On the optimal demand-side management in microgrids through polygonal composition

This article presents a novel methodology for energy management in microgrids focused on the demand side. It is inspired by the Tangram puzzle. The energy demand and production profiles are represented by polygons and managed through computational geometry. Therefore, an optimization problem is defined to place n energy demand profiles (pieces) to cover the total energy production profile (target shape). The optimization problem is addressed with a genetic algorithm. It tries to calculate the optimal positions of the polygons of the demands covering the maximum energy production. Since the referred production comes from renewable energy sources in the microgrid, this method allows reducing both the consumption of fossil fuels and energy bills

Nodal Gap in Fe-Based Layered Superconductor LaO_0.9F_{0.1-delta}FeAs Probed by Specific Heat Measurements

We report the specific heat measurements on the newly discovered Fe-based layered superconductor LaO_0.9F_{0.1-delta}FeAs with the onset transition temperature T_c \approx 28 K. A nonlinear magnetic field dependence of the electronic specific heat coefficient gamma(H) has been found in the low temperature limit, which is consistent with the prediction for a nodal superconductor. The maximum gap value Delta_0 \approx 3.4$\pm$0.5 meV was derived by analyzing gamma(H) based on the d-wave model. We also detected the electronic specific heat difference between 9 T and 0 T in wide temperature region, a specific heat anomaly can be clearly observed near T_c. The Debye temperature of our sample was determined to be about 315.7 K. Our results suggest an unconventional mechanism for this new superconductor.Comment: 4 pages, 4 figures,Corrected typo

Kerr black hole quasinormal frequencies

Black-hole quasinormal modes (QNM) have been the subject of much recent attention, with the hope that these oscillation frequencies may shed some light on the elusive theory of quantum gravity. We compare numerical results for the QNM spectrum of the (rotating) Kerr black hole with an {\it exact} formula Re$\omega \to T_{BH}\ln 3+\Omega m$, which is based on Bohr's correspondence principle. We find a close agreement between the two. Possible implications of this result to the area spectrum of quantum black holes are discussed.Comment: 3 pages, 2 figure

Influence of Rotations on the Critical State of Soil Mechanics

The ability of grains to rotate can play a crucial role on the collective behavior of granular media. It has been observed in computer simulations that imposing a torque at the contacts modifies the force chains, making support chains less important. In this work we investigate the effect of a gradual hindering of the grains rotations on the so-called critical state of soil mechanics. The critical state is an asymptotic state independent of the initial solid fraction where deformations occur at a constant shear strength and compactness. We quantify the difficulty to rotate by a friction coefficient at the level of particles, acting like a threshold. We explore the effect of this particle-level friction coefficient on the critical state by means of molecular dynamics simulations of a simple shear test on a poly-disperse sphere packing. We found that the larger the difficulty to rotate, the larger the final shear strength of the sample. Other micro-mechanical variables, like the structural anisotropy and the distribution of forces, are also influenced by the threshold. These results reveal the key role of rotations on the critical behavior of soils and suggest the inclusion of rotational variables into their constitutive equations.Comment: 9 pages, 8 figures, Accepted for publication in Computer Physics Communication

Synthesis and Characterization of Tin Niobates

The synthesis and the structural characterization of tin niobates Sn11x Nb2 O61x , x50.0, 0.5, and 1.0, are reported. The materials have been characterized by bulk chemical analysis, single-crystal and powder X-ray di4raction, and 119Sn Mossbauer and 93Nb and 119Sn solid-state NMR spectroscopies. SnNb2 O6 is a synthetic analog of the rare mineral foordite. Red Sn2 Nb2 O7 crystallizes in a pyrochlore structure with a510.5386 A. 119Sn Mossbauer reveals the presence of both Sn(II) and Sn(IV) in pyrochlore samples. 119Sn MAS NMR spectroscopy supports the presence in synthetic foordite of Sn(II) in eight-fold coordination. The six-coordinated Sn(IV) and eight-coordinated Sn(II) 119Sn MASNMRresonances are not resolved in the Sn2 Nb2 O7 pyrochlore spectrum. 93Nb NMR indicates a fairly distorted local environment for niobium in synthetic foordite, much more so than in the Sn2 Nb2 O7 pyrochlore.N/

Bubble, Bubble, Flow and Hubble: Large Scale Galaxy Flow from Cosmological Bubble Collisions

We study large scale structure in the cosmology of Coleman-de Luccia bubble collisions. Within a set of controlled approximations we calculate the effects on galaxy motion seen from inside a bubble which has undergone such a collision. We find that generically bubble collisions lead to a coherent bulk flow of galaxies on some part of our sky, the details of which depend on the initial conditions of the collision and redshift to the galaxy in question. With other parameters held fixed the effects weaken as the amount of inflation inside our bubble grows, but can produce measurable flows past the number of efolds required to solve the flatness and horizon problems.Comment: 30 pages, 8 figures, pdftex, minor corrections and references adde

