1. Introduction and Overview. 2. Detecting Influential Observations and Outliers. 3. Detecting and Assessing Collinearity. 4. Applications and Remedies. 5. Research Issues and Directions for Extensions. Bibliography. Author Index. Subject Index.

Regression Diagnostics: Identifying Influential Data and Sources of Collinearity

The American Society for Testing and Materials (ASTM) is an independent organization devoted to the development of standards.

American Society for Testing and Materials

Variations in acoustic velocity and density with age, and their interrelationships in radiata pine

After millions of years of evolution, wood was designed to perform in a wet environment, and nature is programmed to recycle it, in a timely way, back to the basic building blocks of carbon dioxide and water through biological, thermal, aqueous, photochemical, chemical, and mechanical degradation. The properties of wood are, for the most part, a result of the chemistry of its cell wall components. The polysaccharides (cellulose and hemicelluloses) are mainly responsible for (i) moisture uptake and release in changing environments that result in changes in wood volume (dimensional instability), (ii) recognition mechanisms for biological degradation (attack by fungi, termites, etc.), (iii) thermal instability (pyrolysis and burning), (iv) chemical degradation (by acids and bases), and, to some degree, (v) degradation due to ultraviolet radiation (weathering, lignin degradation).

https://www.fpl.fs.fed.us/documnts/pdf2005/fpl_2005_rowell005.pdf

Chemical Modification of Wood

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Nondestructive Characterization And Imaging Of Wood

The primary objective of this study was to investigate the usefulness of a stress wave technique for evaluating wood strength and stiffness of young-growth western hemlock and Sitka spruce in standing trees. A secondary objective was to determine if the effects of silvicultural practices on wood quality can be identified using this technique. Stress wave measurements were conducted on 168 young-growth western hemlock and Sitka spruce trees. After in situ measurements, a 0.61-m-long bole section in the test span was taken from 56 felled trees to obtain small, clear wood specimens. Stress wave and static bending tests were then performed on these specimens to determine strength and stiffness. Results of this study indicate that in situ stress wave measurements could provide relatively accurate and reliable information that would enable nondestructive evaluation of wood properties in standing trees. The mean values of stress wave speed and dynamic modulus of elasticity for trees agreed with those determined from small, clear wood specimens. Statistical regression analyses revealed good correlations between stress wave properties of trees and static bending properties of small, clear wood specimens obtained from the trees. Regression models showed statistical significance at the 0.01 confidence level. Results of this study also demonstrate that the effect of silvicultural practices on wood properties can be identified with the stress wave properties of trees. This indicates that this nondestructive stress wave technique can be used to track property changes in trees and help determine how forests could be managed to meet desired wood and fiber qualities.

/pdf/nondestructive-evaluation-of-standing-trees-with-a-stress-13yvp0ddy5.pdf

Nondestructive evaluation of standing trees with a stress wave method

https://www.fpl.fs.fed.us/documnts/pdf2007/fpl_2007_wang003.pdf

Acoustic Assessment of Wood Quality of Raw Forest Materials - A Path to Increased Profitability.

Arborists are often challenged to identify internal structural defects hidden from view within tree trunks. This article reports the results of a study using a trunk inspection protocol combining visual observation, single-path stress wave testing, acoustic tomography, and resistance microdrilling to detect internal defects. Two century-old red oak (Quercus rubra) trees located in Capitol Park, Madison, Wisconsin, U.S., were visually inspected and then evaluated using a single-path stress wave timer, an acoustic tomography, and a resistance measuring drill. The trees were subsequently felled, and a disk at each test location was obtained and examined. It was found that the visual inspection and single-path stress wave tests correctly identified a general problem but without specificity; the tomograph accurately revealed the general location and magnitude of the defect within the cross-sections tested but required resistance microdrilling to precisely locate defects and differentiate between decay and crack- induced acoustic shadows.

/pdf/decay-detection-in-red-oak-trees-using-a-combination-of-4xhlivirda.pdf

Decay Detection in Red Oak Trees Using a Combination of Visual Inspection, Acoustic Testing, and Resistance Microdrilling

Acoustic technologies have been well established as material evaluation tools in the past several decades, and their use has become widely accepted in the forest products industry for online quality control and products grading. Recent research developments on acoustic sensing technology offer further opportunities to evaluate standing trees and logs for general wood quality and intrinsic wood properties. Although the concept of using acoustic velocity as an effective measure of stiffness applies to both standing trees and felled logs, the method typically used to measure acoustic velocity in trees is different from that used in logs. Consequently, there is a significant difference in measured velocity values between trees and logs. Other factors affecting tree–log velocity relationships include tree diameter, stand age, operating temperature, and wood moisture content. This paper presents the fundamentals of acoustic wave propagation in trees and logs and discusses two different mechanisms of acoustic velocity measurement, time-of-flight for standing trees and resonance for logs. Experimental data from previous studies are reviewed and analyzed to examine the strength of the tree–log velocity relationships and discuss the factors that influence tree velocity deviation.

https://www.fpl.fs.fed.us/documnts/pdf2013/fpl_2013_wang003.pdf

Acoustic measurements on trees and logs: a review and analysis

Acoustic wave velocities in standing trees of five softwood species were measured by the time-of-flight (TOF) method. Tree velocities were compared with acoustic velocities measured in corresponding butt logs through a resonance acoustic method. The experimental data showed a skewed relationship between tree and log acoustic measurements. For most trees tested, observed tree velocities were significantly higher than log velocities. The results indicate that time-of-flight measurement in standing trees is likely dominated by dilatational or quasi-dilatational waves rather than one-dimensional plane waves. To make appropriate adjustments of observed tree velocities, two analytical models were developed for the species evaluated. Both the multivariate regression model and dilatational wave model were effective in eliminating deviation between tree and log velocity and reducing variability in velocity prediction.

/pdf/acoustic-evaluation-of-wood-quality-in-standing-trees-part-i-16byr5dilp.pdf

Xiping Wang

Papers

Nondestructive evaluation of standing trees with a stress wave method

Acoustic Assessment of Wood Quality of Raw Forest Materials - A Path to Increased Profitability.

Decay Detection in Red Oak Trees Using a Combination of Visual Inspection, Acoustic Testing, and Resistance Microdrilling

Acoustic measurements on trees and logs: a review and analysis

Acoustic Evaluation of Wood Quality in Standing Trees. Part I. Acoustic Wave Behavior