432 research outputs found
Relationship between urban green spaces and other features of urban morphology with traffic noise distribution
The effect of greenery on traffic noise mitigation has been extensively studied on the level of single plants, green walls, berms and hedges, but not considering whole sample areas within the cities. Therefore, the aim of this paper is to investigate the relationship between features of urban morphology related to green spaces, roads or buildings and traffic noise distribution in urban areas. The analysis was applied in eight UK cities with different historical and architectural background, following two different settlement forms (radial, linear). In each city a 30 km2 grid was defined and three different levels of approach were considered (macro-scale, meso-scale, micro-scale). The first level regarded the eight cities as single entities, while in the second one every single tile of the applied grid was investigated in two different cities. In the third level only the eight city centres were analyzed. Statistical analysis was used combined with GIS tools. In total 18 variables were constructed and tested for possible relationships with noise levels (Lden). It was found that in spite of the fact that each city has its own dynamic and form, features of urban morphology were related to traffic noise levels to a different extent at each scale. At the macro-scale, the green space pattern was related to the structure of the city as well as the traffic noise levels in combination with the rest of the morphological parameters. At the meso-scale, an increase in internal road connectivity contributed to higher traffic noise. Green space variables explained part of the variance in traffic prediction models. Finally, at the micro-scale, it was also proved that different areas can have the same building coverage but different noise levels. Therefore, these indexes could be profiled and used as an “a priori” tool for urban sound planning
Gradient Flows from an Approximation to the Exact Renormalization Group
Through appropriate projections of an exact renormalization group equation,
we study fixed points, critical exponents and nontrivial renormalization group
flows in scalar field theories in . The standard upper critical
dimensions , appear naturally encoded in
our formalism, and for dimensions smaller but very close to our results
match the \ee-expansion. Within the coupling constant subspace of mass and
quartic couplings and for any , we find a gradient flow with two fixed
points determined by a positive-definite metric and a -function which is
monotonically decreasing along the flow.Comment: 10 pages, TeX, 3 postscript figures available upon request,
UB-ECM-PF-93/2
Scheme Independence and the Exact Renormalization Group
We compute critical exponents in a symmetric scalar field theory in
three dimensions, using Wilson's exact renormalization group equations expanded
in powers of derivatives. A nontrivial relation between these exponents is
confirmed explicitly at the first two orders in the derivative expansion. At
leading order all our results are cutoff independent, while at next-to-leading
order they are not, and the determination of critical exponents becomes
ambiguous. We discuss the possible ways in which this scheme ambiguity might be
resolved.Comment: 15 pages, TeX with harvmac, 2 figures in compressed postscript;
presentation of first section revised, several minor errors corrected, two
references adde
Living and Dying at the Portus Romae
This paper presents the first results of research into plant, animal, and human remains from Portus, the maritime port of Imperial Rome, in order to examine the diet and geographical origins of its inhabitants between the second and sixth century AD. Comparisons with evidence from the excavation and ceramic analysis show clear changes throughout the period, with shifts in diet and patterns of foods import that can be related to the commercial and political changes following the breakdown of Roman of the Mediterranean
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The role of energy productivity in US agriculture
This paper investigates the role of energy on U.S. agricultural productivity using panel data at the state level for the period 1960–2004.We first provide a historical account of energy use in U.S. agriculture. To do this we rely on the Bennet cost indicator to study how the price and volume components of energy costs have developed over time. We then proceed to analyze the contribution of energy to productivity in U.S. agriculture employing the Bennet–Bowley productivity indicator. An important feature of the Bennet–Bowley indicator is its direct association with the change in (normalized) profits. Thus our study is also able to analyze the link between profitability and productivity. Panel regression estimates indicate that energy prices have a negative effect on profitability in the U.S. agricultural sector. We also find that energy productivity has generally remained below total farm productivity following the 1973–1974 global energy crisis.Keywords: Agricultural productivity, Bennet-Bowley indicator, Energy productivit
