symmetry has in power grids and renewable energy systems

Proceedings of the ECCOMAS Thematic Conference on Multibody Dynamics 2015

This volume contains the full papers accepted for presentation at the ECCOMAS Thematic Conference on Multibody Dynamics 2015 held in the Barcelona School of Industrial Engineering, Universitat Politècnica de Catalunya, on June 29 - July 2, 2015. The ECCOMAS Thematic Conference on Multibody Dynamics is an international meeting held once every two years in a European country. Continuing the very successful series of past conferences that have been organized in Lisbon (2003), Madrid (2005), Milan (2007), Warsaw (2009), Brussels (2011) and Zagreb (2013); this edition will once again serve as a meeting point for the international researchers, scientists and experts from academia, research laboratories and industry working in the area of multibody dynamics. Applications are related to many fields of contemporary engineering, such as vehicle and railway systems, aeronautical and space vehicles, robotic manipulators, mechatronic and autonomous systems, smart structures, biomechanical systems and nanotechnologies. The topics of the conference include, but are not restricted to: ● Formulations and Numerical Methods ● Efficient Methods and Real-Time Applications ● Flexible Multibody Dynamics ● Contact Dynamics and Constraints ● Multiphysics and Coupled Problems ● Control and Optimization ● Software Development and Computer Technology ● Aerospace and Maritime Applications ● Biomechanics ● Railroad Vehicle Dynamics ● Road Vehicle Dynamics ● Robotics ● Benchmark ProblemsPostprint (published version