The main problem in the orbit determination of the space debris population is the correlation of independently observed tracklets, that are sets of observations over a short time. The information contained in such data are not sufficient for a complete determination of an orbit, thus we need to find two or more tracklets belonging to the same physical object and an orbit fitting all the observa...

The CERCHAR abrasivity test is very popular for determination of rock abrasivity. An accurate estimation of the CERCHAR abrasivity index (CAI) is useful for excavation operation costs. This paper presents a model to calculate CAI based on the gene expression programming (GEP) approach. This model is trained and tested based on a database collected from the experimental results available in the ...

The challenging problem of distribution-agnostic linear (weighted) unbiased estimation a global parameter from heterogeneous and unbalanced data is addressed. This setup may originate in different signal processing contexts involving the joint non-homogeneous groups whose statistical distribution unknown, with (possibly highly) diverse sample sizes. Since estimators local variances are inaccura...

A class of semiparametric transformation models is proposed to characterise the effects of possibly time-varying covariates on the intensity functions of counting processes. The class includes the proportional intensity model and linear transformation models as special cases. Nonparametric maximum likelihood estimators are developed for the regression parameters and cumulative intensity functio...

Although several papers have studied no-idle scheduling problems, they all focus on flow shops, assuming one processor at each working stage. But, companies commonly extend to hybrid flow shops by duplicating machines in parallel in stages. This paper considers the problem of scheduling no-idle hybrid flow shops. A mixed integer linear programming model is first developed to mathematically form...

A simple and rapid method has been developed for the determination of ascorbic acid in fruit and pharmaceutical products. The method is based on the measurement of the reaction rate between ammonium molybdate and ascorbic acid in acidic media. The reaction was monitored spectrophotometrically at 800 nm by fixed-time and variable-time methods. The calibration graph was linear in the range of...

Of those things that can be estimated well in an inverse problem, which is best to estimate? Backus–Gilbert resolution theory answers a version of this question for linear (or linearized) inverse problems in Hilbert spaces with additive zero-mean errors with known, finite covariance, and no constraints on the unknown other than the data. This paper generalizes resolution: it defines the resolut...

Survey data are often used to fit linear regression models. The values of covariates used in modeling are not controlled as they might be in an experiment. Thus, collinearity among the covariates is an inevitable problem in the analysis of survey data. Although many books and articles have described the collinearity problem and proposed strategies to understand, assess and handle its presence, ...