Treesearch

Wood inhabiting, rotting and/or decomposing fungi from Alaska include representatives from an assortment of fungal groups (cup, jelly, pored coral, tooth, puffball, gilled and lichenized fungi) and one fungus-like group (the slime molds). Of the more than 1,500 species recorded for North America, over 250 species of wood-inhabiting fungi have been reported from Alaska. In Alaska, more than 102 genera of gilled, shelf or bracket fungi with pores, jelly fungi, and flat paint-smear-like fungi are known. Most, if not all, of these fungi are known to fruit in Alaska national parks; however, it...

Kings Covered Bridge over Laurel Creek in Somerset County, Pennsylvania is approximately 114-foot clear span multiple Kingpost Truss with nail-laminated arches. This timber bridge is historically significant because it retains its original features of the 1860’s since the 1930s when it was spared from modernization by the construction of an adjacent steel highway bridge for vehicular traffic. Since that time Kings Bridge has a colorful history, including use as livestock barn and a proposed new use as a part of a “twin covered bridge” municipal park. Kings Bridge remains a museum-quality...

Digital image correlation was used to measure the full-field deformation of paperboard and handsheet tensile specimens. The correlation technique was able to accurately measure strain in regions 0.6 by 0.6 mm. Results showed the variation of strain to be much larger than has been previously reported. For machine made paperboard tested in the cross-direction, the variation of strain increased throughout the tensile test and became erratic near failure, indicating many local failures. The measured strain distribution can be characterized by a Weibull function in agreement with weak-link...

This paper describes an effort to develop a global dynamic testing technique for evaluating the overall stiffness of timber bridge superstructures. A forced vibration method was used to measure the natural frequency of single-span timber bridges in the laboratory and field. An analytical model based on simple beam theory was proposed to represent the relationship between the first bending mode frequency and bridge stiffness (characterized as EI product). The results indicated that the forced vibration method has potential for quickly assessing superstructure stiffness of timber bridges,...

Working stresses and performance of strand composite lumber largely depend upon the properties of each individual strand. Southern pine strands from plantation lumber grown in southern Louisiana were investigated in this study in order to understand strand behaviors. The effects of hot-pressing and resin application on tensile modulus, strength, and dimensional expansions (in three directions) were discussed. The mechanical properties of the untreated control strands were similar to those of solid wood products, while their dimensional expansions were larger than the reported values for...

A quantitative model is presented for evaluating the effects of incising on the bending strength and stiffness of structural dimension lumber. This model is based on the premise that bending strength and stiffness are reduced when lumber is incised, and the extent of this reduction is related to the reduction in moment of inertia of the bending members. Measurements of voids and damage caused by incisor teeth showed that actual incision depth was not always equal to nominal depth. For lumber with 660 incisions/ft2, the actual depth of the incisions was approximately equal to the targeted...

Understanding fiber fractionation in a froth is very important to the quality of recovered fibers in flotation deinking operations. Fiber length is a very important fiber quality parameter in paper-making. For example, long fibers tend to produce a paper with higher tear strength than short fibers. In this study, fibers in froth collected at different froth drainage times and from different heights were analyzed to obtain fiber length distributions. The length distribution of fibers in the collected froth showed a lower fraction of short fibers ( 0.8 mm) than those in the original pulp...

This study reports the feasibility of monitoring liquid and fiber rejection during froth flotation of fiber suspensions through conductivity measurements of the rejected froth. The technique was demonstrated in laboratory flotation experiments using nylon and wood fiber suspensions in two laboratory flotation cells. We found that both the total wet rejection and the fiber/solid consistency in the rejection stream correlate well to the measured relative conductivity of the rejected froth. Therefore, the relative conductivity of the froth can be used to monitor the liquid and fiber/solid...

This paper describes the joint efforts of the Forest Service and the FHWA to administer national programs including research, demonstration bridges, and technology transfer components. Summary information on a number of Forest Service-WIT demonstration bridges constructed with hardwoods is also provided.

Reducing fiber rejection loss in flotation deinking is very important to conserve natural resources and reduce the cost of secondary fibers in paper recycling. This study examined two aspects of the problem, fiber consistency in the rejection stream and rate of Froth (or wet stream) rejection. Flotation experiments were conducted using both nylon and wood fibers in column and commercial bench-scale flotation deinking cells. It was found that increased froth stability resulted in a lower fiber consistency in the wet reject stream. However, it also increased rejection rate of the wet stream....