Six Sigma

Résumé

Six Sigma ou 6 Sigma est une marque déposée de Motorola désignant une méthode structurée de management visant à une amélioration de la qualité et de l'efficacité des processus. La méthode a d’abord été appliquée à des processus industriels avant d’être élargie à tous les types de processus, notamment administratifs, logistiques, commerciaux et d'économie d'énergie. Au début des années 2000, elle connaît un essor en raison de la complexité des organisations et de l'internationalisation des processus qui impose une vision mondiale des problèmes. La méthode Six Sigma repose à la fois sur des enquêtes (la voix du client) et sur des données mesurables et fiables (les indicateurs). Elle est utilisée pour réduire la variabilité dans les processus de production et les produits de façon à améliorer la qualité globale des produits et des services. Histoire L’histoire de Six Sigma débute en 1986 chez Motorola, qui cherche à mettre en place une méthode pour améliorer ses processus d

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https://fr.wikipedia.org/wiki/Six_Sigma

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Let xi(t, x) denote space-time white noise and consider a reaction-diffusion equation of the form (t, x) = 1/2u ''(t, x) + b(u(t, x)) + sigma(u(t,x))xi(t,x) on R+ x [0, 1], with homogeneous Dirichlet boundary conditions and suitable initial data, in the case that there exists epsilon > 0 such that vertical bar b(z)vertical bar >= vertical bar z vertical bar (log vertical bar z vertical bar)(1+epsilon) for all sufficiently-large values of vertical bar z vertical bar. When sigma equivalent to 0, it is well known that such PDEs frequently have nontrivial stationary solutions. By contrast, Bonder and Groisman [Phys. D 238 (2009) 209-215] have recently shown that there is finite-time blowup when sigma is a nonzero constant. In this paper, we prove that the Bonder-Groisman condition is unimprovable by showing that the reaction-diffusion equation with noise is "typically" well posed when vertical bar b(z)vertical bar =O(vertical bar vertical bar z vertical bar log(+) vertical bar z vertical bar) as vertical bar z vertical bar -> infinity. We interpret the word "typically" in two essentially-different ways without altering the conclusions of our assertions.

INST MATHEMATICAL STATISTICS2019

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Cosmological implications of the full shape of anisotropic clustering measurements in BOSS and eBOSS

Cheng Zhao

We present the analysis of the full shape of anisotropic clustering measurement from the extended Baryon Oscillation Spectroscopic Survey (eBOSS) quasar sample together with the combined galaxy sample from the Baryon Oscillation Spectroscopic Survey (BOSS), re-analysed using an updated recipe for the non-linear matter power spectrum and the non-local bias parameters. We obtain constraints for flat Lambda cold dark matter cosmologies, focusing on the cosmological parameters that are independent of the Hubble parameter h. Our recovered value for the Root Mean Square (RMS) linear perturbation theory variance as measured on the scale of 12 Mpc is sigma(12) = 0.805 +/- 0.049, while using the traditional reference scale of 8 h(-1) Mpc gives sigma(8) = 0.815 +/- 0.044. We quantify the agreement between our measurements and the latest cosmic microwave background data from Planck using the suspiciousness metric, and find them to be consistent within 0.64 +/- 0.03 sigma. Combining our clustering constraints with the 3 x 2pt data sample from the Dark Energy Survey Year 1 release slightly degrades this agreement to the level of 1.54 +/- 0.08 sigma, while still showing an overall consistency with Planck. We furthermore study the effect of imposing a Planck - like prior on the parameters that define the shape of the linear matter power spectrum, and find significantly tighter constraints on the parameters that control the evolution of density fluctuations. In particular, the combination of low-redshift data sets prefers a value of the physical dark energy density omega(DE) = 0.335 +/- 0.011, which is 1.7 sigma higher than the one preferred by Planck.

OXFORD UNIV PRESS2022

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Searching for decaying dark matter in deep XMM-Newton observation of the Draco dwarf spheroidal

Alexey Boyarsky, Andrii Neronov, Oleg Ruchayskiy

We present results of a search for the 3.5 keV emission line in our recent very long (similar to 1.4 Ms) XMM-Newton observation of the Draco dwarf spheroidal galaxy. The astrophysical X-ray emission from such dark matter-dominated galaxies is faint, thus they provide a test for the dark matter origin of the 3.5 keV line previously detected in other massive, but X-ray bright objects, such as galaxies and galaxy clusters. We do not detect a statistically significant emission line from Draco; this constrains the lifetime of a decaying dark matter particle to tau > (7-9) x 10(27) s at 95 per cent CL (combining all three XMM-Newton cameras; the interval corresponds to the uncertainty of the dark matter column density in the direction of Draco). The PN camera, which has the highest sensitivity of the three, does show a positive spectral residual (above the carefully modelled continuum) at E = 3.54 +/- A 0.06 keV with a 2.3 sigma significance. The two MOS cameras show less-significant or no positive deviations, consistently within 1 sigma with PN. Our Draco limit on tau is consistent with previous detections in the stacked galaxy clusters, M31 and the Galactic Centre within their 1 - 2 sigma uncertainties, but is inconsistent with the high signal from the core of the Perseus cluster (which has itself been inconsistent with the rest of the detections). We conclude that this Draco observation does not exclude the dark matter interpretation of the 3.5 keV line in those objects.

Wiley-Blackwell2016

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