Quantum Navigation and Ranking in Complex Networks

Complex networks are formal frameworks capturing the interdependencies between the elements of large systems and databases. This formalism allows to use network navigation methods to rank the importance that each constituent has on the global organization of the system. A key example is Pagerank navigation which is at the core of the most used search engine of the World Wide Web. Inspired in this classical algorithm, we define a quantum navigation method providing a unique ranking of the elements of a network. We analyze the convergence of quantum navigation to the stationary rank of networks and show that quantumness decreases the number of navigation steps before convergence. In addition, we show that quantum navigation allows to solve degeneracies found in classical ranks. By implementing the quantum algorithm in real networks, we confirm these improvements and show that quantum coherence unveils new hierarchical features about the global organization of complex systems.Comment: title changed, more real networks analyzed, version published in scientific report

On the trend to global equilibrium for Kuramoto oscillators

The work of J. Morales was supported by the NSF grants DMS16-13911, RNMS11-07444 (KI-Net) and ONR grant N00014-1812465. The work of D. Poyato was partially supported by the MECD (Spain) research grant FPU14/06304, the MINECO-Feder (Spain) research grant number RTI2018-098850-B-I00, the Junta de Andalucia (Spain) projects PY18-RT-2422 and A-FQM-311-UGR18, and the European Research Council (ERC) grant agreement no. 639638.In this paper we study convergence to the stable equilibrium for Kuramoto oscillators. Specifically, we derive estimates on the rate of convergence to the global equilibrium for solutions of the Kuramoto–Sakaguchi equation departing from generic initial data in a large coupling strength regime. As a by-product, using the stability of the equation in the Wasserstein distance, we quantify the rate at which discrete Kuramoto oscillators concentrate around the global equilibrium. In doing this, we achieve a quantitative estimate in which the probability that oscillators concentrate at the given rate tends to 1 as the number of oscillators increases. Among the essential steps in our proof are (1) an entropy production estimate inspired by the formal Riemannian structure of the space of probability measures, first introduced by Otto (2001); (2) a new quantitative estimate on the instability of equilibria with antipodal oscillators based on the dynamics of norms of the solution in sets evolving by the continuity equation; (3) the use of generalized local logarithmic Sobolev- and Talagrand-type inequalities, similar to those derived by Otto and Villani (2000); (4) the study of a system of coupled differential inequalities by a treatment inspired by Desvillettes and Villani (2005). Since the Kuramoto–Sakaguchi equation is not a gradient flow with respect to the Wasserstein distance, we derive such inequalities under a suitable fibered transportation distance.MINECO-Feder RTI2018-098850-B-I00National Science Foundation DMS16-13911, RNMS11-07444 NSFOffice of Naval Research N00014-1812465 ONREuropean Research Council 639638 ERCMinisterio de Educación, Cultura y Deporte FPU14/06304 MECDJunta de Andalucía A-FQM-311-UGR18, PY18-RT-242

A Highly Available Cluster of Web Servers with Increased Storage Capacity

Ponencias de las Decimoséptimas Jornadas de Paralelismo de la Universidad de Castilla-La Mancha celebradas el 18,19 y 20 de septiembre de 2006 en AlbaceteWeb servers scalability has been traditionally solved by improving software elements or increasing hardware resources of the server machine. Another approach has been the usage of distributed architectures. In such architectures, usually, file al- location strategy has been either full replication or full distribution. In previous works we have showed that partial replication offers a good balance between storage capacity and reliability. It offers much higher storage capacity while reliability may be kept at an equivalent level of that from fully replicated solutions. In this paper we present the architectural details of Web cluster solutions adapted to partial replication. We also show that partial replication does not imply a penalty in performance over classical fully replicated architectures. For evaluation purposes we have used a simulation model under the OMNeT++ framework and we use mean service time as a performance comparison metric.Publicad

Experimental characterization framework for SLA additive manufacturing materials

This article belongs to the Special Issue Mechanical Performance of Polymeric Parts Obtained by Additive Manufacturing.Additive manufacturing (AM) is driving a change in the industry not only regarding prototyping but due to the ease of including printed parts in final designs. Engineers and designers can go deeper into optimization and improvements of their designs without drawbacks of long manufacturing times. However, some drawbacks such as the limited available materials or uncertainty about mechanical properties and anisotropic behavior of 3D printed parts prevent use in large-scale production. To gain knowledge and confidence about printed materials it is necessary to know how they behave under different stress states and strain-rate regimes, and how some of the printing parameters may affect them. The present work proposes an experimental methodology framework to study and characterize materials printed by stereolithography (SLA) to clarify certain aspects that must be taken into account to broaden the use of this kind of material. To this end, tensile and compression tests at different strain rates were carried out. To study the influence of certain printing parameters on the printed material behavior, samples with different printing angles (θ = [0–90]) and different printing resolution (layer height of 50 and 100 µm) were tested. In addition, the effects of curing time and temperature were also studied. The testing specimens were manufactured in the non-professional SLA machine Form 2 from Formlabs® using resin called Durable. Nevertheless, the proposed experimental methodology could be extended to any other resin.Ministerio de Asuntos Económicos y Transformación Digital, Gobierno de España grant number DPI2017-85073-R, and Vicerrectorado de Política Científica UC3M (Projects 2013/00413/003 and 2014/00006/003)

El contexto del deporte en España durante la crisis sanitaria de la COVID-19.

