Unveiling connectivity patterns of categories in complex systems: an application to human needs in urban places

This is an Accepted Manuscript of an article published by Taylor & Francis in Journal of mathematical sociology on 06/09/2016, available online: http://www.tandfonline.com/doi/full/10.1080/0022250X.2016.1219855We present a methodology based on weighted networks and dependence coefficients aimed at revealing connectivity patterns between categories. As a case study, it is applied to an urban place and at two spatial levels—neighborhood and square—where categories correspond to human needs. Our results show that diverse spatial levels present different and nontrivial patterns of need emergence. A numerical model indicates that these patterns depend on the probability distribution of weights. We suggest that this way of analyzing the connectivity of categories (human needs in our case study) in social and ecological systems can be used to define new strategies to cope with complex processes, such as those related to transition management and governance, urban-making, and integrated planning.Peer ReviewedPostprint (author's final draft

Network hierarchy evolution and system vulnerability in power grids

(c) 2016 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other users, including reprinting/ republishing this material for advertising or promotional purposes, creating new collective works for resale or redistribution to servers or lists, or reuse of any copyrighted components of this work in other works.The seldom addressed network hierarchy property and its relationship with vulnerability analysis for power transmission grids from a complex-systems point of view are given in this paper. We analyze and compare the evolution of network hierarchy for the dynamic vulnerability evaluation of four different power transmission grids of real cases. Several meaningful results suggest that the vulnerability of power grids can be assessed by means of a network hierarchy evolution analysis. First, the network hierarchy evolution may be used as a novel measurement to quantify the robustness of power grids. Second, an antipyramidal structure appears in the most robust network when quantifying cascading failures by the proposed hierarchy metric. Furthermore, the analysis results are also validated and proved by empirical reliability data. We show that our proposed hierarchy evolution analysis methodology could be used to assess the vulnerability of power grids or even other networks from a complex-systems point of view.Peer ReviewedPostprint (author's final draft

Spatial and performance optimality in power distribution networks

(c) 2016 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other users, including reprinting/ republishing this material for advertising or promotional purposes, creating new collective works for resale or redistribution to servers or lists, or reuse of any copyrighted components of this work in other works.Complex network theory has been widely used in vulnerability analysis of power networks, especially for power transmission ones. With the development of the smart grid concept, power distribution networks are becoming increasingly relevant. In this paper, we model power distribution systems as spatial networks. Topological and spatial properties of 14 European power distribution networks are analyzed, together with the relationship between geographical constraints and performance optimization, taking into account economic and vulnerability issues. Supported by empirical reliability data, our results suggest that power distribution networks are influenced by spatial constraints which clearly affect their overall performance.Peer ReviewedPostprint (author's final draft

A simple spatiotemporal evolution model of a transmission power grid

In this paper, we present a model for the spatial and temporal evolution of a particularly large human-made network: the 400-kV French transmission power grid. This is based on 1) an attachment procedure that diminishes the connection probability between two nodes as the network grows and 2) a coupled cost function characterizing the available budget at every time step. Two differentiated and consecutive processes can be distinguished: a first global space-filling process and a secondary local meshing process that increases connectivity at a local level. Results show that even without power system engineering design constraints (i.e., population and energy demand), the evolution of a transmission network can be remarkably explained by means of a simple attachment procedure. Given a distribution of resources and a time span, the model can also be used to generate the probability distribution of cable lengths at every time step, thus facilitating network planning. Implications for network's fragility are suggested as a starting point for new design perspectives in this kind of infrastructures.Peer ReviewedPostprint (author's final draft

Sustainability study for wheat straw torrefaction technology

The aim of this article is to examine the torrefaction production technology placed in two power plant environment (Rankine-Clausius, and Organic Rankine-Clausius circular procedures). The torrefaction is a heat treatment process at 280 – 300 °C obturated from oxygen, this heat treatment effectively changing the structure of the material, and the feedstock’s heating value improves. Our study is restricted is wheat pallet because we conducted the laboratory experiments with material. In Hungary the agricultural industry produces raw materials in big amounts (mainly combustibles that is energetically renewables) which are at the moment, mixed with nitrogen-based fertilizers and biodegradable anaerobe bacteria ploughed back into the tillage as a form of nutrient supply. It takes 9 months to become nutriment from this inorganic material. The object of our study is the key equipment of a production technology which continuously works, double-jacketed, and can be subjected to vacuuming. This equipment is a cylindrical furnace in which the torrefaction is realized.Peer ReviewedPostprint (published version

Transport energy consumption in mountainous roads. A comparative case study for internal combustion engines and electric vehicles in Andorra

