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Wyszukujesz frazę "Gmelina arborea" wg kryterium: Temat

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    Wyświetlanie 1-4 z 4
    Tytuł:
    Estimating parameters of the Weibull diameter distribution for Gmelina arborea in Nimbia Forest Reserve, Nigeria
    Autorzy:
    Shamaki, S. B.
    Akindele, S. O.
    Marshall, P. L.
    LeMay, V. M.
    Powiązania:
    https://bibliotekanauki.pl/articles/1075794.pdf
    Data publikacji:
    2019
    Wydawca:
    Przedsiębiorstwo Wydawnictw Naukowych Darwin / Scientific Publishing House DARWIN
    Tematy:
    Gmelina arborea
    Nimbia Forest Reserve
    Weibull distribution
    Opis:
    Parameters of the Weibull diameter distribution were estimated for Gmelina (Gmelina arborea) plantation in Nimbia Forest Reserve. Stratified random sampling was employed to select five plots of 20 × 20 m from each forest bit that serves as management unit, thereby having a total of 20 plots for the study. Stump diameter (Dst), diameter at breast height (Dbh), diameter at middle and top positions (Dm and Dt) of trees, and tree height for all the selected trees were measured. Average Dbh measured was 16.33 cm and the mean tree height 6.85 m. Pseudo coefficient of determination (Pseudo R2), residual mean square error, Anderson-Darling, and Kolmogorov-Smirnov goodness-of-fit statistics were considered as model selection criteria. Weibull cumulative density function (Weibull-CDF) was the best fit method for Gmelina compared with the Weibull probability density function based on the goodness-of-fit statistics generated. The diameter distribution models produced are considered only efficient for tree stands of seven years rotation age, while additional site factors like spacing, density and silvicultural treatments are required for better models, hence the need for establishing permanent sample plots (PSP) in order to get additional information from re-measurements of the plots.
    Źródło:
    World Scientific News; 2019, 118; 209-219
    2392-2192
    Pojawia się w:
    World Scientific News
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Non-Linear Regression Models for Volume Estimation of Gmelina arborea (Roxb.) in Uyo Ravine Plantation, Akwa Ibom State, Nigeria
    Autorzy:
    Oyebade, B. A.
    Aigbe, H. I.
    Eguakun, F. S.
    Edem, M. A.
    Powiązania:
    https://bibliotekanauki.pl/articles/1030779.pdf
    Data publikacji:
    2020
    Wydawca:
    Przedsiębiorstwo Wydawnictw Naukowych Darwin / Scientific Publishing House DARWIN
    Tematy:
    Gmelina arborea
    Models
    Non-linear Regression
    Volume estimation
    Opis:
    This research elucidates non linear relationship for volume estimation of Gmelina arborea in Uyo Ravine plantation, Akwa Ibom State Nigeria. Series of functional models were developed and the estimates of measurement of stand parameters such as diameter at breast height (DBH), stump diameter (Dst), total height (THT), merchantable height, (MTH), merchantable length (MLT) were used for modeling procedures for best fit models for stand volume estimation. Twenty temporary sample plots of 20m x 20m were randomly established without replacement and all trees in each plot were measured. Quantitative data collected were subjected to correlation and regression analyses for determination of empirical relationship between the growth variables. The developed models for volume estimation were evaluated by confirming the goodness of fit of the model and the statistical significance of the parameters using statistical relevant fit indices and criteria. The results of the study showed there were significant associations between the Gmelina arborea growth characteristics both at the individual and stand levels. The correlation analyses revealed a significant association with coefficient of correlation (r) ranging from 0.576 – 0.836 among the Gmelina arborea growth characteristics at the stand level while the association between the volume and diameter at breast height gave r-value of 0.978 which was very significant P<0.05. Similarly, the results of the study in testing for relationship among the growth parameters using volume models showed that the non linear regression volume models significantly fulfilled the criteria for model selection or goodness of fit among cubic, logarithm and quadratic non linear regression models with their coefficient of determination (R2) ranging from 0.640-0.881 and low values of standard error of the estimate (SEE) at P< 0.05. These models were recommended for volume estimation of Gmelina arborea in the study area and other Gmelina arborea plantations for effective plantation forest management in Nigeria.
