排序方式: 共有39条查询结果,搜索用时 15 毫秒
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Alexandra Gaubert Yohann Clement Anne Bonhomme Benjamin Burger Delphine Jouan-Rimbaud Bouveresse Douglas Rutledge Hervé Casabianca Pierre Lanteri Claire Bordes 《Analytica chimica acta》2016
This paper presents the analysis of surfactants in complex mixtures using Raman spectroscopy combined with signal extraction (SE) methods. Surfactants are the most important component in laundry detergents. Both their identification and quantification are required for quality control and regulation purposes. Several synthetic mixtures of four surfactants contained in an Ecolabel laundry detergent were prepared and analyzed by Raman spectroscopy. SE methods, Independent Component Analysis and Multivariate Curve Resolution, were then applied to spectral data for surfactant identification and quantification. The influence of several pre-processing treatments (normalization, baseline correction, scatter correction and smoothing) on SE performances were evaluated by experimental design. By using optimal pre-processing strategy, SE methods allowed satisfactorily both identifying and quantifying the four surfactants. When applied to the pre-processed Raman spectrum of the Ecolabel laundry detergent sample, SE models remained robust enough to predict the surfactant concentrations with sufficient precision for deformulation purpose. Comparatively, a supervised modeling technique (PLS regression) was very efficient to quantify the four surfactants in synthetic mixtures but appeared less effective than SE methods when applied to the Raman spectrum of the detergent sample. PLS seemed too sensitive to the other components contained in the laundry detergent while SE methods were more robust. The results obtained demonstrated the interest of SE methods in the context of deformulation. 相似文献
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Sergio Alvarez-Andrade N. Balakrishnan Laurent Bordes 《Annals of the Institute of Statistical Mathematics》2009,61(4):887-903
This paper proposes an inferential method for the semiparametric proportional hazards model for progressively Type-II censored
data. We establish martingale properties of counting processes based on progressively Type-II censored data that allow to
derive the asymptotic behavior of estimators of the regression parameter, the conditional cumulative hazard rate functions,
and the conditional reliability functions. A Monte Carlo study and an example are provided to illustrate the behavior of our
estimators and to compare progressive Type-II censoring sampling plans with classical Type-II right censoring sampling plan. 相似文献
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In this paper we consider a two-component mixture model, one component of which has a known distribution while the other is
only known to be symmetric. The mixture proportion is also an unknown parameter of the model. This mixture model class has
proved to be useful to analyze gene expression data coming from microarray analysis. In this paper a general estimation method
is proposed leading to a joint central limit result for all the estimators. Applications to basic testing problems related
to this class of models are proposed, and the corresponding inference procedures are illustrated through some simulation studies. 相似文献
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Mixture models in reliability bring a useful compromise between parametric and nonparametric models, when several failure modes are suspected. The classical methods for estimation in mixture models rarely handle the additional difficulty coming from the fact that lifetime data are often censored, in a deterministic or random way. We present in this paper several iterative methods based on EM and Stochastic EM methodologies, that allow us to estimate parametric or semiparametric mixture models for randomly right censored lifetime data, provided they are identifiable. We consider different levels of completion for the (incomplete) observed data, and provide genuine or EM-like algorithms for several situations. In particular, we show that simulating the missing data coming from the mixture allows to plug a standard R package for survival data analysis in an EM algorithm’s M-step. Moreover, in censored semiparametric situations, a stochastic step is the only practical solution allowing computation of nonparametric estimates of the unknown survival function. The effectiveness of the new proposed algorithms are demonstrated in simulation studies and an actual dataset example from aeronautic industry. 相似文献
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J. Bordes Hong-Mo Chan Sheung Tsun Tsou 《The European Physical Journal C - Particles and Fields》1999,10(1):63-70
We show that, if one assumes fermion generations to be given by a gauge symmetry, together with a certain Higgs mechanism
for breaking it, then the known empirical features of quark and lepton mixing can be largely explained, including, in particular,
the fact that the mixing (CKM) matrix element , responsible for the muon anomaly in atmospheric neutrinos, is near maximal, and much larger than its quark counterparts
and , while the corner elements for both quarks () and leptons () are all very small. The mechanism also automatically gives a hierarchical fermion-mass spectrum which is intimately related
to the mixing pattern.
Received: 8 February 1999 / Published online: 15 July 1999 相似文献
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