Dark Matter & Dark Energy from a single scalar field: CMB spectrum and matter transfer function

The dual axion model (DAM), yielding bot DM and DE form a PQ-like scalar field solving the strong CP problem, is known to allow a fair fit of CMB data. Recently, however, it was shown that its transfer function exhibits significant anomalies, causing difficulties to fit deep galaxy sample data. Here we show how DAM can be modified to agree with the latter data set. The modification follows the pattern suggested to reconcile any PQ-like approach with gravity. Modified DAM allows precise predictions which can be testable against future CMB and/or deep sample data.Comment: 15 pages, 8 figures, accepted for publication in JCA

assessment of thermal stress in a street canyon in pedestrian area with or without canopy shading

Abstract Urban areas are characterized by a plurality of microclimates given by the diversity of morphologies, optical and radiative properties, solar access and air circulation in different street canyons. For these reasons, beyond strategies at urban scale, mitigation needs to be addressed at district or even at urban canyon scale, just like the design of buildings. Among different options, canopy shading has been proposed in several urban contexts, and to assess the impact of this mitigation technique on air temperature and outdoor thermal comfort conditions we performed numerical simulations for a north-south oriented urban canyon with high solar access (height to width ratio equal to 0.18) in the climate context of Milano (Italy)

Transparent Multilayer ETFE Panels for Building Envelope: Thermal Transmittance Evaluation and Assessment of Optical and Solar Performance Decay due to Soiling

AbstractThis paper is divided in two sections. The first section present the measurement and evaluation of soiling effects of spectral light and solar transmittance decay of Ethylene Tetrafluoroethylene Copolymer (ETFE) membranes after three and six months of exposure in Milano city outdoor urban conditions, with different tilt and orientation. The obtained values where use to compute thermal and solar properties of a multilayer ETFE panel.The second section presents the results of an experimental campaign for measuring thermal transmittance of a non-pneumatic and non-cushion shape double layer ETFE sample panel realized with two membranes parallel to each other and tensioned on a frame. The thermal transmittance measurement reflects ISO 9869 measurement approach combined with the use of a thermographic camera to evaluate surface temperatures over the sample panel

Transparent multilayer ETFE panels for building envelope : thermal transmittance evaluation and assessment of optical and solar performance decay due to soiling.

Abstract This paper is divided in two sections. The first section present the measurement and evaluation of soiling effects of spectral light and solar transmittance decay of Ethylene Tetrafluoroethylene Copolymer (ETFE) membranes after three and six months of exposure in Milano city outdoor urban conditions, with different tilt and orientation. The obtained values where use to compute thermal and solar properties of a multilayer ETFE panel. The second section presents the results of an experimental campaign for measuring thermal transmittance of a non-pneumatic and non-cushion shape double layer ETFE sample panel realized with two membranes parallel to each other and tensioned on a frame. The thermal transmittance measurement reflects ISO 9869 measurement approach combined with the use of a thermographic camera to evaluate surface temperatures over the sample panel

Scalar field-perfect fluid correspondence and nonlinear perturbation equations

The properties of dynamical Dark Energy (DE) and, in particular, the possibility that it can form or contribute to stable inhomogeneities, have been widely debated in recent literature, also in association to a possible coupling between DE and Dark Matter (DM). In order to clarify this issue, in this paper we present a general framework for the study of the nonlinear phases of structure formation, showing the equivalence between two possible descriptions of DE: a scalar field \phi self-interacting through a potential V(\phi) and a perfect fluid with an assigned negative equation of state w(a). This enables us to show that, in the presence of coupling, the mass of DE quanta may increase where large DM condensations are present, so that also DE may partake to the clustering process.Comment: 16 pages, accepted for publication in JCA

Thermal and Economic Efficiency of Progressive Retrofit Strategies for School Buildings by a Statistical Analysis based Tool

Design alternatives in air conditioned buildings may be easily compared just by summing the hourly consumption of primary energy, while quantitative approachs for bioclimatic design strategies are difficult to be assessed and compared. A actively heated and passively cooled school building is considered as an application field of a novel methodology to promote an informed choice about the retrofit strategies to be adopted for buildings, defined as the Gained Comfort Cost (GCC). A functional and significant unit (i.e. a classroom), is used to test different energy retrofit solutions and their performances were compared with a baseline, in terms of the capacity to reduce the indoor air temperature variation. The novel methodology is a visual tool allowing to understand the “distance” of indoor conditions from comfort; the retrofit strategies are promoted to reduce this distance considering however the associated costs (LCC) to deal with actual feasibility

Dynamical Dark Energy simulations: high accuracy Power Spectra at high redshift

Accurate predictions on non--linear power spectra, at various redshift z, will be a basic tool to interpret cosmological data from next generation mass probes, so obtaining key information on Dark Energy nature. This calls for high precision simulations, covering the whole functional space of w(z) state equations and taking also into account the admitted ranges of other cosmological parameters; surely a difficult task. A procedure was however suggested, able to match the spectra at z=0, up to k~3, hMpc^{-1}, in cosmologies with an (almost) arbitrary w(z), by making recourse to the results of N-body simulations with w = const. In this paper we extend such procedure to high redshift and test our approach through a series of N-body gravitational simulations of various models, including a model closely fitting WMAP5 and complementary data. Our approach detects w= const. models, whose spectra meet the requirement within 1% at z=0 and perform even better at higher redshift, where they are close to a permil precision. Available Halofit expressions, extended to (constant) w \neq -1 are unfortunately unsuitable to fit the spectra of the physical models considered here. Their extension to cover the desired range should be however feasible, and this will enable us to match spectra from any DE state equation.Comment: method definitely improved in semplicity and efficacy,accepted for publication on JCA