26 research outputs found
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Properties and uses of bark as an energy source
Energy is extremely important to all societies-but especially important to industrial societies. A characteristic of an industrial society is its enormous consumption of energy. Only in the past few years has there been a broad general concern about energy cost and supply. When petroleum prices increased by a factor of 3 to 4 in just a few months, we all became aware of the importance of, and our dependence on energy supplied by other countries; and we became aware that many energy resources are nonrenewable-once used, they are gone forever. This paper concerns one resource that is renewable, one constantly replaced by energy from the sun. It is a resource in which there is virtually no international trade, one nearly always used in the country in which it is produced. That energy source is bark. By far the most important single use for bark (as well as for wood) is for energy. In 1972, nearly half the wood cut for man's use was for fuel (18), and associated with that wood was bark. Worldwide, more people are warmed by wood and bark than by any other fuel
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A study of wood and bark residue disposal in the forest products industries
A preliminary report to the Fifty-fifth legislative assembly, February 1969. This is a preliminary report of a two-year study that was authorized by the Fifty-fourth Legislative Assembly in 1967. The study was aimed at providing means of lessening air pollution from disposal of wood and bark residues by forest products industries. The final report summarizing conclusions of the study will be published in August 1969. Included in the study are a statewide survey of wood and bark residues; a transportation cost study; an investigation of three methods for disposing of residues, 1, burning in a wigwam burner, 2, burning in other types of incinerators, 3, disposal by landfill; and an investigation of three means of utilization: 1, as fuel, 2, on the soil, and 3, wax extraction from bark.
In Oregon, use of wood residues for paper and composition board manufacture has increased greatly in the last 14 years. Only 6 percent of woo::! residues from sawmills and plywoo::l plants was used for paper and composition board in 1953, compared to about 60 percent in 1967. Quantity of residues being burned in wigwam burners has been consequently reduced in recent years. Utilization will continue to increase in the future and quantities of wood and bark requiring disposal will decrease.KEYWORDS: Wood waste, Bark as fuel, Mulchin
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Wood and bark residues in Oregon : trends in their use
The forest-products industries are most important to the state of Oregon. Oregon leads the nation in the production of plywood, lumber, and particle board. More than half of softwood plywood production in the United States came from Oregon at the time of this survey, and more than a fifth of the lumber and about a third of the particle board were produced in Oregon.
Over 90 percent of the logs harvested in the state at the time of this survey were destined for sawmills and plywood plants. In producing lumber and plywood from logs, less than half of the entering log volume emerges as the finished primary product. That portion of the log remaining consists of such items as bark, sawdust, shavings, slabs; veneer trim, plywood trim, cores, and sander dust. This portion that remains after primary manufacture frequently is called residue.f Ouch of this residue formerly was considered waste and usually was disposed of by burning. But now a large portion of this residue material is recovered for other uses-primarily as raw material for paper and wood-composition board manufacture. If residue is not used, it presents a problem of disposal within allowable limits of pollution.
Because these residue materials are a valuable raw material, we conducted a survey of virtually all sawmills and plywood plants in the state to determine how these residues were being used; to point out what quantities might be available for future use; and to note the changes that had occurred in residue usage since previous surveys.
An additional objective was to obtain information on a material balance for sawmill and plywood plants, so that conversion factors could be developed for estimating average quantities of different types of residue generated from a given production of lumber or plywood. From these conversion factors, the average amount of a given type of residue that might be expected in producing a given board footage of lumber or a given square footage of plywood can be estimated
Socio-cultural determinants of physical activity across the life course: a 'Determinants of Diet and Physical Activity' (DEDIPAC) umbrella systematic literature review
Objective
Regular physical activity (PA) reduces the risk of disease and premature death. Knowing factors associated with PA might help reducing the disease and economic burden caused by low activity. Studies suggest that socio-cultural factors may affect PA, but systematic overviews of findings across the life course are scarce. This umbrella systematic literature review (SLR) summarizes and evaluates available evidence on socio-cultural determinants of PA in children, adolescents, and adults.
Methods
This manuscript was drafted following the recommendations of the ‘Preferred Reporting Items for Systematic reviews and Meta-Analyses’ (PRISMA) checklist. The MEDLINE, Web of Science, Scopus, and SPORTDiscus databases were searched for SLRs and meta-analyses (MAs) on observational studies published in English that assessed PA determinants between January 2004 and April 2016. The methodological quality was assessed and relevant information on socio-cultural determinants and any associations with PA was extracted. The available evidence was evaluated based on the importance of potential determinants and the strength of the evidence.
Results
Twenty SLRs and three MAs encompassing 657 eligible primary studies investigated potential socio-cultural PA determinants, with predominantly moderate methodological quality. Twenty-nine potential PA determinants were identified that were primarily assessed in children and adolescents and investigated the micro-environmental home/household level. We found probable evidence that receiving encouragement from significant others and having a companion for PA were associated with higher PA in children and adolescents, and that parental marital status (living with partner) and experiencing parental modeling were not associated with PA in children. Evidence for the other potential determinants was limited, suggestive, or non-conclusive. In adults, quantitative and conclusive data were scarce.
Conclusions
A substantial number of SLRs and MAs investigating potential socio-cultural determinants of PA were identified. Our data suggest that receiving social support from significant others may increase PA levels in children and adolescents, whereas parental marital status is not a determinant in children. Evidence for other potential determinants was limited. This was mainly due to inconsistencies in results on potential socio-cultural determinants of PA across reviews and studies
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Indentation hardness of Douglas fir and Western hemlock lumber related to density
Indentation hardness tests were made on sections of 211 pieces
of Douglas fir and 208 pieces of Western hemlock at a moisture content
of about 11 percent. Specific gravity and visual-density evaluations
were also determined.
Correlation coefficients for linear regression of density, as
measured by specific gravity, on average standard hardness were
0.826 for Douglas fir and 0.842 for Western hemlock.
Classification according to specific gravity was better using
hardness classes compared to using visual-density classes