In-forest log segregation based on acoustic measurement of wood stiffness.

摘要

To remain competitive, the forest products industry needs to look for new and innovative processes and technologies to not only reduce costs but also to recover more value through the entire seedling-to-customer forest products supply chain. It is well recognized that measuring wood properties of logs in real time during harvesting would lead to improved log allocation decisions and increased value recovery. Wood stiffness is certainly one of the attributes defining the quality of forest products such as veneer and lumber. Accurately assessing stiffness in realtime can be a challenge for log supply managers requiring logs segregated into different product classes based on stiffness.;Acoustic technology has proven to be a well established non-destructive technique for assessing potential product performance by identifying logs with high stiffness. Launched by the worldwide trend towards increased mechanization of forest harvesting operations, providing a platform for innovative measurement systems, the interest in incorporating technologies for measuring internal stem features into a harvester head is rapidly growing. Therefore, the purpose of this study was to provide forest products stakeholders with comprehensive scientific information on the potential capabilities, limitations, and applicability of acoustic technology to improve value recovery from Douglas-fir stands by means of in-forest sorting of veneer quality logs. This dissertation: (1) Demonstrated that recovery of high quality green veneer from Douglas-fir peeler logs could be accurately predicted using resonance-based acoustic velocity measurements, (2) modeled the predictive capabilities of spatial as well as internal and external log and tree characteristics in terms of veneer quality and analyzed their effects on acoustic velocity measurements of Douglas-fir wood stiffness, (4) determined whether time of flight acoustic technology could be used for pre-harvest veneer quality assessment of Douglas-fir stands in terms of stiffness requirements, (5) described influential factors arising from incorporating acoustic instruments on a mechanized harvester head and suggested optimal procedures for scanning in terms of feasibility and harvester productivity, (6) presented a general methodology to estimate breakeven prices of Douglas-fir peeler logs based on the net return obtained when logs from stiffness graded stands using acoustic technology are processed and converted into end products.