We have studied the products of alteration of sulfides contained in the tailings of a former tungsten mine at Enguialès, Aveyron, France. Most of these products are poorly crystalline and contain high concentrations of arsenic. A preliminary classification based on visual observations was carried out, and five products were distinguished according to their color and texture. The data obtained b...

Abstract Chemical compositional data sets of archaeological artefacts are often analysed using standard statistical procedures. Adopting a different approach, we examine the major element oxides found in Parthian and Sasanian glazed pottery by identifying statistically important ratios conjunction with expert knowledge scientist during, rather than after, identification process. This results me...

analysis of time series data can involve the inversion of large covariance matrices. for theclass of arma (p, q) processes there are no exact explicit expressions for these inverses, except for thema (1) process. in practice, the sample covariance matrix can be very large and inversion can becomputationally time consuming and so approximate explicit expressions for the inverse are desirable.thi...

‎the global fom and gmres algorithms are among the effective‎ ‎methods to solve sylvester matrix equations‎. ‎in this paper‎, ‎we‎ ‎study these algorithms in the case that the coefficient matrices‎ ‎are real symmetric (real symmetric positive definite) and extract‎ ‎two cg-type algorithms for solving generalized sylvester matrix‎ ‎equations‎. ‎the proposed methods are iterative projection metho...

let and be a sequence with non-negative entries. if , denote by the infimum of those satisfying the following inequality: whenever . the purpose of this paper is to give an upper bound for the norm of operator t on weighted sequence spaces d(w,p) and lp(w) and also e(w,?). we considered this problem for certain matrix operators such as norlund, weighted mean, ceasaro and copson matrices. th...

The development of John Aitchison’s approach to compositional data analysis is followed since his paper read the Royal Statistical Society in 1982. logratio approach, which was proposed solve problematic aspects working with a fixed-sum constraint, summarized and reappraised. It maintained that properties on this originally built, main one being subcompositional coherence, are not required be s...