ParisTech

About: ParisTech is a education organization based out in Paris, France. It is known for research contribution in the topics: Finite element method & Residual stress. The organization has 1888 authors who have published 1965 publications receiving 55532 citations. The organization is also known as: Paris Institute of Technology & ParisTech Développement.

Electron–Phonon Coupling in Luminescent Europium-Doped Hydride Perovskites Studied by Luminescence Spectroscopy, Inelastic Neutron Scattering, and First-Principles Calculations

Abstract: We present a case study on the vibrational coupling of lattice phonons to the electronic 4f7 (8S7/2)–4f65d1 (eg) transition of divalent europium in the hydrides and deuterides LiMH3 and LiMD3 (M = Sr and Ba). For low doping concentrations, these compounds show extraordinarily well-resolved vibronic fine structures at low temperatures. Besides luminescence emission spectroscopy of the europium-doped compounds, we carried out inelastic neutron scattering (INS) experiments of the europium-free compounds. The phonons coupling to the electronic transition are identified, and a good agreement between the vibronic and the INS data is found. The frequencies of the low-energy acoustic modes do not significantly change upon replacing hydride by deuteride, whereas a decrease by a factor of approximately 2 can be observed for the higher energy optic modes. Furthermore, we compare these experimental results to density functional calculations performed with the Vienna Ab initio Simulation Package. Knowledge of the phon...

Socially Aware Virtual Characters: The Social Signal of Smiles [Social Sciences]

Abstract: At first, machines were mainly used to solve complex mathematical problems. Today, they often embody more and more roles typically endowed by humans, such as a tutor in a virtual learning class or an assistant for virtual task realization. Moreover, the paradigm highlighted in [1] reveals that the user's relation with the computer is intrinsically social, with high similarities compared to interpersonal relationships. For instance, people have no problem using communicative means (verbal and nonverbal behavior) to interact with artificial entities and apply polite rules. One particularly interesting aspect of the human machine interaction is the bidirectionality of the relation: users exhibit social behaviors to the computer, and the machine's behavior affects users. Reeves and Nass [1] have shown that people tend to react naturally and socially to computers, as they would do to another person. In such a human-machine interaction, which can be seen as a particular social context with users sensitive to the computer behavior, the development of socially aware virtual characters appears fundamental.

Tandem Smart Cards: Enforcing Trust for TLS-Based Network Services

Abstract: This paper presents a new concept, called tandem, dedicated to smart cards that control TLS-based applications. The originality of this approach is to introduce a collaborative process between a smart card and its docking host. This technology enables the secure downloading of a huge amount of data, in untrustworthy computers. We present software paradigms and APIs that facilitate the practical deployment of such cards. We analyze experimental results, obtained with four commercial SIM cards and general purpose java cards.

Determination of critical properties and acentric factors of petroleum fractions using artificial neural networks

Abstract: Various correlations are available that can determine the critical properties and acentric factors of petroleum fractions. The available methods may have low accuracy in determining these properties for heavy petroleum fractions and may require further verification because, during the development of the original predictive methods, the data describing the critical properties and acentric factors of heavy hydrocarbons and petroleum fractions were not available. In this work, after a quick review of the most common correlations reported in the literature, an alternative method based on the artificial neural network (ANN) technique is proposed to predict the critical temperatures, critical pressures, critical volumes, and acentric factors of petroleum fractions, especially heavy fractions, from their specific gravity and the average normal boiling-point temperature values. Among the different neural networks reported in the literature, the feed-forward neural network method with a modified Levenberg−Marquard...

Long term evolution of heat budget in the Mediterranean Sea from Med-CORDEX forced and coupled simulations

Abstract: This study evaluates the Mediterranean Sea heat budget components from a set of forced and coupled simulations performed in the frame of the Med-CORDEX project. The simulations use regional climate system models (RCSMs) dedicated to the Mediterranean area and driven by the ERA40/ERA-Interim reanalyses. The study focuses on the period 1980–2010. Interannual variations of the average net heat flux at the sea surface are consistent among models but the spread in the mean values is large (from −4.8 to +2.2 Wm−2) with the coupled models showing the lowest heat loss from the sea. For the heat flux at the Strait of Gibraltar both interannual variations and mean values show a large intermodel spread. The basin average temperature shows positive trends with highest values in the coupled models; it also shows interannual variations that are in good agreement with observations. The heat content rate is calculated based on the derivative of the average temperature and is found to be significantly correlated for most models with the net heat flux at the sea surface (average correlation ~0.5) but not with the net heat flux through the Strait of Gibraltar (average correlation ~0.2), suggesting that in the considered RCSMs the interannual variability of the heat content rate is mainly driven by the surface heat fluxes. The resemblance between the simulated and observed heat content rates is stronger in the forced models than in the coupled ones. This is explained by the stronger constraint applied to the forced models by the use of the surface temperature relaxation to observations. The temperature of the outflowing water through the Strait of Gibraltar shows positive and significant trends, also higher in the coupled models. It is suggested that the Mediterranean Sea warming found in most models and in particular in the coupled ones, induces a change of the hydrographic conditions that affects the Strait of Gibraltar.