Segregation effects in processes handling powder mixture

3 pages Conférence InvitéeThe handling of particles is a general operation concerning a great number of industries for which a process implies a treatment of matter or material: foods, pharmaceutical, cosmetics, chemical. This represents 60-70% of the processes. The materials can be of any type, mineral, organic. The handling of materials is just a transfer from a place to another one, thanks to different devices by operating under different conditions. This insures the transfer of particles from trucks to a bin or from a bin to the unit where the transformation of particles will occur, for example from mixer to bin, or bin to die where compaction or tabletting will occur, or bin to bags

Needlet algorithms for estimation in inverse problems

We provide a new algorithm for the treatment of inverse problems which combines the traditional SVD inversion with an appropriate thresholding technique in a well chosen new basis. Our goal is to devise an inversion procedure which has the advantages of localization and multiscale analysis of wavelet representations without losing the stability and computability of the SVD decompositions. To this end we utilize the construction of localized frames (termed "needlets") built upon the SVD bases. We consider two different situations: the "wavelet" scenario, where the needlets are assumed to behave similarly to true wavelets, and the "Jacobi-type" scenario, where we assume that the properties of the frame truly depend on the SVD basis at hand (hence on the operator). To illustrate each situation, we apply the estimation algorithm respectively to the deconvolution problem and to the Wicksell problem. In the latter case, where the SVD basis is a Jacobi polynomial basis, we show that our scheme is capable of achieving rates of convergence which are optimal in the $L_2$ case, we obtain interesting rates of convergence for other $L_p$ norms which are new (to the best of our knowledge) in the literature, and we also give a simulation study showing that the NEED-D estimator outperforms other standard algorithms in almost all situations.Comment: Published at http://dx.doi.org/10.1214/07-EJS014 in the Electronic Journal of Statistics (http://www.i-journals.org/ejs/) by the Institute of Mathematical Statistics (http://www.imstat.org

Agri-Food Trade Between 1992 and 2002,

The long phase of increasing agri-food exports came to an end during the 1990s. However, Frances weakened position was not just the simple consequence of the CAP reforms and the gradual liberalisation of world trade. Frances decreasing market shares resulted from increased competition from Germany and Spain, and from traditional exporters (Australia, Brazil) or new exporters (Russia, Ukraine, Thailand) from outside the EU. Excluding drinks, the surplus had more than halved between the start of the 1990s and the middle of the 2000s. Frances prospects on the world markets seem to have been weakened because of its concentration on products where the price remains or becomes the competitive criterion, whether they are less processed products (cereals, sugar, poultry meat), or more processed products, such as wine. Conversely, the improved performance of second transformation agri-food products, particularly the gains made on the EU market during 1992, are strengthening Frances positions.Agrifood Trade, Market Share, Agricultural Policy

Recipe theorem for the Tutte polynomial for matroids, renormalization group-like approach

Using a quantum field theory renormalization group-like differential equation, we give a new proof of the recipe theorem for the Tutte polynomial for matroids. The solution of such an equation is in fact given by some appropriate characters of the Hopf algebra of isomorphic classes of matroids, characters which are then related to the Tutte polynomial for matroids. This Hopf algebraic approach also allows to prove, in a new way, a matroid Tutte polynomial convolution formula appearing in W. Kook {\it et. al., J. Comb. Series} {\bf B 76} (1999).Comment: 14 pages, 3 figure

Selenium persistency and speciation in the tissues of lambs following the withdrawal of dietary high-dose selenium-enriched yeast

