Original scientific paper
https://doi.org/10.5552/nms.2019.2
Technical-Economic Analysis of Grapple Saw: A Stochastic Approach
Ricardo Hideaki Miyajima
orcid.org/0000-0002-6200-0060
; São Paulo State University (Unesp)
Paulo Torres Fenner
; School of Agriculture, Botucatu Avenue Universitária, 3780, Altos do Paraíso BRAZIL
Gislaine Cristina Batistela
; São Paulo State University (Unesp) Campus of Itapeva Street Geraldo Alckmin, 519, Vila Nossa Sra. de Fátima BRAZIL
Danilo Simões
; São Paulo State University (Unesp) Campus of Itapeva Street Geraldo Alckmin, 519, Vila Nossa Sra. de Fátima BRAZIL
Abstract
The processing of Eucalyptus logs is a stage that follows the full tree system in mechanized forest harvesting, commonly performed by grapple saw. Therefore, this activity presents some associated uncertainties, especially regarding technical and silvicultural factors that can affect productivity and production costs. To get around this problem, Monte Carlo simulation can be applied, or rather a technique that allows to measure the probabilities of values from factors that are under conditions of uncertainties, to which probability distributions are attributed. The objective of this study was to apply the Monte Carlo method for determining the probabilistic technical-economical coefficients of log processing using two different grapple saw models. Field data were obtained from an area of forest planted with Eucalyptus, located in the State of São Paulo, Brazil. For the technical analysis, the time study protocol was applied by the method of continuous reading of the operational cycle elements, which resulted in production. As for the estimated cost of programmed hour, the applied methods were recommended by the Food and Agriculture Organization of the United Nations. The incorporation of the uncertainties was carried out by applying the Monte Carlo simulation method, by which 100,000 random values were generated. The results showed that the crane empty movement is the operational element that most impacts the total time for processing the logs; the variables that most influence the productivity are specific to each grapple saw model; the difference of USD 0.04 m3 in production costs was observed between processors with gripping area of 0.58 m2 and 0.85 m2. The Monte Carlo method proved to be an applicable tool for mechanized wood harvesting for presenting a range of probability of occurrences for the operational elements and for the production cost.
Keywords
forest harvesting, Eucalyptus, production costs, Monte Carlo, productivity
Hrčak ID:
240268
URI
Publication date:
30.6.2020.
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