3,844 research outputs found
A Model for Selecting the Most Cost-Effective Pressure Control Device for More Sustainable Water Supply Networks
Pressure Reducing Valves (PRV) have been widely used as a device to control pressure at nodes in water distribution networks and thus reduce leakages. However, an energy dissipation takes place during PRV operation. Thus, micro-hydropower turbines and, more precisely, Pump As Turbines (PAT) could be used as both leakage control and energy generating devices, thus contributing to a more sustainable water supply network. Studies providing clear guidelines for the determination of the most cost-effective device (PRV or PAT) analysing a wide database and considering all the costs involved, the water saving and the eventual power generation, have not been carried out to date. A model to determine the most cost-effective device has been developed, taking into account the Net Present Value (NPV). The model has been applied to two case studies: A database with 156 PRVs sites located in the UK; and a rural water supply network in Ireland with three PRVs. The application of the model showed that although the investment cost associated to the PRV installation is lower in the majority of cases, the NPV over the lifespan of the PAT is higher than the NPV associated with the PRV operation. Furthermore, the ratio between the NPV and the water saved over the lifespan of the PAT/PRV also offered higher values (from 6% to 29%) for the PAT installation, making PATs a more cost-effective and more sustainable means of pressure control in water distribution networks. Finally, the development of less expensive turbines and/or PATs adapted to work under different flow-head conditions will tip the balance toward the installation of these devices even further
Decomposing Cross-Country Gaps in Obesity and Overweight: Does the Social Environment Matter?
[cat] Una qĂŒestiĂł clau sobre la producciĂł de salut relativament poc explorada es refereix a la influĂšncia dels factors socioeconĂČmics i mediambientals sobre el pes i lâobesitat. Aquesta problemĂ tica adquireix particular rellevĂ ncia quan es comparen dos paĂŻsos Mediterranis com ItĂ lia i Espanya. Ăs interessant adonar-se que lâobesitat a Espanya Ă©s 5 punts percentual mĂ©s elevada al 2003 mentre que a lâany 1990 era aproximadament la mateixa en ambdĂłs paĂŻsos. Aquesta article presenta una descomposiciĂł no lineal dels gaps o diferencials en taxes de sobrepĂšs (Ăndex de massa corporal â IMC- entre 25 i 29.9 9 kg/m2), obesitat classe 1 (IMCâ„30 kg/m2) i classe 2 (IMCâ„35 kg/m2) entre Espanya i ItĂ lia per gĂšnere i grups dâedat. En explicar aquests gaps entre paĂŻsos aĂŻllem les influĂšncies dels estils de vida, els efectes socioeconĂČmics i els mediambientals. Els nostres resultats indiquen que quan no es controla pels efectes mediambientals (efectes de grup o âpeer effectsâ) els hĂ bits alimentaris i el nivell educatiu sĂłn els principals predictors del gaps totals entre paĂŻsos (36-52%), si bĂ© aquests dos factors exerceixen un impacte diferenciat segons gĂšnere i edat. Un tant paradoxalment, quan controlem pels efectes de grup aquests predictors perden la seva capacitat explicativa i els efectes de grup passen a explicar entre el 46-76% dels gaps en sobrepĂšs i obesitat i mostren un patrĂł creixent amb lâedat.[eng] A key question underpinning health production, and one that remains relatively unexplored, is the influence of socio-economic and environmental factors on weight gain and obesity. Such issues acquire particular relevance when data from two Mediterranean countries (Italy and Spain) are compared. Interestingly, the obesity rate was 5 percentage points higher in Spain in 2003 while in 1990 it had been roughly the same in the two countries. This paper reports a non-linear decomposition of gaps in overweight (body mass index â BMI - between 25 and 29.9 kg/m2), class 1 (BMIâ„30 kg/m2) and class 2 obesity (BMIâ„35 kg/m2) between Spain and Italy by both gender and age. We isolate the influence of lifestyles, socioeconomic and environmental effects in explaining cross-country gaps in the prevalence of obesity. Our findings suggest that when the social environment (peer effects) is not controlled for, eating habits and education are the main predictors of total cross-country gaps (36-52%), albeit that these two factors have a different impact depending on gender and age. Somewhat paradoxically, however, when we controlled for the social environment, these previous predictors lost their explanatory power and peer effects were found to explain between 46 and 76% of gaps and to exhibit an increasing age pattern
Filamentation processes and dynamical excitation of light condensates in optical media with competing nonlinearities
We analyze both theoretically and by means of numerical simulations the
phenomena of filamentation and dynamical formation of self-guided nonlinear
waves in media featuring competing cubic and quintic nonlinearities. We provide
a theoretical description of recent experiments in terms of a linear stability
analysis supported with simulations, showing the possibility of experimental
observation of the modulational instability suppression of intense light pulses
travelling across such nonlinear media. We also show a novel mechanism of
indirect excitation of {\em light condensates} by means of coalescence
processes of nonlinear coherent structures produced by managed filamentation of
high power laser beams.Comment: 6 pages, 4 figure
Creating movable interfaces by micro-powder injection moulding
This paper presents a novel in situ technique to produce articulated components with high-precision, micro-scale movable interfaces by micro-powder injection moulding (ÎŒPIM). The presented process route is based on the use of micro-scale sacrificial layer between the movable subcomponents which is eliminated during the debinding step, creating a dimensionally-controlled, micro-scale mobile interface. The fabrication technique combines the advantages of micro-powder overmoulding, catalytic debinding and sintering. The demonstrated example was a finger bone prosthesis joint consisting of two sub-components with an interface between components of 200 ÎŒm in size. The geometries of the sub-components were designed such that they are inseparable throughout the process whilst allowing them to move relative to each other after the debinding stage. The components produced showed the feasibility of the process route to produce readily-assembled meso-, and potentially micro-, scale articulated system
Total Differentiability and Monogenicity for Functions in Algebras of Order 4
In this paper we discuss some notions of analyticity in associative algebras with unit. We also recall some basic tool in algebraic analysis and we use them to study the properties of analytic functions in two algebras of dimension four that played a relevant role in some work of the Italian school, but that have never been fully investigated
Detecting photon-photon scattering in vacuum at exawatt lasers
In a recent paper, we have shown that the QED nonlinear corrections imply a
phase correction to the linear evolution of crossing electromagnetic waves in
vacuum. Here, we provide a more complete analysis, including a full numerical
solution of the QED nonlinear wave equations for short-distance propagation in
a symmetric configuration. The excellent agreement of such a solution with the
result that we obtain using our perturbatively-motivated Variational Approach
is then used to justify an analytical approximation that can be applied in a
more general case. This allows us to find the most promising configuration for
the search of photon-photon scattering in optics experiments. In particular, we
show that our previous requirement of phase coherence between the two crossing
beams can be released. We then propose a very simple experiment that can be
performed at future exawatt laser facilities, such as ELI, by bombarding a low
power laser beam with the exawatt bump.Comment: 8 pages, 6 figure
Polaronic conductivity in the photoinduced phase of 1T-TaS2
The transient optical conductivity of photoexcited 1T-TaS2 is determined over
a three-order-of-magnitude frequency range. Prompt collapse and recovery of the
Mott gap is observed. However, we find important differences between this
transient metallic state and that seen across the thermally-driven
insulator-metal transition. Suppressed low-frequency conductivity, Fano phonon
lineshapes, and a mid-infrared absorption band point to polaronic transport.
This is explained by noting that the photo-induced metallic state of 1T-TaS2 is
one in which the Mott gap is melted but the lattice retains its low-temperature
symmetry, a regime only accessible by photo-doping.Comment: 10 pages, 4 figure
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