1,700 research outputs found

    Future trajectories of renewable energy consumption in the European Union

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    Renewable energy sources (RESs) are able to reduce the European Union (EU)’s dependence on foreign energy imports, also meeting sustainable objectives to tackle climate change and to enhance economic opportunities. Energy management requires a quantitative analysis and the European Commission follows the performance of each Member State (MS) in order to define the corrective measures towards 2020 targets. Starting from historical data reported in the Eurostat database and through a mathematical model, this work proposes future trajectories towards 2020 of the share of energy from renewables (REs) in terms of gross final energy consumption (GFEC). Furthermore, a quantitative analysis based on two indices—(i) the share of REs in GFEC, and (ii) gross final renewable energy consumption (GFREC) per capita—permits a comparison among 28 MSs. The share of REs in GFEC in EU 28 varies from 19.4% to 21.8% in future trajectories towards 2020. Sweden and Finland occupy the top part of the ranking, while six MSs (Belgium, France, Ireland, Luxembourg, The Netherlands, and the United Kingdom) are not able to reach the 2020 targets

    Gamma-GQM Time Headway Model: Endogenous Effects in Rural Two-lane Two-way Roads

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    AbstractStudy of vehicle time headway distributions is essential in many traffic engineering applications, such as capacity and level of service analysis and, in recent years, in the fields of vehicle generation in traffic micro-simulation models and driving simulation applications. This paper presents results from an experimental analysis of vehicle time headway distributions on two-lane two-way rural roads. Analysis focused on estimating a well-known model, the gamma-generalized queuing model (gamma-GQM). A trendless analysis of observed time headways was also carried out. The endogenous traffic parameters considered as affecting time headway distributions were flow rate and flow composition (percentage of heavy vehicles). Exogenous conditions, such as weather and geometric futures, were common to all time periods and cross-sections analysed. Gamma-GQM pdf appears to be very suitable for representing real headway distributions in all the analysed situations; it fits real-time headway distributions well, despite flow rate range and traffic composition (range of percentage of heavy vehicles)

    Measurements of vacuum magnetic birefringence using permanent dipole magnets: the PVLAS experiment

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    The PVLAS collaboration is presently assembling a new apparatus (at the INFN section of Ferrara, Italy) to detect vacuum magnetic birefringence (VMB). VMB is related to the structure of the QED vacuum and is predicted by the Euler-Heisenberg-Weisskopf effective Lagrangian. It can be detected by measuring the ellipticity acquired by a linearly polarised light beam propagating through a strong magnetic field. Using the very same optical technique it is also possible to search for hypothetical low-mass particles interacting with two photons, such as axion-like (ALP) or millicharged particles (MCP). Here we report results of a scaled-down test setup and describe the new PVLAS apparatus. This latter one is in construction and is based on a high-sensitivity ellipsometer with a high-finesse Fabry-Perot cavity (>4×105>4\times 10^5) and two 0.8 m long 2.5 T rotating permanent dipole magnets. Measurements with the test setup have improved by a factor 2 the previous upper bound on the parameter AeA_e, which determines the strength of the nonlinear terms in the QED Lagrangian: Ae(PVLAS)<3.3×10−21A_e^{\rm (PVLAS)} < 3.3 \times 10^{-21} T−2^{-2} 95% c.l. Furthermore, new laboratory limits have been put on the inverse coupling constant of ALPs to two photons and confirmation of previous limits on the fractional charge of millicharged particles is given

    The PVLAS experiment: measuring vacuum magnetic birefringence and dichroism with a birefringent Fabry-Perot cavity

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    Vacuum magnetic birefringence was predicted long time ago and is still lacking a direct experimental confirmation. Several experimental efforts are striving to reach this goal, and the sequence of results promises a success in the next few years. This measurement generally is accompanied by the search for hypothetical light particles that couple to two photons. The PVLAS experiment employs a sensitive polarimeter based on a high finesse Fabry-Perot cavity. In this paper we report on the latest experimental results of this experiment. The data are analysed taking into account the intrinsic birefringence of the dielectric mirrors of the cavity. Besides the limit on the vacuum magnetic birefringence, the measurements also allow the model-independent exclusion of new regions in the parameter space of axion-like and milli-charged particles. In particular, these last limits hold also for all types of neutrinos, resulting in a laboratory limit on their charge

    First results from the new PVLAS apparatus: a new limit on vacuum magnetic birefringence

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    Several groups are carrying out experiments to observe and measure vacuum magnetic birefringence, predicted by Quantum Electrodynamics (QED). We have started running the new PVLAS apparatus installed in Ferrara, Italy, and have measured a noise floor value for the unitary field magnetic birefringence of vacuum Δnu(vac)=(4±20)×10−23\Delta n_u^{\rm (vac)}= (4\pm 20) \times 10^{-23} T−2^{-2} (the error represents a 1σ\sigma deviation). This measurement is compatible with zero and hence represents a new limit on vacuum magnetic birefringence deriving from non linear electrodynamics. This result reduces to a factor 50 the gap to be overcome to measure for the first time the value of Δnu(vac,QED)\Delta n_u^{\rm (vac,QED)} predicted by QED: Δnu(vac,QED)=4×10−24\Delta n_u^{\rm (vac,QED)}= 4\times 10^{-24} ~T−2^{-2}. These birefringence measurements also yield improved model-independent bounds on the coupling constant of axion-like particles to two photons, for masses greater than 1 meV, along with a factor two improvement of the fractional charge limit on millicharged particles (fermions and scalars), including neutrinos

    New PVLAS model independent limit for the axion coupling to γγ\gamma\gamma for axion masses above 1meV

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    During 2014 the PVLAS experiment has started data taking with a new apparatus installed at the INFN Section of Ferrara, Italy. The main target of the experiment is the observation of magnetic birefringence of vacuum. According to QED, the ellipticity generated by the magnetic birefringence of vacuum in the experimental apparatus is expected to be ψ(QED)≈5×10−11\psi^{\rm(QED)} \approx 5\times10^{-11}. No ellipticity signal is present so far with a noise floor ψ(noise)≈2.5×10−9\psi^{\rm(noise)} \approx 2.5\times10^{-9} after 210 hours of data taking. The resulting ellipticity limit provides the best model independent upper limit on the coupling of axions to γγ\gamma\gamma for axion masses above 10−310^{-3}eV

    Measurement of the Cotton Mouton effect of water vapour

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    In this paper we report on a measurement of the Cotton Mouton effect of water vapour. Measurement performed at room temperature (T=301T=301 K) with a wavelength of 1064 nm gave the value Δnu=(6.67±0.45)⋅10−15\Delta n_u = (6.67 \pm 0.45) \cdot 10^{-15} for the unit magnetic birefringence (1 T magnetic field and atmospheric pressure)
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