Search results for "least squares"
showing 10 items of 268 documents
A kernel regression approach to cloud and shadow detection in multitemporal images
2013
Earth observation satellites will provide in the next years time series with enough revisit time allowing a better surface monitoring. In this work, we propose a cloud screening and a cloud shadow detection method based on detecting abrupt changes in the temporal domain. It is considered that the time series follows smooth variations and abrupt changes in certain spectral features will be mainly due to the presence of clouds or cloud shadows. The method is based on linear and nonlinear regression analysis; in particular we focus on the regularized least squares and kernel regression methods. Experiments are carried out using Landsat 5 TM time series acquired over Albacete (Spain), and compa…
Determination of the energetic value of fruit and milk-based beverages through partial-least-squares attenuated total reflectance-Fourier transform i…
2005
Abstract The estimation of important nutritional parameters, such as carbohydrates content and energetic value (calories) in commercially available fruit juice and flavour milk shakes has been made by attenuated total reflectance-Fourier transform infrared spectroscopy (ATR-FTIR) using a partial-least-square (PLS) calibration approach. A highly heterogeneous population of 65 samples obtained from the Spanish market, covering fruit juices, flavour milk shakes and milk-added fruit juices was used. The spectral range and the size of the calibration set for building the PLS model have been evaluated. Considering a calibration set comprised of 27 samples, selected via hierarchical cluster analys…
Estuarine sediment quality assessment by Fourier-transform infrared spectroscopy
2010
Partial least squares Fourier-transform infrared (PLS-FTIR) models were developed for the quality assessment of estuarine sediments through the evaluation of several physico-chemical parameters. Models were based on the chemometric treatment of attenuated total reflection (ATR) spectra directly obtained from samples previously lyophilized and sieved through a lower than 63 μm grid. Spectra were scanned from 3997 to 523 cm-1, averaging 36 scans per spectrum with a nominal resolution of 8 cm-1. Models were built using reference data obtained for sediment samples collected from Ria de Arousa estuary. Hierarchical cluster classification of sediment ATR spectra was employed for the establishment…
Comparative modelling study on enantioresolution of structurally unrelated compounds with amylose-based chiral stationary phases in reversed phase li…
2020
[EN] Polysaccharide-based chiral stationary phases (CSPs) are the most used chiral selectors in HPLC. These CSPs can be used in normal, polar organic and aqueous-organic mobile phases. However, normal and polar organic mobile phases are not adequate for chiral separation of polar compounds, for the analysis of aqueous samples and for MS detection. In these situations, reversed phase conditions, without the usual non-volatile additives incompatible with MS detection, are preferable. Moreover, in most of the reported chiral chromatographic methods, retention is too large for routine work. In this paper, the chiral separation of 53 structurally unrelated compounds is studied using three commer…
Value, supplier dependence and long‐term orientation
2011
PurposeIn organizational markets, many companies tend to reduce the number of providers to focus on establishing relationships with few of them. The purpose of this paper is to analyze the influence of relationship value and dependence of supplier on long‐term orientation and customer loyalty in the setting of relationships between travel agencies and their main providers.Design/methodology/approachA partial least square regression is performed to test a proposed model that links several relational variables with outcomes in terms of customer loyalty.FindingsResults provide support for the positive indirect influence of relationship value on long‐term orientation, while customer dependence …
Unlocking behaviors of long-term service consumers : the role of action inertia
2017
Purpose The purpose of this paper is to examine the antecedents of word-of-mouth (WOM) in long-term service settings. Specifically, the authors examine the moderating role of action inertia in the relationships between satisfaction and repatronage intention, satisfaction and WOM, and repatronage intention and WOM. Design/methodology/approach The proposed model was empirically tested using survey data from 1,385 telecommunications service subscribers. The data were analyzed using partial least squares path modeling. Findings Results suggest that a positive link between repatronage intention and WOM, hereto a neglected relationship in the marketing literature, in contrast to previous literat…
Iteratively reweighted least squares in crystal structure refinements
2011
The use of robust techniques in crystal structure multipole refinements of small molecules as an alternative to the commonly adopted weighted least squares is presented and discussed. As is well known, the main disadvantage of least-squares fitting is its sensitivity to outliers. The elimination from the data set of the most aberrant reflections (due to both experimental errors and incompleteness of the model) is an effective practice that could yield satisfactory results, but it is often complicated in the presence of a great number of bad data points, whose one-by-one elimination could become unattainable. This problem can be circumvented by means of a robust least-squares regression that…
Adaptive Feed-Forward Neural Network for Wind Power Delivery
2022
This paper describes a grid connected wind energy conversion system. The interconnecting filter is a simple inductor with a series resistor to minimize three-phase current Total Harmonic Distortion (THD). Using the Recursive Least Squares (RLS) Estimator, an online grid impedance technique is proposed in the stationary reference frame using the Recursive Least Squares (RLS) Estimator. An Adaptive Feedforward Neural (AFN) Controller has also been developed using the inverse of the system to improve the performance of the current Proportional-Integral controller under dynamical conditions and provide better DC link voltage stability. The neural network weights are computed in real-time using …
On invariant manifolds of saddle points for 3D multistable models
2017
In dynamical systems a particular solution is completely determined by the parameters considered and the initial conditions. Indeed, when the model shows a multistability, starting from different initial state, the trajectories can evolve towards different attractors. The invariant manifolds of the saddle points separate the vector field into the basins of attraction of different stable equilibria. The aim of this work is the reconstruction of these separation surfaces in order to know in advance the geometry of the basins. In this paper three-dimensional models with three or more stable fixed points is investigated. To this purpose a procedure for the detection of the scattered data lying …
Nonlinear Distribution Regression for Remote Sensing Applications
2020
In many remote sensing applications, one wants to estimate variables or parameters of interest from observations. When the target variable is available at a resolution that matches the remote sensing observations, standard algorithms, such as neural networks, random forests, or the Gaussian processes, are readily available to relate the two. However, we often encounter situations where the target variable is only available at the group level, i.e., collectively associated with a number of remotely sensed observations. This problem setting is known in statistics and machine learning as multiple instance learning (MIL) or distribution regression (DR). This article introduces a nonlinear (kern…