1721 research outputs found
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The wood of teak (Tectona grandis L.)
No full textTeak (Tectona grandis L.) belongs to most precious and desired wood species. Because of reduced supply of teak wood from natural forests in Southeast Asia,mainly the plantation wood from different tropical regions is available on the market. We present the properties of nature grown teak wood compared tothose of wood from the plantations. Teak wood from natural forests generallycontains a greater portion of coloured heartwood containing hydrophobic caoutchouc and high content of biologically active extractives like lapachol, deoxylapachol, 2 methylanthraquinone (tectoquinone) and 2-hydroxymethylanthraquinone. The heartwood of teak is distinguished by its decorative appearance, high natural durability and dimensional stability. Trees from plantations are usually fast grown, have smaller stems and high proportion of sapwood and juvenile wood. Heartwood-formation can be less intensive which leads to reduced natural durability. The wood from plantations is not necessarily of lower quality, but it is likely more variable than the wood form natural sites
Češnjeva listna pegavost, ki jo povzroča gliva Blumeriella jaapii, se je razmahnila v vlažnem letu 2008
Get PDFSuša je omogočila nekaterim endofitom in fakultativnim parazitom povzročiti poškodbe bukve na področju Reštanja, Bohor
Get PDFTechnical parameters dynamics of WOODY 110 cable skidder within the range of stopping due to overload in uphill wood skidding
No full textThe article deals with uphill wood skidding with WOODY 110 skidder and the changes taking place in technical parameters: slip, torque, tractive forces, and weight distribution of a loaded tractor in the last three meters of skidding, which is defined as a range of stopping due to overload. The test was performed on a concave skid trail, where tractor loaded with 8 meter long fir logs stopped at the 32% incline. It stopped somewhat later when skidding with butt-end forward in comparison to skidding with top-end forward. The loadweight with butt-end forward was 31.69 kN, whereas with top-end forward itweighed 33.53 kN. The measured speeds showed minute changes until the last meter, but decreased swiftly after stopping. Regarding some technical parameters, there were almost no changes at the end of stopping, two exceptions being the slip, which increased in the range of stopping, and the forward torque, which decreased in this range. The results showed that the hydrostatic transmission was efficient, considering that in a relatively well-controlled slip (the slip values increase only in the last three meters, which approximately equals the half of tractor's length) there was less grounddamage
Legal basis, standards and criteria for evaluating thermal conditions in forest work
No full textIn this discourse, the Slovene legal basis for thermal conditions at work, together with three international standards for studying thermal conditions SIST EN ISO 7730 (Thermal comfort), SIST EN 27243 (hot environments) and SIST EN ISO 11079 (cold environments), are presented. All three international standards list the criteria for evaluation of thermal conditions and represent the scientific research basis for studying work in practice. For efficient work safety, knowledge of the national legislation is implicit
Assessing maximum loads when skidding wood uphill with tractors
No full textThe results of measuring maximum loads on different slopes when skidding uphill with WOO DY 110 cable skidder and adapted 4WD agricultural tractor AGT 835 are described in the article. Both tractors are very different and were chosen for the purpose of finding the limits of uphill skidding. Besides the slope, the pre-designated loads of different sizes and log orientation (butt-end or top-end forward) have been main variables. The trial was conducted on two concave shaped test skid trails in the forest. On the lower altitudes, the skid trails had small inclination, which slowly increased to 42% on the track where WOODY 110 was tested, and 27% where AGT 835 was measured. First the loads were skidded uphill with butt-end and then with top-end forward. The purpose was to choose too heavy loads, as we wished to stop tractors due to overload, but on different slopes. The proper load formation (butt-end forward if possible) in uphill skidding is most important on steeper skid trails. The dependency between maximum load and slope is linear. The calculated theoretical maximum load on horizontal surface enables us to make similar assessment for any other tractor weighing between 2 and 7 tons. For this purpose, John Deere 6220 and LIMB 80 LUXS adapted agricultural tractors for forest use were chosen and compared. The ratio between the tractor load on different slopes and tractor weight was calculated for all four tractors included in our comparison. Apart from the weight, tractor's engine torque (power) has the decisive influence on the load size. Maximum loads on different slope categories were calculated according to different engine powers
Comparison of standard procedures for estimation of biocides leaching from impregnated wood
No full textLeaching of active ingredients from impregnated wood is one of the most frequently applied criteria for assessing the suitability of impregnated wood to be used in outdoor applications. For this purposes, several standard and nonstandard procedures are applied. Within the framework of this research, leaching of copper and boron compounds from wood, impregnated with four different wood preservatives, were compared: (a) aqueous solution of copper sulphate, (b) commercial copper-ethanolamine based solution Silvanolin, (c) aqueous solution of boric acid and, (d) combination of boric acid and montanic wax emulsion. Pressure impregnated specimens were afterwards leached according to the three different standards: SIST EN 84, SIST EN 1250 and OECD recommendation. The highest portion of leached biocides were determined according to the SIST EN 84 procedure, the lowest portion according to OECD recommendation. All three methods applied, however give us the same ranking of wood preservatives regarding the amount of emitted active ingredients
