UBC Theses and Dissertations

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UBC Theses and Dissertations

Effect of yarding operations on log recovery value Copithorne, Robert Dalgleish


This thesis deals with the problem of controlling losses in log recovery value in yarding operations. It is believed that losses under current operating methods can be substantial over time. The objective is to find ways of applying statistical quality control methods to controlling and reducing these losses. A literature review was done to determine the statistical techniques available. A pilot study was done concurrently to determine the current levels of value loss and test methods of measuring value loss. The final step was to recommend a procedure for monitoring and controlling log value losses based on the findings of the literature review and the pilot study. Value loss estimates in the pilot study were consistent with losses discussed in the literature (1-2%). The problems encountered with the methods used in the pilot study, however, were believed to be severe enough to limit the usefulness of the methods and the results. The methods were found to be cumbersome and time consuming as well as needing considerable refinement in the area of scaling and grading for true value recognition. The recommended statistical quality control method can be used operationally without the necessity of immediate improvement of scaling and grading techniques. The method involves observing occurrences of log damage and recording detailed information related to those occurrences so that the causes of the damage can determined. Procedures can then be developed to correct these causes. The method relies on the use of statistical control charts for attributes for monitoring log damage and highlighting periods of abnormal results for further investigation.

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