El presente artículo forma parte de la sección de debate "Deporte y COVID-19" del Volumen 1, Número 1, de Sociología del Deporte (SD).Universidad Pablo de Olavid

Développement de lois de comportement générales pour des sols soumis à des chargements de véhicules hors-routes

Il existe actuellement plusieurs modèles qui permettent de prédire le comportement et les performances d'un véhicule. Le succès ou non de ces modèles donnera le consentement pour le développement et l'intégration d'équipements hors-route utilisés dans la construction, l'agriculture et les véhicules de loisirs. Cependant, la représentation du sol dans ces modèles montre des limitations concernant au comportement de l'interface pneu-sol. Premièrement, la teneur en eau et le compactage sont des facteurs qui influencent le comportement rhéologique du sol et cette résistance à se déformer est à la fois influencée par les différentes formes d'application de chargement le long d'une trajectoire du pneu sur une particule de sol. Par conséquent, ce projet cherche à s'appuyer sur les fondements de la géotechnique routière pour la prédiction des performances des matériaux soumis à des charges cycliques. Des fondamentaux qui permettront de développer des outils pour comprendre, d'un autre point de vue, l'interaction entre les sols et les pneus provenant des véhicules hors-route.There are currently several models that can be used to predict a vehicle's behaviour and performance. The success or failure of these models will give consent for the development and integration of off-road equipment used in construction, agriculture, and recreational vehicles. However, the soil representation in these models shows limitations in the behaviour of the tyre-ground interface. Firstly, moisture content and compaction are factors that influence the rheological behaviour of the soil and this resistance to deformation is both influenced by different forms of loading application along a tyre's trajectory on a soil particle. Therefore, this project seeks to build on the foundation of the geotechnics of roads for the prediction of the performance of materials subjected to cyclic loading. These fundamentals will enable the development of tools to understand, from another point of view, the nteraction between soils and tires from off-road vehicles

Market Opportunities of Water Treatments Powered by Solar Micro Gas Turbines: Chile and Ecuador Case Studies

Throughout the last decades the developments on desalination field have been focused on energy consumption and costs reduction. However, water recovery and brine disposal are becoming a matter of concern to desalination industry. In this work, a Zero Liquid Discharge (ZLD) unit coupled with a Solar Micro Gas Turbine (SMGT) system is presented to address, among others, the challenges of mining industry in remote areas, in particular, fossil fuel dependence, water availability and pollution derived from effluents disposal. As a way to assess the feasibility of the proposal, a techno-economic analysis of the application in two Southern American regions (Chile and Ecuador) of photovoltaic modules, wind turbines and Solar Micro Gas Turbines is performed. Afterwards, the main novel feature of the new system—i.e., the ZLD unit—is described and a sensitivity analysis on its functioning whilst coupled with the SMGT is carried out. The aim is to propose a preliminary design of the ZLD process. The selection of the optimal ratio between exhaust gases and brine mass flow rates is analyzed, as well as variation in inlet salinity and temperatures. Furthermore, the water which could be recovered from effluents, at the same time that the heat of exhaust gases from SMGT is harvested, is quantified. Lastly, according to the results obtained, a preliminary design of a 10 kWe rated power SMGT system, coupled to Reverse Osmosis (RO) and ZLD units, is proposed.Ministerio de Ciencia, Innovación y Universidades - Agencia Estatal de Investigación (AEI) - Fondo Europeo de Desarrollo Regional (FEDER) RTI2018-102196-B-100FEDER - Interreg Atlantic Area (EERES4WATER project) EAPA 1058/2018Universidad de Sevilla 2019/0000035

Effect of fatty acid composition of methyl and ethyl esters on the lubricity at different humidities

Lubricity of individual fatty acid methyl or ethyl esters and biodiesel fuels has been measured using a high frequency reciprocating rig (HFRR). Tests have been carried out varying the ambient humidity to assess the effect of this parameter on the lubricity of the fuels. The European standard proposes a single humidity correction factor for all the fuels, regardless their composition. It has been proved in this study that this factor is not constant and it depends on the fuel composition. For this reason two different correlations have bee n proposed for the estimation of the humidity correction factor and normalized wear scar as a function of different fuel compositional characteristics. The influence of the water content on the lubricity and the relationship between humidity and water content of the fuel has been studied revealing that the effect of the air humidity is an indirect effect of the hygroscopy of the fuel