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Study of the weakly bound pair Helium–Krypton: Interatomic potential, interaction hyperpolarizabilities and hyperRayleigh spectra
No full textInternational audienceTwo interatomic potentials of the He–Kr mixture are empirically developed from the BFW and MTT type potentials by fitting them to the thermophysical and transport properties over a wide temperature range. The vector part b1 and septor part b3 of the interaction hyperpolarizability tensor of the He–Kr pair are obtained on the basis of several ab initio methods as functions of the interatomic distance. The collision-induced hyperRayleigh scattering (CIHRS) spectra scattered by the He–Kr pairs at room temperature are calculated in absolute units for the two proposed potentials and other potentials from the literature. The spectral moments are used as a criterion of the reliability of the computed profiles. The frequency-dependent depolarization ratio of the CIHRS spectra is evaluated. The spectral features of the CIHRS profiles due to b1 and b3 are discussed
Increasing DC system stability thanks to energy control in MMC based DC-DC converters
No full textInternational audienceDC voltage regulation of DC networks is essential to the operation of the system. Recently a new control method called virtual capacitor control has been proposed for the Modular Multilevel Converter (MMC) to increase the inertia of HVDC systems. In the development of future DC grids, DC-DC converters will be needed. Most of DC-DC converters proposed in the literature for HVDC are based on the MMC, thus some of the features of this converter can be extended for DC-DC converters. In this paper, the virtual capacitor control is proposed for the Front-to-Front MMC. The proposed control approach is validated in transient simulations, analysing the impact on the interconnection of two DC systems. The simulations results show that the variation of the voltage of a DC network after a power disturbance can be decreased with the proposed control and at the same time the DC-DC converter offers a decoupling to the second DC network which is not affected by the perturbation. Moreover, the results show how the virtual capacitor concept can be extended to MMCs that are not directly connected to the DC network where the service is provided
Les Vingt ans de la Revue de Philosophie Economique : textes choisis (titre provisoire)
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The user experience of low-techs: from user problems to design principles
No full textInternational audienceOur technological culture is characterized by the development of increasingly complex artefacts. In this article, we introduce “low-techs”, alternative technologies that tend to use fewer resources, target priority needs and aim for a positive social and environmental impact by design. We describe their relevance for user experience researchers and practioners interested in tackling the environmental crises, as well as what actions can be conducted to improve low-techs’ design and dissemination. Finally, from a survey of 396 participants, we derive 14 main user experience problems of low-techs and propose 7 corresponding design principles (Identify priority needs to derive necessary functionality, Strike the right balance between empowerment and assistance, Pay attention to non-functional features, Facilitate discoverability, Make artefact and operation transparent, Develop user technical knowledge and skill, Compensate increased material loads and deficits). These design principles can be used by practitioners to guide the development of low-techs
Remedies and Remedial dynamiques in Climate change Litigation: Opportunities and Challenges
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I-GWAS: Privacy-Preserving Interdependent Genome-Wide Association Studies
No full textInternational audienceGenome-wide Association Studies (GWASes) identify genomic variations that are statistically associated with a trait, such as a disease, in a group of individuals. Unfortunately, careless sharing of GWAS statistics might give rise to privacy attacks. Several works attempted to reconcile secure processing with privacy-preserving releases of GWASes. However, we highlight that these approaches remain vulnerable if GWASes utilize overlapping sets of individuals and genomic variations. In such conditions, we show that even when relying on state-of-the-art techniques for protecting releases, an adversary could reconstruct the genomic variations of up to 28.6% of participants, and that the released statistics of up to 92.3% of the genomic variations would enable membership inference attacks. We introduce I-GWAS, a novel framework that securely computes and releases the results of multiple possibly interdependent GWASes. I-GWAS continuously releases privacy-preserving and noise-free GWAS results as new genomes become available
Impact of Al2O3, TiO2 and ZnO addition on the crystallization of Yb3+ doped phosphate glass-ceramic
No full textInternational audienceNew Yb 3+-doped phosphate glasses with a composition of (98.75-x) (90 NaPO 3-10 Na 2 O)-x (Al 2 O 3 , TiO 2 , or ZnO)-1.25 Yb 2 O 3 (in mol-%), with x from 0 to 3, were prepared via conventional melting and quenching process. The thermal and physical properties were studied by differential thermal analysis (DTA) and density measurement, respectively. The glass structure was investigated using visible/infrared spectroscopy and the crystallization properties of the glasses using XRD. Changes in the glass composition were found to have an impact on the glass structure and more importantly on the crystallization process; the addition of Al 2 O 3 , TiO 2 and ZnO promotes the precipitation of the Na 5 P 3 O 10 crystalline phase at the expense of NaYb(P 2 O 7) and NaPO 3 phases and more importantly, promotes surface crystallization at the expense of bulk crystallization
Asphaltenes, subfractions A1 and A2 aggregation and adsorption onto RH-SiO 2 nanoparticles: solvent effect on the aggregate size
No full textInternational audienceThe aggregation and adsorption of asphaltenes in dilute solutions has been extensively studied and is now well established. At low concentrations, asphaltenes are mainly found in the form of aggregates of approximately 3 nm in size. One strategy to simplify the study of these systems has been to fractionate the asphaltenes into subfractions called A1 and A2. The nature of these subfraction aggregates, their behavior with the concentration and their interaction with other aggregates and surfaces remain under debate. This work presents experimental results on the aggregation and adsorption of asphaltenes and their subfractions A1 and A2 onto SiO2 nanoparticles from rice husks (RH-SiO2), and the evidence allows us to infer that the aggregates are in equilibrium in solution over a wide range of concentrations. The size distribution for each subfraction does not change with dilution but is sensitive to solvent media. Subfraction A1 has a very similar behavior to asphaltenes, while subfraction A2 tends to form larger aggregates. Larger aggregates more likely adsorb on surfaces than small aggregates. According to the results, the interaction of the aggregates in different solvents can be studied as a phase change phenomenon, where the aggregate can be considered a partially immiscible phase in a solvent. The theoretical principles are described, and a hypothesis is elaborated in these terms
