O potencial da utilização da ferramenta de mapa de ruído em diferentes escalas de análise

The acoustic mapping is an important tool to plan and control urban noise. It can be used for various purposes, depending on the scale and objective of the study. In Brazil, despite the state of the art research in this area, the methods of computer simulation of impact sound are not required not even to large road infrastructure. Furthermore, it’s very commonly used in a level of municipal scale or an urban area, such as a neighbourhood. However, the use of noise mapping on the scale of the city block, as a tool to assistance in project decisions, is still enough scarce. Thus, the paper aims at demonstrating the potential of this tool in different scales of evaluation. The experimental field occurs in the neighborhood of Petrópolis, Natal / RN, which like other medium-sized cities, goes through rapid urban growth. Through the program SoundPLAN, studies were performed for all neighborhood, predictions with future models for part of the same were made and the influence of initial project decisions were verified. The research demonstrates that the current noise levels are already high in the neighborhood, principally along the arterial roads and the tendency of this situation is to worsen in the future. In addition, in urban areas, buildings can influence the propagation of sound as barriers, such as objects of reflection. To manage noise on the building, project decisions must be thought together, because the choice of form is intimately linked to the implantation of the building on the lot.O mapeamento acústico é uma importante ferramenta de planejamento e controle do ruído urbano. Pode ser utilizado para diversos fins, dependendo da escala e objetivo do estudo. No Brasil, apesar do estado da arte das pesquisas nesta área, os métodos de simulação computacional de impacto sonoro não são exigidos nem mesmo para infraestruturas rodoviárias de grande porte. Além disso, é bastante comum ser utilizado no nível da escala municipal ou de uma área urbana, como em um bairro. Entretanto, o uso do mapa de ruído na escala da quadra, como ferramenta de auxílio nas decisões projetuais, ainda é bastante escasso. Assim, o artigo tem o objetivo demonstrar o potencial dessa ferramenta em diferentes escalas de avaliação. O campo experimental ocorre no Bairro de Petrópolis em Natal/RN, que a exemplo de outras cidades de médio porte, passa por acelerado crescimento urbano. Através do programa SoundPLAN, foram realizados estudos para todo o Bairro, previsões com modelos futuros para uma parcela do mesmo e verificado a influência de decisões iniciais de projeto. A pesquisa demonstra que os níveis sonoros atuais no Bairro já estão elevados, principalmente ao longo das vias arteriais e que a tendência da situação é se agravar no futuro. Além disso, no meio urbano, as edificações podem influenciar a propagação sonora tanto como barreiras, como objetos de reflexão. Para a gestão do ruído no edifício, as decisões de projeto devem ser pensadas juntas, pois a escolha da forma está intimamente ligada à implantação do edifício no lote

Inflationary scalar spectrum in loop quantum cosmology

In the context of loop quantum cosmology, we consider an inflationary era driven by a canonical scalar field and occurring in the semiclassical regime, where spacetime is a continuum but quantum gravitational effects are important. The spectral amplitude and index of scalar perturbations on an unperturbed de Sitter background are computed at lowest order in the slow-roll parameters. The scalar spectrum can be blue-tilted and far from scale invariance, and tuning of the quantization ambiguities is necessary for agreement with observations. The results are extended to a generalized quantization scheme including those proposed in the literature. Quantization of the matter field at sub-horizon scales can provide a consistency check of such schemes.Comment: 29 pages, 2 figures. v2: typos corrected, discussion improved and extended, new section added. Conclusions are unchange

Dynamical Dark Energy or Simply Cosmic Curvature?

We show that the assumption of a flat universe induces critically large errors in reconstructing the dark energy equation of state at z>~0.9 even if the true cosmic curvature is very small, O(1%) or less. The spuriously reconstructed w(z) shows a range of unusual behaviour, including crossing of the phantom divide and mimicking of standard tracking quintessence models. For 1% curvature and LCDM, the error in w grows rapidly above z~0.9 reaching (50%,100%) by redshifts of (2.5,2.9) respectively, due to the long cosmological lever arm. Interestingly, the w(z) reconstructed from distance data and Hubble rate measurements have opposite trends due to the asymmetric influence of the curved geodesics. These results show that including curvature as a free parameter is imperative in any future analyses attempting to pin down the dynamics of dark energy, especially at moderate or high redshifts.Comment: 5 pages, 2 figures. To appear in JCA

Is the Dynamics of Tracking Dark Energy Detectable?

We highlight the unexpected impact of nucleosynthesis and other early universe constraints on the detectability of tracking quintessence dynamics at late times, showing that such dynamics may well be invisible until the unveiling of the Stage-IV dark energy experiments (DUNE, JDEM, LSST, SKA). Nucleosynthesis forces |w'(0)| < 0.2 for the models we consider and strongly limits potential deviations from LCDM. Surprisingly, the standard CPL parametrisation, w(z) = w_0 + w_a z/(1+z), cannot match the nucleosynthesis bound for minimally coupled tracking scalar fields. Given that such models are arguably the best-motivated alternatives to a cosmological constant these results may significantly impact future cosmological survey design and imply that dark energy may well be dynamical even if we do not detect any dynamics in the next decade.Comment: 5 pages, 2 figures. Updated to match published versio

Non-parametric Dark Energy Degeneracies

We study the degeneracies between dark energy dynamics, dark matter and curvature using a non-parametric and non-perturbative approach. This allows us to examine the knock-on bias induced in the reconstructed dark energy equation of state, w(z), when there is a bias in the cosmic curvature or dark matter content, without relying on any specific parameterisation of w. Even assuming perfect Hubble, distance and volume measurements, we show that for z > 1, the bias in w(z) is up to two orders of magnitude larger than the corresponding errors in Omega_k or Omega_m. This highlights the importance of obtaining unbiased estimators of all cosmic parameters in the hunt for dark energy dynamics.Comment: 10 pages, 8 figures. Invited Review for special issue of General Relativity and Gravitation issue on Dark Energy, eds. G. F.R Ellis et a