Scala A.,CNR Institute for Complex Systems |
Scala A.,IMT Institutions Market Technology |
Scala A.,LIMS London Institute for Mathematical science |
Pahwa S.,Kansas State University |
Scoglio C.M.,Kansas State University
International Journal of Critical Infrastructures | Year: 2015
Power grids are nowadays experiencing a transformation due to the introduction of distributed generation based on renewable sources. At difference with classical distributed generation, where local power sources mitigate anomalous user consumption peaks, renewable sources introduce in the grid intrinsically erratic power inputs. By introducing a simple schematic (but realistic) model for power grids with stochastic distributed generation, we study the effects of erratic sources on the robustness of several IEEE power grid test networks with up to 2 × 103 buses. We find that increasing the penetration of erratic sources causes the grid to fail with a sharp transition. We compare such results with the case of failures caused by the natural increasing power demand. Copyright © 2015 Inderscience Enterprises Ltd.
Caldarelli G.,IMT Institutions Market Technology |
Caldarelli G.,CNR Institute for Complex Systems |
Caldarelli G.,LIMS London Institute for Mathematical science |
Cristelli M.,CNR Institute for Complex Systems |
And 10 more authors.
PLoS ONE | Year: 2012
In this paper we analyze the bipartite network of countries and products from UN data on country production. We define the country-country and product-product projected networks and introduce a novel method of filtering information based on elements' similarity. As a result we find that country clustering reveals unexpected socio-geographic links among the most competing countries. On the same footings the products clustering can be efficiently used for a bottom-up classification of produced goods. Furthermore we mathematically reformulate the "reflections method" introduced by Hidalgo and Hausmann as a fixpoint problem; such formulation highlights some conceptual weaknesses of the approach. To overcome such an issue, we introduce an alternative methodology (based on biased Markov chains) that allows to rank countries in a conceptually consistent way. Our analysis uncovers a strong non-linear interaction between the diversification of a country and the ubiquity of its products, thus suggesting the possible need of moving towards more efficient and direct non-linear fixpoint algorithms to rank countries and products in the global market. © 2012 Caldarelli et al.