Here I introduce the Stock-and-Flow diagrams, that use a symbolic representation taken from energetics. I will show how to draw a comprehensive diagram including only stocks, flows and processes, and how the choice of these sets of elements and of the (spatial and temporal) boundary actually reflects the reason why one wants to study the system at issue. The reality described by a systemic diagram is not “a photograph” of that system, as is typical of many reductionist approaches like for example those of Biology and of particle Physics. Instead, the systemic diagram is a virtual photograph of its dynamical structure. A particular attention will be then dedicated to the concept of feedback and to the role of hierarchical feedback networks, that is the characteristic that ultimately determines the whole system dynamics. I will introduce how to define the analytical expressions of flows, processes and interactions. From these, a set of interconnected differential equations may be established, from which a computational simulator can be set up using finite differences methods..
Francesco Gonella short bio
PhD in Physics at University of Padova, Italy. Excéllence Postdoctorale at the Université Laval, Québec City, Canada. Since 2016, Full Professor of Physics at the Department of Molecular Sciences and Nanosystems of the Ca’ Foscari University of Venice. After twenty years of activity as an experimental physicist (study of nanostructured glasses, artistic glasses and glasses for energy technologies), ten years ago I have shifted my interests to Systems Thinking and Emergy Analysis, applied to the study of the functioning and the integrated sustainability of systems. I am Director of the “International School on Emergy Accounting'', and member of the Executive Council of the International Society for the Advancement in Emergy Research. I teach Sustainability and Systems Thinking at the Beijing Normal University in China as a high-end foreign expert, and keep courses on the same topics at the Universities of Turin and Catania in Italy. I was Visiting Professor at Tokyo Institute of Technology, Japan, for two years, and Visiting Researcher at Vanderbilt University (Nashville, USA) and the University of Florida (Gainesville, USA). H-index=37 (2020, Scopus). Author or co-author of almost 200 publications in international peer-reviewed Journals. Invited lecturer in Universities in Canada, USA, Germany, India, Japan, China, Poland, France.