Ricerc@Sapienza

The concept of orthogonalized partial least squares regression or, better, as it was originally named, orthogonalized projection to latent structures (O-PLS) was first introduced in 2001 by Johann Trygg and Svante Wold, as a way to deal with the large amount of variation in predictor matrices for multivariate calibration (and classification), not correlated to the responses. In this context, O-PLS operates by partitioning the systematic variance in the X block into a Y relevant and an orthogonal data sets, both having a bilinear structure.

The main national institutes of statistics use calibration estimator (Deville e Särndal, 1992; Särndal, 2007). During the years the numbers of auxiliary totals considered in calibration is strongly increased. Because of this, two main problems arise. Very often there is failure to identify "calibrated" weights and, furthermore, the variability of “calibrated” weights can make the efficiency of estimates worse. Therefore, the choice of auxiliary variables in calibration is of a greatest importance.

In this paper, a class of resampling techniques for finite populations under pps sampling design is introduced. The basic idea on which they rest is a two-step procedure consisting in: (i) constructing a pseudo-population" on the basis of sample data; (ii) drawing a sample from the predicted population according to an appropriate resampling design. From a logical point of view, this approach is essentially based on the plug-in principle by Efron, at the "sampling design level". Theoretical justifications based on large sample theory are provided.

Un confronto tra differenti costruzioni in ℍ^2 ≅ ℝ^8 della 4-forma quaternionale Φ_{Sp(2)Sp(1)} e della calibrazione di Cayley Φ_{Spin(7)} mostra che per esse si può partire dalle “2-forme di Kähler”, che entrano sia in geometria quaternionale kähleriana che Spin(7). Tale confronto si collega con le nozioni di struttura di Clifford pari e di sistema di Clifford.

Research in passive radar has moved its focus towards passive radar on moving platforms in recent years with the purpose of moving target indication and ground imaging via synthetic aperture radar. This is also fostered by the progress in hardware miniaturization, which alleviates the installation of the required hardware on moving platforms. Terrestrial transmitters, commonly known as illuminators of opportunity in the passive radar community, usually emit the signals in the Very High Frequency (VHF) or Ultra High Frequency (UHF) band.

Energy reduction can benefit from the improvement of energy efficiency in buildings. For this purpose, simulation models can be used both as diagnostic and prognostic tools, reproducing the behaviour of the real building as accurately as possible. High modelling accuracy can be achieved only through calibration. Two approaches can be adopted-manual or automatic. Manual calibration consists of an iterative trial and error procedure that requires high skill and expertise of the modeler.

The contribution of chemometrics to important stages throughout the entire analytical process such as experimental design, sampling, and explorative data analysis, including data pretreatment and fusion, was described in the first part of the tutorial “Chemometrics in analytical chemistry.” This is the second part of a tutorial article on chemometrics which is devoted to the supervised modeling of multivariate chemical data, i.e., to the building of calibration and discrimination models, their quantitative validation, and their successful applications in different scientific fields.

Calibrating a classification system consists in transforming the output scores, which somehow state the confidence of the classifier regarding the predicted output, into proper probability estimates. Having a well-calibrated classifier has a non-negligible impact on many real-world applications, for example decision making systems synthesis for anomaly detection/fault prediction. In such industrial scenarios, risk assessment is certainly related to costs which must be covered.

Ground Penetrating Radar (GPR) systems shall be periodically calibrated and
their performance verified, in accordance with the recommendations and
specifications of the manufacturer. Nevertheless, most GPR owners in Europe
employ their instrumentation for years without ever having it checked by the
manufacturer, unless major flaws or problems become evident, according to the
results of a survey carried out in the context of COST (European Cooperation in
Science and Technology) Action TU1208 “Civil engineering applications of

This paper addresses the problem of direct signal interference (DSI) and clutter cancellation for passive radar systems on moving platforms using displaced phase centre antenna (DPCA) approach in the presence of receive channels imbalance. First, we show that using the signal emitted by the illuminator of opportunity as a source for channels calibration might be ineffective when DSI and clutter echoes have different directions of arrival. Then, a calibration approach is presented, based on supervised selection of clutter areas in the range-Doppler map.