The objective was to determine the concentration of total selenium (Se) and the proportion of total Se comprised as selenomethionine (SeMet) and selenocysteine (SeCys) in post mortem tissues of lambs in the six weeks period following the withdrawal of a diet containing high dose selenized yeast (SY), derived from a specific strain of Saccharomyces cerevisae CNCM (Collection Nationale de Culture de Micro-organism) I-3060. Thirty Texel x Suffolk lambs used in this study had previously received diets (91 days) containing either high dose SY (HSY; 6.30 mg Se/kg DM) or an unsupplemented control (C; 0.13 mg Se/kg DM). Following the period of supplementation all lambs were then offered a complete pelleted diet, without additional Se (0.15 mg Se/kg DM), for 42 days. At enrollment and 21 and 42 days later, five lambs from each treatment were blood sampled, euthanased and samples of heart, liver, kidney and skeletal muscle (Longissimus Dorsi and Psoas Major) tissue were retained. Total Se concentration in whole blood and tissues was significantly (P < 0.001) higher in HSY lambs at all time points that had previously received long term exposure to high dietary concentrations of SY. The distribution of total Se and the proportions of total Se comprised as SeMet and SeCys differed between tissues, treatment and time points. Total Se was greatest in HSY liver and kidney (22.64 and 18.96 mg Se/kg DM, respectively) and SeCys comprised the greatest proportion of total Se. Conversely, cardiac and skeletal muscle (Longissimus Dorsi and Psoas Major) tissues had lower total Se concentration (10.80, 7.02 and 7.82 mg Se/kg DM, respectively) and SeMet was the predominant selenized amino acid. Rates of Se clearance in HSY liver (307 µg Se/day) and kidney (238 µg Se/day) were higher compared with HSY cardiac tissue (120 µg Se/day) and skeletal muscle (20 µg Se/day). In conclusion differences in Se clearance rates were different between tissue types, reflecting the relative metabolic activity of each tissue, and appear to be dependant upon the proportions of total Se comprised as either SeMet or SeCys

An approach to anomalous diffusion in the n-dimensional space generated by a self-similar Laplacian

We analyze a quasi-continuous linear chain with self-similar distribution of harmonic interparticle springs as recently introduced for one dimension (Michelitsch et al., Phys. Rev. E 80, 011135 (2009)). We define a continuum limit for one dimension and generalize it to $n=1,2,3,..$ dimensions of the physical space. Application of Hamilton's (variational) principle defines then a self-similar and as consequence non-local Laplacian operator for the $n$-dimensional space where we proof its ellipticity and its accordance (up to a strictly positive prefactor) with the fractional Laplacian $-(-\Delta)^\frac{\alpha}{2}$. By employing this Laplacian we establish a Fokker Planck diffusion equation: We show that this Laplacian generates spatially isotropic L\'evi stable distributions which correspond to L\'evi flights in $n$-dimensions. In the limit of large scaled times $\sim t/r^{\alpha} >>1$ the obtained distributions exhibit an algebraic decay $\sim t^{-\frac{n}{\alpha}} \rightarrow 0$ independent from the initial distribution and spacepoint. This universal scaling depends only on the ratio $n/\alpha$ of the dimension $n$ of the physical space and the L\'evi parameter $\alpha$.Comment: Submitted manuscrip

Supply chain management simulation: an overview

Synthesis of Vendome team research works (team belonging to GDR MACS - CNRS)Chapter 1 : Supply chain management simulation: an overvie

Etude expérimentale de la dissolution des matrices hydrophiles complexes à base d'hypromellose et de principes actifs

National audienceL'influence de l'hypromellose ainsi que des liants sur le relargage du principe actif dans les matrices hydrophiles a été largement étudié. Mais ces études se limitent à des systèmes binaires (hypromellose et principe actif) ou ternaires (hypromellose, principe actif et liant). De plus, l'utilisation dans les formulations de mélanges d'hypromellose est assez peu étudiée. Aussi une étude de la cinétique de dissolution de comprimés à libération retardée issus de mélange de complexité croissante a été entreprise. En effet, l'adjonction de l'hypromellose au principe actif dans une formulation permet d'avoir une libération retardée. Mais généralement la formulation d'un comprimé pharmaceutique est bien plus complexe avec la présence de liant et de charge. Ce travail a permis d'essayer d les influences relatives des excipients sur les profils de libération du principe actif