Noise-induced forced synchronization of global variables in coupled bistable systems

We analyze the noise-induced synchronization between a collective variable characterizing a complex system with a finite number of interacting bistable units and time-periodic driving forces. A random phase process associated to the collective stochastic variable is defined. Its average phase frequency and average phase diffusion are used to characterize the phenomenon. Our analysis is based on numerical solutions of the corresponding set of Langevin equations.Ministerio de Educación y Ciencia FIS2005-0288

Phase Composition and Transport Properties of oxide ion conductors based on Sr1-xKxGeO3-x/2

Oxide ion conductors have been increasingly studied because of their potential applications in different electrochemical devices, such as, oxygen sensors, membranes for oxygen separation and components of fuel cells. Solid Oxide Fuel Cells (SOFCs) are electrochemical devices that operate at high temperatures, 600-1000 ºC, with higher efficiency for electrical generation than conventional systems based on fuel combustion. The high operating temperatures of the SOFC is mainly due to the limited ionic conductivity of the electrolyte. Zr0.84Y0.16O1.92 (YSZ) is the electrolyte most widely used in commercial systems due to its high stability and oxide ion conductivity at elevated temperatures (900-1000 ºC). However, there is a great interest in the development of devices with lower operation temperatures (600-800 ºC) to overcome collateral problems like difficulties in cell sealing or shorter lifetime of the components caused by the high operation temperature of YSZ. The high oxide ion conductivities recently reported in Na- and K-doped strontium silicates and germanates, make them potentially suitable for SOFC electrolytes. In this work, the structure, microstructure and electrical properties of Sr1-xKxGeO3-x/2 (x = 0.0, 0.1, 0.15 and 0.2) compounds have been re-investigated. The materials have been prepared by conventional ceramic and freeze-drying precursor methods. Different phases are stabilized depending on the synthetic method and the sintering temperature. Samples prepared by freeze-drying at 700 ºC exhibit a triclinic structure, which transforms to a mixture of monoclinic and trigonal related phases on heating at 1000 ºC. The presence of some broad diffractions peaks, which are not fitted in the Rietveld analysis, indicates the existence of an amorphous or low-crystalline phase (ACn) that have been quantified by an external standard procedure (G-factor approach). The homogeneity and chemical composition of the samples were checked by scanning electron microscopy combined with energy dispersive spectroscopy (EDX). The total conductivity of these materials was studied by impedance spectroscopy.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

Territorial impacts of sea-level rise in marsh environments. The case of the Bay of Cádiz, Spain

How can sea-level rise affect territory? Has territorial planning adjusted to this new situation? This paper analyses the possible ramifications of changes in tidal recurrence over the course of this century in a potentially vulnerable marsh environment, such as the Bay of Cádiz, in southern Spain, where sea-level rise is already a fact. For that purpose, the regionalisation criterion is used as a basis for adjusting the magnitude of global problems to subregional scale. Geographic information systems are applied to portray the forecasted territorial changes according to the RCP4.5 and RCP8.5 scenarios presented by the Intergovernmental Panel on Climate Change (IPCC) for the years 2050 and 2100. Projections of sea-level rise show that the tide is travelling farther inland, not just invading unoccupied areas of marshes and beaches but also reaching urban and productive areas. Estimates indicate that the floodable area could expand by more than 20% in 2050, with a further 2,000 ha of flooded areas added in 2100 for either of the two scenarios used. The occurrence of these changes, regardless of the model used, would therefore entail an alteration of the environmental, social, cultural and economic values and elements of the Bay of Cádiz, with the Natural Park being the most affected area. In response to these consequences, the need to apply the resulting projections to other variables is insisted on, with a view to introducing territorial management tailored to this new and already present reality. Application of the regionalisation criterion to study repercussions of the climate crisis in the Bay of Cádiz could serve as a precedent for the development of adaptation strategies in other marsh environments at subregional or local level

Ce0.8Gd0.2O2‐δ / La0.6Sr0.4CoO3 Heterostructures prepared by pulsed laser deposition