Non-stoichiometric mixed lead and tin niobates

Novel non-stoichiometric mixed lead and tin niobates with the pyrochlore structure have been synthesized via a solid-state route. The materials have been characterized by bulk chemical analysis, single-crystal and powder X-ray diffraction, 207Pb, 119Sn and 93Nb (single and triple quantum) solid-state NMR spectroscopy. The structures of the new non-stoichiometric mixed lead–tin niobate pyrochlore compounds have been Rietveld refined in the cubic system, space group Fd-3m. The steroactivity of the Sn(II) free electron pair leads to the general formula (Sn1.6−xPbx)(Nb2−ySny)O6.6−0.5y, where x (0–1.6) is the Pb(II) and y (0–0.34) is the Sn(IV) contents. 207Pb, 119Sn and (in particular) 93Nb NMR support the isomorphous substitution of tin for lead in the compounds studied. 93Nb triple-quantum magic-angle spinning NMR spectroscopy show that the materials contain, at least, two distinct niobium sites, in a 2:1 population ratio, which may be associated with different sampleinfo:eu-repo/semantics/publishedVersio

Temperature and Polarization Patterns in Anisotropic Cosmologies

We study the coherent temperature and polarization patterns produced in homogeneous but anisotropic cosmological models. We show results for all Bianchi types with a Friedman-Robertson-Walker limit (i.e. Types I, V, VII$_{0}$, VII$_{h}$ and IX) to illustrate the range of possible behaviour. We discuss the role of spatial curvature, shear and rotation in the geodesic equations for each model and establish some basic results concerning the symmetries of the patterns produced. We also give examples of the time-evolution of these patterns in terms of the Stokes parameters $I$, $Q$ and $U$.Comment: 24 pages, 7 Figures, submitted to JCAP. Revised version: numerous references added, text rewritten, and errors corrected

Identificación de genes relacionados con la tolerancia a la sequía en 41 variedades de quinua (Chenopodium quinoa Willd)

The objective of the research was to identify the genes related to drought tolerance in quinoa. For this, 41 varieties of Chenopodium quinoa Willd were evaluated with six repetitions; in the flowering stage, three pots/material, of each variety, were randomly selected to be induced to total drought for two weeks, resuming irrigation after that period, the other three were the control. From day 27 after sowing, the chlorophyll level was measured and classified as tolerant or susceptible to drought, based on its chlorophyll content index (CCI). For the identification of genes, leaf samples of three varieties were taken (Red head, Salcedo INIA and Kankolla 1). RNA Extraction was performed using reagent® TRI reagent and for the transcriptome sequencing the Ilumina platform was used. 26 genes were identified in the three varieties of quinoa, but in the drought tolerant varieties; three of them are regulated upwards when exposed to drought and five genes (AUR62037809, AUR62000271, AUR62037807, AUR62042825 AUR62009791) have a change in their pattern of expression as a result of drought exposure.El objetivo de la investigación fue identificar los genes relacionados con la tolerancia a la sequía en la quinua. Para ello, se evaluaron 41 variedades de Chenopodium quinoa Willd con seis repeticiones; en la etapa de floración, se seleccionaron al azar tres macetas/material, de cada variedad, para ser inducidas a sequía total por dos semanas, reanudándose el riego después de ese periodo, las otras tres fueron el control. A partir del día 27 después de la siembra, se midió el nivel de clorofila y se clasificó como tolerante o susceptible a la sequía, en función de su índice de contenido clorofila (ICC). Para la identificación de genes se tomaron muestras de hoja de tres variedades (Red head, Salcedo INIA y Kankolla 1). La Extracción del ARN se realizó usando el reactivo reagent® TRI y para el secuenciamiento de transcriptomas se utilizó la plataforma de Ilumina. Se identificaron 26 genes en las tres variedades de quinua, pero en las variedades tolerantes a la sequía; tres de ellos son regulados al alza ante la exposición a la sequía y cinco genes (AUR62037809, AUR62000271, AUR62037807, AUR62042825 AUR62009791) tienen un cambio en su patrón de expresión como consecuencia de la exposición a la sequía

NORIT project: The incidence of Norway lobster (Nephrops norvegicus L.) emergence activity rhythms on its population assessment

Sardà, Francisco ... et. al.-- Marine Technology Workshop (Martech05), 17-18 November 2005, Vilanova i la Geltrú, Barcelona.-- 1 pageThe Norway lobster, Nephrops norvegicus (L.) is a decapod crustacean inhabiting complex burrow systems in muddy continental shelves and slopes on the European waters of the Atlantic Ocean and Mediterranean Sea. This species is object of an important multispecific fishery in the Mediterranean, showing signs of overexploitation. Animals of this species show marked behavioural rhythms of emergence in the field. Emergence is performed under an optimum light intensity whose timing varies at different depths depending upon light penetration into the water column and hence upon the sun position. Present data indicate that not all the individuals emerge from their burrows at a circadian basis. [...]Peer Reviewe