Physicochemical and rheological properties of a transparent asphalt binder modified with Nano-TiO2
Transparent binder is used to substitute conventional black asphalt binder and to provide light-colored pavements, whereas nano-TiO2 has the potential to promote photocatalytic and self-cleaning properties. Together, these materials provide multifunction effects and benefits when the pavement is submitted to high solar irradiation. This paper analyzes the physicochemical and rheological properties of a transparent binder modified with 0.5%, 3.0%, 6.0%, and 10.0% nano-TiO2 and compares it to the transparent base binder and conventional and polymer modified binders (PMB) without nano-TiO2. Their penetration, softening point, dynamic viscosity, master curve, black diagram, Linear Amplitude Sweep (LAS), Multiple Stress Creep Recovery (MSCR), and Fourier Transform Infrared Spectroscopy (FTIR) were obtained. The transparent binders (base and modified) seem to be workable considering their viscosity, and exhibited values between the conventional binder and PMB with respect to rutting resistance, penetration, and softening point. They showed similar behavior to the PMB, demonstrating signs of polymer modification. The addition of TiO2 seemed to reduce fatigue life, except for the 0.5% content. Nevertheless, its addition in high contents increased the rutting resistance. The TiO2 modification seems to have little effect on the chemical functional indices. The best percentage of TiO2 was 0.5%, with respect to fatigue, and 10.0% with respect to permanent deformation.Fundação para a Ciência e a Tecnologia—under the projects
for Strategic Funding UIDB/04650/2020 and UIDB/04029/2020, and Nanobased concepts for Innovative and
Eco-sustainable constructive material surfaces PTDC/FIS/120412/2010. Furthermore, we would like to thank the
Industrial Research Fund (IOF) of the University of Antwerp for funding the PAPPoA project (IOF/SBO/41859/2020).
Lastly, the first author would like to acknowledge FCT for the PhD scholarship (SFRH/BD/137421/2018
Quantum and Thermal Fluctuations in Field Theory
Blocking transformation is performed in quantum field theory at finite
temperature. It is found that the manner temperature deforms the renormalized
trajectories can be used to understand better the role played by the quantum
fluctuations. In particular, it is conjectured that domain formation and mass
parameter generation can be observed in theories without spontaneous symmetry
breaking.Comment: 27pp+7 figures, MIT-CTP-214
Modification of a transparent binder for road pavements using TiO2 nanoparticles
Light and heat are relevant factors for road pavements since they promote the aging of the asphalt surfaces [1], and a large amount of heating can intensify the Urban Heat Island (UHI) effect [2]. Contrariwise, the lack of light strongly affects visibility conditions, reducing safety [3]. The conventional black color of asphalt pavements absorbs light and stores a large amount of thermal energy, which can be reduced opting by the application of light-colored pavements using, for example, a transparent binder [3]. Industrial activities and road traffic are the main sources of pollutant emissions, mostly SO2 and NOx, which are hazardous atmospheric pollutants. There are several consequences at different scales caused by these harmful gases, such as intensification of the greenhouse effect, acid rain, and public health problems. With the use of nano-TiO2 into/over asphalt mixtures, and consequently with the functionalization process considering the photocatalytic and self-cleaning properties, road pavements become the ideal places to mitigate environmental pollution due to proximity to the emissions [4]. If a transparent binder modified with nanoparticles of TiO2 is used, pavements will present multifunction effects and benefits when submitted to high solar irradiation. The production at laboratory-scale of such pavements is presented in Figure 1. First, the transparent binder was modified with nano-TiO2 (0, 0.5%, 3.0%, 6.0% and 10.0%). Binder's workability was confirmed. It presented similar behavior as a polymer modified binder. In these binder samples, the addition of high contents of nano-TiO2 increased the rutting resistance, but it seemed to reduce fatigue life, except for the 0.5%. Also, the nano-TiO2 modification had a slight effect on the chemical functional indices. The best percentage of TiO2 was 10.0% considering rutting resistance and 0.5% concerning fatigue life
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