Browsing by Author "Gül A.U."

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    Calculation of uneven-aged stand structures with the negative exponential diameter distribution and Sterba's modified competition density rule
    (2005) Gül A.U.; Misir M.; Misir N.; Yavuz H.
    Depending on Sterba's modified Competition Density Rule [Sterba, H., 1975. Assmann's theorie der grundflächenhaltung die "Competition Density Rule" det Japaner Kira, Ando und Tadaki. Cbl. f.d. ges. Forstw. 92, 46-62], the maximum basal area (Gmax), quadratic mean diameter (dGmax), and stem numbers (NGmax), for uneven-aged stands of Abies nordmanniana in the Black Sea Region in Turkey were calculated. Then, an exponential diameter distribution as a function of dominant height for these stands was obtained by solving nonlinear system of equations, which uses the maximum basal area (G max) and the stem numbers (NGmax) as input values, and gives diminution coefficient (q) and the number of stems in the largest diameter class (N1) as outputs. The results are in accordance to Sterba and Monserud's findings [Sterba, H., Monserud, R.A., 1993. The maximum density concept applied to uneven-aged mixed species stands. For. Sci. 39 (3), 432-452] on the slope of the maximum density line, and with Susmel's [Susmel, L., 1956. Laws and the variation of the parameters in uneven-aged normal forests. L'Italia Forestale e Montana XI (3), 3-14] concept of decreasing q with increasing dominant height. © 2005 Elsevier B.V. All rights reserved.
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    Efficiency determination of the forest sub-districts by using fuzzy data envelopment analysis (case study: Denizli Forest Regional Directorate)
    (Chinese Fuzzy Systems Association, 2014) Şafak I.; Gül A.U.; Akkaş M.E.; Gediklili M.; Kanat Ş.M.; Portakal S.Ü.
    Until this study an efficiency evaluation study had not been carried out down to the level of forest sub-districts in Turkey. In this research, it is aimed to evaluate the efficiency of the forest sub-districts in the Denizli Forestry Regional Directorate using fuzzy data envelopment analysis (Fuzzy DEA) for years 2007 and 2009. Fuzzy DEA solutions were carried out using the data range. Fuzzy data was established by defining the lower, central and upper limits on the basis of the triangular membership function. These data are converted into interval data considering the approach of Zimmermann (1991) α cutting set. Thus, the upper and lower limits of efficiency values were obtained at five different α (0; 0.25; 0.50; 0.75 and 1.00) using fuzzy data envelopment analysis. Then inefficient forest sub-districts were listed from best to worst using the Minimax Regret-Based Approach. © 2014 TFSA.