Trust-based recommender systems improve rating prediction with respect to Collaborative Filtering by leveraging the additional information provided by a trust network among users to deal with the cold start problem. However, they are challenged by recent studies according to which people generally perceive the usage of data about social relations as a violation of their own privacy. In order to address this issue, we extend trust-based recommender systems with additional evidence about trust, based on public anonymous information, and we make them configurable with respect to the data that can be used in the given application domain: 1. We propose the Multi-faceted Trust Model (MTM) to define trust among users in a compositional way, possibly including or excluding the types of information it contains. MTM flexibly integrates social links with public anonymous feedback received by user profiles and user contributions in social networks. 2. We propose LOCABAL+, based on MTM, which extends the LOCABAL trust-based recommender system with multi-faceted trust and trust-based social regularization. Experiments carried out on two public datasets of item reviews show that, with a minor loss of user coverage, LOCABAL+ outperforms state-of-the art trust-based recommender systems and Collaborative Filtering in accuracy, ranking of items and error minimization both when it uses complete information about trust and when it ignores social relations. The combination of MTM with LOCABAL+ thus represents a promising alternative to state-of-the-art trust-based recommender systems.
In this work, we consider an open single level molecular junction with electrons coupled to a single frequency phonon mode, in which the phonons are also coupled to another heat bath. By applying a temperature gradient between the electrical leads and investigating thermocurrent in non-linear regime, it is shown that the environment can excite phonons which may result in either suppression or very significant enhancement of thermocurrent, depending on the onsite energy. Similarly, in the linear regime the effects of environment are seen in the Seebeck coefficient.
Harvester and agricultural machines are driven both manually and automatically on swarm strategies. In order to avoid undesired movements of the machine, powerful brakes (clutches) are installed on the steering rod to keep track of the machine movements and correct them if undesired events like sudden changes from the original path are detected. The need to operate with reliable and robust devices suggested to design a durability testing bench to assess different braking material performance. In this paper a test bench has been developed to perform wear out characterization and data gathering from different braking materials mounted on a single brake configuration. The proposed work aims at the development of both a robust testing device from the mechanical perspective and a measurement system able to perform accelerated testing controlling the testing temperature and a suitable ageing model for a subset of commercial metallic/epoxide powders used for braking purposes. The work proposes for the first time, some ageing laws parameters for a commonly used braking material exploited in braking systems for heavy duty steering column machines.
The synthesis, Eu complexation, and selective solvent extraction of trivalent americium (Am ) over trivalent europium (Eu ) in nitric acid solution by N-donor ligand of 3,5-bis(2-pyridyl)pyrazole (BisPypzH) were described. By using -butyl benzene as diluent, BisPypzH ligand in combination with 2-bromohexanoic acid demonstrated the extraction selectivity for Am over trivalent lanthanides (Ln ) with the separation factor ( ) value ranging from 14.3 to 59.4. Slope analysis showed the formation of 1:1 and 1:2 metal/ligand extracted species corresponding to the BisPypzH concentration below and above 0.025 mol/L, respectively, which was also confirmed by electrospray ionization mass spectrometry (ESI-MS) and dynamic light scattering (DLS) analyses. The extraction conformed to a cation-exchange model. Additionally, the 1:1 and 1:2 metal/ligand complexes were also observed in methanol solution and in solid state, severally, by means of UV–vis spectroscopy, luminescence spectroscopy and ESI-MS. Furthermore, the analyses of Fourier transform infrared spectra (FTIR), Raman spectra, and time-resolved laser-induced fluorescence spectra (TRLFS) indicated the presence of three bidentate NO and the absence of H O molecules in the inner coordination sphere of the central Eu cation in the complex. Meanwhile, the stability constant for BisPypzH-Eu complex was also given.