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