Scalable robustness of interconnected systems subject to structural changes

This paper studies the robustness of large-scale interconnected systems with respect to external disturbances, focussing on their scalability properties. Specifically, a notion of scalability is introduced that asks for these robustness properties to remain unchanged under a structural change of the system, such as the addition/removal of a subsystem or a change in the interconnection structure. Both necessary and sufficient conditions, in terms of the interconnection structure and edge weights, are given under which elementary structural changes are scalable. The results are illustrated through a simple example.Comment: Published in the Proceedings of the IFAC World Congress, Berlin, Germany, 202

Impulsive perturbations to differential equations: stable/unstable pseudo-manifolds, heteroclinic connections, and flux

State-dependent time-impulsive perturbations to a two-dimensional autonomous flow with stable and unstable manifolds are analysed by posing in terms of an integral equation which is valid in both forwards- and backwards-time. The impulses destroy the smooth invariant manifolds, necessitating new definitions for stable and unstable pseudo-manifolds. Their time-evolution is characterised by solving a Volterra integral equation of the second kind with discontinuous inhomogeniety. A criteria for heteroclinic trajectory persistence in this impulsive context is developed, as is a quantification of an instantaneous flux across broken heteroclinic manifolds. Several examples, including a kicked Duffing oscillator and an underwater explosion in the vicinity of an eddy, are used to illustrate the theory

Stochastic environmental effects, demographic variation, and economic growth

We consider a stochastic environment to study interactions among pollution growth, demographic changes, and economic growth. Drawing on the empirical findings of slow convergence patterns of pollution shocks (viz., with a long-memory), we build an analytical framework where stochastic environmental feedback effects on population changes are reflected upon aggregate economic growth. Long-memory in economic growth, in our model, is shown to arise due to the inherent stochasticity in environmental and demographic system. Empirical results for a set of developed and developing countries generally support our conjecture. Simulation experiment is carried out to lend additional support to this claim.Environmental Quality, Long-memory, Demographic Dynamics, Economic Growth

A combined geomorphological and geophysical approach to characterising relict landslide hazard on the Jurassic Escarpments of Great Britain

The Jurassic Escarpment in the North York Moors in Northern Britain has a high density of deep-seated relict landslides but their regional hazard is poorly understood due to a lack of detailed case studies. Investigation of a typical relict landslide at Great Fryup Dale suggests that the crop of the Whitby Mudstone Formation is highly susceptible to landslide hazards. The mudstone lithologies along the Escarpment form large multiple rotational failures which break down at an accelerated rate during wetter climates and degrade into extensive frontal mudflows. Geomorphological mapping, high resolution LiDAR imagery, boreholes, and geophysical ERT surveys are deployed in a combined approach to delimit internal architecture of the landslide. Cross-sections developed from these data indicate that the main movement displaced a bedrock volume of c. 1 × 107 m3 with a maximum depth of rupture of c. 50 m. The mode of failure is strongly controlled by lithology, bedding, joint pattern, and rate of lateral unloading. Dating of buried peats using the AMS method suggests that the 10 m thick frontal mudflow complex was last active in the Late Holocene, after c. 2270 ± 30 calendar years BP. Geomorphic mapping and dating work indicates that the landslide is dormant, but slope stability modelling suggests that the slope is less stable than previously assumed; implying that this and other similar landslides in Britain may become more susceptible to reactivation or extension during future wetter climatic phases. This study shows the value of a multi-technique approach for landslide hazard assessment and to enhance national landslide inventories

Economic convergence and uneven development : the role of increasing returns and trade imbalances in the eurozone genesis and crisis

Tesis de la Universidad Complutense de Madrid, Facultad de Ciencias Económicas y Empresariales, leída el 05-11-2018La Eurozona constituye el intento de integración económica y monetaria entre países más importante de la historia moderna. Culminando el proyecto original esbozado en el Tratado de Roma (1957), el Tratado de Maastricht (1992) estableció el origen de una Unión Económica y Monetaria cuyo elemento definitorio será la introducción de una nueva divisa: el Euro. Algunos de sus objetivos más pretenciosos apuntaban a conseguir creciente cohesión y convergencia económica entre sus miembros mientras la Eurozona se transformaba en el área más competitiva a nivel global. Sin embargo, las herramientas consideradas para alcanzar estos objetivos resultaron ingenuas en el mejor de los casos. Confiando fervorosamente en las propiedades de un mercado abierto y la libre movilidad de capitales, el éxito transitorio experimentado por los paises miembros de la Eurozona durante los años noventa y primeros años del nuevo siglo parecieron confirmar estas intuiciones. A pesar de este éxito inicial, una vez la crisis financiera de 2008 se desató en Europa, las asimetrías características del reciente proceso de construcción Europea no pudieron ocultarse por más tiempo. Un desempeño externo muy asimétrico, gaps de productividad e importantes diferencias sectoriales aparecieron como elementos clave explicando una crisis europea caracterizada por una autoimpuesta ignorancia institucional en materia de política industrial o monetaria más allá de hieráticos objetivos definidos de inflación y laissez-faire industrial.,,The Eurozone constitutes the most important attempt in modern history of a monetary and economic integration process among countries. Culminating the original project drawn in the Treatise of Rome (1957), the Maastricht Treaty (1992) established the origin of an Economic Union whose cornerstone was the introduction of a common currency: the Euro. Some of its most pretentious goals were to achieve growing cohesion and economic convergence among its members while transforming the Eurozone in the most competitive area worldwide. However, the tools considered in order to achieve these goals were, as it is widely known nowadays, naïve at best. Relying fervorously on the properties of free markets and capital mobility, the transitory success experienced by Eurozone countries during the nineties and early years of the new century seemed to confirm these intuitions. In spite of this initial success, once the 2008 global crisis was triggered in Europe, the asymmetries which characterised the recent European construction process could not be ignored anymore. Uneven external performance, productivity gaps and sectoral differences appeared as core elements explaining a European crisis characterised by a self-imposed institutional ignorance on industrial or monetary policies beyond inflation targets´and industrial laissez-faire. This bias underlying the construction and development of the Eurozone still determines the path of the ongoing European crisis and constitutes the starting point where this dissertation is placed...Fac. de Ciencias Económicas y EmpresarialesTRUEunpu