Assessment of the cooling potential of an indoor living wall using different substrates in a warm climate

The use of vertical greenery systems in buildings is becoming very popular as they provide several benefits. In this work, the influence of an indoor living wall on the temperature and humidity in a hall inside the School of Agricultural Engineering (University of Seville) was studied. Four different substrates, Geotextile, Epiweb, Xaxim and coconut fibre, were used to grow the plants in order to assess their performance. Several parameters such as temperature, humidity, plant growth or water consumption were monitored and analyzed during a 4-month period. The cooling effect of the living wall was proven, with an average reduction of 4°C over the room temperature though maximum decrements of 6°C have been observed in warmer conditions. Higher air humidity levels were experienced near the living wall, increasing the overall humidity in the room. All the substrates tested were suitable for plant growing and their behaviour was similar. Geotextile showed the best cooling capacity but higher water consumption, coconut fibre presented degradation problems and Epiweb performance was the poorest. Therefore, these systems have been proven to be very useful and interesting for warm indoor environments due to the cooling effect observed in addition to their bio-filtration capacity and the aesthetic component

Stochastic quantization of Yang-Mills field theory: Gauge-fixing parameter dependence and equilibrium limit

We calculate, in the framework of stochastic quantization, the one-loop-divergent part of the gluon self-energy and the triple-gluon vertex of pure Yang Mills field theory, with an arbitrary choice of the stochastic gauge-fixing parameter. This allows us to check that the strong conditions imposed by renormalizability are satisfied up to one-loop order. We compare our results with those corning from the Faddeev Popov theory and discuss the relationship between both approaches in the equilibrium limit

A statics-dynamics equivalence through the fluctuation-dissipation ratio provides a window into the spin-glass phase from nonequilibrium measurements

We have performed a very accurate computation of the non-equilibrium fluctuation- dissipation ratio for the 3D Edwards-Anderson Ising spin glass, by means of large-scale simulations on the special-purpose computers Janus and Janus II. This ratio (computed for finite times on very large, effectively infinite, systems) is compared with the equilibrium probability distribution of the spin overlap for finite sizes. Our main result is a quantitative statics-dynamics dictionary, which could allow the experimental exploration of important features of the spin-glass phase without requiring uncontrollable extrapolations to infinite times or system sizes

Matching microscopic and macroscopic responses in glasses

We first reproduce on the Janus and Janus II computers a milestone experiment that measures the spinglass coherence length through the lowering of free-energy barriers induced by the Zeeman effect. Secondly, we determine the scaling behavior that allows a quantitative analysis of a new experiment reported in the companion Letter [S. Guchhait and R. Orbach, Phys. Rev. Lett. 118, 157203 (2017)]. The value of the coherence length estimated through the analysis of microscopic correlation functions turns out to be quantitatively consistent with its measurement through macroscopic response functions. Further, nonlinear susceptibilities, recently measured in glass-forming liquids, scale as powers of the same microscopic length

Aplicaciones de la teoría de funciones de Green en sistemas de muchas partículas : transiciones nucleares con [incremento de] B [distinto de] 0, efectos de superficie

Tesis Univ. Complutense de Madrid, 1985.Depto. de Física TeóricaFac. de Ciencias FísicasTRUEProQuestpu

Hydrogen-air mixing-layer ignition at temperatures below crossover

This paper addresses ignition histories of diffusion flames in unstrained hydrogen-air mixing layers for initial conditions of temperature and pressure that place the system below the crossover temperature associated with the second explosion limit of hydrogen–oxygen mixtures. It is seen that a two-step reduced chemical-kinetic mechanism involving as main species H₂, O₂, H₂O, and H₂O₂, derived previously from a detailed mechanism by assuming all radicals to follow a steady-state approximation, suffices to describe accurately the ignition process. The strong temperature sensitivity of the corresponding overall rates enables activation-energy asymptotics to be employed for the analysis, following the ideas developed for mixing-layer ignition by Liñán and Crespo in 1976 on the basis of one-step Arrhenius model chemistry. When the initial temperatures of both reactants differ by a relative amount that is of the order of or smaller than the ratio of this temperature to the effective activation temperature, the chemical reaction is seen to occur at a significant rate all across the mixing layer. The ignition time is then determined as a thermal runaway in a parabolic problem describing the evolution of the temperature increment and the H₂O₂ concentration, with local accumulation, chemical reaction, and transverse convection and diffusion, all being important. By way of contrast, when the air side is sufficiently hotter than the hydrogen side, as often occurs in applications, ignition occurs in a thin layer close to the air-side boundary, enabling a simplified description to be developed in which the ignition time is determined by analyzing the existence of solutions to a two-point boundary-value problem involving quasi-steady diffusion–reaction ordinary differential equations.This work was supported by the US AFOSR Grant # FA9550-12-1-0138, by the Comunidad de Madrid through Project # P2009/ENE-1597, and by the Spanish MCINN through Project #CSD2010-00011