    Źródło:
    World Scientific News; 2020, 145; 46-61
    2392-2192
    Pojawia się w:
    World Scientific News
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Batch Removal of Metanil Yellow (MY) from Aqueous Solution by Adsorption on HNO3-Treated-H3PO4-Activated Carbon (NATPAAC) from Gmelina arborea Roxb.: Kinetic and Mechanism Studies
    Autorzy:
    Isiuku, B. O.
    Onyema, M. O.
    Powiązania:
    https://bibliotekanauki.pl/articles/1113804.pdf
    Data publikacji:
    2017
    Wydawca:
    Przedsiębiorstwo Wydawnictw Naukowych Darwin / Scientific Publishing House DARWIN
    Tematy:
    Activated carbon
    Gmelina arborea
    adsorption
    kinetic models
    metanil yellow
    Opis:
    As metanil Yellow dye is removed from aqueous solution by batch adsorption on NATPAAC derived from G. aborea bark, we studied the effects of initial dye concentration (Co), initial pH and adsorbent dosage at 29 °C. The experimental equilibrium adsorption capacities (qe) obtained, were 2.35, 1.00 and 0.48 mg/g for Co 25, 50 and 100 mg/L, respectively. The kinetics and mechanism of the adsorption were then modeled by fitting experimental data into the pseudo-second order (PSO), Based on correlation coefficient R2 (> 0.95) values, results show that the PSO and Elovich models simulated experimental data well, but the PSO model simulated it the best. The Boyd model confirmed that the adsorption process was controlled by liquid film diffusion and the effective diffusion coefficients were very low. Moreover, the qe values decreased with increase in Co, increase in pH and increase in adsorbent dosage. However, the removal of MY from aqueous solution was very low. In addition, treatment of carbon with dilute HNO3 had no favorable impact.
    Źródło:
    World News of Natural Sciences; 2017, 13; 10-26
    2543-5426
    Pojawia się w:
    World News of Natural Sciences
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Seasoning technologies of Gmelina arborea Roxb. lumber species grown at Bonga, SNNP, Ethiopia
    Autorzy:
    Desalegn, Getachew
    Kaba, Gemechu
    Tesfaye, Anteneh
    Amanuel, Saifu
    Powiązania:
    https://bibliotekanauki.pl/articles/1031783.pdf
    Data publikacji:
    2020
    Wydawca:
    Przedsiębiorstwo Wydawnictw Naukowych Darwin / Scientific Publishing House DARWIN
    Tematy:
    Defects
    Gmelina arborea
    density
    lumber quality
    seasoning defects
    shrinkage and uses
    Opis:
    Quality and performance of wood and wood-based products have been seriously affected by the major factors, among which moisture content (MC), inappropriate drying (seasoning) and density are the preceding ones. A study was conducted on Gmelina arborea lumber with the main objective of determining some imperative seasoning and density characteristics of the lumber that will help determine its wood quality and decide proper utilization. Gmelina arborea logs were harvested from Bonga trial site of Central Ethiopian Environment and Forest Research Center (CEE-FRC). The experimental design for seasoning and density was complete randomized design. The experiments were conducted in air and kiln seasoning methods. Mean initial moisture content (IMC) of samples were determined using oven and MC for air seasoning stack was 143.80%, while for kiln seasoning was 120.19%. The final MC to reach to about 12% MC in air took 210 days, while kiln seasoning took 13.5 days. Kiln seasoning rate of Gmelina arborea lumber was 15 times faster than air seasoning. The species was classified as slow and fairly rapid air and kiln seasoning lumber species, respectively. When Gmelina arborea lumber seasoned from green to 12% MC, mean shrinkage (%) characteristic values: Tangential (3.63%), radial 1.58%), and volumetric (5.11 %). Mean density of Gmelina arborea lumber species at green (initial), basic and oven dried and at 12% MC was 940,400, 430 and 420 kg/m3, respectively. The density at 12% MC, (420 kg/m3) classified as light density lumber species. Gmelinaarboreashown good quality lumber characteristics, comparable with many indigenous and homegrown exotic lumber species in density, seasoning rate and shrinkage characteristics.
    Źródło:
    World News of Natural Sciences; 2020, 29, 3; 269-281
    2543-5426
    Pojawia się w:
    World News of Natural Sciences
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
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