This paper analyses transport energy consumption of conventional and electric vehicles in mountainous roads. A standard round trip in Andorra has been modelled in order to characterise vehicle dynamics in hilly regions. Two conventional diesel vehicles and their electric-equivalent models have been simulated and their performances have been compared. Six scenarios have been simulated to study the effects of factors such as orography, traffic congestion and driving style. The European fuel consumption and emissions test and Artemis urban driving cycles, representative of European driving cycles, have also been included in the comparative analysis. The results show that road grade has a major impact on fuel economy, although it affects consumption in different levels depending on the technology analysed. Electric vehicles are less affected by this factor as opposed to conventional vehicles, increasing the potential energy savings in a hypothetical electrification of the car fleet. However, electric vehicle range in mountainous terrains is lower compared to that estimated by manufacturers, a fact that could adversely affect a massive adoption of electric cars in the short term.Peer ReviewedPostprint (author’s final draft

Smart Grids and Complexity Science

Postprint (published version

Topological Complexity of the Electricity Transmissión Network. Implications in the Sustainability Paradigm

Aquesta tesi explora i estudia l'estructura, dinàmica i evolució de la xarxa de transmissió d'electricitat des de la perspectiva dels sistemes complexos, essent el seu principal objectiu la definició de nous criteris i eines per ajudar a un disseny més eficient i sostenible de la xarxa de transmissió de potència. Per assolir aquest objectiu, s'han estudiat i analitzat dos conjunts de dades. D'una banda, la xarxa corresponent a la Unió per la Coordinació de Transport d'Electricitat (UCTE), que associa a la majoria dels operadors de xarxes elèctriques nacionals de l'Europa continental amb la finalitat de coordinar la producció i la demanda anual d'uns 2.300 TWh d'energia per 450 milions de clients de 24 països diferents. D'altra banda, l'evolució històrica de la xarxa de transport del Gestionaire du Réseau du Transport d'Electricité (RTE), responsable de l'explotació, manteniment i desenvolupament de la xarxa nacional mésgran d'Europa, la xarxa francesa de transport d'electricitat.Els resultats obtinguts fins al moment mostren diferències estadísticament significatives en l'estructura de les xarxes elèctriques, definint clarament comportaments dinàmics particulars que ens permeten segregar les xarxes europees en dos grups, a saber, fràgil i robust. Les xarxes fràgils es caracteritzen per les topologies més estructurades, mallades i no a l'atzar, mentre que les topològiques de caràcter més robust, contraintuïtivament, tenen estructures molts més aleatòries. Les conseqüències d'aquestes troballes per a la sostenibilitat de les xarxes d'infraestructures són importants en termes de cost i avaluació d'impactes i riscos. Es presenta així mateix un model per a l'evolució temporal i espacial d'una xarxa elèctrica. En aquest sentit, suggerim que la fragilitat topològica global augmenta quan es consideren accions de connectivitat de caire local a fi d'augmentar la fiabilitat de la xarxa a escala regional.Aquests resultats suggereixen la necessitat d'aplicar nous mètodes de disseny de la xarxa elèctrica així com noves eines amb capacitat per incloure aquests nous aspectes topològics en l'avaluació de l'eficiència i la fiabilitat de lamateixa.This Thesis explores the structure, dynamics and evolution of the electricity transmission network from a complexsystems perspective, its main objective being the definition of new criteria and tools to help to design a more efficientand sustainable transmission power grid. In doing so, two data sets have been explored and analyzed. On one hand,the Union for the Coordination of Transport of Electricity (UCTE) network, which associates most of the continentalEurope national power grid operators in order to coordinate the production and demand of some annual 2300 TWh ofenergy and 450 million customers from 24 countries. On the other hand, the Gestionaire du Réseau du Transportd'Electricité (RTE) transport network historical evolution, responsible for operating, maintaining and developing thebiggest national network in Europe, the French electricity transmission network.The results obtained so far show statistically significant dissimilarities in the structure of the power grids, clearlydefining and enclosing particular dynamic behaviors that enable us to segregate European networks in two sets,namely fragile and robust. Fragile networks are characterized by meshed topologies and non random structures whilerobust ones share more randomly generated topologies. The consequences of these finding for the sustainability ofinfrastructure networks are significant in terms of cost and risk assessment. A model for the evolution of a power gridnetwork is also presented. We suggest that global topological fragility increases when local connectivity schemes areadapted in order to increase local reliability.These outcomes appeal for new power grid design methods and tools capable to include these new topologicalaspects into efficiency and reliability assessment

Maximising the degree of user choice: a simple tool to measure current levels of quality of life in urban environments

In this article, a simple tool based on Max-Neef et al.’s (1991) Human-Scale Development paradigm to measure current levels of Quality of Life (QoL) for urban environments is presented. Fundamental human needs form the study domains. The process of the system definition and the survey creation is explained. Questions are then classified into needs as the outcome of two consecutive processes: a qualitative one involving both local communities and/or expert groups, and a quantitative one involving the definition of question weights. Complementarily, objective indicators are added, allowing a comparison between subjective and objective data towards an integrative result. In summary, this method can be used to define more holistic urban quality indexes in order to improve decision making processes, policies and plans. At the same time it can be seen as a tool to enhance bottom-up approaches and processes of urban analysis in order to create more liveable places for the dwellers.Preprin