Oxide interfaces have received greater attention due to the possibility to obtain properties that are very different from bulk materials. Due to the wide variety of electronic and ionic phenomena than can be detected at the interfaces, such materials have many technological applications [1]. Attention is being drawn to oxide heterostructures, a new family of artificial materials where electronic and ionic properties can be modulated at the interfaces by varying the characteristics of the layers [2, 3]. Slight variations in the near anionic-cationic order might take place if there exists strained interfaces. The interest in multilayared heterostructures derives from the mobility deffects and the space-charge-zone effects at the interfaces. In addition, a new degree of freedom related to the capacitive and resistive contributions is provided as a consequence of the size effects of these artificial structures. In the present work, for the first time, we investigate the structure, microstructure and electrical properties of a new family of heterostructured materials with alternated thin layers of La0.6Sr0.4CoO3 (LSC) and Ce0.8Gd0.2O2-δ (CGO) deposited by pulsed laser deposition on (110) NdGaO3 (NGO) single crystal substrates. In order to evaluate the interfacial contribution to ionic-electronic conductivity and know what is actually happens at the interface of MIECs, different heterostructures were prepared by varying both the number of bilayers (N) and the total thickness of the samples (N = 2 and 5; and the thickness were 50, 100 and 300 nm).Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tec

Novel microstructural strategies to enhance the electrochemical performance of La0.8Sr0.2MnO3-δ cathodes

Solid oxide fuel cells (SOFCs) are one of the most efficient technologies for direct conversion of fuels to electricity. La0.8Sr0.2MnO3-δ (LSM) is the cathode material most widely used in SOFCs [1], however, LSM exhibits high activation energy for oxygen reduction reaction (ORR) and low ionic conductivity, which limits its application at reduced temperatures. In this material the electrochemically active reaction sites are restricted to the triple-phase boundary (TPB) near the electrolyte/electrode interface, where the electrolyte, air and electrode meet. Different strategies have been investigated to enlarge the TPB area of LSM, such as the production of nanocrystalline powders by precursor routes, preparation of composites by infiltration methods and thin films [2-4]. Here we present and compare innovative procedures to extend the TPB of LSM in contact with yttria-stabilized zirconia electrolyte: i) nanocrystalline LSM films deposited by spray-pyrolysis on polished YSZ electrolyte; ii) the addition of polymethyl methacrylate microspheres as pore formers during the spray-pyrolysis deposition to further increase the porosity of these films and (iii) the deposition of LSM by spray-pyrolysis on porous backbones of Zr0.84Y0.16O1.92 (YSZ), Ce0.9Gd0.1O1.95 (CGO) and Bi1.5Y0.5O3- (BYO) electrolytes previously fixed onto the YSZ electrolyte. The most remarkable peculiarity of this novel preparation method, compared to the traditional impregnation, is the formation of LSM thick film of 500 nm on the electrode surface (Fig. 1), which improves the electrical conductivity of the composite cathode. Thus, the optimization of this novel method would be an alternative to the classical infiltration with several advantages for the industry of planar SOFCs allowing the deposition of a wide variety of ceramic films over large areas with more uniform distribution of the catalyst, lower cost and only one deposition step is required to form the electrode. The morphology and electrochemical performance of the electrode have been investigated by scanning electron microscopy and impedance spectroscopy. Very low values of area specific resistance were obtained ranging from 1.4 cm2 for LSM deposited on polished YSZ to 0.06 cm2 for LSM deposited onto BYO backbone at a measured temperature of 650 ºC. This electrodes exhibit high performance even after annealing at 950 ºC making them interesting for applications at intermediate temperatures.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

Solid Oxide Fuel Cells based on Lanthanum Tungstates Electrolytes

Lanthanum tungstate with composition La27W4NbO55- (LWNO) has been tested as proton conductor electrolyte for Solid Oxide Fuel Cells (SOFCs). For this purpose, different electrodes and composite electrodes are considered, including: La0.8Sr0.2MnO3-, La0.6Sr0.4Co1-xFexO3-, La0.5Sr0.5Cr0.5Mn0.5O3-, SrFe0.75Nb0.25O3- and NiO. Chemical compatibility between the cell components is investigated by X-ray powder diffraction (XRPD) and energy dispersive spectroscopy (EDS). Furthermore, area specific resistance (ASR) of the different electrodes is determined in symmetrical cells by impedance spectroscopy. XRPD and EDS analysis do not reveal significant bulk reactivity between most of these electrodes and LWNO electrolyte in the typical operating temperature range of a SOFC (600-900 ºC). However, minor interdiffusion of elements at the electrolyte/electrode interface affects both the ohmic losses and electrode polarization of the cells. ASR values are significantly improved by using a buffer layer of Ce0.8Gd0.2O1.9, between the electrolyte and electrode materials, to prevent reactivity. A single cell with 350 µm thick electrolyte, NiO-Ce0.8Gd0.2O1.9 anode and La0.6Sr0.4Co0.8Fe0.2O3- cathode, generates maximum power densities of 140 and 18 mWcm-2 at 900 and 650 ºC, respectively.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

