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Wyszukujesz frazę "Valenzuela, J.L." wg kryterium: Autor


Wyświetlanie 1-3 z 3
Tytuł:
Soil wind erosion characterization in south-eastern Spain using traditional methods in front of an innovative type of dust collector
Autorzy:
Guerrero, R.
Valenzuela, J.L.
Torres, J.L.
Lozano, J.
Asensio, C.
Powiązania:
https://bibliotekanauki.pl/articles/2082948.pdf
Data publikacji:
2020
Wydawca:
Polska Akademia Nauk. Instytut Agrofizyki PAN
Tematy:
dust collector
semi-arid environment
tilled
soil
unploughed soil
wind tunnel
Opis:
The movement of soil particles by the wind can be measured using wind tunnels and collectors, or dust traps. We tested both in Southeast Spain in order to compare movement in four types of soil. Our tests were carried out in a well-tilled orchard on an Anthrosol, an unploughed Leptosol and Arenosol, and finally on an olive-cropped Cambisol. We estimated soil loss using a wind tunnel with a built-in laser-scanner, and then compared the results with records from nine vaned masts, each with four big spring number eight collectors at different heights, and the same for another nine masts but with a new type of dust trap known as the multidirectional. The collectors can differentiate between overall loss and particle deposition, which is not detectable on a larger scale in the tunnel. The results from the big spring number eight traps and our wind tunnel showed a high degree of correlation (R² = 0.933) and an even closer correlation with the multidirectional trap (R² = 0.978). Moreover, the new multidirectional trap collectors are very efficient and easy to manufacture from thermoplastic filaments with an industrial 3D printer.
Źródło:
International Agrophysics; 2020, 34, 4; 503-510
0236-8722
Pojawia się w:
International Agrophysics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Current Annealings and Magnetoimpedance in Co-Fe Amorphous Ribbons
Autorzy:
González, J.
Domínguez, L.
Blanco, J. M.
Aragoneses, P.
Valenzuela, R.
Powiązania:
https://bibliotekanauki.pl/articles/1956111.pdf
Data publikacji:
1997-02
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.60.Nt
75.50.Kj
Opis:
Amorphous ribbons of composition (Co$\text{}_{0.95}$Fe$\text{}_{0.05}$)$\text{}_{100-x}$Si$\text{}_{0.4x}$ B$\text{}_{0.6x}$, with x=25 and 30 were prepared by the melt-spinning technique. Current annealings at 600 mA were performed for annealing times between 15 s and 60 min. The magnetoimpedance response was investigated by submitting the ribbons to ac currents at frequencies in the 10-200 kHz range, with amplitudes between 1 and 15 mA (rms), and measuring their voltage response. The observed results show that a transverse anisotropy is induced by the thermal treatments, which can be evaluated by means of the magnetoimpedance effect. Due to its lower Curie temperature, the x=30 ribbons exhibited lower sensibility to the current annealings.
Źródło:
Acta Physica Polonica A; 1997, 91, 2; 451-454
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Allometric models for estimating aboveground biomass in tree sprouts of three dendroenergetic crops
Autorzy:
Ríos-Saucedo, J.C.
Acuña-Carmona, E.
Cancino-Cancino, J.
Corral-Rivas, J.
Rosales-Serna, R.
Valenzuela-Núñez, L.M.
Powiązania:
https://bibliotekanauki.pl/articles/2078210.pdf
Data publikacji:
2020
Wydawca:
Polska Akademia Nauk. Instytut Dendrologii PAN
Tematy:
bio-energy
short rotation
Eucalyptus globulus
Eucalyptus denticulata
Acacia dealbata
dummy variables
Opis:
Recurrent problems have been observed for biomass measurement in tree sprouts, mainly due to differences in patterns of biomass distribution and the bias generated by using models for mature trees. The objective of this research was to evaluate models to estimate aboveground biomass in sprouts from two-year-old stumps of Short Rotation Woody Crops (SRWC) used for energetic purposes. The study was conducted in Central Chile (Bío-Bío region) under a complete block design and four replications. Three plant species were included: Eucalyptus globulus, E. denticulata, and Acacia dealbata, established in three population densities (5,000, 10,000 and 15,000 trees per ha). Two groups of nonlinear models were used on three independent variables: root collar diameter (squared mean of two dominant stems), height (mean of two dominant stems) and number of epicormic stems. In the allometric model, the total aboveground biomass and the aboveground biomass by component were explained as the product of the mean square of the root collar diameter, mean height of the two dominant new sprouts and total number of epicormic sprouts as the predictive variable. Values of coefficient of determination (R2 ) ranged from 0.78 to 0.95 and RMSE ranged from 168 to 913 g. The species of E. globulus showed higher RMSE for biomass estimation in the all components except the branch component. The inclusion of dummy variables to identify the differences in each parameter of the models explained the seasonality of the biomass accumulation in tree sprouts at 10, 21, and 31 months of age, improving the model goodness of fit RMSE by 27%. Accurate prediction of sprouts aboveground biomass was obtained by the models only evaluating the two dominant epicormic sprouts in the stump, avoiding the need of individual sprouts evaluation or using destructive methods for biomass measurement.
Źródło:
Dendrobiology; 2021, 85; 19-29
1641-1307
Pojawia się w:
Dendrobiology
Dostawca treści:
Biblioteka Nauki
Artykuł
    Wyświetlanie 1-3 z 3

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