2,033 research outputs found
Environmental performances in green labels for hotels – a critical review
The global attention towards climate change has led national governments and the international community to the definition of plans aiming to reduce greenhouse gas emissions in all economic sectors. Recently, attention has focused also on the tourism sector, and especially on the lodging industry, which consumes high amounts of resources and energy to satisfy guests expectations in terms of offered services and comfort conditions. In this sector, eco-certifications or green labels are spreading, perceived as useful marketing tools to communicate the hoteliers’ environmental efforts to consumers, who are becoming more and more sensitive to ecological matters. However, the wide offer of green labels and the lack of appropriate information are contributing to increase costumers’ confusion and perception of real “green”. The present paper focuses its attention on a set of currently available tools to evaluate the environmental performances of hotels, in order to enquire if and to which extent they are able to inform about the sustainability of accommodation structures. Starting from the wide number of certification schemes available on the market, 19 multi-attribute, third-party green labels were compared, aiming to explore the role that energy efficiency measures play in the certification procedure
Defect Engineering: Graphene Gets Designer Defects
An extended one-dimensional defect that has the potential to act as a
conducting wire has been embedded in another perfect graphene sheet.Comment: 2 pages, 1 figur
Nanoengineering Carbon Allotropes from Graphene
Monolithic structures can be built into graphene by the addition and
subsequent re-arrangement of carbon atoms. To this end, ad-dimers of carbon are
a particularly attractive building block because a number of emerging
technologies offer the promise of precisely placing them on carbon surfaces. In
concert with the more common Stone-Wales defect, repeating patterns can be
introduced to create as yet unrealized materials. The idea of building such
allotropes out of defects is new, and we demonstrate the technique by
constructing two-dimensional carbon allotropes known as haeckelite. We then
extend the idea to create a new class of membranic carbon allotropes that we
call \emph{dimerite}, composed exclusively of ad-dimer defects.Comment: 5 pages, 5 figure
When Traffic Flow Prediction and Wireless Big Data Analytics Meet
In this article, we verify whether or not prediction performance can be improved by fitting the actual data to optimize the parameter values of a prediction model. The traffic flow prediction is an important research issue for solving the traffic congestion problem in an Intelligent Transportation System (ITS). The traffic congestion is one of the most serious problems in a city, which can be predicted in advance by analyzing traffic flow patterns. Such prediction is possible by analyzing the realtime transportation data from correlative roads and vehicles. The verification in this article is conducted by comparing the optimized and the normal time series prediction models. With the verification, we can learn that the era of big data is here and will become an important aspect for the study of traffic flow prediction to solve the congestion problem. Experimental results of a case study are provided to verify the existence of the performance improvement in the prediction, while the research challenges of this data-analytics-based prediction are presented and discussed
d_{x^2-y^2} Symmetry and the Pairing Mechanism
An important question is if the gap in the high temperature cuprates has
d_{x^2-y^2} symmetry, what does that tell us about the underlying interaction
responsible for pairing. Here we explore this by determining how three
different types of electron-phonon interactions affect the d_{x^2-y^2} pairing
found within an RPA treatment of the 2D Hubbard model. These results imply that
interactions which become more positive as the momentum transfer increases
favor d_{x^2-y^2} pairing in a nearly half-filled band.Comment: 9 pages and 2 eps figs, uses revtex with epsf, in press, PR
Fluctuating Cu-O-Cu Bond model of high temperature superconductivity in cuprates
Twenty years of extensive research has yet to produce a general consensus on
the origin of high temperature superconductivity (HTS). However, several
generic characteristics of the cuprate superconductors have emerged as the
essential ingredients of and/or constraints on any viable microscopic model of
HTS. Besides a Tc of order 100K, the most prominent on the list include a
d-wave superconducting gap with Fermi liquid nodal excitations, a d-wave
pseudogap with the characteristic temperature scale T*, an anomalous
doping-dependent oxygen isotope shift, nanometer-scale gap inhomogeneity, etc..
The key role of planar oxygen vibrations implied by the isotope shift and other
evidence, in the context of CuO2 plane symmetry and charge constraints from the
strong intra-3d Coulomb repulsion U, enforces an anharmonic mechanism in which
the oxygen vibrational amplitude modulates the strength of the in-plane Cu-Cu
bond. We show, within a Fermi liquid framework, that this mechanism can lead to
strong d-wave pairing and to a natural explanation of the salient features of
HTS
Helium mixtures in nanotube bundles
An analogue to Raoult's law is determined for the case of a 3He-4He mixture
adsorbed in the interstitial channels of a bundle of carbon nanotubes. Unlike
the case of He mixtures in other environments, the ratio of the partial
pressures of the coexisting vapor is found to be a simple function of the ratio
of concentrations within the nanotube bundle.Comment: 3 pages, no figures, submitted to Phys. Rev. Let
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