Compatibility and performance of SOFCs based on lanthanum tungstates

Rare-earth tungstates with general composition “Ln6WO12” have attracted great attention in last few years due to their relatively high mixed proton-electron conductivity [1, 2]. One of the main ad-vantages of these electrolytes, compared to the traditional perovskites based on BaCeO3, is that they exhibit high tolerance towards CO2 and H2S environments. Therefore, this material is a potential electrolyte for proton conducting solid oxide fuel cells (PC-SOFC). In this work, the lanthanum tungstate with com-position La27W4NbO55-δ (LWNO) has been tested as proton conductor electrolyte [3]. For this purpose, different electrodes and composite electrodes have been considered, including: La0.8Sr0.2MnO3-δ, La0.6Sr0.4Co1-xFexO3-δ, La0.5Sr0.5Cr0.5Mn0.5O3-δ, SrFe0.75Nb0.25O3-δ and NiO. Chemical compatibility between the cell compo-nents is investigated by X-ray powder diffraction (XRPD) and energy dispersive spectroscopy (EDS). Furthermore, area specific resistance (ASR) of the different electrodes is determined in symmetrical cells by impedance spectroscopy. XRPD and EDS analysis do not reveal significant bulk reactivity between most of these electrodes and LWNO electrolyte in the typical operating temperature range of a SOFC (600-900 ºC). However, minor interdiffusion of elements at the electrolyte/electrode interface affects both the ohmic losses and electrode polarization of the symmetric cells. ASR values are significantly improved by using a buffer layer of Ce0.8Gd0.2O1.9, between the electrolyte and electrode materials, to prevent reactivity. A single cell with 350 µm thick electrolyte, NiO-Ce0.8Gd0.2O1.9 anode and La0.6Sr0.4Co0.8Fe0.2O3-δ cathode, generates maximum power densities of 140 and 18 mWcm-2 at 900 and 650 ºC, respectively. Hence, lanthanum tungstates could be competitive proton conductors for PC-SOFCs with similar performance to those based on BaZrO3 if thin film electrolytes are used.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

Supersymmetric probes in warped AdS(6)

We consider defects in 5d field theories corresponding to higher-rank generalizations of the ENf+1 theories; holographically dual to the Brandhuber-Oz background in type I’ String Theory. We concentrate on codimension 2 and 1 defects, corresponding, respectively, to 3d and 4d defect Quantum Field Theories. We study holographically such defect theories by considering supersymmetric probe D4- and D6-branes in the AdS6, whose fluctuations allow us to study the spectrum of mesonic operators of the defect theories. In the case of D4-branes, we also consider wrappings in the internal space which can be regarded as generalizations of the configurations capturing the antisymmetric Wilson loopJ. M. P. and A. V. R. are funded by the Spanish grant FPA2017-84436-P, by Xunta de Galicia (GRC2013-024), by FEDER and by the Maria de Maeztu Unit of Excellence MDM-2016-0692. J. M. P. is supported by the Spanish FPU fellowship FPU14/06300. D.R-G is partially supported by the Spanish government grant MINECO-16-FPA2015-63667-P, as well as by the Principado de Asturias through the grant FC-GRUPIN-IDI/2018/000174S

Total replacement of recycled aggregate and treated wastewater: concrete recycling in extremis

Million tons of construction and demolition waste (CDW) are generated every year around the world, and most of them are not adequately disposed, generating significant pollution on water, soil and air. Additionally, the use of freshwater in industrial processes, such as the production of cement, concrete manufacturing and curing for newly-built structures; has damaged the health of our freshwater ecosystems, reducing their volume and hindering their natural cycle of renovation. Therefore, the incorporation of recycled aggregate (RA) and treated wastewater (TW) as substitutes for the usual aggregates (UA) and freshwater, could generate significant environmental benefits. In this research, a comparative analysis of the experimental results of the properties of fresh and hardened concrete with different replacement percentage of UA for RA, is presented; and as an innovation the use TW. The results show that, regardless of the replacement percentage and use of treated wastewater, a concrete with RA and TW (recycled concrete in extremis, CRiE) had a satisfactory and acceptable or equivalent performance, not differing significantly from the performance of conventional concrete (CC), confirming that the use of RA for concrete building is feasible.Peer ReviewedPostprint (published version

