Dynamic characterization of a bell tower by interferometric sensor

The dynamic characterization of a medieval bell tower, forced by its own bell is obtained by using a newly developed interferometric sensor. The displacement of the tower is remotely detected, without installation of contact sensors and the use of a cumbersome vibrodyne for structure excitation. The measurement technique demonstrated in this paper allows heritage bell towers to be monitored in a simple and rapid way.     

Functionalized Graphene as an Electron‐Cascade Acceptor for Air‐Processed Organic Ternary Solar Cells

Functionalized graphene nanoflakes (GNFs) are used as an electron‐cascade acceptor material in air‐processed organic ternary bulk heterojunction solar cells. The functionalization is realized via the attachment of the ethylenedinitrobenzoyl (EDNB) molecule to the GNFs. Simulation and experimental results show that such nanoscale modification greatly influences the density of states near the Fermi level. Consequently, the GNF‐EDNB blend presents favorable highest occupied molecular orbital and lowest unoccupied molecular orbital energy levels to function as a bridge structure between the poly[N‐9′‐heptadecanyl‐2,7‐carbazole‐alt‐5,5‐(4′,7′‐di‐2‐thienyl‐2′,1′,3′‐benzothiadiazole)] (PCDTBT) and the [6,6]‐phenyl‐C71‐butyric‐acid‐methyl‐ester (PC₇₁BM). The improved exciton dissociation and charge transport are associated with the better energy level alignment of the ternary blend and the high electrical conductivity of the GNFs, which act as additional electron transport channels within the photoactive layer. The resulting PCDTBT/GNF‐EDNB/PC₇₁BM ternary organic solar cells, fabricated entirely under ambient conditions, exhibit an average power conversion efficiency enhancement of ≈18% as compared with the binary blend PCDTBT/PC₇₁BM.     

Temperature and Frequency Dependence of Electric Field‐Induced Phase Transitions in PMN–0.32PT

Single crystal (1 ? x)Pb(Mg_1/3 Nb_2/3)O₃–xPbTiO₃ [PMN–xPT] (x = 0.32) is a relaxor‐ferroelectric material known to exhibit ‘giant’ piezoelectric behavior, with achievable strains in excess of 1% for samples of certain particular crystallographic orientations and chemical compositions close to the morphotropic phase boundary. In this study, we investigate the electric field‐induced structural phase transitions in single crystal PMN–0.32PT with time‐of‐flight neutron diffraction and macroscopic electrical polarization measurements, and show that both the frequency of the applied ac field and the temperature of the sample are critical factors in determining these phase transition fields.     

Molecular‐Level Switching of Polymer/Nanocrystal Non‐Covalent Interactions and Application in Hybrid Solar Cells

Hybrid composites obtained upon blending conjugated polymers and colloidal semiconductor nanocrystals are regarded as attractive photo­active materials for optoelectronic applications. Here it is demonstrated that tailoring nanocrystal surface chemistry permits to control non‐covalent and electronic interactions between organic and inorganic components. The pending moieties of organic ligands at the nanocrystal surface are shown to not merely confer colloidal stability while hindering charge separation and transport, but drastically impact morphology of hybrid composites during formation from blend solutions. The relevance of this approach to photovoltaic applications is demonstrated for composites based on poly(3‐hexylthiophene) and lead sulfide nanocrystals, considered as inadequate until this report, which enable the fabrication of hybrid solar cells displaying a power conversion efficiency that reaches 3%. By investigating (quasi)steady‐state and time‐resolved photo‐induced processes in the nanocomposites and their constituents, it is ascertained that electron transfer occurs at the hybrid interface yielding long‐lived separated charge carriers, whereas interfacial hole transfer appears hindered. Here a reliable alternative aiming to gain control over macroscopic optoelectronic properties of polymer/nanocrystal composites by mediating their non‐covalent interactions via ligands' pending moieties is provided, thus opening new possibilities towards efficient solution‐processed hybrid solar cells.     

Churning power losses of ordinary gears: a new approach based on the internal fluid dynamics simulations

The increasing need of more and more efficient gearboxes implies the need of predictive models in order to compare, during the design stage, different design solutions. The models provided by literature are mostly experimentally derived and not accurate on real applications. A new trend suggests the adoption of computational fluid dynamics (CFD) for the calculation of the no‐load losses of gear transmissions. In this sense, literature provides some works, but most of them involve only one single phase. In this paper, the real operating condition in which the gears are immersed in an oil lubricant mixture is studied. Adopting an open‐source code, OpenFOAM®, the influence of some operating and geometrical parameters on the churning losses has been investigated. The aims are both to provide data that can be effectively used by engineers in the design practice and to prove, once again, CFD to be an effective approach for this kind of investigations. Copyright © 2014 John Wiley & Sons, Ltd.     

Proficiency testing programs to improve traceability in chemical analysis

The results of the proficiency test program T062 organised by CNACL (China National Accreditation Committee for Laboratories) were analysed with different statistical procedures: the robust statistic procedure used by the proficiency test organisers and the UNI ISO 5725-2 [8] procedure which is a basic method for the determination of the repeatability and the reproducibility of a standard measurement method to improve the traceability in chemical analysis.The data are taken from a program of chemical analysis on a low alloy steel.The obtained results are commented; the paper aim to give elements of discussion about standard test method, uncertainty evaluations, and repeatability of test results on chemical analysis performed by chemical laboratories.