Treesearch

Reliability analysis is a mathematical technique for appraising the design and materials of engineered structures to provide a quantitative estimate of probability of failure. Two or more cases which are similar in all respects but one may be analyzed by this method; the contrast between the probabilities of failure for these cases allows strong analytical focus on the case differences. This comparative procedure is known as differential reliability analysis. The technique is demonstrated by means of an example involving a simple truss member. Applications of reliability analysis important...

Twelve-foot and 6-foot I-beams with webs of two different hardboard materials and plywood were subjected to constant loads in three different humidity environments. After 17,000 hours of test, the performance of the hardboard-webbed I-beams appears to be at least comparable to that of I- beams with plywood webs. Results of this study will be useful to researchers, designers, and building code officials for judging the acceptability of woodbase materials in structural components such as I- beams.

In the neotropics, the genus Chrysophyllum consists of C. cainito and a number of species which have recently been assigned to the genus Cynodendron. Many taxonomists have not accepted the new genus Cynodendron and this is supported by the present study of the wood anatomy. In this restricted sense, Chrysophyllum consists of a group of closely related species that are readily identifiable by their anatomical structure.

The old genus Chloroluma has been reinstated to generic status after having been in synonomy under Chrysophyllum for many years. The description is based on the type species C. gonocarpa which is characterized by: Its clear yellow wood; pores in radial-echelon arrangement; rhombic, two-sized, and microcrystals frequent in the axial parenchyma and wood rays; colored cell contents and silica lacking; very large crystals occasionally found in the tyloses.

The mobile home industry is a large and expanding lumber market within the housing industry. A sturdy wood frame lies under the metal wall and roof skin found on most mobile home units. When compared with data compiled in 1970 (1), the latest Forest Service, Department of Agriculture survey findings indicate the average mobile home now uses much more lumber for framing. This increase in lumber usage is attributed to larger units and better quality construction--with the quality factor generally thought to be most important. Better quality homes with sturdier framing are produced now...

This report has been prepared to supplement Federal Specification TT-W-571 “Wood Preservation: Treating Practices.” developed for the General Services Administration by the U.S. Department of Agriculture, Forest Service, Forest Products Laboratory, the Specification is used by Federal agencies, State agencies, and private users in procuring preservative-treated wood. The economical and practical procurement of treated wood demands a knowledge of wood deterioration and means of protection. The U.S. Forest Products Laboratory, the nation’s center for wood utilization research, has studied...

Describes a new technique for softening wood, using a 4 percent solution of ethylenediamine; a shortcut method for removing silica and crystalline materials with hydrofluoric acid; a method for rapidly neutralizing wood blocks which have been treated with hydrofluoric acid; and a method for maintaining the flatness of sections through staining, dehydration, and clearing. Methods described are applicable to wood with a specific gravity in excess of 0.75.

A methanol-from-wood waste facility having a capacity of 50 million gallons per year requires 1,500 ovendry tons (ODT) of wood waste per day. The yield of methanol from wood is about 38 percent, or about 100 gallons per ODT of wood. This yield is based on all process energy required coming from the wood waste. At a wood waste cost of $15/ODT, the selling price of methanol is estimated at $0.77/gal; at $34/ODT, the selling price is $0.96/gal.

Urea-formaldehyde-type adhesives have the inherent characteristic of giving off free formaldehyde under some conditions of use. The vapor can build up to concentrations which can be a nuisance, uncomfortable, or an actual health hazard. The "formaldehyde problem" is reviewed, from literature sources, in five respects : oriqins, analytical, control and removal, toxicology, and odor and (general methods of) odor control. Correlation between the citations in each section, and between the sections, is provided by appropriate annotation. The report is current to January 1977.

PARVCOST, a FORTRAN program, was designed to develop economic and financial analyses of systems for manufacturing particleboard. In the program, costs and requirements of wood are calculated as are chemicals and energy per unit of finished board products. Estimates are made of sensitivity of the finished product costs to changes in unit costs of energy and raw materials. Weight statistics are computed for the finished product and for the profit contribution ratio for values of given products. An appendix is included with a sample program output, two versions of data decks and modifications,...