Los criterios de localización en la industria auxiliar del automóvil de Galicia

Texto dispoñible en galego e españolNos últimos anos a actividade industrial experimentou fortes transformacións como consecuencia da evolución seguida en plans como o tecnolóxico, o laboral ou o organizativo. Especialmente relevantes foron as repercusións no ámbito socioeconómico derivadas dos episodios de "cambio industrial". Unha das máis significativas, pola súa notoriedade, afectaría á distribución da industria no espacio. Habitualmente, eses episodios van acompañados de novas xerarquías nos factores de localización, o que dá lugar a novas pautas e criterios nas decisións de emprazamento das empresas. Polo tanto, asistimos, en primeiro lugar, ó auxe da grande empresa multinacional como elemento definitorio de tales pautas e, posteriormente, ó recoñecemento da capacidade de determinadas técnicas de xestión que deben influír no proceso localizador da industria. O sector do automóbil tivo un papel destacado e amosou unha gran capacidade dinamizadora. Técnicas de xestión como o xusto a tempo, a calidade total ou o desenvolvemento compartido afectaron profundamente ás relacións empregador-empregado e provedor-cliente, sinalando novas necesidades en materia de localización. Debido á transcendencia do sector na economía galega e ó feito de atoparse fortemente concentrado, pareceunos interesante determinar cáles son os factores que guían a industria auxiliar á hora de localizarse. Con iso tratariamos de contrastar se esa concentración pode responder á xeneralización do XAT como un estándar de xestión dentro do sector, ou si, pola contra, non é máis có resultado da casualidade ou do efecto das forzas aglutinadoras clásicasIn last years, industrial activity has experienced strong transformations as a result of the evolution in planes like the technological, labor or the organizational one. Repercussions in the socioeconomic scope derived from the episodes of industrial change have been very important. One of them, perhaps the most significant by its notoriety, would affect to the distribution of the industry in the space. Habitually, such episodes embrace new hierarchies in locational factors, giving rise to new guidelines and criteria in location decisions of enterprises. Thus, we have attended, first, to the height of the great multinational company like distinctive element of such guidelines, and later, to the recognition of the capacity of some management techniques to affect process of industrial location. In this sense, automobile manufacture has had an outstanding paper, showing a great revitali-zing capacity. So, techniques like Just in time, Total Quality or Shared Development affected deeply to employer-used and supplier-client relations, projecting new necessities in the field of location. Importance of the sector in the Galician economy and the fact to be strongly concentrated, makes interesting to determine wich are the factors that guide the ancillary industry at the time of being located. In fact, we would try to contrast if concentration may be the response to gene-ralization of JIT like a standard of management within the sector, or, by opossition, it´s only the result of the chance or the effect of the classic agglomerative forcesEn los últimos años la actividad industrial ha experimentado fuertes transformaciones como consecuencia de la evolución seguida en planos como el tecnológico, el laboral o el organizativo. Especialmente relevantes han sido las repercusiónes en el ámbito socioeconómico derivadas de los episodios de "cambio industrial". Una de las más significativas, por su notoriedad, afectaría a la distribución de la industria en el espacio. Habitualmente, tales episodios van acompañados de nuevas jerarquías en los factores de localización, dando lugar a nuevas pautas y criterios en las decisiones de localización de las empresas. Así, hemos asistido, en primer lugar, al auge de la gran empresa multinacional como elemento definitorio de tales pautas y, posteriormente, al reconocimiento de la capacidad de determinadas técnicas de gestión que deben influir en el proceso localizador de la industria. El sector del automóvil ha tenido un papel destacado, mostrando una gran capacidad dinamizadora. Técnicas de gestión como el justo a tiempo, la calidad total o el desarrollo compartido han afectado profundamente a las relaciones empleador-empleado y proveedor-cliente, señalando nuevas necesidades en materia de localización. Debido a la trascendencia del sector en la economía gallega y al hecho de encontrarse fuertemente concentrado, nos ha parecido interesante determinar cuáles son los factores que guían la industria auxiliar a la hora de localizarse. Con ello trataríamos de contrastar si esa concentración puede responder a la generalización del JAT como un estándar de gestión dentro del sector, o si, por el contrario, no es más que el resultado de la casualidad o del efecto de las fuerzas aglomerativas clásicasS