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Wyszukujesz frazę "Sanchez-Lasheras, F." wg kryterium: Wszystkie pola


Wyświetlanie 1-2 z 2
Tytuł:
A Statistical Approach To Prediction Of The CMM Drift Behaviour Using A Calibrated Mechanical Artefact
Autorzy:
Cuesta, E.
Alvarez, B.
Sanchez-Lasheras, F.
Gonzalez-Madruga, D.
Powiązania:
https://bibliotekanauki.pl/articles/221090.pdf
Data publikacji:
2015
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
multivariate regression models
coordinate measuring machine
drift behaviour
calibration
Opis:
This paper presents a multivariate regression predictive model of drift on the Coordinate Measuring Machine (CMM) behaviour. Evaluation tests on a CMM with a multi-step gauge were carried out following an extended version of an ISO evaluation procedure with a periodicity of at least once a week and during more than five months. This test procedure consists in measuring the gauge for several range volumes, spatial locations, distances and repetitions. The procedure, environment conditions and even the gauge have been kept invariables, so a massive measurement dataset was collected over time under high repeatability conditions. A multivariate regression analysis has revealed the main parameters that could affect the CMM behaviour, and then detected a trend on the CMM performance drift. A performance model that considers both the size of the measured dimension and the elapsed time since the last CMM calibration has been developed. This model can predict the CMM performance and measurement reliability over time and also can estimate an optimized period between calibrations for a specific measurement length or accuracy level.
Źródło:
Metrology and Measurement Systems; 2015, 22, 3; 417-428
0860-8229
Pojawia się w:
Metrology and Measurement Systems
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Forecasting European thermal coal spot prices
Autorzy:
Krzemień, A.
Riesgo Fernandez, P.
Suárez Sánchez, A.
Sánchez Lasheras, F.
Powiązania:
https://bibliotekanauki.pl/articles/92159.pdf
Data publikacji:
2015
Wydawca:
Główny Instytut Górnictwa
Tematy:
thermal coal
price forecasting
time series analysis
neural network
autoregressive model
węgiel energetyczny
prognoza cen
analiza szeregów czasowych
sieć neuronowa
model autoregresyjny
Opis:
This paper presents a one-year forecast of European thermal coal spot prices by means of time series analysis, using data from IHS McCloskey NW Europe Steam Coal marker (MCIS). The main purpose was to achieve a good fit for the data using a quick and feasible method and to establish the transformations that better suit this marker, together with an affordable way for its validation. Time series models were selected because the data showed an autocorrelation systematic pattern and also because the number of variables that influence European coal prices is very large, so forecasting coal prices as a dependent variable makes necessary to previously forecast the explanatory variables. A second-order Autoregressive process AR(2) was selected based on the autocorrelation and the partial autocorrelation function. In order to determine if the results obtained are a good fit for the data, the possible drivers that move the European thermal coal spot prices were taken into account, establishing a hypothesis in which they were divided into four categories: (1) energy side drivers, that directly relates coal prices with other energy commodities like oil and natural gas; (2) demand side drivers, that relates coal prices both with the Western World economy and with emerging economies like China, in connection with the demand for electricity in these economies; (3) commodity currency drivers, that have an influence for holders of different commodity currencies in countries that export or import coal; and (4) supply side drivers, involving the production costs, transportation, etc. Finally, in order to analyse the time series model performance a Generalized Regression Neural Network (GRNN) was used and its performance compared against the whole AR(2) process. Empirical results obtained confirmed that there is no statistically significant difference between both methods. The GRNN analysis also allowed pointing out the main drivers that move the European Thermal Coal Spot prices: crude oil, USD/CNY change and supply side drivers.
Źródło:
Journal of Sustainable Mining; 2015, 14, 4; 203-210
2300-1364
2300-3960
Pojawia się w:
Journal of Sustainable Mining
Dostawca treści:
Biblioteka Nauki
Artykuł
    Wyświetlanie 1-2 z 2

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