107 research outputs found
Finite Mixture Models for an underlying Beta distribution with an application to COVID-19 data
IdentiïŹability of Finite Mixture Models with underlying Normal Distribution
In this paper, we show under which conditions generalized ïŹnite mixture with underlying normal distribution are identiïŹable in the sense that a given dataset leads to a uniquely determined set of model parameter estimations up to a permuta-tion of the clusters
Sub-micro a-C:H patterning of silicon surfaces assisted by atmospheric-pressure plasma-enhanced chemical vapor deposition
International audienceMicro and nano-patterning of surfaces is an increasingly popular challenge in the field of the miniaturization of devices assembled via top-down approaches. This study demonstrates the possibility of depositing sub-micrometric localized coatings-spots, lines or even more complex shapes-made of amorphous hydrogenated carbon (a-C:H) thanks to a moving XY stage. Deposition was performed on silicon substrates using chemical vapor deposition assisted by an argon atmospheric-pressure plasma jet. Acetylene was injected into the post-discharge region as a precursor by means of a glass capillary with a sub-micrometric diameter. A parametric study was carried out to study the influence of the geometric configurations (capillary diameter and capillary-plasma distance) on the deposited coating. Thus, the patterns formed were investigated by scanning electron microscopy and atomic force microscopy. Furthermore, the chemical composition of large coated areas was investigated by Fourier transform infrared spectroscopy according to the chosen atmospheric environment. The observed chemical bonds show that reactions of the gaseous precursor in the discharge region and both chemical and morphological stability of the patterns after treatment are strongly dependent on the surrounding gas. Various sub-micrometric a-C:H shapes were successfully deposited under controlled atmospheric conditions using argon as inerting gas. Overall, this new process of micro-scale additive manufacturing by atmospheric plasma offers unusually high-resolution at low cost
Interaction of (3-Aminopropyl)triethoxysilane With Late Ar-N 2 Afterglow: Application to Nanoparticles Synthesis
International audienceFrom results of in situ FTIR absorption and optical emission spectroscopy, the interaction of (3âaminopropyl)triethoxysilane (APTES) with late Ar-N2 afterglow is shown to occur mainly with N atoms. They react preferentially with carbon from CHx groups in the precursor, leading to the synthesis of CN bonds. No production of NH radical is observed, demonstrating the lack of direct reaction between active nitrogen and APTES. The -NH2 group is not affected by the afterglow. One of the C-C bonds of the propylamine group in the APTES is likely broken. These nanoparticles present secondary amides due to reactions with active nitrogen. They are amorphous and react in air to produce a salt
Hubbert's Oil Peak Revisited by a Simulation Model
As conventional oil reserves are declining, the debate on the oil production peak has become a burning issue. An increasing number of papers refer to Hubbert's peak oil theory to forecast the date of the production peak, both at regional and world levels. However, in our views, this theory lacks microeconomic foundations. Notably, it does not assume that exploration and production decisions in the oil industry depend on market prices. In an attempt to overcome these shortcomings, we have built an adaptative model, accounting for the behavior of one agent, standing for the competitive exploration-production industry, subjected to incomplete but improving information on the remaining reserves. Our work yields challenging results on the reasons for an Hubbert type peak oil, lying mainly "above the ground", both at regional and world levels, and on the shape of the production and marginal cost trajectories.
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