Fiber Length in Normal and Foxtail Pinus Caribaea Mor.

Carribbean pine often develops a foxtail form when planted in tropical and subtropical locations. The normal procedure in many plantations is to destroy these trees, partly because it is thought they are of low wood quality. Since as many as 50% of the trees in a location may be affected by foxtailing, this procedure represents a huge loss, especially in areas where survival is already very low.This study was undertaken to determine if foxtailing lowers the fiber length of the affected tree. Ten normal and ten foxtails were sampled at two heights for fiber length. It was found that fibers from foxtail trees were on the average 13.5% longer than from normal trees growing in the same location

A Note on Prediction of Wood Properties in Yellow-Poplar

Increment core samples were taken from fifteen yellow-poplar trees at breast height and determinations of specific gravity and fiber length were made on selected individual growth rings. Juvenile wood and mature wood of different growth rates were compared. The results show mature wood specific gravity uncorrelated with growth rate and mature wood fiber length increasing with increasing growth rate. The extremely low correlation obtained between juvenile wood and mature wood properties within the same tree indicates that no predictive relationship exists for use in selection at a very early age

Direct Scanning Densitometry: An Effect of Sample Heterogeneity and Aperture Area

Direct scanning radiation densitometry is finding increased application in forestry and wood products research. Radiation densitometry is often used for tree ring analysis and density profile analysis of reconstituted panel products. This paper discusses some limitations to accuracy in the use of a scanning or stepping densitometry system. The effect of aperture area and sample heterogeneity on accuracy of the density determination is discussed. The "edge effect" in the densitometry of panel products is discussed

LEADERSHIP IN PROJECTS WITH NEW TECHNOLOGY AND UNCERTAINTY

Project management continues to evolve as types of projects increase, advancement of technologies available, as well as tools for project management grow in sophistication. A successful project is defined as being completed on schedule, on budget, and delivering the requirements as specified by the customer. Projects with new technologies or with technologies requiring maturation add another dimension and challenge for the project manager. Four factors are identified as integral to project success; leadership, requirements definition, technology usage and maturity, and vision and clear objectives. Three historical projects involving new technologies are evaluated within the context of the four factors: the Lockheed SR-71 Blackbird aircraft, the Hoover Dam project, and Project Apollo. The projects are qualitatively ranked as successful based on the cost, schedule, and delivering requirements criteria. The three projects were successful. Each project ranked strongly in the four factors and remain consistent indicators of potential project success

A Procedure To Determine Water Absorption Distribution In Wood Composite Panels

A procedure is presented to determine the water absorption distribution of wood composite panels. The procedure is based on the direct measurement of the vertical density distribution before water soak, the vertical density distribution after the water-soaked specimens have been reconditioned to pre-soak weights, and the construction of the vertical density distribution for the specimens immediately after water soak. The separation of "wood mass" and water was achieved through the application of radiation absorption principles involving the two elements. The procedure was used to examine the water absorption distributions of medium density fiberboard, oriented strandboard, and particle-board. A good agreement was obtained between the estimated average water absorptions and measured water absorptions. Water absorption distribution in relation to the layer density and layer thickness swell was discussed

Density And Growth Ring Characteristics Of Pinus Taeda L. Following Thinning

Sixteen experimental plots of loblolly pine (Pinus taeda L.) grown in plantations in Tennessee, USA, were thinned to basal areas of 13.8 m2/ha (heavy), 23.0 m2/ha (moderate), or 32.2 m2/ha (light) in 1963 at age 23. In 1980 12-mm increment cores were removed at breast height, and sections encompassing 8 years before and after thinning were examined for changes in average wood density, radial growth, earlywood and latewood density, and percent latewood. As expected wood density increased with tree age but was not significantly affected by thinning, even though individual tree growth was considerably improved. Although radial growth usually decreases with age, it actually increased in the heavily thinned plots compared to the less severely thinned or unthinned (control) plots. Trees in the moderately and heavily thinned plots produced wood with lower earlywood density and higher latewood density while percent latewood remained unchanged.The timber strength and seasoning characteristics related to wood density should not be affected by thinning. However, the shift within growth rings of earlywood and latewood density distributions may adversely affect pulping qualities of wood

Fundamentals of Vertical Density Profile Formation in Wood Composites. Part I. In-Situ Density Measurement of the Consolidation Process

We have designed a radiation-based system for measuring density of wood composite mats during consolidation. The system is installed on a laboratory hot-press and has been used to study consolidation of medium density fiberboard (MDF) and oriented strandboard (OSB) mats. Measuring density of the wood mat during consolidation is a key parameter for understanding subsequent product performance. The in-situ measuring system provides for density measurement at three horizontal planes in the wood mat, at positions of 25%, 50%, and 75% of the mat thickness at any time during the press cycle. The system incorporates three cesium137 sources and electronic detection equipment, collimated to move in concert with the up-acting press platen. Radiation count data taken through the mat during pressing are converted to density after pressing. Press position and time are simultaneously recorded with the count data. Moisture migration during hot-pressing resulted in significant density changes as measured by the in-press radiation-based system. Clearly established in all laboratory pressing studies is the indication that the vertical density profile of wood composite panels is formed from a combination of actions that occur both during consolidation and also after the press has reached final position; measurements recorded in the press show that mat densification continues after the press has reached final position. A description of the radiation system and data from elementary pressing examples are presented, along with experimental results of the effects of moisture migration in the mat on measured density during pressing

Calibration Procedure For A Direct Scanning Densitometer Using Gamma Radiation

Direct scanning systems must be properly calibrated so that results may be repeated and verified. A calibration procedure was developed in which blocks of various wood species and densities were scanned with a direct-scanning wood densitomelcr using gamma radiation from a low (Fe55) and a high (Am241) energy source. Wood mass attenuation coefficients for Fe55 and Am241 were, respectively, 18.22 and 0.191 cm2/g at 8% equilibrium moisture content and 17.72 and 0.185 cm2/g under ovendry conditions. These results compare closely