Nature of the spin-glass phase at experimental length scales

We present a massive equilibrium simulation of the three-dimensional Ising spin glass at low temperatures. The Janus special-purpose computer has allowed us to equilibrate, using parallel tempering, L = 32 lattices down to T ≈ 0.64Tc. We demonstrate the relevance of equilibrium finite-size simulations to understand experimental non-equilibrium spin glasses in the thermodynamical limit by establishing a time-length dictionary. We conclude that non-equilibrium experiments performed on a time scale of one hour can be matched with equilibrium results on L ≈ 110 lattices. A detailed investigation of the probability distribution functions of the spin and link overlap, as well as of their correlation functions, shows that Replica Symmetry Breaking is the appropriate theoretical framework for the physically relevant length scales. Besides, we improve over existing methodologies to ensure equilibration in parallel tempering simulations

Naturación urbana y jardinería vertical: de las fachadas verdes a los muros vegetales

En las últimas décadas, las urbes están creciendo considerablemente, dedicándose un porcentaje cada vez más elevado a edificaciones. Se prevé que en el periodo entre 2000 y 2030, la población urbana del mundo habrá aumentado un 72%, mientras que la superficie de las zonas edificadas donde viven 100.000 o más personas podría aumentar en un 175%. En este difícil contexto, la aplicación de los principios de sostenibilidad en las áreas urbanas se erige como uno de los mayores retos de las políticas ambientales del siglo XXI. Su éxito dependerá en gran medida del modelo de ciudad a desarrollar, particularmente en lo que se refiere a la relación entre desarrollo urbano y consumo de recursos ambientales

A statics-dynamics equivalence through the fluctuation-dissipation ratio provides a window into the spin-glass phase from nonequilibrium measurements

The unifying feature of glass formers (such as polymers, supercooled liquids, colloids, granulars, spin glasses, superconductors, ...) is a sluggish dynamics at low temperatures. Indeed, their dynamics is so slow that thermal equilibrium is never reached in macroscopic samples: in analogy with living beings, glasses are said to age. Here, we show how to relate experimentally relevant quantities with the experimentally unreachable low-temperature equilibrium phase. We have performed a very accurate computation of the non-equilibrium fluctuation-dissipation ratio for the three-dimensional Edwards-Anderson Ising spin glass, by means of large-scale simulations on the special-purpose computers Janus and Janus II. This ratio (computed for finite times on very large, effectively infinite, systems) is compared with the equilibrium probability distribution of the spin overlap for finite sizes. The resulting quantitative statics-dynamics dictionary, based on observables that can be measured with current experimental methods, could allow the experimental exploration of important features of the spin-glass phase without uncontrollable extrapolations to infinite times or system sizes

Multidisciplinary Education for New Landscape Engineering Concepts using Problem-Based Collaborative Learning. A Case Study in Spain

Problem-based learning (PBL) is widely regarded as a successful educational method. In Spain, most engineering degrees are still based mainly on old style lecture classes where a great deal of information is given to the students. This work assesses the introduction of a PBL strategy as a complement to traditional engineering education. The instructors’ and students’ attitudes towards its implementation are studied. A new approach has been proposed for the PBL strategy: instead of a single problem, a chain of problems was developed that could be solved in a collaborative environment. Results from the experience showed a high level of student acceptance. Response to the PBL initiative was found to be positive both for instructors and students, though lack of time, difficulties in evaluations and an increase in students’ and teachers’ workloads were the main disadvantages. Compared with traditional engineering curricula, the mixed traditional–PBL model appears to inspire a higher degree of involvement in study activities where on-line learning tools played an important role