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GPSSV simulation model of timber harvesting operations

University of British Columbia

This thesis provides a methodology for examining forest harvesting operations through simulation. The model is capable of simulating multiple landing, single dump logging configurations. Facility locations, equipment types and numbers, parameters, and functional relationships may be varied so that a wide range of west coast British Columbia logging operations can be represented. The model was written in General Purpose Simulation System V (GPSSV) language. A substantial saving in development cost is realized over a FORTRAN-based simulation. The model allows independent users to make modifications within the program in order to adapt to the particular operating rules and policies of their operations. Model formulation for this thesis is based on an actual west coast logging division. Verification of the model involves a three-stage approach. First, a set of hypotheses and postulates are constructed for the subsystems of the harvesting operation and, secondly, these are empirically tested. Historical data is compared to simulation results in order to confirm that particular subsystems adequately model the real system. Tactical considerations and experimental design regarding model execution are presented. It is shown that antithetic variates can be effectively used to reduce the variance of the mean of a response. An improved truck dispatching routine is developed with the objective of maximizing productivity, subject to the availability of yarding and trucking resources. This policy balances the objectives of minimizing truck travel time, truck delays at landings, and yarding stoppages due to timber "saturated" landings. In comparison with other dispatching policies, productivity can be increased from two to over ten percent. The dispatching algorithm has been programmed for a Hewlett-Packard 9830A desktop computing system. The dispatcher, utilizing radio communications with all of the landings and trucks, can theoretically be supplied with the optimum landing to which a truck should be dispatched. Some other practical applications of the timber harvesting simulation model are discussed. Flexibility in the model, in parameter initialization and the substitution of new relationships, allows the investigation of many features of forest resource planning and machine allocation and scheduling. The determination of equipment requirements for various configurations, the evaluation of new equipment and the comparison of different operating policies can be undertaken with the model. Another benefit derived from the development of the model is an increased understanding of the timber harvesting system which allows the design of better operating policies and greater control within the system.

Text

2010-02-24

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http://hdl.handle.net/2429/20854

Forestry

University of British Columbia

Graduate