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Wyszukujesz frazę "seemingly unrelated regression" wg kryterium: Temat


Wyświetlanie 1-2 z 2
Tytuł:
Predicting parameters of Weibull probability density function for diametric distributions in A. melanoxylon, E. camaldulensis and E. nitens bioenergy plantation
Autorzy:
Sandoval, S.
Cancino, J.
Acuña, E.
Rubilar, R.
Powiązania:
https://bibliotekanauki.pl/articles/2078270.pdf
Data publikacji:
2021
Wydawca:
Polska Akademia Nauk. Instytut Dendrologii PAN
Tematy:
Short-rotation crops
stocking
seemingly unrelated regression
parameters recovery
biomass
and bioenergy
Opis:
Precise modeling of stand diameter distributions is required to provide accurate estimates of volume per diameter class and unit area. Therefore, it is necessary to obtain the most accurate probability density functions parameters estimates to predict stand diameter distribution in time. We evaluate two methods to estimate the parameters of the Weibull probability density function in the modeling of diameter distributions of bioenergy plantations. The methods considered a direct method of parameter prediction based on regression models (PPRM) and an indirect method of parameter recovery through the determi- nation of percentiles (PRDP). Both methods are considered systems of linear equations and are adjusted through simultaneous estimation of parameters using stand variables. The greatest precision was obtained with PPRM. The PRDP method was not effective in the prediction of diameter distributions due to the high level of truncation of the observed distributions showing an overestimation of the distribution for the largest diameter classes. Estimated parameters of the Weibull PDF are directly related to mean height, quadratic mean diameter, and crop age; and are inversely related to stocking
Źródło:
Dendrobiology; 2021, 86; 8-18
1641-1307
Pojawia się w:
Dendrobiology
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Uproszczone wzory empiryczne do określania suchej biomasy nadziemnej części drzew i ich komponentów dla sosny zwyczajnej
Simplified empirical formulas to determine the dry biomass of aboveground components of trees for Scots pine
Autorzy:
Bronisz, K.
Zasada, M.
Powiązania:
https://bibliotekanauki.pl/articles/989260.pdf
Data publikacji:
2016
Wydawca:
Polskie Towarzystwo Leśne
Tematy:
lesnictwo
drzewa lesne
sosna zwyczajna
Pinus sylvestris
biomasa nadziemna
obliczenia
wzory empiryczne
wzory uproszczone
piersnice drzew
allometric equation
scots pine
biomass
seemingly unrelated regression
Opis:
So−far developed and published Polish equations for determination of aboveground biomass of Scots pine are based on two predictors: diameter at the breast height (DBH) and tree height. The main goal of the presented study were i) to build the simplified empirical biomass equations that use exclusively DBH as the independent variable, and ii) to compare the obtained results with values from equations based on both predictors (optimal model). The empirical material consisted of biomass data for 90 Scots pines growing on typical habitats in Bory Lubuskie (western Poland). The elaborated equations have a lower accuracy than the optimal ones. The R² value for all biomass components is higher than 0.69, and reaches as much as 0.976 in the case of dry wood biomass. The root mean square error (RMSE) for such components as dry biomass of bark and alive or dead branches and branches with needles is lower for the simplified model. However, for the dry wood biomass the optimal model has lower RMSE value. Because this component has the largest share in the total aboveground tree biomass (AGB), the resulting RMSE for the AGB is lower than for the optimal model. Optimal model is also more accurate when the mean error is considered. The simplified model can be used when there are no height measurement available or there is an anxiety that the use of height−diameter models significantly increases the uncertainty of results.
Źródło:
Sylwan; 2016, 160, 04; 277-283
0039-7660
Pojawia się w:
Sylwan
Dostawca treści:
Biblioteka Nauki
Artykuł
    Wyświetlanie 1-2 z 2

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